4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
21 #include <linux/namei.h>
22 #include <linux/pagemap.h>
23 #include <linux/fsnotify.h>
24 #include <linux/personality.h>
25 #include <linux/security.h>
26 #include <linux/ima.h>
27 #include <linux/syscalls.h>
28 #include <linux/mount.h>
29 #include <linux/audit.h>
30 #include <linux/capability.h>
31 #include <linux/file.h>
32 #include <linux/fcntl.h>
33 #include <linux/device_cgroup.h>
34 #include <linux/fs_struct.h>
35 #include <asm/uaccess.h>
39 /* [Feb-1997 T. Schoebel-Theuer]
40 * Fundamental changes in the pathname lookup mechanisms (namei)
41 * were necessary because of omirr. The reason is that omirr needs
42 * to know the _real_ pathname, not the user-supplied one, in case
43 * of symlinks (and also when transname replacements occur).
45 * The new code replaces the old recursive symlink resolution with
46 * an iterative one (in case of non-nested symlink chains). It does
47 * this with calls to <fs>_follow_link().
48 * As a side effect, dir_namei(), _namei() and follow_link() are now
49 * replaced with a single function lookup_dentry() that can handle all
50 * the special cases of the former code.
52 * With the new dcache, the pathname is stored at each inode, at least as
53 * long as the refcount of the inode is positive. As a side effect, the
54 * size of the dcache depends on the inode cache and thus is dynamic.
56 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
57 * resolution to correspond with current state of the code.
59 * Note that the symlink resolution is not *completely* iterative.
60 * There is still a significant amount of tail- and mid- recursion in
61 * the algorithm. Also, note that <fs>_readlink() is not used in
62 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
63 * may return different results than <fs>_follow_link(). Many virtual
64 * filesystems (including /proc) exhibit this behavior.
67 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
68 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
69 * and the name already exists in form of a symlink, try to create the new
70 * name indicated by the symlink. The old code always complained that the
71 * name already exists, due to not following the symlink even if its target
72 * is nonexistent. The new semantics affects also mknod() and link() when
73 * the name is a symlink pointing to a non-existant name.
75 * I don't know which semantics is the right one, since I have no access
76 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
77 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
78 * "old" one. Personally, I think the new semantics is much more logical.
79 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
80 * file does succeed in both HP-UX and SunOs, but not in Solaris
81 * and in the old Linux semantics.
84 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
85 * semantics. See the comments in "open_namei" and "do_link" below.
87 * [10-Sep-98 Alan Modra] Another symlink change.
90 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
91 * inside the path - always follow.
92 * in the last component in creation/removal/renaming - never follow.
93 * if LOOKUP_FOLLOW passed - follow.
94 * if the pathname has trailing slashes - follow.
95 * otherwise - don't follow.
96 * (applied in that order).
98 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
99 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
100 * During the 2.4 we need to fix the userland stuff depending on it -
101 * hopefully we will be able to get rid of that wart in 2.5. So far only
102 * XEmacs seems to be relying on it...
105 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
106 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
107 * any extra contention...
110 /* In order to reduce some races, while at the same time doing additional
111 * checking and hopefully speeding things up, we copy filenames to the
112 * kernel data space before using them..
114 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
115 * PATH_MAX includes the nul terminator --RR.
117 static int do_getname(const char __user *filename, char *page)
120 unsigned long len = PATH_MAX;
122 if (!segment_eq(get_fs(), KERNEL_DS)) {
123 if ((unsigned long) filename >= TASK_SIZE)
125 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
126 len = TASK_SIZE - (unsigned long) filename;
129 retval = strncpy_from_user(page, filename, len);
133 return -ENAMETOOLONG;
139 char * getname(const char __user * filename)
143 result = ERR_PTR(-ENOMEM);
146 int retval = do_getname(filename, tmp);
151 result = ERR_PTR(retval);
154 audit_getname(result);
158 #ifdef CONFIG_AUDITSYSCALL
159 void putname(const char *name)
161 if (unlikely(!audit_dummy_context()))
166 EXPORT_SYMBOL(putname);
170 * This does basic POSIX ACL permission checking
172 static inline int __acl_permission_check(struct inode *inode, int mask,
173 int (*check_acl)(struct inode *inode, int mask), int rcu)
175 umode_t mode = inode->i_mode;
177 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
179 if (current_fsuid() == inode->i_uid)
182 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
186 int error = check_acl(inode, mask);
187 if (error != -EAGAIN)
192 if (in_group_p(inode->i_gid))
197 * If the DACs are ok we don't need any capability check.
199 if ((mask & ~mode) == 0)
204 static inline int acl_permission_check(struct inode *inode, int mask,
205 int (*check_acl)(struct inode *inode, int mask))
207 return __acl_permission_check(inode, mask, check_acl, 0);
211 * generic_permission - check for access rights on a Posix-like filesystem
212 * @inode: inode to check access rights for
213 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
214 * @check_acl: optional callback to check for Posix ACLs
216 * Used to check for read/write/execute permissions on a file.
217 * We use "fsuid" for this, letting us set arbitrary permissions
218 * for filesystem access without changing the "normal" uids which
219 * are used for other things..
221 int generic_permission(struct inode *inode, int mask,
222 int (*check_acl)(struct inode *inode, int mask))
227 * Do the basic POSIX ACL permission checks.
229 ret = acl_permission_check(inode, mask, check_acl);
234 * Read/write DACs are always overridable.
235 * Executable DACs are overridable if at least one exec bit is set.
237 if (!(mask & MAY_EXEC) || execute_ok(inode))
238 if (capable(CAP_DAC_OVERRIDE))
242 * Searching includes executable on directories, else just read.
244 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
245 if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
246 if (capable(CAP_DAC_READ_SEARCH))
253 * inode_permission - check for access rights to a given inode
254 * @inode: inode to check permission on
255 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
257 * Used to check for read/write/execute permissions on an inode.
258 * We use "fsuid" for this, letting us set arbitrary permissions
259 * for filesystem access without changing the "normal" uids which
260 * are used for other things.
262 int inode_permission(struct inode *inode, int mask)
266 if (mask & MAY_WRITE) {
267 umode_t mode = inode->i_mode;
270 * Nobody gets write access to a read-only fs.
272 if (IS_RDONLY(inode) &&
273 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
277 * Nobody gets write access to an immutable file.
279 if (IS_IMMUTABLE(inode))
283 if (inode->i_op->permission)
284 retval = inode->i_op->permission(inode, mask);
286 retval = generic_permission(inode, mask, inode->i_op->check_acl);
291 retval = devcgroup_inode_permission(inode, mask);
295 return security_inode_permission(inode, mask);
299 * file_permission - check for additional access rights to a given file
300 * @file: file to check access rights for
301 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
303 * Used to check for read/write/execute permissions on an already opened
307 * Do not use this function in new code. All access checks should
308 * be done using inode_permission().
310 int file_permission(struct file *file, int mask)
312 return inode_permission(file->f_path.dentry->d_inode, mask);
316 * get_write_access() gets write permission for a file.
317 * put_write_access() releases this write permission.
318 * This is used for regular files.
319 * We cannot support write (and maybe mmap read-write shared) accesses and
320 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
321 * can have the following values:
322 * 0: no writers, no VM_DENYWRITE mappings
323 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
324 * > 0: (i_writecount) users are writing to the file.
326 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
327 * except for the cases where we don't hold i_writecount yet. Then we need to
328 * use {get,deny}_write_access() - these functions check the sign and refuse
329 * to do the change if sign is wrong. Exclusion between them is provided by
330 * the inode->i_lock spinlock.
333 int get_write_access(struct inode * inode)
335 spin_lock(&inode->i_lock);
336 if (atomic_read(&inode->i_writecount) < 0) {
337 spin_unlock(&inode->i_lock);
340 atomic_inc(&inode->i_writecount);
341 spin_unlock(&inode->i_lock);
346 int deny_write_access(struct file * file)
348 struct inode *inode = file->f_path.dentry->d_inode;
350 spin_lock(&inode->i_lock);
351 if (atomic_read(&inode->i_writecount) > 0) {
352 spin_unlock(&inode->i_lock);
355 atomic_dec(&inode->i_writecount);
356 spin_unlock(&inode->i_lock);
362 * path_get - get a reference to a path
363 * @path: path to get the reference to
365 * Given a path increment the reference count to the dentry and the vfsmount.
367 void path_get(struct path *path)
372 EXPORT_SYMBOL(path_get);
375 * path_put - put a reference to a path
376 * @path: path to put the reference to
378 * Given a path decrement the reference count to the dentry and the vfsmount.
380 void path_put(struct path *path)
385 EXPORT_SYMBOL(path_put);
388 * nameidata_drop_rcu - drop this nameidata out of rcu-walk
389 * @nd: nameidata pathwalk data to drop
390 * @Returns: 0 on success, -ECHLID on failure
392 * Path walking has 2 modes, rcu-walk and ref-walk (see
393 * Documentation/filesystems/path-lookup.txt). __drop_rcu* functions attempt
394 * to drop out of rcu-walk mode and take normal reference counts on dentries
395 * and vfsmounts to transition to rcu-walk mode. __drop_rcu* functions take
396 * refcounts at the last known good point before rcu-walk got stuck, so
397 * ref-walk may continue from there. If this is not successful (eg. a seqcount
398 * has changed), then failure is returned and path walk restarts from the
399 * beginning in ref-walk mode.
401 * nameidata_drop_rcu attempts to drop the current nd->path and nd->root into
402 * ref-walk. Must be called from rcu-walk context.
404 static int nameidata_drop_rcu(struct nameidata *nd)
406 struct fs_struct *fs = current->fs;
407 struct dentry *dentry = nd->path.dentry;
409 BUG_ON(!(nd->flags & LOOKUP_RCU));
411 spin_lock(&fs->lock);
412 if (nd->root.mnt != fs->root.mnt ||
413 nd->root.dentry != fs->root.dentry)
416 spin_lock(&dentry->d_lock);
417 if (!__d_rcu_to_refcount(dentry, nd->seq))
419 BUG_ON(nd->inode != dentry->d_inode);
420 spin_unlock(&dentry->d_lock);
423 spin_unlock(&fs->lock);
425 mntget(nd->path.mnt);
428 br_read_unlock(vfsmount_lock);
429 nd->flags &= ~LOOKUP_RCU;
432 spin_unlock(&dentry->d_lock);
435 spin_unlock(&fs->lock);
439 /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */
440 static inline int nameidata_drop_rcu_maybe(struct nameidata *nd)
442 if (nd->flags & LOOKUP_RCU)
443 return nameidata_drop_rcu(nd);
448 * nameidata_dentry_drop_rcu - drop nameidata and dentry out of rcu-walk
449 * @nd: nameidata pathwalk data to drop
450 * @dentry: dentry to drop
451 * @Returns: 0 on success, -ECHLID on failure
453 * nameidata_dentry_drop_rcu attempts to drop the current nd->path and nd->root,
454 * and dentry into ref-walk. @dentry must be a path found by a do_lookup call on
455 * @nd. Must be called from rcu-walk context.
457 static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry)
459 struct fs_struct *fs = current->fs;
460 struct dentry *parent = nd->path.dentry;
462 BUG_ON(!(nd->flags & LOOKUP_RCU));
464 spin_lock(&fs->lock);
465 if (nd->root.mnt != fs->root.mnt ||
466 nd->root.dentry != fs->root.dentry)
469 spin_lock(&parent->d_lock);
470 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
471 if (!__d_rcu_to_refcount(dentry, nd->seq))
474 * If the sequence check on the child dentry passed, then the child has
475 * not been removed from its parent. This means the parent dentry must
476 * be valid and able to take a reference at this point.
478 BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
479 BUG_ON(!parent->d_count);
481 spin_unlock(&dentry->d_lock);
482 spin_unlock(&parent->d_lock);
485 spin_unlock(&fs->lock);
487 mntget(nd->path.mnt);
490 br_read_unlock(vfsmount_lock);
491 nd->flags &= ~LOOKUP_RCU;
494 spin_unlock(&dentry->d_lock);
495 spin_unlock(&parent->d_lock);
498 spin_unlock(&fs->lock);
502 /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */
503 static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry)
505 if (nd->flags & LOOKUP_RCU)
506 return nameidata_dentry_drop_rcu(nd, dentry);
511 * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk
512 * @nd: nameidata pathwalk data to drop
513 * @Returns: 0 on success, -ECHLID on failure
515 * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk.
516 * nd->path should be the final element of the lookup, so nd->root is discarded.
517 * Must be called from rcu-walk context.
519 static int nameidata_drop_rcu_last(struct nameidata *nd)
521 struct dentry *dentry = nd->path.dentry;
523 BUG_ON(!(nd->flags & LOOKUP_RCU));
524 nd->flags &= ~LOOKUP_RCU;
526 spin_lock(&dentry->d_lock);
527 if (!__d_rcu_to_refcount(dentry, nd->seq))
529 BUG_ON(nd->inode != dentry->d_inode);
530 spin_unlock(&dentry->d_lock);
532 mntget(nd->path.mnt);
535 br_read_unlock(vfsmount_lock);
540 spin_unlock(&dentry->d_lock);
542 br_read_unlock(vfsmount_lock);
546 /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */
547 static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd)
549 if (likely(nd->flags & LOOKUP_RCU))
550 return nameidata_drop_rcu_last(nd);
555 * release_open_intent - free up open intent resources
556 * @nd: pointer to nameidata
558 void release_open_intent(struct nameidata *nd)
560 if (nd->intent.open.file->f_path.dentry == NULL)
561 put_filp(nd->intent.open.file);
563 fput(nd->intent.open.file);
566 static inline struct dentry *
567 do_revalidate(struct dentry *dentry, struct nameidata *nd)
569 int status = dentry->d_op->d_revalidate(dentry, nd);
570 if (unlikely(status <= 0)) {
572 * The dentry failed validation.
573 * If d_revalidate returned 0 attempt to invalidate
574 * the dentry otherwise d_revalidate is asking us
575 * to return a fail status.
578 if (!d_invalidate(dentry)) {
584 dentry = ERR_PTR(status);
590 static inline int need_reval_dot(struct dentry *dentry)
592 if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
595 if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
602 * force_reval_path - force revalidation of a dentry
604 * In some situations the path walking code will trust dentries without
605 * revalidating them. This causes problems for filesystems that depend on
606 * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set
607 * (which indicates that it's possible for the dentry to go stale), force
608 * a d_revalidate call before proceeding.
610 * Returns 0 if the revalidation was successful. If the revalidation fails,
611 * either return the error returned by d_revalidate or -ESTALE if the
612 * revalidation it just returned 0. If d_revalidate returns 0, we attempt to
613 * invalidate the dentry. It's up to the caller to handle putting references
614 * to the path if necessary.
617 force_reval_path(struct path *path, struct nameidata *nd)
620 struct dentry *dentry = path->dentry;
623 * only check on filesystems where it's possible for the dentry to
626 if (!need_reval_dot(dentry))
629 status = dentry->d_op->d_revalidate(dentry, nd);
634 d_invalidate(dentry);
641 * Short-cut version of permission(), for calling on directories
642 * during pathname resolution. Combines parts of permission()
643 * and generic_permission(), and tests ONLY for MAY_EXEC permission.
645 * If appropriate, check DAC only. If not appropriate, or
646 * short-cut DAC fails, then call ->permission() to do more
647 * complete permission check.
649 static inline int __exec_permission(struct inode *inode, int rcu)
653 if (inode->i_op->permission) {
656 ret = inode->i_op->permission(inode, MAY_EXEC);
661 ret = __acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl, rcu);
664 if (rcu && ret == -ECHILD)
667 if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH))
672 return security_inode_exec_permission(inode, rcu);
675 static int exec_permission(struct inode *inode)
677 return __exec_permission(inode, 0);
680 static int exec_permission_rcu(struct inode *inode)
682 return __exec_permission(inode, 1);
685 static __always_inline void set_root(struct nameidata *nd)
688 get_fs_root(current->fs, &nd->root);
691 static int link_path_walk(const char *, struct nameidata *);
693 static __always_inline void set_root_rcu(struct nameidata *nd)
696 struct fs_struct *fs = current->fs;
700 seq = read_seqcount_begin(&fs->seq);
702 } while (read_seqcount_retry(&fs->seq, seq));
706 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
719 nd->inode = nd->path.dentry->d_inode;
721 ret = link_path_walk(link, nd);
725 return PTR_ERR(link);
728 static void path_put_conditional(struct path *path, struct nameidata *nd)
731 if (path->mnt != nd->path.mnt)
735 static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
737 if (!(nd->flags & LOOKUP_RCU)) {
738 dput(nd->path.dentry);
739 if (nd->path.mnt != path->mnt)
740 mntput(nd->path.mnt);
742 nd->path.mnt = path->mnt;
743 nd->path.dentry = path->dentry;
746 static __always_inline int
747 __do_follow_link(struct path *path, struct nameidata *nd, void **p)
750 struct dentry *dentry = path->dentry;
752 touch_atime(path->mnt, dentry);
753 nd_set_link(nd, NULL);
755 if (path->mnt != nd->path.mnt) {
756 path_to_nameidata(path, nd);
757 nd->inode = nd->path.dentry->d_inode;
762 nd->last_type = LAST_BIND;
763 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
766 char *s = nd_get_link(nd);
769 error = __vfs_follow_link(nd, s);
770 else if (nd->last_type == LAST_BIND) {
771 error = force_reval_path(&nd->path, nd);
780 * This limits recursive symlink follows to 8, while
781 * limiting consecutive symlinks to 40.
783 * Without that kind of total limit, nasty chains of consecutive
784 * symlinks can cause almost arbitrarily long lookups.
786 static inline int do_follow_link(struct path *path, struct nameidata *nd)
790 if (current->link_count >= MAX_NESTED_LINKS)
792 if (current->total_link_count >= 40)
794 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
796 err = security_inode_follow_link(path->dentry, nd);
799 current->link_count++;
800 current->total_link_count++;
802 err = __do_follow_link(path, nd, &cookie);
803 if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link)
804 path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie);
806 current->link_count--;
810 path_put_conditional(path, nd);
815 static int follow_up_rcu(struct path *path)
817 struct vfsmount *parent;
818 struct dentry *mountpoint;
820 parent = path->mnt->mnt_parent;
821 if (parent == path->mnt)
823 mountpoint = path->mnt->mnt_mountpoint;
824 path->dentry = mountpoint;
829 int follow_up(struct path *path)
831 struct vfsmount *parent;
832 struct dentry *mountpoint;
834 br_read_lock(vfsmount_lock);
835 parent = path->mnt->mnt_parent;
836 if (parent == path->mnt) {
837 br_read_unlock(vfsmount_lock);
841 mountpoint = dget(path->mnt->mnt_mountpoint);
842 br_read_unlock(vfsmount_lock);
844 path->dentry = mountpoint;
851 * serialization is taken care of in namespace.c
853 static void __follow_mount_rcu(struct nameidata *nd, struct path *path,
854 struct inode **inode)
856 while (d_mountpoint(path->dentry)) {
857 struct vfsmount *mounted;
858 mounted = __lookup_mnt(path->mnt, path->dentry, 1);
862 path->dentry = mounted->mnt_root;
863 nd->seq = read_seqcount_begin(&path->dentry->d_seq);
864 *inode = path->dentry->d_inode;
868 static int __follow_mount(struct path *path)
871 while (d_mountpoint(path->dentry)) {
872 struct vfsmount *mounted = lookup_mnt(path);
879 path->dentry = dget(mounted->mnt_root);
885 static void follow_mount(struct path *path)
887 while (d_mountpoint(path->dentry)) {
888 struct vfsmount *mounted = lookup_mnt(path);
894 path->dentry = dget(mounted->mnt_root);
898 int follow_down(struct path *path)
900 struct vfsmount *mounted;
902 mounted = lookup_mnt(path);
907 path->dentry = dget(mounted->mnt_root);
913 static int follow_dotdot_rcu(struct nameidata *nd)
915 struct inode *inode = nd->inode;
920 if (nd->path.dentry == nd->root.dentry &&
921 nd->path.mnt == nd->root.mnt) {
924 if (nd->path.dentry != nd->path.mnt->mnt_root) {
925 struct dentry *old = nd->path.dentry;
926 struct dentry *parent = old->d_parent;
929 seq = read_seqcount_begin(&parent->d_seq);
930 if (read_seqcount_retry(&old->d_seq, nd->seq))
932 inode = parent->d_inode;
933 nd->path.dentry = parent;
937 if (!follow_up_rcu(&nd->path))
939 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
940 inode = nd->path.dentry->d_inode;
942 __follow_mount_rcu(nd, &nd->path, &inode);
948 static void follow_dotdot(struct nameidata *nd)
953 struct dentry *old = nd->path.dentry;
955 if (nd->path.dentry == nd->root.dentry &&
956 nd->path.mnt == nd->root.mnt) {
959 if (nd->path.dentry != nd->path.mnt->mnt_root) {
960 /* rare case of legitimate dget_parent()... */
961 nd->path.dentry = dget_parent(nd->path.dentry);
965 if (!follow_up(&nd->path))
968 follow_mount(&nd->path);
969 nd->inode = nd->path.dentry->d_inode;
973 * Allocate a dentry with name and parent, and perform a parent
974 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
975 * on error. parent->d_inode->i_mutex must be held. d_lookup must
976 * have verified that no child exists while under i_mutex.
978 static struct dentry *d_alloc_and_lookup(struct dentry *parent,
979 struct qstr *name, struct nameidata *nd)
981 struct inode *inode = parent->d_inode;
982 struct dentry *dentry;
985 /* Don't create child dentry for a dead directory. */
986 if (unlikely(IS_DEADDIR(inode)))
987 return ERR_PTR(-ENOENT);
989 dentry = d_alloc(parent, name);
990 if (unlikely(!dentry))
991 return ERR_PTR(-ENOMEM);
993 old = inode->i_op->lookup(inode, dentry, nd);
1002 * It's more convoluted than I'd like it to be, but... it's still fairly
1003 * small and for now I'd prefer to have fast path as straight as possible.
1004 * It _is_ time-critical.
1006 static int do_lookup(struct nameidata *nd, struct qstr *name,
1007 struct path *path, struct inode **inode)
1009 struct vfsmount *mnt = nd->path.mnt;
1010 struct dentry *dentry, *parent = nd->path.dentry;
1013 * See if the low-level filesystem might want
1014 * to use its own hash..
1016 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
1017 int err = parent->d_op->d_hash(parent, nd->inode, name);
1023 * Rename seqlock is not required here because in the off chance
1024 * of a false negative due to a concurrent rename, we're going to
1025 * do the non-racy lookup, below.
1027 if (nd->flags & LOOKUP_RCU) {
1031 dentry = __d_lookup_rcu(parent, name, &seq, inode);
1033 if (nameidata_drop_rcu(nd))
1037 /* Memory barrier in read_seqcount_begin of child is enough */
1038 if (__read_seqcount_retry(&parent->d_seq, nd->seq))
1042 if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
1043 /* We commonly drop rcu-walk here */
1044 if (nameidata_dentry_drop_rcu(nd, dentry))
1046 goto need_revalidate;
1049 path->dentry = dentry;
1050 __follow_mount_rcu(nd, path, inode);
1052 dentry = __d_lookup(parent, name);
1056 if (dentry->d_flags & DCACHE_OP_REVALIDATE)
1057 goto need_revalidate;
1060 path->dentry = dentry;
1061 __follow_mount(path);
1062 *inode = path->dentry->d_inode;
1067 dir = parent->d_inode;
1068 BUG_ON(nd->inode != dir);
1070 mutex_lock(&dir->i_mutex);
1072 * First re-do the cached lookup just in case it was created
1073 * while we waited for the directory semaphore, or the first
1074 * lookup failed due to an unrelated rename.
1076 * This could use version numbering or similar to avoid unnecessary
1077 * cache lookups, but then we'd have to do the first lookup in the
1078 * non-racy way. However in the common case here, everything should
1079 * be hot in cache, so would it be a big win?
1081 dentry = d_lookup(parent, name);
1082 if (likely(!dentry)) {
1083 dentry = d_alloc_and_lookup(parent, name, nd);
1084 mutex_unlock(&dir->i_mutex);
1090 * Uhhuh! Nasty case: the cache was re-populated while
1091 * we waited on the semaphore. Need to revalidate.
1093 mutex_unlock(&dir->i_mutex);
1097 dentry = do_revalidate(dentry, nd);
1105 return PTR_ERR(dentry);
1109 * This is a temporary kludge to deal with "automount" symlinks; proper
1110 * solution is to trigger them on follow_mount(), so that do_lookup()
1111 * would DTRT. To be killed before 2.6.34-final.
1113 static inline int follow_on_final(struct inode *inode, unsigned lookup_flags)
1115 return inode && unlikely(inode->i_op->follow_link) &&
1116 ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode));
1121 * This is the basic name resolution function, turning a pathname into
1122 * the final dentry. We expect 'base' to be positive and a directory.
1124 * Returns 0 and nd will have valid dentry and mnt on success.
1125 * Returns error and drops reference to input namei data on failure.
1127 static int link_path_walk(const char *name, struct nameidata *nd)
1131 unsigned int lookup_flags = nd->flags;
1139 lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
1141 /* At this point we know we have a real path component. */
1143 struct inode *inode;
1148 nd->flags |= LOOKUP_CONTINUE;
1149 if (nd->flags & LOOKUP_RCU) {
1150 err = exec_permission_rcu(nd->inode);
1151 if (err == -ECHILD) {
1152 if (nameidata_drop_rcu(nd))
1158 err = exec_permission(nd->inode);
1164 c = *(const unsigned char *)name;
1166 hash = init_name_hash();
1169 hash = partial_name_hash(c, hash);
1170 c = *(const unsigned char *)name;
1171 } while (c && (c != '/'));
1172 this.len = name - (const char *) this.name;
1173 this.hash = end_name_hash(hash);
1175 /* remove trailing slashes? */
1177 goto last_component;
1178 while (*++name == '/');
1180 goto last_with_slashes;
1183 * "." and ".." are special - ".." especially so because it has
1184 * to be able to know about the current root directory and
1185 * parent relationships.
1187 if (this.name[0] == '.') switch (this.len) {
1191 if (this.name[1] != '.')
1193 if (nd->flags & LOOKUP_RCU) {
1194 if (follow_dotdot_rcu(nd))
1202 /* This does the actual lookups.. */
1203 err = do_lookup(nd, &this, &next, &inode);
1210 if (inode->i_op->follow_link) {
1211 /* We commonly drop rcu-walk here */
1212 if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
1214 BUG_ON(inode != next.dentry->d_inode);
1215 err = do_follow_link(&next, nd);
1218 nd->inode = nd->path.dentry->d_inode;
1223 path_to_nameidata(&next, nd);
1227 if (!nd->inode->i_op->lookup)
1230 /* here ends the main loop */
1233 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
1235 /* Clear LOOKUP_CONTINUE iff it was previously unset */
1236 nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
1237 if (lookup_flags & LOOKUP_PARENT)
1239 if (this.name[0] == '.') switch (this.len) {
1243 if (this.name[1] != '.')
1245 if (nd->flags & LOOKUP_RCU) {
1246 if (follow_dotdot_rcu(nd))
1254 err = do_lookup(nd, &this, &next, &inode);
1257 if (follow_on_final(inode, lookup_flags)) {
1258 if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
1260 BUG_ON(inode != next.dentry->d_inode);
1261 err = do_follow_link(&next, nd);
1264 nd->inode = nd->path.dentry->d_inode;
1266 path_to_nameidata(&next, nd);
1272 if (lookup_flags & LOOKUP_DIRECTORY) {
1274 if (!nd->inode->i_op->lookup)
1280 nd->last_type = LAST_NORM;
1281 if (this.name[0] != '.')
1284 nd->last_type = LAST_DOT;
1285 else if (this.len == 2 && this.name[1] == '.')
1286 nd->last_type = LAST_DOTDOT;
1291 * We bypassed the ordinary revalidation routines.
1292 * We may need to check the cached dentry for staleness.
1294 if (need_reval_dot(nd->path.dentry)) {
1295 if (nameidata_drop_rcu_maybe(nd))
1298 /* Note: we do not d_invalidate() */
1299 if (!nd->path.dentry->d_op->d_revalidate(
1300 nd->path.dentry, nd))
1304 if (nameidata_drop_rcu_last_maybe(nd))
1308 if (!(nd->flags & LOOKUP_RCU))
1309 path_put_conditional(&next, nd);
1312 if (!(nd->flags & LOOKUP_RCU))
1313 path_put(&nd->path);
1318 static inline int path_walk_rcu(const char *name, struct nameidata *nd)
1320 current->total_link_count = 0;
1322 return link_path_walk(name, nd);
1325 static inline int path_walk_simple(const char *name, struct nameidata *nd)
1327 current->total_link_count = 0;
1329 return link_path_walk(name, nd);
1332 static int path_walk(const char *name, struct nameidata *nd)
1334 struct path save = nd->path;
1337 current->total_link_count = 0;
1339 /* make sure the stuff we saved doesn't go away */
1342 result = link_path_walk(name, nd);
1343 if (result == -ESTALE) {
1344 /* nd->path had been dropped */
1345 current->total_link_count = 0;
1347 path_get(&nd->path);
1348 nd->flags |= LOOKUP_REVAL;
1349 result = link_path_walk(name, nd);
1357 static void path_finish_rcu(struct nameidata *nd)
1359 if (nd->flags & LOOKUP_RCU) {
1360 /* RCU dangling. Cancel it. */
1361 nd->flags &= ~LOOKUP_RCU;
1362 nd->root.mnt = NULL;
1364 br_read_unlock(vfsmount_lock);
1370 static int path_init_rcu(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
1376 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1377 nd->flags = flags | LOOKUP_RCU;
1379 nd->root.mnt = NULL;
1383 struct fs_struct *fs = current->fs;
1386 br_read_lock(vfsmount_lock);
1390 seq = read_seqcount_begin(&fs->seq);
1391 nd->root = fs->root;
1392 nd->path = nd->root;
1393 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1394 } while (read_seqcount_retry(&fs->seq, seq));
1396 } else if (dfd == AT_FDCWD) {
1397 struct fs_struct *fs = current->fs;
1400 br_read_lock(vfsmount_lock);
1404 seq = read_seqcount_begin(&fs->seq);
1406 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1407 } while (read_seqcount_retry(&fs->seq, seq));
1410 struct dentry *dentry;
1412 file = fget_light(dfd, &fput_needed);
1417 dentry = file->f_path.dentry;
1420 if (!S_ISDIR(dentry->d_inode->i_mode))
1423 retval = file_permission(file, MAY_EXEC);
1427 nd->path = file->f_path;
1431 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1432 br_read_lock(vfsmount_lock);
1435 nd->inode = nd->path.dentry->d_inode;
1439 fput_light(file, fput_needed);
1444 static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
1450 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1453 nd->root.mnt = NULL;
1457 nd->path = nd->root;
1458 path_get(&nd->root);
1459 } else if (dfd == AT_FDCWD) {
1460 get_fs_pwd(current->fs, &nd->path);
1462 struct dentry *dentry;
1464 file = fget_light(dfd, &fput_needed);
1469 dentry = file->f_path.dentry;
1472 if (!S_ISDIR(dentry->d_inode->i_mode))
1475 retval = file_permission(file, MAY_EXEC);
1479 nd->path = file->f_path;
1480 path_get(&file->f_path);
1482 fput_light(file, fput_needed);
1484 nd->inode = nd->path.dentry->d_inode;
1488 fput_light(file, fput_needed);
1493 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1494 static int do_path_lookup(int dfd, const char *name,
1495 unsigned int flags, struct nameidata *nd)
1500 * Path walking is largely split up into 2 different synchronisation
1501 * schemes, rcu-walk and ref-walk (explained in
1502 * Documentation/filesystems/path-lookup.txt). These share much of the
1503 * path walk code, but some things particularly setup, cleanup, and
1504 * following mounts are sufficiently divergent that functions are
1505 * duplicated. Typically there is a function foo(), and its RCU
1506 * analogue, foo_rcu().
1508 * -ECHILD is the error number of choice (just to avoid clashes) that
1509 * is returned if some aspect of an rcu-walk fails. Such an error must
1510 * be handled by restarting a traditional ref-walk (which will always
1511 * be able to complete).
1513 retval = path_init_rcu(dfd, name, flags, nd);
1514 if (unlikely(retval))
1516 retval = path_walk_rcu(name, nd);
1517 path_finish_rcu(nd);
1519 path_put(&nd->root);
1520 nd->root.mnt = NULL;
1523 if (unlikely(retval == -ECHILD || retval == -ESTALE)) {
1524 /* slower, locked walk */
1525 if (retval == -ESTALE)
1526 flags |= LOOKUP_REVAL;
1527 retval = path_init(dfd, name, flags, nd);
1528 if (unlikely(retval))
1530 retval = path_walk(name, nd);
1532 path_put(&nd->root);
1533 nd->root.mnt = NULL;
1537 if (likely(!retval)) {
1538 if (unlikely(!audit_dummy_context())) {
1539 if (nd->path.dentry && nd->inode)
1540 audit_inode(name, nd->path.dentry);
1547 int path_lookup(const char *name, unsigned int flags,
1548 struct nameidata *nd)
1550 return do_path_lookup(AT_FDCWD, name, flags, nd);
1553 int kern_path(const char *name, unsigned int flags, struct path *path)
1555 struct nameidata nd;
1556 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1563 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1564 * @dentry: pointer to dentry of the base directory
1565 * @mnt: pointer to vfs mount of the base directory
1566 * @name: pointer to file name
1567 * @flags: lookup flags
1568 * @nd: pointer to nameidata
1570 int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1571 const char *name, unsigned int flags,
1572 struct nameidata *nd)
1576 /* same as do_path_lookup */
1577 nd->last_type = LAST_ROOT;
1581 nd->path.dentry = dentry;
1583 path_get(&nd->path);
1584 nd->root = nd->path;
1585 path_get(&nd->root);
1586 nd->inode = nd->path.dentry->d_inode;
1588 retval = path_walk(name, nd);
1589 if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
1591 audit_inode(name, nd->path.dentry);
1593 path_put(&nd->root);
1594 nd->root.mnt = NULL;
1599 static struct dentry *__lookup_hash(struct qstr *name,
1600 struct dentry *base, struct nameidata *nd)
1602 struct inode *inode = base->d_inode;
1603 struct dentry *dentry;
1606 err = exec_permission(inode);
1608 return ERR_PTR(err);
1611 * See if the low-level filesystem might want
1612 * to use its own hash..
1614 if (base->d_flags & DCACHE_OP_HASH) {
1615 err = base->d_op->d_hash(base, inode, name);
1616 dentry = ERR_PTR(err);
1622 * Don't bother with __d_lookup: callers are for creat as
1623 * well as unlink, so a lot of the time it would cost
1626 dentry = d_lookup(base, name);
1628 if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE))
1629 dentry = do_revalidate(dentry, nd);
1632 dentry = d_alloc_and_lookup(base, name, nd);
1638 * Restricted form of lookup. Doesn't follow links, single-component only,
1639 * needs parent already locked. Doesn't follow mounts.
1642 static struct dentry *lookup_hash(struct nameidata *nd)
1644 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1647 static int __lookup_one_len(const char *name, struct qstr *this,
1648 struct dentry *base, int len)
1658 hash = init_name_hash();
1660 c = *(const unsigned char *)name++;
1661 if (c == '/' || c == '\0')
1663 hash = partial_name_hash(c, hash);
1665 this->hash = end_name_hash(hash);
1670 * lookup_one_len - filesystem helper to lookup single pathname component
1671 * @name: pathname component to lookup
1672 * @base: base directory to lookup from
1673 * @len: maximum length @len should be interpreted to
1675 * Note that this routine is purely a helper for filesystem usage and should
1676 * not be called by generic code. Also note that by using this function the
1677 * nameidata argument is passed to the filesystem methods and a filesystem
1678 * using this helper needs to be prepared for that.
1680 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1685 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1687 err = __lookup_one_len(name, &this, base, len);
1689 return ERR_PTR(err);
1691 return __lookup_hash(&this, base, NULL);
1694 int user_path_at(int dfd, const char __user *name, unsigned flags,
1697 struct nameidata nd;
1698 char *tmp = getname(name);
1699 int err = PTR_ERR(tmp);
1702 BUG_ON(flags & LOOKUP_PARENT);
1704 err = do_path_lookup(dfd, tmp, flags, &nd);
1712 static int user_path_parent(int dfd, const char __user *path,
1713 struct nameidata *nd, char **name)
1715 char *s = getname(path);
1721 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1731 * It's inline, so penalty for filesystems that don't use sticky bit is
1734 static inline int check_sticky(struct inode *dir, struct inode *inode)
1736 uid_t fsuid = current_fsuid();
1738 if (!(dir->i_mode & S_ISVTX))
1740 if (inode->i_uid == fsuid)
1742 if (dir->i_uid == fsuid)
1744 return !capable(CAP_FOWNER);
1748 * Check whether we can remove a link victim from directory dir, check
1749 * whether the type of victim is right.
1750 * 1. We can't do it if dir is read-only (done in permission())
1751 * 2. We should have write and exec permissions on dir
1752 * 3. We can't remove anything from append-only dir
1753 * 4. We can't do anything with immutable dir (done in permission())
1754 * 5. If the sticky bit on dir is set we should either
1755 * a. be owner of dir, or
1756 * b. be owner of victim, or
1757 * c. have CAP_FOWNER capability
1758 * 6. If the victim is append-only or immutable we can't do antyhing with
1759 * links pointing to it.
1760 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1761 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1762 * 9. We can't remove a root or mountpoint.
1763 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1764 * nfs_async_unlink().
1766 static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1770 if (!victim->d_inode)
1773 BUG_ON(victim->d_parent->d_inode != dir);
1774 audit_inode_child(victim, dir);
1776 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1781 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1782 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1785 if (!S_ISDIR(victim->d_inode->i_mode))
1787 if (IS_ROOT(victim))
1789 } else if (S_ISDIR(victim->d_inode->i_mode))
1791 if (IS_DEADDIR(dir))
1793 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1798 /* Check whether we can create an object with dentry child in directory
1800 * 1. We can't do it if child already exists (open has special treatment for
1801 * this case, but since we are inlined it's OK)
1802 * 2. We can't do it if dir is read-only (done in permission())
1803 * 3. We should have write and exec permissions on dir
1804 * 4. We can't do it if dir is immutable (done in permission())
1806 static inline int may_create(struct inode *dir, struct dentry *child)
1810 if (IS_DEADDIR(dir))
1812 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1816 * p1 and p2 should be directories on the same fs.
1818 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1823 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1827 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1829 p = d_ancestor(p2, p1);
1831 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1832 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1836 p = d_ancestor(p1, p2);
1838 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1839 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1843 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1844 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1848 void unlock_rename(struct dentry *p1, struct dentry *p2)
1850 mutex_unlock(&p1->d_inode->i_mutex);
1852 mutex_unlock(&p2->d_inode->i_mutex);
1853 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1857 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1858 struct nameidata *nd)
1860 int error = may_create(dir, dentry);
1865 if (!dir->i_op->create)
1866 return -EACCES; /* shouldn't it be ENOSYS? */
1869 error = security_inode_create(dir, dentry, mode);
1872 error = dir->i_op->create(dir, dentry, mode, nd);
1874 fsnotify_create(dir, dentry);
1878 int may_open(struct path *path, int acc_mode, int flag)
1880 struct dentry *dentry = path->dentry;
1881 struct inode *inode = dentry->d_inode;
1887 switch (inode->i_mode & S_IFMT) {
1891 if (acc_mode & MAY_WRITE)
1896 if (path->mnt->mnt_flags & MNT_NODEV)
1905 error = inode_permission(inode, acc_mode);
1910 * An append-only file must be opened in append mode for writing.
1912 if (IS_APPEND(inode)) {
1913 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
1919 /* O_NOATIME can only be set by the owner or superuser */
1920 if (flag & O_NOATIME && !is_owner_or_cap(inode))
1924 * Ensure there are no outstanding leases on the file.
1926 return break_lease(inode, flag);
1929 static int handle_truncate(struct path *path)
1931 struct inode *inode = path->dentry->d_inode;
1932 int error = get_write_access(inode);
1936 * Refuse to truncate files with mandatory locks held on them.
1938 error = locks_verify_locked(inode);
1940 error = security_path_truncate(path);
1942 error = do_truncate(path->dentry, 0,
1943 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
1946 put_write_access(inode);
1951 * Be careful about ever adding any more callers of this
1952 * function. Its flags must be in the namei format, not
1953 * what get passed to sys_open().
1955 static int __open_namei_create(struct nameidata *nd, struct path *path,
1956 int open_flag, int mode)
1959 struct dentry *dir = nd->path.dentry;
1961 if (!IS_POSIXACL(dir->d_inode))
1962 mode &= ~current_umask();
1963 error = security_path_mknod(&nd->path, path->dentry, mode, 0);
1966 error = vfs_create(dir->d_inode, path->dentry, mode, nd);
1968 mutex_unlock(&dir->d_inode->i_mutex);
1969 dput(nd->path.dentry);
1970 nd->path.dentry = path->dentry;
1974 /* Don't check for write permission, don't truncate */
1975 return may_open(&nd->path, 0, open_flag & ~O_TRUNC);
1979 * Note that while the flag value (low two bits) for sys_open means:
1984 * it is changed into
1985 * 00 - no permissions needed
1986 * 01 - read-permission
1987 * 10 - write-permission
1989 * for the internal routines (ie open_namei()/follow_link() etc)
1990 * This is more logical, and also allows the 00 "no perm needed"
1991 * to be used for symlinks (where the permissions are checked
1995 static inline int open_to_namei_flags(int flag)
1997 if ((flag+1) & O_ACCMODE)
2002 static int open_will_truncate(int flag, struct inode *inode)
2005 * We'll never write to the fs underlying
2008 if (special_file(inode->i_mode))
2010 return (flag & O_TRUNC);
2013 static struct file *finish_open(struct nameidata *nd,
2014 int open_flag, int acc_mode)
2020 will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode);
2021 if (will_truncate) {
2022 error = mnt_want_write(nd->path.mnt);
2026 error = may_open(&nd->path, acc_mode, open_flag);
2029 mnt_drop_write(nd->path.mnt);
2032 filp = nameidata_to_filp(nd);
2033 if (!IS_ERR(filp)) {
2034 error = ima_file_check(filp, acc_mode);
2037 filp = ERR_PTR(error);
2040 if (!IS_ERR(filp)) {
2041 if (will_truncate) {
2042 error = handle_truncate(&nd->path);
2045 filp = ERR_PTR(error);
2050 * It is now safe to drop the mnt write
2051 * because the filp has had a write taken
2055 mnt_drop_write(nd->path.mnt);
2056 path_put(&nd->path);
2060 if (!IS_ERR(nd->intent.open.file))
2061 release_open_intent(nd);
2062 path_put(&nd->path);
2063 return ERR_PTR(error);
2067 * Handle O_CREAT case for do_filp_open
2069 static struct file *do_last(struct nameidata *nd, struct path *path,
2070 int open_flag, int acc_mode,
2071 int mode, const char *pathname)
2073 struct dentry *dir = nd->path.dentry;
2075 int error = -EISDIR;
2077 switch (nd->last_type) {
2080 dir = nd->path.dentry;
2082 if (need_reval_dot(dir)) {
2083 if (!dir->d_op->d_revalidate(dir, nd)) {
2092 audit_inode(pathname, dir);
2096 /* trailing slashes? */
2097 if (nd->last.name[nd->last.len])
2100 mutex_lock(&dir->d_inode->i_mutex);
2102 path->dentry = lookup_hash(nd);
2103 path->mnt = nd->path.mnt;
2105 error = PTR_ERR(path->dentry);
2106 if (IS_ERR(path->dentry)) {
2107 mutex_unlock(&dir->d_inode->i_mutex);
2111 if (IS_ERR(nd->intent.open.file)) {
2112 error = PTR_ERR(nd->intent.open.file);
2113 goto exit_mutex_unlock;
2116 /* Negative dentry, just create the file */
2117 if (!path->dentry->d_inode) {
2119 * This write is needed to ensure that a
2120 * ro->rw transition does not occur between
2121 * the time when the file is created and when
2122 * a permanent write count is taken through
2123 * the 'struct file' in nameidata_to_filp().
2125 error = mnt_want_write(nd->path.mnt);
2127 goto exit_mutex_unlock;
2128 error = __open_namei_create(nd, path, open_flag, mode);
2130 mnt_drop_write(nd->path.mnt);
2133 filp = nameidata_to_filp(nd);
2134 mnt_drop_write(nd->path.mnt);
2135 path_put(&nd->path);
2136 if (!IS_ERR(filp)) {
2137 error = ima_file_check(filp, acc_mode);
2140 filp = ERR_PTR(error);
2147 * It already exists.
2149 mutex_unlock(&dir->d_inode->i_mutex);
2150 audit_inode(pathname, path->dentry);
2153 if (open_flag & O_EXCL)
2156 if (__follow_mount(path)) {
2158 if (open_flag & O_NOFOLLOW)
2163 if (!path->dentry->d_inode)
2166 if (path->dentry->d_inode->i_op->follow_link)
2169 path_to_nameidata(path, nd);
2170 nd->inode = path->dentry->d_inode;
2172 if (S_ISDIR(nd->inode->i_mode))
2175 filp = finish_open(nd, open_flag, acc_mode);
2179 mutex_unlock(&dir->d_inode->i_mutex);
2181 path_put_conditional(path, nd);
2183 if (!IS_ERR(nd->intent.open.file))
2184 release_open_intent(nd);
2185 path_put(&nd->path);
2186 return ERR_PTR(error);
2190 * Note that the low bits of the passed in "open_flag"
2191 * are not the same as in the local variable "flag". See
2192 * open_to_namei_flags() for more details.
2194 struct file *do_filp_open(int dfd, const char *pathname,
2195 int open_flag, int mode, int acc_mode)
2198 struct nameidata nd;
2202 int flag = open_to_namei_flags(open_flag);
2205 if (!(open_flag & O_CREAT))
2208 /* Must never be set by userspace */
2209 open_flag &= ~FMODE_NONOTIFY;
2212 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
2213 * check for O_DSYNC if the need any syncing at all we enforce it's
2214 * always set instead of having to deal with possibly weird behaviour
2215 * for malicious applications setting only __O_SYNC.
2217 if (open_flag & __O_SYNC)
2218 open_flag |= O_DSYNC;
2221 acc_mode = MAY_OPEN | ACC_MODE(open_flag);
2223 /* O_TRUNC implies we need access checks for write permissions */
2224 if (open_flag & O_TRUNC)
2225 acc_mode |= MAY_WRITE;
2227 /* Allow the LSM permission hook to distinguish append
2228 access from general write access. */
2229 if (open_flag & O_APPEND)
2230 acc_mode |= MAY_APPEND;
2232 flags = LOOKUP_OPEN;
2233 if (open_flag & O_CREAT) {
2234 flags |= LOOKUP_CREATE;
2235 if (open_flag & O_EXCL)
2236 flags |= LOOKUP_EXCL;
2238 if (open_flag & O_DIRECTORY)
2239 flags |= LOOKUP_DIRECTORY;
2240 if (!(open_flag & O_NOFOLLOW))
2241 flags |= LOOKUP_FOLLOW;
2243 filp = get_empty_filp();
2245 return ERR_PTR(-ENFILE);
2247 filp->f_flags = open_flag;
2248 nd.intent.open.file = filp;
2249 nd.intent.open.flags = flag;
2250 nd.intent.open.create_mode = mode;
2252 if (open_flag & O_CREAT)
2255 /* !O_CREAT, simple open */
2256 error = do_path_lookup(dfd, pathname, flags, &nd);
2257 if (unlikely(error))
2260 if (!(nd.flags & LOOKUP_FOLLOW)) {
2261 if (nd.inode->i_op->follow_link)
2265 if (nd.flags & LOOKUP_DIRECTORY) {
2266 if (!nd.inode->i_op->lookup)
2269 audit_inode(pathname, nd.path.dentry);
2270 filp = finish_open(&nd, open_flag, acc_mode);
2274 /* OK, have to create the file. Find the parent. */
2275 error = path_init_rcu(dfd, pathname,
2276 LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd);
2279 error = path_walk_rcu(pathname, &nd);
2280 path_finish_rcu(&nd);
2281 if (unlikely(error == -ECHILD || error == -ESTALE)) {
2282 /* slower, locked walk */
2283 if (error == -ESTALE) {
2285 flags |= LOOKUP_REVAL;
2287 error = path_init(dfd, pathname,
2288 LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd);
2292 error = path_walk_simple(pathname, &nd);
2294 if (unlikely(error))
2296 if (unlikely(!audit_dummy_context()))
2297 audit_inode(pathname, nd.path.dentry);
2300 * We have the parent and last component.
2303 filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
2304 while (unlikely(!filp)) { /* trailing symlink */
2308 /* S_ISDIR part is a temporary automount kludge */
2309 if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(nd.inode->i_mode))
2314 * This is subtle. Instead of calling do_follow_link() we do
2315 * the thing by hands. The reason is that this way we have zero
2316 * link_count and path_walk() (called from ->follow_link)
2317 * honoring LOOKUP_PARENT. After that we have the parent and
2318 * last component, i.e. we are in the same situation as after
2319 * the first path_walk(). Well, almost - if the last component
2320 * is normal we get its copy stored in nd->last.name and we will
2321 * have to putname() it when we are done. Procfs-like symlinks
2322 * just set LAST_BIND.
2324 nd.flags |= LOOKUP_PARENT;
2325 error = security_inode_follow_link(path.dentry, &nd);
2328 error = __do_follow_link(&path, &nd, &cookie);
2329 if (unlikely(error)) {
2330 if (!IS_ERR(cookie) && nd.inode->i_op->put_link)
2331 nd.inode->i_op->put_link(path.dentry, &nd, cookie);
2332 /* nd.path had been dropped */
2337 nd.flags &= ~LOOKUP_PARENT;
2338 filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
2339 if (nd.inode->i_op->put_link)
2340 nd.inode->i_op->put_link(holder.dentry, &nd, cookie);
2346 if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL))
2351 path_put_conditional(&path, &nd);
2355 if (!IS_ERR(nd.intent.open.file))
2356 release_open_intent(&nd);
2357 filp = ERR_PTR(error);
2362 * filp_open - open file and return file pointer
2364 * @filename: path to open
2365 * @flags: open flags as per the open(2) second argument
2366 * @mode: mode for the new file if O_CREAT is set, else ignored
2368 * This is the helper to open a file from kernelspace if you really
2369 * have to. But in generally you should not do this, so please move
2370 * along, nothing to see here..
2372 struct file *filp_open(const char *filename, int flags, int mode)
2374 return do_filp_open(AT_FDCWD, filename, flags, mode, 0);
2376 EXPORT_SYMBOL(filp_open);
2379 * lookup_create - lookup a dentry, creating it if it doesn't exist
2380 * @nd: nameidata info
2381 * @is_dir: directory flag
2383 * Simple function to lookup and return a dentry and create it
2384 * if it doesn't exist. Is SMP-safe.
2386 * Returns with nd->path.dentry->d_inode->i_mutex locked.
2388 struct dentry *lookup_create(struct nameidata *nd, int is_dir)
2390 struct dentry *dentry = ERR_PTR(-EEXIST);
2392 mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2394 * Yucky last component or no last component at all?
2395 * (foo/., foo/.., /////)
2397 if (nd->last_type != LAST_NORM)
2399 nd->flags &= ~LOOKUP_PARENT;
2400 nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
2401 nd->intent.open.flags = O_EXCL;
2404 * Do the final lookup.
2406 dentry = lookup_hash(nd);
2410 if (dentry->d_inode)
2413 * Special case - lookup gave negative, but... we had foo/bar/
2414 * From the vfs_mknod() POV we just have a negative dentry -
2415 * all is fine. Let's be bastards - you had / on the end, you've
2416 * been asking for (non-existent) directory. -ENOENT for you.
2418 if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
2420 dentry = ERR_PTR(-ENOENT);
2425 dentry = ERR_PTR(-EEXIST);
2429 EXPORT_SYMBOL_GPL(lookup_create);
2431 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
2433 int error = may_create(dir, dentry);
2438 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
2441 if (!dir->i_op->mknod)
2444 error = devcgroup_inode_mknod(mode, dev);
2448 error = security_inode_mknod(dir, dentry, mode, dev);
2452 error = dir->i_op->mknod(dir, dentry, mode, dev);
2454 fsnotify_create(dir, dentry);
2458 static int may_mknod(mode_t mode)
2460 switch (mode & S_IFMT) {
2466 case 0: /* zero mode translates to S_IFREG */
2475 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
2480 struct dentry *dentry;
2481 struct nameidata nd;
2486 error = user_path_parent(dfd, filename, &nd, &tmp);
2490 dentry = lookup_create(&nd, 0);
2491 if (IS_ERR(dentry)) {
2492 error = PTR_ERR(dentry);
2495 if (!IS_POSIXACL(nd.path.dentry->d_inode))
2496 mode &= ~current_umask();
2497 error = may_mknod(mode);
2500 error = mnt_want_write(nd.path.mnt);
2503 error = security_path_mknod(&nd.path, dentry, mode, dev);
2505 goto out_drop_write;
2506 switch (mode & S_IFMT) {
2507 case 0: case S_IFREG:
2508 error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
2510 case S_IFCHR: case S_IFBLK:
2511 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
2512 new_decode_dev(dev));
2514 case S_IFIFO: case S_IFSOCK:
2515 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
2519 mnt_drop_write(nd.path.mnt);
2523 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2530 SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
2532 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2535 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2537 int error = may_create(dir, dentry);
2542 if (!dir->i_op->mkdir)
2545 mode &= (S_IRWXUGO|S_ISVTX);
2546 error = security_inode_mkdir(dir, dentry, mode);
2550 error = dir->i_op->mkdir(dir, dentry, mode);
2552 fsnotify_mkdir(dir, dentry);
2556 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
2560 struct dentry *dentry;
2561 struct nameidata nd;
2563 error = user_path_parent(dfd, pathname, &nd, &tmp);
2567 dentry = lookup_create(&nd, 1);
2568 error = PTR_ERR(dentry);
2572 if (!IS_POSIXACL(nd.path.dentry->d_inode))
2573 mode &= ~current_umask();
2574 error = mnt_want_write(nd.path.mnt);
2577 error = security_path_mkdir(&nd.path, dentry, mode);
2579 goto out_drop_write;
2580 error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
2582 mnt_drop_write(nd.path.mnt);
2586 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2593 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
2595 return sys_mkdirat(AT_FDCWD, pathname, mode);
2599 * We try to drop the dentry early: we should have
2600 * a usage count of 2 if we're the only user of this
2601 * dentry, and if that is true (possibly after pruning
2602 * the dcache), then we drop the dentry now.
2604 * A low-level filesystem can, if it choses, legally
2607 * if (!d_unhashed(dentry))
2610 * if it cannot handle the case of removing a directory
2611 * that is still in use by something else..
2613 void dentry_unhash(struct dentry *dentry)
2616 shrink_dcache_parent(dentry);
2617 spin_lock(&dentry->d_lock);
2618 if (dentry->d_count == 2)
2620 spin_unlock(&dentry->d_lock);
2623 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2625 int error = may_delete(dir, dentry, 1);
2630 if (!dir->i_op->rmdir)
2633 mutex_lock(&dentry->d_inode->i_mutex);
2634 dentry_unhash(dentry);
2635 if (d_mountpoint(dentry))
2638 error = security_inode_rmdir(dir, dentry);
2640 error = dir->i_op->rmdir(dir, dentry);
2642 dentry->d_inode->i_flags |= S_DEAD;
2647 mutex_unlock(&dentry->d_inode->i_mutex);
2656 static long do_rmdir(int dfd, const char __user *pathname)
2660 struct dentry *dentry;
2661 struct nameidata nd;
2663 error = user_path_parent(dfd, pathname, &nd, &name);
2667 switch(nd.last_type) {
2679 nd.flags &= ~LOOKUP_PARENT;
2681 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2682 dentry = lookup_hash(&nd);
2683 error = PTR_ERR(dentry);
2686 error = mnt_want_write(nd.path.mnt);
2689 error = security_path_rmdir(&nd.path, dentry);
2692 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
2694 mnt_drop_write(nd.path.mnt);
2698 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2705 SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
2707 return do_rmdir(AT_FDCWD, pathname);
2710 int vfs_unlink(struct inode *dir, struct dentry *dentry)
2712 int error = may_delete(dir, dentry, 0);
2717 if (!dir->i_op->unlink)
2720 mutex_lock(&dentry->d_inode->i_mutex);
2721 if (d_mountpoint(dentry))
2724 error = security_inode_unlink(dir, dentry);
2726 error = dir->i_op->unlink(dir, dentry);
2731 mutex_unlock(&dentry->d_inode->i_mutex);
2733 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2734 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2735 fsnotify_link_count(dentry->d_inode);
2743 * Make sure that the actual truncation of the file will occur outside its
2744 * directory's i_mutex. Truncate can take a long time if there is a lot of
2745 * writeout happening, and we don't want to prevent access to the directory
2746 * while waiting on the I/O.
2748 static long do_unlinkat(int dfd, const char __user *pathname)
2752 struct dentry *dentry;
2753 struct nameidata nd;
2754 struct inode *inode = NULL;
2756 error = user_path_parent(dfd, pathname, &nd, &name);
2761 if (nd.last_type != LAST_NORM)
2764 nd.flags &= ~LOOKUP_PARENT;
2766 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2767 dentry = lookup_hash(&nd);
2768 error = PTR_ERR(dentry);
2769 if (!IS_ERR(dentry)) {
2770 /* Why not before? Because we want correct error value */
2771 if (nd.last.name[nd.last.len])
2773 inode = dentry->d_inode;
2776 error = mnt_want_write(nd.path.mnt);
2779 error = security_path_unlink(&nd.path, dentry);
2782 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
2784 mnt_drop_write(nd.path.mnt);
2788 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2790 iput(inode); /* truncate the inode here */
2797 error = !dentry->d_inode ? -ENOENT :
2798 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2802 SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
2804 if ((flag & ~AT_REMOVEDIR) != 0)
2807 if (flag & AT_REMOVEDIR)
2808 return do_rmdir(dfd, pathname);
2810 return do_unlinkat(dfd, pathname);
2813 SYSCALL_DEFINE1(unlink, const char __user *, pathname)
2815 return do_unlinkat(AT_FDCWD, pathname);
2818 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
2820 int error = may_create(dir, dentry);
2825 if (!dir->i_op->symlink)
2828 error = security_inode_symlink(dir, dentry, oldname);
2832 error = dir->i_op->symlink(dir, dentry, oldname);
2834 fsnotify_create(dir, dentry);
2838 SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2839 int, newdfd, const char __user *, newname)
2844 struct dentry *dentry;
2845 struct nameidata nd;
2847 from = getname(oldname);
2849 return PTR_ERR(from);
2851 error = user_path_parent(newdfd, newname, &nd, &to);
2855 dentry = lookup_create(&nd, 0);
2856 error = PTR_ERR(dentry);
2860 error = mnt_want_write(nd.path.mnt);
2863 error = security_path_symlink(&nd.path, dentry, from);
2865 goto out_drop_write;
2866 error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
2868 mnt_drop_write(nd.path.mnt);
2872 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2880 SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
2882 return sys_symlinkat(oldname, AT_FDCWD, newname);
2885 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2887 struct inode *inode = old_dentry->d_inode;
2893 error = may_create(dir, new_dentry);
2897 if (dir->i_sb != inode->i_sb)
2901 * A link to an append-only or immutable file cannot be created.
2903 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2905 if (!dir->i_op->link)
2907 if (S_ISDIR(inode->i_mode))
2910 error = security_inode_link(old_dentry, dir, new_dentry);
2914 mutex_lock(&inode->i_mutex);
2915 error = dir->i_op->link(old_dentry, dir, new_dentry);
2916 mutex_unlock(&inode->i_mutex);
2918 fsnotify_link(dir, inode, new_dentry);
2923 * Hardlinks are often used in delicate situations. We avoid
2924 * security-related surprises by not following symlinks on the
2927 * We don't follow them on the oldname either to be compatible
2928 * with linux 2.0, and to avoid hard-linking to directories
2929 * and other special files. --ADM
2931 SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2932 int, newdfd, const char __user *, newname, int, flags)
2934 struct dentry *new_dentry;
2935 struct nameidata nd;
2936 struct path old_path;
2940 if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
2943 error = user_path_at(olddfd, oldname,
2944 flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
2949 error = user_path_parent(newdfd, newname, &nd, &to);
2953 if (old_path.mnt != nd.path.mnt)
2955 new_dentry = lookup_create(&nd, 0);
2956 error = PTR_ERR(new_dentry);
2957 if (IS_ERR(new_dentry))
2959 error = mnt_want_write(nd.path.mnt);
2962 error = security_path_link(old_path.dentry, &nd.path, new_dentry);
2964 goto out_drop_write;
2965 error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
2967 mnt_drop_write(nd.path.mnt);
2971 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2976 path_put(&old_path);
2981 SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
2983 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2987 * The worst of all namespace operations - renaming directory. "Perverted"
2988 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2990 * a) we can get into loop creation. Check is done in is_subdir().
2991 * b) race potential - two innocent renames can create a loop together.
2992 * That's where 4.4 screws up. Current fix: serialization on
2993 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2995 * c) we have to lock _three_ objects - parents and victim (if it exists).
2996 * And that - after we got ->i_mutex on parents (until then we don't know
2997 * whether the target exists). Solution: try to be smart with locking
2998 * order for inodes. We rely on the fact that tree topology may change
2999 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
3000 * move will be locked. Thus we can rank directories by the tree
3001 * (ancestors first) and rank all non-directories after them.
3002 * That works since everybody except rename does "lock parent, lookup,
3003 * lock child" and rename is under ->s_vfs_rename_mutex.
3004 * HOWEVER, it relies on the assumption that any object with ->lookup()
3005 * has no more than 1 dentry. If "hybrid" objects will ever appear,
3006 * we'd better make sure that there's no link(2) for them.
3007 * d) some filesystems don't support opened-but-unlinked directories,
3008 * either because of layout or because they are not ready to deal with
3009 * all cases correctly. The latter will be fixed (taking this sort of
3010 * stuff into VFS), but the former is not going away. Solution: the same
3011 * trick as in rmdir().
3012 * e) conversion from fhandle to dentry may come in the wrong moment - when
3013 * we are removing the target. Solution: we will have to grab ->i_mutex
3014 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
3015 * ->i_mutex on parents, which works but leads to some truly excessive
3018 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
3019 struct inode *new_dir, struct dentry *new_dentry)
3022 struct inode *target;
3025 * If we are going to change the parent - check write permissions,
3026 * we'll need to flip '..'.
3028 if (new_dir != old_dir) {
3029 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
3034 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3038 target = new_dentry->d_inode;
3040 mutex_lock(&target->i_mutex);
3041 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
3045 dentry_unhash(new_dentry);
3046 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3050 target->i_flags |= S_DEAD;
3051 dont_mount(new_dentry);
3053 mutex_unlock(&target->i_mutex);
3054 if (d_unhashed(new_dentry))
3055 d_rehash(new_dentry);
3059 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3060 d_move(old_dentry,new_dentry);
3064 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
3065 struct inode *new_dir, struct dentry *new_dentry)
3067 struct inode *target;
3070 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3075 target = new_dentry->d_inode;
3077 mutex_lock(&target->i_mutex);
3078 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
3081 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3084 dont_mount(new_dentry);
3085 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3086 d_move(old_dentry, new_dentry);
3089 mutex_unlock(&target->i_mutex);
3094 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
3095 struct inode *new_dir, struct dentry *new_dentry)
3098 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
3099 const unsigned char *old_name;
3101 if (old_dentry->d_inode == new_dentry->d_inode)
3104 error = may_delete(old_dir, old_dentry, is_dir);
3108 if (!new_dentry->d_inode)
3109 error = may_create(new_dir, new_dentry);
3111 error = may_delete(new_dir, new_dentry, is_dir);
3115 if (!old_dir->i_op->rename)
3118 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
3121 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
3123 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
3125 fsnotify_move(old_dir, new_dir, old_name, is_dir,
3126 new_dentry->d_inode, old_dentry);
3127 fsnotify_oldname_free(old_name);
3132 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
3133 int, newdfd, const char __user *, newname)
3135 struct dentry *old_dir, *new_dir;
3136 struct dentry *old_dentry, *new_dentry;
3137 struct dentry *trap;
3138 struct nameidata oldnd, newnd;
3143 error = user_path_parent(olddfd, oldname, &oldnd, &from);
3147 error = user_path_parent(newdfd, newname, &newnd, &to);
3152 if (oldnd.path.mnt != newnd.path.mnt)
3155 old_dir = oldnd.path.dentry;
3157 if (oldnd.last_type != LAST_NORM)
3160 new_dir = newnd.path.dentry;
3161 if (newnd.last_type != LAST_NORM)
3164 oldnd.flags &= ~LOOKUP_PARENT;
3165 newnd.flags &= ~LOOKUP_PARENT;
3166 newnd.flags |= LOOKUP_RENAME_TARGET;
3168 trap = lock_rename(new_dir, old_dir);
3170 old_dentry = lookup_hash(&oldnd);
3171 error = PTR_ERR(old_dentry);
3172 if (IS_ERR(old_dentry))
3174 /* source must exist */
3176 if (!old_dentry->d_inode)
3178 /* unless the source is a directory trailing slashes give -ENOTDIR */
3179 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
3181 if (oldnd.last.name[oldnd.last.len])
3183 if (newnd.last.name[newnd.last.len])
3186 /* source should not be ancestor of target */
3188 if (old_dentry == trap)
3190 new_dentry = lookup_hash(&newnd);
3191 error = PTR_ERR(new_dentry);
3192 if (IS_ERR(new_dentry))
3194 /* target should not be an ancestor of source */
3196 if (new_dentry == trap)
3199 error = mnt_want_write(oldnd.path.mnt);
3202 error = security_path_rename(&oldnd.path, old_dentry,
3203 &newnd.path, new_dentry);
3206 error = vfs_rename(old_dir->d_inode, old_dentry,
3207 new_dir->d_inode, new_dentry);
3209 mnt_drop_write(oldnd.path.mnt);
3215 unlock_rename(new_dir, old_dir);
3217 path_put(&newnd.path);
3220 path_put(&oldnd.path);
3226 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
3228 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
3231 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
3235 len = PTR_ERR(link);
3240 if (len > (unsigned) buflen)
3242 if (copy_to_user(buffer, link, len))
3249 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3250 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3251 * using) it for any given inode is up to filesystem.
3253 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3255 struct nameidata nd;
3260 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
3262 return PTR_ERR(cookie);
3264 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
3265 if (dentry->d_inode->i_op->put_link)
3266 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
3270 int vfs_follow_link(struct nameidata *nd, const char *link)
3272 return __vfs_follow_link(nd, link);
3275 /* get the link contents into pagecache */
3276 static char *page_getlink(struct dentry * dentry, struct page **ppage)
3280 struct address_space *mapping = dentry->d_inode->i_mapping;
3281 page = read_mapping_page(mapping, 0, NULL);
3286 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
3290 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3292 struct page *page = NULL;
3293 char *s = page_getlink(dentry, &page);
3294 int res = vfs_readlink(dentry,buffer,buflen,s);
3297 page_cache_release(page);
3302 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
3304 struct page *page = NULL;
3305 nd_set_link(nd, page_getlink(dentry, &page));
3309 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
3311 struct page *page = cookie;
3315 page_cache_release(page);
3320 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3322 int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
3324 struct address_space *mapping = inode->i_mapping;
3329 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
3331 flags |= AOP_FLAG_NOFS;
3334 err = pagecache_write_begin(NULL, mapping, 0, len-1,
3335 flags, &page, &fsdata);
3339 kaddr = kmap_atomic(page, KM_USER0);
3340 memcpy(kaddr, symname, len-1);
3341 kunmap_atomic(kaddr, KM_USER0);
3343 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
3350 mark_inode_dirty(inode);
3356 int page_symlink(struct inode *inode, const char *symname, int len)
3358 return __page_symlink(inode, symname, len,
3359 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
3362 const struct inode_operations page_symlink_inode_operations = {
3363 .readlink = generic_readlink,
3364 .follow_link = page_follow_link_light,
3365 .put_link = page_put_link,
3368 EXPORT_SYMBOL(user_path_at);
3369 EXPORT_SYMBOL(follow_down);
3370 EXPORT_SYMBOL(follow_up);
3371 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
3372 EXPORT_SYMBOL(getname);
3373 EXPORT_SYMBOL(lock_rename);
3374 EXPORT_SYMBOL(lookup_one_len);
3375 EXPORT_SYMBOL(page_follow_link_light);
3376 EXPORT_SYMBOL(page_put_link);
3377 EXPORT_SYMBOL(page_readlink);
3378 EXPORT_SYMBOL(__page_symlink);
3379 EXPORT_SYMBOL(page_symlink);
3380 EXPORT_SYMBOL(page_symlink_inode_operations);
3381 EXPORT_SYMBOL(path_lookup);
3382 EXPORT_SYMBOL(kern_path);
3383 EXPORT_SYMBOL(vfs_path_lookup);
3384 EXPORT_SYMBOL(inode_permission);
3385 EXPORT_SYMBOL(file_permission);
3386 EXPORT_SYMBOL(unlock_rename);
3387 EXPORT_SYMBOL(vfs_create);
3388 EXPORT_SYMBOL(vfs_follow_link);
3389 EXPORT_SYMBOL(vfs_link);
3390 EXPORT_SYMBOL(vfs_mkdir);
3391 EXPORT_SYMBOL(vfs_mknod);
3392 EXPORT_SYMBOL(generic_permission);
3393 EXPORT_SYMBOL(vfs_readlink);
3394 EXPORT_SYMBOL(vfs_rename);
3395 EXPORT_SYMBOL(vfs_rmdir);
3396 EXPORT_SYMBOL(vfs_symlink);
3397 EXPORT_SYMBOL(vfs_unlink);
3398 EXPORT_SYMBOL(dentry_unhash);
3399 EXPORT_SYMBOL(generic_readlink);