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[mirror_ubuntu-zesty-kernel.git] / fs / reiserfs / xattr.c
1 /*
2 * linux/fs/reiserfs/xattr.c
3 *
4 * Copyright (c) 2002 by Jeff Mahoney, <jeffm@suse.com>
5 *
6 */
7
8 /*
9 * In order to implement EA/ACLs in a clean, backwards compatible manner,
10 * they are implemented as files in a "private" directory.
11 * Each EA is in it's own file, with the directory layout like so (/ is assumed
12 * to be relative to fs root). Inside the /.reiserfs_priv/xattrs directory,
13 * directories named using the capital-hex form of the objectid and
14 * generation number are used. Inside each directory are individual files
15 * named with the name of the extended attribute.
16 *
17 * So, for objectid 12648430, we could have:
18 * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_access
19 * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_default
20 * /.reiserfs_priv/xattrs/C0FFEE.0/user.Content-Type
21 * .. or similar.
22 *
23 * The file contents are the text of the EA. The size is known based on the
24 * stat data describing the file.
25 *
26 * In the case of system.posix_acl_access and system.posix_acl_default, since
27 * these are special cases for filesystem ACLs, they are interpreted by the
28 * kernel, in addition, they are negatively and positively cached and attached
29 * to the inode so that unnecessary lookups are avoided.
30 *
31 * Locking works like so:
32 * Directory components (xattr root, xattr dir) are protectd by their i_mutex.
33 * The xattrs themselves are protected by the xattr_sem.
34 */
35
36 #include "reiserfs.h"
37 #include <linux/capability.h>
38 #include <linux/dcache.h>
39 #include <linux/namei.h>
40 #include <linux/errno.h>
41 #include <linux/gfp.h>
42 #include <linux/fs.h>
43 #include <linux/file.h>
44 #include <linux/pagemap.h>
45 #include <linux/xattr.h>
46 #include "xattr.h"
47 #include "acl.h"
48 #include <linux/uaccess.h>
49 #include <net/checksum.h>
50 #include <linux/stat.h>
51 #include <linux/quotaops.h>
52 #include <linux/security.h>
53 #include <linux/posix_acl_xattr.h>
54
55 #define PRIVROOT_NAME ".reiserfs_priv"
56 #define XAROOT_NAME "xattrs"
57
58
59 /*
60 * Helpers for inode ops. We do this so that we don't have all the VFS
61 * overhead and also for proper i_mutex annotation.
62 * dir->i_mutex must be held for all of them.
63 */
64 #ifdef CONFIG_REISERFS_FS_XATTR
65 static int xattr_create(struct inode *dir, struct dentry *dentry, int mode)
66 {
67 BUG_ON(!mutex_is_locked(&dir->i_mutex));
68 return dir->i_op->create(dir, dentry, mode, true);
69 }
70 #endif
71
72 static int xattr_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
73 {
74 BUG_ON(!mutex_is_locked(&dir->i_mutex));
75 return dir->i_op->mkdir(dir, dentry, mode);
76 }
77
78 /*
79 * We use I_MUTEX_CHILD here to silence lockdep. It's safe because xattr
80 * mutation ops aren't called during rename or splace, which are the
81 * only other users of I_MUTEX_CHILD. It violates the ordering, but that's
82 * better than allocating another subclass just for this code.
83 */
84 static int xattr_unlink(struct inode *dir, struct dentry *dentry)
85 {
86 int error;
87
88 BUG_ON(!mutex_is_locked(&dir->i_mutex));
89
90 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
91 error = dir->i_op->unlink(dir, dentry);
92 mutex_unlock(&dentry->d_inode->i_mutex);
93
94 if (!error)
95 d_delete(dentry);
96 return error;
97 }
98
99 static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
100 {
101 int error;
102
103 BUG_ON(!mutex_is_locked(&dir->i_mutex));
104
105 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
106 error = dir->i_op->rmdir(dir, dentry);
107 if (!error)
108 dentry->d_inode->i_flags |= S_DEAD;
109 mutex_unlock(&dentry->d_inode->i_mutex);
110 if (!error)
111 d_delete(dentry);
112
113 return error;
114 }
115
116 #define xattr_may_create(flags) (!flags || flags & XATTR_CREATE)
117
118 static struct dentry *open_xa_root(struct super_block *sb, int flags)
119 {
120 struct dentry *privroot = REISERFS_SB(sb)->priv_root;
121 struct dentry *xaroot;
122
123 if (!privroot->d_inode)
124 return ERR_PTR(-ENODATA);
125
126 mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
127
128 xaroot = dget(REISERFS_SB(sb)->xattr_root);
129 if (!xaroot)
130 xaroot = ERR_PTR(-ENODATA);
131 else if (!xaroot->d_inode) {
132 int err = -ENODATA;
133
134 if (xattr_may_create(flags))
135 err = xattr_mkdir(privroot->d_inode, xaroot, 0700);
136 if (err) {
137 dput(xaroot);
138 xaroot = ERR_PTR(err);
139 }
140 }
141
142 mutex_unlock(&privroot->d_inode->i_mutex);
143 return xaroot;
144 }
145
146 static struct dentry *open_xa_dir(const struct inode *inode, int flags)
147 {
148 struct dentry *xaroot, *xadir;
149 char namebuf[17];
150
151 xaroot = open_xa_root(inode->i_sb, flags);
152 if (IS_ERR(xaroot))
153 return xaroot;
154
155 snprintf(namebuf, sizeof(namebuf), "%X.%X",
156 le32_to_cpu(INODE_PKEY(inode)->k_objectid),
157 inode->i_generation);
158
159 mutex_lock_nested(&xaroot->d_inode->i_mutex, I_MUTEX_XATTR);
160
161 xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
162 if (!IS_ERR(xadir) && !xadir->d_inode) {
163 int err = -ENODATA;
164
165 if (xattr_may_create(flags))
166 err = xattr_mkdir(xaroot->d_inode, xadir, 0700);
167 if (err) {
168 dput(xadir);
169 xadir = ERR_PTR(err);
170 }
171 }
172
173 mutex_unlock(&xaroot->d_inode->i_mutex);
174 dput(xaroot);
175 return xadir;
176 }
177
178 /*
179 * The following are side effects of other operations that aren't explicitly
180 * modifying extended attributes. This includes operations such as permissions
181 * or ownership changes, object deletions, etc.
182 */
183 struct reiserfs_dentry_buf {
184 struct dir_context ctx;
185 struct dentry *xadir;
186 int count;
187 struct dentry *dentries[8];
188 };
189
190 static int
191 fill_with_dentries(struct dir_context *ctx, const char *name, int namelen,
192 loff_t offset, u64 ino, unsigned int d_type)
193 {
194 struct reiserfs_dentry_buf *dbuf =
195 container_of(ctx, struct reiserfs_dentry_buf, ctx);
196 struct dentry *dentry;
197
198 WARN_ON_ONCE(!mutex_is_locked(&dbuf->xadir->d_inode->i_mutex));
199
200 if (dbuf->count == ARRAY_SIZE(dbuf->dentries))
201 return -ENOSPC;
202
203 if (name[0] == '.' && (namelen < 2 ||
204 (namelen == 2 && name[1] == '.')))
205 return 0;
206
207 dentry = lookup_one_len(name, dbuf->xadir, namelen);
208 if (IS_ERR(dentry)) {
209 return PTR_ERR(dentry);
210 } else if (!dentry->d_inode) {
211 /* A directory entry exists, but no file? */
212 reiserfs_error(dentry->d_sb, "xattr-20003",
213 "Corrupted directory: xattr %pd listed but "
214 "not found for file %pd.\n",
215 dentry, dbuf->xadir);
216 dput(dentry);
217 return -EIO;
218 }
219
220 dbuf->dentries[dbuf->count++] = dentry;
221 return 0;
222 }
223
224 static void
225 cleanup_dentry_buf(struct reiserfs_dentry_buf *buf)
226 {
227 int i;
228
229 for (i = 0; i < buf->count; i++)
230 if (buf->dentries[i])
231 dput(buf->dentries[i]);
232 }
233
234 static int reiserfs_for_each_xattr(struct inode *inode,
235 int (*action)(struct dentry *, void *),
236 void *data)
237 {
238 struct dentry *dir;
239 int i, err = 0;
240 struct reiserfs_dentry_buf buf = {
241 .ctx.actor = fill_with_dentries,
242 };
243
244 /* Skip out, an xattr has no xattrs associated with it */
245 if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1)
246 return 0;
247
248 dir = open_xa_dir(inode, XATTR_REPLACE);
249 if (IS_ERR(dir)) {
250 err = PTR_ERR(dir);
251 goto out;
252 } else if (!dir->d_inode) {
253 err = 0;
254 goto out_dir;
255 }
256
257 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
258
259 buf.xadir = dir;
260 while (1) {
261 err = reiserfs_readdir_inode(dir->d_inode, &buf.ctx);
262 if (err)
263 break;
264 if (!buf.count)
265 break;
266 for (i = 0; !err && i < buf.count && buf.dentries[i]; i++) {
267 struct dentry *dentry = buf.dentries[i];
268
269 if (!d_is_dir(dentry))
270 err = action(dentry, data);
271
272 dput(dentry);
273 buf.dentries[i] = NULL;
274 }
275 if (err)
276 break;
277 buf.count = 0;
278 }
279 mutex_unlock(&dir->d_inode->i_mutex);
280
281 cleanup_dentry_buf(&buf);
282
283 if (!err) {
284 /*
285 * We start a transaction here to avoid a ABBA situation
286 * between the xattr root's i_mutex and the journal lock.
287 * This doesn't incur much additional overhead since the
288 * new transaction will just nest inside the
289 * outer transaction.
290 */
291 int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 +
292 4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb);
293 struct reiserfs_transaction_handle th;
294
295 reiserfs_write_lock(inode->i_sb);
296 err = journal_begin(&th, inode->i_sb, blocks);
297 reiserfs_write_unlock(inode->i_sb);
298 if (!err) {
299 int jerror;
300
301 mutex_lock_nested(&dir->d_parent->d_inode->i_mutex,
302 I_MUTEX_XATTR);
303 err = action(dir, data);
304 reiserfs_write_lock(inode->i_sb);
305 jerror = journal_end(&th);
306 reiserfs_write_unlock(inode->i_sb);
307 mutex_unlock(&dir->d_parent->d_inode->i_mutex);
308 err = jerror ?: err;
309 }
310 }
311 out_dir:
312 dput(dir);
313 out:
314 /* -ENODATA isn't an error */
315 if (err == -ENODATA)
316 err = 0;
317 return err;
318 }
319
320 static int delete_one_xattr(struct dentry *dentry, void *data)
321 {
322 struct inode *dir = dentry->d_parent->d_inode;
323
324 /* This is the xattr dir, handle specially. */
325 if (d_is_dir(dentry))
326 return xattr_rmdir(dir, dentry);
327
328 return xattr_unlink(dir, dentry);
329 }
330
331 static int chown_one_xattr(struct dentry *dentry, void *data)
332 {
333 struct iattr *attrs = data;
334 int ia_valid = attrs->ia_valid;
335 int err;
336
337 /*
338 * We only want the ownership bits. Otherwise, we'll do
339 * things like change a directory to a regular file if
340 * ATTR_MODE is set.
341 */
342 attrs->ia_valid &= (ATTR_UID|ATTR_GID);
343 err = reiserfs_setattr(dentry, attrs);
344 attrs->ia_valid = ia_valid;
345
346 return err;
347 }
348
349 /* No i_mutex, but the inode is unconnected. */
350 int reiserfs_delete_xattrs(struct inode *inode)
351 {
352 int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL);
353
354 if (err)
355 reiserfs_warning(inode->i_sb, "jdm-20004",
356 "Couldn't delete all xattrs (%d)\n", err);
357 return err;
358 }
359
360 /* inode->i_mutex: down */
361 int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
362 {
363 int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs);
364
365 if (err)
366 reiserfs_warning(inode->i_sb, "jdm-20007",
367 "Couldn't chown all xattrs (%d)\n", err);
368 return err;
369 }
370
371 #ifdef CONFIG_REISERFS_FS_XATTR
372 /*
373 * Returns a dentry corresponding to a specific extended attribute file
374 * for the inode. If flags allow, the file is created. Otherwise, a
375 * valid or negative dentry, or an error is returned.
376 */
377 static struct dentry *xattr_lookup(struct inode *inode, const char *name,
378 int flags)
379 {
380 struct dentry *xadir, *xafile;
381 int err = 0;
382
383 xadir = open_xa_dir(inode, flags);
384 if (IS_ERR(xadir))
385 return ERR_CAST(xadir);
386
387 mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
388 xafile = lookup_one_len(name, xadir, strlen(name));
389 if (IS_ERR(xafile)) {
390 err = PTR_ERR(xafile);
391 goto out;
392 }
393
394 if (xafile->d_inode && (flags & XATTR_CREATE))
395 err = -EEXIST;
396
397 if (!xafile->d_inode) {
398 err = -ENODATA;
399 if (xattr_may_create(flags))
400 err = xattr_create(xadir->d_inode, xafile,
401 0700|S_IFREG);
402 }
403
404 if (err)
405 dput(xafile);
406 out:
407 mutex_unlock(&xadir->d_inode->i_mutex);
408 dput(xadir);
409 if (err)
410 return ERR_PTR(err);
411 return xafile;
412 }
413
414 /* Internal operations on file data */
415 static inline void reiserfs_put_page(struct page *page)
416 {
417 kunmap(page);
418 page_cache_release(page);
419 }
420
421 static struct page *reiserfs_get_page(struct inode *dir, size_t n)
422 {
423 struct address_space *mapping = dir->i_mapping;
424 struct page *page;
425 /*
426 * We can deadlock if we try to free dentries,
427 * and an unlink/rmdir has just occurred - GFP_NOFS avoids this
428 */
429 mapping_set_gfp_mask(mapping, GFP_NOFS);
430 page = read_mapping_page(mapping, n >> PAGE_CACHE_SHIFT, NULL);
431 if (!IS_ERR(page)) {
432 kmap(page);
433 if (PageError(page))
434 goto fail;
435 }
436 return page;
437
438 fail:
439 reiserfs_put_page(page);
440 return ERR_PTR(-EIO);
441 }
442
443 static inline __u32 xattr_hash(const char *msg, int len)
444 {
445 return csum_partial(msg, len, 0);
446 }
447
448 int reiserfs_commit_write(struct file *f, struct page *page,
449 unsigned from, unsigned to);
450
451 static void update_ctime(struct inode *inode)
452 {
453 struct timespec now = current_fs_time(inode->i_sb);
454
455 if (inode_unhashed(inode) || !inode->i_nlink ||
456 timespec_equal(&inode->i_ctime, &now))
457 return;
458
459 inode->i_ctime = CURRENT_TIME_SEC;
460 mark_inode_dirty(inode);
461 }
462
463 static int lookup_and_delete_xattr(struct inode *inode, const char *name)
464 {
465 int err = 0;
466 struct dentry *dentry, *xadir;
467
468 xadir = open_xa_dir(inode, XATTR_REPLACE);
469 if (IS_ERR(xadir))
470 return PTR_ERR(xadir);
471
472 mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
473 dentry = lookup_one_len(name, xadir, strlen(name));
474 if (IS_ERR(dentry)) {
475 err = PTR_ERR(dentry);
476 goto out_dput;
477 }
478
479 if (dentry->d_inode) {
480 err = xattr_unlink(xadir->d_inode, dentry);
481 update_ctime(inode);
482 }
483
484 dput(dentry);
485 out_dput:
486 mutex_unlock(&xadir->d_inode->i_mutex);
487 dput(xadir);
488 return err;
489 }
490
491
492 /* Generic extended attribute operations that can be used by xa plugins */
493
494 /*
495 * inode->i_mutex: down
496 */
497 int
498 reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
499 struct inode *inode, const char *name,
500 const void *buffer, size_t buffer_size, int flags)
501 {
502 int err = 0;
503 struct dentry *dentry;
504 struct page *page;
505 char *data;
506 size_t file_pos = 0;
507 size_t buffer_pos = 0;
508 size_t new_size;
509 __u32 xahash = 0;
510
511 if (get_inode_sd_version(inode) == STAT_DATA_V1)
512 return -EOPNOTSUPP;
513
514 if (!buffer) {
515 err = lookup_and_delete_xattr(inode, name);
516 return err;
517 }
518
519 dentry = xattr_lookup(inode, name, flags);
520 if (IS_ERR(dentry))
521 return PTR_ERR(dentry);
522
523 down_write(&REISERFS_I(inode)->i_xattr_sem);
524
525 xahash = xattr_hash(buffer, buffer_size);
526 while (buffer_pos < buffer_size || buffer_pos == 0) {
527 size_t chunk;
528 size_t skip = 0;
529 size_t page_offset = (file_pos & (PAGE_CACHE_SIZE - 1));
530
531 if (buffer_size - buffer_pos > PAGE_CACHE_SIZE)
532 chunk = PAGE_CACHE_SIZE;
533 else
534 chunk = buffer_size - buffer_pos;
535
536 page = reiserfs_get_page(dentry->d_inode, file_pos);
537 if (IS_ERR(page)) {
538 err = PTR_ERR(page);
539 goto out_unlock;
540 }
541
542 lock_page(page);
543 data = page_address(page);
544
545 if (file_pos == 0) {
546 struct reiserfs_xattr_header *rxh;
547
548 skip = file_pos = sizeof(struct reiserfs_xattr_header);
549 if (chunk + skip > PAGE_CACHE_SIZE)
550 chunk = PAGE_CACHE_SIZE - skip;
551 rxh = (struct reiserfs_xattr_header *)data;
552 rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
553 rxh->h_hash = cpu_to_le32(xahash);
554 }
555
556 reiserfs_write_lock(inode->i_sb);
557 err = __reiserfs_write_begin(page, page_offset, chunk + skip);
558 if (!err) {
559 if (buffer)
560 memcpy(data + skip, buffer + buffer_pos, chunk);
561 err = reiserfs_commit_write(NULL, page, page_offset,
562 page_offset + chunk +
563 skip);
564 }
565 reiserfs_write_unlock(inode->i_sb);
566 unlock_page(page);
567 reiserfs_put_page(page);
568 buffer_pos += chunk;
569 file_pos += chunk;
570 skip = 0;
571 if (err || buffer_size == 0 || !buffer)
572 break;
573 }
574
575 new_size = buffer_size + sizeof(struct reiserfs_xattr_header);
576 if (!err && new_size < i_size_read(dentry->d_inode)) {
577 struct iattr newattrs = {
578 .ia_ctime = current_fs_time(inode->i_sb),
579 .ia_size = new_size,
580 .ia_valid = ATTR_SIZE | ATTR_CTIME,
581 };
582
583 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
584 inode_dio_wait(dentry->d_inode);
585
586 err = reiserfs_setattr(dentry, &newattrs);
587 mutex_unlock(&dentry->d_inode->i_mutex);
588 } else
589 update_ctime(inode);
590 out_unlock:
591 up_write(&REISERFS_I(inode)->i_xattr_sem);
592 dput(dentry);
593 return err;
594 }
595
596 /* We need to start a transaction to maintain lock ordering */
597 int reiserfs_xattr_set(struct inode *inode, const char *name,
598 const void *buffer, size_t buffer_size, int flags)
599 {
600
601 struct reiserfs_transaction_handle th;
602 int error, error2;
603 size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size);
604
605 if (!(flags & XATTR_REPLACE))
606 jbegin_count += reiserfs_xattr_jcreate_nblocks(inode);
607
608 reiserfs_write_lock(inode->i_sb);
609 error = journal_begin(&th, inode->i_sb, jbegin_count);
610 reiserfs_write_unlock(inode->i_sb);
611 if (error) {
612 return error;
613 }
614
615 error = reiserfs_xattr_set_handle(&th, inode, name,
616 buffer, buffer_size, flags);
617
618 reiserfs_write_lock(inode->i_sb);
619 error2 = journal_end(&th);
620 reiserfs_write_unlock(inode->i_sb);
621 if (error == 0)
622 error = error2;
623
624 return error;
625 }
626
627 /*
628 * inode->i_mutex: down
629 */
630 int
631 reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer,
632 size_t buffer_size)
633 {
634 ssize_t err = 0;
635 struct dentry *dentry;
636 size_t isize;
637 size_t file_pos = 0;
638 size_t buffer_pos = 0;
639 struct page *page;
640 __u32 hash = 0;
641
642 if (name == NULL)
643 return -EINVAL;
644
645 /*
646 * We can't have xattrs attached to v1 items since they don't have
647 * generation numbers
648 */
649 if (get_inode_sd_version(inode) == STAT_DATA_V1)
650 return -EOPNOTSUPP;
651
652 dentry = xattr_lookup(inode, name, XATTR_REPLACE);
653 if (IS_ERR(dentry)) {
654 err = PTR_ERR(dentry);
655 goto out;
656 }
657
658 down_read(&REISERFS_I(inode)->i_xattr_sem);
659
660 isize = i_size_read(dentry->d_inode);
661
662 /* Just return the size needed */
663 if (buffer == NULL) {
664 err = isize - sizeof(struct reiserfs_xattr_header);
665 goto out_unlock;
666 }
667
668 if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
669 err = -ERANGE;
670 goto out_unlock;
671 }
672
673 while (file_pos < isize) {
674 size_t chunk;
675 char *data;
676 size_t skip = 0;
677
678 if (isize - file_pos > PAGE_CACHE_SIZE)
679 chunk = PAGE_CACHE_SIZE;
680 else
681 chunk = isize - file_pos;
682
683 page = reiserfs_get_page(dentry->d_inode, file_pos);
684 if (IS_ERR(page)) {
685 err = PTR_ERR(page);
686 goto out_unlock;
687 }
688
689 lock_page(page);
690 data = page_address(page);
691 if (file_pos == 0) {
692 struct reiserfs_xattr_header *rxh =
693 (struct reiserfs_xattr_header *)data;
694 skip = file_pos = sizeof(struct reiserfs_xattr_header);
695 chunk -= skip;
696 /* Magic doesn't match up.. */
697 if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
698 unlock_page(page);
699 reiserfs_put_page(page);
700 reiserfs_warning(inode->i_sb, "jdm-20001",
701 "Invalid magic for xattr (%s) "
702 "associated with %k", name,
703 INODE_PKEY(inode));
704 err = -EIO;
705 goto out_unlock;
706 }
707 hash = le32_to_cpu(rxh->h_hash);
708 }
709 memcpy(buffer + buffer_pos, data + skip, chunk);
710 unlock_page(page);
711 reiserfs_put_page(page);
712 file_pos += chunk;
713 buffer_pos += chunk;
714 skip = 0;
715 }
716 err = isize - sizeof(struct reiserfs_xattr_header);
717
718 if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
719 hash) {
720 reiserfs_warning(inode->i_sb, "jdm-20002",
721 "Invalid hash for xattr (%s) associated "
722 "with %k", name, INODE_PKEY(inode));
723 err = -EIO;
724 }
725
726 out_unlock:
727 up_read(&REISERFS_I(inode)->i_xattr_sem);
728 dput(dentry);
729
730 out:
731 return err;
732 }
733
734 /*
735 * In order to implement different sets of xattr operations for each xattr
736 * prefix with the generic xattr API, a filesystem should create a
737 * null-terminated array of struct xattr_handler (one for each prefix) and
738 * hang a pointer to it off of the s_xattr field of the superblock.
739 *
740 * The generic_fooxattr() functions will use this list to dispatch xattr
741 * operations to the correct xattr_handler.
742 */
743 #define for_each_xattr_handler(handlers, handler) \
744 for ((handler) = *(handlers)++; \
745 (handler) != NULL; \
746 (handler) = *(handlers)++)
747
748 /* This is the implementation for the xattr plugin infrastructure */
749 static inline const struct xattr_handler *
750 find_xattr_handler_prefix(const struct xattr_handler **handlers,
751 const char *name)
752 {
753 const struct xattr_handler *xah;
754
755 if (!handlers)
756 return NULL;
757
758 for_each_xattr_handler(handlers, xah) {
759 if (strncmp(xah->prefix, name, strlen(xah->prefix)) == 0)
760 break;
761 }
762
763 return xah;
764 }
765
766
767 /*
768 * Inode operation getxattr()
769 */
770 ssize_t
771 reiserfs_getxattr(struct dentry * dentry, const char *name, void *buffer,
772 size_t size)
773 {
774 const struct xattr_handler *handler;
775
776 handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
777
778 if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
779 return -EOPNOTSUPP;
780
781 return handler->get(dentry, name, buffer, size, handler->flags);
782 }
783
784 /*
785 * Inode operation setxattr()
786 *
787 * dentry->d_inode->i_mutex down
788 */
789 int
790 reiserfs_setxattr(struct dentry *dentry, const char *name, const void *value,
791 size_t size, int flags)
792 {
793 const struct xattr_handler *handler;
794
795 handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
796
797 if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
798 return -EOPNOTSUPP;
799
800 return handler->set(dentry, name, value, size, flags, handler->flags);
801 }
802
803 /*
804 * Inode operation removexattr()
805 *
806 * dentry->d_inode->i_mutex down
807 */
808 int reiserfs_removexattr(struct dentry *dentry, const char *name)
809 {
810 const struct xattr_handler *handler;
811
812 handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
813
814 if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
815 return -EOPNOTSUPP;
816
817 return handler->set(dentry, name, NULL, 0, XATTR_REPLACE, handler->flags);
818 }
819
820 struct listxattr_buf {
821 struct dir_context ctx;
822 size_t size;
823 size_t pos;
824 char *buf;
825 struct dentry *dentry;
826 };
827
828 static int listxattr_filler(struct dir_context *ctx, const char *name,
829 int namelen, loff_t offset, u64 ino,
830 unsigned int d_type)
831 {
832 struct listxattr_buf *b =
833 container_of(ctx, struct listxattr_buf, ctx);
834 size_t size;
835
836 if (name[0] != '.' ||
837 (namelen != 1 && (name[1] != '.' || namelen != 2))) {
838 const struct xattr_handler *handler;
839
840 handler = find_xattr_handler_prefix(b->dentry->d_sb->s_xattr,
841 name);
842 if (!handler) /* Unsupported xattr name */
843 return 0;
844 if (b->buf) {
845 size = handler->list(b->dentry, b->buf + b->pos,
846 b->size, name, namelen,
847 handler->flags);
848 if (size > b->size)
849 return -ERANGE;
850 } else {
851 size = handler->list(b->dentry, NULL, 0, name,
852 namelen, handler->flags);
853 }
854
855 b->pos += size;
856 }
857 return 0;
858 }
859
860 /*
861 * Inode operation listxattr()
862 *
863 * We totally ignore the generic listxattr here because it would be stupid
864 * not to. Since the xattrs are organized in a directory, we can just
865 * readdir to find them.
866 */
867 ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
868 {
869 struct dentry *dir;
870 int err = 0;
871 struct listxattr_buf buf = {
872 .ctx.actor = listxattr_filler,
873 .dentry = dentry,
874 .buf = buffer,
875 .size = buffer ? size : 0,
876 };
877
878 if (!dentry->d_inode)
879 return -EINVAL;
880
881 if (!dentry->d_sb->s_xattr ||
882 get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
883 return -EOPNOTSUPP;
884
885 dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE);
886 if (IS_ERR(dir)) {
887 err = PTR_ERR(dir);
888 if (err == -ENODATA)
889 err = 0; /* Not an error if there aren't any xattrs */
890 goto out;
891 }
892
893 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
894 err = reiserfs_readdir_inode(dir->d_inode, &buf.ctx);
895 mutex_unlock(&dir->d_inode->i_mutex);
896
897 if (!err)
898 err = buf.pos;
899
900 dput(dir);
901 out:
902 return err;
903 }
904
905 static int create_privroot(struct dentry *dentry)
906 {
907 int err;
908 struct inode *inode = dentry->d_parent->d_inode;
909
910 WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
911
912 err = xattr_mkdir(inode, dentry, 0700);
913 if (err || !dentry->d_inode) {
914 reiserfs_warning(dentry->d_sb, "jdm-20006",
915 "xattrs/ACLs enabled and couldn't "
916 "find/create .reiserfs_priv. "
917 "Failing mount.");
918 return -EOPNOTSUPP;
919 }
920
921 dentry->d_inode->i_flags |= S_PRIVATE;
922 reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
923 "storage.\n", PRIVROOT_NAME);
924
925 return 0;
926 }
927
928 #else
929 int __init reiserfs_xattr_register_handlers(void) { return 0; }
930 void reiserfs_xattr_unregister_handlers(void) {}
931 static int create_privroot(struct dentry *dentry) { return 0; }
932 #endif
933
934 /* Actual operations that are exported to VFS-land */
935 static const struct xattr_handler *reiserfs_xattr_handlers[] = {
936 #ifdef CONFIG_REISERFS_FS_XATTR
937 &reiserfs_xattr_user_handler,
938 &reiserfs_xattr_trusted_handler,
939 #endif
940 #ifdef CONFIG_REISERFS_FS_SECURITY
941 &reiserfs_xattr_security_handler,
942 #endif
943 #ifdef CONFIG_REISERFS_FS_POSIX_ACL
944 &posix_acl_access_xattr_handler,
945 &posix_acl_default_xattr_handler,
946 #endif
947 NULL
948 };
949
950 static int xattr_mount_check(struct super_block *s)
951 {
952 /*
953 * We need generation numbers to ensure that the oid mapping is correct
954 * v3.5 filesystems don't have them.
955 */
956 if (old_format_only(s)) {
957 if (reiserfs_xattrs_optional(s)) {
958 /*
959 * Old format filesystem, but optional xattrs have
960 * been enabled. Error out.
961 */
962 reiserfs_warning(s, "jdm-2005",
963 "xattrs/ACLs not supported "
964 "on pre-v3.6 format filesystems. "
965 "Failing mount.");
966 return -EOPNOTSUPP;
967 }
968 }
969
970 return 0;
971 }
972
973 int reiserfs_permission(struct inode *inode, int mask)
974 {
975 /*
976 * We don't do permission checks on the internal objects.
977 * Permissions are determined by the "owning" object.
978 */
979 if (IS_PRIVATE(inode))
980 return 0;
981
982 return generic_permission(inode, mask);
983 }
984
985 static int xattr_hide_revalidate(struct dentry *dentry, unsigned int flags)
986 {
987 return -EPERM;
988 }
989
990 static const struct dentry_operations xattr_lookup_poison_ops = {
991 .d_revalidate = xattr_hide_revalidate,
992 };
993
994 int reiserfs_lookup_privroot(struct super_block *s)
995 {
996 struct dentry *dentry;
997 int err = 0;
998
999 /* If we don't have the privroot located yet - go find it */
1000 mutex_lock(&s->s_root->d_inode->i_mutex);
1001 dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
1002 strlen(PRIVROOT_NAME));
1003 if (!IS_ERR(dentry)) {
1004 REISERFS_SB(s)->priv_root = dentry;
1005 d_set_d_op(dentry, &xattr_lookup_poison_ops);
1006 if (dentry->d_inode)
1007 dentry->d_inode->i_flags |= S_PRIVATE;
1008 } else
1009 err = PTR_ERR(dentry);
1010 mutex_unlock(&s->s_root->d_inode->i_mutex);
1011
1012 return err;
1013 }
1014
1015 /*
1016 * We need to take a copy of the mount flags since things like
1017 * MS_RDONLY don't get set until *after* we're called.
1018 * mount_flags != mount_options
1019 */
1020 int reiserfs_xattr_init(struct super_block *s, int mount_flags)
1021 {
1022 int err = 0;
1023 struct dentry *privroot = REISERFS_SB(s)->priv_root;
1024
1025 err = xattr_mount_check(s);
1026 if (err)
1027 goto error;
1028
1029 if (!privroot->d_inode && !(mount_flags & MS_RDONLY)) {
1030 mutex_lock(&s->s_root->d_inode->i_mutex);
1031 err = create_privroot(REISERFS_SB(s)->priv_root);
1032 mutex_unlock(&s->s_root->d_inode->i_mutex);
1033 }
1034
1035 if (privroot->d_inode) {
1036 s->s_xattr = reiserfs_xattr_handlers;
1037 mutex_lock(&privroot->d_inode->i_mutex);
1038 if (!REISERFS_SB(s)->xattr_root) {
1039 struct dentry *dentry;
1040
1041 dentry = lookup_one_len(XAROOT_NAME, privroot,
1042 strlen(XAROOT_NAME));
1043 if (!IS_ERR(dentry))
1044 REISERFS_SB(s)->xattr_root = dentry;
1045 else
1046 err = PTR_ERR(dentry);
1047 }
1048 mutex_unlock(&privroot->d_inode->i_mutex);
1049 }
1050
1051 error:
1052 if (err) {
1053 clear_bit(REISERFS_XATTRS_USER, &REISERFS_SB(s)->s_mount_opt);
1054 clear_bit(REISERFS_POSIXACL, &REISERFS_SB(s)->s_mount_opt);
1055 }
1056
1057 /* The super_block MS_POSIXACL must mirror the (no)acl mount option. */
1058 if (reiserfs_posixacl(s))
1059 s->s_flags |= MS_POSIXACL;
1060 else
1061 s->s_flags &= ~MS_POSIXACL;
1062
1063 return err;
1064 }