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> | |
16f7e0fe | 31 | #include <linux/capability.h> |
834f2a4a | 32 | #include <linux/file.h> |
5590ff0d UD |
33 | #include <linux/fcntl.h> |
34 | #include <linux/namei.h> | |
1da177e4 LT |
35 | #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) | |
107 | * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives | |
108 | * 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 | */ | |
858119e1 | 118 | static int do_getname(const char __user *filename, char *page) |
1da177e4 LT |
119 | { |
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 | ||
140 | char * 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 | |
160 | void putname(const char *name) | |
161 | { | |
162 | if (unlikely(current->audit_context)) | |
163 | audit_putname(name); | |
164 | else | |
165 | __putname(name); | |
166 | } | |
167 | EXPORT_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 | */ | |
182 | int 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 | ||
228 | int permission(struct inode *inode, int mask, struct nameidata *nd) | |
229 | { | |
230 | int retval, submask; | |
231 | ||
232 | if (mask & MAY_WRITE) { | |
233 | umode_t mode = inode->i_mode; | |
234 | ||
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 | ||
250 | /* Ordinary permission routines do not understand MAY_APPEND. */ | |
251 | submask = mask & ~MAY_APPEND; | |
252 | if (inode->i_op && inode->i_op->permission) | |
253 | retval = inode->i_op->permission(inode, submask, nd); | |
254 | else | |
255 | retval = generic_permission(inode, submask, NULL); | |
256 | if (retval) | |
257 | return retval; | |
258 | ||
259 | return security_inode_permission(inode, mask, nd); | |
260 | } | |
261 | ||
e4543edd CH |
262 | /** |
263 | * vfs_permission - check for access rights to a given path | |
264 | * @nd: lookup result that describes the path | |
265 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
266 | * | |
267 | * Used to check for read/write/execute permissions on a path. | |
268 | * We use "fsuid" for this, letting us set arbitrary permissions | |
269 | * for filesystem access without changing the "normal" uids which | |
270 | * are used for other things. | |
271 | */ | |
272 | int vfs_permission(struct nameidata *nd, int mask) | |
273 | { | |
274 | return permission(nd->dentry->d_inode, mask, nd); | |
275 | } | |
276 | ||
8c744fb8 CH |
277 | /** |
278 | * file_permission - check for additional access rights to a given file | |
279 | * @file: file to check access rights for | |
280 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
281 | * | |
282 | * Used to check for read/write/execute permissions on an already opened | |
283 | * file. | |
284 | * | |
285 | * Note: | |
286 | * Do not use this function in new code. All access checks should | |
287 | * be done using vfs_permission(). | |
288 | */ | |
289 | int file_permission(struct file *file, int mask) | |
290 | { | |
291 | return permission(file->f_dentry->d_inode, mask, NULL); | |
292 | } | |
293 | ||
1da177e4 LT |
294 | /* |
295 | * get_write_access() gets write permission for a file. | |
296 | * put_write_access() releases this write permission. | |
297 | * This is used for regular files. | |
298 | * We cannot support write (and maybe mmap read-write shared) accesses and | |
299 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode | |
300 | * can have the following values: | |
301 | * 0: no writers, no VM_DENYWRITE mappings | |
302 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist | |
303 | * > 0: (i_writecount) users are writing to the file. | |
304 | * | |
305 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe | |
306 | * except for the cases where we don't hold i_writecount yet. Then we need to | |
307 | * use {get,deny}_write_access() - these functions check the sign and refuse | |
308 | * to do the change if sign is wrong. Exclusion between them is provided by | |
309 | * the inode->i_lock spinlock. | |
310 | */ | |
311 | ||
312 | int get_write_access(struct inode * inode) | |
313 | { | |
314 | spin_lock(&inode->i_lock); | |
315 | if (atomic_read(&inode->i_writecount) < 0) { | |
316 | spin_unlock(&inode->i_lock); | |
317 | return -ETXTBSY; | |
318 | } | |
319 | atomic_inc(&inode->i_writecount); | |
320 | spin_unlock(&inode->i_lock); | |
321 | ||
322 | return 0; | |
323 | } | |
324 | ||
325 | int deny_write_access(struct file * file) | |
326 | { | |
327 | struct inode *inode = file->f_dentry->d_inode; | |
328 | ||
329 | spin_lock(&inode->i_lock); | |
330 | if (atomic_read(&inode->i_writecount) > 0) { | |
331 | spin_unlock(&inode->i_lock); | |
332 | return -ETXTBSY; | |
333 | } | |
334 | atomic_dec(&inode->i_writecount); | |
335 | spin_unlock(&inode->i_lock); | |
336 | ||
337 | return 0; | |
338 | } | |
339 | ||
340 | void path_release(struct nameidata *nd) | |
341 | { | |
342 | dput(nd->dentry); | |
343 | mntput(nd->mnt); | |
344 | } | |
345 | ||
346 | /* | |
347 | * umount() mustn't call path_release()/mntput() as that would clear | |
348 | * mnt_expiry_mark | |
349 | */ | |
350 | void path_release_on_umount(struct nameidata *nd) | |
351 | { | |
352 | dput(nd->dentry); | |
751c404b | 353 | mntput_no_expire(nd->mnt); |
1da177e4 LT |
354 | } |
355 | ||
834f2a4a TM |
356 | /** |
357 | * release_open_intent - free up open intent resources | |
358 | * @nd: pointer to nameidata | |
359 | */ | |
360 | void release_open_intent(struct nameidata *nd) | |
361 | { | |
362 | if (nd->intent.open.file->f_dentry == NULL) | |
363 | put_filp(nd->intent.open.file); | |
364 | else | |
365 | fput(nd->intent.open.file); | |
366 | } | |
367 | ||
1da177e4 LT |
368 | /* |
369 | * Internal lookup() using the new generic dcache. | |
370 | * SMP-safe | |
371 | */ | |
372 | static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
373 | { | |
374 | struct dentry * dentry = __d_lookup(parent, name); | |
375 | ||
376 | /* lockess __d_lookup may fail due to concurrent d_move() | |
377 | * in some unrelated directory, so try with d_lookup | |
378 | */ | |
379 | if (!dentry) | |
380 | dentry = d_lookup(parent, name); | |
381 | ||
382 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) { | |
383 | if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) { | |
384 | dput(dentry); | |
385 | dentry = NULL; | |
386 | } | |
387 | } | |
388 | return dentry; | |
389 | } | |
390 | ||
391 | /* | |
392 | * Short-cut version of permission(), for calling by | |
393 | * path_walk(), when dcache lock is held. Combines parts | |
394 | * of permission() and generic_permission(), and tests ONLY for | |
395 | * MAY_EXEC permission. | |
396 | * | |
397 | * If appropriate, check DAC only. If not appropriate, or | |
398 | * short-cut DAC fails, then call permission() to do more | |
399 | * complete permission check. | |
400 | */ | |
858119e1 | 401 | static int exec_permission_lite(struct inode *inode, |
1da177e4 LT |
402 | struct nameidata *nd) |
403 | { | |
404 | umode_t mode = inode->i_mode; | |
405 | ||
406 | if (inode->i_op && inode->i_op->permission) | |
407 | return -EAGAIN; | |
408 | ||
409 | if (current->fsuid == inode->i_uid) | |
410 | mode >>= 6; | |
411 | else if (in_group_p(inode->i_gid)) | |
412 | mode >>= 3; | |
413 | ||
414 | if (mode & MAY_EXEC) | |
415 | goto ok; | |
416 | ||
417 | if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) | |
418 | goto ok; | |
419 | ||
420 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) | |
421 | goto ok; | |
422 | ||
423 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) | |
424 | goto ok; | |
425 | ||
426 | return -EACCES; | |
427 | ok: | |
428 | return security_inode_permission(inode, MAY_EXEC, nd); | |
429 | } | |
430 | ||
431 | /* | |
432 | * This is called when everything else fails, and we actually have | |
433 | * to go to the low-level filesystem to find out what we should do.. | |
434 | * | |
435 | * We get the directory semaphore, and after getting that we also | |
436 | * make sure that nobody added the entry to the dcache in the meantime.. | |
437 | * SMP-safe | |
438 | */ | |
439 | static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
440 | { | |
441 | struct dentry * result; | |
442 | struct inode *dir = parent->d_inode; | |
443 | ||
1b1dcc1b | 444 | mutex_lock(&dir->i_mutex); |
1da177e4 LT |
445 | /* |
446 | * First re-do the cached lookup just in case it was created | |
447 | * while we waited for the directory semaphore.. | |
448 | * | |
449 | * FIXME! This could use version numbering or similar to | |
450 | * avoid unnecessary cache lookups. | |
451 | * | |
452 | * The "dcache_lock" is purely to protect the RCU list walker | |
453 | * from concurrent renames at this point (we mustn't get false | |
454 | * negatives from the RCU list walk here, unlike the optimistic | |
455 | * fast walk). | |
456 | * | |
457 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup | |
458 | */ | |
459 | result = d_lookup(parent, name); | |
460 | if (!result) { | |
461 | struct dentry * dentry = d_alloc(parent, name); | |
462 | result = ERR_PTR(-ENOMEM); | |
463 | if (dentry) { | |
464 | result = dir->i_op->lookup(dir, dentry, nd); | |
465 | if (result) | |
466 | dput(dentry); | |
467 | else | |
468 | result = dentry; | |
469 | } | |
1b1dcc1b | 470 | mutex_unlock(&dir->i_mutex); |
1da177e4 LT |
471 | return result; |
472 | } | |
473 | ||
474 | /* | |
475 | * Uhhuh! Nasty case: the cache was re-populated while | |
476 | * we waited on the semaphore. Need to revalidate. | |
477 | */ | |
1b1dcc1b | 478 | mutex_unlock(&dir->i_mutex); |
1da177e4 LT |
479 | if (result->d_op && result->d_op->d_revalidate) { |
480 | if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) { | |
481 | dput(result); | |
482 | result = ERR_PTR(-ENOENT); | |
483 | } | |
484 | } | |
485 | return result; | |
486 | } | |
487 | ||
488 | static int __emul_lookup_dentry(const char *, struct nameidata *); | |
489 | ||
490 | /* SMP-safe */ | |
f1662356 | 491 | static __always_inline int |
1da177e4 LT |
492 | walk_init_root(const char *name, struct nameidata *nd) |
493 | { | |
494 | read_lock(¤t->fs->lock); | |
495 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { | |
496 | nd->mnt = mntget(current->fs->altrootmnt); | |
497 | nd->dentry = dget(current->fs->altroot); | |
498 | read_unlock(¤t->fs->lock); | |
499 | if (__emul_lookup_dentry(name,nd)) | |
500 | return 0; | |
501 | read_lock(¤t->fs->lock); | |
502 | } | |
503 | nd->mnt = mntget(current->fs->rootmnt); | |
504 | nd->dentry = dget(current->fs->root); | |
505 | read_unlock(¤t->fs->lock); | |
506 | return 1; | |
507 | } | |
508 | ||
f1662356 | 509 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 LT |
510 | { |
511 | int res = 0; | |
512 | char *name; | |
513 | if (IS_ERR(link)) | |
514 | goto fail; | |
515 | ||
516 | if (*link == '/') { | |
517 | path_release(nd); | |
518 | if (!walk_init_root(link, nd)) | |
519 | /* weird __emul_prefix() stuff did it */ | |
520 | goto out; | |
521 | } | |
522 | res = link_path_walk(link, nd); | |
523 | out: | |
524 | if (nd->depth || res || nd->last_type!=LAST_NORM) | |
525 | return res; | |
526 | /* | |
527 | * If it is an iterative symlinks resolution in open_namei() we | |
528 | * have to copy the last component. And all that crap because of | |
529 | * bloody create() on broken symlinks. Furrfu... | |
530 | */ | |
531 | name = __getname(); | |
532 | if (unlikely(!name)) { | |
533 | path_release(nd); | |
534 | return -ENOMEM; | |
535 | } | |
536 | strcpy(name, nd->last.name); | |
537 | nd->last.name = name; | |
538 | return 0; | |
539 | fail: | |
540 | path_release(nd); | |
541 | return PTR_ERR(link); | |
542 | } | |
543 | ||
90ebe565 AV |
544 | struct path { |
545 | struct vfsmount *mnt; | |
546 | struct dentry *dentry; | |
547 | }; | |
548 | ||
f1662356 | 549 | static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
550 | { |
551 | int error; | |
cc314eef | 552 | void *cookie; |
cd4e91d3 | 553 | struct dentry *dentry = path->dentry; |
1da177e4 | 554 | |
d671a1cb | 555 | touch_atime(path->mnt, dentry); |
1da177e4 | 556 | nd_set_link(nd, NULL); |
cd4e91d3 | 557 | |
39ca6d49 AV |
558 | if (path->mnt == nd->mnt) |
559 | mntget(path->mnt); | |
cc314eef LT |
560 | cookie = dentry->d_inode->i_op->follow_link(dentry, nd); |
561 | error = PTR_ERR(cookie); | |
562 | if (!IS_ERR(cookie)) { | |
1da177e4 | 563 | char *s = nd_get_link(nd); |
cc314eef | 564 | error = 0; |
1da177e4 LT |
565 | if (s) |
566 | error = __vfs_follow_link(nd, s); | |
567 | if (dentry->d_inode->i_op->put_link) | |
cc314eef | 568 | dentry->d_inode->i_op->put_link(dentry, nd, cookie); |
1da177e4 | 569 | } |
cd4e91d3 AV |
570 | dput(dentry); |
571 | mntput(path->mnt); | |
1da177e4 LT |
572 | |
573 | return error; | |
574 | } | |
575 | ||
09dd17d3 MS |
576 | static inline void dput_path(struct path *path, struct nameidata *nd) |
577 | { | |
578 | dput(path->dentry); | |
579 | if (path->mnt != nd->mnt) | |
580 | mntput(path->mnt); | |
581 | } | |
582 | ||
583 | static inline void path_to_nameidata(struct path *path, struct nameidata *nd) | |
584 | { | |
585 | dput(nd->dentry); | |
586 | if (nd->mnt != path->mnt) | |
587 | mntput(nd->mnt); | |
588 | nd->mnt = path->mnt; | |
589 | nd->dentry = path->dentry; | |
590 | } | |
591 | ||
1da177e4 LT |
592 | /* |
593 | * This limits recursive symlink follows to 8, while | |
594 | * limiting consecutive symlinks to 40. | |
595 | * | |
596 | * Without that kind of total limit, nasty chains of consecutive | |
597 | * symlinks can cause almost arbitrarily long lookups. | |
598 | */ | |
90ebe565 | 599 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
600 | { |
601 | int err = -ELOOP; | |
602 | if (current->link_count >= MAX_NESTED_LINKS) | |
603 | goto loop; | |
604 | if (current->total_link_count >= 40) | |
605 | goto loop; | |
606 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); | |
607 | cond_resched(); | |
90ebe565 | 608 | err = security_inode_follow_link(path->dentry, nd); |
1da177e4 LT |
609 | if (err) |
610 | goto loop; | |
611 | current->link_count++; | |
612 | current->total_link_count++; | |
613 | nd->depth++; | |
cd4e91d3 | 614 | err = __do_follow_link(path, nd); |
839d9f93 AV |
615 | current->link_count--; |
616 | nd->depth--; | |
1da177e4 LT |
617 | return err; |
618 | loop: | |
09dd17d3 | 619 | dput_path(path, nd); |
839d9f93 | 620 | path_release(nd); |
1da177e4 LT |
621 | return err; |
622 | } | |
623 | ||
624 | int follow_up(struct vfsmount **mnt, struct dentry **dentry) | |
625 | { | |
626 | struct vfsmount *parent; | |
627 | struct dentry *mountpoint; | |
628 | spin_lock(&vfsmount_lock); | |
629 | parent=(*mnt)->mnt_parent; | |
630 | if (parent == *mnt) { | |
631 | spin_unlock(&vfsmount_lock); | |
632 | return 0; | |
633 | } | |
634 | mntget(parent); | |
635 | mountpoint=dget((*mnt)->mnt_mountpoint); | |
636 | spin_unlock(&vfsmount_lock); | |
637 | dput(*dentry); | |
638 | *dentry = mountpoint; | |
639 | mntput(*mnt); | |
640 | *mnt = parent; | |
641 | return 1; | |
642 | } | |
643 | ||
644 | /* no need for dcache_lock, as serialization is taken care in | |
645 | * namespace.c | |
646 | */ | |
463ffb2e AV |
647 | static int __follow_mount(struct path *path) |
648 | { | |
649 | int res = 0; | |
650 | while (d_mountpoint(path->dentry)) { | |
651 | struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); | |
652 | if (!mounted) | |
653 | break; | |
654 | dput(path->dentry); | |
655 | if (res) | |
656 | mntput(path->mnt); | |
657 | path->mnt = mounted; | |
658 | path->dentry = dget(mounted->mnt_root); | |
659 | res = 1; | |
660 | } | |
661 | return res; | |
662 | } | |
663 | ||
58c465eb | 664 | static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 | 665 | { |
1da177e4 LT |
666 | while (d_mountpoint(*dentry)) { |
667 | struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); | |
668 | if (!mounted) | |
669 | break; | |
58c465eb | 670 | dput(*dentry); |
1da177e4 LT |
671 | mntput(*mnt); |
672 | *mnt = mounted; | |
1da177e4 | 673 | *dentry = dget(mounted->mnt_root); |
1da177e4 | 674 | } |
1da177e4 LT |
675 | } |
676 | ||
677 | /* no need for dcache_lock, as serialization is taken care in | |
678 | * namespace.c | |
679 | */ | |
e13b210f | 680 | int follow_down(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 LT |
681 | { |
682 | struct vfsmount *mounted; | |
683 | ||
684 | mounted = lookup_mnt(*mnt, *dentry); | |
685 | if (mounted) { | |
e13b210f | 686 | dput(*dentry); |
1da177e4 LT |
687 | mntput(*mnt); |
688 | *mnt = mounted; | |
1da177e4 LT |
689 | *dentry = dget(mounted->mnt_root); |
690 | return 1; | |
691 | } | |
692 | return 0; | |
693 | } | |
694 | ||
f1662356 | 695 | static __always_inline void follow_dotdot(struct nameidata *nd) |
1da177e4 LT |
696 | { |
697 | while(1) { | |
698 | struct vfsmount *parent; | |
58c465eb | 699 | struct dentry *old = nd->dentry; |
1da177e4 LT |
700 | |
701 | read_lock(¤t->fs->lock); | |
58c465eb AV |
702 | if (nd->dentry == current->fs->root && |
703 | nd->mnt == current->fs->rootmnt) { | |
1da177e4 LT |
704 | read_unlock(¤t->fs->lock); |
705 | break; | |
706 | } | |
707 | read_unlock(¤t->fs->lock); | |
708 | spin_lock(&dcache_lock); | |
58c465eb AV |
709 | if (nd->dentry != nd->mnt->mnt_root) { |
710 | nd->dentry = dget(nd->dentry->d_parent); | |
1da177e4 LT |
711 | spin_unlock(&dcache_lock); |
712 | dput(old); | |
713 | break; | |
714 | } | |
715 | spin_unlock(&dcache_lock); | |
716 | spin_lock(&vfsmount_lock); | |
58c465eb AV |
717 | parent = nd->mnt->mnt_parent; |
718 | if (parent == nd->mnt) { | |
1da177e4 LT |
719 | spin_unlock(&vfsmount_lock); |
720 | break; | |
721 | } | |
722 | mntget(parent); | |
58c465eb | 723 | nd->dentry = dget(nd->mnt->mnt_mountpoint); |
1da177e4 LT |
724 | spin_unlock(&vfsmount_lock); |
725 | dput(old); | |
58c465eb AV |
726 | mntput(nd->mnt); |
727 | nd->mnt = parent; | |
1da177e4 | 728 | } |
58c465eb | 729 | follow_mount(&nd->mnt, &nd->dentry); |
1da177e4 LT |
730 | } |
731 | ||
1da177e4 LT |
732 | /* |
733 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
734 | * small and for now I'd prefer to have fast path as straight as possible. | |
735 | * It _is_ time-critical. | |
736 | */ | |
737 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
738 | struct path *path) | |
739 | { | |
740 | struct vfsmount *mnt = nd->mnt; | |
741 | struct dentry *dentry = __d_lookup(nd->dentry, name); | |
742 | ||
743 | if (!dentry) | |
744 | goto need_lookup; | |
745 | if (dentry->d_op && dentry->d_op->d_revalidate) | |
746 | goto need_revalidate; | |
747 | done: | |
748 | path->mnt = mnt; | |
749 | path->dentry = dentry; | |
634ee701 | 750 | __follow_mount(path); |
1da177e4 LT |
751 | return 0; |
752 | ||
753 | need_lookup: | |
754 | dentry = real_lookup(nd->dentry, name, nd); | |
755 | if (IS_ERR(dentry)) | |
756 | goto fail; | |
757 | goto done; | |
758 | ||
759 | need_revalidate: | |
760 | if (dentry->d_op->d_revalidate(dentry, nd)) | |
761 | goto done; | |
762 | if (d_invalidate(dentry)) | |
763 | goto done; | |
764 | dput(dentry); | |
765 | goto need_lookup; | |
766 | ||
767 | fail: | |
768 | return PTR_ERR(dentry); | |
769 | } | |
770 | ||
771 | /* | |
772 | * Name resolution. | |
ea3834d9 PM |
773 | * This is the basic name resolution function, turning a pathname into |
774 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 775 | * |
ea3834d9 PM |
776 | * Returns 0 and nd will have valid dentry and mnt on success. |
777 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 LT |
778 | */ |
779 | static fastcall int __link_path_walk(const char * name, struct nameidata *nd) | |
780 | { | |
781 | struct path next; | |
782 | struct inode *inode; | |
783 | int err; | |
784 | unsigned int lookup_flags = nd->flags; | |
785 | ||
786 | while (*name=='/') | |
787 | name++; | |
788 | if (!*name) | |
789 | goto return_reval; | |
790 | ||
791 | inode = nd->dentry->d_inode; | |
792 | if (nd->depth) | |
f55eab82 | 793 | lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); |
1da177e4 LT |
794 | |
795 | /* At this point we know we have a real path component. */ | |
796 | for(;;) { | |
797 | unsigned long hash; | |
798 | struct qstr this; | |
799 | unsigned int c; | |
800 | ||
cdce5d6b | 801 | nd->flags |= LOOKUP_CONTINUE; |
1da177e4 | 802 | err = exec_permission_lite(inode, nd); |
e4543edd CH |
803 | if (err == -EAGAIN) |
804 | err = vfs_permission(nd, MAY_EXEC); | |
1da177e4 LT |
805 | if (err) |
806 | break; | |
807 | ||
808 | this.name = name; | |
809 | c = *(const unsigned char *)name; | |
810 | ||
811 | hash = init_name_hash(); | |
812 | do { | |
813 | name++; | |
814 | hash = partial_name_hash(c, hash); | |
815 | c = *(const unsigned char *)name; | |
816 | } while (c && (c != '/')); | |
817 | this.len = name - (const char *) this.name; | |
818 | this.hash = end_name_hash(hash); | |
819 | ||
820 | /* remove trailing slashes? */ | |
821 | if (!c) | |
822 | goto last_component; | |
823 | while (*++name == '/'); | |
824 | if (!*name) | |
825 | goto last_with_slashes; | |
826 | ||
827 | /* | |
828 | * "." and ".." are special - ".." especially so because it has | |
829 | * to be able to know about the current root directory and | |
830 | * parent relationships. | |
831 | */ | |
832 | if (this.name[0] == '.') switch (this.len) { | |
833 | default: | |
834 | break; | |
835 | case 2: | |
836 | if (this.name[1] != '.') | |
837 | break; | |
58c465eb | 838 | follow_dotdot(nd); |
1da177e4 LT |
839 | inode = nd->dentry->d_inode; |
840 | /* fallthrough */ | |
841 | case 1: | |
842 | continue; | |
843 | } | |
844 | /* | |
845 | * See if the low-level filesystem might want | |
846 | * to use its own hash.. | |
847 | */ | |
848 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { | |
849 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); | |
850 | if (err < 0) | |
851 | break; | |
852 | } | |
1da177e4 LT |
853 | /* This does the actual lookups.. */ |
854 | err = do_lookup(nd, &this, &next); | |
855 | if (err) | |
856 | break; | |
1da177e4 LT |
857 | |
858 | err = -ENOENT; | |
859 | inode = next.dentry->d_inode; | |
860 | if (!inode) | |
861 | goto out_dput; | |
862 | err = -ENOTDIR; | |
863 | if (!inode->i_op) | |
864 | goto out_dput; | |
865 | ||
866 | if (inode->i_op->follow_link) { | |
90ebe565 | 867 | err = do_follow_link(&next, nd); |
1da177e4 LT |
868 | if (err) |
869 | goto return_err; | |
870 | err = -ENOENT; | |
871 | inode = nd->dentry->d_inode; | |
872 | if (!inode) | |
873 | break; | |
874 | err = -ENOTDIR; | |
875 | if (!inode->i_op) | |
876 | break; | |
09dd17d3 MS |
877 | } else |
878 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
879 | err = -ENOTDIR; |
880 | if (!inode->i_op->lookup) | |
881 | break; | |
882 | continue; | |
883 | /* here ends the main loop */ | |
884 | ||
885 | last_with_slashes: | |
886 | lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
887 | last_component: | |
f55eab82 TM |
888 | /* Clear LOOKUP_CONTINUE iff it was previously unset */ |
889 | nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; | |
1da177e4 LT |
890 | if (lookup_flags & LOOKUP_PARENT) |
891 | goto lookup_parent; | |
892 | if (this.name[0] == '.') switch (this.len) { | |
893 | default: | |
894 | break; | |
895 | case 2: | |
896 | if (this.name[1] != '.') | |
897 | break; | |
58c465eb | 898 | follow_dotdot(nd); |
1da177e4 LT |
899 | inode = nd->dentry->d_inode; |
900 | /* fallthrough */ | |
901 | case 1: | |
902 | goto return_reval; | |
903 | } | |
904 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { | |
905 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); | |
906 | if (err < 0) | |
907 | break; | |
908 | } | |
909 | err = do_lookup(nd, &this, &next); | |
910 | if (err) | |
911 | break; | |
1da177e4 LT |
912 | inode = next.dentry->d_inode; |
913 | if ((lookup_flags & LOOKUP_FOLLOW) | |
914 | && inode && inode->i_op && inode->i_op->follow_link) { | |
90ebe565 | 915 | err = do_follow_link(&next, nd); |
1da177e4 LT |
916 | if (err) |
917 | goto return_err; | |
918 | inode = nd->dentry->d_inode; | |
09dd17d3 MS |
919 | } else |
920 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
921 | err = -ENOENT; |
922 | if (!inode) | |
923 | break; | |
924 | if (lookup_flags & LOOKUP_DIRECTORY) { | |
925 | err = -ENOTDIR; | |
926 | if (!inode->i_op || !inode->i_op->lookup) | |
927 | break; | |
928 | } | |
929 | goto return_base; | |
930 | lookup_parent: | |
931 | nd->last = this; | |
932 | nd->last_type = LAST_NORM; | |
933 | if (this.name[0] != '.') | |
934 | goto return_base; | |
935 | if (this.len == 1) | |
936 | nd->last_type = LAST_DOT; | |
937 | else if (this.len == 2 && this.name[1] == '.') | |
938 | nd->last_type = LAST_DOTDOT; | |
939 | else | |
940 | goto return_base; | |
941 | return_reval: | |
942 | /* | |
943 | * We bypassed the ordinary revalidation routines. | |
944 | * We may need to check the cached dentry for staleness. | |
945 | */ | |
946 | if (nd->dentry && nd->dentry->d_sb && | |
947 | (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { | |
948 | err = -ESTALE; | |
949 | /* Note: we do not d_invalidate() */ | |
950 | if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd)) | |
951 | break; | |
952 | } | |
953 | return_base: | |
954 | return 0; | |
955 | out_dput: | |
09dd17d3 | 956 | dput_path(&next, nd); |
1da177e4 LT |
957 | break; |
958 | } | |
959 | path_release(nd); | |
960 | return_err: | |
961 | return err; | |
962 | } | |
963 | ||
964 | /* | |
965 | * Wrapper to retry pathname resolution whenever the underlying | |
966 | * file system returns an ESTALE. | |
967 | * | |
968 | * Retry the whole path once, forcing real lookup requests | |
969 | * instead of relying on the dcache. | |
970 | */ | |
971 | int fastcall link_path_walk(const char *name, struct nameidata *nd) | |
972 | { | |
973 | struct nameidata save = *nd; | |
974 | int result; | |
975 | ||
976 | /* make sure the stuff we saved doesn't go away */ | |
977 | dget(save.dentry); | |
978 | mntget(save.mnt); | |
979 | ||
980 | result = __link_path_walk(name, nd); | |
981 | if (result == -ESTALE) { | |
982 | *nd = save; | |
983 | dget(nd->dentry); | |
984 | mntget(nd->mnt); | |
985 | nd->flags |= LOOKUP_REVAL; | |
986 | result = __link_path_walk(name, nd); | |
987 | } | |
988 | ||
989 | dput(save.dentry); | |
990 | mntput(save.mnt); | |
991 | ||
992 | return result; | |
993 | } | |
994 | ||
995 | int fastcall path_walk(const char * name, struct nameidata *nd) | |
996 | { | |
997 | current->total_link_count = 0; | |
998 | return link_path_walk(name, nd); | |
999 | } | |
1000 | ||
ea3834d9 PM |
1001 | /* |
1002 | * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if | |
1003 | * everything is done. Returns 0 and drops input nd, if lookup failed; | |
1004 | */ | |
1da177e4 LT |
1005 | static int __emul_lookup_dentry(const char *name, struct nameidata *nd) |
1006 | { | |
1007 | if (path_walk(name, nd)) | |
1008 | return 0; /* something went wrong... */ | |
1009 | ||
1010 | if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) { | |
1011 | struct dentry *old_dentry = nd->dentry; | |
1012 | struct vfsmount *old_mnt = nd->mnt; | |
1013 | struct qstr last = nd->last; | |
1014 | int last_type = nd->last_type; | |
1015 | /* | |
1016 | * NAME was not found in alternate root or it's a directory. Try to find | |
1017 | * it in the normal root: | |
1018 | */ | |
1019 | nd->last_type = LAST_ROOT; | |
1020 | read_lock(¤t->fs->lock); | |
1021 | nd->mnt = mntget(current->fs->rootmnt); | |
1022 | nd->dentry = dget(current->fs->root); | |
1023 | read_unlock(¤t->fs->lock); | |
1024 | if (path_walk(name, nd) == 0) { | |
1025 | if (nd->dentry->d_inode) { | |
1026 | dput(old_dentry); | |
1027 | mntput(old_mnt); | |
1028 | return 1; | |
1029 | } | |
1030 | path_release(nd); | |
1031 | } | |
1032 | nd->dentry = old_dentry; | |
1033 | nd->mnt = old_mnt; | |
1034 | nd->last = last; | |
1035 | nd->last_type = last_type; | |
1036 | } | |
1037 | return 1; | |
1038 | } | |
1039 | ||
1040 | void set_fs_altroot(void) | |
1041 | { | |
1042 | char *emul = __emul_prefix(); | |
1043 | struct nameidata nd; | |
1044 | struct vfsmount *mnt = NULL, *oldmnt; | |
1045 | struct dentry *dentry = NULL, *olddentry; | |
1046 | int err; | |
1047 | ||
1048 | if (!emul) | |
1049 | goto set_it; | |
1050 | err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); | |
1051 | if (!err) { | |
1052 | mnt = nd.mnt; | |
1053 | dentry = nd.dentry; | |
1054 | } | |
1055 | set_it: | |
1056 | write_lock(¤t->fs->lock); | |
1057 | oldmnt = current->fs->altrootmnt; | |
1058 | olddentry = current->fs->altroot; | |
1059 | current->fs->altrootmnt = mnt; | |
1060 | current->fs->altroot = dentry; | |
1061 | write_unlock(¤t->fs->lock); | |
1062 | if (olddentry) { | |
1063 | dput(olddentry); | |
1064 | mntput(oldmnt); | |
1065 | } | |
1066 | } | |
1067 | ||
ea3834d9 | 1068 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
5590ff0d UD |
1069 | static int fastcall do_path_lookup(int dfd, const char *name, |
1070 | unsigned int flags, struct nameidata *nd) | |
1da177e4 | 1071 | { |
ea3834d9 | 1072 | int retval = 0; |
170aa3d0 UD |
1073 | int fput_needed; |
1074 | struct file *file; | |
1da177e4 LT |
1075 | |
1076 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
1077 | nd->flags = flags; | |
1078 | nd->depth = 0; | |
1079 | ||
1080 | read_lock(¤t->fs->lock); | |
1081 | if (*name=='/') { | |
1082 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { | |
1083 | nd->mnt = mntget(current->fs->altrootmnt); | |
1084 | nd->dentry = dget(current->fs->altroot); | |
1085 | read_unlock(¤t->fs->lock); | |
1086 | if (__emul_lookup_dentry(name,nd)) | |
ea3834d9 | 1087 | goto out; /* found in altroot */ |
1da177e4 LT |
1088 | read_lock(¤t->fs->lock); |
1089 | } | |
1090 | nd->mnt = mntget(current->fs->rootmnt); | |
1091 | nd->dentry = dget(current->fs->root); | |
5590ff0d | 1092 | } else if (dfd == AT_FDCWD) { |
1da177e4 LT |
1093 | nd->mnt = mntget(current->fs->pwdmnt); |
1094 | nd->dentry = dget(current->fs->pwd); | |
5590ff0d | 1095 | } else { |
5590ff0d UD |
1096 | struct dentry *dentry; |
1097 | ||
1098 | file = fget_light(dfd, &fput_needed); | |
170aa3d0 UD |
1099 | retval = -EBADF; |
1100 | if (!file) | |
1101 | goto unlock_fail; | |
5590ff0d UD |
1102 | |
1103 | dentry = file->f_dentry; | |
1104 | ||
170aa3d0 UD |
1105 | retval = -ENOTDIR; |
1106 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
1107 | goto fput_unlock_fail; | |
5590ff0d UD |
1108 | |
1109 | retval = file_permission(file, MAY_EXEC); | |
170aa3d0 UD |
1110 | if (retval) |
1111 | goto fput_unlock_fail; | |
5590ff0d UD |
1112 | |
1113 | nd->mnt = mntget(file->f_vfsmnt); | |
1114 | nd->dentry = dget(dentry); | |
1115 | ||
1116 | fput_light(file, fput_needed); | |
1da177e4 LT |
1117 | } |
1118 | read_unlock(¤t->fs->lock); | |
1119 | current->total_link_count = 0; | |
1120 | retval = link_path_walk(name, nd); | |
ea3834d9 | 1121 | out: |
3bc8414b S |
1122 | if (likely(retval == 0)) { |
1123 | if (unlikely(current->audit_context && nd && nd->dentry && | |
1124 | nd->dentry->d_inode)) | |
ae7b961b | 1125 | audit_inode(name, nd->dentry->d_inode, flags); |
3bc8414b | 1126 | } |
170aa3d0 UD |
1127 | return retval; |
1128 | ||
1129 | fput_unlock_fail: | |
1130 | fput_light(file, fput_needed); | |
1131 | unlock_fail: | |
1132 | read_unlock(¤t->fs->lock); | |
1da177e4 LT |
1133 | return retval; |
1134 | } | |
1135 | ||
5590ff0d UD |
1136 | int fastcall path_lookup(const char *name, unsigned int flags, |
1137 | struct nameidata *nd) | |
1138 | { | |
1139 | return do_path_lookup(AT_FDCWD, name, flags, nd); | |
1140 | } | |
1141 | ||
1142 | static int __path_lookup_intent_open(int dfd, const char *name, | |
1143 | unsigned int lookup_flags, struct nameidata *nd, | |
1144 | int open_flags, int create_mode) | |
834f2a4a TM |
1145 | { |
1146 | struct file *filp = get_empty_filp(); | |
1147 | int err; | |
1148 | ||
1149 | if (filp == NULL) | |
1150 | return -ENFILE; | |
1151 | nd->intent.open.file = filp; | |
1152 | nd->intent.open.flags = open_flags; | |
1153 | nd->intent.open.create_mode = create_mode; | |
5590ff0d | 1154 | err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); |
834f2a4a TM |
1155 | if (IS_ERR(nd->intent.open.file)) { |
1156 | if (err == 0) { | |
1157 | err = PTR_ERR(nd->intent.open.file); | |
1158 | path_release(nd); | |
1159 | } | |
1160 | } else if (err != 0) | |
1161 | release_open_intent(nd); | |
1162 | return err; | |
1163 | } | |
1164 | ||
1165 | /** | |
1166 | * path_lookup_open - lookup a file path with open intent | |
7045f37b | 1167 | * @dfd: the directory to use as base, or AT_FDCWD |
834f2a4a TM |
1168 | * @name: pointer to file name |
1169 | * @lookup_flags: lookup intent flags | |
1170 | * @nd: pointer to nameidata | |
1171 | * @open_flags: open intent flags | |
1172 | */ | |
5590ff0d | 1173 | int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, |
834f2a4a TM |
1174 | struct nameidata *nd, int open_flags) |
1175 | { | |
5590ff0d | 1176 | return __path_lookup_intent_open(dfd, name, lookup_flags, nd, |
834f2a4a TM |
1177 | open_flags, 0); |
1178 | } | |
1179 | ||
1180 | /** | |
1181 | * path_lookup_create - lookup a file path with open + create intent | |
7045f37b | 1182 | * @dfd: the directory to use as base, or AT_FDCWD |
834f2a4a TM |
1183 | * @name: pointer to file name |
1184 | * @lookup_flags: lookup intent flags | |
1185 | * @nd: pointer to nameidata | |
1186 | * @open_flags: open intent flags | |
1187 | * @create_mode: create intent flags | |
1188 | */ | |
5590ff0d UD |
1189 | static int path_lookup_create(int dfd, const char *name, |
1190 | unsigned int lookup_flags, struct nameidata *nd, | |
1191 | int open_flags, int create_mode) | |
834f2a4a | 1192 | { |
5590ff0d UD |
1193 | return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE, |
1194 | nd, open_flags, create_mode); | |
834f2a4a TM |
1195 | } |
1196 | ||
1197 | int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, | |
1198 | struct nameidata *nd, int open_flags) | |
1199 | { | |
1200 | char *tmp = getname(name); | |
1201 | int err = PTR_ERR(tmp); | |
1202 | ||
1203 | if (!IS_ERR(tmp)) { | |
5590ff0d | 1204 | err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0); |
834f2a4a TM |
1205 | putname(tmp); |
1206 | } | |
1207 | return err; | |
1208 | } | |
1209 | ||
1da177e4 LT |
1210 | /* |
1211 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1212 | * needs parent already locked. Doesn't follow mounts. | |
1213 | * SMP-safe. | |
1214 | */ | |
1215 | static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd) | |
1216 | { | |
1217 | struct dentry * dentry; | |
1218 | struct inode *inode; | |
1219 | int err; | |
1220 | ||
1221 | inode = base->d_inode; | |
1222 | err = permission(inode, MAY_EXEC, nd); | |
1223 | dentry = ERR_PTR(err); | |
1224 | if (err) | |
1225 | goto out; | |
1226 | ||
1227 | /* | |
1228 | * See if the low-level filesystem might want | |
1229 | * to use its own hash.. | |
1230 | */ | |
1231 | if (base->d_op && base->d_op->d_hash) { | |
1232 | err = base->d_op->d_hash(base, name); | |
1233 | dentry = ERR_PTR(err); | |
1234 | if (err < 0) | |
1235 | goto out; | |
1236 | } | |
1237 | ||
1238 | dentry = cached_lookup(base, name, nd); | |
1239 | if (!dentry) { | |
1240 | struct dentry *new = d_alloc(base, name); | |
1241 | dentry = ERR_PTR(-ENOMEM); | |
1242 | if (!new) | |
1243 | goto out; | |
1244 | dentry = inode->i_op->lookup(inode, new, nd); | |
1245 | if (!dentry) | |
1246 | dentry = new; | |
1247 | else | |
1248 | dput(new); | |
1249 | } | |
1250 | out: | |
1251 | return dentry; | |
1252 | } | |
1253 | ||
49705b77 | 1254 | struct dentry * lookup_hash(struct nameidata *nd) |
1da177e4 | 1255 | { |
49705b77 | 1256 | return __lookup_hash(&nd->last, nd->dentry, nd); |
1da177e4 LT |
1257 | } |
1258 | ||
1259 | /* SMP-safe */ | |
1260 | struct dentry * lookup_one_len(const char * name, struct dentry * base, int len) | |
1261 | { | |
1262 | unsigned long hash; | |
1263 | struct qstr this; | |
1264 | unsigned int c; | |
1265 | ||
1266 | this.name = name; | |
1267 | this.len = len; | |
1268 | if (!len) | |
1269 | goto access; | |
1270 | ||
1271 | hash = init_name_hash(); | |
1272 | while (len--) { | |
1273 | c = *(const unsigned char *)name++; | |
1274 | if (c == '/' || c == '\0') | |
1275 | goto access; | |
1276 | hash = partial_name_hash(c, hash); | |
1277 | } | |
1278 | this.hash = end_name_hash(hash); | |
1279 | ||
49705b77 | 1280 | return __lookup_hash(&this, base, NULL); |
1da177e4 LT |
1281 | access: |
1282 | return ERR_PTR(-EACCES); | |
1283 | } | |
1284 | ||
1285 | /* | |
1286 | * namei() | |
1287 | * | |
1288 | * is used by most simple commands to get the inode of a specified name. | |
1289 | * Open, link etc use their own routines, but this is enough for things | |
1290 | * like 'chmod' etc. | |
1291 | * | |
1292 | * namei exists in two versions: namei/lnamei. The only difference is | |
1293 | * that namei follows links, while lnamei does not. | |
1294 | * SMP-safe | |
1295 | */ | |
5590ff0d UD |
1296 | int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags, |
1297 | struct nameidata *nd) | |
1da177e4 LT |
1298 | { |
1299 | char *tmp = getname(name); | |
1300 | int err = PTR_ERR(tmp); | |
1301 | ||
1302 | if (!IS_ERR(tmp)) { | |
5590ff0d | 1303 | err = do_path_lookup(dfd, tmp, flags, nd); |
1da177e4 LT |
1304 | putname(tmp); |
1305 | } | |
1306 | return err; | |
1307 | } | |
1308 | ||
5590ff0d UD |
1309 | int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) |
1310 | { | |
1311 | return __user_walk_fd(AT_FDCWD, name, flags, nd); | |
1312 | } | |
1313 | ||
1da177e4 LT |
1314 | /* |
1315 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1316 | * minimal. | |
1317 | */ | |
1318 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1319 | { | |
1320 | if (!(dir->i_mode & S_ISVTX)) | |
1321 | return 0; | |
1322 | if (inode->i_uid == current->fsuid) | |
1323 | return 0; | |
1324 | if (dir->i_uid == current->fsuid) | |
1325 | return 0; | |
1326 | return !capable(CAP_FOWNER); | |
1327 | } | |
1328 | ||
1329 | /* | |
1330 | * Check whether we can remove a link victim from directory dir, check | |
1331 | * whether the type of victim is right. | |
1332 | * 1. We can't do it if dir is read-only (done in permission()) | |
1333 | * 2. We should have write and exec permissions on dir | |
1334 | * 3. We can't remove anything from append-only dir | |
1335 | * 4. We can't do anything with immutable dir (done in permission()) | |
1336 | * 5. If the sticky bit on dir is set we should either | |
1337 | * a. be owner of dir, or | |
1338 | * b. be owner of victim, or | |
1339 | * c. have CAP_FOWNER capability | |
1340 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1341 | * links pointing to it. | |
1342 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1343 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1344 | * 9. We can't remove a root or mountpoint. | |
1345 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1346 | * nfs_async_unlink(). | |
1347 | */ | |
858119e1 | 1348 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1349 | { |
1350 | int error; | |
1351 | ||
1352 | if (!victim->d_inode) | |
1353 | return -ENOENT; | |
1354 | ||
1355 | BUG_ON(victim->d_parent->d_inode != dir); | |
1356 | ||
1357 | error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); | |
1358 | if (error) | |
1359 | return error; | |
1360 | if (IS_APPEND(dir)) | |
1361 | return -EPERM; | |
1362 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
1363 | IS_IMMUTABLE(victim->d_inode)) | |
1364 | return -EPERM; | |
1365 | if (isdir) { | |
1366 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1367 | return -ENOTDIR; | |
1368 | if (IS_ROOT(victim)) | |
1369 | return -EBUSY; | |
1370 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1371 | return -EISDIR; | |
1372 | if (IS_DEADDIR(dir)) | |
1373 | return -ENOENT; | |
1374 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1375 | return -EBUSY; | |
1376 | return 0; | |
1377 | } | |
1378 | ||
1379 | /* Check whether we can create an object with dentry child in directory | |
1380 | * dir. | |
1381 | * 1. We can't do it if child already exists (open has special treatment for | |
1382 | * this case, but since we are inlined it's OK) | |
1383 | * 2. We can't do it if dir is read-only (done in permission()) | |
1384 | * 3. We should have write and exec permissions on dir | |
1385 | * 4. We can't do it if dir is immutable (done in permission()) | |
1386 | */ | |
1387 | static inline int may_create(struct inode *dir, struct dentry *child, | |
1388 | struct nameidata *nd) | |
1389 | { | |
1390 | if (child->d_inode) | |
1391 | return -EEXIST; | |
1392 | if (IS_DEADDIR(dir)) | |
1393 | return -ENOENT; | |
1394 | return permission(dir,MAY_WRITE | MAY_EXEC, nd); | |
1395 | } | |
1396 | ||
1397 | /* | |
1da177e4 LT |
1398 | * O_DIRECTORY translates into forcing a directory lookup. |
1399 | */ | |
1400 | static inline int lookup_flags(unsigned int f) | |
1401 | { | |
1402 | unsigned long retval = LOOKUP_FOLLOW; | |
1403 | ||
1404 | if (f & O_NOFOLLOW) | |
1405 | retval &= ~LOOKUP_FOLLOW; | |
1406 | ||
1da177e4 LT |
1407 | if (f & O_DIRECTORY) |
1408 | retval |= LOOKUP_DIRECTORY; | |
1409 | ||
1410 | return retval; | |
1411 | } | |
1412 | ||
1413 | /* | |
1414 | * p1 and p2 should be directories on the same fs. | |
1415 | */ | |
1416 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1417 | { | |
1418 | struct dentry *p; | |
1419 | ||
1420 | if (p1 == p2) { | |
1b1dcc1b | 1421 | mutex_lock(&p1->d_inode->i_mutex); |
1da177e4 LT |
1422 | return NULL; |
1423 | } | |
1424 | ||
1425 | down(&p1->d_inode->i_sb->s_vfs_rename_sem); | |
1426 | ||
1427 | for (p = p1; p->d_parent != p; p = p->d_parent) { | |
1428 | if (p->d_parent == p2) { | |
1b1dcc1b JS |
1429 | mutex_lock(&p2->d_inode->i_mutex); |
1430 | mutex_lock(&p1->d_inode->i_mutex); | |
1da177e4 LT |
1431 | return p; |
1432 | } | |
1433 | } | |
1434 | ||
1435 | for (p = p2; p->d_parent != p; p = p->d_parent) { | |
1436 | if (p->d_parent == p1) { | |
1b1dcc1b JS |
1437 | mutex_lock(&p1->d_inode->i_mutex); |
1438 | mutex_lock(&p2->d_inode->i_mutex); | |
1da177e4 LT |
1439 | return p; |
1440 | } | |
1441 | } | |
1442 | ||
1b1dcc1b JS |
1443 | mutex_lock(&p1->d_inode->i_mutex); |
1444 | mutex_lock(&p2->d_inode->i_mutex); | |
1da177e4 LT |
1445 | return NULL; |
1446 | } | |
1447 | ||
1448 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1449 | { | |
1b1dcc1b | 1450 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1451 | if (p1 != p2) { |
1b1dcc1b | 1452 | mutex_unlock(&p2->d_inode->i_mutex); |
1da177e4 LT |
1453 | up(&p1->d_inode->i_sb->s_vfs_rename_sem); |
1454 | } | |
1455 | } | |
1456 | ||
1457 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1458 | struct nameidata *nd) | |
1459 | { | |
1460 | int error = may_create(dir, dentry, nd); | |
1461 | ||
1462 | if (error) | |
1463 | return error; | |
1464 | ||
1465 | if (!dir->i_op || !dir->i_op->create) | |
1466 | return -EACCES; /* shouldn't it be ENOSYS? */ | |
1467 | mode &= S_IALLUGO; | |
1468 | mode |= S_IFREG; | |
1469 | error = security_inode_create(dir, dentry, mode); | |
1470 | if (error) | |
1471 | return error; | |
1472 | DQUOT_INIT(dir); | |
1473 | error = dir->i_op->create(dir, dentry, mode, nd); | |
a74574aa | 1474 | if (!error) |
0eeca283 | 1475 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
1476 | return error; |
1477 | } | |
1478 | ||
1479 | int may_open(struct nameidata *nd, int acc_mode, int flag) | |
1480 | { | |
1481 | struct dentry *dentry = nd->dentry; | |
1482 | struct inode *inode = dentry->d_inode; | |
1483 | int error; | |
1484 | ||
1485 | if (!inode) | |
1486 | return -ENOENT; | |
1487 | ||
1488 | if (S_ISLNK(inode->i_mode)) | |
1489 | return -ELOOP; | |
1490 | ||
1491 | if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE)) | |
1492 | return -EISDIR; | |
1493 | ||
e4543edd | 1494 | error = vfs_permission(nd, acc_mode); |
1da177e4 LT |
1495 | if (error) |
1496 | return error; | |
1497 | ||
1498 | /* | |
1499 | * FIFO's, sockets and device files are special: they don't | |
1500 | * actually live on the filesystem itself, and as such you | |
1501 | * can write to them even if the filesystem is read-only. | |
1502 | */ | |
1503 | if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { | |
1504 | flag &= ~O_TRUNC; | |
1505 | } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { | |
1506 | if (nd->mnt->mnt_flags & MNT_NODEV) | |
1507 | return -EACCES; | |
1508 | ||
1509 | flag &= ~O_TRUNC; | |
1510 | } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE)) | |
1511 | return -EROFS; | |
1512 | /* | |
1513 | * An append-only file must be opened in append mode for writing. | |
1514 | */ | |
1515 | if (IS_APPEND(inode)) { | |
1516 | if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) | |
1517 | return -EPERM; | |
1518 | if (flag & O_TRUNC) | |
1519 | return -EPERM; | |
1520 | } | |
1521 | ||
1522 | /* O_NOATIME can only be set by the owner or superuser */ | |
1523 | if (flag & O_NOATIME) | |
1524 | if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) | |
1525 | return -EPERM; | |
1526 | ||
1527 | /* | |
1528 | * Ensure there are no outstanding leases on the file. | |
1529 | */ | |
1530 | error = break_lease(inode, flag); | |
1531 | if (error) | |
1532 | return error; | |
1533 | ||
1534 | if (flag & O_TRUNC) { | |
1535 | error = get_write_access(inode); | |
1536 | if (error) | |
1537 | return error; | |
1538 | ||
1539 | /* | |
1540 | * Refuse to truncate files with mandatory locks held on them. | |
1541 | */ | |
1542 | error = locks_verify_locked(inode); | |
1543 | if (!error) { | |
1544 | DQUOT_INIT(inode); | |
1545 | ||
4a30131e | 1546 | error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, NULL); |
1da177e4 LT |
1547 | } |
1548 | put_write_access(inode); | |
1549 | if (error) | |
1550 | return error; | |
1551 | } else | |
1552 | if (flag & FMODE_WRITE) | |
1553 | DQUOT_INIT(inode); | |
1554 | ||
1555 | return 0; | |
1556 | } | |
1557 | ||
1558 | /* | |
1559 | * open_namei() | |
1560 | * | |
1561 | * namei for open - this is in fact almost the whole open-routine. | |
1562 | * | |
1563 | * Note that the low bits of "flag" aren't the same as in the open | |
1564 | * system call - they are 00 - no permissions needed | |
1565 | * 01 - read permission needed | |
1566 | * 10 - write permission needed | |
1567 | * 11 - read/write permissions needed | |
1568 | * which is a lot more logical, and also allows the "no perm" needed | |
1569 | * for symlinks (where the permissions are checked later). | |
1570 | * SMP-safe | |
1571 | */ | |
5590ff0d UD |
1572 | int open_namei(int dfd, const char *pathname, int flag, |
1573 | int mode, struct nameidata *nd) | |
1da177e4 | 1574 | { |
834f2a4a | 1575 | int acc_mode, error; |
4e7506e4 | 1576 | struct path path; |
1da177e4 LT |
1577 | struct dentry *dir; |
1578 | int count = 0; | |
1579 | ||
1580 | acc_mode = ACC_MODE(flag); | |
1581 | ||
834f2a4a TM |
1582 | /* O_TRUNC implies we need access checks for write permissions */ |
1583 | if (flag & O_TRUNC) | |
1584 | acc_mode |= MAY_WRITE; | |
1585 | ||
1da177e4 LT |
1586 | /* Allow the LSM permission hook to distinguish append |
1587 | access from general write access. */ | |
1588 | if (flag & O_APPEND) | |
1589 | acc_mode |= MAY_APPEND; | |
1590 | ||
1da177e4 LT |
1591 | /* |
1592 | * The simplest case - just a plain lookup. | |
1593 | */ | |
1594 | if (!(flag & O_CREAT)) { | |
5590ff0d UD |
1595 | error = path_lookup_open(dfd, pathname, lookup_flags(flag), |
1596 | nd, flag); | |
1da177e4 LT |
1597 | if (error) |
1598 | return error; | |
1599 | goto ok; | |
1600 | } | |
1601 | ||
1602 | /* | |
1603 | * Create - we need to know the parent. | |
1604 | */ | |
5590ff0d | 1605 | error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode); |
1da177e4 LT |
1606 | if (error) |
1607 | return error; | |
1608 | ||
1609 | /* | |
1610 | * We have the parent and last component. First of all, check | |
1611 | * that we are not asked to creat(2) an obvious directory - that | |
1612 | * will not do. | |
1613 | */ | |
1614 | error = -EISDIR; | |
1615 | if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len]) | |
1616 | goto exit; | |
1617 | ||
1618 | dir = nd->dentry; | |
1619 | nd->flags &= ~LOOKUP_PARENT; | |
1b1dcc1b | 1620 | mutex_lock(&dir->d_inode->i_mutex); |
49705b77 | 1621 | path.dentry = lookup_hash(nd); |
d73ffe16 | 1622 | path.mnt = nd->mnt; |
1da177e4 LT |
1623 | |
1624 | do_last: | |
4e7506e4 AV |
1625 | error = PTR_ERR(path.dentry); |
1626 | if (IS_ERR(path.dentry)) { | |
1b1dcc1b | 1627 | mutex_unlock(&dir->d_inode->i_mutex); |
1da177e4 LT |
1628 | goto exit; |
1629 | } | |
1630 | ||
1631 | /* Negative dentry, just create the file */ | |
4e7506e4 | 1632 | if (!path.dentry->d_inode) { |
1da177e4 LT |
1633 | if (!IS_POSIXACL(dir->d_inode)) |
1634 | mode &= ~current->fs->umask; | |
4e7506e4 | 1635 | error = vfs_create(dir->d_inode, path.dentry, mode, nd); |
1b1dcc1b | 1636 | mutex_unlock(&dir->d_inode->i_mutex); |
1da177e4 | 1637 | dput(nd->dentry); |
4e7506e4 | 1638 | nd->dentry = path.dentry; |
1da177e4 LT |
1639 | if (error) |
1640 | goto exit; | |
1641 | /* Don't check for write permission, don't truncate */ | |
1642 | acc_mode = 0; | |
1643 | flag &= ~O_TRUNC; | |
1644 | goto ok; | |
1645 | } | |
1646 | ||
1647 | /* | |
1648 | * It already exists. | |
1649 | */ | |
1b1dcc1b | 1650 | mutex_unlock(&dir->d_inode->i_mutex); |
1da177e4 LT |
1651 | |
1652 | error = -EEXIST; | |
1653 | if (flag & O_EXCL) | |
1654 | goto exit_dput; | |
1655 | ||
e13b210f | 1656 | if (__follow_mount(&path)) { |
1da177e4 | 1657 | error = -ELOOP; |
ba7a4c1a AV |
1658 | if (flag & O_NOFOLLOW) |
1659 | goto exit_dput; | |
1da177e4 LT |
1660 | } |
1661 | error = -ENOENT; | |
4e7506e4 | 1662 | if (!path.dentry->d_inode) |
1da177e4 | 1663 | goto exit_dput; |
4e7506e4 | 1664 | if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) |
1da177e4 LT |
1665 | goto do_link; |
1666 | ||
09dd17d3 | 1667 | path_to_nameidata(&path, nd); |
1da177e4 | 1668 | error = -EISDIR; |
4e7506e4 | 1669 | if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) |
1da177e4 LT |
1670 | goto exit; |
1671 | ok: | |
1672 | error = may_open(nd, acc_mode, flag); | |
1673 | if (error) | |
1674 | goto exit; | |
1675 | return 0; | |
1676 | ||
1677 | exit_dput: | |
09dd17d3 | 1678 | dput_path(&path, nd); |
1da177e4 | 1679 | exit: |
834f2a4a TM |
1680 | if (!IS_ERR(nd->intent.open.file)) |
1681 | release_open_intent(nd); | |
1da177e4 LT |
1682 | path_release(nd); |
1683 | return error; | |
1684 | ||
1685 | do_link: | |
1686 | error = -ELOOP; | |
1687 | if (flag & O_NOFOLLOW) | |
1688 | goto exit_dput; | |
1689 | /* | |
1690 | * This is subtle. Instead of calling do_follow_link() we do the | |
1691 | * thing by hands. The reason is that this way we have zero link_count | |
1692 | * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. | |
1693 | * After that we have the parent and last component, i.e. | |
1694 | * we are in the same situation as after the first path_walk(). | |
1695 | * Well, almost - if the last component is normal we get its copy | |
1696 | * stored in nd->last.name and we will have to putname() it when we | |
1697 | * are done. Procfs-like symlinks just set LAST_BIND. | |
1698 | */ | |
1699 | nd->flags |= LOOKUP_PARENT; | |
4e7506e4 | 1700 | error = security_inode_follow_link(path.dentry, nd); |
1da177e4 LT |
1701 | if (error) |
1702 | goto exit_dput; | |
cd4e91d3 | 1703 | error = __do_follow_link(&path, nd); |
1da177e4 LT |
1704 | if (error) |
1705 | return error; | |
1706 | nd->flags &= ~LOOKUP_PARENT; | |
d671d5e5 | 1707 | if (nd->last_type == LAST_BIND) |
1da177e4 | 1708 | goto ok; |
1da177e4 LT |
1709 | error = -EISDIR; |
1710 | if (nd->last_type != LAST_NORM) | |
1711 | goto exit; | |
1712 | if (nd->last.name[nd->last.len]) { | |
82984114 | 1713 | __putname(nd->last.name); |
1da177e4 LT |
1714 | goto exit; |
1715 | } | |
1716 | error = -ELOOP; | |
1717 | if (count++==32) { | |
82984114 | 1718 | __putname(nd->last.name); |
1da177e4 LT |
1719 | goto exit; |
1720 | } | |
1721 | dir = nd->dentry; | |
1b1dcc1b | 1722 | mutex_lock(&dir->d_inode->i_mutex); |
49705b77 | 1723 | path.dentry = lookup_hash(nd); |
d671d5e5 | 1724 | path.mnt = nd->mnt; |
82984114 | 1725 | __putname(nd->last.name); |
1da177e4 LT |
1726 | goto do_last; |
1727 | } | |
1728 | ||
1729 | /** | |
1730 | * lookup_create - lookup a dentry, creating it if it doesn't exist | |
1731 | * @nd: nameidata info | |
1732 | * @is_dir: directory flag | |
1733 | * | |
1734 | * Simple function to lookup and return a dentry and create it | |
1735 | * if it doesn't exist. Is SMP-safe. | |
c663e5d8 | 1736 | * |
1b1dcc1b | 1737 | * Returns with nd->dentry->d_inode->i_mutex locked. |
1da177e4 LT |
1738 | */ |
1739 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) | |
1740 | { | |
c663e5d8 | 1741 | struct dentry *dentry = ERR_PTR(-EEXIST); |
1da177e4 | 1742 | |
1b1dcc1b | 1743 | mutex_lock(&nd->dentry->d_inode->i_mutex); |
c663e5d8 CH |
1744 | /* |
1745 | * Yucky last component or no last component at all? | |
1746 | * (foo/., foo/.., /////) | |
1747 | */ | |
1da177e4 LT |
1748 | if (nd->last_type != LAST_NORM) |
1749 | goto fail; | |
1750 | nd->flags &= ~LOOKUP_PARENT; | |
c663e5d8 CH |
1751 | |
1752 | /* | |
1753 | * Do the final lookup. | |
1754 | */ | |
49705b77 | 1755 | dentry = lookup_hash(nd); |
1da177e4 LT |
1756 | if (IS_ERR(dentry)) |
1757 | goto fail; | |
c663e5d8 CH |
1758 | |
1759 | /* | |
1760 | * Special case - lookup gave negative, but... we had foo/bar/ | |
1761 | * From the vfs_mknod() POV we just have a negative dentry - | |
1762 | * all is fine. Let's be bastards - you had / on the end, you've | |
1763 | * been asking for (non-existent) directory. -ENOENT for you. | |
1764 | */ | |
1da177e4 LT |
1765 | if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) |
1766 | goto enoent; | |
1767 | return dentry; | |
1768 | enoent: | |
1769 | dput(dentry); | |
1770 | dentry = ERR_PTR(-ENOENT); | |
1771 | fail: | |
1772 | return dentry; | |
1773 | } | |
f81a0bff | 1774 | EXPORT_SYMBOL_GPL(lookup_create); |
1da177e4 LT |
1775 | |
1776 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
1777 | { | |
1778 | int error = may_create(dir, dentry, NULL); | |
1779 | ||
1780 | if (error) | |
1781 | return error; | |
1782 | ||
1783 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) | |
1784 | return -EPERM; | |
1785 | ||
1786 | if (!dir->i_op || !dir->i_op->mknod) | |
1787 | return -EPERM; | |
1788 | ||
1789 | error = security_inode_mknod(dir, dentry, mode, dev); | |
1790 | if (error) | |
1791 | return error; | |
1792 | ||
1793 | DQUOT_INIT(dir); | |
1794 | error = dir->i_op->mknod(dir, dentry, mode, dev); | |
a74574aa | 1795 | if (!error) |
0eeca283 | 1796 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
1797 | return error; |
1798 | } | |
1799 | ||
5590ff0d UD |
1800 | asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, |
1801 | unsigned dev) | |
1da177e4 LT |
1802 | { |
1803 | int error = 0; | |
1804 | char * tmp; | |
1805 | struct dentry * dentry; | |
1806 | struct nameidata nd; | |
1807 | ||
1808 | if (S_ISDIR(mode)) | |
1809 | return -EPERM; | |
1810 | tmp = getname(filename); | |
1811 | if (IS_ERR(tmp)) | |
1812 | return PTR_ERR(tmp); | |
1813 | ||
5590ff0d | 1814 | error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); |
1da177e4 LT |
1815 | if (error) |
1816 | goto out; | |
1817 | dentry = lookup_create(&nd, 0); | |
1818 | error = PTR_ERR(dentry); | |
1819 | ||
1820 | if (!IS_POSIXACL(nd.dentry->d_inode)) | |
1821 | mode &= ~current->fs->umask; | |
1822 | if (!IS_ERR(dentry)) { | |
1823 | switch (mode & S_IFMT) { | |
1824 | case 0: case S_IFREG: | |
1825 | error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd); | |
1826 | break; | |
1827 | case S_IFCHR: case S_IFBLK: | |
1828 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode, | |
1829 | new_decode_dev(dev)); | |
1830 | break; | |
1831 | case S_IFIFO: case S_IFSOCK: | |
1832 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0); | |
1833 | break; | |
1834 | case S_IFDIR: | |
1835 | error = -EPERM; | |
1836 | break; | |
1837 | default: | |
1838 | error = -EINVAL; | |
1839 | } | |
1840 | dput(dentry); | |
1841 | } | |
1b1dcc1b | 1842 | mutex_unlock(&nd.dentry->d_inode->i_mutex); |
1da177e4 LT |
1843 | path_release(&nd); |
1844 | out: | |
1845 | putname(tmp); | |
1846 | ||
1847 | return error; | |
1848 | } | |
1849 | ||
5590ff0d UD |
1850 | asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) |
1851 | { | |
1852 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
1853 | } | |
1854 | ||
1da177e4 LT |
1855 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
1856 | { | |
1857 | int error = may_create(dir, dentry, NULL); | |
1858 | ||
1859 | if (error) | |
1860 | return error; | |
1861 | ||
1862 | if (!dir->i_op || !dir->i_op->mkdir) | |
1863 | return -EPERM; | |
1864 | ||
1865 | mode &= (S_IRWXUGO|S_ISVTX); | |
1866 | error = security_inode_mkdir(dir, dentry, mode); | |
1867 | if (error) | |
1868 | return error; | |
1869 | ||
1870 | DQUOT_INIT(dir); | |
1871 | error = dir->i_op->mkdir(dir, dentry, mode); | |
a74574aa | 1872 | if (!error) |
0eeca283 | 1873 | fsnotify_mkdir(dir, dentry->d_name.name); |
1da177e4 LT |
1874 | return error; |
1875 | } | |
1876 | ||
5590ff0d | 1877 | asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) |
1da177e4 LT |
1878 | { |
1879 | int error = 0; | |
1880 | char * tmp; | |
1881 | ||
1882 | tmp = getname(pathname); | |
1883 | error = PTR_ERR(tmp); | |
1884 | if (!IS_ERR(tmp)) { | |
1885 | struct dentry *dentry; | |
1886 | struct nameidata nd; | |
1887 | ||
5590ff0d | 1888 | error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); |
1da177e4 LT |
1889 | if (error) |
1890 | goto out; | |
1891 | dentry = lookup_create(&nd, 1); | |
1892 | error = PTR_ERR(dentry); | |
1893 | if (!IS_ERR(dentry)) { | |
1894 | if (!IS_POSIXACL(nd.dentry->d_inode)) | |
1895 | mode &= ~current->fs->umask; | |
1896 | error = vfs_mkdir(nd.dentry->d_inode, dentry, mode); | |
1897 | dput(dentry); | |
1898 | } | |
1b1dcc1b | 1899 | mutex_unlock(&nd.dentry->d_inode->i_mutex); |
1da177e4 LT |
1900 | path_release(&nd); |
1901 | out: | |
1902 | putname(tmp); | |
1903 | } | |
1904 | ||
1905 | return error; | |
1906 | } | |
1907 | ||
5590ff0d UD |
1908 | asmlinkage long sys_mkdir(const char __user *pathname, int mode) |
1909 | { | |
1910 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
1911 | } | |
1912 | ||
1da177e4 LT |
1913 | /* |
1914 | * We try to drop the dentry early: we should have | |
1915 | * a usage count of 2 if we're the only user of this | |
1916 | * dentry, and if that is true (possibly after pruning | |
1917 | * the dcache), then we drop the dentry now. | |
1918 | * | |
1919 | * A low-level filesystem can, if it choses, legally | |
1920 | * do a | |
1921 | * | |
1922 | * if (!d_unhashed(dentry)) | |
1923 | * return -EBUSY; | |
1924 | * | |
1925 | * if it cannot handle the case of removing a directory | |
1926 | * that is still in use by something else.. | |
1927 | */ | |
1928 | void dentry_unhash(struct dentry *dentry) | |
1929 | { | |
1930 | dget(dentry); | |
1931 | if (atomic_read(&dentry->d_count)) | |
1932 | shrink_dcache_parent(dentry); | |
1933 | spin_lock(&dcache_lock); | |
1934 | spin_lock(&dentry->d_lock); | |
1935 | if (atomic_read(&dentry->d_count) == 2) | |
1936 | __d_drop(dentry); | |
1937 | spin_unlock(&dentry->d_lock); | |
1938 | spin_unlock(&dcache_lock); | |
1939 | } | |
1940 | ||
1941 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
1942 | { | |
1943 | int error = may_delete(dir, dentry, 1); | |
1944 | ||
1945 | if (error) | |
1946 | return error; | |
1947 | ||
1948 | if (!dir->i_op || !dir->i_op->rmdir) | |
1949 | return -EPERM; | |
1950 | ||
1951 | DQUOT_INIT(dir); | |
1952 | ||
1b1dcc1b | 1953 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
1954 | dentry_unhash(dentry); |
1955 | if (d_mountpoint(dentry)) | |
1956 | error = -EBUSY; | |
1957 | else { | |
1958 | error = security_inode_rmdir(dir, dentry); | |
1959 | if (!error) { | |
1960 | error = dir->i_op->rmdir(dir, dentry); | |
1961 | if (!error) | |
1962 | dentry->d_inode->i_flags |= S_DEAD; | |
1963 | } | |
1964 | } | |
1b1dcc1b | 1965 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 | 1966 | if (!error) { |
1da177e4 LT |
1967 | d_delete(dentry); |
1968 | } | |
1969 | dput(dentry); | |
1970 | ||
1971 | return error; | |
1972 | } | |
1973 | ||
5590ff0d | 1974 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
1975 | { |
1976 | int error = 0; | |
1977 | char * name; | |
1978 | struct dentry *dentry; | |
1979 | struct nameidata nd; | |
1980 | ||
1981 | name = getname(pathname); | |
1982 | if(IS_ERR(name)) | |
1983 | return PTR_ERR(name); | |
1984 | ||
5590ff0d | 1985 | error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); |
1da177e4 LT |
1986 | if (error) |
1987 | goto exit; | |
1988 | ||
1989 | switch(nd.last_type) { | |
1990 | case LAST_DOTDOT: | |
1991 | error = -ENOTEMPTY; | |
1992 | goto exit1; | |
1993 | case LAST_DOT: | |
1994 | error = -EINVAL; | |
1995 | goto exit1; | |
1996 | case LAST_ROOT: | |
1997 | error = -EBUSY; | |
1998 | goto exit1; | |
1999 | } | |
1b1dcc1b | 2000 | mutex_lock(&nd.dentry->d_inode->i_mutex); |
49705b77 | 2001 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2002 | error = PTR_ERR(dentry); |
2003 | if (!IS_ERR(dentry)) { | |
2004 | error = vfs_rmdir(nd.dentry->d_inode, dentry); | |
2005 | dput(dentry); | |
2006 | } | |
1b1dcc1b | 2007 | mutex_unlock(&nd.dentry->d_inode->i_mutex); |
1da177e4 LT |
2008 | exit1: |
2009 | path_release(&nd); | |
2010 | exit: | |
2011 | putname(name); | |
2012 | return error; | |
2013 | } | |
2014 | ||
5590ff0d UD |
2015 | asmlinkage long sys_rmdir(const char __user *pathname) |
2016 | { | |
2017 | return do_rmdir(AT_FDCWD, pathname); | |
2018 | } | |
2019 | ||
1da177e4 LT |
2020 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2021 | { | |
2022 | int error = may_delete(dir, dentry, 0); | |
2023 | ||
2024 | if (error) | |
2025 | return error; | |
2026 | ||
2027 | if (!dir->i_op || !dir->i_op->unlink) | |
2028 | return -EPERM; | |
2029 | ||
2030 | DQUOT_INIT(dir); | |
2031 | ||
1b1dcc1b | 2032 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2033 | if (d_mountpoint(dentry)) |
2034 | error = -EBUSY; | |
2035 | else { | |
2036 | error = security_inode_unlink(dir, dentry); | |
2037 | if (!error) | |
2038 | error = dir->i_op->unlink(dir, dentry); | |
2039 | } | |
1b1dcc1b | 2040 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2041 | |
2042 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2043 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
e234f35c | 2044 | d_delete(dentry); |
1da177e4 | 2045 | } |
0eeca283 | 2046 | |
1da177e4 LT |
2047 | return error; |
2048 | } | |
2049 | ||
2050 | /* | |
2051 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2052 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2053 | * writeout happening, and we don't want to prevent access to the directory |
2054 | * while waiting on the I/O. | |
2055 | */ | |
5590ff0d | 2056 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 LT |
2057 | { |
2058 | int error = 0; | |
2059 | char * name; | |
2060 | struct dentry *dentry; | |
2061 | struct nameidata nd; | |
2062 | struct inode *inode = NULL; | |
2063 | ||
2064 | name = getname(pathname); | |
2065 | if(IS_ERR(name)) | |
2066 | return PTR_ERR(name); | |
2067 | ||
5590ff0d | 2068 | error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); |
1da177e4 LT |
2069 | if (error) |
2070 | goto exit; | |
2071 | error = -EISDIR; | |
2072 | if (nd.last_type != LAST_NORM) | |
2073 | goto exit1; | |
1b1dcc1b | 2074 | mutex_lock(&nd.dentry->d_inode->i_mutex); |
49705b77 | 2075 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2076 | error = PTR_ERR(dentry); |
2077 | if (!IS_ERR(dentry)) { | |
2078 | /* Why not before? Because we want correct error value */ | |
2079 | if (nd.last.name[nd.last.len]) | |
2080 | goto slashes; | |
2081 | inode = dentry->d_inode; | |
2082 | if (inode) | |
2083 | atomic_inc(&inode->i_count); | |
2084 | error = vfs_unlink(nd.dentry->d_inode, dentry); | |
2085 | exit2: | |
2086 | dput(dentry); | |
2087 | } | |
1b1dcc1b | 2088 | mutex_unlock(&nd.dentry->d_inode->i_mutex); |
1da177e4 LT |
2089 | if (inode) |
2090 | iput(inode); /* truncate the inode here */ | |
2091 | exit1: | |
2092 | path_release(&nd); | |
2093 | exit: | |
2094 | putname(name); | |
2095 | return error; | |
2096 | ||
2097 | slashes: | |
2098 | error = !dentry->d_inode ? -ENOENT : | |
2099 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2100 | goto exit2; | |
2101 | } | |
2102 | ||
5590ff0d UD |
2103 | asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) |
2104 | { | |
2105 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2106 | return -EINVAL; | |
2107 | ||
2108 | if (flag & AT_REMOVEDIR) | |
2109 | return do_rmdir(dfd, pathname); | |
2110 | ||
2111 | return do_unlinkat(dfd, pathname); | |
2112 | } | |
2113 | ||
2114 | asmlinkage long sys_unlink(const char __user *pathname) | |
2115 | { | |
2116 | return do_unlinkat(AT_FDCWD, pathname); | |
2117 | } | |
2118 | ||
1da177e4 LT |
2119 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) |
2120 | { | |
2121 | int error = may_create(dir, dentry, NULL); | |
2122 | ||
2123 | if (error) | |
2124 | return error; | |
2125 | ||
2126 | if (!dir->i_op || !dir->i_op->symlink) | |
2127 | return -EPERM; | |
2128 | ||
2129 | error = security_inode_symlink(dir, dentry, oldname); | |
2130 | if (error) | |
2131 | return error; | |
2132 | ||
2133 | DQUOT_INIT(dir); | |
2134 | error = dir->i_op->symlink(dir, dentry, oldname); | |
a74574aa | 2135 | if (!error) |
0eeca283 | 2136 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
2137 | return error; |
2138 | } | |
2139 | ||
5590ff0d UD |
2140 | asmlinkage long sys_symlinkat(const char __user *oldname, |
2141 | int newdfd, const char __user *newname) | |
1da177e4 LT |
2142 | { |
2143 | int error = 0; | |
2144 | char * from; | |
2145 | char * to; | |
2146 | ||
2147 | from = getname(oldname); | |
2148 | if(IS_ERR(from)) | |
2149 | return PTR_ERR(from); | |
2150 | to = getname(newname); | |
2151 | error = PTR_ERR(to); | |
2152 | if (!IS_ERR(to)) { | |
2153 | struct dentry *dentry; | |
2154 | struct nameidata nd; | |
2155 | ||
5590ff0d | 2156 | error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); |
1da177e4 LT |
2157 | if (error) |
2158 | goto out; | |
2159 | dentry = lookup_create(&nd, 0); | |
2160 | error = PTR_ERR(dentry); | |
2161 | if (!IS_ERR(dentry)) { | |
2162 | error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO); | |
2163 | dput(dentry); | |
2164 | } | |
1b1dcc1b | 2165 | mutex_unlock(&nd.dentry->d_inode->i_mutex); |
1da177e4 LT |
2166 | path_release(&nd); |
2167 | out: | |
2168 | putname(to); | |
2169 | } | |
2170 | putname(from); | |
2171 | return error; | |
2172 | } | |
2173 | ||
5590ff0d UD |
2174 | asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) |
2175 | { | |
2176 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2177 | } | |
2178 | ||
1da177e4 LT |
2179 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2180 | { | |
2181 | struct inode *inode = old_dentry->d_inode; | |
2182 | int error; | |
2183 | ||
2184 | if (!inode) | |
2185 | return -ENOENT; | |
2186 | ||
2187 | error = may_create(dir, new_dentry, NULL); | |
2188 | if (error) | |
2189 | return error; | |
2190 | ||
2191 | if (dir->i_sb != inode->i_sb) | |
2192 | return -EXDEV; | |
2193 | ||
2194 | /* | |
2195 | * A link to an append-only or immutable file cannot be created. | |
2196 | */ | |
2197 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2198 | return -EPERM; | |
2199 | if (!dir->i_op || !dir->i_op->link) | |
2200 | return -EPERM; | |
2201 | if (S_ISDIR(old_dentry->d_inode->i_mode)) | |
2202 | return -EPERM; | |
2203 | ||
2204 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2205 | if (error) | |
2206 | return error; | |
2207 | ||
1b1dcc1b | 2208 | mutex_lock(&old_dentry->d_inode->i_mutex); |
1da177e4 LT |
2209 | DQUOT_INIT(dir); |
2210 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
1b1dcc1b | 2211 | mutex_unlock(&old_dentry->d_inode->i_mutex); |
e31e14ec | 2212 | if (!error) |
0eeca283 | 2213 | fsnotify_create(dir, new_dentry->d_name.name); |
1da177e4 LT |
2214 | return error; |
2215 | } | |
2216 | ||
2217 | /* | |
2218 | * Hardlinks are often used in delicate situations. We avoid | |
2219 | * security-related surprises by not following symlinks on the | |
2220 | * newname. --KAB | |
2221 | * | |
2222 | * We don't follow them on the oldname either to be compatible | |
2223 | * with linux 2.0, and to avoid hard-linking to directories | |
2224 | * and other special files. --ADM | |
2225 | */ | |
5590ff0d | 2226 | asmlinkage long sys_linkat(int olddfd, const char __user *oldname, |
c04030e1 UD |
2227 | int newdfd, const char __user *newname, |
2228 | int flags) | |
1da177e4 LT |
2229 | { |
2230 | struct dentry *new_dentry; | |
2231 | struct nameidata nd, old_nd; | |
2232 | int error; | |
2233 | char * to; | |
2234 | ||
c04030e1 UD |
2235 | if (flags != 0) |
2236 | return -EINVAL; | |
2237 | ||
1da177e4 LT |
2238 | to = getname(newname); |
2239 | if (IS_ERR(to)) | |
2240 | return PTR_ERR(to); | |
2241 | ||
5590ff0d | 2242 | error = __user_walk_fd(olddfd, oldname, 0, &old_nd); |
1da177e4 LT |
2243 | if (error) |
2244 | goto exit; | |
5590ff0d | 2245 | error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); |
1da177e4 LT |
2246 | if (error) |
2247 | goto out; | |
2248 | error = -EXDEV; | |
2249 | if (old_nd.mnt != nd.mnt) | |
2250 | goto out_release; | |
2251 | new_dentry = lookup_create(&nd, 0); | |
2252 | error = PTR_ERR(new_dentry); | |
2253 | if (!IS_ERR(new_dentry)) { | |
2254 | error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry); | |
2255 | dput(new_dentry); | |
2256 | } | |
1b1dcc1b | 2257 | mutex_unlock(&nd.dentry->d_inode->i_mutex); |
1da177e4 LT |
2258 | out_release: |
2259 | path_release(&nd); | |
2260 | out: | |
2261 | path_release(&old_nd); | |
2262 | exit: | |
2263 | putname(to); | |
2264 | ||
2265 | return error; | |
2266 | } | |
2267 | ||
5590ff0d UD |
2268 | asmlinkage long sys_link(const char __user *oldname, const char __user *newname) |
2269 | { | |
c04030e1 | 2270 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2271 | } |
2272 | ||
1da177e4 LT |
2273 | /* |
2274 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2275 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2276 | * Problems: | |
2277 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2278 | * b) race potential - two innocent renames can create a loop together. | |
2279 | * That's where 4.4 screws up. Current fix: serialization on | |
2280 | * sb->s_vfs_rename_sem. We might be more accurate, but that's another | |
2281 | * story. | |
2282 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2283 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2284 | * whether the target exists). Solution: try to be smart with locking |
2285 | * order for inodes. We rely on the fact that tree topology may change | |
2286 | * only under ->s_vfs_rename_sem _and_ that parent of the object we | |
2287 | * move will be locked. Thus we can rank directories by the tree | |
2288 | * (ancestors first) and rank all non-directories after them. | |
2289 | * That works since everybody except rename does "lock parent, lookup, | |
2290 | * lock child" and rename is under ->s_vfs_rename_sem. | |
2291 | * HOWEVER, it relies on the assumption that any object with ->lookup() | |
2292 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2293 | * we'd better make sure that there's no link(2) for them. | |
2294 | * d) some filesystems don't support opened-but-unlinked directories, | |
2295 | * either because of layout or because they are not ready to deal with | |
2296 | * all cases correctly. The latter will be fixed (taking this sort of | |
2297 | * stuff into VFS), but the former is not going away. Solution: the same | |
2298 | * trick as in rmdir(). | |
2299 | * e) conversion from fhandle to dentry may come in the wrong moment - when | |
1b1dcc1b | 2300 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2301 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
1b1dcc1b | 2302 | * ->i_mutex on parents, which works but leads to some truely excessive |
1da177e4 LT |
2303 | * locking]. |
2304 | */ | |
75c96f85 AB |
2305 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2306 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2307 | { |
2308 | int error = 0; | |
2309 | struct inode *target; | |
2310 | ||
2311 | /* | |
2312 | * If we are going to change the parent - check write permissions, | |
2313 | * we'll need to flip '..'. | |
2314 | */ | |
2315 | if (new_dir != old_dir) { | |
2316 | error = permission(old_dentry->d_inode, MAY_WRITE, NULL); | |
2317 | if (error) | |
2318 | return error; | |
2319 | } | |
2320 | ||
2321 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2322 | if (error) | |
2323 | return error; | |
2324 | ||
2325 | target = new_dentry->d_inode; | |
2326 | if (target) { | |
1b1dcc1b | 2327 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2328 | dentry_unhash(new_dentry); |
2329 | } | |
2330 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2331 | error = -EBUSY; | |
2332 | else | |
2333 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2334 | if (target) { | |
2335 | if (!error) | |
2336 | target->i_flags |= S_DEAD; | |
1b1dcc1b | 2337 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2338 | if (d_unhashed(new_dentry)) |
2339 | d_rehash(new_dentry); | |
2340 | dput(new_dentry); | |
2341 | } | |
e31e14ec | 2342 | if (!error) |
1da177e4 | 2343 | d_move(old_dentry,new_dentry); |
1da177e4 LT |
2344 | return error; |
2345 | } | |
2346 | ||
75c96f85 AB |
2347 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2348 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2349 | { |
2350 | struct inode *target; | |
2351 | int error; | |
2352 | ||
2353 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2354 | if (error) | |
2355 | return error; | |
2356 | ||
2357 | dget(new_dentry); | |
2358 | target = new_dentry->d_inode; | |
2359 | if (target) | |
1b1dcc1b | 2360 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2361 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2362 | error = -EBUSY; | |
2363 | else | |
2364 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2365 | if (!error) { | |
2366 | /* The following d_move() should become unconditional */ | |
2367 | if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME)) | |
2368 | d_move(old_dentry, new_dentry); | |
1da177e4 LT |
2369 | } |
2370 | if (target) | |
1b1dcc1b | 2371 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2372 | dput(new_dentry); |
2373 | return error; | |
2374 | } | |
2375 | ||
2376 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2377 | struct inode *new_dir, struct dentry *new_dentry) | |
2378 | { | |
2379 | int error; | |
2380 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
0eeca283 | 2381 | const char *old_name; |
1da177e4 LT |
2382 | |
2383 | if (old_dentry->d_inode == new_dentry->d_inode) | |
2384 | return 0; | |
2385 | ||
2386 | error = may_delete(old_dir, old_dentry, is_dir); | |
2387 | if (error) | |
2388 | return error; | |
2389 | ||
2390 | if (!new_dentry->d_inode) | |
2391 | error = may_create(new_dir, new_dentry, NULL); | |
2392 | else | |
2393 | error = may_delete(new_dir, new_dentry, is_dir); | |
2394 | if (error) | |
2395 | return error; | |
2396 | ||
2397 | if (!old_dir->i_op || !old_dir->i_op->rename) | |
2398 | return -EPERM; | |
2399 | ||
2400 | DQUOT_INIT(old_dir); | |
2401 | DQUOT_INIT(new_dir); | |
2402 | ||
0eeca283 RL |
2403 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
2404 | ||
1da177e4 LT |
2405 | if (is_dir) |
2406 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
2407 | else | |
2408 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
2409 | if (!error) { | |
0eeca283 | 2410 | const char *new_name = old_dentry->d_name.name; |
89204c40 JM |
2411 | fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, |
2412 | new_dentry->d_inode, old_dentry->d_inode); | |
1da177e4 | 2413 | } |
0eeca283 RL |
2414 | fsnotify_oldname_free(old_name); |
2415 | ||
1da177e4 LT |
2416 | return error; |
2417 | } | |
2418 | ||
5590ff0d UD |
2419 | static int do_rename(int olddfd, const char *oldname, |
2420 | int newdfd, const char *newname) | |
1da177e4 LT |
2421 | { |
2422 | int error = 0; | |
2423 | struct dentry * old_dir, * new_dir; | |
2424 | struct dentry * old_dentry, *new_dentry; | |
2425 | struct dentry * trap; | |
2426 | struct nameidata oldnd, newnd; | |
2427 | ||
5590ff0d | 2428 | error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd); |
1da177e4 LT |
2429 | if (error) |
2430 | goto exit; | |
2431 | ||
5590ff0d | 2432 | error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd); |
1da177e4 LT |
2433 | if (error) |
2434 | goto exit1; | |
2435 | ||
2436 | error = -EXDEV; | |
2437 | if (oldnd.mnt != newnd.mnt) | |
2438 | goto exit2; | |
2439 | ||
2440 | old_dir = oldnd.dentry; | |
2441 | error = -EBUSY; | |
2442 | if (oldnd.last_type != LAST_NORM) | |
2443 | goto exit2; | |
2444 | ||
2445 | new_dir = newnd.dentry; | |
2446 | if (newnd.last_type != LAST_NORM) | |
2447 | goto exit2; | |
2448 | ||
2449 | trap = lock_rename(new_dir, old_dir); | |
2450 | ||
49705b77 | 2451 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
2452 | error = PTR_ERR(old_dentry); |
2453 | if (IS_ERR(old_dentry)) | |
2454 | goto exit3; | |
2455 | /* source must exist */ | |
2456 | error = -ENOENT; | |
2457 | if (!old_dentry->d_inode) | |
2458 | goto exit4; | |
2459 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
2460 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
2461 | error = -ENOTDIR; | |
2462 | if (oldnd.last.name[oldnd.last.len]) | |
2463 | goto exit4; | |
2464 | if (newnd.last.name[newnd.last.len]) | |
2465 | goto exit4; | |
2466 | } | |
2467 | /* source should not be ancestor of target */ | |
2468 | error = -EINVAL; | |
2469 | if (old_dentry == trap) | |
2470 | goto exit4; | |
49705b77 | 2471 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
2472 | error = PTR_ERR(new_dentry); |
2473 | if (IS_ERR(new_dentry)) | |
2474 | goto exit4; | |
2475 | /* target should not be an ancestor of source */ | |
2476 | error = -ENOTEMPTY; | |
2477 | if (new_dentry == trap) | |
2478 | goto exit5; | |
2479 | ||
2480 | error = vfs_rename(old_dir->d_inode, old_dentry, | |
2481 | new_dir->d_inode, new_dentry); | |
2482 | exit5: | |
2483 | dput(new_dentry); | |
2484 | exit4: | |
2485 | dput(old_dentry); | |
2486 | exit3: | |
2487 | unlock_rename(new_dir, old_dir); | |
2488 | exit2: | |
2489 | path_release(&newnd); | |
2490 | exit1: | |
2491 | path_release(&oldnd); | |
2492 | exit: | |
2493 | return error; | |
2494 | } | |
2495 | ||
5590ff0d UD |
2496 | asmlinkage long sys_renameat(int olddfd, const char __user *oldname, |
2497 | int newdfd, const char __user *newname) | |
1da177e4 LT |
2498 | { |
2499 | int error; | |
2500 | char * from; | |
2501 | char * to; | |
2502 | ||
2503 | from = getname(oldname); | |
2504 | if(IS_ERR(from)) | |
2505 | return PTR_ERR(from); | |
2506 | to = getname(newname); | |
2507 | error = PTR_ERR(to); | |
2508 | if (!IS_ERR(to)) { | |
5590ff0d | 2509 | error = do_rename(olddfd, from, newdfd, to); |
1da177e4 LT |
2510 | putname(to); |
2511 | } | |
2512 | putname(from); | |
2513 | return error; | |
2514 | } | |
2515 | ||
5590ff0d UD |
2516 | asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) |
2517 | { | |
2518 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
2519 | } | |
2520 | ||
1da177e4 LT |
2521 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
2522 | { | |
2523 | int len; | |
2524 | ||
2525 | len = PTR_ERR(link); | |
2526 | if (IS_ERR(link)) | |
2527 | goto out; | |
2528 | ||
2529 | len = strlen(link); | |
2530 | if (len > (unsigned) buflen) | |
2531 | len = buflen; | |
2532 | if (copy_to_user(buffer, link, len)) | |
2533 | len = -EFAULT; | |
2534 | out: | |
2535 | return len; | |
2536 | } | |
2537 | ||
2538 | /* | |
2539 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
2540 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
2541 | * using) it for any given inode is up to filesystem. | |
2542 | */ | |
2543 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2544 | { | |
2545 | struct nameidata nd; | |
cc314eef LT |
2546 | void *cookie; |
2547 | ||
1da177e4 | 2548 | nd.depth = 0; |
cc314eef LT |
2549 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
2550 | if (!IS_ERR(cookie)) { | |
2551 | int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
1da177e4 | 2552 | if (dentry->d_inode->i_op->put_link) |
cc314eef LT |
2553 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); |
2554 | cookie = ERR_PTR(res); | |
1da177e4 | 2555 | } |
cc314eef | 2556 | return PTR_ERR(cookie); |
1da177e4 LT |
2557 | } |
2558 | ||
2559 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
2560 | { | |
2561 | return __vfs_follow_link(nd, link); | |
2562 | } | |
2563 | ||
2564 | /* get the link contents into pagecache */ | |
2565 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
2566 | { | |
2567 | struct page * page; | |
2568 | struct address_space *mapping = dentry->d_inode->i_mapping; | |
2569 | page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage, | |
2570 | NULL); | |
2571 | if (IS_ERR(page)) | |
2572 | goto sync_fail; | |
2573 | wait_on_page_locked(page); | |
2574 | if (!PageUptodate(page)) | |
2575 | goto async_fail; | |
2576 | *ppage = page; | |
2577 | return kmap(page); | |
2578 | ||
2579 | async_fail: | |
2580 | page_cache_release(page); | |
2581 | return ERR_PTR(-EIO); | |
2582 | ||
2583 | sync_fail: | |
2584 | return (char*)page; | |
2585 | } | |
2586 | ||
2587 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2588 | { | |
2589 | struct page *page = NULL; | |
2590 | char *s = page_getlink(dentry, &page); | |
2591 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
2592 | if (page) { | |
2593 | kunmap(page); | |
2594 | page_cache_release(page); | |
2595 | } | |
2596 | return res; | |
2597 | } | |
2598 | ||
cc314eef | 2599 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 2600 | { |
cc314eef | 2601 | struct page *page = NULL; |
1da177e4 | 2602 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 2603 | return page; |
1da177e4 LT |
2604 | } |
2605 | ||
cc314eef | 2606 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 2607 | { |
cc314eef LT |
2608 | struct page *page = cookie; |
2609 | ||
2610 | if (page) { | |
1da177e4 LT |
2611 | kunmap(page); |
2612 | page_cache_release(page); | |
1da177e4 LT |
2613 | } |
2614 | } | |
2615 | ||
0adb25d2 KK |
2616 | int __page_symlink(struct inode *inode, const char *symname, int len, |
2617 | gfp_t gfp_mask) | |
1da177e4 LT |
2618 | { |
2619 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 2620 | struct page *page; |
1da177e4 LT |
2621 | int err = -ENOMEM; |
2622 | char *kaddr; | |
2623 | ||
0adb25d2 | 2624 | page = find_or_create_page(mapping, 0, gfp_mask); |
1da177e4 LT |
2625 | if (!page) |
2626 | goto fail; | |
2627 | err = mapping->a_ops->prepare_write(NULL, page, 0, len-1); | |
2628 | if (err) | |
2629 | goto fail_map; | |
2630 | kaddr = kmap_atomic(page, KM_USER0); | |
2631 | memcpy(kaddr, symname, len-1); | |
2632 | kunmap_atomic(kaddr, KM_USER0); | |
2633 | mapping->a_ops->commit_write(NULL, page, 0, len-1); | |
2634 | /* | |
2635 | * Notice that we are _not_ going to block here - end of page is | |
2636 | * unmapped, so this will only try to map the rest of page, see | |
2637 | * that it is unmapped (typically even will not look into inode - | |
2638 | * ->i_size will be enough for everything) and zero it out. | |
2639 | * OTOH it's obviously correct and should make the page up-to-date. | |
2640 | */ | |
2641 | if (!PageUptodate(page)) { | |
2642 | err = mapping->a_ops->readpage(NULL, page); | |
2643 | wait_on_page_locked(page); | |
2644 | } else { | |
2645 | unlock_page(page); | |
2646 | } | |
2647 | page_cache_release(page); | |
2648 | if (err < 0) | |
2649 | goto fail; | |
2650 | mark_inode_dirty(inode); | |
2651 | return 0; | |
2652 | fail_map: | |
2653 | unlock_page(page); | |
2654 | page_cache_release(page); | |
2655 | fail: | |
2656 | return err; | |
2657 | } | |
2658 | ||
0adb25d2 KK |
2659 | int page_symlink(struct inode *inode, const char *symname, int len) |
2660 | { | |
2661 | return __page_symlink(inode, symname, len, | |
2662 | mapping_gfp_mask(inode->i_mapping)); | |
2663 | } | |
2664 | ||
1da177e4 LT |
2665 | struct inode_operations page_symlink_inode_operations = { |
2666 | .readlink = generic_readlink, | |
2667 | .follow_link = page_follow_link_light, | |
2668 | .put_link = page_put_link, | |
2669 | }; | |
2670 | ||
2671 | EXPORT_SYMBOL(__user_walk); | |
5590ff0d | 2672 | EXPORT_SYMBOL(__user_walk_fd); |
1da177e4 LT |
2673 | EXPORT_SYMBOL(follow_down); |
2674 | EXPORT_SYMBOL(follow_up); | |
2675 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
2676 | EXPORT_SYMBOL(getname); | |
2677 | EXPORT_SYMBOL(lock_rename); | |
2678 | EXPORT_SYMBOL(lookup_hash); | |
2679 | EXPORT_SYMBOL(lookup_one_len); | |
2680 | EXPORT_SYMBOL(page_follow_link_light); | |
2681 | EXPORT_SYMBOL(page_put_link); | |
2682 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 2683 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
2684 | EXPORT_SYMBOL(page_symlink); |
2685 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
2686 | EXPORT_SYMBOL(path_lookup); | |
2687 | EXPORT_SYMBOL(path_release); | |
2688 | EXPORT_SYMBOL(path_walk); | |
2689 | EXPORT_SYMBOL(permission); | |
e4543edd | 2690 | EXPORT_SYMBOL(vfs_permission); |
8c744fb8 | 2691 | EXPORT_SYMBOL(file_permission); |
1da177e4 LT |
2692 | EXPORT_SYMBOL(unlock_rename); |
2693 | EXPORT_SYMBOL(vfs_create); | |
2694 | EXPORT_SYMBOL(vfs_follow_link); | |
2695 | EXPORT_SYMBOL(vfs_link); | |
2696 | EXPORT_SYMBOL(vfs_mkdir); | |
2697 | EXPORT_SYMBOL(vfs_mknod); | |
2698 | EXPORT_SYMBOL(generic_permission); | |
2699 | EXPORT_SYMBOL(vfs_readlink); | |
2700 | EXPORT_SYMBOL(vfs_rename); | |
2701 | EXPORT_SYMBOL(vfs_rmdir); | |
2702 | EXPORT_SYMBOL(vfs_symlink); | |
2703 | EXPORT_SYMBOL(vfs_unlink); | |
2704 | EXPORT_SYMBOL(dentry_unhash); | |
2705 | EXPORT_SYMBOL(generic_readlink); |