blob: 2892e68d3a8647981e5aa7caf3c53e708584d4bf [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Robert Love0eeca282005-07-12 17:06:03 -040024#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#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>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080031#include <linux/capability.h>
Trond Myklebust834f2a42005-10-18 14:20:16 -070032#include <linux/file.h>
Ulrich Drepper5590ff02006-01-18 17:43:53 -080033#include <linux/fcntl.h>
34#include <linux/namei.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <asm/namei.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)
Arjan van de Vena11f3a02006-03-23 03:00:33 -0800107 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 * any extra contention...
109 */
110
111/* In order to reduce some races, while at the same time doing additional
112 * checking and hopefully speeding things up, we copy filenames to the
113 * kernel data space before using them..
114 *
115 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
116 * PATH_MAX includes the nul terminator --RR.
117 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800118static int do_getname(const char __user *filename, char *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119{
120 int retval;
121 unsigned long len = PATH_MAX;
122
123 if (!segment_eq(get_fs(), KERNEL_DS)) {
124 if ((unsigned long) filename >= TASK_SIZE)
125 return -EFAULT;
126 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
127 len = TASK_SIZE - (unsigned long) filename;
128 }
129
130 retval = strncpy_from_user(page, filename, len);
131 if (retval > 0) {
132 if (retval < len)
133 return 0;
134 return -ENAMETOOLONG;
135 } else if (!retval)
136 retval = -ENOENT;
137 return retval;
138}
139
140char * getname(const char __user * filename)
141{
142 char *tmp, *result;
143
144 result = ERR_PTR(-ENOMEM);
145 tmp = __getname();
146 if (tmp) {
147 int retval = do_getname(filename, tmp);
148
149 result = tmp;
150 if (retval < 0) {
151 __putname(tmp);
152 result = ERR_PTR(retval);
153 }
154 }
155 audit_getname(result);
156 return result;
157}
158
159#ifdef CONFIG_AUDITSYSCALL
160void putname(const char *name)
161{
Al Viro5ac3a9c2006-07-16 06:38:45 -0400162 if (unlikely(!audit_dummy_context()))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 audit_putname(name);
164 else
165 __putname(name);
166}
167EXPORT_SYMBOL(putname);
168#endif
169
170
171/**
172 * generic_permission - check for access rights on a Posix-like filesystem
173 * @inode: inode to check access rights for
174 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
175 * @check_acl: optional callback to check for Posix ACLs
176 *
177 * Used to check for read/write/execute permissions on a file.
178 * We use "fsuid" for this, letting us set arbitrary permissions
179 * for filesystem access without changing the "normal" uids which
180 * are used for other things..
181 */
182int generic_permission(struct inode *inode, int mask,
183 int (*check_acl)(struct inode *inode, int mask))
184{
185 umode_t mode = inode->i_mode;
186
187 if (current->fsuid == inode->i_uid)
188 mode >>= 6;
189 else {
190 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
191 int error = check_acl(inode, mask);
192 if (error == -EACCES)
193 goto check_capabilities;
194 else if (error != -EAGAIN)
195 return error;
196 }
197
198 if (in_group_p(inode->i_gid))
199 mode >>= 3;
200 }
201
202 /*
203 * If the DACs are ok we don't need any capability check.
204 */
205 if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask))
206 return 0;
207
208 check_capabilities:
209 /*
210 * Read/write DACs are always overridable.
211 * Executable DACs are overridable if at least one exec bit is set.
212 */
213 if (!(mask & MAY_EXEC) ||
214 (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
215 if (capable(CAP_DAC_OVERRIDE))
216 return 0;
217
218 /*
219 * Searching includes executable on directories, else just read.
220 */
221 if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
222 if (capable(CAP_DAC_READ_SEARCH))
223 return 0;
224
225 return -EACCES;
226}
227
228int permission(struct inode *inode, int mask, struct nameidata *nd)
229{
Trond Myklebusta343bb72006-08-22 20:06:03 -0400230 umode_t mode = inode->i_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 int retval, submask;
232
233 if (mask & MAY_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
235 /*
236 * Nobody gets write access to a read-only fs.
237 */
238 if (IS_RDONLY(inode) &&
239 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
240 return -EROFS;
241
242 /*
243 * Nobody gets write access to an immutable file.
244 */
245 if (IS_IMMUTABLE(inode))
246 return -EACCES;
247 }
248
249
Trond Myklebusta343bb72006-08-22 20:06:03 -0400250 /*
251 * MAY_EXEC on regular files requires special handling: We override
252 * filesystem execute permissions if the mode bits aren't set.
253 */
254 if ((mask & MAY_EXEC) && S_ISREG(mode) && !(mode & S_IXUGO))
255 return -EACCES;
256
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 /* Ordinary permission routines do not understand MAY_APPEND. */
258 submask = mask & ~MAY_APPEND;
259 if (inode->i_op && inode->i_op->permission)
260 retval = inode->i_op->permission(inode, submask, nd);
261 else
262 retval = generic_permission(inode, submask, NULL);
263 if (retval)
264 return retval;
265
266 return security_inode_permission(inode, mask, nd);
267}
268
Christoph Hellwige4543ed2005-11-08 21:35:04 -0800269/**
270 * vfs_permission - check for access rights to a given path
271 * @nd: lookup result that describes the path
272 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
273 *
274 * Used to check for read/write/execute permissions on a path.
275 * We use "fsuid" for this, letting us set arbitrary permissions
276 * for filesystem access without changing the "normal" uids which
277 * are used for other things.
278 */
279int vfs_permission(struct nameidata *nd, int mask)
280{
281 return permission(nd->dentry->d_inode, mask, nd);
282}
283
Christoph Hellwig8c744fb2005-11-08 21:35:04 -0800284/**
285 * file_permission - check for additional access rights to a given file
286 * @file: file to check access rights for
287 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
288 *
289 * Used to check for read/write/execute permissions on an already opened
290 * file.
291 *
292 * Note:
293 * Do not use this function in new code. All access checks should
294 * be done using vfs_permission().
295 */
296int file_permission(struct file *file, int mask)
297{
298 return permission(file->f_dentry->d_inode, mask, NULL);
299}
300
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301/*
302 * get_write_access() gets write permission for a file.
303 * put_write_access() releases this write permission.
304 * This is used for regular files.
305 * We cannot support write (and maybe mmap read-write shared) accesses and
306 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
307 * can have the following values:
308 * 0: no writers, no VM_DENYWRITE mappings
309 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
310 * > 0: (i_writecount) users are writing to the file.
311 *
312 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
313 * except for the cases where we don't hold i_writecount yet. Then we need to
314 * use {get,deny}_write_access() - these functions check the sign and refuse
315 * to do the change if sign is wrong. Exclusion between them is provided by
316 * the inode->i_lock spinlock.
317 */
318
319int get_write_access(struct inode * inode)
320{
321 spin_lock(&inode->i_lock);
322 if (atomic_read(&inode->i_writecount) < 0) {
323 spin_unlock(&inode->i_lock);
324 return -ETXTBSY;
325 }
326 atomic_inc(&inode->i_writecount);
327 spin_unlock(&inode->i_lock);
328
329 return 0;
330}
331
332int deny_write_access(struct file * file)
333{
334 struct inode *inode = file->f_dentry->d_inode;
335
336 spin_lock(&inode->i_lock);
337 if (atomic_read(&inode->i_writecount) > 0) {
338 spin_unlock(&inode->i_lock);
339 return -ETXTBSY;
340 }
341 atomic_dec(&inode->i_writecount);
342 spin_unlock(&inode->i_lock);
343
344 return 0;
345}
346
347void path_release(struct nameidata *nd)
348{
349 dput(nd->dentry);
350 mntput(nd->mnt);
351}
352
353/*
354 * umount() mustn't call path_release()/mntput() as that would clear
355 * mnt_expiry_mark
356 */
357void path_release_on_umount(struct nameidata *nd)
358{
359 dput(nd->dentry);
Miklos Szeredi751c4042005-07-07 17:57:30 -0700360 mntput_no_expire(nd->mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361}
362
Trond Myklebust834f2a42005-10-18 14:20:16 -0700363/**
364 * release_open_intent - free up open intent resources
365 * @nd: pointer to nameidata
366 */
367void release_open_intent(struct nameidata *nd)
368{
369 if (nd->intent.open.file->f_dentry == NULL)
370 put_filp(nd->intent.open.file);
371 else
372 fput(nd->intent.open.file);
373}
374
Ian Kentbcdc5e02006-09-27 01:50:44 -0700375static inline struct dentry *
376do_revalidate(struct dentry *dentry, struct nameidata *nd)
377{
378 int status = dentry->d_op->d_revalidate(dentry, nd);
379 if (unlikely(status <= 0)) {
380 /*
381 * The dentry failed validation.
382 * If d_revalidate returned 0 attempt to invalidate
383 * the dentry otherwise d_revalidate is asking us
384 * to return a fail status.
385 */
386 if (!status) {
387 if (!d_invalidate(dentry)) {
388 dput(dentry);
389 dentry = NULL;
390 }
391 } else {
392 dput(dentry);
393 dentry = ERR_PTR(status);
394 }
395 }
396 return dentry;
397}
398
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399/*
400 * Internal lookup() using the new generic dcache.
401 * SMP-safe
402 */
403static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
404{
405 struct dentry * dentry = __d_lookup(parent, name);
406
407 /* lockess __d_lookup may fail due to concurrent d_move()
408 * in some unrelated directory, so try with d_lookup
409 */
410 if (!dentry)
411 dentry = d_lookup(parent, name);
412
Ian Kentbcdc5e02006-09-27 01:50:44 -0700413 if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
414 dentry = do_revalidate(dentry, nd);
415
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 return dentry;
417}
418
419/*
420 * Short-cut version of permission(), for calling by
421 * path_walk(), when dcache lock is held. Combines parts
422 * of permission() and generic_permission(), and tests ONLY for
423 * MAY_EXEC permission.
424 *
425 * If appropriate, check DAC only. If not appropriate, or
426 * short-cut DAC fails, then call permission() to do more
427 * complete permission check.
428 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800429static int exec_permission_lite(struct inode *inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 struct nameidata *nd)
431{
432 umode_t mode = inode->i_mode;
433
434 if (inode->i_op && inode->i_op->permission)
435 return -EAGAIN;
436
437 if (current->fsuid == inode->i_uid)
438 mode >>= 6;
439 else if (in_group_p(inode->i_gid))
440 mode >>= 3;
441
442 if (mode & MAY_EXEC)
443 goto ok;
444
445 if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
446 goto ok;
447
448 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
449 goto ok;
450
451 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
452 goto ok;
453
454 return -EACCES;
455ok:
456 return security_inode_permission(inode, MAY_EXEC, nd);
457}
458
459/*
460 * This is called when everything else fails, and we actually have
461 * to go to the low-level filesystem to find out what we should do..
462 *
463 * We get the directory semaphore, and after getting that we also
464 * make sure that nobody added the entry to the dcache in the meantime..
465 * SMP-safe
466 */
467static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
468{
469 struct dentry * result;
470 struct inode *dir = parent->d_inode;
471
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800472 mutex_lock(&dir->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 /*
474 * First re-do the cached lookup just in case it was created
475 * while we waited for the directory semaphore..
476 *
477 * FIXME! This could use version numbering or similar to
478 * avoid unnecessary cache lookups.
479 *
480 * The "dcache_lock" is purely to protect the RCU list walker
481 * from concurrent renames at this point (we mustn't get false
482 * negatives from the RCU list walk here, unlike the optimistic
483 * fast walk).
484 *
485 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
486 */
487 result = d_lookup(parent, name);
488 if (!result) {
489 struct dentry * dentry = d_alloc(parent, name);
490 result = ERR_PTR(-ENOMEM);
491 if (dentry) {
492 result = dir->i_op->lookup(dir, dentry, nd);
493 if (result)
494 dput(dentry);
495 else
496 result = dentry;
497 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800498 mutex_unlock(&dir->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 return result;
500 }
501
502 /*
503 * Uhhuh! Nasty case: the cache was re-populated while
504 * we waited on the semaphore. Need to revalidate.
505 */
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800506 mutex_unlock(&dir->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 if (result->d_op && result->d_op->d_revalidate) {
Ian Kentbcdc5e02006-09-27 01:50:44 -0700508 result = do_revalidate(result, nd);
509 if (!result)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 result = ERR_PTR(-ENOENT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 }
512 return result;
513}
514
515static int __emul_lookup_dentry(const char *, struct nameidata *);
516
517/* SMP-safe */
Arjan van de Venf1662352006-01-14 13:21:31 -0800518static __always_inline int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519walk_init_root(const char *name, struct nameidata *nd)
520{
Andreas Mohre518ddb2006-09-29 02:01:22 -0700521 struct fs_struct *fs = current->fs;
522
523 read_lock(&fs->lock);
524 if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
525 nd->mnt = mntget(fs->altrootmnt);
526 nd->dentry = dget(fs->altroot);
527 read_unlock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 if (__emul_lookup_dentry(name,nd))
529 return 0;
Andreas Mohre518ddb2006-09-29 02:01:22 -0700530 read_lock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 }
Andreas Mohre518ddb2006-09-29 02:01:22 -0700532 nd->mnt = mntget(fs->rootmnt);
533 nd->dentry = dget(fs->root);
534 read_unlock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 return 1;
536}
537
Arjan van de Venf1662352006-01-14 13:21:31 -0800538static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539{
540 int res = 0;
541 char *name;
542 if (IS_ERR(link))
543 goto fail;
544
545 if (*link == '/') {
546 path_release(nd);
547 if (!walk_init_root(link, nd))
548 /* weird __emul_prefix() stuff did it */
549 goto out;
550 }
551 res = link_path_walk(link, nd);
552out:
553 if (nd->depth || res || nd->last_type!=LAST_NORM)
554 return res;
555 /*
556 * If it is an iterative symlinks resolution in open_namei() we
557 * have to copy the last component. And all that crap because of
558 * bloody create() on broken symlinks. Furrfu...
559 */
560 name = __getname();
561 if (unlikely(!name)) {
562 path_release(nd);
563 return -ENOMEM;
564 }
565 strcpy(name, nd->last.name);
566 nd->last.name = name;
567 return 0;
568fail:
569 path_release(nd);
570 return PTR_ERR(link);
571}
572
Al Viro90ebe562005-06-06 13:35:58 -0700573struct path {
574 struct vfsmount *mnt;
575 struct dentry *dentry;
576};
577
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700578static inline void dput_path(struct path *path, struct nameidata *nd)
579{
580 dput(path->dentry);
581 if (path->mnt != nd->mnt)
582 mntput(path->mnt);
583}
584
585static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
586{
587 dput(nd->dentry);
588 if (nd->mnt != path->mnt)
589 mntput(nd->mnt);
590 nd->mnt = path->mnt;
591 nd->dentry = path->dentry;
592}
593
Ian Kent051d3812006-03-27 01:14:53 -0800594static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
595{
596 int error;
597 void *cookie;
598 struct dentry *dentry = path->dentry;
599
600 touch_atime(path->mnt, dentry);
601 nd_set_link(nd, NULL);
602
603 if (path->mnt != nd->mnt) {
604 path_to_nameidata(path, nd);
605 dget(dentry);
606 }
607 mntget(path->mnt);
608 cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
609 error = PTR_ERR(cookie);
610 if (!IS_ERR(cookie)) {
611 char *s = nd_get_link(nd);
612 error = 0;
613 if (s)
614 error = __vfs_follow_link(nd, s);
615 if (dentry->d_inode->i_op->put_link)
616 dentry->d_inode->i_op->put_link(dentry, nd, cookie);
617 }
618 dput(dentry);
619 mntput(path->mnt);
620
621 return error;
622}
623
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624/*
625 * This limits recursive symlink follows to 8, while
626 * limiting consecutive symlinks to 40.
627 *
628 * Without that kind of total limit, nasty chains of consecutive
629 * symlinks can cause almost arbitrarily long lookups.
630 */
Al Viro90ebe562005-06-06 13:35:58 -0700631static inline int do_follow_link(struct path *path, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632{
633 int err = -ELOOP;
634 if (current->link_count >= MAX_NESTED_LINKS)
635 goto loop;
636 if (current->total_link_count >= 40)
637 goto loop;
638 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
639 cond_resched();
Al Viro90ebe562005-06-06 13:35:58 -0700640 err = security_inode_follow_link(path->dentry, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 if (err)
642 goto loop;
643 current->link_count++;
644 current->total_link_count++;
645 nd->depth++;
Al Virocd4e91d2005-06-06 13:36:03 -0700646 err = __do_follow_link(path, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 current->link_count--;
648 nd->depth--;
649 return err;
650loop:
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700651 dput_path(path, nd);
Al Viro839d9f92005-06-06 13:36:02 -0700652 path_release(nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 return err;
654}
655
656int follow_up(struct vfsmount **mnt, struct dentry **dentry)
657{
658 struct vfsmount *parent;
659 struct dentry *mountpoint;
660 spin_lock(&vfsmount_lock);
661 parent=(*mnt)->mnt_parent;
662 if (parent == *mnt) {
663 spin_unlock(&vfsmount_lock);
664 return 0;
665 }
666 mntget(parent);
667 mountpoint=dget((*mnt)->mnt_mountpoint);
668 spin_unlock(&vfsmount_lock);
669 dput(*dentry);
670 *dentry = mountpoint;
671 mntput(*mnt);
672 *mnt = parent;
673 return 1;
674}
675
676/* no need for dcache_lock, as serialization is taken care in
677 * namespace.c
678 */
Al Viro463ffb22005-06-06 13:36:05 -0700679static int __follow_mount(struct path *path)
680{
681 int res = 0;
682 while (d_mountpoint(path->dentry)) {
683 struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
684 if (!mounted)
685 break;
686 dput(path->dentry);
687 if (res)
688 mntput(path->mnt);
689 path->mnt = mounted;
690 path->dentry = dget(mounted->mnt_root);
691 res = 1;
692 }
693 return res;
694}
695
Al Viro58c465e2005-06-06 13:36:13 -0700696static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 while (d_mountpoint(*dentry)) {
699 struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
700 if (!mounted)
701 break;
Al Viro58c465e2005-06-06 13:36:13 -0700702 dput(*dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 mntput(*mnt);
704 *mnt = mounted;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 *dentry = dget(mounted->mnt_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707}
708
709/* no need for dcache_lock, as serialization is taken care in
710 * namespace.c
711 */
Al Viroe13b2102005-06-06 13:36:06 -0700712int follow_down(struct vfsmount **mnt, struct dentry **dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713{
714 struct vfsmount *mounted;
715
716 mounted = lookup_mnt(*mnt, *dentry);
717 if (mounted) {
Al Viroe13b2102005-06-06 13:36:06 -0700718 dput(*dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 mntput(*mnt);
720 *mnt = mounted;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 *dentry = dget(mounted->mnt_root);
722 return 1;
723 }
724 return 0;
725}
726
Arjan van de Venf1662352006-01-14 13:21:31 -0800727static __always_inline void follow_dotdot(struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728{
Andreas Mohre518ddb2006-09-29 02:01:22 -0700729 struct fs_struct *fs = current->fs;
730
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 while(1) {
732 struct vfsmount *parent;
Al Viro58c465e2005-06-06 13:36:13 -0700733 struct dentry *old = nd->dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734
Andreas Mohre518ddb2006-09-29 02:01:22 -0700735 read_lock(&fs->lock);
736 if (nd->dentry == fs->root &&
737 nd->mnt == fs->rootmnt) {
738 read_unlock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 break;
740 }
Andreas Mohre518ddb2006-09-29 02:01:22 -0700741 read_unlock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 spin_lock(&dcache_lock);
Al Viro58c465e2005-06-06 13:36:13 -0700743 if (nd->dentry != nd->mnt->mnt_root) {
744 nd->dentry = dget(nd->dentry->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 spin_unlock(&dcache_lock);
746 dput(old);
747 break;
748 }
749 spin_unlock(&dcache_lock);
750 spin_lock(&vfsmount_lock);
Al Viro58c465e2005-06-06 13:36:13 -0700751 parent = nd->mnt->mnt_parent;
752 if (parent == nd->mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 spin_unlock(&vfsmount_lock);
754 break;
755 }
756 mntget(parent);
Al Viro58c465e2005-06-06 13:36:13 -0700757 nd->dentry = dget(nd->mnt->mnt_mountpoint);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 spin_unlock(&vfsmount_lock);
759 dput(old);
Al Viro58c465e2005-06-06 13:36:13 -0700760 mntput(nd->mnt);
761 nd->mnt = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 }
Al Viro58c465e2005-06-06 13:36:13 -0700763 follow_mount(&nd->mnt, &nd->dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764}
765
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766/*
767 * It's more convoluted than I'd like it to be, but... it's still fairly
768 * small and for now I'd prefer to have fast path as straight as possible.
769 * It _is_ time-critical.
770 */
771static int do_lookup(struct nameidata *nd, struct qstr *name,
772 struct path *path)
773{
774 struct vfsmount *mnt = nd->mnt;
775 struct dentry *dentry = __d_lookup(nd->dentry, name);
776
777 if (!dentry)
778 goto need_lookup;
779 if (dentry->d_op && dentry->d_op->d_revalidate)
780 goto need_revalidate;
781done:
782 path->mnt = mnt;
783 path->dentry = dentry;
Al Viro634ee702005-06-06 13:36:13 -0700784 __follow_mount(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 return 0;
786
787need_lookup:
788 dentry = real_lookup(nd->dentry, name, nd);
789 if (IS_ERR(dentry))
790 goto fail;
791 goto done;
792
793need_revalidate:
Ian Kentbcdc5e02006-09-27 01:50:44 -0700794 dentry = do_revalidate(dentry, nd);
795 if (!dentry)
796 goto need_lookup;
797 if (IS_ERR(dentry))
798 goto fail;
799 goto done;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800
801fail:
802 return PTR_ERR(dentry);
803}
804
805/*
806 * Name resolution.
Prasanna Medaea3834d2005-04-29 16:00:17 +0100807 * This is the basic name resolution function, turning a pathname into
808 * the final dentry. We expect 'base' to be positive and a directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 *
Prasanna Medaea3834d2005-04-29 16:00:17 +0100810 * Returns 0 and nd will have valid dentry and mnt on success.
811 * Returns error and drops reference to input namei data on failure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 */
813static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
814{
815 struct path next;
816 struct inode *inode;
817 int err;
818 unsigned int lookup_flags = nd->flags;
819
820 while (*name=='/')
821 name++;
822 if (!*name)
823 goto return_reval;
824
825 inode = nd->dentry->d_inode;
826 if (nd->depth)
Trond Myklebustf55eab82006-02-04 23:28:01 -0800827 lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828
829 /* At this point we know we have a real path component. */
830 for(;;) {
831 unsigned long hash;
832 struct qstr this;
833 unsigned int c;
834
Trond Myklebustcdce5d62005-10-18 14:20:18 -0700835 nd->flags |= LOOKUP_CONTINUE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836 err = exec_permission_lite(inode, nd);
Christoph Hellwige4543ed2005-11-08 21:35:04 -0800837 if (err == -EAGAIN)
838 err = vfs_permission(nd, MAY_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 if (err)
840 break;
841
842 this.name = name;
843 c = *(const unsigned char *)name;
844
845 hash = init_name_hash();
846 do {
847 name++;
848 hash = partial_name_hash(c, hash);
849 c = *(const unsigned char *)name;
850 } while (c && (c != '/'));
851 this.len = name - (const char *) this.name;
852 this.hash = end_name_hash(hash);
853
854 /* remove trailing slashes? */
855 if (!c)
856 goto last_component;
857 while (*++name == '/');
858 if (!*name)
859 goto last_with_slashes;
860
861 /*
862 * "." and ".." are special - ".." especially so because it has
863 * to be able to know about the current root directory and
864 * parent relationships.
865 */
866 if (this.name[0] == '.') switch (this.len) {
867 default:
868 break;
869 case 2:
870 if (this.name[1] != '.')
871 break;
Al Viro58c465e2005-06-06 13:36:13 -0700872 follow_dotdot(nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 inode = nd->dentry->d_inode;
874 /* fallthrough */
875 case 1:
876 continue;
877 }
878 /*
879 * See if the low-level filesystem might want
880 * to use its own hash..
881 */
882 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
883 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
884 if (err < 0)
885 break;
886 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 /* This does the actual lookups.. */
888 err = do_lookup(nd, &this, &next);
889 if (err)
890 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891
892 err = -ENOENT;
893 inode = next.dentry->d_inode;
894 if (!inode)
895 goto out_dput;
896 err = -ENOTDIR;
897 if (!inode->i_op)
898 goto out_dput;
899
900 if (inode->i_op->follow_link) {
Al Viro90ebe562005-06-06 13:35:58 -0700901 err = do_follow_link(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902 if (err)
903 goto return_err;
904 err = -ENOENT;
905 inode = nd->dentry->d_inode;
906 if (!inode)
907 break;
908 err = -ENOTDIR;
909 if (!inode->i_op)
910 break;
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700911 } else
912 path_to_nameidata(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 err = -ENOTDIR;
914 if (!inode->i_op->lookup)
915 break;
916 continue;
917 /* here ends the main loop */
918
919last_with_slashes:
920 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
921last_component:
Trond Myklebustf55eab82006-02-04 23:28:01 -0800922 /* Clear LOOKUP_CONTINUE iff it was previously unset */
923 nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 if (lookup_flags & LOOKUP_PARENT)
925 goto lookup_parent;
926 if (this.name[0] == '.') switch (this.len) {
927 default:
928 break;
929 case 2:
930 if (this.name[1] != '.')
931 break;
Al Viro58c465e2005-06-06 13:36:13 -0700932 follow_dotdot(nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 inode = nd->dentry->d_inode;
934 /* fallthrough */
935 case 1:
936 goto return_reval;
937 }
938 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
939 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
940 if (err < 0)
941 break;
942 }
943 err = do_lookup(nd, &this, &next);
944 if (err)
945 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 inode = next.dentry->d_inode;
947 if ((lookup_flags & LOOKUP_FOLLOW)
948 && inode && inode->i_op && inode->i_op->follow_link) {
Al Viro90ebe562005-06-06 13:35:58 -0700949 err = do_follow_link(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 if (err)
951 goto return_err;
952 inode = nd->dentry->d_inode;
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700953 } else
954 path_to_nameidata(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955 err = -ENOENT;
956 if (!inode)
957 break;
958 if (lookup_flags & LOOKUP_DIRECTORY) {
959 err = -ENOTDIR;
960 if (!inode->i_op || !inode->i_op->lookup)
961 break;
962 }
963 goto return_base;
964lookup_parent:
965 nd->last = this;
966 nd->last_type = LAST_NORM;
967 if (this.name[0] != '.')
968 goto return_base;
969 if (this.len == 1)
970 nd->last_type = LAST_DOT;
971 else if (this.len == 2 && this.name[1] == '.')
972 nd->last_type = LAST_DOTDOT;
973 else
974 goto return_base;
975return_reval:
976 /*
977 * We bypassed the ordinary revalidation routines.
978 * We may need to check the cached dentry for staleness.
979 */
980 if (nd->dentry && nd->dentry->d_sb &&
981 (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
982 err = -ESTALE;
983 /* Note: we do not d_invalidate() */
984 if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
985 break;
986 }
987return_base:
988 return 0;
989out_dput:
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700990 dput_path(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 break;
992 }
993 path_release(nd);
994return_err:
995 return err;
996}
997
998/*
999 * Wrapper to retry pathname resolution whenever the underlying
1000 * file system returns an ESTALE.
1001 *
1002 * Retry the whole path once, forcing real lookup requests
1003 * instead of relying on the dcache.
1004 */
1005int fastcall link_path_walk(const char *name, struct nameidata *nd)
1006{
1007 struct nameidata save = *nd;
1008 int result;
1009
1010 /* make sure the stuff we saved doesn't go away */
1011 dget(save.dentry);
1012 mntget(save.mnt);
1013
1014 result = __link_path_walk(name, nd);
1015 if (result == -ESTALE) {
1016 *nd = save;
1017 dget(nd->dentry);
1018 mntget(nd->mnt);
1019 nd->flags |= LOOKUP_REVAL;
1020 result = __link_path_walk(name, nd);
1021 }
1022
1023 dput(save.dentry);
1024 mntput(save.mnt);
1025
1026 return result;
1027}
1028
1029int fastcall path_walk(const char * name, struct nameidata *nd)
1030{
1031 current->total_link_count = 0;
1032 return link_path_walk(name, nd);
1033}
1034
Prasanna Medaea3834d2005-04-29 16:00:17 +01001035/*
1036 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
1037 * everything is done. Returns 0 and drops input nd, if lookup failed;
1038 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
1040{
1041 if (path_walk(name, nd))
1042 return 0; /* something went wrong... */
1043
1044 if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
1045 struct dentry *old_dentry = nd->dentry;
1046 struct vfsmount *old_mnt = nd->mnt;
1047 struct qstr last = nd->last;
1048 int last_type = nd->last_type;
Andreas Mohre518ddb2006-09-29 02:01:22 -07001049 struct fs_struct *fs = current->fs;
1050
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 /*
Andreas Mohre518ddb2006-09-29 02:01:22 -07001052 * NAME was not found in alternate root or it's a directory.
1053 * Try to find it in the normal root:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054 */
1055 nd->last_type = LAST_ROOT;
Andreas Mohre518ddb2006-09-29 02:01:22 -07001056 read_lock(&fs->lock);
1057 nd->mnt = mntget(fs->rootmnt);
1058 nd->dentry = dget(fs->root);
1059 read_unlock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 if (path_walk(name, nd) == 0) {
1061 if (nd->dentry->d_inode) {
1062 dput(old_dentry);
1063 mntput(old_mnt);
1064 return 1;
1065 }
1066 path_release(nd);
1067 }
1068 nd->dentry = old_dentry;
1069 nd->mnt = old_mnt;
1070 nd->last = last;
1071 nd->last_type = last_type;
1072 }
1073 return 1;
1074}
1075
1076void set_fs_altroot(void)
1077{
1078 char *emul = __emul_prefix();
1079 struct nameidata nd;
1080 struct vfsmount *mnt = NULL, *oldmnt;
1081 struct dentry *dentry = NULL, *olddentry;
1082 int err;
Andreas Mohre518ddb2006-09-29 02:01:22 -07001083 struct fs_struct *fs = current->fs;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084
1085 if (!emul)
1086 goto set_it;
1087 err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
1088 if (!err) {
1089 mnt = nd.mnt;
1090 dentry = nd.dentry;
1091 }
1092set_it:
Andreas Mohre518ddb2006-09-29 02:01:22 -07001093 write_lock(&fs->lock);
1094 oldmnt = fs->altrootmnt;
1095 olddentry = fs->altroot;
1096 fs->altrootmnt = mnt;
1097 fs->altroot = dentry;
1098 write_unlock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 if (olddentry) {
1100 dput(olddentry);
1101 mntput(oldmnt);
1102 }
1103}
1104
Prasanna Medaea3834d2005-04-29 16:00:17 +01001105/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001106static int fastcall do_path_lookup(int dfd, const char *name,
1107 unsigned int flags, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108{
Prasanna Medaea3834d2005-04-29 16:00:17 +01001109 int retval = 0;
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001110 int fput_needed;
1111 struct file *file;
Andreas Mohre518ddb2006-09-29 02:01:22 -07001112 struct fs_struct *fs = current->fs;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113
1114 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1115 nd->flags = flags;
1116 nd->depth = 0;
1117
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 if (*name=='/') {
Andreas Mohre518ddb2006-09-29 02:01:22 -07001119 read_lock(&fs->lock);
1120 if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
1121 nd->mnt = mntget(fs->altrootmnt);
1122 nd->dentry = dget(fs->altroot);
1123 read_unlock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124 if (__emul_lookup_dentry(name,nd))
Prasanna Medaea3834d2005-04-29 16:00:17 +01001125 goto out; /* found in altroot */
Andreas Mohre518ddb2006-09-29 02:01:22 -07001126 read_lock(&fs->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 }
Andreas Mohre518ddb2006-09-29 02:01:22 -07001128 nd->mnt = mntget(fs->rootmnt);
1129 nd->dentry = dget(fs->root);
1130 read_unlock(&fs->lock);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001131 } else if (dfd == AT_FDCWD) {
Andreas Mohre518ddb2006-09-29 02:01:22 -07001132 read_lock(&fs->lock);
1133 nd->mnt = mntget(fs->pwdmnt);
1134 nd->dentry = dget(fs->pwd);
1135 read_unlock(&fs->lock);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001136 } else {
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001137 struct dentry *dentry;
1138
1139 file = fget_light(dfd, &fput_needed);
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001140 retval = -EBADF;
1141 if (!file)
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001142 goto out_fail;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001143
1144 dentry = file->f_dentry;
1145
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001146 retval = -ENOTDIR;
1147 if (!S_ISDIR(dentry->d_inode->i_mode))
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001148 goto fput_fail;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001149
1150 retval = file_permission(file, MAY_EXEC);
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001151 if (retval)
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001152 goto fput_fail;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001153
1154 nd->mnt = mntget(file->f_vfsmnt);
1155 nd->dentry = dget(dentry);
1156
1157 fput_light(file, fput_needed);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 current->total_link_count = 0;
1160 retval = link_path_walk(name, nd);
Prasanna Medaea3834d2005-04-29 16:00:17 +01001161out:
Suzuki3bc8414b2006-02-07 12:58:36 -08001162 if (likely(retval == 0)) {
Al Viro5ac3a9c2006-07-16 06:38:45 -04001163 if (unlikely(!audit_dummy_context() && nd && nd->dentry &&
Suzuki3bc8414b2006-02-07 12:58:36 -08001164 nd->dentry->d_inode))
Amy Griffis9c937dc2006-06-08 23:19:31 -04001165 audit_inode(name, nd->dentry->d_inode);
Suzuki3bc8414b2006-02-07 12:58:36 -08001166 }
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001167out_fail:
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001168 return retval;
1169
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001170fput_fail:
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001171 fput_light(file, fput_needed);
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001172 goto out_fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173}
1174
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001175int fastcall path_lookup(const char *name, unsigned int flags,
1176 struct nameidata *nd)
1177{
1178 return do_path_lookup(AT_FDCWD, name, flags, nd);
1179}
1180
1181static int __path_lookup_intent_open(int dfd, const char *name,
1182 unsigned int lookup_flags, struct nameidata *nd,
1183 int open_flags, int create_mode)
Trond Myklebust834f2a42005-10-18 14:20:16 -07001184{
1185 struct file *filp = get_empty_filp();
1186 int err;
1187
1188 if (filp == NULL)
1189 return -ENFILE;
1190 nd->intent.open.file = filp;
1191 nd->intent.open.flags = open_flags;
1192 nd->intent.open.create_mode = create_mode;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001193 err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
Trond Myklebust834f2a42005-10-18 14:20:16 -07001194 if (IS_ERR(nd->intent.open.file)) {
1195 if (err == 0) {
1196 err = PTR_ERR(nd->intent.open.file);
1197 path_release(nd);
1198 }
1199 } else if (err != 0)
1200 release_open_intent(nd);
1201 return err;
1202}
1203
1204/**
1205 * path_lookup_open - lookup a file path with open intent
Martin Waitz7045f372006-02-01 03:06:57 -08001206 * @dfd: the directory to use as base, or AT_FDCWD
Trond Myklebust834f2a42005-10-18 14:20:16 -07001207 * @name: pointer to file name
1208 * @lookup_flags: lookup intent flags
1209 * @nd: pointer to nameidata
1210 * @open_flags: open intent flags
1211 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001212int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags,
Trond Myklebust834f2a42005-10-18 14:20:16 -07001213 struct nameidata *nd, int open_flags)
1214{
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001215 return __path_lookup_intent_open(dfd, name, lookup_flags, nd,
Trond Myklebust834f2a42005-10-18 14:20:16 -07001216 open_flags, 0);
1217}
1218
1219/**
1220 * path_lookup_create - lookup a file path with open + create intent
Martin Waitz7045f372006-02-01 03:06:57 -08001221 * @dfd: the directory to use as base, or AT_FDCWD
Trond Myklebust834f2a42005-10-18 14:20:16 -07001222 * @name: pointer to file name
1223 * @lookup_flags: lookup intent flags
1224 * @nd: pointer to nameidata
1225 * @open_flags: open intent flags
1226 * @create_mode: create intent flags
1227 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001228static int path_lookup_create(int dfd, const char *name,
1229 unsigned int lookup_flags, struct nameidata *nd,
1230 int open_flags, int create_mode)
Trond Myklebust834f2a42005-10-18 14:20:16 -07001231{
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001232 return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE,
1233 nd, open_flags, create_mode);
Trond Myklebust834f2a42005-10-18 14:20:16 -07001234}
1235
1236int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags,
1237 struct nameidata *nd, int open_flags)
1238{
1239 char *tmp = getname(name);
1240 int err = PTR_ERR(tmp);
1241
1242 if (!IS_ERR(tmp)) {
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001243 err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0);
Trond Myklebust834f2a42005-10-18 14:20:16 -07001244 putname(tmp);
1245 }
1246 return err;
1247}
1248
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249/*
1250 * Restricted form of lookup. Doesn't follow links, single-component only,
1251 * needs parent already locked. Doesn't follow mounts.
1252 * SMP-safe.
1253 */
1254static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
1255{
1256 struct dentry * dentry;
1257 struct inode *inode;
1258 int err;
1259
1260 inode = base->d_inode;
1261 err = permission(inode, MAY_EXEC, nd);
1262 dentry = ERR_PTR(err);
1263 if (err)
1264 goto out;
1265
1266 /*
1267 * See if the low-level filesystem might want
1268 * to use its own hash..
1269 */
1270 if (base->d_op && base->d_op->d_hash) {
1271 err = base->d_op->d_hash(base, name);
1272 dentry = ERR_PTR(err);
1273 if (err < 0)
1274 goto out;
1275 }
1276
1277 dentry = cached_lookup(base, name, nd);
1278 if (!dentry) {
1279 struct dentry *new = d_alloc(base, name);
1280 dentry = ERR_PTR(-ENOMEM);
1281 if (!new)
1282 goto out;
1283 dentry = inode->i_op->lookup(inode, new, nd);
1284 if (!dentry)
1285 dentry = new;
1286 else
1287 dput(new);
1288 }
1289out:
1290 return dentry;
1291}
1292
Adrian Bunka244e162006-03-31 02:32:11 -08001293static struct dentry *lookup_hash(struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294{
Christoph Hellwig49705b72005-11-08 21:35:06 -08001295 return __lookup_hash(&nd->last, nd->dentry, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296}
1297
1298/* SMP-safe */
1299struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
1300{
1301 unsigned long hash;
1302 struct qstr this;
1303 unsigned int c;
1304
1305 this.name = name;
1306 this.len = len;
1307 if (!len)
1308 goto access;
1309
1310 hash = init_name_hash();
1311 while (len--) {
1312 c = *(const unsigned char *)name++;
1313 if (c == '/' || c == '\0')
1314 goto access;
1315 hash = partial_name_hash(c, hash);
1316 }
1317 this.hash = end_name_hash(hash);
1318
Christoph Hellwig49705b72005-11-08 21:35:06 -08001319 return __lookup_hash(&this, base, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320access:
1321 return ERR_PTR(-EACCES);
1322}
1323
1324/*
1325 * namei()
1326 *
1327 * is used by most simple commands to get the inode of a specified name.
1328 * Open, link etc use their own routines, but this is enough for things
1329 * like 'chmod' etc.
1330 *
1331 * namei exists in two versions: namei/lnamei. The only difference is
1332 * that namei follows links, while lnamei does not.
1333 * SMP-safe
1334 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001335int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags,
1336 struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337{
1338 char *tmp = getname(name);
1339 int err = PTR_ERR(tmp);
1340
1341 if (!IS_ERR(tmp)) {
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001342 err = do_path_lookup(dfd, tmp, flags, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343 putname(tmp);
1344 }
1345 return err;
1346}
1347
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001348int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
1349{
1350 return __user_walk_fd(AT_FDCWD, name, flags, nd);
1351}
1352
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353/*
1354 * It's inline, so penalty for filesystems that don't use sticky bit is
1355 * minimal.
1356 */
1357static inline int check_sticky(struct inode *dir, struct inode *inode)
1358{
1359 if (!(dir->i_mode & S_ISVTX))
1360 return 0;
1361 if (inode->i_uid == current->fsuid)
1362 return 0;
1363 if (dir->i_uid == current->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 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001387static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388{
1389 int error;
1390
1391 if (!victim->d_inode)
1392 return -ENOENT;
1393
1394 BUG_ON(victim->d_parent->d_inode != dir);
Amy Griffis73d3ec52006-07-13 13:16:39 -04001395 audit_inode_child(victim->d_name.name, victim->d_inode, dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396
1397 error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
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))
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 */
1427static inline int may_create(struct inode *dir, struct dentry *child,
1428 struct nameidata *nd)
1429{
1430 if (child->d_inode)
1431 return -EEXIST;
1432 if (IS_DEADDIR(dir))
1433 return -ENOENT;
1434 return permission(dir,MAY_WRITE | MAY_EXEC, nd);
1435}
1436
1437/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 * O_DIRECTORY translates into forcing a directory lookup.
1439 */
1440static inline int lookup_flags(unsigned int f)
1441{
1442 unsigned long retval = LOOKUP_FOLLOW;
1443
1444 if (f & O_NOFOLLOW)
1445 retval &= ~LOOKUP_FOLLOW;
1446
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447 if (f & O_DIRECTORY)
1448 retval |= LOOKUP_DIRECTORY;
1449
1450 return retval;
1451}
1452
1453/*
1454 * p1 and p2 should be directories on the same fs.
1455 */
1456struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1457{
1458 struct dentry *p;
1459
1460 if (p1 == p2) {
Ingo Molnarf2eace22006-07-03 00:25:05 -07001461 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462 return NULL;
1463 }
1464
Arjan van de Vena11f3a02006-03-23 03:00:33 -08001465 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466
1467 for (p = p1; p->d_parent != p; p = p->d_parent) {
1468 if (p->d_parent == p2) {
Ingo Molnarf2eace22006-07-03 00:25:05 -07001469 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1470 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 return p;
1472 }
1473 }
1474
1475 for (p = p2; p->d_parent != p; p = p->d_parent) {
1476 if (p->d_parent == p1) {
Ingo Molnarf2eace22006-07-03 00:25:05 -07001477 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1478 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 return p;
1480 }
1481 }
1482
Ingo Molnarf2eace22006-07-03 00:25:05 -07001483 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1484 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485 return NULL;
1486}
1487
1488void unlock_rename(struct dentry *p1, struct dentry *p2)
1489{
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001490 mutex_unlock(&p1->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491 if (p1 != p2) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001492 mutex_unlock(&p2->d_inode->i_mutex);
Arjan van de Vena11f3a02006-03-23 03:00:33 -08001493 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494 }
1495}
1496
1497int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1498 struct nameidata *nd)
1499{
1500 int error = may_create(dir, dentry, nd);
1501
1502 if (error)
1503 return error;
1504
1505 if (!dir->i_op || !dir->i_op->create)
1506 return -EACCES; /* shouldn't it be ENOSYS? */
1507 mode &= S_IALLUGO;
1508 mode |= S_IFREG;
1509 error = security_inode_create(dir, dentry, mode);
1510 if (error)
1511 return error;
1512 DQUOT_INIT(dir);
1513 error = dir->i_op->create(dir, dentry, mode, nd);
Stephen Smalleya74574a2005-09-09 13:01:44 -07001514 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00001515 fsnotify_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516 return error;
1517}
1518
1519int may_open(struct nameidata *nd, int acc_mode, int flag)
1520{
1521 struct dentry *dentry = nd->dentry;
1522 struct inode *inode = dentry->d_inode;
1523 int error;
1524
1525 if (!inode)
1526 return -ENOENT;
1527
1528 if (S_ISLNK(inode->i_mode))
1529 return -ELOOP;
1530
1531 if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
1532 return -EISDIR;
1533
Christoph Hellwige4543ed2005-11-08 21:35:04 -08001534 error = vfs_permission(nd, acc_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535 if (error)
1536 return error;
1537
1538 /*
1539 * FIFO's, sockets and device files are special: they don't
1540 * actually live on the filesystem itself, and as such you
1541 * can write to them even if the filesystem is read-only.
1542 */
1543 if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
1544 flag &= ~O_TRUNC;
1545 } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
1546 if (nd->mnt->mnt_flags & MNT_NODEV)
1547 return -EACCES;
1548
1549 flag &= ~O_TRUNC;
1550 } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
1551 return -EROFS;
1552 /*
1553 * An append-only file must be opened in append mode for writing.
1554 */
1555 if (IS_APPEND(inode)) {
1556 if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1557 return -EPERM;
1558 if (flag & O_TRUNC)
1559 return -EPERM;
1560 }
1561
1562 /* O_NOATIME can only be set by the owner or superuser */
1563 if (flag & O_NOATIME)
1564 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
1565 return -EPERM;
1566
1567 /*
1568 * Ensure there are no outstanding leases on the file.
1569 */
1570 error = break_lease(inode, flag);
1571 if (error)
1572 return error;
1573
1574 if (flag & O_TRUNC) {
1575 error = get_write_access(inode);
1576 if (error)
1577 return error;
1578
1579 /*
1580 * Refuse to truncate files with mandatory locks held on them.
1581 */
1582 error = locks_verify_locked(inode);
1583 if (!error) {
1584 DQUOT_INIT(inode);
1585
NeilBrown4a301312006-01-08 01:02:39 -08001586 error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 }
1588 put_write_access(inode);
1589 if (error)
1590 return error;
1591 } else
1592 if (flag & FMODE_WRITE)
1593 DQUOT_INIT(inode);
1594
1595 return 0;
1596}
1597
1598/*
1599 * open_namei()
1600 *
1601 * namei for open - this is in fact almost the whole open-routine.
1602 *
1603 * Note that the low bits of "flag" aren't the same as in the open
1604 * system call - they are 00 - no permissions needed
1605 * 01 - read permission needed
1606 * 10 - write permission needed
1607 * 11 - read/write permissions needed
1608 * which is a lot more logical, and also allows the "no perm" needed
1609 * for symlinks (where the permissions are checked later).
1610 * SMP-safe
1611 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001612int open_namei(int dfd, const char *pathname, int flag,
1613 int mode, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614{
Trond Myklebust834f2a42005-10-18 14:20:16 -07001615 int acc_mode, error;
Al Viro4e7506e2005-06-06 13:36:00 -07001616 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 struct dentry *dir;
1618 int count = 0;
1619
1620 acc_mode = ACC_MODE(flag);
1621
Trond Myklebust834f2a42005-10-18 14:20:16 -07001622 /* O_TRUNC implies we need access checks for write permissions */
1623 if (flag & O_TRUNC)
1624 acc_mode |= MAY_WRITE;
1625
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 /* Allow the LSM permission hook to distinguish append
1627 access from general write access. */
1628 if (flag & O_APPEND)
1629 acc_mode |= MAY_APPEND;
1630
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 /*
1632 * The simplest case - just a plain lookup.
1633 */
1634 if (!(flag & O_CREAT)) {
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001635 error = path_lookup_open(dfd, pathname, lookup_flags(flag),
1636 nd, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 if (error)
1638 return error;
1639 goto ok;
1640 }
1641
1642 /*
1643 * Create - we need to know the parent.
1644 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001645 error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 if (error)
1647 return error;
1648
1649 /*
1650 * We have the parent and last component. First of all, check
1651 * that we are not asked to creat(2) an obvious directory - that
1652 * will not do.
1653 */
1654 error = -EISDIR;
1655 if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
1656 goto exit;
1657
1658 dir = nd->dentry;
1659 nd->flags &= ~LOOKUP_PARENT;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001660 mutex_lock(&dir->d_inode->i_mutex);
Christoph Hellwig49705b72005-11-08 21:35:06 -08001661 path.dentry = lookup_hash(nd);
Al Virod73ffe12005-06-06 13:36:01 -07001662 path.mnt = nd->mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663
1664do_last:
Al Viro4e7506e2005-06-06 13:36:00 -07001665 error = PTR_ERR(path.dentry);
1666 if (IS_ERR(path.dentry)) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001667 mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 goto exit;
1669 }
1670
Oleg Drokin4af4c522006-03-25 03:06:54 -08001671 if (IS_ERR(nd->intent.open.file)) {
1672 mutex_unlock(&dir->d_inode->i_mutex);
1673 error = PTR_ERR(nd->intent.open.file);
1674 goto exit_dput;
1675 }
1676
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677 /* Negative dentry, just create the file */
Al Viro4e7506e2005-06-06 13:36:00 -07001678 if (!path.dentry->d_inode) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 if (!IS_POSIXACL(dir->d_inode))
1680 mode &= ~current->fs->umask;
Al Viro4e7506e2005-06-06 13:36:00 -07001681 error = vfs_create(dir->d_inode, path.dentry, mode, nd);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001682 mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 dput(nd->dentry);
Al Viro4e7506e2005-06-06 13:36:00 -07001684 nd->dentry = path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 if (error)
1686 goto exit;
1687 /* Don't check for write permission, don't truncate */
1688 acc_mode = 0;
1689 flag &= ~O_TRUNC;
1690 goto ok;
1691 }
1692
1693 /*
1694 * It already exists.
1695 */
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001696 mutex_unlock(&dir->d_inode->i_mutex);
Amy Griffis3e2efce2006-07-13 13:16:02 -04001697 audit_inode_update(path.dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698
1699 error = -EEXIST;
1700 if (flag & O_EXCL)
1701 goto exit_dput;
1702
Al Viroe13b2102005-06-06 13:36:06 -07001703 if (__follow_mount(&path)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 error = -ELOOP;
Al Viroba7a4c12005-06-06 13:36:08 -07001705 if (flag & O_NOFOLLOW)
1706 goto exit_dput;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 }
Amy Griffis3e2efce2006-07-13 13:16:02 -04001708
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 error = -ENOENT;
Al Viro4e7506e2005-06-06 13:36:00 -07001710 if (!path.dentry->d_inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 goto exit_dput;
Al Viro4e7506e2005-06-06 13:36:00 -07001712 if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713 goto do_link;
1714
Miklos Szeredi09dd17d2005-09-06 15:18:21 -07001715 path_to_nameidata(&path, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 error = -EISDIR;
Al Viro4e7506e2005-06-06 13:36:00 -07001717 if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718 goto exit;
1719ok:
1720 error = may_open(nd, acc_mode, flag);
1721 if (error)
1722 goto exit;
1723 return 0;
1724
1725exit_dput:
Miklos Szeredi09dd17d2005-09-06 15:18:21 -07001726 dput_path(&path, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727exit:
Trond Myklebust834f2a42005-10-18 14:20:16 -07001728 if (!IS_ERR(nd->intent.open.file))
1729 release_open_intent(nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 path_release(nd);
1731 return error;
1732
1733do_link:
1734 error = -ELOOP;
1735 if (flag & O_NOFOLLOW)
1736 goto exit_dput;
1737 /*
1738 * This is subtle. Instead of calling do_follow_link() we do the
1739 * thing by hands. The reason is that this way we have zero link_count
1740 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1741 * After that we have the parent and last component, i.e.
1742 * we are in the same situation as after the first path_walk().
1743 * Well, almost - if the last component is normal we get its copy
1744 * stored in nd->last.name and we will have to putname() it when we
1745 * are done. Procfs-like symlinks just set LAST_BIND.
1746 */
1747 nd->flags |= LOOKUP_PARENT;
Al Viro4e7506e2005-06-06 13:36:00 -07001748 error = security_inode_follow_link(path.dentry, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001749 if (error)
1750 goto exit_dput;
Al Virocd4e91d2005-06-06 13:36:03 -07001751 error = __do_follow_link(&path, nd);
Kirill Korotaevde459212006-07-14 00:23:49 -07001752 if (error) {
1753 /* Does someone understand code flow here? Or it is only
1754 * me so stupid? Anathema to whoever designed this non-sense
1755 * with "intent.open".
1756 */
1757 release_open_intent(nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 return error;
Kirill Korotaevde459212006-07-14 00:23:49 -07001759 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 nd->flags &= ~LOOKUP_PARENT;
Al Virod671d5e2005-06-06 13:36:04 -07001761 if (nd->last_type == LAST_BIND)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 goto ok;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763 error = -EISDIR;
1764 if (nd->last_type != LAST_NORM)
1765 goto exit;
1766 if (nd->last.name[nd->last.len]) {
Linus Torvalds82984112005-10-06 21:54:21 -07001767 __putname(nd->last.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 goto exit;
1769 }
1770 error = -ELOOP;
1771 if (count++==32) {
Linus Torvalds82984112005-10-06 21:54:21 -07001772 __putname(nd->last.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 goto exit;
1774 }
1775 dir = nd->dentry;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001776 mutex_lock(&dir->d_inode->i_mutex);
Christoph Hellwig49705b72005-11-08 21:35:06 -08001777 path.dentry = lookup_hash(nd);
Al Virod671d5e2005-06-06 13:36:04 -07001778 path.mnt = nd->mnt;
Linus Torvalds82984112005-10-06 21:54:21 -07001779 __putname(nd->last.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780 goto do_last;
1781}
1782
1783/**
1784 * lookup_create - lookup a dentry, creating it if it doesn't exist
1785 * @nd: nameidata info
1786 * @is_dir: directory flag
1787 *
1788 * Simple function to lookup and return a dentry and create it
1789 * if it doesn't exist. Is SMP-safe.
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001790 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001791 * Returns with nd->dentry->d_inode->i_mutex locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 */
1793struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1794{
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001795 struct dentry *dentry = ERR_PTR(-EEXIST);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796
Ingo Molnarf2eace22006-07-03 00:25:05 -07001797 mutex_lock_nested(&nd->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001798 /*
1799 * Yucky last component or no last component at all?
1800 * (foo/., foo/.., /////)
1801 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802 if (nd->last_type != LAST_NORM)
1803 goto fail;
1804 nd->flags &= ~LOOKUP_PARENT;
ASANO Masahiroa6349042006-08-22 20:06:02 -04001805 nd->flags |= LOOKUP_CREATE;
1806 nd->intent.open.flags = O_EXCL;
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001807
1808 /*
1809 * Do the final lookup.
1810 */
Christoph Hellwig49705b72005-11-08 21:35:06 -08001811 dentry = lookup_hash(nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001812 if (IS_ERR(dentry))
1813 goto fail;
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001814
1815 /*
1816 * Special case - lookup gave negative, but... we had foo/bar/
1817 * From the vfs_mknod() POV we just have a negative dentry -
1818 * all is fine. Let's be bastards - you had / on the end, you've
1819 * been asking for (non-existent) directory. -ENOENT for you.
1820 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821 if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
1822 goto enoent;
1823 return dentry;
1824enoent:
1825 dput(dentry);
1826 dentry = ERR_PTR(-ENOENT);
1827fail:
1828 return dentry;
1829}
Christoph Hellwigf81a0bf2005-05-19 12:26:43 -07001830EXPORT_SYMBOL_GPL(lookup_create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831
1832int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1833{
1834 int error = may_create(dir, dentry, NULL);
1835
1836 if (error)
1837 return error;
1838
1839 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1840 return -EPERM;
1841
1842 if (!dir->i_op || !dir->i_op->mknod)
1843 return -EPERM;
1844
1845 error = security_inode_mknod(dir, dentry, mode, dev);
1846 if (error)
1847 return error;
1848
1849 DQUOT_INIT(dir);
1850 error = dir->i_op->mknod(dir, dentry, mode, dev);
Stephen Smalleya74574a2005-09-09 13:01:44 -07001851 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00001852 fsnotify_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853 return error;
1854}
1855
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001856asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
1857 unsigned dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858{
1859 int error = 0;
1860 char * tmp;
1861 struct dentry * dentry;
1862 struct nameidata nd;
1863
1864 if (S_ISDIR(mode))
1865 return -EPERM;
1866 tmp = getname(filename);
1867 if (IS_ERR(tmp))
1868 return PTR_ERR(tmp);
1869
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001870 error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871 if (error)
1872 goto out;
1873 dentry = lookup_create(&nd, 0);
1874 error = PTR_ERR(dentry);
1875
1876 if (!IS_POSIXACL(nd.dentry->d_inode))
1877 mode &= ~current->fs->umask;
1878 if (!IS_ERR(dentry)) {
1879 switch (mode & S_IFMT) {
1880 case 0: case S_IFREG:
1881 error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
1882 break;
1883 case S_IFCHR: case S_IFBLK:
1884 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
1885 new_decode_dev(dev));
1886 break;
1887 case S_IFIFO: case S_IFSOCK:
1888 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
1889 break;
1890 case S_IFDIR:
1891 error = -EPERM;
1892 break;
1893 default:
1894 error = -EINVAL;
1895 }
1896 dput(dentry);
1897 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001898 mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 path_release(&nd);
1900out:
1901 putname(tmp);
1902
1903 return error;
1904}
1905
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001906asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev)
1907{
1908 return sys_mknodat(AT_FDCWD, filename, mode, dev);
1909}
1910
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1912{
1913 int error = may_create(dir, dentry, NULL);
1914
1915 if (error)
1916 return error;
1917
1918 if (!dir->i_op || !dir->i_op->mkdir)
1919 return -EPERM;
1920
1921 mode &= (S_IRWXUGO|S_ISVTX);
1922 error = security_inode_mkdir(dir, dentry, mode);
1923 if (error)
1924 return error;
1925
1926 DQUOT_INIT(dir);
1927 error = dir->i_op->mkdir(dir, dentry, mode);
Stephen Smalleya74574a2005-09-09 13:01:44 -07001928 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00001929 fsnotify_mkdir(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930 return error;
1931}
1932
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001933asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934{
1935 int error = 0;
1936 char * tmp;
1937
1938 tmp = getname(pathname);
1939 error = PTR_ERR(tmp);
1940 if (!IS_ERR(tmp)) {
1941 struct dentry *dentry;
1942 struct nameidata nd;
1943
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001944 error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 if (error)
1946 goto out;
1947 dentry = lookup_create(&nd, 1);
1948 error = PTR_ERR(dentry);
1949 if (!IS_ERR(dentry)) {
1950 if (!IS_POSIXACL(nd.dentry->d_inode))
1951 mode &= ~current->fs->umask;
1952 error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
1953 dput(dentry);
1954 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001955 mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956 path_release(&nd);
1957out:
1958 putname(tmp);
1959 }
1960
1961 return error;
1962}
1963
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001964asmlinkage long sys_mkdir(const char __user *pathname, int mode)
1965{
1966 return sys_mkdirat(AT_FDCWD, pathname, mode);
1967}
1968
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969/*
1970 * We try to drop the dentry early: we should have
1971 * a usage count of 2 if we're the only user of this
1972 * dentry, and if that is true (possibly after pruning
1973 * the dcache), then we drop the dentry now.
1974 *
1975 * A low-level filesystem can, if it choses, legally
1976 * do a
1977 *
1978 * if (!d_unhashed(dentry))
1979 * return -EBUSY;
1980 *
1981 * if it cannot handle the case of removing a directory
1982 * that is still in use by something else..
1983 */
1984void dentry_unhash(struct dentry *dentry)
1985{
1986 dget(dentry);
1987 if (atomic_read(&dentry->d_count))
1988 shrink_dcache_parent(dentry);
1989 spin_lock(&dcache_lock);
1990 spin_lock(&dentry->d_lock);
1991 if (atomic_read(&dentry->d_count) == 2)
1992 __d_drop(dentry);
1993 spin_unlock(&dentry->d_lock);
1994 spin_unlock(&dcache_lock);
1995}
1996
1997int vfs_rmdir(struct inode *dir, struct dentry *dentry)
1998{
1999 int error = may_delete(dir, dentry, 1);
2000
2001 if (error)
2002 return error;
2003
2004 if (!dir->i_op || !dir->i_op->rmdir)
2005 return -EPERM;
2006
2007 DQUOT_INIT(dir);
2008
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002009 mutex_lock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002010 dentry_unhash(dentry);
2011 if (d_mountpoint(dentry))
2012 error = -EBUSY;
2013 else {
2014 error = security_inode_rmdir(dir, dentry);
2015 if (!error) {
2016 error = dir->i_op->rmdir(dir, dentry);
2017 if (!error)
2018 dentry->d_inode->i_flags |= S_DEAD;
2019 }
2020 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002021 mutex_unlock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023 d_delete(dentry);
2024 }
2025 dput(dentry);
2026
2027 return error;
2028}
2029
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002030static long do_rmdir(int dfd, const char __user *pathname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002031{
2032 int error = 0;
2033 char * name;
2034 struct dentry *dentry;
2035 struct nameidata nd;
2036
2037 name = getname(pathname);
2038 if(IS_ERR(name))
2039 return PTR_ERR(name);
2040
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002041 error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042 if (error)
2043 goto exit;
2044
2045 switch(nd.last_type) {
2046 case LAST_DOTDOT:
2047 error = -ENOTEMPTY;
2048 goto exit1;
2049 case LAST_DOT:
2050 error = -EINVAL;
2051 goto exit1;
2052 case LAST_ROOT:
2053 error = -EBUSY;
2054 goto exit1;
2055 }
Ingo Molnarf2eace22006-07-03 00:25:05 -07002056 mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
Christoph Hellwig49705b72005-11-08 21:35:06 -08002057 dentry = lookup_hash(&nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 error = PTR_ERR(dentry);
2059 if (!IS_ERR(dentry)) {
2060 error = vfs_rmdir(nd.dentry->d_inode, dentry);
2061 dput(dentry);
2062 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002063 mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002064exit1:
2065 path_release(&nd);
2066exit:
2067 putname(name);
2068 return error;
2069}
2070
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002071asmlinkage long sys_rmdir(const char __user *pathname)
2072{
2073 return do_rmdir(AT_FDCWD, pathname);
2074}
2075
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076int vfs_unlink(struct inode *dir, struct dentry *dentry)
2077{
2078 int error = may_delete(dir, dentry, 0);
2079
2080 if (error)
2081 return error;
2082
2083 if (!dir->i_op || !dir->i_op->unlink)
2084 return -EPERM;
2085
2086 DQUOT_INIT(dir);
2087
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002088 mutex_lock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 if (d_mountpoint(dentry))
2090 error = -EBUSY;
2091 else {
2092 error = security_inode_unlink(dir, dentry);
2093 if (!error)
2094 error = dir->i_op->unlink(dir, dentry);
2095 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002096 mutex_unlock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002097
2098 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2099 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2100 d_delete(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002101 }
Robert Love0eeca282005-07-12 17:06:03 -04002102
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103 return error;
2104}
2105
2106/*
2107 * Make sure that the actual truncation of the file will occur outside its
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002108 * directory's i_mutex. Truncate can take a long time if there is a lot of
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 * writeout happening, and we don't want to prevent access to the directory
2110 * while waiting on the I/O.
2111 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002112static long do_unlinkat(int dfd, const char __user *pathname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113{
2114 int error = 0;
2115 char * name;
2116 struct dentry *dentry;
2117 struct nameidata nd;
2118 struct inode *inode = NULL;
2119
2120 name = getname(pathname);
2121 if(IS_ERR(name))
2122 return PTR_ERR(name);
2123
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002124 error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125 if (error)
2126 goto exit;
2127 error = -EISDIR;
2128 if (nd.last_type != LAST_NORM)
2129 goto exit1;
Ingo Molnarf2eace22006-07-03 00:25:05 -07002130 mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
Christoph Hellwig49705b72005-11-08 21:35:06 -08002131 dentry = lookup_hash(&nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132 error = PTR_ERR(dentry);
2133 if (!IS_ERR(dentry)) {
2134 /* Why not before? Because we want correct error value */
2135 if (nd.last.name[nd.last.len])
2136 goto slashes;
2137 inode = dentry->d_inode;
2138 if (inode)
2139 atomic_inc(&inode->i_count);
2140 error = vfs_unlink(nd.dentry->d_inode, dentry);
2141 exit2:
2142 dput(dentry);
2143 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002144 mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145 if (inode)
2146 iput(inode); /* truncate the inode here */
2147exit1:
2148 path_release(&nd);
2149exit:
2150 putname(name);
2151 return error;
2152
2153slashes:
2154 error = !dentry->d_inode ? -ENOENT :
2155 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2156 goto exit2;
2157}
2158
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002159asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag)
2160{
2161 if ((flag & ~AT_REMOVEDIR) != 0)
2162 return -EINVAL;
2163
2164 if (flag & AT_REMOVEDIR)
2165 return do_rmdir(dfd, pathname);
2166
2167 return do_unlinkat(dfd, pathname);
2168}
2169
2170asmlinkage long sys_unlink(const char __user *pathname)
2171{
2172 return do_unlinkat(AT_FDCWD, pathname);
2173}
2174
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
2176{
2177 int error = may_create(dir, dentry, NULL);
2178
2179 if (error)
2180 return error;
2181
2182 if (!dir->i_op || !dir->i_op->symlink)
2183 return -EPERM;
2184
2185 error = security_inode_symlink(dir, dentry, oldname);
2186 if (error)
2187 return error;
2188
2189 DQUOT_INIT(dir);
2190 error = dir->i_op->symlink(dir, dentry, oldname);
Stephen Smalleya74574a2005-09-09 13:01:44 -07002191 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00002192 fsnotify_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 return error;
2194}
2195
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002196asmlinkage long sys_symlinkat(const char __user *oldname,
2197 int newdfd, const char __user *newname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198{
2199 int error = 0;
2200 char * from;
2201 char * to;
2202
2203 from = getname(oldname);
2204 if(IS_ERR(from))
2205 return PTR_ERR(from);
2206 to = getname(newname);
2207 error = PTR_ERR(to);
2208 if (!IS_ERR(to)) {
2209 struct dentry *dentry;
2210 struct nameidata nd;
2211
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002212 error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002213 if (error)
2214 goto out;
2215 dentry = lookup_create(&nd, 0);
2216 error = PTR_ERR(dentry);
2217 if (!IS_ERR(dentry)) {
2218 error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
2219 dput(dentry);
2220 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002221 mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222 path_release(&nd);
2223out:
2224 putname(to);
2225 }
2226 putname(from);
2227 return error;
2228}
2229
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002230asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname)
2231{
2232 return sys_symlinkat(oldname, AT_FDCWD, newname);
2233}
2234
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2236{
2237 struct inode *inode = old_dentry->d_inode;
2238 int error;
2239
2240 if (!inode)
2241 return -ENOENT;
2242
2243 error = may_create(dir, new_dentry, NULL);
2244 if (error)
2245 return error;
2246
2247 if (dir->i_sb != inode->i_sb)
2248 return -EXDEV;
2249
2250 /*
2251 * A link to an append-only or immutable file cannot be created.
2252 */
2253 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2254 return -EPERM;
2255 if (!dir->i_op || !dir->i_op->link)
2256 return -EPERM;
2257 if (S_ISDIR(old_dentry->d_inode->i_mode))
2258 return -EPERM;
2259
2260 error = security_inode_link(old_dentry, dir, new_dentry);
2261 if (error)
2262 return error;
2263
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002264 mutex_lock(&old_dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002265 DQUOT_INIT(dir);
2266 error = dir->i_op->link(old_dentry, dir, new_dentry);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002267 mutex_unlock(&old_dentry->d_inode->i_mutex);
Stephen Smalleye31e14e2005-09-09 13:01:45 -07002268 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00002269 fsnotify_create(dir, new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 return error;
2271}
2272
2273/*
2274 * Hardlinks are often used in delicate situations. We avoid
2275 * security-related surprises by not following symlinks on the
2276 * newname. --KAB
2277 *
2278 * We don't follow them on the oldname either to be compatible
2279 * with linux 2.0, and to avoid hard-linking to directories
2280 * and other special files. --ADM
2281 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002282asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
Ulrich Drepperc04030e2006-02-24 13:04:21 -08002283 int newdfd, const char __user *newname,
2284 int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285{
2286 struct dentry *new_dentry;
2287 struct nameidata nd, old_nd;
2288 int error;
2289 char * to;
2290
Ulrich Drepper45c9b112006-06-25 05:49:11 -07002291 if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
Ulrich Drepperc04030e2006-02-24 13:04:21 -08002292 return -EINVAL;
2293
Linus Torvalds1da177e2005-04-16 15:20:36 -07002294 to = getname(newname);
2295 if (IS_ERR(to))
2296 return PTR_ERR(to);
2297
Ulrich Drepper45c9b112006-06-25 05:49:11 -07002298 error = __user_walk_fd(olddfd, oldname,
2299 flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
2300 &old_nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 if (error)
2302 goto exit;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002303 error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 if (error)
2305 goto out;
2306 error = -EXDEV;
2307 if (old_nd.mnt != nd.mnt)
2308 goto out_release;
2309 new_dentry = lookup_create(&nd, 0);
2310 error = PTR_ERR(new_dentry);
2311 if (!IS_ERR(new_dentry)) {
2312 error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
2313 dput(new_dentry);
2314 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002315 mutex_unlock(&nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316out_release:
2317 path_release(&nd);
2318out:
2319 path_release(&old_nd);
2320exit:
2321 putname(to);
2322
2323 return error;
2324}
2325
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002326asmlinkage long sys_link(const char __user *oldname, const char __user *newname)
2327{
Ulrich Drepperc04030e2006-02-24 13:04:21 -08002328 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002329}
2330
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331/*
2332 * The worst of all namespace operations - renaming directory. "Perverted"
2333 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2334 * Problems:
2335 * a) we can get into loop creation. Check is done in is_subdir().
2336 * b) race potential - two innocent renames can create a loop together.
2337 * That's where 4.4 screws up. Current fix: serialization on
Arjan van de Vena11f3a02006-03-23 03:00:33 -08002338 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
Linus Torvalds1da177e2005-04-16 15:20:36 -07002339 * story.
2340 * c) we have to lock _three_ objects - parents and victim (if it exists).
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002341 * And that - after we got ->i_mutex on parents (until then we don't know
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342 * whether the target exists). Solution: try to be smart with locking
2343 * order for inodes. We rely on the fact that tree topology may change
Arjan van de Vena11f3a02006-03-23 03:00:33 -08002344 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345 * move will be locked. Thus we can rank directories by the tree
2346 * (ancestors first) and rank all non-directories after them.
2347 * That works since everybody except rename does "lock parent, lookup,
Arjan van de Vena11f3a02006-03-23 03:00:33 -08002348 * lock child" and rename is under ->s_vfs_rename_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349 * HOWEVER, it relies on the assumption that any object with ->lookup()
2350 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2351 * we'd better make sure that there's no link(2) for them.
2352 * d) some filesystems don't support opened-but-unlinked directories,
2353 * either because of layout or because they are not ready to deal with
2354 * all cases correctly. The latter will be fixed (taking this sort of
2355 * stuff into VFS), but the former is not going away. Solution: the same
2356 * trick as in rmdir().
2357 * e) conversion from fhandle to dentry may come in the wrong moment - when
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002358 * we are removing the target. Solution: we will have to grab ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002360 * ->i_mutex on parents, which works but leads to some truely excessive
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361 * locking].
2362 */
Adrian Bunk75c96f82005-05-05 16:16:09 -07002363static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2364 struct inode *new_dir, struct dentry *new_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365{
2366 int error = 0;
2367 struct inode *target;
2368
2369 /*
2370 * If we are going to change the parent - check write permissions,
2371 * we'll need to flip '..'.
2372 */
2373 if (new_dir != old_dir) {
2374 error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
2375 if (error)
2376 return error;
2377 }
2378
2379 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2380 if (error)
2381 return error;
2382
2383 target = new_dentry->d_inode;
2384 if (target) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002385 mutex_lock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002386 dentry_unhash(new_dentry);
2387 }
2388 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2389 error = -EBUSY;
2390 else
2391 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2392 if (target) {
2393 if (!error)
2394 target->i_flags |= S_DEAD;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002395 mutex_unlock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002396 if (d_unhashed(new_dentry))
2397 d_rehash(new_dentry);
2398 dput(new_dentry);
2399 }
Stephen Smalleye31e14e2005-09-09 13:01:45 -07002400 if (!error)
Mark Fasheh349457c2006-09-08 14:22:21 -07002401 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2402 d_move(old_dentry,new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002403 return error;
2404}
2405
Adrian Bunk75c96f82005-05-05 16:16:09 -07002406static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2407 struct inode *new_dir, struct dentry *new_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002408{
2409 struct inode *target;
2410 int error;
2411
2412 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2413 if (error)
2414 return error;
2415
2416 dget(new_dentry);
2417 target = new_dentry->d_inode;
2418 if (target)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002419 mutex_lock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002420 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2421 error = -EBUSY;
2422 else
2423 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2424 if (!error) {
Mark Fasheh349457c2006-09-08 14:22:21 -07002425 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426 d_move(old_dentry, new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 }
2428 if (target)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002429 mutex_unlock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002430 dput(new_dentry);
2431 return error;
2432}
2433
2434int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2435 struct inode *new_dir, struct dentry *new_dentry)
2436{
2437 int error;
2438 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
Robert Love0eeca282005-07-12 17:06:03 -04002439 const char *old_name;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440
2441 if (old_dentry->d_inode == new_dentry->d_inode)
2442 return 0;
2443
2444 error = may_delete(old_dir, old_dentry, is_dir);
2445 if (error)
2446 return error;
2447
2448 if (!new_dentry->d_inode)
2449 error = may_create(new_dir, new_dentry, NULL);
2450 else
2451 error = may_delete(new_dir, new_dentry, is_dir);
2452 if (error)
2453 return error;
2454
2455 if (!old_dir->i_op || !old_dir->i_op->rename)
2456 return -EPERM;
2457
2458 DQUOT_INIT(old_dir);
2459 DQUOT_INIT(new_dir);
2460
Robert Love0eeca282005-07-12 17:06:03 -04002461 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
2462
Linus Torvalds1da177e2005-04-16 15:20:36 -07002463 if (is_dir)
2464 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2465 else
2466 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2467 if (!error) {
Robert Love0eeca282005-07-12 17:06:03 -04002468 const char *new_name = old_dentry->d_name.name;
John McCutchan89204c42005-08-15 12:13:28 -04002469 fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
2470 new_dentry->d_inode, old_dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002471 }
Robert Love0eeca282005-07-12 17:06:03 -04002472 fsnotify_oldname_free(old_name);
2473
Linus Torvalds1da177e2005-04-16 15:20:36 -07002474 return error;
2475}
2476
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002477static int do_rename(int olddfd, const char *oldname,
2478 int newdfd, const char *newname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002479{
2480 int error = 0;
2481 struct dentry * old_dir, * new_dir;
2482 struct dentry * old_dentry, *new_dentry;
2483 struct dentry * trap;
2484 struct nameidata oldnd, newnd;
2485
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002486 error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487 if (error)
2488 goto exit;
2489
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002490 error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002491 if (error)
2492 goto exit1;
2493
2494 error = -EXDEV;
2495 if (oldnd.mnt != newnd.mnt)
2496 goto exit2;
2497
2498 old_dir = oldnd.dentry;
2499 error = -EBUSY;
2500 if (oldnd.last_type != LAST_NORM)
2501 goto exit2;
2502
2503 new_dir = newnd.dentry;
2504 if (newnd.last_type != LAST_NORM)
2505 goto exit2;
2506
2507 trap = lock_rename(new_dir, old_dir);
2508
Christoph Hellwig49705b72005-11-08 21:35:06 -08002509 old_dentry = lookup_hash(&oldnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510 error = PTR_ERR(old_dentry);
2511 if (IS_ERR(old_dentry))
2512 goto exit3;
2513 /* source must exist */
2514 error = -ENOENT;
2515 if (!old_dentry->d_inode)
2516 goto exit4;
2517 /* unless the source is a directory trailing slashes give -ENOTDIR */
2518 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2519 error = -ENOTDIR;
2520 if (oldnd.last.name[oldnd.last.len])
2521 goto exit4;
2522 if (newnd.last.name[newnd.last.len])
2523 goto exit4;
2524 }
2525 /* source should not be ancestor of target */
2526 error = -EINVAL;
2527 if (old_dentry == trap)
2528 goto exit4;
Christoph Hellwig49705b72005-11-08 21:35:06 -08002529 new_dentry = lookup_hash(&newnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002530 error = PTR_ERR(new_dentry);
2531 if (IS_ERR(new_dentry))
2532 goto exit4;
2533 /* target should not be an ancestor of source */
2534 error = -ENOTEMPTY;
2535 if (new_dentry == trap)
2536 goto exit5;
2537
2538 error = vfs_rename(old_dir->d_inode, old_dentry,
2539 new_dir->d_inode, new_dentry);
2540exit5:
2541 dput(new_dentry);
2542exit4:
2543 dput(old_dentry);
2544exit3:
2545 unlock_rename(new_dir, old_dir);
2546exit2:
2547 path_release(&newnd);
2548exit1:
2549 path_release(&oldnd);
2550exit:
2551 return error;
2552}
2553
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002554asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
2555 int newdfd, const char __user *newname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002556{
2557 int error;
2558 char * from;
2559 char * to;
2560
2561 from = getname(oldname);
2562 if(IS_ERR(from))
2563 return PTR_ERR(from);
2564 to = getname(newname);
2565 error = PTR_ERR(to);
2566 if (!IS_ERR(to)) {
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002567 error = do_rename(olddfd, from, newdfd, to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 putname(to);
2569 }
2570 putname(from);
2571 return error;
2572}
2573
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002574asmlinkage long sys_rename(const char __user *oldname, const char __user *newname)
2575{
2576 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
2577}
2578
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2580{
2581 int len;
2582
2583 len = PTR_ERR(link);
2584 if (IS_ERR(link))
2585 goto out;
2586
2587 len = strlen(link);
2588 if (len > (unsigned) buflen)
2589 len = buflen;
2590 if (copy_to_user(buffer, link, len))
2591 len = -EFAULT;
2592out:
2593 return len;
2594}
2595
2596/*
2597 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2598 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2599 * using) it for any given inode is up to filesystem.
2600 */
2601int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2602{
2603 struct nameidata nd;
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002604 void *cookie;
2605
Linus Torvalds1da177e2005-04-16 15:20:36 -07002606 nd.depth = 0;
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002607 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
2608 if (!IS_ERR(cookie)) {
2609 int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002610 if (dentry->d_inode->i_op->put_link)
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002611 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
2612 cookie = ERR_PTR(res);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002613 }
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002614 return PTR_ERR(cookie);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002615}
2616
2617int vfs_follow_link(struct nameidata *nd, const char *link)
2618{
2619 return __vfs_follow_link(nd, link);
2620}
2621
2622/* get the link contents into pagecache */
2623static char *page_getlink(struct dentry * dentry, struct page **ppage)
2624{
2625 struct page * page;
2626 struct address_space *mapping = dentry->d_inode->i_mapping;
Pekka Enberg090d2b12006-06-23 02:05:08 -07002627 page = read_mapping_page(mapping, 0, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002628 if (IS_ERR(page))
2629 goto sync_fail;
2630 wait_on_page_locked(page);
2631 if (!PageUptodate(page))
2632 goto async_fail;
2633 *ppage = page;
2634 return kmap(page);
2635
2636async_fail:
2637 page_cache_release(page);
2638 return ERR_PTR(-EIO);
2639
2640sync_fail:
2641 return (char*)page;
2642}
2643
2644int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2645{
2646 struct page *page = NULL;
2647 char *s = page_getlink(dentry, &page);
2648 int res = vfs_readlink(dentry,buffer,buflen,s);
2649 if (page) {
2650 kunmap(page);
2651 page_cache_release(page);
2652 }
2653 return res;
2654}
2655
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002656void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002657{
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002658 struct page *page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002659 nd_set_link(nd, page_getlink(dentry, &page));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002660 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661}
2662
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002663void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002664{
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002665 struct page *page = cookie;
2666
2667 if (page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668 kunmap(page);
2669 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002670 }
2671}
2672
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002673int __page_symlink(struct inode *inode, const char *symname, int len,
2674 gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002675{
2676 struct address_space *mapping = inode->i_mapping;
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002677 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002678 int err = -ENOMEM;
2679 char *kaddr;
2680
NeilBrown7e53cac2006-03-25 03:07:57 -08002681retry:
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002682 page = find_or_create_page(mapping, 0, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002683 if (!page)
2684 goto fail;
2685 err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
NeilBrown7e53cac2006-03-25 03:07:57 -08002686 if (err == AOP_TRUNCATED_PAGE) {
2687 page_cache_release(page);
2688 goto retry;
2689 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002690 if (err)
2691 goto fail_map;
2692 kaddr = kmap_atomic(page, KM_USER0);
2693 memcpy(kaddr, symname, len-1);
2694 kunmap_atomic(kaddr, KM_USER0);
NeilBrown7e53cac2006-03-25 03:07:57 -08002695 err = mapping->a_ops->commit_write(NULL, page, 0, len-1);
2696 if (err == AOP_TRUNCATED_PAGE) {
2697 page_cache_release(page);
2698 goto retry;
2699 }
2700 if (err)
2701 goto fail_map;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002702 /*
2703 * Notice that we are _not_ going to block here - end of page is
2704 * unmapped, so this will only try to map the rest of page, see
2705 * that it is unmapped (typically even will not look into inode -
2706 * ->i_size will be enough for everything) and zero it out.
2707 * OTOH it's obviously correct and should make the page up-to-date.
2708 */
2709 if (!PageUptodate(page)) {
2710 err = mapping->a_ops->readpage(NULL, page);
NeilBrown7e53cac2006-03-25 03:07:57 -08002711 if (err != AOP_TRUNCATED_PAGE)
2712 wait_on_page_locked(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002713 } else {
2714 unlock_page(page);
2715 }
2716 page_cache_release(page);
2717 if (err < 0)
2718 goto fail;
2719 mark_inode_dirty(inode);
2720 return 0;
2721fail_map:
2722 unlock_page(page);
2723 page_cache_release(page);
2724fail:
2725 return err;
2726}
2727
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002728int page_symlink(struct inode *inode, const char *symname, int len)
2729{
2730 return __page_symlink(inode, symname, len,
2731 mapping_gfp_mask(inode->i_mapping));
2732}
2733
Linus Torvalds1da177e2005-04-16 15:20:36 -07002734struct inode_operations page_symlink_inode_operations = {
2735 .readlink = generic_readlink,
2736 .follow_link = page_follow_link_light,
2737 .put_link = page_put_link,
2738};
2739
2740EXPORT_SYMBOL(__user_walk);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002741EXPORT_SYMBOL(__user_walk_fd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002742EXPORT_SYMBOL(follow_down);
2743EXPORT_SYMBOL(follow_up);
2744EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2745EXPORT_SYMBOL(getname);
2746EXPORT_SYMBOL(lock_rename);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002747EXPORT_SYMBOL(lookup_one_len);
2748EXPORT_SYMBOL(page_follow_link_light);
2749EXPORT_SYMBOL(page_put_link);
2750EXPORT_SYMBOL(page_readlink);
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002751EXPORT_SYMBOL(__page_symlink);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002752EXPORT_SYMBOL(page_symlink);
2753EXPORT_SYMBOL(page_symlink_inode_operations);
2754EXPORT_SYMBOL(path_lookup);
2755EXPORT_SYMBOL(path_release);
2756EXPORT_SYMBOL(path_walk);
2757EXPORT_SYMBOL(permission);
Christoph Hellwige4543ed2005-11-08 21:35:04 -08002758EXPORT_SYMBOL(vfs_permission);
Christoph Hellwig8c744fb2005-11-08 21:35:04 -08002759EXPORT_SYMBOL(file_permission);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002760EXPORT_SYMBOL(unlock_rename);
2761EXPORT_SYMBOL(vfs_create);
2762EXPORT_SYMBOL(vfs_follow_link);
2763EXPORT_SYMBOL(vfs_link);
2764EXPORT_SYMBOL(vfs_mkdir);
2765EXPORT_SYMBOL(vfs_mknod);
2766EXPORT_SYMBOL(generic_permission);
2767EXPORT_SYMBOL(vfs_readlink);
2768EXPORT_SYMBOL(vfs_rename);
2769EXPORT_SYMBOL(vfs_rmdir);
2770EXPORT_SYMBOL(vfs_symlink);
2771EXPORT_SYMBOL(vfs_unlink);
2772EXPORT_SYMBOL(dentry_unhash);
2773EXPORT_SYMBOL(generic_readlink);