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