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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/namei.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c2454
1 files changed, 2454 insertions, 0 deletions
diff --git a/fs/namei.c b/fs/namei.c
new file mode 100644
index 000000000000..9e4aef2a1a21
--- /dev/null
+++ b/fs/namei.c
@@ -0,0 +1,2454 @@
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 */
114static 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
136char * 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
156void putname(const char *name)
157{
158 if (unlikely(current->audit_context))
159 audit_putname(name);
160 else
161 __putname(name);
162}
163EXPORT_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 */
178int 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
224int 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
276int 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
289int 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
304void 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 */
314void 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 */
324static 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 */
353static 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;
379ok:
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 */
391static 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
440static int __emul_lookup_dentry(const char *, struct nameidata *);
441
442/* SMP-safe */
443static inline int
444walk_init_root(const char *name, struct nameidata *nd)
445{
446 read_lock(&current->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(&current->fs->lock);
451 if (__emul_lookup_dentry(name,nd))
452 return 0;
453 read_lock(&current->fs->lock);
454 }
455 nd->mnt = mntget(current->fs->rootmnt);
456 nd->dentry = dget(current->fs->root);
457 read_unlock(&current->fs->lock);
458 return 1;
459}
460
461static 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);
475out:
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;
491fail:
492 path_release(nd);
493 return PTR_ERR(link);
494}
495
496static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
497{
498 int error;
499
500 touch_atime(nd->mnt, dentry);
501 nd_set_link(nd, NULL);
502 error = dentry->d_inode->i_op->follow_link(dentry, nd);
503 if (!error) {
504 char *s = nd_get_link(nd);
505 if (s)
506 error = __vfs_follow_link(nd, s);
507 if (dentry->d_inode->i_op->put_link)
508 dentry->d_inode->i_op->put_link(dentry, nd);
509 }
510
511 return error;
512}
513
514/*
515 * This limits recursive symlink follows to 8, while
516 * limiting consecutive symlinks to 40.
517 *
518 * Without that kind of total limit, nasty chains of consecutive
519 * symlinks can cause almost arbitrarily long lookups.
520 */
521static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd)
522{
523 int err = -ELOOP;
524 if (current->link_count >= MAX_NESTED_LINKS)
525 goto loop;
526 if (current->total_link_count >= 40)
527 goto loop;
528 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
529 cond_resched();
530 err = security_inode_follow_link(dentry, nd);
531 if (err)
532 goto loop;
533 current->link_count++;
534 current->total_link_count++;
535 nd->depth++;
536 err = __do_follow_link(dentry, nd);
537 current->link_count--;
538 nd->depth--;
539 return err;
540loop:
541 path_release(nd);
542 return err;
543}
544
545int follow_up(struct vfsmount **mnt, struct dentry **dentry)
546{
547 struct vfsmount *parent;
548 struct dentry *mountpoint;
549 spin_lock(&vfsmount_lock);
550 parent=(*mnt)->mnt_parent;
551 if (parent == *mnt) {
552 spin_unlock(&vfsmount_lock);
553 return 0;
554 }
555 mntget(parent);
556 mountpoint=dget((*mnt)->mnt_mountpoint);
557 spin_unlock(&vfsmount_lock);
558 dput(*dentry);
559 *dentry = mountpoint;
560 mntput(*mnt);
561 *mnt = parent;
562 return 1;
563}
564
565/* no need for dcache_lock, as serialization is taken care in
566 * namespace.c
567 */
568static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
569{
570 int res = 0;
571 while (d_mountpoint(*dentry)) {
572 struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
573 if (!mounted)
574 break;
575 mntput(*mnt);
576 *mnt = mounted;
577 dput(*dentry);
578 *dentry = dget(mounted->mnt_root);
579 res = 1;
580 }
581 return res;
582}
583
584/* no need for dcache_lock, as serialization is taken care in
585 * namespace.c
586 */
587static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry)
588{
589 struct vfsmount *mounted;
590
591 mounted = lookup_mnt(*mnt, *dentry);
592 if (mounted) {
593 mntput(*mnt);
594 *mnt = mounted;
595 dput(*dentry);
596 *dentry = dget(mounted->mnt_root);
597 return 1;
598 }
599 return 0;
600}
601
602int follow_down(struct vfsmount **mnt, struct dentry **dentry)
603{
604 return __follow_down(mnt,dentry);
605}
606
607static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
608{
609 while(1) {
610 struct vfsmount *parent;
611 struct dentry *old = *dentry;
612
613 read_lock(&current->fs->lock);
614 if (*dentry == current->fs->root &&
615 *mnt == current->fs->rootmnt) {
616 read_unlock(&current->fs->lock);
617 break;
618 }
619 read_unlock(&current->fs->lock);
620 spin_lock(&dcache_lock);
621 if (*dentry != (*mnt)->mnt_root) {
622 *dentry = dget((*dentry)->d_parent);
623 spin_unlock(&dcache_lock);
624 dput(old);
625 break;
626 }
627 spin_unlock(&dcache_lock);
628 spin_lock(&vfsmount_lock);
629 parent = (*mnt)->mnt_parent;
630 if (parent == *mnt) {
631 spin_unlock(&vfsmount_lock);
632 break;
633 }
634 mntget(parent);
635 *dentry = dget((*mnt)->mnt_mountpoint);
636 spin_unlock(&vfsmount_lock);
637 dput(old);
638 mntput(*mnt);
639 *mnt = parent;
640 }
641 follow_mount(mnt, dentry);
642}
643
644struct path {
645 struct vfsmount *mnt;
646 struct dentry *dentry;
647};
648
649/*
650 * It's more convoluted than I'd like it to be, but... it's still fairly
651 * small and for now I'd prefer to have fast path as straight as possible.
652 * It _is_ time-critical.
653 */
654static int do_lookup(struct nameidata *nd, struct qstr *name,
655 struct path *path)
656{
657 struct vfsmount *mnt = nd->mnt;
658 struct dentry *dentry = __d_lookup(nd->dentry, name);
659
660 if (!dentry)
661 goto need_lookup;
662 if (dentry->d_op && dentry->d_op->d_revalidate)
663 goto need_revalidate;
664done:
665 path->mnt = mnt;
666 path->dentry = dentry;
667 return 0;
668
669need_lookup:
670 dentry = real_lookup(nd->dentry, name, nd);
671 if (IS_ERR(dentry))
672 goto fail;
673 goto done;
674
675need_revalidate:
676 if (dentry->d_op->d_revalidate(dentry, nd))
677 goto done;
678 if (d_invalidate(dentry))
679 goto done;
680 dput(dentry);
681 goto need_lookup;
682
683fail:
684 return PTR_ERR(dentry);
685}
686
687/*
688 * Name resolution.
689 *
690 * This is the basic name resolution function, turning a pathname
691 * into the final dentry.
692 *
693 * We expect 'base' to be positive and a directory.
694 */
695static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
696{
697 struct path next;
698 struct inode *inode;
699 int err;
700 unsigned int lookup_flags = nd->flags;
701
702 while (*name=='/')
703 name++;
704 if (!*name)
705 goto return_reval;
706
707 inode = nd->dentry->d_inode;
708 if (nd->depth)
709 lookup_flags = LOOKUP_FOLLOW;
710
711 /* At this point we know we have a real path component. */
712 for(;;) {
713 unsigned long hash;
714 struct qstr this;
715 unsigned int c;
716
717 err = exec_permission_lite(inode, nd);
718 if (err == -EAGAIN) {
719 err = permission(inode, MAY_EXEC, nd);
720 }
721 if (err)
722 break;
723
724 this.name = name;
725 c = *(const unsigned char *)name;
726
727 hash = init_name_hash();
728 do {
729 name++;
730 hash = partial_name_hash(c, hash);
731 c = *(const unsigned char *)name;
732 } while (c && (c != '/'));
733 this.len = name - (const char *) this.name;
734 this.hash = end_name_hash(hash);
735
736 /* remove trailing slashes? */
737 if (!c)
738 goto last_component;
739 while (*++name == '/');
740 if (!*name)
741 goto last_with_slashes;
742
743 /*
744 * "." and ".." are special - ".." especially so because it has
745 * to be able to know about the current root directory and
746 * parent relationships.
747 */
748 if (this.name[0] == '.') switch (this.len) {
749 default:
750 break;
751 case 2:
752 if (this.name[1] != '.')
753 break;
754 follow_dotdot(&nd->mnt, &nd->dentry);
755 inode = nd->dentry->d_inode;
756 /* fallthrough */
757 case 1:
758 continue;
759 }
760 /*
761 * See if the low-level filesystem might want
762 * to use its own hash..
763 */
764 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
765 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
766 if (err < 0)
767 break;
768 }
769 nd->flags |= LOOKUP_CONTINUE;
770 /* This does the actual lookups.. */
771 err = do_lookup(nd, &this, &next);
772 if (err)
773 break;
774 /* Check mountpoints.. */
775 follow_mount(&next.mnt, &next.dentry);
776
777 err = -ENOENT;
778 inode = next.dentry->d_inode;
779 if (!inode)
780 goto out_dput;
781 err = -ENOTDIR;
782 if (!inode->i_op)
783 goto out_dput;
784
785 if (inode->i_op->follow_link) {
786 mntget(next.mnt);
787 err = do_follow_link(next.dentry, nd);
788 dput(next.dentry);
789 mntput(next.mnt);
790 if (err)
791 goto return_err;
792 err = -ENOENT;
793 inode = nd->dentry->d_inode;
794 if (!inode)
795 break;
796 err = -ENOTDIR;
797 if (!inode->i_op)
798 break;
799 } else {
800 dput(nd->dentry);
801 nd->mnt = next.mnt;
802 nd->dentry = next.dentry;
803 }
804 err = -ENOTDIR;
805 if (!inode->i_op->lookup)
806 break;
807 continue;
808 /* here ends the main loop */
809
810last_with_slashes:
811 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
812last_component:
813 nd->flags &= ~LOOKUP_CONTINUE;
814 if (lookup_flags & LOOKUP_PARENT)
815 goto lookup_parent;
816 if (this.name[0] == '.') switch (this.len) {
817 default:
818 break;
819 case 2:
820 if (this.name[1] != '.')
821 break;
822 follow_dotdot(&nd->mnt, &nd->dentry);
823 inode = nd->dentry->d_inode;
824 /* fallthrough */
825 case 1:
826 goto return_reval;
827 }
828 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
829 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
830 if (err < 0)
831 break;
832 }
833 err = do_lookup(nd, &this, &next);
834 if (err)
835 break;
836 follow_mount(&next.mnt, &next.dentry);
837 inode = next.dentry->d_inode;
838 if ((lookup_flags & LOOKUP_FOLLOW)
839 && inode && inode->i_op && inode->i_op->follow_link) {
840 mntget(next.mnt);
841 err = do_follow_link(next.dentry, nd);
842 dput(next.dentry);
843 mntput(next.mnt);
844 if (err)
845 goto return_err;
846 inode = nd->dentry->d_inode;
847 } else {
848 dput(nd->dentry);
849 nd->mnt = next.mnt;
850 nd->dentry = next.dentry;
851 }
852 err = -ENOENT;
853 if (!inode)
854 break;
855 if (lookup_flags & LOOKUP_DIRECTORY) {
856 err = -ENOTDIR;
857 if (!inode->i_op || !inode->i_op->lookup)
858 break;
859 }
860 goto return_base;
861lookup_parent:
862 nd->last = this;
863 nd->last_type = LAST_NORM;
864 if (this.name[0] != '.')
865 goto return_base;
866 if (this.len == 1)
867 nd->last_type = LAST_DOT;
868 else if (this.len == 2 && this.name[1] == '.')
869 nd->last_type = LAST_DOTDOT;
870 else
871 goto return_base;
872return_reval:
873 /*
874 * We bypassed the ordinary revalidation routines.
875 * We may need to check the cached dentry for staleness.
876 */
877 if (nd->dentry && nd->dentry->d_sb &&
878 (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
879 err = -ESTALE;
880 /* Note: we do not d_invalidate() */
881 if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
882 break;
883 }
884return_base:
885 return 0;
886out_dput:
887 dput(next.dentry);
888 break;
889 }
890 path_release(nd);
891return_err:
892 return err;
893}
894
895/*
896 * Wrapper to retry pathname resolution whenever the underlying
897 * file system returns an ESTALE.
898 *
899 * Retry the whole path once, forcing real lookup requests
900 * instead of relying on the dcache.
901 */
902int fastcall link_path_walk(const char *name, struct nameidata *nd)
903{
904 struct nameidata save = *nd;
905 int result;
906
907 /* make sure the stuff we saved doesn't go away */
908 dget(save.dentry);
909 mntget(save.mnt);
910
911 result = __link_path_walk(name, nd);
912 if (result == -ESTALE) {
913 *nd = save;
914 dget(nd->dentry);
915 mntget(nd->mnt);
916 nd->flags |= LOOKUP_REVAL;
917 result = __link_path_walk(name, nd);
918 }
919
920 dput(save.dentry);
921 mntput(save.mnt);
922
923 return result;
924}
925
926int fastcall path_walk(const char * name, struct nameidata *nd)
927{
928 current->total_link_count = 0;
929 return link_path_walk(name, nd);
930}
931
932/* SMP-safe */
933/* returns 1 if everything is done */
934static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
935{
936 if (path_walk(name, nd))
937 return 0; /* something went wrong... */
938
939 if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
940 struct dentry *old_dentry = nd->dentry;
941 struct vfsmount *old_mnt = nd->mnt;
942 struct qstr last = nd->last;
943 int last_type = nd->last_type;
944 /*
945 * NAME was not found in alternate root or it's a directory. Try to find
946 * it in the normal root:
947 */
948 nd->last_type = LAST_ROOT;
949 read_lock(&current->fs->lock);
950 nd->mnt = mntget(current->fs->rootmnt);
951 nd->dentry = dget(current->fs->root);
952 read_unlock(&current->fs->lock);
953 if (path_walk(name, nd) == 0) {
954 if (nd->dentry->d_inode) {
955 dput(old_dentry);
956 mntput(old_mnt);
957 return 1;
958 }
959 path_release(nd);
960 }
961 nd->dentry = old_dentry;
962 nd->mnt = old_mnt;
963 nd->last = last;
964 nd->last_type = last_type;
965 }
966 return 1;
967}
968
969void set_fs_altroot(void)
970{
971 char *emul = __emul_prefix();
972 struct nameidata nd;
973 struct vfsmount *mnt = NULL, *oldmnt;
974 struct dentry *dentry = NULL, *olddentry;
975 int err;
976
977 if (!emul)
978 goto set_it;
979 err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
980 if (!err) {
981 mnt = nd.mnt;
982 dentry = nd.dentry;
983 }
984set_it:
985 write_lock(&current->fs->lock);
986 oldmnt = current->fs->altrootmnt;
987 olddentry = current->fs->altroot;
988 current->fs->altrootmnt = mnt;
989 current->fs->altroot = dentry;
990 write_unlock(&current->fs->lock);
991 if (olddentry) {
992 dput(olddentry);
993 mntput(oldmnt);
994 }
995}
996
997int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd)
998{
999 int retval;
1000
1001 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1002 nd->flags = flags;
1003 nd->depth = 0;
1004
1005 read_lock(&current->fs->lock);
1006 if (*name=='/') {
1007 if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
1008 nd->mnt = mntget(current->fs->altrootmnt);
1009 nd->dentry = dget(current->fs->altroot);
1010 read_unlock(&current->fs->lock);
1011 if (__emul_lookup_dentry(name,nd))
1012 return 0;
1013 read_lock(&current->fs->lock);
1014 }
1015 nd->mnt = mntget(current->fs->rootmnt);
1016 nd->dentry = dget(current->fs->root);
1017 } else {
1018 nd->mnt = mntget(current->fs->pwdmnt);
1019 nd->dentry = dget(current->fs->pwd);
1020 }
1021 read_unlock(&current->fs->lock);
1022 current->total_link_count = 0;
1023 retval = link_path_walk(name, nd);
1024 if (unlikely(current->audit_context
1025 && nd && nd->dentry && nd->dentry->d_inode))
1026 audit_inode(name, nd->dentry->d_inode);
1027 return retval;
1028}
1029
1030/*
1031 * Restricted form of lookup. Doesn't follow links, single-component only,
1032 * needs parent already locked. Doesn't follow mounts.
1033 * SMP-safe.
1034 */
1035static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
1036{
1037 struct dentry * dentry;
1038 struct inode *inode;
1039 int err;
1040
1041 inode = base->d_inode;
1042 err = permission(inode, MAY_EXEC, nd);
1043 dentry = ERR_PTR(err);
1044 if (err)
1045 goto out;
1046
1047 /*
1048 * See if the low-level filesystem might want
1049 * to use its own hash..
1050 */
1051 if (base->d_op && base->d_op->d_hash) {
1052 err = base->d_op->d_hash(base, name);
1053 dentry = ERR_PTR(err);
1054 if (err < 0)
1055 goto out;
1056 }
1057
1058 dentry = cached_lookup(base, name, nd);
1059 if (!dentry) {
1060 struct dentry *new = d_alloc(base, name);
1061 dentry = ERR_PTR(-ENOMEM);
1062 if (!new)
1063 goto out;
1064 dentry = inode->i_op->lookup(inode, new, nd);
1065 if (!dentry)
1066 dentry = new;
1067 else
1068 dput(new);
1069 }
1070out:
1071 return dentry;
1072}
1073
1074struct dentry * lookup_hash(struct qstr *name, struct dentry * base)
1075{
1076 return __lookup_hash(name, base, NULL);
1077}
1078
1079/* SMP-safe */
1080struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
1081{
1082 unsigned long hash;
1083 struct qstr this;
1084 unsigned int c;
1085
1086 this.name = name;
1087 this.len = len;
1088 if (!len)
1089 goto access;
1090
1091 hash = init_name_hash();
1092 while (len--) {
1093 c = *(const unsigned char *)name++;
1094 if (c == '/' || c == '\0')
1095 goto access;
1096 hash = partial_name_hash(c, hash);
1097 }
1098 this.hash = end_name_hash(hash);
1099
1100 return lookup_hash(&this, base);
1101access:
1102 return ERR_PTR(-EACCES);
1103}
1104
1105/*
1106 * namei()
1107 *
1108 * is used by most simple commands to get the inode of a specified name.
1109 * Open, link etc use their own routines, but this is enough for things
1110 * like 'chmod' etc.
1111 *
1112 * namei exists in two versions: namei/lnamei. The only difference is
1113 * that namei follows links, while lnamei does not.
1114 * SMP-safe
1115 */
1116int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
1117{
1118 char *tmp = getname(name);
1119 int err = PTR_ERR(tmp);
1120
1121 if (!IS_ERR(tmp)) {
1122 err = path_lookup(tmp, flags, nd);
1123 putname(tmp);
1124 }
1125 return err;
1126}
1127
1128/*
1129 * It's inline, so penalty for filesystems that don't use sticky bit is
1130 * minimal.
1131 */
1132static inline int check_sticky(struct inode *dir, struct inode *inode)
1133{
1134 if (!(dir->i_mode & S_ISVTX))
1135 return 0;
1136 if (inode->i_uid == current->fsuid)
1137 return 0;
1138 if (dir->i_uid == current->fsuid)
1139 return 0;
1140 return !capable(CAP_FOWNER);
1141}
1142
1143/*
1144 * Check whether we can remove a link victim from directory dir, check
1145 * whether the type of victim is right.
1146 * 1. We can't do it if dir is read-only (done in permission())
1147 * 2. We should have write and exec permissions on dir
1148 * 3. We can't remove anything from append-only dir
1149 * 4. We can't do anything with immutable dir (done in permission())
1150 * 5. If the sticky bit on dir is set we should either
1151 * a. be owner of dir, or
1152 * b. be owner of victim, or
1153 * c. have CAP_FOWNER capability
1154 * 6. If the victim is append-only or immutable we can't do antyhing with
1155 * links pointing to it.
1156 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1157 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1158 * 9. We can't remove a root or mountpoint.
1159 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1160 * nfs_async_unlink().
1161 */
1162static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1163{
1164 int error;
1165
1166 if (!victim->d_inode)
1167 return -ENOENT;
1168
1169 BUG_ON(victim->d_parent->d_inode != dir);
1170
1171 error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
1172 if (error)
1173 return error;
1174 if (IS_APPEND(dir))
1175 return -EPERM;
1176 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1177 IS_IMMUTABLE(victim->d_inode))
1178 return -EPERM;
1179 if (isdir) {
1180 if (!S_ISDIR(victim->d_inode->i_mode))
1181 return -ENOTDIR;
1182 if (IS_ROOT(victim))
1183 return -EBUSY;
1184 } else if (S_ISDIR(victim->d_inode->i_mode))
1185 return -EISDIR;
1186 if (IS_DEADDIR(dir))
1187 return -ENOENT;
1188 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1189 return -EBUSY;
1190 return 0;
1191}
1192
1193/* Check whether we can create an object with dentry child in directory
1194 * dir.
1195 * 1. We can't do it if child already exists (open has special treatment for
1196 * this case, but since we are inlined it's OK)
1197 * 2. We can't do it if dir is read-only (done in permission())
1198 * 3. We should have write and exec permissions on dir
1199 * 4. We can't do it if dir is immutable (done in permission())
1200 */
1201static inline int may_create(struct inode *dir, struct dentry *child,
1202 struct nameidata *nd)
1203{
1204 if (child->d_inode)
1205 return -EEXIST;
1206 if (IS_DEADDIR(dir))
1207 return -ENOENT;
1208 return permission(dir,MAY_WRITE | MAY_EXEC, nd);
1209}
1210
1211/*
1212 * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
1213 * reasons.
1214 *
1215 * O_DIRECTORY translates into forcing a directory lookup.
1216 */
1217static inline int lookup_flags(unsigned int f)
1218{
1219 unsigned long retval = LOOKUP_FOLLOW;
1220
1221 if (f & O_NOFOLLOW)
1222 retval &= ~LOOKUP_FOLLOW;
1223
1224 if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
1225 retval &= ~LOOKUP_FOLLOW;
1226
1227 if (f & O_DIRECTORY)
1228 retval |= LOOKUP_DIRECTORY;
1229
1230 return retval;
1231}
1232
1233/*
1234 * p1 and p2 should be directories on the same fs.
1235 */
1236struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1237{
1238 struct dentry *p;
1239
1240 if (p1 == p2) {
1241 down(&p1->d_inode->i_sem);
1242 return NULL;
1243 }
1244
1245 down(&p1->d_inode->i_sb->s_vfs_rename_sem);
1246
1247 for (p = p1; p->d_parent != p; p = p->d_parent) {
1248 if (p->d_parent == p2) {
1249 down(&p2->d_inode->i_sem);
1250 down(&p1->d_inode->i_sem);
1251 return p;
1252 }
1253 }
1254
1255 for (p = p2; p->d_parent != p; p = p->d_parent) {
1256 if (p->d_parent == p1) {
1257 down(&p1->d_inode->i_sem);
1258 down(&p2->d_inode->i_sem);
1259 return p;
1260 }
1261 }
1262
1263 down(&p1->d_inode->i_sem);
1264 down(&p2->d_inode->i_sem);
1265 return NULL;
1266}
1267
1268void unlock_rename(struct dentry *p1, struct dentry *p2)
1269{
1270 up(&p1->d_inode->i_sem);
1271 if (p1 != p2) {
1272 up(&p2->d_inode->i_sem);
1273 up(&p1->d_inode->i_sb->s_vfs_rename_sem);
1274 }
1275}
1276
1277int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1278 struct nameidata *nd)
1279{
1280 int error = may_create(dir, dentry, nd);
1281
1282 if (error)
1283 return error;
1284
1285 if (!dir->i_op || !dir->i_op->create)
1286 return -EACCES; /* shouldn't it be ENOSYS? */
1287 mode &= S_IALLUGO;
1288 mode |= S_IFREG;
1289 error = security_inode_create(dir, dentry, mode);
1290 if (error)
1291 return error;
1292 DQUOT_INIT(dir);
1293 error = dir->i_op->create(dir, dentry, mode, nd);
1294 if (!error) {
1295 inode_dir_notify(dir, DN_CREATE);
1296 security_inode_post_create(dir, dentry, mode);
1297 }
1298 return error;
1299}
1300
1301int may_open(struct nameidata *nd, int acc_mode, int flag)
1302{
1303 struct dentry *dentry = nd->dentry;
1304 struct inode *inode = dentry->d_inode;
1305 int error;
1306
1307 if (!inode)
1308 return -ENOENT;
1309
1310 if (S_ISLNK(inode->i_mode))
1311 return -ELOOP;
1312
1313 if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
1314 return -EISDIR;
1315
1316 error = permission(inode, acc_mode, nd);
1317 if (error)
1318 return error;
1319
1320 /*
1321 * FIFO's, sockets and device files are special: they don't
1322 * actually live on the filesystem itself, and as such you
1323 * can write to them even if the filesystem is read-only.
1324 */
1325 if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
1326 flag &= ~O_TRUNC;
1327 } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
1328 if (nd->mnt->mnt_flags & MNT_NODEV)
1329 return -EACCES;
1330
1331 flag &= ~O_TRUNC;
1332 } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
1333 return -EROFS;
1334 /*
1335 * An append-only file must be opened in append mode for writing.
1336 */
1337 if (IS_APPEND(inode)) {
1338 if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1339 return -EPERM;
1340 if (flag & O_TRUNC)
1341 return -EPERM;
1342 }
1343
1344 /* O_NOATIME can only be set by the owner or superuser */
1345 if (flag & O_NOATIME)
1346 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
1347 return -EPERM;
1348
1349 /*
1350 * Ensure there are no outstanding leases on the file.
1351 */
1352 error = break_lease(inode, flag);
1353 if (error)
1354 return error;
1355
1356 if (flag & O_TRUNC) {
1357 error = get_write_access(inode);
1358 if (error)
1359 return error;
1360
1361 /*
1362 * Refuse to truncate files with mandatory locks held on them.
1363 */
1364 error = locks_verify_locked(inode);
1365 if (!error) {
1366 DQUOT_INIT(inode);
1367
1368 error = do_truncate(dentry, 0);
1369 }
1370 put_write_access(inode);
1371 if (error)
1372 return error;
1373 } else
1374 if (flag & FMODE_WRITE)
1375 DQUOT_INIT(inode);
1376
1377 return 0;
1378}
1379
1380/*
1381 * open_namei()
1382 *
1383 * namei for open - this is in fact almost the whole open-routine.
1384 *
1385 * Note that the low bits of "flag" aren't the same as in the open
1386 * system call - they are 00 - no permissions needed
1387 * 01 - read permission needed
1388 * 10 - write permission needed
1389 * 11 - read/write permissions needed
1390 * which is a lot more logical, and also allows the "no perm" needed
1391 * for symlinks (where the permissions are checked later).
1392 * SMP-safe
1393 */
1394int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
1395{
1396 int acc_mode, error = 0;
1397 struct dentry *dentry;
1398 struct dentry *dir;
1399 int count = 0;
1400
1401 acc_mode = ACC_MODE(flag);
1402
1403 /* Allow the LSM permission hook to distinguish append
1404 access from general write access. */
1405 if (flag & O_APPEND)
1406 acc_mode |= MAY_APPEND;
1407
1408 /* Fill in the open() intent data */
1409 nd->intent.open.flags = flag;
1410 nd->intent.open.create_mode = mode;
1411
1412 /*
1413 * The simplest case - just a plain lookup.
1414 */
1415 if (!(flag & O_CREAT)) {
1416 error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd);
1417 if (error)
1418 return error;
1419 goto ok;
1420 }
1421
1422 /*
1423 * Create - we need to know the parent.
1424 */
1425 error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd);
1426 if (error)
1427 return error;
1428
1429 /*
1430 * We have the parent and last component. First of all, check
1431 * that we are not asked to creat(2) an obvious directory - that
1432 * will not do.
1433 */
1434 error = -EISDIR;
1435 if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
1436 goto exit;
1437
1438 dir = nd->dentry;
1439 nd->flags &= ~LOOKUP_PARENT;
1440 down(&dir->d_inode->i_sem);
1441 dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1442
1443do_last:
1444 error = PTR_ERR(dentry);
1445 if (IS_ERR(dentry)) {
1446 up(&dir->d_inode->i_sem);
1447 goto exit;
1448 }
1449
1450 /* Negative dentry, just create the file */
1451 if (!dentry->d_inode) {
1452 if (!IS_POSIXACL(dir->d_inode))
1453 mode &= ~current->fs->umask;
1454 error = vfs_create(dir->d_inode, dentry, mode, nd);
1455 up(&dir->d_inode->i_sem);
1456 dput(nd->dentry);
1457 nd->dentry = dentry;
1458 if (error)
1459 goto exit;
1460 /* Don't check for write permission, don't truncate */
1461 acc_mode = 0;
1462 flag &= ~O_TRUNC;
1463 goto ok;
1464 }
1465
1466 /*
1467 * It already exists.
1468 */
1469 up(&dir->d_inode->i_sem);
1470
1471 error = -EEXIST;
1472 if (flag & O_EXCL)
1473 goto exit_dput;
1474
1475 if (d_mountpoint(dentry)) {
1476 error = -ELOOP;
1477 if (flag & O_NOFOLLOW)
1478 goto exit_dput;
1479 while (__follow_down(&nd->mnt,&dentry) && d_mountpoint(dentry));
1480 }
1481 error = -ENOENT;
1482 if (!dentry->d_inode)
1483 goto exit_dput;
1484 if (dentry->d_inode->i_op && dentry->d_inode->i_op->follow_link)
1485 goto do_link;
1486
1487 dput(nd->dentry);
1488 nd->dentry = dentry;
1489 error = -EISDIR;
1490 if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode))
1491 goto exit;
1492ok:
1493 error = may_open(nd, acc_mode, flag);
1494 if (error)
1495 goto exit;
1496 return 0;
1497
1498exit_dput:
1499 dput(dentry);
1500exit:
1501 path_release(nd);
1502 return error;
1503
1504do_link:
1505 error = -ELOOP;
1506 if (flag & O_NOFOLLOW)
1507 goto exit_dput;
1508 /*
1509 * This is subtle. Instead of calling do_follow_link() we do the
1510 * thing by hands. The reason is that this way we have zero link_count
1511 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1512 * After that we have the parent and last component, i.e.
1513 * we are in the same situation as after the first path_walk().
1514 * Well, almost - if the last component is normal we get its copy
1515 * stored in nd->last.name and we will have to putname() it when we
1516 * are done. Procfs-like symlinks just set LAST_BIND.
1517 */
1518 nd->flags |= LOOKUP_PARENT;
1519 error = security_inode_follow_link(dentry, nd);
1520 if (error)
1521 goto exit_dput;
1522 error = __do_follow_link(dentry, nd);
1523 dput(dentry);
1524 if (error)
1525 return error;
1526 nd->flags &= ~LOOKUP_PARENT;
1527 if (nd->last_type == LAST_BIND) {
1528 dentry = nd->dentry;
1529 goto ok;
1530 }
1531 error = -EISDIR;
1532 if (nd->last_type != LAST_NORM)
1533 goto exit;
1534 if (nd->last.name[nd->last.len]) {
1535 putname(nd->last.name);
1536 goto exit;
1537 }
1538 error = -ELOOP;
1539 if (count++==32) {
1540 putname(nd->last.name);
1541 goto exit;
1542 }
1543 dir = nd->dentry;
1544 down(&dir->d_inode->i_sem);
1545 dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1546 putname(nd->last.name);
1547 goto do_last;
1548}
1549
1550/**
1551 * lookup_create - lookup a dentry, creating it if it doesn't exist
1552 * @nd: nameidata info
1553 * @is_dir: directory flag
1554 *
1555 * Simple function to lookup and return a dentry and create it
1556 * if it doesn't exist. Is SMP-safe.
1557 */
1558struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1559{
1560 struct dentry *dentry;
1561
1562 down(&nd->dentry->d_inode->i_sem);
1563 dentry = ERR_PTR(-EEXIST);
1564 if (nd->last_type != LAST_NORM)
1565 goto fail;
1566 nd->flags &= ~LOOKUP_PARENT;
1567 dentry = lookup_hash(&nd->last, nd->dentry);
1568 if (IS_ERR(dentry))
1569 goto fail;
1570 if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
1571 goto enoent;
1572 return dentry;
1573enoent:
1574 dput(dentry);
1575 dentry = ERR_PTR(-ENOENT);
1576fail:
1577 return dentry;
1578}
1579
1580int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1581{
1582 int error = may_create(dir, dentry, NULL);
1583
1584 if (error)
1585 return error;
1586
1587 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1588 return -EPERM;
1589
1590 if (!dir->i_op || !dir->i_op->mknod)
1591 return -EPERM;
1592
1593 error = security_inode_mknod(dir, dentry, mode, dev);
1594 if (error)
1595 return error;
1596
1597 DQUOT_INIT(dir);
1598 error = dir->i_op->mknod(dir, dentry, mode, dev);
1599 if (!error) {
1600 inode_dir_notify(dir, DN_CREATE);
1601 security_inode_post_mknod(dir, dentry, mode, dev);
1602 }
1603 return error;
1604}
1605
1606asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev)
1607{
1608 int error = 0;
1609 char * tmp;
1610 struct dentry * dentry;
1611 struct nameidata nd;
1612
1613 if (S_ISDIR(mode))
1614 return -EPERM;
1615 tmp = getname(filename);
1616 if (IS_ERR(tmp))
1617 return PTR_ERR(tmp);
1618
1619 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1620 if (error)
1621 goto out;
1622 dentry = lookup_create(&nd, 0);
1623 error = PTR_ERR(dentry);
1624
1625 if (!IS_POSIXACL(nd.dentry->d_inode))
1626 mode &= ~current->fs->umask;
1627 if (!IS_ERR(dentry)) {
1628 switch (mode & S_IFMT) {
1629 case 0: case S_IFREG:
1630 error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
1631 break;
1632 case S_IFCHR: case S_IFBLK:
1633 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
1634 new_decode_dev(dev));
1635 break;
1636 case S_IFIFO: case S_IFSOCK:
1637 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
1638 break;
1639 case S_IFDIR:
1640 error = -EPERM;
1641 break;
1642 default:
1643 error = -EINVAL;
1644 }
1645 dput(dentry);
1646 }
1647 up(&nd.dentry->d_inode->i_sem);
1648 path_release(&nd);
1649out:
1650 putname(tmp);
1651
1652 return error;
1653}
1654
1655int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1656{
1657 int error = may_create(dir, dentry, NULL);
1658
1659 if (error)
1660 return error;
1661
1662 if (!dir->i_op || !dir->i_op->mkdir)
1663 return -EPERM;
1664
1665 mode &= (S_IRWXUGO|S_ISVTX);
1666 error = security_inode_mkdir(dir, dentry, mode);
1667 if (error)
1668 return error;
1669
1670 DQUOT_INIT(dir);
1671 error = dir->i_op->mkdir(dir, dentry, mode);
1672 if (!error) {
1673 inode_dir_notify(dir, DN_CREATE);
1674 security_inode_post_mkdir(dir,dentry, mode);
1675 }
1676 return error;
1677}
1678
1679asmlinkage long sys_mkdir(const char __user * pathname, int mode)
1680{
1681 int error = 0;
1682 char * tmp;
1683
1684 tmp = getname(pathname);
1685 error = PTR_ERR(tmp);
1686 if (!IS_ERR(tmp)) {
1687 struct dentry *dentry;
1688 struct nameidata nd;
1689
1690 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1691 if (error)
1692 goto out;
1693 dentry = lookup_create(&nd, 1);
1694 error = PTR_ERR(dentry);
1695 if (!IS_ERR(dentry)) {
1696 if (!IS_POSIXACL(nd.dentry->d_inode))
1697 mode &= ~current->fs->umask;
1698 error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
1699 dput(dentry);
1700 }
1701 up(&nd.dentry->d_inode->i_sem);
1702 path_release(&nd);
1703out:
1704 putname(tmp);
1705 }
1706
1707 return error;
1708}
1709
1710/*
1711 * We try to drop the dentry early: we should have
1712 * a usage count of 2 if we're the only user of this
1713 * dentry, and if that is true (possibly after pruning
1714 * the dcache), then we drop the dentry now.
1715 *
1716 * A low-level filesystem can, if it choses, legally
1717 * do a
1718 *
1719 * if (!d_unhashed(dentry))
1720 * return -EBUSY;
1721 *
1722 * if it cannot handle the case of removing a directory
1723 * that is still in use by something else..
1724 */
1725void dentry_unhash(struct dentry *dentry)
1726{
1727 dget(dentry);
1728 if (atomic_read(&dentry->d_count))
1729 shrink_dcache_parent(dentry);
1730 spin_lock(&dcache_lock);
1731 spin_lock(&dentry->d_lock);
1732 if (atomic_read(&dentry->d_count) == 2)
1733 __d_drop(dentry);
1734 spin_unlock(&dentry->d_lock);
1735 spin_unlock(&dcache_lock);
1736}
1737
1738int vfs_rmdir(struct inode *dir, struct dentry *dentry)
1739{
1740 int error = may_delete(dir, dentry, 1);
1741
1742 if (error)
1743 return error;
1744
1745 if (!dir->i_op || !dir->i_op->rmdir)
1746 return -EPERM;
1747
1748 DQUOT_INIT(dir);
1749
1750 down(&dentry->d_inode->i_sem);
1751 dentry_unhash(dentry);
1752 if (d_mountpoint(dentry))
1753 error = -EBUSY;
1754 else {
1755 error = security_inode_rmdir(dir, dentry);
1756 if (!error) {
1757 error = dir->i_op->rmdir(dir, dentry);
1758 if (!error)
1759 dentry->d_inode->i_flags |= S_DEAD;
1760 }
1761 }
1762 up(&dentry->d_inode->i_sem);
1763 if (!error) {
1764 inode_dir_notify(dir, DN_DELETE);
1765 d_delete(dentry);
1766 }
1767 dput(dentry);
1768
1769 return error;
1770}
1771
1772asmlinkage long sys_rmdir(const char __user * pathname)
1773{
1774 int error = 0;
1775 char * name;
1776 struct dentry *dentry;
1777 struct nameidata nd;
1778
1779 name = getname(pathname);
1780 if(IS_ERR(name))
1781 return PTR_ERR(name);
1782
1783 error = path_lookup(name, LOOKUP_PARENT, &nd);
1784 if (error)
1785 goto exit;
1786
1787 switch(nd.last_type) {
1788 case LAST_DOTDOT:
1789 error = -ENOTEMPTY;
1790 goto exit1;
1791 case LAST_DOT:
1792 error = -EINVAL;
1793 goto exit1;
1794 case LAST_ROOT:
1795 error = -EBUSY;
1796 goto exit1;
1797 }
1798 down(&nd.dentry->d_inode->i_sem);
1799 dentry = lookup_hash(&nd.last, nd.dentry);
1800 error = PTR_ERR(dentry);
1801 if (!IS_ERR(dentry)) {
1802 error = vfs_rmdir(nd.dentry->d_inode, dentry);
1803 dput(dentry);
1804 }
1805 up(&nd.dentry->d_inode->i_sem);
1806exit1:
1807 path_release(&nd);
1808exit:
1809 putname(name);
1810 return error;
1811}
1812
1813int vfs_unlink(struct inode *dir, struct dentry *dentry)
1814{
1815 int error = may_delete(dir, dentry, 0);
1816
1817 if (error)
1818 return error;
1819
1820 if (!dir->i_op || !dir->i_op->unlink)
1821 return -EPERM;
1822
1823 DQUOT_INIT(dir);
1824
1825 down(&dentry->d_inode->i_sem);
1826 if (d_mountpoint(dentry))
1827 error = -EBUSY;
1828 else {
1829 error = security_inode_unlink(dir, dentry);
1830 if (!error)
1831 error = dir->i_op->unlink(dir, dentry);
1832 }
1833 up(&dentry->d_inode->i_sem);
1834
1835 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
1836 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
1837 d_delete(dentry);
1838 inode_dir_notify(dir, DN_DELETE);
1839 }
1840 return error;
1841}
1842
1843/*
1844 * Make sure that the actual truncation of the file will occur outside its
1845 * directory's i_sem. Truncate can take a long time if there is a lot of
1846 * writeout happening, and we don't want to prevent access to the directory
1847 * while waiting on the I/O.
1848 */
1849asmlinkage long sys_unlink(const char __user * pathname)
1850{
1851 int error = 0;
1852 char * name;
1853 struct dentry *dentry;
1854 struct nameidata nd;
1855 struct inode *inode = NULL;
1856
1857 name = getname(pathname);
1858 if(IS_ERR(name))
1859 return PTR_ERR(name);
1860
1861 error = path_lookup(name, LOOKUP_PARENT, &nd);
1862 if (error)
1863 goto exit;
1864 error = -EISDIR;
1865 if (nd.last_type != LAST_NORM)
1866 goto exit1;
1867 down(&nd.dentry->d_inode->i_sem);
1868 dentry = lookup_hash(&nd.last, nd.dentry);
1869 error = PTR_ERR(dentry);
1870 if (!IS_ERR(dentry)) {
1871 /* Why not before? Because we want correct error value */
1872 if (nd.last.name[nd.last.len])
1873 goto slashes;
1874 inode = dentry->d_inode;
1875 if (inode)
1876 atomic_inc(&inode->i_count);
1877 error = vfs_unlink(nd.dentry->d_inode, dentry);
1878 exit2:
1879 dput(dentry);
1880 }
1881 up(&nd.dentry->d_inode->i_sem);
1882 if (inode)
1883 iput(inode); /* truncate the inode here */
1884exit1:
1885 path_release(&nd);
1886exit:
1887 putname(name);
1888 return error;
1889
1890slashes:
1891 error = !dentry->d_inode ? -ENOENT :
1892 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
1893 goto exit2;
1894}
1895
1896int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
1897{
1898 int error = may_create(dir, dentry, NULL);
1899
1900 if (error)
1901 return error;
1902
1903 if (!dir->i_op || !dir->i_op->symlink)
1904 return -EPERM;
1905
1906 error = security_inode_symlink(dir, dentry, oldname);
1907 if (error)
1908 return error;
1909
1910 DQUOT_INIT(dir);
1911 error = dir->i_op->symlink(dir, dentry, oldname);
1912 if (!error) {
1913 inode_dir_notify(dir, DN_CREATE);
1914 security_inode_post_symlink(dir, dentry, oldname);
1915 }
1916 return error;
1917}
1918
1919asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname)
1920{
1921 int error = 0;
1922 char * from;
1923 char * to;
1924
1925 from = getname(oldname);
1926 if(IS_ERR(from))
1927 return PTR_ERR(from);
1928 to = getname(newname);
1929 error = PTR_ERR(to);
1930 if (!IS_ERR(to)) {
1931 struct dentry *dentry;
1932 struct nameidata nd;
1933
1934 error = path_lookup(to, LOOKUP_PARENT, &nd);
1935 if (error)
1936 goto out;
1937 dentry = lookup_create(&nd, 0);
1938 error = PTR_ERR(dentry);
1939 if (!IS_ERR(dentry)) {
1940 error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
1941 dput(dentry);
1942 }
1943 up(&nd.dentry->d_inode->i_sem);
1944 path_release(&nd);
1945out:
1946 putname(to);
1947 }
1948 putname(from);
1949 return error;
1950}
1951
1952int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
1953{
1954 struct inode *inode = old_dentry->d_inode;
1955 int error;
1956
1957 if (!inode)
1958 return -ENOENT;
1959
1960 error = may_create(dir, new_dentry, NULL);
1961 if (error)
1962 return error;
1963
1964 if (dir->i_sb != inode->i_sb)
1965 return -EXDEV;
1966
1967 /*
1968 * A link to an append-only or immutable file cannot be created.
1969 */
1970 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1971 return -EPERM;
1972 if (!dir->i_op || !dir->i_op->link)
1973 return -EPERM;
1974 if (S_ISDIR(old_dentry->d_inode->i_mode))
1975 return -EPERM;
1976
1977 error = security_inode_link(old_dentry, dir, new_dentry);
1978 if (error)
1979 return error;
1980
1981 down(&old_dentry->d_inode->i_sem);
1982 DQUOT_INIT(dir);
1983 error = dir->i_op->link(old_dentry, dir, new_dentry);
1984 up(&old_dentry->d_inode->i_sem);
1985 if (!error) {
1986 inode_dir_notify(dir, DN_CREATE);
1987 security_inode_post_link(old_dentry, dir, new_dentry);
1988 }
1989 return error;
1990}
1991
1992/*
1993 * Hardlinks are often used in delicate situations. We avoid
1994 * security-related surprises by not following symlinks on the
1995 * newname. --KAB
1996 *
1997 * We don't follow them on the oldname either to be compatible
1998 * with linux 2.0, and to avoid hard-linking to directories
1999 * and other special files. --ADM
2000 */
2001asmlinkage long sys_link(const char __user * oldname, const char __user * newname)
2002{
2003 struct dentry *new_dentry;
2004 struct nameidata nd, old_nd;
2005 int error;
2006 char * to;
2007
2008 to = getname(newname);
2009 if (IS_ERR(to))
2010 return PTR_ERR(to);
2011
2012 error = __user_walk(oldname, 0, &old_nd);
2013 if (error)
2014 goto exit;
2015 error = path_lookup(to, LOOKUP_PARENT, &nd);
2016 if (error)
2017 goto out;
2018 error = -EXDEV;
2019 if (old_nd.mnt != nd.mnt)
2020 goto out_release;
2021 new_dentry = lookup_create(&nd, 0);
2022 error = PTR_ERR(new_dentry);
2023 if (!IS_ERR(new_dentry)) {
2024 error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
2025 dput(new_dentry);
2026 }
2027 up(&nd.dentry->d_inode->i_sem);
2028out_release:
2029 path_release(&nd);
2030out:
2031 path_release(&old_nd);
2032exit:
2033 putname(to);
2034
2035 return error;
2036}
2037
2038/*
2039 * The worst of all namespace operations - renaming directory. "Perverted"
2040 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2041 * Problems:
2042 * a) we can get into loop creation. Check is done in is_subdir().
2043 * b) race potential - two innocent renames can create a loop together.
2044 * That's where 4.4 screws up. Current fix: serialization on
2045 * sb->s_vfs_rename_sem. We might be more accurate, but that's another
2046 * story.
2047 * c) we have to lock _three_ objects - parents and victim (if it exists).
2048 * And that - after we got ->i_sem on parents (until then we don't know
2049 * whether the target exists). Solution: try to be smart with locking
2050 * order for inodes. We rely on the fact that tree topology may change
2051 * only under ->s_vfs_rename_sem _and_ that parent of the object we
2052 * move will be locked. Thus we can rank directories by the tree
2053 * (ancestors first) and rank all non-directories after them.
2054 * That works since everybody except rename does "lock parent, lookup,
2055 * lock child" and rename is under ->s_vfs_rename_sem.
2056 * HOWEVER, it relies on the assumption that any object with ->lookup()
2057 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2058 * we'd better make sure that there's no link(2) for them.
2059 * d) some filesystems don't support opened-but-unlinked directories,
2060 * either because of layout or because they are not ready to deal with
2061 * all cases correctly. The latter will be fixed (taking this sort of
2062 * stuff into VFS), but the former is not going away. Solution: the same
2063 * trick as in rmdir().
2064 * e) conversion from fhandle to dentry may come in the wrong moment - when
2065 * we are removing the target. Solution: we will have to grab ->i_sem
2066 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2067 * ->i_sem on parents, which works but leads to some truely excessive
2068 * locking].
2069 */
2070int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2071 struct inode *new_dir, struct dentry *new_dentry)
2072{
2073 int error = 0;
2074 struct inode *target;
2075
2076 /*
2077 * If we are going to change the parent - check write permissions,
2078 * we'll need to flip '..'.
2079 */
2080 if (new_dir != old_dir) {
2081 error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
2082 if (error)
2083 return error;
2084 }
2085
2086 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2087 if (error)
2088 return error;
2089
2090 target = new_dentry->d_inode;
2091 if (target) {
2092 down(&target->i_sem);
2093 dentry_unhash(new_dentry);
2094 }
2095 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2096 error = -EBUSY;
2097 else
2098 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2099 if (target) {
2100 if (!error)
2101 target->i_flags |= S_DEAD;
2102 up(&target->i_sem);
2103 if (d_unhashed(new_dentry))
2104 d_rehash(new_dentry);
2105 dput(new_dentry);
2106 }
2107 if (!error) {
2108 d_move(old_dentry,new_dentry);
2109 security_inode_post_rename(old_dir, old_dentry,
2110 new_dir, new_dentry);
2111 }
2112 return error;
2113}
2114
2115int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2116 struct inode *new_dir, struct dentry *new_dentry)
2117{
2118 struct inode *target;
2119 int error;
2120
2121 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2122 if (error)
2123 return error;
2124
2125 dget(new_dentry);
2126 target = new_dentry->d_inode;
2127 if (target)
2128 down(&target->i_sem);
2129 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2130 error = -EBUSY;
2131 else
2132 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2133 if (!error) {
2134 /* The following d_move() should become unconditional */
2135 if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME))
2136 d_move(old_dentry, new_dentry);
2137 security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry);
2138 }
2139 if (target)
2140 up(&target->i_sem);
2141 dput(new_dentry);
2142 return error;
2143}
2144
2145int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2146 struct inode *new_dir, struct dentry *new_dentry)
2147{
2148 int error;
2149 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2150
2151 if (old_dentry->d_inode == new_dentry->d_inode)
2152 return 0;
2153
2154 error = may_delete(old_dir, old_dentry, is_dir);
2155 if (error)
2156 return error;
2157
2158 if (!new_dentry->d_inode)
2159 error = may_create(new_dir, new_dentry, NULL);
2160 else
2161 error = may_delete(new_dir, new_dentry, is_dir);
2162 if (error)
2163 return error;
2164
2165 if (!old_dir->i_op || !old_dir->i_op->rename)
2166 return -EPERM;
2167
2168 DQUOT_INIT(old_dir);
2169 DQUOT_INIT(new_dir);
2170
2171 if (is_dir)
2172 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2173 else
2174 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2175 if (!error) {
2176 if (old_dir == new_dir)
2177 inode_dir_notify(old_dir, DN_RENAME);
2178 else {
2179 inode_dir_notify(old_dir, DN_DELETE);
2180 inode_dir_notify(new_dir, DN_CREATE);
2181 }
2182 }
2183 return error;
2184}
2185
2186static inline int do_rename(const char * oldname, const char * newname)
2187{
2188 int error = 0;
2189 struct dentry * old_dir, * new_dir;
2190 struct dentry * old_dentry, *new_dentry;
2191 struct dentry * trap;
2192 struct nameidata oldnd, newnd;
2193
2194 error = path_lookup(oldname, LOOKUP_PARENT, &oldnd);
2195 if (error)
2196 goto exit;
2197
2198 error = path_lookup(newname, LOOKUP_PARENT, &newnd);
2199 if (error)
2200 goto exit1;
2201
2202 error = -EXDEV;
2203 if (oldnd.mnt != newnd.mnt)
2204 goto exit2;
2205
2206 old_dir = oldnd.dentry;
2207 error = -EBUSY;
2208 if (oldnd.last_type != LAST_NORM)
2209 goto exit2;
2210
2211 new_dir = newnd.dentry;
2212 if (newnd.last_type != LAST_NORM)
2213 goto exit2;
2214
2215 trap = lock_rename(new_dir, old_dir);
2216
2217 old_dentry = lookup_hash(&oldnd.last, old_dir);
2218 error = PTR_ERR(old_dentry);
2219 if (IS_ERR(old_dentry))
2220 goto exit3;
2221 /* source must exist */
2222 error = -ENOENT;
2223 if (!old_dentry->d_inode)
2224 goto exit4;
2225 /* unless the source is a directory trailing slashes give -ENOTDIR */
2226 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2227 error = -ENOTDIR;
2228 if (oldnd.last.name[oldnd.last.len])
2229 goto exit4;
2230 if (newnd.last.name[newnd.last.len])
2231 goto exit4;
2232 }
2233 /* source should not be ancestor of target */
2234 error = -EINVAL;
2235 if (old_dentry == trap)
2236 goto exit4;
2237 new_dentry = lookup_hash(&newnd.last, new_dir);
2238 error = PTR_ERR(new_dentry);
2239 if (IS_ERR(new_dentry))
2240 goto exit4;
2241 /* target should not be an ancestor of source */
2242 error = -ENOTEMPTY;
2243 if (new_dentry == trap)
2244 goto exit5;
2245
2246 error = vfs_rename(old_dir->d_inode, old_dentry,
2247 new_dir->d_inode, new_dentry);
2248exit5:
2249 dput(new_dentry);
2250exit4:
2251 dput(old_dentry);
2252exit3:
2253 unlock_rename(new_dir, old_dir);
2254exit2:
2255 path_release(&newnd);
2256exit1:
2257 path_release(&oldnd);
2258exit:
2259 return error;
2260}
2261
2262asmlinkage long sys_rename(const char __user * oldname, const char __user * newname)
2263{
2264 int error;
2265 char * from;
2266 char * to;
2267
2268 from = getname(oldname);
2269 if(IS_ERR(from))
2270 return PTR_ERR(from);
2271 to = getname(newname);
2272 error = PTR_ERR(to);
2273 if (!IS_ERR(to)) {
2274 error = do_rename(from,to);
2275 putname(to);
2276 }
2277 putname(from);
2278 return error;
2279}
2280
2281int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2282{
2283 int len;
2284
2285 len = PTR_ERR(link);
2286 if (IS_ERR(link))
2287 goto out;
2288
2289 len = strlen(link);
2290 if (len > (unsigned) buflen)
2291 len = buflen;
2292 if (copy_to_user(buffer, link, len))
2293 len = -EFAULT;
2294out:
2295 return len;
2296}
2297
2298/*
2299 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2300 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2301 * using) it for any given inode is up to filesystem.
2302 */
2303int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2304{
2305 struct nameidata nd;
2306 int res;
2307 nd.depth = 0;
2308 res = dentry->d_inode->i_op->follow_link(dentry, &nd);
2309 if (!res) {
2310 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2311 if (dentry->d_inode->i_op->put_link)
2312 dentry->d_inode->i_op->put_link(dentry, &nd);
2313 }
2314 return res;
2315}
2316
2317int vfs_follow_link(struct nameidata *nd, const char *link)
2318{
2319 return __vfs_follow_link(nd, link);
2320}
2321
2322/* get the link contents into pagecache */
2323static char *page_getlink(struct dentry * dentry, struct page **ppage)
2324{
2325 struct page * page;
2326 struct address_space *mapping = dentry->d_inode->i_mapping;
2327 page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
2328 NULL);
2329 if (IS_ERR(page))
2330 goto sync_fail;
2331 wait_on_page_locked(page);
2332 if (!PageUptodate(page))
2333 goto async_fail;
2334 *ppage = page;
2335 return kmap(page);
2336
2337async_fail:
2338 page_cache_release(page);
2339 return ERR_PTR(-EIO);
2340
2341sync_fail:
2342 return (char*)page;
2343}
2344
2345int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2346{
2347 struct page *page = NULL;
2348 char *s = page_getlink(dentry, &page);
2349 int res = vfs_readlink(dentry,buffer,buflen,s);
2350 if (page) {
2351 kunmap(page);
2352 page_cache_release(page);
2353 }
2354 return res;
2355}
2356
2357int page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
2358{
2359 struct page *page;
2360 nd_set_link(nd, page_getlink(dentry, &page));
2361 return 0;
2362}
2363
2364void page_put_link(struct dentry *dentry, struct nameidata *nd)
2365{
2366 if (!IS_ERR(nd_get_link(nd))) {
2367 struct page *page;
2368 page = find_get_page(dentry->d_inode->i_mapping, 0);
2369 if (!page)
2370 BUG();
2371 kunmap(page);
2372 page_cache_release(page);
2373 page_cache_release(page);
2374 }
2375}
2376
2377int page_symlink(struct inode *inode, const char *symname, int len)
2378{
2379 struct address_space *mapping = inode->i_mapping;
2380 struct page *page = grab_cache_page(mapping, 0);
2381 int err = -ENOMEM;
2382 char *kaddr;
2383
2384 if (!page)
2385 goto fail;
2386 err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
2387 if (err)
2388 goto fail_map;
2389 kaddr = kmap_atomic(page, KM_USER0);
2390 memcpy(kaddr, symname, len-1);
2391 kunmap_atomic(kaddr, KM_USER0);
2392 mapping->a_ops->commit_write(NULL, page, 0, len-1);
2393 /*
2394 * Notice that we are _not_ going to block here - end of page is
2395 * unmapped, so this will only try to map the rest of page, see
2396 * that it is unmapped (typically even will not look into inode -
2397 * ->i_size will be enough for everything) and zero it out.
2398 * OTOH it's obviously correct and should make the page up-to-date.
2399 */
2400 if (!PageUptodate(page)) {
2401 err = mapping->a_ops->readpage(NULL, page);
2402 wait_on_page_locked(page);
2403 } else {
2404 unlock_page(page);
2405 }
2406 page_cache_release(page);
2407 if (err < 0)
2408 goto fail;
2409 mark_inode_dirty(inode);
2410 return 0;
2411fail_map:
2412 unlock_page(page);
2413 page_cache_release(page);
2414fail:
2415 return err;
2416}
2417
2418struct inode_operations page_symlink_inode_operations = {
2419 .readlink = generic_readlink,
2420 .follow_link = page_follow_link_light,
2421 .put_link = page_put_link,
2422};
2423
2424EXPORT_SYMBOL(__user_walk);
2425EXPORT_SYMBOL(follow_down);
2426EXPORT_SYMBOL(follow_up);
2427EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2428EXPORT_SYMBOL(getname);
2429EXPORT_SYMBOL(lock_rename);
2430EXPORT_SYMBOL(lookup_hash);
2431EXPORT_SYMBOL(lookup_one_len);
2432EXPORT_SYMBOL(page_follow_link_light);
2433EXPORT_SYMBOL(page_put_link);
2434EXPORT_SYMBOL(page_readlink);
2435EXPORT_SYMBOL(page_symlink);
2436EXPORT_SYMBOL(page_symlink_inode_operations);
2437EXPORT_SYMBOL(path_lookup);
2438EXPORT_SYMBOL(path_release);
2439EXPORT_SYMBOL(path_walk);
2440EXPORT_SYMBOL(permission);
2441EXPORT_SYMBOL(unlock_rename);
2442EXPORT_SYMBOL(vfs_create);
2443EXPORT_SYMBOL(vfs_follow_link);
2444EXPORT_SYMBOL(vfs_link);
2445EXPORT_SYMBOL(vfs_mkdir);
2446EXPORT_SYMBOL(vfs_mknod);
2447EXPORT_SYMBOL(generic_permission);
2448EXPORT_SYMBOL(vfs_readlink);
2449EXPORT_SYMBOL(vfs_rename);
2450EXPORT_SYMBOL(vfs_rmdir);
2451EXPORT_SYMBOL(vfs_symlink);
2452EXPORT_SYMBOL(vfs_unlink);
2453EXPORT_SYMBOL(dentry_unhash);
2454EXPORT_SYMBOL(generic_readlink);
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-10 02:06:18 -0500