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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> | |
31 | #include <asm/namei.h> | |
32 | #include <asm/uaccess.h> | |
33 | ||
34 | #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) | |
35 | ||
36 | /* [Feb-1997 T. Schoebel-Theuer] | |
37 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
38 | * were necessary because of omirr. The reason is that omirr needs | |
39 | * to know the _real_ pathname, not the user-supplied one, in case | |
40 | * of symlinks (and also when transname replacements occur). | |
41 | * | |
42 | * The new code replaces the old recursive symlink resolution with | |
43 | * an iterative one (in case of non-nested symlink chains). It does | |
44 | * this with calls to <fs>_follow_link(). | |
45 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
46 | * replaced with a single function lookup_dentry() that can handle all | |
47 | * the special cases of the former code. | |
48 | * | |
49 | * With the new dcache, the pathname is stored at each inode, at least as | |
50 | * long as the refcount of the inode is positive. As a side effect, the | |
51 | * size of the dcache depends on the inode cache and thus is dynamic. | |
52 | * | |
53 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
54 | * resolution to correspond with current state of the code. | |
55 | * | |
56 | * Note that the symlink resolution is not *completely* iterative. | |
57 | * There is still a significant amount of tail- and mid- recursion in | |
58 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
59 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
60 | * may return different results than <fs>_follow_link(). Many virtual | |
61 | * filesystems (including /proc) exhibit this behavior. | |
62 | */ | |
63 | ||
64 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
65 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
66 | * and the name already exists in form of a symlink, try to create the new | |
67 | * name indicated by the symlink. The old code always complained that the | |
68 | * name already exists, due to not following the symlink even if its target | |
69 | * is nonexistent. The new semantics affects also mknod() and link() when | |
70 | * the name is a symlink pointing to a non-existant name. | |
71 | * | |
72 | * I don't know which semantics is the right one, since I have no access | |
73 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
74 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
75 | * "old" one. Personally, I think the new semantics is much more logical. | |
76 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
77 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
78 | * and in the old Linux semantics. | |
79 | */ | |
80 | ||
81 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
82 | * semantics. See the comments in "open_namei" and "do_link" below. | |
83 | * | |
84 | * [10-Sep-98 Alan Modra] Another symlink change. | |
85 | */ | |
86 | ||
87 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
88 | * inside the path - always follow. | |
89 | * in the last component in creation/removal/renaming - never follow. | |
90 | * if LOOKUP_FOLLOW passed - follow. | |
91 | * if the pathname has trailing slashes - follow. | |
92 | * otherwise - don't follow. | |
93 | * (applied in that order). | |
94 | * | |
95 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
96 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
97 | * During the 2.4 we need to fix the userland stuff depending on it - | |
98 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
99 | * XEmacs seems to be relying on it... | |
100 | */ | |
101 | /* | |
102 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
103 | * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives | |
104 | * any extra contention... | |
105 | */ | |
106 | ||
107 | /* In order to reduce some races, while at the same time doing additional | |
108 | * checking and hopefully speeding things up, we copy filenames to the | |
109 | * kernel data space before using them.. | |
110 | * | |
111 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
112 | * PATH_MAX includes the nul terminator --RR. | |
113 | */ | |
114 | static inline int do_getname(const char __user *filename, char *page) | |
115 | { | |
116 | int retval; | |
117 | unsigned long len = PATH_MAX; | |
118 | ||
119 | if (!segment_eq(get_fs(), KERNEL_DS)) { | |
120 | if ((unsigned long) filename >= TASK_SIZE) | |
121 | return -EFAULT; | |
122 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) | |
123 | len = TASK_SIZE - (unsigned long) filename; | |
124 | } | |
125 | ||
126 | retval = strncpy_from_user(page, filename, len); | |
127 | if (retval > 0) { | |
128 | if (retval < len) | |
129 | return 0; | |
130 | return -ENAMETOOLONG; | |
131 | } else if (!retval) | |
132 | retval = -ENOENT; | |
133 | return retval; | |
134 | } | |
135 | ||
136 | char * getname(const char __user * filename) | |
137 | { | |
138 | char *tmp, *result; | |
139 | ||
140 | result = ERR_PTR(-ENOMEM); | |
141 | tmp = __getname(); | |
142 | if (tmp) { | |
143 | int retval = do_getname(filename, tmp); | |
144 | ||
145 | result = tmp; | |
146 | if (retval < 0) { | |
147 | __putname(tmp); | |
148 | result = ERR_PTR(retval); | |
149 | } | |
150 | } | |
151 | audit_getname(result); | |
152 | return result; | |
153 | } | |
154 | ||
155 | #ifdef CONFIG_AUDITSYSCALL | |
156 | void putname(const char *name) | |
157 | { | |
158 | if (unlikely(current->audit_context)) | |
159 | audit_putname(name); | |
160 | else | |
161 | __putname(name); | |
162 | } | |
163 | EXPORT_SYMBOL(putname); | |
164 | #endif | |
165 | ||
166 | ||
167 | /** | |
168 | * generic_permission - check for access rights on a Posix-like filesystem | |
169 | * @inode: inode to check access rights for | |
170 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
171 | * @check_acl: optional callback to check for Posix ACLs | |
172 | * | |
173 | * Used to check for read/write/execute permissions on a file. | |
174 | * We use "fsuid" for this, letting us set arbitrary permissions | |
175 | * for filesystem access without changing the "normal" uids which | |
176 | * are used for other things.. | |
177 | */ | |
178 | int generic_permission(struct inode *inode, int mask, | |
179 | int (*check_acl)(struct inode *inode, int mask)) | |
180 | { | |
181 | umode_t mode = inode->i_mode; | |
182 | ||
183 | if (current->fsuid == inode->i_uid) | |
184 | mode >>= 6; | |
185 | else { | |
186 | if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { | |
187 | int error = check_acl(inode, mask); | |
188 | if (error == -EACCES) | |
189 | goto check_capabilities; | |
190 | else if (error != -EAGAIN) | |
191 | return error; | |
192 | } | |
193 | ||
194 | if (in_group_p(inode->i_gid)) | |
195 | mode >>= 3; | |
196 | } | |
197 | ||
198 | /* | |
199 | * If the DACs are ok we don't need any capability check. | |
200 | */ | |
201 | if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)) | |
202 | return 0; | |
203 | ||
204 | check_capabilities: | |
205 | /* | |
206 | * Read/write DACs are always overridable. | |
207 | * Executable DACs are overridable if at least one exec bit is set. | |
208 | */ | |
209 | if (!(mask & MAY_EXEC) || | |
210 | (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) | |
211 | if (capable(CAP_DAC_OVERRIDE)) | |
212 | return 0; | |
213 | ||
214 | /* | |
215 | * Searching includes executable on directories, else just read. | |
216 | */ | |
217 | if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) | |
218 | if (capable(CAP_DAC_READ_SEARCH)) | |
219 | return 0; | |
220 | ||
221 | return -EACCES; | |
222 | } | |
223 | ||
224 | int permission(struct inode *inode, int mask, struct nameidata *nd) | |
225 | { | |
226 | int retval, submask; | |
227 | ||
228 | if (mask & MAY_WRITE) { | |
229 | umode_t mode = inode->i_mode; | |
230 | ||
231 | /* | |
232 | * Nobody gets write access to a read-only fs. | |
233 | */ | |
234 | if (IS_RDONLY(inode) && | |
235 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
236 | return -EROFS; | |
237 | ||
238 | /* | |
239 | * Nobody gets write access to an immutable file. | |
240 | */ | |
241 | if (IS_IMMUTABLE(inode)) | |
242 | return -EACCES; | |
243 | } | |
244 | ||
245 | ||
246 | /* Ordinary permission routines do not understand MAY_APPEND. */ | |
247 | submask = mask & ~MAY_APPEND; | |
248 | if (inode->i_op && inode->i_op->permission) | |
249 | retval = inode->i_op->permission(inode, submask, nd); | |
250 | else | |
251 | retval = generic_permission(inode, submask, NULL); | |
252 | if (retval) | |
253 | return retval; | |
254 | ||
255 | return security_inode_permission(inode, mask, nd); | |
256 | } | |
257 | ||
258 | /* | |
259 | * get_write_access() gets write permission for a file. | |
260 | * put_write_access() releases this write permission. | |
261 | * This is used for regular files. | |
262 | * We cannot support write (and maybe mmap read-write shared) accesses and | |
263 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode | |
264 | * can have the following values: | |
265 | * 0: no writers, no VM_DENYWRITE mappings | |
266 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist | |
267 | * > 0: (i_writecount) users are writing to the file. | |
268 | * | |
269 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe | |
270 | * except for the cases where we don't hold i_writecount yet. Then we need to | |
271 | * use {get,deny}_write_access() - these functions check the sign and refuse | |
272 | * to do the change if sign is wrong. Exclusion between them is provided by | |
273 | * the inode->i_lock spinlock. | |
274 | */ | |
275 | ||
276 | int get_write_access(struct inode * inode) | |
277 | { | |
278 | spin_lock(&inode->i_lock); | |
279 | if (atomic_read(&inode->i_writecount) < 0) { | |
280 | spin_unlock(&inode->i_lock); | |
281 | return -ETXTBSY; | |
282 | } | |
283 | atomic_inc(&inode->i_writecount); | |
284 | spin_unlock(&inode->i_lock); | |
285 | ||
286 | return 0; | |
287 | } | |
288 | ||
289 | int deny_write_access(struct file * file) | |
290 | { | |
291 | struct inode *inode = file->f_dentry->d_inode; | |
292 | ||
293 | spin_lock(&inode->i_lock); | |
294 | if (atomic_read(&inode->i_writecount) > 0) { | |
295 | spin_unlock(&inode->i_lock); | |
296 | return -ETXTBSY; | |
297 | } | |
298 | atomic_dec(&inode->i_writecount); | |
299 | spin_unlock(&inode->i_lock); | |
300 | ||
301 | return 0; | |
302 | } | |
303 | ||
304 | void path_release(struct nameidata *nd) | |
305 | { | |
306 | dput(nd->dentry); | |
307 | mntput(nd->mnt); | |
308 | } | |
309 | ||
310 | /* | |
311 | * umount() mustn't call path_release()/mntput() as that would clear | |
312 | * mnt_expiry_mark | |
313 | */ | |
314 | void path_release_on_umount(struct nameidata *nd) | |
315 | { | |
316 | dput(nd->dentry); | |
751c404b | 317 | mntput_no_expire(nd->mnt); |
1da177e4 LT |
318 | } |
319 | ||
320 | /* | |
321 | * Internal lookup() using the new generic dcache. | |
322 | * SMP-safe | |
323 | */ | |
324 | static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
325 | { | |
326 | struct dentry * dentry = __d_lookup(parent, name); | |
327 | ||
328 | /* lockess __d_lookup may fail due to concurrent d_move() | |
329 | * in some unrelated directory, so try with d_lookup | |
330 | */ | |
331 | if (!dentry) | |
332 | dentry = d_lookup(parent, name); | |
333 | ||
334 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) { | |
335 | if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) { | |
336 | dput(dentry); | |
337 | dentry = NULL; | |
338 | } | |
339 | } | |
340 | return dentry; | |
341 | } | |
342 | ||
343 | /* | |
344 | * Short-cut version of permission(), for calling by | |
345 | * path_walk(), when dcache lock is held. Combines parts | |
346 | * of permission() and generic_permission(), and tests ONLY for | |
347 | * MAY_EXEC permission. | |
348 | * | |
349 | * If appropriate, check DAC only. If not appropriate, or | |
350 | * short-cut DAC fails, then call permission() to do more | |
351 | * complete permission check. | |
352 | */ | |
353 | static inline int exec_permission_lite(struct inode *inode, | |
354 | struct nameidata *nd) | |
355 | { | |
356 | umode_t mode = inode->i_mode; | |
357 | ||
358 | if (inode->i_op && inode->i_op->permission) | |
359 | return -EAGAIN; | |
360 | ||
361 | if (current->fsuid == inode->i_uid) | |
362 | mode >>= 6; | |
363 | else if (in_group_p(inode->i_gid)) | |
364 | mode >>= 3; | |
365 | ||
366 | if (mode & MAY_EXEC) | |
367 | goto ok; | |
368 | ||
369 | if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) | |
370 | goto ok; | |
371 | ||
372 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) | |
373 | goto ok; | |
374 | ||
375 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) | |
376 | goto ok; | |
377 | ||
378 | return -EACCES; | |
379 | ok: | |
380 | return security_inode_permission(inode, MAY_EXEC, nd); | |
381 | } | |
382 | ||
383 | /* | |
384 | * This is called when everything else fails, and we actually have | |
385 | * to go to the low-level filesystem to find out what we should do.. | |
386 | * | |
387 | * We get the directory semaphore, and after getting that we also | |
388 | * make sure that nobody added the entry to the dcache in the meantime.. | |
389 | * SMP-safe | |
390 | */ | |
391 | static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
392 | { | |
393 | struct dentry * result; | |
394 | struct inode *dir = parent->d_inode; | |
395 | ||
396 | down(&dir->i_sem); | |
397 | /* | |
398 | * First re-do the cached lookup just in case it was created | |
399 | * while we waited for the directory semaphore.. | |
400 | * | |
401 | * FIXME! This could use version numbering or similar to | |
402 | * avoid unnecessary cache lookups. | |
403 | * | |
404 | * The "dcache_lock" is purely to protect the RCU list walker | |
405 | * from concurrent renames at this point (we mustn't get false | |
406 | * negatives from the RCU list walk here, unlike the optimistic | |
407 | * fast walk). | |
408 | * | |
409 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup | |
410 | */ | |
411 | result = d_lookup(parent, name); | |
412 | if (!result) { | |
413 | struct dentry * dentry = d_alloc(parent, name); | |
414 | result = ERR_PTR(-ENOMEM); | |
415 | if (dentry) { | |
416 | result = dir->i_op->lookup(dir, dentry, nd); | |
417 | if (result) | |
418 | dput(dentry); | |
419 | else | |
420 | result = dentry; | |
421 | } | |
422 | up(&dir->i_sem); | |
423 | return result; | |
424 | } | |
425 | ||
426 | /* | |
427 | * Uhhuh! Nasty case: the cache was re-populated while | |
428 | * we waited on the semaphore. Need to revalidate. | |
429 | */ | |
430 | up(&dir->i_sem); | |
431 | if (result->d_op && result->d_op->d_revalidate) { | |
432 | if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) { | |
433 | dput(result); | |
434 | result = ERR_PTR(-ENOENT); | |
435 | } | |
436 | } | |
437 | return result; | |
438 | } | |
439 | ||
440 | static int __emul_lookup_dentry(const char *, struct nameidata *); | |
441 | ||
442 | /* SMP-safe */ | |
443 | static inline int | |
444 | walk_init_root(const char *name, struct nameidata *nd) | |
445 | { | |
446 | read_lock(¤t->fs->lock); | |
447 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { | |
448 | nd->mnt = mntget(current->fs->altrootmnt); | |
449 | nd->dentry = dget(current->fs->altroot); | |
450 | read_unlock(¤t->fs->lock); | |
451 | if (__emul_lookup_dentry(name,nd)) | |
452 | return 0; | |
453 | read_lock(¤t->fs->lock); | |
454 | } | |
455 | nd->mnt = mntget(current->fs->rootmnt); | |
456 | nd->dentry = dget(current->fs->root); | |
457 | read_unlock(¤t->fs->lock); | |
458 | return 1; | |
459 | } | |
460 | ||
461 | static inline int __vfs_follow_link(struct nameidata *nd, const char *link) | |
462 | { | |
463 | int res = 0; | |
464 | char *name; | |
465 | if (IS_ERR(link)) | |
466 | goto fail; | |
467 | ||
468 | if (*link == '/') { | |
469 | path_release(nd); | |
470 | if (!walk_init_root(link, nd)) | |
471 | /* weird __emul_prefix() stuff did it */ | |
472 | goto out; | |
473 | } | |
474 | res = link_path_walk(link, nd); | |
475 | out: | |
476 | if (nd->depth || res || nd->last_type!=LAST_NORM) | |
477 | return res; | |
478 | /* | |
479 | * If it is an iterative symlinks resolution in open_namei() we | |
480 | * have to copy the last component. And all that crap because of | |
481 | * bloody create() on broken symlinks. Furrfu... | |
482 | */ | |
483 | name = __getname(); | |
484 | if (unlikely(!name)) { | |
485 | path_release(nd); | |
486 | return -ENOMEM; | |
487 | } | |
488 | strcpy(name, nd->last.name); | |
489 | nd->last.name = name; | |
490 | return 0; | |
491 | fail: | |
492 | path_release(nd); | |
493 | return PTR_ERR(link); | |
494 | } | |
495 | ||
90ebe565 AV |
496 | struct path { |
497 | struct vfsmount *mnt; | |
498 | struct dentry *dentry; | |
499 | }; | |
500 | ||
cd4e91d3 | 501 | static inline int __do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
502 | { |
503 | int error; | |
cc314eef | 504 | void *cookie; |
cd4e91d3 | 505 | struct dentry *dentry = path->dentry; |
1da177e4 | 506 | |
d671a1cb | 507 | touch_atime(path->mnt, dentry); |
1da177e4 | 508 | nd_set_link(nd, NULL); |
cd4e91d3 | 509 | |
39ca6d49 AV |
510 | if (path->mnt == nd->mnt) |
511 | mntget(path->mnt); | |
cc314eef LT |
512 | cookie = dentry->d_inode->i_op->follow_link(dentry, nd); |
513 | error = PTR_ERR(cookie); | |
514 | if (!IS_ERR(cookie)) { | |
1da177e4 | 515 | char *s = nd_get_link(nd); |
cc314eef | 516 | error = 0; |
1da177e4 LT |
517 | if (s) |
518 | error = __vfs_follow_link(nd, s); | |
519 | if (dentry->d_inode->i_op->put_link) | |
cc314eef | 520 | dentry->d_inode->i_op->put_link(dentry, nd, cookie); |
1da177e4 | 521 | } |
cd4e91d3 AV |
522 | dput(dentry); |
523 | mntput(path->mnt); | |
1da177e4 LT |
524 | |
525 | return error; | |
526 | } | |
527 | ||
528 | /* | |
529 | * This limits recursive symlink follows to 8, while | |
530 | * limiting consecutive symlinks to 40. | |
531 | * | |
532 | * Without that kind of total limit, nasty chains of consecutive | |
533 | * symlinks can cause almost arbitrarily long lookups. | |
534 | */ | |
90ebe565 | 535 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
536 | { |
537 | int err = -ELOOP; | |
538 | if (current->link_count >= MAX_NESTED_LINKS) | |
539 | goto loop; | |
540 | if (current->total_link_count >= 40) | |
541 | goto loop; | |
542 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); | |
543 | cond_resched(); | |
90ebe565 | 544 | err = security_inode_follow_link(path->dentry, nd); |
1da177e4 LT |
545 | if (err) |
546 | goto loop; | |
547 | current->link_count++; | |
548 | current->total_link_count++; | |
549 | nd->depth++; | |
cd4e91d3 | 550 | err = __do_follow_link(path, nd); |
839d9f93 AV |
551 | current->link_count--; |
552 | nd->depth--; | |
1da177e4 LT |
553 | return err; |
554 | loop: | |
5f92b3bc | 555 | dput(path->dentry); |
d9d29a29 AV |
556 | if (path->mnt != nd->mnt) |
557 | mntput(path->mnt); | |
839d9f93 | 558 | path_release(nd); |
1da177e4 LT |
559 | return err; |
560 | } | |
561 | ||
562 | int follow_up(struct vfsmount **mnt, struct dentry **dentry) | |
563 | { | |
564 | struct vfsmount *parent; | |
565 | struct dentry *mountpoint; | |
566 | spin_lock(&vfsmount_lock); | |
567 | parent=(*mnt)->mnt_parent; | |
568 | if (parent == *mnt) { | |
569 | spin_unlock(&vfsmount_lock); | |
570 | return 0; | |
571 | } | |
572 | mntget(parent); | |
573 | mountpoint=dget((*mnt)->mnt_mountpoint); | |
574 | spin_unlock(&vfsmount_lock); | |
575 | dput(*dentry); | |
576 | *dentry = mountpoint; | |
577 | mntput(*mnt); | |
578 | *mnt = parent; | |
579 | return 1; | |
580 | } | |
581 | ||
582 | /* no need for dcache_lock, as serialization is taken care in | |
583 | * namespace.c | |
584 | */ | |
463ffb2e AV |
585 | static int __follow_mount(struct path *path) |
586 | { | |
587 | int res = 0; | |
588 | while (d_mountpoint(path->dentry)) { | |
589 | struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); | |
590 | if (!mounted) | |
591 | break; | |
592 | dput(path->dentry); | |
593 | if (res) | |
594 | mntput(path->mnt); | |
595 | path->mnt = mounted; | |
596 | path->dentry = dget(mounted->mnt_root); | |
597 | res = 1; | |
598 | } | |
599 | return res; | |
600 | } | |
601 | ||
58c465eb | 602 | static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 | 603 | { |
1da177e4 LT |
604 | while (d_mountpoint(*dentry)) { |
605 | struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); | |
606 | if (!mounted) | |
607 | break; | |
58c465eb | 608 | dput(*dentry); |
1da177e4 LT |
609 | mntput(*mnt); |
610 | *mnt = mounted; | |
1da177e4 | 611 | *dentry = dget(mounted->mnt_root); |
1da177e4 | 612 | } |
1da177e4 LT |
613 | } |
614 | ||
615 | /* no need for dcache_lock, as serialization is taken care in | |
616 | * namespace.c | |
617 | */ | |
e13b210f | 618 | int follow_down(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 LT |
619 | { |
620 | struct vfsmount *mounted; | |
621 | ||
622 | mounted = lookup_mnt(*mnt, *dentry); | |
623 | if (mounted) { | |
e13b210f | 624 | dput(*dentry); |
1da177e4 LT |
625 | mntput(*mnt); |
626 | *mnt = mounted; | |
1da177e4 LT |
627 | *dentry = dget(mounted->mnt_root); |
628 | return 1; | |
629 | } | |
630 | return 0; | |
631 | } | |
632 | ||
58c465eb | 633 | static inline void follow_dotdot(struct nameidata *nd) |
1da177e4 LT |
634 | { |
635 | while(1) { | |
636 | struct vfsmount *parent; | |
58c465eb | 637 | struct dentry *old = nd->dentry; |
1da177e4 LT |
638 | |
639 | read_lock(¤t->fs->lock); | |
58c465eb AV |
640 | if (nd->dentry == current->fs->root && |
641 | nd->mnt == current->fs->rootmnt) { | |
1da177e4 LT |
642 | read_unlock(¤t->fs->lock); |
643 | break; | |
644 | } | |
645 | read_unlock(¤t->fs->lock); | |
646 | spin_lock(&dcache_lock); | |
58c465eb AV |
647 | if (nd->dentry != nd->mnt->mnt_root) { |
648 | nd->dentry = dget(nd->dentry->d_parent); | |
1da177e4 LT |
649 | spin_unlock(&dcache_lock); |
650 | dput(old); | |
651 | break; | |
652 | } | |
653 | spin_unlock(&dcache_lock); | |
654 | spin_lock(&vfsmount_lock); | |
58c465eb AV |
655 | parent = nd->mnt->mnt_parent; |
656 | if (parent == nd->mnt) { | |
1da177e4 LT |
657 | spin_unlock(&vfsmount_lock); |
658 | break; | |
659 | } | |
660 | mntget(parent); | |
58c465eb | 661 | nd->dentry = dget(nd->mnt->mnt_mountpoint); |
1da177e4 LT |
662 | spin_unlock(&vfsmount_lock); |
663 | dput(old); | |
58c465eb AV |
664 | mntput(nd->mnt); |
665 | nd->mnt = parent; | |
1da177e4 | 666 | } |
58c465eb | 667 | follow_mount(&nd->mnt, &nd->dentry); |
1da177e4 LT |
668 | } |
669 | ||
1da177e4 LT |
670 | /* |
671 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
672 | * small and for now I'd prefer to have fast path as straight as possible. | |
673 | * It _is_ time-critical. | |
674 | */ | |
675 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
676 | struct path *path) | |
677 | { | |
678 | struct vfsmount *mnt = nd->mnt; | |
679 | struct dentry *dentry = __d_lookup(nd->dentry, name); | |
680 | ||
681 | if (!dentry) | |
682 | goto need_lookup; | |
683 | if (dentry->d_op && dentry->d_op->d_revalidate) | |
684 | goto need_revalidate; | |
685 | done: | |
686 | path->mnt = mnt; | |
687 | path->dentry = dentry; | |
634ee701 | 688 | __follow_mount(path); |
1da177e4 LT |
689 | return 0; |
690 | ||
691 | need_lookup: | |
692 | dentry = real_lookup(nd->dentry, name, nd); | |
693 | if (IS_ERR(dentry)) | |
694 | goto fail; | |
695 | goto done; | |
696 | ||
697 | need_revalidate: | |
698 | if (dentry->d_op->d_revalidate(dentry, nd)) | |
699 | goto done; | |
700 | if (d_invalidate(dentry)) | |
701 | goto done; | |
702 | dput(dentry); | |
703 | goto need_lookup; | |
704 | ||
705 | fail: | |
706 | return PTR_ERR(dentry); | |
707 | } | |
708 | ||
709 | /* | |
710 | * Name resolution. | |
ea3834d9 PM |
711 | * This is the basic name resolution function, turning a pathname into |
712 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 713 | * |
ea3834d9 PM |
714 | * Returns 0 and nd will have valid dentry and mnt on success. |
715 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 LT |
716 | */ |
717 | static fastcall int __link_path_walk(const char * name, struct nameidata *nd) | |
718 | { | |
719 | struct path next; | |
720 | struct inode *inode; | |
721 | int err; | |
722 | unsigned int lookup_flags = nd->flags; | |
723 | ||
724 | while (*name=='/') | |
725 | name++; | |
726 | if (!*name) | |
727 | goto return_reval; | |
728 | ||
729 | inode = nd->dentry->d_inode; | |
730 | if (nd->depth) | |
731 | lookup_flags = LOOKUP_FOLLOW; | |
732 | ||
733 | /* At this point we know we have a real path component. */ | |
734 | for(;;) { | |
735 | unsigned long hash; | |
736 | struct qstr this; | |
737 | unsigned int c; | |
738 | ||
739 | err = exec_permission_lite(inode, nd); | |
740 | if (err == -EAGAIN) { | |
741 | err = permission(inode, MAY_EXEC, nd); | |
742 | } | |
743 | if (err) | |
744 | break; | |
745 | ||
746 | this.name = name; | |
747 | c = *(const unsigned char *)name; | |
748 | ||
749 | hash = init_name_hash(); | |
750 | do { | |
751 | name++; | |
752 | hash = partial_name_hash(c, hash); | |
753 | c = *(const unsigned char *)name; | |
754 | } while (c && (c != '/')); | |
755 | this.len = name - (const char *) this.name; | |
756 | this.hash = end_name_hash(hash); | |
757 | ||
758 | /* remove trailing slashes? */ | |
759 | if (!c) | |
760 | goto last_component; | |
761 | while (*++name == '/'); | |
762 | if (!*name) | |
763 | goto last_with_slashes; | |
764 | ||
765 | /* | |
766 | * "." and ".." are special - ".." especially so because it has | |
767 | * to be able to know about the current root directory and | |
768 | * parent relationships. | |
769 | */ | |
770 | if (this.name[0] == '.') switch (this.len) { | |
771 | default: | |
772 | break; | |
773 | case 2: | |
774 | if (this.name[1] != '.') | |
775 | break; | |
58c465eb | 776 | follow_dotdot(nd); |
1da177e4 LT |
777 | inode = nd->dentry->d_inode; |
778 | /* fallthrough */ | |
779 | case 1: | |
780 | continue; | |
781 | } | |
782 | /* | |
783 | * See if the low-level filesystem might want | |
784 | * to use its own hash.. | |
785 | */ | |
786 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { | |
787 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); | |
788 | if (err < 0) | |
789 | break; | |
790 | } | |
791 | nd->flags |= LOOKUP_CONTINUE; | |
792 | /* This does the actual lookups.. */ | |
793 | err = do_lookup(nd, &this, &next); | |
794 | if (err) | |
795 | break; | |
1da177e4 LT |
796 | |
797 | err = -ENOENT; | |
798 | inode = next.dentry->d_inode; | |
799 | if (!inode) | |
800 | goto out_dput; | |
801 | err = -ENOTDIR; | |
802 | if (!inode->i_op) | |
803 | goto out_dput; | |
804 | ||
805 | if (inode->i_op->follow_link) { | |
90ebe565 | 806 | err = do_follow_link(&next, nd); |
1da177e4 LT |
807 | if (err) |
808 | goto return_err; | |
809 | err = -ENOENT; | |
810 | inode = nd->dentry->d_inode; | |
811 | if (!inode) | |
812 | break; | |
813 | err = -ENOTDIR; | |
814 | if (!inode->i_op) | |
815 | break; | |
816 | } else { | |
817 | dput(nd->dentry); | |
2f12dbfb AV |
818 | if (nd->mnt != next.mnt) |
819 | mntput(nd->mnt); | |
1da177e4 LT |
820 | nd->mnt = next.mnt; |
821 | nd->dentry = next.dentry; | |
822 | } | |
823 | err = -ENOTDIR; | |
824 | if (!inode->i_op->lookup) | |
825 | break; | |
826 | continue; | |
827 | /* here ends the main loop */ | |
828 | ||
829 | last_with_slashes: | |
830 | lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
831 | last_component: | |
832 | nd->flags &= ~LOOKUP_CONTINUE; | |
833 | if (lookup_flags & LOOKUP_PARENT) | |
834 | goto lookup_parent; | |
835 | if (this.name[0] == '.') switch (this.len) { | |
836 | default: | |
837 | break; | |
838 | case 2: | |
839 | if (this.name[1] != '.') | |
840 | break; | |
58c465eb | 841 | follow_dotdot(nd); |
1da177e4 LT |
842 | inode = nd->dentry->d_inode; |
843 | /* fallthrough */ | |
844 | case 1: | |
845 | goto return_reval; | |
846 | } | |
847 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { | |
848 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); | |
849 | if (err < 0) | |
850 | break; | |
851 | } | |
852 | err = do_lookup(nd, &this, &next); | |
853 | if (err) | |
854 | break; | |
1da177e4 LT |
855 | inode = next.dentry->d_inode; |
856 | if ((lookup_flags & LOOKUP_FOLLOW) | |
857 | && inode && inode->i_op && inode->i_op->follow_link) { | |
90ebe565 | 858 | err = do_follow_link(&next, nd); |
1da177e4 LT |
859 | if (err) |
860 | goto return_err; | |
861 | inode = nd->dentry->d_inode; | |
862 | } else { | |
863 | dput(nd->dentry); | |
2f12dbfb AV |
864 | if (nd->mnt != next.mnt) |
865 | mntput(nd->mnt); | |
1da177e4 LT |
866 | nd->mnt = next.mnt; |
867 | nd->dentry = next.dentry; | |
868 | } | |
869 | err = -ENOENT; | |
870 | if (!inode) | |
871 | break; | |
872 | if (lookup_flags & LOOKUP_DIRECTORY) { | |
873 | err = -ENOTDIR; | |
874 | if (!inode->i_op || !inode->i_op->lookup) | |
875 | break; | |
876 | } | |
877 | goto return_base; | |
878 | lookup_parent: | |
879 | nd->last = this; | |
880 | nd->last_type = LAST_NORM; | |
881 | if (this.name[0] != '.') | |
882 | goto return_base; | |
883 | if (this.len == 1) | |
884 | nd->last_type = LAST_DOT; | |
885 | else if (this.len == 2 && this.name[1] == '.') | |
886 | nd->last_type = LAST_DOTDOT; | |
887 | else | |
888 | goto return_base; | |
889 | return_reval: | |
890 | /* | |
891 | * We bypassed the ordinary revalidation routines. | |
892 | * We may need to check the cached dentry for staleness. | |
893 | */ | |
894 | if (nd->dentry && nd->dentry->d_sb && | |
895 | (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { | |
896 | err = -ESTALE; | |
897 | /* Note: we do not d_invalidate() */ | |
898 | if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd)) | |
899 | break; | |
900 | } | |
901 | return_base: | |
902 | return 0; | |
903 | out_dput: | |
904 | dput(next.dentry); | |
2f12dbfb | 905 | if (nd->mnt != next.mnt) |
d9d29a29 | 906 | mntput(next.mnt); |
1da177e4 LT |
907 | break; |
908 | } | |
909 | path_release(nd); | |
910 | return_err: | |
911 | return err; | |
912 | } | |
913 | ||
914 | /* | |
915 | * Wrapper to retry pathname resolution whenever the underlying | |
916 | * file system returns an ESTALE. | |
917 | * | |
918 | * Retry the whole path once, forcing real lookup requests | |
919 | * instead of relying on the dcache. | |
920 | */ | |
921 | int fastcall link_path_walk(const char *name, struct nameidata *nd) | |
922 | { | |
923 | struct nameidata save = *nd; | |
924 | int result; | |
925 | ||
926 | /* make sure the stuff we saved doesn't go away */ | |
927 | dget(save.dentry); | |
928 | mntget(save.mnt); | |
929 | ||
930 | result = __link_path_walk(name, nd); | |
931 | if (result == -ESTALE) { | |
932 | *nd = save; | |
933 | dget(nd->dentry); | |
934 | mntget(nd->mnt); | |
935 | nd->flags |= LOOKUP_REVAL; | |
936 | result = __link_path_walk(name, nd); | |
937 | } | |
938 | ||
939 | dput(save.dentry); | |
940 | mntput(save.mnt); | |
941 | ||
942 | return result; | |
943 | } | |
944 | ||
945 | int fastcall path_walk(const char * name, struct nameidata *nd) | |
946 | { | |
947 | current->total_link_count = 0; | |
948 | return link_path_walk(name, nd); | |
949 | } | |
950 | ||
ea3834d9 PM |
951 | /* |
952 | * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if | |
953 | * everything is done. Returns 0 and drops input nd, if lookup failed; | |
954 | */ | |
1da177e4 LT |
955 | static int __emul_lookup_dentry(const char *name, struct nameidata *nd) |
956 | { | |
957 | if (path_walk(name, nd)) | |
958 | return 0; /* something went wrong... */ | |
959 | ||
960 | if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) { | |
961 | struct dentry *old_dentry = nd->dentry; | |
962 | struct vfsmount *old_mnt = nd->mnt; | |
963 | struct qstr last = nd->last; | |
964 | int last_type = nd->last_type; | |
965 | /* | |
966 | * NAME was not found in alternate root or it's a directory. Try to find | |
967 | * it in the normal root: | |
968 | */ | |
969 | nd->last_type = LAST_ROOT; | |
970 | read_lock(¤t->fs->lock); | |
971 | nd->mnt = mntget(current->fs->rootmnt); | |
972 | nd->dentry = dget(current->fs->root); | |
973 | read_unlock(¤t->fs->lock); | |
974 | if (path_walk(name, nd) == 0) { | |
975 | if (nd->dentry->d_inode) { | |
976 | dput(old_dentry); | |
977 | mntput(old_mnt); | |
978 | return 1; | |
979 | } | |
980 | path_release(nd); | |
981 | } | |
982 | nd->dentry = old_dentry; | |
983 | nd->mnt = old_mnt; | |
984 | nd->last = last; | |
985 | nd->last_type = last_type; | |
986 | } | |
987 | return 1; | |
988 | } | |
989 | ||
990 | void set_fs_altroot(void) | |
991 | { | |
992 | char *emul = __emul_prefix(); | |
993 | struct nameidata nd; | |
994 | struct vfsmount *mnt = NULL, *oldmnt; | |
995 | struct dentry *dentry = NULL, *olddentry; | |
996 | int err; | |
997 | ||
998 | if (!emul) | |
999 | goto set_it; | |
1000 | err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); | |
1001 | if (!err) { | |
1002 | mnt = nd.mnt; | |
1003 | dentry = nd.dentry; | |
1004 | } | |
1005 | set_it: | |
1006 | write_lock(¤t->fs->lock); | |
1007 | oldmnt = current->fs->altrootmnt; | |
1008 | olddentry = current->fs->altroot; | |
1009 | current->fs->altrootmnt = mnt; | |
1010 | current->fs->altroot = dentry; | |
1011 | write_unlock(¤t->fs->lock); | |
1012 | if (olddentry) { | |
1013 | dput(olddentry); | |
1014 | mntput(oldmnt); | |
1015 | } | |
1016 | } | |
1017 | ||
ea3834d9 | 1018 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
1da177e4 LT |
1019 | int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd) |
1020 | { | |
ea3834d9 | 1021 | int retval = 0; |
1da177e4 LT |
1022 | |
1023 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
1024 | nd->flags = flags; | |
1025 | nd->depth = 0; | |
1026 | ||
1027 | read_lock(¤t->fs->lock); | |
1028 | if (*name=='/') { | |
1029 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { | |
1030 | nd->mnt = mntget(current->fs->altrootmnt); | |
1031 | nd->dentry = dget(current->fs->altroot); | |
1032 | read_unlock(¤t->fs->lock); | |
1033 | if (__emul_lookup_dentry(name,nd)) | |
ea3834d9 | 1034 | goto out; /* found in altroot */ |
1da177e4 LT |
1035 | read_lock(¤t->fs->lock); |
1036 | } | |
1037 | nd->mnt = mntget(current->fs->rootmnt); | |
1038 | nd->dentry = dget(current->fs->root); | |
1039 | } else { | |
1040 | nd->mnt = mntget(current->fs->pwdmnt); | |
1041 | nd->dentry = dget(current->fs->pwd); | |
1042 | } | |
1043 | read_unlock(¤t->fs->lock); | |
1044 | current->total_link_count = 0; | |
1045 | retval = link_path_walk(name, nd); | |
ea3834d9 | 1046 | out: |
1da177e4 LT |
1047 | if (unlikely(current->audit_context |
1048 | && nd && nd->dentry && nd->dentry->d_inode)) | |
1049 | audit_inode(name, nd->dentry->d_inode); | |
1050 | return retval; | |
1051 | } | |
1052 | ||
1053 | /* | |
1054 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1055 | * needs parent already locked. Doesn't follow mounts. | |
1056 | * SMP-safe. | |
1057 | */ | |
1058 | static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd) | |
1059 | { | |
1060 | struct dentry * dentry; | |
1061 | struct inode *inode; | |
1062 | int err; | |
1063 | ||
1064 | inode = base->d_inode; | |
1065 | err = permission(inode, MAY_EXEC, nd); | |
1066 | dentry = ERR_PTR(err); | |
1067 | if (err) | |
1068 | goto out; | |
1069 | ||
1070 | /* | |
1071 | * See if the low-level filesystem might want | |
1072 | * to use its own hash.. | |
1073 | */ | |
1074 | if (base->d_op && base->d_op->d_hash) { | |
1075 | err = base->d_op->d_hash(base, name); | |
1076 | dentry = ERR_PTR(err); | |
1077 | if (err < 0) | |
1078 | goto out; | |
1079 | } | |
1080 | ||
1081 | dentry = cached_lookup(base, name, nd); | |
1082 | if (!dentry) { | |
1083 | struct dentry *new = d_alloc(base, name); | |
1084 | dentry = ERR_PTR(-ENOMEM); | |
1085 | if (!new) | |
1086 | goto out; | |
1087 | dentry = inode->i_op->lookup(inode, new, nd); | |
1088 | if (!dentry) | |
1089 | dentry = new; | |
1090 | else | |
1091 | dput(new); | |
1092 | } | |
1093 | out: | |
1094 | return dentry; | |
1095 | } | |
1096 | ||
1097 | struct dentry * lookup_hash(struct qstr *name, struct dentry * base) | |
1098 | { | |
1099 | return __lookup_hash(name, base, NULL); | |
1100 | } | |
1101 | ||
1102 | /* SMP-safe */ | |
1103 | struct dentry * lookup_one_len(const char * name, struct dentry * base, int len) | |
1104 | { | |
1105 | unsigned long hash; | |
1106 | struct qstr this; | |
1107 | unsigned int c; | |
1108 | ||
1109 | this.name = name; | |
1110 | this.len = len; | |
1111 | if (!len) | |
1112 | goto access; | |
1113 | ||
1114 | hash = init_name_hash(); | |
1115 | while (len--) { | |
1116 | c = *(const unsigned char *)name++; | |
1117 | if (c == '/' || c == '\0') | |
1118 | goto access; | |
1119 | hash = partial_name_hash(c, hash); | |
1120 | } | |
1121 | this.hash = end_name_hash(hash); | |
1122 | ||
1123 | return lookup_hash(&this, base); | |
1124 | access: | |
1125 | return ERR_PTR(-EACCES); | |
1126 | } | |
1127 | ||
1128 | /* | |
1129 | * namei() | |
1130 | * | |
1131 | * is used by most simple commands to get the inode of a specified name. | |
1132 | * Open, link etc use their own routines, but this is enough for things | |
1133 | * like 'chmod' etc. | |
1134 | * | |
1135 | * namei exists in two versions: namei/lnamei. The only difference is | |
1136 | * that namei follows links, while lnamei does not. | |
1137 | * SMP-safe | |
1138 | */ | |
1139 | int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) | |
1140 | { | |
1141 | char *tmp = getname(name); | |
1142 | int err = PTR_ERR(tmp); | |
1143 | ||
1144 | if (!IS_ERR(tmp)) { | |
1145 | err = path_lookup(tmp, flags, nd); | |
1146 | putname(tmp); | |
1147 | } | |
1148 | return err; | |
1149 | } | |
1150 | ||
1151 | /* | |
1152 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1153 | * minimal. | |
1154 | */ | |
1155 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1156 | { | |
1157 | if (!(dir->i_mode & S_ISVTX)) | |
1158 | return 0; | |
1159 | if (inode->i_uid == current->fsuid) | |
1160 | return 0; | |
1161 | if (dir->i_uid == current->fsuid) | |
1162 | return 0; | |
1163 | return !capable(CAP_FOWNER); | |
1164 | } | |
1165 | ||
1166 | /* | |
1167 | * Check whether we can remove a link victim from directory dir, check | |
1168 | * whether the type of victim is right. | |
1169 | * 1. We can't do it if dir is read-only (done in permission()) | |
1170 | * 2. We should have write and exec permissions on dir | |
1171 | * 3. We can't remove anything from append-only dir | |
1172 | * 4. We can't do anything with immutable dir (done in permission()) | |
1173 | * 5. If the sticky bit on dir is set we should either | |
1174 | * a. be owner of dir, or | |
1175 | * b. be owner of victim, or | |
1176 | * c. have CAP_FOWNER capability | |
1177 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1178 | * links pointing to it. | |
1179 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1180 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1181 | * 9. We can't remove a root or mountpoint. | |
1182 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1183 | * nfs_async_unlink(). | |
1184 | */ | |
1185 | static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir) | |
1186 | { | |
1187 | int error; | |
1188 | ||
1189 | if (!victim->d_inode) | |
1190 | return -ENOENT; | |
1191 | ||
1192 | BUG_ON(victim->d_parent->d_inode != dir); | |
1193 | ||
1194 | error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); | |
1195 | if (error) | |
1196 | return error; | |
1197 | if (IS_APPEND(dir)) | |
1198 | return -EPERM; | |
1199 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
1200 | IS_IMMUTABLE(victim->d_inode)) | |
1201 | return -EPERM; | |
1202 | if (isdir) { | |
1203 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1204 | return -ENOTDIR; | |
1205 | if (IS_ROOT(victim)) | |
1206 | return -EBUSY; | |
1207 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1208 | return -EISDIR; | |
1209 | if (IS_DEADDIR(dir)) | |
1210 | return -ENOENT; | |
1211 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1212 | return -EBUSY; | |
1213 | return 0; | |
1214 | } | |
1215 | ||
1216 | /* Check whether we can create an object with dentry child in directory | |
1217 | * dir. | |
1218 | * 1. We can't do it if child already exists (open has special treatment for | |
1219 | * this case, but since we are inlined it's OK) | |
1220 | * 2. We can't do it if dir is read-only (done in permission()) | |
1221 | * 3. We should have write and exec permissions on dir | |
1222 | * 4. We can't do it if dir is immutable (done in permission()) | |
1223 | */ | |
1224 | static inline int may_create(struct inode *dir, struct dentry *child, | |
1225 | struct nameidata *nd) | |
1226 | { | |
1227 | if (child->d_inode) | |
1228 | return -EEXIST; | |
1229 | if (IS_DEADDIR(dir)) | |
1230 | return -ENOENT; | |
1231 | return permission(dir,MAY_WRITE | MAY_EXEC, nd); | |
1232 | } | |
1233 | ||
1234 | /* | |
1235 | * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security | |
1236 | * reasons. | |
1237 | * | |
1238 | * O_DIRECTORY translates into forcing a directory lookup. | |
1239 | */ | |
1240 | static inline int lookup_flags(unsigned int f) | |
1241 | { | |
1242 | unsigned long retval = LOOKUP_FOLLOW; | |
1243 | ||
1244 | if (f & O_NOFOLLOW) | |
1245 | retval &= ~LOOKUP_FOLLOW; | |
1246 | ||
1247 | if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)) | |
1248 | retval &= ~LOOKUP_FOLLOW; | |
1249 | ||
1250 | if (f & O_DIRECTORY) | |
1251 | retval |= LOOKUP_DIRECTORY; | |
1252 | ||
1253 | return retval; | |
1254 | } | |
1255 | ||
1256 | /* | |
1257 | * p1 and p2 should be directories on the same fs. | |
1258 | */ | |
1259 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1260 | { | |
1261 | struct dentry *p; | |
1262 | ||
1263 | if (p1 == p2) { | |
1264 | down(&p1->d_inode->i_sem); | |
1265 | return NULL; | |
1266 | } | |
1267 | ||
1268 | down(&p1->d_inode->i_sb->s_vfs_rename_sem); | |
1269 | ||
1270 | for (p = p1; p->d_parent != p; p = p->d_parent) { | |
1271 | if (p->d_parent == p2) { | |
1272 | down(&p2->d_inode->i_sem); | |
1273 | down(&p1->d_inode->i_sem); | |
1274 | return p; | |
1275 | } | |
1276 | } | |
1277 | ||
1278 | for (p = p2; p->d_parent != p; p = p->d_parent) { | |
1279 | if (p->d_parent == p1) { | |
1280 | down(&p1->d_inode->i_sem); | |
1281 | down(&p2->d_inode->i_sem); | |
1282 | return p; | |
1283 | } | |
1284 | } | |
1285 | ||
1286 | down(&p1->d_inode->i_sem); | |
1287 | down(&p2->d_inode->i_sem); | |
1288 | return NULL; | |
1289 | } | |
1290 | ||
1291 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1292 | { | |
1293 | up(&p1->d_inode->i_sem); | |
1294 | if (p1 != p2) { | |
1295 | up(&p2->d_inode->i_sem); | |
1296 | up(&p1->d_inode->i_sb->s_vfs_rename_sem); | |
1297 | } | |
1298 | } | |
1299 | ||
1300 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1301 | struct nameidata *nd) | |
1302 | { | |
1303 | int error = may_create(dir, dentry, nd); | |
1304 | ||
1305 | if (error) | |
1306 | return error; | |
1307 | ||
1308 | if (!dir->i_op || !dir->i_op->create) | |
1309 | return -EACCES; /* shouldn't it be ENOSYS? */ | |
1310 | mode &= S_IALLUGO; | |
1311 | mode |= S_IFREG; | |
1312 | error = security_inode_create(dir, dentry, mode); | |
1313 | if (error) | |
1314 | return error; | |
1315 | DQUOT_INIT(dir); | |
1316 | error = dir->i_op->create(dir, dentry, mode, nd); | |
1317 | if (!error) { | |
0eeca283 | 1318 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
1319 | security_inode_post_create(dir, dentry, mode); |
1320 | } | |
1321 | return error; | |
1322 | } | |
1323 | ||
1324 | int may_open(struct nameidata *nd, int acc_mode, int flag) | |
1325 | { | |
1326 | struct dentry *dentry = nd->dentry; | |
1327 | struct inode *inode = dentry->d_inode; | |
1328 | int error; | |
1329 | ||
1330 | if (!inode) | |
1331 | return -ENOENT; | |
1332 | ||
1333 | if (S_ISLNK(inode->i_mode)) | |
1334 | return -ELOOP; | |
1335 | ||
1336 | if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE)) | |
1337 | return -EISDIR; | |
1338 | ||
1339 | error = permission(inode, acc_mode, nd); | |
1340 | if (error) | |
1341 | return error; | |
1342 | ||
1343 | /* | |
1344 | * FIFO's, sockets and device files are special: they don't | |
1345 | * actually live on the filesystem itself, and as such you | |
1346 | * can write to them even if the filesystem is read-only. | |
1347 | */ | |
1348 | if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { | |
1349 | flag &= ~O_TRUNC; | |
1350 | } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { | |
1351 | if (nd->mnt->mnt_flags & MNT_NODEV) | |
1352 | return -EACCES; | |
1353 | ||
1354 | flag &= ~O_TRUNC; | |
1355 | } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE)) | |
1356 | return -EROFS; | |
1357 | /* | |
1358 | * An append-only file must be opened in append mode for writing. | |
1359 | */ | |
1360 | if (IS_APPEND(inode)) { | |
1361 | if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) | |
1362 | return -EPERM; | |
1363 | if (flag & O_TRUNC) | |
1364 | return -EPERM; | |
1365 | } | |
1366 | ||
1367 | /* O_NOATIME can only be set by the owner or superuser */ | |
1368 | if (flag & O_NOATIME) | |
1369 | if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) | |
1370 | return -EPERM; | |
1371 | ||
1372 | /* | |
1373 | * Ensure there are no outstanding leases on the file. | |
1374 | */ | |
1375 | error = break_lease(inode, flag); | |
1376 | if (error) | |
1377 | return error; | |
1378 | ||
1379 | if (flag & O_TRUNC) { | |
1380 | error = get_write_access(inode); | |
1381 | if (error) | |
1382 | return error; | |
1383 | ||
1384 | /* | |
1385 | * Refuse to truncate files with mandatory locks held on them. | |
1386 | */ | |
1387 | error = locks_verify_locked(inode); | |
1388 | if (!error) { | |
1389 | DQUOT_INIT(inode); | |
1390 | ||
1391 | error = do_truncate(dentry, 0); | |
1392 | } | |
1393 | put_write_access(inode); | |
1394 | if (error) | |
1395 | return error; | |
1396 | } else | |
1397 | if (flag & FMODE_WRITE) | |
1398 | DQUOT_INIT(inode); | |
1399 | ||
1400 | return 0; | |
1401 | } | |
1402 | ||
1403 | /* | |
1404 | * open_namei() | |
1405 | * | |
1406 | * namei for open - this is in fact almost the whole open-routine. | |
1407 | * | |
1408 | * Note that the low bits of "flag" aren't the same as in the open | |
1409 | * system call - they are 00 - no permissions needed | |
1410 | * 01 - read permission needed | |
1411 | * 10 - write permission needed | |
1412 | * 11 - read/write permissions needed | |
1413 | * which is a lot more logical, and also allows the "no perm" needed | |
1414 | * for symlinks (where the permissions are checked later). | |
1415 | * SMP-safe | |
1416 | */ | |
1417 | int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) | |
1418 | { | |
1419 | int acc_mode, error = 0; | |
4e7506e4 | 1420 | struct path path; |
1da177e4 LT |
1421 | struct dentry *dir; |
1422 | int count = 0; | |
1423 | ||
1424 | acc_mode = ACC_MODE(flag); | |
1425 | ||
1426 | /* Allow the LSM permission hook to distinguish append | |
1427 | access from general write access. */ | |
1428 | if (flag & O_APPEND) | |
1429 | acc_mode |= MAY_APPEND; | |
1430 | ||
1431 | /* Fill in the open() intent data */ | |
1432 | nd->intent.open.flags = flag; | |
1433 | nd->intent.open.create_mode = mode; | |
1434 | ||
1435 | /* | |
1436 | * The simplest case - just a plain lookup. | |
1437 | */ | |
1438 | if (!(flag & O_CREAT)) { | |
1439 | error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd); | |
1440 | if (error) | |
1441 | return error; | |
1442 | goto ok; | |
1443 | } | |
1444 | ||
1445 | /* | |
1446 | * Create - we need to know the parent. | |
1447 | */ | |
1448 | error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd); | |
1449 | if (error) | |
1450 | return error; | |
1451 | ||
1452 | /* | |
1453 | * We have the parent and last component. First of all, check | |
1454 | * that we are not asked to creat(2) an obvious directory - that | |
1455 | * will not do. | |
1456 | */ | |
1457 | error = -EISDIR; | |
1458 | if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len]) | |
1459 | goto exit; | |
1460 | ||
1461 | dir = nd->dentry; | |
1462 | nd->flags &= ~LOOKUP_PARENT; | |
1463 | down(&dir->d_inode->i_sem); | |
4e7506e4 | 1464 | path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); |
d73ffe16 | 1465 | path.mnt = nd->mnt; |
1da177e4 LT |
1466 | |
1467 | do_last: | |
4e7506e4 AV |
1468 | error = PTR_ERR(path.dentry); |
1469 | if (IS_ERR(path.dentry)) { | |
1da177e4 LT |
1470 | up(&dir->d_inode->i_sem); |
1471 | goto exit; | |
1472 | } | |
1473 | ||
1474 | /* Negative dentry, just create the file */ | |
4e7506e4 | 1475 | if (!path.dentry->d_inode) { |
1da177e4 LT |
1476 | if (!IS_POSIXACL(dir->d_inode)) |
1477 | mode &= ~current->fs->umask; | |
4e7506e4 | 1478 | error = vfs_create(dir->d_inode, path.dentry, mode, nd); |
1da177e4 LT |
1479 | up(&dir->d_inode->i_sem); |
1480 | dput(nd->dentry); | |
4e7506e4 | 1481 | nd->dentry = path.dentry; |
1da177e4 LT |
1482 | if (error) |
1483 | goto exit; | |
1484 | /* Don't check for write permission, don't truncate */ | |
1485 | acc_mode = 0; | |
1486 | flag &= ~O_TRUNC; | |
1487 | goto ok; | |
1488 | } | |
1489 | ||
1490 | /* | |
1491 | * It already exists. | |
1492 | */ | |
1493 | up(&dir->d_inode->i_sem); | |
1494 | ||
1495 | error = -EEXIST; | |
1496 | if (flag & O_EXCL) | |
1497 | goto exit_dput; | |
1498 | ||
e13b210f | 1499 | if (__follow_mount(&path)) { |
1da177e4 | 1500 | error = -ELOOP; |
ba7a4c1a AV |
1501 | if (flag & O_NOFOLLOW) |
1502 | goto exit_dput; | |
1da177e4 LT |
1503 | } |
1504 | error = -ENOENT; | |
4e7506e4 | 1505 | if (!path.dentry->d_inode) |
1da177e4 | 1506 | goto exit_dput; |
4e7506e4 | 1507 | if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) |
1da177e4 LT |
1508 | goto do_link; |
1509 | ||
1510 | dput(nd->dentry); | |
4e7506e4 | 1511 | nd->dentry = path.dentry; |
a15a3f6f AV |
1512 | if (nd->mnt != path.mnt) |
1513 | mntput(nd->mnt); | |
1514 | nd->mnt = path.mnt; | |
1da177e4 | 1515 | error = -EISDIR; |
4e7506e4 | 1516 | if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) |
1da177e4 LT |
1517 | goto exit; |
1518 | ok: | |
1519 | error = may_open(nd, acc_mode, flag); | |
1520 | if (error) | |
1521 | goto exit; | |
1522 | return 0; | |
1523 | ||
1524 | exit_dput: | |
4e7506e4 | 1525 | dput(path.dentry); |
a15a3f6f | 1526 | if (nd->mnt != path.mnt) |
ba7a4c1a | 1527 | mntput(path.mnt); |
1da177e4 LT |
1528 | exit: |
1529 | path_release(nd); | |
1530 | return error; | |
1531 | ||
1532 | do_link: | |
1533 | error = -ELOOP; | |
1534 | if (flag & O_NOFOLLOW) | |
1535 | goto exit_dput; | |
1536 | /* | |
1537 | * This is subtle. Instead of calling do_follow_link() we do the | |
1538 | * thing by hands. The reason is that this way we have zero link_count | |
1539 | * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. | |
1540 | * After that we have the parent and last component, i.e. | |
1541 | * we are in the same situation as after the first path_walk(). | |
1542 | * Well, almost - if the last component is normal we get its copy | |
1543 | * stored in nd->last.name and we will have to putname() it when we | |
1544 | * are done. Procfs-like symlinks just set LAST_BIND. | |
1545 | */ | |
1546 | nd->flags |= LOOKUP_PARENT; | |
4e7506e4 | 1547 | error = security_inode_follow_link(path.dentry, nd); |
1da177e4 LT |
1548 | if (error) |
1549 | goto exit_dput; | |
cd4e91d3 | 1550 | error = __do_follow_link(&path, nd); |
1da177e4 LT |
1551 | if (error) |
1552 | return error; | |
1553 | nd->flags &= ~LOOKUP_PARENT; | |
d671d5e5 | 1554 | if (nd->last_type == LAST_BIND) |
1da177e4 | 1555 | goto ok; |
1da177e4 LT |
1556 | error = -EISDIR; |
1557 | if (nd->last_type != LAST_NORM) | |
1558 | goto exit; | |
1559 | if (nd->last.name[nd->last.len]) { | |
1560 | putname(nd->last.name); | |
1561 | goto exit; | |
1562 | } | |
1563 | error = -ELOOP; | |
1564 | if (count++==32) { | |
1565 | putname(nd->last.name); | |
1566 | goto exit; | |
1567 | } | |
1568 | dir = nd->dentry; | |
1569 | down(&dir->d_inode->i_sem); | |
4e7506e4 | 1570 | path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); |
d671d5e5 | 1571 | path.mnt = nd->mnt; |
1da177e4 LT |
1572 | putname(nd->last.name); |
1573 | goto do_last; | |
1574 | } | |
1575 | ||
1576 | /** | |
1577 | * lookup_create - lookup a dentry, creating it if it doesn't exist | |
1578 | * @nd: nameidata info | |
1579 | * @is_dir: directory flag | |
1580 | * | |
1581 | * Simple function to lookup and return a dentry and create it | |
1582 | * if it doesn't exist. Is SMP-safe. | |
c663e5d8 CH |
1583 | * |
1584 | * Returns with nd->dentry->d_inode->i_sem locked. | |
1da177e4 LT |
1585 | */ |
1586 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) | |
1587 | { | |
c663e5d8 | 1588 | struct dentry *dentry = ERR_PTR(-EEXIST); |
1da177e4 LT |
1589 | |
1590 | down(&nd->dentry->d_inode->i_sem); | |
c663e5d8 CH |
1591 | /* |
1592 | * Yucky last component or no last component at all? | |
1593 | * (foo/., foo/.., /////) | |
1594 | */ | |
1da177e4 LT |
1595 | if (nd->last_type != LAST_NORM) |
1596 | goto fail; | |
1597 | nd->flags &= ~LOOKUP_PARENT; | |
c663e5d8 CH |
1598 | |
1599 | /* | |
1600 | * Do the final lookup. | |
1601 | */ | |
1da177e4 LT |
1602 | dentry = lookup_hash(&nd->last, nd->dentry); |
1603 | if (IS_ERR(dentry)) | |
1604 | goto fail; | |
c663e5d8 CH |
1605 | |
1606 | /* | |
1607 | * Special case - lookup gave negative, but... we had foo/bar/ | |
1608 | * From the vfs_mknod() POV we just have a negative dentry - | |
1609 | * all is fine. Let's be bastards - you had / on the end, you've | |
1610 | * been asking for (non-existent) directory. -ENOENT for you. | |
1611 | */ | |
1da177e4 LT |
1612 | if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) |
1613 | goto enoent; | |
1614 | return dentry; | |
1615 | enoent: | |
1616 | dput(dentry); | |
1617 | dentry = ERR_PTR(-ENOENT); | |
1618 | fail: | |
1619 | return dentry; | |
1620 | } | |
f81a0bff | 1621 | EXPORT_SYMBOL_GPL(lookup_create); |
1da177e4 LT |
1622 | |
1623 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
1624 | { | |
1625 | int error = may_create(dir, dentry, NULL); | |
1626 | ||
1627 | if (error) | |
1628 | return error; | |
1629 | ||
1630 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) | |
1631 | return -EPERM; | |
1632 | ||
1633 | if (!dir->i_op || !dir->i_op->mknod) | |
1634 | return -EPERM; | |
1635 | ||
1636 | error = security_inode_mknod(dir, dentry, mode, dev); | |
1637 | if (error) | |
1638 | return error; | |
1639 | ||
1640 | DQUOT_INIT(dir); | |
1641 | error = dir->i_op->mknod(dir, dentry, mode, dev); | |
1642 | if (!error) { | |
0eeca283 | 1643 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
1644 | security_inode_post_mknod(dir, dentry, mode, dev); |
1645 | } | |
1646 | return error; | |
1647 | } | |
1648 | ||
1649 | asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev) | |
1650 | { | |
1651 | int error = 0; | |
1652 | char * tmp; | |
1653 | struct dentry * dentry; | |
1654 | struct nameidata nd; | |
1655 | ||
1656 | if (S_ISDIR(mode)) | |
1657 | return -EPERM; | |
1658 | tmp = getname(filename); | |
1659 | if (IS_ERR(tmp)) | |
1660 | return PTR_ERR(tmp); | |
1661 | ||
1662 | error = path_lookup(tmp, LOOKUP_PARENT, &nd); | |
1663 | if (error) | |
1664 | goto out; | |
1665 | dentry = lookup_create(&nd, 0); | |
1666 | error = PTR_ERR(dentry); | |
1667 | ||
1668 | if (!IS_POSIXACL(nd.dentry->d_inode)) | |
1669 | mode &= ~current->fs->umask; | |
1670 | if (!IS_ERR(dentry)) { | |
1671 | switch (mode & S_IFMT) { | |
1672 | case 0: case S_IFREG: | |
1673 | error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd); | |
1674 | break; | |
1675 | case S_IFCHR: case S_IFBLK: | |
1676 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode, | |
1677 | new_decode_dev(dev)); | |
1678 | break; | |
1679 | case S_IFIFO: case S_IFSOCK: | |
1680 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0); | |
1681 | break; | |
1682 | case S_IFDIR: | |
1683 | error = -EPERM; | |
1684 | break; | |
1685 | default: | |
1686 | error = -EINVAL; | |
1687 | } | |
1688 | dput(dentry); | |
1689 | } | |
1690 | up(&nd.dentry->d_inode->i_sem); | |
1691 | path_release(&nd); | |
1692 | out: | |
1693 | putname(tmp); | |
1694 | ||
1695 | return error; | |
1696 | } | |
1697 | ||
1698 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
1699 | { | |
1700 | int error = may_create(dir, dentry, NULL); | |
1701 | ||
1702 | if (error) | |
1703 | return error; | |
1704 | ||
1705 | if (!dir->i_op || !dir->i_op->mkdir) | |
1706 | return -EPERM; | |
1707 | ||
1708 | mode &= (S_IRWXUGO|S_ISVTX); | |
1709 | error = security_inode_mkdir(dir, dentry, mode); | |
1710 | if (error) | |
1711 | return error; | |
1712 | ||
1713 | DQUOT_INIT(dir); | |
1714 | error = dir->i_op->mkdir(dir, dentry, mode); | |
1715 | if (!error) { | |
0eeca283 | 1716 | fsnotify_mkdir(dir, dentry->d_name.name); |
1da177e4 LT |
1717 | security_inode_post_mkdir(dir,dentry, mode); |
1718 | } | |
1719 | return error; | |
1720 | } | |
1721 | ||
1722 | asmlinkage long sys_mkdir(const char __user * pathname, int mode) | |
1723 | { | |
1724 | int error = 0; | |
1725 | char * tmp; | |
1726 | ||
1727 | tmp = getname(pathname); | |
1728 | error = PTR_ERR(tmp); | |
1729 | if (!IS_ERR(tmp)) { | |
1730 | struct dentry *dentry; | |
1731 | struct nameidata nd; | |
1732 | ||
1733 | error = path_lookup(tmp, LOOKUP_PARENT, &nd); | |
1734 | if (error) | |
1735 | goto out; | |
1736 | dentry = lookup_create(&nd, 1); | |
1737 | error = PTR_ERR(dentry); | |
1738 | if (!IS_ERR(dentry)) { | |
1739 | if (!IS_POSIXACL(nd.dentry->d_inode)) | |
1740 | mode &= ~current->fs->umask; | |
1741 | error = vfs_mkdir(nd.dentry->d_inode, dentry, mode); | |
1742 | dput(dentry); | |
1743 | } | |
1744 | up(&nd.dentry->d_inode->i_sem); | |
1745 | path_release(&nd); | |
1746 | out: | |
1747 | putname(tmp); | |
1748 | } | |
1749 | ||
1750 | return error; | |
1751 | } | |
1752 | ||
1753 | /* | |
1754 | * We try to drop the dentry early: we should have | |
1755 | * a usage count of 2 if we're the only user of this | |
1756 | * dentry, and if that is true (possibly after pruning | |
1757 | * the dcache), then we drop the dentry now. | |
1758 | * | |
1759 | * A low-level filesystem can, if it choses, legally | |
1760 | * do a | |
1761 | * | |
1762 | * if (!d_unhashed(dentry)) | |
1763 | * return -EBUSY; | |
1764 | * | |
1765 | * if it cannot handle the case of removing a directory | |
1766 | * that is still in use by something else.. | |
1767 | */ | |
1768 | void dentry_unhash(struct dentry *dentry) | |
1769 | { | |
1770 | dget(dentry); | |
1771 | if (atomic_read(&dentry->d_count)) | |
1772 | shrink_dcache_parent(dentry); | |
1773 | spin_lock(&dcache_lock); | |
1774 | spin_lock(&dentry->d_lock); | |
1775 | if (atomic_read(&dentry->d_count) == 2) | |
1776 | __d_drop(dentry); | |
1777 | spin_unlock(&dentry->d_lock); | |
1778 | spin_unlock(&dcache_lock); | |
1779 | } | |
1780 | ||
1781 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
1782 | { | |
1783 | int error = may_delete(dir, dentry, 1); | |
1784 | ||
1785 | if (error) | |
1786 | return error; | |
1787 | ||
1788 | if (!dir->i_op || !dir->i_op->rmdir) | |
1789 | return -EPERM; | |
1790 | ||
1791 | DQUOT_INIT(dir); | |
1792 | ||
1793 | down(&dentry->d_inode->i_sem); | |
1794 | dentry_unhash(dentry); | |
1795 | if (d_mountpoint(dentry)) | |
1796 | error = -EBUSY; | |
1797 | else { | |
1798 | error = security_inode_rmdir(dir, dentry); | |
1799 | if (!error) { | |
1800 | error = dir->i_op->rmdir(dir, dentry); | |
1801 | if (!error) | |
1802 | dentry->d_inode->i_flags |= S_DEAD; | |
1803 | } | |
1804 | } | |
1805 | up(&dentry->d_inode->i_sem); | |
1806 | if (!error) { | |
1da177e4 LT |
1807 | d_delete(dentry); |
1808 | } | |
1809 | dput(dentry); | |
1810 | ||
1811 | return error; | |
1812 | } | |
1813 | ||
1814 | asmlinkage long sys_rmdir(const char __user * pathname) | |
1815 | { | |
1816 | int error = 0; | |
1817 | char * name; | |
1818 | struct dentry *dentry; | |
1819 | struct nameidata nd; | |
1820 | ||
1821 | name = getname(pathname); | |
1822 | if(IS_ERR(name)) | |
1823 | return PTR_ERR(name); | |
1824 | ||
1825 | error = path_lookup(name, LOOKUP_PARENT, &nd); | |
1826 | if (error) | |
1827 | goto exit; | |
1828 | ||
1829 | switch(nd.last_type) { | |
1830 | case LAST_DOTDOT: | |
1831 | error = -ENOTEMPTY; | |
1832 | goto exit1; | |
1833 | case LAST_DOT: | |
1834 | error = -EINVAL; | |
1835 | goto exit1; | |
1836 | case LAST_ROOT: | |
1837 | error = -EBUSY; | |
1838 | goto exit1; | |
1839 | } | |
1840 | down(&nd.dentry->d_inode->i_sem); | |
1841 | dentry = lookup_hash(&nd.last, nd.dentry); | |
1842 | error = PTR_ERR(dentry); | |
1843 | if (!IS_ERR(dentry)) { | |
1844 | error = vfs_rmdir(nd.dentry->d_inode, dentry); | |
1845 | dput(dentry); | |
1846 | } | |
1847 | up(&nd.dentry->d_inode->i_sem); | |
1848 | exit1: | |
1849 | path_release(&nd); | |
1850 | exit: | |
1851 | putname(name); | |
1852 | return error; | |
1853 | } | |
1854 | ||
1855 | int vfs_unlink(struct inode *dir, struct dentry *dentry) | |
1856 | { | |
1857 | int error = may_delete(dir, dentry, 0); | |
1858 | ||
1859 | if (error) | |
1860 | return error; | |
1861 | ||
1862 | if (!dir->i_op || !dir->i_op->unlink) | |
1863 | return -EPERM; | |
1864 | ||
1865 | DQUOT_INIT(dir); | |
1866 | ||
1867 | down(&dentry->d_inode->i_sem); | |
1868 | if (d_mountpoint(dentry)) | |
1869 | error = -EBUSY; | |
1870 | else { | |
1871 | error = security_inode_unlink(dir, dentry); | |
1872 | if (!error) | |
1873 | error = dir->i_op->unlink(dir, dentry); | |
1874 | } | |
1875 | up(&dentry->d_inode->i_sem); | |
1876 | ||
1877 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
1878 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
e234f35c | 1879 | d_delete(dentry); |
1da177e4 | 1880 | } |
0eeca283 | 1881 | |
1da177e4 LT |
1882 | return error; |
1883 | } | |
1884 | ||
1885 | /* | |
1886 | * Make sure that the actual truncation of the file will occur outside its | |
1887 | * directory's i_sem. Truncate can take a long time if there is a lot of | |
1888 | * writeout happening, and we don't want to prevent access to the directory | |
1889 | * while waiting on the I/O. | |
1890 | */ | |
1891 | asmlinkage long sys_unlink(const char __user * pathname) | |
1892 | { | |
1893 | int error = 0; | |
1894 | char * name; | |
1895 | struct dentry *dentry; | |
1896 | struct nameidata nd; | |
1897 | struct inode *inode = NULL; | |
1898 | ||
1899 | name = getname(pathname); | |
1900 | if(IS_ERR(name)) | |
1901 | return PTR_ERR(name); | |
1902 | ||
1903 | error = path_lookup(name, LOOKUP_PARENT, &nd); | |
1904 | if (error) | |
1905 | goto exit; | |
1906 | error = -EISDIR; | |
1907 | if (nd.last_type != LAST_NORM) | |
1908 | goto exit1; | |
1909 | down(&nd.dentry->d_inode->i_sem); | |
1910 | dentry = lookup_hash(&nd.last, nd.dentry); | |
1911 | error = PTR_ERR(dentry); | |
1912 | if (!IS_ERR(dentry)) { | |
1913 | /* Why not before? Because we want correct error value */ | |
1914 | if (nd.last.name[nd.last.len]) | |
1915 | goto slashes; | |
1916 | inode = dentry->d_inode; | |
1917 | if (inode) | |
1918 | atomic_inc(&inode->i_count); | |
1919 | error = vfs_unlink(nd.dentry->d_inode, dentry); | |
1920 | exit2: | |
1921 | dput(dentry); | |
1922 | } | |
1923 | up(&nd.dentry->d_inode->i_sem); | |
1924 | if (inode) | |
1925 | iput(inode); /* truncate the inode here */ | |
1926 | exit1: | |
1927 | path_release(&nd); | |
1928 | exit: | |
1929 | putname(name); | |
1930 | return error; | |
1931 | ||
1932 | slashes: | |
1933 | error = !dentry->d_inode ? -ENOENT : | |
1934 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
1935 | goto exit2; | |
1936 | } | |
1937 | ||
1938 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) | |
1939 | { | |
1940 | int error = may_create(dir, dentry, NULL); | |
1941 | ||
1942 | if (error) | |
1943 | return error; | |
1944 | ||
1945 | if (!dir->i_op || !dir->i_op->symlink) | |
1946 | return -EPERM; | |
1947 | ||
1948 | error = security_inode_symlink(dir, dentry, oldname); | |
1949 | if (error) | |
1950 | return error; | |
1951 | ||
1952 | DQUOT_INIT(dir); | |
1953 | error = dir->i_op->symlink(dir, dentry, oldname); | |
1954 | if (!error) { | |
0eeca283 | 1955 | fsnotify_create(dir, dentry->d_name.name); |
1da177e4 LT |
1956 | security_inode_post_symlink(dir, dentry, oldname); |
1957 | } | |
1958 | return error; | |
1959 | } | |
1960 | ||
1961 | asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname) | |
1962 | { | |
1963 | int error = 0; | |
1964 | char * from; | |
1965 | char * to; | |
1966 | ||
1967 | from = getname(oldname); | |
1968 | if(IS_ERR(from)) | |
1969 | return PTR_ERR(from); | |
1970 | to = getname(newname); | |
1971 | error = PTR_ERR(to); | |
1972 | if (!IS_ERR(to)) { | |
1973 | struct dentry *dentry; | |
1974 | struct nameidata nd; | |
1975 | ||
1976 | error = path_lookup(to, LOOKUP_PARENT, &nd); | |
1977 | if (error) | |
1978 | goto out; | |
1979 | dentry = lookup_create(&nd, 0); | |
1980 | error = PTR_ERR(dentry); | |
1981 | if (!IS_ERR(dentry)) { | |
1982 | error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO); | |
1983 | dput(dentry); | |
1984 | } | |
1985 | up(&nd.dentry->d_inode->i_sem); | |
1986 | path_release(&nd); | |
1987 | out: | |
1988 | putname(to); | |
1989 | } | |
1990 | putname(from); | |
1991 | return error; | |
1992 | } | |
1993 | ||
1994 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) | |
1995 | { | |
1996 | struct inode *inode = old_dentry->d_inode; | |
1997 | int error; | |
1998 | ||
1999 | if (!inode) | |
2000 | return -ENOENT; | |
2001 | ||
2002 | error = may_create(dir, new_dentry, NULL); | |
2003 | if (error) | |
2004 | return error; | |
2005 | ||
2006 | if (dir->i_sb != inode->i_sb) | |
2007 | return -EXDEV; | |
2008 | ||
2009 | /* | |
2010 | * A link to an append-only or immutable file cannot be created. | |
2011 | */ | |
2012 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2013 | return -EPERM; | |
2014 | if (!dir->i_op || !dir->i_op->link) | |
2015 | return -EPERM; | |
2016 | if (S_ISDIR(old_dentry->d_inode->i_mode)) | |
2017 | return -EPERM; | |
2018 | ||
2019 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2020 | if (error) | |
2021 | return error; | |
2022 | ||
2023 | down(&old_dentry->d_inode->i_sem); | |
2024 | DQUOT_INIT(dir); | |
2025 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
2026 | up(&old_dentry->d_inode->i_sem); | |
2027 | if (!error) { | |
0eeca283 | 2028 | fsnotify_create(dir, new_dentry->d_name.name); |
1da177e4 LT |
2029 | security_inode_post_link(old_dentry, dir, new_dentry); |
2030 | } | |
2031 | return error; | |
2032 | } | |
2033 | ||
2034 | /* | |
2035 | * Hardlinks are often used in delicate situations. We avoid | |
2036 | * security-related surprises by not following symlinks on the | |
2037 | * newname. --KAB | |
2038 | * | |
2039 | * We don't follow them on the oldname either to be compatible | |
2040 | * with linux 2.0, and to avoid hard-linking to directories | |
2041 | * and other special files. --ADM | |
2042 | */ | |
2043 | asmlinkage long sys_link(const char __user * oldname, const char __user * newname) | |
2044 | { | |
2045 | struct dentry *new_dentry; | |
2046 | struct nameidata nd, old_nd; | |
2047 | int error; | |
2048 | char * to; | |
2049 | ||
2050 | to = getname(newname); | |
2051 | if (IS_ERR(to)) | |
2052 | return PTR_ERR(to); | |
2053 | ||
2054 | error = __user_walk(oldname, 0, &old_nd); | |
2055 | if (error) | |
2056 | goto exit; | |
2057 | error = path_lookup(to, LOOKUP_PARENT, &nd); | |
2058 | if (error) | |
2059 | goto out; | |
2060 | error = -EXDEV; | |
2061 | if (old_nd.mnt != nd.mnt) | |
2062 | goto out_release; | |
2063 | new_dentry = lookup_create(&nd, 0); | |
2064 | error = PTR_ERR(new_dentry); | |
2065 | if (!IS_ERR(new_dentry)) { | |
2066 | error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry); | |
2067 | dput(new_dentry); | |
2068 | } | |
2069 | up(&nd.dentry->d_inode->i_sem); | |
2070 | out_release: | |
2071 | path_release(&nd); | |
2072 | out: | |
2073 | path_release(&old_nd); | |
2074 | exit: | |
2075 | putname(to); | |
2076 | ||
2077 | return error; | |
2078 | } | |
2079 | ||
2080 | /* | |
2081 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2082 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2083 | * Problems: | |
2084 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2085 | * b) race potential - two innocent renames can create a loop together. | |
2086 | * That's where 4.4 screws up. Current fix: serialization on | |
2087 | * sb->s_vfs_rename_sem. We might be more accurate, but that's another | |
2088 | * story. | |
2089 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
2090 | * And that - after we got ->i_sem on parents (until then we don't know | |
2091 | * whether the target exists). Solution: try to be smart with locking | |
2092 | * order for inodes. We rely on the fact that tree topology may change | |
2093 | * only under ->s_vfs_rename_sem _and_ that parent of the object we | |
2094 | * move will be locked. Thus we can rank directories by the tree | |
2095 | * (ancestors first) and rank all non-directories after them. | |
2096 | * That works since everybody except rename does "lock parent, lookup, | |
2097 | * lock child" and rename is under ->s_vfs_rename_sem. | |
2098 | * HOWEVER, it relies on the assumption that any object with ->lookup() | |
2099 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2100 | * we'd better make sure that there's no link(2) for them. | |
2101 | * d) some filesystems don't support opened-but-unlinked directories, | |
2102 | * either because of layout or because they are not ready to deal with | |
2103 | * all cases correctly. The latter will be fixed (taking this sort of | |
2104 | * stuff into VFS), but the former is not going away. Solution: the same | |
2105 | * trick as in rmdir(). | |
2106 | * e) conversion from fhandle to dentry may come in the wrong moment - when | |
2107 | * we are removing the target. Solution: we will have to grab ->i_sem | |
2108 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on | |
2109 | * ->i_sem on parents, which works but leads to some truely excessive | |
2110 | * locking]. | |
2111 | */ | |
75c96f85 AB |
2112 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2113 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2114 | { |
2115 | int error = 0; | |
2116 | struct inode *target; | |
2117 | ||
2118 | /* | |
2119 | * If we are going to change the parent - check write permissions, | |
2120 | * we'll need to flip '..'. | |
2121 | */ | |
2122 | if (new_dir != old_dir) { | |
2123 | error = permission(old_dentry->d_inode, MAY_WRITE, NULL); | |
2124 | if (error) | |
2125 | return error; | |
2126 | } | |
2127 | ||
2128 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2129 | if (error) | |
2130 | return error; | |
2131 | ||
2132 | target = new_dentry->d_inode; | |
2133 | if (target) { | |
2134 | down(&target->i_sem); | |
2135 | dentry_unhash(new_dentry); | |
2136 | } | |
2137 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2138 | error = -EBUSY; | |
2139 | else | |
2140 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2141 | if (target) { | |
2142 | if (!error) | |
2143 | target->i_flags |= S_DEAD; | |
2144 | up(&target->i_sem); | |
2145 | if (d_unhashed(new_dentry)) | |
2146 | d_rehash(new_dentry); | |
2147 | dput(new_dentry); | |
2148 | } | |
2149 | if (!error) { | |
2150 | d_move(old_dentry,new_dentry); | |
2151 | security_inode_post_rename(old_dir, old_dentry, | |
2152 | new_dir, new_dentry); | |
2153 | } | |
2154 | return error; | |
2155 | } | |
2156 | ||
75c96f85 AB |
2157 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2158 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2159 | { |
2160 | struct inode *target; | |
2161 | int error; | |
2162 | ||
2163 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2164 | if (error) | |
2165 | return error; | |
2166 | ||
2167 | dget(new_dentry); | |
2168 | target = new_dentry->d_inode; | |
2169 | if (target) | |
2170 | down(&target->i_sem); | |
2171 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2172 | error = -EBUSY; | |
2173 | else | |
2174 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2175 | if (!error) { | |
2176 | /* The following d_move() should become unconditional */ | |
2177 | if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME)) | |
2178 | d_move(old_dentry, new_dentry); | |
2179 | security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2180 | } | |
2181 | if (target) | |
2182 | up(&target->i_sem); | |
2183 | dput(new_dentry); | |
2184 | return error; | |
2185 | } | |
2186 | ||
2187 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2188 | struct inode *new_dir, struct dentry *new_dentry) | |
2189 | { | |
2190 | int error; | |
2191 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
0eeca283 | 2192 | const char *old_name; |
1da177e4 LT |
2193 | |
2194 | if (old_dentry->d_inode == new_dentry->d_inode) | |
2195 | return 0; | |
2196 | ||
2197 | error = may_delete(old_dir, old_dentry, is_dir); | |
2198 | if (error) | |
2199 | return error; | |
2200 | ||
2201 | if (!new_dentry->d_inode) | |
2202 | error = may_create(new_dir, new_dentry, NULL); | |
2203 | else | |
2204 | error = may_delete(new_dir, new_dentry, is_dir); | |
2205 | if (error) | |
2206 | return error; | |
2207 | ||
2208 | if (!old_dir->i_op || !old_dir->i_op->rename) | |
2209 | return -EPERM; | |
2210 | ||
2211 | DQUOT_INIT(old_dir); | |
2212 | DQUOT_INIT(new_dir); | |
2213 | ||
0eeca283 RL |
2214 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
2215 | ||
1da177e4 LT |
2216 | if (is_dir) |
2217 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
2218 | else | |
2219 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
2220 | if (!error) { | |
0eeca283 | 2221 | const char *new_name = old_dentry->d_name.name; |
89204c40 JM |
2222 | fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, |
2223 | new_dentry->d_inode, old_dentry->d_inode); | |
1da177e4 | 2224 | } |
0eeca283 RL |
2225 | fsnotify_oldname_free(old_name); |
2226 | ||
1da177e4 LT |
2227 | return error; |
2228 | } | |
2229 | ||
2230 | static inline int do_rename(const char * oldname, const char * newname) | |
2231 | { | |
2232 | int error = 0; | |
2233 | struct dentry * old_dir, * new_dir; | |
2234 | struct dentry * old_dentry, *new_dentry; | |
2235 | struct dentry * trap; | |
2236 | struct nameidata oldnd, newnd; | |
2237 | ||
2238 | error = path_lookup(oldname, LOOKUP_PARENT, &oldnd); | |
2239 | if (error) | |
2240 | goto exit; | |
2241 | ||
2242 | error = path_lookup(newname, LOOKUP_PARENT, &newnd); | |
2243 | if (error) | |
2244 | goto exit1; | |
2245 | ||
2246 | error = -EXDEV; | |
2247 | if (oldnd.mnt != newnd.mnt) | |
2248 | goto exit2; | |
2249 | ||
2250 | old_dir = oldnd.dentry; | |
2251 | error = -EBUSY; | |
2252 | if (oldnd.last_type != LAST_NORM) | |
2253 | goto exit2; | |
2254 | ||
2255 | new_dir = newnd.dentry; | |
2256 | if (newnd.last_type != LAST_NORM) | |
2257 | goto exit2; | |
2258 | ||
2259 | trap = lock_rename(new_dir, old_dir); | |
2260 | ||
2261 | old_dentry = lookup_hash(&oldnd.last, old_dir); | |
2262 | error = PTR_ERR(old_dentry); | |
2263 | if (IS_ERR(old_dentry)) | |
2264 | goto exit3; | |
2265 | /* source must exist */ | |
2266 | error = -ENOENT; | |
2267 | if (!old_dentry->d_inode) | |
2268 | goto exit4; | |
2269 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
2270 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
2271 | error = -ENOTDIR; | |
2272 | if (oldnd.last.name[oldnd.last.len]) | |
2273 | goto exit4; | |
2274 | if (newnd.last.name[newnd.last.len]) | |
2275 | goto exit4; | |
2276 | } | |
2277 | /* source should not be ancestor of target */ | |
2278 | error = -EINVAL; | |
2279 | if (old_dentry == trap) | |
2280 | goto exit4; | |
2281 | new_dentry = lookup_hash(&newnd.last, new_dir); | |
2282 | error = PTR_ERR(new_dentry); | |
2283 | if (IS_ERR(new_dentry)) | |
2284 | goto exit4; | |
2285 | /* target should not be an ancestor of source */ | |
2286 | error = -ENOTEMPTY; | |
2287 | if (new_dentry == trap) | |
2288 | goto exit5; | |
2289 | ||
2290 | error = vfs_rename(old_dir->d_inode, old_dentry, | |
2291 | new_dir->d_inode, new_dentry); | |
2292 | exit5: | |
2293 | dput(new_dentry); | |
2294 | exit4: | |
2295 | dput(old_dentry); | |
2296 | exit3: | |
2297 | unlock_rename(new_dir, old_dir); | |
2298 | exit2: | |
2299 | path_release(&newnd); | |
2300 | exit1: | |
2301 | path_release(&oldnd); | |
2302 | exit: | |
2303 | return error; | |
2304 | } | |
2305 | ||
2306 | asmlinkage long sys_rename(const char __user * oldname, const char __user * newname) | |
2307 | { | |
2308 | int error; | |
2309 | char * from; | |
2310 | char * to; | |
2311 | ||
2312 | from = getname(oldname); | |
2313 | if(IS_ERR(from)) | |
2314 | return PTR_ERR(from); | |
2315 | to = getname(newname); | |
2316 | error = PTR_ERR(to); | |
2317 | if (!IS_ERR(to)) { | |
2318 | error = do_rename(from,to); | |
2319 | putname(to); | |
2320 | } | |
2321 | putname(from); | |
2322 | return error; | |
2323 | } | |
2324 | ||
2325 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) | |
2326 | { | |
2327 | int len; | |
2328 | ||
2329 | len = PTR_ERR(link); | |
2330 | if (IS_ERR(link)) | |
2331 | goto out; | |
2332 | ||
2333 | len = strlen(link); | |
2334 | if (len > (unsigned) buflen) | |
2335 | len = buflen; | |
2336 | if (copy_to_user(buffer, link, len)) | |
2337 | len = -EFAULT; | |
2338 | out: | |
2339 | return len; | |
2340 | } | |
2341 | ||
2342 | /* | |
2343 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
2344 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
2345 | * using) it for any given inode is up to filesystem. | |
2346 | */ | |
2347 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2348 | { | |
2349 | struct nameidata nd; | |
cc314eef LT |
2350 | void *cookie; |
2351 | ||
1da177e4 | 2352 | nd.depth = 0; |
cc314eef LT |
2353 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
2354 | if (!IS_ERR(cookie)) { | |
2355 | int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
1da177e4 | 2356 | if (dentry->d_inode->i_op->put_link) |
cc314eef LT |
2357 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); |
2358 | cookie = ERR_PTR(res); | |
1da177e4 | 2359 | } |
cc314eef | 2360 | return PTR_ERR(cookie); |
1da177e4 LT |
2361 | } |
2362 | ||
2363 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
2364 | { | |
2365 | return __vfs_follow_link(nd, link); | |
2366 | } | |
2367 | ||
2368 | /* get the link contents into pagecache */ | |
2369 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
2370 | { | |
2371 | struct page * page; | |
2372 | struct address_space *mapping = dentry->d_inode->i_mapping; | |
2373 | page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage, | |
2374 | NULL); | |
2375 | if (IS_ERR(page)) | |
2376 | goto sync_fail; | |
2377 | wait_on_page_locked(page); | |
2378 | if (!PageUptodate(page)) | |
2379 | goto async_fail; | |
2380 | *ppage = page; | |
2381 | return kmap(page); | |
2382 | ||
2383 | async_fail: | |
2384 | page_cache_release(page); | |
2385 | return ERR_PTR(-EIO); | |
2386 | ||
2387 | sync_fail: | |
2388 | return (char*)page; | |
2389 | } | |
2390 | ||
2391 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2392 | { | |
2393 | struct page *page = NULL; | |
2394 | char *s = page_getlink(dentry, &page); | |
2395 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
2396 | if (page) { | |
2397 | kunmap(page); | |
2398 | page_cache_release(page); | |
2399 | } | |
2400 | return res; | |
2401 | } | |
2402 | ||
cc314eef | 2403 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 2404 | { |
cc314eef | 2405 | struct page *page = NULL; |
1da177e4 | 2406 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 2407 | return page; |
1da177e4 LT |
2408 | } |
2409 | ||
cc314eef | 2410 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 2411 | { |
cc314eef LT |
2412 | struct page *page = cookie; |
2413 | ||
2414 | if (page) { | |
1da177e4 LT |
2415 | kunmap(page); |
2416 | page_cache_release(page); | |
1da177e4 LT |
2417 | } |
2418 | } | |
2419 | ||
2420 | int page_symlink(struct inode *inode, const char *symname, int len) | |
2421 | { | |
2422 | struct address_space *mapping = inode->i_mapping; | |
2423 | struct page *page = grab_cache_page(mapping, 0); | |
2424 | int err = -ENOMEM; | |
2425 | char *kaddr; | |
2426 | ||
2427 | if (!page) | |
2428 | goto fail; | |
2429 | err = mapping->a_ops->prepare_write(NULL, page, 0, len-1); | |
2430 | if (err) | |
2431 | goto fail_map; | |
2432 | kaddr = kmap_atomic(page, KM_USER0); | |
2433 | memcpy(kaddr, symname, len-1); | |
2434 | kunmap_atomic(kaddr, KM_USER0); | |
2435 | mapping->a_ops->commit_write(NULL, page, 0, len-1); | |
2436 | /* | |
2437 | * Notice that we are _not_ going to block here - end of page is | |
2438 | * unmapped, so this will only try to map the rest of page, see | |
2439 | * that it is unmapped (typically even will not look into inode - | |
2440 | * ->i_size will be enough for everything) and zero it out. | |
2441 | * OTOH it's obviously correct and should make the page up-to-date. | |
2442 | */ | |
2443 | if (!PageUptodate(page)) { | |
2444 | err = mapping->a_ops->readpage(NULL, page); | |
2445 | wait_on_page_locked(page); | |
2446 | } else { | |
2447 | unlock_page(page); | |
2448 | } | |
2449 | page_cache_release(page); | |
2450 | if (err < 0) | |
2451 | goto fail; | |
2452 | mark_inode_dirty(inode); | |
2453 | return 0; | |
2454 | fail_map: | |
2455 | unlock_page(page); | |
2456 | page_cache_release(page); | |
2457 | fail: | |
2458 | return err; | |
2459 | } | |
2460 | ||
2461 | struct inode_operations page_symlink_inode_operations = { | |
2462 | .readlink = generic_readlink, | |
2463 | .follow_link = page_follow_link_light, | |
2464 | .put_link = page_put_link, | |
2465 | }; | |
2466 | ||
2467 | EXPORT_SYMBOL(__user_walk); | |
2468 | EXPORT_SYMBOL(follow_down); | |
2469 | EXPORT_SYMBOL(follow_up); | |
2470 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
2471 | EXPORT_SYMBOL(getname); | |
2472 | EXPORT_SYMBOL(lock_rename); | |
2473 | EXPORT_SYMBOL(lookup_hash); | |
2474 | EXPORT_SYMBOL(lookup_one_len); | |
2475 | EXPORT_SYMBOL(page_follow_link_light); | |
2476 | EXPORT_SYMBOL(page_put_link); | |
2477 | EXPORT_SYMBOL(page_readlink); | |
2478 | EXPORT_SYMBOL(page_symlink); | |
2479 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
2480 | EXPORT_SYMBOL(path_lookup); | |
2481 | EXPORT_SYMBOL(path_release); | |
2482 | EXPORT_SYMBOL(path_walk); | |
2483 | EXPORT_SYMBOL(permission); | |
2484 | EXPORT_SYMBOL(unlock_rename); | |
2485 | EXPORT_SYMBOL(vfs_create); | |
2486 | EXPORT_SYMBOL(vfs_follow_link); | |
2487 | EXPORT_SYMBOL(vfs_link); | |
2488 | EXPORT_SYMBOL(vfs_mkdir); | |
2489 | EXPORT_SYMBOL(vfs_mknod); | |
2490 | EXPORT_SYMBOL(generic_permission); | |
2491 | EXPORT_SYMBOL(vfs_readlink); | |
2492 | EXPORT_SYMBOL(vfs_rename); | |
2493 | EXPORT_SYMBOL(vfs_rmdir); | |
2494 | EXPORT_SYMBOL(vfs_symlink); | |
2495 | EXPORT_SYMBOL(vfs_unlink); | |
2496 | EXPORT_SYMBOL(dentry_unhash); | |
2497 | EXPORT_SYMBOL(generic_readlink); |