1 /*
2 * linux/fs/namei.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 /*
8 * Some corrections by tytso.
9 */
10
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
12 * lookup logic.
13 */
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
15 */
16
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
20 #include <linux/fs.h>
21 #include <linux/namei.h>
22 #include <linux/quotaops.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/ima.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/capability.h>
32 #include <linux/file.h>
33 #include <linux/fcntl.h>
34 #include <linux/device_cgroup.h>
35 #include <linux/fs_struct.h>
36 #include <asm/uaccess.h>
37
38 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
39
40 /* [Feb-1997 T. Schoebel-Theuer]
41 * Fundamental changes in the pathname lookup mechanisms (namei)
42 * were necessary because of omirr. The reason is that omirr needs
43 * to know the _real_ pathname, not the user-supplied one, in case
44 * of symlinks (and also when transname replacements occur).
45 *
46 * The new code replaces the old recursive symlink resolution with
47 * an iterative one (in case of non-nested symlink chains). It does
48 * this with calls to <fs>_follow_link().
49 * As a side effect, dir_namei(), _namei() and follow_link() are now
50 * replaced with a single function lookup_dentry() that can handle all
51 * the special cases of the former code.
52 *
53 * With the new dcache, the pathname is stored at each inode, at least as
54 * long as the refcount of the inode is positive. As a side effect, the
55 * size of the dcache depends on the inode cache and thus is dynamic.
56 *
57 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
58 * resolution to correspond with current state of the code.
59 *
60 * Note that the symlink resolution is not *completely* iterative.
61 * There is still a significant amount of tail- and mid- recursion in
62 * the algorithm. Also, note that <fs>_readlink() is not used in
63 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
64 * may return different results than <fs>_follow_link(). Many virtual
65 * filesystems (including /proc) exhibit this behavior.
66 */
67
68 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
69 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
70 * and the name already exists in form of a symlink, try to create the new
71 * name indicated by the symlink. The old code always complained that the
72 * name already exists, due to not following the symlink even if its target
73 * is nonexistent. The new semantics affects also mknod() and link() when
74 * the name is a symlink pointing to a non-existant name.
75 *
76 * I don't know which semantics is the right one, since I have no access
77 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
78 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
79 * "old" one. Personally, I think the new semantics is much more logical.
80 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
81 * file does succeed in both HP-UX and SunOs, but not in Solaris
82 * and in the old Linux semantics.
83 */
84
85 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
86 * semantics. See the comments in "open_namei" and "do_link" below.
87 *
88 * [10-Sep-98 Alan Modra] Another symlink change.
89 */
90
91 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
92 * inside the path - always follow.
93 * in the last component in creation/removal/renaming - never follow.
94 * if LOOKUP_FOLLOW passed - follow.
95 * if the pathname has trailing slashes - follow.
96 * otherwise - don't follow.
97 * (applied in that order).
98 *
99 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
100 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
101 * During the 2.4 we need to fix the userland stuff depending on it -
102 * hopefully we will be able to get rid of that wart in 2.5. So far only
103 * XEmacs seems to be relying on it...
104 */
105 /*
106 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
107 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
108 * any extra contention...
109 */
110
111 static int __link_path_walk(const char *name, struct nameidata *nd);
112
113 /* In order to reduce some races, while at the same time doing additional
114 * checking and hopefully speeding things up, we copy filenames to the
115 * kernel data space before using them..
116 *
117 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
118 * PATH_MAX includes the nul terminator --RR.
119 */
120 static int do_getname(const char __user *filename, char *page)
121 {
122 int retval;
123 unsigned long len = PATH_MAX;
124
125 if (!segment_eq(get_fs(), KERNEL_DS)) {
126 if ((unsigned long) filename >= TASK_SIZE)
127 return -EFAULT;
128 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
129 len = TASK_SIZE - (unsigned long) filename;
130 }
131
132 retval = strncpy_from_user(page, filename, len);
133 if (retval > 0) {
134 if (retval < len)
135 return 0;
136 return -ENAMETOOLONG;
137 } else if (!retval)
138 retval = -ENOENT;
139 return retval;
140 }
141
142 char * getname(const char __user * filename)
143 {
144 char *tmp, *result;
145
146 result = ERR_PTR(-ENOMEM);
147 tmp = __getname();
148 if (tmp) {
149 int retval = do_getname(filename, tmp);
150
151 result = tmp;
152 if (retval < 0) {
153 __putname(tmp);
154 result = ERR_PTR(retval);
155 }
156 }
157 audit_getname(result);
158 return result;
159 }
160
161 #ifdef CONFIG_AUDITSYSCALL
162 void putname(const char *name)
163 {
164 if (unlikely(!audit_dummy_context()))
165 audit_putname(name);
166 else
167 __putname(name);
168 }
169 EXPORT_SYMBOL(putname);
170 #endif
171
172
173 /**
174 * generic_permission - check for access rights on a Posix-like filesystem
175 * @inode: inode to check access rights for
176 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
177 * @check_acl: optional callback to check for Posix ACLs
178 *
179 * Used to check for read/write/execute permissions on a file.
180 * We use "fsuid" for this, letting us set arbitrary permissions
181 * for filesystem access without changing the "normal" uids which
182 * are used for other things..
183 */
184 int generic_permission(struct inode *inode, int mask,
185 int (*check_acl)(struct inode *inode, int mask))
186 {
187 umode_t mode = inode->i_mode;
188
189 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
190
191 if (current_fsuid() == inode->i_uid)
192 mode >>= 6;
193 else {
194 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
195 int error = check_acl(inode, mask);
196 if (error == -EACCES)
197 goto check_capabilities;
198 else if (error != -EAGAIN)
199 return error;
200 }
201
202 if (in_group_p(inode->i_gid))
203 mode >>= 3;
204 }
205
206 /*
207 * If the DACs are ok we don't need any capability check.
208 */
209 if ((mask & ~mode) == 0)
210 return 0;
211
212 check_capabilities:
213 /*
214 * Read/write DACs are always overridable.
215 * Executable DACs are overridable if at least one exec bit is set.
216 */
217 if (!(mask & MAY_EXEC) || execute_ok(inode))
218 if (capable(CAP_DAC_OVERRIDE))
219 return 0;
220
221 /*
222 * Searching includes executable on directories, else just read.
223 */
224 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
225 if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
226 if (capable(CAP_DAC_READ_SEARCH))
227 return 0;
228
229 return -EACCES;
230 }
231
232 /**
233 * inode_permission - check for access rights to a given inode
234 * @inode: inode to check permission on
235 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
236 *
237 * Used to check for read/write/execute permissions on an inode.
238 * We use "fsuid" for this, letting us set arbitrary permissions
239 * for filesystem access without changing the "normal" uids which
240 * are used for other things.
241 */
242 int inode_permission(struct inode *inode, int mask)
243 {
244 int retval;
245
246 if (mask & MAY_WRITE) {
247 umode_t mode = inode->i_mode;
248
249 /*
250 * Nobody gets write access to a read-only fs.
251 */
252 if (IS_RDONLY(inode) &&
253 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
254 return -EROFS;
255
256 /*
257 * Nobody gets write access to an immutable file.
258 */
259 if (IS_IMMUTABLE(inode))
260 return -EACCES;
261 }
262
263 if (inode->i_op->permission)
264 retval = inode->i_op->permission(inode, mask);
265 else
266 retval = generic_permission(inode, mask, NULL);
267
268 if (retval)
269 return retval;
270
271 retval = devcgroup_inode_permission(inode, mask);
272 if (retval)
273 return retval;
274
275 return security_inode_permission(inode,
276 mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND));
277 }
278
279 /**
280 * file_permission - check for additional access rights to a given file
281 * @file: file to check access rights for
282 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
283 *
284 * Used to check for read/write/execute permissions on an already opened
285 * file.
286 *
287 * Note:
288 * Do not use this function in new code. All access checks should
289 * be done using inode_permission().
290 */
291 int file_permission(struct file *file, int mask)
292 {
293 return inode_permission(file->f_path.dentry->d_inode, mask);
294 }
295
296 /*
297 * get_write_access() gets write permission for a file.
298 * put_write_access() releases this write permission.
299 * This is used for regular files.
300 * We cannot support write (and maybe mmap read-write shared) accesses and
301 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
302 * can have the following values:
303 * 0: no writers, no VM_DENYWRITE mappings
304 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
305 * > 0: (i_writecount) users are writing to the file.
306 *
307 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
308 * except for the cases where we don't hold i_writecount yet. Then we need to
309 * use {get,deny}_write_access() - these functions check the sign and refuse
310 * to do the change if sign is wrong. Exclusion between them is provided by
311 * the inode->i_lock spinlock.
312 */
313
314 int get_write_access(struct inode * inode)
315 {
316 spin_lock(&inode->i_lock);
317 if (atomic_read(&inode->i_writecount) < 0) {
318 spin_unlock(&inode->i_lock);
319 return -ETXTBSY;
320 }
321 atomic_inc(&inode->i_writecount);
322 spin_unlock(&inode->i_lock);
323
324 return 0;
325 }
326
327 int deny_write_access(struct file * file)
328 {
329 struct inode *inode = file->f_path.dentry->d_inode;
330
331 spin_lock(&inode->i_lock);
332 if (atomic_read(&inode->i_writecount) > 0) {
333 spin_unlock(&inode->i_lock);
334 return -ETXTBSY;
335 }
336 atomic_dec(&inode->i_writecount);
337 spin_unlock(&inode->i_lock);
338
339 return 0;
340 }
341
342 /**
343 * path_get - get a reference to a path
344 * @path: path to get the reference to
345 *
346 * Given a path increment the reference count to the dentry and the vfsmount.
347 */
348 void path_get(struct path *path)
349 {
350 mntget(path->mnt);
351 dget(path->dentry);
352 }
353 EXPORT_SYMBOL(path_get);
354
355 /**
356 * path_put - put a reference to a path
357 * @path: path to put the reference to
358 *
359 * Given a path decrement the reference count to the dentry and the vfsmount.
360 */
361 void path_put(struct path *path)
362 {
363 dput(path->dentry);
364 mntput(path->mnt);
365 }
366 EXPORT_SYMBOL(path_put);
367
368 /**
369 * release_open_intent - free up open intent resources
370 * @nd: pointer to nameidata
371 */
372 void release_open_intent(struct nameidata *nd)
373 {
374 if (nd->intent.open.file->f_path.dentry == NULL)
375 put_filp(nd->intent.open.file);
376 else
377 fput(nd->intent.open.file);
378 }
379
380 static inline struct dentry *
381 do_revalidate(struct dentry *dentry, struct nameidata *nd)
382 {
383 int status = dentry->d_op->d_revalidate(dentry, nd);
384 if (unlikely(status <= 0)) {
385 /*
386 * The dentry failed validation.
387 * If d_revalidate returned 0 attempt to invalidate
388 * the dentry otherwise d_revalidate is asking us
389 * to return a fail status.
390 */
391 if (!status) {
392 if (!d_invalidate(dentry)) {
393 dput(dentry);
394 dentry = NULL;
395 }
396 } else {
397 dput(dentry);
398 dentry = ERR_PTR(status);
399 }
400 }
401 return dentry;
402 }
403
404 /*
405 * Internal lookup() using the new generic dcache.
406 * SMP-safe
407 */
408 static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
409 {
410 struct dentry * dentry = __d_lookup(parent, name);
411
412 /* lockess __d_lookup may fail due to concurrent d_move()
413 * in some unrelated directory, so try with d_lookup
414 */
415 if (!dentry)
416 dentry = d_lookup(parent, name);
417
418 if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
419 dentry = do_revalidate(dentry, nd);
420
421 return dentry;
422 }
423
424 /*
425 * Short-cut version of permission(), for calling by
426 * path_walk(), when dcache lock is held. Combines parts
427 * of permission() and generic_permission(), and tests ONLY for
428 * MAY_EXEC permission.
429 *
430 * If appropriate, check DAC only. If not appropriate, or
431 * short-cut DAC fails, then call permission() to do more
432 * complete permission check.
433 */
434 static int exec_permission_lite(struct inode *inode)
435 {
436 umode_t mode = inode->i_mode;
437
438 if (inode->i_op->permission)
439 return -EAGAIN;
440
441 if (current_fsuid() == inode->i_uid)
442 mode >>= 6;
443 else if (in_group_p(inode->i_gid))
444 mode >>= 3;
445
446 if (mode & MAY_EXEC)
447 goto ok;
448
449 if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
450 goto ok;
451
452 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
453 goto ok;
454
455 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
456 goto ok;
457
458 return -EACCES;
459 ok:
460 return security_inode_permission(inode, MAY_EXEC);
461 }
462
463 /*
464 * This is called when everything else fails, and we actually have
465 * to go to the low-level filesystem to find out what we should do..
466 *
467 * We get the directory semaphore, and after getting that we also
468 * make sure that nobody added the entry to the dcache in the meantime..
469 * SMP-safe
470 */
471 static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
472 {
473 struct dentry * result;
474 struct inode *dir = parent->d_inode;
475
476 mutex_lock(&dir->i_mutex);
477 /*
478 * First re-do the cached lookup just in case it was created
479 * while we waited for the directory semaphore..
480 *
481 * FIXME! This could use version numbering or similar to
482 * avoid unnecessary cache lookups.
483 *
484 * The "dcache_lock" is purely to protect the RCU list walker
485 * from concurrent renames at this point (we mustn't get false
486 * negatives from the RCU list walk here, unlike the optimistic
487 * fast walk).
488 *
489 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
490 */
491 result = d_lookup(parent, name);
492 if (!result) {
493 struct dentry *dentry;
494
495 /* Don't create child dentry for a dead directory. */
496 result = ERR_PTR(-ENOENT);
497 if (IS_DEADDIR(dir))
498 goto out_unlock;
499
500 dentry = d_alloc(parent, name);
501 result = ERR_PTR(-ENOMEM);
502 if (dentry) {
503 result = dir->i_op->lookup(dir, dentry, nd);
504 if (result)
505 dput(dentry);
506 else
507 result = dentry;
508 }
509 out_unlock:
510 mutex_unlock(&dir->i_mutex);
511 return result;
512 }
513
514 /*
515 * Uhhuh! Nasty case: the cache was re-populated while
516 * we waited on the semaphore. Need to revalidate.
517 */
518 mutex_unlock(&dir->i_mutex);
519 if (result->d_op && result->d_op->d_revalidate) {
520 result = do_revalidate(result, nd);
521 if (!result)
522 result = ERR_PTR(-ENOENT);
523 }
524 return result;
525 }
526
527 /*
528 * Wrapper to retry pathname resolution whenever the underlying
529 * file system returns an ESTALE.
530 *
531 * Retry the whole path once, forcing real lookup requests
532 * instead of relying on the dcache.
533 */
534 static __always_inline int link_path_walk(const char *name, struct nameidata *nd)
535 {
536 struct path save = nd->path;
537 int result;
538
539 /* make sure the stuff we saved doesn't go away */
540 path_get(&save);
541
542 result = __link_path_walk(name, nd);
543 if (result == -ESTALE) {
544 /* nd->path had been dropped */
545 nd->path = save;
546 path_get(&nd->path);
547 nd->flags |= LOOKUP_REVAL;
548 result = __link_path_walk(name, nd);
549 }
550
551 path_put(&save);
552
553 return result;
554 }
555
556 static __always_inline void set_root(struct nameidata *nd)
557 {
558 if (!nd->root.mnt) {
559 struct fs_struct *fs = current->fs;
560 read_lock(&fs->lock);
561 nd->root = fs->root;
562 path_get(&nd->root);
563 read_unlock(&fs->lock);
564 }
565 }
566
567 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
568 {
569 int res = 0;
570 char *name;
571 if (IS_ERR(link))
572 goto fail;
573
574 if (*link == '/') {
575 set_root(nd);
576 path_put(&nd->path);
577 nd->path = nd->root;
578 path_get(&nd->root);
579 }
580
581 res = link_path_walk(link, nd);
582 if (nd->depth || res || nd->last_type!=LAST_NORM)
583 return res;
584 /*
585 * If it is an iterative symlinks resolution in open_namei() we
586 * have to copy the last component. And all that crap because of
587 * bloody create() on broken symlinks. Furrfu...
588 */
589 name = __getname();
590 if (unlikely(!name)) {
591 path_put(&nd->path);
592 return -ENOMEM;
593 }
594 strcpy(name, nd->last.name);
595 nd->last.name = name;
596 return 0;
597 fail:
598 path_put(&nd->path);
599 return PTR_ERR(link);
600 }
601
602 static void path_put_conditional(struct path *path, struct nameidata *nd)
603 {
604 dput(path->dentry);
605 if (path->mnt != nd->path.mnt)
606 mntput(path->mnt);
607 }
608
609 static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
610 {
611 dput(nd->path.dentry);
612 if (nd->path.mnt != path->mnt)
613 mntput(nd->path.mnt);
614 nd->path.mnt = path->mnt;
615 nd->path.dentry = path->dentry;
616 }
617
618 static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
619 {
620 int error;
621 void *cookie;
622 struct dentry *dentry = path->dentry;
623
624 touch_atime(path->mnt, dentry);
625 nd_set_link(nd, NULL);
626
627 if (path->mnt != nd->path.mnt) {
628 path_to_nameidata(path, nd);
629 dget(dentry);
630 }
631 mntget(path->mnt);
632 cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
633 error = PTR_ERR(cookie);
634 if (!IS_ERR(cookie)) {
635 char *s = nd_get_link(nd);
636 error = 0;
637 if (s)
638 error = __vfs_follow_link(nd, s);
639 if (dentry->d_inode->i_op->put_link)
640 dentry->d_inode->i_op->put_link(dentry, nd, cookie);
641 }
642 path_put(path);
643
644 return error;
645 }
646
647 /*
648 * This limits recursive symlink follows to 8, while
649 * limiting consecutive symlinks to 40.
650 *
651 * Without that kind of total limit, nasty chains of consecutive
652 * symlinks can cause almost arbitrarily long lookups.
653 */
654 static inline int do_follow_link(struct path *path, struct nameidata *nd)
655 {
656 int err = -ELOOP;
657 if (current->link_count >= MAX_NESTED_LINKS)
658 goto loop;
659 if (current->total_link_count >= 40)
660 goto loop;
661 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
662 cond_resched();
663 err = security_inode_follow_link(path->dentry, nd);
664 if (err)
665 goto loop;
666 current->link_count++;
667 current->total_link_count++;
668 nd->depth++;
669 err = __do_follow_link(path, nd);
670 current->link_count--;
671 nd->depth--;
672 return err;
673 loop:
674 path_put_conditional(path, nd);
675 path_put(&nd->path);
676 return err;
677 }
678
679 int follow_up(struct path *path)
680 {
681 struct vfsmount *parent;
682 struct dentry *mountpoint;
683 spin_lock(&vfsmount_lock);
684 parent = path->mnt->mnt_parent;
685 if (parent == path->mnt) {
686 spin_unlock(&vfsmount_lock);
687 return 0;
688 }
689 mntget(parent);
690 mountpoint = dget(path->mnt->mnt_mountpoint);
691 spin_unlock(&vfsmount_lock);
692 dput(path->dentry);
693 path->dentry = mountpoint;
694 mntput(path->mnt);
695 path->mnt = parent;
696 return 1;
697 }
698
699 /* no need for dcache_lock, as serialization is taken care in
700 * namespace.c
701 */
702 static int __follow_mount(struct path *path)
703 {
704 int res = 0;
705 while (d_mountpoint(path->dentry)) {
706 struct vfsmount *mounted = lookup_mnt(path);
707 if (!mounted)
708 break;
709 dput(path->dentry);
710 if (res)
711 mntput(path->mnt);
712 path->mnt = mounted;
713 path->dentry = dget(mounted->mnt_root);
714 res = 1;
715 }
716 return res;
717 }
718
719 static void follow_mount(struct path *path)
720 {
721 while (d_mountpoint(path->dentry)) {
722 struct vfsmount *mounted = lookup_mnt(path);
723 if (!mounted)
724 break;
725 dput(path->dentry);
726 mntput(path->mnt);
727 path->mnt = mounted;
728 path->dentry = dget(mounted->mnt_root);
729 }
730 }
731
732 /* no need for dcache_lock, as serialization is taken care in
733 * namespace.c
734 */
735 int follow_down(struct path *path)
736 {
737 struct vfsmount *mounted;
738
739 mounted = lookup_mnt(path);
740 if (mounted) {
741 dput(path->dentry);
742 mntput(path->mnt);
743 path->mnt = mounted;
744 path->dentry = dget(mounted->mnt_root);
745 return 1;
746 }
747 return 0;
748 }
749
750 static __always_inline void follow_dotdot(struct nameidata *nd)
751 {
752 set_root(nd);
753
754 while(1) {
755 struct vfsmount *parent;
756 struct dentry *old = nd->path.dentry;
757
758 if (nd->path.dentry == nd->root.dentry &&
759 nd->path.mnt == nd->root.mnt) {
760 break;
761 }
762 spin_lock(&dcache_lock);
763 if (nd->path.dentry != nd->path.mnt->mnt_root) {
764 nd->path.dentry = dget(nd->path.dentry->d_parent);
765 spin_unlock(&dcache_lock);
766 dput(old);
767 break;
768 }
769 spin_unlock(&dcache_lock);
770 spin_lock(&vfsmount_lock);
771 parent = nd->path.mnt->mnt_parent;
772 if (parent == nd->path.mnt) {
773 spin_unlock(&vfsmount_lock);
774 break;
775 }
776 mntget(parent);
777 nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint);
778 spin_unlock(&vfsmount_lock);
779 dput(old);
780 mntput(nd->path.mnt);
781 nd->path.mnt = parent;
782 }
783 follow_mount(&nd->path);
784 }
785
786 /*
787 * It's more convoluted than I'd like it to be, but... it's still fairly
788 * small and for now I'd prefer to have fast path as straight as possible.
789 * It _is_ time-critical.
790 */
791 static int do_lookup(struct nameidata *nd, struct qstr *name,
792 struct path *path)
793 {
794 struct vfsmount *mnt = nd->path.mnt;
795 struct dentry *dentry = __d_lookup(nd->path.dentry, name);
796
797 if (!dentry)
798 goto need_lookup;
799 if (dentry->d_op && dentry->d_op->d_revalidate)
800 goto need_revalidate;
801 done:
802 path->mnt = mnt;
803 path->dentry = dentry;
804 __follow_mount(path);
805 return 0;
806
807 need_lookup:
808 dentry = real_lookup(nd->path.dentry, name, nd);
809 if (IS_ERR(dentry))
810 goto fail;
811 goto done;
812
813 need_revalidate:
814 dentry = do_revalidate(dentry, nd);
815 if (!dentry)
816 goto need_lookup;
817 if (IS_ERR(dentry))
818 goto fail;
819 goto done;
820
821 fail:
822 return PTR_ERR(dentry);
823 }
824
825 /*
826 * This is a temporary kludge to deal with "automount" symlinks; proper
827 * solution is to trigger them on follow_mount(), so that do_lookup()
828 * would DTRT. To be killed before 2.6.34-final.
829 */
830 static inline int follow_on_final(struct inode *inode, unsigned lookup_flags)
831 {
832 return inode && unlikely(inode->i_op->follow_link) &&
833 ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode));
834 }
835
836 /*
837 * Name resolution.
838 * This is the basic name resolution function, turning a pathname into
839 * the final dentry. We expect 'base' to be positive and a directory.
840 *
841 * Returns 0 and nd will have valid dentry and mnt on success.
842 * Returns error and drops reference to input namei data on failure.
843 */
844 static int __link_path_walk(const char *name, struct nameidata *nd)
845 {
846 struct path next;
847 struct inode *inode;
848 int err;
849 unsigned int lookup_flags = nd->flags;
850
851 while (*name=='/')
852 name++;
853 if (!*name)
854 goto return_reval;
855
856 inode = nd->path.dentry->d_inode;
857 if (nd->depth)
858 lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
859
860 /* At this point we know we have a real path component. */
861 for(;;) {
862 unsigned long hash;
863 struct qstr this;
864 unsigned int c;
865
866 nd->flags |= LOOKUP_CONTINUE;
867 err = exec_permission_lite(inode);
868 if (err == -EAGAIN)
869 err = inode_permission(nd->path.dentry->d_inode,
870 MAY_EXEC);
871 if (!err)
872 err = ima_path_check(&nd->path, MAY_EXEC,
873 IMA_COUNT_UPDATE);
874 if (err)
875 break;
876
877 this.name = name;
878 c = *(const unsigned char *)name;
879
880 hash = init_name_hash();
881 do {
882 name++;
883 hash = partial_name_hash(c, hash);
884 c = *(const unsigned char *)name;
885 } while (c && (c != '/'));
886 this.len = name - (const char *) this.name;
887 this.hash = end_name_hash(hash);
888
889 /* remove trailing slashes? */
890 if (!c)
891 goto last_component;
892 while (*++name == '/');
893 if (!*name)
894 goto last_with_slashes;
895
896 /*
897 * "." and ".." are special - ".." especially so because it has
898 * to be able to know about the current root directory and
899 * parent relationships.
900 */
901 if (this.name[0] == '.') switch (this.len) {
902 default:
903 break;
904 case 2:
905 if (this.name[1] != '.')
906 break;
907 follow_dotdot(nd);
908 inode = nd->path.dentry->d_inode;
909 /* fallthrough */
910 case 1:
911 continue;
912 }
913 /*
914 * See if the low-level filesystem might want
915 * to use its own hash..
916 */
917 if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
918 err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
919 &this);
920 if (err < 0)
921 break;
922 }
923 /* This does the actual lookups.. */
924 err = do_lookup(nd, &this, &next);
925 if (err)
926 break;
927
928 err = -ENOENT;
929 inode = next.dentry->d_inode;
930 if (!inode)
931 goto out_dput;
932
933 if (inode->i_op->follow_link) {
934 err = do_follow_link(&next, nd);
935 if (err)
936 goto return_err;
937 err = -ENOENT;
938 inode = nd->path.dentry->d_inode;
939 if (!inode)
940 break;
941 } else
942 path_to_nameidata(&next, nd);
943 err = -ENOTDIR;
944 if (!inode->i_op->lookup)
945 break;
946 continue;
947 /* here ends the main loop */
948
949 last_with_slashes:
950 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
951 last_component:
952 /* Clear LOOKUP_CONTINUE iff it was previously unset */
953 nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
954 if (lookup_flags & LOOKUP_PARENT)
955 goto lookup_parent;
956 if (this.name[0] == '.') switch (this.len) {
957 default:
958 break;
959 case 2:
960 if (this.name[1] != '.')
961 break;
962 follow_dotdot(nd);
963 inode = nd->path.dentry->d_inode;
964 /* fallthrough */
965 case 1:
966 goto return_reval;
967 }
968 if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
969 err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
970 &this);
971 if (err < 0)
972 break;
973 }
974 err = do_lookup(nd, &this, &next);
975 if (err)
976 break;
977 inode = next.dentry->d_inode;
978 if (follow_on_final(inode, lookup_flags)) {
979 err = do_follow_link(&next, nd);
980 if (err)
981 goto return_err;
982 inode = nd->path.dentry->d_inode;
983 } else
984 path_to_nameidata(&next, nd);
985 err = -ENOENT;
986 if (!inode)
987 break;
988 if (lookup_flags & LOOKUP_DIRECTORY) {
989 err = -ENOTDIR;
990 if (!inode->i_op->lookup)
991 break;
992 }
993 goto return_base;
994 lookup_parent:
995 nd->last = this;
996 nd->last_type = LAST_NORM;
997 if (this.name[0] != '.')
998 goto return_base;
999 if (this.len == 1)
1000 nd->last_type = LAST_DOT;
1001 else if (this.len == 2 && this.name[1] == '.')
1002 nd->last_type = LAST_DOTDOT;
1003 else
1004 goto return_base;
1005 return_reval:
1006 /*
1007 * We bypassed the ordinary revalidation routines.
1008 * We may need to check the cached dentry for staleness.
1009 */
1010 if (nd->path.dentry && nd->path.dentry->d_sb &&
1011 (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
1012 err = -ESTALE;
1013 /* Note: we do not d_invalidate() */
1014 if (!nd->path.dentry->d_op->d_revalidate(
1015 nd->path.dentry, nd))
1016 break;
1017 }
1018 return_base:
1019 return 0;
1020 out_dput:
1021 path_put_conditional(&next, nd);
1022 break;
1023 }
1024 path_put(&nd->path);
1025 return_err:
1026 return err;
1027 }
1028
1029 static int path_walk(const char *name, struct nameidata *nd)
1030 {
1031 current->total_link_count = 0;
1032 return link_path_walk(name, nd);
1033 }
1034
1035 static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
1036 {
1037 int retval = 0;
1038 int fput_needed;
1039 struct file *file;
1040
1041 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1042 nd->flags = flags;
1043 nd->depth = 0;
1044 nd->root.mnt = NULL;
1045
1046 if (*name=='/') {
1047 set_root(nd);
1048 nd->path = nd->root;
1049 path_get(&nd->root);
1050 } else if (dfd == AT_FDCWD) {
1051 struct fs_struct *fs = current->fs;
1052 read_lock(&fs->lock);
1053 nd->path = fs->pwd;
1054 path_get(&fs->pwd);
1055 read_unlock(&fs->lock);
1056 } else {
1057 struct dentry *dentry;
1058
1059 file = fget_light(dfd, &fput_needed);
1060 retval = -EBADF;
1061 if (!file)
1062 goto out_fail;
1063
1064 dentry = file->f_path.dentry;
1065
1066 retval = -ENOTDIR;
1067 if (!S_ISDIR(dentry->d_inode->i_mode))
1068 goto fput_fail;
1069
1070 retval = file_permission(file, MAY_EXEC);
1071 if (retval)
1072 goto fput_fail;
1073
1074 nd->path = file->f_path;
1075 path_get(&file->f_path);
1076
1077 fput_light(file, fput_needed);
1078 }
1079 return 0;
1080
1081 fput_fail:
1082 fput_light(file, fput_needed);
1083 out_fail:
1084 return retval;
1085 }
1086
1087 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1088 static int do_path_lookup(int dfd, const char *name,
1089 unsigned int flags, struct nameidata *nd)
1090 {
1091 int retval = path_init(dfd, name, flags, nd);
1092 if (!retval)
1093 retval = path_walk(name, nd);
1094 if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
1095 nd->path.dentry->d_inode))
1096 audit_inode(name, nd->path.dentry);
1097 if (nd->root.mnt) {
1098 path_put(&nd->root);
1099 nd->root.mnt = NULL;
1100 }
1101 return retval;
1102 }
1103
1104 int path_lookup(const char *name, unsigned int flags,
1105 struct nameidata *nd)
1106 {
1107 return do_path_lookup(AT_FDCWD, name, flags, nd);
1108 }
1109
1110 int kern_path(const char *name, unsigned int flags, struct path *path)
1111 {
1112 struct nameidata nd;
1113 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1114 if (!res)
1115 *path = nd.path;
1116 return res;
1117 }
1118
1119 /**
1120 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1121 * @dentry: pointer to dentry of the base directory
1122 * @mnt: pointer to vfs mount of the base directory
1123 * @name: pointer to file name
1124 * @flags: lookup flags
1125 * @nd: pointer to nameidata
1126 */
1127 int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1128 const char *name, unsigned int flags,
1129 struct nameidata *nd)
1130 {
1131 int retval;
1132
1133 /* same as do_path_lookup */
1134 nd->last_type = LAST_ROOT;
1135 nd->flags = flags;
1136 nd->depth = 0;
1137
1138 nd->path.dentry = dentry;
1139 nd->path.mnt = mnt;
1140 path_get(&nd->path);
1141 nd->root = nd->path;
1142 path_get(&nd->root);
1143
1144 retval = path_walk(name, nd);
1145 if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
1146 nd->path.dentry->d_inode))
1147 audit_inode(name, nd->path.dentry);
1148
1149 path_put(&nd->root);
1150 nd->root.mnt = NULL;
1151
1152 return retval;
1153 }
1154
1155 /**
1156 * path_lookup_open - lookup a file path with open intent
1157 * @dfd: the directory to use as base, or AT_FDCWD
1158 * @name: pointer to file name
1159 * @lookup_flags: lookup intent flags
1160 * @nd: pointer to nameidata
1161 * @open_flags: open intent flags
1162 */
1163 static int path_lookup_open(int dfd, const char *name,
1164 unsigned int lookup_flags, struct nameidata *nd, int open_flags)
1165 {
1166 struct file *filp = get_empty_filp();
1167 int err;
1168
1169 if (filp == NULL)
1170 return -ENFILE;
1171 nd->intent.open.file = filp;
1172 nd->intent.open.flags = open_flags;
1173 nd->intent.open.create_mode = 0;
1174 err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
1175 if (IS_ERR(nd->intent.open.file)) {
1176 if (err == 0) {
1177 err = PTR_ERR(nd->intent.open.file);
1178 path_put(&nd->path);
1179 }
1180 } else if (err != 0)
1181 release_open_intent(nd);
1182 return err;
1183 }
1184
1185 static struct dentry *__lookup_hash(struct qstr *name,
1186 struct dentry *base, struct nameidata *nd)
1187 {
1188 struct dentry *dentry;
1189 struct inode *inode;
1190 int err;
1191
1192 inode = base->d_inode;
1193
1194 /*
1195 * See if the low-level filesystem might want
1196 * to use its own hash..
1197 */
1198 if (base->d_op && base->d_op->d_hash) {
1199 err = base->d_op->d_hash(base, name);
1200 dentry = ERR_PTR(err);
1201 if (err < 0)
1202 goto out;
1203 }
1204
1205 dentry = cached_lookup(base, name, nd);
1206 if (!dentry) {
1207 struct dentry *new;
1208
1209 /* Don't create child dentry for a dead directory. */
1210 dentry = ERR_PTR(-ENOENT);
1211 if (IS_DEADDIR(inode))
1212 goto out;
1213
1214 new = d_alloc(base, name);
1215 dentry = ERR_PTR(-ENOMEM);
1216 if (!new)
1217 goto out;
1218 dentry = inode->i_op->lookup(inode, new, nd);
1219 if (!dentry)
1220 dentry = new;
1221 else
1222 dput(new);
1223 }
1224 out:
1225 return dentry;
1226 }
1227
1228 /*
1229 * Restricted form of lookup. Doesn't follow links, single-component only,
1230 * needs parent already locked. Doesn't follow mounts.
1231 * SMP-safe.
1232 */
1233 static struct dentry *lookup_hash(struct nameidata *nd)
1234 {
1235 int err;
1236
1237 err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC);
1238 if (err)
1239 return ERR_PTR(err);
1240 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1241 }
1242
1243 static int __lookup_one_len(const char *name, struct qstr *this,
1244 struct dentry *base, int len)
1245 {
1246 unsigned long hash;
1247 unsigned int c;
1248
1249 this->name = name;
1250 this->len = len;
1251 if (!len)
1252 return -EACCES;
1253
1254 hash = init_name_hash();
1255 while (len--) {
1256 c = *(const unsigned char *)name++;
1257 if (c == '/' || c == '\0')
1258 return -EACCES;
1259 hash = partial_name_hash(c, hash);
1260 }
1261 this->hash = end_name_hash(hash);
1262 return 0;
1263 }
1264
1265 /**
1266 * lookup_one_len - filesystem helper to lookup single pathname component
1267 * @name: pathname component to lookup
1268 * @base: base directory to lookup from
1269 * @len: maximum length @len should be interpreted to
1270 *
1271 * Note that this routine is purely a helper for filesystem usage and should
1272 * not be called by generic code. Also note that by using this function the
1273 * nameidata argument is passed to the filesystem methods and a filesystem
1274 * using this helper needs to be prepared for that.
1275 */
1276 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1277 {
1278 int err;
1279 struct qstr this;
1280
1281 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1282
1283 err = __lookup_one_len(name, &this, base, len);
1284 if (err)
1285 return ERR_PTR(err);
1286
1287 err = inode_permission(base->d_inode, MAY_EXEC);
1288 if (err)
1289 return ERR_PTR(err);
1290 return __lookup_hash(&this, base, NULL);
1291 }
1292
1293 /**
1294 * lookup_one_noperm - bad hack for sysfs
1295 * @name: pathname component to lookup
1296 * @base: base directory to lookup from
1297 *
1298 * This is a variant of lookup_one_len that doesn't perform any permission
1299 * checks. It's a horrible hack to work around the braindead sysfs
1300 * architecture and should not be used anywhere else.
1301 *
1302 * DON'T USE THIS FUNCTION EVER, thanks.
1303 */
1304 struct dentry *lookup_one_noperm(const char *name, struct dentry *base)
1305 {
1306 int err;
1307 struct qstr this;
1308
1309 err = __lookup_one_len(name, &this, base, strlen(name));
1310 if (err)
1311 return ERR_PTR(err);
1312 return __lookup_hash(&this, base, NULL);
1313 }
1314
1315 int user_path_at(int dfd, const char __user *name, unsigned flags,
1316 struct path *path)
1317 {
1318 struct nameidata nd;
1319 char *tmp = getname(name);
1320 int err = PTR_ERR(tmp);
1321 if (!IS_ERR(tmp)) {
1322
1323 BUG_ON(flags & LOOKUP_PARENT);
1324
1325 err = do_path_lookup(dfd, tmp, flags, &nd);
1326 putname(tmp);
1327 if (!err)
1328 *path = nd.path;
1329 }
1330 return err;
1331 }
1332
1333 static int user_path_parent(int dfd, const char __user *path,
1334 struct nameidata *nd, char **name)
1335 {
1336 char *s = getname(path);
1337 int error;
1338
1339 if (IS_ERR(s))
1340 return PTR_ERR(s);
1341
1342 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1343 if (error)
1344 putname(s);
1345 else
1346 *name = s;
1347
1348 return error;
1349 }
1350
1351 /*
1352 * It's inline, so penalty for filesystems that don't use sticky bit is
1353 * minimal.
1354 */
1355 static inline int check_sticky(struct inode *dir, struct inode *inode)
1356 {
1357 uid_t fsuid = current_fsuid();
1358
1359 if (!(dir->i_mode & S_ISVTX))
1360 return 0;
1361 if (inode->i_uid == fsuid)
1362 return 0;
1363 if (dir->i_uid == fsuid)
1364 return 0;
1365 return !capable(CAP_FOWNER);
1366 }
1367
1368 /*
1369 * Check whether we can remove a link victim from directory dir, check
1370 * whether the type of victim is right.
1371 * 1. We can't do it if dir is read-only (done in permission())
1372 * 2. We should have write and exec permissions on dir
1373 * 3. We can't remove anything from append-only dir
1374 * 4. We can't do anything with immutable dir (done in permission())
1375 * 5. If the sticky bit on dir is set we should either
1376 * a. be owner of dir, or
1377 * b. be owner of victim, or
1378 * c. have CAP_FOWNER capability
1379 * 6. If the victim is append-only or immutable we can't do antyhing with
1380 * links pointing to it.
1381 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1382 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1383 * 9. We can't remove a root or mountpoint.
1384 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1385 * nfs_async_unlink().
1386 */
1387 static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1388 {
1389 int error;
1390
1391 if (!victim->d_inode)
1392 return -ENOENT;
1393
1394 BUG_ON(victim->d_parent->d_inode != dir);
1395 audit_inode_child(victim->d_name.name, victim, dir);
1396
1397 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1398 if (error)
1399 return error;
1400 if (IS_APPEND(dir))
1401 return -EPERM;
1402 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1403 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1404 return -EPERM;
1405 if (isdir) {
1406 if (!S_ISDIR(victim->d_inode->i_mode))
1407 return -ENOTDIR;
1408 if (IS_ROOT(victim))
1409 return -EBUSY;
1410 } else if (S_ISDIR(victim->d_inode->i_mode))
1411 return -EISDIR;
1412 if (IS_DEADDIR(dir))
1413 return -ENOENT;
1414 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1415 return -EBUSY;
1416 return 0;
1417 }
1418
1419 /* Check whether we can create an object with dentry child in directory
1420 * dir.
1421 * 1. We can't do it if child already exists (open has special treatment for
1422 * this case, but since we are inlined it's OK)
1423 * 2. We can't do it if dir is read-only (done in permission())
1424 * 3. We should have write and exec permissions on dir
1425 * 4. We can't do it if dir is immutable (done in permission())
1426 */
1427 static inline int may_create(struct inode *dir, struct dentry *child)
1428 {
1429 if (child->d_inode)
1430 return -EEXIST;
1431 if (IS_DEADDIR(dir))
1432 return -ENOENT;
1433 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1434 }
1435
1436 /*
1437 * O_DIRECTORY translates into forcing a directory lookup.
1438 */
1439 static inline int lookup_flags(unsigned int f)
1440 {
1441 unsigned long retval = LOOKUP_FOLLOW;
1442
1443 if (f & O_NOFOLLOW)
1444 retval &= ~LOOKUP_FOLLOW;
1445
1446 if (f & O_DIRECTORY)
1447 retval |= LOOKUP_DIRECTORY;
1448
1449 return retval;
1450 }
1451
1452 /*
1453 * p1 and p2 should be directories on the same fs.
1454 */
1455 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1456 {
1457 struct dentry *p;
1458
1459 if (p1 == p2) {
1460 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1461 return NULL;
1462 }
1463
1464 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1465
1466 p = d_ancestor(p2, p1);
1467 if (p) {
1468 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1469 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1470 return p;
1471 }
1472
1473 p = d_ancestor(p1, p2);
1474 if (p) {
1475 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1476 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1477 return p;
1478 }
1479
1480 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1481 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1482 return NULL;
1483 }
1484
1485 void unlock_rename(struct dentry *p1, struct dentry *p2)
1486 {
1487 mutex_unlock(&p1->d_inode->i_mutex);
1488 if (p1 != p2) {
1489 mutex_unlock(&p2->d_inode->i_mutex);
1490 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1491 }
1492 }
1493
1494 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1495 struct nameidata *nd)
1496 {
1497 int error = may_create(dir, dentry);
1498
1499 if (error)
1500 return error;
1501
1502 if (!dir->i_op->create)
1503 return -EACCES; /* shouldn't it be ENOSYS? */
1504 mode &= S_IALLUGO;
1505 mode |= S_IFREG;
1506 error = security_inode_create(dir, dentry, mode);
1507 if (error)
1508 return error;
1509 vfs_dq_init(dir);
1510 error = dir->i_op->create(dir, dentry, mode, nd);
1511 if (!error)
1512 fsnotify_create(dir, dentry);
1513 return error;
1514 }
1515
1516 int may_open(struct path *path, int acc_mode, int flag)
1517 {
1518 struct dentry *dentry = path->dentry;
1519 struct inode *inode = dentry->d_inode;
1520 int error;
1521
1522 if (!inode)
1523 return -ENOENT;
1524
1525 switch (inode->i_mode & S_IFMT) {
1526 case S_IFLNK:
1527 return -ELOOP;
1528 case S_IFDIR:
1529 if (acc_mode & MAY_WRITE)
1530 return -EISDIR;
1531 break;
1532 case S_IFBLK:
1533 case S_IFCHR:
1534 if (path->mnt->mnt_flags & MNT_NODEV)
1535 return -EACCES;
1536 /*FALLTHRU*/
1537 case S_IFIFO:
1538 case S_IFSOCK:
1539 flag &= ~O_TRUNC;
1540 break;
1541 }
1542
1543 error = inode_permission(inode, acc_mode);
1544 if (error)
1545 return error;
1546
1547 error = ima_path_check(path, acc_mode ?
1548 acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
1549 ACC_MODE(flag) & (MAY_READ | MAY_WRITE),
1550 IMA_COUNT_UPDATE);
1551
1552 if (error)
1553 return error;
1554 /*
1555 * An append-only file must be opened in append mode for writing.
1556 */
1557 if (IS_APPEND(inode)) {
1558 error = -EPERM;
1559 if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1560 goto err_out;
1561 if (flag & O_TRUNC)
1562 goto err_out;
1563 }
1564
1565 /* O_NOATIME can only be set by the owner or superuser */
1566 if (flag & O_NOATIME)
1567 if (!is_owner_or_cap(inode)) {
1568 error = -EPERM;
1569 goto err_out;
1570 }
1571
1572 /*
1573 * Ensure there are no outstanding leases on the file.
1574 */
1575 error = break_lease(inode, flag);
1576 if (error)
1577 goto err_out;
1578
1579 if (flag & O_TRUNC) {
1580 error = get_write_access(inode);
1581 if (error)
1582 goto err_out;
1583
1584 /*
1585 * Refuse to truncate files with mandatory locks held on them.
1586 */
1587 error = locks_verify_locked(inode);
1588 if (!error)
1589 error = security_path_truncate(path, 0,
1590 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
1591 if (!error) {
1592 vfs_dq_init(inode);
1593
1594 error = do_truncate(dentry, 0,
1595 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
1596 NULL);
1597 }
1598 put_write_access(inode);
1599 if (error)
1600 goto err_out;
1601 } else
1602 if (flag & FMODE_WRITE)
1603 vfs_dq_init(inode);
1604
1605 return 0;
1606 err_out:
1607 ima_counts_put(path, acc_mode ?
1608 acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
1609 ACC_MODE(flag) & (MAY_READ | MAY_WRITE));
1610 return error;
1611 }
1612
1613 /*
1614 * Be careful about ever adding any more callers of this
1615 * function. Its flags must be in the namei format, not
1616 * what get passed to sys_open().
1617 */
1618 static int __open_namei_create(struct nameidata *nd, struct path *path,
1619 int flag, int mode)
1620 {
1621 int error;
1622 struct dentry *dir = nd->path.dentry;
1623
1624 if (!IS_POSIXACL(dir->d_inode))
1625 mode &= ~current_umask();
1626 error = security_path_mknod(&nd->path, path->dentry, mode, 0);
1627 if (error)
1628 goto out_unlock;
1629 error = vfs_create(dir->d_inode, path->dentry, mode, nd);
1630 out_unlock:
1631 mutex_unlock(&dir->d_inode->i_mutex);
1632 dput(nd->path.dentry);
1633 nd->path.dentry = path->dentry;
1634 if (error)
1635 return error;
1636 /* Don't check for write permission, don't truncate */
1637 return may_open(&nd->path, 0, flag & ~O_TRUNC);
1638 }
1639
1640 /*
1641 * Note that while the flag value (low two bits) for sys_open means:
1642 * 00 - read-only
1643 * 01 - write-only
1644 * 10 - read-write
1645 * 11 - special
1646 * it is changed into
1647 * 00 - no permissions needed
1648 * 01 - read-permission
1649 * 10 - write-permission
1650 * 11 - read-write
1651 * for the internal routines (ie open_namei()/follow_link() etc)
1652 * This is more logical, and also allows the 00 "no perm needed"
1653 * to be used for symlinks (where the permissions are checked
1654 * later).
1655 *
1656 */
1657 static inline int open_to_namei_flags(int flag)
1658 {
1659 if ((flag+1) & O_ACCMODE)
1660 flag++;
1661 return flag;
1662 }
1663
1664 static int open_will_write_to_fs(int flag, struct inode *inode)
1665 {
1666 /*
1667 * We'll never write to the fs underlying
1668 * a device file.
1669 */
1670 if (special_file(inode->i_mode))
1671 return 0;
1672 return (flag & O_TRUNC);
1673 }
1674
1675 /*
1676 * Note that the low bits of the passed in "open_flag"
1677 * are not the same as in the local variable "flag". See
1678 * open_to_namei_flags() for more details.
1679 */
1680 struct file *do_filp_open(int dfd, const char *pathname,
1681 int open_flag, int mode, int acc_mode)
1682 {
1683 struct file *filp;
1684 struct nameidata nd;
1685 int error;
1686 struct path path;
1687 struct dentry *dir;
1688 int count = 0;
1689 int will_write;
1690 int flag = open_to_namei_flags(open_flag);
1691
1692 if (!acc_mode)
1693 acc_mode = MAY_OPEN | ACC_MODE(flag);
1694
1695 /* O_TRUNC implies we need access checks for write permissions */
1696 if (flag & O_TRUNC)
1697 acc_mode |= MAY_WRITE;
1698
1699 /* Allow the LSM permission hook to distinguish append
1700 access from general write access. */
1701 if (flag & O_APPEND)
1702 acc_mode |= MAY_APPEND;
1703
1704 /*
1705 * The simplest case - just a plain lookup.
1706 */
1707 if (!(flag & O_CREAT)) {
1708 error = path_lookup_open(dfd, pathname, lookup_flags(flag),
1709 &nd, flag);
1710 if (error)
1711 return ERR_PTR(error);
1712 goto ok;
1713 }
1714
1715 /*
1716 * Create - we need to know the parent.
1717 */
1718 error = path_init(dfd, pathname, LOOKUP_PARENT, &nd);
1719 if (error)
1720 return ERR_PTR(error);
1721 error = path_walk(pathname, &nd);
1722 if (error) {
1723 if (nd.root.mnt)
1724 path_put(&nd.root);
1725 return ERR_PTR(error);
1726 }
1727 if (unlikely(!audit_dummy_context()))
1728 audit_inode(pathname, nd.path.dentry);
1729
1730 /*
1731 * We have the parent and last component. First of all, check
1732 * that we are not asked to creat(2) an obvious directory - that
1733 * will not do.
1734 */
1735 error = -EISDIR;
1736 if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len])
1737 goto exit_parent;
1738
1739 error = -ENFILE;
1740 filp = get_empty_filp();
1741 if (filp == NULL)
1742 goto exit_parent;
1743 nd.intent.open.file = filp;
1744 nd.intent.open.flags = flag;
1745 nd.intent.open.create_mode = mode;
1746 dir = nd.path.dentry;
1747 nd.flags &= ~LOOKUP_PARENT;
1748 nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN;
1749 if (flag & O_EXCL)
1750 nd.flags |= LOOKUP_EXCL;
1751 mutex_lock(&dir->d_inode->i_mutex);
1752 path.dentry = lookup_hash(&nd);
1753 path.mnt = nd.path.mnt;
1754
1755 do_last:
1756 error = PTR_ERR(path.dentry);
1757 if (IS_ERR(path.dentry)) {
1758 mutex_unlock(&dir->d_inode->i_mutex);
1759 goto exit;
1760 }
1761
1762 if (IS_ERR(nd.intent.open.file)) {
1763 error = PTR_ERR(nd.intent.open.file);
1764 goto exit_mutex_unlock;
1765 }
1766
1767 /* Negative dentry, just create the file */
1768 if (!path.dentry->d_inode) {
1769 /*
1770 * This write is needed to ensure that a
1771 * ro->rw transition does not occur between
1772 * the time when the file is created and when
1773 * a permanent write count is taken through
1774 * the 'struct file' in nameidata_to_filp().
1775 */
1776 error = mnt_want_write(nd.path.mnt);
1777 if (error)
1778 goto exit_mutex_unlock;
1779 error = __open_namei_create(&nd, &path, flag, mode);
1780 if (error) {
1781 mnt_drop_write(nd.path.mnt);
1782 goto exit;
1783 }
1784 filp = nameidata_to_filp(&nd, open_flag);
1785 if (IS_ERR(filp))
1786 ima_counts_put(&nd.path,
1787 acc_mode & (MAY_READ | MAY_WRITE |
1788 MAY_EXEC));
1789 mnt_drop_write(nd.path.mnt);
1790 if (nd.root.mnt)
1791 path_put(&nd.root);
1792 return filp;
1793 }
1794
1795 /*
1796 * It already exists.
1797 */
1798 mutex_unlock(&dir->d_inode->i_mutex);
1799 audit_inode(pathname, path.dentry);
1800
1801 error = -EEXIST;
1802 if (flag & O_EXCL)
1803 goto exit_dput;
1804
1805 if (__follow_mount(&path)) {
1806 error = -ELOOP;
1807 if (flag & O_NOFOLLOW)
1808 goto exit_dput;
1809 }
1810
1811 error = -ENOENT;
1812 if (!path.dentry->d_inode)
1813 goto exit_dput;
1814 if (path.dentry->d_inode->i_op->follow_link)
1815 goto do_link;
1816
1817 path_to_nameidata(&path, &nd);
1818 error = -EISDIR;
1819 if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
1820 goto exit;
1821 ok:
1822 /*
1823 * Consider:
1824 * 1. may_open() truncates a file
1825 * 2. a rw->ro mount transition occurs
1826 * 3. nameidata_to_filp() fails due to
1827 * the ro mount.
1828 * That would be inconsistent, and should
1829 * be avoided. Taking this mnt write here
1830 * ensures that (2) can not occur.
1831 */
1832 will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode);
1833 if (will_write) {
1834 error = mnt_want_write(nd.path.mnt);
1835 if (error)
1836 goto exit;
1837 }
1838 error = may_open(&nd.path, acc_mode, flag);
1839 if (error) {
1840 if (will_write)
1841 mnt_drop_write(nd.path.mnt);
1842 goto exit;
1843 }
1844 filp = nameidata_to_filp(&nd, open_flag);
1845 if (IS_ERR(filp))
1846 ima_counts_put(&nd.path,
1847 acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC));
1848 /*
1849 * It is now safe to drop the mnt write
1850 * because the filp has had a write taken
1851 * on its behalf.
1852 */
1853 if (will_write)
1854 mnt_drop_write(nd.path.mnt);
1855 if (nd.root.mnt)
1856 path_put(&nd.root);
1857 return filp;
1858
1859 exit_mutex_unlock:
1860 mutex_unlock(&dir->d_inode->i_mutex);
1861 exit_dput:
1862 path_put_conditional(&path, &nd);
1863 exit:
1864 if (!IS_ERR(nd.intent.open.file))
1865 release_open_intent(&nd);
1866 exit_parent:
1867 if (nd.root.mnt)
1868 path_put(&nd.root);
1869 path_put(&nd.path);
1870 return ERR_PTR(error);
1871
1872 do_link:
1873 error = -ELOOP;
1874 if (flag & O_NOFOLLOW)
1875 goto exit_dput;
1876 /*
1877 * This is subtle. Instead of calling do_follow_link() we do the
1878 * thing by hands. The reason is that this way we have zero link_count
1879 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1880 * After that we have the parent and last component, i.e.
1881 * we are in the same situation as after the first path_walk().
1882 * Well, almost - if the last component is normal we get its copy
1883 * stored in nd->last.name and we will have to putname() it when we
1884 * are done. Procfs-like symlinks just set LAST_BIND.
1885 */
1886 nd.flags |= LOOKUP_PARENT;
1887 error = security_inode_follow_link(path.dentry, &nd);
1888 if (error)
1889 goto exit_dput;
1890 error = __do_follow_link(&path, &nd);
1891 if (error) {
1892 /* Does someone understand code flow here? Or it is only
1893 * me so stupid? Anathema to whoever designed this non-sense
1894 * with "intent.open".
1895 */
1896 release_open_intent(&nd);
1897 if (nd.root.mnt)
1898 path_put(&nd.root);
1899 return ERR_PTR(error);
1900 }
1901 nd.flags &= ~LOOKUP_PARENT;
1902 if (nd.last_type == LAST_BIND)
1903 goto ok;
1904 error = -EISDIR;
1905 if (nd.last_type != LAST_NORM)
1906 goto exit;
1907 if (nd.last.name[nd.last.len]) {
1908 __putname(nd.last.name);
1909 goto exit;
1910 }
1911 error = -ELOOP;
1912 if (count++==32) {
1913 __putname(nd.last.name);
1914 goto exit;
1915 }
1916 dir = nd.path.dentry;
1917 mutex_lock(&dir->d_inode->i_mutex);
1918 path.dentry = lookup_hash(&nd);
1919 path.mnt = nd.path.mnt;
1920 __putname(nd.last.name);
1921 goto do_last;
1922 }
1923
1924 /**
1925 * filp_open - open file and return file pointer
1926 *
1927 * @filename: path to open
1928 * @flags: open flags as per the open(2) second argument
1929 * @mode: mode for the new file if O_CREAT is set, else ignored
1930 *
1931 * This is the helper to open a file from kernelspace if you really
1932 * have to. But in generally you should not do this, so please move
1933 * along, nothing to see here..
1934 */
1935 struct file *filp_open(const char *filename, int flags, int mode)
1936 {
1937 return do_filp_open(AT_FDCWD, filename, flags, mode, 0);
1938 }
1939 EXPORT_SYMBOL(filp_open);
1940
1941 /**
1942 * lookup_create - lookup a dentry, creating it if it doesn't exist
1943 * @nd: nameidata info
1944 * @is_dir: directory flag
1945 *
1946 * Simple function to lookup and return a dentry and create it
1947 * if it doesn't exist. Is SMP-safe.
1948 *
1949 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1950 */
1951 struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1952 {
1953 struct dentry *dentry = ERR_PTR(-EEXIST);
1954
1955 mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
1956 /*
1957 * Yucky last component or no last component at all?
1958 * (foo/., foo/.., /////)
1959 */
1960 if (nd->last_type != LAST_NORM)
1961 goto fail;
1962 nd->flags &= ~LOOKUP_PARENT;
1963 nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
1964 nd->intent.open.flags = O_EXCL;
1965
1966 /*
1967 * Do the final lookup.
1968 */
1969 dentry = lookup_hash(nd);
1970 if (IS_ERR(dentry))
1971 goto fail;
1972
1973 if (dentry->d_inode)
1974 goto eexist;
1975 /*
1976 * Special case - lookup gave negative, but... we had foo/bar/
1977 * From the vfs_mknod() POV we just have a negative dentry -
1978 * all is fine. Let's be bastards - you had / on the end, you've
1979 * been asking for (non-existent) directory. -ENOENT for you.
1980 */
1981 if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
1982 dput(dentry);
1983 dentry = ERR_PTR(-ENOENT);
1984 }
1985 return dentry;
1986 eexist:
1987 dput(dentry);
1988 dentry = ERR_PTR(-EEXIST);
1989 fail:
1990 return dentry;
1991 }
1992 EXPORT_SYMBOL_GPL(lookup_create);
1993
1994 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1995 {
1996 int error = may_create(dir, dentry);
1997
1998 if (error)
1999 return error;
2000
2001 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
2002 return -EPERM;
2003
2004 if (!dir->i_op->mknod)
2005 return -EPERM;
2006
2007 error = devcgroup_inode_mknod(mode, dev);
2008 if (error)
2009 return error;
2010
2011 error = security_inode_mknod(dir, dentry, mode, dev);
2012 if (error)
2013 return error;
2014
2015 vfs_dq_init(dir);
2016 error = dir->i_op->mknod(dir, dentry, mode, dev);
2017 if (!error)
2018 fsnotify_create(dir, dentry);
2019 return error;
2020 }
2021
2022 static int may_mknod(mode_t mode)
2023 {
2024 switch (mode & S_IFMT) {
2025 case S_IFREG:
2026 case S_IFCHR:
2027 case S_IFBLK:
2028 case S_IFIFO:
2029 case S_IFSOCK:
2030 case 0: /* zero mode translates to S_IFREG */
2031 return 0;
2032 case S_IFDIR:
2033 return -EPERM;
2034 default:
2035 return -EINVAL;
2036 }
2037 }
2038
2039 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
2040 unsigned, dev)
2041 {
2042 int error;
2043 char *tmp;
2044 struct dentry *dentry;
2045 struct nameidata nd;
2046
2047 if (S_ISDIR(mode))
2048 return -EPERM;
2049
2050 error = user_path_parent(dfd, filename, &nd, &tmp);
2051 if (error)
2052 return error;
2053
2054 dentry = lookup_create(&nd, 0);
2055 if (IS_ERR(dentry)) {
2056 error = PTR_ERR(dentry);
2057 goto out_unlock;
2058 }
2059 if (!IS_POSIXACL(nd.path.dentry->d_inode))
2060 mode &= ~current_umask();
2061 error = may_mknod(mode);
2062 if (error)
2063 goto out_dput;
2064 error = mnt_want_write(nd.path.mnt);
2065 if (error)
2066 goto out_dput;
2067 error = security_path_mknod(&nd.path, dentry, mode, dev);
2068 if (error)
2069 goto out_drop_write;
2070 switch (mode & S_IFMT) {
2071 case 0: case S_IFREG:
2072 error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
2073 break;
2074 case S_IFCHR: case S_IFBLK:
2075 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
2076 new_decode_dev(dev));
2077 break;
2078 case S_IFIFO: case S_IFSOCK:
2079 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
2080 break;
2081 }
2082 out_drop_write:
2083 mnt_drop_write(nd.path.mnt);
2084 out_dput:
2085 dput(dentry);
2086 out_unlock:
2087 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2088 path_put(&nd.path);
2089 putname(tmp);
2090
2091 return error;
2092 }
2093
2094 SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
2095 {
2096 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2097 }
2098
2099 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2100 {
2101 int error = may_create(dir, dentry);
2102
2103 if (error)
2104 return error;
2105
2106 if (!dir->i_op->mkdir)
2107 return -EPERM;
2108
2109 mode &= (S_IRWXUGO|S_ISVTX);
2110 error = security_inode_mkdir(dir, dentry, mode);
2111 if (error)
2112 return error;
2113
2114 vfs_dq_init(dir);
2115 error = dir->i_op->mkdir(dir, dentry, mode);
2116 if (!error)
2117 fsnotify_mkdir(dir, dentry);
2118 return error;
2119 }
2120
2121 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
2122 {
2123 int error = 0;
2124 char * tmp;
2125 struct dentry *dentry;
2126 struct nameidata nd;
2127
2128 error = user_path_parent(dfd, pathname, &nd, &tmp);
2129 if (error)
2130 goto out_err;
2131
2132 dentry = lookup_create(&nd, 1);
2133 error = PTR_ERR(dentry);
2134 if (IS_ERR(dentry))
2135 goto out_unlock;
2136
2137 if (!IS_POSIXACL(nd.path.dentry->d_inode))
2138 mode &= ~current_umask();
2139 error = mnt_want_write(nd.path.mnt);
2140 if (error)
2141 goto out_dput;
2142 error = security_path_mkdir(&nd.path, dentry, mode);
2143 if (error)
2144 goto out_drop_write;
2145 error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
2146 out_drop_write:
2147 mnt_drop_write(nd.path.mnt);
2148 out_dput:
2149 dput(dentry);
2150 out_unlock:
2151 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2152 path_put(&nd.path);
2153 putname(tmp);
2154 out_err:
2155 return error;
2156 }
2157
2158 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
2159 {
2160 return sys_mkdirat(AT_FDCWD, pathname, mode);
2161 }
2162
2163 /*
2164 * We try to drop the dentry early: we should have
2165 * a usage count of 2 if we're the only user of this
2166 * dentry, and if that is true (possibly after pruning
2167 * the dcache), then we drop the dentry now.
2168 *
2169 * A low-level filesystem can, if it choses, legally
2170 * do a
2171 *
2172 * if (!d_unhashed(dentry))
2173 * return -EBUSY;
2174 *
2175 * if it cannot handle the case of removing a directory
2176 * that is still in use by something else..
2177 */
2178 void dentry_unhash(struct dentry *dentry)
2179 {
2180 dget(dentry);
2181 shrink_dcache_parent(dentry);
2182 spin_lock(&dcache_lock);
2183 spin_lock(&dentry->d_lock);
2184 if (atomic_read(&dentry->d_count) == 2)
2185 __d_drop(dentry);
2186 spin_unlock(&dentry->d_lock);
2187 spin_unlock(&dcache_lock);
2188 }
2189
2190 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2191 {
2192 int error = may_delete(dir, dentry, 1);
2193
2194 if (error)
2195 return error;
2196
2197 if (!dir->i_op->rmdir)
2198 return -EPERM;
2199
2200 vfs_dq_init(dir);
2201
2202 mutex_lock(&dentry->d_inode->i_mutex);
2203 dentry_unhash(dentry);
2204 if (d_mountpoint(dentry))
2205 error = -EBUSY;
2206 else {
2207 error = security_inode_rmdir(dir, dentry);
2208 if (!error) {
2209 error = dir->i_op->rmdir(dir, dentry);
2210 if (!error)
2211 dentry->d_inode->i_flags |= S_DEAD;
2212 }
2213 }
2214 mutex_unlock(&dentry->d_inode->i_mutex);
2215 if (!error) {
2216 d_delete(dentry);
2217 }
2218 dput(dentry);
2219
2220 return error;
2221 }
2222
2223 static long do_rmdir(int dfd, const char __user *pathname)
2224 {
2225 int error = 0;
2226 char * name;
2227 struct dentry *dentry;
2228 struct nameidata nd;
2229
2230 error = user_path_parent(dfd, pathname, &nd, &name);
2231 if (error)
2232 return error;
2233
2234 switch(nd.last_type) {
2235 case LAST_DOTDOT:
2236 error = -ENOTEMPTY;
2237 goto exit1;
2238 case LAST_DOT:
2239 error = -EINVAL;
2240 goto exit1;
2241 case LAST_ROOT:
2242 error = -EBUSY;
2243 goto exit1;
2244 }
2245
2246 nd.flags &= ~LOOKUP_PARENT;
2247
2248 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2249 dentry = lookup_hash(&nd);
2250 error = PTR_ERR(dentry);
2251 if (IS_ERR(dentry))
2252 goto exit2;
2253 error = mnt_want_write(nd.path.mnt);
2254 if (error)
2255 goto exit3;
2256 error = security_path_rmdir(&nd.path, dentry);
2257 if (error)
2258 goto exit4;
2259 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
2260 exit4:
2261 mnt_drop_write(nd.path.mnt);
2262 exit3:
2263 dput(dentry);
2264 exit2:
2265 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2266 exit1:
2267 path_put(&nd.path);
2268 putname(name);
2269 return error;
2270 }
2271
2272 SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
2273 {
2274 return do_rmdir(AT_FDCWD, pathname);
2275 }
2276
2277 int vfs_unlink(struct inode *dir, struct dentry *dentry)
2278 {
2279 int error = may_delete(dir, dentry, 0);
2280
2281 if (error)
2282 return error;
2283
2284 if (!dir->i_op->unlink)
2285 return -EPERM;
2286
2287 vfs_dq_init(dir);
2288
2289 mutex_lock(&dentry->d_inode->i_mutex);
2290 if (d_mountpoint(dentry))
2291 error = -EBUSY;
2292 else {
2293 error = security_inode_unlink(dir, dentry);
2294 if (!error)
2295 error = dir->i_op->unlink(dir, dentry);
2296 }
2297 mutex_unlock(&dentry->d_inode->i_mutex);
2298
2299 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2300 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2301 fsnotify_link_count(dentry->d_inode);
2302 d_delete(dentry);
2303 }
2304
2305 return error;
2306 }
2307
2308 /*
2309 * Make sure that the actual truncation of the file will occur outside its
2310 * directory's i_mutex. Truncate can take a long time if there is a lot of
2311 * writeout happening, and we don't want to prevent access to the directory
2312 * while waiting on the I/O.
2313 */
2314 static long do_unlinkat(int dfd, const char __user *pathname)
2315 {
2316 int error;
2317 char *name;
2318 struct dentry *dentry;
2319 struct nameidata nd;
2320 struct inode *inode = NULL;
2321
2322 error = user_path_parent(dfd, pathname, &nd, &name);
2323 if (error)
2324 return error;
2325
2326 error = -EISDIR;
2327 if (nd.last_type != LAST_NORM)
2328 goto exit1;
2329
2330 nd.flags &= ~LOOKUP_PARENT;
2331
2332 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2333 dentry = lookup_hash(&nd);
2334 error = PTR_ERR(dentry);
2335 if (!IS_ERR(dentry)) {
2336 /* Why not before? Because we want correct error value */
2337 if (nd.last.name[nd.last.len])
2338 goto slashes;
2339 inode = dentry->d_inode;
2340 if (inode)
2341 atomic_inc(&inode->i_count);
2342 error = mnt_want_write(nd.path.mnt);
2343 if (error)
2344 goto exit2;
2345 error = security_path_unlink(&nd.path, dentry);
2346 if (error)
2347 goto exit3;
2348 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
2349 exit3:
2350 mnt_drop_write(nd.path.mnt);
2351 exit2:
2352 dput(dentry);
2353 }
2354 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2355 if (inode)
2356 iput(inode); /* truncate the inode here */
2357 exit1:
2358 path_put(&nd.path);
2359 putname(name);
2360 return error;
2361
2362 slashes:
2363 error = !dentry->d_inode ? -ENOENT :
2364 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2365 goto exit2;
2366 }
2367
2368 SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
2369 {
2370 if ((flag & ~AT_REMOVEDIR) != 0)
2371 return -EINVAL;
2372
2373 if (flag & AT_REMOVEDIR)
2374 return do_rmdir(dfd, pathname);
2375
2376 return do_unlinkat(dfd, pathname);
2377 }
2378
2379 SYSCALL_DEFINE1(unlink, const char __user *, pathname)
2380 {
2381 return do_unlinkat(AT_FDCWD, pathname);
2382 }
2383
2384 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
2385 {
2386 int error = may_create(dir, dentry);
2387
2388 if (error)
2389 return error;
2390
2391 if (!dir->i_op->symlink)
2392 return -EPERM;
2393
2394 error = security_inode_symlink(dir, dentry, oldname);
2395 if (error)
2396 return error;
2397
2398 vfs_dq_init(dir);
2399 error = dir->i_op->symlink(dir, dentry, oldname);
2400 if (!error)
2401 fsnotify_create(dir, dentry);
2402 return error;
2403 }
2404
2405 SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2406 int, newdfd, const char __user *, newname)
2407 {
2408 int error;
2409 char *from;
2410 char *to;
2411 struct dentry *dentry;
2412 struct nameidata nd;
2413
2414 from = getname(oldname);
2415 if (IS_ERR(from))
2416 return PTR_ERR(from);
2417
2418 error = user_path_parent(newdfd, newname, &nd, &to);
2419 if (error)
2420 goto out_putname;
2421
2422 dentry = lookup_create(&nd, 0);
2423 error = PTR_ERR(dentry);
2424 if (IS_ERR(dentry))
2425 goto out_unlock;
2426
2427 error = mnt_want_write(nd.path.mnt);
2428 if (error)
2429 goto out_dput;
2430 error = security_path_symlink(&nd.path, dentry, from);
2431 if (error)
2432 goto out_drop_write;
2433 error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
2434 out_drop_write:
2435 mnt_drop_write(nd.path.mnt);
2436 out_dput:
2437 dput(dentry);
2438 out_unlock:
2439 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2440 path_put(&nd.path);
2441 putname(to);
2442 out_putname:
2443 putname(from);
2444 return error;
2445 }
2446
2447 SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
2448 {
2449 return sys_symlinkat(oldname, AT_FDCWD, newname);
2450 }
2451
2452 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2453 {
2454 struct inode *inode = old_dentry->d_inode;
2455 int error;
2456
2457 if (!inode)
2458 return -ENOENT;
2459
2460 error = may_create(dir, new_dentry);
2461 if (error)
2462 return error;
2463
2464 if (dir->i_sb != inode->i_sb)
2465 return -EXDEV;
2466
2467 /*
2468 * A link to an append-only or immutable file cannot be created.
2469 */
2470 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2471 return -EPERM;
2472 if (!dir->i_op->link)
2473 return -EPERM;
2474 if (S_ISDIR(inode->i_mode))
2475 return -EPERM;
2476
2477 error = security_inode_link(old_dentry, dir, new_dentry);
2478 if (error)
2479 return error;
2480
2481 mutex_lock(&inode->i_mutex);
2482 vfs_dq_init(dir);
2483 error = dir->i_op->link(old_dentry, dir, new_dentry);
2484 mutex_unlock(&inode->i_mutex);
2485 if (!error)
2486 fsnotify_link(dir, inode, new_dentry);
2487 return error;
2488 }
2489
2490 /*
2491 * Hardlinks are often used in delicate situations. We avoid
2492 * security-related surprises by not following symlinks on the
2493 * newname. --KAB
2494 *
2495 * We don't follow them on the oldname either to be compatible
2496 * with linux 2.0, and to avoid hard-linking to directories
2497 * and other special files. --ADM
2498 */
2499 SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2500 int, newdfd, const char __user *, newname, int, flags)
2501 {
2502 struct dentry *new_dentry;
2503 struct nameidata nd;
2504 struct path old_path;
2505 int error;
2506 char *to;
2507
2508 if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
2509 return -EINVAL;
2510
2511 error = user_path_at(olddfd, oldname,
2512 flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
2513 &old_path);
2514 if (error)
2515 return error;
2516
2517 error = user_path_parent(newdfd, newname, &nd, &to);
2518 if (error)
2519 goto out;
2520 error = -EXDEV;
2521 if (old_path.mnt != nd.path.mnt)
2522 goto out_release;
2523 new_dentry = lookup_create(&nd, 0);
2524 error = PTR_ERR(new_dentry);
2525 if (IS_ERR(new_dentry))
2526 goto out_unlock;
2527 error = mnt_want_write(nd.path.mnt);
2528 if (error)
2529 goto out_dput;
2530 error = security_path_link(old_path.dentry, &nd.path, new_dentry);
2531 if (error)
2532 goto out_drop_write;
2533 error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
2534 out_drop_write:
2535 mnt_drop_write(nd.path.mnt);
2536 out_dput:
2537 dput(new_dentry);
2538 out_unlock:
2539 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2540 out_release:
2541 path_put(&nd.path);
2542 putname(to);
2543 out:
2544 path_put(&old_path);
2545
2546 return error;
2547 }
2548
2549 SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
2550 {
2551 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2552 }
2553
2554 /*
2555 * The worst of all namespace operations - renaming directory. "Perverted"
2556 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2557 * Problems:
2558 * a) we can get into loop creation. Check is done in is_subdir().
2559 * b) race potential - two innocent renames can create a loop together.
2560 * That's where 4.4 screws up. Current fix: serialization on
2561 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2562 * story.
2563 * c) we have to lock _three_ objects - parents and victim (if it exists).
2564 * And that - after we got ->i_mutex on parents (until then we don't know
2565 * whether the target exists). Solution: try to be smart with locking
2566 * order for inodes. We rely on the fact that tree topology may change
2567 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2568 * move will be locked. Thus we can rank directories by the tree
2569 * (ancestors first) and rank all non-directories after them.
2570 * That works since everybody except rename does "lock parent, lookup,
2571 * lock child" and rename is under ->s_vfs_rename_mutex.
2572 * HOWEVER, it relies on the assumption that any object with ->lookup()
2573 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2574 * we'd better make sure that there's no link(2) for them.
2575 * d) some filesystems don't support opened-but-unlinked directories,
2576 * either because of layout or because they are not ready to deal with
2577 * all cases correctly. The latter will be fixed (taking this sort of
2578 * stuff into VFS), but the former is not going away. Solution: the same
2579 * trick as in rmdir().
2580 * e) conversion from fhandle to dentry may come in the wrong moment - when
2581 * we are removing the target. Solution: we will have to grab ->i_mutex
2582 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2583 * ->i_mutex on parents, which works but leads to some truely excessive
2584 * locking].
2585 */
2586 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2587 struct inode *new_dir, struct dentry *new_dentry)
2588 {
2589 int error = 0;
2590 struct inode *target;
2591
2592 /*
2593 * If we are going to change the parent - check write permissions,
2594 * we'll need to flip '..'.
2595 */
2596 if (new_dir != old_dir) {
2597 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
2598 if (error)
2599 return error;
2600 }
2601
2602 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2603 if (error)
2604 return error;
2605
2606 target = new_dentry->d_inode;
2607 if (target) {
2608 mutex_lock(&target->i_mutex);
2609 dentry_unhash(new_dentry);
2610 }
2611 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2612 error = -EBUSY;
2613 else
2614 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2615 if (target) {
2616 if (!error)
2617 target->i_flags |= S_DEAD;
2618 mutex_unlock(&target->i_mutex);
2619 if (d_unhashed(new_dentry))
2620 d_rehash(new_dentry);
2621 dput(new_dentry);
2622 }
2623 if (!error)
2624 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2625 d_move(old_dentry,new_dentry);
2626 return error;
2627 }
2628
2629 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2630 struct inode *new_dir, struct dentry *new_dentry)
2631 {
2632 struct inode *target;
2633 int error;
2634
2635 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2636 if (error)
2637 return error;
2638
2639 dget(new_dentry);
2640 target = new_dentry->d_inode;
2641 if (target)
2642 mutex_lock(&target->i_mutex);
2643 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2644 error = -EBUSY;
2645 else
2646 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2647 if (!error) {
2648 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2649 d_move(old_dentry, new_dentry);
2650 }
2651 if (target)
2652 mutex_unlock(&target->i_mutex);
2653 dput(new_dentry);
2654 return error;
2655 }
2656
2657 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2658 struct inode *new_dir, struct dentry *new_dentry)
2659 {
2660 int error;
2661 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2662 const char *old_name;
2663
2664 if (old_dentry->d_inode == new_dentry->d_inode)
2665 return 0;
2666
2667 error = may_delete(old_dir, old_dentry, is_dir);
2668 if (error)
2669 return error;
2670
2671 if (!new_dentry->d_inode)
2672 error = may_create(new_dir, new_dentry);
2673 else
2674 error = may_delete(new_dir, new_dentry, is_dir);
2675 if (error)
2676 return error;
2677
2678 if (!old_dir->i_op->rename)
2679 return -EPERM;
2680
2681 vfs_dq_init(old_dir);
2682 vfs_dq_init(new_dir);
2683
2684 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
2685
2686 if (is_dir)
2687 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2688 else
2689 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2690 if (!error) {
2691 const char *new_name = old_dentry->d_name.name;
2692 fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
2693 new_dentry->d_inode, old_dentry);
2694 }
2695 fsnotify_oldname_free(old_name);
2696
2697 return error;
2698 }
2699
2700 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
2701 int, newdfd, const char __user *, newname)
2702 {
2703 struct dentry *old_dir, *new_dir;
2704 struct dentry *old_dentry, *new_dentry;
2705 struct dentry *trap;
2706 struct nameidata oldnd, newnd;
2707 char *from;
2708 char *to;
2709 int error;
2710
2711 error = user_path_parent(olddfd, oldname, &oldnd, &from);
2712 if (error)
2713 goto exit;
2714
2715 error = user_path_parent(newdfd, newname, &newnd, &to);
2716 if (error)
2717 goto exit1;
2718
2719 error = -EXDEV;
2720 if (oldnd.path.mnt != newnd.path.mnt)
2721 goto exit2;
2722
2723 old_dir = oldnd.path.dentry;
2724 error = -EBUSY;
2725 if (oldnd.last_type != LAST_NORM)
2726 goto exit2;
2727
2728 new_dir = newnd.path.dentry;
2729 if (newnd.last_type != LAST_NORM)
2730 goto exit2;
2731
2732 oldnd.flags &= ~LOOKUP_PARENT;
2733 newnd.flags &= ~LOOKUP_PARENT;
2734 newnd.flags |= LOOKUP_RENAME_TARGET;
2735
2736 trap = lock_rename(new_dir, old_dir);
2737
2738 old_dentry = lookup_hash(&oldnd);
2739 error = PTR_ERR(old_dentry);
2740 if (IS_ERR(old_dentry))
2741 goto exit3;
2742 /* source must exist */
2743 error = -ENOENT;
2744 if (!old_dentry->d_inode)
2745 goto exit4;
2746 /* unless the source is a directory trailing slashes give -ENOTDIR */
2747 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2748 error = -ENOTDIR;
2749 if (oldnd.last.name[oldnd.last.len])
2750 goto exit4;
2751 if (newnd.last.name[newnd.last.len])
2752 goto exit4;
2753 }
2754 /* source should not be ancestor of target */
2755 error = -EINVAL;
2756 if (old_dentry == trap)
2757 goto exit4;
2758 new_dentry = lookup_hash(&newnd);
2759 error = PTR_ERR(new_dentry);
2760 if (IS_ERR(new_dentry))
2761 goto exit4;
2762 /* target should not be an ancestor of source */
2763 error = -ENOTEMPTY;
2764 if (new_dentry == trap)
2765 goto exit5;
2766
2767 error = mnt_want_write(oldnd.path.mnt);
2768 if (error)
2769 goto exit5;
2770 error = security_path_rename(&oldnd.path, old_dentry,
2771 &newnd.path, new_dentry);
2772 if (error)
2773 goto exit6;
2774 error = vfs_rename(old_dir->d_inode, old_dentry,
2775 new_dir->d_inode, new_dentry);
2776 exit6:
2777 mnt_drop_write(oldnd.path.mnt);
2778 exit5:
2779 dput(new_dentry);
2780 exit4:
2781 dput(old_dentry);
2782 exit3:
2783 unlock_rename(new_dir, old_dir);
2784 exit2:
2785 path_put(&newnd.path);
2786 putname(to);
2787 exit1:
2788 path_put(&oldnd.path);
2789 putname(from);
2790 exit:
2791 return error;
2792 }
2793
2794 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
2795 {
2796 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
2797 }
2798
2799 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2800 {
2801 int len;
2802
2803 len = PTR_ERR(link);
2804 if (IS_ERR(link))
2805 goto out;
2806
2807 len = strlen(link);
2808 if (len > (unsigned) buflen)
2809 len = buflen;
2810 if (copy_to_user(buffer, link, len))
2811 len = -EFAULT;
2812 out:
2813 return len;
2814 }
2815
2816 /*
2817 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2818 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2819 * using) it for any given inode is up to filesystem.
2820 */
2821 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2822 {
2823 struct nameidata nd;
2824 void *cookie;
2825 int res;
2826
2827 nd.depth = 0;
2828 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
2829 if (IS_ERR(cookie))
2830 return PTR_ERR(cookie);
2831
2832 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2833 if (dentry->d_inode->i_op->put_link)
2834 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
2835 return res;
2836 }
2837
2838 int vfs_follow_link(struct nameidata *nd, const char *link)
2839 {
2840 return __vfs_follow_link(nd, link);
2841 }
2842
2843 /* get the link contents into pagecache */
2844 static char *page_getlink(struct dentry * dentry, struct page **ppage)
2845 {
2846 char *kaddr;
2847 struct page *page;
2848 struct address_space *mapping = dentry->d_inode->i_mapping;
2849 page = read_mapping_page(mapping, 0, NULL);
2850 if (IS_ERR(page))
2851 return (char*)page;
2852 *ppage = page;
2853 kaddr = kmap(page);
2854 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
2855 return kaddr;
2856 }
2857
2858 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2859 {
2860 struct page *page = NULL;
2861 char *s = page_getlink(dentry, &page);
2862 int res = vfs_readlink(dentry,buffer,buflen,s);
2863 if (page) {
2864 kunmap(page);
2865 page_cache_release(page);
2866 }
2867 return res;
2868 }
2869
2870 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
2871 {
2872 struct page *page = NULL;
2873 nd_set_link(nd, page_getlink(dentry, &page));
2874 return page;
2875 }
2876
2877 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2878 {
2879 struct page *page = cookie;
2880
2881 if (page) {
2882 kunmap(page);
2883 page_cache_release(page);
2884 }
2885 }
2886
2887 /*
2888 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
2889 */
2890 int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
2891 {
2892 struct address_space *mapping = inode->i_mapping;
2893 struct page *page;
2894 void *fsdata;
2895 int err;
2896 char *kaddr;
2897 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
2898 if (nofs)
2899 flags |= AOP_FLAG_NOFS;
2900
2901 retry:
2902 err = pagecache_write_begin(NULL, mapping, 0, len-1,
2903 flags, &page, &fsdata);
2904 if (err)
2905 goto fail;
2906
2907 kaddr = kmap_atomic(page, KM_USER0);
2908 memcpy(kaddr, symname, len-1);
2909 kunmap_atomic(kaddr, KM_USER0);
2910
2911 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
2912 page, fsdata);
2913 if (err < 0)
2914 goto fail;
2915 if (err < len-1)
2916 goto retry;
2917
2918 mark_inode_dirty(inode);
2919 return 0;
2920 fail:
2921 return err;
2922 }
2923
2924 int page_symlink(struct inode *inode, const char *symname, int len)
2925 {
2926 return __page_symlink(inode, symname, len,
2927 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
2928 }
2929
2930 const struct inode_operations page_symlink_inode_operations = {
2931 .readlink = generic_readlink,
2932 .follow_link = page_follow_link_light,
2933 .put_link = page_put_link,
2934 };
2935
2936 EXPORT_SYMBOL(user_path_at);
2937 EXPORT_SYMBOL(follow_down);
2938 EXPORT_SYMBOL(follow_up);
2939 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2940 EXPORT_SYMBOL(getname);
2941 EXPORT_SYMBOL(lock_rename);
2942 EXPORT_SYMBOL(lookup_one_len);
2943 EXPORT_SYMBOL(page_follow_link_light);
2944 EXPORT_SYMBOL(page_put_link);
2945 EXPORT_SYMBOL(page_readlink);
2946 EXPORT_SYMBOL(__page_symlink);
2947 EXPORT_SYMBOL(page_symlink);
2948 EXPORT_SYMBOL(page_symlink_inode_operations);
2949 EXPORT_SYMBOL(path_lookup);
2950 EXPORT_SYMBOL(kern_path);
2951 EXPORT_SYMBOL(vfs_path_lookup);
2952 EXPORT_SYMBOL(inode_permission);
2953 EXPORT_SYMBOL(file_permission);
2954 EXPORT_SYMBOL(unlock_rename);
2955 EXPORT_SYMBOL(vfs_create);
2956 EXPORT_SYMBOL(vfs_follow_link);
2957 EXPORT_SYMBOL(vfs_link);
2958 EXPORT_SYMBOL(vfs_mkdir);
2959 EXPORT_SYMBOL(vfs_mknod);
2960 EXPORT_SYMBOL(generic_permission);
2961 EXPORT_SYMBOL(vfs_readlink);
2962 EXPORT_SYMBOL(vfs_rename);
2963 EXPORT_SYMBOL(vfs_rmdir);
2964 EXPORT_SYMBOL(vfs_symlink);
2965 EXPORT_SYMBOL(vfs_unlink);
2966 EXPORT_SYMBOL(dentry_unhash);
2967 EXPORT_SYMBOL(generic_readlink);
2968
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