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/quotaops.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/smp_lock.h>
26 #include <linux/personality.h>
27 #include <linux/security.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/file.h>
32 #include <asm/namei.h>
33 #include <asm/uaccess.h>
35 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
37 /* [Feb-1997 T. Schoebel-Theuer]
38 * Fundamental changes in the pathname lookup mechanisms (namei)
39 * were necessary because of omirr. The reason is that omirr needs
40 * to know the _real_ pathname, not the user-supplied one, in case
41 * of symlinks (and also when transname replacements occur).
43 * The new code replaces the old recursive symlink resolution with
44 * an iterative one (in case of non-nested symlink chains). It does
45 * this with calls to <fs>_follow_link().
46 * As a side effect, dir_namei(), _namei() and follow_link() are now
47 * replaced with a single function lookup_dentry() that can handle all
48 * the special cases of the former code.
50 * With the new dcache, the pathname is stored at each inode, at least as
51 * long as the refcount of the inode is positive. As a side effect, the
52 * size of the dcache depends on the inode cache and thus is dynamic.
54 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
55 * resolution to correspond with current state of the code.
57 * Note that the symlink resolution is not *completely* iterative.
58 * There is still a significant amount of tail- and mid- recursion in
59 * the algorithm. Also, note that <fs>_readlink() is not used in
60 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
61 * may return different results than <fs>_follow_link(). Many virtual
62 * filesystems (including /proc) exhibit this behavior.
65 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
66 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
67 * and the name already exists in form of a symlink, try to create the new
68 * name indicated by the symlink. The old code always complained that the
69 * name already exists, due to not following the symlink even if its target
70 * is nonexistent. The new semantics affects also mknod() and link() when
71 * the name is a symlink pointing to a non-existant name.
73 * I don't know which semantics is the right one, since I have no access
74 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
75 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
76 * "old" one. Personally, I think the new semantics is much more logical.
77 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
78 * file does succeed in both HP-UX and SunOs, but not in Solaris
79 * and in the old Linux semantics.
82 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
83 * semantics. See the comments in "open_namei" and "do_link" below.
85 * [10-Sep-98 Alan Modra] Another symlink change.
88 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
89 * inside the path - always follow.
90 * in the last component in creation/removal/renaming - never follow.
91 * if LOOKUP_FOLLOW passed - follow.
92 * if the pathname has trailing slashes - follow.
93 * otherwise - don't follow.
94 * (applied in that order).
96 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
97 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
98 * During the 2.4 we need to fix the userland stuff depending on it -
99 * hopefully we will be able to get rid of that wart in 2.5. So far only
100 * XEmacs seems to be relying on it...
103 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
104 * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives
105 * any extra contention...
108 /* In order to reduce some races, while at the same time doing additional
109 * checking and hopefully speeding things up, we copy filenames to the
110 * kernel data space before using them..
112 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
113 * PATH_MAX includes the nul terminator --RR.
115 static inline int do_getname(const char __user *filename, char *page)
118 unsigned long len = PATH_MAX;
120 if (!segment_eq(get_fs(), KERNEL_DS)) {
121 if ((unsigned long) filename >= TASK_SIZE)
123 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
124 len = TASK_SIZE - (unsigned long) filename;
127 retval = strncpy_from_user(page, filename, len);
131 return -ENAMETOOLONG;
137 char * getname(const char __user * filename)
141 result = ERR_PTR(-ENOMEM);
144 int retval = do_getname(filename, tmp);
149 result = ERR_PTR(retval);
152 audit_getname(result);
156 #ifdef CONFIG_AUDITSYSCALL
157 void putname(const char *name)
159 if (unlikely(current->audit_context))
164 EXPORT_SYMBOL(putname);
169 * generic_permission - check for access rights on a Posix-like filesystem
170 * @inode: inode to check access rights for
171 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
172 * @check_acl: optional callback to check for Posix ACLs
174 * Used to check for read/write/execute permissions on a file.
175 * We use "fsuid" for this, letting us set arbitrary permissions
176 * for filesystem access without changing the "normal" uids which
177 * are used for other things..
179 int generic_permission(struct inode *inode, int mask,
180 int (*check_acl)(struct inode *inode, int mask))
182 umode_t mode = inode->i_mode;
184 if (current->fsuid == inode->i_uid)
187 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
188 int error = check_acl(inode, mask);
189 if (error == -EACCES)
190 goto check_capabilities;
191 else if (error != -EAGAIN)
195 if (in_group_p(inode->i_gid))
200 * If the DACs are ok we don't need any capability check.
202 if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask))
207 * Read/write DACs are always overridable.
208 * Executable DACs are overridable if at least one exec bit is set.
210 if (!(mask & MAY_EXEC) ||
211 (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
212 if (capable(CAP_DAC_OVERRIDE))
216 * Searching includes executable on directories, else just read.
218 if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
219 if (capable(CAP_DAC_READ_SEARCH))
225 int permission(struct inode *inode, int mask, struct nameidata *nd)
229 if (mask & MAY_WRITE) {
230 umode_t mode = inode->i_mode;
233 * Nobody gets write access to a read-only fs.
235 if (IS_RDONLY(inode) &&
236 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
240 * Nobody gets write access to an immutable file.
242 if (IS_IMMUTABLE(inode))
247 /* Ordinary permission routines do not understand MAY_APPEND. */
248 submask = mask & ~MAY_APPEND;
249 if (inode->i_op && inode->i_op->permission)
250 retval = inode->i_op->permission(inode, submask, nd);
252 retval = generic_permission(inode, submask, NULL);
256 return security_inode_permission(inode, mask, nd);
260 * vfs_permission - check for access rights to a given path
261 * @nd: lookup result that describes the path
262 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
264 * Used to check for read/write/execute permissions on a path.
265 * We use "fsuid" for this, letting us set arbitrary permissions
266 * for filesystem access without changing the "normal" uids which
267 * are used for other things.
269 int vfs_permission(struct nameidata *nd, int mask)
271 return permission(nd->dentry->d_inode, mask, nd);
275 * get_write_access() gets write permission for a file.
276 * put_write_access() releases this write permission.
277 * This is used for regular files.
278 * We cannot support write (and maybe mmap read-write shared) accesses and
279 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
280 * can have the following values:
281 * 0: no writers, no VM_DENYWRITE mappings
282 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
283 * > 0: (i_writecount) users are writing to the file.
285 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
286 * except for the cases where we don't hold i_writecount yet. Then we need to
287 * use {get,deny}_write_access() - these functions check the sign and refuse
288 * to do the change if sign is wrong. Exclusion between them is provided by
289 * the inode->i_lock spinlock.
292 int get_write_access(struct inode * inode)
294 spin_lock(&inode->i_lock);
295 if (atomic_read(&inode->i_writecount) < 0) {
296 spin_unlock(&inode->i_lock);
299 atomic_inc(&inode->i_writecount);
300 spin_unlock(&inode->i_lock);
305 int deny_write_access(struct file * file)
307 struct inode *inode = file->f_dentry->d_inode;
309 spin_lock(&inode->i_lock);
310 if (atomic_read(&inode->i_writecount) > 0) {
311 spin_unlock(&inode->i_lock);
314 atomic_dec(&inode->i_writecount);
315 spin_unlock(&inode->i_lock);
320 void path_release(struct nameidata *nd)
327 * umount() mustn't call path_release()/mntput() as that would clear
330 void path_release_on_umount(struct nameidata *nd)
333 mntput_no_expire(nd->mnt);
337 * release_open_intent - free up open intent resources
338 * @nd: pointer to nameidata
340 void release_open_intent(struct nameidata *nd)
342 if (nd->intent.open.file->f_dentry == NULL)
343 put_filp(nd->intent.open.file);
345 fput(nd->intent.open.file);
349 * Internal lookup() using the new generic dcache.
352 static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
354 struct dentry * dentry = __d_lookup(parent, name);
356 /* lockess __d_lookup may fail due to concurrent d_move()
357 * in some unrelated directory, so try with d_lookup
360 dentry = d_lookup(parent, name);
362 if (dentry && dentry->d_op && dentry->d_op->d_revalidate) {
363 if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) {
372 * Short-cut version of permission(), for calling by
373 * path_walk(), when dcache lock is held. Combines parts
374 * of permission() and generic_permission(), and tests ONLY for
375 * MAY_EXEC permission.
377 * If appropriate, check DAC only. If not appropriate, or
378 * short-cut DAC fails, then call permission() to do more
379 * complete permission check.
381 static inline int exec_permission_lite(struct inode *inode,
382 struct nameidata *nd)
384 umode_t mode = inode->i_mode;
386 if (inode->i_op && inode->i_op->permission)
389 if (current->fsuid == inode->i_uid)
391 else if (in_group_p(inode->i_gid))
397 if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
400 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
403 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
408 return security_inode_permission(inode, MAY_EXEC, nd);
412 * This is called when everything else fails, and we actually have
413 * to go to the low-level filesystem to find out what we should do..
415 * We get the directory semaphore, and after getting that we also
416 * make sure that nobody added the entry to the dcache in the meantime..
419 static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
421 struct dentry * result;
422 struct inode *dir = parent->d_inode;
426 * First re-do the cached lookup just in case it was created
427 * while we waited for the directory semaphore..
429 * FIXME! This could use version numbering or similar to
430 * avoid unnecessary cache lookups.
432 * The "dcache_lock" is purely to protect the RCU list walker
433 * from concurrent renames at this point (we mustn't get false
434 * negatives from the RCU list walk here, unlike the optimistic
437 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
439 result = d_lookup(parent, name);
441 struct dentry * dentry = d_alloc(parent, name);
442 result = ERR_PTR(-ENOMEM);
444 result = dir->i_op->lookup(dir, dentry, nd);
455 * Uhhuh! Nasty case: the cache was re-populated while
456 * we waited on the semaphore. Need to revalidate.
459 if (result->d_op && result->d_op->d_revalidate) {
460 if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) {
462 result = ERR_PTR(-ENOENT);
468 static int __emul_lookup_dentry(const char *, struct nameidata *);
472 walk_init_root(const char *name, struct nameidata *nd)
474 read_lock(¤t->fs->lock);
475 if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
476 nd->mnt = mntget(current->fs->altrootmnt);
477 nd->dentry = dget(current->fs->altroot);
478 read_unlock(¤t->fs->lock);
479 if (__emul_lookup_dentry(name,nd))
481 read_lock(¤t->fs->lock);
483 nd->mnt = mntget(current->fs->rootmnt);
484 nd->dentry = dget(current->fs->root);
485 read_unlock(¤t->fs->lock);
489 static inline int __vfs_follow_link(struct nameidata *nd, const char *link)
498 if (!walk_init_root(link, nd))
499 /* weird __emul_prefix() stuff did it */
502 res = link_path_walk(link, nd);
504 if (nd->depth || res || nd->last_type!=LAST_NORM)
507 * If it is an iterative symlinks resolution in open_namei() we
508 * have to copy the last component. And all that crap because of
509 * bloody create() on broken symlinks. Furrfu...
512 if (unlikely(!name)) {
516 strcpy(name, nd->last.name);
517 nd->last.name = name;
521 return PTR_ERR(link);
525 struct vfsmount *mnt;
526 struct dentry *dentry;
529 static inline int __do_follow_link(struct path *path, struct nameidata *nd)
533 struct dentry *dentry = path->dentry;
535 touch_atime(path->mnt, dentry);
536 nd_set_link(nd, NULL);
538 if (path->mnt == nd->mnt)
540 cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
541 error = PTR_ERR(cookie);
542 if (!IS_ERR(cookie)) {
543 char *s = nd_get_link(nd);
546 error = __vfs_follow_link(nd, s);
547 if (dentry->d_inode->i_op->put_link)
548 dentry->d_inode->i_op->put_link(dentry, nd, cookie);
556 static inline void dput_path(struct path *path, struct nameidata *nd)
559 if (path->mnt != nd->mnt)
563 static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
566 if (nd->mnt != path->mnt)
569 nd->dentry = path->dentry;
573 * This limits recursive symlink follows to 8, while
574 * limiting consecutive symlinks to 40.
576 * Without that kind of total limit, nasty chains of consecutive
577 * symlinks can cause almost arbitrarily long lookups.
579 static inline int do_follow_link(struct path *path, struct nameidata *nd)
582 if (current->link_count >= MAX_NESTED_LINKS)
584 if (current->total_link_count >= 40)
586 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
588 err = security_inode_follow_link(path->dentry, nd);
591 current->link_count++;
592 current->total_link_count++;
594 err = __do_follow_link(path, nd);
595 current->link_count--;
604 int follow_up(struct vfsmount **mnt, struct dentry **dentry)
606 struct vfsmount *parent;
607 struct dentry *mountpoint;
608 spin_lock(&vfsmount_lock);
609 parent=(*mnt)->mnt_parent;
610 if (parent == *mnt) {
611 spin_unlock(&vfsmount_lock);
615 mountpoint=dget((*mnt)->mnt_mountpoint);
616 spin_unlock(&vfsmount_lock);
618 *dentry = mountpoint;
624 /* no need for dcache_lock, as serialization is taken care in
627 static int __follow_mount(struct path *path)
630 while (d_mountpoint(path->dentry)) {
631 struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
638 path->dentry = dget(mounted->mnt_root);
644 static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
646 while (d_mountpoint(*dentry)) {
647 struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
653 *dentry = dget(mounted->mnt_root);
657 /* no need for dcache_lock, as serialization is taken care in
660 int follow_down(struct vfsmount **mnt, struct dentry **dentry)
662 struct vfsmount *mounted;
664 mounted = lookup_mnt(*mnt, *dentry);
669 *dentry = dget(mounted->mnt_root);
675 static inline void follow_dotdot(struct nameidata *nd)
678 struct vfsmount *parent;
679 struct dentry *old = nd->dentry;
681 read_lock(¤t->fs->lock);
682 if (nd->dentry == current->fs->root &&
683 nd->mnt == current->fs->rootmnt) {
684 read_unlock(¤t->fs->lock);
687 read_unlock(¤t->fs->lock);
688 spin_lock(&dcache_lock);
689 if (nd->dentry != nd->mnt->mnt_root) {
690 nd->dentry = dget(nd->dentry->d_parent);
691 spin_unlock(&dcache_lock);
695 spin_unlock(&dcache_lock);
696 spin_lock(&vfsmount_lock);
697 parent = nd->mnt->mnt_parent;
698 if (parent == nd->mnt) {
699 spin_unlock(&vfsmount_lock);
703 nd->dentry = dget(nd->mnt->mnt_mountpoint);
704 spin_unlock(&vfsmount_lock);
709 follow_mount(&nd->mnt, &nd->dentry);
713 * It's more convoluted than I'd like it to be, but... it's still fairly
714 * small and for now I'd prefer to have fast path as straight as possible.
715 * It _is_ time-critical.
717 static int do_lookup(struct nameidata *nd, struct qstr *name,
720 struct vfsmount *mnt = nd->mnt;
721 struct dentry *dentry = __d_lookup(nd->dentry, name);
725 if (dentry->d_op && dentry->d_op->d_revalidate)
726 goto need_revalidate;
729 path->dentry = dentry;
730 __follow_mount(path);
734 dentry = real_lookup(nd->dentry, name, nd);
740 if (dentry->d_op->d_revalidate(dentry, nd))
742 if (d_invalidate(dentry))
748 return PTR_ERR(dentry);
753 * This is the basic name resolution function, turning a pathname into
754 * the final dentry. We expect 'base' to be positive and a directory.
756 * Returns 0 and nd will have valid dentry and mnt on success.
757 * Returns error and drops reference to input namei data on failure.
759 static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
764 unsigned int lookup_flags = nd->flags;
771 inode = nd->dentry->d_inode;
773 lookup_flags = LOOKUP_FOLLOW;
775 /* At this point we know we have a real path component. */
781 nd->flags |= LOOKUP_CONTINUE;
782 err = exec_permission_lite(inode, nd);
784 err = vfs_permission(nd, MAY_EXEC);
789 c = *(const unsigned char *)name;
791 hash = init_name_hash();
794 hash = partial_name_hash(c, hash);
795 c = *(const unsigned char *)name;
796 } while (c && (c != '/'));
797 this.len = name - (const char *) this.name;
798 this.hash = end_name_hash(hash);
800 /* remove trailing slashes? */
803 while (*++name == '/');
805 goto last_with_slashes;
808 * "." and ".." are special - ".." especially so because it has
809 * to be able to know about the current root directory and
810 * parent relationships.
812 if (this.name[0] == '.') switch (this.len) {
816 if (this.name[1] != '.')
819 inode = nd->dentry->d_inode;
825 * See if the low-level filesystem might want
826 * to use its own hash..
828 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
829 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
833 /* This does the actual lookups.. */
834 err = do_lookup(nd, &this, &next);
839 inode = next.dentry->d_inode;
846 if (inode->i_op->follow_link) {
847 err = do_follow_link(&next, nd);
851 inode = nd->dentry->d_inode;
858 path_to_nameidata(&next, nd);
860 if (!inode->i_op->lookup)
863 /* here ends the main loop */
866 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
868 nd->flags &= ~LOOKUP_CONTINUE;
869 if (lookup_flags & LOOKUP_PARENT)
871 if (this.name[0] == '.') switch (this.len) {
875 if (this.name[1] != '.')
878 inode = nd->dentry->d_inode;
883 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
884 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
888 err = do_lookup(nd, &this, &next);
891 inode = next.dentry->d_inode;
892 if ((lookup_flags & LOOKUP_FOLLOW)
893 && inode && inode->i_op && inode->i_op->follow_link) {
894 err = do_follow_link(&next, nd);
897 inode = nd->dentry->d_inode;
899 path_to_nameidata(&next, nd);
903 if (lookup_flags & LOOKUP_DIRECTORY) {
905 if (!inode->i_op || !inode->i_op->lookup)
911 nd->last_type = LAST_NORM;
912 if (this.name[0] != '.')
915 nd->last_type = LAST_DOT;
916 else if (this.len == 2 && this.name[1] == '.')
917 nd->last_type = LAST_DOTDOT;
922 * We bypassed the ordinary revalidation routines.
923 * We may need to check the cached dentry for staleness.
925 if (nd->dentry && nd->dentry->d_sb &&
926 (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
928 /* Note: we do not d_invalidate() */
929 if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
935 dput_path(&next, nd);
944 * Wrapper to retry pathname resolution whenever the underlying
945 * file system returns an ESTALE.
947 * Retry the whole path once, forcing real lookup requests
948 * instead of relying on the dcache.
950 int fastcall link_path_walk(const char *name, struct nameidata *nd)
952 struct nameidata save = *nd;
955 /* make sure the stuff we saved doesn't go away */
959 result = __link_path_walk(name, nd);
960 if (result == -ESTALE) {
964 nd->flags |= LOOKUP_REVAL;
965 result = __link_path_walk(name, nd);
974 int fastcall path_walk(const char * name, struct nameidata *nd)
976 current->total_link_count = 0;
977 return link_path_walk(name, nd);
981 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
982 * everything is done. Returns 0 and drops input nd, if lookup failed;
984 static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
986 if (path_walk(name, nd))
987 return 0; /* something went wrong... */
989 if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
990 struct dentry *old_dentry = nd->dentry;
991 struct vfsmount *old_mnt = nd->mnt;
992 struct qstr last = nd->last;
993 int last_type = nd->last_type;
995 * NAME was not found in alternate root or it's a directory. Try to find
996 * it in the normal root:
998 nd->last_type = LAST_ROOT;
999 read_lock(¤t->fs->lock);
1000 nd->mnt = mntget(current->fs->rootmnt);
1001 nd->dentry = dget(current->fs->root);
1002 read_unlock(¤t->fs->lock);
1003 if (path_walk(name, nd) == 0) {
1004 if (nd->dentry->d_inode) {
1011 nd->dentry = old_dentry;
1014 nd->last_type = last_type;
1019 void set_fs_altroot(void)
1021 char *emul = __emul_prefix();
1022 struct nameidata nd;
1023 struct vfsmount *mnt = NULL, *oldmnt;
1024 struct dentry *dentry = NULL, *olddentry;
1029 err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
1035 write_lock(¤t->fs->lock);
1036 oldmnt = current->fs->altrootmnt;
1037 olddentry = current->fs->altroot;
1038 current->fs->altrootmnt = mnt;
1039 current->fs->altroot = dentry;
1040 write_unlock(¤t->fs->lock);
1047 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1048 int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd)
1052 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1056 read_lock(¤t->fs->lock);
1058 if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
1059 nd->mnt = mntget(current->fs->altrootmnt);
1060 nd->dentry = dget(current->fs->altroot);
1061 read_unlock(¤t->fs->lock);
1062 if (__emul_lookup_dentry(name,nd))
1063 goto out; /* found in altroot */
1064 read_lock(¤t->fs->lock);
1066 nd->mnt = mntget(current->fs->rootmnt);
1067 nd->dentry = dget(current->fs->root);
1069 nd->mnt = mntget(current->fs->pwdmnt);
1070 nd->dentry = dget(current->fs->pwd);
1072 read_unlock(¤t->fs->lock);
1073 current->total_link_count = 0;
1074 retval = link_path_walk(name, nd);
1076 if (unlikely(current->audit_context
1077 && nd && nd->dentry && nd->dentry->d_inode))
1078 audit_inode(name, nd->dentry->d_inode, flags);
1082 static int __path_lookup_intent_open(const char *name, unsigned int lookup_flags,
1083 struct nameidata *nd, int open_flags, int create_mode)
1085 struct file *filp = get_empty_filp();
1090 nd->intent.open.file = filp;
1091 nd->intent.open.flags = open_flags;
1092 nd->intent.open.create_mode = create_mode;
1093 err = path_lookup(name, lookup_flags|LOOKUP_OPEN, nd);
1094 if (IS_ERR(nd->intent.open.file)) {
1096 err = PTR_ERR(nd->intent.open.file);
1099 } else if (err != 0)
1100 release_open_intent(nd);
1105 * path_lookup_open - lookup a file path with open intent
1106 * @name: pointer to file name
1107 * @lookup_flags: lookup intent flags
1108 * @nd: pointer to nameidata
1109 * @open_flags: open intent flags
1111 int path_lookup_open(const char *name, unsigned int lookup_flags,
1112 struct nameidata *nd, int open_flags)
1114 return __path_lookup_intent_open(name, lookup_flags, nd,
1119 * path_lookup_create - lookup a file path with open + create intent
1120 * @name: pointer to file name
1121 * @lookup_flags: lookup intent flags
1122 * @nd: pointer to nameidata
1123 * @open_flags: open intent flags
1124 * @create_mode: create intent flags
1126 int path_lookup_create(const char *name, unsigned int lookup_flags,
1127 struct nameidata *nd, int open_flags, int create_mode)
1129 return __path_lookup_intent_open(name, lookup_flags|LOOKUP_CREATE, nd,
1130 open_flags, create_mode);
1133 int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags,
1134 struct nameidata *nd, int open_flags)
1136 char *tmp = getname(name);
1137 int err = PTR_ERR(tmp);
1140 err = __path_lookup_intent_open(tmp, lookup_flags, nd, open_flags, 0);
1147 * Restricted form of lookup. Doesn't follow links, single-component only,
1148 * needs parent already locked. Doesn't follow mounts.
1151 static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
1153 struct dentry * dentry;
1154 struct inode *inode;
1157 inode = base->d_inode;
1158 err = permission(inode, MAY_EXEC, nd);
1159 dentry = ERR_PTR(err);
1164 * See if the low-level filesystem might want
1165 * to use its own hash..
1167 if (base->d_op && base->d_op->d_hash) {
1168 err = base->d_op->d_hash(base, name);
1169 dentry = ERR_PTR(err);
1174 dentry = cached_lookup(base, name, nd);
1176 struct dentry *new = d_alloc(base, name);
1177 dentry = ERR_PTR(-ENOMEM);
1180 dentry = inode->i_op->lookup(inode, new, nd);
1190 struct dentry * lookup_hash(struct qstr *name, struct dentry * base)
1192 return __lookup_hash(name, base, NULL);
1196 struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
1207 hash = init_name_hash();
1209 c = *(const unsigned char *)name++;
1210 if (c == '/' || c == '\0')
1212 hash = partial_name_hash(c, hash);
1214 this.hash = end_name_hash(hash);
1216 return lookup_hash(&this, base);
1218 return ERR_PTR(-EACCES);
1224 * is used by most simple commands to get the inode of a specified name.
1225 * Open, link etc use their own routines, but this is enough for things
1228 * namei exists in two versions: namei/lnamei. The only difference is
1229 * that namei follows links, while lnamei does not.
1232 int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
1234 char *tmp = getname(name);
1235 int err = PTR_ERR(tmp);
1238 err = path_lookup(tmp, flags, nd);
1245 * It's inline, so penalty for filesystems that don't use sticky bit is
1248 static inline int check_sticky(struct inode *dir, struct inode *inode)
1250 if (!(dir->i_mode & S_ISVTX))
1252 if (inode->i_uid == current->fsuid)
1254 if (dir->i_uid == current->fsuid)
1256 return !capable(CAP_FOWNER);
1260 * Check whether we can remove a link victim from directory dir, check
1261 * whether the type of victim is right.
1262 * 1. We can't do it if dir is read-only (done in permission())
1263 * 2. We should have write and exec permissions on dir
1264 * 3. We can't remove anything from append-only dir
1265 * 4. We can't do anything with immutable dir (done in permission())
1266 * 5. If the sticky bit on dir is set we should either
1267 * a. be owner of dir, or
1268 * b. be owner of victim, or
1269 * c. have CAP_FOWNER capability
1270 * 6. If the victim is append-only or immutable we can't do antyhing with
1271 * links pointing to it.
1272 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1273 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1274 * 9. We can't remove a root or mountpoint.
1275 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1276 * nfs_async_unlink().
1278 static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1282 if (!victim->d_inode)
1285 BUG_ON(victim->d_parent->d_inode != dir);
1287 error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
1292 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1293 IS_IMMUTABLE(victim->d_inode))
1296 if (!S_ISDIR(victim->d_inode->i_mode))
1298 if (IS_ROOT(victim))
1300 } else if (S_ISDIR(victim->d_inode->i_mode))
1302 if (IS_DEADDIR(dir))
1304 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1309 /* Check whether we can create an object with dentry child in directory
1311 * 1. We can't do it if child already exists (open has special treatment for
1312 * this case, but since we are inlined it's OK)
1313 * 2. We can't do it if dir is read-only (done in permission())
1314 * 3. We should have write and exec permissions on dir
1315 * 4. We can't do it if dir is immutable (done in permission())
1317 static inline int may_create(struct inode *dir, struct dentry *child,
1318 struct nameidata *nd)
1322 if (IS_DEADDIR(dir))
1324 return permission(dir,MAY_WRITE | MAY_EXEC, nd);
1328 * O_DIRECTORY translates into forcing a directory lookup.
1330 static inline int lookup_flags(unsigned int f)
1332 unsigned long retval = LOOKUP_FOLLOW;
1335 retval &= ~LOOKUP_FOLLOW;
1337 if (f & O_DIRECTORY)
1338 retval |= LOOKUP_DIRECTORY;
1344 * p1 and p2 should be directories on the same fs.
1346 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1351 down(&p1->d_inode->i_sem);
1355 down(&p1->d_inode->i_sb->s_vfs_rename_sem);
1357 for (p = p1; p->d_parent != p; p = p->d_parent) {
1358 if (p->d_parent == p2) {
1359 down(&p2->d_inode->i_sem);
1360 down(&p1->d_inode->i_sem);
1365 for (p = p2; p->d_parent != p; p = p->d_parent) {
1366 if (p->d_parent == p1) {
1367 down(&p1->d_inode->i_sem);
1368 down(&p2->d_inode->i_sem);
1373 down(&p1->d_inode->i_sem);
1374 down(&p2->d_inode->i_sem);
1378 void unlock_rename(struct dentry *p1, struct dentry *p2)
1380 up(&p1->d_inode->i_sem);
1382 up(&p2->d_inode->i_sem);
1383 up(&p1->d_inode->i_sb->s_vfs_rename_sem);
1387 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1388 struct nameidata *nd)
1390 int error = may_create(dir, dentry, nd);
1395 if (!dir->i_op || !dir->i_op->create)
1396 return -EACCES; /* shouldn't it be ENOSYS? */
1399 error = security_inode_create(dir, dentry, mode);
1403 error = dir->i_op->create(dir, dentry, mode, nd);
1405 fsnotify_create(dir, dentry->d_name.name);
1409 int may_open(struct nameidata *nd, int acc_mode, int flag)
1411 struct dentry *dentry = nd->dentry;
1412 struct inode *inode = dentry->d_inode;
1418 if (S_ISLNK(inode->i_mode))
1421 if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
1424 error = vfs_permission(nd, acc_mode);
1429 * FIFO's, sockets and device files are special: they don't
1430 * actually live on the filesystem itself, and as such you
1431 * can write to them even if the filesystem is read-only.
1433 if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
1435 } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
1436 if (nd->mnt->mnt_flags & MNT_NODEV)
1440 } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
1443 * An append-only file must be opened in append mode for writing.
1445 if (IS_APPEND(inode)) {
1446 if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1452 /* O_NOATIME can only be set by the owner or superuser */
1453 if (flag & O_NOATIME)
1454 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
1458 * Ensure there are no outstanding leases on the file.
1460 error = break_lease(inode, flag);
1464 if (flag & O_TRUNC) {
1465 error = get_write_access(inode);
1470 * Refuse to truncate files with mandatory locks held on them.
1472 error = locks_verify_locked(inode);
1476 error = do_truncate(dentry, 0, NULL);
1478 put_write_access(inode);
1482 if (flag & FMODE_WRITE)
1491 * namei for open - this is in fact almost the whole open-routine.
1493 * Note that the low bits of "flag" aren't the same as in the open
1494 * system call - they are 00 - no permissions needed
1495 * 01 - read permission needed
1496 * 10 - write permission needed
1497 * 11 - read/write permissions needed
1498 * which is a lot more logical, and also allows the "no perm" needed
1499 * for symlinks (where the permissions are checked later).
1502 int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
1504 int acc_mode, error;
1509 acc_mode = ACC_MODE(flag);
1511 /* O_TRUNC implies we need access checks for write permissions */
1513 acc_mode |= MAY_WRITE;
1515 /* Allow the LSM permission hook to distinguish append
1516 access from general write access. */
1517 if (flag & O_APPEND)
1518 acc_mode |= MAY_APPEND;
1521 * The simplest case - just a plain lookup.
1523 if (!(flag & O_CREAT)) {
1524 error = path_lookup_open(pathname, lookup_flags(flag), nd, flag);
1531 * Create - we need to know the parent.
1533 error = path_lookup_create(pathname, LOOKUP_PARENT, nd, flag, mode);
1538 * We have the parent and last component. First of all, check
1539 * that we are not asked to creat(2) an obvious directory - that
1543 if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
1547 nd->flags &= ~LOOKUP_PARENT;
1548 down(&dir->d_inode->i_sem);
1549 path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1553 error = PTR_ERR(path.dentry);
1554 if (IS_ERR(path.dentry)) {
1555 up(&dir->d_inode->i_sem);
1559 /* Negative dentry, just create the file */
1560 if (!path.dentry->d_inode) {
1561 if (!IS_POSIXACL(dir->d_inode))
1562 mode &= ~current->fs->umask;
1563 error = vfs_create(dir->d_inode, path.dentry, mode, nd);
1564 up(&dir->d_inode->i_sem);
1566 nd->dentry = path.dentry;
1569 /* Don't check for write permission, don't truncate */
1576 * It already exists.
1578 up(&dir->d_inode->i_sem);
1584 if (__follow_mount(&path)) {
1586 if (flag & O_NOFOLLOW)
1590 if (!path.dentry->d_inode)
1592 if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
1595 path_to_nameidata(&path, nd);
1597 if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
1600 error = may_open(nd, acc_mode, flag);
1606 dput_path(&path, nd);
1608 if (!IS_ERR(nd->intent.open.file))
1609 release_open_intent(nd);
1615 if (flag & O_NOFOLLOW)
1618 * This is subtle. Instead of calling do_follow_link() we do the
1619 * thing by hands. The reason is that this way we have zero link_count
1620 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1621 * After that we have the parent and last component, i.e.
1622 * we are in the same situation as after the first path_walk().
1623 * Well, almost - if the last component is normal we get its copy
1624 * stored in nd->last.name and we will have to putname() it when we
1625 * are done. Procfs-like symlinks just set LAST_BIND.
1627 nd->flags |= LOOKUP_PARENT;
1628 error = security_inode_follow_link(path.dentry, nd);
1631 error = __do_follow_link(&path, nd);
1634 nd->flags &= ~LOOKUP_PARENT;
1635 if (nd->last_type == LAST_BIND)
1638 if (nd->last_type != LAST_NORM)
1640 if (nd->last.name[nd->last.len]) {
1641 __putname(nd->last.name);
1646 __putname(nd->last.name);
1650 down(&dir->d_inode->i_sem);
1651 path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1653 __putname(nd->last.name);
1658 * lookup_create - lookup a dentry, creating it if it doesn't exist
1659 * @nd: nameidata info
1660 * @is_dir: directory flag
1662 * Simple function to lookup and return a dentry and create it
1663 * if it doesn't exist. Is SMP-safe.
1665 * Returns with nd->dentry->d_inode->i_sem locked.
1667 struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1669 struct dentry *dentry = ERR_PTR(-EEXIST);
1671 down(&nd->dentry->d_inode->i_sem);
1673 * Yucky last component or no last component at all?
1674 * (foo/., foo/.., /////)
1676 if (nd->last_type != LAST_NORM)
1678 nd->flags &= ~LOOKUP_PARENT;
1681 * Do the final lookup.
1683 dentry = lookup_hash(&nd->last, nd->dentry);
1688 * Special case - lookup gave negative, but... we had foo/bar/
1689 * From the vfs_mknod() POV we just have a negative dentry -
1690 * all is fine. Let's be bastards - you had / on the end, you've
1691 * been asking for (non-existent) directory. -ENOENT for you.
1693 if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
1698 dentry = ERR_PTR(-ENOENT);
1702 EXPORT_SYMBOL_GPL(lookup_create);
1704 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1706 int error = may_create(dir, dentry, NULL);
1711 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1714 if (!dir->i_op || !dir->i_op->mknod)
1717 error = security_inode_mknod(dir, dentry, mode, dev);
1722 error = dir->i_op->mknod(dir, dentry, mode, dev);
1724 fsnotify_create(dir, dentry->d_name.name);
1728 asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev)
1732 struct dentry * dentry;
1733 struct nameidata nd;
1737 tmp = getname(filename);
1739 return PTR_ERR(tmp);
1741 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1744 dentry = lookup_create(&nd, 0);
1745 error = PTR_ERR(dentry);
1747 if (!IS_POSIXACL(nd.dentry->d_inode))
1748 mode &= ~current->fs->umask;
1749 if (!IS_ERR(dentry)) {
1750 switch (mode & S_IFMT) {
1751 case 0: case S_IFREG:
1752 error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
1754 case S_IFCHR: case S_IFBLK:
1755 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
1756 new_decode_dev(dev));
1758 case S_IFIFO: case S_IFSOCK:
1759 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
1769 up(&nd.dentry->d_inode->i_sem);
1777 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1779 int error = may_create(dir, dentry, NULL);
1784 if (!dir->i_op || !dir->i_op->mkdir)
1787 mode &= (S_IRWXUGO|S_ISVTX);
1788 error = security_inode_mkdir(dir, dentry, mode);
1793 error = dir->i_op->mkdir(dir, dentry, mode);
1795 fsnotify_mkdir(dir, dentry->d_name.name);
1799 asmlinkage long sys_mkdir(const char __user * pathname, int mode)
1804 tmp = getname(pathname);
1805 error = PTR_ERR(tmp);
1807 struct dentry *dentry;
1808 struct nameidata nd;
1810 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1813 dentry = lookup_create(&nd, 1);
1814 error = PTR_ERR(dentry);
1815 if (!IS_ERR(dentry)) {
1816 if (!IS_POSIXACL(nd.dentry->d_inode))
1817 mode &= ~current->fs->umask;
1818 error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
1821 up(&nd.dentry->d_inode->i_sem);
1831 * We try to drop the dentry early: we should have
1832 * a usage count of 2 if we're the only user of this
1833 * dentry, and if that is true (possibly after pruning
1834 * the dcache), then we drop the dentry now.
1836 * A low-level filesystem can, if it choses, legally
1839 * if (!d_unhashed(dentry))
1842 * if it cannot handle the case of removing a directory
1843 * that is still in use by something else..
1845 void dentry_unhash(struct dentry *dentry)
1848 if (atomic_read(&dentry->d_count))
1849 shrink_dcache_parent(dentry);
1850 spin_lock(&dcache_lock);
1851 spin_lock(&dentry->d_lock);
1852 if (atomic_read(&dentry->d_count) == 2)
1854 spin_unlock(&dentry->d_lock);
1855 spin_unlock(&dcache_lock);
1858 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
1860 int error = may_delete(dir, dentry, 1);
1865 if (!dir->i_op || !dir->i_op->rmdir)
1870 down(&dentry->d_inode->i_sem);
1871 dentry_unhash(dentry);
1872 if (d_mountpoint(dentry))
1875 error = security_inode_rmdir(dir, dentry);
1877 error = dir->i_op->rmdir(dir, dentry);
1879 dentry->d_inode->i_flags |= S_DEAD;
1882 up(&dentry->d_inode->i_sem);
1891 asmlinkage long sys_rmdir(const char __user * pathname)
1895 struct dentry *dentry;
1896 struct nameidata nd;
1898 name = getname(pathname);
1900 return PTR_ERR(name);
1902 error = path_lookup(name, LOOKUP_PARENT, &nd);
1906 switch(nd.last_type) {
1917 down(&nd.dentry->d_inode->i_sem);
1918 dentry = lookup_hash(&nd.last, nd.dentry);
1919 error = PTR_ERR(dentry);
1920 if (!IS_ERR(dentry)) {
1921 error = vfs_rmdir(nd.dentry->d_inode, dentry);
1924 up(&nd.dentry->d_inode->i_sem);
1932 int vfs_unlink(struct inode *dir, struct dentry *dentry)
1934 int error = may_delete(dir, dentry, 0);
1939 if (!dir->i_op || !dir->i_op->unlink)
1944 down(&dentry->d_inode->i_sem);
1945 if (d_mountpoint(dentry))
1948 error = security_inode_unlink(dir, dentry);
1950 error = dir->i_op->unlink(dir, dentry);
1952 up(&dentry->d_inode->i_sem);
1954 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
1955 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
1963 * Make sure that the actual truncation of the file will occur outside its
1964 * directory's i_sem. Truncate can take a long time if there is a lot of
1965 * writeout happening, and we don't want to prevent access to the directory
1966 * while waiting on the I/O.
1968 asmlinkage long sys_unlink(const char __user * pathname)
1972 struct dentry *dentry;
1973 struct nameidata nd;
1974 struct inode *inode = NULL;
1976 name = getname(pathname);
1978 return PTR_ERR(name);
1980 error = path_lookup(name, LOOKUP_PARENT, &nd);
1984 if (nd.last_type != LAST_NORM)
1986 down(&nd.dentry->d_inode->i_sem);
1987 dentry = lookup_hash(&nd.last, nd.dentry);
1988 error = PTR_ERR(dentry);
1989 if (!IS_ERR(dentry)) {
1990 /* Why not before? Because we want correct error value */
1991 if (nd.last.name[nd.last.len])
1993 inode = dentry->d_inode;
1995 atomic_inc(&inode->i_count);
1996 error = vfs_unlink(nd.dentry->d_inode, dentry);
2000 up(&nd.dentry->d_inode->i_sem);
2002 iput(inode); /* truncate the inode here */
2010 error = !dentry->d_inode ? -ENOENT :
2011 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2015 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
2017 int error = may_create(dir, dentry, NULL);
2022 if (!dir->i_op || !dir->i_op->symlink)
2025 error = security_inode_symlink(dir, dentry, oldname);
2030 error = dir->i_op->symlink(dir, dentry, oldname);
2032 fsnotify_create(dir, dentry->d_name.name);
2036 asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname)
2042 from = getname(oldname);
2044 return PTR_ERR(from);
2045 to = getname(newname);
2046 error = PTR_ERR(to);
2048 struct dentry *dentry;
2049 struct nameidata nd;
2051 error = path_lookup(to, LOOKUP_PARENT, &nd);
2054 dentry = lookup_create(&nd, 0);
2055 error = PTR_ERR(dentry);
2056 if (!IS_ERR(dentry)) {
2057 error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
2060 up(&nd.dentry->d_inode->i_sem);
2069 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2071 struct inode *inode = old_dentry->d_inode;
2077 error = may_create(dir, new_dentry, NULL);
2081 if (dir->i_sb != inode->i_sb)
2085 * A link to an append-only or immutable file cannot be created.
2087 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2089 if (!dir->i_op || !dir->i_op->link)
2091 if (S_ISDIR(old_dentry->d_inode->i_mode))
2094 error = security_inode_link(old_dentry, dir, new_dentry);
2098 down(&old_dentry->d_inode->i_sem);
2100 error = dir->i_op->link(old_dentry, dir, new_dentry);
2101 up(&old_dentry->d_inode->i_sem);
2103 fsnotify_create(dir, new_dentry->d_name.name);
2108 * Hardlinks are often used in delicate situations. We avoid
2109 * security-related surprises by not following symlinks on the
2112 * We don't follow them on the oldname either to be compatible
2113 * with linux 2.0, and to avoid hard-linking to directories
2114 * and other special files. --ADM
2116 asmlinkage long sys_link(const char __user * oldname, const char __user * newname)
2118 struct dentry *new_dentry;
2119 struct nameidata nd, old_nd;
2123 to = getname(newname);
2127 error = __user_walk(oldname, 0, &old_nd);
2130 error = path_lookup(to, LOOKUP_PARENT, &nd);
2134 if (old_nd.mnt != nd.mnt)
2136 new_dentry = lookup_create(&nd, 0);
2137 error = PTR_ERR(new_dentry);
2138 if (!IS_ERR(new_dentry)) {
2139 error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
2142 up(&nd.dentry->d_inode->i_sem);
2146 path_release(&old_nd);
2154 * The worst of all namespace operations - renaming directory. "Perverted"
2155 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2157 * a) we can get into loop creation. Check is done in is_subdir().
2158 * b) race potential - two innocent renames can create a loop together.
2159 * That's where 4.4 screws up. Current fix: serialization on
2160 * sb->s_vfs_rename_sem. We might be more accurate, but that's another
2162 * c) we have to lock _three_ objects - parents and victim (if it exists).
2163 * And that - after we got ->i_sem on parents (until then we don't know
2164 * whether the target exists). Solution: try to be smart with locking
2165 * order for inodes. We rely on the fact that tree topology may change
2166 * only under ->s_vfs_rename_sem _and_ that parent of the object we
2167 * move will be locked. Thus we can rank directories by the tree
2168 * (ancestors first) and rank all non-directories after them.
2169 * That works since everybody except rename does "lock parent, lookup,
2170 * lock child" and rename is under ->s_vfs_rename_sem.
2171 * HOWEVER, it relies on the assumption that any object with ->lookup()
2172 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2173 * we'd better make sure that there's no link(2) for them.
2174 * d) some filesystems don't support opened-but-unlinked directories,
2175 * either because of layout or because they are not ready to deal with
2176 * all cases correctly. The latter will be fixed (taking this sort of
2177 * stuff into VFS), but the former is not going away. Solution: the same
2178 * trick as in rmdir().
2179 * e) conversion from fhandle to dentry may come in the wrong moment - when
2180 * we are removing the target. Solution: we will have to grab ->i_sem
2181 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2182 * ->i_sem on parents, which works but leads to some truely excessive
2185 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2186 struct inode *new_dir, struct dentry *new_dentry)
2189 struct inode *target;
2192 * If we are going to change the parent - check write permissions,
2193 * we'll need to flip '..'.
2195 if (new_dir != old_dir) {
2196 error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
2201 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2205 target = new_dentry->d_inode;
2207 down(&target->i_sem);
2208 dentry_unhash(new_dentry);
2210 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2213 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2216 target->i_flags |= S_DEAD;
2218 if (d_unhashed(new_dentry))
2219 d_rehash(new_dentry);
2223 d_move(old_dentry,new_dentry);
2227 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2228 struct inode *new_dir, struct dentry *new_dentry)
2230 struct inode *target;
2233 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2238 target = new_dentry->d_inode;
2240 down(&target->i_sem);
2241 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2244 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2246 /* The following d_move() should become unconditional */
2247 if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME))
2248 d_move(old_dentry, new_dentry);
2256 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2257 struct inode *new_dir, struct dentry *new_dentry)
2260 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2261 const char *old_name;
2263 if (old_dentry->d_inode == new_dentry->d_inode)
2266 error = may_delete(old_dir, old_dentry, is_dir);
2270 if (!new_dentry->d_inode)
2271 error = may_create(new_dir, new_dentry, NULL);
2273 error = may_delete(new_dir, new_dentry, is_dir);
2277 if (!old_dir->i_op || !old_dir->i_op->rename)
2280 DQUOT_INIT(old_dir);
2281 DQUOT_INIT(new_dir);
2283 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
2286 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2288 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2290 const char *new_name = old_dentry->d_name.name;
2291 fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
2292 new_dentry->d_inode, old_dentry->d_inode);
2294 fsnotify_oldname_free(old_name);
2299 static inline int do_rename(const char * oldname, const char * newname)
2302 struct dentry * old_dir, * new_dir;
2303 struct dentry * old_dentry, *new_dentry;
2304 struct dentry * trap;
2305 struct nameidata oldnd, newnd;
2307 error = path_lookup(oldname, LOOKUP_PARENT, &oldnd);
2311 error = path_lookup(newname, LOOKUP_PARENT, &newnd);
2316 if (oldnd.mnt != newnd.mnt)
2319 old_dir = oldnd.dentry;
2321 if (oldnd.last_type != LAST_NORM)
2324 new_dir = newnd.dentry;
2325 if (newnd.last_type != LAST_NORM)
2328 trap = lock_rename(new_dir, old_dir);
2330 old_dentry = lookup_hash(&oldnd.last, old_dir);
2331 error = PTR_ERR(old_dentry);
2332 if (IS_ERR(old_dentry))
2334 /* source must exist */
2336 if (!old_dentry->d_inode)
2338 /* unless the source is a directory trailing slashes give -ENOTDIR */
2339 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2341 if (oldnd.last.name[oldnd.last.len])
2343 if (newnd.last.name[newnd.last.len])
2346 /* source should not be ancestor of target */
2348 if (old_dentry == trap)
2350 new_dentry = lookup_hash(&newnd.last, new_dir);
2351 error = PTR_ERR(new_dentry);
2352 if (IS_ERR(new_dentry))
2354 /* target should not be an ancestor of source */
2356 if (new_dentry == trap)
2359 error = vfs_rename(old_dir->d_inode, old_dentry,
2360 new_dir->d_inode, new_dentry);
2366 unlock_rename(new_dir, old_dir);
2368 path_release(&newnd);
2370 path_release(&oldnd);
2375 asmlinkage long sys_rename(const char __user * oldname, const char __user * newname)
2381 from = getname(oldname);
2383 return PTR_ERR(from);
2384 to = getname(newname);
2385 error = PTR_ERR(to);
2387 error = do_rename(from,to);
2394 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2398 len = PTR_ERR(link);
2403 if (len > (unsigned) buflen)
2405 if (copy_to_user(buffer, link, len))
2412 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2413 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2414 * using) it for any given inode is up to filesystem.
2416 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2418 struct nameidata nd;
2422 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
2423 if (!IS_ERR(cookie)) {
2424 int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2425 if (dentry->d_inode->i_op->put_link)
2426 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
2427 cookie = ERR_PTR(res);
2429 return PTR_ERR(cookie);
2432 int vfs_follow_link(struct nameidata *nd, const char *link)
2434 return __vfs_follow_link(nd, link);
2437 /* get the link contents into pagecache */
2438 static char *page_getlink(struct dentry * dentry, struct page **ppage)
2441 struct address_space *mapping = dentry->d_inode->i_mapping;
2442 page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
2446 wait_on_page_locked(page);
2447 if (!PageUptodate(page))
2453 page_cache_release(page);
2454 return ERR_PTR(-EIO);
2460 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2462 struct page *page = NULL;
2463 char *s = page_getlink(dentry, &page);
2464 int res = vfs_readlink(dentry,buffer,buflen,s);
2467 page_cache_release(page);
2472 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
2474 struct page *page = NULL;
2475 nd_set_link(nd, page_getlink(dentry, &page));
2479 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2481 struct page *page = cookie;
2485 page_cache_release(page);
2489 int page_symlink(struct inode *inode, const char *symname, int len)
2491 struct address_space *mapping = inode->i_mapping;
2492 struct page *page = grab_cache_page(mapping, 0);
2498 err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
2501 kaddr = kmap_atomic(page, KM_USER0);
2502 memcpy(kaddr, symname, len-1);
2503 kunmap_atomic(kaddr, KM_USER0);
2504 mapping->a_ops->commit_write(NULL, page, 0, len-1);
2506 * Notice that we are _not_ going to block here - end of page is
2507 * unmapped, so this will only try to map the rest of page, see
2508 * that it is unmapped (typically even will not look into inode -
2509 * ->i_size will be enough for everything) and zero it out.
2510 * OTOH it's obviously correct and should make the page up-to-date.
2512 if (!PageUptodate(page)) {
2513 err = mapping->a_ops->readpage(NULL, page);
2514 wait_on_page_locked(page);
2518 page_cache_release(page);
2521 mark_inode_dirty(inode);
2525 page_cache_release(page);
2530 struct inode_operations page_symlink_inode_operations = {
2531 .readlink = generic_readlink,
2532 .follow_link = page_follow_link_light,
2533 .put_link = page_put_link,
2536 EXPORT_SYMBOL(__user_walk);
2537 EXPORT_SYMBOL(follow_down);
2538 EXPORT_SYMBOL(follow_up);
2539 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2540 EXPORT_SYMBOL(getname);
2541 EXPORT_SYMBOL(lock_rename);
2542 EXPORT_SYMBOL(lookup_hash);
2543 EXPORT_SYMBOL(lookup_one_len);
2544 EXPORT_SYMBOL(page_follow_link_light);
2545 EXPORT_SYMBOL(page_put_link);
2546 EXPORT_SYMBOL(page_readlink);
2547 EXPORT_SYMBOL(page_symlink);
2548 EXPORT_SYMBOL(page_symlink_inode_operations);
2549 EXPORT_SYMBOL(path_lookup);
2550 EXPORT_SYMBOL(path_release);
2551 EXPORT_SYMBOL(path_walk);
2552 EXPORT_SYMBOL(permission);
2553 EXPORT_SYMBOL(vfs_permission);
2554 EXPORT_SYMBOL(unlock_rename);
2555 EXPORT_SYMBOL(vfs_create);
2556 EXPORT_SYMBOL(vfs_follow_link);
2557 EXPORT_SYMBOL(vfs_link);
2558 EXPORT_SYMBOL(vfs_mkdir);
2559 EXPORT_SYMBOL(vfs_mknod);
2560 EXPORT_SYMBOL(generic_permission);
2561 EXPORT_SYMBOL(vfs_readlink);
2562 EXPORT_SYMBOL(vfs_rename);
2563 EXPORT_SYMBOL(vfs_rmdir);
2564 EXPORT_SYMBOL(vfs_symlink);
2565 EXPORT_SYMBOL(vfs_unlink);
2566 EXPORT_SYMBOL(dentry_unhash);
2567 EXPORT_SYMBOL(generic_readlink);