1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 494ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 506fceef393SAl Viro struct inode *link_inode; 5079883d185SAl Viro unsigned root_seq; 5089883d185SAl Viro int dfd; 5093859a271SKees Cook } __randomize_layout; 5101f55a6ecSAl Viro 5119883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 512894bc8c4SAl Viro { 513756daf26SNeilBrown struct nameidata *old = current->nameidata; 514756daf26SNeilBrown p->stack = p->internal; 515c8a53ee5SAl Viro p->dfd = dfd; 516c8a53ee5SAl Viro p->name = name; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5189883d185SAl Viro p->saved = old; 519756daf26SNeilBrown current->nameidata = p; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 5229883d185SAl Viro static void restore_nameidata(void) 523894bc8c4SAl Viro { 5249883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529e1a63bbcSAl Viro if (now->stack != now->internal) 530756daf26SNeilBrown kfree(now->stack); 531894bc8c4SAl Viro } 532894bc8c4SAl Viro 533894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 534894bc8c4SAl Viro { 535bc40aee0SAl Viro struct saved *p; 536bc40aee0SAl Viro 537bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5386da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 539bc40aee0SAl Viro GFP_ATOMIC); 540bc40aee0SAl Viro if (unlikely(!p)) 541bc40aee0SAl Viro return -ECHILD; 542bc40aee0SAl Viro } else { 5436da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 544894bc8c4SAl Viro GFP_KERNEL); 545894bc8c4SAl Viro if (unlikely(!p)) 546894bc8c4SAl Viro return -ENOMEM; 547bc40aee0SAl Viro } 548894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 549894bc8c4SAl Viro nd->stack = p; 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro } 552894bc8c4SAl Viro 553397d425dSEric W. Biederman /** 554397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 555397d425dSEric W. Biederman * @path: nameidate to verify 556397d425dSEric W. Biederman * 557397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 558397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 559397d425dSEric W. Biederman */ 560397d425dSEric W. Biederman static bool path_connected(const struct path *path) 561397d425dSEric W. Biederman { 562397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 56395dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 564397d425dSEric W. Biederman 56595dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56695dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 567397d425dSEric W. Biederman return true; 568397d425dSEric W. Biederman 569397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 570397d425dSEric W. Biederman } 571397d425dSEric W. Biederman 572894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 573894bc8c4SAl Viro { 574da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 575894bc8c4SAl Viro return 0; 576894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 577894bc8c4SAl Viro return 0; 578894bc8c4SAl Viro return __nd_alloc_stack(nd); 579894bc8c4SAl Viro } 580894bc8c4SAl Viro 5817973387aSAl Viro static void drop_links(struct nameidata *nd) 5827973387aSAl Viro { 5837973387aSAl Viro int i = nd->depth; 5847973387aSAl Viro while (i--) { 5857973387aSAl Viro struct saved *last = nd->stack + i; 586fceef393SAl Viro do_delayed_call(&last->done); 587fceef393SAl Viro clear_delayed_call(&last->done); 5887973387aSAl Viro } 5897973387aSAl Viro } 5907973387aSAl Viro 5917973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5927973387aSAl Viro { 5937973387aSAl Viro drop_links(nd); 5947973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5957973387aSAl Viro int i; 5967973387aSAl Viro path_put(&nd->path); 5977973387aSAl Viro for (i = 0; i < nd->depth; i++) 5987973387aSAl Viro path_put(&nd->stack[i].link); 59984a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 600102b8af2SAl Viro path_put(&nd->root); 60184a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 602102b8af2SAl Viro } 6037973387aSAl Viro } else { 6047973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6057973387aSAl Viro rcu_read_unlock(); 6067973387aSAl Viro } 6077973387aSAl Viro nd->depth = 0; 6087973387aSAl Viro } 6097973387aSAl Viro 6107973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6117973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6127973387aSAl Viro struct path *path, unsigned seq) 6137973387aSAl Viro { 6147973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6157973387aSAl Viro if (unlikely(res)) { 6167973387aSAl Viro if (res > 0) 6177973387aSAl Viro path->mnt = NULL; 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6227973387aSAl Viro path->dentry = NULL; 6237973387aSAl Viro return false; 6247973387aSAl Viro } 6257973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6267973387aSAl Viro } 6277973387aSAl Viro 6287973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6297973387aSAl Viro { 6307973387aSAl Viro int i; 6317973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6327973387aSAl Viro struct saved *last = nd->stack + i; 6337973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6347973387aSAl Viro drop_links(nd); 6357973387aSAl Viro nd->depth = i + 1; 6367973387aSAl Viro return false; 6377973387aSAl Viro } 6387973387aSAl Viro } 6397973387aSAl Viro return true; 6407973387aSAl Viro } 6417973387aSAl Viro 642ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 643ee594bffSAl Viro { 644adb21d2bSAleksa Sarai /* 645adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 646adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 647adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 648adb21d2bSAleksa Sarai */ 649adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 650adb21d2bSAleksa Sarai return false; 651adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 652ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 653ee594bffSAl Viro return true; 65484a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 655ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 656ee594bffSAl Viro } 657ee594bffSAl Viro 65819660af7SAl Viro /* 65931e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66019660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66119660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66257e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66319660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66419660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66519660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66619660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66731e6b01fSNick Piggin */ 66831e6b01fSNick Piggin 66931e6b01fSNick Piggin /** 67019660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67119660af7SAl Viro * @nd: nameidata pathwalk data 67239191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67331e6b01fSNick Piggin * 6744675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6754675ac39SAl Viro * for ref-walk mode. 6764675ac39SAl Viro * Must be called from rcu-walk context. 6777973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6787973387aSAl Viro * terminate_walk(). 67931e6b01fSNick Piggin */ 6804675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 68131e6b01fSNick Piggin { 68231e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68331e6b01fSNick Piggin 68431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 685e5c832d5SLinus Torvalds 686e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6877973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6884675ac39SAl Viro goto out1; 68984a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 69084a2bd39SAl Viro goto out; 691ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6924675ac39SAl Viro goto out; 6934675ac39SAl Viro rcu_read_unlock(); 6944675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6954675ac39SAl Viro return 0; 6964675ac39SAl Viro 69784a2bd39SAl Viro out1: 6984675ac39SAl Viro nd->path.mnt = NULL; 6994675ac39SAl Viro nd->path.dentry = NULL; 7004675ac39SAl Viro out: 7014675ac39SAl Viro rcu_read_unlock(); 7024675ac39SAl Viro return -ECHILD; 7034675ac39SAl Viro } 7044675ac39SAl Viro 7054675ac39SAl Viro /** 7064675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7074675ac39SAl Viro * @nd: nameidata pathwalk data 7084675ac39SAl Viro * @dentry: child of nd->path.dentry 7094675ac39SAl Viro * @seq: seq number to check dentry against 7104675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7114675ac39SAl Viro * 7124675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7134675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7144675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7154675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7164675ac39SAl Viro * terminate_walk(). 7174675ac39SAl Viro */ 7184675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7194675ac39SAl Viro { 7204675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7214675ac39SAl Viro 7224675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7234675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7244675ac39SAl Viro goto out2; 7257973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7267973387aSAl Viro goto out2; 7274675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7287973387aSAl Viro goto out1; 72948a066e7SAl Viro 73015570086SLinus Torvalds /* 7314675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7324675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7334675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7344675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7354675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73615570086SLinus Torvalds */ 7374675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 738e5c832d5SLinus Torvalds goto out; 73984a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 74084a2bd39SAl Viro goto out_dput; 741e5c832d5SLinus Torvalds /* 742e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 743e5c832d5SLinus Torvalds * still valid and get it if required. 744e5c832d5SLinus Torvalds */ 74584a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74684a2bd39SAl Viro goto out_dput; 7478b61e74fSAl Viro rcu_read_unlock(); 74831e6b01fSNick Piggin return 0; 74919660af7SAl Viro 7507973387aSAl Viro out2: 7517973387aSAl Viro nd->path.mnt = NULL; 7527973387aSAl Viro out1: 7537973387aSAl Viro nd->path.dentry = NULL; 754e5c832d5SLinus Torvalds out: 7558b61e74fSAl Viro rcu_read_unlock(); 75684a2bd39SAl Viro return -ECHILD; 75784a2bd39SAl Viro out_dput: 75884a2bd39SAl Viro rcu_read_unlock(); 75984a2bd39SAl Viro dput(dentry); 76031e6b01fSNick Piggin return -ECHILD; 76131e6b01fSNick Piggin } 76231e6b01fSNick Piggin 7634ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76434286d66SNick Piggin { 765a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7664ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 767a89f8337SAl Viro else 768a89f8337SAl Viro return 1; 76934286d66SNick Piggin } 77034286d66SNick Piggin 7719f1fafeeSAl Viro /** 7729f1fafeeSAl Viro * complete_walk - successful completion of path walk 7739f1fafeeSAl Viro * @nd: pointer nameidata 77439159de2SJeff Layton * 7759f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7769f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7779f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7789f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7799f1fafeeSAl Viro * need to drop nd->path. 78039159de2SJeff Layton */ 7819f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78239159de2SJeff Layton { 78316c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78439159de2SJeff Layton int status; 78539159de2SJeff Layton 7869f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 787adb21d2bSAleksa Sarai /* 788adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 789adb21d2bSAleksa Sarai * externally-managed nd->root. 790adb21d2bSAleksa Sarai */ 791adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7929f1fafeeSAl Viro nd->root.mnt = NULL; 7934675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79448a066e7SAl Viro return -ECHILD; 79548a066e7SAl Viro } 7969f1fafeeSAl Viro 797adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 798adb21d2bSAleksa Sarai /* 799adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 800adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 801adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 802adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 803adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 804adb21d2bSAleksa Sarai * 805adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 806adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 807adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 808adb21d2bSAleksa Sarai * requested root to userspace. 809adb21d2bSAleksa Sarai * 810adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 811adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 812adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 813adb21d2bSAleksa Sarai */ 814adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 815adb21d2bSAleksa Sarai return -EXDEV; 816adb21d2bSAleksa Sarai } 817adb21d2bSAleksa Sarai 81816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 81939159de2SJeff Layton return 0; 82039159de2SJeff Layton 821ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 82216c2cd71SAl Viro return 0; 82316c2cd71SAl Viro 824ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82539159de2SJeff Layton if (status > 0) 82639159de2SJeff Layton return 0; 82739159de2SJeff Layton 82816c2cd71SAl Viro if (!status) 82939159de2SJeff Layton status = -ESTALE; 83016c2cd71SAl Viro 83139159de2SJeff Layton return status; 83239159de2SJeff Layton } 83339159de2SJeff Layton 834740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8352a737871SAl Viro { 83631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8379e6697e2SAl Viro 838adb21d2bSAleksa Sarai /* 839adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 840adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 841adb21d2bSAleksa Sarai * from the dirfd. 842adb21d2bSAleksa Sarai */ 843adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 844adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 845adb21d2bSAleksa Sarai 8469e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8478f47a016SAl Viro unsigned seq; 848c28cc364SNick Piggin 849c28cc364SNick Piggin do { 850c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 85131e6b01fSNick Piggin nd->root = fs->root; 8528f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 853c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8549e6697e2SAl Viro } else { 8559e6697e2SAl Viro get_fs_root(fs, &nd->root); 85684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8579e6697e2SAl Viro } 858740a1678SAleksa Sarai return 0; 85931e6b01fSNick Piggin } 86031e6b01fSNick Piggin 8611d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 862051d3812SIan Kent { 863051d3812SIan Kent dput(path->dentry); 8644ac91378SJan Blunck if (path->mnt != nd->path.mnt) 865051d3812SIan Kent mntput(path->mnt); 866051d3812SIan Kent } 867051d3812SIan Kent 8687b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8697b9337aaSNick Piggin struct nameidata *nd) 870051d3812SIan Kent { 87131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8724ac91378SJan Blunck dput(nd->path.dentry); 87331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8744ac91378SJan Blunck mntput(nd->path.mnt); 8759a229683SHuang Shijie } 87631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8774ac91378SJan Blunck nd->path.dentry = path->dentry; 878051d3812SIan Kent } 879051d3812SIan Kent 880248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 881248fb5b9SAl Viro { 882adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 883adb21d2bSAleksa Sarai return -EXDEV; 88472ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 88572ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 88672ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 88772ba2929SAleksa Sarai return -EXDEV; 88872ba2929SAleksa Sarai } 889740a1678SAleksa Sarai if (!nd->root.mnt) { 890740a1678SAleksa Sarai int error = set_root(nd); 891740a1678SAleksa Sarai if (error) 892740a1678SAleksa Sarai return error; 893740a1678SAleksa Sarai } 894248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 895248fb5b9SAl Viro struct dentry *d; 896248fb5b9SAl Viro nd->path = nd->root; 897248fb5b9SAl Viro d = nd->path.dentry; 898248fb5b9SAl Viro nd->inode = d->d_inode; 899248fb5b9SAl Viro nd->seq = nd->root_seq; 900248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 901248fb5b9SAl Viro return -ECHILD; 902248fb5b9SAl Viro } else { 903248fb5b9SAl Viro path_put(&nd->path); 904248fb5b9SAl Viro nd->path = nd->root; 905248fb5b9SAl Viro path_get(&nd->path); 906248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 907248fb5b9SAl Viro } 908248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 909248fb5b9SAl Viro return 0; 910248fb5b9SAl Viro } 911248fb5b9SAl Viro 912b5fb63c1SChristoph Hellwig /* 9136b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 914b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 915b5fb63c1SChristoph Hellwig */ 9161bc82070SAleksa Sarai int nd_jump_link(struct path *path) 917b5fb63c1SChristoph Hellwig { 9184b99d499SAleksa Sarai int error = -ELOOP; 9196e77137bSAl Viro struct nameidata *nd = current->nameidata; 920b5fb63c1SChristoph Hellwig 9214b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9224b99d499SAleksa Sarai goto err; 9234b99d499SAleksa Sarai 92472ba2929SAleksa Sarai error = -EXDEV; 92572ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 92672ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 92772ba2929SAleksa Sarai goto err; 92872ba2929SAleksa Sarai } 929adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 930adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 931adb21d2bSAleksa Sarai goto err; 93272ba2929SAleksa Sarai 9334b99d499SAleksa Sarai path_put(&nd->path); 934b5fb63c1SChristoph Hellwig nd->path = *path; 935b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 936b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9371bc82070SAleksa Sarai return 0; 9384b99d499SAleksa Sarai 9394b99d499SAleksa Sarai err: 9404b99d499SAleksa Sarai path_put(path); 9414b99d499SAleksa Sarai return error; 942b5fb63c1SChristoph Hellwig } 943b5fb63c1SChristoph Hellwig 944b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 945574197e0SAl Viro { 94621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 947fceef393SAl Viro do_delayed_call(&last->done); 9486548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 949b9ff4429SAl Viro path_put(&last->link); 950574197e0SAl Viro } 951574197e0SAl Viro 952561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 953561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 95430aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 95530aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 956800179c9SKees Cook 957800179c9SKees Cook /** 958800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 95955852635SRandy Dunlap * @nd: nameidata pathwalk data 960800179c9SKees Cook * 961800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 962800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 963800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 964800179c9SKees Cook * processes from failing races against path names that may change out 965800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 966800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 967800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 968800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 969800179c9SKees Cook * 970800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 971800179c9SKees Cook */ 972fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 973800179c9SKees Cook { 974800179c9SKees Cook const struct inode *inode; 975800179c9SKees Cook const struct inode *parent; 9762d7f9e2aSSeth Forshee kuid_t puid; 977800179c9SKees Cook 978800179c9SKees Cook if (!sysctl_protected_symlinks) 979800179c9SKees Cook return 0; 980800179c9SKees Cook 981800179c9SKees Cook /* Allowed if owner and follower match. */ 982fceef393SAl Viro inode = nd->link_inode; 98381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 984800179c9SKees Cook return 0; 985800179c9SKees Cook 986800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 987aa65fa35SAl Viro parent = nd->inode; 988800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 989800179c9SKees Cook return 0; 990800179c9SKees Cook 991800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9922d7f9e2aSSeth Forshee puid = parent->i_uid; 9932d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 994800179c9SKees Cook return 0; 995800179c9SKees Cook 99631956502SAl Viro if (nd->flags & LOOKUP_RCU) 99731956502SAl Viro return -ECHILD; 99831956502SAl Viro 999ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 1000245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 1001800179c9SKees Cook return -EACCES; 1002800179c9SKees Cook } 1003800179c9SKees Cook 1004800179c9SKees Cook /** 1005800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 1006800179c9SKees Cook * @inode: the source inode to hardlink from 1007800179c9SKees Cook * 1008800179c9SKees Cook * Return false if at least one of the following conditions: 1009800179c9SKees Cook * - inode is not a regular file 1010800179c9SKees Cook * - inode is setuid 1011800179c9SKees Cook * - inode is setgid and group-exec 1012800179c9SKees Cook * - access failure for read and write 1013800179c9SKees Cook * 1014800179c9SKees Cook * Otherwise returns true. 1015800179c9SKees Cook */ 1016800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1017800179c9SKees Cook { 1018800179c9SKees Cook umode_t mode = inode->i_mode; 1019800179c9SKees Cook 1020800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1021800179c9SKees Cook if (!S_ISREG(mode)) 1022800179c9SKees Cook return false; 1023800179c9SKees Cook 1024800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1025800179c9SKees Cook if (mode & S_ISUID) 1026800179c9SKees Cook return false; 1027800179c9SKees Cook 1028800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1029800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1030800179c9SKees Cook return false; 1031800179c9SKees Cook 1032800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1033800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1034800179c9SKees Cook return false; 1035800179c9SKees Cook 1036800179c9SKees Cook return true; 1037800179c9SKees Cook } 1038800179c9SKees Cook 1039800179c9SKees Cook /** 1040800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1041800179c9SKees Cook * @link: the source to hardlink from 1042800179c9SKees Cook * 1043800179c9SKees Cook * Block hardlink when all of: 1044800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1045800179c9SKees Cook * - fsuid does not match inode 1046800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1047f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1048800179c9SKees Cook * 1049800179c9SKees Cook * Returns 0 if successful, -ve on error. 1050800179c9SKees Cook */ 1051800179c9SKees Cook static int may_linkat(struct path *link) 1052800179c9SKees Cook { 1053593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1054593d1ce8SEric W. Biederman 1055593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1056593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1057593d1ce8SEric W. Biederman return -EOVERFLOW; 1058800179c9SKees Cook 1059800179c9SKees Cook if (!sysctl_protected_hardlinks) 1060800179c9SKees Cook return 0; 1061800179c9SKees Cook 1062800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1063800179c9SKees Cook * otherwise, it must be a safe source. 1064800179c9SKees Cook */ 1065cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1066800179c9SKees Cook return 0; 1067800179c9SKees Cook 1068245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1069800179c9SKees Cook return -EPERM; 1070800179c9SKees Cook } 1071800179c9SKees Cook 107230aba665SSalvatore Mesoraca /** 107330aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 107430aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 107530aba665SSalvatore Mesoraca * exist. 107630aba665SSalvatore Mesoraca * @dir: the sticky parent directory 107730aba665SSalvatore Mesoraca * @inode: the inode of the file to open 107830aba665SSalvatore Mesoraca * 107930aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 108030aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 108130aba665SSalvatore Mesoraca * - the file already exists 108230aba665SSalvatore Mesoraca * - we are in a sticky directory 108330aba665SSalvatore Mesoraca * - we don't own the file 108430aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 108530aba665SSalvatore Mesoraca * - the directory is world writable 108630aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 108730aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 108830aba665SSalvatore Mesoraca * be enough. 108930aba665SSalvatore Mesoraca * 109030aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 109130aba665SSalvatore Mesoraca */ 109230aba665SSalvatore Mesoraca static int may_create_in_sticky(struct dentry * const dir, 109330aba665SSalvatore Mesoraca struct inode * const inode) 109430aba665SSalvatore Mesoraca { 109530aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 109630aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 109730aba665SSalvatore Mesoraca likely(!(dir->d_inode->i_mode & S_ISVTX)) || 109830aba665SSalvatore Mesoraca uid_eq(inode->i_uid, dir->d_inode->i_uid) || 109930aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 110030aba665SSalvatore Mesoraca return 0; 110130aba665SSalvatore Mesoraca 110230aba665SSalvatore Mesoraca if (likely(dir->d_inode->i_mode & 0002) || 110330aba665SSalvatore Mesoraca (dir->d_inode->i_mode & 0020 && 110430aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 110530aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1106245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1107245d7369SKees Cook "sticky_create_fifo" : 1108245d7369SKees Cook "sticky_create_regular"; 1109245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 111030aba665SSalvatore Mesoraca return -EACCES; 111130aba665SSalvatore Mesoraca } 111230aba665SSalvatore Mesoraca return 0; 111330aba665SSalvatore Mesoraca } 111430aba665SSalvatore Mesoraca 11153b2e7f75SAl Viro static __always_inline 11163b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 11171da177e4SLinus Torvalds { 1118ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 11191cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1120fceef393SAl Viro struct inode *inode = nd->link_inode; 11216d7b5aaeSAl Viro int error; 11220a959df5SAl Viro const char *res; 11231da177e4SLinus Torvalds 112427812141SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 112527812141SAleksa Sarai return ERR_PTR(-ELOOP); 112627812141SAleksa Sarai 11278fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 11288fa9dd24SNeilBrown touch_atime(&last->link); 11298fa9dd24SNeilBrown cond_resched(); 1130c6718543SMiklos Szeredi } else if (atime_needs_update(&last->link, inode)) { 11314675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 11328fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 11338fa9dd24SNeilBrown touch_atime(&last->link); 11348fa9dd24SNeilBrown } 11358fa9dd24SNeilBrown 1136bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1137bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1138bda0be7aSNeilBrown if (unlikely(error)) 11396920a440SAl Viro return ERR_PTR(error); 114036f3b4f6SAl Viro 114186acdca1SAl Viro nd->last_type = LAST_BIND; 11424c4f7c19SEric Biggers res = READ_ONCE(inode->i_link); 1143d4dee48bSAl Viro if (!res) { 1144fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1145fceef393SAl Viro struct delayed_call *); 1146fceef393SAl Viro get = inode->i_op->get_link; 11478c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1148fceef393SAl Viro res = get(NULL, inode, &last->done); 11496b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 11504675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 11518c1b4566SAl Viro return ERR_PTR(-ECHILD); 1152fceef393SAl Viro res = get(dentry, inode, &last->done); 11538c1b4566SAl Viro } 11546b255391SAl Viro } else { 1155fceef393SAl Viro res = get(dentry, inode, &last->done); 11566b255391SAl Viro } 1157fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1158fab51e8aSAl Viro return res; 11590a959df5SAl Viro } 1160fab51e8aSAl Viro if (*res == '/') { 1161740a1678SAleksa Sarai error = nd_jump_root(nd); 1162740a1678SAleksa Sarai if (unlikely(error)) 1163740a1678SAleksa Sarai return ERR_PTR(error); 1164fab51e8aSAl Viro while (unlikely(*++res == '/')) 1165fab51e8aSAl Viro ; 1166fab51e8aSAl Viro } 1167fab51e8aSAl Viro if (!*res) 1168fab51e8aSAl Viro res = NULL; 11690a959df5SAl Viro return res; 11700a959df5SAl Viro } 11716d7b5aaeSAl Viro 1172f015f126SDavid Howells /* 1173f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1174f015f126SDavid Howells * 1175f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1176f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1177f015f126SDavid Howells * Up is towards /. 1178f015f126SDavid Howells * 1179f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1180f015f126SDavid Howells * root. 1181f015f126SDavid Howells */ 1182bab77ebfSAl Viro int follow_up(struct path *path) 11831da177e4SLinus Torvalds { 11840714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11850714a533SAl Viro struct mount *parent; 11861da177e4SLinus Torvalds struct dentry *mountpoint; 118799b7db7bSNick Piggin 118848a066e7SAl Viro read_seqlock_excl(&mount_lock); 11890714a533SAl Viro parent = mnt->mnt_parent; 11903c0a6163SAl Viro if (parent == mnt) { 119148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11921da177e4SLinus Torvalds return 0; 11931da177e4SLinus Torvalds } 11940714a533SAl Viro mntget(&parent->mnt); 1195a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 119648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1197bab77ebfSAl Viro dput(path->dentry); 1198bab77ebfSAl Viro path->dentry = mountpoint; 1199bab77ebfSAl Viro mntput(path->mnt); 12000714a533SAl Viro path->mnt = &parent->mnt; 12011da177e4SLinus Torvalds return 1; 12021da177e4SLinus Torvalds } 12034d359507SAl Viro EXPORT_SYMBOL(follow_up); 12041da177e4SLinus Torvalds 1205b5c84bf6SNick Piggin /* 12069875cf80SDavid Howells * Perform an automount 12079875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 12089875cf80SDavid Howells * were called with. 12091da177e4SLinus Torvalds */ 1210756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 12119875cf80SDavid Howells bool *need_mntput) 121231e6b01fSNick Piggin { 12139875cf80SDavid Howells struct vfsmount *mnt; 1214ea5b778aSDavid Howells int err; 12159875cf80SDavid Howells 12169875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 12179875cf80SDavid Howells return -EREMOTE; 12189875cf80SDavid Howells 12190ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 12200ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 12210ec26fd0SMiklos Szeredi * the name. 12220ec26fd0SMiklos Szeredi * 12230ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 12245a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 12250ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 12260ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 12270ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 12280ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 12295a30d8a2SDavid Howells */ 1230756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 12315d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 12325d38f049SIan Kent path->dentry->d_inode) 12339875cf80SDavid Howells return -EISDIR; 12340ec26fd0SMiklos Szeredi 1235756daf26SNeilBrown nd->total_link_count++; 1236756daf26SNeilBrown if (nd->total_link_count >= 40) 12379875cf80SDavid Howells return -ELOOP; 12389875cf80SDavid Howells 12399875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 12409875cf80SDavid Howells if (IS_ERR(mnt)) { 12419875cf80SDavid Howells /* 12429875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 12439875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 12449875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 12459875cf80SDavid Howells * 12469875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 12479875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 12489875cf80SDavid Howells * the path is inaccessible and we should say so. 12499875cf80SDavid Howells */ 1250756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 12519875cf80SDavid Howells return -EREMOTE; 12529875cf80SDavid Howells return PTR_ERR(mnt); 125331e6b01fSNick Piggin } 1254ea5b778aSDavid Howells 12559875cf80SDavid Howells if (!mnt) /* mount collision */ 12569875cf80SDavid Howells return 0; 12579875cf80SDavid Howells 12588aef1884SAl Viro if (!*need_mntput) { 12598aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 12608aef1884SAl Viro mntget(path->mnt); 12618aef1884SAl Viro *need_mntput = true; 12628aef1884SAl Viro } 126319a167afSAl Viro err = finish_automount(mnt, path); 1264ea5b778aSDavid Howells 1265ea5b778aSDavid Howells switch (err) { 1266ea5b778aSDavid Howells case -EBUSY: 1267ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 126819a167afSAl Viro return 0; 1269ea5b778aSDavid Howells case 0: 12708aef1884SAl Viro path_put(path); 12719875cf80SDavid Howells path->mnt = mnt; 12729875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 12739875cf80SDavid Howells return 0; 127419a167afSAl Viro default: 127519a167afSAl Viro return err; 12769875cf80SDavid Howells } 127719a167afSAl Viro 1278ea5b778aSDavid Howells } 12799875cf80SDavid Howells 12809875cf80SDavid Howells /* 12819875cf80SDavid Howells * Handle a dentry that is managed in some way. 1282cc53ce53SDavid Howells * - Flagged for transit management (autofs) 12839875cf80SDavid Howells * - Flagged as mountpoint 12849875cf80SDavid Howells * - Flagged as automount point 12859875cf80SDavid Howells * 12869875cf80SDavid Howells * This may only be called in refwalk mode. 1287d41efb52SAl Viro * On success path->dentry is known positive. 12889875cf80SDavid Howells * 12899875cf80SDavid Howells * Serialization is taken care of in namespace.c 12909875cf80SDavid Howells */ 1291756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 12929875cf80SDavid Howells { 12938aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 1294d41efb52SAl Viro unsigned flags; 12959875cf80SDavid Howells bool need_mntput = false; 12968aef1884SAl Viro int ret = 0; 12979875cf80SDavid Howells 12989875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 12999875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 13009875cf80SDavid Howells * the components of that value change under us */ 13012fa6b1e0SAl Viro while (flags = smp_load_acquire(&path->dentry->d_flags), 1302d41efb52SAl Viro unlikely(flags & DCACHE_MANAGED_DENTRY)) { 1303cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1304cc53ce53SDavid Howells * being held. */ 1305d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1306cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1307cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1308fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1309cc53ce53SDavid Howells if (ret < 0) 13108aef1884SAl Viro break; 1311cc53ce53SDavid Howells } 1312cc53ce53SDavid Howells 13139875cf80SDavid Howells /* Transit to a mounted filesystem. */ 1314d41efb52SAl Viro if (flags & DCACHE_MOUNTED) { 13159875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13169875cf80SDavid Howells if (mounted) { 13179875cf80SDavid Howells dput(path->dentry); 13189875cf80SDavid Howells if (need_mntput) 1319463ffb2eSAl Viro mntput(path->mnt); 1320463ffb2eSAl Viro path->mnt = mounted; 1321463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 13229875cf80SDavid Howells need_mntput = true; 13239875cf80SDavid Howells continue; 1324463ffb2eSAl Viro } 1325463ffb2eSAl Viro 13269875cf80SDavid Howells /* Something is mounted on this dentry in another 13279875cf80SDavid Howells * namespace and/or whatever was mounted there in this 132848a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 132948a066e7SAl Viro * get it */ 13301da177e4SLinus Torvalds } 13319875cf80SDavid Howells 13329875cf80SDavid Howells /* Handle an automount point */ 1333d41efb52SAl Viro if (flags & DCACHE_NEED_AUTOMOUNT) { 1334756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 13359875cf80SDavid Howells if (ret < 0) 13368aef1884SAl Viro break; 13379875cf80SDavid Howells continue; 13389875cf80SDavid Howells } 13399875cf80SDavid Howells 13409875cf80SDavid Howells /* We didn't change the current path point */ 13419875cf80SDavid Howells break; 13429875cf80SDavid Howells } 13438aef1884SAl Viro 134472ba2929SAleksa Sarai if (need_mntput) { 134572ba2929SAleksa Sarai if (path->mnt == mnt) 13468aef1884SAl Viro mntput(path->mnt); 134772ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 134872ba2929SAleksa Sarai ret = -EXDEV; 134972ba2929SAleksa Sarai else 13508402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 135172ba2929SAleksa Sarai } 1352d41efb52SAl Viro if (ret == -EISDIR || !ret) 1353d41efb52SAl Viro ret = 1; 1354d41efb52SAl Viro if (ret > 0 && unlikely(d_flags_negative(flags))) 1355d41efb52SAl Viro ret = -ENOENT; 13568402752eSAl Viro if (unlikely(ret < 0)) 13578402752eSAl Viro path_put_conditional(path, nd); 13588402752eSAl Viro return ret; 13591da177e4SLinus Torvalds } 13601da177e4SLinus Torvalds 1361cc53ce53SDavid Howells int follow_down_one(struct path *path) 13621da177e4SLinus Torvalds { 13631da177e4SLinus Torvalds struct vfsmount *mounted; 13641da177e4SLinus Torvalds 13651c755af4SAl Viro mounted = lookup_mnt(path); 13661da177e4SLinus Torvalds if (mounted) { 13679393bd07SAl Viro dput(path->dentry); 13689393bd07SAl Viro mntput(path->mnt); 13699393bd07SAl Viro path->mnt = mounted; 13709393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 13711da177e4SLinus Torvalds return 1; 13721da177e4SLinus Torvalds } 13731da177e4SLinus Torvalds return 0; 13741da177e4SLinus Torvalds } 13754d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 13761da177e4SLinus Torvalds 1377fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 137862a7375eSIan Kent { 1379fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1380fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 138162a7375eSIan Kent } 138262a7375eSIan Kent 13839875cf80SDavid Howells /* 1384287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1385287548e4SAl Viro * we meet a managed dentry that would need blocking. 13869875cf80SDavid Howells */ 13879875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1388254cf582SAl Viro struct inode **inode, unsigned *seqp) 13899875cf80SDavid Howells { 139062a7375eSIan Kent for (;;) { 1391c7105365SAl Viro struct mount *mounted; 139262a7375eSIan Kent /* 139362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 139462a7375eSIan Kent * that wants to block transit. 139562a7375eSIan Kent */ 1396fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1397b8faf035SNeilBrown case -ECHILD: 1398b8faf035SNeilBrown default: 1399ab90911fSDavid Howells return false; 1400b8faf035SNeilBrown case -EISDIR: 1401b8faf035SNeilBrown return true; 1402b8faf035SNeilBrown case 0: 1403b8faf035SNeilBrown break; 1404b8faf035SNeilBrown } 140562a7375eSIan Kent 140662a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1407b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 140862a7375eSIan Kent 1409474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 14109875cf80SDavid Howells if (!mounted) 14119875cf80SDavid Howells break; 141272ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 141372ba2929SAleksa Sarai return false; 1414c7105365SAl Viro path->mnt = &mounted->mnt; 1415c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1416a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1417254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 141859430262SLinus Torvalds /* 141959430262SLinus Torvalds * Update the inode too. We don't need to re-check the 142059430262SLinus Torvalds * dentry sequence number here after this d_inode read, 142159430262SLinus Torvalds * because a mount-point is always pinned. 142259430262SLinus Torvalds */ 142359430262SLinus Torvalds *inode = path->dentry->d_inode; 14249875cf80SDavid Howells } 1425f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1426b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1427287548e4SAl Viro } 1428287548e4SAl Viro 142931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 143031e6b01fSNick Piggin { 14314023bfc9SAl Viro struct inode *inode = nd->inode; 143231e6b01fSNick Piggin 143331e6b01fSNick Piggin while (1) { 1434adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1435adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1436adb21d2bSAleksa Sarai return -ECHILD; 143731e6b01fSNick Piggin break; 1438adb21d2bSAleksa Sarai } 143931e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 144031e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 144131e6b01fSNick Piggin struct dentry *parent = old->d_parent; 144231e6b01fSNick Piggin unsigned seq; 144331e6b01fSNick Piggin 14444023bfc9SAl Viro inode = parent->d_inode; 144531e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1446aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1447aed434adSAl Viro return -ECHILD; 144831e6b01fSNick Piggin nd->path.dentry = parent; 144931e6b01fSNick Piggin nd->seq = seq; 1450397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 14512b98149cSAleksa Sarai return -ECHILD; 145231e6b01fSNick Piggin break; 1453aed434adSAl Viro } else { 1454aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1455aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1456aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1457aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1458aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1459aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1460aed434adSAl Viro return -ECHILD; 1461aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 146231e6b01fSNick Piggin break; 146372ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 146472ba2929SAleksa Sarai return -ECHILD; 1465aed434adSAl Viro /* we know that mountpoint was pinned */ 1466aed434adSAl Viro nd->path.dentry = mountpoint; 1467aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1468aed434adSAl Viro inode = inode2; 1469aed434adSAl Viro nd->seq = seq; 147031e6b01fSNick Piggin } 1471aed434adSAl Viro } 1472aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1473b37199e6SAl Viro struct mount *mounted; 1474b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1475aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1476aed434adSAl Viro return -ECHILD; 1477b37199e6SAl Viro if (!mounted) 1478b37199e6SAl Viro break; 147972ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 148072ba2929SAleksa Sarai return -ECHILD; 1481b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1482b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 14834023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1484b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1485b37199e6SAl Viro } 14864023bfc9SAl Viro nd->inode = inode; 148731e6b01fSNick Piggin return 0; 148831e6b01fSNick Piggin } 148931e6b01fSNick Piggin 14909875cf80SDavid Howells /* 1491cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1492cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1493cc53ce53SDavid Howells * caller is permitted to proceed or not. 1494cc53ce53SDavid Howells */ 14957cc90cc3SAl Viro int follow_down(struct path *path) 1496cc53ce53SDavid Howells { 1497cc53ce53SDavid Howells unsigned managed; 1498cc53ce53SDavid Howells int ret; 1499cc53ce53SDavid Howells 15006aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1501cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1502cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1503cc53ce53SDavid Howells * being held. 1504cc53ce53SDavid Howells * 1505cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1506cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1507cc53ce53SDavid Howells * other than its daemon the right to mount on its 1508cc53ce53SDavid Howells * superstructure. 1509cc53ce53SDavid Howells * 1510cc53ce53SDavid Howells * The filesystem may sleep at this point. 1511cc53ce53SDavid Howells */ 1512cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1513cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1514cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1515fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1516cc53ce53SDavid Howells if (ret < 0) 1517cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1518cc53ce53SDavid Howells } 1519cc53ce53SDavid Howells 1520cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1521cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1522cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1523cc53ce53SDavid Howells if (!mounted) 1524cc53ce53SDavid Howells break; 1525cc53ce53SDavid Howells dput(path->dentry); 1526cc53ce53SDavid Howells mntput(path->mnt); 1527cc53ce53SDavid Howells path->mnt = mounted; 1528cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1529cc53ce53SDavid Howells continue; 1530cc53ce53SDavid Howells } 1531cc53ce53SDavid Howells 1532cc53ce53SDavid Howells /* Don't handle automount points here */ 1533cc53ce53SDavid Howells break; 1534cc53ce53SDavid Howells } 1535cc53ce53SDavid Howells return 0; 1536cc53ce53SDavid Howells } 15374d359507SAl Viro EXPORT_SYMBOL(follow_down); 1538cc53ce53SDavid Howells 1539cc53ce53SDavid Howells /* 15409875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 15419875cf80SDavid Howells */ 15429875cf80SDavid Howells static void follow_mount(struct path *path) 15439875cf80SDavid Howells { 15449875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 15459875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 15469875cf80SDavid Howells if (!mounted) 15479875cf80SDavid Howells break; 15489875cf80SDavid Howells dput(path->dentry); 15499875cf80SDavid Howells mntput(path->mnt); 15509875cf80SDavid Howells path->mnt = mounted; 15519875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 15529875cf80SDavid Howells } 15539875cf80SDavid Howells } 15549875cf80SDavid Howells 1555eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1556eedf265aSEric W. Biederman { 1557eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1558eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1559eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1560eedf265aSEric W. Biederman dput(old); 1561eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1562eedf265aSEric W. Biederman return -ENOENT; 1563eedf265aSEric W. Biederman return 0; 1564eedf265aSEric W. Biederman } 1565eedf265aSEric W. Biederman 1566397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 15671da177e4SLinus Torvalds { 15681da177e4SLinus Torvalds while (1) { 1569adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1570adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1571adb21d2bSAleksa Sarai return -EXDEV; 15721da177e4SLinus Torvalds break; 1573adb21d2bSAleksa Sarai } 15744ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1575eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1576eedf265aSEric W. Biederman if (ret) 1577eedf265aSEric W. Biederman return ret; 15781da177e4SLinus Torvalds break; 15791da177e4SLinus Torvalds } 15803088dd70SAl Viro if (!follow_up(&nd->path)) 15811da177e4SLinus Torvalds break; 158272ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 158372ba2929SAleksa Sarai return -EXDEV; 15841da177e4SLinus Torvalds } 158579ed0226SAl Viro follow_mount(&nd->path); 158631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1587397d425dSEric W. Biederman return 0; 15881da177e4SLinus Torvalds } 15891da177e4SLinus Torvalds 15901da177e4SLinus Torvalds /* 1591f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1592f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1593baa03890SNick Piggin */ 1594e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1595e3c13928SAl Viro struct dentry *dir, 15966c51e513SAl Viro unsigned int flags) 1597baa03890SNick Piggin { 1598a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1599bad61189SMiklos Szeredi if (dentry) { 1600a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1601bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 160274ff0ffcSAl Viro if (!error) 16035542aa2fSEric W. Biederman d_invalidate(dentry); 1604bad61189SMiklos Szeredi dput(dentry); 160574ff0ffcSAl Viro return ERR_PTR(error); 1606bad61189SMiklos Szeredi } 1607bad61189SMiklos Szeredi } 1608baa03890SNick Piggin return dentry; 1609baa03890SNick Piggin } 1610baa03890SNick Piggin 1611baa03890SNick Piggin /* 1612a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1613a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1614a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1615a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1616a03ece5fSAl Viro * at all. 161744396f4bSJosef Bacik */ 1618a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1619a03ece5fSAl Viro struct dentry *base, unsigned int flags) 162044396f4bSJosef Bacik { 1621a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 162244396f4bSJosef Bacik struct dentry *old; 1623a03ece5fSAl Viro struct inode *dir = base->d_inode; 1624a03ece5fSAl Viro 1625a03ece5fSAl Viro if (dentry) 1626a03ece5fSAl Viro return dentry; 162744396f4bSJosef Bacik 162844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1629a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 163044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1631a03ece5fSAl Viro 1632a03ece5fSAl Viro dentry = d_alloc(base, name); 1633a03ece5fSAl Viro if (unlikely(!dentry)) 1634a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 163544396f4bSJosef Bacik 163672bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 163744396f4bSJosef Bacik if (unlikely(old)) { 163844396f4bSJosef Bacik dput(dentry); 163944396f4bSJosef Bacik dentry = old; 164044396f4bSJosef Bacik } 164144396f4bSJosef Bacik return dentry; 164244396f4bSJosef Bacik } 164344396f4bSJosef Bacik 1644e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1645254cf582SAl Viro struct path *path, struct inode **inode, 1646254cf582SAl Viro unsigned *seqp) 16471da177e4SLinus Torvalds { 16484ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 164931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 16505a18fff2SAl Viro int status = 1; 16519875cf80SDavid Howells int err; 16529875cf80SDavid Howells 16533cac260aSAl Viro /* 1654b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 16555d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 16565d0f49c1SAl Viro * going to fall back to non-racy lookup. 1657b04f784eSNick Piggin */ 165831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 165931e6b01fSNick Piggin unsigned seq; 1660766c4cbfSAl Viro bool negative; 1661da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 16625d0f49c1SAl Viro if (unlikely(!dentry)) { 16634675ac39SAl Viro if (unlazy_walk(nd)) 16645d0f49c1SAl Viro return -ECHILD; 1665e9742b53SAl Viro return 0; 16665d0f49c1SAl Viro } 16675a18fff2SAl Viro 166812f8ad4bSLinus Torvalds /* 166912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 167012f8ad4bSLinus Torvalds * the dentry name information from lookup. 167112f8ad4bSLinus Torvalds */ 167263afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1673766c4cbfSAl Viro negative = d_is_negative(dentry); 16745d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 167512f8ad4bSLinus Torvalds return -ECHILD; 167612f8ad4bSLinus Torvalds 167712f8ad4bSLinus Torvalds /* 167812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 167912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 168012f8ad4bSLinus Torvalds * 168112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 168212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 168312f8ad4bSLinus Torvalds */ 16845d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 168531e6b01fSNick Piggin return -ECHILD; 16865a18fff2SAl Viro 1687254cf582SAl Viro *seqp = seq; 16884ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1689209a7fb2SAl Viro if (likely(status > 0)) { 1690daf3761cSTrond Myklebust /* 1691daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1692daf3761cSTrond Myklebust * case that drops it. 1693daf3761cSTrond Myklebust */ 16945d0f49c1SAl Viro if (unlikely(negative)) 1695daf3761cSTrond Myklebust return -ENOENT; 169631e6b01fSNick Piggin path->mnt = mnt; 169731e6b01fSNick Piggin path->dentry = dentry; 1698254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1699e9742b53SAl Viro return 1; 17005d0f49c1SAl Viro } 17014675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1702254cf582SAl Viro return -ECHILD; 1703209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1704209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1705209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 17065a18fff2SAl Viro } else { 1707e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 170881e6f520SAl Viro if (unlikely(!dentry)) 1709e9742b53SAl Viro return 0; 17104ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 17115d0f49c1SAl Viro } 17125a18fff2SAl Viro if (unlikely(status <= 0)) { 1713e9742b53SAl Viro if (!status) 17145d0f49c1SAl Viro d_invalidate(dentry); 17155a18fff2SAl Viro dput(dentry); 17165a18fff2SAl Viro return status; 17175a18fff2SAl Viro } 17185d0f49c1SAl Viro 17191da177e4SLinus Torvalds path->mnt = mnt; 17201da177e4SLinus Torvalds path->dentry = dentry; 1721756daf26SNeilBrown err = follow_managed(path, nd); 1722e9742b53SAl Viro if (likely(err > 0)) 172363afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 17248402752eSAl Viro return err; 1725697f514dSMiklos Szeredi } 1726697f514dSMiklos Szeredi 1727697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 172888d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1729e3c13928SAl Viro struct dentry *dir, 1730e3c13928SAl Viro unsigned int flags) 1731697f514dSMiklos Szeredi { 173288d8331aSAl Viro struct dentry *dentry, *old; 17331936386eSAl Viro struct inode *inode = dir->d_inode; 1734d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 17351936386eSAl Viro 17361936386eSAl Viro /* Don't go there if it's already dead */ 173794bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 173888d8331aSAl Viro return ERR_PTR(-ENOENT); 173994bdd655SAl Viro again: 1740d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 174194bdd655SAl Viro if (IS_ERR(dentry)) 174288d8331aSAl Viro return dentry; 174394bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1744a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1745949a852eSAl Viro int error = d_revalidate(dentry, flags); 1746949a852eSAl Viro if (unlikely(error <= 0)) { 174794bdd655SAl Viro if (!error) { 1748949a852eSAl Viro d_invalidate(dentry); 1749949a852eSAl Viro dput(dentry); 175094bdd655SAl Viro goto again; 175194bdd655SAl Viro } 175294bdd655SAl Viro dput(dentry); 1753949a852eSAl Viro dentry = ERR_PTR(error); 1754949a852eSAl Viro } 1755949a852eSAl Viro } 175694bdd655SAl Viro } else { 17571936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 175885c7f810SAl Viro d_lookup_done(dentry); 17591936386eSAl Viro if (unlikely(old)) { 17601936386eSAl Viro dput(dentry); 17611936386eSAl Viro dentry = old; 1762949a852eSAl Viro } 1763949a852eSAl Viro } 1764e3c13928SAl Viro return dentry; 17651da177e4SLinus Torvalds } 17661da177e4SLinus Torvalds 176788d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 176888d8331aSAl Viro struct dentry *dir, 176988d8331aSAl Viro unsigned int flags) 177088d8331aSAl Viro { 177188d8331aSAl Viro struct inode *inode = dir->d_inode; 177288d8331aSAl Viro struct dentry *res; 177388d8331aSAl Viro inode_lock_shared(inode); 177488d8331aSAl Viro res = __lookup_slow(name, dir, flags); 177588d8331aSAl Viro inode_unlock_shared(inode); 177688d8331aSAl Viro return res; 177788d8331aSAl Viro } 177888d8331aSAl Viro 177952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 178052094c8aSAl Viro { 178152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 17824ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 178352094c8aSAl Viro if (err != -ECHILD) 178452094c8aSAl Viro return err; 17854675ac39SAl Viro if (unlazy_walk(nd)) 178652094c8aSAl Viro return -ECHILD; 178752094c8aSAl Viro } 17884ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 178952094c8aSAl Viro } 179052094c8aSAl Viro 17919856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 17929856fa1bSAl Viro { 17939856fa1bSAl Viro if (type == LAST_DOTDOT) { 1794740a1678SAleksa Sarai int error = 0; 1795740a1678SAleksa Sarai 1796740a1678SAleksa Sarai if (!nd->root.mnt) { 1797740a1678SAleksa Sarai error = set_root(nd); 1798740a1678SAleksa Sarai if (error) 1799740a1678SAleksa Sarai return error; 1800740a1678SAleksa Sarai } 1801ab87f9a5SAleksa Sarai if (nd->flags & LOOKUP_RCU) 1802ab87f9a5SAleksa Sarai error = follow_dotdot_rcu(nd); 1803ab87f9a5SAleksa Sarai else 1804ab87f9a5SAleksa Sarai error = follow_dotdot(nd); 1805ab87f9a5SAleksa Sarai if (error) 1806ab87f9a5SAleksa Sarai return error; 1807ab87f9a5SAleksa Sarai 1808ab87f9a5SAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1809ab87f9a5SAleksa Sarai /* 1810ab87f9a5SAleksa Sarai * If there was a racing rename or mount along our 1811ab87f9a5SAleksa Sarai * path, then we can't be sure that ".." hasn't jumped 1812ab87f9a5SAleksa Sarai * above nd->root (and so userspace should retry or use 1813ab87f9a5SAleksa Sarai * some fallback). 1814ab87f9a5SAleksa Sarai */ 1815ab87f9a5SAleksa Sarai smp_rmb(); 1816ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 1817ab87f9a5SAleksa Sarai return -EAGAIN; 1818ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 1819ab87f9a5SAleksa Sarai return -EAGAIN; 1820ab87f9a5SAleksa Sarai } 18219856fa1bSAl Viro } 18229856fa1bSAl Viro return 0; 18239856fa1bSAl Viro } 18249856fa1bSAl Viro 1825181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1826181548c0SAl Viro struct inode *inode, unsigned seq) 1827d63ff28fSAl Viro { 1828626de996SAl Viro int error; 18291cf2665bSAl Viro struct saved *last; 1830756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1831626de996SAl Viro path_to_nameidata(link, nd); 1832626de996SAl Viro return -ELOOP; 1833626de996SAl Viro } 1834bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1835cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1836cd179f44SAl Viro mntget(link->mnt); 18377973387aSAl Viro } 1838626de996SAl Viro error = nd_alloc_stack(nd); 1839626de996SAl Viro if (unlikely(error)) { 1840bc40aee0SAl Viro if (error == -ECHILD) { 1841ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1842ad1633a1SAl Viro drop_links(nd); 1843ad1633a1SAl Viro nd->depth = 0; 1844ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1845ad1633a1SAl Viro nd->path.mnt = NULL; 1846ad1633a1SAl Viro nd->path.dentry = NULL; 1847ad1633a1SAl Viro rcu_read_unlock(); 18484675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1849bc40aee0SAl Viro error = nd_alloc_stack(nd); 1850bc40aee0SAl Viro } 1851bc40aee0SAl Viro if (error) { 1852cd179f44SAl Viro path_put(link); 1853626de996SAl Viro return error; 1854626de996SAl Viro } 1855bc40aee0SAl Viro } 1856626de996SAl Viro 1857ab104923SAl Viro last = nd->stack + nd->depth++; 18581cf2665bSAl Viro last->link = *link; 1859fceef393SAl Viro clear_delayed_call(&last->done); 1860fceef393SAl Viro nd->link_inode = inode; 18610450b2d1SAl Viro last->seq = seq; 1862d63ff28fSAl Viro return 1; 1863d63ff28fSAl Viro } 1864d63ff28fSAl Viro 18658f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 186631d66bcdSAl Viro 18673ddcd056SLinus Torvalds /* 18683ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 18693ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 18703ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 18713ddcd056SLinus Torvalds * for the common case. 18723ddcd056SLinus Torvalds */ 18738f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 18748f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 18753ddcd056SLinus Torvalds { 187631d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 187731d66bcdSAl Viro put_link(nd); 18788f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 18798f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 18808f64fb1cSAl Viro /* not a symlink or should not follow */ 18818f64fb1cSAl Viro path_to_nameidata(path, nd); 18828f64fb1cSAl Viro nd->inode = inode; 18838f64fb1cSAl Viro nd->seq = seq; 1884d63ff28fSAl Viro return 0; 18858f64fb1cSAl Viro } 1886a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1887a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 18888f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1889a7f77542SAl Viro return -ECHILD; 1890a7f77542SAl Viro } 18918f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 18923ddcd056SLinus Torvalds } 18933ddcd056SLinus Torvalds 18944693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1895ce57dfc1SAl Viro { 1896caa85634SAl Viro struct path path; 1897ce57dfc1SAl Viro struct inode *inode; 1898254cf582SAl Viro unsigned seq; 1899ce57dfc1SAl Viro int err; 1900ce57dfc1SAl Viro /* 1901ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1902ce57dfc1SAl Viro * to be able to know about the current root directory and 1903ce57dfc1SAl Viro * parent relationships. 1904ce57dfc1SAl Viro */ 19054693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 19064693a547SAl Viro err = handle_dots(nd, nd->last_type); 19071c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 19084693a547SAl Viro put_link(nd); 19094693a547SAl Viro return err; 19104693a547SAl Viro } 1911254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1912e9742b53SAl Viro if (unlikely(err <= 0)) { 1913697f514dSMiklos Szeredi if (err < 0) 1914f0a9ba70SAl Viro return err; 1915e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1916e3c13928SAl Viro nd->flags); 1917e3c13928SAl Viro if (IS_ERR(path.dentry)) 1918e3c13928SAl Viro return PTR_ERR(path.dentry); 19197500c38aSAl Viro 1920e3c13928SAl Viro path.mnt = nd->path.mnt; 1921e3c13928SAl Viro err = follow_managed(&path, nd); 1922e3c13928SAl Viro if (unlikely(err < 0)) 1923f0a9ba70SAl Viro return err; 1924697f514dSMiklos Szeredi 1925254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1926d4565649SAl Viro inode = d_backing_inode(path.dentry); 1927766c4cbfSAl Viro } 1928697f514dSMiklos Szeredi 19298f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1930ce57dfc1SAl Viro } 1931ce57dfc1SAl Viro 19321da177e4SLinus Torvalds /* 1933bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1934bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1935bfcfaa77SLinus Torvalds * 1936bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1937bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1938bfcfaa77SLinus Torvalds * fast. 1939bfcfaa77SLinus Torvalds * 1940bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1941bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1942bfcfaa77SLinus Torvalds * crossing operation. 1943bfcfaa77SLinus Torvalds * 1944bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1945bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1946bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1947bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1948bfcfaa77SLinus Torvalds */ 1949bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1950bfcfaa77SLinus Torvalds 1951f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1952bfcfaa77SLinus Torvalds 1953468a9428SGeorge Spelvin #ifdef HASH_MIX 1954bfcfaa77SLinus Torvalds 1955468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1956468a9428SGeorge Spelvin 1957468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 19582a18da7aSGeorge Spelvin /* 19592a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 19602a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 19612a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19622a18da7aSGeorge Spelvin * and no temporaries. 19632a18da7aSGeorge Spelvin * 19642a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19652a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19662a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19672a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19682a18da7aSGeorge Spelvin * 19692a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19702a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19712a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19722a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19732a18da7aSGeorge Spelvin * 19742a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19752a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19762a18da7aSGeorge Spelvin * toggling any given output bit. 19772a18da7aSGeorge Spelvin * 19782a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19792a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19802a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19812a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19822a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19832a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19842a18da7aSGeorge Spelvin * Perfect: 8192 258048 19852a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19862a18da7aSGeorge Spelvin */ 19872a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19882a18da7aSGeorge Spelvin ( x ^= (a), \ 19892a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19902a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19912a18da7aSGeorge Spelvin y *= 9 ) 1992bfcfaa77SLinus Torvalds 19930fed3ac8SGeorge Spelvin /* 19942a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19952a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19962a18da7aSGeorge Spelvin * work done before the hash value is used. 19970fed3ac8SGeorge Spelvin */ 19982a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19990fed3ac8SGeorge Spelvin { 20002a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 20012a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 20022a18da7aSGeorge Spelvin return y >> 32; 20030fed3ac8SGeorge Spelvin } 20040fed3ac8SGeorge Spelvin 2005bfcfaa77SLinus Torvalds #else /* 32-bit case */ 2006bfcfaa77SLinus Torvalds 20072a18da7aSGeorge Spelvin /* 20082a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 20092a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 20102a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 20112a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 20122a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 20132a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 20142a18da7aSGeorge Spelvin * Perfect: 2048 31744 20152a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 20162a18da7aSGeorge Spelvin */ 20172a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 20182a18da7aSGeorge Spelvin ( x ^= (a), \ 20192a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 20202a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 20212a18da7aSGeorge Spelvin y *= 9 ) 2022bfcfaa77SLinus Torvalds 20232a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 20240fed3ac8SGeorge Spelvin { 20252a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 20262a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 20270fed3ac8SGeorge Spelvin } 20280fed3ac8SGeorge Spelvin 2029bfcfaa77SLinus Torvalds #endif 2030bfcfaa77SLinus Torvalds 20312a18da7aSGeorge Spelvin /* 20322a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 20332a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 20342a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 20352a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 20362a18da7aSGeorge Spelvin * finds the delimiter after the name. 20372a18da7aSGeorge Spelvin */ 20388387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 2039bfcfaa77SLinus Torvalds { 20408387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 2041bfcfaa77SLinus Torvalds 2042bfcfaa77SLinus Torvalds for (;;) { 2043fcfd2fbfSGeorge Spelvin if (!len) 2044fcfd2fbfSGeorge Spelvin goto done; 2045e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 2046bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2047bfcfaa77SLinus Torvalds break; 20482a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2049bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2050bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2051bfcfaa77SLinus Torvalds } 20522a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2053bfcfaa77SLinus Torvalds done: 20542a18da7aSGeorge Spelvin return fold_hash(x, y); 2055bfcfaa77SLinus Torvalds } 2056bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2057bfcfaa77SLinus Torvalds 2058fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20598387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2060fcfd2fbfSGeorge Spelvin { 20618387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20628387ff25SLinus Torvalds unsigned long adata, mask, len; 2063fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2064fcfd2fbfSGeorge Spelvin 20658387ff25SLinus Torvalds len = 0; 20668387ff25SLinus Torvalds goto inside; 20678387ff25SLinus Torvalds 2068fcfd2fbfSGeorge Spelvin do { 20692a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2070fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20718387ff25SLinus Torvalds inside: 2072fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2073fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2074fcfd2fbfSGeorge Spelvin 2075fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2076fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20772a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2078fcfd2fbfSGeorge Spelvin 20792a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2080fcfd2fbfSGeorge Spelvin } 2081fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2082fcfd2fbfSGeorge Spelvin 2083bfcfaa77SLinus Torvalds /* 2084bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2085d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2086bfcfaa77SLinus Torvalds */ 20878387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2088bfcfaa77SLinus Torvalds { 20898387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20908387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 209136126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2092bfcfaa77SLinus Torvalds 20938387ff25SLinus Torvalds len = 0; 20948387ff25SLinus Torvalds goto inside; 20958387ff25SLinus Torvalds 2096bfcfaa77SLinus Torvalds do { 20972a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2098bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20998387ff25SLinus Torvalds inside: 2100e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 210136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 210236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2103bfcfaa77SLinus Torvalds 210436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 210536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 210636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 21072a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 210836126f8fSLinus Torvalds 21092a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2110bfcfaa77SLinus Torvalds } 2111bfcfaa77SLinus Torvalds 21122a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2113bfcfaa77SLinus Torvalds 2114fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 21158387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 21160145acc2SLinus Torvalds { 21178387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 21180145acc2SLinus Torvalds while (len--) 2119fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 21200145acc2SLinus Torvalds return end_name_hash(hash); 21210145acc2SLinus Torvalds } 2122ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 21230145acc2SLinus Torvalds 2124fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 21258387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2126fcfd2fbfSGeorge Spelvin { 21278387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2128fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2129fcfd2fbfSGeorge Spelvin 2130fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2131e0ab7af9SGeorge Spelvin while (c) { 2132fcfd2fbfSGeorge Spelvin len++; 2133fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2134fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2135e0ab7af9SGeorge Spelvin } 2136fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2137fcfd2fbfSGeorge Spelvin } 2138f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2139fcfd2fbfSGeorge Spelvin 21403ddcd056SLinus Torvalds /* 2141200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2142200e9ef7SLinus Torvalds * one character. 2143200e9ef7SLinus Torvalds */ 21448387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2145200e9ef7SLinus Torvalds { 21468387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2147200e9ef7SLinus Torvalds unsigned long len = 0, c; 2148200e9ef7SLinus Torvalds 2149200e9ef7SLinus Torvalds c = (unsigned char)*name; 2150200e9ef7SLinus Torvalds do { 2151200e9ef7SLinus Torvalds len++; 2152200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2153200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2154200e9ef7SLinus Torvalds } while (c && c != '/'); 2155d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2156200e9ef7SLinus Torvalds } 2157200e9ef7SLinus Torvalds 2158bfcfaa77SLinus Torvalds #endif 2159bfcfaa77SLinus Torvalds 2160200e9ef7SLinus Torvalds /* 21611da177e4SLinus Torvalds * Name resolution. 2162ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2163ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21641da177e4SLinus Torvalds * 2165ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2166ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21671da177e4SLinus Torvalds */ 21686de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21691da177e4SLinus Torvalds { 21701da177e4SLinus Torvalds int err; 21711da177e4SLinus Torvalds 21729b5858e9SAl Viro if (IS_ERR(name)) 21739b5858e9SAl Viro return PTR_ERR(name); 21741da177e4SLinus Torvalds while (*name=='/') 21751da177e4SLinus Torvalds name++; 21761da177e4SLinus Torvalds if (!*name) 21779e18f10aSAl Viro return 0; 21781da177e4SLinus Torvalds 21791da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21801da177e4SLinus Torvalds for(;;) { 2181d6bb3e90SLinus Torvalds u64 hash_len; 2182fe479a58SAl Viro int type; 21831da177e4SLinus Torvalds 218452094c8aSAl Viro err = may_lookup(nd); 21851da177e4SLinus Torvalds if (err) 21863595e234SAl Viro return err; 21871da177e4SLinus Torvalds 21888387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21891da177e4SLinus Torvalds 2190fe479a58SAl Viro type = LAST_NORM; 2191d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2192fe479a58SAl Viro case 2: 2193200e9ef7SLinus Torvalds if (name[1] == '.') { 2194fe479a58SAl Viro type = LAST_DOTDOT; 219516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 219616c2cd71SAl Viro } 2197fe479a58SAl Viro break; 2198fe479a58SAl Viro case 1: 2199fe479a58SAl Viro type = LAST_DOT; 2200fe479a58SAl Viro } 22015a202bcdSAl Viro if (likely(type == LAST_NORM)) { 22025a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 220316c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 22045a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2205a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2206da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 22075a202bcdSAl Viro if (err < 0) 22083595e234SAl Viro return err; 2209d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2210d6bb3e90SLinus Torvalds name = this.name; 22115a202bcdSAl Viro } 22125a202bcdSAl Viro } 2213fe479a58SAl Viro 2214d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2215d6bb3e90SLinus Torvalds nd->last.name = name; 22165f4a6a69SAl Viro nd->last_type = type; 22175f4a6a69SAl Viro 2218d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2219d6bb3e90SLinus Torvalds if (!*name) 2220bdf6cbf1SAl Viro goto OK; 2221200e9ef7SLinus Torvalds /* 2222200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2223200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2224200e9ef7SLinus Torvalds */ 2225200e9ef7SLinus Torvalds do { 2226d6bb3e90SLinus Torvalds name++; 2227d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 22288620c238SAl Viro if (unlikely(!*name)) { 22298620c238SAl Viro OK: 2230368ee9baSAl Viro /* pathname body, done */ 22318620c238SAl Viro if (!nd->depth) 22328620c238SAl Viro return 0; 22338620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2234368ee9baSAl Viro /* trailing symlink, done */ 22358620c238SAl Viro if (!name) 22368620c238SAl Viro return 0; 22378620c238SAl Viro /* last component of nested symlink */ 22388f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 22391c4ff1a8SAl Viro } else { 22401c4ff1a8SAl Viro /* not the last component */ 22418f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 22428620c238SAl Viro } 2243ce57dfc1SAl Viro if (err < 0) 22443595e234SAl Viro return err; 2245fe479a58SAl Viro 2246ce57dfc1SAl Viro if (err) { 2247626de996SAl Viro const char *s = get_link(nd); 22485a460275SAl Viro 2249a1c83681SViresh Kumar if (IS_ERR(s)) 22503595e234SAl Viro return PTR_ERR(s); 2251172a39a0SAl Viro err = 0; 225212b09578SAl Viro if (unlikely(!s)) { 225312b09578SAl Viro /* jumped */ 2254b9ff4429SAl Viro put_link(nd); 225512b09578SAl Viro } else { 2256071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 225732cd7468SAl Viro name = s; 22589e18f10aSAl Viro continue; 225948c8b0c5SAl Viro } 226031e6b01fSNick Piggin } 226197242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 226297242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 22634675ac39SAl Viro if (unlazy_walk(nd)) 226497242f99SAl Viro return -ECHILD; 226597242f99SAl Viro } 22663595e234SAl Viro return -ENOTDIR; 22675f4a6a69SAl Viro } 2268ce57dfc1SAl Viro } 226997242f99SAl Viro } 22701da177e4SLinus Torvalds 2271edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2272c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 227331e6b01fSNick Piggin { 2274740a1678SAleksa Sarai int error; 2275c8a53ee5SAl Viro const char *s = nd->name->name; 227631e6b01fSNick Piggin 2277c0eb027eSLinus Torvalds if (!*s) 2278c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2279edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2280edc2b1daSAl Viro rcu_read_lock(); 2281c0eb027eSLinus Torvalds 228231e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2283980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 228431e6b01fSNick Piggin nd->depth = 0; 2285ab87f9a5SAleksa Sarai 2286ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2287ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2288ab87f9a5SAleksa Sarai smp_rmb(); 2289ab87f9a5SAleksa Sarai 22905b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2291b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2292b18825a7SDavid Howells struct inode *inode = root->d_inode; 229393893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2294368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22955b6ca027SAl Viro nd->path = nd->root; 22965b6ca027SAl Viro nd->inode = inode; 22975b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2298ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22998f47a016SAl Viro nd->root_seq = nd->seq; 23005b6ca027SAl Viro } else { 23015b6ca027SAl Viro path_get(&nd->path); 23025b6ca027SAl Viro } 2303368ee9baSAl Viro return s; 23045b6ca027SAl Viro } 23055b6ca027SAl Viro 230631e6b01fSNick Piggin nd->root.mnt = NULL; 2307248fb5b9SAl Viro nd->path.mnt = NULL; 2308248fb5b9SAl Viro nd->path.dentry = NULL; 230931e6b01fSNick Piggin 23108db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 23118db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2312740a1678SAleksa Sarai error = nd_jump_root(nd); 2313740a1678SAleksa Sarai if (unlikely(error)) 2314740a1678SAleksa Sarai return ERR_PTR(error); 2315ef55d917SAl Viro return s; 23168db52c7eSAleksa Sarai } 23178db52c7eSAleksa Sarai 23188db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 23198db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2320e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 232131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2322c28cc364SNick Piggin unsigned seq; 232331e6b01fSNick Piggin 2324c28cc364SNick Piggin do { 2325c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 232631e6b01fSNick Piggin nd->path = fs->pwd; 2327ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2328c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2329c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2330e41f7d4eSAl Viro } else { 2331e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2332ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2333e41f7d4eSAl Viro } 233431e6b01fSNick Piggin } else { 2335582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2336c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 233731e6b01fSNick Piggin struct dentry *dentry; 233831e6b01fSNick Piggin 23392903ff01SAl Viro if (!f.file) 2340368ee9baSAl Viro return ERR_PTR(-EBADF); 234131e6b01fSNick Piggin 23422903ff01SAl Viro dentry = f.file->f_path.dentry; 234331e6b01fSNick Piggin 2344edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 23452903ff01SAl Viro fdput(f); 2346368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2347f52e0c11SAl Viro } 23482903ff01SAl Viro 23492903ff01SAl Viro nd->path = f.file->f_path; 2350e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 235134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 235234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 23535590ff0dSUlrich Drepper } else { 23542903ff01SAl Viro path_get(&nd->path); 235534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 23561da177e4SLinus Torvalds } 235734a26b99SAl Viro fdput(f); 2358e41f7d4eSAl Viro } 23598db52c7eSAleksa Sarai 2360adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2361adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2362adb21d2bSAleksa Sarai nd->root = nd->path; 2363adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2364adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2365adb21d2bSAleksa Sarai } else { 2366adb21d2bSAleksa Sarai path_get(&nd->root); 2367adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2368adb21d2bSAleksa Sarai } 2369adb21d2bSAleksa Sarai } 2370adb21d2bSAleksa Sarai return s; 23719b4a9b14SAl Viro } 23729b4a9b14SAl Viro 23733bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 237495fa25d9SAl Viro { 237595fa25d9SAl Viro const char *s; 2376fec2fa24SAl Viro int error = may_follow_link(nd); 2377deb106c6SAl Viro if (unlikely(error)) 23783bdba28bSAl Viro return ERR_PTR(error); 237995fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2380fab51e8aSAl Viro nd->stack[0].name = NULL; 23813b2e7f75SAl Viro s = get_link(nd); 2382deb106c6SAl Viro return s ? s : ""; 238395fa25d9SAl Viro } 238495fa25d9SAl Viro 2385caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2386bd92d7feSAl Viro { 2387bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2388bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2389bd92d7feSAl Viro 2390bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 23911c4ff1a8SAl Viro return walk_component(nd, 0); 2392bd92d7feSAl Viro } 2393bd92d7feSAl Viro 23944f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23954f757f3cSAl Viro { 23964f757f3cSAl Viro struct path path = nd->path; 23974f757f3cSAl Viro struct inode *inode = nd->inode; 23984f757f3cSAl Viro unsigned seq = nd->seq; 23994f757f3cSAl Viro int err; 24004f757f3cSAl Viro 24014f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 24024f757f3cSAl Viro /* 24034f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 24044f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 24054f757f3cSAl Viro * if we simply redo everything in non-RCU mode 24064f757f3cSAl Viro */ 24074f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 24084f757f3cSAl Viro return -ECHILD; 24094f757f3cSAl Viro } else { 24104f757f3cSAl Viro dget(path.dentry); 24114f757f3cSAl Viro err = follow_managed(&path, nd); 24124f757f3cSAl Viro if (unlikely(err < 0)) 24134f757f3cSAl Viro return err; 24144f757f3cSAl Viro inode = d_backing_inode(path.dentry); 24154f757f3cSAl Viro seq = 0; 24164f757f3cSAl Viro } 24174f757f3cSAl Viro path_to_nameidata(&path, nd); 24184f757f3cSAl Viro nd->inode = inode; 24194f757f3cSAl Viro nd->seq = seq; 24204f757f3cSAl Viro return 0; 24214f757f3cSAl Viro } 24224f757f3cSAl Viro 24239b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2424c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 24259b4a9b14SAl Viro { 2426c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2427bd92d7feSAl Viro int err; 242831e6b01fSNick Piggin 24299b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 24304f757f3cSAl Viro err = handle_lookup_down(nd); 24315f336e72SAl Viro if (unlikely(err < 0)) 24325f336e72SAl Viro s = ERR_PTR(err); 24334f757f3cSAl Viro } 24344f757f3cSAl Viro 24353bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 24363bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 24373bdba28bSAl Viro s = trailing_symlink(nd); 2438bd92d7feSAl Viro } 24399f1fafeeSAl Viro if (!err) 24409f1fafeeSAl Viro err = complete_walk(nd); 2441bd92d7feSAl Viro 2442deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2443deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2444bd23a539SAl Viro err = -ENOTDIR; 2445625b6d10SAl Viro if (!err) { 2446625b6d10SAl Viro *path = nd->path; 2447625b6d10SAl Viro nd->path.mnt = NULL; 2448625b6d10SAl Viro nd->path.dentry = NULL; 2449625b6d10SAl Viro } 2450deb106c6SAl Viro terminate_walk(nd); 2451bd92d7feSAl Viro return err; 245231e6b01fSNick Piggin } 245331e6b01fSNick Piggin 245431d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 24559ad1aaa6SAl Viro struct path *path, struct path *root) 2456873f1eedSJeff Layton { 2457894bc8c4SAl Viro int retval; 24589883d185SAl Viro struct nameidata nd; 2459abc9f5beSAl Viro if (IS_ERR(name)) 2460abc9f5beSAl Viro return PTR_ERR(name); 24619ad1aaa6SAl Viro if (unlikely(root)) { 24629ad1aaa6SAl Viro nd.root = *root; 24639ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 24649ad1aaa6SAl Viro } 24659883d185SAl Viro set_nameidata(&nd, dfd, name); 2466c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2467873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2468c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2469873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2470c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2471873f1eedSJeff Layton 2472873f1eedSJeff Layton if (likely(!retval)) 2473ff0ebee2SAl Viro audit_inode(name, path->dentry, 0); 24749883d185SAl Viro restore_nameidata(); 2475e4bd1c1aSAl Viro putname(name); 2476873f1eedSJeff Layton return retval; 2477873f1eedSJeff Layton } 2478873f1eedSJeff Layton 24798bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2480c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2481391172c4SAl Viro struct path *parent) 24828bcb77faSAl Viro { 2483c8a53ee5SAl Viro const char *s = path_init(nd, flags); 24849b5858e9SAl Viro int err = link_path_walk(s, nd); 24858bcb77faSAl Viro if (!err) 24868bcb77faSAl Viro err = complete_walk(nd); 2487391172c4SAl Viro if (!err) { 2488391172c4SAl Viro *parent = nd->path; 2489391172c4SAl Viro nd->path.mnt = NULL; 2490391172c4SAl Viro nd->path.dentry = NULL; 2491391172c4SAl Viro } 2492deb106c6SAl Viro terminate_walk(nd); 24938bcb77faSAl Viro return err; 24948bcb77faSAl Viro } 24958bcb77faSAl Viro 24965c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2497391172c4SAl Viro unsigned int flags, struct path *parent, 2498391172c4SAl Viro struct qstr *last, int *type) 24998bcb77faSAl Viro { 25008bcb77faSAl Viro int retval; 25019883d185SAl Viro struct nameidata nd; 25028bcb77faSAl Viro 25035c31b6ceSAl Viro if (IS_ERR(name)) 25045c31b6ceSAl Viro return name; 25059883d185SAl Viro set_nameidata(&nd, dfd, name); 2506c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 25078bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2508c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 25098bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2510c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2511391172c4SAl Viro if (likely(!retval)) { 2512391172c4SAl Viro *last = nd.last; 2513391172c4SAl Viro *type = nd.last_type; 2514c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 25155c31b6ceSAl Viro } else { 25165c31b6ceSAl Viro putname(name); 25175c31b6ceSAl Viro name = ERR_PTR(retval); 2518391172c4SAl Viro } 25199883d185SAl Viro restore_nameidata(); 25205c31b6ceSAl Viro return name; 25218bcb77faSAl Viro } 25228bcb77faSAl Viro 252379714f72SAl Viro /* does lookup, returns the object with parent locked */ 252479714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 25255590ff0dSUlrich Drepper { 25265c31b6ceSAl Viro struct filename *filename; 25275c31b6ceSAl Viro struct dentry *d; 2528391172c4SAl Viro struct qstr last; 2529391172c4SAl Viro int type; 253051689104SPaul Moore 25315c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 25325c31b6ceSAl Viro &last, &type); 253351689104SPaul Moore if (IS_ERR(filename)) 253451689104SPaul Moore return ERR_CAST(filename); 25355c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2536391172c4SAl Viro path_put(path); 25375c31b6ceSAl Viro putname(filename); 25385c31b6ceSAl Viro return ERR_PTR(-EINVAL); 253979714f72SAl Viro } 25405955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2541391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 254279714f72SAl Viro if (IS_ERR(d)) { 25435955102cSAl Viro inode_unlock(path->dentry->d_inode); 2544391172c4SAl Viro path_put(path); 254579714f72SAl Viro } 254651689104SPaul Moore putname(filename); 254779714f72SAl Viro return d; 25485590ff0dSUlrich Drepper } 25495590ff0dSUlrich Drepper 2550d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2551d1811465SAl Viro { 2552abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2553abc9f5beSAl Viro flags, path, NULL); 2554d1811465SAl Viro } 25554d359507SAl Viro EXPORT_SYMBOL(kern_path); 2556d1811465SAl Viro 255716f18200SJosef 'Jeff' Sipek /** 255816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 255916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 256016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 256116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 256216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2563e0a01249SAl Viro * @path: pointer to struct path to fill 256416f18200SJosef 'Jeff' Sipek */ 256516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 256616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2567e0a01249SAl Viro struct path *path) 256816f18200SJosef 'Jeff' Sipek { 25699ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 25709ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2571abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2572abc9f5beSAl Viro flags , path, &root); 257316f18200SJosef 'Jeff' Sipek } 25744d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 257516f18200SJosef 'Jeff' Sipek 25763c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 25773c95f0dcSAl Viro int len, struct qstr *this) 25783c95f0dcSAl Viro { 25793c95f0dcSAl Viro this->name = name; 25803c95f0dcSAl Viro this->len = len; 25813c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 25823c95f0dcSAl Viro if (!len) 25833c95f0dcSAl Viro return -EACCES; 25843c95f0dcSAl Viro 25853c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 25863c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 25873c95f0dcSAl Viro return -EACCES; 25883c95f0dcSAl Viro } 25893c95f0dcSAl Viro 25903c95f0dcSAl Viro while (len--) { 25913c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 25923c95f0dcSAl Viro if (c == '/' || c == '\0') 25933c95f0dcSAl Viro return -EACCES; 25943c95f0dcSAl Viro } 25953c95f0dcSAl Viro /* 25963c95f0dcSAl Viro * See if the low-level filesystem might want 25973c95f0dcSAl Viro * to use its own hash.. 25983c95f0dcSAl Viro */ 25993c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 26003c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 26013c95f0dcSAl Viro if (err < 0) 26023c95f0dcSAl Viro return err; 26033c95f0dcSAl Viro } 26043c95f0dcSAl Viro 26053c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 26063c95f0dcSAl Viro } 26073c95f0dcSAl Viro 2608eead1911SChristoph Hellwig /** 26090da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 26100da0b7fdSDavid Howells * @name: pathname component to lookup 26110da0b7fdSDavid Howells * @base: base directory to lookup from 26120da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 26130da0b7fdSDavid Howells * 26140da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 26150da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 26160da0b7fdSDavid Howells * 26170da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 26180da0b7fdSDavid Howells * not be called by generic code. 26190da0b7fdSDavid Howells * 26200da0b7fdSDavid Howells * The caller must hold base->i_mutex. 26210da0b7fdSDavid Howells */ 26220da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 26230da0b7fdSDavid Howells { 26240da0b7fdSDavid Howells struct qstr this; 26250da0b7fdSDavid Howells int err; 26260da0b7fdSDavid Howells 26270da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 26280da0b7fdSDavid Howells 26290da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 26300da0b7fdSDavid Howells if (err) 26310da0b7fdSDavid Howells return ERR_PTR(err); 26320da0b7fdSDavid Howells 26330da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 26340da0b7fdSDavid Howells } 26350da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 26360da0b7fdSDavid Howells 26370da0b7fdSDavid Howells /** 2638a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2639eead1911SChristoph Hellwig * @name: pathname component to lookup 2640eead1911SChristoph Hellwig * @base: base directory to lookup from 2641eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2642eead1911SChristoph Hellwig * 2643a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 26449e7543e9SAl Viro * not be called by generic code. 2645bbddca8eSNeilBrown * 2646bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2647eead1911SChristoph Hellwig */ 2648057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2649057f6c01SJames Morris { 26508613a209SAl Viro struct dentry *dentry; 2651057f6c01SJames Morris struct qstr this; 2652cda309deSMiklos Szeredi int err; 2653057f6c01SJames Morris 26545955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 26552f9092e1SDavid Woodhouse 26563c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2657cda309deSMiklos Szeredi if (err) 2658cda309deSMiklos Szeredi return ERR_PTR(err); 2659cda309deSMiklos Szeredi 26608613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 26618613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2662057f6c01SJames Morris } 26634d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2664057f6c01SJames Morris 2665bbddca8eSNeilBrown /** 2666bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2667bbddca8eSNeilBrown * @name: pathname component to lookup 2668bbddca8eSNeilBrown * @base: base directory to lookup from 2669bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2670bbddca8eSNeilBrown * 2671bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2672bbddca8eSNeilBrown * not be called by generic code. 2673bbddca8eSNeilBrown * 2674bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2675bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2676bbddca8eSNeilBrown */ 2677bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2678bbddca8eSNeilBrown struct dentry *base, int len) 2679bbddca8eSNeilBrown { 2680bbddca8eSNeilBrown struct qstr this; 2681bbddca8eSNeilBrown int err; 268220d00ee8SLinus Torvalds struct dentry *ret; 2683bbddca8eSNeilBrown 26843c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2685bbddca8eSNeilBrown if (err) 2686bbddca8eSNeilBrown return ERR_PTR(err); 2687bbddca8eSNeilBrown 268820d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 268920d00ee8SLinus Torvalds if (!ret) 269020d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 269120d00ee8SLinus Torvalds return ret; 2692bbddca8eSNeilBrown } 2693bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2694bbddca8eSNeilBrown 26956c2d4798SAl Viro /* 26966c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 26976c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 26986c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 26996c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 27006c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 27016c2d4798SAl Viro * this one avoids such problems. 27026c2d4798SAl Viro */ 27036c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 27046c2d4798SAl Viro struct dentry *base, int len) 27056c2d4798SAl Viro { 27066c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 27072fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 27086c2d4798SAl Viro dput(ret); 27096c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 27106c2d4798SAl Viro } 27116c2d4798SAl Viro return ret; 27126c2d4798SAl Viro } 27136c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 27146c2d4798SAl Viro 2715eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2716eedf265aSEric W. Biederman int path_pts(struct path *path) 2717eedf265aSEric W. Biederman { 2718eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2719eedf265aSEric W. Biederman * the input path. 2720eedf265aSEric W. Biederman */ 2721eedf265aSEric W. Biederman struct dentry *child, *parent; 2722eedf265aSEric W. Biederman struct qstr this; 2723eedf265aSEric W. Biederman int ret; 2724eedf265aSEric W. Biederman 2725eedf265aSEric W. Biederman ret = path_parent_directory(path); 2726eedf265aSEric W. Biederman if (ret) 2727eedf265aSEric W. Biederman return ret; 2728eedf265aSEric W. Biederman 2729eedf265aSEric W. Biederman parent = path->dentry; 2730eedf265aSEric W. Biederman this.name = "pts"; 2731eedf265aSEric W. Biederman this.len = 3; 2732eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2733eedf265aSEric W. Biederman if (!child) 2734eedf265aSEric W. Biederman return -ENOENT; 2735eedf265aSEric W. Biederman 2736eedf265aSEric W. Biederman path->dentry = child; 2737eedf265aSEric W. Biederman dput(parent); 2738eedf265aSEric W. Biederman follow_mount(path); 2739eedf265aSEric W. Biederman return 0; 2740eedf265aSEric W. Biederman } 2741eedf265aSEric W. Biederman #endif 2742eedf265aSEric W. Biederman 27431fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 27441fa1e7f6SAndy Whitcroft struct path *path, int *empty) 27451da177e4SLinus Torvalds { 2746abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2747abc9f5beSAl Viro flags, path, NULL); 27481da177e4SLinus Torvalds } 2749b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 27501fa1e7f6SAndy Whitcroft 27518033426eSJeff Layton /** 2752197df04cSAl Viro * mountpoint_last - look up last component for umount 27538033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 27548033426eSJeff Layton * 27558033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 27568033426eSJeff Layton * need to resolve the path without doing any revalidation. 27578033426eSJeff Layton * 27588033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 27598033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 27608033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 27618033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 27628033426eSJeff Layton * bogus and it doesn't exist. 27638033426eSJeff Layton * 27648033426eSJeff Layton * Returns: 27658033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2766ba8f4613SAl Viro * lookup found a negative dentry. 27678033426eSJeff Layton * 2768ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2769ba8f4613SAl Viro * symlink that needs to be followed. 27708033426eSJeff Layton * 27718033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2772ba8f4613SAl Viro * that needs to be followed. 27738033426eSJeff Layton */ 27748033426eSJeff Layton static int 2775ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 27768033426eSJeff Layton { 27778033426eSJeff Layton int error = 0; 27788033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2779ba8f4613SAl Viro struct path path; 27808033426eSJeff Layton 278135759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 278235759521SAl Viro if (nd->flags & LOOKUP_RCU) { 27834675ac39SAl Viro if (unlazy_walk(nd)) 2784deb106c6SAl Viro return -ECHILD; 27858033426eSJeff Layton } 27868033426eSJeff Layton 27878033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 27888033426eSJeff Layton 27898033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 27908033426eSJeff Layton error = handle_dots(nd, nd->last_type); 279135759521SAl Viro if (error) 2792deb106c6SAl Viro return error; 2793ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2794949a852eSAl Viro } else { 2795ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2796ba8f4613SAl Viro if (!path.dentry) { 27978033426eSJeff Layton /* 2798949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2799949a852eSAl Viro * cache, so that means that this dentry is probably 2800949a852eSAl Viro * a symlink or the path doesn't actually point 2801949a852eSAl Viro * to a mounted dentry. 28028033426eSJeff Layton */ 2803ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2804949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2805ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2806ba8f4613SAl Viro return PTR_ERR(path.dentry); 28078033426eSJeff Layton } 2808bcceeebaSDave Jones } 28092fa6b1e0SAl Viro if (d_flags_negative(smp_load_acquire(&path.dentry->d_flags))) { 2810ba8f4613SAl Viro dput(path.dentry); 2811deb106c6SAl Viro return -ENOENT; 281235759521SAl Viro } 2813ba8f4613SAl Viro path.mnt = nd->path.mnt; 28148f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 28158033426eSJeff Layton } 28168033426eSJeff Layton 28178033426eSJeff Layton /** 2818197df04cSAl Viro * path_mountpoint - look up a path to be umounted 28192a78b857SMasanari Iida * @nd: lookup context 28208033426eSJeff Layton * @flags: lookup flags 2821c8a53ee5SAl Viro * @path: pointer to container for result 28228033426eSJeff Layton * 28238033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2824606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 28258033426eSJeff Layton */ 28268033426eSJeff Layton static int 2827c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 28288033426eSJeff Layton { 2829c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2830368ee9baSAl Viro int err; 28319b5858e9SAl Viro 28323bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2833ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 28343bdba28bSAl Viro s = trailing_symlink(nd); 28353bdba28bSAl Viro } 2836ba8f4613SAl Viro if (!err) { 2837ba8f4613SAl Viro *path = nd->path; 2838ba8f4613SAl Viro nd->path.mnt = NULL; 2839ba8f4613SAl Viro nd->path.dentry = NULL; 2840ba8f4613SAl Viro follow_mount(path); 2841ba8f4613SAl Viro } 2842deb106c6SAl Viro terminate_walk(nd); 28438033426eSJeff Layton return err; 28448033426eSJeff Layton } 28458033426eSJeff Layton 28462d864651SAl Viro static int 2847668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 28482d864651SAl Viro unsigned int flags) 28492d864651SAl Viro { 28509883d185SAl Viro struct nameidata nd; 2851cbaab2dbSAl Viro int error; 2852668696dcSAl Viro if (IS_ERR(name)) 2853668696dcSAl Viro return PTR_ERR(name); 28549883d185SAl Viro set_nameidata(&nd, dfd, name); 2855c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 28562d864651SAl Viro if (unlikely(error == -ECHILD)) 2857c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 28582d864651SAl Viro if (unlikely(error == -ESTALE)) 2859c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 28602d864651SAl Viro if (likely(!error)) 2861c9b07eabSAl Viro audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL); 28629883d185SAl Viro restore_nameidata(); 2863668696dcSAl Viro putname(name); 28642d864651SAl Viro return error; 28652d864651SAl Viro } 28662d864651SAl Viro 28678033426eSJeff Layton /** 2868197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 28698033426eSJeff Layton * @dfd: directory file descriptor 28708033426eSJeff Layton * @name: pathname from userland 28718033426eSJeff Layton * @flags: lookup flags 28728033426eSJeff Layton * @path: pointer to container to hold result 28738033426eSJeff Layton * 28748033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 28758033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 28768033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 28778033426eSJeff Layton * and avoid revalidating the last component. 28788033426eSJeff Layton * 28798033426eSJeff Layton * Returns 0 and populates "path" on success. 28808033426eSJeff Layton */ 28818033426eSJeff Layton int 2882197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 28838033426eSJeff Layton struct path *path) 28848033426eSJeff Layton { 2885cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 28868033426eSJeff Layton } 28878033426eSJeff Layton 28882d864651SAl Viro int 28892d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 28902d864651SAl Viro unsigned int flags) 28912d864651SAl Viro { 2892cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 28932d864651SAl Viro } 28942d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 28952d864651SAl Viro 2896cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 28971da177e4SLinus Torvalds { 28988e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2899da9592edSDavid Howells 29008e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 29011da177e4SLinus Torvalds return 0; 29028e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 29031da177e4SLinus Torvalds return 0; 290423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 29051da177e4SLinus Torvalds } 2906cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 29071da177e4SLinus Torvalds 29081da177e4SLinus Torvalds /* 29091da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 29101da177e4SLinus Torvalds * whether the type of victim is right. 29111da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 29121da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 29131da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 29141da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 29151da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 29161da177e4SLinus Torvalds * a. be owner of dir, or 29171da177e4SLinus Torvalds * b. be owner of victim, or 29181da177e4SLinus Torvalds * c. have CAP_FOWNER capability 29191da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 29201da177e4SLinus Torvalds * links pointing to it. 29210bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 29220bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 29230bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 29240bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 29250bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 29261da177e4SLinus Torvalds * nfs_async_unlink(). 29271da177e4SLinus Torvalds */ 2928b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 29291da177e4SLinus Torvalds { 293063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 29311da177e4SLinus Torvalds int error; 29321da177e4SLinus Torvalds 2933b18825a7SDavid Howells if (d_is_negative(victim)) 29341da177e4SLinus Torvalds return -ENOENT; 2935b18825a7SDavid Howells BUG_ON(!inode); 29361da177e4SLinus Torvalds 29371da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2938593d1ce8SEric W. Biederman 2939593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2940593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2941593d1ce8SEric W. Biederman return -EOVERFLOW; 2942593d1ce8SEric W. Biederman 29434fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 29441da177e4SLinus Torvalds 2945f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 29461da177e4SLinus Torvalds if (error) 29471da177e4SLinus Torvalds return error; 29481da177e4SLinus Torvalds if (IS_APPEND(dir)) 29491da177e4SLinus Torvalds return -EPERM; 2950b18825a7SDavid Howells 2951b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 29520bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 29531da177e4SLinus Torvalds return -EPERM; 29541da177e4SLinus Torvalds if (isdir) { 295544b1d530SMiklos Szeredi if (!d_is_dir(victim)) 29561da177e4SLinus Torvalds return -ENOTDIR; 29571da177e4SLinus Torvalds if (IS_ROOT(victim)) 29581da177e4SLinus Torvalds return -EBUSY; 295944b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 29601da177e4SLinus Torvalds return -EISDIR; 29611da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 29621da177e4SLinus Torvalds return -ENOENT; 29631da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 29641da177e4SLinus Torvalds return -EBUSY; 29651da177e4SLinus Torvalds return 0; 29661da177e4SLinus Torvalds } 29671da177e4SLinus Torvalds 29681da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 29691da177e4SLinus Torvalds * dir. 29701da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 29711da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 29721da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2973036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2974036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2975036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 29761da177e4SLinus Torvalds */ 2977a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 29781da177e4SLinus Torvalds { 2979036d5236SEric W. Biederman struct user_namespace *s_user_ns; 298014e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 29811da177e4SLinus Torvalds if (child->d_inode) 29821da177e4SLinus Torvalds return -EEXIST; 29831da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 29841da177e4SLinus Torvalds return -ENOENT; 2985036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2986036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2987036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2988036d5236SEric W. Biederman return -EOVERFLOW; 2989f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 29901da177e4SLinus Torvalds } 29911da177e4SLinus Torvalds 29921da177e4SLinus Torvalds /* 29931da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 29941da177e4SLinus Torvalds */ 29951da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 29961da177e4SLinus Torvalds { 29971da177e4SLinus Torvalds struct dentry *p; 29981da177e4SLinus Torvalds 29991da177e4SLinus Torvalds if (p1 == p2) { 30005955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30011da177e4SLinus Torvalds return NULL; 30021da177e4SLinus Torvalds } 30031da177e4SLinus Torvalds 3004fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 30051da177e4SLinus Torvalds 3006e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 3007e2761a11SOGAWA Hirofumi if (p) { 30085955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 30095955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 30101da177e4SLinus Torvalds return p; 30111da177e4SLinus Torvalds } 30121da177e4SLinus Torvalds 3013e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 3014e2761a11SOGAWA Hirofumi if (p) { 30155955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30165955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 30171da177e4SLinus Torvalds return p; 30181da177e4SLinus Torvalds } 30191da177e4SLinus Torvalds 30205955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30215955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 30221da177e4SLinus Torvalds return NULL; 30231da177e4SLinus Torvalds } 30244d359507SAl Viro EXPORT_SYMBOL(lock_rename); 30251da177e4SLinus Torvalds 30261da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 30271da177e4SLinus Torvalds { 30285955102cSAl Viro inode_unlock(p1->d_inode); 30291da177e4SLinus Torvalds if (p1 != p2) { 30305955102cSAl Viro inode_unlock(p2->d_inode); 3031fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 30321da177e4SLinus Torvalds } 30331da177e4SLinus Torvalds } 30344d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 30351da177e4SLinus Torvalds 30364acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 3037312b63fbSAl Viro bool want_excl) 30381da177e4SLinus Torvalds { 3039a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 30401da177e4SLinus Torvalds if (error) 30411da177e4SLinus Torvalds return error; 30421da177e4SLinus Torvalds 3043acfa4380SAl Viro if (!dir->i_op->create) 30441da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 30451da177e4SLinus Torvalds mode &= S_IALLUGO; 30461da177e4SLinus Torvalds mode |= S_IFREG; 30471da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 30481da177e4SLinus Torvalds if (error) 30491da177e4SLinus Torvalds return error; 3050312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 3051a74574aaSStephen Smalley if (!error) 3052f38aa942SAmy Griffis fsnotify_create(dir, dentry); 30531da177e4SLinus Torvalds return error; 30541da177e4SLinus Torvalds } 30554d359507SAl Viro EXPORT_SYMBOL(vfs_create); 30561da177e4SLinus Torvalds 30578e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 30588e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 30598e6c848eSAl Viro void *arg) 30608e6c848eSAl Viro { 30618e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 30628e6c848eSAl Viro int error = may_create(dir, dentry); 30638e6c848eSAl Viro if (error) 30648e6c848eSAl Viro return error; 30658e6c848eSAl Viro 30668e6c848eSAl Viro mode &= S_IALLUGO; 30678e6c848eSAl Viro mode |= S_IFREG; 30688e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 30698e6c848eSAl Viro if (error) 30708e6c848eSAl Viro return error; 30718e6c848eSAl Viro error = f(dentry, mode, arg); 30728e6c848eSAl Viro if (!error) 30738e6c848eSAl Viro fsnotify_create(dir, dentry); 30748e6c848eSAl Viro return error; 30758e6c848eSAl Viro } 30768e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 30778e6c848eSAl Viro 3078a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 3079a2982cc9SEric W. Biederman { 3080a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 3081a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 3082a2982cc9SEric W. Biederman } 3083a2982cc9SEric W. Biederman 3084f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 30851da177e4SLinus Torvalds { 30863fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 30871da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 30881da177e4SLinus Torvalds int error; 30891da177e4SLinus Torvalds 30901da177e4SLinus Torvalds if (!inode) 30911da177e4SLinus Torvalds return -ENOENT; 30921da177e4SLinus Torvalds 3093c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 3094c8fe8f30SChristoph Hellwig case S_IFLNK: 30951da177e4SLinus Torvalds return -ELOOP; 3096c8fe8f30SChristoph Hellwig case S_IFDIR: 3097c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 30981da177e4SLinus Torvalds return -EISDIR; 3099c8fe8f30SChristoph Hellwig break; 3100c8fe8f30SChristoph Hellwig case S_IFBLK: 3101c8fe8f30SChristoph Hellwig case S_IFCHR: 3102a2982cc9SEric W. Biederman if (!may_open_dev(path)) 31031da177e4SLinus Torvalds return -EACCES; 3104c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 3105c8fe8f30SChristoph Hellwig case S_IFIFO: 3106c8fe8f30SChristoph Hellwig case S_IFSOCK: 31071da177e4SLinus Torvalds flag &= ~O_TRUNC; 3108c8fe8f30SChristoph Hellwig break; 31094a3fd211SDave Hansen } 3110b41572e9SDave Hansen 311162fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 3112b41572e9SDave Hansen if (error) 3113b41572e9SDave Hansen return error; 31146146f0d5SMimi Zohar 31151da177e4SLinus Torvalds /* 31161da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 31171da177e4SLinus Torvalds */ 31181da177e4SLinus Torvalds if (IS_APPEND(inode)) { 31198737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 31207715b521SAl Viro return -EPERM; 31211da177e4SLinus Torvalds if (flag & O_TRUNC) 31227715b521SAl Viro return -EPERM; 31231da177e4SLinus Torvalds } 31241da177e4SLinus Torvalds 31251da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 31262e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 31277715b521SAl Viro return -EPERM; 31281da177e4SLinus Torvalds 3129f3c7691eSJ. Bruce Fields return 0; 31307715b521SAl Viro } 31317715b521SAl Viro 3132e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 31337715b521SAl Viro { 3134f0bb5aafSAl Viro const struct path *path = &filp->f_path; 31357715b521SAl Viro struct inode *inode = path->dentry->d_inode; 31367715b521SAl Viro int error = get_write_access(inode); 31371da177e4SLinus Torvalds if (error) 31387715b521SAl Viro return error; 31391da177e4SLinus Torvalds /* 31401da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 31411da177e4SLinus Torvalds */ 3142d7a06983SJeff Layton error = locks_verify_locked(filp); 3143be6d3e56SKentaro Takeda if (!error) 3144ea0d3ab2STetsuo Handa error = security_path_truncate(path); 31451da177e4SLinus Torvalds if (!error) { 31467715b521SAl Viro error = do_truncate(path->dentry, 0, 3147d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 3148e1181ee6SJeff Layton filp); 31491da177e4SLinus Torvalds } 31501da177e4SLinus Torvalds put_write_access(inode); 3151acd0c935SMimi Zohar return error; 31521da177e4SLinus Torvalds } 31531da177e4SLinus Torvalds 3154d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 3155d57999e1SDave Hansen { 31568a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 31578a5e929dSAl Viro flag--; 3158d57999e1SDave Hansen return flag; 3159d57999e1SDave Hansen } 3160d57999e1SDave Hansen 3161d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 3162d18e9008SMiklos Szeredi { 31631328c727SSeth Forshee struct user_namespace *s_user_ns; 3164d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 3165d18e9008SMiklos Szeredi if (error) 3166d18e9008SMiklos Szeredi return error; 3167d18e9008SMiklos Szeredi 31681328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 31691328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 31701328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 31711328c727SSeth Forshee return -EOVERFLOW; 31721328c727SSeth Forshee 3173d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 3174d18e9008SMiklos Szeredi if (error) 3175d18e9008SMiklos Szeredi return error; 3176d18e9008SMiklos Szeredi 3177d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3178d18e9008SMiklos Szeredi } 3179d18e9008SMiklos Szeredi 31801acf0af9SDavid Howells /* 31811acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 31821acf0af9SDavid Howells * dentry. 31831acf0af9SDavid Howells * 31841acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 31851acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 31861acf0af9SDavid Howells * 318700a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 318800a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 318900a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 31901acf0af9SDavid Howells * 31911acf0af9SDavid Howells * Returns an error code otherwise. 31921acf0af9SDavid Howells */ 31932675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 319430d90494SAl Viro struct path *path, struct file *file, 3195015c3bbcSMiklos Szeredi const struct open_flags *op, 31963ec2eef1SAl Viro int open_flag, umode_t mode) 3197d18e9008SMiklos Szeredi { 3198d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3199d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3200d18e9008SMiklos Szeredi int error; 3201d18e9008SMiklos Szeredi 3202384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3203d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3204d18e9008SMiklos Szeredi 3205d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3206d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3207d18e9008SMiklos Szeredi 320830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 320930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 32100fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 321144907d79SAl Viro open_to_namei_flags(open_flag), mode); 32126fbd0714SAl Viro d_lookup_done(dentry); 3213384f26e2SAl Viro if (!error) { 321464e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 3215d18e9008SMiklos Szeredi /* 3216384f26e2SAl Viro * We didn't have the inode before the open, so check open 3217384f26e2SAl Viro * permission here. 3218d18e9008SMiklos Szeredi */ 3219384f26e2SAl Viro int acc_mode = op->acc_mode; 322073a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 322103da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 322203da633aSAl Viro fsnotify_create(dir, dentry); 322362fb4a15SAl Viro acc_mode = 0; 322403da633aSAl Viro } 32252675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3226384f26e2SAl Viro if (WARN_ON(error > 0)) 3227384f26e2SAl Viro error = -EINVAL; 322864e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3229d18e9008SMiklos Szeredi error = -EIO; 3230384f26e2SAl Viro } else { 3231d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3232d18e9008SMiklos Szeredi dput(dentry); 3233d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 323410c64ceaSAl Viro } 323573a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3236d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3237a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3238a01e718fSAl Viro error = -ENOENT; 3239a01e718fSAl Viro } else { 3240d18e9008SMiklos Szeredi path->dentry = dentry; 3241d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 324200a07c15SAl Viro return 0; 3243d18e9008SMiklos Szeredi } 3244d18e9008SMiklos Szeredi } 3245a01e718fSAl Viro } 3246d18e9008SMiklos Szeredi dput(dentry); 3247d18e9008SMiklos Szeredi return error; 3248d18e9008SMiklos Szeredi } 3249d18e9008SMiklos Szeredi 325031e6b01fSNick Piggin /* 32511acf0af9SDavid Howells * Look up and maybe create and open the last component. 3252d58ffd35SMiklos Szeredi * 325300a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3254d58ffd35SMiklos Szeredi * 325500a07c15SAl Viro * Returns 0 on success, that is, if 325600a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 325700a07c15SAl Viro * the file was not completely opened at this time, though lookups and 325800a07c15SAl Viro * creations were performed. 325900a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 326000a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 326100a07c15SAl Viro * hadn't been specified. 32621acf0af9SDavid Howells * 326300a07c15SAl Viro * An error code is returned on failure. 3264d58ffd35SMiklos Szeredi */ 32652675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 326630d90494SAl Viro struct file *file, 3267d58ffd35SMiklos Szeredi const struct open_flags *op, 32683ec2eef1SAl Viro bool got_write) 3269d58ffd35SMiklos Szeredi { 3270d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 327154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 32721643b43fSAl Viro int open_flag = op->open_flag; 3273d58ffd35SMiklos Szeredi struct dentry *dentry; 32741643b43fSAl Viro int error, create_error = 0; 32751643b43fSAl Viro umode_t mode = op->mode; 32766fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3277d58ffd35SMiklos Szeredi 3278ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3279ce8644fcSAl Viro return -ENOENT; 3280d58ffd35SMiklos Szeredi 328173a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 32826fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 32836fbd0714SAl Viro for (;;) { 32846fbd0714SAl Viro if (!dentry) { 32856fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3286d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 32872675a4ebSAl Viro return PTR_ERR(dentry); 32886fbd0714SAl Viro } 32896fbd0714SAl Viro if (d_in_lookup(dentry)) 32906fbd0714SAl Viro break; 3291d58ffd35SMiklos Szeredi 32926fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 32936fbd0714SAl Viro if (likely(error > 0)) 32946fbd0714SAl Viro break; 32956fbd0714SAl Viro if (error) 32966fbd0714SAl Viro goto out_dput; 32976fbd0714SAl Viro d_invalidate(dentry); 32986fbd0714SAl Viro dput(dentry); 32996fbd0714SAl Viro dentry = NULL; 33006fbd0714SAl Viro } 33016fbd0714SAl Viro if (dentry->d_inode) { 3302d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3303d18e9008SMiklos Szeredi goto out_no_open; 33046c51e513SAl Viro } 3305d18e9008SMiklos Szeredi 33061643b43fSAl Viro /* 33071643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 33081643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 33091643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 33101643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 33111643b43fSAl Viro * 33121643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 33131643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 33141643b43fSAl Viro */ 33151643b43fSAl Viro if (open_flag & O_CREAT) { 33161643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 33171643b43fSAl Viro mode &= ~current_umask(); 33181643b43fSAl Viro if (unlikely(!got_write)) { 33191643b43fSAl Viro create_error = -EROFS; 33201643b43fSAl Viro open_flag &= ~O_CREAT; 33211643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 33221643b43fSAl Viro goto no_open; 33231643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 33241643b43fSAl Viro } else { 33251643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 33261643b43fSAl Viro if (create_error) { 33271643b43fSAl Viro open_flag &= ~O_CREAT; 33281643b43fSAl Viro if (open_flag & O_EXCL) 33291643b43fSAl Viro goto no_open; 33301643b43fSAl Viro } 33311643b43fSAl Viro } 33321643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 33331643b43fSAl Viro unlikely(!got_write)) { 33341643b43fSAl Viro /* 33351643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 33361643b43fSAl Viro * back to lookup + open 33371643b43fSAl Viro */ 33381643b43fSAl Viro goto no_open; 3339d18e9008SMiklos Szeredi } 3340d18e9008SMiklos Szeredi 33411643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 33421643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 33433ec2eef1SAl Viro mode); 33441643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 33451643b43fSAl Viro error = create_error; 33461643b43fSAl Viro return error; 33471643b43fSAl Viro } 334854ef4872SMiklos Szeredi 33491643b43fSAl Viro no_open: 33506fbd0714SAl Viro if (d_in_lookup(dentry)) { 335112fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 335212fa5e24SAl Viro nd->flags); 33536fbd0714SAl Viro d_lookup_done(dentry); 335412fa5e24SAl Viro if (unlikely(res)) { 335512fa5e24SAl Viro if (IS_ERR(res)) { 335612fa5e24SAl Viro error = PTR_ERR(res); 335712fa5e24SAl Viro goto out_dput; 335812fa5e24SAl Viro } 335912fa5e24SAl Viro dput(dentry); 336012fa5e24SAl Viro dentry = res; 336112fa5e24SAl Viro } 336254ef4872SMiklos Szeredi } 336354ef4872SMiklos Szeredi 3364d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 33651643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 336673a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3367ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3368ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3369ce8644fcSAl Viro error = -EACCES; 3370d58ffd35SMiklos Szeredi goto out_dput; 337164894cf8SAl Viro } 3372ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 33731643b43fSAl Viro open_flag & O_EXCL); 3374d58ffd35SMiklos Szeredi if (error) 3375d58ffd35SMiklos Szeredi goto out_dput; 3376ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3377d58ffd35SMiklos Szeredi } 33781643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 33791643b43fSAl Viro error = create_error; 3380d58ffd35SMiklos Szeredi goto out_dput; 3381d58ffd35SMiklos Szeredi } 3382d18e9008SMiklos Szeredi out_no_open: 3383d58ffd35SMiklos Szeredi path->dentry = dentry; 3384d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 338500a07c15SAl Viro return 0; 3386d58ffd35SMiklos Szeredi 3387d58ffd35SMiklos Szeredi out_dput: 3388d58ffd35SMiklos Szeredi dput(dentry); 33892675a4ebSAl Viro return error; 3390d58ffd35SMiklos Szeredi } 3391d58ffd35SMiklos Szeredi 3392d58ffd35SMiklos Szeredi /* 3393fe2d35ffSAl Viro * Handle the last step of open() 339431e6b01fSNick Piggin */ 3395896475d5SAl Viro static int do_last(struct nameidata *nd, 33963ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3397fb1cc555SAl Viro { 3398a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3399ca344a89SAl Viro int open_flag = op->open_flag; 340077d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 340164894cf8SAl Viro bool got_write = false; 3402bcda7652SAl Viro int acc_mode = op->acc_mode; 3403254cf582SAl Viro unsigned seq; 3404a1eb3315SMiklos Szeredi struct inode *inode; 3405896475d5SAl Viro struct path path; 340616c2cd71SAl Viro int error; 3407fb1cc555SAl Viro 3408c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3409c3e380b0SAl Viro nd->flags |= op->intent; 3410c3e380b0SAl Viro 3411bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3412fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3413deb106c6SAl Viro if (unlikely(error)) 34142675a4ebSAl Viro return error; 3415e83db167SMiklos Szeredi goto finish_open; 34161f36f774SAl Viro } 3417a2c36b45SAl Viro 3418ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3419fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3420fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3421fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3422254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3423e9742b53SAl Viro if (likely(error > 0)) 342471574865SMiklos Szeredi goto finish_lookup; 342571574865SMiklos Szeredi 3426ce57dfc1SAl Viro if (error < 0) 3427deb106c6SAl Viro return error; 3428a1eb3315SMiklos Szeredi 342937d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 34306583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3431b6183df7SMiklos Szeredi } else { 3432fe2d35ffSAl Viro /* create side of things */ 3433a3fbbde7SAl Viro /* 3434b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3435b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3436b6183df7SMiklos Szeredi * about to look up 3437a3fbbde7SAl Viro */ 34389f1fafeeSAl Viro error = complete_walk(nd); 3439e8bb73dfSAl Viro if (error) 34402675a4ebSAl Viro return error; 3441fe2d35ffSAl Viro 3442c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 34431f36f774SAl Viro /* trailing slashes? */ 3444deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3445deb106c6SAl Viro return -EISDIR; 3446b6183df7SMiklos Szeredi } 34471f36f774SAl Viro 34489cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 344964894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 345064894cf8SAl Viro if (!error) 345164894cf8SAl Viro got_write = true; 345264894cf8SAl Viro /* 345364894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 345464894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 345564894cf8SAl Viro * dropping this one anyway. 345664894cf8SAl Viro */ 345764894cf8SAl Viro } 34589cf843e3SAl Viro if (open_flag & O_CREAT) 34595955102cSAl Viro inode_lock(dir->d_inode); 34609cf843e3SAl Viro else 34619cf843e3SAl Viro inode_lock_shared(dir->d_inode); 34623ec2eef1SAl Viro error = lookup_open(nd, &path, file, op, got_write); 34639cf843e3SAl Viro if (open_flag & O_CREAT) 34645955102cSAl Viro inode_unlock(dir->d_inode); 34659cf843e3SAl Viro else 34669cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3467fb1cc555SAl Viro 34682675a4ebSAl Viro if (error) 3469d58ffd35SMiklos Szeredi goto out; 34706c0d46c4SAl Viro 347100a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 347273a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3473496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 347477d660a8SMiklos Szeredi will_truncate = false; 3475d18e9008SMiklos Szeredi 347676ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3477d18e9008SMiklos Szeredi goto opened; 3478d18e9008SMiklos Szeredi } 3479d18e9008SMiklos Szeredi 348073a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 34819b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3482ca344a89SAl Viro open_flag &= ~O_TRUNC; 348377d660a8SMiklos Szeredi will_truncate = false; 348462fb4a15SAl Viro acc_mode = 0; 3485896475d5SAl Viro path_to_nameidata(&path, nd); 3486e83db167SMiklos Szeredi goto finish_open_created; 3487fb1cc555SAl Viro } 3488fb1cc555SAl Viro 3489fb1cc555SAl Viro /* 3490d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3491d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3492d18e9008SMiklos Szeredi * necessary...) 3493d18e9008SMiklos Szeredi */ 349464894cf8SAl Viro if (got_write) { 3495d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 349664894cf8SAl Viro got_write = false; 3497d18e9008SMiklos Szeredi } 3498d18e9008SMiklos Szeredi 3499e6ec03a2SAl Viro error = follow_managed(&path, nd); 3500e6ec03a2SAl Viro if (unlikely(error < 0)) 3501e6ec03a2SAl Viro return error; 3502e6ec03a2SAl Viro 35036583fe22SAl Viro /* 35046583fe22SAl Viro * create/update audit record if it already exists. 35056583fe22SAl Viro */ 35066583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 35076583fe22SAl Viro 3508deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3509deb106c6SAl Viro path_to_nameidata(&path, nd); 3510deb106c6SAl Viro return -EEXIST; 3511deb106c6SAl Viro } 3512fb1cc555SAl Viro 3513254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3514d4565649SAl Viro inode = d_backing_inode(path.dentry); 3515766c4cbfSAl Viro finish_lookup: 35168f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3517deb106c6SAl Viro if (unlikely(error)) 3518d63ff28fSAl Viro return error; 3519bc77daa7SAl Viro finish_open: 35208f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3521a3fbbde7SAl Viro error = complete_walk(nd); 3522fac7d191SAl Viro if (error) 35232675a4ebSAl Viro return error; 352476ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 352530aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3526fb1cc555SAl Viro error = -EISDIR; 352730aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 35282675a4ebSAl Viro goto out; 352930aba665SSalvatore Mesoraca error = may_create_in_sticky(dir, 353030aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 353130aba665SSalvatore Mesoraca if (unlikely(error)) 353230aba665SSalvatore Mesoraca goto out; 353330aba665SSalvatore Mesoraca } 3534af2f5542SMiklos Szeredi error = -ENOTDIR; 353544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 35362675a4ebSAl Viro goto out; 35374bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 353877d660a8SMiklos Szeredi will_truncate = false; 35396c0d46c4SAl Viro 35400f9d1a10SAl Viro if (will_truncate) { 35410f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 35420f9d1a10SAl Viro if (error) 35432675a4ebSAl Viro goto out; 354464894cf8SAl Viro got_write = true; 35450f9d1a10SAl Viro } 3546e83db167SMiklos Szeredi finish_open_created: 3547bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3548ca344a89SAl Viro if (error) 35492675a4ebSAl Viro goto out; 3550aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3551ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3552fac7d191SAl Viro if (error) 3553015c3bbcSMiklos Szeredi goto out; 3554a8277b9bSMiklos Szeredi opened: 35556035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3556fe9ec829SAl Viro if (!error && will_truncate) 35572675a4ebSAl Viro error = handle_truncate(file); 3558ca344a89SAl Viro out: 3559c80567c8SAl Viro if (unlikely(error > 0)) { 3560c80567c8SAl Viro WARN_ON(1); 3561c80567c8SAl Viro error = -EINVAL; 3562c80567c8SAl Viro } 356364894cf8SAl Viro if (got_write) 35640f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 35652675a4ebSAl Viro return error; 3566fb1cc555SAl Viro } 3567fb1cc555SAl Viro 3568af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3569af7bd4dcSAmir Goldstein { 3570af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3571af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3572af7bd4dcSAmir Goldstein struct inode *inode; 3573af7bd4dcSAmir Goldstein int error; 3574af7bd4dcSAmir Goldstein 3575af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3576af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3577af7bd4dcSAmir Goldstein if (error) 3578af7bd4dcSAmir Goldstein goto out_err; 3579af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3580af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3581af7bd4dcSAmir Goldstein goto out_err; 3582af7bd4dcSAmir Goldstein error = -ENOMEM; 3583cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3584af7bd4dcSAmir Goldstein if (unlikely(!child)) 3585af7bd4dcSAmir Goldstein goto out_err; 3586af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3587af7bd4dcSAmir Goldstein if (error) 3588af7bd4dcSAmir Goldstein goto out_err; 3589af7bd4dcSAmir Goldstein error = -ENOENT; 3590af7bd4dcSAmir Goldstein inode = child->d_inode; 3591af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3592af7bd4dcSAmir Goldstein goto out_err; 3593af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3594af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3595af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3596af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3597af7bd4dcSAmir Goldstein } 3598fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3599af7bd4dcSAmir Goldstein return child; 3600af7bd4dcSAmir Goldstein 3601af7bd4dcSAmir Goldstein out_err: 3602af7bd4dcSAmir Goldstein dput(child); 3603af7bd4dcSAmir Goldstein return ERR_PTR(error); 3604af7bd4dcSAmir Goldstein } 3605af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3606af7bd4dcSAmir Goldstein 3607c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 360860545d0dSAl Viro const struct open_flags *op, 36093ec2eef1SAl Viro struct file *file) 361060545d0dSAl Viro { 3611625b6d10SAl Viro struct dentry *child; 3612625b6d10SAl Viro struct path path; 3613c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 361460545d0dSAl Viro if (unlikely(error)) 361560545d0dSAl Viro return error; 3616625b6d10SAl Viro error = mnt_want_write(path.mnt); 361760545d0dSAl Viro if (unlikely(error)) 361860545d0dSAl Viro goto out; 3619af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3620af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3621684e73beSHirofumi Nakagawa if (IS_ERR(child)) 362260545d0dSAl Viro goto out2; 3623625b6d10SAl Viro dput(path.dentry); 3624625b6d10SAl Viro path.dentry = child; 3625c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 362669a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 362762fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 362860545d0dSAl Viro if (error) 362960545d0dSAl Viro goto out2; 3630625b6d10SAl Viro file->f_path.mnt = path.mnt; 3631be12af3eSAl Viro error = finish_open(file, child, NULL); 363260545d0dSAl Viro out2: 3633625b6d10SAl Viro mnt_drop_write(path.mnt); 363460545d0dSAl Viro out: 3635625b6d10SAl Viro path_put(&path); 363660545d0dSAl Viro return error; 363760545d0dSAl Viro } 363860545d0dSAl Viro 36396ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 36406ac08709SAl Viro { 36416ac08709SAl Viro struct path path; 36426ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 36436ac08709SAl Viro if (!error) { 36446ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3645ae2bb293SAl Viro error = vfs_open(&path, file); 36466ac08709SAl Viro path_put(&path); 36476ac08709SAl Viro } 36486ac08709SAl Viro return error; 36496ac08709SAl Viro } 36506ac08709SAl Viro 3651c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3652c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 36531da177e4SLinus Torvalds { 365430d90494SAl Viro struct file *file; 365513aab428SAl Viro int error; 365631e6b01fSNick Piggin 3657ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 36581afc99beSAl Viro if (IS_ERR(file)) 36591afc99beSAl Viro return file; 366031e6b01fSNick Piggin 3661bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 36623ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 36635f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 36646ac08709SAl Viro error = do_o_path(nd, flags, file); 36655f336e72SAl Viro } else { 36665f336e72SAl Viro const char *s = path_init(nd, flags); 36673bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 36683ec2eef1SAl Viro (error = do_last(nd, file, op)) > 0) { 366973d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 36703bdba28bSAl Viro s = trailing_symlink(nd); 36713bdba28bSAl Viro } 3672deb106c6SAl Viro terminate_walk(nd); 36735f336e72SAl Viro } 36747c1c01ecSAl Viro if (likely(!error)) { 3675aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 36767c1c01ecSAl Viro return file; 36777c1c01ecSAl Viro WARN_ON(1); 36787c1c01ecSAl Viro error = -EINVAL; 3679015c3bbcSMiklos Szeredi } 36807c1c01ecSAl Viro fput(file); 36812675a4ebSAl Viro if (error == -EOPENSTALE) { 36822675a4ebSAl Viro if (flags & LOOKUP_RCU) 36832675a4ebSAl Viro error = -ECHILD; 36842675a4ebSAl Viro else 36852675a4ebSAl Viro error = -ESTALE; 36862675a4ebSAl Viro } 36877c1c01ecSAl Viro return ERR_PTR(error); 3688de459215SKirill Korotaev } 36891da177e4SLinus Torvalds 3690669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3691f9652e10SAl Viro const struct open_flags *op) 369213aab428SAl Viro { 36939883d185SAl Viro struct nameidata nd; 3694f9652e10SAl Viro int flags = op->lookup_flags; 369513aab428SAl Viro struct file *filp; 369613aab428SAl Viro 36979883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3698c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 369913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3700c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 370113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3702c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 37039883d185SAl Viro restore_nameidata(); 370413aab428SAl Viro return filp; 370513aab428SAl Viro } 370613aab428SAl Viro 370773d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3708f9652e10SAl Viro const char *name, const struct open_flags *op) 370973d049a4SAl Viro { 37109883d185SAl Viro struct nameidata nd; 371173d049a4SAl Viro struct file *file; 371251689104SPaul Moore struct filename *filename; 3713f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 371473d049a4SAl Viro 371573d049a4SAl Viro nd.root.mnt = mnt; 371673d049a4SAl Viro nd.root.dentry = dentry; 371773d049a4SAl Viro 3718b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 371973d049a4SAl Viro return ERR_PTR(-ELOOP); 372073d049a4SAl Viro 372151689104SPaul Moore filename = getname_kernel(name); 3722a1c83681SViresh Kumar if (IS_ERR(filename)) 372351689104SPaul Moore return ERR_CAST(filename); 372451689104SPaul Moore 37259883d185SAl Viro set_nameidata(&nd, -1, filename); 3726c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 372773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3728c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 372973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3730c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 37319883d185SAl Viro restore_nameidata(); 373251689104SPaul Moore putname(filename); 373373d049a4SAl Viro return file; 373473d049a4SAl Viro } 373573d049a4SAl Viro 3736fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 37371ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 37381da177e4SLinus Torvalds { 3739c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3740391172c4SAl Viro struct qstr last; 3741391172c4SAl Viro int type; 3742c30dabfeSJan Kara int err2; 37431ac12b4bSJeff Layton int error; 37441ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 37451ac12b4bSJeff Layton 37461ac12b4bSJeff Layton /* 37471ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 37481ac12b4bSJeff Layton * other flags passed in are ignored! 37491ac12b4bSJeff Layton */ 37501ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 37511ac12b4bSJeff Layton 37525c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 37535c31b6ceSAl Viro if (IS_ERR(name)) 37545c31b6ceSAl Viro return ERR_CAST(name); 37551da177e4SLinus Torvalds 3756c663e5d8SChristoph Hellwig /* 3757c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3758c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3759c663e5d8SChristoph Hellwig */ 37605c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3761ed75e95dSAl Viro goto out; 3762c663e5d8SChristoph Hellwig 3763c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3764391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3765c663e5d8SChristoph Hellwig /* 3766c663e5d8SChristoph Hellwig * Do the final lookup. 3767c663e5d8SChristoph Hellwig */ 3768391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 37695955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3770391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 37711da177e4SLinus Torvalds if (IS_ERR(dentry)) 3772a8104a9fSAl Viro goto unlock; 3773c663e5d8SChristoph Hellwig 3774a8104a9fSAl Viro error = -EEXIST; 3775b18825a7SDavid Howells if (d_is_positive(dentry)) 3776a8104a9fSAl Viro goto fail; 3777b18825a7SDavid Howells 3778c663e5d8SChristoph Hellwig /* 3779c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3780c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3781c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3782c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3783c663e5d8SChristoph Hellwig */ 3784391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3785a8104a9fSAl Viro error = -ENOENT; 3786ed75e95dSAl Viro goto fail; 3787e9baf6e5SAl Viro } 3788c30dabfeSJan Kara if (unlikely(err2)) { 3789c30dabfeSJan Kara error = err2; 3790a8104a9fSAl Viro goto fail; 3791c30dabfeSJan Kara } 3792181c37b6SAl Viro putname(name); 3793e9baf6e5SAl Viro return dentry; 37941da177e4SLinus Torvalds fail: 3795a8104a9fSAl Viro dput(dentry); 3796a8104a9fSAl Viro dentry = ERR_PTR(error); 3797a8104a9fSAl Viro unlock: 37985955102cSAl Viro inode_unlock(path->dentry->d_inode); 3799c30dabfeSJan Kara if (!err2) 3800391172c4SAl Viro mnt_drop_write(path->mnt); 3801ed75e95dSAl Viro out: 3802391172c4SAl Viro path_put(path); 3803181c37b6SAl Viro putname(name); 3804ed75e95dSAl Viro return dentry; 3805dae6ad8fSAl Viro } 3806fa14a0b8SAl Viro 3807fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3808fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3809fa14a0b8SAl Viro { 3810181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3811181c37b6SAl Viro path, lookup_flags); 3812fa14a0b8SAl Viro } 3813dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3814dae6ad8fSAl Viro 3815921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3816921a1650SAl Viro { 3817921a1650SAl Viro dput(dentry); 38185955102cSAl Viro inode_unlock(path->dentry->d_inode); 3819a8104a9fSAl Viro mnt_drop_write(path->mnt); 3820921a1650SAl Viro path_put(path); 3821921a1650SAl Viro } 3822921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3823921a1650SAl Viro 3824520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 38251ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3826dae6ad8fSAl Viro { 3827181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3828dae6ad8fSAl Viro } 3829dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3830dae6ad8fSAl Viro 38311a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 38321da177e4SLinus Torvalds { 3833a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38341da177e4SLinus Torvalds 38351da177e4SLinus Torvalds if (error) 38361da177e4SLinus Torvalds return error; 38371da177e4SLinus Torvalds 383894f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 38391da177e4SLinus Torvalds return -EPERM; 38401da177e4SLinus Torvalds 3841acfa4380SAl Viro if (!dir->i_op->mknod) 38421da177e4SLinus Torvalds return -EPERM; 38431da177e4SLinus Torvalds 384408ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 384508ce5f16SSerge E. Hallyn if (error) 384608ce5f16SSerge E. Hallyn return error; 384708ce5f16SSerge E. Hallyn 38481da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 38491da177e4SLinus Torvalds if (error) 38501da177e4SLinus Torvalds return error; 38511da177e4SLinus Torvalds 38521da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3853a74574aaSStephen Smalley if (!error) 3854f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38551da177e4SLinus Torvalds return error; 38561da177e4SLinus Torvalds } 38574d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 38581da177e4SLinus Torvalds 3859f69aac00SAl Viro static int may_mknod(umode_t mode) 3860463c3197SDave Hansen { 3861463c3197SDave Hansen switch (mode & S_IFMT) { 3862463c3197SDave Hansen case S_IFREG: 3863463c3197SDave Hansen case S_IFCHR: 3864463c3197SDave Hansen case S_IFBLK: 3865463c3197SDave Hansen case S_IFIFO: 3866463c3197SDave Hansen case S_IFSOCK: 3867463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3868463c3197SDave Hansen return 0; 3869463c3197SDave Hansen case S_IFDIR: 3870463c3197SDave Hansen return -EPERM; 3871463c3197SDave Hansen default: 3872463c3197SDave Hansen return -EINVAL; 3873463c3197SDave Hansen } 3874463c3197SDave Hansen } 3875463c3197SDave Hansen 387687c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 387787c4e192SDominik Brodowski unsigned int dev) 38781da177e4SLinus Torvalds { 38791da177e4SLinus Torvalds struct dentry *dentry; 3880dae6ad8fSAl Viro struct path path; 3881dae6ad8fSAl Viro int error; 3882972567f1SJeff Layton unsigned int lookup_flags = 0; 38831da177e4SLinus Torvalds 38848e4bfca1SAl Viro error = may_mknod(mode); 38858e4bfca1SAl Viro if (error) 38868e4bfca1SAl Viro return error; 3887972567f1SJeff Layton retry: 3888972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3889dae6ad8fSAl Viro if (IS_ERR(dentry)) 3890dae6ad8fSAl Viro return PTR_ERR(dentry); 38912ad94ae6SAl Viro 3892dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3893ce3b0f8dSAl Viro mode &= ~current_umask(); 3894dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3895be6d3e56SKentaro Takeda if (error) 3896a8104a9fSAl Viro goto out; 38971da177e4SLinus Torvalds switch (mode & S_IFMT) { 38981da177e4SLinus Torvalds case 0: case S_IFREG: 3899312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 390005d1a717SMimi Zohar if (!error) 390105d1a717SMimi Zohar ima_post_path_mknod(dentry); 39021da177e4SLinus Torvalds break; 39031da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3904dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 39051da177e4SLinus Torvalds new_decode_dev(dev)); 39061da177e4SLinus Torvalds break; 39071da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3908dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 39091da177e4SLinus Torvalds break; 39101da177e4SLinus Torvalds } 3911a8104a9fSAl Viro out: 3912921a1650SAl Viro done_path_create(&path, dentry); 3913972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3914972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3915972567f1SJeff Layton goto retry; 3916972567f1SJeff Layton } 39171da177e4SLinus Torvalds return error; 39181da177e4SLinus Torvalds } 39191da177e4SLinus Torvalds 392087c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 392187c4e192SDominik Brodowski unsigned int, dev) 392287c4e192SDominik Brodowski { 392387c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 392487c4e192SDominik Brodowski } 392587c4e192SDominik Brodowski 39268208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 39275590ff0dSUlrich Drepper { 392887c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 39295590ff0dSUlrich Drepper } 39305590ff0dSUlrich Drepper 393118bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 39321da177e4SLinus Torvalds { 3933a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39348de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39351da177e4SLinus Torvalds 39361da177e4SLinus Torvalds if (error) 39371da177e4SLinus Torvalds return error; 39381da177e4SLinus Torvalds 3939acfa4380SAl Viro if (!dir->i_op->mkdir) 39401da177e4SLinus Torvalds return -EPERM; 39411da177e4SLinus Torvalds 39421da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 39431da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 39441da177e4SLinus Torvalds if (error) 39451da177e4SLinus Torvalds return error; 39461da177e4SLinus Torvalds 39478de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 39488de52778SAl Viro return -EMLINK; 39498de52778SAl Viro 39501da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3951a74574aaSStephen Smalley if (!error) 3952f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 39531da177e4SLinus Torvalds return error; 39541da177e4SLinus Torvalds } 39554d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 39561da177e4SLinus Torvalds 39570101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 39581da177e4SLinus Torvalds { 39596902d925SDave Hansen struct dentry *dentry; 3960dae6ad8fSAl Viro struct path path; 3961dae6ad8fSAl Viro int error; 3962b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 39631da177e4SLinus Torvalds 3964b76d8b82SJeff Layton retry: 3965b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 39666902d925SDave Hansen if (IS_ERR(dentry)) 3967dae6ad8fSAl Viro return PTR_ERR(dentry); 39686902d925SDave Hansen 3969dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3970ce3b0f8dSAl Viro mode &= ~current_umask(); 3971dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3972a8104a9fSAl Viro if (!error) 3973dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3974921a1650SAl Viro done_path_create(&path, dentry); 3975b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3976b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3977b76d8b82SJeff Layton goto retry; 3978b76d8b82SJeff Layton } 39791da177e4SLinus Torvalds return error; 39801da177e4SLinus Torvalds } 39811da177e4SLinus Torvalds 39820101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 39830101db7aSDominik Brodowski { 39840101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 39850101db7aSDominik Brodowski } 39860101db7aSDominik Brodowski 3987a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 39885590ff0dSUlrich Drepper { 39890101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 39905590ff0dSUlrich Drepper } 39915590ff0dSUlrich Drepper 39921da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 39931da177e4SLinus Torvalds { 39941da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 39951da177e4SLinus Torvalds 39961da177e4SLinus Torvalds if (error) 39971da177e4SLinus Torvalds return error; 39981da177e4SLinus Torvalds 3999acfa4380SAl Viro if (!dir->i_op->rmdir) 40001da177e4SLinus Torvalds return -EPERM; 40011da177e4SLinus Torvalds 40021d2ef590SAl Viro dget(dentry); 40035955102cSAl Viro inode_lock(dentry->d_inode); 4004912dbc15SSage Weil 40051da177e4SLinus Torvalds error = -EBUSY; 40067af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 4007912dbc15SSage Weil goto out; 4008912dbc15SSage Weil 40091da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 4010912dbc15SSage Weil if (error) 4011912dbc15SSage Weil goto out; 4012912dbc15SSage Weil 40131da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 4014912dbc15SSage Weil if (error) 4015912dbc15SSage Weil goto out; 4016912dbc15SSage Weil 40178767712fSAl Viro shrink_dcache_parent(dentry); 40181da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 4019d83c49f3SAl Viro dont_mount(dentry); 40208ed936b5SEric W. Biederman detach_mounts(dentry); 4021116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 40221da177e4SLinus Torvalds 4023912dbc15SSage Weil out: 40245955102cSAl Viro inode_unlock(dentry->d_inode); 40251d2ef590SAl Viro dput(dentry); 4026912dbc15SSage Weil if (!error) 4027912dbc15SSage Weil d_delete(dentry); 40281da177e4SLinus Torvalds return error; 40291da177e4SLinus Torvalds } 40304d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 40311da177e4SLinus Torvalds 4032f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 40331da177e4SLinus Torvalds { 40341da177e4SLinus Torvalds int error = 0; 403591a27b2aSJeff Layton struct filename *name; 40361da177e4SLinus Torvalds struct dentry *dentry; 4037f5beed75SAl Viro struct path path; 4038f5beed75SAl Viro struct qstr last; 4039f5beed75SAl Viro int type; 4040c6ee9206SJeff Layton unsigned int lookup_flags = 0; 4041c6ee9206SJeff Layton retry: 4042c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 4043c1d4dd27SAl Viro &path, &last, &type); 404491a27b2aSJeff Layton if (IS_ERR(name)) 404591a27b2aSJeff Layton return PTR_ERR(name); 40461da177e4SLinus Torvalds 4047f5beed75SAl Viro switch (type) { 40481da177e4SLinus Torvalds case LAST_DOTDOT: 40491da177e4SLinus Torvalds error = -ENOTEMPTY; 40501da177e4SLinus Torvalds goto exit1; 40511da177e4SLinus Torvalds case LAST_DOT: 40521da177e4SLinus Torvalds error = -EINVAL; 40531da177e4SLinus Torvalds goto exit1; 40541da177e4SLinus Torvalds case LAST_ROOT: 40551da177e4SLinus Torvalds error = -EBUSY; 40561da177e4SLinus Torvalds goto exit1; 40571da177e4SLinus Torvalds } 40580612d9fbSOGAWA Hirofumi 4059f5beed75SAl Viro error = mnt_want_write(path.mnt); 4060c30dabfeSJan Kara if (error) 4061c30dabfeSJan Kara goto exit1; 40620612d9fbSOGAWA Hirofumi 40635955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4064f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40651da177e4SLinus Torvalds error = PTR_ERR(dentry); 40666902d925SDave Hansen if (IS_ERR(dentry)) 40676902d925SDave Hansen goto exit2; 4068e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 4069e6bc45d6STheodore Ts'o error = -ENOENT; 4070e6bc45d6STheodore Ts'o goto exit3; 4071e6bc45d6STheodore Ts'o } 4072f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 4073be6d3e56SKentaro Takeda if (error) 4074c30dabfeSJan Kara goto exit3; 4075f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 40760622753bSDave Hansen exit3: 40771da177e4SLinus Torvalds dput(dentry); 40786902d925SDave Hansen exit2: 40795955102cSAl Viro inode_unlock(path.dentry->d_inode); 4080f5beed75SAl Viro mnt_drop_write(path.mnt); 40811da177e4SLinus Torvalds exit1: 4082f5beed75SAl Viro path_put(&path); 40831da177e4SLinus Torvalds putname(name); 4084c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 4085c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 4086c6ee9206SJeff Layton goto retry; 4087c6ee9206SJeff Layton } 40881da177e4SLinus Torvalds return error; 40891da177e4SLinus Torvalds } 40901da177e4SLinus Torvalds 40913cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 40925590ff0dSUlrich Drepper { 40935590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 40945590ff0dSUlrich Drepper } 40955590ff0dSUlrich Drepper 4096b21996e3SJ. Bruce Fields /** 4097b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 4098b21996e3SJ. Bruce Fields * @dir: parent directory 4099b21996e3SJ. Bruce Fields * @dentry: victim 4100b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 4101b21996e3SJ. Bruce Fields * 4102b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 4103b21996e3SJ. Bruce Fields * 4104b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 4105b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 4106b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 4107b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 4108b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 4109b21996e3SJ. Bruce Fields * 4110b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4111b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4112b21996e3SJ. Bruce Fields * to be NFS exported. 4113b21996e3SJ. Bruce Fields */ 4114b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 41151da177e4SLinus Torvalds { 41169accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 41171da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 41181da177e4SLinus Torvalds 41191da177e4SLinus Torvalds if (error) 41201da177e4SLinus Torvalds return error; 41211da177e4SLinus Torvalds 4122acfa4380SAl Viro if (!dir->i_op->unlink) 41231da177e4SLinus Torvalds return -EPERM; 41241da177e4SLinus Torvalds 41255955102cSAl Viro inode_lock(target); 41268ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 41271da177e4SLinus Torvalds error = -EBUSY; 41281da177e4SLinus Torvalds else { 41291da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 4130bec1052eSAl Viro if (!error) { 41315a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 41325a14696cSJ. Bruce Fields if (error) 4133b21996e3SJ. Bruce Fields goto out; 41341da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 41358ed936b5SEric W. Biederman if (!error) { 4136d83c49f3SAl Viro dont_mount(dentry); 41378ed936b5SEric W. Biederman detach_mounts(dentry); 4138116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 41398ed936b5SEric W. Biederman } 4140bec1052eSAl Viro } 41411da177e4SLinus Torvalds } 4142b21996e3SJ. Bruce Fields out: 41435955102cSAl Viro inode_unlock(target); 41441da177e4SLinus Torvalds 41451da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 41461da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 41479accbb97SJ. Bruce Fields fsnotify_link_count(target); 41481da177e4SLinus Torvalds d_delete(dentry); 41491da177e4SLinus Torvalds } 41500eeca283SRobert Love 41511da177e4SLinus Torvalds return error; 41521da177e4SLinus Torvalds } 41534d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 41541da177e4SLinus Torvalds 41551da177e4SLinus Torvalds /* 41561da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 41571b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 41581da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 41591da177e4SLinus Torvalds * while waiting on the I/O. 41601da177e4SLinus Torvalds */ 4161da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 41621da177e4SLinus Torvalds { 41632ad94ae6SAl Viro int error; 41641da177e4SLinus Torvalds struct dentry *dentry; 4165f5beed75SAl Viro struct path path; 4166f5beed75SAl Viro struct qstr last; 4167f5beed75SAl Viro int type; 41681da177e4SLinus Torvalds struct inode *inode = NULL; 4169b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 41705d18f813SJeff Layton unsigned int lookup_flags = 0; 41715d18f813SJeff Layton retry: 4172da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 417391a27b2aSJeff Layton if (IS_ERR(name)) 417491a27b2aSJeff Layton return PTR_ERR(name); 41752ad94ae6SAl Viro 41761da177e4SLinus Torvalds error = -EISDIR; 4177f5beed75SAl Viro if (type != LAST_NORM) 41781da177e4SLinus Torvalds goto exit1; 41790612d9fbSOGAWA Hirofumi 4180f5beed75SAl Viro error = mnt_want_write(path.mnt); 4181c30dabfeSJan Kara if (error) 4182c30dabfeSJan Kara goto exit1; 4183b21996e3SJ. Bruce Fields retry_deleg: 41845955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4185f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 41861da177e4SLinus Torvalds error = PTR_ERR(dentry); 41871da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 41881da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4189f5beed75SAl Viro if (last.name[last.len]) 419050338b88STörök Edwin goto slashes; 41911da177e4SLinus Torvalds inode = dentry->d_inode; 4192b18825a7SDavid Howells if (d_is_negative(dentry)) 4193e6bc45d6STheodore Ts'o goto slashes; 41947de9c6eeSAl Viro ihold(inode); 4195f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4196be6d3e56SKentaro Takeda if (error) 4197c30dabfeSJan Kara goto exit2; 4198f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 41991da177e4SLinus Torvalds exit2: 42001da177e4SLinus Torvalds dput(dentry); 42011da177e4SLinus Torvalds } 42025955102cSAl Viro inode_unlock(path.dentry->d_inode); 42031da177e4SLinus Torvalds if (inode) 42041da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4205b21996e3SJ. Bruce Fields inode = NULL; 4206b21996e3SJ. Bruce Fields if (delegated_inode) { 42075a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4208b21996e3SJ. Bruce Fields if (!error) 4209b21996e3SJ. Bruce Fields goto retry_deleg; 4210b21996e3SJ. Bruce Fields } 4211f5beed75SAl Viro mnt_drop_write(path.mnt); 42121da177e4SLinus Torvalds exit1: 4213f5beed75SAl Viro path_put(&path); 42145d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 42155d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 42165d18f813SJeff Layton inode = NULL; 42175d18f813SJeff Layton goto retry; 42185d18f813SJeff Layton } 4219da2f1362SChristoph Hellwig putname(name); 42201da177e4SLinus Torvalds return error; 42211da177e4SLinus Torvalds 42221da177e4SLinus Torvalds slashes: 4223b18825a7SDavid Howells if (d_is_negative(dentry)) 4224b18825a7SDavid Howells error = -ENOENT; 422544b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4226b18825a7SDavid Howells error = -EISDIR; 4227b18825a7SDavid Howells else 4228b18825a7SDavid Howells error = -ENOTDIR; 42291da177e4SLinus Torvalds goto exit2; 42301da177e4SLinus Torvalds } 42311da177e4SLinus Torvalds 42322e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 42335590ff0dSUlrich Drepper { 42345590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 42355590ff0dSUlrich Drepper return -EINVAL; 42365590ff0dSUlrich Drepper 42375590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 42385590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 42395590ff0dSUlrich Drepper 4240da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 42415590ff0dSUlrich Drepper } 42425590ff0dSUlrich Drepper 42433480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 42445590ff0dSUlrich Drepper { 4245da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 42465590ff0dSUlrich Drepper } 42475590ff0dSUlrich Drepper 4248db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 42491da177e4SLinus Torvalds { 4250a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 42511da177e4SLinus Torvalds 42521da177e4SLinus Torvalds if (error) 42531da177e4SLinus Torvalds return error; 42541da177e4SLinus Torvalds 4255acfa4380SAl Viro if (!dir->i_op->symlink) 42561da177e4SLinus Torvalds return -EPERM; 42571da177e4SLinus Torvalds 42581da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 42591da177e4SLinus Torvalds if (error) 42601da177e4SLinus Torvalds return error; 42611da177e4SLinus Torvalds 42621da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4263a74574aaSStephen Smalley if (!error) 4264f38aa942SAmy Griffis fsnotify_create(dir, dentry); 42651da177e4SLinus Torvalds return error; 42661da177e4SLinus Torvalds } 42674d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 42681da177e4SLinus Torvalds 4269b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4270b724e846SDominik Brodowski const char __user *newname) 42711da177e4SLinus Torvalds { 42722ad94ae6SAl Viro int error; 427391a27b2aSJeff Layton struct filename *from; 42746902d925SDave Hansen struct dentry *dentry; 4275dae6ad8fSAl Viro struct path path; 4276f46d3567SJeff Layton unsigned int lookup_flags = 0; 42771da177e4SLinus Torvalds 42781da177e4SLinus Torvalds from = getname(oldname); 42791da177e4SLinus Torvalds if (IS_ERR(from)) 42801da177e4SLinus Torvalds return PTR_ERR(from); 4281f46d3567SJeff Layton retry: 4282f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 42831da177e4SLinus Torvalds error = PTR_ERR(dentry); 42846902d925SDave Hansen if (IS_ERR(dentry)) 4285dae6ad8fSAl Viro goto out_putname; 42866902d925SDave Hansen 428791a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4288a8104a9fSAl Viro if (!error) 428991a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4290921a1650SAl Viro done_path_create(&path, dentry); 4291f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4292f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4293f46d3567SJeff Layton goto retry; 4294f46d3567SJeff Layton } 42956902d925SDave Hansen out_putname: 42961da177e4SLinus Torvalds putname(from); 42971da177e4SLinus Torvalds return error; 42981da177e4SLinus Torvalds } 42991da177e4SLinus Torvalds 4300b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4301b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4302b724e846SDominik Brodowski { 4303b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4304b724e846SDominik Brodowski } 4305b724e846SDominik Brodowski 43063480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 43075590ff0dSUlrich Drepper { 4308b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 43095590ff0dSUlrich Drepper } 43105590ff0dSUlrich Drepper 4311146a8595SJ. Bruce Fields /** 4312146a8595SJ. Bruce Fields * vfs_link - create a new link 4313146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4314146a8595SJ. Bruce Fields * @dir: new parent 4315146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4316146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4317146a8595SJ. Bruce Fields * 4318146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4319146a8595SJ. Bruce Fields * 4320146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4321146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4322146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4323146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4324146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4325146a8595SJ. Bruce Fields * 4326146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4327146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4328146a8595SJ. Bruce Fields * to be NFS exported. 4329146a8595SJ. Bruce Fields */ 4330146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 43311da177e4SLinus Torvalds { 43321da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 43338de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 43341da177e4SLinus Torvalds int error; 43351da177e4SLinus Torvalds 43361da177e4SLinus Torvalds if (!inode) 43371da177e4SLinus Torvalds return -ENOENT; 43381da177e4SLinus Torvalds 4339a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 43401da177e4SLinus Torvalds if (error) 43411da177e4SLinus Torvalds return error; 43421da177e4SLinus Torvalds 43431da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 43441da177e4SLinus Torvalds return -EXDEV; 43451da177e4SLinus Torvalds 43461da177e4SLinus Torvalds /* 43471da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 43481da177e4SLinus Torvalds */ 43491da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 43501da177e4SLinus Torvalds return -EPERM; 43510bd23d09SEric W. Biederman /* 43520bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 43530bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 43540bd23d09SEric W. Biederman * the vfs. 43550bd23d09SEric W. Biederman */ 43560bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 43570bd23d09SEric W. Biederman return -EPERM; 4358acfa4380SAl Viro if (!dir->i_op->link) 43591da177e4SLinus Torvalds return -EPERM; 43607e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 43611da177e4SLinus Torvalds return -EPERM; 43621da177e4SLinus Torvalds 43631da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 43641da177e4SLinus Torvalds if (error) 43651da177e4SLinus Torvalds return error; 43661da177e4SLinus Torvalds 43675955102cSAl Viro inode_lock(inode); 4368aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4369f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4370aae8a97dSAneesh Kumar K.V error = -ENOENT; 43718de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 43728de52778SAl Viro error = -EMLINK; 4373146a8595SJ. Bruce Fields else { 4374146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4375146a8595SJ. Bruce Fields if (!error) 43761da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4377146a8595SJ. Bruce Fields } 4378f4e0c30cSAl Viro 4379f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4380f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4381f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4382f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4383f4e0c30cSAl Viro } 43845955102cSAl Viro inode_unlock(inode); 4385e31e14ecSStephen Smalley if (!error) 43867e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 43871da177e4SLinus Torvalds return error; 43881da177e4SLinus Torvalds } 43894d359507SAl Viro EXPORT_SYMBOL(vfs_link); 43901da177e4SLinus Torvalds 43911da177e4SLinus Torvalds /* 43921da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 43931da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 43941da177e4SLinus Torvalds * newname. --KAB 43951da177e4SLinus Torvalds * 43961da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 43971da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 43981da177e4SLinus Torvalds * and other special files. --ADM 43991da177e4SLinus Torvalds */ 440046ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 440146ea89ebSDominik Brodowski const char __user *newname, int flags) 44021da177e4SLinus Torvalds { 44031da177e4SLinus Torvalds struct dentry *new_dentry; 4404dae6ad8fSAl Viro struct path old_path, new_path; 4405146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 440611a7b371SAneesh Kumar K.V int how = 0; 44071da177e4SLinus Torvalds int error; 44081da177e4SLinus Torvalds 440911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4410c04030e1SUlrich Drepper return -EINVAL; 441111a7b371SAneesh Kumar K.V /* 4412f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4413f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4414f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 441511a7b371SAneesh Kumar K.V */ 4416f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4417f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4418f0cc6ffbSLinus Torvalds return -ENOENT; 441911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4420f0cc6ffbSLinus Torvalds } 4421c04030e1SUlrich Drepper 442211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 442311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4424442e31caSJeff Layton retry: 442511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 44261da177e4SLinus Torvalds if (error) 44272ad94ae6SAl Viro return error; 44282ad94ae6SAl Viro 4429442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4430442e31caSJeff Layton (how & LOOKUP_REVAL)); 44311da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44326902d925SDave Hansen if (IS_ERR(new_dentry)) 4433dae6ad8fSAl Viro goto out; 4434dae6ad8fSAl Viro 4435dae6ad8fSAl Viro error = -EXDEV; 4436dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4437dae6ad8fSAl Viro goto out_dput; 4438800179c9SKees Cook error = may_linkat(&old_path); 4439800179c9SKees Cook if (unlikely(error)) 4440800179c9SKees Cook goto out_dput; 4441dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4442be6d3e56SKentaro Takeda if (error) 4443a8104a9fSAl Viro goto out_dput; 4444146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 444575c3f29dSDave Hansen out_dput: 4446921a1650SAl Viro done_path_create(&new_path, new_dentry); 4447146a8595SJ. Bruce Fields if (delegated_inode) { 4448146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4449d22e6338SOleg Drokin if (!error) { 4450d22e6338SOleg Drokin path_put(&old_path); 4451146a8595SJ. Bruce Fields goto retry; 4452146a8595SJ. Bruce Fields } 4453d22e6338SOleg Drokin } 4454442e31caSJeff Layton if (retry_estale(error, how)) { 4455d22e6338SOleg Drokin path_put(&old_path); 4456442e31caSJeff Layton how |= LOOKUP_REVAL; 4457442e31caSJeff Layton goto retry; 4458442e31caSJeff Layton } 44591da177e4SLinus Torvalds out: 44602d8f3038SAl Viro path_put(&old_path); 44611da177e4SLinus Torvalds 44621da177e4SLinus Torvalds return error; 44631da177e4SLinus Torvalds } 44641da177e4SLinus Torvalds 446546ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 446646ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 446746ea89ebSDominik Brodowski { 446846ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 446946ea89ebSDominik Brodowski } 447046ea89ebSDominik Brodowski 44713480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 44725590ff0dSUlrich Drepper { 447346ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44745590ff0dSUlrich Drepper } 44755590ff0dSUlrich Drepper 4476bc27027aSMiklos Szeredi /** 4477bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4478bc27027aSMiklos Szeredi * @old_dir: parent of source 4479bc27027aSMiklos Szeredi * @old_dentry: source 4480bc27027aSMiklos Szeredi * @new_dir: parent of destination 4481bc27027aSMiklos Szeredi * @new_dentry: destination 4482bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4483520c8b16SMiklos Szeredi * @flags: rename flags 4484bc27027aSMiklos Szeredi * 4485bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4486bc27027aSMiklos Szeredi * 4487bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4488bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4489bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4490bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4491bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4492bc27027aSMiklos Szeredi * so. 4493bc27027aSMiklos Szeredi * 4494bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4495bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4496bc27027aSMiklos Szeredi * to be NFS exported. 4497bc27027aSMiklos Szeredi * 44981da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 44991da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 45001da177e4SLinus Torvalds * Problems: 45010117d427SMauro Carvalho Chehab * 4502d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 45031da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 45041da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4505a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 45061da177e4SLinus Torvalds * story. 45076cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 45086cedba89SJ. Bruce Fields * and source (if it is not a directory). 45091b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 45101da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 45111da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4512a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 45131da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 45141da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 45151da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4516a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 45171da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 45181da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 45191da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4520e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 45211b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 45221da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4523c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 45241da177e4SLinus Torvalds * locking]. 45251da177e4SLinus Torvalds */ 45261da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 45278e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4528520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 45291da177e4SLinus Torvalds { 45301da177e4SLinus Torvalds int error; 4531bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4532bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4533bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4534da1ce067SMiklos Szeredi bool new_is_dir = false; 4535da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 453649d31c2fSAl Viro struct name_snapshot old_name; 45371da177e4SLinus Torvalds 45388d3e2936SMiklos Szeredi if (source == target) 45391da177e4SLinus Torvalds return 0; 45401da177e4SLinus Torvalds 45411da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 45421da177e4SLinus Torvalds if (error) 45431da177e4SLinus Torvalds return error; 45441da177e4SLinus Torvalds 4545da1ce067SMiklos Szeredi if (!target) { 4546a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4547da1ce067SMiklos Szeredi } else { 4548da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4549da1ce067SMiklos Szeredi 4550da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45511da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4552da1ce067SMiklos Szeredi else 4553da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4554da1ce067SMiklos Szeredi } 45551da177e4SLinus Torvalds if (error) 45561da177e4SLinus Torvalds return error; 45571da177e4SLinus Torvalds 45582773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 45591da177e4SLinus Torvalds return -EPERM; 45601da177e4SLinus Torvalds 4561bc27027aSMiklos Szeredi /* 4562bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4563bc27027aSMiklos Szeredi * we'll need to flip '..'. 4564bc27027aSMiklos Szeredi */ 4565da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4566da1ce067SMiklos Szeredi if (is_dir) { 4567bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4568bc27027aSMiklos Szeredi if (error) 4569bc27027aSMiklos Szeredi return error; 4570bc27027aSMiklos Szeredi } 4571da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4572da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4573da1ce067SMiklos Szeredi if (error) 4574da1ce067SMiklos Szeredi return error; 4575da1ce067SMiklos Szeredi } 4576da1ce067SMiklos Szeredi } 45770eeca283SRobert Love 45780b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 45790b3974ebSMiklos Szeredi flags); 4580bc27027aSMiklos Szeredi if (error) 4581bc27027aSMiklos Szeredi return error; 4582bc27027aSMiklos Szeredi 458349d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4584bc27027aSMiklos Szeredi dget(new_dentry); 4585da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4586bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4587bc27027aSMiklos Szeredi else if (target) 45885955102cSAl Viro inode_lock(target); 4589bc27027aSMiklos Szeredi 4590bc27027aSMiklos Szeredi error = -EBUSY; 45917af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4592bc27027aSMiklos Szeredi goto out; 4593bc27027aSMiklos Szeredi 4594da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4595bc27027aSMiklos Szeredi error = -EMLINK; 4596da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4597bc27027aSMiklos Szeredi goto out; 4598da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4599da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4600da1ce067SMiklos Szeredi goto out; 4601da1ce067SMiklos Szeredi } 4602da1ce067SMiklos Szeredi if (!is_dir) { 4603bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4604bc27027aSMiklos Szeredi if (error) 4605bc27027aSMiklos Szeredi goto out; 4606da1ce067SMiklos Szeredi } 4607da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4608bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4609bc27027aSMiklos Szeredi if (error) 4610bc27027aSMiklos Szeredi goto out; 4611bc27027aSMiklos Szeredi } 4612520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4613520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4614bc27027aSMiklos Szeredi if (error) 4615bc27027aSMiklos Szeredi goto out; 4616bc27027aSMiklos Szeredi 4617da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 46188767712fSAl Viro if (is_dir) { 46198767712fSAl Viro shrink_dcache_parent(new_dentry); 4620bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 46218767712fSAl Viro } 4622bc27027aSMiklos Szeredi dont_mount(new_dentry); 46238ed936b5SEric W. Biederman detach_mounts(new_dentry); 4624bc27027aSMiklos Szeredi } 4625da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4626da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4627bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4628da1ce067SMiklos Szeredi else 4629da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4630da1ce067SMiklos Szeredi } 4631bc27027aSMiklos Szeredi out: 4632da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4633bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4634bc27027aSMiklos Szeredi else if (target) 46355955102cSAl Viro inode_unlock(target); 4636bc27027aSMiklos Szeredi dput(new_dentry); 4637da1ce067SMiklos Szeredi if (!error) { 4638f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4639da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4640da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4641f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4642da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4643da1ce067SMiklos Szeredi } 4644da1ce067SMiklos Szeredi } 464549d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 46460eeca283SRobert Love 46471da177e4SLinus Torvalds return error; 46481da177e4SLinus Torvalds } 46494d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 46501da177e4SLinus Torvalds 4651ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4652ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 46531da177e4SLinus Torvalds { 46541da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 46551da177e4SLinus Torvalds struct dentry *trap; 4656f5beed75SAl Viro struct path old_path, new_path; 4657f5beed75SAl Viro struct qstr old_last, new_last; 4658f5beed75SAl Viro int old_type, new_type; 46598e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 466091a27b2aSJeff Layton struct filename *from; 466191a27b2aSJeff Layton struct filename *to; 4662f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4663c6a94284SJeff Layton bool should_retry = false; 46642ad94ae6SAl Viro int error; 4665520c8b16SMiklos Szeredi 46660d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4667da1ce067SMiklos Szeredi return -EINVAL; 4668da1ce067SMiklos Szeredi 46690d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 46700d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4671520c8b16SMiklos Szeredi return -EINVAL; 4672520c8b16SMiklos Szeredi 46730d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 46740d7a8555SMiklos Szeredi return -EPERM; 46750d7a8555SMiklos Szeredi 4676f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4677f5beed75SAl Viro target_flags = 0; 4678f5beed75SAl Viro 4679c6a94284SJeff Layton retry: 4680c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4681c1d4dd27SAl Viro &old_path, &old_last, &old_type); 468291a27b2aSJeff Layton if (IS_ERR(from)) { 468391a27b2aSJeff Layton error = PTR_ERR(from); 46841da177e4SLinus Torvalds goto exit; 468591a27b2aSJeff Layton } 46861da177e4SLinus Torvalds 4687c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4688c1d4dd27SAl Viro &new_path, &new_last, &new_type); 468991a27b2aSJeff Layton if (IS_ERR(to)) { 469091a27b2aSJeff Layton error = PTR_ERR(to); 46911da177e4SLinus Torvalds goto exit1; 469291a27b2aSJeff Layton } 46931da177e4SLinus Torvalds 46941da177e4SLinus Torvalds error = -EXDEV; 4695f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 46961da177e4SLinus Torvalds goto exit2; 46971da177e4SLinus Torvalds 46981da177e4SLinus Torvalds error = -EBUSY; 4699f5beed75SAl Viro if (old_type != LAST_NORM) 47001da177e4SLinus Torvalds goto exit2; 47011da177e4SLinus Torvalds 47020a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 47030a7c3937SMiklos Szeredi error = -EEXIST; 4704f5beed75SAl Viro if (new_type != LAST_NORM) 47051da177e4SLinus Torvalds goto exit2; 47061da177e4SLinus Torvalds 4707f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4708c30dabfeSJan Kara if (error) 4709c30dabfeSJan Kara goto exit2; 4710c30dabfeSJan Kara 47118e6d782cSJ. Bruce Fields retry_deleg: 4712f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 47131da177e4SLinus Torvalds 4714f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 47151da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 47161da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 47171da177e4SLinus Torvalds goto exit3; 47181da177e4SLinus Torvalds /* source must exist */ 47191da177e4SLinus Torvalds error = -ENOENT; 4720b18825a7SDavid Howells if (d_is_negative(old_dentry)) 47211da177e4SLinus Torvalds goto exit4; 4722f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 47231da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 47241da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 47251da177e4SLinus Torvalds goto exit4; 47260a7c3937SMiklos Szeredi error = -EEXIST; 47270a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 47280a7c3937SMiklos Szeredi goto exit5; 4729da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4730da1ce067SMiklos Szeredi error = -ENOENT; 4731da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4732da1ce067SMiklos Szeredi goto exit5; 4733da1ce067SMiklos Szeredi 4734da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4735da1ce067SMiklos Szeredi error = -ENOTDIR; 4736f5beed75SAl Viro if (new_last.name[new_last.len]) 4737da1ce067SMiklos Szeredi goto exit5; 4738da1ce067SMiklos Szeredi } 4739da1ce067SMiklos Szeredi } 47400a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 47410a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 47420a7c3937SMiklos Szeredi error = -ENOTDIR; 4743f5beed75SAl Viro if (old_last.name[old_last.len]) 47440a7c3937SMiklos Szeredi goto exit5; 4745f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 47460a7c3937SMiklos Szeredi goto exit5; 47470a7c3937SMiklos Szeredi } 47480a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 47490a7c3937SMiklos Szeredi error = -EINVAL; 47500a7c3937SMiklos Szeredi if (old_dentry == trap) 47510a7c3937SMiklos Szeredi goto exit5; 47521da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4753da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 47541da177e4SLinus Torvalds error = -ENOTEMPTY; 47551da177e4SLinus Torvalds if (new_dentry == trap) 47561da177e4SLinus Torvalds goto exit5; 47571da177e4SLinus Torvalds 4758f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4759f5beed75SAl Viro &new_path, new_dentry, flags); 4760be6d3e56SKentaro Takeda if (error) 4761c30dabfeSJan Kara goto exit5; 4762f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4763f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4764520c8b16SMiklos Szeredi &delegated_inode, flags); 47651da177e4SLinus Torvalds exit5: 47661da177e4SLinus Torvalds dput(new_dentry); 47671da177e4SLinus Torvalds exit4: 47681da177e4SLinus Torvalds dput(old_dentry); 47691da177e4SLinus Torvalds exit3: 4770f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 47718e6d782cSJ. Bruce Fields if (delegated_inode) { 47728e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 47738e6d782cSJ. Bruce Fields if (!error) 47748e6d782cSJ. Bruce Fields goto retry_deleg; 47758e6d782cSJ. Bruce Fields } 4776f5beed75SAl Viro mnt_drop_write(old_path.mnt); 47771da177e4SLinus Torvalds exit2: 4778c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4779c6a94284SJeff Layton should_retry = true; 4780f5beed75SAl Viro path_put(&new_path); 47812ad94ae6SAl Viro putname(to); 47821da177e4SLinus Torvalds exit1: 4783f5beed75SAl Viro path_put(&old_path); 47841da177e4SLinus Torvalds putname(from); 4785c6a94284SJeff Layton if (should_retry) { 4786c6a94284SJeff Layton should_retry = false; 4787c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4788c6a94284SJeff Layton goto retry; 4789c6a94284SJeff Layton } 47902ad94ae6SAl Viro exit: 47911da177e4SLinus Torvalds return error; 47921da177e4SLinus Torvalds } 47931da177e4SLinus Torvalds 4794ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4795ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4796ee81feb6SDominik Brodowski { 4797ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4798ee81feb6SDominik Brodowski } 4799ee81feb6SDominik Brodowski 4800520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4801520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4802520c8b16SMiklos Szeredi { 4803ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4804520c8b16SMiklos Szeredi } 4805520c8b16SMiklos Szeredi 4806a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 48075590ff0dSUlrich Drepper { 4808ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 48095590ff0dSUlrich Drepper } 48105590ff0dSUlrich Drepper 4811787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4812787fb6bcSMiklos Szeredi { 4813787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4814787fb6bcSMiklos Szeredi if (error) 4815787fb6bcSMiklos Szeredi return error; 4816787fb6bcSMiklos Szeredi 4817787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4818787fb6bcSMiklos Szeredi return -EPERM; 4819787fb6bcSMiklos Szeredi 4820787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4821787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4822787fb6bcSMiklos Szeredi } 4823787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4824787fb6bcSMiklos Szeredi 48255d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 48261da177e4SLinus Torvalds { 48275d826c84SAl Viro int len = PTR_ERR(link); 48281da177e4SLinus Torvalds if (IS_ERR(link)) 48291da177e4SLinus Torvalds goto out; 48301da177e4SLinus Torvalds 48311da177e4SLinus Torvalds len = strlen(link); 48321da177e4SLinus Torvalds if (len > (unsigned) buflen) 48331da177e4SLinus Torvalds len = buflen; 48341da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 48351da177e4SLinus Torvalds len = -EFAULT; 48361da177e4SLinus Torvalds out: 48371da177e4SLinus Torvalds return len; 48381da177e4SLinus Torvalds } 48391da177e4SLinus Torvalds 4840d60874cdSMiklos Szeredi /** 4841fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4842fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4843fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4844fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4845fd4a0edfSMiklos Szeredi * 4846fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4847fd4a0edfSMiklos Szeredi * 4848fd4a0edfSMiklos Szeredi * Does not call security hook. 4849fd4a0edfSMiklos Szeredi */ 4850fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4851fd4a0edfSMiklos Szeredi { 4852fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4853f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4854f2df5da6SAl Viro const char *link; 4855f2df5da6SAl Viro int res; 4856fd4a0edfSMiklos Szeredi 485776fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 485876fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 485976fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 486076fca90eSMiklos Szeredi 486176fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4862fd4a0edfSMiklos Szeredi return -EINVAL; 4863fd4a0edfSMiklos Szeredi 486476fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 486576fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 486676fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 486776fca90eSMiklos Szeredi } 486876fca90eSMiklos Szeredi 48694c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4870f2df5da6SAl Viro if (!link) { 4871f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4872f2df5da6SAl Viro if (IS_ERR(link)) 4873f2df5da6SAl Viro return PTR_ERR(link); 4874f2df5da6SAl Viro } 4875f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4876f2df5da6SAl Viro do_delayed_call(&done); 4877f2df5da6SAl Viro return res; 4878fd4a0edfSMiklos Szeredi } 4879fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 48801da177e4SLinus Torvalds 4881d60874cdSMiklos Szeredi /** 4882d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4883d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4884d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4885d60874cdSMiklos Szeredi * 4886d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4887d60874cdSMiklos Szeredi * 4888d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4889d60874cdSMiklos Szeredi * 4890d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4891d60874cdSMiklos Szeredi */ 4892d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4893d60874cdSMiklos Szeredi { 4894d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4895d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4896d60874cdSMiklos Szeredi 4897d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4898d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4899d60874cdSMiklos Szeredi if (!res) 4900d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4901d60874cdSMiklos Szeredi } 4902d60874cdSMiklos Szeredi return res; 4903d60874cdSMiklos Szeredi } 4904d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4905d60874cdSMiklos Szeredi 49061da177e4SLinus Torvalds /* get the link contents into pagecache */ 49076b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4908fceef393SAl Viro struct delayed_call *callback) 49091da177e4SLinus Torvalds { 4910ebd09abbSDuane Griffin char *kaddr; 49111da177e4SLinus Torvalds struct page *page; 49126b255391SAl Viro struct address_space *mapping = inode->i_mapping; 49136b255391SAl Viro 4914d3883d4fSAl Viro if (!dentry) { 4915d3883d4fSAl Viro page = find_get_page(mapping, 0); 4916d3883d4fSAl Viro if (!page) 49176b255391SAl Viro return ERR_PTR(-ECHILD); 4918d3883d4fSAl Viro if (!PageUptodate(page)) { 4919d3883d4fSAl Viro put_page(page); 4920d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4921d3883d4fSAl Viro } 4922d3883d4fSAl Viro } else { 4923090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 49241da177e4SLinus Torvalds if (IS_ERR(page)) 49256fe6900eSNick Piggin return (char*)page; 4926d3883d4fSAl Viro } 4927fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 492821fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 492921fc61c7SAl Viro kaddr = page_address(page); 49306b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4931ebd09abbSDuane Griffin return kaddr; 49321da177e4SLinus Torvalds } 49331da177e4SLinus Torvalds 49346b255391SAl Viro EXPORT_SYMBOL(page_get_link); 49351da177e4SLinus Torvalds 4936fceef393SAl Viro void page_put_link(void *arg) 49371da177e4SLinus Torvalds { 4938fceef393SAl Viro put_page(arg); 49391da177e4SLinus Torvalds } 49404d359507SAl Viro EXPORT_SYMBOL(page_put_link); 49411da177e4SLinus Torvalds 4942aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4943aa80deabSAl Viro { 4944fceef393SAl Viro DEFINE_DELAYED_CALL(done); 49456b255391SAl Viro int res = readlink_copy(buffer, buflen, 49466b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4947fceef393SAl Viro &done)); 4948fceef393SAl Viro do_delayed_call(&done); 4949aa80deabSAl Viro return res; 4950aa80deabSAl Viro } 4951aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4952aa80deabSAl Viro 495354566b2cSNick Piggin /* 495454566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 495554566b2cSNick Piggin */ 495654566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 49571da177e4SLinus Torvalds { 49581da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 49590adb25d2SKirill Korotaev struct page *page; 4960afddba49SNick Piggin void *fsdata; 4961beb497abSDmitriy Monakhov int err; 4962c718a975STetsuo Handa unsigned int flags = 0; 496354566b2cSNick Piggin if (nofs) 496454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 49651da177e4SLinus Torvalds 49667e53cac4SNeilBrown retry: 4967afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 496854566b2cSNick Piggin flags, &page, &fsdata); 49691da177e4SLinus Torvalds if (err) 4970afddba49SNick Piggin goto fail; 4971afddba49SNick Piggin 497221fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4973afddba49SNick Piggin 4974afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4975afddba49SNick Piggin page, fsdata); 49761da177e4SLinus Torvalds if (err < 0) 49771da177e4SLinus Torvalds goto fail; 4978afddba49SNick Piggin if (err < len-1) 4979afddba49SNick Piggin goto retry; 4980afddba49SNick Piggin 49811da177e4SLinus Torvalds mark_inode_dirty(inode); 49821da177e4SLinus Torvalds return 0; 49831da177e4SLinus Torvalds fail: 49841da177e4SLinus Torvalds return err; 49851da177e4SLinus Torvalds } 49864d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 49871da177e4SLinus Torvalds 49880adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 49890adb25d2SKirill Korotaev { 49900adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4991c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 49920adb25d2SKirill Korotaev } 49934d359507SAl Viro EXPORT_SYMBOL(page_symlink); 49940adb25d2SKirill Korotaev 499592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 49966b255391SAl Viro .get_link = page_get_link, 49971da177e4SLinus Torvalds }; 49981da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4999