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; 4949883d185SAl Viro unsigned seq, m_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 1796adb21d2bSAleksa Sarai /* 1797adb21d2bSAleksa Sarai * Scoped-lookup flags resolving ".." is not currently safe -- 1798adb21d2bSAleksa Sarai * races can cause our parent to have moved outside of the root 1799adb21d2bSAleksa Sarai * and us to skip over it. 1800adb21d2bSAleksa Sarai */ 1801adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 1802adb21d2bSAleksa Sarai return -EXDEV; 1803740a1678SAleksa Sarai if (!nd->root.mnt) { 1804740a1678SAleksa Sarai error = set_root(nd); 1805740a1678SAleksa Sarai if (error) 1806740a1678SAleksa Sarai return error; 1807740a1678SAleksa Sarai } 18089856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 180970291aecSAl Viro return follow_dotdot_rcu(nd); 18109856fa1bSAl Viro } else 1811397d425dSEric W. Biederman return follow_dotdot(nd); 18129856fa1bSAl Viro } 18139856fa1bSAl Viro return 0; 18149856fa1bSAl Viro } 18159856fa1bSAl Viro 1816181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1817181548c0SAl Viro struct inode *inode, unsigned seq) 1818d63ff28fSAl Viro { 1819626de996SAl Viro int error; 18201cf2665bSAl Viro struct saved *last; 1821756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1822626de996SAl Viro path_to_nameidata(link, nd); 1823626de996SAl Viro return -ELOOP; 1824626de996SAl Viro } 1825bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1826cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1827cd179f44SAl Viro mntget(link->mnt); 18287973387aSAl Viro } 1829626de996SAl Viro error = nd_alloc_stack(nd); 1830626de996SAl Viro if (unlikely(error)) { 1831bc40aee0SAl Viro if (error == -ECHILD) { 1832ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1833ad1633a1SAl Viro drop_links(nd); 1834ad1633a1SAl Viro nd->depth = 0; 1835ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1836ad1633a1SAl Viro nd->path.mnt = NULL; 1837ad1633a1SAl Viro nd->path.dentry = NULL; 1838ad1633a1SAl Viro rcu_read_unlock(); 18394675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1840bc40aee0SAl Viro error = nd_alloc_stack(nd); 1841bc40aee0SAl Viro } 1842bc40aee0SAl Viro if (error) { 1843cd179f44SAl Viro path_put(link); 1844626de996SAl Viro return error; 1845626de996SAl Viro } 1846bc40aee0SAl Viro } 1847626de996SAl Viro 1848ab104923SAl Viro last = nd->stack + nd->depth++; 18491cf2665bSAl Viro last->link = *link; 1850fceef393SAl Viro clear_delayed_call(&last->done); 1851fceef393SAl Viro nd->link_inode = inode; 18520450b2d1SAl Viro last->seq = seq; 1853d63ff28fSAl Viro return 1; 1854d63ff28fSAl Viro } 1855d63ff28fSAl Viro 18568f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 185731d66bcdSAl Viro 18583ddcd056SLinus Torvalds /* 18593ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 18603ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 18613ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 18623ddcd056SLinus Torvalds * for the common case. 18633ddcd056SLinus Torvalds */ 18648f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 18658f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 18663ddcd056SLinus Torvalds { 186731d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 186831d66bcdSAl Viro put_link(nd); 18698f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 18708f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 18718f64fb1cSAl Viro /* not a symlink or should not follow */ 18728f64fb1cSAl Viro path_to_nameidata(path, nd); 18738f64fb1cSAl Viro nd->inode = inode; 18748f64fb1cSAl Viro nd->seq = seq; 1875d63ff28fSAl Viro return 0; 18768f64fb1cSAl Viro } 1877a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1878a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 18798f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1880a7f77542SAl Viro return -ECHILD; 1881a7f77542SAl Viro } 18828f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 18833ddcd056SLinus Torvalds } 18843ddcd056SLinus Torvalds 18854693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1886ce57dfc1SAl Viro { 1887caa85634SAl Viro struct path path; 1888ce57dfc1SAl Viro struct inode *inode; 1889254cf582SAl Viro unsigned seq; 1890ce57dfc1SAl Viro int err; 1891ce57dfc1SAl Viro /* 1892ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1893ce57dfc1SAl Viro * to be able to know about the current root directory and 1894ce57dfc1SAl Viro * parent relationships. 1895ce57dfc1SAl Viro */ 18964693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18974693a547SAl Viro err = handle_dots(nd, nd->last_type); 18981c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18994693a547SAl Viro put_link(nd); 19004693a547SAl Viro return err; 19014693a547SAl Viro } 1902254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1903e9742b53SAl Viro if (unlikely(err <= 0)) { 1904697f514dSMiklos Szeredi if (err < 0) 1905f0a9ba70SAl Viro return err; 1906e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1907e3c13928SAl Viro nd->flags); 1908e3c13928SAl Viro if (IS_ERR(path.dentry)) 1909e3c13928SAl Viro return PTR_ERR(path.dentry); 19107500c38aSAl Viro 1911e3c13928SAl Viro path.mnt = nd->path.mnt; 1912e3c13928SAl Viro err = follow_managed(&path, nd); 1913e3c13928SAl Viro if (unlikely(err < 0)) 1914f0a9ba70SAl Viro return err; 1915697f514dSMiklos Szeredi 1916254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1917d4565649SAl Viro inode = d_backing_inode(path.dentry); 1918766c4cbfSAl Viro } 1919697f514dSMiklos Szeredi 19208f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1921ce57dfc1SAl Viro } 1922ce57dfc1SAl Viro 19231da177e4SLinus Torvalds /* 1924bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1925bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1926bfcfaa77SLinus Torvalds * 1927bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1928bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1929bfcfaa77SLinus Torvalds * fast. 1930bfcfaa77SLinus Torvalds * 1931bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1932bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1933bfcfaa77SLinus Torvalds * crossing operation. 1934bfcfaa77SLinus Torvalds * 1935bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1936bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1937bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1938bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1939bfcfaa77SLinus Torvalds */ 1940bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1941bfcfaa77SLinus Torvalds 1942f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1943bfcfaa77SLinus Torvalds 1944468a9428SGeorge Spelvin #ifdef HASH_MIX 1945bfcfaa77SLinus Torvalds 1946468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1947468a9428SGeorge Spelvin 1948468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 19492a18da7aSGeorge Spelvin /* 19502a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 19512a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 19522a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19532a18da7aSGeorge Spelvin * and no temporaries. 19542a18da7aSGeorge Spelvin * 19552a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19562a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19572a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19582a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19592a18da7aSGeorge Spelvin * 19602a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19612a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19622a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19632a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19642a18da7aSGeorge Spelvin * 19652a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19662a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19672a18da7aSGeorge Spelvin * toggling any given output bit. 19682a18da7aSGeorge Spelvin * 19692a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19702a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19712a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19722a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19732a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19742a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19752a18da7aSGeorge Spelvin * Perfect: 8192 258048 19762a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19772a18da7aSGeorge Spelvin */ 19782a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19792a18da7aSGeorge Spelvin ( x ^= (a), \ 19802a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19812a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19822a18da7aSGeorge Spelvin y *= 9 ) 1983bfcfaa77SLinus Torvalds 19840fed3ac8SGeorge Spelvin /* 19852a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19862a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19872a18da7aSGeorge Spelvin * work done before the hash value is used. 19880fed3ac8SGeorge Spelvin */ 19892a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19900fed3ac8SGeorge Spelvin { 19912a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19922a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19932a18da7aSGeorge Spelvin return y >> 32; 19940fed3ac8SGeorge Spelvin } 19950fed3ac8SGeorge Spelvin 1996bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1997bfcfaa77SLinus Torvalds 19982a18da7aSGeorge Spelvin /* 19992a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 20002a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 20012a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 20022a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 20032a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 20042a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 20052a18da7aSGeorge Spelvin * Perfect: 2048 31744 20062a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 20072a18da7aSGeorge Spelvin */ 20082a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 20092a18da7aSGeorge Spelvin ( x ^= (a), \ 20102a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 20112a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 20122a18da7aSGeorge Spelvin y *= 9 ) 2013bfcfaa77SLinus Torvalds 20142a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 20150fed3ac8SGeorge Spelvin { 20162a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 20172a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 20180fed3ac8SGeorge Spelvin } 20190fed3ac8SGeorge Spelvin 2020bfcfaa77SLinus Torvalds #endif 2021bfcfaa77SLinus Torvalds 20222a18da7aSGeorge Spelvin /* 20232a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 20242a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 20252a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 20262a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 20272a18da7aSGeorge Spelvin * finds the delimiter after the name. 20282a18da7aSGeorge Spelvin */ 20298387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 2030bfcfaa77SLinus Torvalds { 20318387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 2032bfcfaa77SLinus Torvalds 2033bfcfaa77SLinus Torvalds for (;;) { 2034fcfd2fbfSGeorge Spelvin if (!len) 2035fcfd2fbfSGeorge Spelvin goto done; 2036e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 2037bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2038bfcfaa77SLinus Torvalds break; 20392a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2040bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2041bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2042bfcfaa77SLinus Torvalds } 20432a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2044bfcfaa77SLinus Torvalds done: 20452a18da7aSGeorge Spelvin return fold_hash(x, y); 2046bfcfaa77SLinus Torvalds } 2047bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2048bfcfaa77SLinus Torvalds 2049fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20508387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2051fcfd2fbfSGeorge Spelvin { 20528387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20538387ff25SLinus Torvalds unsigned long adata, mask, len; 2054fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2055fcfd2fbfSGeorge Spelvin 20568387ff25SLinus Torvalds len = 0; 20578387ff25SLinus Torvalds goto inside; 20588387ff25SLinus Torvalds 2059fcfd2fbfSGeorge Spelvin do { 20602a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2061fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20628387ff25SLinus Torvalds inside: 2063fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2064fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2065fcfd2fbfSGeorge Spelvin 2066fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2067fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20682a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2069fcfd2fbfSGeorge Spelvin 20702a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2071fcfd2fbfSGeorge Spelvin } 2072fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2073fcfd2fbfSGeorge Spelvin 2074bfcfaa77SLinus Torvalds /* 2075bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2076d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2077bfcfaa77SLinus Torvalds */ 20788387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2079bfcfaa77SLinus Torvalds { 20808387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20818387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 208236126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2083bfcfaa77SLinus Torvalds 20848387ff25SLinus Torvalds len = 0; 20858387ff25SLinus Torvalds goto inside; 20868387ff25SLinus Torvalds 2087bfcfaa77SLinus Torvalds do { 20882a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2089bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20908387ff25SLinus Torvalds inside: 2091e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 209236126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 209336126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2094bfcfaa77SLinus Torvalds 209536126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 209636126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 209736126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20982a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 209936126f8fSLinus Torvalds 21002a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2101bfcfaa77SLinus Torvalds } 2102bfcfaa77SLinus Torvalds 21032a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2104bfcfaa77SLinus Torvalds 2105fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 21068387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 21070145acc2SLinus Torvalds { 21088387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 21090145acc2SLinus Torvalds while (len--) 2110fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 21110145acc2SLinus Torvalds return end_name_hash(hash); 21120145acc2SLinus Torvalds } 2113ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 21140145acc2SLinus Torvalds 2115fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 21168387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2117fcfd2fbfSGeorge Spelvin { 21188387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2119fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2120fcfd2fbfSGeorge Spelvin 2121fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2122e0ab7af9SGeorge Spelvin while (c) { 2123fcfd2fbfSGeorge Spelvin len++; 2124fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2125fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2126e0ab7af9SGeorge Spelvin } 2127fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2128fcfd2fbfSGeorge Spelvin } 2129f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2130fcfd2fbfSGeorge Spelvin 21313ddcd056SLinus Torvalds /* 2132200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2133200e9ef7SLinus Torvalds * one character. 2134200e9ef7SLinus Torvalds */ 21358387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2136200e9ef7SLinus Torvalds { 21378387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2138200e9ef7SLinus Torvalds unsigned long len = 0, c; 2139200e9ef7SLinus Torvalds 2140200e9ef7SLinus Torvalds c = (unsigned char)*name; 2141200e9ef7SLinus Torvalds do { 2142200e9ef7SLinus Torvalds len++; 2143200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2144200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2145200e9ef7SLinus Torvalds } while (c && c != '/'); 2146d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2147200e9ef7SLinus Torvalds } 2148200e9ef7SLinus Torvalds 2149bfcfaa77SLinus Torvalds #endif 2150bfcfaa77SLinus Torvalds 2151200e9ef7SLinus Torvalds /* 21521da177e4SLinus Torvalds * Name resolution. 2153ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2154ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21551da177e4SLinus Torvalds * 2156ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2157ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21581da177e4SLinus Torvalds */ 21596de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21601da177e4SLinus Torvalds { 21611da177e4SLinus Torvalds int err; 21621da177e4SLinus Torvalds 21639b5858e9SAl Viro if (IS_ERR(name)) 21649b5858e9SAl Viro return PTR_ERR(name); 21651da177e4SLinus Torvalds while (*name=='/') 21661da177e4SLinus Torvalds name++; 21671da177e4SLinus Torvalds if (!*name) 21689e18f10aSAl Viro return 0; 21691da177e4SLinus Torvalds 21701da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21711da177e4SLinus Torvalds for(;;) { 2172d6bb3e90SLinus Torvalds u64 hash_len; 2173fe479a58SAl Viro int type; 21741da177e4SLinus Torvalds 217552094c8aSAl Viro err = may_lookup(nd); 21761da177e4SLinus Torvalds if (err) 21773595e234SAl Viro return err; 21781da177e4SLinus Torvalds 21798387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21801da177e4SLinus Torvalds 2181fe479a58SAl Viro type = LAST_NORM; 2182d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2183fe479a58SAl Viro case 2: 2184200e9ef7SLinus Torvalds if (name[1] == '.') { 2185fe479a58SAl Viro type = LAST_DOTDOT; 218616c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 218716c2cd71SAl Viro } 2188fe479a58SAl Viro break; 2189fe479a58SAl Viro case 1: 2190fe479a58SAl Viro type = LAST_DOT; 2191fe479a58SAl Viro } 21925a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21935a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 219416c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21955a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2196a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2197da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21985a202bcdSAl Viro if (err < 0) 21993595e234SAl Viro return err; 2200d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2201d6bb3e90SLinus Torvalds name = this.name; 22025a202bcdSAl Viro } 22035a202bcdSAl Viro } 2204fe479a58SAl Viro 2205d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2206d6bb3e90SLinus Torvalds nd->last.name = name; 22075f4a6a69SAl Viro nd->last_type = type; 22085f4a6a69SAl Viro 2209d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2210d6bb3e90SLinus Torvalds if (!*name) 2211bdf6cbf1SAl Viro goto OK; 2212200e9ef7SLinus Torvalds /* 2213200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2214200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2215200e9ef7SLinus Torvalds */ 2216200e9ef7SLinus Torvalds do { 2217d6bb3e90SLinus Torvalds name++; 2218d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 22198620c238SAl Viro if (unlikely(!*name)) { 22208620c238SAl Viro OK: 2221368ee9baSAl Viro /* pathname body, done */ 22228620c238SAl Viro if (!nd->depth) 22238620c238SAl Viro return 0; 22248620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2225368ee9baSAl Viro /* trailing symlink, done */ 22268620c238SAl Viro if (!name) 22278620c238SAl Viro return 0; 22288620c238SAl Viro /* last component of nested symlink */ 22298f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 22301c4ff1a8SAl Viro } else { 22311c4ff1a8SAl Viro /* not the last component */ 22328f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 22338620c238SAl Viro } 2234ce57dfc1SAl Viro if (err < 0) 22353595e234SAl Viro return err; 2236fe479a58SAl Viro 2237ce57dfc1SAl Viro if (err) { 2238626de996SAl Viro const char *s = get_link(nd); 22395a460275SAl Viro 2240a1c83681SViresh Kumar if (IS_ERR(s)) 22413595e234SAl Viro return PTR_ERR(s); 2242172a39a0SAl Viro err = 0; 224312b09578SAl Viro if (unlikely(!s)) { 224412b09578SAl Viro /* jumped */ 2245b9ff4429SAl Viro put_link(nd); 224612b09578SAl Viro } else { 2247071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 224832cd7468SAl Viro name = s; 22499e18f10aSAl Viro continue; 225048c8b0c5SAl Viro } 225131e6b01fSNick Piggin } 225297242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 225397242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 22544675ac39SAl Viro if (unlazy_walk(nd)) 225597242f99SAl Viro return -ECHILD; 225697242f99SAl Viro } 22573595e234SAl Viro return -ENOTDIR; 22585f4a6a69SAl Viro } 2259ce57dfc1SAl Viro } 226097242f99SAl Viro } 22611da177e4SLinus Torvalds 2262edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2263c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 226431e6b01fSNick Piggin { 2265740a1678SAleksa Sarai int error; 2266c8a53ee5SAl Viro const char *s = nd->name->name; 226731e6b01fSNick Piggin 2268c0eb027eSLinus Torvalds if (!*s) 2269c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2270edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2271edc2b1daSAl Viro rcu_read_lock(); 2272c0eb027eSLinus Torvalds 227331e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2274980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 227531e6b01fSNick Piggin nd->depth = 0; 22765b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2277b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2278b18825a7SDavid Howells struct inode *inode = root->d_inode; 227993893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2280368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22815b6ca027SAl Viro nd->path = nd->root; 22825b6ca027SAl Viro nd->inode = inode; 22835b6ca027SAl Viro if (flags & LOOKUP_RCU) { 22845b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 22858f47a016SAl Viro nd->root_seq = nd->seq; 228648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 22875b6ca027SAl Viro } else { 22885b6ca027SAl Viro path_get(&nd->path); 22895b6ca027SAl Viro } 2290368ee9baSAl Viro return s; 22915b6ca027SAl Viro } 22925b6ca027SAl Viro 229331e6b01fSNick Piggin nd->root.mnt = NULL; 2294248fb5b9SAl Viro nd->path.mnt = NULL; 2295248fb5b9SAl Viro nd->path.dentry = NULL; 229631e6b01fSNick Piggin 229748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2298740a1678SAleksa Sarai 2299740a1678SAleksa Sarai /* Figure out the starting path and root (if needed). */ 2300fd2f7cb5SAl Viro if (*s == '/') { 2301740a1678SAleksa Sarai error = nd_jump_root(nd); 2302740a1678SAleksa Sarai if (unlikely(error)) 2303740a1678SAleksa Sarai return ERR_PTR(error); 2304ef55d917SAl Viro return s; 2305c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2306e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 230731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2308c28cc364SNick Piggin unsigned seq; 230931e6b01fSNick Piggin 2310c28cc364SNick Piggin do { 2311c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 231231e6b01fSNick Piggin nd->path = fs->pwd; 2313ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2314c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2315c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2316e41f7d4eSAl Viro } else { 2317e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2318ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2319e41f7d4eSAl Viro } 232031e6b01fSNick Piggin } else { 2321582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2322c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 232331e6b01fSNick Piggin struct dentry *dentry; 232431e6b01fSNick Piggin 23252903ff01SAl Viro if (!f.file) 2326368ee9baSAl Viro return ERR_PTR(-EBADF); 232731e6b01fSNick Piggin 23282903ff01SAl Viro dentry = f.file->f_path.dentry; 232931e6b01fSNick Piggin 2330edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 23312903ff01SAl Viro fdput(f); 2332368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2333f52e0c11SAl Viro } 23342903ff01SAl Viro 23352903ff01SAl Viro nd->path = f.file->f_path; 2336e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 233734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 233834a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 23395590ff0dSUlrich Drepper } else { 23402903ff01SAl Viro path_get(&nd->path); 234134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 23421da177e4SLinus Torvalds } 234334a26b99SAl Viro fdput(f); 2344e41f7d4eSAl Viro } 2345adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2346adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2347adb21d2bSAleksa Sarai nd->root = nd->path; 2348adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2349adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2350adb21d2bSAleksa Sarai } else { 2351adb21d2bSAleksa Sarai path_get(&nd->root); 2352adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2353adb21d2bSAleksa Sarai } 2354adb21d2bSAleksa Sarai } 2355adb21d2bSAleksa Sarai return s; 23569b4a9b14SAl Viro } 23579b4a9b14SAl Viro 23583bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 235995fa25d9SAl Viro { 236095fa25d9SAl Viro const char *s; 2361fec2fa24SAl Viro int error = may_follow_link(nd); 2362deb106c6SAl Viro if (unlikely(error)) 23633bdba28bSAl Viro return ERR_PTR(error); 236495fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2365fab51e8aSAl Viro nd->stack[0].name = NULL; 23663b2e7f75SAl Viro s = get_link(nd); 2367deb106c6SAl Viro return s ? s : ""; 236895fa25d9SAl Viro } 236995fa25d9SAl Viro 2370caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2371bd92d7feSAl Viro { 2372bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2373bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2374bd92d7feSAl Viro 2375bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 23761c4ff1a8SAl Viro return walk_component(nd, 0); 2377bd92d7feSAl Viro } 2378bd92d7feSAl Viro 23794f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23804f757f3cSAl Viro { 23814f757f3cSAl Viro struct path path = nd->path; 23824f757f3cSAl Viro struct inode *inode = nd->inode; 23834f757f3cSAl Viro unsigned seq = nd->seq; 23844f757f3cSAl Viro int err; 23854f757f3cSAl Viro 23864f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 23874f757f3cSAl Viro /* 23884f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 23894f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 23904f757f3cSAl Viro * if we simply redo everything in non-RCU mode 23914f757f3cSAl Viro */ 23924f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 23934f757f3cSAl Viro return -ECHILD; 23944f757f3cSAl Viro } else { 23954f757f3cSAl Viro dget(path.dentry); 23964f757f3cSAl Viro err = follow_managed(&path, nd); 23974f757f3cSAl Viro if (unlikely(err < 0)) 23984f757f3cSAl Viro return err; 23994f757f3cSAl Viro inode = d_backing_inode(path.dentry); 24004f757f3cSAl Viro seq = 0; 24014f757f3cSAl Viro } 24024f757f3cSAl Viro path_to_nameidata(&path, nd); 24034f757f3cSAl Viro nd->inode = inode; 24044f757f3cSAl Viro nd->seq = seq; 24054f757f3cSAl Viro return 0; 24064f757f3cSAl Viro } 24074f757f3cSAl Viro 24089b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2409c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 24109b4a9b14SAl Viro { 2411c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2412bd92d7feSAl Viro int err; 241331e6b01fSNick Piggin 24149b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 24154f757f3cSAl Viro err = handle_lookup_down(nd); 24165f336e72SAl Viro if (unlikely(err < 0)) 24175f336e72SAl Viro s = ERR_PTR(err); 24184f757f3cSAl Viro } 24194f757f3cSAl Viro 24203bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 24213bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 24223bdba28bSAl Viro s = trailing_symlink(nd); 2423bd92d7feSAl Viro } 24249f1fafeeSAl Viro if (!err) 24259f1fafeeSAl Viro err = complete_walk(nd); 2426bd92d7feSAl Viro 2427deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2428deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2429bd23a539SAl Viro err = -ENOTDIR; 2430625b6d10SAl Viro if (!err) { 2431625b6d10SAl Viro *path = nd->path; 2432625b6d10SAl Viro nd->path.mnt = NULL; 2433625b6d10SAl Viro nd->path.dentry = NULL; 2434625b6d10SAl Viro } 2435deb106c6SAl Viro terminate_walk(nd); 2436bd92d7feSAl Viro return err; 243731e6b01fSNick Piggin } 243831e6b01fSNick Piggin 243931d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 24409ad1aaa6SAl Viro struct path *path, struct path *root) 2441873f1eedSJeff Layton { 2442894bc8c4SAl Viro int retval; 24439883d185SAl Viro struct nameidata nd; 2444abc9f5beSAl Viro if (IS_ERR(name)) 2445abc9f5beSAl Viro return PTR_ERR(name); 24469ad1aaa6SAl Viro if (unlikely(root)) { 24479ad1aaa6SAl Viro nd.root = *root; 24489ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 24499ad1aaa6SAl Viro } 24509883d185SAl Viro set_nameidata(&nd, dfd, name); 2451c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2452873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2453c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2454873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2455c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2456873f1eedSJeff Layton 2457873f1eedSJeff Layton if (likely(!retval)) 2458ff0ebee2SAl Viro audit_inode(name, path->dentry, 0); 24599883d185SAl Viro restore_nameidata(); 2460e4bd1c1aSAl Viro putname(name); 2461873f1eedSJeff Layton return retval; 2462873f1eedSJeff Layton } 2463873f1eedSJeff Layton 24648bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2465c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2466391172c4SAl Viro struct path *parent) 24678bcb77faSAl Viro { 2468c8a53ee5SAl Viro const char *s = path_init(nd, flags); 24699b5858e9SAl Viro int err = link_path_walk(s, nd); 24708bcb77faSAl Viro if (!err) 24718bcb77faSAl Viro err = complete_walk(nd); 2472391172c4SAl Viro if (!err) { 2473391172c4SAl Viro *parent = nd->path; 2474391172c4SAl Viro nd->path.mnt = NULL; 2475391172c4SAl Viro nd->path.dentry = NULL; 2476391172c4SAl Viro } 2477deb106c6SAl Viro terminate_walk(nd); 24788bcb77faSAl Viro return err; 24798bcb77faSAl Viro } 24808bcb77faSAl Viro 24815c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2482391172c4SAl Viro unsigned int flags, struct path *parent, 2483391172c4SAl Viro struct qstr *last, int *type) 24848bcb77faSAl Viro { 24858bcb77faSAl Viro int retval; 24869883d185SAl Viro struct nameidata nd; 24878bcb77faSAl Viro 24885c31b6ceSAl Viro if (IS_ERR(name)) 24895c31b6ceSAl Viro return name; 24909883d185SAl Viro set_nameidata(&nd, dfd, name); 2491c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 24928bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2493c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 24948bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2495c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2496391172c4SAl Viro if (likely(!retval)) { 2497391172c4SAl Viro *last = nd.last; 2498391172c4SAl Viro *type = nd.last_type; 2499c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 25005c31b6ceSAl Viro } else { 25015c31b6ceSAl Viro putname(name); 25025c31b6ceSAl Viro name = ERR_PTR(retval); 2503391172c4SAl Viro } 25049883d185SAl Viro restore_nameidata(); 25055c31b6ceSAl Viro return name; 25068bcb77faSAl Viro } 25078bcb77faSAl Viro 250879714f72SAl Viro /* does lookup, returns the object with parent locked */ 250979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 25105590ff0dSUlrich Drepper { 25115c31b6ceSAl Viro struct filename *filename; 25125c31b6ceSAl Viro struct dentry *d; 2513391172c4SAl Viro struct qstr last; 2514391172c4SAl Viro int type; 251551689104SPaul Moore 25165c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 25175c31b6ceSAl Viro &last, &type); 251851689104SPaul Moore if (IS_ERR(filename)) 251951689104SPaul Moore return ERR_CAST(filename); 25205c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2521391172c4SAl Viro path_put(path); 25225c31b6ceSAl Viro putname(filename); 25235c31b6ceSAl Viro return ERR_PTR(-EINVAL); 252479714f72SAl Viro } 25255955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2526391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 252779714f72SAl Viro if (IS_ERR(d)) { 25285955102cSAl Viro inode_unlock(path->dentry->d_inode); 2529391172c4SAl Viro path_put(path); 253079714f72SAl Viro } 253151689104SPaul Moore putname(filename); 253279714f72SAl Viro return d; 25335590ff0dSUlrich Drepper } 25345590ff0dSUlrich Drepper 2535d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2536d1811465SAl Viro { 2537abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2538abc9f5beSAl Viro flags, path, NULL); 2539d1811465SAl Viro } 25404d359507SAl Viro EXPORT_SYMBOL(kern_path); 2541d1811465SAl Viro 254216f18200SJosef 'Jeff' Sipek /** 254316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 254416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 254516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 254616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 254716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2548e0a01249SAl Viro * @path: pointer to struct path to fill 254916f18200SJosef 'Jeff' Sipek */ 255016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 255116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2552e0a01249SAl Viro struct path *path) 255316f18200SJosef 'Jeff' Sipek { 25549ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 25559ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2556abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2557abc9f5beSAl Viro flags , path, &root); 255816f18200SJosef 'Jeff' Sipek } 25594d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 256016f18200SJosef 'Jeff' Sipek 25613c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 25623c95f0dcSAl Viro int len, struct qstr *this) 25633c95f0dcSAl Viro { 25643c95f0dcSAl Viro this->name = name; 25653c95f0dcSAl Viro this->len = len; 25663c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 25673c95f0dcSAl Viro if (!len) 25683c95f0dcSAl Viro return -EACCES; 25693c95f0dcSAl Viro 25703c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 25713c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 25723c95f0dcSAl Viro return -EACCES; 25733c95f0dcSAl Viro } 25743c95f0dcSAl Viro 25753c95f0dcSAl Viro while (len--) { 25763c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 25773c95f0dcSAl Viro if (c == '/' || c == '\0') 25783c95f0dcSAl Viro return -EACCES; 25793c95f0dcSAl Viro } 25803c95f0dcSAl Viro /* 25813c95f0dcSAl Viro * See if the low-level filesystem might want 25823c95f0dcSAl Viro * to use its own hash.. 25833c95f0dcSAl Viro */ 25843c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 25853c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 25863c95f0dcSAl Viro if (err < 0) 25873c95f0dcSAl Viro return err; 25883c95f0dcSAl Viro } 25893c95f0dcSAl Viro 25903c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 25913c95f0dcSAl Viro } 25923c95f0dcSAl Viro 2593eead1911SChristoph Hellwig /** 25940da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25950da0b7fdSDavid Howells * @name: pathname component to lookup 25960da0b7fdSDavid Howells * @base: base directory to lookup from 25970da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25980da0b7fdSDavid Howells * 25990da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 26000da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 26010da0b7fdSDavid Howells * 26020da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 26030da0b7fdSDavid Howells * not be called by generic code. 26040da0b7fdSDavid Howells * 26050da0b7fdSDavid Howells * The caller must hold base->i_mutex. 26060da0b7fdSDavid Howells */ 26070da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 26080da0b7fdSDavid Howells { 26090da0b7fdSDavid Howells struct qstr this; 26100da0b7fdSDavid Howells int err; 26110da0b7fdSDavid Howells 26120da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 26130da0b7fdSDavid Howells 26140da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 26150da0b7fdSDavid Howells if (err) 26160da0b7fdSDavid Howells return ERR_PTR(err); 26170da0b7fdSDavid Howells 26180da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 26190da0b7fdSDavid Howells } 26200da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 26210da0b7fdSDavid Howells 26220da0b7fdSDavid Howells /** 2623a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2624eead1911SChristoph Hellwig * @name: pathname component to lookup 2625eead1911SChristoph Hellwig * @base: base directory to lookup from 2626eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2627eead1911SChristoph Hellwig * 2628a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 26299e7543e9SAl Viro * not be called by generic code. 2630bbddca8eSNeilBrown * 2631bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2632eead1911SChristoph Hellwig */ 2633057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2634057f6c01SJames Morris { 26358613a209SAl Viro struct dentry *dentry; 2636057f6c01SJames Morris struct qstr this; 2637cda309deSMiklos Szeredi int err; 2638057f6c01SJames Morris 26395955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 26402f9092e1SDavid Woodhouse 26413c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2642cda309deSMiklos Szeredi if (err) 2643cda309deSMiklos Szeredi return ERR_PTR(err); 2644cda309deSMiklos Szeredi 26458613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 26468613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2647057f6c01SJames Morris } 26484d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2649057f6c01SJames Morris 2650bbddca8eSNeilBrown /** 2651bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2652bbddca8eSNeilBrown * @name: pathname component to lookup 2653bbddca8eSNeilBrown * @base: base directory to lookup from 2654bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2655bbddca8eSNeilBrown * 2656bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2657bbddca8eSNeilBrown * not be called by generic code. 2658bbddca8eSNeilBrown * 2659bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2660bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2661bbddca8eSNeilBrown */ 2662bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2663bbddca8eSNeilBrown struct dentry *base, int len) 2664bbddca8eSNeilBrown { 2665bbddca8eSNeilBrown struct qstr this; 2666bbddca8eSNeilBrown int err; 266720d00ee8SLinus Torvalds struct dentry *ret; 2668bbddca8eSNeilBrown 26693c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2670bbddca8eSNeilBrown if (err) 2671bbddca8eSNeilBrown return ERR_PTR(err); 2672bbddca8eSNeilBrown 267320d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 267420d00ee8SLinus Torvalds if (!ret) 267520d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 267620d00ee8SLinus Torvalds return ret; 2677bbddca8eSNeilBrown } 2678bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2679bbddca8eSNeilBrown 26806c2d4798SAl Viro /* 26816c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 26826c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 26836c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 26846c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 26856c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 26866c2d4798SAl Viro * this one avoids such problems. 26876c2d4798SAl Viro */ 26886c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 26896c2d4798SAl Viro struct dentry *base, int len) 26906c2d4798SAl Viro { 26916c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 26922fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 26936c2d4798SAl Viro dput(ret); 26946c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26956c2d4798SAl Viro } 26966c2d4798SAl Viro return ret; 26976c2d4798SAl Viro } 26986c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26996c2d4798SAl Viro 2700eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2701eedf265aSEric W. Biederman int path_pts(struct path *path) 2702eedf265aSEric W. Biederman { 2703eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2704eedf265aSEric W. Biederman * the input path. 2705eedf265aSEric W. Biederman */ 2706eedf265aSEric W. Biederman struct dentry *child, *parent; 2707eedf265aSEric W. Biederman struct qstr this; 2708eedf265aSEric W. Biederman int ret; 2709eedf265aSEric W. Biederman 2710eedf265aSEric W. Biederman ret = path_parent_directory(path); 2711eedf265aSEric W. Biederman if (ret) 2712eedf265aSEric W. Biederman return ret; 2713eedf265aSEric W. Biederman 2714eedf265aSEric W. Biederman parent = path->dentry; 2715eedf265aSEric W. Biederman this.name = "pts"; 2716eedf265aSEric W. Biederman this.len = 3; 2717eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2718eedf265aSEric W. Biederman if (!child) 2719eedf265aSEric W. Biederman return -ENOENT; 2720eedf265aSEric W. Biederman 2721eedf265aSEric W. Biederman path->dentry = child; 2722eedf265aSEric W. Biederman dput(parent); 2723eedf265aSEric W. Biederman follow_mount(path); 2724eedf265aSEric W. Biederman return 0; 2725eedf265aSEric W. Biederman } 2726eedf265aSEric W. Biederman #endif 2727eedf265aSEric W. Biederman 27281fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 27291fa1e7f6SAndy Whitcroft struct path *path, int *empty) 27301da177e4SLinus Torvalds { 2731abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2732abc9f5beSAl Viro flags, path, NULL); 27331da177e4SLinus Torvalds } 2734b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 27351fa1e7f6SAndy Whitcroft 27368033426eSJeff Layton /** 2737197df04cSAl Viro * mountpoint_last - look up last component for umount 27388033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 27398033426eSJeff Layton * 27408033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 27418033426eSJeff Layton * need to resolve the path without doing any revalidation. 27428033426eSJeff Layton * 27438033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 27448033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 27458033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 27468033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 27478033426eSJeff Layton * bogus and it doesn't exist. 27488033426eSJeff Layton * 27498033426eSJeff Layton * Returns: 27508033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2751ba8f4613SAl Viro * lookup found a negative dentry. 27528033426eSJeff Layton * 2753ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2754ba8f4613SAl Viro * symlink that needs to be followed. 27558033426eSJeff Layton * 27568033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2757ba8f4613SAl Viro * that needs to be followed. 27588033426eSJeff Layton */ 27598033426eSJeff Layton static int 2760ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 27618033426eSJeff Layton { 27628033426eSJeff Layton int error = 0; 27638033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2764ba8f4613SAl Viro struct path path; 27658033426eSJeff Layton 276635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 276735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 27684675ac39SAl Viro if (unlazy_walk(nd)) 2769deb106c6SAl Viro return -ECHILD; 27708033426eSJeff Layton } 27718033426eSJeff Layton 27728033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 27738033426eSJeff Layton 27748033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 27758033426eSJeff Layton error = handle_dots(nd, nd->last_type); 277635759521SAl Viro if (error) 2777deb106c6SAl Viro return error; 2778ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2779949a852eSAl Viro } else { 2780ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2781ba8f4613SAl Viro if (!path.dentry) { 27828033426eSJeff Layton /* 2783949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2784949a852eSAl Viro * cache, so that means that this dentry is probably 2785949a852eSAl Viro * a symlink or the path doesn't actually point 2786949a852eSAl Viro * to a mounted dentry. 27878033426eSJeff Layton */ 2788ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2789949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2790ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2791ba8f4613SAl Viro return PTR_ERR(path.dentry); 27928033426eSJeff Layton } 2793bcceeebaSDave Jones } 27942fa6b1e0SAl Viro if (d_flags_negative(smp_load_acquire(&path.dentry->d_flags))) { 2795ba8f4613SAl Viro dput(path.dentry); 2796deb106c6SAl Viro return -ENOENT; 279735759521SAl Viro } 2798ba8f4613SAl Viro path.mnt = nd->path.mnt; 27998f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 28008033426eSJeff Layton } 28018033426eSJeff Layton 28028033426eSJeff Layton /** 2803197df04cSAl Viro * path_mountpoint - look up a path to be umounted 28042a78b857SMasanari Iida * @nd: lookup context 28058033426eSJeff Layton * @flags: lookup flags 2806c8a53ee5SAl Viro * @path: pointer to container for result 28078033426eSJeff Layton * 28088033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2809606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 28108033426eSJeff Layton */ 28118033426eSJeff Layton static int 2812c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 28138033426eSJeff Layton { 2814c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2815368ee9baSAl Viro int err; 28169b5858e9SAl Viro 28173bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2818ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 28193bdba28bSAl Viro s = trailing_symlink(nd); 28203bdba28bSAl Viro } 2821ba8f4613SAl Viro if (!err) { 2822ba8f4613SAl Viro *path = nd->path; 2823ba8f4613SAl Viro nd->path.mnt = NULL; 2824ba8f4613SAl Viro nd->path.dentry = NULL; 2825ba8f4613SAl Viro follow_mount(path); 2826ba8f4613SAl Viro } 2827deb106c6SAl Viro terminate_walk(nd); 28288033426eSJeff Layton return err; 28298033426eSJeff Layton } 28308033426eSJeff Layton 28312d864651SAl Viro static int 2832668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 28332d864651SAl Viro unsigned int flags) 28342d864651SAl Viro { 28359883d185SAl Viro struct nameidata nd; 2836cbaab2dbSAl Viro int error; 2837668696dcSAl Viro if (IS_ERR(name)) 2838668696dcSAl Viro return PTR_ERR(name); 28399883d185SAl Viro set_nameidata(&nd, dfd, name); 2840c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 28412d864651SAl Viro if (unlikely(error == -ECHILD)) 2842c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 28432d864651SAl Viro if (unlikely(error == -ESTALE)) 2844c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 28452d864651SAl Viro if (likely(!error)) 2846c9b07eabSAl Viro audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL); 28479883d185SAl Viro restore_nameidata(); 2848668696dcSAl Viro putname(name); 28492d864651SAl Viro return error; 28502d864651SAl Viro } 28512d864651SAl Viro 28528033426eSJeff Layton /** 2853197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 28548033426eSJeff Layton * @dfd: directory file descriptor 28558033426eSJeff Layton * @name: pathname from userland 28568033426eSJeff Layton * @flags: lookup flags 28578033426eSJeff Layton * @path: pointer to container to hold result 28588033426eSJeff Layton * 28598033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 28608033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 28618033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 28628033426eSJeff Layton * and avoid revalidating the last component. 28638033426eSJeff Layton * 28648033426eSJeff Layton * Returns 0 and populates "path" on success. 28658033426eSJeff Layton */ 28668033426eSJeff Layton int 2867197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 28688033426eSJeff Layton struct path *path) 28698033426eSJeff Layton { 2870cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 28718033426eSJeff Layton } 28728033426eSJeff Layton 28732d864651SAl Viro int 28742d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 28752d864651SAl Viro unsigned int flags) 28762d864651SAl Viro { 2877cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 28782d864651SAl Viro } 28792d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 28802d864651SAl Viro 2881cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 28821da177e4SLinus Torvalds { 28838e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2884da9592edSDavid Howells 28858e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 28861da177e4SLinus Torvalds return 0; 28878e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 28881da177e4SLinus Torvalds return 0; 288923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 28901da177e4SLinus Torvalds } 2891cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 28921da177e4SLinus Torvalds 28931da177e4SLinus Torvalds /* 28941da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 28951da177e4SLinus Torvalds * whether the type of victim is right. 28961da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 28971da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 28981da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 28991da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 29001da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 29011da177e4SLinus Torvalds * a. be owner of dir, or 29021da177e4SLinus Torvalds * b. be owner of victim, or 29031da177e4SLinus Torvalds * c. have CAP_FOWNER capability 29041da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 29051da177e4SLinus Torvalds * links pointing to it. 29060bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 29070bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 29080bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 29090bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 29100bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 29111da177e4SLinus Torvalds * nfs_async_unlink(). 29121da177e4SLinus Torvalds */ 2913b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 29141da177e4SLinus Torvalds { 291563afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 29161da177e4SLinus Torvalds int error; 29171da177e4SLinus Torvalds 2918b18825a7SDavid Howells if (d_is_negative(victim)) 29191da177e4SLinus Torvalds return -ENOENT; 2920b18825a7SDavid Howells BUG_ON(!inode); 29211da177e4SLinus Torvalds 29221da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2923593d1ce8SEric W. Biederman 2924593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2925593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2926593d1ce8SEric W. Biederman return -EOVERFLOW; 2927593d1ce8SEric W. Biederman 29284fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 29291da177e4SLinus Torvalds 2930f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 29311da177e4SLinus Torvalds if (error) 29321da177e4SLinus Torvalds return error; 29331da177e4SLinus Torvalds if (IS_APPEND(dir)) 29341da177e4SLinus Torvalds return -EPERM; 2935b18825a7SDavid Howells 2936b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 29370bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 29381da177e4SLinus Torvalds return -EPERM; 29391da177e4SLinus Torvalds if (isdir) { 294044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 29411da177e4SLinus Torvalds return -ENOTDIR; 29421da177e4SLinus Torvalds if (IS_ROOT(victim)) 29431da177e4SLinus Torvalds return -EBUSY; 294444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 29451da177e4SLinus Torvalds return -EISDIR; 29461da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 29471da177e4SLinus Torvalds return -ENOENT; 29481da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 29491da177e4SLinus Torvalds return -EBUSY; 29501da177e4SLinus Torvalds return 0; 29511da177e4SLinus Torvalds } 29521da177e4SLinus Torvalds 29531da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 29541da177e4SLinus Torvalds * dir. 29551da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 29561da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 29571da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2958036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2959036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2960036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 29611da177e4SLinus Torvalds */ 2962a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 29631da177e4SLinus Torvalds { 2964036d5236SEric W. Biederman struct user_namespace *s_user_ns; 296514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 29661da177e4SLinus Torvalds if (child->d_inode) 29671da177e4SLinus Torvalds return -EEXIST; 29681da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 29691da177e4SLinus Torvalds return -ENOENT; 2970036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2971036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2972036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2973036d5236SEric W. Biederman return -EOVERFLOW; 2974f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 29751da177e4SLinus Torvalds } 29761da177e4SLinus Torvalds 29771da177e4SLinus Torvalds /* 29781da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 29791da177e4SLinus Torvalds */ 29801da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 29811da177e4SLinus Torvalds { 29821da177e4SLinus Torvalds struct dentry *p; 29831da177e4SLinus Torvalds 29841da177e4SLinus Torvalds if (p1 == p2) { 29855955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 29861da177e4SLinus Torvalds return NULL; 29871da177e4SLinus Torvalds } 29881da177e4SLinus Torvalds 2989fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 29901da177e4SLinus Torvalds 2991e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2992e2761a11SOGAWA Hirofumi if (p) { 29935955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 29945955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 29951da177e4SLinus Torvalds return p; 29961da177e4SLinus Torvalds } 29971da177e4SLinus Torvalds 2998e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2999e2761a11SOGAWA Hirofumi if (p) { 30005955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30015955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 30021da177e4SLinus Torvalds return p; 30031da177e4SLinus Torvalds } 30041da177e4SLinus Torvalds 30055955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30065955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 30071da177e4SLinus Torvalds return NULL; 30081da177e4SLinus Torvalds } 30094d359507SAl Viro EXPORT_SYMBOL(lock_rename); 30101da177e4SLinus Torvalds 30111da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 30121da177e4SLinus Torvalds { 30135955102cSAl Viro inode_unlock(p1->d_inode); 30141da177e4SLinus Torvalds if (p1 != p2) { 30155955102cSAl Viro inode_unlock(p2->d_inode); 3016fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 30171da177e4SLinus Torvalds } 30181da177e4SLinus Torvalds } 30194d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 30201da177e4SLinus Torvalds 30214acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 3022312b63fbSAl Viro bool want_excl) 30231da177e4SLinus Torvalds { 3024a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 30251da177e4SLinus Torvalds if (error) 30261da177e4SLinus Torvalds return error; 30271da177e4SLinus Torvalds 3028acfa4380SAl Viro if (!dir->i_op->create) 30291da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 30301da177e4SLinus Torvalds mode &= S_IALLUGO; 30311da177e4SLinus Torvalds mode |= S_IFREG; 30321da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 30331da177e4SLinus Torvalds if (error) 30341da177e4SLinus Torvalds return error; 3035312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 3036a74574aaSStephen Smalley if (!error) 3037f38aa942SAmy Griffis fsnotify_create(dir, dentry); 30381da177e4SLinus Torvalds return error; 30391da177e4SLinus Torvalds } 30404d359507SAl Viro EXPORT_SYMBOL(vfs_create); 30411da177e4SLinus Torvalds 30428e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 30438e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 30448e6c848eSAl Viro void *arg) 30458e6c848eSAl Viro { 30468e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 30478e6c848eSAl Viro int error = may_create(dir, dentry); 30488e6c848eSAl Viro if (error) 30498e6c848eSAl Viro return error; 30508e6c848eSAl Viro 30518e6c848eSAl Viro mode &= S_IALLUGO; 30528e6c848eSAl Viro mode |= S_IFREG; 30538e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 30548e6c848eSAl Viro if (error) 30558e6c848eSAl Viro return error; 30568e6c848eSAl Viro error = f(dentry, mode, arg); 30578e6c848eSAl Viro if (!error) 30588e6c848eSAl Viro fsnotify_create(dir, dentry); 30598e6c848eSAl Viro return error; 30608e6c848eSAl Viro } 30618e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 30628e6c848eSAl Viro 3063a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 3064a2982cc9SEric W. Biederman { 3065a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 3066a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 3067a2982cc9SEric W. Biederman } 3068a2982cc9SEric W. Biederman 3069f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 30701da177e4SLinus Torvalds { 30713fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 30721da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 30731da177e4SLinus Torvalds int error; 30741da177e4SLinus Torvalds 30751da177e4SLinus Torvalds if (!inode) 30761da177e4SLinus Torvalds return -ENOENT; 30771da177e4SLinus Torvalds 3078c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 3079c8fe8f30SChristoph Hellwig case S_IFLNK: 30801da177e4SLinus Torvalds return -ELOOP; 3081c8fe8f30SChristoph Hellwig case S_IFDIR: 3082c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 30831da177e4SLinus Torvalds return -EISDIR; 3084c8fe8f30SChristoph Hellwig break; 3085c8fe8f30SChristoph Hellwig case S_IFBLK: 3086c8fe8f30SChristoph Hellwig case S_IFCHR: 3087a2982cc9SEric W. Biederman if (!may_open_dev(path)) 30881da177e4SLinus Torvalds return -EACCES; 3089c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 3090c8fe8f30SChristoph Hellwig case S_IFIFO: 3091c8fe8f30SChristoph Hellwig case S_IFSOCK: 30921da177e4SLinus Torvalds flag &= ~O_TRUNC; 3093c8fe8f30SChristoph Hellwig break; 30944a3fd211SDave Hansen } 3095b41572e9SDave Hansen 309662fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 3097b41572e9SDave Hansen if (error) 3098b41572e9SDave Hansen return error; 30996146f0d5SMimi Zohar 31001da177e4SLinus Torvalds /* 31011da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 31021da177e4SLinus Torvalds */ 31031da177e4SLinus Torvalds if (IS_APPEND(inode)) { 31048737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 31057715b521SAl Viro return -EPERM; 31061da177e4SLinus Torvalds if (flag & O_TRUNC) 31077715b521SAl Viro return -EPERM; 31081da177e4SLinus Torvalds } 31091da177e4SLinus Torvalds 31101da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 31112e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 31127715b521SAl Viro return -EPERM; 31131da177e4SLinus Torvalds 3114f3c7691eSJ. Bruce Fields return 0; 31157715b521SAl Viro } 31167715b521SAl Viro 3117e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 31187715b521SAl Viro { 3119f0bb5aafSAl Viro const struct path *path = &filp->f_path; 31207715b521SAl Viro struct inode *inode = path->dentry->d_inode; 31217715b521SAl Viro int error = get_write_access(inode); 31221da177e4SLinus Torvalds if (error) 31237715b521SAl Viro return error; 31241da177e4SLinus Torvalds /* 31251da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 31261da177e4SLinus Torvalds */ 3127d7a06983SJeff Layton error = locks_verify_locked(filp); 3128be6d3e56SKentaro Takeda if (!error) 3129ea0d3ab2STetsuo Handa error = security_path_truncate(path); 31301da177e4SLinus Torvalds if (!error) { 31317715b521SAl Viro error = do_truncate(path->dentry, 0, 3132d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 3133e1181ee6SJeff Layton filp); 31341da177e4SLinus Torvalds } 31351da177e4SLinus Torvalds put_write_access(inode); 3136acd0c935SMimi Zohar return error; 31371da177e4SLinus Torvalds } 31381da177e4SLinus Torvalds 3139d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 3140d57999e1SDave Hansen { 31418a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 31428a5e929dSAl Viro flag--; 3143d57999e1SDave Hansen return flag; 3144d57999e1SDave Hansen } 3145d57999e1SDave Hansen 3146d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 3147d18e9008SMiklos Szeredi { 31481328c727SSeth Forshee struct user_namespace *s_user_ns; 3149d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 3150d18e9008SMiklos Szeredi if (error) 3151d18e9008SMiklos Szeredi return error; 3152d18e9008SMiklos Szeredi 31531328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 31541328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 31551328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 31561328c727SSeth Forshee return -EOVERFLOW; 31571328c727SSeth Forshee 3158d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 3159d18e9008SMiklos Szeredi if (error) 3160d18e9008SMiklos Szeredi return error; 3161d18e9008SMiklos Szeredi 3162d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3163d18e9008SMiklos Szeredi } 3164d18e9008SMiklos Szeredi 31651acf0af9SDavid Howells /* 31661acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 31671acf0af9SDavid Howells * dentry. 31681acf0af9SDavid Howells * 31691acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 31701acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 31711acf0af9SDavid Howells * 317200a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 317300a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 317400a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 31751acf0af9SDavid Howells * 31761acf0af9SDavid Howells * Returns an error code otherwise. 31771acf0af9SDavid Howells */ 31782675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 317930d90494SAl Viro struct path *path, struct file *file, 3180015c3bbcSMiklos Szeredi const struct open_flags *op, 31813ec2eef1SAl Viro int open_flag, umode_t mode) 3182d18e9008SMiklos Szeredi { 3183d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3184d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3185d18e9008SMiklos Szeredi int error; 3186d18e9008SMiklos Szeredi 3187384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3188d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3189d18e9008SMiklos Szeredi 3190d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3191d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3192d18e9008SMiklos Szeredi 319330d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 319430d90494SAl Viro file->f_path.mnt = nd->path.mnt; 31950fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 319644907d79SAl Viro open_to_namei_flags(open_flag), mode); 31976fbd0714SAl Viro d_lookup_done(dentry); 3198384f26e2SAl Viro if (!error) { 319964e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 3200d18e9008SMiklos Szeredi /* 3201384f26e2SAl Viro * We didn't have the inode before the open, so check open 3202384f26e2SAl Viro * permission here. 3203d18e9008SMiklos Szeredi */ 3204384f26e2SAl Viro int acc_mode = op->acc_mode; 320573a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 320603da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 320703da633aSAl Viro fsnotify_create(dir, dentry); 320862fb4a15SAl Viro acc_mode = 0; 320903da633aSAl Viro } 32102675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3211384f26e2SAl Viro if (WARN_ON(error > 0)) 3212384f26e2SAl Viro error = -EINVAL; 321364e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3214d18e9008SMiklos Szeredi error = -EIO; 3215384f26e2SAl Viro } else { 3216d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3217d18e9008SMiklos Szeredi dput(dentry); 3218d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 321910c64ceaSAl Viro } 322073a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3221d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3222a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3223a01e718fSAl Viro error = -ENOENT; 3224a01e718fSAl Viro } else { 3225d18e9008SMiklos Szeredi path->dentry = dentry; 3226d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 322700a07c15SAl Viro return 0; 3228d18e9008SMiklos Szeredi } 3229d18e9008SMiklos Szeredi } 3230a01e718fSAl Viro } 3231d18e9008SMiklos Szeredi dput(dentry); 3232d18e9008SMiklos Szeredi return error; 3233d18e9008SMiklos Szeredi } 3234d18e9008SMiklos Szeredi 323531e6b01fSNick Piggin /* 32361acf0af9SDavid Howells * Look up and maybe create and open the last component. 3237d58ffd35SMiklos Szeredi * 323800a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3239d58ffd35SMiklos Szeredi * 324000a07c15SAl Viro * Returns 0 on success, that is, if 324100a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 324200a07c15SAl Viro * the file was not completely opened at this time, though lookups and 324300a07c15SAl Viro * creations were performed. 324400a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 324500a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 324600a07c15SAl Viro * hadn't been specified. 32471acf0af9SDavid Howells * 324800a07c15SAl Viro * An error code is returned on failure. 3249d58ffd35SMiklos Szeredi */ 32502675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 325130d90494SAl Viro struct file *file, 3252d58ffd35SMiklos Szeredi const struct open_flags *op, 32533ec2eef1SAl Viro bool got_write) 3254d58ffd35SMiklos Szeredi { 3255d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 325654ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 32571643b43fSAl Viro int open_flag = op->open_flag; 3258d58ffd35SMiklos Szeredi struct dentry *dentry; 32591643b43fSAl Viro int error, create_error = 0; 32601643b43fSAl Viro umode_t mode = op->mode; 32616fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3262d58ffd35SMiklos Szeredi 3263ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3264ce8644fcSAl Viro return -ENOENT; 3265d58ffd35SMiklos Szeredi 326673a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 32676fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 32686fbd0714SAl Viro for (;;) { 32696fbd0714SAl Viro if (!dentry) { 32706fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3271d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 32722675a4ebSAl Viro return PTR_ERR(dentry); 32736fbd0714SAl Viro } 32746fbd0714SAl Viro if (d_in_lookup(dentry)) 32756fbd0714SAl Viro break; 3276d58ffd35SMiklos Szeredi 32776fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 32786fbd0714SAl Viro if (likely(error > 0)) 32796fbd0714SAl Viro break; 32806fbd0714SAl Viro if (error) 32816fbd0714SAl Viro goto out_dput; 32826fbd0714SAl Viro d_invalidate(dentry); 32836fbd0714SAl Viro dput(dentry); 32846fbd0714SAl Viro dentry = NULL; 32856fbd0714SAl Viro } 32866fbd0714SAl Viro if (dentry->d_inode) { 3287d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3288d18e9008SMiklos Szeredi goto out_no_open; 32896c51e513SAl Viro } 3290d18e9008SMiklos Szeredi 32911643b43fSAl Viro /* 32921643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 32931643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 32941643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 32951643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 32961643b43fSAl Viro * 32971643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 32981643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 32991643b43fSAl Viro */ 33001643b43fSAl Viro if (open_flag & O_CREAT) { 33011643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 33021643b43fSAl Viro mode &= ~current_umask(); 33031643b43fSAl Viro if (unlikely(!got_write)) { 33041643b43fSAl Viro create_error = -EROFS; 33051643b43fSAl Viro open_flag &= ~O_CREAT; 33061643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 33071643b43fSAl Viro goto no_open; 33081643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 33091643b43fSAl Viro } else { 33101643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 33111643b43fSAl Viro if (create_error) { 33121643b43fSAl Viro open_flag &= ~O_CREAT; 33131643b43fSAl Viro if (open_flag & O_EXCL) 33141643b43fSAl Viro goto no_open; 33151643b43fSAl Viro } 33161643b43fSAl Viro } 33171643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 33181643b43fSAl Viro unlikely(!got_write)) { 33191643b43fSAl Viro /* 33201643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 33211643b43fSAl Viro * back to lookup + open 33221643b43fSAl Viro */ 33231643b43fSAl Viro goto no_open; 3324d18e9008SMiklos Szeredi } 3325d18e9008SMiklos Szeredi 33261643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 33271643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 33283ec2eef1SAl Viro mode); 33291643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 33301643b43fSAl Viro error = create_error; 33311643b43fSAl Viro return error; 33321643b43fSAl Viro } 333354ef4872SMiklos Szeredi 33341643b43fSAl Viro no_open: 33356fbd0714SAl Viro if (d_in_lookup(dentry)) { 333612fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 333712fa5e24SAl Viro nd->flags); 33386fbd0714SAl Viro d_lookup_done(dentry); 333912fa5e24SAl Viro if (unlikely(res)) { 334012fa5e24SAl Viro if (IS_ERR(res)) { 334112fa5e24SAl Viro error = PTR_ERR(res); 334212fa5e24SAl Viro goto out_dput; 334312fa5e24SAl Viro } 334412fa5e24SAl Viro dput(dentry); 334512fa5e24SAl Viro dentry = res; 334612fa5e24SAl Viro } 334754ef4872SMiklos Szeredi } 334854ef4872SMiklos Szeredi 3349d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 33501643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 335173a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3352ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3353ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3354ce8644fcSAl Viro error = -EACCES; 3355d58ffd35SMiklos Szeredi goto out_dput; 335664894cf8SAl Viro } 3357ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 33581643b43fSAl Viro open_flag & O_EXCL); 3359d58ffd35SMiklos Szeredi if (error) 3360d58ffd35SMiklos Szeredi goto out_dput; 3361ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3362d58ffd35SMiklos Szeredi } 33631643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 33641643b43fSAl Viro error = create_error; 3365d58ffd35SMiklos Szeredi goto out_dput; 3366d58ffd35SMiklos Szeredi } 3367d18e9008SMiklos Szeredi out_no_open: 3368d58ffd35SMiklos Szeredi path->dentry = dentry; 3369d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 337000a07c15SAl Viro return 0; 3371d58ffd35SMiklos Szeredi 3372d58ffd35SMiklos Szeredi out_dput: 3373d58ffd35SMiklos Szeredi dput(dentry); 33742675a4ebSAl Viro return error; 3375d58ffd35SMiklos Szeredi } 3376d58ffd35SMiklos Szeredi 3377d58ffd35SMiklos Szeredi /* 3378fe2d35ffSAl Viro * Handle the last step of open() 337931e6b01fSNick Piggin */ 3380896475d5SAl Viro static int do_last(struct nameidata *nd, 33813ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3382fb1cc555SAl Viro { 3383a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3384ca344a89SAl Viro int open_flag = op->open_flag; 338577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 338664894cf8SAl Viro bool got_write = false; 3387bcda7652SAl Viro int acc_mode = op->acc_mode; 3388254cf582SAl Viro unsigned seq; 3389a1eb3315SMiklos Szeredi struct inode *inode; 3390896475d5SAl Viro struct path path; 339116c2cd71SAl Viro int error; 3392fb1cc555SAl Viro 3393c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3394c3e380b0SAl Viro nd->flags |= op->intent; 3395c3e380b0SAl Viro 3396bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3397fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3398deb106c6SAl Viro if (unlikely(error)) 33992675a4ebSAl Viro return error; 3400e83db167SMiklos Szeredi goto finish_open; 34011f36f774SAl Viro } 3402a2c36b45SAl Viro 3403ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3404fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3405fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3406fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3407254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3408e9742b53SAl Viro if (likely(error > 0)) 340971574865SMiklos Szeredi goto finish_lookup; 341071574865SMiklos Szeredi 3411ce57dfc1SAl Viro if (error < 0) 3412deb106c6SAl Viro return error; 3413a1eb3315SMiklos Szeredi 341437d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 34156583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3416b6183df7SMiklos Szeredi } else { 3417fe2d35ffSAl Viro /* create side of things */ 3418a3fbbde7SAl Viro /* 3419b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3420b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3421b6183df7SMiklos Szeredi * about to look up 3422a3fbbde7SAl Viro */ 34239f1fafeeSAl Viro error = complete_walk(nd); 3424e8bb73dfSAl Viro if (error) 34252675a4ebSAl Viro return error; 3426fe2d35ffSAl Viro 3427c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 34281f36f774SAl Viro /* trailing slashes? */ 3429deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3430deb106c6SAl Viro return -EISDIR; 3431b6183df7SMiklos Szeredi } 34321f36f774SAl Viro 34339cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 343464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 343564894cf8SAl Viro if (!error) 343664894cf8SAl Viro got_write = true; 343764894cf8SAl Viro /* 343864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 343964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 344064894cf8SAl Viro * dropping this one anyway. 344164894cf8SAl Viro */ 344264894cf8SAl Viro } 34439cf843e3SAl Viro if (open_flag & O_CREAT) 34445955102cSAl Viro inode_lock(dir->d_inode); 34459cf843e3SAl Viro else 34469cf843e3SAl Viro inode_lock_shared(dir->d_inode); 34473ec2eef1SAl Viro error = lookup_open(nd, &path, file, op, got_write); 34489cf843e3SAl Viro if (open_flag & O_CREAT) 34495955102cSAl Viro inode_unlock(dir->d_inode); 34509cf843e3SAl Viro else 34519cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3452fb1cc555SAl Viro 34532675a4ebSAl Viro if (error) 3454d58ffd35SMiklos Szeredi goto out; 34556c0d46c4SAl Viro 345600a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 345773a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3458496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 345977d660a8SMiklos Szeredi will_truncate = false; 3460d18e9008SMiklos Szeredi 346176ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3462d18e9008SMiklos Szeredi goto opened; 3463d18e9008SMiklos Szeredi } 3464d18e9008SMiklos Szeredi 346573a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 34669b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3467ca344a89SAl Viro open_flag &= ~O_TRUNC; 346877d660a8SMiklos Szeredi will_truncate = false; 346962fb4a15SAl Viro acc_mode = 0; 3470896475d5SAl Viro path_to_nameidata(&path, nd); 3471e83db167SMiklos Szeredi goto finish_open_created; 3472fb1cc555SAl Viro } 3473fb1cc555SAl Viro 3474fb1cc555SAl Viro /* 3475d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3476d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3477d18e9008SMiklos Szeredi * necessary...) 3478d18e9008SMiklos Szeredi */ 347964894cf8SAl Viro if (got_write) { 3480d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 348164894cf8SAl Viro got_write = false; 3482d18e9008SMiklos Szeredi } 3483d18e9008SMiklos Szeredi 3484e6ec03a2SAl Viro error = follow_managed(&path, nd); 3485e6ec03a2SAl Viro if (unlikely(error < 0)) 3486e6ec03a2SAl Viro return error; 3487e6ec03a2SAl Viro 34886583fe22SAl Viro /* 34896583fe22SAl Viro * create/update audit record if it already exists. 34906583fe22SAl Viro */ 34916583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 34926583fe22SAl Viro 3493deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3494deb106c6SAl Viro path_to_nameidata(&path, nd); 3495deb106c6SAl Viro return -EEXIST; 3496deb106c6SAl Viro } 3497fb1cc555SAl Viro 3498254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3499d4565649SAl Viro inode = d_backing_inode(path.dentry); 3500766c4cbfSAl Viro finish_lookup: 35018f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3502deb106c6SAl Viro if (unlikely(error)) 3503d63ff28fSAl Viro return error; 3504bc77daa7SAl Viro finish_open: 35058f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3506a3fbbde7SAl Viro error = complete_walk(nd); 3507fac7d191SAl Viro if (error) 35082675a4ebSAl Viro return error; 350976ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 351030aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3511fb1cc555SAl Viro error = -EISDIR; 351230aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 35132675a4ebSAl Viro goto out; 351430aba665SSalvatore Mesoraca error = may_create_in_sticky(dir, 351530aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 351630aba665SSalvatore Mesoraca if (unlikely(error)) 351730aba665SSalvatore Mesoraca goto out; 351830aba665SSalvatore Mesoraca } 3519af2f5542SMiklos Szeredi error = -ENOTDIR; 352044b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 35212675a4ebSAl Viro goto out; 35224bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 352377d660a8SMiklos Szeredi will_truncate = false; 35246c0d46c4SAl Viro 35250f9d1a10SAl Viro if (will_truncate) { 35260f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 35270f9d1a10SAl Viro if (error) 35282675a4ebSAl Viro goto out; 352964894cf8SAl Viro got_write = true; 35300f9d1a10SAl Viro } 3531e83db167SMiklos Szeredi finish_open_created: 3532bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3533ca344a89SAl Viro if (error) 35342675a4ebSAl Viro goto out; 3535aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3536ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3537fac7d191SAl Viro if (error) 3538015c3bbcSMiklos Szeredi goto out; 3539a8277b9bSMiklos Szeredi opened: 35406035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3541fe9ec829SAl Viro if (!error && will_truncate) 35422675a4ebSAl Viro error = handle_truncate(file); 3543ca344a89SAl Viro out: 3544c80567c8SAl Viro if (unlikely(error > 0)) { 3545c80567c8SAl Viro WARN_ON(1); 3546c80567c8SAl Viro error = -EINVAL; 3547c80567c8SAl Viro } 354864894cf8SAl Viro if (got_write) 35490f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 35502675a4ebSAl Viro return error; 3551fb1cc555SAl Viro } 3552fb1cc555SAl Viro 3553af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3554af7bd4dcSAmir Goldstein { 3555af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3556af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3557af7bd4dcSAmir Goldstein struct inode *inode; 3558af7bd4dcSAmir Goldstein int error; 3559af7bd4dcSAmir Goldstein 3560af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3561af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3562af7bd4dcSAmir Goldstein if (error) 3563af7bd4dcSAmir Goldstein goto out_err; 3564af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3565af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3566af7bd4dcSAmir Goldstein goto out_err; 3567af7bd4dcSAmir Goldstein error = -ENOMEM; 3568cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3569af7bd4dcSAmir Goldstein if (unlikely(!child)) 3570af7bd4dcSAmir Goldstein goto out_err; 3571af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3572af7bd4dcSAmir Goldstein if (error) 3573af7bd4dcSAmir Goldstein goto out_err; 3574af7bd4dcSAmir Goldstein error = -ENOENT; 3575af7bd4dcSAmir Goldstein inode = child->d_inode; 3576af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3577af7bd4dcSAmir Goldstein goto out_err; 3578af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3579af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3580af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3581af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3582af7bd4dcSAmir Goldstein } 3583fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3584af7bd4dcSAmir Goldstein return child; 3585af7bd4dcSAmir Goldstein 3586af7bd4dcSAmir Goldstein out_err: 3587af7bd4dcSAmir Goldstein dput(child); 3588af7bd4dcSAmir Goldstein return ERR_PTR(error); 3589af7bd4dcSAmir Goldstein } 3590af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3591af7bd4dcSAmir Goldstein 3592c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 359360545d0dSAl Viro const struct open_flags *op, 35943ec2eef1SAl Viro struct file *file) 359560545d0dSAl Viro { 3596625b6d10SAl Viro struct dentry *child; 3597625b6d10SAl Viro struct path path; 3598c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 359960545d0dSAl Viro if (unlikely(error)) 360060545d0dSAl Viro return error; 3601625b6d10SAl Viro error = mnt_want_write(path.mnt); 360260545d0dSAl Viro if (unlikely(error)) 360360545d0dSAl Viro goto out; 3604af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3605af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3606684e73beSHirofumi Nakagawa if (IS_ERR(child)) 360760545d0dSAl Viro goto out2; 3608625b6d10SAl Viro dput(path.dentry); 3609625b6d10SAl Viro path.dentry = child; 3610c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 361169a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 361262fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 361360545d0dSAl Viro if (error) 361460545d0dSAl Viro goto out2; 3615625b6d10SAl Viro file->f_path.mnt = path.mnt; 3616be12af3eSAl Viro error = finish_open(file, child, NULL); 361760545d0dSAl Viro out2: 3618625b6d10SAl Viro mnt_drop_write(path.mnt); 361960545d0dSAl Viro out: 3620625b6d10SAl Viro path_put(&path); 362160545d0dSAl Viro return error; 362260545d0dSAl Viro } 362360545d0dSAl Viro 36246ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 36256ac08709SAl Viro { 36266ac08709SAl Viro struct path path; 36276ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 36286ac08709SAl Viro if (!error) { 36296ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3630ae2bb293SAl Viro error = vfs_open(&path, file); 36316ac08709SAl Viro path_put(&path); 36326ac08709SAl Viro } 36336ac08709SAl Viro return error; 36346ac08709SAl Viro } 36356ac08709SAl Viro 3636c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3637c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 36381da177e4SLinus Torvalds { 363930d90494SAl Viro struct file *file; 364013aab428SAl Viro int error; 364131e6b01fSNick Piggin 3642ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 36431afc99beSAl Viro if (IS_ERR(file)) 36441afc99beSAl Viro return file; 364531e6b01fSNick Piggin 3646bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 36473ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 36485f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 36496ac08709SAl Viro error = do_o_path(nd, flags, file); 36505f336e72SAl Viro } else { 36515f336e72SAl Viro const char *s = path_init(nd, flags); 36523bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 36533ec2eef1SAl Viro (error = do_last(nd, file, op)) > 0) { 365473d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 36553bdba28bSAl Viro s = trailing_symlink(nd); 36563bdba28bSAl Viro } 3657deb106c6SAl Viro terminate_walk(nd); 36585f336e72SAl Viro } 36597c1c01ecSAl Viro if (likely(!error)) { 3660aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 36617c1c01ecSAl Viro return file; 36627c1c01ecSAl Viro WARN_ON(1); 36637c1c01ecSAl Viro error = -EINVAL; 3664015c3bbcSMiklos Szeredi } 36657c1c01ecSAl Viro fput(file); 36662675a4ebSAl Viro if (error == -EOPENSTALE) { 36672675a4ebSAl Viro if (flags & LOOKUP_RCU) 36682675a4ebSAl Viro error = -ECHILD; 36692675a4ebSAl Viro else 36702675a4ebSAl Viro error = -ESTALE; 36712675a4ebSAl Viro } 36727c1c01ecSAl Viro return ERR_PTR(error); 3673de459215SKirill Korotaev } 36741da177e4SLinus Torvalds 3675669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3676f9652e10SAl Viro const struct open_flags *op) 367713aab428SAl Viro { 36789883d185SAl Viro struct nameidata nd; 3679f9652e10SAl Viro int flags = op->lookup_flags; 368013aab428SAl Viro struct file *filp; 368113aab428SAl Viro 36829883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3683c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 368413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3685c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 368613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3687c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 36889883d185SAl Viro restore_nameidata(); 368913aab428SAl Viro return filp; 369013aab428SAl Viro } 369113aab428SAl Viro 369273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3693f9652e10SAl Viro const char *name, const struct open_flags *op) 369473d049a4SAl Viro { 36959883d185SAl Viro struct nameidata nd; 369673d049a4SAl Viro struct file *file; 369751689104SPaul Moore struct filename *filename; 3698f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 369973d049a4SAl Viro 370073d049a4SAl Viro nd.root.mnt = mnt; 370173d049a4SAl Viro nd.root.dentry = dentry; 370273d049a4SAl Viro 3703b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 370473d049a4SAl Viro return ERR_PTR(-ELOOP); 370573d049a4SAl Viro 370651689104SPaul Moore filename = getname_kernel(name); 3707a1c83681SViresh Kumar if (IS_ERR(filename)) 370851689104SPaul Moore return ERR_CAST(filename); 370951689104SPaul Moore 37109883d185SAl Viro set_nameidata(&nd, -1, filename); 3711c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 371273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3713c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 371473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3715c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 37169883d185SAl Viro restore_nameidata(); 371751689104SPaul Moore putname(filename); 371873d049a4SAl Viro return file; 371973d049a4SAl Viro } 372073d049a4SAl Viro 3721fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 37221ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 37231da177e4SLinus Torvalds { 3724c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3725391172c4SAl Viro struct qstr last; 3726391172c4SAl Viro int type; 3727c30dabfeSJan Kara int err2; 37281ac12b4bSJeff Layton int error; 37291ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 37301ac12b4bSJeff Layton 37311ac12b4bSJeff Layton /* 37321ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 37331ac12b4bSJeff Layton * other flags passed in are ignored! 37341ac12b4bSJeff Layton */ 37351ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 37361ac12b4bSJeff Layton 37375c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 37385c31b6ceSAl Viro if (IS_ERR(name)) 37395c31b6ceSAl Viro return ERR_CAST(name); 37401da177e4SLinus Torvalds 3741c663e5d8SChristoph Hellwig /* 3742c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3743c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3744c663e5d8SChristoph Hellwig */ 37455c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3746ed75e95dSAl Viro goto out; 3747c663e5d8SChristoph Hellwig 3748c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3749391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3750c663e5d8SChristoph Hellwig /* 3751c663e5d8SChristoph Hellwig * Do the final lookup. 3752c663e5d8SChristoph Hellwig */ 3753391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 37545955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3755391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 37561da177e4SLinus Torvalds if (IS_ERR(dentry)) 3757a8104a9fSAl Viro goto unlock; 3758c663e5d8SChristoph Hellwig 3759a8104a9fSAl Viro error = -EEXIST; 3760b18825a7SDavid Howells if (d_is_positive(dentry)) 3761a8104a9fSAl Viro goto fail; 3762b18825a7SDavid Howells 3763c663e5d8SChristoph Hellwig /* 3764c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3765c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3766c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3767c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3768c663e5d8SChristoph Hellwig */ 3769391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3770a8104a9fSAl Viro error = -ENOENT; 3771ed75e95dSAl Viro goto fail; 3772e9baf6e5SAl Viro } 3773c30dabfeSJan Kara if (unlikely(err2)) { 3774c30dabfeSJan Kara error = err2; 3775a8104a9fSAl Viro goto fail; 3776c30dabfeSJan Kara } 3777181c37b6SAl Viro putname(name); 3778e9baf6e5SAl Viro return dentry; 37791da177e4SLinus Torvalds fail: 3780a8104a9fSAl Viro dput(dentry); 3781a8104a9fSAl Viro dentry = ERR_PTR(error); 3782a8104a9fSAl Viro unlock: 37835955102cSAl Viro inode_unlock(path->dentry->d_inode); 3784c30dabfeSJan Kara if (!err2) 3785391172c4SAl Viro mnt_drop_write(path->mnt); 3786ed75e95dSAl Viro out: 3787391172c4SAl Viro path_put(path); 3788181c37b6SAl Viro putname(name); 3789ed75e95dSAl Viro return dentry; 3790dae6ad8fSAl Viro } 3791fa14a0b8SAl Viro 3792fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3793fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3794fa14a0b8SAl Viro { 3795181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3796181c37b6SAl Viro path, lookup_flags); 3797fa14a0b8SAl Viro } 3798dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3799dae6ad8fSAl Viro 3800921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3801921a1650SAl Viro { 3802921a1650SAl Viro dput(dentry); 38035955102cSAl Viro inode_unlock(path->dentry->d_inode); 3804a8104a9fSAl Viro mnt_drop_write(path->mnt); 3805921a1650SAl Viro path_put(path); 3806921a1650SAl Viro } 3807921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3808921a1650SAl Viro 3809520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 38101ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3811dae6ad8fSAl Viro { 3812181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3813dae6ad8fSAl Viro } 3814dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3815dae6ad8fSAl Viro 38161a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 38171da177e4SLinus Torvalds { 3818a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38191da177e4SLinus Torvalds 38201da177e4SLinus Torvalds if (error) 38211da177e4SLinus Torvalds return error; 38221da177e4SLinus Torvalds 382394f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 38241da177e4SLinus Torvalds return -EPERM; 38251da177e4SLinus Torvalds 3826acfa4380SAl Viro if (!dir->i_op->mknod) 38271da177e4SLinus Torvalds return -EPERM; 38281da177e4SLinus Torvalds 382908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 383008ce5f16SSerge E. Hallyn if (error) 383108ce5f16SSerge E. Hallyn return error; 383208ce5f16SSerge E. Hallyn 38331da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 38341da177e4SLinus Torvalds if (error) 38351da177e4SLinus Torvalds return error; 38361da177e4SLinus Torvalds 38371da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3838a74574aaSStephen Smalley if (!error) 3839f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38401da177e4SLinus Torvalds return error; 38411da177e4SLinus Torvalds } 38424d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 38431da177e4SLinus Torvalds 3844f69aac00SAl Viro static int may_mknod(umode_t mode) 3845463c3197SDave Hansen { 3846463c3197SDave Hansen switch (mode & S_IFMT) { 3847463c3197SDave Hansen case S_IFREG: 3848463c3197SDave Hansen case S_IFCHR: 3849463c3197SDave Hansen case S_IFBLK: 3850463c3197SDave Hansen case S_IFIFO: 3851463c3197SDave Hansen case S_IFSOCK: 3852463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3853463c3197SDave Hansen return 0; 3854463c3197SDave Hansen case S_IFDIR: 3855463c3197SDave Hansen return -EPERM; 3856463c3197SDave Hansen default: 3857463c3197SDave Hansen return -EINVAL; 3858463c3197SDave Hansen } 3859463c3197SDave Hansen } 3860463c3197SDave Hansen 386187c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 386287c4e192SDominik Brodowski unsigned int dev) 38631da177e4SLinus Torvalds { 38641da177e4SLinus Torvalds struct dentry *dentry; 3865dae6ad8fSAl Viro struct path path; 3866dae6ad8fSAl Viro int error; 3867972567f1SJeff Layton unsigned int lookup_flags = 0; 38681da177e4SLinus Torvalds 38698e4bfca1SAl Viro error = may_mknod(mode); 38708e4bfca1SAl Viro if (error) 38718e4bfca1SAl Viro return error; 3872972567f1SJeff Layton retry: 3873972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3874dae6ad8fSAl Viro if (IS_ERR(dentry)) 3875dae6ad8fSAl Viro return PTR_ERR(dentry); 38762ad94ae6SAl Viro 3877dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3878ce3b0f8dSAl Viro mode &= ~current_umask(); 3879dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3880be6d3e56SKentaro Takeda if (error) 3881a8104a9fSAl Viro goto out; 38821da177e4SLinus Torvalds switch (mode & S_IFMT) { 38831da177e4SLinus Torvalds case 0: case S_IFREG: 3884312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 388505d1a717SMimi Zohar if (!error) 388605d1a717SMimi Zohar ima_post_path_mknod(dentry); 38871da177e4SLinus Torvalds break; 38881da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3889dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 38901da177e4SLinus Torvalds new_decode_dev(dev)); 38911da177e4SLinus Torvalds break; 38921da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3893dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 38941da177e4SLinus Torvalds break; 38951da177e4SLinus Torvalds } 3896a8104a9fSAl Viro out: 3897921a1650SAl Viro done_path_create(&path, dentry); 3898972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3899972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3900972567f1SJeff Layton goto retry; 3901972567f1SJeff Layton } 39021da177e4SLinus Torvalds return error; 39031da177e4SLinus Torvalds } 39041da177e4SLinus Torvalds 390587c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 390687c4e192SDominik Brodowski unsigned int, dev) 390787c4e192SDominik Brodowski { 390887c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 390987c4e192SDominik Brodowski } 391087c4e192SDominik Brodowski 39118208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 39125590ff0dSUlrich Drepper { 391387c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 39145590ff0dSUlrich Drepper } 39155590ff0dSUlrich Drepper 391618bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 39171da177e4SLinus Torvalds { 3918a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39198de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39201da177e4SLinus Torvalds 39211da177e4SLinus Torvalds if (error) 39221da177e4SLinus Torvalds return error; 39231da177e4SLinus Torvalds 3924acfa4380SAl Viro if (!dir->i_op->mkdir) 39251da177e4SLinus Torvalds return -EPERM; 39261da177e4SLinus Torvalds 39271da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 39281da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 39291da177e4SLinus Torvalds if (error) 39301da177e4SLinus Torvalds return error; 39311da177e4SLinus Torvalds 39328de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 39338de52778SAl Viro return -EMLINK; 39348de52778SAl Viro 39351da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3936a74574aaSStephen Smalley if (!error) 3937f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 39381da177e4SLinus Torvalds return error; 39391da177e4SLinus Torvalds } 39404d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 39411da177e4SLinus Torvalds 39420101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 39431da177e4SLinus Torvalds { 39446902d925SDave Hansen struct dentry *dentry; 3945dae6ad8fSAl Viro struct path path; 3946dae6ad8fSAl Viro int error; 3947b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 39481da177e4SLinus Torvalds 3949b76d8b82SJeff Layton retry: 3950b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 39516902d925SDave Hansen if (IS_ERR(dentry)) 3952dae6ad8fSAl Viro return PTR_ERR(dentry); 39536902d925SDave Hansen 3954dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3955ce3b0f8dSAl Viro mode &= ~current_umask(); 3956dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3957a8104a9fSAl Viro if (!error) 3958dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3959921a1650SAl Viro done_path_create(&path, dentry); 3960b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3961b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3962b76d8b82SJeff Layton goto retry; 3963b76d8b82SJeff Layton } 39641da177e4SLinus Torvalds return error; 39651da177e4SLinus Torvalds } 39661da177e4SLinus Torvalds 39670101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 39680101db7aSDominik Brodowski { 39690101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 39700101db7aSDominik Brodowski } 39710101db7aSDominik Brodowski 3972a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 39735590ff0dSUlrich Drepper { 39740101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 39755590ff0dSUlrich Drepper } 39765590ff0dSUlrich Drepper 39771da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 39781da177e4SLinus Torvalds { 39791da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 39801da177e4SLinus Torvalds 39811da177e4SLinus Torvalds if (error) 39821da177e4SLinus Torvalds return error; 39831da177e4SLinus Torvalds 3984acfa4380SAl Viro if (!dir->i_op->rmdir) 39851da177e4SLinus Torvalds return -EPERM; 39861da177e4SLinus Torvalds 39871d2ef590SAl Viro dget(dentry); 39885955102cSAl Viro inode_lock(dentry->d_inode); 3989912dbc15SSage Weil 39901da177e4SLinus Torvalds error = -EBUSY; 39917af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3992912dbc15SSage Weil goto out; 3993912dbc15SSage Weil 39941da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3995912dbc15SSage Weil if (error) 3996912dbc15SSage Weil goto out; 3997912dbc15SSage Weil 39981da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3999912dbc15SSage Weil if (error) 4000912dbc15SSage Weil goto out; 4001912dbc15SSage Weil 40028767712fSAl Viro shrink_dcache_parent(dentry); 40031da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 4004d83c49f3SAl Viro dont_mount(dentry); 40058ed936b5SEric W. Biederman detach_mounts(dentry); 4006116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 40071da177e4SLinus Torvalds 4008912dbc15SSage Weil out: 40095955102cSAl Viro inode_unlock(dentry->d_inode); 40101d2ef590SAl Viro dput(dentry); 4011912dbc15SSage Weil if (!error) 4012912dbc15SSage Weil d_delete(dentry); 40131da177e4SLinus Torvalds return error; 40141da177e4SLinus Torvalds } 40154d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 40161da177e4SLinus Torvalds 4017f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 40181da177e4SLinus Torvalds { 40191da177e4SLinus Torvalds int error = 0; 402091a27b2aSJeff Layton struct filename *name; 40211da177e4SLinus Torvalds struct dentry *dentry; 4022f5beed75SAl Viro struct path path; 4023f5beed75SAl Viro struct qstr last; 4024f5beed75SAl Viro int type; 4025c6ee9206SJeff Layton unsigned int lookup_flags = 0; 4026c6ee9206SJeff Layton retry: 4027c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 4028c1d4dd27SAl Viro &path, &last, &type); 402991a27b2aSJeff Layton if (IS_ERR(name)) 403091a27b2aSJeff Layton return PTR_ERR(name); 40311da177e4SLinus Torvalds 4032f5beed75SAl Viro switch (type) { 40331da177e4SLinus Torvalds case LAST_DOTDOT: 40341da177e4SLinus Torvalds error = -ENOTEMPTY; 40351da177e4SLinus Torvalds goto exit1; 40361da177e4SLinus Torvalds case LAST_DOT: 40371da177e4SLinus Torvalds error = -EINVAL; 40381da177e4SLinus Torvalds goto exit1; 40391da177e4SLinus Torvalds case LAST_ROOT: 40401da177e4SLinus Torvalds error = -EBUSY; 40411da177e4SLinus Torvalds goto exit1; 40421da177e4SLinus Torvalds } 40430612d9fbSOGAWA Hirofumi 4044f5beed75SAl Viro error = mnt_want_write(path.mnt); 4045c30dabfeSJan Kara if (error) 4046c30dabfeSJan Kara goto exit1; 40470612d9fbSOGAWA Hirofumi 40485955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4049f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40501da177e4SLinus Torvalds error = PTR_ERR(dentry); 40516902d925SDave Hansen if (IS_ERR(dentry)) 40526902d925SDave Hansen goto exit2; 4053e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 4054e6bc45d6STheodore Ts'o error = -ENOENT; 4055e6bc45d6STheodore Ts'o goto exit3; 4056e6bc45d6STheodore Ts'o } 4057f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 4058be6d3e56SKentaro Takeda if (error) 4059c30dabfeSJan Kara goto exit3; 4060f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 40610622753bSDave Hansen exit3: 40621da177e4SLinus Torvalds dput(dentry); 40636902d925SDave Hansen exit2: 40645955102cSAl Viro inode_unlock(path.dentry->d_inode); 4065f5beed75SAl Viro mnt_drop_write(path.mnt); 40661da177e4SLinus Torvalds exit1: 4067f5beed75SAl Viro path_put(&path); 40681da177e4SLinus Torvalds putname(name); 4069c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 4070c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 4071c6ee9206SJeff Layton goto retry; 4072c6ee9206SJeff Layton } 40731da177e4SLinus Torvalds return error; 40741da177e4SLinus Torvalds } 40751da177e4SLinus Torvalds 40763cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 40775590ff0dSUlrich Drepper { 40785590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 40795590ff0dSUlrich Drepper } 40805590ff0dSUlrich Drepper 4081b21996e3SJ. Bruce Fields /** 4082b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 4083b21996e3SJ. Bruce Fields * @dir: parent directory 4084b21996e3SJ. Bruce Fields * @dentry: victim 4085b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 4086b21996e3SJ. Bruce Fields * 4087b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 4088b21996e3SJ. Bruce Fields * 4089b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 4090b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 4091b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 4092b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 4093b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 4094b21996e3SJ. Bruce Fields * 4095b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4096b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4097b21996e3SJ. Bruce Fields * to be NFS exported. 4098b21996e3SJ. Bruce Fields */ 4099b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 41001da177e4SLinus Torvalds { 41019accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 41021da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 41031da177e4SLinus Torvalds 41041da177e4SLinus Torvalds if (error) 41051da177e4SLinus Torvalds return error; 41061da177e4SLinus Torvalds 4107acfa4380SAl Viro if (!dir->i_op->unlink) 41081da177e4SLinus Torvalds return -EPERM; 41091da177e4SLinus Torvalds 41105955102cSAl Viro inode_lock(target); 41118ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 41121da177e4SLinus Torvalds error = -EBUSY; 41131da177e4SLinus Torvalds else { 41141da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 4115bec1052eSAl Viro if (!error) { 41165a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 41175a14696cSJ. Bruce Fields if (error) 4118b21996e3SJ. Bruce Fields goto out; 41191da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 41208ed936b5SEric W. Biederman if (!error) { 4121d83c49f3SAl Viro dont_mount(dentry); 41228ed936b5SEric W. Biederman detach_mounts(dentry); 4123116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 41248ed936b5SEric W. Biederman } 4125bec1052eSAl Viro } 41261da177e4SLinus Torvalds } 4127b21996e3SJ. Bruce Fields out: 41285955102cSAl Viro inode_unlock(target); 41291da177e4SLinus Torvalds 41301da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 41311da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 41329accbb97SJ. Bruce Fields fsnotify_link_count(target); 41331da177e4SLinus Torvalds d_delete(dentry); 41341da177e4SLinus Torvalds } 41350eeca283SRobert Love 41361da177e4SLinus Torvalds return error; 41371da177e4SLinus Torvalds } 41384d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 41391da177e4SLinus Torvalds 41401da177e4SLinus Torvalds /* 41411da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 41421b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 41431da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 41441da177e4SLinus Torvalds * while waiting on the I/O. 41451da177e4SLinus Torvalds */ 4146da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 41471da177e4SLinus Torvalds { 41482ad94ae6SAl Viro int error; 41491da177e4SLinus Torvalds struct dentry *dentry; 4150f5beed75SAl Viro struct path path; 4151f5beed75SAl Viro struct qstr last; 4152f5beed75SAl Viro int type; 41531da177e4SLinus Torvalds struct inode *inode = NULL; 4154b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 41555d18f813SJeff Layton unsigned int lookup_flags = 0; 41565d18f813SJeff Layton retry: 4157da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 415891a27b2aSJeff Layton if (IS_ERR(name)) 415991a27b2aSJeff Layton return PTR_ERR(name); 41602ad94ae6SAl Viro 41611da177e4SLinus Torvalds error = -EISDIR; 4162f5beed75SAl Viro if (type != LAST_NORM) 41631da177e4SLinus Torvalds goto exit1; 41640612d9fbSOGAWA Hirofumi 4165f5beed75SAl Viro error = mnt_want_write(path.mnt); 4166c30dabfeSJan Kara if (error) 4167c30dabfeSJan Kara goto exit1; 4168b21996e3SJ. Bruce Fields retry_deleg: 41695955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4170f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 41711da177e4SLinus Torvalds error = PTR_ERR(dentry); 41721da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 41731da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4174f5beed75SAl Viro if (last.name[last.len]) 417550338b88STörök Edwin goto slashes; 41761da177e4SLinus Torvalds inode = dentry->d_inode; 4177b18825a7SDavid Howells if (d_is_negative(dentry)) 4178e6bc45d6STheodore Ts'o goto slashes; 41797de9c6eeSAl Viro ihold(inode); 4180f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4181be6d3e56SKentaro Takeda if (error) 4182c30dabfeSJan Kara goto exit2; 4183f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 41841da177e4SLinus Torvalds exit2: 41851da177e4SLinus Torvalds dput(dentry); 41861da177e4SLinus Torvalds } 41875955102cSAl Viro inode_unlock(path.dentry->d_inode); 41881da177e4SLinus Torvalds if (inode) 41891da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4190b21996e3SJ. Bruce Fields inode = NULL; 4191b21996e3SJ. Bruce Fields if (delegated_inode) { 41925a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4193b21996e3SJ. Bruce Fields if (!error) 4194b21996e3SJ. Bruce Fields goto retry_deleg; 4195b21996e3SJ. Bruce Fields } 4196f5beed75SAl Viro mnt_drop_write(path.mnt); 41971da177e4SLinus Torvalds exit1: 4198f5beed75SAl Viro path_put(&path); 41995d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 42005d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 42015d18f813SJeff Layton inode = NULL; 42025d18f813SJeff Layton goto retry; 42035d18f813SJeff Layton } 4204da2f1362SChristoph Hellwig putname(name); 42051da177e4SLinus Torvalds return error; 42061da177e4SLinus Torvalds 42071da177e4SLinus Torvalds slashes: 4208b18825a7SDavid Howells if (d_is_negative(dentry)) 4209b18825a7SDavid Howells error = -ENOENT; 421044b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4211b18825a7SDavid Howells error = -EISDIR; 4212b18825a7SDavid Howells else 4213b18825a7SDavid Howells error = -ENOTDIR; 42141da177e4SLinus Torvalds goto exit2; 42151da177e4SLinus Torvalds } 42161da177e4SLinus Torvalds 42172e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 42185590ff0dSUlrich Drepper { 42195590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 42205590ff0dSUlrich Drepper return -EINVAL; 42215590ff0dSUlrich Drepper 42225590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 42235590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 42245590ff0dSUlrich Drepper 4225da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 42265590ff0dSUlrich Drepper } 42275590ff0dSUlrich Drepper 42283480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 42295590ff0dSUlrich Drepper { 4230da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 42315590ff0dSUlrich Drepper } 42325590ff0dSUlrich Drepper 4233db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 42341da177e4SLinus Torvalds { 4235a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 42361da177e4SLinus Torvalds 42371da177e4SLinus Torvalds if (error) 42381da177e4SLinus Torvalds return error; 42391da177e4SLinus Torvalds 4240acfa4380SAl Viro if (!dir->i_op->symlink) 42411da177e4SLinus Torvalds return -EPERM; 42421da177e4SLinus Torvalds 42431da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 42441da177e4SLinus Torvalds if (error) 42451da177e4SLinus Torvalds return error; 42461da177e4SLinus Torvalds 42471da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4248a74574aaSStephen Smalley if (!error) 4249f38aa942SAmy Griffis fsnotify_create(dir, dentry); 42501da177e4SLinus Torvalds return error; 42511da177e4SLinus Torvalds } 42524d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 42531da177e4SLinus Torvalds 4254b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4255b724e846SDominik Brodowski const char __user *newname) 42561da177e4SLinus Torvalds { 42572ad94ae6SAl Viro int error; 425891a27b2aSJeff Layton struct filename *from; 42596902d925SDave Hansen struct dentry *dentry; 4260dae6ad8fSAl Viro struct path path; 4261f46d3567SJeff Layton unsigned int lookup_flags = 0; 42621da177e4SLinus Torvalds 42631da177e4SLinus Torvalds from = getname(oldname); 42641da177e4SLinus Torvalds if (IS_ERR(from)) 42651da177e4SLinus Torvalds return PTR_ERR(from); 4266f46d3567SJeff Layton retry: 4267f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 42681da177e4SLinus Torvalds error = PTR_ERR(dentry); 42696902d925SDave Hansen if (IS_ERR(dentry)) 4270dae6ad8fSAl Viro goto out_putname; 42716902d925SDave Hansen 427291a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4273a8104a9fSAl Viro if (!error) 427491a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4275921a1650SAl Viro done_path_create(&path, dentry); 4276f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4277f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4278f46d3567SJeff Layton goto retry; 4279f46d3567SJeff Layton } 42806902d925SDave Hansen out_putname: 42811da177e4SLinus Torvalds putname(from); 42821da177e4SLinus Torvalds return error; 42831da177e4SLinus Torvalds } 42841da177e4SLinus Torvalds 4285b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4286b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4287b724e846SDominik Brodowski { 4288b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4289b724e846SDominik Brodowski } 4290b724e846SDominik Brodowski 42913480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 42925590ff0dSUlrich Drepper { 4293b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 42945590ff0dSUlrich Drepper } 42955590ff0dSUlrich Drepper 4296146a8595SJ. Bruce Fields /** 4297146a8595SJ. Bruce Fields * vfs_link - create a new link 4298146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4299146a8595SJ. Bruce Fields * @dir: new parent 4300146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4301146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4302146a8595SJ. Bruce Fields * 4303146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4304146a8595SJ. Bruce Fields * 4305146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4306146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4307146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4308146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4309146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4310146a8595SJ. Bruce Fields * 4311146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4312146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4313146a8595SJ. Bruce Fields * to be NFS exported. 4314146a8595SJ. Bruce Fields */ 4315146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 43161da177e4SLinus Torvalds { 43171da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 43188de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 43191da177e4SLinus Torvalds int error; 43201da177e4SLinus Torvalds 43211da177e4SLinus Torvalds if (!inode) 43221da177e4SLinus Torvalds return -ENOENT; 43231da177e4SLinus Torvalds 4324a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 43251da177e4SLinus Torvalds if (error) 43261da177e4SLinus Torvalds return error; 43271da177e4SLinus Torvalds 43281da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 43291da177e4SLinus Torvalds return -EXDEV; 43301da177e4SLinus Torvalds 43311da177e4SLinus Torvalds /* 43321da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 43331da177e4SLinus Torvalds */ 43341da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 43351da177e4SLinus Torvalds return -EPERM; 43360bd23d09SEric W. Biederman /* 43370bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 43380bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 43390bd23d09SEric W. Biederman * the vfs. 43400bd23d09SEric W. Biederman */ 43410bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 43420bd23d09SEric W. Biederman return -EPERM; 4343acfa4380SAl Viro if (!dir->i_op->link) 43441da177e4SLinus Torvalds return -EPERM; 43457e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 43461da177e4SLinus Torvalds return -EPERM; 43471da177e4SLinus Torvalds 43481da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 43491da177e4SLinus Torvalds if (error) 43501da177e4SLinus Torvalds return error; 43511da177e4SLinus Torvalds 43525955102cSAl Viro inode_lock(inode); 4353aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4354f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4355aae8a97dSAneesh Kumar K.V error = -ENOENT; 43568de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 43578de52778SAl Viro error = -EMLINK; 4358146a8595SJ. Bruce Fields else { 4359146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4360146a8595SJ. Bruce Fields if (!error) 43611da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4362146a8595SJ. Bruce Fields } 4363f4e0c30cSAl Viro 4364f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4365f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4366f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4367f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4368f4e0c30cSAl Viro } 43695955102cSAl Viro inode_unlock(inode); 4370e31e14ecSStephen Smalley if (!error) 43717e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 43721da177e4SLinus Torvalds return error; 43731da177e4SLinus Torvalds } 43744d359507SAl Viro EXPORT_SYMBOL(vfs_link); 43751da177e4SLinus Torvalds 43761da177e4SLinus Torvalds /* 43771da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 43781da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 43791da177e4SLinus Torvalds * newname. --KAB 43801da177e4SLinus Torvalds * 43811da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 43821da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 43831da177e4SLinus Torvalds * and other special files. --ADM 43841da177e4SLinus Torvalds */ 438546ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 438646ea89ebSDominik Brodowski const char __user *newname, int flags) 43871da177e4SLinus Torvalds { 43881da177e4SLinus Torvalds struct dentry *new_dentry; 4389dae6ad8fSAl Viro struct path old_path, new_path; 4390146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 439111a7b371SAneesh Kumar K.V int how = 0; 43921da177e4SLinus Torvalds int error; 43931da177e4SLinus Torvalds 439411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4395c04030e1SUlrich Drepper return -EINVAL; 439611a7b371SAneesh Kumar K.V /* 4397f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4398f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4399f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 440011a7b371SAneesh Kumar K.V */ 4401f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4402f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4403f0cc6ffbSLinus Torvalds return -ENOENT; 440411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4405f0cc6ffbSLinus Torvalds } 4406c04030e1SUlrich Drepper 440711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 440811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4409442e31caSJeff Layton retry: 441011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 44111da177e4SLinus Torvalds if (error) 44122ad94ae6SAl Viro return error; 44132ad94ae6SAl Viro 4414442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4415442e31caSJeff Layton (how & LOOKUP_REVAL)); 44161da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44176902d925SDave Hansen if (IS_ERR(new_dentry)) 4418dae6ad8fSAl Viro goto out; 4419dae6ad8fSAl Viro 4420dae6ad8fSAl Viro error = -EXDEV; 4421dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4422dae6ad8fSAl Viro goto out_dput; 4423800179c9SKees Cook error = may_linkat(&old_path); 4424800179c9SKees Cook if (unlikely(error)) 4425800179c9SKees Cook goto out_dput; 4426dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4427be6d3e56SKentaro Takeda if (error) 4428a8104a9fSAl Viro goto out_dput; 4429146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 443075c3f29dSDave Hansen out_dput: 4431921a1650SAl Viro done_path_create(&new_path, new_dentry); 4432146a8595SJ. Bruce Fields if (delegated_inode) { 4433146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4434d22e6338SOleg Drokin if (!error) { 4435d22e6338SOleg Drokin path_put(&old_path); 4436146a8595SJ. Bruce Fields goto retry; 4437146a8595SJ. Bruce Fields } 4438d22e6338SOleg Drokin } 4439442e31caSJeff Layton if (retry_estale(error, how)) { 4440d22e6338SOleg Drokin path_put(&old_path); 4441442e31caSJeff Layton how |= LOOKUP_REVAL; 4442442e31caSJeff Layton goto retry; 4443442e31caSJeff Layton } 44441da177e4SLinus Torvalds out: 44452d8f3038SAl Viro path_put(&old_path); 44461da177e4SLinus Torvalds 44471da177e4SLinus Torvalds return error; 44481da177e4SLinus Torvalds } 44491da177e4SLinus Torvalds 445046ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 445146ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 445246ea89ebSDominik Brodowski { 445346ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 445446ea89ebSDominik Brodowski } 445546ea89ebSDominik Brodowski 44563480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 44575590ff0dSUlrich Drepper { 445846ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44595590ff0dSUlrich Drepper } 44605590ff0dSUlrich Drepper 4461bc27027aSMiklos Szeredi /** 4462bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4463bc27027aSMiklos Szeredi * @old_dir: parent of source 4464bc27027aSMiklos Szeredi * @old_dentry: source 4465bc27027aSMiklos Szeredi * @new_dir: parent of destination 4466bc27027aSMiklos Szeredi * @new_dentry: destination 4467bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4468520c8b16SMiklos Szeredi * @flags: rename flags 4469bc27027aSMiklos Szeredi * 4470bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4471bc27027aSMiklos Szeredi * 4472bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4473bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4474bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4475bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4476bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4477bc27027aSMiklos Szeredi * so. 4478bc27027aSMiklos Szeredi * 4479bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4480bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4481bc27027aSMiklos Szeredi * to be NFS exported. 4482bc27027aSMiklos Szeredi * 44831da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 44841da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 44851da177e4SLinus Torvalds * Problems: 44860117d427SMauro Carvalho Chehab * 4487d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 44881da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 44891da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4490a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 44911da177e4SLinus Torvalds * story. 44926cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 44936cedba89SJ. Bruce Fields * and source (if it is not a directory). 44941b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 44951da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 44961da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4497a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 44981da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 44991da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 45001da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4501a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 45021da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 45031da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 45041da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4505e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 45061b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 45071da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4508c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 45091da177e4SLinus Torvalds * locking]. 45101da177e4SLinus Torvalds */ 45111da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 45128e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4513520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 45141da177e4SLinus Torvalds { 45151da177e4SLinus Torvalds int error; 4516bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4517bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4518bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4519da1ce067SMiklos Szeredi bool new_is_dir = false; 4520da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 452149d31c2fSAl Viro struct name_snapshot old_name; 45221da177e4SLinus Torvalds 45238d3e2936SMiklos Szeredi if (source == target) 45241da177e4SLinus Torvalds return 0; 45251da177e4SLinus Torvalds 45261da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 45271da177e4SLinus Torvalds if (error) 45281da177e4SLinus Torvalds return error; 45291da177e4SLinus Torvalds 4530da1ce067SMiklos Szeredi if (!target) { 4531a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4532da1ce067SMiklos Szeredi } else { 4533da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4534da1ce067SMiklos Szeredi 4535da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45361da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4537da1ce067SMiklos Szeredi else 4538da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4539da1ce067SMiklos Szeredi } 45401da177e4SLinus Torvalds if (error) 45411da177e4SLinus Torvalds return error; 45421da177e4SLinus Torvalds 45432773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 45441da177e4SLinus Torvalds return -EPERM; 45451da177e4SLinus Torvalds 4546bc27027aSMiklos Szeredi /* 4547bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4548bc27027aSMiklos Szeredi * we'll need to flip '..'. 4549bc27027aSMiklos Szeredi */ 4550da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4551da1ce067SMiklos Szeredi if (is_dir) { 4552bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4553bc27027aSMiklos Szeredi if (error) 4554bc27027aSMiklos Szeredi return error; 4555bc27027aSMiklos Szeredi } 4556da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4557da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4558da1ce067SMiklos Szeredi if (error) 4559da1ce067SMiklos Szeredi return error; 4560da1ce067SMiklos Szeredi } 4561da1ce067SMiklos Szeredi } 45620eeca283SRobert Love 45630b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 45640b3974ebSMiklos Szeredi flags); 4565bc27027aSMiklos Szeredi if (error) 4566bc27027aSMiklos Szeredi return error; 4567bc27027aSMiklos Szeredi 456849d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4569bc27027aSMiklos Szeredi dget(new_dentry); 4570da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4571bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4572bc27027aSMiklos Szeredi else if (target) 45735955102cSAl Viro inode_lock(target); 4574bc27027aSMiklos Szeredi 4575bc27027aSMiklos Szeredi error = -EBUSY; 45767af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4577bc27027aSMiklos Szeredi goto out; 4578bc27027aSMiklos Szeredi 4579da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4580bc27027aSMiklos Szeredi error = -EMLINK; 4581da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4582bc27027aSMiklos Szeredi goto out; 4583da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4584da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4585da1ce067SMiklos Szeredi goto out; 4586da1ce067SMiklos Szeredi } 4587da1ce067SMiklos Szeredi if (!is_dir) { 4588bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4589bc27027aSMiklos Szeredi if (error) 4590bc27027aSMiklos Szeredi goto out; 4591da1ce067SMiklos Szeredi } 4592da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4593bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4594bc27027aSMiklos Szeredi if (error) 4595bc27027aSMiklos Szeredi goto out; 4596bc27027aSMiklos Szeredi } 4597520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4598520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4599bc27027aSMiklos Szeredi if (error) 4600bc27027aSMiklos Szeredi goto out; 4601bc27027aSMiklos Szeredi 4602da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 46038767712fSAl Viro if (is_dir) { 46048767712fSAl Viro shrink_dcache_parent(new_dentry); 4605bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 46068767712fSAl Viro } 4607bc27027aSMiklos Szeredi dont_mount(new_dentry); 46088ed936b5SEric W. Biederman detach_mounts(new_dentry); 4609bc27027aSMiklos Szeredi } 4610da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4611da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4612bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4613da1ce067SMiklos Szeredi else 4614da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4615da1ce067SMiklos Szeredi } 4616bc27027aSMiklos Szeredi out: 4617da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4618bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4619bc27027aSMiklos Szeredi else if (target) 46205955102cSAl Viro inode_unlock(target); 4621bc27027aSMiklos Szeredi dput(new_dentry); 4622da1ce067SMiklos Szeredi if (!error) { 4623f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4624da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4625da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4626f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4627da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4628da1ce067SMiklos Szeredi } 4629da1ce067SMiklos Szeredi } 463049d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 46310eeca283SRobert Love 46321da177e4SLinus Torvalds return error; 46331da177e4SLinus Torvalds } 46344d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 46351da177e4SLinus Torvalds 4636ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4637ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 46381da177e4SLinus Torvalds { 46391da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 46401da177e4SLinus Torvalds struct dentry *trap; 4641f5beed75SAl Viro struct path old_path, new_path; 4642f5beed75SAl Viro struct qstr old_last, new_last; 4643f5beed75SAl Viro int old_type, new_type; 46448e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 464591a27b2aSJeff Layton struct filename *from; 464691a27b2aSJeff Layton struct filename *to; 4647f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4648c6a94284SJeff Layton bool should_retry = false; 46492ad94ae6SAl Viro int error; 4650520c8b16SMiklos Szeredi 46510d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4652da1ce067SMiklos Szeredi return -EINVAL; 4653da1ce067SMiklos Szeredi 46540d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 46550d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4656520c8b16SMiklos Szeredi return -EINVAL; 4657520c8b16SMiklos Szeredi 46580d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 46590d7a8555SMiklos Szeredi return -EPERM; 46600d7a8555SMiklos Szeredi 4661f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4662f5beed75SAl Viro target_flags = 0; 4663f5beed75SAl Viro 4664c6a94284SJeff Layton retry: 4665c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4666c1d4dd27SAl Viro &old_path, &old_last, &old_type); 466791a27b2aSJeff Layton if (IS_ERR(from)) { 466891a27b2aSJeff Layton error = PTR_ERR(from); 46691da177e4SLinus Torvalds goto exit; 467091a27b2aSJeff Layton } 46711da177e4SLinus Torvalds 4672c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4673c1d4dd27SAl Viro &new_path, &new_last, &new_type); 467491a27b2aSJeff Layton if (IS_ERR(to)) { 467591a27b2aSJeff Layton error = PTR_ERR(to); 46761da177e4SLinus Torvalds goto exit1; 467791a27b2aSJeff Layton } 46781da177e4SLinus Torvalds 46791da177e4SLinus Torvalds error = -EXDEV; 4680f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 46811da177e4SLinus Torvalds goto exit2; 46821da177e4SLinus Torvalds 46831da177e4SLinus Torvalds error = -EBUSY; 4684f5beed75SAl Viro if (old_type != LAST_NORM) 46851da177e4SLinus Torvalds goto exit2; 46861da177e4SLinus Torvalds 46870a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 46880a7c3937SMiklos Szeredi error = -EEXIST; 4689f5beed75SAl Viro if (new_type != LAST_NORM) 46901da177e4SLinus Torvalds goto exit2; 46911da177e4SLinus Torvalds 4692f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4693c30dabfeSJan Kara if (error) 4694c30dabfeSJan Kara goto exit2; 4695c30dabfeSJan Kara 46968e6d782cSJ. Bruce Fields retry_deleg: 4697f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 46981da177e4SLinus Torvalds 4699f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 47001da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 47011da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 47021da177e4SLinus Torvalds goto exit3; 47031da177e4SLinus Torvalds /* source must exist */ 47041da177e4SLinus Torvalds error = -ENOENT; 4705b18825a7SDavid Howells if (d_is_negative(old_dentry)) 47061da177e4SLinus Torvalds goto exit4; 4707f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 47081da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 47091da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 47101da177e4SLinus Torvalds goto exit4; 47110a7c3937SMiklos Szeredi error = -EEXIST; 47120a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 47130a7c3937SMiklos Szeredi goto exit5; 4714da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4715da1ce067SMiklos Szeredi error = -ENOENT; 4716da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4717da1ce067SMiklos Szeredi goto exit5; 4718da1ce067SMiklos Szeredi 4719da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4720da1ce067SMiklos Szeredi error = -ENOTDIR; 4721f5beed75SAl Viro if (new_last.name[new_last.len]) 4722da1ce067SMiklos Szeredi goto exit5; 4723da1ce067SMiklos Szeredi } 4724da1ce067SMiklos Szeredi } 47250a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 47260a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 47270a7c3937SMiklos Szeredi error = -ENOTDIR; 4728f5beed75SAl Viro if (old_last.name[old_last.len]) 47290a7c3937SMiklos Szeredi goto exit5; 4730f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 47310a7c3937SMiklos Szeredi goto exit5; 47320a7c3937SMiklos Szeredi } 47330a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 47340a7c3937SMiklos Szeredi error = -EINVAL; 47350a7c3937SMiklos Szeredi if (old_dentry == trap) 47360a7c3937SMiklos Szeredi goto exit5; 47371da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4738da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 47391da177e4SLinus Torvalds error = -ENOTEMPTY; 47401da177e4SLinus Torvalds if (new_dentry == trap) 47411da177e4SLinus Torvalds goto exit5; 47421da177e4SLinus Torvalds 4743f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4744f5beed75SAl Viro &new_path, new_dentry, flags); 4745be6d3e56SKentaro Takeda if (error) 4746c30dabfeSJan Kara goto exit5; 4747f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4748f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4749520c8b16SMiklos Szeredi &delegated_inode, flags); 47501da177e4SLinus Torvalds exit5: 47511da177e4SLinus Torvalds dput(new_dentry); 47521da177e4SLinus Torvalds exit4: 47531da177e4SLinus Torvalds dput(old_dentry); 47541da177e4SLinus Torvalds exit3: 4755f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 47568e6d782cSJ. Bruce Fields if (delegated_inode) { 47578e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 47588e6d782cSJ. Bruce Fields if (!error) 47598e6d782cSJ. Bruce Fields goto retry_deleg; 47608e6d782cSJ. Bruce Fields } 4761f5beed75SAl Viro mnt_drop_write(old_path.mnt); 47621da177e4SLinus Torvalds exit2: 4763c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4764c6a94284SJeff Layton should_retry = true; 4765f5beed75SAl Viro path_put(&new_path); 47662ad94ae6SAl Viro putname(to); 47671da177e4SLinus Torvalds exit1: 4768f5beed75SAl Viro path_put(&old_path); 47691da177e4SLinus Torvalds putname(from); 4770c6a94284SJeff Layton if (should_retry) { 4771c6a94284SJeff Layton should_retry = false; 4772c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4773c6a94284SJeff Layton goto retry; 4774c6a94284SJeff Layton } 47752ad94ae6SAl Viro exit: 47761da177e4SLinus Torvalds return error; 47771da177e4SLinus Torvalds } 47781da177e4SLinus Torvalds 4779ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4780ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4781ee81feb6SDominik Brodowski { 4782ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4783ee81feb6SDominik Brodowski } 4784ee81feb6SDominik Brodowski 4785520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4786520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4787520c8b16SMiklos Szeredi { 4788ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4789520c8b16SMiklos Szeredi } 4790520c8b16SMiklos Szeredi 4791a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 47925590ff0dSUlrich Drepper { 4793ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 47945590ff0dSUlrich Drepper } 47955590ff0dSUlrich Drepper 4796787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4797787fb6bcSMiklos Szeredi { 4798787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4799787fb6bcSMiklos Szeredi if (error) 4800787fb6bcSMiklos Szeredi return error; 4801787fb6bcSMiklos Szeredi 4802787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4803787fb6bcSMiklos Szeredi return -EPERM; 4804787fb6bcSMiklos Szeredi 4805787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4806787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4807787fb6bcSMiklos Szeredi } 4808787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4809787fb6bcSMiklos Szeredi 48105d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 48111da177e4SLinus Torvalds { 48125d826c84SAl Viro int len = PTR_ERR(link); 48131da177e4SLinus Torvalds if (IS_ERR(link)) 48141da177e4SLinus Torvalds goto out; 48151da177e4SLinus Torvalds 48161da177e4SLinus Torvalds len = strlen(link); 48171da177e4SLinus Torvalds if (len > (unsigned) buflen) 48181da177e4SLinus Torvalds len = buflen; 48191da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 48201da177e4SLinus Torvalds len = -EFAULT; 48211da177e4SLinus Torvalds out: 48221da177e4SLinus Torvalds return len; 48231da177e4SLinus Torvalds } 48241da177e4SLinus Torvalds 4825d60874cdSMiklos Szeredi /** 4826fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4827fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4828fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4829fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4830fd4a0edfSMiklos Szeredi * 4831fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4832fd4a0edfSMiklos Szeredi * 4833fd4a0edfSMiklos Szeredi * Does not call security hook. 4834fd4a0edfSMiklos Szeredi */ 4835fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4836fd4a0edfSMiklos Szeredi { 4837fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4838f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4839f2df5da6SAl Viro const char *link; 4840f2df5da6SAl Viro int res; 4841fd4a0edfSMiklos Szeredi 484276fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 484376fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 484476fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 484576fca90eSMiklos Szeredi 484676fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4847fd4a0edfSMiklos Szeredi return -EINVAL; 4848fd4a0edfSMiklos Szeredi 484976fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 485076fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 485176fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 485276fca90eSMiklos Szeredi } 485376fca90eSMiklos Szeredi 48544c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4855f2df5da6SAl Viro if (!link) { 4856f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4857f2df5da6SAl Viro if (IS_ERR(link)) 4858f2df5da6SAl Viro return PTR_ERR(link); 4859f2df5da6SAl Viro } 4860f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4861f2df5da6SAl Viro do_delayed_call(&done); 4862f2df5da6SAl Viro return res; 4863fd4a0edfSMiklos Szeredi } 4864fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 48651da177e4SLinus Torvalds 4866d60874cdSMiklos Szeredi /** 4867d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4868d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4869d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4870d60874cdSMiklos Szeredi * 4871d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4872d60874cdSMiklos Szeredi * 4873d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4874d60874cdSMiklos Szeredi * 4875d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4876d60874cdSMiklos Szeredi */ 4877d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4878d60874cdSMiklos Szeredi { 4879d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4880d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4881d60874cdSMiklos Szeredi 4882d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4883d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4884d60874cdSMiklos Szeredi if (!res) 4885d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4886d60874cdSMiklos Szeredi } 4887d60874cdSMiklos Szeredi return res; 4888d60874cdSMiklos Szeredi } 4889d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4890d60874cdSMiklos Szeredi 48911da177e4SLinus Torvalds /* get the link contents into pagecache */ 48926b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4893fceef393SAl Viro struct delayed_call *callback) 48941da177e4SLinus Torvalds { 4895ebd09abbSDuane Griffin char *kaddr; 48961da177e4SLinus Torvalds struct page *page; 48976b255391SAl Viro struct address_space *mapping = inode->i_mapping; 48986b255391SAl Viro 4899d3883d4fSAl Viro if (!dentry) { 4900d3883d4fSAl Viro page = find_get_page(mapping, 0); 4901d3883d4fSAl Viro if (!page) 49026b255391SAl Viro return ERR_PTR(-ECHILD); 4903d3883d4fSAl Viro if (!PageUptodate(page)) { 4904d3883d4fSAl Viro put_page(page); 4905d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4906d3883d4fSAl Viro } 4907d3883d4fSAl Viro } else { 4908090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 49091da177e4SLinus Torvalds if (IS_ERR(page)) 49106fe6900eSNick Piggin return (char*)page; 4911d3883d4fSAl Viro } 4912fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 491321fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 491421fc61c7SAl Viro kaddr = page_address(page); 49156b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4916ebd09abbSDuane Griffin return kaddr; 49171da177e4SLinus Torvalds } 49181da177e4SLinus Torvalds 49196b255391SAl Viro EXPORT_SYMBOL(page_get_link); 49201da177e4SLinus Torvalds 4921fceef393SAl Viro void page_put_link(void *arg) 49221da177e4SLinus Torvalds { 4923fceef393SAl Viro put_page(arg); 49241da177e4SLinus Torvalds } 49254d359507SAl Viro EXPORT_SYMBOL(page_put_link); 49261da177e4SLinus Torvalds 4927aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4928aa80deabSAl Viro { 4929fceef393SAl Viro DEFINE_DELAYED_CALL(done); 49306b255391SAl Viro int res = readlink_copy(buffer, buflen, 49316b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4932fceef393SAl Viro &done)); 4933fceef393SAl Viro do_delayed_call(&done); 4934aa80deabSAl Viro return res; 4935aa80deabSAl Viro } 4936aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4937aa80deabSAl Viro 493854566b2cSNick Piggin /* 493954566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 494054566b2cSNick Piggin */ 494154566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 49421da177e4SLinus Torvalds { 49431da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 49440adb25d2SKirill Korotaev struct page *page; 4945afddba49SNick Piggin void *fsdata; 4946beb497abSDmitriy Monakhov int err; 4947c718a975STetsuo Handa unsigned int flags = 0; 494854566b2cSNick Piggin if (nofs) 494954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 49501da177e4SLinus Torvalds 49517e53cac4SNeilBrown retry: 4952afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 495354566b2cSNick Piggin flags, &page, &fsdata); 49541da177e4SLinus Torvalds if (err) 4955afddba49SNick Piggin goto fail; 4956afddba49SNick Piggin 495721fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4958afddba49SNick Piggin 4959afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4960afddba49SNick Piggin page, fsdata); 49611da177e4SLinus Torvalds if (err < 0) 49621da177e4SLinus Torvalds goto fail; 4963afddba49SNick Piggin if (err < len-1) 4964afddba49SNick Piggin goto retry; 4965afddba49SNick Piggin 49661da177e4SLinus Torvalds mark_inode_dirty(inode); 49671da177e4SLinus Torvalds return 0; 49681da177e4SLinus Torvalds fail: 49691da177e4SLinus Torvalds return err; 49701da177e4SLinus Torvalds } 49714d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 49721da177e4SLinus Torvalds 49730adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 49740adb25d2SKirill Korotaev { 49750adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4976c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 49770adb25d2SKirill Korotaev } 49784d359507SAl Viro EXPORT_SYMBOL(page_symlink); 49790adb25d2SKirill Korotaev 498092e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 49816b255391SAl Viro .get_link = page_get_link, 49821da177e4SLinus Torvalds }; 49831da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4984