Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/namei.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 61234 byte(s)
Tag kernel26-2.6.12-alx-r9
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> |
24 | #include <linux/dnotify.h> |
25 | #include <linux/smp_lock.h> |
26 | #include <linux/personality.h> |
27 | #include <linux/security.h> |
28 | #include <linux/syscalls.h> |
29 | #include <linux/mount.h> |
30 | #include <linux/audit.h> |
31 | #include <asm/namei.h> |
32 | #include <asm/uaccess.h> |
33 | |
34 | #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) |
35 | |
36 | /* [Feb-1997 T. Schoebel-Theuer] |
37 | * Fundamental changes in the pathname lookup mechanisms (namei) |
38 | * were necessary because of omirr. The reason is that omirr needs |
39 | * to know the _real_ pathname, not the user-supplied one, in case |
40 | * of symlinks (and also when transname replacements occur). |
41 | * |
42 | * The new code replaces the old recursive symlink resolution with |
43 | * an iterative one (in case of non-nested symlink chains). It does |
44 | * this with calls to <fs>_follow_link(). |
45 | * As a side effect, dir_namei(), _namei() and follow_link() are now |
46 | * replaced with a single function lookup_dentry() that can handle all |
47 | * the special cases of the former code. |
48 | * |
49 | * With the new dcache, the pathname is stored at each inode, at least as |
50 | * long as the refcount of the inode is positive. As a side effect, the |
51 | * size of the dcache depends on the inode cache and thus is dynamic. |
52 | * |
53 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink |
54 | * resolution to correspond with current state of the code. |
55 | * |
56 | * Note that the symlink resolution is not *completely* iterative. |
57 | * There is still a significant amount of tail- and mid- recursion in |
58 | * the algorithm. Also, note that <fs>_readlink() is not used in |
59 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() |
60 | * may return different results than <fs>_follow_link(). Many virtual |
61 | * filesystems (including /proc) exhibit this behavior. |
62 | */ |
63 | |
64 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: |
65 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL |
66 | * and the name already exists in form of a symlink, try to create the new |
67 | * name indicated by the symlink. The old code always complained that the |
68 | * name already exists, due to not following the symlink even if its target |
69 | * is nonexistent. The new semantics affects also mknod() and link() when |
70 | * the name is a symlink pointing to a non-existant name. |
71 | * |
72 | * I don't know which semantics is the right one, since I have no access |
73 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" |
74 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the |
75 | * "old" one. Personally, I think the new semantics is much more logical. |
76 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing |
77 | * file does succeed in both HP-UX and SunOs, but not in Solaris |
78 | * and in the old Linux semantics. |
79 | */ |
80 | |
81 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink |
82 | * semantics. See the comments in "open_namei" and "do_link" below. |
83 | * |
84 | * [10-Sep-98 Alan Modra] Another symlink change. |
85 | */ |
86 | |
87 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: |
88 | * inside the path - always follow. |
89 | * in the last component in creation/removal/renaming - never follow. |
90 | * if LOOKUP_FOLLOW passed - follow. |
91 | * if the pathname has trailing slashes - follow. |
92 | * otherwise - don't follow. |
93 | * (applied in that order). |
94 | * |
95 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT |
96 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. |
97 | * During the 2.4 we need to fix the userland stuff depending on it - |
98 | * hopefully we will be able to get rid of that wart in 2.5. So far only |
99 | * XEmacs seems to be relying on it... |
100 | */ |
101 | /* |
102 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) |
103 | * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives |
104 | * any extra contention... |
105 | */ |
106 | |
107 | /* In order to reduce some races, while at the same time doing additional |
108 | * checking and hopefully speeding things up, we copy filenames to the |
109 | * kernel data space before using them.. |
110 | * |
111 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). |
112 | * PATH_MAX includes the nul terminator --RR. |
113 | */ |
114 | static inline int do_getname(const char __user *filename, char *page) |
115 | { |
116 | int retval; |
117 | unsigned long len = PATH_MAX; |
118 | |
119 | if (!segment_eq(get_fs(), KERNEL_DS)) { |
120 | if ((unsigned long) filename >= TASK_SIZE) |
121 | return -EFAULT; |
122 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) |
123 | len = TASK_SIZE - (unsigned long) filename; |
124 | } |
125 | |
126 | retval = strncpy_from_user(page, filename, len); |
127 | if (retval > 0) { |
128 | if (retval < len) |
129 | return 0; |
130 | return -ENAMETOOLONG; |
131 | } else if (!retval) |
132 | retval = -ENOENT; |
133 | return retval; |
134 | } |
135 | |
136 | char * getname(const char __user * filename) |
137 | { |
138 | char *tmp, *result; |
139 | |
140 | result = ERR_PTR(-ENOMEM); |
141 | tmp = __getname(); |
142 | if (tmp) { |
143 | int retval = do_getname(filename, tmp); |
144 | |
145 | result = tmp; |
146 | if (retval < 0) { |
147 | __putname(tmp); |
148 | result = ERR_PTR(retval); |
149 | } |
150 | } |
151 | audit_getname(result); |
152 | return result; |
153 | } |
154 | |
155 | #ifdef CONFIG_AUDITSYSCALL |
156 | void putname(const char *name) |
157 | { |
158 | if (unlikely(current->audit_context)) |
159 | audit_putname(name); |
160 | else |
161 | __putname(name); |
162 | } |
163 | EXPORT_SYMBOL(putname); |
164 | #endif |
165 | |
166 | |
167 | /** |
168 | * generic_permission - check for access rights on a Posix-like filesystem |
169 | * @inode: inode to check access rights for |
170 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
171 | * @check_acl: optional callback to check for Posix ACLs |
172 | * |
173 | * Used to check for read/write/execute permissions on a file. |
174 | * We use "fsuid" for this, letting us set arbitrary permissions |
175 | * for filesystem access without changing the "normal" uids which |
176 | * are used for other things.. |
177 | */ |
178 | int generic_permission(struct inode *inode, int mask, |
179 | int (*check_acl)(struct inode *inode, int mask)) |
180 | { |
181 | umode_t mode = inode->i_mode; |
182 | |
183 | if (current->fsuid == inode->i_uid) |
184 | mode >>= 6; |
185 | else { |
186 | if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { |
187 | int error = check_acl(inode, mask); |
188 | if (error == -EACCES) |
189 | goto check_capabilities; |
190 | else if (error != -EAGAIN) |
191 | return error; |
192 | } |
193 | |
194 | if (in_group_p(inode->i_gid)) |
195 | mode >>= 3; |
196 | } |
197 | |
198 | /* |
199 | * If the DACs are ok we don't need any capability check. |
200 | */ |
201 | if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)) |
202 | return 0; |
203 | |
204 | check_capabilities: |
205 | /* |
206 | * Read/write DACs are always overridable. |
207 | * Executable DACs are overridable if at least one exec bit is set. |
208 | */ |
209 | if (!(mask & MAY_EXEC) || |
210 | (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) |
211 | if (capable(CAP_DAC_OVERRIDE)) |
212 | return 0; |
213 | |
214 | /* |
215 | * Searching includes executable on directories, else just read. |
216 | */ |
217 | if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) |
218 | if (capable(CAP_DAC_READ_SEARCH)) |
219 | return 0; |
220 | |
221 | return -EACCES; |
222 | } |
223 | |
224 | int permission(struct inode *inode, int mask, struct nameidata *nd) |
225 | { |
226 | int retval, submask; |
227 | |
228 | if (mask & MAY_WRITE) { |
229 | umode_t mode = inode->i_mode; |
230 | |
231 | /* |
232 | * Nobody gets write access to a read-only fs. |
233 | */ |
234 | if (IS_RDONLY(inode) && |
235 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) |
236 | return -EROFS; |
237 | |
238 | /* |
239 | * Nobody gets write access to an immutable file. |
240 | */ |
241 | if (IS_IMMUTABLE(inode)) |
242 | return -EACCES; |
243 | } |
244 | |
245 | |
246 | /* Ordinary permission routines do not understand MAY_APPEND. */ |
247 | submask = mask & ~MAY_APPEND; |
248 | if (inode->i_op && inode->i_op->permission) |
249 | retval = inode->i_op->permission(inode, submask, nd); |
250 | else |
251 | retval = generic_permission(inode, submask, NULL); |
252 | if (retval) |
253 | return retval; |
254 | |
255 | return security_inode_permission(inode, mask, nd); |
256 | } |
257 | |
258 | /* |
259 | * get_write_access() gets write permission for a file. |
260 | * put_write_access() releases this write permission. |
261 | * This is used for regular files. |
262 | * We cannot support write (and maybe mmap read-write shared) accesses and |
263 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode |
264 | * can have the following values: |
265 | * 0: no writers, no VM_DENYWRITE mappings |
266 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist |
267 | * > 0: (i_writecount) users are writing to the file. |
268 | * |
269 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe |
270 | * except for the cases where we don't hold i_writecount yet. Then we need to |
271 | * use {get,deny}_write_access() - these functions check the sign and refuse |
272 | * to do the change if sign is wrong. Exclusion between them is provided by |
273 | * the inode->i_lock spinlock. |
274 | */ |
275 | |
276 | int get_write_access(struct inode * inode) |
277 | { |
278 | spin_lock(&inode->i_lock); |
279 | if (atomic_read(&inode->i_writecount) < 0) { |
280 | spin_unlock(&inode->i_lock); |
281 | return -ETXTBSY; |
282 | } |
283 | atomic_inc(&inode->i_writecount); |
284 | spin_unlock(&inode->i_lock); |
285 | |
286 | return 0; |
287 | } |
288 | |
289 | int deny_write_access(struct file * file) |
290 | { |
291 | struct inode *inode = file->f_dentry->d_inode; |
292 | |
293 | spin_lock(&inode->i_lock); |
294 | if (atomic_read(&inode->i_writecount) > 0) { |
295 | spin_unlock(&inode->i_lock); |
296 | return -ETXTBSY; |
297 | } |
298 | atomic_dec(&inode->i_writecount); |
299 | spin_unlock(&inode->i_lock); |
300 | |
301 | return 0; |
302 | } |
303 | |
304 | void path_release(struct nameidata *nd) |
305 | { |
306 | dput(nd->dentry); |
307 | mntput(nd->mnt); |
308 | } |
309 | |
310 | /* |
311 | * umount() mustn't call path_release()/mntput() as that would clear |
312 | * mnt_expiry_mark |
313 | */ |
314 | void path_release_on_umount(struct nameidata *nd) |
315 | { |
316 | dput(nd->dentry); |
317 | _mntput(nd->mnt); |
318 | } |
319 | |
320 | /* |
321 | * Internal lookup() using the new generic dcache. |
322 | * SMP-safe |
323 | */ |
324 | static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) |
325 | { |
326 | struct dentry * dentry = __d_lookup(parent, name); |
327 | |
328 | /* lockess __d_lookup may fail due to concurrent d_move() |
329 | * in some unrelated directory, so try with d_lookup |
330 | */ |
331 | if (!dentry) |
332 | dentry = d_lookup(parent, name); |
333 | |
334 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) { |
335 | if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) { |
336 | dput(dentry); |
337 | dentry = NULL; |
338 | } |
339 | } |
340 | return dentry; |
341 | } |
342 | |
343 | /* |
344 | * Short-cut version of permission(), for calling by |
345 | * path_walk(), when dcache lock is held. Combines parts |
346 | * of permission() and generic_permission(), and tests ONLY for |
347 | * MAY_EXEC permission. |
348 | * |
349 | * If appropriate, check DAC only. If not appropriate, or |
350 | * short-cut DAC fails, then call permission() to do more |
351 | * complete permission check. |
352 | */ |
353 | static inline int exec_permission_lite(struct inode *inode, |
354 | struct nameidata *nd) |
355 | { |
356 | umode_t mode = inode->i_mode; |
357 | |
358 | if (inode->i_op && inode->i_op->permission) |
359 | return -EAGAIN; |
360 | |
361 | if (current->fsuid == inode->i_uid) |
362 | mode >>= 6; |
363 | else if (in_group_p(inode->i_gid)) |
364 | mode >>= 3; |
365 | |
366 | if (mode & MAY_EXEC) |
367 | goto ok; |
368 | |
369 | if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) |
370 | goto ok; |
371 | |
372 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) |
373 | goto ok; |
374 | |
375 | if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) |
376 | goto ok; |
377 | |
378 | return -EACCES; |
379 | ok: |
380 | return security_inode_permission(inode, MAY_EXEC, nd); |
381 | } |
382 | |
383 | /* |
384 | * This is called when everything else fails, and we actually have |
385 | * to go to the low-level filesystem to find out what we should do.. |
386 | * |
387 | * We get the directory semaphore, and after getting that we also |
388 | * make sure that nobody added the entry to the dcache in the meantime.. |
389 | * SMP-safe |
390 | */ |
391 | static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) |
392 | { |
393 | struct dentry * result; |
394 | struct inode *dir = parent->d_inode; |
395 | |
396 | down(&dir->i_sem); |
397 | /* |
398 | * First re-do the cached lookup just in case it was created |
399 | * while we waited for the directory semaphore.. |
400 | * |
401 | * FIXME! This could use version numbering or similar to |
402 | * avoid unnecessary cache lookups. |
403 | * |
404 | * The "dcache_lock" is purely to protect the RCU list walker |
405 | * from concurrent renames at this point (we mustn't get false |
406 | * negatives from the RCU list walk here, unlike the optimistic |
407 | * fast walk). |
408 | * |
409 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup |
410 | */ |
411 | result = d_lookup(parent, name); |
412 | if (!result) { |
413 | struct dentry * dentry = d_alloc(parent, name); |
414 | result = ERR_PTR(-ENOMEM); |
415 | if (dentry) { |
416 | result = dir->i_op->lookup(dir, dentry, nd); |
417 | if (result) |
418 | dput(dentry); |
419 | else |
420 | result = dentry; |
421 | } |
422 | up(&dir->i_sem); |
423 | return result; |
424 | } |
425 | |
426 | /* |
427 | * Uhhuh! Nasty case: the cache was re-populated while |
428 | * we waited on the semaphore. Need to revalidate. |
429 | */ |
430 | up(&dir->i_sem); |
431 | if (result->d_op && result->d_op->d_revalidate) { |
432 | if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) { |
433 | dput(result); |
434 | result = ERR_PTR(-ENOENT); |
435 | } |
436 | } |
437 | return result; |
438 | } |
439 | |
440 | static int __emul_lookup_dentry(const char *, struct nameidata *); |
441 | |
442 | /* SMP-safe */ |
443 | static inline int |
444 | walk_init_root(const char *name, struct nameidata *nd) |
445 | { |
446 | read_lock(¤t->fs->lock); |
447 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { |
448 | nd->mnt = mntget(current->fs->altrootmnt); |
449 | nd->dentry = dget(current->fs->altroot); |
450 | read_unlock(¤t->fs->lock); |
451 | if (__emul_lookup_dentry(name,nd)) |
452 | return 0; |
453 | read_lock(¤t->fs->lock); |
454 | } |
455 | nd->mnt = mntget(current->fs->rootmnt); |
456 | nd->dentry = dget(current->fs->root); |
457 | read_unlock(¤t->fs->lock); |
458 | return 1; |
459 | } |
460 | |
461 | static inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
462 | { |
463 | int res = 0; |
464 | char *name; |
465 | if (IS_ERR(link)) |
466 | goto fail; |
467 | |
468 | if (*link == '/') { |
469 | path_release(nd); |
470 | if (!walk_init_root(link, nd)) |
471 | /* weird __emul_prefix() stuff did it */ |
472 | goto out; |
473 | } |
474 | res = link_path_walk(link, nd); |
475 | out: |
476 | if (nd->depth || res || nd->last_type!=LAST_NORM) |
477 | return res; |
478 | /* |
479 | * If it is an iterative symlinks resolution in open_namei() we |
480 | * have to copy the last component. And all that crap because of |
481 | * bloody create() on broken symlinks. Furrfu... |
482 | */ |
483 | name = __getname(); |
484 | if (unlikely(!name)) { |
485 | path_release(nd); |
486 | return -ENOMEM; |
487 | } |
488 | strcpy(name, nd->last.name); |
489 | nd->last.name = name; |
490 | return 0; |
491 | fail: |
492 | path_release(nd); |
493 | return PTR_ERR(link); |
494 | } |
495 | |
496 | struct path { |
497 | struct vfsmount *mnt; |
498 | struct dentry *dentry; |
499 | }; |
500 | |
501 | static inline int __do_follow_link(struct path *path, struct nameidata *nd) |
502 | { |
503 | int error; |
504 | struct dentry *dentry = path->dentry; |
505 | |
506 | touch_atime(path->mnt, dentry); |
507 | nd_set_link(nd, NULL); |
508 | |
509 | if (path->mnt == nd->mnt) |
510 | mntget(path->mnt); |
511 | error = dentry->d_inode->i_op->follow_link(dentry, nd); |
512 | if (!error) { |
513 | char *s = nd_get_link(nd); |
514 | if (s) |
515 | error = __vfs_follow_link(nd, s); |
516 | if (dentry->d_inode->i_op->put_link) |
517 | dentry->d_inode->i_op->put_link(dentry, nd); |
518 | } |
519 | dput(dentry); |
520 | mntput(path->mnt); |
521 | |
522 | return error; |
523 | } |
524 | |
525 | /* |
526 | * This limits recursive symlink follows to 8, while |
527 | * limiting consecutive symlinks to 40. |
528 | * |
529 | * Without that kind of total limit, nasty chains of consecutive |
530 | * symlinks can cause almost arbitrarily long lookups. |
531 | */ |
532 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
533 | { |
534 | int err = -ELOOP; |
535 | if (current->link_count >= MAX_NESTED_LINKS) |
536 | goto loop; |
537 | if (current->total_link_count >= 40) |
538 | goto loop; |
539 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
540 | cond_resched(); |
541 | err = security_inode_follow_link(path->dentry, nd); |
542 | if (err) |
543 | goto loop; |
544 | current->link_count++; |
545 | current->total_link_count++; |
546 | nd->depth++; |
547 | err = __do_follow_link(path, nd); |
548 | current->link_count--; |
549 | nd->depth--; |
550 | return err; |
551 | loop: |
552 | dput(path->dentry); |
553 | if (path->mnt != nd->mnt) |
554 | mntput(path->mnt); |
555 | path_release(nd); |
556 | return err; |
557 | } |
558 | |
559 | int follow_up(struct vfsmount **mnt, struct dentry **dentry) |
560 | { |
561 | struct vfsmount *parent; |
562 | struct dentry *mountpoint; |
563 | spin_lock(&vfsmount_lock); |
564 | parent=(*mnt)->mnt_parent; |
565 | if (parent == *mnt) { |
566 | spin_unlock(&vfsmount_lock); |
567 | return 0; |
568 | } |
569 | mntget(parent); |
570 | mountpoint=dget((*mnt)->mnt_mountpoint); |
571 | spin_unlock(&vfsmount_lock); |
572 | dput(*dentry); |
573 | *dentry = mountpoint; |
574 | mntput(*mnt); |
575 | *mnt = parent; |
576 | return 1; |
577 | } |
578 | |
579 | /* no need for dcache_lock, as serialization is taken care in |
580 | * namespace.c |
581 | */ |
582 | static int __follow_mount(struct path *path) |
583 | { |
584 | int res = 0; |
585 | while (d_mountpoint(path->dentry)) { |
586 | struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); |
587 | if (!mounted) |
588 | break; |
589 | dput(path->dentry); |
590 | if (res) |
591 | mntput(path->mnt); |
592 | path->mnt = mounted; |
593 | path->dentry = dget(mounted->mnt_root); |
594 | res = 1; |
595 | } |
596 | return res; |
597 | } |
598 | |
599 | static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) |
600 | { |
601 | while (d_mountpoint(*dentry)) { |
602 | struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); |
603 | if (!mounted) |
604 | break; |
605 | dput(*dentry); |
606 | mntput(*mnt); |
607 | *mnt = mounted; |
608 | *dentry = dget(mounted->mnt_root); |
609 | } |
610 | } |
611 | |
612 | /* no need for dcache_lock, as serialization is taken care in |
613 | * namespace.c |
614 | */ |
615 | int follow_down(struct vfsmount **mnt, struct dentry **dentry) |
616 | { |
617 | struct vfsmount *mounted; |
618 | |
619 | mounted = lookup_mnt(*mnt, *dentry); |
620 | if (mounted) { |
621 | dput(*dentry); |
622 | mntput(*mnt); |
623 | *mnt = mounted; |
624 | *dentry = dget(mounted->mnt_root); |
625 | return 1; |
626 | } |
627 | return 0; |
628 | } |
629 | |
630 | static inline void follow_dotdot(struct nameidata *nd) |
631 | { |
632 | while(1) { |
633 | struct vfsmount *parent; |
634 | struct dentry *old = nd->dentry; |
635 | |
636 | read_lock(¤t->fs->lock); |
637 | if (nd->dentry == current->fs->root && |
638 | nd->mnt == current->fs->rootmnt) { |
639 | read_unlock(¤t->fs->lock); |
640 | break; |
641 | } |
642 | read_unlock(¤t->fs->lock); |
643 | spin_lock(&dcache_lock); |
644 | if (nd->dentry != nd->mnt->mnt_root) { |
645 | nd->dentry = dget(nd->dentry->d_parent); |
646 | spin_unlock(&dcache_lock); |
647 | dput(old); |
648 | break; |
649 | } |
650 | spin_unlock(&dcache_lock); |
651 | spin_lock(&vfsmount_lock); |
652 | parent = nd->mnt->mnt_parent; |
653 | if (parent == nd->mnt) { |
654 | spin_unlock(&vfsmount_lock); |
655 | break; |
656 | } |
657 | mntget(parent); |
658 | nd->dentry = dget(nd->mnt->mnt_mountpoint); |
659 | spin_unlock(&vfsmount_lock); |
660 | dput(old); |
661 | mntput(nd->mnt); |
662 | nd->mnt = parent; |
663 | } |
664 | follow_mount(&nd->mnt, &nd->dentry); |
665 | } |
666 | |
667 | /* |
668 | * It's more convoluted than I'd like it to be, but... it's still fairly |
669 | * small and for now I'd prefer to have fast path as straight as possible. |
670 | * It _is_ time-critical. |
671 | */ |
672 | static int do_lookup(struct nameidata *nd, struct qstr *name, |
673 | struct path *path) |
674 | { |
675 | struct vfsmount *mnt = nd->mnt; |
676 | struct dentry *dentry = __d_lookup(nd->dentry, name); |
677 | |
678 | if (!dentry) |
679 | goto need_lookup; |
680 | if (dentry->d_op && dentry->d_op->d_revalidate) |
681 | goto need_revalidate; |
682 | done: |
683 | path->mnt = mnt; |
684 | path->dentry = dentry; |
685 | __follow_mount(path); |
686 | return 0; |
687 | |
688 | need_lookup: |
689 | dentry = real_lookup(nd->dentry, name, nd); |
690 | if (IS_ERR(dentry)) |
691 | goto fail; |
692 | goto done; |
693 | |
694 | need_revalidate: |
695 | if (dentry->d_op->d_revalidate(dentry, nd)) |
696 | goto done; |
697 | if (d_invalidate(dentry)) |
698 | goto done; |
699 | dput(dentry); |
700 | goto need_lookup; |
701 | |
702 | fail: |
703 | return PTR_ERR(dentry); |
704 | } |
705 | |
706 | /* |
707 | * Name resolution. |
708 | * This is the basic name resolution function, turning a pathname into |
709 | * the final dentry. We expect 'base' to be positive and a directory. |
710 | * |
711 | * Returns 0 and nd will have valid dentry and mnt on success. |
712 | * Returns error and drops reference to input namei data on failure. |
713 | */ |
714 | static fastcall int __link_path_walk(const char * name, struct nameidata *nd) |
715 | { |
716 | struct path next; |
717 | struct inode *inode; |
718 | int err; |
719 | unsigned int lookup_flags = nd->flags; |
720 | |
721 | while (*name=='/') |
722 | name++; |
723 | if (!*name) |
724 | goto return_reval; |
725 | |
726 | inode = nd->dentry->d_inode; |
727 | if (nd->depth) |
728 | lookup_flags = LOOKUP_FOLLOW; |
729 | |
730 | /* At this point we know we have a real path component. */ |
731 | for(;;) { |
732 | unsigned long hash; |
733 | struct qstr this; |
734 | unsigned int c; |
735 | |
736 | err = exec_permission_lite(inode, nd); |
737 | if (err == -EAGAIN) { |
738 | err = permission(inode, MAY_EXEC, nd); |
739 | } |
740 | if (err) |
741 | break; |
742 | |
743 | this.name = name; |
744 | c = *(const unsigned char *)name; |
745 | |
746 | hash = init_name_hash(); |
747 | do { |
748 | name++; |
749 | hash = partial_name_hash(c, hash); |
750 | c = *(const unsigned char *)name; |
751 | } while (c && (c != '/')); |
752 | this.len = name - (const char *) this.name; |
753 | this.hash = end_name_hash(hash); |
754 | |
755 | /* remove trailing slashes? */ |
756 | if (!c) |
757 | goto last_component; |
758 | while (*++name == '/'); |
759 | if (!*name) |
760 | goto last_with_slashes; |
761 | |
762 | /* |
763 | * "." and ".." are special - ".." especially so because it has |
764 | * to be able to know about the current root directory and |
765 | * parent relationships. |
766 | */ |
767 | if (this.name[0] == '.') switch (this.len) { |
768 | default: |
769 | break; |
770 | case 2: |
771 | if (this.name[1] != '.') |
772 | break; |
773 | follow_dotdot(nd); |
774 | inode = nd->dentry->d_inode; |
775 | /* fallthrough */ |
776 | case 1: |
777 | continue; |
778 | } |
779 | /* |
780 | * See if the low-level filesystem might want |
781 | * to use its own hash.. |
782 | */ |
783 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { |
784 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); |
785 | if (err < 0) |
786 | break; |
787 | } |
788 | nd->flags |= LOOKUP_CONTINUE; |
789 | /* This does the actual lookups.. */ |
790 | err = do_lookup(nd, &this, &next); |
791 | if (err) |
792 | break; |
793 | |
794 | err = -ENOENT; |
795 | inode = next.dentry->d_inode; |
796 | if (!inode) |
797 | goto out_dput; |
798 | err = -ENOTDIR; |
799 | if (!inode->i_op) |
800 | goto out_dput; |
801 | |
802 | if (inode->i_op->follow_link) { |
803 | err = do_follow_link(&next, nd); |
804 | if (err) |
805 | goto return_err; |
806 | err = -ENOENT; |
807 | inode = nd->dentry->d_inode; |
808 | if (!inode) |
809 | break; |
810 | err = -ENOTDIR; |
811 | if (!inode->i_op) |
812 | break; |
813 | } else { |
814 | dput(nd->dentry); |
815 | if (nd->mnt != next.mnt) |
816 | mntput(nd->mnt); |
817 | nd->mnt = next.mnt; |
818 | nd->dentry = next.dentry; |
819 | } |
820 | err = -ENOTDIR; |
821 | if (!inode->i_op->lookup) |
822 | break; |
823 | continue; |
824 | /* here ends the main loop */ |
825 | |
826 | last_with_slashes: |
827 | lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; |
828 | last_component: |
829 | nd->flags &= ~LOOKUP_CONTINUE; |
830 | if (lookup_flags & LOOKUP_PARENT) |
831 | goto lookup_parent; |
832 | if (this.name[0] == '.') switch (this.len) { |
833 | default: |
834 | break; |
835 | case 2: |
836 | if (this.name[1] != '.') |
837 | break; |
838 | follow_dotdot(nd); |
839 | inode = nd->dentry->d_inode; |
840 | /* fallthrough */ |
841 | case 1: |
842 | goto return_reval; |
843 | } |
844 | if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { |
845 | err = nd->dentry->d_op->d_hash(nd->dentry, &this); |
846 | if (err < 0) |
847 | break; |
848 | } |
849 | err = do_lookup(nd, &this, &next); |
850 | if (err) |
851 | break; |
852 | inode = next.dentry->d_inode; |
853 | if ((lookup_flags & LOOKUP_FOLLOW) |
854 | && inode && inode->i_op && inode->i_op->follow_link) { |
855 | err = do_follow_link(&next, nd); |
856 | if (err) |
857 | goto return_err; |
858 | inode = nd->dentry->d_inode; |
859 | } else { |
860 | dput(nd->dentry); |
861 | if (nd->mnt != next.mnt) |
862 | mntput(nd->mnt); |
863 | nd->mnt = next.mnt; |
864 | nd->dentry = next.dentry; |
865 | } |
866 | err = -ENOENT; |
867 | if (!inode) |
868 | break; |
869 | if (lookup_flags & LOOKUP_DIRECTORY) { |
870 | err = -ENOTDIR; |
871 | if (!inode->i_op || !inode->i_op->lookup) |
872 | break; |
873 | } |
874 | goto return_base; |
875 | lookup_parent: |
876 | nd->last = this; |
877 | nd->last_type = LAST_NORM; |
878 | if (this.name[0] != '.') |
879 | goto return_base; |
880 | if (this.len == 1) |
881 | nd->last_type = LAST_DOT; |
882 | else if (this.len == 2 && this.name[1] == '.') |
883 | nd->last_type = LAST_DOTDOT; |
884 | else |
885 | goto return_base; |
886 | return_reval: |
887 | /* |
888 | * We bypassed the ordinary revalidation routines. |
889 | * We may need to check the cached dentry for staleness. |
890 | */ |
891 | if (nd->dentry && nd->dentry->d_sb && |
892 | (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { |
893 | err = -ESTALE; |
894 | /* Note: we do not d_invalidate() */ |
895 | if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd)) |
896 | break; |
897 | } |
898 | return_base: |
899 | return 0; |
900 | out_dput: |
901 | dput(next.dentry); |
902 | if (nd->mnt != next.mnt) |
903 | mntput(next.mnt); |
904 | break; |
905 | } |
906 | path_release(nd); |
907 | return_err: |
908 | return err; |
909 | } |
910 | |
911 | /* |
912 | * Wrapper to retry pathname resolution whenever the underlying |
913 | * file system returns an ESTALE. |
914 | * |
915 | * Retry the whole path once, forcing real lookup requests |
916 | * instead of relying on the dcache. |
917 | */ |
918 | int fastcall link_path_walk(const char *name, struct nameidata *nd) |
919 | { |
920 | struct nameidata save = *nd; |
921 | int result; |
922 | |
923 | /* make sure the stuff we saved doesn't go away */ |
924 | dget(save.dentry); |
925 | mntget(save.mnt); |
926 | |
927 | result = __link_path_walk(name, nd); |
928 | if (result == -ESTALE) { |
929 | *nd = save; |
930 | dget(nd->dentry); |
931 | mntget(nd->mnt); |
932 | nd->flags |= LOOKUP_REVAL; |
933 | result = __link_path_walk(name, nd); |
934 | } |
935 | |
936 | dput(save.dentry); |
937 | mntput(save.mnt); |
938 | |
939 | return result; |
940 | } |
941 | |
942 | int fastcall path_walk(const char * name, struct nameidata *nd) |
943 | { |
944 | current->total_link_count = 0; |
945 | return link_path_walk(name, nd); |
946 | } |
947 | |
948 | /* |
949 | * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if |
950 | * everything is done. Returns 0 and drops input nd, if lookup failed; |
951 | */ |
952 | static int __emul_lookup_dentry(const char *name, struct nameidata *nd) |
953 | { |
954 | if (path_walk(name, nd)) |
955 | return 0; /* something went wrong... */ |
956 | |
957 | if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) { |
958 | struct dentry *old_dentry = nd->dentry; |
959 | struct vfsmount *old_mnt = nd->mnt; |
960 | struct qstr last = nd->last; |
961 | int last_type = nd->last_type; |
962 | /* |
963 | * NAME was not found in alternate root or it's a directory. Try to find |
964 | * it in the normal root: |
965 | */ |
966 | nd->last_type = LAST_ROOT; |
967 | read_lock(¤t->fs->lock); |
968 | nd->mnt = mntget(current->fs->rootmnt); |
969 | nd->dentry = dget(current->fs->root); |
970 | read_unlock(¤t->fs->lock); |
971 | if (path_walk(name, nd) == 0) { |
972 | if (nd->dentry->d_inode) { |
973 | dput(old_dentry); |
974 | mntput(old_mnt); |
975 | return 1; |
976 | } |
977 | path_release(nd); |
978 | } |
979 | nd->dentry = old_dentry; |
980 | nd->mnt = old_mnt; |
981 | nd->last = last; |
982 | nd->last_type = last_type; |
983 | } |
984 | return 1; |
985 | } |
986 | |
987 | void set_fs_altroot(void) |
988 | { |
989 | char *emul = __emul_prefix(); |
990 | struct nameidata nd; |
991 | struct vfsmount *mnt = NULL, *oldmnt; |
992 | struct dentry *dentry = NULL, *olddentry; |
993 | int err; |
994 | |
995 | if (!emul) |
996 | goto set_it; |
997 | err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); |
998 | if (!err) { |
999 | mnt = nd.mnt; |
1000 | dentry = nd.dentry; |
1001 | } |
1002 | set_it: |
1003 | write_lock(¤t->fs->lock); |
1004 | oldmnt = current->fs->altrootmnt; |
1005 | olddentry = current->fs->altroot; |
1006 | current->fs->altrootmnt = mnt; |
1007 | current->fs->altroot = dentry; |
1008 | write_unlock(¤t->fs->lock); |
1009 | if (olddentry) { |
1010 | dput(olddentry); |
1011 | mntput(oldmnt); |
1012 | } |
1013 | } |
1014 | |
1015 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
1016 | int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd) |
1017 | { |
1018 | int retval = 0; |
1019 | |
1020 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ |
1021 | nd->flags = flags; |
1022 | nd->depth = 0; |
1023 | |
1024 | read_lock(¤t->fs->lock); |
1025 | if (*name=='/') { |
1026 | if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { |
1027 | nd->mnt = mntget(current->fs->altrootmnt); |
1028 | nd->dentry = dget(current->fs->altroot); |
1029 | read_unlock(¤t->fs->lock); |
1030 | if (__emul_lookup_dentry(name,nd)) |
1031 | goto out; /* found in altroot */ |
1032 | read_lock(¤t->fs->lock); |
1033 | } |
1034 | nd->mnt = mntget(current->fs->rootmnt); |
1035 | nd->dentry = dget(current->fs->root); |
1036 | } else { |
1037 | nd->mnt = mntget(current->fs->pwdmnt); |
1038 | nd->dentry = dget(current->fs->pwd); |
1039 | } |
1040 | read_unlock(¤t->fs->lock); |
1041 | current->total_link_count = 0; |
1042 | retval = link_path_walk(name, nd); |
1043 | out: |
1044 | if (unlikely(current->audit_context |
1045 | && nd && nd->dentry && nd->dentry->d_inode)) |
1046 | audit_inode(name, nd->dentry->d_inode); |
1047 | return retval; |
1048 | } |
1049 | |
1050 | /* |
1051 | * Restricted form of lookup. Doesn't follow links, single-component only, |
1052 | * needs parent already locked. Doesn't follow mounts. |
1053 | * SMP-safe. |
1054 | */ |
1055 | static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd) |
1056 | { |
1057 | struct dentry * dentry; |
1058 | struct inode *inode; |
1059 | int err; |
1060 | |
1061 | inode = base->d_inode; |
1062 | err = permission(inode, MAY_EXEC, nd); |
1063 | dentry = ERR_PTR(err); |
1064 | if (err) |
1065 | goto out; |
1066 | |
1067 | /* |
1068 | * See if the low-level filesystem might want |
1069 | * to use its own hash.. |
1070 | */ |
1071 | if (base->d_op && base->d_op->d_hash) { |
1072 | err = base->d_op->d_hash(base, name); |
1073 | dentry = ERR_PTR(err); |
1074 | if (err < 0) |
1075 | goto out; |
1076 | } |
1077 | |
1078 | dentry = cached_lookup(base, name, nd); |
1079 | if (!dentry) { |
1080 | struct dentry *new = d_alloc(base, name); |
1081 | dentry = ERR_PTR(-ENOMEM); |
1082 | if (!new) |
1083 | goto out; |
1084 | dentry = inode->i_op->lookup(inode, new, nd); |
1085 | if (!dentry) |
1086 | dentry = new; |
1087 | else |
1088 | dput(new); |
1089 | } |
1090 | out: |
1091 | return dentry; |
1092 | } |
1093 | |
1094 | struct dentry * lookup_hash(struct qstr *name, struct dentry * base) |
1095 | { |
1096 | return __lookup_hash(name, base, NULL); |
1097 | } |
1098 | |
1099 | /* SMP-safe */ |
1100 | struct dentry * lookup_one_len(const char * name, struct dentry * base, int len) |
1101 | { |
1102 | unsigned long hash; |
1103 | struct qstr this; |
1104 | unsigned int c; |
1105 | |
1106 | this.name = name; |
1107 | this.len = len; |
1108 | if (!len) |
1109 | goto access; |
1110 | |
1111 | hash = init_name_hash(); |
1112 | while (len--) { |
1113 | c = *(const unsigned char *)name++; |
1114 | if (c == '/' || c == '\0') |
1115 | goto access; |
1116 | hash = partial_name_hash(c, hash); |
1117 | } |
1118 | this.hash = end_name_hash(hash); |
1119 | |
1120 | return lookup_hash(&this, base); |
1121 | access: |
1122 | return ERR_PTR(-EACCES); |
1123 | } |
1124 | |
1125 | /* |
1126 | * namei() |
1127 | * |
1128 | * is used by most simple commands to get the inode of a specified name. |
1129 | * Open, link etc use their own routines, but this is enough for things |
1130 | * like 'chmod' etc. |
1131 | * |
1132 | * namei exists in two versions: namei/lnamei. The only difference is |
1133 | * that namei follows links, while lnamei does not. |
1134 | * SMP-safe |
1135 | */ |
1136 | int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) |
1137 | { |
1138 | char *tmp = getname(name); |
1139 | int err = PTR_ERR(tmp); |
1140 | |
1141 | if (!IS_ERR(tmp)) { |
1142 | err = path_lookup(tmp, flags, nd); |
1143 | putname(tmp); |
1144 | } |
1145 | return err; |
1146 | } |
1147 | |
1148 | /* |
1149 | * It's inline, so penalty for filesystems that don't use sticky bit is |
1150 | * minimal. |
1151 | */ |
1152 | static inline int check_sticky(struct inode *dir, struct inode *inode) |
1153 | { |
1154 | if (!(dir->i_mode & S_ISVTX)) |
1155 | return 0; |
1156 | if (inode->i_uid == current->fsuid) |
1157 | return 0; |
1158 | if (dir->i_uid == current->fsuid) |
1159 | return 0; |
1160 | return !capable(CAP_FOWNER); |
1161 | } |
1162 | |
1163 | /* |
1164 | * Check whether we can remove a link victim from directory dir, check |
1165 | * whether the type of victim is right. |
1166 | * 1. We can't do it if dir is read-only (done in permission()) |
1167 | * 2. We should have write and exec permissions on dir |
1168 | * 3. We can't remove anything from append-only dir |
1169 | * 4. We can't do anything with immutable dir (done in permission()) |
1170 | * 5. If the sticky bit on dir is set we should either |
1171 | * a. be owner of dir, or |
1172 | * b. be owner of victim, or |
1173 | * c. have CAP_FOWNER capability |
1174 | * 6. If the victim is append-only or immutable we can't do antyhing with |
1175 | * links pointing to it. |
1176 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. |
1177 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. |
1178 | * 9. We can't remove a root or mountpoint. |
1179 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by |
1180 | * nfs_async_unlink(). |
1181 | */ |
1182 | static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1183 | { |
1184 | int error; |
1185 | |
1186 | if (!victim->d_inode) |
1187 | return -ENOENT; |
1188 | |
1189 | BUG_ON(victim->d_parent->d_inode != dir); |
1190 | |
1191 | error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); |
1192 | if (error) |
1193 | return error; |
1194 | if (IS_APPEND(dir)) |
1195 | return -EPERM; |
1196 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| |
1197 | IS_IMMUTABLE(victim->d_inode)) |
1198 | return -EPERM; |
1199 | if (isdir) { |
1200 | if (!S_ISDIR(victim->d_inode->i_mode)) |
1201 | return -ENOTDIR; |
1202 | if (IS_ROOT(victim)) |
1203 | return -EBUSY; |
1204 | } else if (S_ISDIR(victim->d_inode->i_mode)) |
1205 | return -EISDIR; |
1206 | if (IS_DEADDIR(dir)) |
1207 | return -ENOENT; |
1208 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) |
1209 | return -EBUSY; |
1210 | return 0; |
1211 | } |
1212 | |
1213 | /* Check whether we can create an object with dentry child in directory |
1214 | * dir. |
1215 | * 1. We can't do it if child already exists (open has special treatment for |
1216 | * this case, but since we are inlined it's OK) |
1217 | * 2. We can't do it if dir is read-only (done in permission()) |
1218 | * 3. We should have write and exec permissions on dir |
1219 | * 4. We can't do it if dir is immutable (done in permission()) |
1220 | */ |
1221 | static inline int may_create(struct inode *dir, struct dentry *child, |
1222 | struct nameidata *nd) |
1223 | { |
1224 | if (child->d_inode) |
1225 | return -EEXIST; |
1226 | if (IS_DEADDIR(dir)) |
1227 | return -ENOENT; |
1228 | return permission(dir,MAY_WRITE | MAY_EXEC, nd); |
1229 | } |
1230 | |
1231 | /* |
1232 | * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security |
1233 | * reasons. |
1234 | * |
1235 | * O_DIRECTORY translates into forcing a directory lookup. |
1236 | */ |
1237 | static inline int lookup_flags(unsigned int f) |
1238 | { |
1239 | unsigned long retval = LOOKUP_FOLLOW; |
1240 | |
1241 | if (f & O_NOFOLLOW) |
1242 | retval &= ~LOOKUP_FOLLOW; |
1243 | |
1244 | if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)) |
1245 | retval &= ~LOOKUP_FOLLOW; |
1246 | |
1247 | if (f & O_DIRECTORY) |
1248 | retval |= LOOKUP_DIRECTORY; |
1249 | |
1250 | return retval; |
1251 | } |
1252 | |
1253 | /* |
1254 | * p1 and p2 should be directories on the same fs. |
1255 | */ |
1256 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) |
1257 | { |
1258 | struct dentry *p; |
1259 | |
1260 | if (p1 == p2) { |
1261 | down(&p1->d_inode->i_sem); |
1262 | return NULL; |
1263 | } |
1264 | |
1265 | down(&p1->d_inode->i_sb->s_vfs_rename_sem); |
1266 | |
1267 | for (p = p1; p->d_parent != p; p = p->d_parent) { |
1268 | if (p->d_parent == p2) { |
1269 | down(&p2->d_inode->i_sem); |
1270 | down(&p1->d_inode->i_sem); |
1271 | return p; |
1272 | } |
1273 | } |
1274 | |
1275 | for (p = p2; p->d_parent != p; p = p->d_parent) { |
1276 | if (p->d_parent == p1) { |
1277 | down(&p1->d_inode->i_sem); |
1278 | down(&p2->d_inode->i_sem); |
1279 | return p; |
1280 | } |
1281 | } |
1282 | |
1283 | down(&p1->d_inode->i_sem); |
1284 | down(&p2->d_inode->i_sem); |
1285 | return NULL; |
1286 | } |
1287 | |
1288 | void unlock_rename(struct dentry *p1, struct dentry *p2) |
1289 | { |
1290 | up(&p1->d_inode->i_sem); |
1291 | if (p1 != p2) { |
1292 | up(&p2->d_inode->i_sem); |
1293 | up(&p1->d_inode->i_sb->s_vfs_rename_sem); |
1294 | } |
1295 | } |
1296 | |
1297 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, |
1298 | struct nameidata *nd) |
1299 | { |
1300 | int error = may_create(dir, dentry, nd); |
1301 | |
1302 | if (error) |
1303 | return error; |
1304 | |
1305 | if (!dir->i_op || !dir->i_op->create) |
1306 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1307 | mode &= S_IALLUGO; |
1308 | mode |= S_IFREG; |
1309 | error = security_inode_create(dir, dentry, mode); |
1310 | if (error) |
1311 | return error; |
1312 | DQUOT_INIT(dir); |
1313 | error = dir->i_op->create(dir, dentry, mode, nd); |
1314 | if (!error) { |
1315 | inode_dir_notify(dir, DN_CREATE); |
1316 | security_inode_post_create(dir, dentry, mode); |
1317 | } |
1318 | return error; |
1319 | } |
1320 | |
1321 | int may_open(struct nameidata *nd, int acc_mode, int flag) |
1322 | { |
1323 | struct dentry *dentry = nd->dentry; |
1324 | struct inode *inode = dentry->d_inode; |
1325 | int error; |
1326 | |
1327 | if (!inode) |
1328 | return -ENOENT; |
1329 | |
1330 | if (S_ISLNK(inode->i_mode)) |
1331 | return -ELOOP; |
1332 | |
1333 | if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE)) |
1334 | return -EISDIR; |
1335 | |
1336 | error = permission(inode, acc_mode, nd); |
1337 | if (error) |
1338 | return error; |
1339 | |
1340 | /* |
1341 | * FIFO's, sockets and device files are special: they don't |
1342 | * actually live on the filesystem itself, and as such you |
1343 | * can write to them even if the filesystem is read-only. |
1344 | */ |
1345 | if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { |
1346 | flag &= ~O_TRUNC; |
1347 | } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { |
1348 | if (nd->mnt->mnt_flags & MNT_NODEV) |
1349 | return -EACCES; |
1350 | |
1351 | flag &= ~O_TRUNC; |
1352 | } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE)) |
1353 | return -EROFS; |
1354 | /* |
1355 | * An append-only file must be opened in append mode for writing. |
1356 | */ |
1357 | if (IS_APPEND(inode)) { |
1358 | if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) |
1359 | return -EPERM; |
1360 | if (flag & O_TRUNC) |
1361 | return -EPERM; |
1362 | } |
1363 | |
1364 | /* O_NOATIME can only be set by the owner or superuser */ |
1365 | if (flag & O_NOATIME) |
1366 | if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) |
1367 | return -EPERM; |
1368 | |
1369 | /* |
1370 | * Ensure there are no outstanding leases on the file. |
1371 | */ |
1372 | error = break_lease(inode, flag); |
1373 | if (error) |
1374 | return error; |
1375 | |
1376 | if (flag & O_TRUNC) { |
1377 | error = get_write_access(inode); |
1378 | if (error) |
1379 | return error; |
1380 | |
1381 | /* |
1382 | * Refuse to truncate files with mandatory locks held on them. |
1383 | */ |
1384 | error = locks_verify_locked(inode); |
1385 | if (!error) { |
1386 | DQUOT_INIT(inode); |
1387 | |
1388 | error = do_truncate(dentry, 0); |
1389 | } |
1390 | put_write_access(inode); |
1391 | if (error) |
1392 | return error; |
1393 | } else |
1394 | if (flag & FMODE_WRITE) |
1395 | DQUOT_INIT(inode); |
1396 | |
1397 | return 0; |
1398 | } |
1399 | |
1400 | /* |
1401 | * open_namei() |
1402 | * |
1403 | * namei for open - this is in fact almost the whole open-routine. |
1404 | * |
1405 | * Note that the low bits of "flag" aren't the same as in the open |
1406 | * system call - they are 00 - no permissions needed |
1407 | * 01 - read permission needed |
1408 | * 10 - write permission needed |
1409 | * 11 - read/write permissions needed |
1410 | * which is a lot more logical, and also allows the "no perm" needed |
1411 | * for symlinks (where the permissions are checked later). |
1412 | * SMP-safe |
1413 | */ |
1414 | int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) |
1415 | { |
1416 | int acc_mode, error = 0; |
1417 | struct path path; |
1418 | struct dentry *dir; |
1419 | int count = 0; |
1420 | |
1421 | acc_mode = ACC_MODE(flag); |
1422 | |
1423 | /* Allow the LSM permission hook to distinguish append |
1424 | access from general write access. */ |
1425 | if (flag & O_APPEND) |
1426 | acc_mode |= MAY_APPEND; |
1427 | |
1428 | /* Fill in the open() intent data */ |
1429 | nd->intent.open.flags = flag; |
1430 | nd->intent.open.create_mode = mode; |
1431 | |
1432 | /* |
1433 | * The simplest case - just a plain lookup. |
1434 | */ |
1435 | if (!(flag & O_CREAT)) { |
1436 | error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd); |
1437 | if (error) |
1438 | return error; |
1439 | goto ok; |
1440 | } |
1441 | |
1442 | /* |
1443 | * Create - we need to know the parent. |
1444 | */ |
1445 | error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd); |
1446 | if (error) |
1447 | return error; |
1448 | |
1449 | /* |
1450 | * We have the parent and last component. First of all, check |
1451 | * that we are not asked to creat(2) an obvious directory - that |
1452 | * will not do. |
1453 | */ |
1454 | error = -EISDIR; |
1455 | if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len]) |
1456 | goto exit; |
1457 | |
1458 | dir = nd->dentry; |
1459 | nd->flags &= ~LOOKUP_PARENT; |
1460 | down(&dir->d_inode->i_sem); |
1461 | path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); |
1462 | path.mnt = nd->mnt; |
1463 | |
1464 | do_last: |
1465 | error = PTR_ERR(path.dentry); |
1466 | if (IS_ERR(path.dentry)) { |
1467 | up(&dir->d_inode->i_sem); |
1468 | goto exit; |
1469 | } |
1470 | |
1471 | /* Negative dentry, just create the file */ |
1472 | if (!path.dentry->d_inode) { |
1473 | if (!IS_POSIXACL(dir->d_inode)) |
1474 | mode &= ~current->fs->umask; |
1475 | error = vfs_create(dir->d_inode, path.dentry, mode, nd); |
1476 | up(&dir->d_inode->i_sem); |
1477 | dput(nd->dentry); |
1478 | nd->dentry = path.dentry; |
1479 | if (error) |
1480 | goto exit; |
1481 | /* Don't check for write permission, don't truncate */ |
1482 | acc_mode = 0; |
1483 | flag &= ~O_TRUNC; |
1484 | goto ok; |
1485 | } |
1486 | |
1487 | /* |
1488 | * It already exists. |
1489 | */ |
1490 | up(&dir->d_inode->i_sem); |
1491 | |
1492 | error = -EEXIST; |
1493 | if (flag & O_EXCL) |
1494 | goto exit_dput; |
1495 | |
1496 | if (__follow_mount(&path)) { |
1497 | error = -ELOOP; |
1498 | if (flag & O_NOFOLLOW) |
1499 | goto exit_dput; |
1500 | } |
1501 | error = -ENOENT; |
1502 | if (!path.dentry->d_inode) |
1503 | goto exit_dput; |
1504 | if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) |
1505 | goto do_link; |
1506 | |
1507 | dput(nd->dentry); |
1508 | nd->dentry = path.dentry; |
1509 | if (nd->mnt != path.mnt) |
1510 | mntput(nd->mnt); |
1511 | nd->mnt = path.mnt; |
1512 | error = -EISDIR; |
1513 | if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) |
1514 | goto exit; |
1515 | ok: |
1516 | error = may_open(nd, acc_mode, flag); |
1517 | if (error) |
1518 | goto exit; |
1519 | return 0; |
1520 | |
1521 | exit_dput: |
1522 | dput(path.dentry); |
1523 | if (nd->mnt != path.mnt) |
1524 | mntput(path.mnt); |
1525 | exit: |
1526 | path_release(nd); |
1527 | return error; |
1528 | |
1529 | do_link: |
1530 | error = -ELOOP; |
1531 | if (flag & O_NOFOLLOW) |
1532 | goto exit_dput; |
1533 | /* |
1534 | * This is subtle. Instead of calling do_follow_link() we do the |
1535 | * thing by hands. The reason is that this way we have zero link_count |
1536 | * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. |
1537 | * After that we have the parent and last component, i.e. |
1538 | * we are in the same situation as after the first path_walk(). |
1539 | * Well, almost - if the last component is normal we get its copy |
1540 | * stored in nd->last.name and we will have to putname() it when we |
1541 | * are done. Procfs-like symlinks just set LAST_BIND. |
1542 | */ |
1543 | nd->flags |= LOOKUP_PARENT; |
1544 | error = security_inode_follow_link(path.dentry, nd); |
1545 | if (error) |
1546 | goto exit_dput; |
1547 | error = __do_follow_link(&path, nd); |
1548 | if (error) |
1549 | return error; |
1550 | nd->flags &= ~LOOKUP_PARENT; |
1551 | if (nd->last_type == LAST_BIND) |
1552 | goto ok; |
1553 | error = -EISDIR; |
1554 | if (nd->last_type != LAST_NORM) |
1555 | goto exit; |
1556 | if (nd->last.name[nd->last.len]) { |
1557 | putname(nd->last.name); |
1558 | goto exit; |
1559 | } |
1560 | error = -ELOOP; |
1561 | if (count++==32) { |
1562 | putname(nd->last.name); |
1563 | goto exit; |
1564 | } |
1565 | dir = nd->dentry; |
1566 | down(&dir->d_inode->i_sem); |
1567 | path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); |
1568 | path.mnt = nd->mnt; |
1569 | putname(nd->last.name); |
1570 | goto do_last; |
1571 | } |
1572 | |
1573 | /** |
1574 | * lookup_create - lookup a dentry, creating it if it doesn't exist |
1575 | * @nd: nameidata info |
1576 | * @is_dir: directory flag |
1577 | * |
1578 | * Simple function to lookup and return a dentry and create it |
1579 | * if it doesn't exist. Is SMP-safe. |
1580 | */ |
1581 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) |
1582 | { |
1583 | struct dentry *dentry; |
1584 | |
1585 | down(&nd->dentry->d_inode->i_sem); |
1586 | dentry = ERR_PTR(-EEXIST); |
1587 | if (nd->last_type != LAST_NORM) |
1588 | goto fail; |
1589 | nd->flags &= ~LOOKUP_PARENT; |
1590 | dentry = lookup_hash(&nd->last, nd->dentry); |
1591 | if (IS_ERR(dentry)) |
1592 | goto fail; |
1593 | if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) |
1594 | goto enoent; |
1595 | return dentry; |
1596 | enoent: |
1597 | dput(dentry); |
1598 | dentry = ERR_PTR(-ENOENT); |
1599 | fail: |
1600 | return dentry; |
1601 | } |
1602 | EXPORT_SYMBOL_GPL(lookup_create); |
1603 | |
1604 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
1605 | { |
1606 | int error = may_create(dir, dentry, NULL); |
1607 | |
1608 | if (error) |
1609 | return error; |
1610 | |
1611 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1612 | return -EPERM; |
1613 | |
1614 | if (!dir->i_op || !dir->i_op->mknod) |
1615 | return -EPERM; |
1616 | |
1617 | error = security_inode_mknod(dir, dentry, mode, dev); |
1618 | if (error) |
1619 | return error; |
1620 | |
1621 | DQUOT_INIT(dir); |
1622 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
1623 | if (!error) { |
1624 | inode_dir_notify(dir, DN_CREATE); |
1625 | security_inode_post_mknod(dir, dentry, mode, dev); |
1626 | } |
1627 | return error; |
1628 | } |
1629 | |
1630 | asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev) |
1631 | { |
1632 | int error = 0; |
1633 | char * tmp; |
1634 | struct dentry * dentry; |
1635 | struct nameidata nd; |
1636 | |
1637 | if (S_ISDIR(mode)) |
1638 | return -EPERM; |
1639 | tmp = getname(filename); |
1640 | if (IS_ERR(tmp)) |
1641 | return PTR_ERR(tmp); |
1642 | |
1643 | error = path_lookup(tmp, LOOKUP_PARENT, &nd); |
1644 | if (error) |
1645 | goto out; |
1646 | dentry = lookup_create(&nd, 0); |
1647 | error = PTR_ERR(dentry); |
1648 | |
1649 | if (!IS_POSIXACL(nd.dentry->d_inode)) |
1650 | mode &= ~current->fs->umask; |
1651 | if (!IS_ERR(dentry)) { |
1652 | switch (mode & S_IFMT) { |
1653 | case 0: case S_IFREG: |
1654 | error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd); |
1655 | break; |
1656 | case S_IFCHR: case S_IFBLK: |
1657 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode, |
1658 | new_decode_dev(dev)); |
1659 | break; |
1660 | case S_IFIFO: case S_IFSOCK: |
1661 | error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0); |
1662 | break; |
1663 | case S_IFDIR: |
1664 | error = -EPERM; |
1665 | break; |
1666 | default: |
1667 | error = -EINVAL; |
1668 | } |
1669 | dput(dentry); |
1670 | } |
1671 | up(&nd.dentry->d_inode->i_sem); |
1672 | path_release(&nd); |
1673 | out: |
1674 | putname(tmp); |
1675 | |
1676 | return error; |
1677 | } |
1678 | |
1679 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
1680 | { |
1681 | int error = may_create(dir, dentry, NULL); |
1682 | |
1683 | if (error) |
1684 | return error; |
1685 | |
1686 | if (!dir->i_op || !dir->i_op->mkdir) |
1687 | return -EPERM; |
1688 | |
1689 | mode &= (S_IRWXUGO|S_ISVTX); |
1690 | error = security_inode_mkdir(dir, dentry, mode); |
1691 | if (error) |
1692 | return error; |
1693 | |
1694 | DQUOT_INIT(dir); |
1695 | error = dir->i_op->mkdir(dir, dentry, mode); |
1696 | if (!error) { |
1697 | inode_dir_notify(dir, DN_CREATE); |
1698 | security_inode_post_mkdir(dir,dentry, mode); |
1699 | } |
1700 | return error; |
1701 | } |
1702 | |
1703 | asmlinkage long sys_mkdir(const char __user * pathname, int mode) |
1704 | { |
1705 | int error = 0; |
1706 | char * tmp; |
1707 | |
1708 | tmp = getname(pathname); |
1709 | error = PTR_ERR(tmp); |
1710 | if (!IS_ERR(tmp)) { |
1711 | struct dentry *dentry; |
1712 | struct nameidata nd; |
1713 | |
1714 | error = path_lookup(tmp, LOOKUP_PARENT, &nd); |
1715 | if (error) |
1716 | goto out; |
1717 | dentry = lookup_create(&nd, 1); |
1718 | error = PTR_ERR(dentry); |
1719 | if (!IS_ERR(dentry)) { |
1720 | if (!IS_POSIXACL(nd.dentry->d_inode)) |
1721 | mode &= ~current->fs->umask; |
1722 | error = vfs_mkdir(nd.dentry->d_inode, dentry, mode); |
1723 | dput(dentry); |
1724 | } |
1725 | up(&nd.dentry->d_inode->i_sem); |
1726 | path_release(&nd); |
1727 | out: |
1728 | putname(tmp); |
1729 | } |
1730 | |
1731 | return error; |
1732 | } |
1733 | |
1734 | /* |
1735 | * We try to drop the dentry early: we should have |
1736 | * a usage count of 2 if we're the only user of this |
1737 | * dentry, and if that is true (possibly after pruning |
1738 | * the dcache), then we drop the dentry now. |
1739 | * |
1740 | * A low-level filesystem can, if it choses, legally |
1741 | * do a |
1742 | * |
1743 | * if (!d_unhashed(dentry)) |
1744 | * return -EBUSY; |
1745 | * |
1746 | * if it cannot handle the case of removing a directory |
1747 | * that is still in use by something else.. |
1748 | */ |
1749 | void dentry_unhash(struct dentry *dentry) |
1750 | { |
1751 | dget(dentry); |
1752 | if (atomic_read(&dentry->d_count)) |
1753 | shrink_dcache_parent(dentry); |
1754 | spin_lock(&dcache_lock); |
1755 | spin_lock(&dentry->d_lock); |
1756 | if (atomic_read(&dentry->d_count) == 2) |
1757 | __d_drop(dentry); |
1758 | spin_unlock(&dentry->d_lock); |
1759 | spin_unlock(&dcache_lock); |
1760 | } |
1761 | |
1762 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) |
1763 | { |
1764 | int error = may_delete(dir, dentry, 1); |
1765 | |
1766 | if (error) |
1767 | return error; |
1768 | |
1769 | if (!dir->i_op || !dir->i_op->rmdir) |
1770 | return -EPERM; |
1771 | |
1772 | DQUOT_INIT(dir); |
1773 | |
1774 | down(&dentry->d_inode->i_sem); |
1775 | dentry_unhash(dentry); |
1776 | if (d_mountpoint(dentry)) |
1777 | error = -EBUSY; |
1778 | else { |
1779 | error = security_inode_rmdir(dir, dentry); |
1780 | if (!error) { |
1781 | error = dir->i_op->rmdir(dir, dentry); |
1782 | if (!error) |
1783 | dentry->d_inode->i_flags |= S_DEAD; |
1784 | } |
1785 | } |
1786 | up(&dentry->d_inode->i_sem); |
1787 | if (!error) { |
1788 | inode_dir_notify(dir, DN_DELETE); |
1789 | d_delete(dentry); |
1790 | } |
1791 | dput(dentry); |
1792 | |
1793 | return error; |
1794 | } |
1795 | |
1796 | asmlinkage long sys_rmdir(const char __user * pathname) |
1797 | { |
1798 | int error = 0; |
1799 | char * name; |
1800 | struct dentry *dentry; |
1801 | struct nameidata nd; |
1802 | |
1803 | name = getname(pathname); |
1804 | if(IS_ERR(name)) |
1805 | return PTR_ERR(name); |
1806 | |
1807 | error = path_lookup(name, LOOKUP_PARENT, &nd); |
1808 | if (error) |
1809 | goto exit; |
1810 | |
1811 | switch(nd.last_type) { |
1812 | case LAST_DOTDOT: |
1813 | error = -ENOTEMPTY; |
1814 | goto exit1; |
1815 | case LAST_DOT: |
1816 | error = -EINVAL; |
1817 | goto exit1; |
1818 | case LAST_ROOT: |
1819 | error = -EBUSY; |
1820 | goto exit1; |
1821 | } |
1822 | down(&nd.dentry->d_inode->i_sem); |
1823 | dentry = lookup_hash(&nd.last, nd.dentry); |
1824 | error = PTR_ERR(dentry); |
1825 | if (!IS_ERR(dentry)) { |
1826 | error = vfs_rmdir(nd.dentry->d_inode, dentry); |
1827 | dput(dentry); |
1828 | } |
1829 | up(&nd.dentry->d_inode->i_sem); |
1830 | exit1: |
1831 | path_release(&nd); |
1832 | exit: |
1833 | putname(name); |
1834 | return error; |
1835 | } |
1836 | |
1837 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
1838 | { |
1839 | int error = may_delete(dir, dentry, 0); |
1840 | |
1841 | if (error) |
1842 | return error; |
1843 | |
1844 | if (!dir->i_op || !dir->i_op->unlink) |
1845 | return -EPERM; |
1846 | |
1847 | DQUOT_INIT(dir); |
1848 | |
1849 | down(&dentry->d_inode->i_sem); |
1850 | if (d_mountpoint(dentry)) |
1851 | error = -EBUSY; |
1852 | else { |
1853 | error = security_inode_unlink(dir, dentry); |
1854 | if (!error) |
1855 | error = dir->i_op->unlink(dir, dentry); |
1856 | } |
1857 | up(&dentry->d_inode->i_sem); |
1858 | |
1859 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ |
1860 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { |
1861 | d_delete(dentry); |
1862 | inode_dir_notify(dir, DN_DELETE); |
1863 | } |
1864 | return error; |
1865 | } |
1866 | |
1867 | /* |
1868 | * Make sure that the actual truncation of the file will occur outside its |
1869 | * directory's i_sem. Truncate can take a long time if there is a lot of |
1870 | * writeout happening, and we don't want to prevent access to the directory |
1871 | * while waiting on the I/O. |
1872 | */ |
1873 | asmlinkage long sys_unlink(const char __user * pathname) |
1874 | { |
1875 | int error = 0; |
1876 | char * name; |
1877 | struct dentry *dentry; |
1878 | struct nameidata nd; |
1879 | struct inode *inode = NULL; |
1880 | |
1881 | name = getname(pathname); |
1882 | if(IS_ERR(name)) |
1883 | return PTR_ERR(name); |
1884 | |
1885 | error = path_lookup(name, LOOKUP_PARENT, &nd); |
1886 | if (error) |
1887 | goto exit; |
1888 | error = -EISDIR; |
1889 | if (nd.last_type != LAST_NORM) |
1890 | goto exit1; |
1891 | down(&nd.dentry->d_inode->i_sem); |
1892 | dentry = lookup_hash(&nd.last, nd.dentry); |
1893 | error = PTR_ERR(dentry); |
1894 | if (!IS_ERR(dentry)) { |
1895 | /* Why not before? Because we want correct error value */ |
1896 | if (nd.last.name[nd.last.len]) |
1897 | goto slashes; |
1898 | inode = dentry->d_inode; |
1899 | if (inode) |
1900 | atomic_inc(&inode->i_count); |
1901 | error = vfs_unlink(nd.dentry->d_inode, dentry); |
1902 | exit2: |
1903 | dput(dentry); |
1904 | } |
1905 | up(&nd.dentry->d_inode->i_sem); |
1906 | if (inode) |
1907 | iput(inode); /* truncate the inode here */ |
1908 | exit1: |
1909 | path_release(&nd); |
1910 | exit: |
1911 | putname(name); |
1912 | return error; |
1913 | |
1914 | slashes: |
1915 | error = !dentry->d_inode ? -ENOENT : |
1916 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; |
1917 | goto exit2; |
1918 | } |
1919 | |
1920 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) |
1921 | { |
1922 | int error = may_create(dir, dentry, NULL); |
1923 | |
1924 | if (error) |
1925 | return error; |
1926 | |
1927 | if (!dir->i_op || !dir->i_op->symlink) |
1928 | return -EPERM; |
1929 | |
1930 | error = security_inode_symlink(dir, dentry, oldname); |
1931 | if (error) |
1932 | return error; |
1933 | |
1934 | DQUOT_INIT(dir); |
1935 | error = dir->i_op->symlink(dir, dentry, oldname); |
1936 | if (!error) { |
1937 | inode_dir_notify(dir, DN_CREATE); |
1938 | security_inode_post_symlink(dir, dentry, oldname); |
1939 | } |
1940 | return error; |
1941 | } |
1942 | |
1943 | asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname) |
1944 | { |
1945 | int error = 0; |
1946 | char * from; |
1947 | char * to; |
1948 | |
1949 | from = getname(oldname); |
1950 | if(IS_ERR(from)) |
1951 | return PTR_ERR(from); |
1952 | to = getname(newname); |
1953 | error = PTR_ERR(to); |
1954 | if (!IS_ERR(to)) { |
1955 | struct dentry *dentry; |
1956 | struct nameidata nd; |
1957 | |
1958 | error = path_lookup(to, LOOKUP_PARENT, &nd); |
1959 | if (error) |
1960 | goto out; |
1961 | dentry = lookup_create(&nd, 0); |
1962 | error = PTR_ERR(dentry); |
1963 | if (!IS_ERR(dentry)) { |
1964 | error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO); |
1965 | dput(dentry); |
1966 | } |
1967 | up(&nd.dentry->d_inode->i_sem); |
1968 | path_release(&nd); |
1969 | out: |
1970 | putname(to); |
1971 | } |
1972 | putname(from); |
1973 | return error; |
1974 | } |
1975 | |
1976 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
1977 | { |
1978 | struct inode *inode = old_dentry->d_inode; |
1979 | int error; |
1980 | |
1981 | if (!inode) |
1982 | return -ENOENT; |
1983 | |
1984 | error = may_create(dir, new_dentry, NULL); |
1985 | if (error) |
1986 | return error; |
1987 | |
1988 | if (dir->i_sb != inode->i_sb) |
1989 | return -EXDEV; |
1990 | |
1991 | /* |
1992 | * A link to an append-only or immutable file cannot be created. |
1993 | */ |
1994 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) |
1995 | return -EPERM; |
1996 | if (!dir->i_op || !dir->i_op->link) |
1997 | return -EPERM; |
1998 | if (S_ISDIR(old_dentry->d_inode->i_mode)) |
1999 | return -EPERM; |
2000 | |
2001 | error = security_inode_link(old_dentry, dir, new_dentry); |
2002 | if (error) |
2003 | return error; |
2004 | |
2005 | down(&old_dentry->d_inode->i_sem); |
2006 | DQUOT_INIT(dir); |
2007 | error = dir->i_op->link(old_dentry, dir, new_dentry); |
2008 | up(&old_dentry->d_inode->i_sem); |
2009 | if (!error) { |
2010 | inode_dir_notify(dir, DN_CREATE); |
2011 | security_inode_post_link(old_dentry, dir, new_dentry); |
2012 | } |
2013 | return error; |
2014 | } |
2015 | |
2016 | /* |
2017 | * Hardlinks are often used in delicate situations. We avoid |
2018 | * security-related surprises by not following symlinks on the |
2019 | * newname. --KAB |
2020 | * |
2021 | * We don't follow them on the oldname either to be compatible |
2022 | * with linux 2.0, and to avoid hard-linking to directories |
2023 | * and other special files. --ADM |
2024 | */ |
2025 | asmlinkage long sys_link(const char __user * oldname, const char __user * newname) |
2026 | { |
2027 | struct dentry *new_dentry; |
2028 | struct nameidata nd, old_nd; |
2029 | int error; |
2030 | char * to; |
2031 | |
2032 | to = getname(newname); |
2033 | if (IS_ERR(to)) |
2034 | return PTR_ERR(to); |
2035 | |
2036 | error = __user_walk(oldname, 0, &old_nd); |
2037 | if (error) |
2038 | goto exit; |
2039 | error = path_lookup(to, LOOKUP_PARENT, &nd); |
2040 | if (error) |
2041 | goto out; |
2042 | error = -EXDEV; |
2043 | if (old_nd.mnt != nd.mnt) |
2044 | goto out_release; |
2045 | new_dentry = lookup_create(&nd, 0); |
2046 | error = PTR_ERR(new_dentry); |
2047 | if (!IS_ERR(new_dentry)) { |
2048 | error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry); |
2049 | dput(new_dentry); |
2050 | } |
2051 | up(&nd.dentry->d_inode->i_sem); |
2052 | out_release: |
2053 | path_release(&nd); |
2054 | out: |
2055 | path_release(&old_nd); |
2056 | exit: |
2057 | putname(to); |
2058 | |
2059 | return error; |
2060 | } |
2061 | |
2062 | /* |
2063 | * The worst of all namespace operations - renaming directory. "Perverted" |
2064 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... |
2065 | * Problems: |
2066 | * a) we can get into loop creation. Check is done in is_subdir(). |
2067 | * b) race potential - two innocent renames can create a loop together. |
2068 | * That's where 4.4 screws up. Current fix: serialization on |
2069 | * sb->s_vfs_rename_sem. We might be more accurate, but that's another |
2070 | * story. |
2071 | * c) we have to lock _three_ objects - parents and victim (if it exists). |
2072 | * And that - after we got ->i_sem on parents (until then we don't know |
2073 | * whether the target exists). Solution: try to be smart with locking |
2074 | * order for inodes. We rely on the fact that tree topology may change |
2075 | * only under ->s_vfs_rename_sem _and_ that parent of the object we |
2076 | * move will be locked. Thus we can rank directories by the tree |
2077 | * (ancestors first) and rank all non-directories after them. |
2078 | * That works since everybody except rename does "lock parent, lookup, |
2079 | * lock child" and rename is under ->s_vfs_rename_sem. |
2080 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2081 | * has no more than 1 dentry. If "hybrid" objects will ever appear, |
2082 | * we'd better make sure that there's no link(2) for them. |
2083 | * d) some filesystems don't support opened-but-unlinked directories, |
2084 | * either because of layout or because they are not ready to deal with |
2085 | * all cases correctly. The latter will be fixed (taking this sort of |
2086 | * stuff into VFS), but the former is not going away. Solution: the same |
2087 | * trick as in rmdir(). |
2088 | * e) conversion from fhandle to dentry may come in the wrong moment - when |
2089 | * we are removing the target. Solution: we will have to grab ->i_sem |
2090 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
2091 | * ->i_sem on parents, which works but leads to some truely excessive |
2092 | * locking]. |
2093 | */ |
2094 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2095 | struct inode *new_dir, struct dentry *new_dentry) |
2096 | { |
2097 | int error = 0; |
2098 | struct inode *target; |
2099 | |
2100 | /* |
2101 | * If we are going to change the parent - check write permissions, |
2102 | * we'll need to flip '..'. |
2103 | */ |
2104 | if (new_dir != old_dir) { |
2105 | error = permission(old_dentry->d_inode, MAY_WRITE, NULL); |
2106 | if (error) |
2107 | return error; |
2108 | } |
2109 | |
2110 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
2111 | if (error) |
2112 | return error; |
2113 | |
2114 | target = new_dentry->d_inode; |
2115 | if (target) { |
2116 | down(&target->i_sem); |
2117 | dentry_unhash(new_dentry); |
2118 | } |
2119 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2120 | error = -EBUSY; |
2121 | else |
2122 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
2123 | if (target) { |
2124 | if (!error) |
2125 | target->i_flags |= S_DEAD; |
2126 | up(&target->i_sem); |
2127 | if (d_unhashed(new_dentry)) |
2128 | d_rehash(new_dentry); |
2129 | dput(new_dentry); |
2130 | } |
2131 | if (!error) { |
2132 | d_move(old_dentry,new_dentry); |
2133 | security_inode_post_rename(old_dir, old_dentry, |
2134 | new_dir, new_dentry); |
2135 | } |
2136 | return error; |
2137 | } |
2138 | |
2139 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2140 | struct inode *new_dir, struct dentry *new_dentry) |
2141 | { |
2142 | struct inode *target; |
2143 | int error; |
2144 | |
2145 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
2146 | if (error) |
2147 | return error; |
2148 | |
2149 | dget(new_dentry); |
2150 | target = new_dentry->d_inode; |
2151 | if (target) |
2152 | down(&target->i_sem); |
2153 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2154 | error = -EBUSY; |
2155 | else |
2156 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
2157 | if (!error) { |
2158 | /* The following d_move() should become unconditional */ |
2159 | if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME)) |
2160 | d_move(old_dentry, new_dentry); |
2161 | security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry); |
2162 | } |
2163 | if (target) |
2164 | up(&target->i_sem); |
2165 | dput(new_dentry); |
2166 | return error; |
2167 | } |
2168 | |
2169 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
2170 | struct inode *new_dir, struct dentry *new_dentry) |
2171 | { |
2172 | int error; |
2173 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); |
2174 | |
2175 | if (old_dentry->d_inode == new_dentry->d_inode) |
2176 | return 0; |
2177 | |
2178 | error = may_delete(old_dir, old_dentry, is_dir); |
2179 | if (error) |
2180 | return error; |
2181 | |
2182 | if (!new_dentry->d_inode) |
2183 | error = may_create(new_dir, new_dentry, NULL); |
2184 | else |
2185 | error = may_delete(new_dir, new_dentry, is_dir); |
2186 | if (error) |
2187 | return error; |
2188 | |
2189 | if (!old_dir->i_op || !old_dir->i_op->rename) |
2190 | return -EPERM; |
2191 | |
2192 | DQUOT_INIT(old_dir); |
2193 | DQUOT_INIT(new_dir); |
2194 | |
2195 | if (is_dir) |
2196 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); |
2197 | else |
2198 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); |
2199 | if (!error) { |
2200 | if (old_dir == new_dir) |
2201 | inode_dir_notify(old_dir, DN_RENAME); |
2202 | else { |
2203 | inode_dir_notify(old_dir, DN_DELETE); |
2204 | inode_dir_notify(new_dir, DN_CREATE); |
2205 | } |
2206 | } |
2207 | return error; |
2208 | } |
2209 | |
2210 | static inline int do_rename(const char * oldname, const char * newname) |
2211 | { |
2212 | int error = 0; |
2213 | struct dentry * old_dir, * new_dir; |
2214 | struct dentry * old_dentry, *new_dentry; |
2215 | struct dentry * trap; |
2216 | struct nameidata oldnd, newnd; |
2217 | |
2218 | error = path_lookup(oldname, LOOKUP_PARENT, &oldnd); |
2219 | if (error) |
2220 | goto exit; |
2221 | |
2222 | error = path_lookup(newname, LOOKUP_PARENT, &newnd); |
2223 | if (error) |
2224 | goto exit1; |
2225 | |
2226 | error = -EXDEV; |
2227 | if (oldnd.mnt != newnd.mnt) |
2228 | goto exit2; |
2229 | |
2230 | old_dir = oldnd.dentry; |
2231 | error = -EBUSY; |
2232 | if (oldnd.last_type != LAST_NORM) |
2233 | goto exit2; |
2234 | |
2235 | new_dir = newnd.dentry; |
2236 | if (newnd.last_type != LAST_NORM) |
2237 | goto exit2; |
2238 | |
2239 | trap = lock_rename(new_dir, old_dir); |
2240 | |
2241 | old_dentry = lookup_hash(&oldnd.last, old_dir); |
2242 | error = PTR_ERR(old_dentry); |
2243 | if (IS_ERR(old_dentry)) |
2244 | goto exit3; |
2245 | /* source must exist */ |
2246 | error = -ENOENT; |
2247 | if (!old_dentry->d_inode) |
2248 | goto exit4; |
2249 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
2250 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { |
2251 | error = -ENOTDIR; |
2252 | if (oldnd.last.name[oldnd.last.len]) |
2253 | goto exit4; |
2254 | if (newnd.last.name[newnd.last.len]) |
2255 | goto exit4; |
2256 | } |
2257 | /* source should not be ancestor of target */ |
2258 | error = -EINVAL; |
2259 | if (old_dentry == trap) |
2260 | goto exit4; |
2261 | new_dentry = lookup_hash(&newnd.last, new_dir); |
2262 | error = PTR_ERR(new_dentry); |
2263 | if (IS_ERR(new_dentry)) |
2264 | goto exit4; |
2265 | /* target should not be an ancestor of source */ |
2266 | error = -ENOTEMPTY; |
2267 | if (new_dentry == trap) |
2268 | goto exit5; |
2269 | |
2270 | error = vfs_rename(old_dir->d_inode, old_dentry, |
2271 | new_dir->d_inode, new_dentry); |
2272 | exit5: |
2273 | dput(new_dentry); |
2274 | exit4: |
2275 | dput(old_dentry); |
2276 | exit3: |
2277 | unlock_rename(new_dir, old_dir); |
2278 | exit2: |
2279 | path_release(&newnd); |
2280 | exit1: |
2281 | path_release(&oldnd); |
2282 | exit: |
2283 | return error; |
2284 | } |
2285 | |
2286 | asmlinkage long sys_rename(const char __user * oldname, const char __user * newname) |
2287 | { |
2288 | int error; |
2289 | char * from; |
2290 | char * to; |
2291 | |
2292 | from = getname(oldname); |
2293 | if(IS_ERR(from)) |
2294 | return PTR_ERR(from); |
2295 | to = getname(newname); |
2296 | error = PTR_ERR(to); |
2297 | if (!IS_ERR(to)) { |
2298 | error = do_rename(from,to); |
2299 | putname(to); |
2300 | } |
2301 | putname(from); |
2302 | return error; |
2303 | } |
2304 | |
2305 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
2306 | { |
2307 | int len; |
2308 | |
2309 | len = PTR_ERR(link); |
2310 | if (IS_ERR(link)) |
2311 | goto out; |
2312 | |
2313 | len = strlen(link); |
2314 | if (len > (unsigned) buflen) |
2315 | len = buflen; |
2316 | if (copy_to_user(buffer, link, len)) |
2317 | len = -EFAULT; |
2318 | out: |
2319 | return len; |
2320 | } |
2321 | |
2322 | /* |
2323 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that |
2324 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not |
2325 | * using) it for any given inode is up to filesystem. |
2326 | */ |
2327 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
2328 | { |
2329 | struct nameidata nd; |
2330 | int res; |
2331 | nd.depth = 0; |
2332 | res = dentry->d_inode->i_op->follow_link(dentry, &nd); |
2333 | if (!res) { |
2334 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); |
2335 | if (dentry->d_inode->i_op->put_link) |
2336 | dentry->d_inode->i_op->put_link(dentry, &nd); |
2337 | } |
2338 | return res; |
2339 | } |
2340 | |
2341 | int vfs_follow_link(struct nameidata *nd, const char *link) |
2342 | { |
2343 | return __vfs_follow_link(nd, link); |
2344 | } |
2345 | |
2346 | /* get the link contents into pagecache */ |
2347 | static char *page_getlink(struct dentry * dentry, struct page **ppage) |
2348 | { |
2349 | struct page * page; |
2350 | struct address_space *mapping = dentry->d_inode->i_mapping; |
2351 | page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage, |
2352 | NULL); |
2353 | if (IS_ERR(page)) |
2354 | goto sync_fail; |
2355 | wait_on_page_locked(page); |
2356 | if (!PageUptodate(page)) |
2357 | goto async_fail; |
2358 | *ppage = page; |
2359 | return kmap(page); |
2360 | |
2361 | async_fail: |
2362 | page_cache_release(page); |
2363 | return ERR_PTR(-EIO); |
2364 | |
2365 | sync_fail: |
2366 | return (char*)page; |
2367 | } |
2368 | |
2369 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
2370 | { |
2371 | struct page *page = NULL; |
2372 | char *s = page_getlink(dentry, &page); |
2373 | int res = vfs_readlink(dentry,buffer,buflen,s); |
2374 | if (page) { |
2375 | kunmap(page); |
2376 | page_cache_release(page); |
2377 | } |
2378 | return res; |
2379 | } |
2380 | |
2381 | int page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
2382 | { |
2383 | struct page *page; |
2384 | nd_set_link(nd, page_getlink(dentry, &page)); |
2385 | return 0; |
2386 | } |
2387 | |
2388 | void page_put_link(struct dentry *dentry, struct nameidata *nd) |
2389 | { |
2390 | if (!IS_ERR(nd_get_link(nd))) { |
2391 | struct page *page; |
2392 | page = find_get_page(dentry->d_inode->i_mapping, 0); |
2393 | if (!page) |
2394 | BUG(); |
2395 | kunmap(page); |
2396 | page_cache_release(page); |
2397 | page_cache_release(page); |
2398 | } |
2399 | } |
2400 | |
2401 | int page_symlink(struct inode *inode, const char *symname, int len) |
2402 | { |
2403 | struct address_space *mapping = inode->i_mapping; |
2404 | struct page *page = grab_cache_page(mapping, 0); |
2405 | int err = -ENOMEM; |
2406 | char *kaddr; |
2407 | |
2408 | if (!page) |
2409 | goto fail; |
2410 | err = mapping->a_ops->prepare_write(NULL, page, 0, len-1); |
2411 | if (err) |
2412 | goto fail_map; |
2413 | kaddr = kmap_atomic(page, KM_USER0); |
2414 | memcpy(kaddr, symname, len-1); |
2415 | kunmap_atomic(kaddr, KM_USER0); |
2416 | mapping->a_ops->commit_write(NULL, page, 0, len-1); |
2417 | /* |
2418 | * Notice that we are _not_ going to block here - end of page is |
2419 | * unmapped, so this will only try to map the rest of page, see |
2420 | * that it is unmapped (typically even will not look into inode - |
2421 | * ->i_size will be enough for everything) and zero it out. |
2422 | * OTOH it's obviously correct and should make the page up-to-date. |
2423 | */ |
2424 | if (!PageUptodate(page)) { |
2425 | err = mapping->a_ops->readpage(NULL, page); |
2426 | wait_on_page_locked(page); |
2427 | } else { |
2428 | unlock_page(page); |
2429 | } |
2430 | page_cache_release(page); |
2431 | if (err < 0) |
2432 | goto fail; |
2433 | mark_inode_dirty(inode); |
2434 | return 0; |
2435 | fail_map: |
2436 | unlock_page(page); |
2437 | page_cache_release(page); |
2438 | fail: |
2439 | return err; |
2440 | } |
2441 | |
2442 | struct inode_operations page_symlink_inode_operations = { |
2443 | .readlink = generic_readlink, |
2444 | .follow_link = page_follow_link_light, |
2445 | .put_link = page_put_link, |
2446 | }; |
2447 | |
2448 | EXPORT_SYMBOL(__user_walk); |
2449 | EXPORT_SYMBOL(follow_down); |
2450 | EXPORT_SYMBOL(follow_up); |
2451 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ |
2452 | EXPORT_SYMBOL(getname); |
2453 | EXPORT_SYMBOL(lock_rename); |
2454 | EXPORT_SYMBOL(lookup_hash); |
2455 | EXPORT_SYMBOL(lookup_one_len); |
2456 | EXPORT_SYMBOL(page_follow_link_light); |
2457 | EXPORT_SYMBOL(page_put_link); |
2458 | EXPORT_SYMBOL(page_readlink); |
2459 | EXPORT_SYMBOL(page_symlink); |
2460 | EXPORT_SYMBOL(page_symlink_inode_operations); |
2461 | EXPORT_SYMBOL(path_lookup); |
2462 | EXPORT_SYMBOL(path_release); |
2463 | EXPORT_SYMBOL(path_walk); |
2464 | EXPORT_SYMBOL(permission); |
2465 | EXPORT_SYMBOL(unlock_rename); |
2466 | EXPORT_SYMBOL(vfs_create); |
2467 | EXPORT_SYMBOL(vfs_follow_link); |
2468 | EXPORT_SYMBOL(vfs_link); |
2469 | EXPORT_SYMBOL(vfs_mkdir); |
2470 | EXPORT_SYMBOL(vfs_mknod); |
2471 | EXPORT_SYMBOL(generic_permission); |
2472 | EXPORT_SYMBOL(vfs_readlink); |
2473 | EXPORT_SYMBOL(vfs_rename); |
2474 | EXPORT_SYMBOL(vfs_rmdir); |
2475 | EXPORT_SYMBOL(vfs_symlink); |
2476 | EXPORT_SYMBOL(vfs_unlink); |
2477 | EXPORT_SYMBOL(dentry_unhash); |
2478 | EXPORT_SYMBOL(generic_readlink); |