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/personality.h> |
26 | #include <linux/security.h> | |
27 | #include <linux/syscalls.h> | |
28 | #include <linux/mount.h> | |
29 | #include <linux/audit.h> | |
16f7e0fe | 30 | #include <linux/capability.h> |
834f2a4a | 31 | #include <linux/file.h> |
5590ff0d | 32 | #include <linux/fcntl.h> |
08ce5f16 | 33 | #include <linux/device_cgroup.h> |
1da177e4 LT |
34 | #include <asm/namei.h> |
35 | #include <asm/uaccess.h> | |
36 | ||
37 | #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) | |
38 | ||
39 | /* [Feb-1997 T. Schoebel-Theuer] | |
40 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
41 | * were necessary because of omirr. The reason is that omirr needs | |
42 | * to know the _real_ pathname, not the user-supplied one, in case | |
43 | * of symlinks (and also when transname replacements occur). | |
44 | * | |
45 | * The new code replaces the old recursive symlink resolution with | |
46 | * an iterative one (in case of non-nested symlink chains). It does | |
47 | * this with calls to <fs>_follow_link(). | |
48 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
49 | * replaced with a single function lookup_dentry() that can handle all | |
50 | * the special cases of the former code. | |
51 | * | |
52 | * With the new dcache, the pathname is stored at each inode, at least as | |
53 | * long as the refcount of the inode is positive. As a side effect, the | |
54 | * size of the dcache depends on the inode cache and thus is dynamic. | |
55 | * | |
56 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
57 | * resolution to correspond with current state of the code. | |
58 | * | |
59 | * Note that the symlink resolution is not *completely* iterative. | |
60 | * There is still a significant amount of tail- and mid- recursion in | |
61 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
62 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
63 | * may return different results than <fs>_follow_link(). Many virtual | |
64 | * filesystems (including /proc) exhibit this behavior. | |
65 | */ | |
66 | ||
67 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
68 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
69 | * and the name already exists in form of a symlink, try to create the new | |
70 | * name indicated by the symlink. The old code always complained that the | |
71 | * name already exists, due to not following the symlink even if its target | |
72 | * is nonexistent. The new semantics affects also mknod() and link() when | |
73 | * the name is a symlink pointing to a non-existant name. | |
74 | * | |
75 | * I don't know which semantics is the right one, since I have no access | |
76 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
77 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
78 | * "old" one. Personally, I think the new semantics is much more logical. | |
79 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
80 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
81 | * and in the old Linux semantics. | |
82 | */ | |
83 | ||
84 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
85 | * semantics. See the comments in "open_namei" and "do_link" below. | |
86 | * | |
87 | * [10-Sep-98 Alan Modra] Another symlink change. | |
88 | */ | |
89 | ||
90 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
91 | * inside the path - always follow. | |
92 | * in the last component in creation/removal/renaming - never follow. | |
93 | * if LOOKUP_FOLLOW passed - follow. | |
94 | * if the pathname has trailing slashes - follow. | |
95 | * otherwise - don't follow. | |
96 | * (applied in that order). | |
97 | * | |
98 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
99 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
100 | * During the 2.4 we need to fix the userland stuff depending on it - | |
101 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
102 | * XEmacs seems to be relying on it... | |
103 | */ | |
104 | /* | |
105 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 106 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
107 | * any extra contention... |
108 | */ | |
109 | ||
a02f76c3 | 110 | static int __link_path_walk(const char *name, struct nameidata *nd); |
c4a7808f | 111 | |
1da177e4 LT |
112 | /* In order to reduce some races, while at the same time doing additional |
113 | * checking and hopefully speeding things up, we copy filenames to the | |
114 | * kernel data space before using them.. | |
115 | * | |
116 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
117 | * PATH_MAX includes the nul terminator --RR. | |
118 | */ | |
858119e1 | 119 | static int do_getname(const char __user *filename, char *page) |
1da177e4 LT |
120 | { |
121 | int retval; | |
122 | unsigned long len = PATH_MAX; | |
123 | ||
124 | if (!segment_eq(get_fs(), KERNEL_DS)) { | |
125 | if ((unsigned long) filename >= TASK_SIZE) | |
126 | return -EFAULT; | |
127 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) | |
128 | len = TASK_SIZE - (unsigned long) filename; | |
129 | } | |
130 | ||
131 | retval = strncpy_from_user(page, filename, len); | |
132 | if (retval > 0) { | |
133 | if (retval < len) | |
134 | return 0; | |
135 | return -ENAMETOOLONG; | |
136 | } else if (!retval) | |
137 | retval = -ENOENT; | |
138 | return retval; | |
139 | } | |
140 | ||
141 | char * getname(const char __user * filename) | |
142 | { | |
143 | char *tmp, *result; | |
144 | ||
145 | result = ERR_PTR(-ENOMEM); | |
146 | tmp = __getname(); | |
147 | if (tmp) { | |
148 | int retval = do_getname(filename, tmp); | |
149 | ||
150 | result = tmp; | |
151 | if (retval < 0) { | |
152 | __putname(tmp); | |
153 | result = ERR_PTR(retval); | |
154 | } | |
155 | } | |
156 | audit_getname(result); | |
157 | return result; | |
158 | } | |
159 | ||
160 | #ifdef CONFIG_AUDITSYSCALL | |
161 | void putname(const char *name) | |
162 | { | |
5ac3a9c2 | 163 | if (unlikely(!audit_dummy_context())) |
1da177e4 LT |
164 | audit_putname(name); |
165 | else | |
166 | __putname(name); | |
167 | } | |
168 | EXPORT_SYMBOL(putname); | |
169 | #endif | |
170 | ||
171 | ||
172 | /** | |
173 | * generic_permission - check for access rights on a Posix-like filesystem | |
174 | * @inode: inode to check access rights for | |
175 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
176 | * @check_acl: optional callback to check for Posix ACLs | |
177 | * | |
178 | * Used to check for read/write/execute permissions on a file. | |
179 | * We use "fsuid" for this, letting us set arbitrary permissions | |
180 | * for filesystem access without changing the "normal" uids which | |
181 | * are used for other things.. | |
182 | */ | |
183 | int generic_permission(struct inode *inode, int mask, | |
184 | int (*check_acl)(struct inode *inode, int mask)) | |
185 | { | |
186 | umode_t mode = inode->i_mode; | |
187 | ||
e6305c43 AV |
188 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
189 | ||
1da177e4 LT |
190 | if (current->fsuid == inode->i_uid) |
191 | mode >>= 6; | |
192 | else { | |
193 | if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { | |
194 | int error = check_acl(inode, mask); | |
195 | if (error == -EACCES) | |
196 | goto check_capabilities; | |
197 | else if (error != -EAGAIN) | |
198 | return error; | |
199 | } | |
200 | ||
201 | if (in_group_p(inode->i_gid)) | |
202 | mode >>= 3; | |
203 | } | |
204 | ||
205 | /* | |
206 | * If the DACs are ok we don't need any capability check. | |
207 | */ | |
e6305c43 | 208 | if ((mask & ~mode) == 0) |
1da177e4 LT |
209 | return 0; |
210 | ||
211 | check_capabilities: | |
212 | /* | |
213 | * Read/write DACs are always overridable. | |
214 | * Executable DACs are overridable if at least one exec bit is set. | |
215 | */ | |
216 | if (!(mask & MAY_EXEC) || | |
217 | (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) | |
218 | if (capable(CAP_DAC_OVERRIDE)) | |
219 | return 0; | |
220 | ||
221 | /* | |
222 | * Searching includes executable on directories, else just read. | |
223 | */ | |
224 | if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) | |
225 | if (capable(CAP_DAC_READ_SEARCH)) | |
226 | return 0; | |
227 | ||
228 | return -EACCES; | |
229 | } | |
230 | ||
231 | int permission(struct inode *inode, int mask, struct nameidata *nd) | |
232 | { | |
e6305c43 | 233 | int retval; |
c7eb2667 DH |
234 | struct vfsmount *mnt = NULL; |
235 | ||
236 | if (nd) | |
4ac91378 | 237 | mnt = nd->path.mnt; |
1da177e4 LT |
238 | |
239 | if (mask & MAY_WRITE) { | |
22590e41 | 240 | umode_t mode = inode->i_mode; |
1da177e4 LT |
241 | |
242 | /* | |
243 | * Nobody gets write access to a read-only fs. | |
244 | */ | |
245 | if (IS_RDONLY(inode) && | |
246 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
247 | return -EROFS; | |
248 | ||
249 | /* | |
250 | * Nobody gets write access to an immutable file. | |
251 | */ | |
252 | if (IS_IMMUTABLE(inode)) | |
253 | return -EACCES; | |
254 | } | |
255 | ||
22590e41 MS |
256 | if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) { |
257 | /* | |
258 | * MAY_EXEC on regular files is denied if the fs is mounted | |
259 | * with the "noexec" flag. | |
260 | */ | |
c7eb2667 | 261 | if (mnt && (mnt->mnt_flags & MNT_NOEXEC)) |
22590e41 MS |
262 | return -EACCES; |
263 | } | |
a343bb77 | 264 | |
1da177e4 | 265 | /* Ordinary permission routines do not understand MAY_APPEND. */ |
22590e41 | 266 | if (inode->i_op && inode->i_op->permission) { |
e6305c43 AV |
267 | int extra = 0; |
268 | if (nd) { | |
269 | if (nd->flags & LOOKUP_ACCESS) | |
270 | extra |= MAY_ACCESS; | |
271 | if (nd->flags & LOOKUP_CHDIR) | |
272 | extra |= MAY_CHDIR; | |
273 | if (nd->flags & LOOKUP_OPEN) | |
274 | extra |= MAY_OPEN; | |
275 | } | |
276 | retval = inode->i_op->permission(inode, mask | extra); | |
22590e41 MS |
277 | if (!retval) { |
278 | /* | |
279 | * Exec permission on a regular file is denied if none | |
280 | * of the execute bits are set. | |
281 | * | |
282 | * This check should be done by the ->permission() | |
283 | * method. | |
284 | */ | |
285 | if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) && | |
286 | !(inode->i_mode & S_IXUGO)) | |
287 | return -EACCES; | |
288 | } | |
289 | } else { | |
e6305c43 | 290 | retval = generic_permission(inode, mask, NULL); |
22590e41 | 291 | } |
1da177e4 LT |
292 | if (retval) |
293 | return retval; | |
294 | ||
08ce5f16 SH |
295 | retval = devcgroup_inode_permission(inode, mask); |
296 | if (retval) | |
297 | return retval; | |
298 | ||
e6305c43 AV |
299 | return security_inode_permission(inode, |
300 | mask & (MAY_READ|MAY_WRITE|MAY_EXEC), nd); | |
1da177e4 LT |
301 | } |
302 | ||
e4543edd CH |
303 | /** |
304 | * vfs_permission - check for access rights to a given path | |
305 | * @nd: lookup result that describes the path | |
306 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
307 | * | |
308 | * Used to check for read/write/execute permissions on a path. | |
309 | * We use "fsuid" for this, letting us set arbitrary permissions | |
310 | * for filesystem access without changing the "normal" uids which | |
311 | * are used for other things. | |
312 | */ | |
313 | int vfs_permission(struct nameidata *nd, int mask) | |
314 | { | |
4ac91378 | 315 | return permission(nd->path.dentry->d_inode, mask, nd); |
e4543edd CH |
316 | } |
317 | ||
8c744fb8 CH |
318 | /** |
319 | * file_permission - check for additional access rights to a given file | |
320 | * @file: file to check access rights for | |
321 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
322 | * | |
323 | * Used to check for read/write/execute permissions on an already opened | |
324 | * file. | |
325 | * | |
326 | * Note: | |
327 | * Do not use this function in new code. All access checks should | |
328 | * be done using vfs_permission(). | |
329 | */ | |
330 | int file_permission(struct file *file, int mask) | |
331 | { | |
0f7fc9e4 | 332 | return permission(file->f_path.dentry->d_inode, mask, NULL); |
8c744fb8 CH |
333 | } |
334 | ||
1da177e4 LT |
335 | /* |
336 | * get_write_access() gets write permission for a file. | |
337 | * put_write_access() releases this write permission. | |
338 | * This is used for regular files. | |
339 | * We cannot support write (and maybe mmap read-write shared) accesses and | |
340 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode | |
341 | * can have the following values: | |
342 | * 0: no writers, no VM_DENYWRITE mappings | |
343 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist | |
344 | * > 0: (i_writecount) users are writing to the file. | |
345 | * | |
346 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe | |
347 | * except for the cases where we don't hold i_writecount yet. Then we need to | |
348 | * use {get,deny}_write_access() - these functions check the sign and refuse | |
349 | * to do the change if sign is wrong. Exclusion between them is provided by | |
350 | * the inode->i_lock spinlock. | |
351 | */ | |
352 | ||
353 | int get_write_access(struct inode * inode) | |
354 | { | |
355 | spin_lock(&inode->i_lock); | |
356 | if (atomic_read(&inode->i_writecount) < 0) { | |
357 | spin_unlock(&inode->i_lock); | |
358 | return -ETXTBSY; | |
359 | } | |
360 | atomic_inc(&inode->i_writecount); | |
361 | spin_unlock(&inode->i_lock); | |
362 | ||
363 | return 0; | |
364 | } | |
365 | ||
366 | int deny_write_access(struct file * file) | |
367 | { | |
0f7fc9e4 | 368 | struct inode *inode = file->f_path.dentry->d_inode; |
1da177e4 LT |
369 | |
370 | spin_lock(&inode->i_lock); | |
371 | if (atomic_read(&inode->i_writecount) > 0) { | |
372 | spin_unlock(&inode->i_lock); | |
373 | return -ETXTBSY; | |
374 | } | |
375 | atomic_dec(&inode->i_writecount); | |
376 | spin_unlock(&inode->i_lock); | |
377 | ||
378 | return 0; | |
379 | } | |
380 | ||
5dd784d0 JB |
381 | /** |
382 | * path_get - get a reference to a path | |
383 | * @path: path to get the reference to | |
384 | * | |
385 | * Given a path increment the reference count to the dentry and the vfsmount. | |
386 | */ | |
387 | void path_get(struct path *path) | |
388 | { | |
389 | mntget(path->mnt); | |
390 | dget(path->dentry); | |
391 | } | |
392 | EXPORT_SYMBOL(path_get); | |
393 | ||
1d957f9b JB |
394 | /** |
395 | * path_put - put a reference to a path | |
396 | * @path: path to put the reference to | |
397 | * | |
398 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
399 | */ | |
400 | void path_put(struct path *path) | |
1da177e4 | 401 | { |
1d957f9b JB |
402 | dput(path->dentry); |
403 | mntput(path->mnt); | |
1da177e4 | 404 | } |
1d957f9b | 405 | EXPORT_SYMBOL(path_put); |
1da177e4 | 406 | |
834f2a4a TM |
407 | /** |
408 | * release_open_intent - free up open intent resources | |
409 | * @nd: pointer to nameidata | |
410 | */ | |
411 | void release_open_intent(struct nameidata *nd) | |
412 | { | |
0f7fc9e4 | 413 | if (nd->intent.open.file->f_path.dentry == NULL) |
834f2a4a TM |
414 | put_filp(nd->intent.open.file); |
415 | else | |
416 | fput(nd->intent.open.file); | |
417 | } | |
418 | ||
bcdc5e01 IK |
419 | static inline struct dentry * |
420 | do_revalidate(struct dentry *dentry, struct nameidata *nd) | |
421 | { | |
422 | int status = dentry->d_op->d_revalidate(dentry, nd); | |
423 | if (unlikely(status <= 0)) { | |
424 | /* | |
425 | * The dentry failed validation. | |
426 | * If d_revalidate returned 0 attempt to invalidate | |
427 | * the dentry otherwise d_revalidate is asking us | |
428 | * to return a fail status. | |
429 | */ | |
430 | if (!status) { | |
431 | if (!d_invalidate(dentry)) { | |
432 | dput(dentry); | |
433 | dentry = NULL; | |
434 | } | |
435 | } else { | |
436 | dput(dentry); | |
437 | dentry = ERR_PTR(status); | |
438 | } | |
439 | } | |
440 | return dentry; | |
441 | } | |
442 | ||
1da177e4 LT |
443 | /* |
444 | * Internal lookup() using the new generic dcache. | |
445 | * SMP-safe | |
446 | */ | |
447 | static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
448 | { | |
449 | struct dentry * dentry = __d_lookup(parent, name); | |
450 | ||
451 | /* lockess __d_lookup may fail due to concurrent d_move() | |
452 | * in some unrelated directory, so try with d_lookup | |
453 | */ | |
454 | if (!dentry) | |
455 | dentry = d_lookup(parent, name); | |
456 | ||
bcdc5e01 IK |
457 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) |
458 | dentry = do_revalidate(dentry, nd); | |
459 | ||
1da177e4 LT |
460 | return dentry; |
461 | } | |
462 | ||
463 | /* | |
464 | * Short-cut version of permission(), for calling by | |
465 | * path_walk(), when dcache lock is held. Combines parts | |
466 | * of permission() and generic_permission(), and tests ONLY for | |
467 | * MAY_EXEC permission. | |
468 | * | |
469 | * If appropriate, check DAC only. If not appropriate, or | |
470 | * short-cut DAC fails, then call permission() to do more | |
471 | * complete permission check. | |
472 | */ | |
858119e1 | 473 | static int exec_permission_lite(struct inode *inode, |
1da177e4 LT |
474 | struct nameidata *nd) |
475 | { | |
476 | umode_t mode = inode->i_mode; | |
477 | ||
478 | if (inode->i_op && inode->i_op->permission) | |
479 | return -EAGAIN; | |
480 | ||
481 | if (current->fsuid == inode->i_uid) | |
482 | mode >>= 6; | |
483 | else if (in_group_p(inode->i_gid)) | |
484 | mode >>= 3; | |
485 | ||
486 | if (mode & MAY_EXEC) | |
487 | goto ok; | |
488 | ||
489 | if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) | |
490 | goto ok; | |
491 | ||
492 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) | |
493 | goto ok; | |
494 | ||
495 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) | |
496 | goto ok; | |
497 | ||
498 | return -EACCES; | |
499 | ok: | |
500 | return security_inode_permission(inode, MAY_EXEC, nd); | |
501 | } | |
502 | ||
503 | /* | |
504 | * This is called when everything else fails, and we actually have | |
505 | * to go to the low-level filesystem to find out what we should do.. | |
506 | * | |
507 | * We get the directory semaphore, and after getting that we also | |
508 | * make sure that nobody added the entry to the dcache in the meantime.. | |
509 | * SMP-safe | |
510 | */ | |
511 | static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) | |
512 | { | |
513 | struct dentry * result; | |
514 | struct inode *dir = parent->d_inode; | |
515 | ||
1b1dcc1b | 516 | mutex_lock(&dir->i_mutex); |
1da177e4 LT |
517 | /* |
518 | * First re-do the cached lookup just in case it was created | |
519 | * while we waited for the directory semaphore.. | |
520 | * | |
521 | * FIXME! This could use version numbering or similar to | |
522 | * avoid unnecessary cache lookups. | |
523 | * | |
524 | * The "dcache_lock" is purely to protect the RCU list walker | |
525 | * from concurrent renames at this point (we mustn't get false | |
526 | * negatives from the RCU list walk here, unlike the optimistic | |
527 | * fast walk). | |
528 | * | |
529 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup | |
530 | */ | |
531 | result = d_lookup(parent, name); | |
532 | if (!result) { | |
d70b67c8 MS |
533 | struct dentry *dentry; |
534 | ||
535 | /* Don't create child dentry for a dead directory. */ | |
536 | result = ERR_PTR(-ENOENT); | |
537 | if (IS_DEADDIR(dir)) | |
538 | goto out_unlock; | |
539 | ||
540 | dentry = d_alloc(parent, name); | |
1da177e4 LT |
541 | result = ERR_PTR(-ENOMEM); |
542 | if (dentry) { | |
543 | result = dir->i_op->lookup(dir, dentry, nd); | |
544 | if (result) | |
545 | dput(dentry); | |
546 | else | |
547 | result = dentry; | |
548 | } | |
d70b67c8 | 549 | out_unlock: |
1b1dcc1b | 550 | mutex_unlock(&dir->i_mutex); |
1da177e4 LT |
551 | return result; |
552 | } | |
553 | ||
554 | /* | |
555 | * Uhhuh! Nasty case: the cache was re-populated while | |
556 | * we waited on the semaphore. Need to revalidate. | |
557 | */ | |
1b1dcc1b | 558 | mutex_unlock(&dir->i_mutex); |
1da177e4 | 559 | if (result->d_op && result->d_op->d_revalidate) { |
bcdc5e01 IK |
560 | result = do_revalidate(result, nd); |
561 | if (!result) | |
1da177e4 | 562 | result = ERR_PTR(-ENOENT); |
1da177e4 LT |
563 | } |
564 | return result; | |
565 | } | |
566 | ||
567 | static int __emul_lookup_dentry(const char *, struct nameidata *); | |
568 | ||
569 | /* SMP-safe */ | |
f1662356 | 570 | static __always_inline int |
1da177e4 LT |
571 | walk_init_root(const char *name, struct nameidata *nd) |
572 | { | |
e518ddb7 AM |
573 | struct fs_struct *fs = current->fs; |
574 | ||
575 | read_lock(&fs->lock); | |
6ac08c39 JB |
576 | if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { |
577 | nd->path = fs->altroot; | |
578 | path_get(&fs->altroot); | |
e518ddb7 | 579 | read_unlock(&fs->lock); |
1da177e4 LT |
580 | if (__emul_lookup_dentry(name,nd)) |
581 | return 0; | |
e518ddb7 | 582 | read_lock(&fs->lock); |
1da177e4 | 583 | } |
6ac08c39 JB |
584 | nd->path = fs->root; |
585 | path_get(&fs->root); | |
e518ddb7 | 586 | read_unlock(&fs->lock); |
1da177e4 LT |
587 | return 1; |
588 | } | |
589 | ||
a02f76c3 AV |
590 | /* |
591 | * Wrapper to retry pathname resolution whenever the underlying | |
592 | * file system returns an ESTALE. | |
593 | * | |
594 | * Retry the whole path once, forcing real lookup requests | |
595 | * instead of relying on the dcache. | |
596 | */ | |
597 | static __always_inline int link_path_walk(const char *name, struct nameidata *nd) | |
598 | { | |
599 | struct path save = nd->path; | |
600 | int result; | |
601 | ||
602 | /* make sure the stuff we saved doesn't go away */ | |
c8e7f449 | 603 | path_get(&save); |
a02f76c3 AV |
604 | |
605 | result = __link_path_walk(name, nd); | |
606 | if (result == -ESTALE) { | |
607 | /* nd->path had been dropped */ | |
608 | nd->path = save; | |
c8e7f449 | 609 | path_get(&nd->path); |
a02f76c3 AV |
610 | nd->flags |= LOOKUP_REVAL; |
611 | result = __link_path_walk(name, nd); | |
612 | } | |
613 | ||
614 | path_put(&save); | |
615 | ||
616 | return result; | |
617 | } | |
618 | ||
f1662356 | 619 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 LT |
620 | { |
621 | int res = 0; | |
622 | char *name; | |
623 | if (IS_ERR(link)) | |
624 | goto fail; | |
625 | ||
626 | if (*link == '/') { | |
1d957f9b | 627 | path_put(&nd->path); |
1da177e4 LT |
628 | if (!walk_init_root(link, nd)) |
629 | /* weird __emul_prefix() stuff did it */ | |
630 | goto out; | |
631 | } | |
632 | res = link_path_walk(link, nd); | |
633 | out: | |
634 | if (nd->depth || res || nd->last_type!=LAST_NORM) | |
635 | return res; | |
636 | /* | |
637 | * If it is an iterative symlinks resolution in open_namei() we | |
638 | * have to copy the last component. And all that crap because of | |
639 | * bloody create() on broken symlinks. Furrfu... | |
640 | */ | |
641 | name = __getname(); | |
642 | if (unlikely(!name)) { | |
1d957f9b | 643 | path_put(&nd->path); |
1da177e4 LT |
644 | return -ENOMEM; |
645 | } | |
646 | strcpy(name, nd->last.name); | |
647 | nd->last.name = name; | |
648 | return 0; | |
649 | fail: | |
1d957f9b | 650 | path_put(&nd->path); |
1da177e4 LT |
651 | return PTR_ERR(link); |
652 | } | |
653 | ||
1d957f9b | 654 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
655 | { |
656 | dput(path->dentry); | |
4ac91378 | 657 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
658 | mntput(path->mnt); |
659 | } | |
660 | ||
661 | static inline void path_to_nameidata(struct path *path, struct nameidata *nd) | |
662 | { | |
4ac91378 JB |
663 | dput(nd->path.dentry); |
664 | if (nd->path.mnt != path->mnt) | |
665 | mntput(nd->path.mnt); | |
666 | nd->path.mnt = path->mnt; | |
667 | nd->path.dentry = path->dentry; | |
051d3812 IK |
668 | } |
669 | ||
f1662356 | 670 | static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
671 | { |
672 | int error; | |
cc314eef | 673 | void *cookie; |
cd4e91d3 | 674 | struct dentry *dentry = path->dentry; |
1da177e4 | 675 | |
d671a1cb | 676 | touch_atime(path->mnt, dentry); |
1da177e4 | 677 | nd_set_link(nd, NULL); |
cd4e91d3 | 678 | |
4ac91378 | 679 | if (path->mnt != nd->path.mnt) { |
051d3812 IK |
680 | path_to_nameidata(path, nd); |
681 | dget(dentry); | |
682 | } | |
683 | mntget(path->mnt); | |
cc314eef LT |
684 | cookie = dentry->d_inode->i_op->follow_link(dentry, nd); |
685 | error = PTR_ERR(cookie); | |
686 | if (!IS_ERR(cookie)) { | |
1da177e4 | 687 | char *s = nd_get_link(nd); |
cc314eef | 688 | error = 0; |
1da177e4 LT |
689 | if (s) |
690 | error = __vfs_follow_link(nd, s); | |
691 | if (dentry->d_inode->i_op->put_link) | |
cc314eef | 692 | dentry->d_inode->i_op->put_link(dentry, nd, cookie); |
1da177e4 | 693 | } |
09da5916 | 694 | path_put(path); |
1da177e4 LT |
695 | |
696 | return error; | |
697 | } | |
698 | ||
699 | /* | |
700 | * This limits recursive symlink follows to 8, while | |
701 | * limiting consecutive symlinks to 40. | |
702 | * | |
703 | * Without that kind of total limit, nasty chains of consecutive | |
704 | * symlinks can cause almost arbitrarily long lookups. | |
705 | */ | |
90ebe565 | 706 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
707 | { |
708 | int err = -ELOOP; | |
709 | if (current->link_count >= MAX_NESTED_LINKS) | |
710 | goto loop; | |
711 | if (current->total_link_count >= 40) | |
712 | goto loop; | |
713 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); | |
714 | cond_resched(); | |
90ebe565 | 715 | err = security_inode_follow_link(path->dentry, nd); |
1da177e4 LT |
716 | if (err) |
717 | goto loop; | |
718 | current->link_count++; | |
719 | current->total_link_count++; | |
720 | nd->depth++; | |
cd4e91d3 | 721 | err = __do_follow_link(path, nd); |
839d9f93 AV |
722 | current->link_count--; |
723 | nd->depth--; | |
1da177e4 LT |
724 | return err; |
725 | loop: | |
1d957f9b JB |
726 | path_put_conditional(path, nd); |
727 | path_put(&nd->path); | |
1da177e4 LT |
728 | return err; |
729 | } | |
730 | ||
731 | int follow_up(struct vfsmount **mnt, struct dentry **dentry) | |
732 | { | |
733 | struct vfsmount *parent; | |
734 | struct dentry *mountpoint; | |
735 | spin_lock(&vfsmount_lock); | |
736 | parent=(*mnt)->mnt_parent; | |
737 | if (parent == *mnt) { | |
738 | spin_unlock(&vfsmount_lock); | |
739 | return 0; | |
740 | } | |
741 | mntget(parent); | |
742 | mountpoint=dget((*mnt)->mnt_mountpoint); | |
743 | spin_unlock(&vfsmount_lock); | |
744 | dput(*dentry); | |
745 | *dentry = mountpoint; | |
746 | mntput(*mnt); | |
747 | *mnt = parent; | |
748 | return 1; | |
749 | } | |
750 | ||
751 | /* no need for dcache_lock, as serialization is taken care in | |
752 | * namespace.c | |
753 | */ | |
463ffb2e AV |
754 | static int __follow_mount(struct path *path) |
755 | { | |
756 | int res = 0; | |
757 | while (d_mountpoint(path->dentry)) { | |
758 | struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); | |
759 | if (!mounted) | |
760 | break; | |
761 | dput(path->dentry); | |
762 | if (res) | |
763 | mntput(path->mnt); | |
764 | path->mnt = mounted; | |
765 | path->dentry = dget(mounted->mnt_root); | |
766 | res = 1; | |
767 | } | |
768 | return res; | |
769 | } | |
770 | ||
58c465eb | 771 | static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 | 772 | { |
1da177e4 LT |
773 | while (d_mountpoint(*dentry)) { |
774 | struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); | |
775 | if (!mounted) | |
776 | break; | |
58c465eb | 777 | dput(*dentry); |
1da177e4 LT |
778 | mntput(*mnt); |
779 | *mnt = mounted; | |
1da177e4 | 780 | *dentry = dget(mounted->mnt_root); |
1da177e4 | 781 | } |
1da177e4 LT |
782 | } |
783 | ||
784 | /* no need for dcache_lock, as serialization is taken care in | |
785 | * namespace.c | |
786 | */ | |
e13b210f | 787 | int follow_down(struct vfsmount **mnt, struct dentry **dentry) |
1da177e4 LT |
788 | { |
789 | struct vfsmount *mounted; | |
790 | ||
791 | mounted = lookup_mnt(*mnt, *dentry); | |
792 | if (mounted) { | |
e13b210f | 793 | dput(*dentry); |
1da177e4 LT |
794 | mntput(*mnt); |
795 | *mnt = mounted; | |
1da177e4 LT |
796 | *dentry = dget(mounted->mnt_root); |
797 | return 1; | |
798 | } | |
799 | return 0; | |
800 | } | |
801 | ||
f1662356 | 802 | static __always_inline void follow_dotdot(struct nameidata *nd) |
1da177e4 | 803 | { |
e518ddb7 AM |
804 | struct fs_struct *fs = current->fs; |
805 | ||
1da177e4 LT |
806 | while(1) { |
807 | struct vfsmount *parent; | |
4ac91378 | 808 | struct dentry *old = nd->path.dentry; |
1da177e4 | 809 | |
e518ddb7 | 810 | read_lock(&fs->lock); |
6ac08c39 JB |
811 | if (nd->path.dentry == fs->root.dentry && |
812 | nd->path.mnt == fs->root.mnt) { | |
e518ddb7 | 813 | read_unlock(&fs->lock); |
1da177e4 LT |
814 | break; |
815 | } | |
e518ddb7 | 816 | read_unlock(&fs->lock); |
1da177e4 | 817 | spin_lock(&dcache_lock); |
4ac91378 JB |
818 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
819 | nd->path.dentry = dget(nd->path.dentry->d_parent); | |
1da177e4 LT |
820 | spin_unlock(&dcache_lock); |
821 | dput(old); | |
822 | break; | |
823 | } | |
824 | spin_unlock(&dcache_lock); | |
825 | spin_lock(&vfsmount_lock); | |
4ac91378 JB |
826 | parent = nd->path.mnt->mnt_parent; |
827 | if (parent == nd->path.mnt) { | |
1da177e4 LT |
828 | spin_unlock(&vfsmount_lock); |
829 | break; | |
830 | } | |
831 | mntget(parent); | |
4ac91378 | 832 | nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); |
1da177e4 LT |
833 | spin_unlock(&vfsmount_lock); |
834 | dput(old); | |
4ac91378 JB |
835 | mntput(nd->path.mnt); |
836 | nd->path.mnt = parent; | |
1da177e4 | 837 | } |
4ac91378 | 838 | follow_mount(&nd->path.mnt, &nd->path.dentry); |
1da177e4 LT |
839 | } |
840 | ||
1da177e4 LT |
841 | /* |
842 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
843 | * small and for now I'd prefer to have fast path as straight as possible. | |
844 | * It _is_ time-critical. | |
845 | */ | |
846 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
847 | struct path *path) | |
848 | { | |
4ac91378 JB |
849 | struct vfsmount *mnt = nd->path.mnt; |
850 | struct dentry *dentry = __d_lookup(nd->path.dentry, name); | |
1da177e4 LT |
851 | |
852 | if (!dentry) | |
853 | goto need_lookup; | |
854 | if (dentry->d_op && dentry->d_op->d_revalidate) | |
855 | goto need_revalidate; | |
856 | done: | |
857 | path->mnt = mnt; | |
858 | path->dentry = dentry; | |
634ee701 | 859 | __follow_mount(path); |
1da177e4 LT |
860 | return 0; |
861 | ||
862 | need_lookup: | |
4ac91378 | 863 | dentry = real_lookup(nd->path.dentry, name, nd); |
1da177e4 LT |
864 | if (IS_ERR(dentry)) |
865 | goto fail; | |
866 | goto done; | |
867 | ||
868 | need_revalidate: | |
bcdc5e01 IK |
869 | dentry = do_revalidate(dentry, nd); |
870 | if (!dentry) | |
871 | goto need_lookup; | |
872 | if (IS_ERR(dentry)) | |
873 | goto fail; | |
874 | goto done; | |
1da177e4 LT |
875 | |
876 | fail: | |
877 | return PTR_ERR(dentry); | |
878 | } | |
879 | ||
880 | /* | |
881 | * Name resolution. | |
ea3834d9 PM |
882 | * This is the basic name resolution function, turning a pathname into |
883 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 884 | * |
ea3834d9 PM |
885 | * Returns 0 and nd will have valid dentry and mnt on success. |
886 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 887 | */ |
fc9b52cd | 888 | static int __link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
889 | { |
890 | struct path next; | |
891 | struct inode *inode; | |
892 | int err; | |
893 | unsigned int lookup_flags = nd->flags; | |
894 | ||
895 | while (*name=='/') | |
896 | name++; | |
897 | if (!*name) | |
898 | goto return_reval; | |
899 | ||
4ac91378 | 900 | inode = nd->path.dentry->d_inode; |
1da177e4 | 901 | if (nd->depth) |
f55eab82 | 902 | lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); |
1da177e4 LT |
903 | |
904 | /* At this point we know we have a real path component. */ | |
905 | for(;;) { | |
906 | unsigned long hash; | |
907 | struct qstr this; | |
908 | unsigned int c; | |
909 | ||
cdce5d6b | 910 | nd->flags |= LOOKUP_CONTINUE; |
1da177e4 | 911 | err = exec_permission_lite(inode, nd); |
e4543edd CH |
912 | if (err == -EAGAIN) |
913 | err = vfs_permission(nd, MAY_EXEC); | |
1da177e4 LT |
914 | if (err) |
915 | break; | |
916 | ||
917 | this.name = name; | |
918 | c = *(const unsigned char *)name; | |
919 | ||
920 | hash = init_name_hash(); | |
921 | do { | |
922 | name++; | |
923 | hash = partial_name_hash(c, hash); | |
924 | c = *(const unsigned char *)name; | |
925 | } while (c && (c != '/')); | |
926 | this.len = name - (const char *) this.name; | |
927 | this.hash = end_name_hash(hash); | |
928 | ||
929 | /* remove trailing slashes? */ | |
930 | if (!c) | |
931 | goto last_component; | |
932 | while (*++name == '/'); | |
933 | if (!*name) | |
934 | goto last_with_slashes; | |
935 | ||
936 | /* | |
937 | * "." and ".." are special - ".." especially so because it has | |
938 | * to be able to know about the current root directory and | |
939 | * parent relationships. | |
940 | */ | |
941 | if (this.name[0] == '.') switch (this.len) { | |
942 | default: | |
943 | break; | |
944 | case 2: | |
945 | if (this.name[1] != '.') | |
946 | break; | |
58c465eb | 947 | follow_dotdot(nd); |
4ac91378 | 948 | inode = nd->path.dentry->d_inode; |
1da177e4 LT |
949 | /* fallthrough */ |
950 | case 1: | |
951 | continue; | |
952 | } | |
953 | /* | |
954 | * See if the low-level filesystem might want | |
955 | * to use its own hash.. | |
956 | */ | |
4ac91378 JB |
957 | if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { |
958 | err = nd->path.dentry->d_op->d_hash(nd->path.dentry, | |
959 | &this); | |
1da177e4 LT |
960 | if (err < 0) |
961 | break; | |
962 | } | |
1da177e4 LT |
963 | /* This does the actual lookups.. */ |
964 | err = do_lookup(nd, &this, &next); | |
965 | if (err) | |
966 | break; | |
1da177e4 LT |
967 | |
968 | err = -ENOENT; | |
969 | inode = next.dentry->d_inode; | |
970 | if (!inode) | |
971 | goto out_dput; | |
972 | err = -ENOTDIR; | |
973 | if (!inode->i_op) | |
974 | goto out_dput; | |
975 | ||
976 | if (inode->i_op->follow_link) { | |
90ebe565 | 977 | err = do_follow_link(&next, nd); |
1da177e4 LT |
978 | if (err) |
979 | goto return_err; | |
980 | err = -ENOENT; | |
4ac91378 | 981 | inode = nd->path.dentry->d_inode; |
1da177e4 LT |
982 | if (!inode) |
983 | break; | |
984 | err = -ENOTDIR; | |
985 | if (!inode->i_op) | |
986 | break; | |
09dd17d3 MS |
987 | } else |
988 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
989 | err = -ENOTDIR; |
990 | if (!inode->i_op->lookup) | |
991 | break; | |
992 | continue; | |
993 | /* here ends the main loop */ | |
994 | ||
995 | last_with_slashes: | |
996 | lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
997 | last_component: | |
f55eab82 TM |
998 | /* Clear LOOKUP_CONTINUE iff it was previously unset */ |
999 | nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; | |
1da177e4 LT |
1000 | if (lookup_flags & LOOKUP_PARENT) |
1001 | goto lookup_parent; | |
1002 | if (this.name[0] == '.') switch (this.len) { | |
1003 | default: | |
1004 | break; | |
1005 | case 2: | |
1006 | if (this.name[1] != '.') | |
1007 | break; | |
58c465eb | 1008 | follow_dotdot(nd); |
4ac91378 | 1009 | inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1010 | /* fallthrough */ |
1011 | case 1: | |
1012 | goto return_reval; | |
1013 | } | |
4ac91378 JB |
1014 | if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { |
1015 | err = nd->path.dentry->d_op->d_hash(nd->path.dentry, | |
1016 | &this); | |
1da177e4 LT |
1017 | if (err < 0) |
1018 | break; | |
1019 | } | |
1020 | err = do_lookup(nd, &this, &next); | |
1021 | if (err) | |
1022 | break; | |
1da177e4 LT |
1023 | inode = next.dentry->d_inode; |
1024 | if ((lookup_flags & LOOKUP_FOLLOW) | |
1025 | && inode && inode->i_op && inode->i_op->follow_link) { | |
90ebe565 | 1026 | err = do_follow_link(&next, nd); |
1da177e4 LT |
1027 | if (err) |
1028 | goto return_err; | |
4ac91378 | 1029 | inode = nd->path.dentry->d_inode; |
09dd17d3 MS |
1030 | } else |
1031 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
1032 | err = -ENOENT; |
1033 | if (!inode) | |
1034 | break; | |
1035 | if (lookup_flags & LOOKUP_DIRECTORY) { | |
1036 | err = -ENOTDIR; | |
1037 | if (!inode->i_op || !inode->i_op->lookup) | |
1038 | break; | |
1039 | } | |
1040 | goto return_base; | |
1041 | lookup_parent: | |
1042 | nd->last = this; | |
1043 | nd->last_type = LAST_NORM; | |
1044 | if (this.name[0] != '.') | |
1045 | goto return_base; | |
1046 | if (this.len == 1) | |
1047 | nd->last_type = LAST_DOT; | |
1048 | else if (this.len == 2 && this.name[1] == '.') | |
1049 | nd->last_type = LAST_DOTDOT; | |
1050 | else | |
1051 | goto return_base; | |
1052 | return_reval: | |
1053 | /* | |
1054 | * We bypassed the ordinary revalidation routines. | |
1055 | * We may need to check the cached dentry for staleness. | |
1056 | */ | |
4ac91378 JB |
1057 | if (nd->path.dentry && nd->path.dentry->d_sb && |
1058 | (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { | |
1da177e4 LT |
1059 | err = -ESTALE; |
1060 | /* Note: we do not d_invalidate() */ | |
4ac91378 JB |
1061 | if (!nd->path.dentry->d_op->d_revalidate( |
1062 | nd->path.dentry, nd)) | |
1da177e4 LT |
1063 | break; |
1064 | } | |
1065 | return_base: | |
1066 | return 0; | |
1067 | out_dput: | |
1d957f9b | 1068 | path_put_conditional(&next, nd); |
1da177e4 LT |
1069 | break; |
1070 | } | |
1d957f9b | 1071 | path_put(&nd->path); |
1da177e4 LT |
1072 | return_err: |
1073 | return err; | |
1074 | } | |
1075 | ||
fc9b52cd | 1076 | static int path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1077 | { |
1078 | current->total_link_count = 0; | |
1079 | return link_path_walk(name, nd); | |
1080 | } | |
1081 | ||
ea3834d9 PM |
1082 | /* |
1083 | * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if | |
1084 | * everything is done. Returns 0 and drops input nd, if lookup failed; | |
1085 | */ | |
1da177e4 LT |
1086 | static int __emul_lookup_dentry(const char *name, struct nameidata *nd) |
1087 | { | |
1088 | if (path_walk(name, nd)) | |
1089 | return 0; /* something went wrong... */ | |
1090 | ||
4ac91378 JB |
1091 | if (!nd->path.dentry->d_inode || |
1092 | S_ISDIR(nd->path.dentry->d_inode->i_mode)) { | |
09da5916 | 1093 | struct path old_path = nd->path; |
1da177e4 LT |
1094 | struct qstr last = nd->last; |
1095 | int last_type = nd->last_type; | |
e518ddb7 AM |
1096 | struct fs_struct *fs = current->fs; |
1097 | ||
1da177e4 | 1098 | /* |
e518ddb7 AM |
1099 | * NAME was not found in alternate root or it's a directory. |
1100 | * Try to find it in the normal root: | |
1da177e4 LT |
1101 | */ |
1102 | nd->last_type = LAST_ROOT; | |
e518ddb7 | 1103 | read_lock(&fs->lock); |
6ac08c39 JB |
1104 | nd->path = fs->root; |
1105 | path_get(&fs->root); | |
e518ddb7 | 1106 | read_unlock(&fs->lock); |
1da177e4 | 1107 | if (path_walk(name, nd) == 0) { |
4ac91378 | 1108 | if (nd->path.dentry->d_inode) { |
09da5916 | 1109 | path_put(&old_path); |
1da177e4 LT |
1110 | return 1; |
1111 | } | |
1d957f9b | 1112 | path_put(&nd->path); |
1da177e4 | 1113 | } |
09da5916 | 1114 | nd->path = old_path; |
1da177e4 LT |
1115 | nd->last = last; |
1116 | nd->last_type = last_type; | |
1117 | } | |
1118 | return 1; | |
1119 | } | |
1120 | ||
1121 | void set_fs_altroot(void) | |
1122 | { | |
1123 | char *emul = __emul_prefix(); | |
1124 | struct nameidata nd; | |
6ac08c39 | 1125 | struct path path = {}, old_path; |
1da177e4 | 1126 | int err; |
e518ddb7 | 1127 | struct fs_struct *fs = current->fs; |
1da177e4 LT |
1128 | |
1129 | if (!emul) | |
1130 | goto set_it; | |
1131 | err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); | |
6ac08c39 JB |
1132 | if (!err) |
1133 | path = nd.path; | |
1da177e4 | 1134 | set_it: |
e518ddb7 | 1135 | write_lock(&fs->lock); |
6ac08c39 JB |
1136 | old_path = fs->altroot; |
1137 | fs->altroot = path; | |
e518ddb7 | 1138 | write_unlock(&fs->lock); |
6ac08c39 JB |
1139 | if (old_path.dentry) |
1140 | path_put(&old_path); | |
1da177e4 LT |
1141 | } |
1142 | ||
ea3834d9 | 1143 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
fc9b52cd | 1144 | static int do_path_lookup(int dfd, const char *name, |
5590ff0d | 1145 | unsigned int flags, struct nameidata *nd) |
1da177e4 | 1146 | { |
ea3834d9 | 1147 | int retval = 0; |
170aa3d0 UD |
1148 | int fput_needed; |
1149 | struct file *file; | |
e518ddb7 | 1150 | struct fs_struct *fs = current->fs; |
1da177e4 LT |
1151 | |
1152 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
1153 | nd->flags = flags; | |
1154 | nd->depth = 0; | |
1155 | ||
1da177e4 | 1156 | if (*name=='/') { |
e518ddb7 | 1157 | read_lock(&fs->lock); |
6ac08c39 JB |
1158 | if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) { |
1159 | nd->path = fs->altroot; | |
1160 | path_get(&fs->altroot); | |
e518ddb7 | 1161 | read_unlock(&fs->lock); |
1da177e4 | 1162 | if (__emul_lookup_dentry(name,nd)) |
ea3834d9 | 1163 | goto out; /* found in altroot */ |
e518ddb7 | 1164 | read_lock(&fs->lock); |
1da177e4 | 1165 | } |
6ac08c39 JB |
1166 | nd->path = fs->root; |
1167 | path_get(&fs->root); | |
e518ddb7 | 1168 | read_unlock(&fs->lock); |
5590ff0d | 1169 | } else if (dfd == AT_FDCWD) { |
e518ddb7 | 1170 | read_lock(&fs->lock); |
6ac08c39 JB |
1171 | nd->path = fs->pwd; |
1172 | path_get(&fs->pwd); | |
e518ddb7 | 1173 | read_unlock(&fs->lock); |
5590ff0d | 1174 | } else { |
5590ff0d UD |
1175 | struct dentry *dentry; |
1176 | ||
1177 | file = fget_light(dfd, &fput_needed); | |
170aa3d0 UD |
1178 | retval = -EBADF; |
1179 | if (!file) | |
6d09bb62 | 1180 | goto out_fail; |
5590ff0d | 1181 | |
0f7fc9e4 | 1182 | dentry = file->f_path.dentry; |
5590ff0d | 1183 | |
170aa3d0 UD |
1184 | retval = -ENOTDIR; |
1185 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
6d09bb62 | 1186 | goto fput_fail; |
5590ff0d UD |
1187 | |
1188 | retval = file_permission(file, MAY_EXEC); | |
170aa3d0 | 1189 | if (retval) |
6d09bb62 | 1190 | goto fput_fail; |
5590ff0d | 1191 | |
5dd784d0 JB |
1192 | nd->path = file->f_path; |
1193 | path_get(&file->f_path); | |
5590ff0d UD |
1194 | |
1195 | fput_light(file, fput_needed); | |
1da177e4 | 1196 | } |
2dfdd266 JJS |
1197 | |
1198 | retval = path_walk(name, nd); | |
ea3834d9 | 1199 | out: |
4ac91378 JB |
1200 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1201 | nd->path.dentry->d_inode)) | |
1202 | audit_inode(name, nd->path.dentry); | |
6d09bb62 | 1203 | out_fail: |
170aa3d0 UD |
1204 | return retval; |
1205 | ||
6d09bb62 | 1206 | fput_fail: |
170aa3d0 | 1207 | fput_light(file, fput_needed); |
6d09bb62 | 1208 | goto out_fail; |
1da177e4 LT |
1209 | } |
1210 | ||
fc9b52cd | 1211 | int path_lookup(const char *name, unsigned int flags, |
5590ff0d UD |
1212 | struct nameidata *nd) |
1213 | { | |
1214 | return do_path_lookup(AT_FDCWD, name, flags, nd); | |
1215 | } | |
1216 | ||
16f18200 JJS |
1217 | /** |
1218 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
1219 | * @dentry: pointer to dentry of the base directory | |
1220 | * @mnt: pointer to vfs mount of the base directory | |
1221 | * @name: pointer to file name | |
1222 | * @flags: lookup flags | |
1223 | * @nd: pointer to nameidata | |
1224 | */ | |
1225 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
1226 | const char *name, unsigned int flags, | |
1227 | struct nameidata *nd) | |
1228 | { | |
1229 | int retval; | |
1230 | ||
1231 | /* same as do_path_lookup */ | |
1232 | nd->last_type = LAST_ROOT; | |
1233 | nd->flags = flags; | |
1234 | nd->depth = 0; | |
1235 | ||
c8e7f449 JB |
1236 | nd->path.dentry = dentry; |
1237 | nd->path.mnt = mnt; | |
1238 | path_get(&nd->path); | |
16f18200 JJS |
1239 | |
1240 | retval = path_walk(name, nd); | |
4ac91378 JB |
1241 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1242 | nd->path.dentry->d_inode)) | |
1243 | audit_inode(name, nd->path.dentry); | |
16f18200 JJS |
1244 | |
1245 | return retval; | |
1246 | ||
1247 | } | |
1248 | ||
5590ff0d UD |
1249 | static int __path_lookup_intent_open(int dfd, const char *name, |
1250 | unsigned int lookup_flags, struct nameidata *nd, | |
1251 | int open_flags, int create_mode) | |
834f2a4a TM |
1252 | { |
1253 | struct file *filp = get_empty_filp(); | |
1254 | int err; | |
1255 | ||
1256 | if (filp == NULL) | |
1257 | return -ENFILE; | |
1258 | nd->intent.open.file = filp; | |
1259 | nd->intent.open.flags = open_flags; | |
1260 | nd->intent.open.create_mode = create_mode; | |
5590ff0d | 1261 | err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); |
834f2a4a TM |
1262 | if (IS_ERR(nd->intent.open.file)) { |
1263 | if (err == 0) { | |
1264 | err = PTR_ERR(nd->intent.open.file); | |
1d957f9b | 1265 | path_put(&nd->path); |
834f2a4a TM |
1266 | } |
1267 | } else if (err != 0) | |
1268 | release_open_intent(nd); | |
1269 | return err; | |
1270 | } | |
1271 | ||
1272 | /** | |
1273 | * path_lookup_open - lookup a file path with open intent | |
7045f37b | 1274 | * @dfd: the directory to use as base, or AT_FDCWD |
834f2a4a TM |
1275 | * @name: pointer to file name |
1276 | * @lookup_flags: lookup intent flags | |
1277 | * @nd: pointer to nameidata | |
1278 | * @open_flags: open intent flags | |
1279 | */ | |
5590ff0d | 1280 | int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, |
834f2a4a TM |
1281 | struct nameidata *nd, int open_flags) |
1282 | { | |
5590ff0d | 1283 | return __path_lookup_intent_open(dfd, name, lookup_flags, nd, |
834f2a4a TM |
1284 | open_flags, 0); |
1285 | } | |
1286 | ||
1287 | /** | |
1288 | * path_lookup_create - lookup a file path with open + create intent | |
7045f37b | 1289 | * @dfd: the directory to use as base, or AT_FDCWD |
834f2a4a TM |
1290 | * @name: pointer to file name |
1291 | * @lookup_flags: lookup intent flags | |
1292 | * @nd: pointer to nameidata | |
1293 | * @open_flags: open intent flags | |
1294 | * @create_mode: create intent flags | |
1295 | */ | |
5590ff0d UD |
1296 | static int path_lookup_create(int dfd, const char *name, |
1297 | unsigned int lookup_flags, struct nameidata *nd, | |
1298 | int open_flags, int create_mode) | |
834f2a4a | 1299 | { |
5590ff0d UD |
1300 | return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE, |
1301 | nd, open_flags, create_mode); | |
834f2a4a TM |
1302 | } |
1303 | ||
1304 | int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, | |
1305 | struct nameidata *nd, int open_flags) | |
1306 | { | |
1307 | char *tmp = getname(name); | |
1308 | int err = PTR_ERR(tmp); | |
1309 | ||
1310 | if (!IS_ERR(tmp)) { | |
5590ff0d | 1311 | err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0); |
834f2a4a TM |
1312 | putname(tmp); |
1313 | } | |
1314 | return err; | |
1315 | } | |
1316 | ||
eead1911 CH |
1317 | static struct dentry *__lookup_hash(struct qstr *name, |
1318 | struct dentry *base, struct nameidata *nd) | |
1da177e4 | 1319 | { |
057f6c01 | 1320 | struct dentry *dentry; |
1da177e4 LT |
1321 | struct inode *inode; |
1322 | int err; | |
1323 | ||
1324 | inode = base->d_inode; | |
1da177e4 LT |
1325 | |
1326 | /* | |
1327 | * See if the low-level filesystem might want | |
1328 | * to use its own hash.. | |
1329 | */ | |
1330 | if (base->d_op && base->d_op->d_hash) { | |
1331 | err = base->d_op->d_hash(base, name); | |
1332 | dentry = ERR_PTR(err); | |
1333 | if (err < 0) | |
1334 | goto out; | |
1335 | } | |
1336 | ||
1337 | dentry = cached_lookup(base, name, nd); | |
1338 | if (!dentry) { | |
d70b67c8 MS |
1339 | struct dentry *new; |
1340 | ||
1341 | /* Don't create child dentry for a dead directory. */ | |
1342 | dentry = ERR_PTR(-ENOENT); | |
1343 | if (IS_DEADDIR(inode)) | |
1344 | goto out; | |
1345 | ||
1346 | new = d_alloc(base, name); | |
1da177e4 LT |
1347 | dentry = ERR_PTR(-ENOMEM); |
1348 | if (!new) | |
1349 | goto out; | |
1350 | dentry = inode->i_op->lookup(inode, new, nd); | |
1351 | if (!dentry) | |
1352 | dentry = new; | |
1353 | else | |
1354 | dput(new); | |
1355 | } | |
1356 | out: | |
1357 | return dentry; | |
1358 | } | |
1359 | ||
057f6c01 JM |
1360 | /* |
1361 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1362 | * needs parent already locked. Doesn't follow mounts. | |
1363 | * SMP-safe. | |
1364 | */ | |
eead1911 | 1365 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 1366 | { |
057f6c01 JM |
1367 | int err; |
1368 | ||
4ac91378 | 1369 | err = permission(nd->path.dentry->d_inode, MAY_EXEC, nd); |
057f6c01 | 1370 | if (err) |
eead1911 | 1371 | return ERR_PTR(err); |
4ac91378 | 1372 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1da177e4 LT |
1373 | } |
1374 | ||
eead1911 CH |
1375 | static int __lookup_one_len(const char *name, struct qstr *this, |
1376 | struct dentry *base, int len) | |
1da177e4 LT |
1377 | { |
1378 | unsigned long hash; | |
1da177e4 LT |
1379 | unsigned int c; |
1380 | ||
057f6c01 JM |
1381 | this->name = name; |
1382 | this->len = len; | |
1da177e4 | 1383 | if (!len) |
057f6c01 | 1384 | return -EACCES; |
1da177e4 LT |
1385 | |
1386 | hash = init_name_hash(); | |
1387 | while (len--) { | |
1388 | c = *(const unsigned char *)name++; | |
1389 | if (c == '/' || c == '\0') | |
057f6c01 | 1390 | return -EACCES; |
1da177e4 LT |
1391 | hash = partial_name_hash(c, hash); |
1392 | } | |
057f6c01 JM |
1393 | this->hash = end_name_hash(hash); |
1394 | return 0; | |
1395 | } | |
1da177e4 | 1396 | |
eead1911 | 1397 | /** |
a6b91919 | 1398 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
1399 | * @name: pathname component to lookup |
1400 | * @base: base directory to lookup from | |
1401 | * @len: maximum length @len should be interpreted to | |
1402 | * | |
a6b91919 RD |
1403 | * Note that this routine is purely a helper for filesystem usage and should |
1404 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
1405 | * nameidata argument is passed to the filesystem methods and a filesystem |
1406 | * using this helper needs to be prepared for that. | |
1407 | */ | |
057f6c01 JM |
1408 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1409 | { | |
1410 | int err; | |
1411 | struct qstr this; | |
1412 | ||
1413 | err = __lookup_one_len(name, &this, base, len); | |
eead1911 CH |
1414 | if (err) |
1415 | return ERR_PTR(err); | |
1416 | ||
1417 | err = permission(base->d_inode, MAY_EXEC, NULL); | |
057f6c01 JM |
1418 | if (err) |
1419 | return ERR_PTR(err); | |
49705b77 | 1420 | return __lookup_hash(&this, base, NULL); |
057f6c01 JM |
1421 | } |
1422 | ||
eead1911 CH |
1423 | /** |
1424 | * lookup_one_noperm - bad hack for sysfs | |
1425 | * @name: pathname component to lookup | |
1426 | * @base: base directory to lookup from | |
1427 | * | |
1428 | * This is a variant of lookup_one_len that doesn't perform any permission | |
1429 | * checks. It's a horrible hack to work around the braindead sysfs | |
1430 | * architecture and should not be used anywhere else. | |
1431 | * | |
1432 | * DON'T USE THIS FUNCTION EVER, thanks. | |
1433 | */ | |
1434 | struct dentry *lookup_one_noperm(const char *name, struct dentry *base) | |
057f6c01 JM |
1435 | { |
1436 | int err; | |
1437 | struct qstr this; | |
1438 | ||
eead1911 | 1439 | err = __lookup_one_len(name, &this, base, strlen(name)); |
057f6c01 JM |
1440 | if (err) |
1441 | return ERR_PTR(err); | |
eead1911 | 1442 | return __lookup_hash(&this, base, NULL); |
1da177e4 LT |
1443 | } |
1444 | ||
fc9b52cd | 1445 | int __user_walk_fd(int dfd, const char __user *name, unsigned flags, |
5590ff0d | 1446 | struct nameidata *nd) |
1da177e4 LT |
1447 | { |
1448 | char *tmp = getname(name); | |
1449 | int err = PTR_ERR(tmp); | |
1450 | ||
1451 | if (!IS_ERR(tmp)) { | |
5590ff0d | 1452 | err = do_path_lookup(dfd, tmp, flags, nd); |
1da177e4 LT |
1453 | putname(tmp); |
1454 | } | |
1455 | return err; | |
1456 | } | |
1457 | ||
fc9b52cd | 1458 | int __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) |
5590ff0d UD |
1459 | { |
1460 | return __user_walk_fd(AT_FDCWD, name, flags, nd); | |
1461 | } | |
1462 | ||
1da177e4 LT |
1463 | /* |
1464 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1465 | * minimal. | |
1466 | */ | |
1467 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1468 | { | |
1469 | if (!(dir->i_mode & S_ISVTX)) | |
1470 | return 0; | |
1471 | if (inode->i_uid == current->fsuid) | |
1472 | return 0; | |
1473 | if (dir->i_uid == current->fsuid) | |
1474 | return 0; | |
1475 | return !capable(CAP_FOWNER); | |
1476 | } | |
1477 | ||
1478 | /* | |
1479 | * Check whether we can remove a link victim from directory dir, check | |
1480 | * whether the type of victim is right. | |
1481 | * 1. We can't do it if dir is read-only (done in permission()) | |
1482 | * 2. We should have write and exec permissions on dir | |
1483 | * 3. We can't remove anything from append-only dir | |
1484 | * 4. We can't do anything with immutable dir (done in permission()) | |
1485 | * 5. If the sticky bit on dir is set we should either | |
1486 | * a. be owner of dir, or | |
1487 | * b. be owner of victim, or | |
1488 | * c. have CAP_FOWNER capability | |
1489 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1490 | * links pointing to it. | |
1491 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1492 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1493 | * 9. We can't remove a root or mountpoint. | |
1494 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1495 | * nfs_async_unlink(). | |
1496 | */ | |
858119e1 | 1497 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1498 | { |
1499 | int error; | |
1500 | ||
1501 | if (!victim->d_inode) | |
1502 | return -ENOENT; | |
1503 | ||
1504 | BUG_ON(victim->d_parent->d_inode != dir); | |
5a190ae6 | 1505 | audit_inode_child(victim->d_name.name, victim, dir); |
1da177e4 LT |
1506 | |
1507 | error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); | |
1508 | if (error) | |
1509 | return error; | |
1510 | if (IS_APPEND(dir)) | |
1511 | return -EPERM; | |
1512 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
1513 | IS_IMMUTABLE(victim->d_inode)) | |
1514 | return -EPERM; | |
1515 | if (isdir) { | |
1516 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1517 | return -ENOTDIR; | |
1518 | if (IS_ROOT(victim)) | |
1519 | return -EBUSY; | |
1520 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1521 | return -EISDIR; | |
1522 | if (IS_DEADDIR(dir)) | |
1523 | return -ENOENT; | |
1524 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1525 | return -EBUSY; | |
1526 | return 0; | |
1527 | } | |
1528 | ||
1529 | /* Check whether we can create an object with dentry child in directory | |
1530 | * dir. | |
1531 | * 1. We can't do it if child already exists (open has special treatment for | |
1532 | * this case, but since we are inlined it's OK) | |
1533 | * 2. We can't do it if dir is read-only (done in permission()) | |
1534 | * 3. We should have write and exec permissions on dir | |
1535 | * 4. We can't do it if dir is immutable (done in permission()) | |
1536 | */ | |
1537 | static inline int may_create(struct inode *dir, struct dentry *child, | |
1538 | struct nameidata *nd) | |
1539 | { | |
1540 | if (child->d_inode) | |
1541 | return -EEXIST; | |
1542 | if (IS_DEADDIR(dir)) | |
1543 | return -ENOENT; | |
1544 | return permission(dir,MAY_WRITE | MAY_EXEC, nd); | |
1545 | } | |
1546 | ||
1547 | /* | |
1da177e4 LT |
1548 | * O_DIRECTORY translates into forcing a directory lookup. |
1549 | */ | |
1550 | static inline int lookup_flags(unsigned int f) | |
1551 | { | |
1552 | unsigned long retval = LOOKUP_FOLLOW; | |
1553 | ||
1554 | if (f & O_NOFOLLOW) | |
1555 | retval &= ~LOOKUP_FOLLOW; | |
1556 | ||
1da177e4 LT |
1557 | if (f & O_DIRECTORY) |
1558 | retval |= LOOKUP_DIRECTORY; | |
1559 | ||
1560 | return retval; | |
1561 | } | |
1562 | ||
1563 | /* | |
1564 | * p1 and p2 should be directories on the same fs. | |
1565 | */ | |
1566 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1567 | { | |
1568 | struct dentry *p; | |
1569 | ||
1570 | if (p1 == p2) { | |
f2eace23 | 1571 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
1572 | return NULL; |
1573 | } | |
1574 | ||
a11f3a05 | 1575 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1576 | |
1577 | for (p = p1; p->d_parent != p; p = p->d_parent) { | |
1578 | if (p->d_parent == p2) { | |
f2eace23 IM |
1579 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); |
1580 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1581 | return p; |
1582 | } | |
1583 | } | |
1584 | ||
1585 | for (p = p2; p->d_parent != p; p = p->d_parent) { | |
1586 | if (p->d_parent == p1) { | |
f2eace23 IM |
1587 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1588 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1589 | return p; |
1590 | } | |
1591 | } | |
1592 | ||
f2eace23 IM |
1593 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1594 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1595 | return NULL; |
1596 | } | |
1597 | ||
1598 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1599 | { | |
1b1dcc1b | 1600 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1601 | if (p1 != p2) { |
1b1dcc1b | 1602 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 1603 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1604 | } |
1605 | } | |
1606 | ||
1607 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1608 | struct nameidata *nd) | |
1609 | { | |
1610 | int error = may_create(dir, dentry, nd); | |
1611 | ||
1612 | if (error) | |
1613 | return error; | |
1614 | ||
1615 | if (!dir->i_op || !dir->i_op->create) | |
1616 | return -EACCES; /* shouldn't it be ENOSYS? */ | |
1617 | mode &= S_IALLUGO; | |
1618 | mode |= S_IFREG; | |
1619 | error = security_inode_create(dir, dentry, mode); | |
1620 | if (error) | |
1621 | return error; | |
1622 | DQUOT_INIT(dir); | |
1623 | error = dir->i_op->create(dir, dentry, mode, nd); | |
a74574aa | 1624 | if (!error) |
f38aa942 | 1625 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1626 | return error; |
1627 | } | |
1628 | ||
1629 | int may_open(struct nameidata *nd, int acc_mode, int flag) | |
1630 | { | |
4ac91378 | 1631 | struct dentry *dentry = nd->path.dentry; |
1da177e4 LT |
1632 | struct inode *inode = dentry->d_inode; |
1633 | int error; | |
1634 | ||
1635 | if (!inode) | |
1636 | return -ENOENT; | |
1637 | ||
1638 | if (S_ISLNK(inode->i_mode)) | |
1639 | return -ELOOP; | |
1640 | ||
974a9f0b | 1641 | if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) |
1da177e4 LT |
1642 | return -EISDIR; |
1643 | ||
1da177e4 LT |
1644 | /* |
1645 | * FIFO's, sockets and device files are special: they don't | |
1646 | * actually live on the filesystem itself, and as such you | |
1647 | * can write to them even if the filesystem is read-only. | |
1648 | */ | |
1649 | if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { | |
1650 | flag &= ~O_TRUNC; | |
1651 | } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { | |
4ac91378 | 1652 | if (nd->path.mnt->mnt_flags & MNT_NODEV) |
1da177e4 LT |
1653 | return -EACCES; |
1654 | ||
1655 | flag &= ~O_TRUNC; | |
4a3fd211 | 1656 | } |
b41572e9 DH |
1657 | |
1658 | error = vfs_permission(nd, acc_mode); | |
1659 | if (error) | |
1660 | return error; | |
1da177e4 LT |
1661 | /* |
1662 | * An append-only file must be opened in append mode for writing. | |
1663 | */ | |
1664 | if (IS_APPEND(inode)) { | |
1665 | if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) | |
1666 | return -EPERM; | |
1667 | if (flag & O_TRUNC) | |
1668 | return -EPERM; | |
1669 | } | |
1670 | ||
1671 | /* O_NOATIME can only be set by the owner or superuser */ | |
1672 | if (flag & O_NOATIME) | |
3bd858ab | 1673 | if (!is_owner_or_cap(inode)) |
1da177e4 LT |
1674 | return -EPERM; |
1675 | ||
1676 | /* | |
1677 | * Ensure there are no outstanding leases on the file. | |
1678 | */ | |
1679 | error = break_lease(inode, flag); | |
1680 | if (error) | |
1681 | return error; | |
1682 | ||
1683 | if (flag & O_TRUNC) { | |
1684 | error = get_write_access(inode); | |
1685 | if (error) | |
1686 | return error; | |
1687 | ||
1688 | /* | |
1689 | * Refuse to truncate files with mandatory locks held on them. | |
1690 | */ | |
1691 | error = locks_verify_locked(inode); | |
1692 | if (!error) { | |
1693 | DQUOT_INIT(inode); | |
d139d7ff MS |
1694 | |
1695 | error = do_truncate(dentry, 0, | |
1696 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
1697 | NULL); | |
1da177e4 LT |
1698 | } |
1699 | put_write_access(inode); | |
1700 | if (error) | |
1701 | return error; | |
1702 | } else | |
1703 | if (flag & FMODE_WRITE) | |
1704 | DQUOT_INIT(inode); | |
1705 | ||
1706 | return 0; | |
1707 | } | |
1708 | ||
d57999e1 DH |
1709 | /* |
1710 | * Be careful about ever adding any more callers of this | |
1711 | * function. Its flags must be in the namei format, not | |
1712 | * what get passed to sys_open(). | |
1713 | */ | |
1714 | static int __open_namei_create(struct nameidata *nd, struct path *path, | |
aab520e2 DH |
1715 | int flag, int mode) |
1716 | { | |
1717 | int error; | |
4ac91378 | 1718 | struct dentry *dir = nd->path.dentry; |
aab520e2 DH |
1719 | |
1720 | if (!IS_POSIXACL(dir->d_inode)) | |
1721 | mode &= ~current->fs->umask; | |
1722 | error = vfs_create(dir->d_inode, path->dentry, mode, nd); | |
1723 | mutex_unlock(&dir->d_inode->i_mutex); | |
4ac91378 JB |
1724 | dput(nd->path.dentry); |
1725 | nd->path.dentry = path->dentry; | |
aab520e2 DH |
1726 | if (error) |
1727 | return error; | |
1728 | /* Don't check for write permission, don't truncate */ | |
1729 | return may_open(nd, 0, flag & ~O_TRUNC); | |
1730 | } | |
1731 | ||
d57999e1 DH |
1732 | /* |
1733 | * Note that while the flag value (low two bits) for sys_open means: | |
1734 | * 00 - read-only | |
1735 | * 01 - write-only | |
1736 | * 10 - read-write | |
1737 | * 11 - special | |
1738 | * it is changed into | |
1739 | * 00 - no permissions needed | |
1740 | * 01 - read-permission | |
1741 | * 10 - write-permission | |
1742 | * 11 - read-write | |
1743 | * for the internal routines (ie open_namei()/follow_link() etc) | |
1744 | * This is more logical, and also allows the 00 "no perm needed" | |
1745 | * to be used for symlinks (where the permissions are checked | |
1746 | * later). | |
1747 | * | |
1748 | */ | |
1749 | static inline int open_to_namei_flags(int flag) | |
1750 | { | |
1751 | if ((flag+1) & O_ACCMODE) | |
1752 | flag++; | |
1753 | return flag; | |
1754 | } | |
1755 | ||
4a3fd211 DH |
1756 | static int open_will_write_to_fs(int flag, struct inode *inode) |
1757 | { | |
1758 | /* | |
1759 | * We'll never write to the fs underlying | |
1760 | * a device file. | |
1761 | */ | |
1762 | if (special_file(inode->i_mode)) | |
1763 | return 0; | |
1764 | return (flag & O_TRUNC); | |
1765 | } | |
1766 | ||
1da177e4 | 1767 | /* |
4a3fd211 DH |
1768 | * Note that the low bits of the passed in "open_flag" |
1769 | * are not the same as in the local variable "flag". See | |
1770 | * open_to_namei_flags() for more details. | |
1da177e4 | 1771 | */ |
a70e65df CH |
1772 | struct file *do_filp_open(int dfd, const char *pathname, |
1773 | int open_flag, int mode) | |
1da177e4 | 1774 | { |
4a3fd211 | 1775 | struct file *filp; |
a70e65df | 1776 | struct nameidata nd; |
834f2a4a | 1777 | int acc_mode, error; |
4e7506e4 | 1778 | struct path path; |
1da177e4 LT |
1779 | struct dentry *dir; |
1780 | int count = 0; | |
4a3fd211 | 1781 | int will_write; |
d57999e1 | 1782 | int flag = open_to_namei_flags(open_flag); |
1da177e4 LT |
1783 | |
1784 | acc_mode = ACC_MODE(flag); | |
1785 | ||
834f2a4a TM |
1786 | /* O_TRUNC implies we need access checks for write permissions */ |
1787 | if (flag & O_TRUNC) | |
1788 | acc_mode |= MAY_WRITE; | |
1789 | ||
1da177e4 LT |
1790 | /* Allow the LSM permission hook to distinguish append |
1791 | access from general write access. */ | |
1792 | if (flag & O_APPEND) | |
1793 | acc_mode |= MAY_APPEND; | |
1794 | ||
1da177e4 LT |
1795 | /* |
1796 | * The simplest case - just a plain lookup. | |
1797 | */ | |
1798 | if (!(flag & O_CREAT)) { | |
5590ff0d | 1799 | error = path_lookup_open(dfd, pathname, lookup_flags(flag), |
a70e65df | 1800 | &nd, flag); |
1da177e4 | 1801 | if (error) |
a70e65df | 1802 | return ERR_PTR(error); |
1da177e4 LT |
1803 | goto ok; |
1804 | } | |
1805 | ||
1806 | /* | |
1807 | * Create - we need to know the parent. | |
1808 | */ | |
a70e65df CH |
1809 | error = path_lookup_create(dfd, pathname, LOOKUP_PARENT, |
1810 | &nd, flag, mode); | |
1da177e4 | 1811 | if (error) |
a70e65df | 1812 | return ERR_PTR(error); |
1da177e4 LT |
1813 | |
1814 | /* | |
1815 | * We have the parent and last component. First of all, check | |
1816 | * that we are not asked to creat(2) an obvious directory - that | |
1817 | * will not do. | |
1818 | */ | |
1819 | error = -EISDIR; | |
a70e65df | 1820 | if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) |
1da177e4 LT |
1821 | goto exit; |
1822 | ||
a70e65df CH |
1823 | dir = nd.path.dentry; |
1824 | nd.flags &= ~LOOKUP_PARENT; | |
1b1dcc1b | 1825 | mutex_lock(&dir->d_inode->i_mutex); |
a70e65df CH |
1826 | path.dentry = lookup_hash(&nd); |
1827 | path.mnt = nd.path.mnt; | |
1da177e4 LT |
1828 | |
1829 | do_last: | |
4e7506e4 AV |
1830 | error = PTR_ERR(path.dentry); |
1831 | if (IS_ERR(path.dentry)) { | |
1b1dcc1b | 1832 | mutex_unlock(&dir->d_inode->i_mutex); |
1da177e4 LT |
1833 | goto exit; |
1834 | } | |
1835 | ||
a70e65df | 1836 | if (IS_ERR(nd.intent.open.file)) { |
a70e65df | 1837 | error = PTR_ERR(nd.intent.open.file); |
4a3fd211 | 1838 | goto exit_mutex_unlock; |
4af4c52f OD |
1839 | } |
1840 | ||
1da177e4 | 1841 | /* Negative dentry, just create the file */ |
4e7506e4 | 1842 | if (!path.dentry->d_inode) { |
4a3fd211 DH |
1843 | /* |
1844 | * This write is needed to ensure that a | |
1845 | * ro->rw transition does not occur between | |
1846 | * the time when the file is created and when | |
1847 | * a permanent write count is taken through | |
1848 | * the 'struct file' in nameidata_to_filp(). | |
1849 | */ | |
1850 | error = mnt_want_write(nd.path.mnt); | |
1da177e4 | 1851 | if (error) |
4a3fd211 DH |
1852 | goto exit_mutex_unlock; |
1853 | error = __open_namei_create(&nd, &path, flag, mode); | |
1854 | if (error) { | |
1855 | mnt_drop_write(nd.path.mnt); | |
1da177e4 | 1856 | goto exit; |
4a3fd211 DH |
1857 | } |
1858 | filp = nameidata_to_filp(&nd, open_flag); | |
1859 | mnt_drop_write(nd.path.mnt); | |
1860 | return filp; | |
1da177e4 LT |
1861 | } |
1862 | ||
1863 | /* | |
1864 | * It already exists. | |
1865 | */ | |
1b1dcc1b | 1866 | mutex_unlock(&dir->d_inode->i_mutex); |
5a190ae6 | 1867 | audit_inode(pathname, path.dentry); |
1da177e4 LT |
1868 | |
1869 | error = -EEXIST; | |
1870 | if (flag & O_EXCL) | |
1871 | goto exit_dput; | |
1872 | ||
e13b210f | 1873 | if (__follow_mount(&path)) { |
1da177e4 | 1874 | error = -ELOOP; |
ba7a4c1a AV |
1875 | if (flag & O_NOFOLLOW) |
1876 | goto exit_dput; | |
1da177e4 | 1877 | } |
3e2efce0 | 1878 | |
1da177e4 | 1879 | error = -ENOENT; |
4e7506e4 | 1880 | if (!path.dentry->d_inode) |
1da177e4 | 1881 | goto exit_dput; |
4e7506e4 | 1882 | if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) |
1da177e4 LT |
1883 | goto do_link; |
1884 | ||
a70e65df | 1885 | path_to_nameidata(&path, &nd); |
1da177e4 | 1886 | error = -EISDIR; |
4e7506e4 | 1887 | if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) |
1da177e4 LT |
1888 | goto exit; |
1889 | ok: | |
4a3fd211 DH |
1890 | /* |
1891 | * Consider: | |
1892 | * 1. may_open() truncates a file | |
1893 | * 2. a rw->ro mount transition occurs | |
1894 | * 3. nameidata_to_filp() fails due to | |
1895 | * the ro mount. | |
1896 | * That would be inconsistent, and should | |
1897 | * be avoided. Taking this mnt write here | |
1898 | * ensures that (2) can not occur. | |
1899 | */ | |
1900 | will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); | |
1901 | if (will_write) { | |
1902 | error = mnt_want_write(nd.path.mnt); | |
1903 | if (error) | |
1904 | goto exit; | |
1905 | } | |
a70e65df | 1906 | error = may_open(&nd, acc_mode, flag); |
4a3fd211 DH |
1907 | if (error) { |
1908 | if (will_write) | |
1909 | mnt_drop_write(nd.path.mnt); | |
1da177e4 | 1910 | goto exit; |
4a3fd211 DH |
1911 | } |
1912 | filp = nameidata_to_filp(&nd, open_flag); | |
1913 | /* | |
1914 | * It is now safe to drop the mnt write | |
1915 | * because the filp has had a write taken | |
1916 | * on its behalf. | |
1917 | */ | |
1918 | if (will_write) | |
1919 | mnt_drop_write(nd.path.mnt); | |
1920 | return filp; | |
1da177e4 | 1921 | |
4a3fd211 DH |
1922 | exit_mutex_unlock: |
1923 | mutex_unlock(&dir->d_inode->i_mutex); | |
1da177e4 | 1924 | exit_dput: |
a70e65df | 1925 | path_put_conditional(&path, &nd); |
1da177e4 | 1926 | exit: |
a70e65df CH |
1927 | if (!IS_ERR(nd.intent.open.file)) |
1928 | release_open_intent(&nd); | |
1929 | path_put(&nd.path); | |
1930 | return ERR_PTR(error); | |
1da177e4 LT |
1931 | |
1932 | do_link: | |
1933 | error = -ELOOP; | |
1934 | if (flag & O_NOFOLLOW) | |
1935 | goto exit_dput; | |
1936 | /* | |
1937 | * This is subtle. Instead of calling do_follow_link() we do the | |
1938 | * thing by hands. The reason is that this way we have zero link_count | |
1939 | * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. | |
1940 | * After that we have the parent and last component, i.e. | |
1941 | * we are in the same situation as after the first path_walk(). | |
1942 | * Well, almost - if the last component is normal we get its copy | |
1943 | * stored in nd->last.name and we will have to putname() it when we | |
1944 | * are done. Procfs-like symlinks just set LAST_BIND. | |
1945 | */ | |
a70e65df CH |
1946 | nd.flags |= LOOKUP_PARENT; |
1947 | error = security_inode_follow_link(path.dentry, &nd); | |
1da177e4 LT |
1948 | if (error) |
1949 | goto exit_dput; | |
a70e65df | 1950 | error = __do_follow_link(&path, &nd); |
de459215 KK |
1951 | if (error) { |
1952 | /* Does someone understand code flow here? Or it is only | |
1953 | * me so stupid? Anathema to whoever designed this non-sense | |
1954 | * with "intent.open". | |
1955 | */ | |
a70e65df CH |
1956 | release_open_intent(&nd); |
1957 | return ERR_PTR(error); | |
de459215 | 1958 | } |
a70e65df CH |
1959 | nd.flags &= ~LOOKUP_PARENT; |
1960 | if (nd.last_type == LAST_BIND) | |
1da177e4 | 1961 | goto ok; |
1da177e4 | 1962 | error = -EISDIR; |
a70e65df | 1963 | if (nd.last_type != LAST_NORM) |
1da177e4 | 1964 | goto exit; |
a70e65df CH |
1965 | if (nd.last.name[nd.last.len]) { |
1966 | __putname(nd.last.name); | |
1da177e4 LT |
1967 | goto exit; |
1968 | } | |
1969 | error = -ELOOP; | |
1970 | if (count++==32) { | |
a70e65df | 1971 | __putname(nd.last.name); |
1da177e4 LT |
1972 | goto exit; |
1973 | } | |
a70e65df | 1974 | dir = nd.path.dentry; |
1b1dcc1b | 1975 | mutex_lock(&dir->d_inode->i_mutex); |
a70e65df CH |
1976 | path.dentry = lookup_hash(&nd); |
1977 | path.mnt = nd.path.mnt; | |
1978 | __putname(nd.last.name); | |
1da177e4 LT |
1979 | goto do_last; |
1980 | } | |
1981 | ||
a70e65df CH |
1982 | /** |
1983 | * filp_open - open file and return file pointer | |
1984 | * | |
1985 | * @filename: path to open | |
1986 | * @flags: open flags as per the open(2) second argument | |
1987 | * @mode: mode for the new file if O_CREAT is set, else ignored | |
1988 | * | |
1989 | * This is the helper to open a file from kernelspace if you really | |
1990 | * have to. But in generally you should not do this, so please move | |
1991 | * along, nothing to see here.. | |
1992 | */ | |
1993 | struct file *filp_open(const char *filename, int flags, int mode) | |
1994 | { | |
1995 | return do_filp_open(AT_FDCWD, filename, flags, mode); | |
1996 | } | |
1997 | EXPORT_SYMBOL(filp_open); | |
1998 | ||
1da177e4 LT |
1999 | /** |
2000 | * lookup_create - lookup a dentry, creating it if it doesn't exist | |
2001 | * @nd: nameidata info | |
2002 | * @is_dir: directory flag | |
2003 | * | |
2004 | * Simple function to lookup and return a dentry and create it | |
2005 | * if it doesn't exist. Is SMP-safe. | |
c663e5d8 | 2006 | * |
4ac91378 | 2007 | * Returns with nd->path.dentry->d_inode->i_mutex locked. |
1da177e4 LT |
2008 | */ |
2009 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) | |
2010 | { | |
c663e5d8 | 2011 | struct dentry *dentry = ERR_PTR(-EEXIST); |
1da177e4 | 2012 | |
4ac91378 | 2013 | mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
c663e5d8 CH |
2014 | /* |
2015 | * Yucky last component or no last component at all? | |
2016 | * (foo/., foo/.., /////) | |
2017 | */ | |
1da177e4 LT |
2018 | if (nd->last_type != LAST_NORM) |
2019 | goto fail; | |
2020 | nd->flags &= ~LOOKUP_PARENT; | |
a634904a AM |
2021 | nd->flags |= LOOKUP_CREATE; |
2022 | nd->intent.open.flags = O_EXCL; | |
c663e5d8 CH |
2023 | |
2024 | /* | |
2025 | * Do the final lookup. | |
2026 | */ | |
49705b77 | 2027 | dentry = lookup_hash(nd); |
1da177e4 LT |
2028 | if (IS_ERR(dentry)) |
2029 | goto fail; | |
c663e5d8 | 2030 | |
e9baf6e5 AV |
2031 | if (dentry->d_inode) |
2032 | goto eexist; | |
c663e5d8 CH |
2033 | /* |
2034 | * Special case - lookup gave negative, but... we had foo/bar/ | |
2035 | * From the vfs_mknod() POV we just have a negative dentry - | |
2036 | * all is fine. Let's be bastards - you had / on the end, you've | |
2037 | * been asking for (non-existent) directory. -ENOENT for you. | |
2038 | */ | |
e9baf6e5 AV |
2039 | if (unlikely(!is_dir && nd->last.name[nd->last.len])) { |
2040 | dput(dentry); | |
2041 | dentry = ERR_PTR(-ENOENT); | |
2042 | } | |
1da177e4 | 2043 | return dentry; |
e9baf6e5 | 2044 | eexist: |
1da177e4 | 2045 | dput(dentry); |
e9baf6e5 | 2046 | dentry = ERR_PTR(-EEXIST); |
1da177e4 LT |
2047 | fail: |
2048 | return dentry; | |
2049 | } | |
f81a0bff | 2050 | EXPORT_SYMBOL_GPL(lookup_create); |
1da177e4 LT |
2051 | |
2052 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
2053 | { | |
2054 | int error = may_create(dir, dentry, NULL); | |
2055 | ||
2056 | if (error) | |
2057 | return error; | |
2058 | ||
2059 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) | |
2060 | return -EPERM; | |
2061 | ||
2062 | if (!dir->i_op || !dir->i_op->mknod) | |
2063 | return -EPERM; | |
2064 | ||
08ce5f16 SH |
2065 | error = devcgroup_inode_mknod(mode, dev); |
2066 | if (error) | |
2067 | return error; | |
2068 | ||
1da177e4 LT |
2069 | error = security_inode_mknod(dir, dentry, mode, dev); |
2070 | if (error) | |
2071 | return error; | |
2072 | ||
2073 | DQUOT_INIT(dir); | |
2074 | error = dir->i_op->mknod(dir, dentry, mode, dev); | |
a74574aa | 2075 | if (!error) |
f38aa942 | 2076 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2077 | return error; |
2078 | } | |
2079 | ||
463c3197 DH |
2080 | static int may_mknod(mode_t mode) |
2081 | { | |
2082 | switch (mode & S_IFMT) { | |
2083 | case S_IFREG: | |
2084 | case S_IFCHR: | |
2085 | case S_IFBLK: | |
2086 | case S_IFIFO: | |
2087 | case S_IFSOCK: | |
2088 | case 0: /* zero mode translates to S_IFREG */ | |
2089 | return 0; | |
2090 | case S_IFDIR: | |
2091 | return -EPERM; | |
2092 | default: | |
2093 | return -EINVAL; | |
2094 | } | |
2095 | } | |
2096 | ||
5590ff0d UD |
2097 | asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, |
2098 | unsigned dev) | |
1da177e4 LT |
2099 | { |
2100 | int error = 0; | |
2101 | char * tmp; | |
2102 | struct dentry * dentry; | |
2103 | struct nameidata nd; | |
2104 | ||
2105 | if (S_ISDIR(mode)) | |
2106 | return -EPERM; | |
2107 | tmp = getname(filename); | |
2108 | if (IS_ERR(tmp)) | |
2109 | return PTR_ERR(tmp); | |
2110 | ||
5590ff0d | 2111 | error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); |
1da177e4 LT |
2112 | if (error) |
2113 | goto out; | |
2114 | dentry = lookup_create(&nd, 0); | |
463c3197 DH |
2115 | if (IS_ERR(dentry)) { |
2116 | error = PTR_ERR(dentry); | |
2117 | goto out_unlock; | |
2118 | } | |
4ac91378 | 2119 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
1da177e4 | 2120 | mode &= ~current->fs->umask; |
463c3197 DH |
2121 | error = may_mknod(mode); |
2122 | if (error) | |
2123 | goto out_dput; | |
2124 | error = mnt_want_write(nd.path.mnt); | |
2125 | if (error) | |
2126 | goto out_dput; | |
2127 | switch (mode & S_IFMT) { | |
1da177e4 | 2128 | case 0: case S_IFREG: |
4ac91378 | 2129 | error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); |
1da177e4 LT |
2130 | break; |
2131 | case S_IFCHR: case S_IFBLK: | |
4ac91378 | 2132 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
2133 | new_decode_dev(dev)); |
2134 | break; | |
2135 | case S_IFIFO: case S_IFSOCK: | |
4ac91378 | 2136 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 2137 | break; |
1da177e4 | 2138 | } |
463c3197 DH |
2139 | mnt_drop_write(nd.path.mnt); |
2140 | out_dput: | |
2141 | dput(dentry); | |
2142 | out_unlock: | |
4ac91378 | 2143 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2144 | path_put(&nd.path); |
1da177e4 LT |
2145 | out: |
2146 | putname(tmp); | |
2147 | ||
2148 | return error; | |
2149 | } | |
2150 | ||
5590ff0d UD |
2151 | asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) |
2152 | { | |
2153 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
2154 | } | |
2155 | ||
1da177e4 LT |
2156 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2157 | { | |
2158 | int error = may_create(dir, dentry, NULL); | |
2159 | ||
2160 | if (error) | |
2161 | return error; | |
2162 | ||
2163 | if (!dir->i_op || !dir->i_op->mkdir) | |
2164 | return -EPERM; | |
2165 | ||
2166 | mode &= (S_IRWXUGO|S_ISVTX); | |
2167 | error = security_inode_mkdir(dir, dentry, mode); | |
2168 | if (error) | |
2169 | return error; | |
2170 | ||
2171 | DQUOT_INIT(dir); | |
2172 | error = dir->i_op->mkdir(dir, dentry, mode); | |
a74574aa | 2173 | if (!error) |
f38aa942 | 2174 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
2175 | return error; |
2176 | } | |
2177 | ||
5590ff0d | 2178 | asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) |
1da177e4 LT |
2179 | { |
2180 | int error = 0; | |
2181 | char * tmp; | |
6902d925 DH |
2182 | struct dentry *dentry; |
2183 | struct nameidata nd; | |
1da177e4 LT |
2184 | |
2185 | tmp = getname(pathname); | |
2186 | error = PTR_ERR(tmp); | |
6902d925 DH |
2187 | if (IS_ERR(tmp)) |
2188 | goto out_err; | |
1da177e4 | 2189 | |
6902d925 DH |
2190 | error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd); |
2191 | if (error) | |
2192 | goto out; | |
2193 | dentry = lookup_create(&nd, 1); | |
2194 | error = PTR_ERR(dentry); | |
2195 | if (IS_ERR(dentry)) | |
2196 | goto out_unlock; | |
1da177e4 | 2197 | |
4ac91378 | 2198 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
6902d925 | 2199 | mode &= ~current->fs->umask; |
463c3197 DH |
2200 | error = mnt_want_write(nd.path.mnt); |
2201 | if (error) | |
2202 | goto out_dput; | |
4ac91378 | 2203 | error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); |
463c3197 DH |
2204 | mnt_drop_write(nd.path.mnt); |
2205 | out_dput: | |
6902d925 DH |
2206 | dput(dentry); |
2207 | out_unlock: | |
4ac91378 | 2208 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2209 | path_put(&nd.path); |
6902d925 DH |
2210 | out: |
2211 | putname(tmp); | |
2212 | out_err: | |
1da177e4 LT |
2213 | return error; |
2214 | } | |
2215 | ||
5590ff0d UD |
2216 | asmlinkage long sys_mkdir(const char __user *pathname, int mode) |
2217 | { | |
2218 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
2219 | } | |
2220 | ||
1da177e4 LT |
2221 | /* |
2222 | * We try to drop the dentry early: we should have | |
2223 | * a usage count of 2 if we're the only user of this | |
2224 | * dentry, and if that is true (possibly after pruning | |
2225 | * the dcache), then we drop the dentry now. | |
2226 | * | |
2227 | * A low-level filesystem can, if it choses, legally | |
2228 | * do a | |
2229 | * | |
2230 | * if (!d_unhashed(dentry)) | |
2231 | * return -EBUSY; | |
2232 | * | |
2233 | * if it cannot handle the case of removing a directory | |
2234 | * that is still in use by something else.. | |
2235 | */ | |
2236 | void dentry_unhash(struct dentry *dentry) | |
2237 | { | |
2238 | dget(dentry); | |
dc168427 | 2239 | shrink_dcache_parent(dentry); |
1da177e4 LT |
2240 | spin_lock(&dcache_lock); |
2241 | spin_lock(&dentry->d_lock); | |
2242 | if (atomic_read(&dentry->d_count) == 2) | |
2243 | __d_drop(dentry); | |
2244 | spin_unlock(&dentry->d_lock); | |
2245 | spin_unlock(&dcache_lock); | |
2246 | } | |
2247 | ||
2248 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
2249 | { | |
2250 | int error = may_delete(dir, dentry, 1); | |
2251 | ||
2252 | if (error) | |
2253 | return error; | |
2254 | ||
2255 | if (!dir->i_op || !dir->i_op->rmdir) | |
2256 | return -EPERM; | |
2257 | ||
2258 | DQUOT_INIT(dir); | |
2259 | ||
1b1dcc1b | 2260 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2261 | dentry_unhash(dentry); |
2262 | if (d_mountpoint(dentry)) | |
2263 | error = -EBUSY; | |
2264 | else { | |
2265 | error = security_inode_rmdir(dir, dentry); | |
2266 | if (!error) { | |
2267 | error = dir->i_op->rmdir(dir, dentry); | |
2268 | if (!error) | |
2269 | dentry->d_inode->i_flags |= S_DEAD; | |
2270 | } | |
2271 | } | |
1b1dcc1b | 2272 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 | 2273 | if (!error) { |
1da177e4 LT |
2274 | d_delete(dentry); |
2275 | } | |
2276 | dput(dentry); | |
2277 | ||
2278 | return error; | |
2279 | } | |
2280 | ||
5590ff0d | 2281 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
2282 | { |
2283 | int error = 0; | |
2284 | char * name; | |
2285 | struct dentry *dentry; | |
2286 | struct nameidata nd; | |
2287 | ||
2288 | name = getname(pathname); | |
2289 | if(IS_ERR(name)) | |
2290 | return PTR_ERR(name); | |
2291 | ||
5590ff0d | 2292 | error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); |
1da177e4 LT |
2293 | if (error) |
2294 | goto exit; | |
2295 | ||
2296 | switch(nd.last_type) { | |
2297 | case LAST_DOTDOT: | |
2298 | error = -ENOTEMPTY; | |
2299 | goto exit1; | |
2300 | case LAST_DOT: | |
2301 | error = -EINVAL; | |
2302 | goto exit1; | |
2303 | case LAST_ROOT: | |
2304 | error = -EBUSY; | |
2305 | goto exit1; | |
2306 | } | |
4ac91378 | 2307 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2308 | dentry = lookup_hash(&nd); |
1da177e4 | 2309 | error = PTR_ERR(dentry); |
6902d925 DH |
2310 | if (IS_ERR(dentry)) |
2311 | goto exit2; | |
0622753b DH |
2312 | error = mnt_want_write(nd.path.mnt); |
2313 | if (error) | |
2314 | goto exit3; | |
4ac91378 | 2315 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
0622753b DH |
2316 | mnt_drop_write(nd.path.mnt); |
2317 | exit3: | |
6902d925 DH |
2318 | dput(dentry); |
2319 | exit2: | |
4ac91378 | 2320 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2321 | exit1: |
1d957f9b | 2322 | path_put(&nd.path); |
1da177e4 LT |
2323 | exit: |
2324 | putname(name); | |
2325 | return error; | |
2326 | } | |
2327 | ||
5590ff0d UD |
2328 | asmlinkage long sys_rmdir(const char __user *pathname) |
2329 | { | |
2330 | return do_rmdir(AT_FDCWD, pathname); | |
2331 | } | |
2332 | ||
1da177e4 LT |
2333 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2334 | { | |
2335 | int error = may_delete(dir, dentry, 0); | |
2336 | ||
2337 | if (error) | |
2338 | return error; | |
2339 | ||
2340 | if (!dir->i_op || !dir->i_op->unlink) | |
2341 | return -EPERM; | |
2342 | ||
2343 | DQUOT_INIT(dir); | |
2344 | ||
1b1dcc1b | 2345 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2346 | if (d_mountpoint(dentry)) |
2347 | error = -EBUSY; | |
2348 | else { | |
2349 | error = security_inode_unlink(dir, dentry); | |
2350 | if (!error) | |
2351 | error = dir->i_op->unlink(dir, dentry); | |
2352 | } | |
1b1dcc1b | 2353 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2354 | |
2355 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2356 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 2357 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 2358 | d_delete(dentry); |
1da177e4 | 2359 | } |
0eeca283 | 2360 | |
1da177e4 LT |
2361 | return error; |
2362 | } | |
2363 | ||
2364 | /* | |
2365 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2366 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2367 | * writeout happening, and we don't want to prevent access to the directory |
2368 | * while waiting on the I/O. | |
2369 | */ | |
5590ff0d | 2370 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 LT |
2371 | { |
2372 | int error = 0; | |
2373 | char * name; | |
2374 | struct dentry *dentry; | |
2375 | struct nameidata nd; | |
2376 | struct inode *inode = NULL; | |
2377 | ||
2378 | name = getname(pathname); | |
2379 | if(IS_ERR(name)) | |
2380 | return PTR_ERR(name); | |
2381 | ||
5590ff0d | 2382 | error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd); |
1da177e4 LT |
2383 | if (error) |
2384 | goto exit; | |
2385 | error = -EISDIR; | |
2386 | if (nd.last_type != LAST_NORM) | |
2387 | goto exit1; | |
4ac91378 | 2388 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2389 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2390 | error = PTR_ERR(dentry); |
2391 | if (!IS_ERR(dentry)) { | |
2392 | /* Why not before? Because we want correct error value */ | |
2393 | if (nd.last.name[nd.last.len]) | |
2394 | goto slashes; | |
2395 | inode = dentry->d_inode; | |
2396 | if (inode) | |
2397 | atomic_inc(&inode->i_count); | |
0622753b DH |
2398 | error = mnt_want_write(nd.path.mnt); |
2399 | if (error) | |
2400 | goto exit2; | |
4ac91378 | 2401 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
0622753b | 2402 | mnt_drop_write(nd.path.mnt); |
1da177e4 LT |
2403 | exit2: |
2404 | dput(dentry); | |
2405 | } | |
4ac91378 | 2406 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
2407 | if (inode) |
2408 | iput(inode); /* truncate the inode here */ | |
2409 | exit1: | |
1d957f9b | 2410 | path_put(&nd.path); |
1da177e4 LT |
2411 | exit: |
2412 | putname(name); | |
2413 | return error; | |
2414 | ||
2415 | slashes: | |
2416 | error = !dentry->d_inode ? -ENOENT : | |
2417 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2418 | goto exit2; | |
2419 | } | |
2420 | ||
5590ff0d UD |
2421 | asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) |
2422 | { | |
2423 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2424 | return -EINVAL; | |
2425 | ||
2426 | if (flag & AT_REMOVEDIR) | |
2427 | return do_rmdir(dfd, pathname); | |
2428 | ||
2429 | return do_unlinkat(dfd, pathname); | |
2430 | } | |
2431 | ||
2432 | asmlinkage long sys_unlink(const char __user *pathname) | |
2433 | { | |
2434 | return do_unlinkat(AT_FDCWD, pathname); | |
2435 | } | |
2436 | ||
1da177e4 LT |
2437 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) |
2438 | { | |
2439 | int error = may_create(dir, dentry, NULL); | |
2440 | ||
2441 | if (error) | |
2442 | return error; | |
2443 | ||
2444 | if (!dir->i_op || !dir->i_op->symlink) | |
2445 | return -EPERM; | |
2446 | ||
2447 | error = security_inode_symlink(dir, dentry, oldname); | |
2448 | if (error) | |
2449 | return error; | |
2450 | ||
2451 | DQUOT_INIT(dir); | |
2452 | error = dir->i_op->symlink(dir, dentry, oldname); | |
a74574aa | 2453 | if (!error) |
f38aa942 | 2454 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2455 | return error; |
2456 | } | |
2457 | ||
5590ff0d UD |
2458 | asmlinkage long sys_symlinkat(const char __user *oldname, |
2459 | int newdfd, const char __user *newname) | |
1da177e4 LT |
2460 | { |
2461 | int error = 0; | |
2462 | char * from; | |
2463 | char * to; | |
6902d925 DH |
2464 | struct dentry *dentry; |
2465 | struct nameidata nd; | |
1da177e4 LT |
2466 | |
2467 | from = getname(oldname); | |
2468 | if(IS_ERR(from)) | |
2469 | return PTR_ERR(from); | |
2470 | to = getname(newname); | |
2471 | error = PTR_ERR(to); | |
6902d925 DH |
2472 | if (IS_ERR(to)) |
2473 | goto out_putname; | |
1da177e4 | 2474 | |
6902d925 DH |
2475 | error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); |
2476 | if (error) | |
2477 | goto out; | |
2478 | dentry = lookup_create(&nd, 0); | |
2479 | error = PTR_ERR(dentry); | |
2480 | if (IS_ERR(dentry)) | |
2481 | goto out_unlock; | |
2482 | ||
75c3f29d DH |
2483 | error = mnt_want_write(nd.path.mnt); |
2484 | if (error) | |
2485 | goto out_dput; | |
4ac91378 | 2486 | error = vfs_symlink(nd.path.dentry->d_inode, dentry, from, S_IALLUGO); |
75c3f29d DH |
2487 | mnt_drop_write(nd.path.mnt); |
2488 | out_dput: | |
6902d925 DH |
2489 | dput(dentry); |
2490 | out_unlock: | |
4ac91378 | 2491 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2492 | path_put(&nd.path); |
1da177e4 | 2493 | out: |
6902d925 DH |
2494 | putname(to); |
2495 | out_putname: | |
1da177e4 LT |
2496 | putname(from); |
2497 | return error; | |
2498 | } | |
2499 | ||
5590ff0d UD |
2500 | asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) |
2501 | { | |
2502 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2503 | } | |
2504 | ||
1da177e4 LT |
2505 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2506 | { | |
2507 | struct inode *inode = old_dentry->d_inode; | |
2508 | int error; | |
2509 | ||
2510 | if (!inode) | |
2511 | return -ENOENT; | |
2512 | ||
2513 | error = may_create(dir, new_dentry, NULL); | |
2514 | if (error) | |
2515 | return error; | |
2516 | ||
2517 | if (dir->i_sb != inode->i_sb) | |
2518 | return -EXDEV; | |
2519 | ||
2520 | /* | |
2521 | * A link to an append-only or immutable file cannot be created. | |
2522 | */ | |
2523 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2524 | return -EPERM; | |
2525 | if (!dir->i_op || !dir->i_op->link) | |
2526 | return -EPERM; | |
2527 | if (S_ISDIR(old_dentry->d_inode->i_mode)) | |
2528 | return -EPERM; | |
2529 | ||
2530 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2531 | if (error) | |
2532 | return error; | |
2533 | ||
1b1dcc1b | 2534 | mutex_lock(&old_dentry->d_inode->i_mutex); |
1da177e4 LT |
2535 | DQUOT_INIT(dir); |
2536 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
1b1dcc1b | 2537 | mutex_unlock(&old_dentry->d_inode->i_mutex); |
e31e14ec | 2538 | if (!error) |
ece95912 | 2539 | fsnotify_link(dir, old_dentry->d_inode, new_dentry); |
1da177e4 LT |
2540 | return error; |
2541 | } | |
2542 | ||
2543 | /* | |
2544 | * Hardlinks are often used in delicate situations. We avoid | |
2545 | * security-related surprises by not following symlinks on the | |
2546 | * newname. --KAB | |
2547 | * | |
2548 | * We don't follow them on the oldname either to be compatible | |
2549 | * with linux 2.0, and to avoid hard-linking to directories | |
2550 | * and other special files. --ADM | |
2551 | */ | |
5590ff0d | 2552 | asmlinkage long sys_linkat(int olddfd, const char __user *oldname, |
c04030e1 UD |
2553 | int newdfd, const char __user *newname, |
2554 | int flags) | |
1da177e4 LT |
2555 | { |
2556 | struct dentry *new_dentry; | |
2557 | struct nameidata nd, old_nd; | |
2558 | int error; | |
2559 | char * to; | |
2560 | ||
45c9b11a | 2561 | if ((flags & ~AT_SYMLINK_FOLLOW) != 0) |
c04030e1 UD |
2562 | return -EINVAL; |
2563 | ||
1da177e4 LT |
2564 | to = getname(newname); |
2565 | if (IS_ERR(to)) | |
2566 | return PTR_ERR(to); | |
2567 | ||
45c9b11a UD |
2568 | error = __user_walk_fd(olddfd, oldname, |
2569 | flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, | |
2570 | &old_nd); | |
1da177e4 LT |
2571 | if (error) |
2572 | goto exit; | |
5590ff0d | 2573 | error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd); |
1da177e4 LT |
2574 | if (error) |
2575 | goto out; | |
2576 | error = -EXDEV; | |
4ac91378 | 2577 | if (old_nd.path.mnt != nd.path.mnt) |
1da177e4 LT |
2578 | goto out_release; |
2579 | new_dentry = lookup_create(&nd, 0); | |
2580 | error = PTR_ERR(new_dentry); | |
6902d925 DH |
2581 | if (IS_ERR(new_dentry)) |
2582 | goto out_unlock; | |
75c3f29d DH |
2583 | error = mnt_want_write(nd.path.mnt); |
2584 | if (error) | |
2585 | goto out_dput; | |
4ac91378 | 2586 | error = vfs_link(old_nd.path.dentry, nd.path.dentry->d_inode, new_dentry); |
75c3f29d DH |
2587 | mnt_drop_write(nd.path.mnt); |
2588 | out_dput: | |
6902d925 DH |
2589 | dput(new_dentry); |
2590 | out_unlock: | |
4ac91378 | 2591 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2592 | out_release: |
1d957f9b | 2593 | path_put(&nd.path); |
1da177e4 | 2594 | out: |
1d957f9b | 2595 | path_put(&old_nd.path); |
1da177e4 LT |
2596 | exit: |
2597 | putname(to); | |
2598 | ||
2599 | return error; | |
2600 | } | |
2601 | ||
5590ff0d UD |
2602 | asmlinkage long sys_link(const char __user *oldname, const char __user *newname) |
2603 | { | |
c04030e1 | 2604 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2605 | } |
2606 | ||
1da177e4 LT |
2607 | /* |
2608 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2609 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2610 | * Problems: | |
2611 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2612 | * b) race potential - two innocent renames can create a loop together. | |
2613 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 2614 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
2615 | * story. |
2616 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2617 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2618 | * whether the target exists). Solution: try to be smart with locking |
2619 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 2620 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
2621 | * move will be locked. Thus we can rank directories by the tree |
2622 | * (ancestors first) and rank all non-directories after them. | |
2623 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 2624 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
2625 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2626 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2627 | * we'd better make sure that there's no link(2) for them. | |
2628 | * d) some filesystems don't support opened-but-unlinked directories, | |
2629 | * either because of layout or because they are not ready to deal with | |
2630 | * all cases correctly. The latter will be fixed (taking this sort of | |
2631 | * stuff into VFS), but the former is not going away. Solution: the same | |
2632 | * trick as in rmdir(). | |
2633 | * e) conversion from fhandle to dentry may come in the wrong moment - when | |
1b1dcc1b | 2634 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2635 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
1b1dcc1b | 2636 | * ->i_mutex on parents, which works but leads to some truely excessive |
1da177e4 LT |
2637 | * locking]. |
2638 | */ | |
75c96f85 AB |
2639 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2640 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2641 | { |
2642 | int error = 0; | |
2643 | struct inode *target; | |
2644 | ||
2645 | /* | |
2646 | * If we are going to change the parent - check write permissions, | |
2647 | * we'll need to flip '..'. | |
2648 | */ | |
2649 | if (new_dir != old_dir) { | |
2650 | error = permission(old_dentry->d_inode, MAY_WRITE, NULL); | |
2651 | if (error) | |
2652 | return error; | |
2653 | } | |
2654 | ||
2655 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2656 | if (error) | |
2657 | return error; | |
2658 | ||
2659 | target = new_dentry->d_inode; | |
2660 | if (target) { | |
1b1dcc1b | 2661 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2662 | dentry_unhash(new_dentry); |
2663 | } | |
2664 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2665 | error = -EBUSY; | |
2666 | else | |
2667 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2668 | if (target) { | |
2669 | if (!error) | |
2670 | target->i_flags |= S_DEAD; | |
1b1dcc1b | 2671 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2672 | if (d_unhashed(new_dentry)) |
2673 | d_rehash(new_dentry); | |
2674 | dput(new_dentry); | |
2675 | } | |
e31e14ec | 2676 | if (!error) |
349457cc MF |
2677 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
2678 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
2679 | return error; |
2680 | } | |
2681 | ||
75c96f85 AB |
2682 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2683 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2684 | { |
2685 | struct inode *target; | |
2686 | int error; | |
2687 | ||
2688 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2689 | if (error) | |
2690 | return error; | |
2691 | ||
2692 | dget(new_dentry); | |
2693 | target = new_dentry->d_inode; | |
2694 | if (target) | |
1b1dcc1b | 2695 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2696 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2697 | error = -EBUSY; | |
2698 | else | |
2699 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2700 | if (!error) { | |
349457cc | 2701 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
1da177e4 | 2702 | d_move(old_dentry, new_dentry); |
1da177e4 LT |
2703 | } |
2704 | if (target) | |
1b1dcc1b | 2705 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2706 | dput(new_dentry); |
2707 | return error; | |
2708 | } | |
2709 | ||
2710 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2711 | struct inode *new_dir, struct dentry *new_dentry) | |
2712 | { | |
2713 | int error; | |
2714 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
0eeca283 | 2715 | const char *old_name; |
1da177e4 LT |
2716 | |
2717 | if (old_dentry->d_inode == new_dentry->d_inode) | |
2718 | return 0; | |
2719 | ||
2720 | error = may_delete(old_dir, old_dentry, is_dir); | |
2721 | if (error) | |
2722 | return error; | |
2723 | ||
2724 | if (!new_dentry->d_inode) | |
2725 | error = may_create(new_dir, new_dentry, NULL); | |
2726 | else | |
2727 | error = may_delete(new_dir, new_dentry, is_dir); | |
2728 | if (error) | |
2729 | return error; | |
2730 | ||
2731 | if (!old_dir->i_op || !old_dir->i_op->rename) | |
2732 | return -EPERM; | |
2733 | ||
2734 | DQUOT_INIT(old_dir); | |
2735 | DQUOT_INIT(new_dir); | |
2736 | ||
0eeca283 RL |
2737 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
2738 | ||
1da177e4 LT |
2739 | if (is_dir) |
2740 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
2741 | else | |
2742 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
2743 | if (!error) { | |
0eeca283 | 2744 | const char *new_name = old_dentry->d_name.name; |
89204c40 | 2745 | fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, |
5a190ae6 | 2746 | new_dentry->d_inode, old_dentry); |
1da177e4 | 2747 | } |
0eeca283 RL |
2748 | fsnotify_oldname_free(old_name); |
2749 | ||
1da177e4 LT |
2750 | return error; |
2751 | } | |
2752 | ||
5590ff0d UD |
2753 | static int do_rename(int olddfd, const char *oldname, |
2754 | int newdfd, const char *newname) | |
1da177e4 LT |
2755 | { |
2756 | int error = 0; | |
2757 | struct dentry * old_dir, * new_dir; | |
2758 | struct dentry * old_dentry, *new_dentry; | |
2759 | struct dentry * trap; | |
2760 | struct nameidata oldnd, newnd; | |
2761 | ||
5590ff0d | 2762 | error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd); |
1da177e4 LT |
2763 | if (error) |
2764 | goto exit; | |
2765 | ||
5590ff0d | 2766 | error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd); |
1da177e4 LT |
2767 | if (error) |
2768 | goto exit1; | |
2769 | ||
2770 | error = -EXDEV; | |
4ac91378 | 2771 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
2772 | goto exit2; |
2773 | ||
4ac91378 | 2774 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
2775 | error = -EBUSY; |
2776 | if (oldnd.last_type != LAST_NORM) | |
2777 | goto exit2; | |
2778 | ||
4ac91378 | 2779 | new_dir = newnd.path.dentry; |
1da177e4 LT |
2780 | if (newnd.last_type != LAST_NORM) |
2781 | goto exit2; | |
2782 | ||
2783 | trap = lock_rename(new_dir, old_dir); | |
2784 | ||
49705b77 | 2785 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
2786 | error = PTR_ERR(old_dentry); |
2787 | if (IS_ERR(old_dentry)) | |
2788 | goto exit3; | |
2789 | /* source must exist */ | |
2790 | error = -ENOENT; | |
2791 | if (!old_dentry->d_inode) | |
2792 | goto exit4; | |
2793 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
2794 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
2795 | error = -ENOTDIR; | |
2796 | if (oldnd.last.name[oldnd.last.len]) | |
2797 | goto exit4; | |
2798 | if (newnd.last.name[newnd.last.len]) | |
2799 | goto exit4; | |
2800 | } | |
2801 | /* source should not be ancestor of target */ | |
2802 | error = -EINVAL; | |
2803 | if (old_dentry == trap) | |
2804 | goto exit4; | |
49705b77 | 2805 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
2806 | error = PTR_ERR(new_dentry); |
2807 | if (IS_ERR(new_dentry)) | |
2808 | goto exit4; | |
2809 | /* target should not be an ancestor of source */ | |
2810 | error = -ENOTEMPTY; | |
2811 | if (new_dentry == trap) | |
2812 | goto exit5; | |
2813 | ||
9079b1eb DH |
2814 | error = mnt_want_write(oldnd.path.mnt); |
2815 | if (error) | |
2816 | goto exit5; | |
1da177e4 LT |
2817 | error = vfs_rename(old_dir->d_inode, old_dentry, |
2818 | new_dir->d_inode, new_dentry); | |
9079b1eb | 2819 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 LT |
2820 | exit5: |
2821 | dput(new_dentry); | |
2822 | exit4: | |
2823 | dput(old_dentry); | |
2824 | exit3: | |
2825 | unlock_rename(new_dir, old_dir); | |
2826 | exit2: | |
1d957f9b | 2827 | path_put(&newnd.path); |
1da177e4 | 2828 | exit1: |
1d957f9b | 2829 | path_put(&oldnd.path); |
1da177e4 LT |
2830 | exit: |
2831 | return error; | |
2832 | } | |
2833 | ||
5590ff0d UD |
2834 | asmlinkage long sys_renameat(int olddfd, const char __user *oldname, |
2835 | int newdfd, const char __user *newname) | |
1da177e4 LT |
2836 | { |
2837 | int error; | |
2838 | char * from; | |
2839 | char * to; | |
2840 | ||
2841 | from = getname(oldname); | |
2842 | if(IS_ERR(from)) | |
2843 | return PTR_ERR(from); | |
2844 | to = getname(newname); | |
2845 | error = PTR_ERR(to); | |
2846 | if (!IS_ERR(to)) { | |
5590ff0d | 2847 | error = do_rename(olddfd, from, newdfd, to); |
1da177e4 LT |
2848 | putname(to); |
2849 | } | |
2850 | putname(from); | |
2851 | return error; | |
2852 | } | |
2853 | ||
5590ff0d UD |
2854 | asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) |
2855 | { | |
2856 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
2857 | } | |
2858 | ||
1da177e4 LT |
2859 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
2860 | { | |
2861 | int len; | |
2862 | ||
2863 | len = PTR_ERR(link); | |
2864 | if (IS_ERR(link)) | |
2865 | goto out; | |
2866 | ||
2867 | len = strlen(link); | |
2868 | if (len > (unsigned) buflen) | |
2869 | len = buflen; | |
2870 | if (copy_to_user(buffer, link, len)) | |
2871 | len = -EFAULT; | |
2872 | out: | |
2873 | return len; | |
2874 | } | |
2875 | ||
2876 | /* | |
2877 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
2878 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
2879 | * using) it for any given inode is up to filesystem. | |
2880 | */ | |
2881 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2882 | { | |
2883 | struct nameidata nd; | |
cc314eef | 2884 | void *cookie; |
694a1764 | 2885 | int res; |
cc314eef | 2886 | |
1da177e4 | 2887 | nd.depth = 0; |
cc314eef | 2888 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
2889 | if (IS_ERR(cookie)) |
2890 | return PTR_ERR(cookie); | |
2891 | ||
2892 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
2893 | if (dentry->d_inode->i_op->put_link) | |
2894 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
2895 | return res; | |
1da177e4 LT |
2896 | } |
2897 | ||
2898 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
2899 | { | |
2900 | return __vfs_follow_link(nd, link); | |
2901 | } | |
2902 | ||
2903 | /* get the link contents into pagecache */ | |
2904 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
2905 | { | |
2906 | struct page * page; | |
2907 | struct address_space *mapping = dentry->d_inode->i_mapping; | |
090d2b18 | 2908 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 2909 | if (IS_ERR(page)) |
6fe6900e | 2910 | return (char*)page; |
1da177e4 LT |
2911 | *ppage = page; |
2912 | return kmap(page); | |
1da177e4 LT |
2913 | } |
2914 | ||
2915 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2916 | { | |
2917 | struct page *page = NULL; | |
2918 | char *s = page_getlink(dentry, &page); | |
2919 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
2920 | if (page) { | |
2921 | kunmap(page); | |
2922 | page_cache_release(page); | |
2923 | } | |
2924 | return res; | |
2925 | } | |
2926 | ||
cc314eef | 2927 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 2928 | { |
cc314eef | 2929 | struct page *page = NULL; |
1da177e4 | 2930 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 2931 | return page; |
1da177e4 LT |
2932 | } |
2933 | ||
cc314eef | 2934 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 2935 | { |
cc314eef LT |
2936 | struct page *page = cookie; |
2937 | ||
2938 | if (page) { | |
1da177e4 LT |
2939 | kunmap(page); |
2940 | page_cache_release(page); | |
1da177e4 LT |
2941 | } |
2942 | } | |
2943 | ||
0adb25d2 KK |
2944 | int __page_symlink(struct inode *inode, const char *symname, int len, |
2945 | gfp_t gfp_mask) | |
1da177e4 LT |
2946 | { |
2947 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 2948 | struct page *page; |
afddba49 | 2949 | void *fsdata; |
beb497ab | 2950 | int err; |
1da177e4 LT |
2951 | char *kaddr; |
2952 | ||
7e53cac4 | 2953 | retry: |
afddba49 NP |
2954 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
2955 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); | |
1da177e4 | 2956 | if (err) |
afddba49 NP |
2957 | goto fail; |
2958 | ||
1da177e4 LT |
2959 | kaddr = kmap_atomic(page, KM_USER0); |
2960 | memcpy(kaddr, symname, len-1); | |
2961 | kunmap_atomic(kaddr, KM_USER0); | |
afddba49 NP |
2962 | |
2963 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
2964 | page, fsdata); | |
1da177e4 LT |
2965 | if (err < 0) |
2966 | goto fail; | |
afddba49 NP |
2967 | if (err < len-1) |
2968 | goto retry; | |
2969 | ||
1da177e4 LT |
2970 | mark_inode_dirty(inode); |
2971 | return 0; | |
1da177e4 LT |
2972 | fail: |
2973 | return err; | |
2974 | } | |
2975 | ||
0adb25d2 KK |
2976 | int page_symlink(struct inode *inode, const char *symname, int len) |
2977 | { | |
2978 | return __page_symlink(inode, symname, len, | |
2979 | mapping_gfp_mask(inode->i_mapping)); | |
2980 | } | |
2981 | ||
92e1d5be | 2982 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
2983 | .readlink = generic_readlink, |
2984 | .follow_link = page_follow_link_light, | |
2985 | .put_link = page_put_link, | |
2986 | }; | |
2987 | ||
2988 | EXPORT_SYMBOL(__user_walk); | |
5590ff0d | 2989 | EXPORT_SYMBOL(__user_walk_fd); |
1da177e4 LT |
2990 | EXPORT_SYMBOL(follow_down); |
2991 | EXPORT_SYMBOL(follow_up); | |
2992 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
2993 | EXPORT_SYMBOL(getname); | |
2994 | EXPORT_SYMBOL(lock_rename); | |
1da177e4 LT |
2995 | EXPORT_SYMBOL(lookup_one_len); |
2996 | EXPORT_SYMBOL(page_follow_link_light); | |
2997 | EXPORT_SYMBOL(page_put_link); | |
2998 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 2999 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
3000 | EXPORT_SYMBOL(page_symlink); |
3001 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
3002 | EXPORT_SYMBOL(path_lookup); | |
16f18200 | 3003 | EXPORT_SYMBOL(vfs_path_lookup); |
1da177e4 | 3004 | EXPORT_SYMBOL(permission); |
e4543edd | 3005 | EXPORT_SYMBOL(vfs_permission); |
8c744fb8 | 3006 | EXPORT_SYMBOL(file_permission); |
1da177e4 LT |
3007 | EXPORT_SYMBOL(unlock_rename); |
3008 | EXPORT_SYMBOL(vfs_create); | |
3009 | EXPORT_SYMBOL(vfs_follow_link); | |
3010 | EXPORT_SYMBOL(vfs_link); | |
3011 | EXPORT_SYMBOL(vfs_mkdir); | |
3012 | EXPORT_SYMBOL(vfs_mknod); | |
3013 | EXPORT_SYMBOL(generic_permission); | |
3014 | EXPORT_SYMBOL(vfs_readlink); | |
3015 | EXPORT_SYMBOL(vfs_rename); | |
3016 | EXPORT_SYMBOL(vfs_rmdir); | |
3017 | EXPORT_SYMBOL(vfs_symlink); | |
3018 | EXPORT_SYMBOL(vfs_unlink); | |
3019 | EXPORT_SYMBOL(dentry_unhash); | |
3020 | EXPORT_SYMBOL(generic_readlink); |