1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 494ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 506fceef393SAl Viro struct inode *link_inode; 5079883d185SAl Viro unsigned root_seq; 5089883d185SAl Viro int dfd; 5093859a271SKees Cook } __randomize_layout; 5101f55a6ecSAl Viro 5119883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 512894bc8c4SAl Viro { 513756daf26SNeilBrown struct nameidata *old = current->nameidata; 514756daf26SNeilBrown p->stack = p->internal; 515c8a53ee5SAl Viro p->dfd = dfd; 516c8a53ee5SAl Viro p->name = name; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5189883d185SAl Viro p->saved = old; 519756daf26SNeilBrown current->nameidata = p; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 5229883d185SAl Viro static void restore_nameidata(void) 523894bc8c4SAl Viro { 5249883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529e1a63bbcSAl Viro if (now->stack != now->internal) 530756daf26SNeilBrown kfree(now->stack); 531894bc8c4SAl Viro } 532894bc8c4SAl Viro 533894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 534894bc8c4SAl Viro { 535bc40aee0SAl Viro struct saved *p; 536bc40aee0SAl Viro 537bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5386da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 539bc40aee0SAl Viro GFP_ATOMIC); 540bc40aee0SAl Viro if (unlikely(!p)) 541bc40aee0SAl Viro return -ECHILD; 542bc40aee0SAl Viro } else { 5436da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 544894bc8c4SAl Viro GFP_KERNEL); 545894bc8c4SAl Viro if (unlikely(!p)) 546894bc8c4SAl Viro return -ENOMEM; 547bc40aee0SAl Viro } 548894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 549894bc8c4SAl Viro nd->stack = p; 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro } 552894bc8c4SAl Viro 553397d425dSEric W. Biederman /** 554397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 555397d425dSEric W. Biederman * @path: nameidate to verify 556397d425dSEric W. Biederman * 557397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 558397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 559397d425dSEric W. Biederman */ 560397d425dSEric W. Biederman static bool path_connected(const struct path *path) 561397d425dSEric W. Biederman { 562397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 56395dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 564397d425dSEric W. Biederman 56595dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56695dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 567397d425dSEric W. Biederman return true; 568397d425dSEric W. Biederman 569397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 570397d425dSEric W. Biederman } 571397d425dSEric W. Biederman 572894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 573894bc8c4SAl Viro { 574da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 575894bc8c4SAl Viro return 0; 576894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 577894bc8c4SAl Viro return 0; 578894bc8c4SAl Viro return __nd_alloc_stack(nd); 579894bc8c4SAl Viro } 580894bc8c4SAl Viro 5817973387aSAl Viro static void drop_links(struct nameidata *nd) 5827973387aSAl Viro { 5837973387aSAl Viro int i = nd->depth; 5847973387aSAl Viro while (i--) { 5857973387aSAl Viro struct saved *last = nd->stack + i; 586fceef393SAl Viro do_delayed_call(&last->done); 587fceef393SAl Viro clear_delayed_call(&last->done); 5887973387aSAl Viro } 5897973387aSAl Viro } 5907973387aSAl Viro 5917973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5927973387aSAl Viro { 5937973387aSAl Viro drop_links(nd); 5947973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5957973387aSAl Viro int i; 5967973387aSAl Viro path_put(&nd->path); 5977973387aSAl Viro for (i = 0; i < nd->depth; i++) 5987973387aSAl Viro path_put(&nd->stack[i].link); 59984a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 600102b8af2SAl Viro path_put(&nd->root); 60184a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 602102b8af2SAl Viro } 6037973387aSAl Viro } else { 6047973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6057973387aSAl Viro rcu_read_unlock(); 6067973387aSAl Viro } 6077973387aSAl Viro nd->depth = 0; 6087973387aSAl Viro } 6097973387aSAl Viro 6107973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6117973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6127973387aSAl Viro struct path *path, unsigned seq) 6137973387aSAl Viro { 6147973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6157973387aSAl Viro if (unlikely(res)) { 6167973387aSAl Viro if (res > 0) 6177973387aSAl Viro path->mnt = NULL; 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6227973387aSAl Viro path->dentry = NULL; 6237973387aSAl Viro return false; 6247973387aSAl Viro } 6257973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6267973387aSAl Viro } 6277973387aSAl Viro 6287973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6297973387aSAl Viro { 6307973387aSAl Viro int i; 6317973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6327973387aSAl Viro struct saved *last = nd->stack + i; 6337973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6347973387aSAl Viro drop_links(nd); 6357973387aSAl Viro nd->depth = i + 1; 6367973387aSAl Viro return false; 6377973387aSAl Viro } 6387973387aSAl Viro } 6397973387aSAl Viro return true; 6407973387aSAl Viro } 6417973387aSAl Viro 642ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 643ee594bffSAl Viro { 644adb21d2bSAleksa Sarai /* 645adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 646adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 647adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 648adb21d2bSAleksa Sarai */ 649adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 650adb21d2bSAleksa Sarai return false; 651adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 652ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 653ee594bffSAl Viro return true; 65484a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 655ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 656ee594bffSAl Viro } 657ee594bffSAl Viro 65819660af7SAl Viro /* 65931e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66019660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66119660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66257e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66319660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66419660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66519660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66619660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66731e6b01fSNick Piggin */ 66831e6b01fSNick Piggin 66931e6b01fSNick Piggin /** 67019660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67119660af7SAl Viro * @nd: nameidata pathwalk data 67239191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67331e6b01fSNick Piggin * 6744675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6754675ac39SAl Viro * for ref-walk mode. 6764675ac39SAl Viro * Must be called from rcu-walk context. 6777973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6787973387aSAl Viro * terminate_walk(). 67931e6b01fSNick Piggin */ 6804675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 68131e6b01fSNick Piggin { 68231e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68331e6b01fSNick Piggin 68431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 685e5c832d5SLinus Torvalds 686e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6877973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6884675ac39SAl Viro goto out1; 68984a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 69084a2bd39SAl Viro goto out; 691ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6924675ac39SAl Viro goto out; 6934675ac39SAl Viro rcu_read_unlock(); 6944675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6954675ac39SAl Viro return 0; 6964675ac39SAl Viro 69784a2bd39SAl Viro out1: 6984675ac39SAl Viro nd->path.mnt = NULL; 6994675ac39SAl Viro nd->path.dentry = NULL; 7004675ac39SAl Viro out: 7014675ac39SAl Viro rcu_read_unlock(); 7024675ac39SAl Viro return -ECHILD; 7034675ac39SAl Viro } 7044675ac39SAl Viro 7054675ac39SAl Viro /** 7064675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7074675ac39SAl Viro * @nd: nameidata pathwalk data 7084675ac39SAl Viro * @dentry: child of nd->path.dentry 7094675ac39SAl Viro * @seq: seq number to check dentry against 7104675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7114675ac39SAl Viro * 7124675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7134675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7144675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7154675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7164675ac39SAl Viro * terminate_walk(). 7174675ac39SAl Viro */ 7184675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7194675ac39SAl Viro { 7204675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7214675ac39SAl Viro 7224675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7234675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7244675ac39SAl Viro goto out2; 7257973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7267973387aSAl Viro goto out2; 7274675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7287973387aSAl Viro goto out1; 72948a066e7SAl Viro 73015570086SLinus Torvalds /* 7314675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7324675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7334675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7344675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7354675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73615570086SLinus Torvalds */ 7374675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 738e5c832d5SLinus Torvalds goto out; 73984a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 74084a2bd39SAl Viro goto out_dput; 741e5c832d5SLinus Torvalds /* 742e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 743e5c832d5SLinus Torvalds * still valid and get it if required. 744e5c832d5SLinus Torvalds */ 74584a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74684a2bd39SAl Viro goto out_dput; 7478b61e74fSAl Viro rcu_read_unlock(); 74831e6b01fSNick Piggin return 0; 74919660af7SAl Viro 7507973387aSAl Viro out2: 7517973387aSAl Viro nd->path.mnt = NULL; 7527973387aSAl Viro out1: 7537973387aSAl Viro nd->path.dentry = NULL; 754e5c832d5SLinus Torvalds out: 7558b61e74fSAl Viro rcu_read_unlock(); 75684a2bd39SAl Viro return -ECHILD; 75784a2bd39SAl Viro out_dput: 75884a2bd39SAl Viro rcu_read_unlock(); 75984a2bd39SAl Viro dput(dentry); 76031e6b01fSNick Piggin return -ECHILD; 76131e6b01fSNick Piggin } 76231e6b01fSNick Piggin 7634ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76434286d66SNick Piggin { 765a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7664ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 767a89f8337SAl Viro else 768a89f8337SAl Viro return 1; 76934286d66SNick Piggin } 77034286d66SNick Piggin 7719f1fafeeSAl Viro /** 7729f1fafeeSAl Viro * complete_walk - successful completion of path walk 7739f1fafeeSAl Viro * @nd: pointer nameidata 77439159de2SJeff Layton * 7759f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7769f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7779f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7789f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7799f1fafeeSAl Viro * need to drop nd->path. 78039159de2SJeff Layton */ 7819f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78239159de2SJeff Layton { 78316c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78439159de2SJeff Layton int status; 78539159de2SJeff Layton 7869f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 787adb21d2bSAleksa Sarai /* 788adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 789adb21d2bSAleksa Sarai * externally-managed nd->root. 790adb21d2bSAleksa Sarai */ 791adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7929f1fafeeSAl Viro nd->root.mnt = NULL; 7934675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79448a066e7SAl Viro return -ECHILD; 79548a066e7SAl Viro } 7969f1fafeeSAl Viro 797adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 798adb21d2bSAleksa Sarai /* 799adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 800adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 801adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 802adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 803adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 804adb21d2bSAleksa Sarai * 805adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 806adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 807adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 808adb21d2bSAleksa Sarai * requested root to userspace. 809adb21d2bSAleksa Sarai * 810adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 811adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 812adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 813adb21d2bSAleksa Sarai */ 814adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 815adb21d2bSAleksa Sarai return -EXDEV; 816adb21d2bSAleksa Sarai } 817adb21d2bSAleksa Sarai 81816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 81939159de2SJeff Layton return 0; 82039159de2SJeff Layton 821ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 82216c2cd71SAl Viro return 0; 82316c2cd71SAl Viro 824ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82539159de2SJeff Layton if (status > 0) 82639159de2SJeff Layton return 0; 82739159de2SJeff Layton 82816c2cd71SAl Viro if (!status) 82939159de2SJeff Layton status = -ESTALE; 83016c2cd71SAl Viro 83139159de2SJeff Layton return status; 83239159de2SJeff Layton } 83339159de2SJeff Layton 834740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8352a737871SAl Viro { 83631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8379e6697e2SAl Viro 838adb21d2bSAleksa Sarai /* 839adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 840adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 841adb21d2bSAleksa Sarai * from the dirfd. 842adb21d2bSAleksa Sarai */ 843adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 844adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 845adb21d2bSAleksa Sarai 8469e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8478f47a016SAl Viro unsigned seq; 848c28cc364SNick Piggin 849c28cc364SNick Piggin do { 850c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 85131e6b01fSNick Piggin nd->root = fs->root; 8528f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 853c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8549e6697e2SAl Viro } else { 8559e6697e2SAl Viro get_fs_root(fs, &nd->root); 85684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8579e6697e2SAl Viro } 858740a1678SAleksa Sarai return 0; 85931e6b01fSNick Piggin } 86031e6b01fSNick Piggin 8617b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8627b9337aaSNick Piggin struct nameidata *nd) 863051d3812SIan Kent { 86431e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8654ac91378SJan Blunck dput(nd->path.dentry); 86631e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8674ac91378SJan Blunck mntput(nd->path.mnt); 8689a229683SHuang Shijie } 86931e6b01fSNick Piggin nd->path.mnt = path->mnt; 8704ac91378SJan Blunck nd->path.dentry = path->dentry; 871051d3812SIan Kent } 872051d3812SIan Kent 873248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 874248fb5b9SAl Viro { 875adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 876adb21d2bSAleksa Sarai return -EXDEV; 87772ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 87872ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 87972ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 88072ba2929SAleksa Sarai return -EXDEV; 88172ba2929SAleksa Sarai } 882740a1678SAleksa Sarai if (!nd->root.mnt) { 883740a1678SAleksa Sarai int error = set_root(nd); 884740a1678SAleksa Sarai if (error) 885740a1678SAleksa Sarai return error; 886740a1678SAleksa Sarai } 887248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 888248fb5b9SAl Viro struct dentry *d; 889248fb5b9SAl Viro nd->path = nd->root; 890248fb5b9SAl Viro d = nd->path.dentry; 891248fb5b9SAl Viro nd->inode = d->d_inode; 892248fb5b9SAl Viro nd->seq = nd->root_seq; 893248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 894248fb5b9SAl Viro return -ECHILD; 895248fb5b9SAl Viro } else { 896248fb5b9SAl Viro path_put(&nd->path); 897248fb5b9SAl Viro nd->path = nd->root; 898248fb5b9SAl Viro path_get(&nd->path); 899248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 900248fb5b9SAl Viro } 901248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 902248fb5b9SAl Viro return 0; 903248fb5b9SAl Viro } 904248fb5b9SAl Viro 905b5fb63c1SChristoph Hellwig /* 9066b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 907b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 908b5fb63c1SChristoph Hellwig */ 9091bc82070SAleksa Sarai int nd_jump_link(struct path *path) 910b5fb63c1SChristoph Hellwig { 9114b99d499SAleksa Sarai int error = -ELOOP; 9126e77137bSAl Viro struct nameidata *nd = current->nameidata; 913b5fb63c1SChristoph Hellwig 9144b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9154b99d499SAleksa Sarai goto err; 9164b99d499SAleksa Sarai 91772ba2929SAleksa Sarai error = -EXDEV; 91872ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 91972ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 92072ba2929SAleksa Sarai goto err; 92172ba2929SAleksa Sarai } 922adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 923adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 924adb21d2bSAleksa Sarai goto err; 92572ba2929SAleksa Sarai 9264b99d499SAleksa Sarai path_put(&nd->path); 927b5fb63c1SChristoph Hellwig nd->path = *path; 928b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 929b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9301bc82070SAleksa Sarai return 0; 9314b99d499SAleksa Sarai 9324b99d499SAleksa Sarai err: 9334b99d499SAleksa Sarai path_put(path); 9344b99d499SAleksa Sarai return error; 935b5fb63c1SChristoph Hellwig } 936b5fb63c1SChristoph Hellwig 937b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 938574197e0SAl Viro { 93921c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 940fceef393SAl Viro do_delayed_call(&last->done); 9416548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 942b9ff4429SAl Viro path_put(&last->link); 943574197e0SAl Viro } 944574197e0SAl Viro 945561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 946561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 94730aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 94830aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 949800179c9SKees Cook 950800179c9SKees Cook /** 951800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 95255852635SRandy Dunlap * @nd: nameidata pathwalk data 953800179c9SKees Cook * 954800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 955800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 956800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 957800179c9SKees Cook * processes from failing races against path names that may change out 958800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 959800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 960800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 961800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 962800179c9SKees Cook * 963800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 964800179c9SKees Cook */ 965fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 966800179c9SKees Cook { 967800179c9SKees Cook const struct inode *inode; 968800179c9SKees Cook const struct inode *parent; 9692d7f9e2aSSeth Forshee kuid_t puid; 970800179c9SKees Cook 971800179c9SKees Cook if (!sysctl_protected_symlinks) 972800179c9SKees Cook return 0; 973800179c9SKees Cook 974800179c9SKees Cook /* Allowed if owner and follower match. */ 975fceef393SAl Viro inode = nd->link_inode; 97681abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 977800179c9SKees Cook return 0; 978800179c9SKees Cook 979800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 980aa65fa35SAl Viro parent = nd->inode; 981800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 982800179c9SKees Cook return 0; 983800179c9SKees Cook 984800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9852d7f9e2aSSeth Forshee puid = parent->i_uid; 9862d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 987800179c9SKees Cook return 0; 988800179c9SKees Cook 98931956502SAl Viro if (nd->flags & LOOKUP_RCU) 99031956502SAl Viro return -ECHILD; 99131956502SAl Viro 992ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 993245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 994800179c9SKees Cook return -EACCES; 995800179c9SKees Cook } 996800179c9SKees Cook 997800179c9SKees Cook /** 998800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 999800179c9SKees Cook * @inode: the source inode to hardlink from 1000800179c9SKees Cook * 1001800179c9SKees Cook * Return false if at least one of the following conditions: 1002800179c9SKees Cook * - inode is not a regular file 1003800179c9SKees Cook * - inode is setuid 1004800179c9SKees Cook * - inode is setgid and group-exec 1005800179c9SKees Cook * - access failure for read and write 1006800179c9SKees Cook * 1007800179c9SKees Cook * Otherwise returns true. 1008800179c9SKees Cook */ 1009800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1010800179c9SKees Cook { 1011800179c9SKees Cook umode_t mode = inode->i_mode; 1012800179c9SKees Cook 1013800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1014800179c9SKees Cook if (!S_ISREG(mode)) 1015800179c9SKees Cook return false; 1016800179c9SKees Cook 1017800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1018800179c9SKees Cook if (mode & S_ISUID) 1019800179c9SKees Cook return false; 1020800179c9SKees Cook 1021800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1022800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1023800179c9SKees Cook return false; 1024800179c9SKees Cook 1025800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1026800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1027800179c9SKees Cook return false; 1028800179c9SKees Cook 1029800179c9SKees Cook return true; 1030800179c9SKees Cook } 1031800179c9SKees Cook 1032800179c9SKees Cook /** 1033800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1034800179c9SKees Cook * @link: the source to hardlink from 1035800179c9SKees Cook * 1036800179c9SKees Cook * Block hardlink when all of: 1037800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1038800179c9SKees Cook * - fsuid does not match inode 1039800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1040f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1041800179c9SKees Cook * 1042800179c9SKees Cook * Returns 0 if successful, -ve on error. 1043800179c9SKees Cook */ 1044800179c9SKees Cook static int may_linkat(struct path *link) 1045800179c9SKees Cook { 1046593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1047593d1ce8SEric W. Biederman 1048593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1049593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1050593d1ce8SEric W. Biederman return -EOVERFLOW; 1051800179c9SKees Cook 1052800179c9SKees Cook if (!sysctl_protected_hardlinks) 1053800179c9SKees Cook return 0; 1054800179c9SKees Cook 1055800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1056800179c9SKees Cook * otherwise, it must be a safe source. 1057800179c9SKees Cook */ 1058cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1059800179c9SKees Cook return 0; 1060800179c9SKees Cook 1061245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1062800179c9SKees Cook return -EPERM; 1063800179c9SKees Cook } 1064800179c9SKees Cook 106530aba665SSalvatore Mesoraca /** 106630aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 106730aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 106830aba665SSalvatore Mesoraca * exist. 1069d0cb5018SAl Viro * @dir_mode: mode bits of directory 1070d0cb5018SAl Viro * @dir_uid: owner of directory 107130aba665SSalvatore Mesoraca * @inode: the inode of the file to open 107230aba665SSalvatore Mesoraca * 107330aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 107430aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 107530aba665SSalvatore Mesoraca * - the file already exists 107630aba665SSalvatore Mesoraca * - we are in a sticky directory 107730aba665SSalvatore Mesoraca * - we don't own the file 107830aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 107930aba665SSalvatore Mesoraca * - the directory is world writable 108030aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 108130aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 108230aba665SSalvatore Mesoraca * be enough. 108330aba665SSalvatore Mesoraca * 108430aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 108530aba665SSalvatore Mesoraca */ 1086d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 108730aba665SSalvatore Mesoraca struct inode * const inode) 108830aba665SSalvatore Mesoraca { 108930aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 109030aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1091d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1092d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 109330aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 109430aba665SSalvatore Mesoraca return 0; 109530aba665SSalvatore Mesoraca 1096d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1097d0cb5018SAl Viro (dir_mode & 0020 && 109830aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 109930aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1100245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1101245d7369SKees Cook "sticky_create_fifo" : 1102245d7369SKees Cook "sticky_create_regular"; 1103245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 110430aba665SSalvatore Mesoraca return -EACCES; 110530aba665SSalvatore Mesoraca } 110630aba665SSalvatore Mesoraca return 0; 110730aba665SSalvatore Mesoraca } 110830aba665SSalvatore Mesoraca 11093b2e7f75SAl Viro static __always_inline 11103b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 11111da177e4SLinus Torvalds { 1112ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 11131cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1114fceef393SAl Viro struct inode *inode = nd->link_inode; 11156d7b5aaeSAl Viro int error; 11160a959df5SAl Viro const char *res; 11171da177e4SLinus Torvalds 111843679723SAl Viro if (!(nd->flags & LOOKUP_PARENT)) { 111943679723SAl Viro error = may_follow_link(nd); 112043679723SAl Viro if (unlikely(error)) 112143679723SAl Viro return ERR_PTR(error); 112243679723SAl Viro } 112343679723SAl Viro 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 } 115740fcf5a9SAl Viro if (!res) 115840fcf5a9SAl Viro goto all_done; 115940fcf5a9SAl Viro if (IS_ERR(res)) 1160fab51e8aSAl Viro return res; 11610a959df5SAl Viro } 1162fab51e8aSAl Viro if (*res == '/') { 1163740a1678SAleksa Sarai error = nd_jump_root(nd); 1164740a1678SAleksa Sarai if (unlikely(error)) 1165740a1678SAleksa Sarai return ERR_PTR(error); 1166fab51e8aSAl Viro while (unlikely(*++res == '/')) 1167fab51e8aSAl Viro ; 1168fab51e8aSAl Viro } 116940fcf5a9SAl Viro if (*res) 11700a959df5SAl Viro return res; 117140fcf5a9SAl Viro all_done: // pure jump 117240fcf5a9SAl Viro put_link(nd); 117340fcf5a9SAl Viro return NULL; 11740a959df5SAl Viro } 11756d7b5aaeSAl Viro 1176f015f126SDavid Howells /* 1177f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1178f015f126SDavid Howells * 1179f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1180f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1181f015f126SDavid Howells * Up is towards /. 1182f015f126SDavid Howells * 1183f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1184f015f126SDavid Howells * root. 1185f015f126SDavid Howells */ 1186bab77ebfSAl Viro int follow_up(struct path *path) 11871da177e4SLinus Torvalds { 11880714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11890714a533SAl Viro struct mount *parent; 11901da177e4SLinus Torvalds struct dentry *mountpoint; 119199b7db7bSNick Piggin 119248a066e7SAl Viro read_seqlock_excl(&mount_lock); 11930714a533SAl Viro parent = mnt->mnt_parent; 11943c0a6163SAl Viro if (parent == mnt) { 119548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11961da177e4SLinus Torvalds return 0; 11971da177e4SLinus Torvalds } 11980714a533SAl Viro mntget(&parent->mnt); 1199a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 120048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1201bab77ebfSAl Viro dput(path->dentry); 1202bab77ebfSAl Viro path->dentry = mountpoint; 1203bab77ebfSAl Viro mntput(path->mnt); 12040714a533SAl Viro path->mnt = &parent->mnt; 12051da177e4SLinus Torvalds return 1; 12061da177e4SLinus Torvalds } 12074d359507SAl Viro EXPORT_SYMBOL(follow_up); 12081da177e4SLinus Torvalds 1209b5c84bf6SNick Piggin /* 12109875cf80SDavid Howells * Perform an automount 12119875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 12129875cf80SDavid Howells * were called with. 12131da177e4SLinus Torvalds */ 12141c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 121531e6b01fSNick Piggin { 121625e195aaSAl Viro struct dentry *dentry = path->dentry; 12179875cf80SDavid Howells 12180ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 12190ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 12200ec26fd0SMiklos Szeredi * the name. 12210ec26fd0SMiklos Szeredi * 12220ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 12235a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 12240ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 12250ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 12260ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 12270ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 12285a30d8a2SDavid Howells */ 12291c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 12305d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 123125e195aaSAl Viro dentry->d_inode) 12329875cf80SDavid Howells return -EISDIR; 12330ec26fd0SMiklos Szeredi 12341c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 12359875cf80SDavid Howells return -ELOOP; 12369875cf80SDavid Howells 123725e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1238ea5b778aSDavid Howells } 12399875cf80SDavid Howells 12409875cf80SDavid Howells /* 12419875cf80SDavid Howells * Handle a dentry that is managed in some way. 1242cc53ce53SDavid Howells * - Flagged for transit management (autofs) 12439875cf80SDavid Howells * - Flagged as mountpoint 12449875cf80SDavid Howells * - Flagged as automount point 12459875cf80SDavid Howells * 12469875cf80SDavid Howells * This may only be called in refwalk mode. 1247d41efb52SAl Viro * On success path->dentry is known positive. 12489875cf80SDavid Howells * 12499875cf80SDavid Howells * Serialization is taken care of in namespace.c 12509875cf80SDavid Howells */ 1251756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 12529875cf80SDavid Howells { 12538aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 1254d41efb52SAl Viro unsigned flags; 12559875cf80SDavid Howells bool need_mntput = false; 12568aef1884SAl Viro int ret = 0; 12579875cf80SDavid Howells 12589875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 12599875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 12609875cf80SDavid Howells * the components of that value change under us */ 12612fa6b1e0SAl Viro while (flags = smp_load_acquire(&path->dentry->d_flags), 1262d41efb52SAl Viro unlikely(flags & DCACHE_MANAGED_DENTRY)) { 1263cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1264cc53ce53SDavid Howells * being held. */ 1265d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1266cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1267cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1268fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1269508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1270cc53ce53SDavid Howells if (ret < 0) 12718aef1884SAl Viro break; 1272cc53ce53SDavid Howells } 1273cc53ce53SDavid Howells 12749875cf80SDavid Howells /* Transit to a mounted filesystem. */ 1275d41efb52SAl Viro if (flags & DCACHE_MOUNTED) { 12769875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12779875cf80SDavid Howells if (mounted) { 12789875cf80SDavid Howells dput(path->dentry); 12799875cf80SDavid Howells if (need_mntput) 1280463ffb2eSAl Viro mntput(path->mnt); 1281463ffb2eSAl Viro path->mnt = mounted; 1282463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12839875cf80SDavid Howells need_mntput = true; 12849875cf80SDavid Howells continue; 1285463ffb2eSAl Viro } 1286463ffb2eSAl Viro 12879875cf80SDavid Howells /* Something is mounted on this dentry in another 12889875cf80SDavid Howells * namespace and/or whatever was mounted there in this 128948a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 129048a066e7SAl Viro * get it */ 12911da177e4SLinus Torvalds } 12929875cf80SDavid Howells 12939875cf80SDavid Howells /* Handle an automount point */ 1294d41efb52SAl Viro if (flags & DCACHE_NEED_AUTOMOUNT) { 12951c9f5e06SAl Viro ret = follow_automount(path, &nd->total_link_count, 12961c9f5e06SAl Viro nd->flags); 12979875cf80SDavid Howells if (ret < 0) 12988aef1884SAl Viro break; 12999875cf80SDavid Howells continue; 13009875cf80SDavid Howells } 13019875cf80SDavid Howells 13029875cf80SDavid Howells /* We didn't change the current path point */ 13039875cf80SDavid Howells break; 13049875cf80SDavid Howells } 13058aef1884SAl Viro 130672ba2929SAleksa Sarai if (need_mntput) { 130772ba2929SAleksa Sarai if (path->mnt == mnt) 13088aef1884SAl Viro mntput(path->mnt); 130972ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 131072ba2929SAleksa Sarai ret = -EXDEV; 131172ba2929SAleksa Sarai else 13128402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 131372ba2929SAleksa Sarai } 1314d41efb52SAl Viro if (ret == -EISDIR || !ret) 1315d41efb52SAl Viro ret = 1; 1316d41efb52SAl Viro if (ret > 0 && unlikely(d_flags_negative(flags))) 1317d41efb52SAl Viro ret = -ENOENT; 1318a9dc1494SAl Viro if (unlikely(ret < 0)) { 1319a9dc1494SAl Viro dput(path->dentry); 1320a9dc1494SAl Viro if (path->mnt != nd->path.mnt) 1321a9dc1494SAl Viro mntput(path->mnt); 1322a9dc1494SAl Viro } 13238402752eSAl Viro return ret; 13241da177e4SLinus Torvalds } 13251da177e4SLinus Torvalds 1326cc53ce53SDavid Howells int follow_down_one(struct path *path) 13271da177e4SLinus Torvalds { 13281da177e4SLinus Torvalds struct vfsmount *mounted; 13291da177e4SLinus Torvalds 13301c755af4SAl Viro mounted = lookup_mnt(path); 13311da177e4SLinus Torvalds if (mounted) { 13329393bd07SAl Viro dput(path->dentry); 13339393bd07SAl Viro mntput(path->mnt); 13349393bd07SAl Viro path->mnt = mounted; 13359393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 13361da177e4SLinus Torvalds return 1; 13371da177e4SLinus Torvalds } 13381da177e4SLinus Torvalds return 0; 13391da177e4SLinus Torvalds } 13404d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 13411da177e4SLinus Torvalds 1342fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 134362a7375eSIan Kent { 1344fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1345fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 134662a7375eSIan Kent } 134762a7375eSIan Kent 13489875cf80SDavid Howells /* 1349287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1350287548e4SAl Viro * we meet a managed dentry that would need blocking. 13519875cf80SDavid Howells */ 13529875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1353254cf582SAl Viro struct inode **inode, unsigned *seqp) 13549875cf80SDavid Howells { 135562a7375eSIan Kent for (;;) { 1356c7105365SAl Viro struct mount *mounted; 135762a7375eSIan Kent /* 135862a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 135962a7375eSIan Kent * that wants to block transit. 136062a7375eSIan Kent */ 1361fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1362b8faf035SNeilBrown case -ECHILD: 1363b8faf035SNeilBrown default: 1364ab90911fSDavid Howells return false; 1365b8faf035SNeilBrown case -EISDIR: 1366b8faf035SNeilBrown return true; 1367b8faf035SNeilBrown case 0: 1368b8faf035SNeilBrown break; 1369b8faf035SNeilBrown } 137062a7375eSIan Kent 137162a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1372b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 137362a7375eSIan Kent 1374474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 13759875cf80SDavid Howells if (!mounted) 13769875cf80SDavid Howells break; 137772ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 137872ba2929SAleksa Sarai return false; 1379c7105365SAl Viro path->mnt = &mounted->mnt; 1380c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1381a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1382254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 138359430262SLinus Torvalds /* 138459430262SLinus Torvalds * Update the inode too. We don't need to re-check the 138559430262SLinus Torvalds * dentry sequence number here after this d_inode read, 138659430262SLinus Torvalds * because a mount-point is always pinned. 138759430262SLinus Torvalds */ 138859430262SLinus Torvalds *inode = path->dentry->d_inode; 13899875cf80SDavid Howells } 1390f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1391b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1392287548e4SAl Viro } 1393287548e4SAl Viro 1394db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1395db3c9adeSAl Viro struct path *path, struct inode **inode, 1396db3c9adeSAl Viro unsigned int *seqp) 1397bd7c4b50SAl Viro { 1398db3c9adeSAl Viro int ret; 1399bd7c4b50SAl Viro 1400db3c9adeSAl Viro path->mnt = nd->path.mnt; 1401db3c9adeSAl Viro path->dentry = dentry; 1402c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1403c153007bSAl Viro unsigned int seq = *seqp; 1404c153007bSAl Viro if (unlikely(!*inode)) 1405c153007bSAl Viro return -ENOENT; 1406c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1407c153007bSAl Viro return 1; 1408c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1409c153007bSAl Viro return -ECHILD; 1410c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1411c153007bSAl Viro path->mnt = nd->path.mnt; 1412c153007bSAl Viro path->dentry = dentry; 1413c153007bSAl Viro } 1414db3c9adeSAl Viro ret = follow_managed(path, nd); 1415bd7c4b50SAl Viro if (likely(ret >= 0)) { 1416bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1417bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1418bd7c4b50SAl Viro } 1419bd7c4b50SAl Viro return ret; 1420bd7c4b50SAl Viro } 1421bd7c4b50SAl Viro 142231e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 142331e6b01fSNick Piggin { 14244023bfc9SAl Viro struct inode *inode = nd->inode; 142531e6b01fSNick Piggin 142631e6b01fSNick Piggin while (1) { 1427adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1428adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1429adb21d2bSAleksa Sarai return -ECHILD; 143031e6b01fSNick Piggin break; 1431adb21d2bSAleksa Sarai } 143231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 143331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 143431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 143531e6b01fSNick Piggin unsigned seq; 143631e6b01fSNick Piggin 14374023bfc9SAl Viro inode = parent->d_inode; 143831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1439aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1440aed434adSAl Viro return -ECHILD; 144131e6b01fSNick Piggin nd->path.dentry = parent; 144231e6b01fSNick Piggin nd->seq = seq; 1443397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 14442b98149cSAleksa Sarai return -ECHILD; 144531e6b01fSNick Piggin break; 1446aed434adSAl Viro } else { 1447aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1448aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1449aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1450aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1451aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1452aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1453aed434adSAl Viro return -ECHILD; 1454aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 145531e6b01fSNick Piggin break; 145672ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 145772ba2929SAleksa Sarai return -ECHILD; 1458aed434adSAl Viro /* we know that mountpoint was pinned */ 1459aed434adSAl Viro nd->path.dentry = mountpoint; 1460aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1461aed434adSAl Viro inode = inode2; 1462aed434adSAl Viro nd->seq = seq; 146331e6b01fSNick Piggin } 1464aed434adSAl Viro } 1465aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1466b37199e6SAl Viro struct mount *mounted; 1467b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1468aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1469aed434adSAl Viro return -ECHILD; 1470b37199e6SAl Viro if (!mounted) 1471b37199e6SAl Viro break; 147272ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 147372ba2929SAleksa Sarai return -ECHILD; 1474b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1475b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 14764023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1477b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1478b37199e6SAl Viro } 14794023bfc9SAl Viro nd->inode = inode; 148031e6b01fSNick Piggin return 0; 148131e6b01fSNick Piggin } 148231e6b01fSNick Piggin 14839875cf80SDavid Howells /* 1484cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1485cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1486cc53ce53SDavid Howells * caller is permitted to proceed or not. 1487cc53ce53SDavid Howells */ 14887cc90cc3SAl Viro int follow_down(struct path *path) 1489cc53ce53SDavid Howells { 1490cc53ce53SDavid Howells unsigned managed; 1491cc53ce53SDavid Howells int ret; 1492cc53ce53SDavid Howells 14936aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1494cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1495cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1496cc53ce53SDavid Howells * being held. 1497cc53ce53SDavid Howells * 1498cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1499cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1500cc53ce53SDavid Howells * other than its daemon the right to mount on its 1501cc53ce53SDavid Howells * superstructure. 1502cc53ce53SDavid Howells * 1503cc53ce53SDavid Howells * The filesystem may sleep at this point. 1504cc53ce53SDavid Howells */ 1505cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1506cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1507cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1508fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1509cc53ce53SDavid Howells if (ret < 0) 1510cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1511cc53ce53SDavid Howells } 1512cc53ce53SDavid Howells 1513cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1514cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1515cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1516cc53ce53SDavid Howells if (!mounted) 1517cc53ce53SDavid Howells break; 1518cc53ce53SDavid Howells dput(path->dentry); 1519cc53ce53SDavid Howells mntput(path->mnt); 1520cc53ce53SDavid Howells path->mnt = mounted; 1521cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1522cc53ce53SDavid Howells continue; 1523cc53ce53SDavid Howells } 1524cc53ce53SDavid Howells 1525cc53ce53SDavid Howells /* Don't handle automount points here */ 1526cc53ce53SDavid Howells break; 1527cc53ce53SDavid Howells } 1528cc53ce53SDavid Howells return 0; 1529cc53ce53SDavid Howells } 15304d359507SAl Viro EXPORT_SYMBOL(follow_down); 1531cc53ce53SDavid Howells 1532cc53ce53SDavid Howells /* 15339875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 15349875cf80SDavid Howells */ 15359875cf80SDavid Howells static void follow_mount(struct path *path) 15369875cf80SDavid Howells { 15379875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 15389875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 15399875cf80SDavid Howells if (!mounted) 15409875cf80SDavid Howells break; 15419875cf80SDavid Howells dput(path->dentry); 15429875cf80SDavid Howells mntput(path->mnt); 15439875cf80SDavid Howells path->mnt = mounted; 15449875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 15459875cf80SDavid Howells } 15469875cf80SDavid Howells } 15479875cf80SDavid Howells 1548eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1549eedf265aSEric W. Biederman { 1550eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1551eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1552eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1553eedf265aSEric W. Biederman dput(old); 1554eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1555eedf265aSEric W. Biederman return -ENOENT; 1556eedf265aSEric W. Biederman return 0; 1557eedf265aSEric W. Biederman } 1558eedf265aSEric W. Biederman 1559397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 15601da177e4SLinus Torvalds { 15611da177e4SLinus Torvalds while (1) { 1562adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1563adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1564adb21d2bSAleksa Sarai return -EXDEV; 15651da177e4SLinus Torvalds break; 1566adb21d2bSAleksa Sarai } 15674ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1568eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1569eedf265aSEric W. Biederman if (ret) 1570eedf265aSEric W. Biederman return ret; 15711da177e4SLinus Torvalds break; 15721da177e4SLinus Torvalds } 15733088dd70SAl Viro if (!follow_up(&nd->path)) 15741da177e4SLinus Torvalds break; 157572ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 157672ba2929SAleksa Sarai return -EXDEV; 15771da177e4SLinus Torvalds } 157879ed0226SAl Viro follow_mount(&nd->path); 157931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1580397d425dSEric W. Biederman return 0; 15811da177e4SLinus Torvalds } 15821da177e4SLinus Torvalds 15831da177e4SLinus Torvalds /* 1584f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1585f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1586baa03890SNick Piggin */ 1587e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1588e3c13928SAl Viro struct dentry *dir, 15896c51e513SAl Viro unsigned int flags) 1590baa03890SNick Piggin { 1591a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1592bad61189SMiklos Szeredi if (dentry) { 1593a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1594bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 159574ff0ffcSAl Viro if (!error) 15965542aa2fSEric W. Biederman d_invalidate(dentry); 1597bad61189SMiklos Szeredi dput(dentry); 159874ff0ffcSAl Viro return ERR_PTR(error); 1599bad61189SMiklos Szeredi } 1600bad61189SMiklos Szeredi } 1601baa03890SNick Piggin return dentry; 1602baa03890SNick Piggin } 1603baa03890SNick Piggin 1604baa03890SNick Piggin /* 1605a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1606a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1607a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1608a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1609a03ece5fSAl Viro * at all. 161044396f4bSJosef Bacik */ 1611a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1612a03ece5fSAl Viro struct dentry *base, unsigned int flags) 161344396f4bSJosef Bacik { 1614a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 161544396f4bSJosef Bacik struct dentry *old; 1616a03ece5fSAl Viro struct inode *dir = base->d_inode; 1617a03ece5fSAl Viro 1618a03ece5fSAl Viro if (dentry) 1619a03ece5fSAl Viro return dentry; 162044396f4bSJosef Bacik 162144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1622a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 162344396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1624a03ece5fSAl Viro 1625a03ece5fSAl Viro dentry = d_alloc(base, name); 1626a03ece5fSAl Viro if (unlikely(!dentry)) 1627a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 162844396f4bSJosef Bacik 162972bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 163044396f4bSJosef Bacik if (unlikely(old)) { 163144396f4bSJosef Bacik dput(dentry); 163244396f4bSJosef Bacik dentry = old; 163344396f4bSJosef Bacik } 163444396f4bSJosef Bacik return dentry; 163544396f4bSJosef Bacik } 163644396f4bSJosef Bacik 163720e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 163820e34357SAl Viro struct inode **inode, 1639254cf582SAl Viro unsigned *seqp) 16401da177e4SLinus Torvalds { 164131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 16425a18fff2SAl Viro int status = 1; 16439875cf80SDavid Howells 16443cac260aSAl Viro /* 1645b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 16465d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 16475d0f49c1SAl Viro * going to fall back to non-racy lookup. 1648b04f784eSNick Piggin */ 164931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 165031e6b01fSNick Piggin unsigned seq; 1651da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 16525d0f49c1SAl Viro if (unlikely(!dentry)) { 16534675ac39SAl Viro if (unlazy_walk(nd)) 165420e34357SAl Viro return ERR_PTR(-ECHILD); 165520e34357SAl Viro return NULL; 16565d0f49c1SAl Viro } 16575a18fff2SAl Viro 165812f8ad4bSLinus Torvalds /* 165912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 166012f8ad4bSLinus Torvalds * the dentry name information from lookup. 166112f8ad4bSLinus Torvalds */ 166263afdfc7SDavid Howells *inode = d_backing_inode(dentry); 16635d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 166420e34357SAl Viro return ERR_PTR(-ECHILD); 166512f8ad4bSLinus Torvalds 166612f8ad4bSLinus Torvalds /* 166712f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 166812f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 166912f8ad4bSLinus Torvalds * 167012f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 167112f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 167212f8ad4bSLinus Torvalds */ 16735d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 167420e34357SAl Viro return ERR_PTR(-ECHILD); 16755a18fff2SAl Viro 1676254cf582SAl Viro *seqp = seq; 16774ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1678c153007bSAl Viro if (likely(status > 0)) 167920e34357SAl Viro return dentry; 16804675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 168120e34357SAl Viro return ERR_PTR(-ECHILD); 1682209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1683209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1684209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16855a18fff2SAl Viro } else { 1686e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 168781e6f520SAl Viro if (unlikely(!dentry)) 168820e34357SAl Viro return NULL; 16894ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16905d0f49c1SAl Viro } 16915a18fff2SAl Viro if (unlikely(status <= 0)) { 1692e9742b53SAl Viro if (!status) 16935d0f49c1SAl Viro d_invalidate(dentry); 16945a18fff2SAl Viro dput(dentry); 169520e34357SAl Viro return ERR_PTR(status); 16965a18fff2SAl Viro } 169720e34357SAl Viro return dentry; 1698697f514dSMiklos Szeredi } 1699697f514dSMiklos Szeredi 1700697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 170188d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1702e3c13928SAl Viro struct dentry *dir, 1703e3c13928SAl Viro unsigned int flags) 1704697f514dSMiklos Szeredi { 170588d8331aSAl Viro struct dentry *dentry, *old; 17061936386eSAl Viro struct inode *inode = dir->d_inode; 1707d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 17081936386eSAl Viro 17091936386eSAl Viro /* Don't go there if it's already dead */ 171094bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 171188d8331aSAl Viro return ERR_PTR(-ENOENT); 171294bdd655SAl Viro again: 1713d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 171494bdd655SAl Viro if (IS_ERR(dentry)) 171588d8331aSAl Viro return dentry; 171694bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1717949a852eSAl Viro int error = d_revalidate(dentry, flags); 1718949a852eSAl Viro if (unlikely(error <= 0)) { 171994bdd655SAl Viro if (!error) { 1720949a852eSAl Viro d_invalidate(dentry); 1721949a852eSAl Viro dput(dentry); 172294bdd655SAl Viro goto again; 172394bdd655SAl Viro } 172494bdd655SAl Viro dput(dentry); 1725949a852eSAl Viro dentry = ERR_PTR(error); 1726949a852eSAl Viro } 172794bdd655SAl Viro } else { 17281936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 172985c7f810SAl Viro d_lookup_done(dentry); 17301936386eSAl Viro if (unlikely(old)) { 17311936386eSAl Viro dput(dentry); 17321936386eSAl Viro dentry = old; 1733949a852eSAl Viro } 1734949a852eSAl Viro } 1735e3c13928SAl Viro return dentry; 17361da177e4SLinus Torvalds } 17371da177e4SLinus Torvalds 173888d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 173988d8331aSAl Viro struct dentry *dir, 174088d8331aSAl Viro unsigned int flags) 174188d8331aSAl Viro { 174288d8331aSAl Viro struct inode *inode = dir->d_inode; 174388d8331aSAl Viro struct dentry *res; 174488d8331aSAl Viro inode_lock_shared(inode); 174588d8331aSAl Viro res = __lookup_slow(name, dir, flags); 174688d8331aSAl Viro inode_unlock_shared(inode); 174788d8331aSAl Viro return res; 174888d8331aSAl Viro } 174988d8331aSAl Viro 175052094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 175152094c8aSAl Viro { 175252094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 17534ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 175452094c8aSAl Viro if (err != -ECHILD) 175552094c8aSAl Viro return err; 17564675ac39SAl Viro if (unlazy_walk(nd)) 175752094c8aSAl Viro return -ECHILD; 175852094c8aSAl Viro } 17594ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 176052094c8aSAl Viro } 176152094c8aSAl Viro 17629856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 17639856fa1bSAl Viro { 17649856fa1bSAl Viro if (type == LAST_DOTDOT) { 1765740a1678SAleksa Sarai int error = 0; 1766740a1678SAleksa Sarai 1767740a1678SAleksa Sarai if (!nd->root.mnt) { 1768740a1678SAleksa Sarai error = set_root(nd); 1769740a1678SAleksa Sarai if (error) 1770740a1678SAleksa Sarai return error; 1771740a1678SAleksa Sarai } 1772ab87f9a5SAleksa Sarai if (nd->flags & LOOKUP_RCU) 1773ab87f9a5SAleksa Sarai error = follow_dotdot_rcu(nd); 1774ab87f9a5SAleksa Sarai else 1775ab87f9a5SAleksa Sarai error = follow_dotdot(nd); 1776ab87f9a5SAleksa Sarai if (error) 1777ab87f9a5SAleksa Sarai return error; 1778ab87f9a5SAleksa Sarai 1779ab87f9a5SAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1780ab87f9a5SAleksa Sarai /* 1781ab87f9a5SAleksa Sarai * If there was a racing rename or mount along our 1782ab87f9a5SAleksa Sarai * path, then we can't be sure that ".." hasn't jumped 1783ab87f9a5SAleksa Sarai * above nd->root (and so userspace should retry or use 1784ab87f9a5SAleksa Sarai * some fallback). 1785ab87f9a5SAleksa Sarai */ 1786ab87f9a5SAleksa Sarai smp_rmb(); 1787ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 1788ab87f9a5SAleksa Sarai return -EAGAIN; 1789ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 1790ab87f9a5SAleksa Sarai return -EAGAIN; 1791ab87f9a5SAleksa Sarai } 17929856fa1bSAl Viro } 17939856fa1bSAl Viro return 0; 17949856fa1bSAl Viro } 17959856fa1bSAl Viro 179606708adbSAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 1797181548c0SAl Viro struct inode *inode, unsigned seq) 1798d63ff28fSAl Viro { 1799626de996SAl Viro int error; 18001cf2665bSAl Viro struct saved *last; 1801756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1802626de996SAl Viro path_to_nameidata(link, nd); 180306708adbSAl Viro return ERR_PTR(-ELOOP); 1804626de996SAl Viro } 1805bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1806cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1807cd179f44SAl Viro mntget(link->mnt); 18087973387aSAl Viro } 1809626de996SAl Viro error = nd_alloc_stack(nd); 1810626de996SAl Viro if (unlikely(error)) { 1811bc40aee0SAl Viro if (error == -ECHILD) { 1812ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1813ad1633a1SAl Viro drop_links(nd); 1814ad1633a1SAl Viro nd->depth = 0; 1815ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1816ad1633a1SAl Viro nd->path.mnt = NULL; 1817ad1633a1SAl Viro nd->path.dentry = NULL; 1818ad1633a1SAl Viro rcu_read_unlock(); 18194675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1820bc40aee0SAl Viro error = nd_alloc_stack(nd); 1821bc40aee0SAl Viro } 1822bc40aee0SAl Viro if (error) { 1823cd179f44SAl Viro path_put(link); 182406708adbSAl Viro return ERR_PTR(error); 1825626de996SAl Viro } 1826bc40aee0SAl Viro } 1827626de996SAl Viro 1828ab104923SAl Viro last = nd->stack + nd->depth++; 18291cf2665bSAl Viro last->link = *link; 1830fceef393SAl Viro clear_delayed_call(&last->done); 1831fceef393SAl Viro nd->link_inode = inode; 18320450b2d1SAl Viro last->seq = seq; 183306708adbSAl Viro return get_link(nd); 1834d63ff28fSAl Viro } 1835d63ff28fSAl Viro 1836aca2903eSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 183731d66bcdSAl Viro 18383ddcd056SLinus Torvalds /* 18393ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 18403ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 18413ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 18423ddcd056SLinus Torvalds * for the common case. 18433ddcd056SLinus Torvalds */ 1844b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1845cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 18463ddcd056SLinus Torvalds { 1847cbae4d12SAl Viro struct path path; 1848cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1849cbae4d12SAl Viro 1850cbae4d12SAl Viro if (err < 0) 1851b0417d2cSAl Viro return ERR_PTR(err); 1852cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 1853aca2903eSAl Viro !((flags & WALK_FOLLOW) || (nd->flags & LOOKUP_FOLLOW)) || 1854aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 18558f64fb1cSAl Viro /* not a symlink or should not follow */ 1856cbae4d12SAl Viro path_to_nameidata(&path, nd); 18578f64fb1cSAl Viro nd->inode = inode; 18588f64fb1cSAl Viro nd->seq = seq; 1859b0417d2cSAl Viro return NULL; 18608f64fb1cSAl Viro } 1861a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1862a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1863cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1864b0417d2cSAl Viro return ERR_PTR(-ECHILD); 1865a7f77542SAl Viro } 186606708adbSAl Viro return pick_link(nd, &path, inode, seq); 18673ddcd056SLinus Torvalds } 18683ddcd056SLinus Torvalds 186992d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1870ce57dfc1SAl Viro { 1871db3c9adeSAl Viro struct dentry *dentry; 1872ce57dfc1SAl Viro struct inode *inode; 1873254cf582SAl Viro unsigned seq; 1874ce57dfc1SAl Viro int err; 1875ce57dfc1SAl Viro /* 1876ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1877ce57dfc1SAl Viro * to be able to know about the current root directory and 1878ce57dfc1SAl Viro * parent relationships. 1879ce57dfc1SAl Viro */ 18804693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18811c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18824693a547SAl Viro put_link(nd); 188356676ec3SAl Viro err = handle_dots(nd, nd->last_type); 188492d27016SAl Viro return ERR_PTR(err); 18854693a547SAl Viro } 188620e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 188720e34357SAl Viro if (IS_ERR(dentry)) 188892d27016SAl Viro return ERR_CAST(dentry); 188920e34357SAl Viro if (unlikely(!dentry)) { 1890db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1891db3c9adeSAl Viro if (IS_ERR(dentry)) 189292d27016SAl Viro return ERR_CAST(dentry); 189320e34357SAl Viro } 189456676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 189556676ec3SAl Viro put_link(nd); 1896b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1897ce57dfc1SAl Viro } 1898ce57dfc1SAl Viro 18991da177e4SLinus Torvalds /* 1900bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1901bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1902bfcfaa77SLinus Torvalds * 1903bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1904bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1905bfcfaa77SLinus Torvalds * fast. 1906bfcfaa77SLinus Torvalds * 1907bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1908bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1909bfcfaa77SLinus Torvalds * crossing operation. 1910bfcfaa77SLinus Torvalds * 1911bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1912bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1913bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1914bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1915bfcfaa77SLinus Torvalds */ 1916bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1917bfcfaa77SLinus Torvalds 1918f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1919bfcfaa77SLinus Torvalds 1920468a9428SGeorge Spelvin #ifdef HASH_MIX 1921bfcfaa77SLinus Torvalds 1922468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1923468a9428SGeorge Spelvin 1924468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 19252a18da7aSGeorge Spelvin /* 19262a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 19272a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 19282a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19292a18da7aSGeorge Spelvin * and no temporaries. 19302a18da7aSGeorge Spelvin * 19312a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19322a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19332a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19342a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19352a18da7aSGeorge Spelvin * 19362a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19372a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19382a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19392a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19402a18da7aSGeorge Spelvin * 19412a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19422a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19432a18da7aSGeorge Spelvin * toggling any given output bit. 19442a18da7aSGeorge Spelvin * 19452a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19462a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19472a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19482a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19492a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19502a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19512a18da7aSGeorge Spelvin * Perfect: 8192 258048 19522a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19532a18da7aSGeorge Spelvin */ 19542a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19552a18da7aSGeorge Spelvin ( x ^= (a), \ 19562a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19572a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19582a18da7aSGeorge Spelvin y *= 9 ) 1959bfcfaa77SLinus Torvalds 19600fed3ac8SGeorge Spelvin /* 19612a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19622a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19632a18da7aSGeorge Spelvin * work done before the hash value is used. 19640fed3ac8SGeorge Spelvin */ 19652a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19660fed3ac8SGeorge Spelvin { 19672a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19682a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19692a18da7aSGeorge Spelvin return y >> 32; 19700fed3ac8SGeorge Spelvin } 19710fed3ac8SGeorge Spelvin 1972bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1973bfcfaa77SLinus Torvalds 19742a18da7aSGeorge Spelvin /* 19752a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19762a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19772a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19782a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19792a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19802a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19812a18da7aSGeorge Spelvin * Perfect: 2048 31744 19822a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19832a18da7aSGeorge Spelvin */ 19842a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19852a18da7aSGeorge Spelvin ( x ^= (a), \ 19862a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19872a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19882a18da7aSGeorge Spelvin y *= 9 ) 1989bfcfaa77SLinus Torvalds 19902a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19910fed3ac8SGeorge Spelvin { 19922a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19932a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19940fed3ac8SGeorge Spelvin } 19950fed3ac8SGeorge Spelvin 1996bfcfaa77SLinus Torvalds #endif 1997bfcfaa77SLinus Torvalds 19982a18da7aSGeorge Spelvin /* 19992a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 20002a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 20012a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 20022a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 20032a18da7aSGeorge Spelvin * finds the delimiter after the name. 20042a18da7aSGeorge Spelvin */ 20058387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 2006bfcfaa77SLinus Torvalds { 20078387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 2008bfcfaa77SLinus Torvalds 2009bfcfaa77SLinus Torvalds for (;;) { 2010fcfd2fbfSGeorge Spelvin if (!len) 2011fcfd2fbfSGeorge Spelvin goto done; 2012e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 2013bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2014bfcfaa77SLinus Torvalds break; 20152a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2016bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2017bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2018bfcfaa77SLinus Torvalds } 20192a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2020bfcfaa77SLinus Torvalds done: 20212a18da7aSGeorge Spelvin return fold_hash(x, y); 2022bfcfaa77SLinus Torvalds } 2023bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2024bfcfaa77SLinus Torvalds 2025fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20268387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2027fcfd2fbfSGeorge Spelvin { 20288387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20298387ff25SLinus Torvalds unsigned long adata, mask, len; 2030fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2031fcfd2fbfSGeorge Spelvin 20328387ff25SLinus Torvalds len = 0; 20338387ff25SLinus Torvalds goto inside; 20348387ff25SLinus Torvalds 2035fcfd2fbfSGeorge Spelvin do { 20362a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2037fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20388387ff25SLinus Torvalds inside: 2039fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2040fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2041fcfd2fbfSGeorge Spelvin 2042fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2043fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20442a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2045fcfd2fbfSGeorge Spelvin 20462a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2047fcfd2fbfSGeorge Spelvin } 2048fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2049fcfd2fbfSGeorge Spelvin 2050bfcfaa77SLinus Torvalds /* 2051bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2052d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2053bfcfaa77SLinus Torvalds */ 20548387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2055bfcfaa77SLinus Torvalds { 20568387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20578387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 205836126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2059bfcfaa77SLinus Torvalds 20608387ff25SLinus Torvalds len = 0; 20618387ff25SLinus Torvalds goto inside; 20628387ff25SLinus Torvalds 2063bfcfaa77SLinus Torvalds do { 20642a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2065bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20668387ff25SLinus Torvalds inside: 2067e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 206836126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 206936126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2070bfcfaa77SLinus Torvalds 207136126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 207236126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 207336126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20742a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 207536126f8fSLinus Torvalds 20762a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2077bfcfaa77SLinus Torvalds } 2078bfcfaa77SLinus Torvalds 20792a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2080bfcfaa77SLinus Torvalds 2081fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20828387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20830145acc2SLinus Torvalds { 20848387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20850145acc2SLinus Torvalds while (len--) 2086fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20870145acc2SLinus Torvalds return end_name_hash(hash); 20880145acc2SLinus Torvalds } 2089ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20900145acc2SLinus Torvalds 2091fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20928387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2093fcfd2fbfSGeorge Spelvin { 20948387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2095fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2096fcfd2fbfSGeorge Spelvin 2097fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2098e0ab7af9SGeorge Spelvin while (c) { 2099fcfd2fbfSGeorge Spelvin len++; 2100fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2101fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2102e0ab7af9SGeorge Spelvin } 2103fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2104fcfd2fbfSGeorge Spelvin } 2105f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2106fcfd2fbfSGeorge Spelvin 21073ddcd056SLinus Torvalds /* 2108200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2109200e9ef7SLinus Torvalds * one character. 2110200e9ef7SLinus Torvalds */ 21118387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2112200e9ef7SLinus Torvalds { 21138387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2114200e9ef7SLinus Torvalds unsigned long len = 0, c; 2115200e9ef7SLinus Torvalds 2116200e9ef7SLinus Torvalds c = (unsigned char)*name; 2117200e9ef7SLinus Torvalds do { 2118200e9ef7SLinus Torvalds len++; 2119200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2120200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2121200e9ef7SLinus Torvalds } while (c && c != '/'); 2122d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2123200e9ef7SLinus Torvalds } 2124200e9ef7SLinus Torvalds 2125bfcfaa77SLinus Torvalds #endif 2126bfcfaa77SLinus Torvalds 2127200e9ef7SLinus Torvalds /* 21281da177e4SLinus Torvalds * Name resolution. 2129ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2130ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21311da177e4SLinus Torvalds * 2132ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2133ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21341da177e4SLinus Torvalds */ 21356de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21361da177e4SLinus Torvalds { 21371da177e4SLinus Torvalds int err; 21381da177e4SLinus Torvalds 21399b5858e9SAl Viro if (IS_ERR(name)) 21409b5858e9SAl Viro return PTR_ERR(name); 21411da177e4SLinus Torvalds while (*name=='/') 21421da177e4SLinus Torvalds name++; 21431da177e4SLinus Torvalds if (!*name) 21449e18f10aSAl Viro return 0; 21451da177e4SLinus Torvalds 21461da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21471da177e4SLinus Torvalds for(;;) { 214892d27016SAl Viro const char *link; 2149d6bb3e90SLinus Torvalds u64 hash_len; 2150fe479a58SAl Viro int type; 21511da177e4SLinus Torvalds 215252094c8aSAl Viro err = may_lookup(nd); 21531da177e4SLinus Torvalds if (err) 21543595e234SAl Viro return err; 21551da177e4SLinus Torvalds 21568387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21571da177e4SLinus Torvalds 2158fe479a58SAl Viro type = LAST_NORM; 2159d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2160fe479a58SAl Viro case 2: 2161200e9ef7SLinus Torvalds if (name[1] == '.') { 2162fe479a58SAl Viro type = LAST_DOTDOT; 216316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 216416c2cd71SAl Viro } 2165fe479a58SAl Viro break; 2166fe479a58SAl Viro case 1: 2167fe479a58SAl Viro type = LAST_DOT; 2168fe479a58SAl Viro } 21695a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21705a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 217116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21725a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2173a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2174da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21755a202bcdSAl Viro if (err < 0) 21763595e234SAl Viro return err; 2177d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2178d6bb3e90SLinus Torvalds name = this.name; 21795a202bcdSAl Viro } 21805a202bcdSAl Viro } 2181fe479a58SAl Viro 2182d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2183d6bb3e90SLinus Torvalds nd->last.name = name; 21845f4a6a69SAl Viro nd->last_type = type; 21855f4a6a69SAl Viro 2186d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2187d6bb3e90SLinus Torvalds if (!*name) 2188bdf6cbf1SAl Viro goto OK; 2189200e9ef7SLinus Torvalds /* 2190200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2191200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2192200e9ef7SLinus Torvalds */ 2193200e9ef7SLinus Torvalds do { 2194d6bb3e90SLinus Torvalds name++; 2195d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21968620c238SAl Viro if (unlikely(!*name)) { 21978620c238SAl Viro OK: 2198368ee9baSAl Viro /* pathname body, done */ 21998620c238SAl Viro if (!nd->depth) 22008620c238SAl Viro return 0; 22018620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2202368ee9baSAl Viro /* trailing symlink, done */ 22038620c238SAl Viro if (!name) 22048620c238SAl Viro return 0; 22058620c238SAl Viro /* last component of nested symlink */ 220692d27016SAl Viro link = walk_component(nd, WALK_FOLLOW); 22071c4ff1a8SAl Viro } else { 22081c4ff1a8SAl Viro /* not the last component */ 220992d27016SAl Viro link = walk_component(nd, WALK_FOLLOW | WALK_MORE); 22108620c238SAl Viro } 221192d27016SAl Viro if (unlikely(link)) { 221292d27016SAl Viro if (IS_ERR(link)) 221392d27016SAl Viro return PTR_ERR(link); 221492d27016SAl Viro /* a symlink to follow */ 2215071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 221692d27016SAl Viro name = link; 22179e18f10aSAl Viro continue; 221848c8b0c5SAl Viro } 221997242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 222097242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 22214675ac39SAl Viro if (unlazy_walk(nd)) 222297242f99SAl Viro return -ECHILD; 222397242f99SAl Viro } 22243595e234SAl Viro return -ENOTDIR; 22255f4a6a69SAl Viro } 2226ce57dfc1SAl Viro } 222797242f99SAl Viro } 22281da177e4SLinus Torvalds 2229edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2230c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 223131e6b01fSNick Piggin { 2232740a1678SAleksa Sarai int error; 2233c8a53ee5SAl Viro const char *s = nd->name->name; 223431e6b01fSNick Piggin 2235c0eb027eSLinus Torvalds if (!*s) 2236c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2237edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2238edc2b1daSAl Viro rcu_read_lock(); 2239c0eb027eSLinus Torvalds 224031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2241980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 224231e6b01fSNick Piggin nd->depth = 0; 2243ab87f9a5SAleksa Sarai 2244ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2245ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2246ab87f9a5SAleksa Sarai smp_rmb(); 2247ab87f9a5SAleksa Sarai 22485b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2249b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2250b18825a7SDavid Howells struct inode *inode = root->d_inode; 225193893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2252368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22535b6ca027SAl Viro nd->path = nd->root; 22545b6ca027SAl Viro nd->inode = inode; 22555b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2256ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22578f47a016SAl Viro nd->root_seq = nd->seq; 22585b6ca027SAl Viro } else { 22595b6ca027SAl Viro path_get(&nd->path); 22605b6ca027SAl Viro } 2261368ee9baSAl Viro return s; 22625b6ca027SAl Viro } 22635b6ca027SAl Viro 226431e6b01fSNick Piggin nd->root.mnt = NULL; 2265248fb5b9SAl Viro nd->path.mnt = NULL; 2266248fb5b9SAl Viro nd->path.dentry = NULL; 226731e6b01fSNick Piggin 22688db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22698db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2270740a1678SAleksa Sarai error = nd_jump_root(nd); 2271740a1678SAleksa Sarai if (unlikely(error)) 2272740a1678SAleksa Sarai return ERR_PTR(error); 2273ef55d917SAl Viro return s; 22748db52c7eSAleksa Sarai } 22758db52c7eSAleksa Sarai 22768db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22778db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2278e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 227931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2280c28cc364SNick Piggin unsigned seq; 228131e6b01fSNick Piggin 2282c28cc364SNick Piggin do { 2283c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 228431e6b01fSNick Piggin nd->path = fs->pwd; 2285ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2286c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2287c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2288e41f7d4eSAl Viro } else { 2289e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2290ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2291e41f7d4eSAl Viro } 229231e6b01fSNick Piggin } else { 2293582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2294c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 229531e6b01fSNick Piggin struct dentry *dentry; 229631e6b01fSNick Piggin 22972903ff01SAl Viro if (!f.file) 2298368ee9baSAl Viro return ERR_PTR(-EBADF); 229931e6b01fSNick Piggin 23002903ff01SAl Viro dentry = f.file->f_path.dentry; 230131e6b01fSNick Piggin 2302edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 23032903ff01SAl Viro fdput(f); 2304368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2305f52e0c11SAl Viro } 23062903ff01SAl Viro 23072903ff01SAl Viro nd->path = f.file->f_path; 2308e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 230934a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 231034a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 23115590ff0dSUlrich Drepper } else { 23122903ff01SAl Viro path_get(&nd->path); 231334a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 23141da177e4SLinus Torvalds } 231534a26b99SAl Viro fdput(f); 2316e41f7d4eSAl Viro } 23178db52c7eSAleksa Sarai 2318adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2319adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2320adb21d2bSAleksa Sarai nd->root = nd->path; 2321adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2322adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2323adb21d2bSAleksa Sarai } else { 2324adb21d2bSAleksa Sarai path_get(&nd->root); 2325adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2326adb21d2bSAleksa Sarai } 2327adb21d2bSAleksa Sarai } 2328adb21d2bSAleksa Sarai return s; 23299b4a9b14SAl Viro } 23309b4a9b14SAl Viro 23311ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 233295fa25d9SAl Viro { 233392d27016SAl Viro const char *link; 2334bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2335bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2336bd92d7feSAl Viro 2337bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 233892d27016SAl Viro link = walk_component(nd, 0); 233992d27016SAl Viro if (link) { 23401ccac622SAl Viro nd->flags |= LOOKUP_PARENT; 23411ccac622SAl Viro nd->stack[0].name = NULL; 23421ccac622SAl Viro } 234392d27016SAl Viro return link; 2344bd92d7feSAl Viro } 2345bd92d7feSAl Viro 23464f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23474f757f3cSAl Viro { 2348c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2349db3c9adeSAl Viro dget(nd->path.dentry); 2350b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2351b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 23524f757f3cSAl Viro } 23534f757f3cSAl Viro 23549b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2355c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23569b4a9b14SAl Viro { 2357c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2358bd92d7feSAl Viro int err; 235931e6b01fSNick Piggin 23609b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23614f757f3cSAl Viro err = handle_lookup_down(nd); 23625f336e72SAl Viro if (unlikely(err < 0)) 23635f336e72SAl Viro s = ERR_PTR(err); 23644f757f3cSAl Viro } 23654f757f3cSAl Viro 23661ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23671ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23681ccac622SAl Viro ; 23699f1fafeeSAl Viro if (!err) 23709f1fafeeSAl Viro err = complete_walk(nd); 2371bd92d7feSAl Viro 2372deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2373deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2374bd23a539SAl Viro err = -ENOTDIR; 2375161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2376161aff1dSAl Viro err = handle_lookup_down(nd); 2377161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2378161aff1dSAl Viro } 2379625b6d10SAl Viro if (!err) { 2380625b6d10SAl Viro *path = nd->path; 2381625b6d10SAl Viro nd->path.mnt = NULL; 2382625b6d10SAl Viro nd->path.dentry = NULL; 2383625b6d10SAl Viro } 2384deb106c6SAl Viro terminate_walk(nd); 2385bd92d7feSAl Viro return err; 238631e6b01fSNick Piggin } 238731e6b01fSNick Piggin 238831d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23899ad1aaa6SAl Viro struct path *path, struct path *root) 2390873f1eedSJeff Layton { 2391894bc8c4SAl Viro int retval; 23929883d185SAl Viro struct nameidata nd; 2393abc9f5beSAl Viro if (IS_ERR(name)) 2394abc9f5beSAl Viro return PTR_ERR(name); 23959ad1aaa6SAl Viro if (unlikely(root)) { 23969ad1aaa6SAl Viro nd.root = *root; 23979ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23989ad1aaa6SAl Viro } 23999883d185SAl Viro set_nameidata(&nd, dfd, name); 2400c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2401873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2402c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2403873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2404c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2405873f1eedSJeff Layton 2406873f1eedSJeff Layton if (likely(!retval)) 2407161aff1dSAl Viro audit_inode(name, path->dentry, 2408161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 24099883d185SAl Viro restore_nameidata(); 2410e4bd1c1aSAl Viro putname(name); 2411873f1eedSJeff Layton return retval; 2412873f1eedSJeff Layton } 2413873f1eedSJeff Layton 24148bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2415c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2416391172c4SAl Viro struct path *parent) 24178bcb77faSAl Viro { 2418c8a53ee5SAl Viro const char *s = path_init(nd, flags); 24199b5858e9SAl Viro int err = link_path_walk(s, nd); 24208bcb77faSAl Viro if (!err) 24218bcb77faSAl Viro err = complete_walk(nd); 2422391172c4SAl Viro if (!err) { 2423391172c4SAl Viro *parent = nd->path; 2424391172c4SAl Viro nd->path.mnt = NULL; 2425391172c4SAl Viro nd->path.dentry = NULL; 2426391172c4SAl Viro } 2427deb106c6SAl Viro terminate_walk(nd); 24288bcb77faSAl Viro return err; 24298bcb77faSAl Viro } 24308bcb77faSAl Viro 24315c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2432391172c4SAl Viro unsigned int flags, struct path *parent, 2433391172c4SAl Viro struct qstr *last, int *type) 24348bcb77faSAl Viro { 24358bcb77faSAl Viro int retval; 24369883d185SAl Viro struct nameidata nd; 24378bcb77faSAl Viro 24385c31b6ceSAl Viro if (IS_ERR(name)) 24395c31b6ceSAl Viro return name; 24409883d185SAl Viro set_nameidata(&nd, dfd, name); 2441c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 24428bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2443c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 24448bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2445c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2446391172c4SAl Viro if (likely(!retval)) { 2447391172c4SAl Viro *last = nd.last; 2448391172c4SAl Viro *type = nd.last_type; 2449c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 24505c31b6ceSAl Viro } else { 24515c31b6ceSAl Viro putname(name); 24525c31b6ceSAl Viro name = ERR_PTR(retval); 2453391172c4SAl Viro } 24549883d185SAl Viro restore_nameidata(); 24555c31b6ceSAl Viro return name; 24568bcb77faSAl Viro } 24578bcb77faSAl Viro 245879714f72SAl Viro /* does lookup, returns the object with parent locked */ 245979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24605590ff0dSUlrich Drepper { 24615c31b6ceSAl Viro struct filename *filename; 24625c31b6ceSAl Viro struct dentry *d; 2463391172c4SAl Viro struct qstr last; 2464391172c4SAl Viro int type; 246551689104SPaul Moore 24665c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24675c31b6ceSAl Viro &last, &type); 246851689104SPaul Moore if (IS_ERR(filename)) 246951689104SPaul Moore return ERR_CAST(filename); 24705c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2471391172c4SAl Viro path_put(path); 24725c31b6ceSAl Viro putname(filename); 24735c31b6ceSAl Viro return ERR_PTR(-EINVAL); 247479714f72SAl Viro } 24755955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2476391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 247779714f72SAl Viro if (IS_ERR(d)) { 24785955102cSAl Viro inode_unlock(path->dentry->d_inode); 2479391172c4SAl Viro path_put(path); 248079714f72SAl Viro } 248151689104SPaul Moore putname(filename); 248279714f72SAl Viro return d; 24835590ff0dSUlrich Drepper } 24845590ff0dSUlrich Drepper 2485d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2486d1811465SAl Viro { 2487abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2488abc9f5beSAl Viro flags, path, NULL); 2489d1811465SAl Viro } 24904d359507SAl Viro EXPORT_SYMBOL(kern_path); 2491d1811465SAl Viro 249216f18200SJosef 'Jeff' Sipek /** 249316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 249416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 249516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 249616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 249716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2498e0a01249SAl Viro * @path: pointer to struct path to fill 249916f18200SJosef 'Jeff' Sipek */ 250016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 250116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2502e0a01249SAl Viro struct path *path) 250316f18200SJosef 'Jeff' Sipek { 25049ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 25059ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2506abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2507abc9f5beSAl Viro flags , path, &root); 250816f18200SJosef 'Jeff' Sipek } 25094d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 251016f18200SJosef 'Jeff' Sipek 25113c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 25123c95f0dcSAl Viro int len, struct qstr *this) 25133c95f0dcSAl Viro { 25143c95f0dcSAl Viro this->name = name; 25153c95f0dcSAl Viro this->len = len; 25163c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 25173c95f0dcSAl Viro if (!len) 25183c95f0dcSAl Viro return -EACCES; 25193c95f0dcSAl Viro 25203c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 25213c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 25223c95f0dcSAl Viro return -EACCES; 25233c95f0dcSAl Viro } 25243c95f0dcSAl Viro 25253c95f0dcSAl Viro while (len--) { 25263c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 25273c95f0dcSAl Viro if (c == '/' || c == '\0') 25283c95f0dcSAl Viro return -EACCES; 25293c95f0dcSAl Viro } 25303c95f0dcSAl Viro /* 25313c95f0dcSAl Viro * See if the low-level filesystem might want 25323c95f0dcSAl Viro * to use its own hash.. 25333c95f0dcSAl Viro */ 25343c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 25353c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 25363c95f0dcSAl Viro if (err < 0) 25373c95f0dcSAl Viro return err; 25383c95f0dcSAl Viro } 25393c95f0dcSAl Viro 25403c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 25413c95f0dcSAl Viro } 25423c95f0dcSAl Viro 2543eead1911SChristoph Hellwig /** 25440da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25450da0b7fdSDavid Howells * @name: pathname component to lookup 25460da0b7fdSDavid Howells * @base: base directory to lookup from 25470da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25480da0b7fdSDavid Howells * 25490da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 25500da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 25510da0b7fdSDavid Howells * 25520da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 25530da0b7fdSDavid Howells * not be called by generic code. 25540da0b7fdSDavid Howells * 25550da0b7fdSDavid Howells * The caller must hold base->i_mutex. 25560da0b7fdSDavid Howells */ 25570da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 25580da0b7fdSDavid Howells { 25590da0b7fdSDavid Howells struct qstr this; 25600da0b7fdSDavid Howells int err; 25610da0b7fdSDavid Howells 25620da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25630da0b7fdSDavid Howells 25640da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25650da0b7fdSDavid Howells if (err) 25660da0b7fdSDavid Howells return ERR_PTR(err); 25670da0b7fdSDavid Howells 25680da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25690da0b7fdSDavid Howells } 25700da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25710da0b7fdSDavid Howells 25720da0b7fdSDavid Howells /** 2573a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2574eead1911SChristoph Hellwig * @name: pathname component to lookup 2575eead1911SChristoph Hellwig * @base: base directory to lookup from 2576eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2577eead1911SChristoph Hellwig * 2578a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25799e7543e9SAl Viro * not be called by generic code. 2580bbddca8eSNeilBrown * 2581bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2582eead1911SChristoph Hellwig */ 2583057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2584057f6c01SJames Morris { 25858613a209SAl Viro struct dentry *dentry; 2586057f6c01SJames Morris struct qstr this; 2587cda309deSMiklos Szeredi int err; 2588057f6c01SJames Morris 25895955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25902f9092e1SDavid Woodhouse 25913c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2592cda309deSMiklos Szeredi if (err) 2593cda309deSMiklos Szeredi return ERR_PTR(err); 2594cda309deSMiklos Szeredi 25958613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25968613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2597057f6c01SJames Morris } 25984d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2599057f6c01SJames Morris 2600bbddca8eSNeilBrown /** 2601bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2602bbddca8eSNeilBrown * @name: pathname component to lookup 2603bbddca8eSNeilBrown * @base: base directory to lookup from 2604bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2605bbddca8eSNeilBrown * 2606bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2607bbddca8eSNeilBrown * not be called by generic code. 2608bbddca8eSNeilBrown * 2609bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2610bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2611bbddca8eSNeilBrown */ 2612bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2613bbddca8eSNeilBrown struct dentry *base, int len) 2614bbddca8eSNeilBrown { 2615bbddca8eSNeilBrown struct qstr this; 2616bbddca8eSNeilBrown int err; 261720d00ee8SLinus Torvalds struct dentry *ret; 2618bbddca8eSNeilBrown 26193c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2620bbddca8eSNeilBrown if (err) 2621bbddca8eSNeilBrown return ERR_PTR(err); 2622bbddca8eSNeilBrown 262320d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 262420d00ee8SLinus Torvalds if (!ret) 262520d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 262620d00ee8SLinus Torvalds return ret; 2627bbddca8eSNeilBrown } 2628bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2629bbddca8eSNeilBrown 26306c2d4798SAl Viro /* 26316c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 26326c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 26336c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 26346c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 26356c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 26366c2d4798SAl Viro * this one avoids such problems. 26376c2d4798SAl Viro */ 26386c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 26396c2d4798SAl Viro struct dentry *base, int len) 26406c2d4798SAl Viro { 26416c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 26422fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 26436c2d4798SAl Viro dput(ret); 26446c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26456c2d4798SAl Viro } 26466c2d4798SAl Viro return ret; 26476c2d4798SAl Viro } 26486c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26496c2d4798SAl Viro 2650eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2651eedf265aSEric W. Biederman int path_pts(struct path *path) 2652eedf265aSEric W. Biederman { 2653eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2654eedf265aSEric W. Biederman * the input path. 2655eedf265aSEric W. Biederman */ 2656eedf265aSEric W. Biederman struct dentry *child, *parent; 2657eedf265aSEric W. Biederman struct qstr this; 2658eedf265aSEric W. Biederman int ret; 2659eedf265aSEric W. Biederman 2660eedf265aSEric W. Biederman ret = path_parent_directory(path); 2661eedf265aSEric W. Biederman if (ret) 2662eedf265aSEric W. Biederman return ret; 2663eedf265aSEric W. Biederman 2664eedf265aSEric W. Biederman parent = path->dentry; 2665eedf265aSEric W. Biederman this.name = "pts"; 2666eedf265aSEric W. Biederman this.len = 3; 2667eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2668eedf265aSEric W. Biederman if (!child) 2669eedf265aSEric W. Biederman return -ENOENT; 2670eedf265aSEric W. Biederman 2671eedf265aSEric W. Biederman path->dentry = child; 2672eedf265aSEric W. Biederman dput(parent); 2673eedf265aSEric W. Biederman follow_mount(path); 2674eedf265aSEric W. Biederman return 0; 2675eedf265aSEric W. Biederman } 2676eedf265aSEric W. Biederman #endif 2677eedf265aSEric W. Biederman 26781fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26791fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26801da177e4SLinus Torvalds { 2681abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2682abc9f5beSAl Viro flags, path, NULL); 26831da177e4SLinus Torvalds } 2684b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26851fa1e7f6SAndy Whitcroft 2686cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26871da177e4SLinus Torvalds { 26888e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2689da9592edSDavid Howells 26908e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26911da177e4SLinus Torvalds return 0; 26928e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26931da177e4SLinus Torvalds return 0; 269423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26951da177e4SLinus Torvalds } 2696cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26971da177e4SLinus Torvalds 26981da177e4SLinus Torvalds /* 26991da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27001da177e4SLinus Torvalds * whether the type of victim is right. 27011da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27021da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27031da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27041da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27051da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27061da177e4SLinus Torvalds * a. be owner of dir, or 27071da177e4SLinus Torvalds * b. be owner of victim, or 27081da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27091da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27101da177e4SLinus Torvalds * links pointing to it. 27110bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27120bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27130bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27140bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27150bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27161da177e4SLinus Torvalds * nfs_async_unlink(). 27171da177e4SLinus Torvalds */ 2718b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27191da177e4SLinus Torvalds { 272063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27211da177e4SLinus Torvalds int error; 27221da177e4SLinus Torvalds 2723b18825a7SDavid Howells if (d_is_negative(victim)) 27241da177e4SLinus Torvalds return -ENOENT; 2725b18825a7SDavid Howells BUG_ON(!inode); 27261da177e4SLinus Torvalds 27271da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2728593d1ce8SEric W. Biederman 2729593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2730593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2731593d1ce8SEric W. Biederman return -EOVERFLOW; 2732593d1ce8SEric W. Biederman 27334fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27341da177e4SLinus Torvalds 2735f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27361da177e4SLinus Torvalds if (error) 27371da177e4SLinus Torvalds return error; 27381da177e4SLinus Torvalds if (IS_APPEND(dir)) 27391da177e4SLinus Torvalds return -EPERM; 2740b18825a7SDavid Howells 2741b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27420bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27431da177e4SLinus Torvalds return -EPERM; 27441da177e4SLinus Torvalds if (isdir) { 274544b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27461da177e4SLinus Torvalds return -ENOTDIR; 27471da177e4SLinus Torvalds if (IS_ROOT(victim)) 27481da177e4SLinus Torvalds return -EBUSY; 274944b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27501da177e4SLinus Torvalds return -EISDIR; 27511da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27521da177e4SLinus Torvalds return -ENOENT; 27531da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27541da177e4SLinus Torvalds return -EBUSY; 27551da177e4SLinus Torvalds return 0; 27561da177e4SLinus Torvalds } 27571da177e4SLinus Torvalds 27581da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27591da177e4SLinus Torvalds * dir. 27601da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27611da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27621da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2763036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2764036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2765036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27661da177e4SLinus Torvalds */ 2767a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27681da177e4SLinus Torvalds { 2769036d5236SEric W. Biederman struct user_namespace *s_user_ns; 277014e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27711da177e4SLinus Torvalds if (child->d_inode) 27721da177e4SLinus Torvalds return -EEXIST; 27731da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27741da177e4SLinus Torvalds return -ENOENT; 2775036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2776036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2777036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2778036d5236SEric W. Biederman return -EOVERFLOW; 2779f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27801da177e4SLinus Torvalds } 27811da177e4SLinus Torvalds 27821da177e4SLinus Torvalds /* 27831da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27841da177e4SLinus Torvalds */ 27851da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27861da177e4SLinus Torvalds { 27871da177e4SLinus Torvalds struct dentry *p; 27881da177e4SLinus Torvalds 27891da177e4SLinus Torvalds if (p1 == p2) { 27905955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27911da177e4SLinus Torvalds return NULL; 27921da177e4SLinus Torvalds } 27931da177e4SLinus Torvalds 2794fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27951da177e4SLinus Torvalds 2796e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2797e2761a11SOGAWA Hirofumi if (p) { 27985955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27995955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28001da177e4SLinus Torvalds return p; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 2803e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2804e2761a11SOGAWA Hirofumi if (p) { 28055955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28065955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28071da177e4SLinus Torvalds return p; 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 28105955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28115955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28121da177e4SLinus Torvalds return NULL; 28131da177e4SLinus Torvalds } 28144d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28151da177e4SLinus Torvalds 28161da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28171da177e4SLinus Torvalds { 28185955102cSAl Viro inode_unlock(p1->d_inode); 28191da177e4SLinus Torvalds if (p1 != p2) { 28205955102cSAl Viro inode_unlock(p2->d_inode); 2821fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28221da177e4SLinus Torvalds } 28231da177e4SLinus Torvalds } 28244d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28251da177e4SLinus Torvalds 28264acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2827312b63fbSAl Viro bool want_excl) 28281da177e4SLinus Torvalds { 2829a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28301da177e4SLinus Torvalds if (error) 28311da177e4SLinus Torvalds return error; 28321da177e4SLinus Torvalds 2833acfa4380SAl Viro if (!dir->i_op->create) 28341da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28351da177e4SLinus Torvalds mode &= S_IALLUGO; 28361da177e4SLinus Torvalds mode |= S_IFREG; 28371da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28381da177e4SLinus Torvalds if (error) 28391da177e4SLinus Torvalds return error; 2840312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2841a74574aaSStephen Smalley if (!error) 2842f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28431da177e4SLinus Torvalds return error; 28441da177e4SLinus Torvalds } 28454d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28461da177e4SLinus Torvalds 28478e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28488e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28498e6c848eSAl Viro void *arg) 28508e6c848eSAl Viro { 28518e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28528e6c848eSAl Viro int error = may_create(dir, dentry); 28538e6c848eSAl Viro if (error) 28548e6c848eSAl Viro return error; 28558e6c848eSAl Viro 28568e6c848eSAl Viro mode &= S_IALLUGO; 28578e6c848eSAl Viro mode |= S_IFREG; 28588e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28598e6c848eSAl Viro if (error) 28608e6c848eSAl Viro return error; 28618e6c848eSAl Viro error = f(dentry, mode, arg); 28628e6c848eSAl Viro if (!error) 28638e6c848eSAl Viro fsnotify_create(dir, dentry); 28648e6c848eSAl Viro return error; 28658e6c848eSAl Viro } 28668e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28678e6c848eSAl Viro 2868a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2869a2982cc9SEric W. Biederman { 2870a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2871a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2872a2982cc9SEric W. Biederman } 2873a2982cc9SEric W. Biederman 2874f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28751da177e4SLinus Torvalds { 28763fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28771da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28781da177e4SLinus Torvalds int error; 28791da177e4SLinus Torvalds 28801da177e4SLinus Torvalds if (!inode) 28811da177e4SLinus Torvalds return -ENOENT; 28821da177e4SLinus Torvalds 2883c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2884c8fe8f30SChristoph Hellwig case S_IFLNK: 28851da177e4SLinus Torvalds return -ELOOP; 2886c8fe8f30SChristoph Hellwig case S_IFDIR: 2887c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28881da177e4SLinus Torvalds return -EISDIR; 2889c8fe8f30SChristoph Hellwig break; 2890c8fe8f30SChristoph Hellwig case S_IFBLK: 2891c8fe8f30SChristoph Hellwig case S_IFCHR: 2892a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28931da177e4SLinus Torvalds return -EACCES; 2894c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2895c8fe8f30SChristoph Hellwig case S_IFIFO: 2896c8fe8f30SChristoph Hellwig case S_IFSOCK: 28971da177e4SLinus Torvalds flag &= ~O_TRUNC; 2898c8fe8f30SChristoph Hellwig break; 28994a3fd211SDave Hansen } 2900b41572e9SDave Hansen 290162fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2902b41572e9SDave Hansen if (error) 2903b41572e9SDave Hansen return error; 29046146f0d5SMimi Zohar 29051da177e4SLinus Torvalds /* 29061da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29071da177e4SLinus Torvalds */ 29081da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29098737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29107715b521SAl Viro return -EPERM; 29111da177e4SLinus Torvalds if (flag & O_TRUNC) 29127715b521SAl Viro return -EPERM; 29131da177e4SLinus Torvalds } 29141da177e4SLinus Torvalds 29151da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29162e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29177715b521SAl Viro return -EPERM; 29181da177e4SLinus Torvalds 2919f3c7691eSJ. Bruce Fields return 0; 29207715b521SAl Viro } 29217715b521SAl Viro 2922e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29237715b521SAl Viro { 2924f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29257715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29267715b521SAl Viro int error = get_write_access(inode); 29271da177e4SLinus Torvalds if (error) 29287715b521SAl Viro return error; 29291da177e4SLinus Torvalds /* 29301da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29311da177e4SLinus Torvalds */ 2932d7a06983SJeff Layton error = locks_verify_locked(filp); 2933be6d3e56SKentaro Takeda if (!error) 2934ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29351da177e4SLinus Torvalds if (!error) { 29367715b521SAl Viro error = do_truncate(path->dentry, 0, 2937d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2938e1181ee6SJeff Layton filp); 29391da177e4SLinus Torvalds } 29401da177e4SLinus Torvalds put_write_access(inode); 2941acd0c935SMimi Zohar return error; 29421da177e4SLinus Torvalds } 29431da177e4SLinus Torvalds 2944d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2945d57999e1SDave Hansen { 29468a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29478a5e929dSAl Viro flag--; 2948d57999e1SDave Hansen return flag; 2949d57999e1SDave Hansen } 2950d57999e1SDave Hansen 2951d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2952d18e9008SMiklos Szeredi { 29531328c727SSeth Forshee struct user_namespace *s_user_ns; 2954d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2955d18e9008SMiklos Szeredi if (error) 2956d18e9008SMiklos Szeredi return error; 2957d18e9008SMiklos Szeredi 29581328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29591328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29601328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29611328c727SSeth Forshee return -EOVERFLOW; 29621328c727SSeth Forshee 2963d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2964d18e9008SMiklos Szeredi if (error) 2965d18e9008SMiklos Szeredi return error; 2966d18e9008SMiklos Szeredi 2967d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2968d18e9008SMiklos Szeredi } 2969d18e9008SMiklos Szeredi 29701acf0af9SDavid Howells /* 29711acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29721acf0af9SDavid Howells * dentry. 29731acf0af9SDavid Howells * 29741acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29751acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29761acf0af9SDavid Howells * 297700a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 297800a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 297900a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29801acf0af9SDavid Howells * 29811acf0af9SDavid Howells * Returns an error code otherwise. 29821acf0af9SDavid Howells */ 2983239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2984239eb983SAl Viro struct file *file, 2985015c3bbcSMiklos Szeredi const struct open_flags *op, 29863ec2eef1SAl Viro int open_flag, umode_t mode) 2987d18e9008SMiklos Szeredi { 2988d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2989d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2990d18e9008SMiklos Szeredi int error; 2991d18e9008SMiklos Szeredi 2992384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2993d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2994d18e9008SMiklos Szeredi 2995d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2996d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2997d18e9008SMiklos Szeredi 299830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 299930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30000fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 300144907d79SAl Viro open_to_namei_flags(open_flag), mode); 30026fbd0714SAl Viro d_lookup_done(dentry); 3003384f26e2SAl Viro if (!error) { 300464e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 3005d18e9008SMiklos Szeredi /* 3006384f26e2SAl Viro * We didn't have the inode before the open, so check open 3007384f26e2SAl Viro * permission here. 3008d18e9008SMiklos Szeredi */ 3009384f26e2SAl Viro int acc_mode = op->acc_mode; 301073a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 301103da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 301203da633aSAl Viro fsnotify_create(dir, dentry); 301362fb4a15SAl Viro acc_mode = 0; 301403da633aSAl Viro } 30152675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3016384f26e2SAl Viro if (WARN_ON(error > 0)) 3017384f26e2SAl Viro error = -EINVAL; 301864e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3019d18e9008SMiklos Szeredi error = -EIO; 3020384f26e2SAl Viro } else { 3021d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3022d18e9008SMiklos Szeredi dput(dentry); 3023d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 302410c64ceaSAl Viro } 302573a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3026d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3027239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 3028a01e718fSAl Viro error = -ENOENT; 3029d18e9008SMiklos Szeredi } 3030d18e9008SMiklos Szeredi } 3031239eb983SAl Viro if (error) { 3032d18e9008SMiklos Szeredi dput(dentry); 3033239eb983SAl Viro dentry = ERR_PTR(error); 3034239eb983SAl Viro } 3035239eb983SAl Viro return dentry; 3036d18e9008SMiklos Szeredi } 3037d18e9008SMiklos Szeredi 303831e6b01fSNick Piggin /* 30391acf0af9SDavid Howells * Look up and maybe create and open the last component. 3040d58ffd35SMiklos Szeredi * 304100a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3042d58ffd35SMiklos Szeredi * 304300a07c15SAl Viro * Returns 0 on success, that is, if 304400a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 304500a07c15SAl Viro * the file was not completely opened at this time, though lookups and 304600a07c15SAl Viro * creations were performed. 304700a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 304800a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 304900a07c15SAl Viro * hadn't been specified. 30501acf0af9SDavid Howells * 305100a07c15SAl Viro * An error code is returned on failure. 3052d58ffd35SMiklos Szeredi */ 3053da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3054d58ffd35SMiklos Szeredi const struct open_flags *op, 30553ec2eef1SAl Viro bool got_write) 3056d58ffd35SMiklos Szeredi { 3057d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 305854ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30591643b43fSAl Viro int open_flag = op->open_flag; 3060d58ffd35SMiklos Szeredi struct dentry *dentry; 30611643b43fSAl Viro int error, create_error = 0; 30621643b43fSAl Viro umode_t mode = op->mode; 30636fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3064d58ffd35SMiklos Szeredi 3065ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3066da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3067d58ffd35SMiklos Szeredi 306873a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30696fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30706fbd0714SAl Viro for (;;) { 30716fbd0714SAl Viro if (!dentry) { 30726fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3073d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3074da5ebf5aSAl Viro return dentry; 30756fbd0714SAl Viro } 30766fbd0714SAl Viro if (d_in_lookup(dentry)) 30776fbd0714SAl Viro break; 3078d58ffd35SMiklos Szeredi 30796fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30806fbd0714SAl Viro if (likely(error > 0)) 30816fbd0714SAl Viro break; 30826fbd0714SAl Viro if (error) 30836fbd0714SAl Viro goto out_dput; 30846fbd0714SAl Viro d_invalidate(dentry); 30856fbd0714SAl Viro dput(dentry); 30866fbd0714SAl Viro dentry = NULL; 30876fbd0714SAl Viro } 30886fbd0714SAl Viro if (dentry->d_inode) { 3089d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3090da5ebf5aSAl Viro return dentry; 30916c51e513SAl Viro } 3092d18e9008SMiklos Szeredi 30931643b43fSAl Viro /* 30941643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30951643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30961643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30971643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30981643b43fSAl Viro * 30991643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31001643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31011643b43fSAl Viro */ 31021643b43fSAl Viro if (open_flag & O_CREAT) { 31031643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31041643b43fSAl Viro mode &= ~current_umask(); 31051643b43fSAl Viro if (unlikely(!got_write)) { 31061643b43fSAl Viro create_error = -EROFS; 31071643b43fSAl Viro open_flag &= ~O_CREAT; 31081643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31091643b43fSAl Viro goto no_open; 31101643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31111643b43fSAl Viro } else { 31121643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31131643b43fSAl Viro if (create_error) { 31141643b43fSAl Viro open_flag &= ~O_CREAT; 31151643b43fSAl Viro if (open_flag & O_EXCL) 31161643b43fSAl Viro goto no_open; 31171643b43fSAl Viro } 31181643b43fSAl Viro } 31191643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31201643b43fSAl Viro unlikely(!got_write)) { 31211643b43fSAl Viro /* 31221643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31231643b43fSAl Viro * back to lookup + open 31241643b43fSAl Viro */ 31251643b43fSAl Viro goto no_open; 3126d18e9008SMiklos Szeredi } 3127d18e9008SMiklos Szeredi 31281643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3129239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3130da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3131da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3132da5ebf5aSAl Viro return dentry; 3133239eb983SAl Viro } 313454ef4872SMiklos Szeredi 31351643b43fSAl Viro no_open: 31366fbd0714SAl Viro if (d_in_lookup(dentry)) { 313712fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 313812fa5e24SAl Viro nd->flags); 31396fbd0714SAl Viro d_lookup_done(dentry); 314012fa5e24SAl Viro if (unlikely(res)) { 314112fa5e24SAl Viro if (IS_ERR(res)) { 314212fa5e24SAl Viro error = PTR_ERR(res); 314312fa5e24SAl Viro goto out_dput; 314412fa5e24SAl Viro } 314512fa5e24SAl Viro dput(dentry); 314612fa5e24SAl Viro dentry = res; 314712fa5e24SAl Viro } 314854ef4872SMiklos Szeredi } 314954ef4872SMiklos Szeredi 3150d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31511643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 315273a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3153ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3154ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3155ce8644fcSAl Viro error = -EACCES; 3156d58ffd35SMiklos Szeredi goto out_dput; 315764894cf8SAl Viro } 3158ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31591643b43fSAl Viro open_flag & O_EXCL); 3160d58ffd35SMiklos Szeredi if (error) 3161d58ffd35SMiklos Szeredi goto out_dput; 3162ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3163d58ffd35SMiklos Szeredi } 31641643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31651643b43fSAl Viro error = create_error; 3166d58ffd35SMiklos Szeredi goto out_dput; 3167d58ffd35SMiklos Szeredi } 3168da5ebf5aSAl Viro return dentry; 3169d58ffd35SMiklos Szeredi 3170d58ffd35SMiklos Szeredi out_dput: 3171d58ffd35SMiklos Szeredi dput(dentry); 3172da5ebf5aSAl Viro return ERR_PTR(error); 3173d58ffd35SMiklos Szeredi } 3174d58ffd35SMiklos Szeredi 3175d58ffd35SMiklos Szeredi /* 3176fe2d35ffSAl Viro * Handle the last step of open() 317731e6b01fSNick Piggin */ 31781ccac622SAl Viro static const char *do_last(struct nameidata *nd, 31793ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3180fb1cc555SAl Viro { 3181a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 31826404674aSAl Viro kuid_t dir_uid = nd->inode->i_uid; 31836404674aSAl Viro umode_t dir_mode = nd->inode->i_mode; 3184ca344a89SAl Viro int open_flag = op->open_flag; 318577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 318664894cf8SAl Viro bool got_write = false; 3187bcda7652SAl Viro int acc_mode = op->acc_mode; 3188254cf582SAl Viro unsigned seq; 3189a1eb3315SMiklos Szeredi struct inode *inode; 3190da5ebf5aSAl Viro struct dentry *dentry; 3191b0417d2cSAl Viro const char *res; 319216c2cd71SAl Viro int error; 3193fb1cc555SAl Viro 3194c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3195c3e380b0SAl Viro nd->flags |= op->intent; 3196c3e380b0SAl Viro 3197bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 319856676ec3SAl Viro if (nd->depth) 319956676ec3SAl Viro put_link(nd); 3200fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3201deb106c6SAl Viro if (unlikely(error)) 32021ccac622SAl Viro return ERR_PTR(error); 3203e83db167SMiklos Szeredi goto finish_open; 32041f36f774SAl Viro } 3205a2c36b45SAl Viro 3206ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3207fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3208fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3209fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 321020e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 321120e34357SAl Viro if (IS_ERR(dentry)) 32121ccac622SAl Viro return ERR_CAST(dentry); 321320e34357SAl Viro if (likely(dentry)) 321471574865SMiklos Szeredi goto finish_lookup; 321571574865SMiklos Szeredi 321637d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32176583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3218b6183df7SMiklos Szeredi } else { 3219fe2d35ffSAl Viro /* create side of things */ 3220a3fbbde7SAl Viro /* 3221b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3222b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3223b6183df7SMiklos Szeredi * about to look up 3224a3fbbde7SAl Viro */ 32259f1fafeeSAl Viro error = complete_walk(nd); 3226e8bb73dfSAl Viro if (error) 32271ccac622SAl Viro return ERR_PTR(error); 3228fe2d35ffSAl Viro 3229c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32301f36f774SAl Viro /* trailing slashes? */ 3231deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 32321ccac622SAl Viro return ERR_PTR(-EISDIR); 3233b6183df7SMiklos Szeredi } 32341f36f774SAl Viro 32359cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 323664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 323764894cf8SAl Viro if (!error) 323864894cf8SAl Viro got_write = true; 323964894cf8SAl Viro /* 324064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 324164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 324264894cf8SAl Viro * dropping this one anyway. 324364894cf8SAl Viro */ 324464894cf8SAl Viro } 32459cf843e3SAl Viro if (open_flag & O_CREAT) 32465955102cSAl Viro inode_lock(dir->d_inode); 32479cf843e3SAl Viro else 32489cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3249da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 32509cf843e3SAl Viro if (open_flag & O_CREAT) 32515955102cSAl Viro inode_unlock(dir->d_inode); 32529cf843e3SAl Viro else 32539cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3254fb1cc555SAl Viro 3255da5ebf5aSAl Viro if (IS_ERR(dentry)) { 3256da5ebf5aSAl Viro error = PTR_ERR(dentry); 3257d58ffd35SMiklos Szeredi goto out; 3258da5ebf5aSAl Viro } 32596c0d46c4SAl Viro 326000a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 326173a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3262496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 326377d660a8SMiklos Szeredi will_truncate = false; 3264d18e9008SMiklos Szeredi 326576ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3266da5ebf5aSAl Viro dput(dentry); 3267d18e9008SMiklos Szeredi goto opened; 3268d18e9008SMiklos Szeredi } 3269d18e9008SMiklos Szeredi 327073a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 32719b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3272ca344a89SAl Viro open_flag &= ~O_TRUNC; 327377d660a8SMiklos Szeredi will_truncate = false; 327462fb4a15SAl Viro acc_mode = 0; 3275e73cabffSAl Viro dput(nd->path.dentry); 3276e73cabffSAl Viro nd->path.dentry = dentry; 3277e83db167SMiklos Szeredi goto finish_open_created; 3278fb1cc555SAl Viro } 3279fb1cc555SAl Viro 3280fb1cc555SAl Viro /* 3281d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3282d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3283d18e9008SMiklos Szeredi * necessary...) 3284d18e9008SMiklos Szeredi */ 328564894cf8SAl Viro if (got_write) { 3286d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 328764894cf8SAl Viro got_write = false; 3288d18e9008SMiklos Szeredi } 3289d18e9008SMiklos Szeredi 329020e34357SAl Viro finish_lookup: 329156676ec3SAl Viro if (nd->depth) 329256676ec3SAl Viro put_link(nd); 3293b0417d2cSAl Viro res = step_into(nd, 0, dentry, inode, seq); 3294b0417d2cSAl Viro if (unlikely(res)) { 32951ccac622SAl Viro nd->flags |= LOOKUP_PARENT; 32961ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32971ccac622SAl Viro nd->stack[0].name = NULL; 3298b0417d2cSAl Viro return res; 32991ccac622SAl Viro } 330031d1726dSAl Viro 330131d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 330231d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 33031ccac622SAl Viro return ERR_PTR(-EEXIST); 330431d1726dSAl Viro } 3305bc77daa7SAl Viro finish_open: 33068f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3307a3fbbde7SAl Viro error = complete_walk(nd); 3308fac7d191SAl Viro if (error) 33091ccac622SAl Viro return ERR_PTR(error); 331076ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 331130aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3312fb1cc555SAl Viro error = -EISDIR; 331330aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 33142675a4ebSAl Viro goto out; 3315d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 331630aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 331730aba665SSalvatore Mesoraca if (unlikely(error)) 331830aba665SSalvatore Mesoraca goto out; 331930aba665SSalvatore Mesoraca } 3320af2f5542SMiklos Szeredi error = -ENOTDIR; 332144b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33222675a4ebSAl Viro goto out; 33234bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 332477d660a8SMiklos Szeredi will_truncate = false; 33256c0d46c4SAl Viro 33260f9d1a10SAl Viro if (will_truncate) { 33270f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33280f9d1a10SAl Viro if (error) 33292675a4ebSAl Viro goto out; 333064894cf8SAl Viro got_write = true; 33310f9d1a10SAl Viro } 3332e83db167SMiklos Szeredi finish_open_created: 3333bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3334ca344a89SAl Viro if (error) 33352675a4ebSAl Viro goto out; 3336aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3337ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3338fac7d191SAl Viro if (error) 3339015c3bbcSMiklos Szeredi goto out; 3340a8277b9bSMiklos Szeredi opened: 33416035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3342fe9ec829SAl Viro if (!error && will_truncate) 33432675a4ebSAl Viro error = handle_truncate(file); 3344ca344a89SAl Viro out: 3345c80567c8SAl Viro if (unlikely(error > 0)) { 3346c80567c8SAl Viro WARN_ON(1); 3347c80567c8SAl Viro error = -EINVAL; 3348c80567c8SAl Viro } 334964894cf8SAl Viro if (got_write) 33500f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33511ccac622SAl Viro return ERR_PTR(error); 3352fb1cc555SAl Viro } 3353fb1cc555SAl Viro 3354af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3355af7bd4dcSAmir Goldstein { 3356af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3357af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3358af7bd4dcSAmir Goldstein struct inode *inode; 3359af7bd4dcSAmir Goldstein int error; 3360af7bd4dcSAmir Goldstein 3361af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3362af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3363af7bd4dcSAmir Goldstein if (error) 3364af7bd4dcSAmir Goldstein goto out_err; 3365af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3366af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3367af7bd4dcSAmir Goldstein goto out_err; 3368af7bd4dcSAmir Goldstein error = -ENOMEM; 3369cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3370af7bd4dcSAmir Goldstein if (unlikely(!child)) 3371af7bd4dcSAmir Goldstein goto out_err; 3372af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3373af7bd4dcSAmir Goldstein if (error) 3374af7bd4dcSAmir Goldstein goto out_err; 3375af7bd4dcSAmir Goldstein error = -ENOENT; 3376af7bd4dcSAmir Goldstein inode = child->d_inode; 3377af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3378af7bd4dcSAmir Goldstein goto out_err; 3379af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3380af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3381af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3382af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3383af7bd4dcSAmir Goldstein } 3384fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3385af7bd4dcSAmir Goldstein return child; 3386af7bd4dcSAmir Goldstein 3387af7bd4dcSAmir Goldstein out_err: 3388af7bd4dcSAmir Goldstein dput(child); 3389af7bd4dcSAmir Goldstein return ERR_PTR(error); 3390af7bd4dcSAmir Goldstein } 3391af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3392af7bd4dcSAmir Goldstein 3393c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 339460545d0dSAl Viro const struct open_flags *op, 33953ec2eef1SAl Viro struct file *file) 339660545d0dSAl Viro { 3397625b6d10SAl Viro struct dentry *child; 3398625b6d10SAl Viro struct path path; 3399c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 340060545d0dSAl Viro if (unlikely(error)) 340160545d0dSAl Viro return error; 3402625b6d10SAl Viro error = mnt_want_write(path.mnt); 340360545d0dSAl Viro if (unlikely(error)) 340460545d0dSAl Viro goto out; 3405af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3406af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3407684e73beSHirofumi Nakagawa if (IS_ERR(child)) 340860545d0dSAl Viro goto out2; 3409625b6d10SAl Viro dput(path.dentry); 3410625b6d10SAl Viro path.dentry = child; 3411c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 341269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 341362fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 341460545d0dSAl Viro if (error) 341560545d0dSAl Viro goto out2; 3416625b6d10SAl Viro file->f_path.mnt = path.mnt; 3417be12af3eSAl Viro error = finish_open(file, child, NULL); 341860545d0dSAl Viro out2: 3419625b6d10SAl Viro mnt_drop_write(path.mnt); 342060545d0dSAl Viro out: 3421625b6d10SAl Viro path_put(&path); 342260545d0dSAl Viro return error; 342360545d0dSAl Viro } 342460545d0dSAl Viro 34256ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34266ac08709SAl Viro { 34276ac08709SAl Viro struct path path; 34286ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34296ac08709SAl Viro if (!error) { 34306ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3431ae2bb293SAl Viro error = vfs_open(&path, file); 34326ac08709SAl Viro path_put(&path); 34336ac08709SAl Viro } 34346ac08709SAl Viro return error; 34356ac08709SAl Viro } 34366ac08709SAl Viro 3437c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3438c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34391da177e4SLinus Torvalds { 344030d90494SAl Viro struct file *file; 344113aab428SAl Viro int error; 344231e6b01fSNick Piggin 3443ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 34441afc99beSAl Viro if (IS_ERR(file)) 34451afc99beSAl Viro return file; 344631e6b01fSNick Piggin 3447bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 34483ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 34495f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 34506ac08709SAl Viro error = do_o_path(nd, flags, file); 34515f336e72SAl Viro } else { 34525f336e72SAl Viro const char *s = path_init(nd, flags); 34533bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 34541ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 34551ccac622SAl Viro ; 3456deb106c6SAl Viro terminate_walk(nd); 34575f336e72SAl Viro } 34587c1c01ecSAl Viro if (likely(!error)) { 3459aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 34607c1c01ecSAl Viro return file; 34617c1c01ecSAl Viro WARN_ON(1); 34627c1c01ecSAl Viro error = -EINVAL; 3463015c3bbcSMiklos Szeredi } 34647c1c01ecSAl Viro fput(file); 34652675a4ebSAl Viro if (error == -EOPENSTALE) { 34662675a4ebSAl Viro if (flags & LOOKUP_RCU) 34672675a4ebSAl Viro error = -ECHILD; 34682675a4ebSAl Viro else 34692675a4ebSAl Viro error = -ESTALE; 34702675a4ebSAl Viro } 34717c1c01ecSAl Viro return ERR_PTR(error); 3472de459215SKirill Korotaev } 34731da177e4SLinus Torvalds 3474669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3475f9652e10SAl Viro const struct open_flags *op) 347613aab428SAl Viro { 34779883d185SAl Viro struct nameidata nd; 3478f9652e10SAl Viro int flags = op->lookup_flags; 347913aab428SAl Viro struct file *filp; 348013aab428SAl Viro 34819883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3482c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 348313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3484c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 348513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3486c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34879883d185SAl Viro restore_nameidata(); 348813aab428SAl Viro return filp; 348913aab428SAl Viro } 349013aab428SAl Viro 349173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3492f9652e10SAl Viro const char *name, const struct open_flags *op) 349373d049a4SAl Viro { 34949883d185SAl Viro struct nameidata nd; 349573d049a4SAl Viro struct file *file; 349651689104SPaul Moore struct filename *filename; 3497f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 349873d049a4SAl Viro 349973d049a4SAl Viro nd.root.mnt = mnt; 350073d049a4SAl Viro nd.root.dentry = dentry; 350173d049a4SAl Viro 3502b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 350373d049a4SAl Viro return ERR_PTR(-ELOOP); 350473d049a4SAl Viro 350551689104SPaul Moore filename = getname_kernel(name); 3506a1c83681SViresh Kumar if (IS_ERR(filename)) 350751689104SPaul Moore return ERR_CAST(filename); 350851689104SPaul Moore 35099883d185SAl Viro set_nameidata(&nd, -1, filename); 3510c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 351173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3512c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 351373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3514c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35159883d185SAl Viro restore_nameidata(); 351651689104SPaul Moore putname(filename); 351773d049a4SAl Viro return file; 351873d049a4SAl Viro } 351973d049a4SAl Viro 3520fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35211ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35221da177e4SLinus Torvalds { 3523c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3524391172c4SAl Viro struct qstr last; 3525391172c4SAl Viro int type; 3526c30dabfeSJan Kara int err2; 35271ac12b4bSJeff Layton int error; 35281ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35291ac12b4bSJeff Layton 35301ac12b4bSJeff Layton /* 35311ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35321ac12b4bSJeff Layton * other flags passed in are ignored! 35331ac12b4bSJeff Layton */ 35341ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35351ac12b4bSJeff Layton 35365c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35375c31b6ceSAl Viro if (IS_ERR(name)) 35385c31b6ceSAl Viro return ERR_CAST(name); 35391da177e4SLinus Torvalds 3540c663e5d8SChristoph Hellwig /* 3541c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3542c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3543c663e5d8SChristoph Hellwig */ 35445c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3545ed75e95dSAl Viro goto out; 3546c663e5d8SChristoph Hellwig 3547c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3548391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3549c663e5d8SChristoph Hellwig /* 3550c663e5d8SChristoph Hellwig * Do the final lookup. 3551c663e5d8SChristoph Hellwig */ 3552391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35535955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3554391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35551da177e4SLinus Torvalds if (IS_ERR(dentry)) 3556a8104a9fSAl Viro goto unlock; 3557c663e5d8SChristoph Hellwig 3558a8104a9fSAl Viro error = -EEXIST; 3559b18825a7SDavid Howells if (d_is_positive(dentry)) 3560a8104a9fSAl Viro goto fail; 3561b18825a7SDavid Howells 3562c663e5d8SChristoph Hellwig /* 3563c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3564c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3565c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3566c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3567c663e5d8SChristoph Hellwig */ 3568391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3569a8104a9fSAl Viro error = -ENOENT; 3570ed75e95dSAl Viro goto fail; 3571e9baf6e5SAl Viro } 3572c30dabfeSJan Kara if (unlikely(err2)) { 3573c30dabfeSJan Kara error = err2; 3574a8104a9fSAl Viro goto fail; 3575c30dabfeSJan Kara } 3576181c37b6SAl Viro putname(name); 3577e9baf6e5SAl Viro return dentry; 35781da177e4SLinus Torvalds fail: 3579a8104a9fSAl Viro dput(dentry); 3580a8104a9fSAl Viro dentry = ERR_PTR(error); 3581a8104a9fSAl Viro unlock: 35825955102cSAl Viro inode_unlock(path->dentry->d_inode); 3583c30dabfeSJan Kara if (!err2) 3584391172c4SAl Viro mnt_drop_write(path->mnt); 3585ed75e95dSAl Viro out: 3586391172c4SAl Viro path_put(path); 3587181c37b6SAl Viro putname(name); 3588ed75e95dSAl Viro return dentry; 3589dae6ad8fSAl Viro } 3590fa14a0b8SAl Viro 3591fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3592fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3593fa14a0b8SAl Viro { 3594181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3595181c37b6SAl Viro path, lookup_flags); 3596fa14a0b8SAl Viro } 3597dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3598dae6ad8fSAl Viro 3599921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3600921a1650SAl Viro { 3601921a1650SAl Viro dput(dentry); 36025955102cSAl Viro inode_unlock(path->dentry->d_inode); 3603a8104a9fSAl Viro mnt_drop_write(path->mnt); 3604921a1650SAl Viro path_put(path); 3605921a1650SAl Viro } 3606921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3607921a1650SAl Viro 3608520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36091ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3610dae6ad8fSAl Viro { 3611181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3612dae6ad8fSAl Viro } 3613dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3614dae6ad8fSAl Viro 36151a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36161da177e4SLinus Torvalds { 3617a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36181da177e4SLinus Torvalds 36191da177e4SLinus Torvalds if (error) 36201da177e4SLinus Torvalds return error; 36211da177e4SLinus Torvalds 362294f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36231da177e4SLinus Torvalds return -EPERM; 36241da177e4SLinus Torvalds 3625acfa4380SAl Viro if (!dir->i_op->mknod) 36261da177e4SLinus Torvalds return -EPERM; 36271da177e4SLinus Torvalds 362808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 362908ce5f16SSerge E. Hallyn if (error) 363008ce5f16SSerge E. Hallyn return error; 363108ce5f16SSerge E. Hallyn 36321da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36331da177e4SLinus Torvalds if (error) 36341da177e4SLinus Torvalds return error; 36351da177e4SLinus Torvalds 36361da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3637a74574aaSStephen Smalley if (!error) 3638f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36391da177e4SLinus Torvalds return error; 36401da177e4SLinus Torvalds } 36414d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36421da177e4SLinus Torvalds 3643f69aac00SAl Viro static int may_mknod(umode_t mode) 3644463c3197SDave Hansen { 3645463c3197SDave Hansen switch (mode & S_IFMT) { 3646463c3197SDave Hansen case S_IFREG: 3647463c3197SDave Hansen case S_IFCHR: 3648463c3197SDave Hansen case S_IFBLK: 3649463c3197SDave Hansen case S_IFIFO: 3650463c3197SDave Hansen case S_IFSOCK: 3651463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3652463c3197SDave Hansen return 0; 3653463c3197SDave Hansen case S_IFDIR: 3654463c3197SDave Hansen return -EPERM; 3655463c3197SDave Hansen default: 3656463c3197SDave Hansen return -EINVAL; 3657463c3197SDave Hansen } 3658463c3197SDave Hansen } 3659463c3197SDave Hansen 366087c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 366187c4e192SDominik Brodowski unsigned int dev) 36621da177e4SLinus Torvalds { 36631da177e4SLinus Torvalds struct dentry *dentry; 3664dae6ad8fSAl Viro struct path path; 3665dae6ad8fSAl Viro int error; 3666972567f1SJeff Layton unsigned int lookup_flags = 0; 36671da177e4SLinus Torvalds 36688e4bfca1SAl Viro error = may_mknod(mode); 36698e4bfca1SAl Viro if (error) 36708e4bfca1SAl Viro return error; 3671972567f1SJeff Layton retry: 3672972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3673dae6ad8fSAl Viro if (IS_ERR(dentry)) 3674dae6ad8fSAl Viro return PTR_ERR(dentry); 36752ad94ae6SAl Viro 3676dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3677ce3b0f8dSAl Viro mode &= ~current_umask(); 3678dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3679be6d3e56SKentaro Takeda if (error) 3680a8104a9fSAl Viro goto out; 36811da177e4SLinus Torvalds switch (mode & S_IFMT) { 36821da177e4SLinus Torvalds case 0: case S_IFREG: 3683312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 368405d1a717SMimi Zohar if (!error) 368505d1a717SMimi Zohar ima_post_path_mknod(dentry); 36861da177e4SLinus Torvalds break; 36871da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3688dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36891da177e4SLinus Torvalds new_decode_dev(dev)); 36901da177e4SLinus Torvalds break; 36911da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3692dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36931da177e4SLinus Torvalds break; 36941da177e4SLinus Torvalds } 3695a8104a9fSAl Viro out: 3696921a1650SAl Viro done_path_create(&path, dentry); 3697972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3698972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3699972567f1SJeff Layton goto retry; 3700972567f1SJeff Layton } 37011da177e4SLinus Torvalds return error; 37021da177e4SLinus Torvalds } 37031da177e4SLinus Torvalds 370487c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 370587c4e192SDominik Brodowski unsigned int, dev) 370687c4e192SDominik Brodowski { 370787c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 370887c4e192SDominik Brodowski } 370987c4e192SDominik Brodowski 37108208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37115590ff0dSUlrich Drepper { 371287c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 37135590ff0dSUlrich Drepper } 37145590ff0dSUlrich Drepper 371518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37161da177e4SLinus Torvalds { 3717a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37188de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37191da177e4SLinus Torvalds 37201da177e4SLinus Torvalds if (error) 37211da177e4SLinus Torvalds return error; 37221da177e4SLinus Torvalds 3723acfa4380SAl Viro if (!dir->i_op->mkdir) 37241da177e4SLinus Torvalds return -EPERM; 37251da177e4SLinus Torvalds 37261da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37271da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37281da177e4SLinus Torvalds if (error) 37291da177e4SLinus Torvalds return error; 37301da177e4SLinus Torvalds 37318de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37328de52778SAl Viro return -EMLINK; 37338de52778SAl Viro 37341da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3735a74574aaSStephen Smalley if (!error) 3736f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37371da177e4SLinus Torvalds return error; 37381da177e4SLinus Torvalds } 37394d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37401da177e4SLinus Torvalds 37410101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 37421da177e4SLinus Torvalds { 37436902d925SDave Hansen struct dentry *dentry; 3744dae6ad8fSAl Viro struct path path; 3745dae6ad8fSAl Viro int error; 3746b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37471da177e4SLinus Torvalds 3748b76d8b82SJeff Layton retry: 3749b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37506902d925SDave Hansen if (IS_ERR(dentry)) 3751dae6ad8fSAl Viro return PTR_ERR(dentry); 37526902d925SDave Hansen 3753dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3754ce3b0f8dSAl Viro mode &= ~current_umask(); 3755dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3756a8104a9fSAl Viro if (!error) 3757dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3758921a1650SAl Viro done_path_create(&path, dentry); 3759b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3760b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3761b76d8b82SJeff Layton goto retry; 3762b76d8b82SJeff Layton } 37631da177e4SLinus Torvalds return error; 37641da177e4SLinus Torvalds } 37651da177e4SLinus Torvalds 37660101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37670101db7aSDominik Brodowski { 37680101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37690101db7aSDominik Brodowski } 37700101db7aSDominik Brodowski 3771a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37725590ff0dSUlrich Drepper { 37730101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37745590ff0dSUlrich Drepper } 37755590ff0dSUlrich Drepper 37761da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37771da177e4SLinus Torvalds { 37781da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37791da177e4SLinus Torvalds 37801da177e4SLinus Torvalds if (error) 37811da177e4SLinus Torvalds return error; 37821da177e4SLinus Torvalds 3783acfa4380SAl Viro if (!dir->i_op->rmdir) 37841da177e4SLinus Torvalds return -EPERM; 37851da177e4SLinus Torvalds 37861d2ef590SAl Viro dget(dentry); 37875955102cSAl Viro inode_lock(dentry->d_inode); 3788912dbc15SSage Weil 37891da177e4SLinus Torvalds error = -EBUSY; 37907af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3791912dbc15SSage Weil goto out; 3792912dbc15SSage Weil 37931da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3794912dbc15SSage Weil if (error) 3795912dbc15SSage Weil goto out; 3796912dbc15SSage Weil 37971da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3798912dbc15SSage Weil if (error) 3799912dbc15SSage Weil goto out; 3800912dbc15SSage Weil 38018767712fSAl Viro shrink_dcache_parent(dentry); 38021da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3803d83c49f3SAl Viro dont_mount(dentry); 38048ed936b5SEric W. Biederman detach_mounts(dentry); 3805116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 38061da177e4SLinus Torvalds 3807912dbc15SSage Weil out: 38085955102cSAl Viro inode_unlock(dentry->d_inode); 38091d2ef590SAl Viro dput(dentry); 3810912dbc15SSage Weil if (!error) 3811912dbc15SSage Weil d_delete(dentry); 38121da177e4SLinus Torvalds return error; 38131da177e4SLinus Torvalds } 38144d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38151da177e4SLinus Torvalds 3816f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 38171da177e4SLinus Torvalds { 38181da177e4SLinus Torvalds int error = 0; 381991a27b2aSJeff Layton struct filename *name; 38201da177e4SLinus Torvalds struct dentry *dentry; 3821f5beed75SAl Viro struct path path; 3822f5beed75SAl Viro struct qstr last; 3823f5beed75SAl Viro int type; 3824c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3825c6ee9206SJeff Layton retry: 3826c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3827c1d4dd27SAl Viro &path, &last, &type); 382891a27b2aSJeff Layton if (IS_ERR(name)) 382991a27b2aSJeff Layton return PTR_ERR(name); 38301da177e4SLinus Torvalds 3831f5beed75SAl Viro switch (type) { 38321da177e4SLinus Torvalds case LAST_DOTDOT: 38331da177e4SLinus Torvalds error = -ENOTEMPTY; 38341da177e4SLinus Torvalds goto exit1; 38351da177e4SLinus Torvalds case LAST_DOT: 38361da177e4SLinus Torvalds error = -EINVAL; 38371da177e4SLinus Torvalds goto exit1; 38381da177e4SLinus Torvalds case LAST_ROOT: 38391da177e4SLinus Torvalds error = -EBUSY; 38401da177e4SLinus Torvalds goto exit1; 38411da177e4SLinus Torvalds } 38420612d9fbSOGAWA Hirofumi 3843f5beed75SAl Viro error = mnt_want_write(path.mnt); 3844c30dabfeSJan Kara if (error) 3845c30dabfeSJan Kara goto exit1; 38460612d9fbSOGAWA Hirofumi 38475955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3848f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38491da177e4SLinus Torvalds error = PTR_ERR(dentry); 38506902d925SDave Hansen if (IS_ERR(dentry)) 38516902d925SDave Hansen goto exit2; 3852e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3853e6bc45d6STheodore Ts'o error = -ENOENT; 3854e6bc45d6STheodore Ts'o goto exit3; 3855e6bc45d6STheodore Ts'o } 3856f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3857be6d3e56SKentaro Takeda if (error) 3858c30dabfeSJan Kara goto exit3; 3859f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38600622753bSDave Hansen exit3: 38611da177e4SLinus Torvalds dput(dentry); 38626902d925SDave Hansen exit2: 38635955102cSAl Viro inode_unlock(path.dentry->d_inode); 3864f5beed75SAl Viro mnt_drop_write(path.mnt); 38651da177e4SLinus Torvalds exit1: 3866f5beed75SAl Viro path_put(&path); 38671da177e4SLinus Torvalds putname(name); 3868c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3869c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3870c6ee9206SJeff Layton goto retry; 3871c6ee9206SJeff Layton } 38721da177e4SLinus Torvalds return error; 38731da177e4SLinus Torvalds } 38741da177e4SLinus Torvalds 38753cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38765590ff0dSUlrich Drepper { 38775590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38785590ff0dSUlrich Drepper } 38795590ff0dSUlrich Drepper 3880b21996e3SJ. Bruce Fields /** 3881b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3882b21996e3SJ. Bruce Fields * @dir: parent directory 3883b21996e3SJ. Bruce Fields * @dentry: victim 3884b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3885b21996e3SJ. Bruce Fields * 3886b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3887b21996e3SJ. Bruce Fields * 3888b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3889b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3890b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3891b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3892b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3893b21996e3SJ. Bruce Fields * 3894b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3895b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3896b21996e3SJ. Bruce Fields * to be NFS exported. 3897b21996e3SJ. Bruce Fields */ 3898b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38991da177e4SLinus Torvalds { 39009accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39011da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39021da177e4SLinus Torvalds 39031da177e4SLinus Torvalds if (error) 39041da177e4SLinus Torvalds return error; 39051da177e4SLinus Torvalds 3906acfa4380SAl Viro if (!dir->i_op->unlink) 39071da177e4SLinus Torvalds return -EPERM; 39081da177e4SLinus Torvalds 39095955102cSAl Viro inode_lock(target); 39108ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39111da177e4SLinus Torvalds error = -EBUSY; 39121da177e4SLinus Torvalds else { 39131da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3914bec1052eSAl Viro if (!error) { 39155a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39165a14696cSJ. Bruce Fields if (error) 3917b21996e3SJ. Bruce Fields goto out; 39181da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39198ed936b5SEric W. Biederman if (!error) { 3920d83c49f3SAl Viro dont_mount(dentry); 39218ed936b5SEric W. Biederman detach_mounts(dentry); 3922116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 39238ed936b5SEric W. Biederman } 3924bec1052eSAl Viro } 39251da177e4SLinus Torvalds } 3926b21996e3SJ. Bruce Fields out: 39275955102cSAl Viro inode_unlock(target); 39281da177e4SLinus Torvalds 39291da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39301da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39319accbb97SJ. Bruce Fields fsnotify_link_count(target); 39321da177e4SLinus Torvalds d_delete(dentry); 39331da177e4SLinus Torvalds } 39340eeca283SRobert Love 39351da177e4SLinus Torvalds return error; 39361da177e4SLinus Torvalds } 39374d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39381da177e4SLinus Torvalds 39391da177e4SLinus Torvalds /* 39401da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39411b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39421da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39431da177e4SLinus Torvalds * while waiting on the I/O. 39441da177e4SLinus Torvalds */ 3945da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39461da177e4SLinus Torvalds { 39472ad94ae6SAl Viro int error; 39481da177e4SLinus Torvalds struct dentry *dentry; 3949f5beed75SAl Viro struct path path; 3950f5beed75SAl Viro struct qstr last; 3951f5beed75SAl Viro int type; 39521da177e4SLinus Torvalds struct inode *inode = NULL; 3953b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39545d18f813SJeff Layton unsigned int lookup_flags = 0; 39555d18f813SJeff Layton retry: 3956da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 395791a27b2aSJeff Layton if (IS_ERR(name)) 395891a27b2aSJeff Layton return PTR_ERR(name); 39592ad94ae6SAl Viro 39601da177e4SLinus Torvalds error = -EISDIR; 3961f5beed75SAl Viro if (type != LAST_NORM) 39621da177e4SLinus Torvalds goto exit1; 39630612d9fbSOGAWA Hirofumi 3964f5beed75SAl Viro error = mnt_want_write(path.mnt); 3965c30dabfeSJan Kara if (error) 3966c30dabfeSJan Kara goto exit1; 3967b21996e3SJ. Bruce Fields retry_deleg: 39685955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3969f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39701da177e4SLinus Torvalds error = PTR_ERR(dentry); 39711da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39721da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3973f5beed75SAl Viro if (last.name[last.len]) 397450338b88STörök Edwin goto slashes; 39751da177e4SLinus Torvalds inode = dentry->d_inode; 3976b18825a7SDavid Howells if (d_is_negative(dentry)) 3977e6bc45d6STheodore Ts'o goto slashes; 39787de9c6eeSAl Viro ihold(inode); 3979f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3980be6d3e56SKentaro Takeda if (error) 3981c30dabfeSJan Kara goto exit2; 3982f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39831da177e4SLinus Torvalds exit2: 39841da177e4SLinus Torvalds dput(dentry); 39851da177e4SLinus Torvalds } 39865955102cSAl Viro inode_unlock(path.dentry->d_inode); 39871da177e4SLinus Torvalds if (inode) 39881da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3989b21996e3SJ. Bruce Fields inode = NULL; 3990b21996e3SJ. Bruce Fields if (delegated_inode) { 39915a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3992b21996e3SJ. Bruce Fields if (!error) 3993b21996e3SJ. Bruce Fields goto retry_deleg; 3994b21996e3SJ. Bruce Fields } 3995f5beed75SAl Viro mnt_drop_write(path.mnt); 39961da177e4SLinus Torvalds exit1: 3997f5beed75SAl Viro path_put(&path); 39985d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39995d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40005d18f813SJeff Layton inode = NULL; 40015d18f813SJeff Layton goto retry; 40025d18f813SJeff Layton } 4003da2f1362SChristoph Hellwig putname(name); 40041da177e4SLinus Torvalds return error; 40051da177e4SLinus Torvalds 40061da177e4SLinus Torvalds slashes: 4007b18825a7SDavid Howells if (d_is_negative(dentry)) 4008b18825a7SDavid Howells error = -ENOENT; 400944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4010b18825a7SDavid Howells error = -EISDIR; 4011b18825a7SDavid Howells else 4012b18825a7SDavid Howells error = -ENOTDIR; 40131da177e4SLinus Torvalds goto exit2; 40141da177e4SLinus Torvalds } 40151da177e4SLinus Torvalds 40162e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40175590ff0dSUlrich Drepper { 40185590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40195590ff0dSUlrich Drepper return -EINVAL; 40205590ff0dSUlrich Drepper 40215590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40225590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40235590ff0dSUlrich Drepper 4024da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40255590ff0dSUlrich Drepper } 40265590ff0dSUlrich Drepper 40273480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40285590ff0dSUlrich Drepper { 4029da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40305590ff0dSUlrich Drepper } 40315590ff0dSUlrich Drepper 4032db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40331da177e4SLinus Torvalds { 4034a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40351da177e4SLinus Torvalds 40361da177e4SLinus Torvalds if (error) 40371da177e4SLinus Torvalds return error; 40381da177e4SLinus Torvalds 4039acfa4380SAl Viro if (!dir->i_op->symlink) 40401da177e4SLinus Torvalds return -EPERM; 40411da177e4SLinus Torvalds 40421da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40431da177e4SLinus Torvalds if (error) 40441da177e4SLinus Torvalds return error; 40451da177e4SLinus Torvalds 40461da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4047a74574aaSStephen Smalley if (!error) 4048f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40491da177e4SLinus Torvalds return error; 40501da177e4SLinus Torvalds } 40514d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40521da177e4SLinus Torvalds 4053b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4054b724e846SDominik Brodowski const char __user *newname) 40551da177e4SLinus Torvalds { 40562ad94ae6SAl Viro int error; 405791a27b2aSJeff Layton struct filename *from; 40586902d925SDave Hansen struct dentry *dentry; 4059dae6ad8fSAl Viro struct path path; 4060f46d3567SJeff Layton unsigned int lookup_flags = 0; 40611da177e4SLinus Torvalds 40621da177e4SLinus Torvalds from = getname(oldname); 40631da177e4SLinus Torvalds if (IS_ERR(from)) 40641da177e4SLinus Torvalds return PTR_ERR(from); 4065f46d3567SJeff Layton retry: 4066f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40671da177e4SLinus Torvalds error = PTR_ERR(dentry); 40686902d925SDave Hansen if (IS_ERR(dentry)) 4069dae6ad8fSAl Viro goto out_putname; 40706902d925SDave Hansen 407191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4072a8104a9fSAl Viro if (!error) 407391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4074921a1650SAl Viro done_path_create(&path, dentry); 4075f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4076f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4077f46d3567SJeff Layton goto retry; 4078f46d3567SJeff Layton } 40796902d925SDave Hansen out_putname: 40801da177e4SLinus Torvalds putname(from); 40811da177e4SLinus Torvalds return error; 40821da177e4SLinus Torvalds } 40831da177e4SLinus Torvalds 4084b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4085b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4086b724e846SDominik Brodowski { 4087b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4088b724e846SDominik Brodowski } 4089b724e846SDominik Brodowski 40903480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40915590ff0dSUlrich Drepper { 4092b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40935590ff0dSUlrich Drepper } 40945590ff0dSUlrich Drepper 4095146a8595SJ. Bruce Fields /** 4096146a8595SJ. Bruce Fields * vfs_link - create a new link 4097146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4098146a8595SJ. Bruce Fields * @dir: new parent 4099146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4100146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4101146a8595SJ. Bruce Fields * 4102146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4103146a8595SJ. Bruce Fields * 4104146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4105146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4106146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4107146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4108146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4109146a8595SJ. Bruce Fields * 4110146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4111146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4112146a8595SJ. Bruce Fields * to be NFS exported. 4113146a8595SJ. Bruce Fields */ 4114146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41151da177e4SLinus Torvalds { 41161da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41178de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41181da177e4SLinus Torvalds int error; 41191da177e4SLinus Torvalds 41201da177e4SLinus Torvalds if (!inode) 41211da177e4SLinus Torvalds return -ENOENT; 41221da177e4SLinus Torvalds 4123a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41241da177e4SLinus Torvalds if (error) 41251da177e4SLinus Torvalds return error; 41261da177e4SLinus Torvalds 41271da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41281da177e4SLinus Torvalds return -EXDEV; 41291da177e4SLinus Torvalds 41301da177e4SLinus Torvalds /* 41311da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41321da177e4SLinus Torvalds */ 41331da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41341da177e4SLinus Torvalds return -EPERM; 41350bd23d09SEric W. Biederman /* 41360bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41370bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41380bd23d09SEric W. Biederman * the vfs. 41390bd23d09SEric W. Biederman */ 41400bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41410bd23d09SEric W. Biederman return -EPERM; 4142acfa4380SAl Viro if (!dir->i_op->link) 41431da177e4SLinus Torvalds return -EPERM; 41447e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41451da177e4SLinus Torvalds return -EPERM; 41461da177e4SLinus Torvalds 41471da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41481da177e4SLinus Torvalds if (error) 41491da177e4SLinus Torvalds return error; 41501da177e4SLinus Torvalds 41515955102cSAl Viro inode_lock(inode); 4152aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4153f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4154aae8a97dSAneesh Kumar K.V error = -ENOENT; 41558de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41568de52778SAl Viro error = -EMLINK; 4157146a8595SJ. Bruce Fields else { 4158146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4159146a8595SJ. Bruce Fields if (!error) 41601da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4161146a8595SJ. Bruce Fields } 4162f4e0c30cSAl Viro 4163f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4164f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4165f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4166f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4167f4e0c30cSAl Viro } 41685955102cSAl Viro inode_unlock(inode); 4169e31e14ecSStephen Smalley if (!error) 41707e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41711da177e4SLinus Torvalds return error; 41721da177e4SLinus Torvalds } 41734d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41741da177e4SLinus Torvalds 41751da177e4SLinus Torvalds /* 41761da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41771da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41781da177e4SLinus Torvalds * newname. --KAB 41791da177e4SLinus Torvalds * 41801da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41811da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41821da177e4SLinus Torvalds * and other special files. --ADM 41831da177e4SLinus Torvalds */ 418446ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 418546ea89ebSDominik Brodowski const char __user *newname, int flags) 41861da177e4SLinus Torvalds { 41871da177e4SLinus Torvalds struct dentry *new_dentry; 4188dae6ad8fSAl Viro struct path old_path, new_path; 4189146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 419011a7b371SAneesh Kumar K.V int how = 0; 41911da177e4SLinus Torvalds int error; 41921da177e4SLinus Torvalds 419311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4194c04030e1SUlrich Drepper return -EINVAL; 419511a7b371SAneesh Kumar K.V /* 4196f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4197f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4198f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 419911a7b371SAneesh Kumar K.V */ 4200f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4201f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4202f0cc6ffbSLinus Torvalds return -ENOENT; 420311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4204f0cc6ffbSLinus Torvalds } 4205c04030e1SUlrich Drepper 420611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 420711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4208442e31caSJeff Layton retry: 420911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42101da177e4SLinus Torvalds if (error) 42112ad94ae6SAl Viro return error; 42122ad94ae6SAl Viro 4213442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4214442e31caSJeff Layton (how & LOOKUP_REVAL)); 42151da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42166902d925SDave Hansen if (IS_ERR(new_dentry)) 4217dae6ad8fSAl Viro goto out; 4218dae6ad8fSAl Viro 4219dae6ad8fSAl Viro error = -EXDEV; 4220dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4221dae6ad8fSAl Viro goto out_dput; 4222800179c9SKees Cook error = may_linkat(&old_path); 4223800179c9SKees Cook if (unlikely(error)) 4224800179c9SKees Cook goto out_dput; 4225dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4226be6d3e56SKentaro Takeda if (error) 4227a8104a9fSAl Viro goto out_dput; 4228146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 422975c3f29dSDave Hansen out_dput: 4230921a1650SAl Viro done_path_create(&new_path, new_dentry); 4231146a8595SJ. Bruce Fields if (delegated_inode) { 4232146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4233d22e6338SOleg Drokin if (!error) { 4234d22e6338SOleg Drokin path_put(&old_path); 4235146a8595SJ. Bruce Fields goto retry; 4236146a8595SJ. Bruce Fields } 4237d22e6338SOleg Drokin } 4238442e31caSJeff Layton if (retry_estale(error, how)) { 4239d22e6338SOleg Drokin path_put(&old_path); 4240442e31caSJeff Layton how |= LOOKUP_REVAL; 4241442e31caSJeff Layton goto retry; 4242442e31caSJeff Layton } 42431da177e4SLinus Torvalds out: 42442d8f3038SAl Viro path_put(&old_path); 42451da177e4SLinus Torvalds 42461da177e4SLinus Torvalds return error; 42471da177e4SLinus Torvalds } 42481da177e4SLinus Torvalds 424946ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 425046ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 425146ea89ebSDominik Brodowski { 425246ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 425346ea89ebSDominik Brodowski } 425446ea89ebSDominik Brodowski 42553480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42565590ff0dSUlrich Drepper { 425746ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42585590ff0dSUlrich Drepper } 42595590ff0dSUlrich Drepper 4260bc27027aSMiklos Szeredi /** 4261bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4262bc27027aSMiklos Szeredi * @old_dir: parent of source 4263bc27027aSMiklos Szeredi * @old_dentry: source 4264bc27027aSMiklos Szeredi * @new_dir: parent of destination 4265bc27027aSMiklos Szeredi * @new_dentry: destination 4266bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4267520c8b16SMiklos Szeredi * @flags: rename flags 4268bc27027aSMiklos Szeredi * 4269bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4270bc27027aSMiklos Szeredi * 4271bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4272bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4273bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4274bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4275bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4276bc27027aSMiklos Szeredi * so. 4277bc27027aSMiklos Szeredi * 4278bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4279bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4280bc27027aSMiklos Szeredi * to be NFS exported. 4281bc27027aSMiklos Szeredi * 42821da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42831da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42841da177e4SLinus Torvalds * Problems: 42850117d427SMauro Carvalho Chehab * 4286d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42871da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42881da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4289a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42901da177e4SLinus Torvalds * story. 42916cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42926cedba89SJ. Bruce Fields * and source (if it is not a directory). 42931b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42941da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42951da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4296a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42971da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42981da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42991da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4300a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43011da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43021da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43031da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4304e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43051b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43061da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4307c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43081da177e4SLinus Torvalds * locking]. 43091da177e4SLinus Torvalds */ 43101da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43118e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4312520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43131da177e4SLinus Torvalds { 43141da177e4SLinus Torvalds int error; 4315bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4316bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4317bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4318da1ce067SMiklos Szeredi bool new_is_dir = false; 4319da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 432049d31c2fSAl Viro struct name_snapshot old_name; 43211da177e4SLinus Torvalds 43228d3e2936SMiklos Szeredi if (source == target) 43231da177e4SLinus Torvalds return 0; 43241da177e4SLinus Torvalds 43251da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43261da177e4SLinus Torvalds if (error) 43271da177e4SLinus Torvalds return error; 43281da177e4SLinus Torvalds 4329da1ce067SMiklos Szeredi if (!target) { 4330a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4331da1ce067SMiklos Szeredi } else { 4332da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4333da1ce067SMiklos Szeredi 4334da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43351da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4336da1ce067SMiklos Szeredi else 4337da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4338da1ce067SMiklos Szeredi } 43391da177e4SLinus Torvalds if (error) 43401da177e4SLinus Torvalds return error; 43411da177e4SLinus Torvalds 43422773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43431da177e4SLinus Torvalds return -EPERM; 43441da177e4SLinus Torvalds 4345bc27027aSMiklos Szeredi /* 4346bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4347bc27027aSMiklos Szeredi * we'll need to flip '..'. 4348bc27027aSMiklos Szeredi */ 4349da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4350da1ce067SMiklos Szeredi if (is_dir) { 4351bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4352bc27027aSMiklos Szeredi if (error) 4353bc27027aSMiklos Szeredi return error; 4354bc27027aSMiklos Szeredi } 4355da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4356da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4357da1ce067SMiklos Szeredi if (error) 4358da1ce067SMiklos Szeredi return error; 4359da1ce067SMiklos Szeredi } 4360da1ce067SMiklos Szeredi } 43610eeca283SRobert Love 43620b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43630b3974ebSMiklos Szeredi flags); 4364bc27027aSMiklos Szeredi if (error) 4365bc27027aSMiklos Szeredi return error; 4366bc27027aSMiklos Szeredi 436749d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4368bc27027aSMiklos Szeredi dget(new_dentry); 4369da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4370bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4371bc27027aSMiklos Szeredi else if (target) 43725955102cSAl Viro inode_lock(target); 4373bc27027aSMiklos Szeredi 4374bc27027aSMiklos Szeredi error = -EBUSY; 43757af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4376bc27027aSMiklos Szeredi goto out; 4377bc27027aSMiklos Szeredi 4378da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4379bc27027aSMiklos Szeredi error = -EMLINK; 4380da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4381bc27027aSMiklos Szeredi goto out; 4382da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4383da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4384da1ce067SMiklos Szeredi goto out; 4385da1ce067SMiklos Szeredi } 4386da1ce067SMiklos Szeredi if (!is_dir) { 4387bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4388bc27027aSMiklos Szeredi if (error) 4389bc27027aSMiklos Szeredi goto out; 4390da1ce067SMiklos Szeredi } 4391da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4392bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4393bc27027aSMiklos Szeredi if (error) 4394bc27027aSMiklos Szeredi goto out; 4395bc27027aSMiklos Szeredi } 4396520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4397520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4398bc27027aSMiklos Szeredi if (error) 4399bc27027aSMiklos Szeredi goto out; 4400bc27027aSMiklos Szeredi 4401da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44028767712fSAl Viro if (is_dir) { 44038767712fSAl Viro shrink_dcache_parent(new_dentry); 4404bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 44058767712fSAl Viro } 4406bc27027aSMiklos Szeredi dont_mount(new_dentry); 44078ed936b5SEric W. Biederman detach_mounts(new_dentry); 4408bc27027aSMiklos Szeredi } 4409da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4410da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4411bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4412da1ce067SMiklos Szeredi else 4413da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4414da1ce067SMiklos Szeredi } 4415bc27027aSMiklos Szeredi out: 4416da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4417bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4418bc27027aSMiklos Szeredi else if (target) 44195955102cSAl Viro inode_unlock(target); 4420bc27027aSMiklos Szeredi dput(new_dentry); 4421da1ce067SMiklos Szeredi if (!error) { 4422f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4423da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4424da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4425f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4426da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4427da1ce067SMiklos Szeredi } 4428da1ce067SMiklos Szeredi } 442949d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44300eeca283SRobert Love 44311da177e4SLinus Torvalds return error; 44321da177e4SLinus Torvalds } 44334d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44341da177e4SLinus Torvalds 4435ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4436ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 44371da177e4SLinus Torvalds { 44381da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44391da177e4SLinus Torvalds struct dentry *trap; 4440f5beed75SAl Viro struct path old_path, new_path; 4441f5beed75SAl Viro struct qstr old_last, new_last; 4442f5beed75SAl Viro int old_type, new_type; 44438e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 444491a27b2aSJeff Layton struct filename *from; 444591a27b2aSJeff Layton struct filename *to; 4446f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4447c6a94284SJeff Layton bool should_retry = false; 44482ad94ae6SAl Viro int error; 4449520c8b16SMiklos Szeredi 44500d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4451da1ce067SMiklos Szeredi return -EINVAL; 4452da1ce067SMiklos Szeredi 44530d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44540d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4455520c8b16SMiklos Szeredi return -EINVAL; 4456520c8b16SMiklos Szeredi 44570d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44580d7a8555SMiklos Szeredi return -EPERM; 44590d7a8555SMiklos Szeredi 4460f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4461f5beed75SAl Viro target_flags = 0; 4462f5beed75SAl Viro 4463c6a94284SJeff Layton retry: 4464c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4465c1d4dd27SAl Viro &old_path, &old_last, &old_type); 446691a27b2aSJeff Layton if (IS_ERR(from)) { 446791a27b2aSJeff Layton error = PTR_ERR(from); 44681da177e4SLinus Torvalds goto exit; 446991a27b2aSJeff Layton } 44701da177e4SLinus Torvalds 4471c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4472c1d4dd27SAl Viro &new_path, &new_last, &new_type); 447391a27b2aSJeff Layton if (IS_ERR(to)) { 447491a27b2aSJeff Layton error = PTR_ERR(to); 44751da177e4SLinus Torvalds goto exit1; 447691a27b2aSJeff Layton } 44771da177e4SLinus Torvalds 44781da177e4SLinus Torvalds error = -EXDEV; 4479f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44801da177e4SLinus Torvalds goto exit2; 44811da177e4SLinus Torvalds 44821da177e4SLinus Torvalds error = -EBUSY; 4483f5beed75SAl Viro if (old_type != LAST_NORM) 44841da177e4SLinus Torvalds goto exit2; 44851da177e4SLinus Torvalds 44860a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44870a7c3937SMiklos Szeredi error = -EEXIST; 4488f5beed75SAl Viro if (new_type != LAST_NORM) 44891da177e4SLinus Torvalds goto exit2; 44901da177e4SLinus Torvalds 4491f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4492c30dabfeSJan Kara if (error) 4493c30dabfeSJan Kara goto exit2; 4494c30dabfeSJan Kara 44958e6d782cSJ. Bruce Fields retry_deleg: 4496f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44971da177e4SLinus Torvalds 4498f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44991da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45001da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45011da177e4SLinus Torvalds goto exit3; 45021da177e4SLinus Torvalds /* source must exist */ 45031da177e4SLinus Torvalds error = -ENOENT; 4504b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45051da177e4SLinus Torvalds goto exit4; 4506f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45071da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45081da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45091da177e4SLinus Torvalds goto exit4; 45100a7c3937SMiklos Szeredi error = -EEXIST; 45110a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45120a7c3937SMiklos Szeredi goto exit5; 4513da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4514da1ce067SMiklos Szeredi error = -ENOENT; 4515da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4516da1ce067SMiklos Szeredi goto exit5; 4517da1ce067SMiklos Szeredi 4518da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4519da1ce067SMiklos Szeredi error = -ENOTDIR; 4520f5beed75SAl Viro if (new_last.name[new_last.len]) 4521da1ce067SMiklos Szeredi goto exit5; 4522da1ce067SMiklos Szeredi } 4523da1ce067SMiklos Szeredi } 45240a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45250a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45260a7c3937SMiklos Szeredi error = -ENOTDIR; 4527f5beed75SAl Viro if (old_last.name[old_last.len]) 45280a7c3937SMiklos Szeredi goto exit5; 4529f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45300a7c3937SMiklos Szeredi goto exit5; 45310a7c3937SMiklos Szeredi } 45320a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45330a7c3937SMiklos Szeredi error = -EINVAL; 45340a7c3937SMiklos Szeredi if (old_dentry == trap) 45350a7c3937SMiklos Szeredi goto exit5; 45361da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4537da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45381da177e4SLinus Torvalds error = -ENOTEMPTY; 45391da177e4SLinus Torvalds if (new_dentry == trap) 45401da177e4SLinus Torvalds goto exit5; 45411da177e4SLinus Torvalds 4542f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4543f5beed75SAl Viro &new_path, new_dentry, flags); 4544be6d3e56SKentaro Takeda if (error) 4545c30dabfeSJan Kara goto exit5; 4546f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4547f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4548520c8b16SMiklos Szeredi &delegated_inode, flags); 45491da177e4SLinus Torvalds exit5: 45501da177e4SLinus Torvalds dput(new_dentry); 45511da177e4SLinus Torvalds exit4: 45521da177e4SLinus Torvalds dput(old_dentry); 45531da177e4SLinus Torvalds exit3: 4554f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45558e6d782cSJ. Bruce Fields if (delegated_inode) { 45568e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45578e6d782cSJ. Bruce Fields if (!error) 45588e6d782cSJ. Bruce Fields goto retry_deleg; 45598e6d782cSJ. Bruce Fields } 4560f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45611da177e4SLinus Torvalds exit2: 4562c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4563c6a94284SJeff Layton should_retry = true; 4564f5beed75SAl Viro path_put(&new_path); 45652ad94ae6SAl Viro putname(to); 45661da177e4SLinus Torvalds exit1: 4567f5beed75SAl Viro path_put(&old_path); 45681da177e4SLinus Torvalds putname(from); 4569c6a94284SJeff Layton if (should_retry) { 4570c6a94284SJeff Layton should_retry = false; 4571c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4572c6a94284SJeff Layton goto retry; 4573c6a94284SJeff Layton } 45742ad94ae6SAl Viro exit: 45751da177e4SLinus Torvalds return error; 45761da177e4SLinus Torvalds } 45771da177e4SLinus Torvalds 4578ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4579ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4580ee81feb6SDominik Brodowski { 4581ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4582ee81feb6SDominik Brodowski } 4583ee81feb6SDominik Brodowski 4584520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4585520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4586520c8b16SMiklos Szeredi { 4587ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4588520c8b16SMiklos Szeredi } 4589520c8b16SMiklos Szeredi 4590a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45915590ff0dSUlrich Drepper { 4592ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45935590ff0dSUlrich Drepper } 45945590ff0dSUlrich Drepper 4595787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4596787fb6bcSMiklos Szeredi { 4597787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4598787fb6bcSMiklos Szeredi if (error) 4599787fb6bcSMiklos Szeredi return error; 4600787fb6bcSMiklos Szeredi 4601787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4602787fb6bcSMiklos Szeredi return -EPERM; 4603787fb6bcSMiklos Szeredi 4604787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4605787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4606787fb6bcSMiklos Szeredi } 4607787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4608787fb6bcSMiklos Szeredi 46095d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46101da177e4SLinus Torvalds { 46115d826c84SAl Viro int len = PTR_ERR(link); 46121da177e4SLinus Torvalds if (IS_ERR(link)) 46131da177e4SLinus Torvalds goto out; 46141da177e4SLinus Torvalds 46151da177e4SLinus Torvalds len = strlen(link); 46161da177e4SLinus Torvalds if (len > (unsigned) buflen) 46171da177e4SLinus Torvalds len = buflen; 46181da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46191da177e4SLinus Torvalds len = -EFAULT; 46201da177e4SLinus Torvalds out: 46211da177e4SLinus Torvalds return len; 46221da177e4SLinus Torvalds } 46231da177e4SLinus Torvalds 4624d60874cdSMiklos Szeredi /** 4625fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4626fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4627fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4628fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4629fd4a0edfSMiklos Szeredi * 4630fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4631fd4a0edfSMiklos Szeredi * 4632fd4a0edfSMiklos Szeredi * Does not call security hook. 4633fd4a0edfSMiklos Szeredi */ 4634fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4635fd4a0edfSMiklos Szeredi { 4636fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4637f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4638f2df5da6SAl Viro const char *link; 4639f2df5da6SAl Viro int res; 4640fd4a0edfSMiklos Szeredi 464176fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 464276fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 464376fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 464476fca90eSMiklos Szeredi 464576fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4646fd4a0edfSMiklos Szeredi return -EINVAL; 4647fd4a0edfSMiklos Szeredi 464876fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 464976fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 465076fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 465176fca90eSMiklos Szeredi } 465276fca90eSMiklos Szeredi 46534c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4654f2df5da6SAl Viro if (!link) { 4655f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4656f2df5da6SAl Viro if (IS_ERR(link)) 4657f2df5da6SAl Viro return PTR_ERR(link); 4658f2df5da6SAl Viro } 4659f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4660f2df5da6SAl Viro do_delayed_call(&done); 4661f2df5da6SAl Viro return res; 4662fd4a0edfSMiklos Szeredi } 4663fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46641da177e4SLinus Torvalds 4665d60874cdSMiklos Szeredi /** 4666d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4667d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4668d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4669d60874cdSMiklos Szeredi * 4670d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4671d60874cdSMiklos Szeredi * 4672d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4673d60874cdSMiklos Szeredi * 4674d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4675d60874cdSMiklos Szeredi */ 4676d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4677d60874cdSMiklos Szeredi { 4678d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4679d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4680d60874cdSMiklos Szeredi 4681d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4682d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4683d60874cdSMiklos Szeredi if (!res) 4684d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4685d60874cdSMiklos Szeredi } 4686d60874cdSMiklos Szeredi return res; 4687d60874cdSMiklos Szeredi } 4688d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4689d60874cdSMiklos Szeredi 46901da177e4SLinus Torvalds /* get the link contents into pagecache */ 46916b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4692fceef393SAl Viro struct delayed_call *callback) 46931da177e4SLinus Torvalds { 4694ebd09abbSDuane Griffin char *kaddr; 46951da177e4SLinus Torvalds struct page *page; 46966b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46976b255391SAl Viro 4698d3883d4fSAl Viro if (!dentry) { 4699d3883d4fSAl Viro page = find_get_page(mapping, 0); 4700d3883d4fSAl Viro if (!page) 47016b255391SAl Viro return ERR_PTR(-ECHILD); 4702d3883d4fSAl Viro if (!PageUptodate(page)) { 4703d3883d4fSAl Viro put_page(page); 4704d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4705d3883d4fSAl Viro } 4706d3883d4fSAl Viro } else { 4707090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47081da177e4SLinus Torvalds if (IS_ERR(page)) 47096fe6900eSNick Piggin return (char*)page; 4710d3883d4fSAl Viro } 4711fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 471221fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 471321fc61c7SAl Viro kaddr = page_address(page); 47146b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4715ebd09abbSDuane Griffin return kaddr; 47161da177e4SLinus Torvalds } 47171da177e4SLinus Torvalds 47186b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47191da177e4SLinus Torvalds 4720fceef393SAl Viro void page_put_link(void *arg) 47211da177e4SLinus Torvalds { 4722fceef393SAl Viro put_page(arg); 47231da177e4SLinus Torvalds } 47244d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47251da177e4SLinus Torvalds 4726aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4727aa80deabSAl Viro { 4728fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47296b255391SAl Viro int res = readlink_copy(buffer, buflen, 47306b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4731fceef393SAl Viro &done)); 4732fceef393SAl Viro do_delayed_call(&done); 4733aa80deabSAl Viro return res; 4734aa80deabSAl Viro } 4735aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4736aa80deabSAl Viro 473754566b2cSNick Piggin /* 473854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 473954566b2cSNick Piggin */ 474054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47411da177e4SLinus Torvalds { 47421da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47430adb25d2SKirill Korotaev struct page *page; 4744afddba49SNick Piggin void *fsdata; 4745beb497abSDmitriy Monakhov int err; 4746c718a975STetsuo Handa unsigned int flags = 0; 474754566b2cSNick Piggin if (nofs) 474854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47491da177e4SLinus Torvalds 47507e53cac4SNeilBrown retry: 4751afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 475254566b2cSNick Piggin flags, &page, &fsdata); 47531da177e4SLinus Torvalds if (err) 4754afddba49SNick Piggin goto fail; 4755afddba49SNick Piggin 475621fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4757afddba49SNick Piggin 4758afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4759afddba49SNick Piggin page, fsdata); 47601da177e4SLinus Torvalds if (err < 0) 47611da177e4SLinus Torvalds goto fail; 4762afddba49SNick Piggin if (err < len-1) 4763afddba49SNick Piggin goto retry; 4764afddba49SNick Piggin 47651da177e4SLinus Torvalds mark_inode_dirty(inode); 47661da177e4SLinus Torvalds return 0; 47671da177e4SLinus Torvalds fail: 47681da177e4SLinus Torvalds return err; 47691da177e4SLinus Torvalds } 47704d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47711da177e4SLinus Torvalds 47720adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47730adb25d2SKirill Korotaev { 47740adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4775c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47760adb25d2SKirill Korotaev } 47774d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47780adb25d2SKirill Korotaev 477992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47806b255391SAl Viro .get_link = page_get_link, 47811da177e4SLinus Torvalds }; 47821da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4783