Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/namei.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Some corrections by tytso. | |
9 | */ | |
10 | ||
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname | |
12 | * lookup logic. | |
13 | */ | |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. | |
15 | */ | |
16 | ||
17 | #include <linux/init.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/fs.h> | |
21 | #include <linux/namei.h> | |
22 | #include <linux/quotaops.h> | |
23 | #include <linux/pagemap.h> | |
0eeca283 | 24 | #include <linux/fsnotify.h> |
1da177e4 LT |
25 | #include <linux/smp_lock.h> |
26 | #include <linux/personality.h> | |
27 | #include <linux/security.h> | |
28 | #include <linux/syscalls.h> | |
29 | #include <linux/mount.h> | |
30 | #include <linux/audit.h> | |
834f2a4a | 31 | #include <linux/file.h> |
1da177e4 LT |
32 | #include <asm/namei.h> |
33 | #include <asm/uaccess.h> | |
34 | ||
35 | #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) | |
36 | ||
37 | /* [Feb-1997 T. Schoebel-Theuer] | |
38 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
39 | * were necessary because of omirr. The reason is that omirr needs | |
40 | * to know the _real_ pathname, not the user-supplied one, in case | |
41 | * of symlinks (and also when transname replacements occur). | |
42 | * | |
43 | * The new code replaces the old recursive symlink resolution with | |
44 | * an iterative one (in case of non-nested symlink chains). It does | |
45 | * this with calls to <fs>_follow_link(). | |
46 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
47 | * replaced with a single function lookup_dentry() that can handle all | |
48 | * the special cases of the former code. | |
49 | * | |
50 | * With the new dcache, the pathname is stored at each inode, at least as | |
51 | * long as the refcount of the inode is positive. As a side effect, the | |
52 | * size of the dcache depends on the inode cache and thus is dynamic. | |
53 | * | |
54 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
55 | * resolution to correspond with current state of the code. | |
56 | * | |
57 | * Note that the symlink resolution is not *completely* iterative. | |
58 | * There is still a significant amount of tail- and mid- recursion in | |
59 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
60 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
61 | * may return different results than <fs>_follow_link(). Many virtual | |
62 | * filesystems (including /proc) exhibit this behavior. | |
63 | */ | |
64 | ||
65 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
66 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
67 | * and the name already exists in form of a symlink, try to create the new | |
68 | * name indicated by the symlink. The old code always complained that the | |
69 | * name already exists, due to not following the symlink even if its target | |
70 | * is nonexistent. The new semantics affects also mknod() and link() when | |
71 | * the name is a symlink pointing to a non-existant name. | |
72 | * | |
73 | * I don't know which semantics is the right one, since I have no access | |
74 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
75 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
76 | * "old" one. Personally, I think the new semantics is much more logical. | |
77 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
78 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
79 | * and in the old Linux semantics. | |
80 | */ | |
81 | ||
82 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
83 | * semantics. See the comments in "open_namei" and "do_link" below. | |
84 | * | |
85 | * [10-Sep-98 Alan Modra] Another symlink change. | |
86 | */ | |
87 | ||
88 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
89 | * inside the path - always follow. | |
90 | * in the last component in creation/removal/renaming - never follow. | |
91 | * if LOOKUP_FOLLOW passed - follow. | |
92 | * if the pathname has trailing slashes - follow. | |
93 | * otherwise - don't follow. | |
94 | * (applied in that order). | |
95 | * | |
96 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
97 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
98 | * During the 2.4 we need to fix the userland stuff depending on it - | |
99 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
100 | * XEmacs seems to be relying on it... | |
101 | */ | |
102 | /* | |
103 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
104 | * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives | |
105 | * any extra contention... | |
106 | */ | |
107 | ||
108 | /* In order to reduce some races, while at the same time doing additional | |
109 | * checking and hopefully speeding things up, we copy filenames to the | |
110 | * kernel data space before using them.. | |
111 | * | |
112 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
113 | * PATH_MAX includes the nul terminator --RR. | |
114 | */ | |
115 | static inline int do_getname(const char __user *filename, char *page) | |
116 | { | |
117 | int retval; | |
118 | unsigned long len = PATH_MAX; | |
119 | ||
120 | if (!segment_eq(get_fs(), KERNEL_DS)) { | |
121 | if ((unsigned long) filename >= TASK_SIZE) | |
122 | return -EFAULT; | |
123 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) | |
124 | len = TASK_SIZE - (unsigned long) filename; | |
125 | } | |
126 | ||
127 | retval = strncpy_from_user(page, filename, len); | |
128 | if (retval > 0) { | |
129 | if (retval < len) | |
130 | return 0; | |
131 | return -ENAMETOOLONG; | |
132 | } else if (!retval) | |
133 | retval = -ENOENT; | |
134 | return retval; | |
135 | } | |
136 | ||
137 | char * getname(const char __user * filename) | |
138 | { | |
139 | char *tmp, *result; | |
140 | ||
141 | result = ERR_PTR(-ENOMEM); | |
142 | tmp = __getname(); | |
143 | if (tmp) { | |
144 | int retval = do_getname(filename, tmp); | |
145 | ||
146 | result = tmp; | |
147 | if (retval < 0) { | |
148 | __putname(tmp); | |
149 | result = ERR_PTR(retval); | |
150 | } | |
151 | } | |
152 | audit_getname(result); | |
153 | return result; | |
154 | } | |
155 | ||
156 | #ifdef CONFIG_AUDITSYSCALL | |
157 | void putname(const char *name) | |
158 | { | |
159 | if (unlikely(current->audit_context)) | |
160 | audit_putname(name); | |
161 | else | |
162 | __putname(name); | |
163 | } | |
164 | EXPORT_SYMBOL(putname); | |
165 | #endif | |
166 | ||
167 | ||
168 | /** | |
169 | * generic_permission - check for access rights on a Posix-like filesystem | |
170 | * @inode: inode to check access rights for | |
171 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
172 | * @check_acl: optional callback to check for Posix ACLs | |
173 | * | |
174 | * Used to check for read/write/execute permissions on a file. | |
175 | * We use "fsuid" for this, letting us set arbitrary permissions | |
176 | * for filesystem access without changing the "normal" uids which | |
177 | * are used for other things.. | |
178 | */ | |
179 | int generic_permission(struct inode *inode, int mask, | |
180 | int (*check_acl)(struct inode *inode, int mask)) | |
181 | { | |
182 | umode_t mode = inode->i_mode; | |
183 | ||
184 | if (current->fsuid == inode->i_uid) | |
185 | mode >>= 6; | |
186 | else { | |
187 | if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { | |
188 | int error = check_acl(inode, mask); | |
189 | if (error == -EACCES) | |
190 | goto check_capabilities; | |
191 | else if (error != -EAGAIN) | |
192 | return error; | |
193 | } | |
194 | ||
195 | if (in_group_p(inode->i_gid)) | |
196 | mode >>= 3; | |
197 | } | |
198 | ||
199 | /* | |
200 | * If the DACs are ok we don't need any capability check. | |
201 | */ | |
202 | if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)) | |
203 | return 0; | |
204 | ||
205 | check_capabilities: | |
206 | /* | |
207 | * Read/write DACs are always overridable. | |
208 | * Executable DACs are overridable if at least one exec bit is set. | |
209 | */ | |
210 | if (!(mask & MAY_EXEC) || | |
211 | (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) | |
212 | if (capable(CAP_DAC_OVERRIDE)) | |
213 | return 0; | |
214 | ||
215 | /* | |
216 | * Searching includes executable on directories, else just read. | |
217 | */ | |
218 | if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) | |
219 | if (capable(CAP_DAC_READ_SEARCH)) | |
220 | return 0; | |
221 | ||
222 | return -EACCES; | |
223 | } | |
224 | ||
225 | int permission(struct inode *inode, int mask, struct nameidata *nd) | |
226 | { | |
227 | int retval, submask; | |
228 | ||
229 | if (mask & MAY_WRITE) { | |
230 | umode_t mode = inode->i_mode; | |
231 | ||
232 | /* | |
233 | * Nobody gets write access to a read-only fs. | |
234 | */ | |
235 | if (IS_RDONLY(inode) && | |
236 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
237 | return -EROFS; | |
238 | ||
239 | /* | |
240 | * Nobody gets write access to an immutable file. | |
241 | */ | |
242 | if (IS_IMMUTABLE(inode)) | |
243 | return -EACCES; | |
244 | } | |
245 | ||
246 | ||
247 | /* Ordinary permission routines do not understand MAY_APPEND. */ | |
248 | submask = mask & ~MAY_APPEND; | |
249 | if (inode->i_op && inode->i_op->permission) | |
250 | retval = inode->i_op->permission(inode, submask, nd); | |
251 | else | |
252 | retval = generic_permission(inode, submask, NULL); | |
253 | if (retval) | |
254 | return retval; | |
255 | ||
256 | return security_inode_permission(inode, mask, nd); | |
257 | } | |
258 | ||
e4543edd CH |
259 | /** |
260 | * vfs_permission - check for access rights to a given path | |
261 | * @nd: lookup result that describes the path | |
262 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
263 | * | |
264 | * Used to check for read/write/execute permissions on a path. | |
265 | * We use "fsuid" for this, letting us set arbitrary permissions | |
266 | * for filesystem access without changing the "normal" uids which | |
267 | * are used for other things. | |
268 | */ | |
269 | int vfs_permission(struct nameidata *nd, int mask) | |
270 | { | |
271 | return permission(nd->dentry->d_inode, mask, nd); | |
272 | } | |
273 | ||
8c744fb8 CH |
274 | /** |
275 | * file_permission - check for additional access rights to a given file | |
276 | * @file: file to check access rights for | |
277 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
278 | * | |
279 | * Used to check for read/write/execute permissions on an already opened | |
280 | * file. | |
281 | * | |
282 | * Note: | |
283 | * Do not use this function in new code. All access checks should | |
284 | * be done using vfs_permission(). | |
285 | */ | |
286 | int file_permission(struct file *file, int mask) | |
287 | { | |
288 | return permission(file->f_dentry->d_inode, mask, NULL); | |
289 | } | |
290 | ||
1da177e4 LT |
291 | /* |
292 | * get_write_access() gets write permission for a file. | |
293 | * put_write_access() releases this write permission. | |
294 | * This is used for regular files. | |
295 | * We cannot support write (and maybe mmap read-write shared) accesses and | |
296 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode | |
297 | * can have the following values: | |
298 | * 0: no writers, no VM_DENYWRITE mappings | |
299 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist | |
300 | * > 0: (i_writecount) users are writing to the file. | |
301 | * | |
302 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe | |
303 | * except for the cases where we don't hold i_writecount yet. Then we need to | |
304 | * use {get,deny}_write_access() - these functions check the sign and refuse | |
305 | * to do the change if sign is wrong. Exclusion between them is provided by | |
306 | * the inode->i_lock spinlock. | |
307 | */ | |
308 | ||
309 | int get_write_access(struct inode * inode) | |
310 | { | |
311 | spin_lock(&inode->i_lock); | |
312 | if (atomic_read(&inode->i_writecount) < 0) { | |
313 | spin_unlock(&inode->i_lock); | |
314 | return -ETXTBSY; | |
315 | } | |
316 | atomic_inc(&inode->i_writecount); | |
317 | spin_unlock(&inode->i_lock); | |
318 | ||
319 | return 0; | |
320 | } | |
321 | ||
322 | int deny_write_access(struct file * file) | |
323 | { | |
324 | struct inode *inode = file->f_dentry->d_inode; | |
325 | ||
326 | spin_lock(&inode->i_lock); | |
327 | if (atomic_read(&inode->i_writecount) > 0) { | |
328 | spin_unlock(&inode->i_lock); | |
329 | return -ETXTBSY; | |
330 | } | |
331 | atomic_dec(&inode->i_writecount); | |
332 | spin_unlock(&inode->i_lock); | |
333 | ||
334 | return 0; | |
335 | } | |
336 | ||
337 | void path_release(struct nameidata *nd) | |
338 | { | |
339 | dput(nd->dentry); | |
340 | mntput(nd->mnt); | |
341 | } | |
342 | ||
343 | /* | |
344 | * umount() mustn't call path_release()/mntput() as that would clear | |
345 | * mnt_expiry_mark | |
346 | */ | |
347 | void path_release_on_umount(struct nameidata *nd) | |
348 | { | |
349 | dput(nd->dentry); | |
751c404b | 350 | mntput_no_expire(nd->mnt); |
1da177e4 LT |
351 | } |
352 | ||
834f2a4a TM |
353 | /** |
354 | * release_open_intent - free up open intent resources | |
355 | * @nd: pointer to nameidata | |
356 | */ | |
357 | void release_open_intent(struct nameidata *nd) | |
358 | { | |
359 | if (nd->intent.open.file->f_dentry == NULL) | |
360 | put_filp(nd->intent.open.file); | |
361 | else | |
362 | fput(nd->intent.open.file); | |
363 | } | |
364 | ||
1da177e4 LT |
365 | /* |
366 | * Internal lookup() using the new generic dcache. | |
367 | * SMP-safe | |
368 | */ | |
369 | static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
370 | { | |
371 | struct dentry * dentry = __d_lookup(parent, name); | |
372 | ||
373 | /* lockess __d_lookup may fail due to concurrent d_move() | |
374 | * in some unrelated directory, so try with d_lookup | |
375 | */ | |
376 | if (!dentry) | |
377 | dentry = d_lookup(parent, name); | |
378 | ||
379 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) { | |
380 | if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) { | |
381 | dput(dentry); | |
382 | dentry = NULL; | |
383 | } | |
384 | } | |
385 | return dentry; | |
386 | } | |
387 | ||
388 | /* | |
389 | * Short-cut version of permission(), for calling by | |
390 | * path_walk(), when dcache lock is held. Combines parts | |
391 | * of permission() and generic_permission(), and tests ONLY for | |
392 | * MAY_EXEC permission. | |
393 | * | |
394 | * If appropriate, check DAC only. If not appropriate, or | |
395 | * short-cut DAC fails, then call permission() to do more | |
396 | * complete permission check. | |
397 | */ | |
398 | static inline int exec_permission_lite(struct inode *inode, | |
399 | struct nameidata *nd) | |
400 | { | |
401 | umode_t mode = inode->i_mode; | |
402 | ||
403 | if (inode->i_op && inode->i_op->permission) | |
404 | return -EAGAIN; | |
405 | ||
406 | if (current->fsuid == inode->i_uid) | |
407 | mode >>= 6; | |
408 | else if (in_group_p(inode->i_gid)) | |
409 | mode >>= 3; | |
410 | ||
411 | if (mode & MAY_EXEC) | |
412 | goto ok; | |
413 | ||
414 | if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) | |
415 | goto ok; | |
416 | ||
417 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) | |
418 | goto ok; | |
419 | ||
420 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) | |
421 | goto ok; | |
422 | ||
423 | return -EACCES; | |
424 | ok: | |
425 | return security_inode_permission(inode, MAY_EXEC, nd); | |
426 | } | |
427 | ||
428 | /* | |
429 | * This is called when everything else fails, and we actually have | |
430 | * to go to the low-level filesystem to find out what we should do.. | |
431 | * | |
432 | * We get the directory semaphore, and after getting that we also | |
433 | * make sure that nobody added the entry to the dcache in the meantime.. | |
434 | * SMP-safe | |
435 | */ | |
436 | static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
437 | { | |
438 | struct dentry * result; | |
439 | struct inode *dir = parent->d_inode; | |
440 | ||
441 | down(&dir->i_sem); | |
442 | /* | |
443 | * First re-do the cached lookup just in case it was created | |
444 | * while we waited for the directory semaphore.. | |
445 | * | |
446 | * FIXME! This could use version numbering or similar to | |
447 | * avoid unnecessary cache lookups. | |
448 | * | |
449 | * The "dcache_lock" is purely to protect the RCU list walker | |
450 | * from concurrent renames at this point (we mustn't get false | |
451 | * negatives from the RCU list walk here, unlike the optimistic | |
452 | * fast walk). | |
453 | * | |
454 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup | |
455 | */ | |
456 | result = d_lookup(parent, name); | |
457 | if (!result) { | |
458 | struct dentry * dentry = d_alloc(parent, name); | |
459 | result = ERR_PTR(-ENOMEM); | |
460 | if (dentry) { | |
461 | result = dir->i_op->lookup(dir, dentry, nd); | |
462 | if (result) | |
463 | dput(dentry); | |
464 | else | |
465 | result = dentry; | |
466 | } | |
467 | up(&dir->i_sem); | |
468 | return result; | |
469 | } | |
470 | ||
471 | /* | |
472 | * Uhhuh! Nasty case: the cache was re-populated while | |
473 | * we waited on the semaphore. Need to revalidate. | |
474 | */ | |
475 | up(&dir->i_sem); | |
476 | if (result->d_op && result->d_op->d_revalidate) { | |
477 | if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) { | |
478 | dput(result); | |
479 | result = ERR_PTR(-ENOENT); | |
480 | } | |
481 | } | |
482 | return result; | |
483 | } | |
484 | ||
485 | static int __emul_lookup_dentry(const char *, struct nameidata *); | |
486 | ||
487 | /* SMP-safe */ | |
488 | static inline int | |
489 | walk_init_root(const char *name, struct nameidata *nd) | |
490 | { | |
491 | read_lock(¤t->fs->lock); | |
492 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { | |
493 | nd->mnt = mntget(current->fs->altrootmnt); | |
494 | nd->dentry = dget(current->fs->altroot); | |
495 | read_unlock(¤t->fs->lock); | |
496 | if (__emul_lookup_dentry(name,nd)) | |
497 | return 0; | |
498 | read_lock(¤t->fs->lock); | |
499 | } | |
500 | nd->mnt = mntget(current->fs->rootmnt); | |
501 | nd->dentry = dget(current->fs->root); | |
502 | read_unlock(¤t->fs->lock); | |
503 | return 1; | |
504 | } | |
505 | ||
506 | static inline int __vfs_follow_link(struct nameidata *nd, const char *link) | |
507 | { | |
508 | int res = 0; | |
509 | char *name; | |
510 | if (IS_ERR(link)) | |
511 | goto fail; | |
512 | ||
513 | if (*link == '/') { | |
514 | path_release(nd); | |
515 | if (!walk_init_root(link, nd)) | |
516 | /* weird __emul_prefix() stuff did it */ | |
517 | goto out; | |
518 | } | |
519 | res = link_path_walk(link, nd); | |
520 | out: | |
521 | if (nd->depth || res || nd->last_type!=LAST_NORM) | |
522 | return res; | |
523 | /* | |
524 | * If it is an iterative symlinks resolution in open_namei() we | |
525 | * have to copy the last component. And all that crap because of | |
526 | * bloody create() on broken symlinks. Furrfu... | |
527 | */ | |
528 | name = __getname(); | |
529 | if (unlikely(!name)) { | |
530 | path_release(nd); | |
531 | return -ENOMEM; | |
532 | } | |
533 | strcpy(name, nd->last.name); | |
534 | nd->last.name = name; | |
535 | return 0; | |
536 | fail: | |
537 | path_release(nd); | |
538 | return PTR_ERR(link); | |
539 | } | |
540 | ||
90ebe565 AV |
541 | struct path { |
542 | struct vfsmount *mnt; | |
543 | struct dentry *dentry; | |
544 | }; | |
545 | ||
cd4e91d3 | 546 | static inline int __do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
547 | { |
548 | int error; | |
cc314eef | 549 | void *cookie; |
cd4e91d3 | 550 | struct dentry *dentry = path->dentry; |
1da177e4 | 551 | |
d671a1cb | 552 | touch_atime(path->mnt, dentry); |
1da177e4 | 553 | nd_set_link(nd, NULL); |
cd4e91d3 | 554 | |
39ca6d49 AV |
555 | if (path->mnt == nd->mnt) |
556 | mntget(path->mnt); | |
cc314eef LT |
557 | cookie = dentry->d_inode->i_op->follow_link(dentry, nd); |
558 | error = PTR_ERR(cookie); | |
559 | if (!IS_ERR(cookie)) { | |
1da177e4 | 560 | char *s = nd_get_link(nd); |
cc314eef | 561 | error = 0; |
1da177e4 LT |
562 | if (s) |
563 | error = __vfs_follow_link(nd, s); | |
564 | if (dentry->d_inode->i_op->put_link) | |
cc314eef | 565 | dentry->d_inode->i_op->put_link(dentry, nd, cookie); |
1da177e4 | 566 | } |
cd4e91d3 AV |
567 | dput(dentry); |
568 | mntput(path->mnt); | |
1da177e4 LT |
569 | |
570 | return error; | |
571 | } | |
572 | ||
09dd17d3 MS |
573 | static inline void dput_path(struct path *path, struct nameidata *nd) |
574 | { | |
575 | dput(path->dentry); | |
576 | if (path->mnt != nd->mnt) | |
577 | mntput(path->mnt); | |
578 | } | |
579 | ||
580 | static inline void path_to_nameidata(struct path *path, struct nameidata *nd) | |
581 | { | |
582 | dput(nd->dentry); | |
583 | if (nd->mnt != path->mnt) | |
584 | mntput(nd->mnt); | |
585 | nd->mnt = path->mnt; | |
586 | nd->dentry = path->dentry; | |
587 | } | |
588 | ||
1da177e4 LT |
589 | /* |
590 | * This limits recursive symlink follows to 8, while | |
591 | * limiting consecutive symlinks to 40. | |
592 | * | |
593 | * Without that kind of total limit, nasty chains of consecutive | |
594 | * symlinks can cause almost arbitrarily long lookups. | |
595 | */ | |
90ebe565 | 596 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
597 | { |
598 | int err = -ELOOP; | |
599 | if (current->link_count >= MAX_NESTED_LINKS) | |
600 | goto loop; | |
601 | if (current->total_link_count >= 40) | |
602 | goto loop; | |
603 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); | |
604 | cond_resched(); | |
90ebe565 | 605 | err = security_inode_follow_link(path->dentry, nd); |
1da177e4 LT |
606 | if (err) |
607 | goto loop; | |
608 | current->link_count++; | |
609 | current->total_link_count++; | |
610 | nd->depth++; | |
cd4e91d3 | 611 | err = __do_follow_link(path, nd); |
839d9f93 AV |
612 | current->link_count--; |
613 | nd->depth--; | |
1da177e4 LT |
614 | return err; |
615 | loop: | |
09dd17d3 | 616 | dput_path(path, nd); |
839d9f93 | 617 | path_release(nd); |
1da177e4 LT |
618 | return err; |
619 | } | |
620 | ||
621 | int follow_up(struct vfsmount **mnt, struct dentry **dentry) | |
622 | { | |
623 | struct vfsmount *parent; | |
624 | struct dentry *mountpoint; | |
625 | spin_lock(&vfsmount_lock); | |
626 | parent=(*mnt)->mnt_parent; | |
627 | if (parent == *mnt) { | |
628 | spin_unlock(&vfsmount_lock); | |
629 | return 0; | |
630 | } | |
631 | mntget(parent); | |
632 | mountpoint=dget((*mnt)->mnt_mountpoint); | |
633 | spin_unlock(&vfsmount_lock); | |
634 | dput(*dentry); | |
635 | *dentry = mountpoint; | |
636 | mntput(*mnt); | |
637 | *mnt = parent; | |
638 | return 1; | |
639 | } | |
640 | ||
641 | /* no need for dcache_lock, as serialization is taken care in | |
642 | * namespace.c | |
643 | */ | |
463ffb2e AV |
644 | static int __follow_mount(struct path *path) |
645 | { | |
646 | int res = 0; | |
647 | while (d_mountpoint(path->dentry)) { | |
648 | struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); | |
649 | if (!mounted) | |
650 | break; | |
651 | dput(path->dentry); | |
652 | if (res) | |
653 | mntput(path->mnt); | |
654 | path->mnt = mounted; | |
655 | path->dentry = dget(mounted->mnt_root); | |
656 | res = 1; | |
657 | } | |
658 | return res; | |
659 | } | |
660 | ||
58c465eb | 661 | static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 | 662 | { |
1da177e4 LT |
663 | while (d_mountpoint(*dentry)) { |
664 | struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); | |
665 | if (!mounted) | |
666 | break; | |
58c465eb | 667 | dput(*dentry); |
1da177e4 LT |
668 | mntput(*mnt); |
669 | *mnt = mounted; | |
1da177e4 | 670 | *dentry = dget(mounted->mnt_root); |
1da177e4 | 671 | } |
1da177e4 LT |
672 | } |
673 | ||
674 | /* no need for dcache_lock, as serialization is taken care in | |
675 | * namespace.c | |
676 | */ | |
e13b210f | 677 | int follow_down(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 LT |
678 | { |
679 | struct vfsmount *mounted; | |
680 | ||
681 | mounted = lookup_mnt(*mnt, *dentry); | |
682 | if (mounted) { | |
e13b210f | 683 | dput(*dentry); |
1da177e4 LT |
684 | mntput(*mnt); |
685 | *mnt = mounted; | |
1da177e4 LT |
686 | *dentry = dget(mounted->mnt_root); |
687 | return 1; | |
688 | } | |
689 | return 0; | |
690 | } | |
691 | ||
58c465eb | 692 | static inline void follow_dotdot(struct nameidata *nd) |
1da177e4 LT |
693 | { |
694 | while(1) { | |
695 | struct vfsmount *parent; | |
58c465eb | 696 | struct dentry *old = nd->dentry; |
1da177e4 LT |
697 | |
698 | read_lock(¤t->fs->lock); | |
58c465eb AV |
699 | if (nd->dentry == current->fs->root && |
700 | nd->mnt == current->fs->rootmnt) { | |
1da177e4 LT |
701 | read_unlock(¤t->fs->lock); |
702 | break; | |
703 | } | |
704 | read_unlock(¤t->fs->lock); | |
705 | spin_lock(&dcache_lock); | |
58c465eb AV |
706 | if (nd->dentry != nd->mnt->mnt_root) { |
707 | nd->dentry = dget(nd->dentry->d_parent); | |
1da177e4 LT |
708 | spin_unlock(&dcache_lock); |
709 | dput(old); | |
710 | break; | |
711 | } | |
712 | spin_unlock(&dcache_lock); | |
713 | spin_lock(&vfsmount_lock); | |
58c465eb AV |
714 | parent = nd->mnt->mnt_parent; |
715 | if (parent == nd->mnt) { | |
1da177e4 LT |
716 | spin_unlock(&vfsmount_lock); |
717 | break; | |
718 | } | |
719 | mntget(parent); | |
58c465eb | 720 | nd->dentry = dget(nd->mnt->mnt_mountpoint); |
1da177e4 LT |
721 | spin_unlock(&vfsmount_lock); |
722 | dput(old); | |
58c465eb AV |
723 | mntput(nd->mnt); |
724 | nd->mnt = parent; | |
1da177e4 | 725 | } |
58c465eb | 726 | follow_mount(&nd->mnt, &nd->dentry); |
1da177e4 LT |
727 | } |
728 | ||
1da177e4 LT |
729 | /* |
730 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
731 | * small and for now I'd prefer to have fast path as straight as possible. | |
732 | * It _is_ time-critical. | |
733 | */ | |
734 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
735 | struct path *path) | |
736 | { | |
737 | struct vfsmount *mnt = nd->mnt; | |
738 | struct dentry *dentry = __d_lookup(nd->dentry, name); | |
739 | ||
740 | if (!dentry) | |
741 | goto need_lookup; | |
742 | if (dentry->d_op && dentry->d_op->d_revalidate) | |
743 | goto need_revalidate; | |
744 | done: | |
745 | path->mnt = mnt; | |
746 | path->dentry = dentry; | |
634ee701 | 747 | __follow_mount(path); |
1da177e4 LT |
748 | return 0; |
749 | ||
750 | need_lookup: | |
751 | dentry = real_lookup(nd->dentry, name, nd); | |
752 | if (IS_ERR(dentry)) | |
753 | goto fail; | |
754 | goto done; | |
755 | ||
756 | need_revalidate: | |
757 | if (dentry->d_op->d_revalidate(dentry, nd)) | |
758 | goto done; | |
759 | if (d_invalidate(dentry)) | |
760 | goto done; | |
761 | dput(dentry); | |
762 | goto need_lookup; | |
763 | ||
764 | fail: | |
765 | return PTR_ERR(dentry); | |
766 | } | |
767 | ||
768 | /* | |
769 | * Name resolution. | |
ea3834d9 PM |
770 | * This is the basic name resolution function, turning a pathname into |
771 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 772 | * |
ea3834d9 PM |
773 | * Returns 0 and nd will have valid dentry and mnt on success. |
774 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 LT |
775 | */ |
776 | static fastcall int __link_path_walk(const char * name, struct nameidata *nd) | |
777 | { | |
778 | struct path next; | |
779 | struct inode *inode; | |
780 | int err; | |
781 | unsigned int lookup_flags = nd->flags; | |
782 | ||
783 | while (*name=='/') | |
784 | name++; | |
785 | if (!*name) | |
786 | goto return_reval; | |
787 | ||
788 | inode = nd->dentry->d_inode; | |
789 | if (nd->depth) | |
790 | lookup_flags = LOOKUP_FOLLOW; | |
791 | ||
792 | /* At this point we know we have a real path component. */ | |
793 | for(;;) { | |
794 | unsigned long hash; | |
795 | struct qstr this; | |
796 | unsigned int c; | |
797 | ||
cdce5d6b | 798 | nd->flags |= LOOKUP_CONTINUE; |
1da177e4 | 799 | err = exec_permission_lite(inode, nd); |
e4543edd CH |
800 | if (err == -EAGAIN) |
801 | err = vfs_permission(nd, MAY_EXEC); | |
1da177e4 LT |
802 | if (err) |
803 | break; | |
804 | ||
805 | this.name = name; | |
806 | c = *(const unsigned char *)name; | |
807 | ||
808 | hash = init_name_hash(); | |
809 | do { | |
810 | name++; | |
811 | hash = partial_name_hash(c, hash); | |
812 | c = *(const unsigned char *)name; | |
813 | } while (c && (c != '/')); | |
814 | this.len = name - (const char *) this.name; | |
815 | this.hash = end_name_hash(hash); | |
816 | ||
817 | /* remove trailing slashes? */ | |
818 | if (!c) | |
819 | goto last_component; | |
820 | while (*++name == '/'); | |
821 | if (!*name) | |
822 | goto last_with_slashes; | |
823 | ||
824 | /* | |
825 | * "." and ".." are special - ".." especially so because it has | |
826 | * to be able to know about the current root directory and | |
827 | * parent relationships. | |
828 | */ | |
829 | if (this.name[0] == '.') switch (this.len) { | |
830 | default: | |
831 | break; | |
832 | case 2: | |
833 | if (this.name[1] != '.') | |
834 | break; | |
58c465eb | 835 | follow_dotdot(nd); |
1da177e4 LT |
836 | inode = nd->dentry->d_inode; |
837 | /* fallthrough */ | |
838 | case 1: | |
839 | continue; | |
840 | } | |
841 | /* | |
842 | * See if the low-level filesystem might want | |
843 | * to use its own hash.. | |
844 | */ | |
845 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { | |
846 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); | |
847 | if (err < 0) | |
848 | break; | |
849 | } | |
1da177e4 LT |
850 | /* This does the actual lookups.. */ |
851 | err = do_lookup(nd, &this, &next); | |
852 | if (err) | |
853 | break; | |
1da177e4 LT |
854 | |
855 | err = -ENOENT; | |
856 | inode = next.dentry->d_inode; | |
857 | if (!inode) | |
858 | goto out_dput; | |
859 | err = -ENOTDIR; | |
860 | if (!inode->i_op) | |
861 | goto out_dput; | |
862 | ||
863 | if (inode->i_op->follow_link) { | |
90ebe565 | 864 | err = do_follow_link(&next, nd); |
1da177e4 LT |
865 | if (err) |
866 | goto return_err; | |
867 | err = -ENOENT; | |
868 | inode = nd->dentry->d_inode; | |
869 | if (!inode) | |
870 | break; | |
871 | err = -ENOTDIR; | |
872 | if (!inode->i_op) | |
873 | break; | |
09dd17d3 MS |
874 | } else |
875 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
876 | err = -ENOTDIR; |
877 | if (!inode->i_op->lookup) | |
878 | break; | |
879 | continue; | |
880 | /* here ends the main loop */ | |
881 | ||
882 | last_with_slashes: | |
883 | lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
884 | last_component: | |
885 | nd->flags &= ~LOOKUP_CONTINUE; | |
886 | if (lookup_flags & LOOKUP_PARENT) | |
887 | goto lookup_parent; | |
888 | if (this.name[0] == '.') switch (this.len) { | |
889 | default: | |
890 | break; | |
891 | case 2: | |
892 | if (this.name[1] != '.') | |
893 | break; | |
58c465eb | 894 | follow_dotdot(nd); |
1da177e4 LT |
895 | inode = nd->dentry->d_inode; |
896 | /* fallthrough */ | |
897 | case 1: | |
898 | goto return_reval; | |
899 | } | |
900 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { | |
901 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); | |
902 | if (err < 0) | |
903 | break; | |
904 | } | |
905 | err = do_lookup(nd, &this, &next); | |
906 | if (err) | |
907 | break; | |
1da177e4 LT |
908 | inode = next.dentry->d_inode; |
909 | if ((lookup_flags & LOOKUP_FOLLOW) | |
910 | && inode && inode->i_op && inode->i_op->follow_link) { | |
90ebe565 | 911 | err = do_follow_link(&next, nd); |
1da177e4 LT |
912 | if (err) |
913 | goto return_err; | |
914 | inode = nd->dentry->d_inode; | |
09dd17d3 MS |
915 | } else |
916 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
917 | err = -ENOENT; |
918 | if (!inode) | |
919 | break; | |
920 | if (lookup_flags & LOOKUP_DIRECTORY) { | |
921 | err = -ENOTDIR; | |
922 | if (!inode->i_op || !inode->i_op->lookup) | |
923 | break; | |
924 | } | |
925 | goto return_base; | |
926 | lookup_parent: | |
927 | nd->last = this; | |
928 | nd->last_type = LAST_NORM; | |
929 | if (this.name[0] != '.') | |
930 | goto return_base; | |
931 | if (this.len == 1) | |
932 | nd->last_type = LAST_DOT; | |
933 | else if (this.len == 2 && this.name[1] == '.') | |
934 | nd->last_type = LAST_DOTDOT; | |
935 | else | |
936 | goto return_base; | |
937 | return_reval: | |
938 | /* | |
939 | * We bypassed the ordinary revalidation routines. | |
940 | * We may need to check the cached dentry for staleness. | |
941 | */ | |
942 | if (nd->dentry && nd->dentry->d_sb && | |
943 | (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { | |
944 | err = -ESTALE; | |
945 | /* Note: we do not d_invalidate() */ | |
946 | if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd)) | |
947 | break; | |
948 | } | |
949 | return_base: | |
950 | return 0; | |
951 | out_dput: | |
09dd17d3 | 952 | dput_path(&next, nd); |
1da177e4 LT |
953 | break; |
954 | } | |
955 | path_release(nd); | |
956 | return_err: | |
957 | return err; | |
958 | } | |
959 | ||
960 | /* | |
961 | * Wrapper to retry pathname resolution whenever the underlying | |
962 | * file system returns an ESTALE. | |
963 | * | |
964 | * Retry the whole path once, forcing real lookup requests | |
965 | * instead of relying on the dcache. | |
966 | */ | |
967 | int fastcall link_path_walk(const char *name, struct nameidata *nd) | |
968 | { | |
969 | struct nameidata save = *nd; | |
970 | int result; | |
971 | ||
972 | /* make sure the stuff we saved doesn't go away */ | |
973 | dget(save.dentry); | |
974 | mntget(save.mnt); | |
975 | ||
976 | result = __link_path_walk(name, nd); | |
977 | if (result == -ESTALE) { | |
978 | *nd = save; | |
979 | dget(nd->dentry); | |
980 | mntget(nd->mnt); | |
981 | nd->flags |= LOOKUP_REVAL; | |
982 | result = __link_path_walk(name, nd); | |
983 | } | |
984 | ||
985 | dput(save.dentry); | |
986 | mntput(save.mnt); | |
987 | ||
988 | return result; | |
989 | } | |
990 | ||
991 | int fastcall path_walk(const char * name, struct nameidata *nd) | |
992 | { | |
993 | current->total_link_count = 0; | |
994 | return link_path_walk(name, nd); | |
995 | } | |
996 | ||
ea3834d9 PM |
997 | /* |
998 | * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if | |
999 | * everything is done. Returns 0 and drops input nd, if lookup failed; | |
1000 | */ | |
1da177e4 LT |
1001 | static int __emul_lookup_dentry(const char *name, struct nameidata *nd) |
1002 | { | |
1003 | if (path_walk(name, nd)) | |
1004 | return 0; /* something went wrong... */ | |
1005 | ||
1006 | if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) { | |
1007 | struct dentry *old_dentry = nd->dentry; | |
1008 | struct vfsmount *old_mnt = nd->mnt; | |
1009 | struct qstr last = nd->last; | |
1010 | int last_type = nd->last_type; | |
1011 | /* | |
1012 | * NAME was not found in alternate root or it's a directory. Try to find | |
1013 | * it in the normal root: | |
1014 | */ | |
1015 | nd->last_type = LAST_ROOT; | |
1016 | read_lock(¤t->fs->lock); | |
1017 | nd->mnt = mntget(current->fs->rootmnt); | |
1018 | nd->dentry = dget(current->fs->root); | |
1019 | read_unlock(¤t->fs->lock); | |
1020 | if (path_walk(name, nd) == 0) { | |
1021 | if (nd->dentry->d_inode) { | |
1022 | dput(old_dentry); | |
1023 | mntput(old_mnt); | |
1024 | return 1; | |
1025 | } | |
1026 | path_release(nd); | |
1027 | } | |
1028 | nd->dentry = old_dentry; | |
1029 | nd->mnt = old_mnt; | |
1030 | nd->last = last; | |
1031 | nd->last_type = last_type; | |
1032 | } | |
1033 | return 1; | |
1034 | } | |
1035 | ||
1036 | void set_fs_altroot(void) | |
1037 | { | |
1038 | char *emul = __emul_prefix(); | |
1039 | struct nameidata nd; | |
1040 | struct vfsmount *mnt = NULL, *oldmnt; | |
1041 | struct dentry *dentry = NULL, *olddentry; | |
1042 | int err; | |
1043 | ||
1044 | if (!emul) | |
1045 | goto set_it; | |
1046 | err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); | |
1047 | if (!err) { | |
1048 | mnt = nd.mnt; | |
1049 | dentry = nd.dentry; | |
1050 | } | |
1051 | set_it: | |
1052 | write_lock(¤t->fs->lock); | |
1053 | oldmnt = current->fs->altrootmnt; | |
1054 | olddentry = current->fs->altroot; | |
1055 | current->fs->altrootmnt = mnt; | |
1056 | current->fs->altroot = dentry; | |
1057 | write_unlock(¤t->fs->lock); | |
1058 | if (olddentry) { | |
1059 | dput(olddentry); | |
1060 | mntput(oldmnt); | |
1061 | } | |
1062 | } | |
1063 | ||
ea3834d9 | 1064 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
1da177e4 LT |
1065 | int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd) |
1066 | { | |
ea3834d9 | 1067 | int retval = 0; |
1da177e4 LT |
1068 | |
1069 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
1070 | nd->flags = flags; | |
1071 | nd->depth = 0; | |
1072 | ||
1073 | read_lock(¤t->fs->lock); | |
1074 | if (*name=='/') { | |
1075 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { | |
1076 | nd->mnt = mntget(current->fs->altrootmnt); | |
1077 | nd->dentry = dget(current->fs->altroot); | |
1078 | read_unlock(¤t->fs->lock); | |
1079 | if (__emul_lookup_dentry(name,nd)) | |
ea3834d9 | 1080 | goto out; /* found in altroot */ |
1da177e4 LT |
1081 | read_lock(¤t->fs->lock); |
1082 | } | |
1083 | nd->mnt = mntget(current->fs->rootmnt); | |
1084 | nd->dentry = dget(current->fs->root); | |
1085 | } else { | |
1086 | nd->mnt = mntget(current->fs->pwdmnt); | |
1087 | nd->dentry = dget(current->fs->pwd); | |
1088 | } | |
1089 | read_unlock(¤t->fs->lock); | |
1090 | current->total_link_count = 0; | |
1091 | retval = link_path_walk(name, nd); | |
ea3834d9 | 1092 | out: |
1da177e4 LT |
1093 | if (unlikely(current->audit_context |
1094 | && nd && nd->dentry && nd->dentry->d_inode)) | |
ae7b961b | 1095 | audit_inode(name, nd->dentry->d_inode, flags); |
1da177e4 LT |
1096 | return retval; |
1097 | } | |
1098 | ||
834f2a4a TM |
1099 | static int __path_lookup_intent_open(const char *name, unsigned int lookup_flags, |
1100 | struct nameidata *nd, int open_flags, int create_mode) | |
1101 | { | |
1102 | struct file *filp = get_empty_filp(); | |
1103 | int err; | |
1104 | ||
1105 | if (filp == NULL) | |
1106 | return -ENFILE; | |
1107 | nd->intent.open.file = filp; | |
1108 | nd->intent.open.flags = open_flags; | |
1109 | nd->intent.open.create_mode = create_mode; | |
1110 | err = path_lookup(name, lookup_flags|LOOKUP_OPEN, nd); | |
1111 | if (IS_ERR(nd->intent.open.file)) { | |
1112 | if (err == 0) { | |
1113 | err = PTR_ERR(nd->intent.open.file); | |
1114 | path_release(nd); | |
1115 | } | |
1116 | } else if (err != 0) | |
1117 | release_open_intent(nd); | |
1118 | return err; | |
1119 | } | |
1120 | ||
1121 | /** | |
1122 | * path_lookup_open - lookup a file path with open intent | |
1123 | * @name: pointer to file name | |
1124 | * @lookup_flags: lookup intent flags | |
1125 | * @nd: pointer to nameidata | |
1126 | * @open_flags: open intent flags | |
1127 | */ | |
1128 | int path_lookup_open(const char *name, unsigned int lookup_flags, | |
1129 | struct nameidata *nd, int open_flags) | |
1130 | { | |
1131 | return __path_lookup_intent_open(name, lookup_flags, nd, | |
1132 | open_flags, 0); | |
1133 | } | |
1134 | ||
1135 | /** | |
1136 | * path_lookup_create - lookup a file path with open + create intent | |
1137 | * @name: pointer to file name | |
1138 | * @lookup_flags: lookup intent flags | |
1139 | * @nd: pointer to nameidata | |
1140 | * @open_flags: open intent flags | |
1141 | * @create_mode: create intent flags | |
1142 | */ | |
0ce6e62b AB |
1143 | static int path_lookup_create(const char *name, unsigned int lookup_flags, |
1144 | struct nameidata *nd, int open_flags, | |
1145 | int create_mode) | |
834f2a4a TM |
1146 | { |
1147 | return __path_lookup_intent_open(name, lookup_flags|LOOKUP_CREATE, nd, | |
1148 | open_flags, create_mode); | |
1149 | } | |
1150 | ||
1151 | int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, | |
1152 | struct nameidata *nd, int open_flags) | |
1153 | { | |
1154 | char *tmp = getname(name); | |
1155 | int err = PTR_ERR(tmp); | |
1156 | ||
1157 | if (!IS_ERR(tmp)) { | |
1158 | err = __path_lookup_intent_open(tmp, lookup_flags, nd, open_flags, 0); | |
1159 | putname(tmp); | |
1160 | } | |
1161 | return err; | |
1162 | } | |
1163 | ||
1da177e4 LT |
1164 | /* |
1165 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1166 | * needs parent already locked. Doesn't follow mounts. | |
1167 | * SMP-safe. | |
1168 | */ | |
1169 | static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd) | |
1170 | { | |
1171 | struct dentry * dentry; | |
1172 | struct inode *inode; | |
1173 | int err; | |
1174 | ||
1175 | inode = base->d_inode; | |
1176 | err = permission(inode, MAY_EXEC, nd); | |
1177 | dentry = ERR_PTR(err); | |
1178 | if (err) | |
1179 | goto out; | |
1180 | ||
1181 | /* | |
1182 | * See if the low-level filesystem might want | |
1183 | * to use its own hash.. | |
1184 | */ | |
1185 | if (base->d_op && base->d_op->d_hash) { | |
1186 | err = base->d_op->d_hash(base, name); | |
1187 | dentry = ERR_PTR(err); | |
1188 | if (err < 0) | |
1189 | goto out; | |
1190 | } | |
1191 | ||
1192 | dentry = cached_lookup(base, name, nd); | |
1193 | if (!dentry) { | |
1194 | struct dentry *new = d_alloc(base, name); | |
1195 | dentry = ERR_PTR(-ENOMEM); | |
1196 | if (!new) | |
1197 | goto out; | |
1198 | dentry = inode->i_op->lookup(inode, new, nd); | |
1199 | if (!dentry) | |
1200 | dentry = new; | |
1201 | else | |
1202 | dput(new); | |
1203 | } | |
1204 | out: | |
1205 | return dentry; | |
1206 | } | |
1207 | ||
49705b77 | 1208 | struct dentry * lookup_hash(struct nameidata *nd) |
1da177e4 | 1209 | { |
49705b77 | 1210 | return __lookup_hash(&nd->last, nd->dentry, nd); |
1da177e4 LT |
1211 | } |
1212 | ||
1213 | /* SMP-safe */ | |
1214 | struct dentry * lookup_one_len(const char * name, struct dentry * base, int len) | |
1215 | { | |
1216 | unsigned long hash; | |
1217 | struct qstr this; | |
1218 | unsigned int c; | |
1219 | ||
1220 | this.name = name; | |
1221 | this.len = len; | |
1222 | if (!len) | |
1223 | goto access; | |
1224 | ||
1225 | hash = init_name_hash(); | |
1226 | while (len--) { | |
1227 | c = *(const unsigned char *)name++; | |
1228 | if (c == '/' || c == '\0') | |
1229 | goto access; | |
1230 | hash = partial_name_hash(c, hash); | |
1231 | } | |
1232 | this.hash = end_name_hash(hash); | |
1233 | ||
49705b77 | 1234 | return __lookup_hash(&this, base, NULL); |
1da177e4 LT |
1235 | access: |
1236 | return ERR_PTR(-EACCES); | |
1237 | } | |
1238 | ||
1239 | /* | |
1240 | * namei() | |
1241 | * | |
1242 | * is used by most simple commands to get the inode of a specified name. | |
1243 | * Open, link etc use their own routines, but this is enough for things | |
1244 | * like 'chmod' etc. | |
1245 | * | |
1246 | * namei exists in two versions: namei/lnamei. The only difference is | |
1247 | * that namei follows links, while lnamei does not. | |
1248 | * SMP-safe | |
1249 | */ | |
1250 | int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) | |
1251 | { | |
1252 | char *tmp = getname(name); | |
1253 | int err = PTR_ERR(tmp); | |
1254 | ||
1255 | if (!IS_ERR(tmp)) { | |
1256 | err = path_lookup(tmp, flags, nd); | |
1257 | putname(tmp); | |
1258 | } | |
1259 | return err; | |
1260 | } | |
1261 | ||
1262 | /* | |
1263 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1264 | * minimal. | |
1265 | */ | |
1266 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1267 | { | |
1268 | if (!(dir->i_mode & S_ISVTX)) | |
1269 | return 0; | |
1270 | if (inode->i_uid == current->fsuid) | |
1271 | return 0; | |
1272 | if (dir->i_uid == current->fsuid) | |
1273 | return 0; | |
1274 | return !capable(CAP_FOWNER); | |
1275 | } | |
1276 | ||
1277 | /* | |
1278 | * Check whether we can remove a link victim from directory dir, check | |
1279 | * whether the type of victim is right. | |
1280 | * 1. We can't do it if dir is read-only (done in permission()) | |
1281 | * 2. We should have write and exec permissions on dir | |
1282 | * 3. We can't remove anything from append-only dir | |
1283 | * 4. We can't do anything with immutable dir (done in permission()) | |
1284 | * 5. If the sticky bit on dir is set we should either | |
1285 | * a. be owner of dir, or | |
1286 | * b. be owner of victim, or | |
1287 | * c. have CAP_FOWNER capability | |
1288 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1289 | * links pointing to it. | |
1290 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1291 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1292 | * 9. We can't remove a root or mountpoint. | |
1293 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1294 | * nfs_async_unlink(). | |
1295 | */ | |
1296 | static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir) | |
1297 | { | |
1298 | int error; | |
1299 | ||
1300 | if (!victim->d_inode) | |
1301 | return -ENOENT; | |
1302 | ||
1303 | BUG_ON(victim->d_parent->d_inode != dir); | |
1304 | ||
1305 | error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); | |
1306 | if (error) | |
1307 | return error; | |
1308 | if (IS_APPEND(dir)) | |
1309 | return -EPERM; | |
1310 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
1311 | IS_IMMUTABLE(victim->d_inode)) | |
1312 | return -EPERM; | |
1313 | if (isdir) { | |
1314 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1315 | return -ENOTDIR; | |
1316 | if (IS_ROOT(victim)) | |
1317 | return -EBUSY; | |
1318 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1319 | return -EISDIR; | |
1320 | if (IS_DEADDIR(dir)) | |
1321 | return -ENOENT; | |
1322 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1323 | return -EBUSY; | |
1324 | return 0; | |
1325 | } | |
1326 | ||
1327 | /* Check whether we can create an object with dentry child in directory | |
1328 | * dir. | |
1329 | * 1. We can't do it if child already exists (open has special treatment for | |
1330 | * this case, but since we are inlined it's OK) | |
1331 | * 2. We can't do it if dir is read-only (done in permission()) | |
1332 | * 3. We should have write and exec permissions on dir | |
1333 | * 4. We can't do it if dir is immutable (done in permission()) | |
1334 | */ | |
1335 | static inline int may_create(struct inode *dir, struct dentry *child, | |
1336 | struct nameidata *nd) | |
1337 | { | |
1338 | if (child->d_inode) | |
1339 | return -EEXIST; | |
1340 | if (IS_DEADDIR(dir)) | |
1341 | return -ENOENT; | |
1342 | return permission(dir,MAY_WRITE | MAY_EXEC, nd); | |
1343 | } | |
1344 | ||
1345 | /* | |
1da177e4 LT |
1346 | * O_DIRECTORY translates into forcing a directory lookup. |
1347 | */ | |
1348 | static inline int lookup_flags(unsigned int f) | |
1349 | { | |
1350 | unsigned long retval = LOOKUP_FOLLOW; | |
1351 | ||
1352 | if (f & O_NOFOLLOW) | |
1353 | retval &= ~LOOKUP_FOLLOW; | |
1354 | ||
1da177e4 LT |
1355 | if (f & O_DIRECTORY) |
1356 | retval |= LOOKUP_DIRECTORY; | |
1357 | ||
1358 | return retval; | |
1359 | } | |
1360 | ||
1361 | /* | |
1362 | * p1 and p2 should be directories on the same fs. | |
1363 | */ | |
1364 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1365 | { | |
1366 | struct dentry *p; | |
1367 | ||
1368 | if (p1 == p2) { | |
1369 | down(&p1->d_inode->i_sem); | |
1370 | return NULL; | |
1371 | } | |
1372 | ||
1373 | down(&p1->d_inode->i_sb->s_vfs_rename_sem); | |
1374 | ||
1375 | for (p = p1; p->d_parent != p; p = p->d_parent) { | |
1376 | if (p->d_parent == p2) { | |
1377 | down(&p2->d_inode->i_sem); | |
1378 | down(&p1->d_inode->i_sem); | |
1379 | return p; | |
1380 | } | |
1381 | } | |
1382 | ||
1383 | for (p = p2; p->d_parent != p; p = p->d_parent) { | |
1384 | if (p->d_parent == p1) { | |
1385 | down(&p1->d_inode->i_sem); | |
1386 | down(&p2->d_inode->i_sem); | |
1387 | return p; | |
1388 | } | |
1389 | } | |
1390 | ||
1391 | down(&p1->d_inode->i_sem); | |
1392 | down(&p2->d_inode->i_sem); | |
1393 | return NULL; | |
1394 | } | |
1395 | ||
1396 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1397 | { | |
1398 | up(&p1->d_inode->i_sem); | |
1399 | if (p1 != p2) { | |
1400 | up(&p2->d_inode->i_sem); | |
1401 | up(&p1->d_inode->i_sb->s_vfs_rename_sem); | |
1402 | } | |
1403 | } | |
1404 | ||
1405 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1406 | struct nameidata *nd) | |
1407 | { | |
1408 | int error = may_create(dir, dentry, nd); | |
1409 | ||
1410 | if (error) | |
1411 | return error; | |
1412 | ||
1413 | if (!dir->i_op || !dir->i_op->create) | |
1414 | return -EACCES; /* shouldn't it be ENOSYS? */ | |
1415 | mode &= S_IALLUGO; | |
1416 | mode |= S_IFREG; | |
1417 | error = security_inode_create(dir, dentry, mode); | |
1418 | if (error) | |
1419 | return error; | |
1420 | DQUOT_INIT(dir); | |
1421 | error = dir->i_op->create(dir, dentry, mode, nd); | |
a74574aa | 1422 | if (!error) |
0eeca283 | 1423 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
1424 | return error; |
1425 | } | |
1426 | ||
1427 | int may_open(struct nameidata *nd, int acc_mode, int flag) | |
1428 | { | |
1429 | struct dentry *dentry = nd->dentry; | |
1430 | struct inode *inode = dentry->d_inode; | |
1431 | int error; | |
1432 | ||
1433 | if (!inode) | |
1434 | return -ENOENT; | |
1435 | ||
1436 | if (S_ISLNK(inode->i_mode)) | |
1437 | return -ELOOP; | |
1438 | ||
1439 | if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE)) | |
1440 | return -EISDIR; | |
1441 | ||
e4543edd | 1442 | error = vfs_permission(nd, acc_mode); |
1da177e4 LT |
1443 | if (error) |
1444 | return error; | |
1445 | ||
1446 | /* | |
1447 | * FIFO's, sockets and device files are special: they don't | |
1448 | * actually live on the filesystem itself, and as such you | |
1449 | * can write to them even if the filesystem is read-only. | |
1450 | */ | |
1451 | if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { | |
1452 | flag &= ~O_TRUNC; | |
1453 | } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { | |
1454 | if (nd->mnt->mnt_flags & MNT_NODEV) | |
1455 | return -EACCES; | |
1456 | ||
1457 | flag &= ~O_TRUNC; | |
1458 | } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE)) | |
1459 | return -EROFS; | |
1460 | /* | |
1461 | * An append-only file must be opened in append mode for writing. | |
1462 | */ | |
1463 | if (IS_APPEND(inode)) { | |
1464 | if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) | |
1465 | return -EPERM; | |
1466 | if (flag & O_TRUNC) | |
1467 | return -EPERM; | |
1468 | } | |
1469 | ||
1470 | /* O_NOATIME can only be set by the owner or superuser */ | |
1471 | if (flag & O_NOATIME) | |
1472 | if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) | |
1473 | return -EPERM; | |
1474 | ||
1475 | /* | |
1476 | * Ensure there are no outstanding leases on the file. | |
1477 | */ | |
1478 | error = break_lease(inode, flag); | |
1479 | if (error) | |
1480 | return error; | |
1481 | ||
1482 | if (flag & O_TRUNC) { | |
1483 | error = get_write_access(inode); | |
1484 | if (error) | |
1485 | return error; | |
1486 | ||
1487 | /* | |
1488 | * Refuse to truncate files with mandatory locks held on them. | |
1489 | */ | |
1490 | error = locks_verify_locked(inode); | |
1491 | if (!error) { | |
1492 | DQUOT_INIT(inode); | |
1493 | ||
cc4e69de | 1494 | error = do_truncate(dentry, 0, NULL); |
1da177e4 LT |
1495 | } |
1496 | put_write_access(inode); | |
1497 | if (error) | |
1498 | return error; | |
1499 | } else | |
1500 | if (flag & FMODE_WRITE) | |
1501 | DQUOT_INIT(inode); | |
1502 | ||
1503 | return 0; | |
1504 | } | |
1505 | ||
1506 | /* | |
1507 | * open_namei() | |
1508 | * | |
1509 | * namei for open - this is in fact almost the whole open-routine. | |
1510 | * | |
1511 | * Note that the low bits of "flag" aren't the same as in the open | |
1512 | * system call - they are 00 - no permissions needed | |
1513 | * 01 - read permission needed | |
1514 | * 10 - write permission needed | |
1515 | * 11 - read/write permissions needed | |
1516 | * which is a lot more logical, and also allows the "no perm" needed | |
1517 | * for symlinks (where the permissions are checked later). | |
1518 | * SMP-safe | |
1519 | */ | |
1520 | int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) | |
1521 | { | |
834f2a4a | 1522 | int acc_mode, error; |
4e7506e4 | 1523 | struct path path; |
1da177e4 LT |
1524 | struct dentry *dir; |
1525 | int count = 0; | |
1526 | ||
1527 | acc_mode = ACC_MODE(flag); | |
1528 | ||
834f2a4a TM |
1529 | /* O_TRUNC implies we need access checks for write permissions */ |
1530 | if (flag & O_TRUNC) | |
1531 | acc_mode |= MAY_WRITE; | |
1532 | ||
1da177e4 LT |
1533 | /* Allow the LSM permission hook to distinguish append |
1534 | access from general write access. */ | |
1535 | if (flag & O_APPEND) | |
1536 | acc_mode |= MAY_APPEND; | |
1537 | ||
1da177e4 LT |
1538 | /* |
1539 | * The simplest case - just a plain lookup. | |
1540 | */ | |
1541 | if (!(flag & O_CREAT)) { | |
834f2a4a | 1542 | error = path_lookup_open(pathname, lookup_flags(flag), nd, flag); |
1da177e4 LT |
1543 | if (error) |
1544 | return error; | |
1545 | goto ok; | |
1546 | } | |
1547 | ||
1548 | /* | |
1549 | * Create - we need to know the parent. | |
1550 | */ | |
834f2a4a | 1551 | error = path_lookup_create(pathname, LOOKUP_PARENT, nd, flag, mode); |
1da177e4 LT |
1552 | if (error) |
1553 | return error; | |
1554 | ||
1555 | /* | |
1556 | * We have the parent and last component. First of all, check | |
1557 | * that we are not asked to creat(2) an obvious directory - that | |
1558 | * will not do. | |
1559 | */ | |
1560 | error = -EISDIR; | |
1561 | if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len]) | |
1562 | goto exit; | |
1563 | ||
1564 | dir = nd->dentry; | |
1565 | nd->flags &= ~LOOKUP_PARENT; | |
1566 | down(&dir->d_inode->i_sem); | |
49705b77 | 1567 | path.dentry = lookup_hash(nd); |
d73ffe16 | 1568 | path.mnt = nd->mnt; |
1da177e4 LT |
1569 | |
1570 | do_last: | |
4e7506e4 AV |
1571 | error = PTR_ERR(path.dentry); |
1572 | if (IS_ERR(path.dentry)) { | |
1da177e4 LT |
1573 | up(&dir->d_inode->i_sem); |
1574 | goto exit; | |
1575 | } | |
1576 | ||
1577 | /* Negative dentry, just create the file */ | |
4e7506e4 | 1578 | if (!path.dentry->d_inode) { |
1da177e4 LT |
1579 | if (!IS_POSIXACL(dir->d_inode)) |
1580 | mode &= ~current->fs->umask; | |
4e7506e4 | 1581 | error = vfs_create(dir->d_inode, path.dentry, mode, nd); |
1da177e4 LT |
1582 | up(&dir->d_inode->i_sem); |
1583 | dput(nd->dentry); | |
4e7506e4 | 1584 | nd->dentry = path.dentry; |
1da177e4 LT |
1585 | if (error) |
1586 | goto exit; | |
1587 | /* Don't check for write permission, don't truncate */ | |
1588 | acc_mode = 0; | |
1589 | flag &= ~O_TRUNC; | |
1590 | goto ok; | |
1591 | } | |
1592 | ||
1593 | /* | |
1594 | * It already exists. | |
1595 | */ | |
1596 | up(&dir->d_inode->i_sem); | |
1597 | ||
1598 | error = -EEXIST; | |
1599 | if (flag & O_EXCL) | |
1600 | goto exit_dput; | |
1601 | ||
e13b210f | 1602 | if (__follow_mount(&path)) { |
1da177e4 | 1603 | error = -ELOOP; |
ba7a4c1a AV |
1604 | if (flag & O_NOFOLLOW) |
1605 | goto exit_dput; | |
1da177e4 LT |
1606 | } |
1607 | error = -ENOENT; | |
4e7506e4 | 1608 | if (!path.dentry->d_inode) |
1da177e4 | 1609 | goto exit_dput; |
4e7506e4 | 1610 | if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) |
1da177e4 LT |
1611 | goto do_link; |
1612 | ||
09dd17d3 | 1613 | path_to_nameidata(&path, nd); |
1da177e4 | 1614 | error = -EISDIR; |
4e7506e4 | 1615 | if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) |
1da177e4 LT |
1616 | goto exit; |
1617 | ok: | |
1618 | error = may_open(nd, acc_mode, flag); | |
1619 | if (error) | |
1620 | goto exit; | |
1621 | return 0; | |
1622 | ||
1623 | exit_dput: | |
09dd17d3 | 1624 | dput_path(&path, nd); |
1da177e4 | 1625 | exit: |
834f2a4a TM |
1626 | if (!IS_ERR(nd->intent.open.file)) |
1627 | release_open_intent(nd); | |
1da177e4 LT |
1628 | path_release(nd); |
1629 | return error; | |
1630 | ||
1631 | do_link: | |
1632 | error = -ELOOP; | |
1633 | if (flag & O_NOFOLLOW) | |
1634 | goto exit_dput; | |
1635 | /* | |
1636 | * This is subtle. Instead of calling do_follow_link() we do the | |
1637 | * thing by hands. The reason is that this way we have zero link_count | |
1638 | * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. | |
1639 | * After that we have the parent and last component, i.e. | |
1640 | * we are in the same situation as after the first path_walk(). | |
1641 | * Well, almost - if the last component is normal we get its copy | |
1642 | * stored in nd->last.name and we will have to putname() it when we | |
1643 | * are done. Procfs-like symlinks just set LAST_BIND. | |
1644 | */ | |
1645 | nd->flags |= LOOKUP_PARENT; | |
4e7506e4 | 1646 | error = security_inode_follow_link(path.dentry, nd); |
1da177e4 LT |
1647 | if (error) |
1648 | goto exit_dput; | |
cd4e91d3 | 1649 | error = __do_follow_link(&path, nd); |
1da177e4 LT |
1650 | if (error) |
1651 | return error; | |
1652 | nd->flags &= ~LOOKUP_PARENT; | |
d671d5e5 | 1653 | if (nd->last_type == LAST_BIND) |
1da177e4 | 1654 | goto ok; |
1da177e4 LT |
1655 | error = -EISDIR; |
1656 | if (nd->last_type != LAST_NORM) | |
1657 | goto exit; | |
1658 | if (nd->last.name[nd->last.len]) { | |
82984114 | 1659 | __putname(nd->last.name); |
1da177e4 LT |
1660 | goto exit; |
1661 | } | |
1662 | error = -ELOOP; | |
1663 | if (count++==32) { | |
82984114 | 1664 | __putname(nd->last.name); |
1da177e4 LT |
1665 | goto exit; |
1666 | } | |
1667 | dir = nd->dentry; | |
1668 | down(&dir->d_inode->i_sem); | |
49705b77 | 1669 | path.dentry = lookup_hash(nd); |
d671d5e5 | 1670 | path.mnt = nd->mnt; |
82984114 | 1671 | __putname(nd->last.name); |
1da177e4 LT |
1672 | goto do_last; |
1673 | } | |
1674 | ||
1675 | /** | |
1676 | * lookup_create - lookup a dentry, creating it if it doesn't exist | |
1677 | * @nd: nameidata info | |
1678 | * @is_dir: directory flag | |
1679 | * | |
1680 | * Simple function to lookup and return a dentry and create it | |
1681 | * if it doesn't exist. Is SMP-safe. | |
c663e5d8 CH |
1682 | * |
1683 | * Returns with nd->dentry->d_inode->i_sem locked. | |
1da177e4 LT |
1684 | */ |
1685 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) | |
1686 | { | |
c663e5d8 | 1687 | struct dentry *dentry = ERR_PTR(-EEXIST); |
1da177e4 LT |
1688 | |
1689 | down(&nd->dentry->d_inode->i_sem); | |
c663e5d8 CH |
1690 | /* |
1691 | * Yucky last component or no last component at all? | |
1692 | * (foo/., foo/.., /////) | |
1693 | */ | |
1da177e4 LT |
1694 | if (nd->last_type != LAST_NORM) |
1695 | goto fail; | |
1696 | nd->flags &= ~LOOKUP_PARENT; | |
c663e5d8 CH |
1697 | |
1698 | /* | |
1699 | * Do the final lookup. | |
1700 | */ | |
49705b77 | 1701 | dentry = lookup_hash(nd); |
1da177e4 LT |
1702 | if (IS_ERR(dentry)) |
1703 | goto fail; | |
c663e5d8 CH |
1704 | |
1705 | /* | |
1706 | * Special case - lookup gave negative, but... we had foo/bar/ | |
1707 | * From the vfs_mknod() POV we just have a negative dentry - | |
1708 | * all is fine. Let's be bastards - you had / on the end, you've | |
1709 | * been asking for (non-existent) directory. -ENOENT for you. | |
1710 | */ | |
1da177e4 LT |
1711 | if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) |
1712 | goto enoent; | |
1713 | return dentry; | |
1714 | enoent: | |
1715 | dput(dentry); | |
1716 | dentry = ERR_PTR(-ENOENT); | |
1717 | fail: | |
1718 | return dentry; | |
1719 | } | |
f81a0bff | 1720 | EXPORT_SYMBOL_GPL(lookup_create); |
1da177e4 LT |
1721 | |
1722 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
1723 | { | |
1724 | int error = may_create(dir, dentry, NULL); | |
1725 | ||
1726 | if (error) | |
1727 | return error; | |
1728 | ||
1729 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) | |
1730 | return -EPERM; | |
1731 | ||
1732 | if (!dir->i_op || !dir->i_op->mknod) | |
1733 | return -EPERM; | |
1734 | ||
1735 | error = security_inode_mknod(dir, dentry, mode, dev); | |
1736 | if (error) | |
1737 | return error; | |
1738 | ||
1739 | DQUOT_INIT(dir); | |
1740 | error = dir->i_op->mknod(dir, dentry, mode, dev); | |
a74574aa | 1741 | if (!error) |
0eeca283 | 1742 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
1743 | return error; |
1744 | } | |
1745 | ||
1746 | asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev) | |
1747 | { | |
1748 | int error = 0; | |
1749 | char * tmp; | |
1750 | struct dentry * dentry; | |
1751 | struct nameidata nd; | |
1752 | ||
1753 | if (S_ISDIR(mode)) | |
1754 | return -EPERM; | |
1755 | tmp = getname(filename); | |
1756 | if (IS_ERR(tmp)) | |
1757 | return PTR_ERR(tmp); | |
1758 | ||
1759 | error = path_lookup(tmp, LOOKUP_PARENT, &nd); | |
1760 | if (error) | |
1761 | goto out; | |
1762 | dentry = lookup_create(&nd, 0); | |
1763 | error = PTR_ERR(dentry); | |
1764 | ||
1765 | if (!IS_POSIXACL(nd.dentry->d_inode)) | |
1766 | mode &= ~current->fs->umask; | |
1767 | if (!IS_ERR(dentry)) { | |
1768 | switch (mode & S_IFMT) { | |
1769 | case 0: case S_IFREG: | |
1770 | error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd); | |
1771 | break; | |
1772 | case S_IFCHR: case S_IFBLK: | |
1773 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode, | |
1774 | new_decode_dev(dev)); | |
1775 | break; | |
1776 | case S_IFIFO: case S_IFSOCK: | |
1777 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0); | |
1778 | break; | |
1779 | case S_IFDIR: | |
1780 | error = -EPERM; | |
1781 | break; | |
1782 | default: | |
1783 | error = -EINVAL; | |
1784 | } | |
1785 | dput(dentry); | |
1786 | } | |
1787 | up(&nd.dentry->d_inode->i_sem); | |
1788 | path_release(&nd); | |
1789 | out: | |
1790 | putname(tmp); | |
1791 | ||
1792 | return error; | |
1793 | } | |
1794 | ||
1795 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
1796 | { | |
1797 | int error = may_create(dir, dentry, NULL); | |
1798 | ||
1799 | if (error) | |
1800 | return error; | |
1801 | ||
1802 | if (!dir->i_op || !dir->i_op->mkdir) | |
1803 | return -EPERM; | |
1804 | ||
1805 | mode &= (S_IRWXUGO|S_ISVTX); | |
1806 | error = security_inode_mkdir(dir, dentry, mode); | |
1807 | if (error) | |
1808 | return error; | |
1809 | ||
1810 | DQUOT_INIT(dir); | |
1811 | error = dir->i_op->mkdir(dir, dentry, mode); | |
a74574aa | 1812 | if (!error) |
0eeca283 | 1813 | fsnotify_mkdir(dir, dentry->d_name.name); |
1da177e4 LT |
1814 | return error; |
1815 | } | |
1816 | ||
1817 | asmlinkage long sys_mkdir(const char __user * pathname, int mode) | |
1818 | { | |
1819 | int error = 0; | |
1820 | char * tmp; | |
1821 | ||
1822 | tmp = getname(pathname); | |
1823 | error = PTR_ERR(tmp); | |
1824 | if (!IS_ERR(tmp)) { | |
1825 | struct dentry *dentry; | |
1826 | struct nameidata nd; | |
1827 | ||
1828 | error = path_lookup(tmp, LOOKUP_PARENT, &nd); | |
1829 | if (error) | |
1830 | goto out; | |
1831 | dentry = lookup_create(&nd, 1); | |
1832 | error = PTR_ERR(dentry); | |
1833 | if (!IS_ERR(dentry)) { | |
1834 | if (!IS_POSIXACL(nd.dentry->d_inode)) | |
1835 | mode &= ~current->fs->umask; | |
1836 | error = vfs_mkdir(nd.dentry->d_inode, dentry, mode); | |
1837 | dput(dentry); | |
1838 | } | |
1839 | up(&nd.dentry->d_inode->i_sem); | |
1840 | path_release(&nd); | |
1841 | out: | |
1842 | putname(tmp); | |
1843 | } | |
1844 | ||
1845 | return error; | |
1846 | } | |
1847 | ||
1848 | /* | |
1849 | * We try to drop the dentry early: we should have | |
1850 | * a usage count of 2 if we're the only user of this | |
1851 | * dentry, and if that is true (possibly after pruning | |
1852 | * the dcache), then we drop the dentry now. | |
1853 | * | |
1854 | * A low-level filesystem can, if it choses, legally | |
1855 | * do a | |
1856 | * | |
1857 | * if (!d_unhashed(dentry)) | |
1858 | * return -EBUSY; | |
1859 | * | |
1860 | * if it cannot handle the case of removing a directory | |
1861 | * that is still in use by something else.. | |
1862 | */ | |
1863 | void dentry_unhash(struct dentry *dentry) | |
1864 | { | |
1865 | dget(dentry); | |
1866 | if (atomic_read(&dentry->d_count)) | |
1867 | shrink_dcache_parent(dentry); | |
1868 | spin_lock(&dcache_lock); | |
1869 | spin_lock(&dentry->d_lock); | |
1870 | if (atomic_read(&dentry->d_count) == 2) | |
1871 | __d_drop(dentry); | |
1872 | spin_unlock(&dentry->d_lock); | |
1873 | spin_unlock(&dcache_lock); | |
1874 | } | |
1875 | ||
1876 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
1877 | { | |
1878 | int error = may_delete(dir, dentry, 1); | |
1879 | ||
1880 | if (error) | |
1881 | return error; | |
1882 | ||
1883 | if (!dir->i_op || !dir->i_op->rmdir) | |
1884 | return -EPERM; | |
1885 | ||
1886 | DQUOT_INIT(dir); | |
1887 | ||
1888 | down(&dentry->d_inode->i_sem); | |
1889 | dentry_unhash(dentry); | |
1890 | if (d_mountpoint(dentry)) | |
1891 | error = -EBUSY; | |
1892 | else { | |
1893 | error = security_inode_rmdir(dir, dentry); | |
1894 | if (!error) { | |
1895 | error = dir->i_op->rmdir(dir, dentry); | |
1896 | if (!error) | |
1897 | dentry->d_inode->i_flags |= S_DEAD; | |
1898 | } | |
1899 | } | |
1900 | up(&dentry->d_inode->i_sem); | |
1901 | if (!error) { | |
1da177e4 LT |
1902 | d_delete(dentry); |
1903 | } | |
1904 | dput(dentry); | |
1905 | ||
1906 | return error; | |
1907 | } | |
1908 | ||
1909 | asmlinkage long sys_rmdir(const char __user * pathname) | |
1910 | { | |
1911 | int error = 0; | |
1912 | char * name; | |
1913 | struct dentry *dentry; | |
1914 | struct nameidata nd; | |
1915 | ||
1916 | name = getname(pathname); | |
1917 | if(IS_ERR(name)) | |
1918 | return PTR_ERR(name); | |
1919 | ||
1920 | error = path_lookup(name, LOOKUP_PARENT, &nd); | |
1921 | if (error) | |
1922 | goto exit; | |
1923 | ||
1924 | switch(nd.last_type) { | |
1925 | case LAST_DOTDOT: | |
1926 | error = -ENOTEMPTY; | |
1927 | goto exit1; | |
1928 | case LAST_DOT: | |
1929 | error = -EINVAL; | |
1930 | goto exit1; | |
1931 | case LAST_ROOT: | |
1932 | error = -EBUSY; | |
1933 | goto exit1; | |
1934 | } | |
1935 | down(&nd.dentry->d_inode->i_sem); | |
49705b77 | 1936 | dentry = lookup_hash(&nd); |
1da177e4 LT |
1937 | error = PTR_ERR(dentry); |
1938 | if (!IS_ERR(dentry)) { | |
1939 | error = vfs_rmdir(nd.dentry->d_inode, dentry); | |
1940 | dput(dentry); | |
1941 | } | |
1942 | up(&nd.dentry->d_inode->i_sem); | |
1943 | exit1: | |
1944 | path_release(&nd); | |
1945 | exit: | |
1946 | putname(name); | |
1947 | return error; | |
1948 | } | |
1949 | ||
1950 | int vfs_unlink(struct inode *dir, struct dentry *dentry) | |
1951 | { | |
1952 | int error = may_delete(dir, dentry, 0); | |
1953 | ||
1954 | if (error) | |
1955 | return error; | |
1956 | ||
1957 | if (!dir->i_op || !dir->i_op->unlink) | |
1958 | return -EPERM; | |
1959 | ||
1960 | DQUOT_INIT(dir); | |
1961 | ||
1962 | down(&dentry->d_inode->i_sem); | |
1963 | if (d_mountpoint(dentry)) | |
1964 | error = -EBUSY; | |
1965 | else { | |
1966 | error = security_inode_unlink(dir, dentry); | |
1967 | if (!error) | |
1968 | error = dir->i_op->unlink(dir, dentry); | |
1969 | } | |
1970 | up(&dentry->d_inode->i_sem); | |
1971 | ||
1972 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
1973 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
e234f35c | 1974 | d_delete(dentry); |
1da177e4 | 1975 | } |
0eeca283 | 1976 | |
1da177e4 LT |
1977 | return error; |
1978 | } | |
1979 | ||
1980 | /* | |
1981 | * Make sure that the actual truncation of the file will occur outside its | |
1982 | * directory's i_sem. Truncate can take a long time if there is a lot of | |
1983 | * writeout happening, and we don't want to prevent access to the directory | |
1984 | * while waiting on the I/O. | |
1985 | */ | |
1986 | asmlinkage long sys_unlink(const char __user * pathname) | |
1987 | { | |
1988 | int error = 0; | |
1989 | char * name; | |
1990 | struct dentry *dentry; | |
1991 | struct nameidata nd; | |
1992 | struct inode *inode = NULL; | |
1993 | ||
1994 | name = getname(pathname); | |
1995 | if(IS_ERR(name)) | |
1996 | return PTR_ERR(name); | |
1997 | ||
1998 | error = path_lookup(name, LOOKUP_PARENT, &nd); | |
1999 | if (error) | |
2000 | goto exit; | |
2001 | error = -EISDIR; | |
2002 | if (nd.last_type != LAST_NORM) | |
2003 | goto exit1; | |
2004 | down(&nd.dentry->d_inode->i_sem); | |
49705b77 | 2005 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2006 | error = PTR_ERR(dentry); |
2007 | if (!IS_ERR(dentry)) { | |
2008 | /* Why not before? Because we want correct error value */ | |
2009 | if (nd.last.name[nd.last.len]) | |
2010 | goto slashes; | |
2011 | inode = dentry->d_inode; | |
2012 | if (inode) | |
2013 | atomic_inc(&inode->i_count); | |
2014 | error = vfs_unlink(nd.dentry->d_inode, dentry); | |
2015 | exit2: | |
2016 | dput(dentry); | |
2017 | } | |
2018 | up(&nd.dentry->d_inode->i_sem); | |
2019 | if (inode) | |
2020 | iput(inode); /* truncate the inode here */ | |
2021 | exit1: | |
2022 | path_release(&nd); | |
2023 | exit: | |
2024 | putname(name); | |
2025 | return error; | |
2026 | ||
2027 | slashes: | |
2028 | error = !dentry->d_inode ? -ENOENT : | |
2029 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2030 | goto exit2; | |
2031 | } | |
2032 | ||
2033 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) | |
2034 | { | |
2035 | int error = may_create(dir, dentry, NULL); | |
2036 | ||
2037 | if (error) | |
2038 | return error; | |
2039 | ||
2040 | if (!dir->i_op || !dir->i_op->symlink) | |
2041 | return -EPERM; | |
2042 | ||
2043 | error = security_inode_symlink(dir, dentry, oldname); | |
2044 | if (error) | |
2045 | return error; | |
2046 | ||
2047 | DQUOT_INIT(dir); | |
2048 | error = dir->i_op->symlink(dir, dentry, oldname); | |
a74574aa | 2049 | if (!error) |
0eeca283 | 2050 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
2051 | return error; |
2052 | } | |
2053 | ||
2054 | asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname) | |
2055 | { | |
2056 | int error = 0; | |
2057 | char * from; | |
2058 | char * to; | |
2059 | ||
2060 | from = getname(oldname); | |
2061 | if(IS_ERR(from)) | |
2062 | return PTR_ERR(from); | |
2063 | to = getname(newname); | |
2064 | error = PTR_ERR(to); | |
2065 | if (!IS_ERR(to)) { | |
2066 | struct dentry *dentry; | |
2067 | struct nameidata nd; | |
2068 | ||
2069 | error = path_lookup(to, LOOKUP_PARENT, &nd); | |
2070 | if (error) | |
2071 | goto out; | |
2072 | dentry = lookup_create(&nd, 0); | |
2073 | error = PTR_ERR(dentry); | |
2074 | if (!IS_ERR(dentry)) { | |
2075 | error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO); | |
2076 | dput(dentry); | |
2077 | } | |
2078 | up(&nd.dentry->d_inode->i_sem); | |
2079 | path_release(&nd); | |
2080 | out: | |
2081 | putname(to); | |
2082 | } | |
2083 | putname(from); | |
2084 | return error; | |
2085 | } | |
2086 | ||
2087 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) | |
2088 | { | |
2089 | struct inode *inode = old_dentry->d_inode; | |
2090 | int error; | |
2091 | ||
2092 | if (!inode) | |
2093 | return -ENOENT; | |
2094 | ||
2095 | error = may_create(dir, new_dentry, NULL); | |
2096 | if (error) | |
2097 | return error; | |
2098 | ||
2099 | if (dir->i_sb != inode->i_sb) | |
2100 | return -EXDEV; | |
2101 | ||
2102 | /* | |
2103 | * A link to an append-only or immutable file cannot be created. | |
2104 | */ | |
2105 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2106 | return -EPERM; | |
2107 | if (!dir->i_op || !dir->i_op->link) | |
2108 | return -EPERM; | |
2109 | if (S_ISDIR(old_dentry->d_inode->i_mode)) | |
2110 | return -EPERM; | |
2111 | ||
2112 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2113 | if (error) | |
2114 | return error; | |
2115 | ||
2116 | down(&old_dentry->d_inode->i_sem); | |
2117 | DQUOT_INIT(dir); | |
2118 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
2119 | up(&old_dentry->d_inode->i_sem); | |
e31e14ec | 2120 | if (!error) |
0eeca283 | 2121 | fsnotify_create(dir, new_dentry->d_name.name); |
1da177e4 LT |
2122 | return error; |
2123 | } | |
2124 | ||
2125 | /* | |
2126 | * Hardlinks are often used in delicate situations. We avoid | |
2127 | * security-related surprises by not following symlinks on the | |
2128 | * newname. --KAB | |
2129 | * | |
2130 | * We don't follow them on the oldname either to be compatible | |
2131 | * with linux 2.0, and to avoid hard-linking to directories | |
2132 | * and other special files. --ADM | |
2133 | */ | |
2134 | asmlinkage long sys_link(const char __user * oldname, const char __user * newname) | |
2135 | { | |
2136 | struct dentry *new_dentry; | |
2137 | struct nameidata nd, old_nd; | |
2138 | int error; | |
2139 | char * to; | |
2140 | ||
2141 | to = getname(newname); | |
2142 | if (IS_ERR(to)) | |
2143 | return PTR_ERR(to); | |
2144 | ||
2145 | error = __user_walk(oldname, 0, &old_nd); | |
2146 | if (error) | |
2147 | goto exit; | |
2148 | error = path_lookup(to, LOOKUP_PARENT, &nd); | |
2149 | if (error) | |
2150 | goto out; | |
2151 | error = -EXDEV; | |
2152 | if (old_nd.mnt != nd.mnt) | |
2153 | goto out_release; | |
2154 | new_dentry = lookup_create(&nd, 0); | |
2155 | error = PTR_ERR(new_dentry); | |
2156 | if (!IS_ERR(new_dentry)) { | |
2157 | error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry); | |
2158 | dput(new_dentry); | |
2159 | } | |
2160 | up(&nd.dentry->d_inode->i_sem); | |
2161 | out_release: | |
2162 | path_release(&nd); | |
2163 | out: | |
2164 | path_release(&old_nd); | |
2165 | exit: | |
2166 | putname(to); | |
2167 | ||
2168 | return error; | |
2169 | } | |
2170 | ||
2171 | /* | |
2172 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2173 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2174 | * Problems: | |
2175 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2176 | * b) race potential - two innocent renames can create a loop together. | |
2177 | * That's where 4.4 screws up. Current fix: serialization on | |
2178 | * sb->s_vfs_rename_sem. We might be more accurate, but that's another | |
2179 | * story. | |
2180 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
2181 | * And that - after we got ->i_sem on parents (until then we don't know | |
2182 | * whether the target exists). Solution: try to be smart with locking | |
2183 | * order for inodes. We rely on the fact that tree topology may change | |
2184 | * only under ->s_vfs_rename_sem _and_ that parent of the object we | |
2185 | * move will be locked. Thus we can rank directories by the tree | |
2186 | * (ancestors first) and rank all non-directories after them. | |
2187 | * That works since everybody except rename does "lock parent, lookup, | |
2188 | * lock child" and rename is under ->s_vfs_rename_sem. | |
2189 | * HOWEVER, it relies on the assumption that any object with ->lookup() | |
2190 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2191 | * we'd better make sure that there's no link(2) for them. | |
2192 | * d) some filesystems don't support opened-but-unlinked directories, | |
2193 | * either because of layout or because they are not ready to deal with | |
2194 | * all cases correctly. The latter will be fixed (taking this sort of | |
2195 | * stuff into VFS), but the former is not going away. Solution: the same | |
2196 | * trick as in rmdir(). | |
2197 | * e) conversion from fhandle to dentry may come in the wrong moment - when | |
2198 | * we are removing the target. Solution: we will have to grab ->i_sem | |
2199 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on | |
2200 | * ->i_sem on parents, which works but leads to some truely excessive | |
2201 | * locking]. | |
2202 | */ | |
75c96f85 AB |
2203 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2204 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2205 | { |
2206 | int error = 0; | |
2207 | struct inode *target; | |
2208 | ||
2209 | /* | |
2210 | * If we are going to change the parent - check write permissions, | |
2211 | * we'll need to flip '..'. | |
2212 | */ | |
2213 | if (new_dir != old_dir) { | |
2214 | error = permission(old_dentry->d_inode, MAY_WRITE, NULL); | |
2215 | if (error) | |
2216 | return error; | |
2217 | } | |
2218 | ||
2219 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2220 | if (error) | |
2221 | return error; | |
2222 | ||
2223 | target = new_dentry->d_inode; | |
2224 | if (target) { | |
2225 | down(&target->i_sem); | |
2226 | dentry_unhash(new_dentry); | |
2227 | } | |
2228 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2229 | error = -EBUSY; | |
2230 | else | |
2231 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2232 | if (target) { | |
2233 | if (!error) | |
2234 | target->i_flags |= S_DEAD; | |
2235 | up(&target->i_sem); | |
2236 | if (d_unhashed(new_dentry)) | |
2237 | d_rehash(new_dentry); | |
2238 | dput(new_dentry); | |
2239 | } | |
e31e14ec | 2240 | if (!error) |
1da177e4 | 2241 | d_move(old_dentry,new_dentry); |
1da177e4 LT |
2242 | return error; |
2243 | } | |
2244 | ||
75c96f85 AB |
2245 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2246 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2247 | { |
2248 | struct inode *target; | |
2249 | int error; | |
2250 | ||
2251 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2252 | if (error) | |
2253 | return error; | |
2254 | ||
2255 | dget(new_dentry); | |
2256 | target = new_dentry->d_inode; | |
2257 | if (target) | |
2258 | down(&target->i_sem); | |
2259 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2260 | error = -EBUSY; | |
2261 | else | |
2262 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2263 | if (!error) { | |
2264 | /* The following d_move() should become unconditional */ | |
2265 | if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME)) | |
2266 | d_move(old_dentry, new_dentry); | |
1da177e4 LT |
2267 | } |
2268 | if (target) | |
2269 | up(&target->i_sem); | |
2270 | dput(new_dentry); | |
2271 | return error; | |
2272 | } | |
2273 | ||
2274 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2275 | struct inode *new_dir, struct dentry *new_dentry) | |
2276 | { | |
2277 | int error; | |
2278 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
0eeca283 | 2279 | const char *old_name; |
1da177e4 LT |
2280 | |
2281 | if (old_dentry->d_inode == new_dentry->d_inode) | |
2282 | return 0; | |
2283 | ||
2284 | error = may_delete(old_dir, old_dentry, is_dir); | |
2285 | if (error) | |
2286 | return error; | |
2287 | ||
2288 | if (!new_dentry->d_inode) | |
2289 | error = may_create(new_dir, new_dentry, NULL); | |
2290 | else | |
2291 | error = may_delete(new_dir, new_dentry, is_dir); | |
2292 | if (error) | |
2293 | return error; | |
2294 | ||
2295 | if (!old_dir->i_op || !old_dir->i_op->rename) | |
2296 | return -EPERM; | |
2297 | ||
2298 | DQUOT_INIT(old_dir); | |
2299 | DQUOT_INIT(new_dir); | |
2300 | ||
0eeca283 RL |
2301 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
2302 | ||
1da177e4 LT |
2303 | if (is_dir) |
2304 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
2305 | else | |
2306 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
2307 | if (!error) { | |
0eeca283 | 2308 | const char *new_name = old_dentry->d_name.name; |
89204c40 JM |
2309 | fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, |
2310 | new_dentry->d_inode, old_dentry->d_inode); | |
1da177e4 | 2311 | } |
0eeca283 RL |
2312 | fsnotify_oldname_free(old_name); |
2313 | ||
1da177e4 LT |
2314 | return error; |
2315 | } | |
2316 | ||
2317 | static inline int do_rename(const char * oldname, const char * newname) | |
2318 | { | |
2319 | int error = 0; | |
2320 | struct dentry * old_dir, * new_dir; | |
2321 | struct dentry * old_dentry, *new_dentry; | |
2322 | struct dentry * trap; | |
2323 | struct nameidata oldnd, newnd; | |
2324 | ||
2325 | error = path_lookup(oldname, LOOKUP_PARENT, &oldnd); | |
2326 | if (error) | |
2327 | goto exit; | |
2328 | ||
2329 | error = path_lookup(newname, LOOKUP_PARENT, &newnd); | |
2330 | if (error) | |
2331 | goto exit1; | |
2332 | ||
2333 | error = -EXDEV; | |
2334 | if (oldnd.mnt != newnd.mnt) | |
2335 | goto exit2; | |
2336 | ||
2337 | old_dir = oldnd.dentry; | |
2338 | error = -EBUSY; | |
2339 | if (oldnd.last_type != LAST_NORM) | |
2340 | goto exit2; | |
2341 | ||
2342 | new_dir = newnd.dentry; | |
2343 | if (newnd.last_type != LAST_NORM) | |
2344 | goto exit2; | |
2345 | ||
2346 | trap = lock_rename(new_dir, old_dir); | |
2347 | ||
49705b77 | 2348 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
2349 | error = PTR_ERR(old_dentry); |
2350 | if (IS_ERR(old_dentry)) | |
2351 | goto exit3; | |
2352 | /* source must exist */ | |
2353 | error = -ENOENT; | |
2354 | if (!old_dentry->d_inode) | |
2355 | goto exit4; | |
2356 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
2357 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
2358 | error = -ENOTDIR; | |
2359 | if (oldnd.last.name[oldnd.last.len]) | |
2360 | goto exit4; | |
2361 | if (newnd.last.name[newnd.last.len]) | |
2362 | goto exit4; | |
2363 | } | |
2364 | /* source should not be ancestor of target */ | |
2365 | error = -EINVAL; | |
2366 | if (old_dentry == trap) | |
2367 | goto exit4; | |
49705b77 | 2368 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
2369 | error = PTR_ERR(new_dentry); |
2370 | if (IS_ERR(new_dentry)) | |
2371 | goto exit4; | |
2372 | /* target should not be an ancestor of source */ | |
2373 | error = -ENOTEMPTY; | |
2374 | if (new_dentry == trap) | |
2375 | goto exit5; | |
2376 | ||
2377 | error = vfs_rename(old_dir->d_inode, old_dentry, | |
2378 | new_dir->d_inode, new_dentry); | |
2379 | exit5: | |
2380 | dput(new_dentry); | |
2381 | exit4: | |
2382 | dput(old_dentry); | |
2383 | exit3: | |
2384 | unlock_rename(new_dir, old_dir); | |
2385 | exit2: | |
2386 | path_release(&newnd); | |
2387 | exit1: | |
2388 | path_release(&oldnd); | |
2389 | exit: | |
2390 | return error; | |
2391 | } | |
2392 | ||
2393 | asmlinkage long sys_rename(const char __user * oldname, const char __user * newname) | |
2394 | { | |
2395 | int error; | |
2396 | char * from; | |
2397 | char * to; | |
2398 | ||
2399 | from = getname(oldname); | |
2400 | if(IS_ERR(from)) | |
2401 | return PTR_ERR(from); | |
2402 | to = getname(newname); | |
2403 | error = PTR_ERR(to); | |
2404 | if (!IS_ERR(to)) { | |
2405 | error = do_rename(from,to); | |
2406 | putname(to); | |
2407 | } | |
2408 | putname(from); | |
2409 | return error; | |
2410 | } | |
2411 | ||
2412 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) | |
2413 | { | |
2414 | int len; | |
2415 | ||
2416 | len = PTR_ERR(link); | |
2417 | if (IS_ERR(link)) | |
2418 | goto out; | |
2419 | ||
2420 | len = strlen(link); | |
2421 | if (len > (unsigned) buflen) | |
2422 | len = buflen; | |
2423 | if (copy_to_user(buffer, link, len)) | |
2424 | len = -EFAULT; | |
2425 | out: | |
2426 | return len; | |
2427 | } | |
2428 | ||
2429 | /* | |
2430 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
2431 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
2432 | * using) it for any given inode is up to filesystem. | |
2433 | */ | |
2434 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2435 | { | |
2436 | struct nameidata nd; | |
cc314eef LT |
2437 | void *cookie; |
2438 | ||
1da177e4 | 2439 | nd.depth = 0; |
cc314eef LT |
2440 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
2441 | if (!IS_ERR(cookie)) { | |
2442 | int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
1da177e4 | 2443 | if (dentry->d_inode->i_op->put_link) |
cc314eef LT |
2444 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); |
2445 | cookie = ERR_PTR(res); | |
1da177e4 | 2446 | } |
cc314eef | 2447 | return PTR_ERR(cookie); |
1da177e4 LT |
2448 | } |
2449 | ||
2450 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
2451 | { | |
2452 | return __vfs_follow_link(nd, link); | |
2453 | } | |
2454 | ||
2455 | /* get the link contents into pagecache */ | |
2456 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
2457 | { | |
2458 | struct page * page; | |
2459 | struct address_space *mapping = dentry->d_inode->i_mapping; | |
2460 | page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage, | |
2461 | NULL); | |
2462 | if (IS_ERR(page)) | |
2463 | goto sync_fail; | |
2464 | wait_on_page_locked(page); | |
2465 | if (!PageUptodate(page)) | |
2466 | goto async_fail; | |
2467 | *ppage = page; | |
2468 | return kmap(page); | |
2469 | ||
2470 | async_fail: | |
2471 | page_cache_release(page); | |
2472 | return ERR_PTR(-EIO); | |
2473 | ||
2474 | sync_fail: | |
2475 | return (char*)page; | |
2476 | } | |
2477 | ||
2478 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2479 | { | |
2480 | struct page *page = NULL; | |
2481 | char *s = page_getlink(dentry, &page); | |
2482 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
2483 | if (page) { | |
2484 | kunmap(page); | |
2485 | page_cache_release(page); | |
2486 | } | |
2487 | return res; | |
2488 | } | |
2489 | ||
cc314eef | 2490 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 2491 | { |
cc314eef | 2492 | struct page *page = NULL; |
1da177e4 | 2493 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 2494 | return page; |
1da177e4 LT |
2495 | } |
2496 | ||
cc314eef | 2497 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 2498 | { |
cc314eef LT |
2499 | struct page *page = cookie; |
2500 | ||
2501 | if (page) { | |
1da177e4 LT |
2502 | kunmap(page); |
2503 | page_cache_release(page); | |
1da177e4 LT |
2504 | } |
2505 | } | |
2506 | ||
2507 | int page_symlink(struct inode *inode, const char *symname, int len) | |
2508 | { | |
2509 | struct address_space *mapping = inode->i_mapping; | |
2510 | struct page *page = grab_cache_page(mapping, 0); | |
2511 | int err = -ENOMEM; | |
2512 | char *kaddr; | |
2513 | ||
2514 | if (!page) | |
2515 | goto fail; | |
2516 | err = mapping->a_ops->prepare_write(NULL, page, 0, len-1); | |
2517 | if (err) | |
2518 | goto fail_map; | |
2519 | kaddr = kmap_atomic(page, KM_USER0); | |
2520 | memcpy(kaddr, symname, len-1); | |
2521 | kunmap_atomic(kaddr, KM_USER0); | |
2522 | mapping->a_ops->commit_write(NULL, page, 0, len-1); | |
2523 | /* | |
2524 | * Notice that we are _not_ going to block here - end of page is | |
2525 | * unmapped, so this will only try to map the rest of page, see | |
2526 | * that it is unmapped (typically even will not look into inode - | |
2527 | * ->i_size will be enough for everything) and zero it out. | |
2528 | * OTOH it's obviously correct and should make the page up-to-date. | |
2529 | */ | |
2530 | if (!PageUptodate(page)) { | |
2531 | err = mapping->a_ops->readpage(NULL, page); | |
2532 | wait_on_page_locked(page); | |
2533 | } else { | |
2534 | unlock_page(page); | |
2535 | } | |
2536 | page_cache_release(page); | |
2537 | if (err < 0) | |
2538 | goto fail; | |
2539 | mark_inode_dirty(inode); | |
2540 | return 0; | |
2541 | fail_map: | |
2542 | unlock_page(page); | |
2543 | page_cache_release(page); | |
2544 | fail: | |
2545 | return err; | |
2546 | } | |
2547 | ||
2548 | struct inode_operations page_symlink_inode_operations = { | |
2549 | .readlink = generic_readlink, | |
2550 | .follow_link = page_follow_link_light, | |
2551 | .put_link = page_put_link, | |
2552 | }; | |
2553 | ||
2554 | EXPORT_SYMBOL(__user_walk); | |
2555 | EXPORT_SYMBOL(follow_down); | |
2556 | EXPORT_SYMBOL(follow_up); | |
2557 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
2558 | EXPORT_SYMBOL(getname); | |
2559 | EXPORT_SYMBOL(lock_rename); | |
2560 | EXPORT_SYMBOL(lookup_hash); | |
2561 | EXPORT_SYMBOL(lookup_one_len); | |
2562 | EXPORT_SYMBOL(page_follow_link_light); | |
2563 | EXPORT_SYMBOL(page_put_link); | |
2564 | EXPORT_SYMBOL(page_readlink); | |
2565 | EXPORT_SYMBOL(page_symlink); | |
2566 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
2567 | EXPORT_SYMBOL(path_lookup); | |
2568 | EXPORT_SYMBOL(path_release); | |
2569 | EXPORT_SYMBOL(path_walk); | |
2570 | EXPORT_SYMBOL(permission); | |
e4543edd | 2571 | EXPORT_SYMBOL(vfs_permission); |
8c744fb8 | 2572 | EXPORT_SYMBOL(file_permission); |
1da177e4 LT |
2573 | EXPORT_SYMBOL(unlock_rename); |
2574 | EXPORT_SYMBOL(vfs_create); | |
2575 | EXPORT_SYMBOL(vfs_follow_link); | |
2576 | EXPORT_SYMBOL(vfs_link); | |
2577 | EXPORT_SYMBOL(vfs_mkdir); | |
2578 | EXPORT_SYMBOL(vfs_mknod); | |
2579 | EXPORT_SYMBOL(generic_permission); | |
2580 | EXPORT_SYMBOL(vfs_readlink); | |
2581 | EXPORT_SYMBOL(vfs_rename); | |
2582 | EXPORT_SYMBOL(vfs_rmdir); | |
2583 | EXPORT_SYMBOL(vfs_symlink); | |
2584 | EXPORT_SYMBOL(vfs_unlink); | |
2585 | EXPORT_SYMBOL(dentry_unhash); | |
2586 | EXPORT_SYMBOL(generic_readlink); |