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TOMOYO Linux Cross Reference
Linux/fs/reiserfs/xattr.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * linux/fs/reiserfs/xattr.c
  4  *
  5  * Copyright (c) 2002 by Jeff Mahoney, <jeffm@suse.com>
  6  *
  7  */
  8 
  9 /*
 10  * In order to implement EA/ACLs in a clean, backwards compatible manner,
 11  * they are implemented as files in a "private" directory.
 12  * Each EA is in it's own file, with the directory layout like so (/ is assumed
 13  * to be relative to fs root). Inside the /.reiserfs_priv/xattrs directory,
 14  * directories named using the capital-hex form of the objectid and
 15  * generation number are used. Inside each directory are individual files
 16  * named with the name of the extended attribute.
 17  *
 18  * So, for objectid 12648430, we could have:
 19  * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_access
 20  * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_default
 21  * /.reiserfs_priv/xattrs/C0FFEE.0/user.Content-Type
 22  * .. or similar.
 23  *
 24  * The file contents are the text of the EA. The size is known based on the
 25  * stat data describing the file.
 26  *
 27  * In the case of system.posix_acl_access and system.posix_acl_default, since
 28  * these are special cases for filesystem ACLs, they are interpreted by the
 29  * kernel, in addition, they are negatively and positively cached and attached
 30  * to the inode so that unnecessary lookups are avoided.
 31  *
 32  * Locking works like so:
 33  * Directory components (xattr root, xattr dir) are protectd by their i_mutex.
 34  * The xattrs themselves are protected by the xattr_sem.
 35  */
 36 
 37 #include "reiserfs.h"
 38 #include <linux/capability.h>
 39 #include <linux/dcache.h>
 40 #include <linux/namei.h>
 41 #include <linux/errno.h>
 42 #include <linux/gfp.h>
 43 #include <linux/fs.h>
 44 #include <linux/file.h>
 45 #include <linux/pagemap.h>
 46 #include <linux/xattr.h>
 47 #include "xattr.h"
 48 #include "acl.h"
 49 #include <linux/uaccess.h>
 50 #include <net/checksum.h>
 51 #include <linux/stat.h>
 52 #include <linux/quotaops.h>
 53 #include <linux/security.h>
 54 #include <linux/posix_acl_xattr.h>
 55 
 56 #define PRIVROOT_NAME ".reiserfs_priv"
 57 #define XAROOT_NAME   "xattrs"
 58 
 59 
 60 /*
 61  * Helpers for inode ops. We do this so that we don't have all the VFS
 62  * overhead and also for proper i_mutex annotation.
 63  * dir->i_mutex must be held for all of them.
 64  */
 65 #ifdef CONFIG_REISERFS_FS_XATTR
 66 static int xattr_create(struct inode *dir, struct dentry *dentry, int mode)
 67 {
 68         BUG_ON(!inode_is_locked(dir));
 69         return dir->i_op->create(dir, dentry, mode, true);
 70 }
 71 #endif
 72 
 73 static int xattr_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 74 {
 75         BUG_ON(!inode_is_locked(dir));
 76         return dir->i_op->mkdir(dir, dentry, mode);
 77 }
 78 
 79 /*
 80  * We use I_MUTEX_CHILD here to silence lockdep. It's safe because xattr
 81  * mutation ops aren't called during rename or splace, which are the
 82  * only other users of I_MUTEX_CHILD. It violates the ordering, but that's
 83  * better than allocating another subclass just for this code.
 84  */
 85 static int xattr_unlink(struct inode *dir, struct dentry *dentry)
 86 {
 87         int error;
 88 
 89         BUG_ON(!inode_is_locked(dir));
 90 
 91         inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
 92         error = dir->i_op->unlink(dir, dentry);
 93         inode_unlock(d_inode(dentry));
 94 
 95         if (!error)
 96                 d_delete(dentry);
 97         return error;
 98 }
 99 
100 static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
101 {
102         int error;
103 
104         BUG_ON(!inode_is_locked(dir));
105 
106         inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
107         error = dir->i_op->rmdir(dir, dentry);
108         if (!error)
109                 d_inode(dentry)->i_flags |= S_DEAD;
110         inode_unlock(d_inode(dentry));
111         if (!error)
112                 d_delete(dentry);
113 
114         return error;
115 }
116 
117 #define xattr_may_create(flags) (!flags || flags & XATTR_CREATE)
118 
119 static struct dentry *open_xa_root(struct super_block *sb, int flags)
120 {
121         struct dentry *privroot = REISERFS_SB(sb)->priv_root;
122         struct dentry *xaroot;
123 
124         if (d_really_is_negative(privroot))
125                 return ERR_PTR(-ENODATA);
126 
127         inode_lock_nested(d_inode(privroot), I_MUTEX_XATTR);
128 
129         xaroot = dget(REISERFS_SB(sb)->xattr_root);
130         if (!xaroot)
131                 xaroot = ERR_PTR(-ENODATA);
132         else if (d_really_is_negative(xaroot)) {
133                 int err = -ENODATA;
134 
135                 if (xattr_may_create(flags))
136                         err = xattr_mkdir(d_inode(privroot), xaroot, 0700);
137                 if (err) {
138                         dput(xaroot);
139                         xaroot = ERR_PTR(err);
140                 }
141         }
142 
143         inode_unlock(d_inode(privroot));
144         return xaroot;
145 }
146 
147 static struct dentry *open_xa_dir(const struct inode *inode, int flags)
148 {
149         struct dentry *xaroot, *xadir;
150         char namebuf[17];
151 
152         xaroot = open_xa_root(inode->i_sb, flags);
153         if (IS_ERR(xaroot))
154                 return xaroot;
155 
156         snprintf(namebuf, sizeof(namebuf), "%X.%X",
157                  le32_to_cpu(INODE_PKEY(inode)->k_objectid),
158                  inode->i_generation);
159 
160         inode_lock_nested(d_inode(xaroot), I_MUTEX_XATTR);
161 
162         xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
163         if (!IS_ERR(xadir) && d_really_is_negative(xadir)) {
164                 int err = -ENODATA;
165 
166                 if (xattr_may_create(flags))
167                         err = xattr_mkdir(d_inode(xaroot), xadir, 0700);
168                 if (err) {
169                         dput(xadir);
170                         xadir = ERR_PTR(err);
171                 }
172         }
173 
174         inode_unlock(d_inode(xaroot));
175         dput(xaroot);
176         return xadir;
177 }
178 
179 /*
180  * The following are side effects of other operations that aren't explicitly
181  * modifying extended attributes. This includes operations such as permissions
182  * or ownership changes, object deletions, etc.
183  */
184 struct reiserfs_dentry_buf {
185         struct dir_context ctx;
186         struct dentry *xadir;
187         int count;
188         struct dentry *dentries[8];
189 };
190 
191 static int
192 fill_with_dentries(struct dir_context *ctx, const char *name, int namelen,
193                    loff_t offset, u64 ino, unsigned int d_type)
194 {
195         struct reiserfs_dentry_buf *dbuf =
196                 container_of(ctx, struct reiserfs_dentry_buf, ctx);
197         struct dentry *dentry;
198 
199         WARN_ON_ONCE(!inode_is_locked(d_inode(dbuf->xadir)));
200 
201         if (dbuf->count == ARRAY_SIZE(dbuf->dentries))
202                 return -ENOSPC;
203 
204         if (name[0] == '.' && (namelen < 2 ||
205                                (namelen == 2 && name[1] == '.')))
206                 return 0;
207 
208         dentry = lookup_one_len(name, dbuf->xadir, namelen);
209         if (IS_ERR(dentry)) {
210                 return PTR_ERR(dentry);
211         } else if (d_really_is_negative(dentry)) {
212                 /* A directory entry exists, but no file? */
213                 reiserfs_error(dentry->d_sb, "xattr-20003",
214                                "Corrupted directory: xattr %pd listed but "
215                                "not found for file %pd.\n",
216                                dentry, dbuf->xadir);
217                 dput(dentry);
218                 return -EIO;
219         }
220 
221         dbuf->dentries[dbuf->count++] = dentry;
222         return 0;
223 }
224 
225 static void
226 cleanup_dentry_buf(struct reiserfs_dentry_buf *buf)
227 {
228         int i;
229 
230         for (i = 0; i < buf->count; i++)
231                 if (buf->dentries[i])
232                         dput(buf->dentries[i]);
233 }
234 
235 static int reiserfs_for_each_xattr(struct inode *inode,
236                                    int (*action)(struct dentry *, void *),
237                                    void *data)
238 {
239         struct dentry *dir;
240         int i, err = 0;
241         struct reiserfs_dentry_buf buf = {
242                 .ctx.actor = fill_with_dentries,
243         };
244 
245         /* Skip out, an xattr has no xattrs associated with it */
246         if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1)
247                 return 0;
248 
249         dir = open_xa_dir(inode, XATTR_REPLACE);
250         if (IS_ERR(dir)) {
251                 err = PTR_ERR(dir);
252                 goto out;
253         } else if (d_really_is_negative(dir)) {
254                 err = 0;
255                 goto out_dir;
256         }
257 
258         inode_lock_nested(d_inode(dir), I_MUTEX_XATTR);
259 
260         buf.xadir = dir;
261         while (1) {
262                 err = reiserfs_readdir_inode(d_inode(dir), &buf.ctx);
263                 if (err)
264                         break;
265                 if (!buf.count)
266                         break;
267                 for (i = 0; !err && i < buf.count && buf.dentries[i]; i++) {
268                         struct dentry *dentry = buf.dentries[i];
269 
270                         if (!d_is_dir(dentry))
271                                 err = action(dentry, data);
272 
273                         dput(dentry);
274                         buf.dentries[i] = NULL;
275                 }
276                 if (err)
277                         break;
278                 buf.count = 0;
279         }
280         inode_unlock(d_inode(dir));
281 
282         cleanup_dentry_buf(&buf);
283 
284         if (!err) {
285                 /*
286                  * We start a transaction here to avoid a ABBA situation
287                  * between the xattr root's i_mutex and the journal lock.
288                  * This doesn't incur much additional overhead since the
289                  * new transaction will just nest inside the
290                  * outer transaction.
291                  */
292                 int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 +
293                              4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb);
294                 struct reiserfs_transaction_handle th;
295 
296                 reiserfs_write_lock(inode->i_sb);
297                 err = journal_begin(&th, inode->i_sb, blocks);
298                 reiserfs_write_unlock(inode->i_sb);
299                 if (!err) {
300                         int jerror;
301 
302                         inode_lock_nested(d_inode(dir->d_parent),
303                                           I_MUTEX_XATTR);
304                         err = action(dir, data);
305                         reiserfs_write_lock(inode->i_sb);
306                         jerror = journal_end(&th);
307                         reiserfs_write_unlock(inode->i_sb);
308                         inode_unlock(d_inode(dir->d_parent));
309                         err = jerror ?: err;
310                 }
311         }
312 out_dir:
313         dput(dir);
314 out:
315         /* -ENODATA isn't an error */
316         if (err == -ENODATA)
317                 err = 0;
318         return err;
319 }
320 
321 static int delete_one_xattr(struct dentry *dentry, void *data)
322 {
323         struct inode *dir = d_inode(dentry->d_parent);
324 
325         /* This is the xattr dir, handle specially. */
326         if (d_is_dir(dentry))
327                 return xattr_rmdir(dir, dentry);
328 
329         return xattr_unlink(dir, dentry);
330 }
331 
332 static int chown_one_xattr(struct dentry *dentry, void *data)
333 {
334         struct iattr *attrs = data;
335         int ia_valid = attrs->ia_valid;
336         int err;
337 
338         /*
339          * We only want the ownership bits. Otherwise, we'll do
340          * things like change a directory to a regular file if
341          * ATTR_MODE is set.
342          */
343         attrs->ia_valid &= (ATTR_UID|ATTR_GID);
344         err = reiserfs_setattr(dentry, attrs);
345         attrs->ia_valid = ia_valid;
346 
347         return err;
348 }
349 
350 /* No i_mutex, but the inode is unconnected. */
351 int reiserfs_delete_xattrs(struct inode *inode)
352 {
353         int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL);
354 
355         if (err)
356                 reiserfs_warning(inode->i_sb, "jdm-20004",
357                                  "Couldn't delete all xattrs (%d)\n", err);
358         return err;
359 }
360 
361 /* inode->i_mutex: down */
362 int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
363 {
364         int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs);
365 
366         if (err)
367                 reiserfs_warning(inode->i_sb, "jdm-20007",
368                                  "Couldn't chown all xattrs (%d)\n", err);
369         return err;
370 }
371 
372 #ifdef CONFIG_REISERFS_FS_XATTR
373 /*
374  * Returns a dentry corresponding to a specific extended attribute file
375  * for the inode. If flags allow, the file is created. Otherwise, a
376  * valid or negative dentry, or an error is returned.
377  */
378 static struct dentry *xattr_lookup(struct inode *inode, const char *name,
379                                     int flags)
380 {
381         struct dentry *xadir, *xafile;
382         int err = 0;
383 
384         xadir = open_xa_dir(inode, flags);
385         if (IS_ERR(xadir))
386                 return ERR_CAST(xadir);
387 
388         inode_lock_nested(d_inode(xadir), I_MUTEX_XATTR);
389         xafile = lookup_one_len(name, xadir, strlen(name));
390         if (IS_ERR(xafile)) {
391                 err = PTR_ERR(xafile);
392                 goto out;
393         }
394 
395         if (d_really_is_positive(xafile) && (flags & XATTR_CREATE))
396                 err = -EEXIST;
397 
398         if (d_really_is_negative(xafile)) {
399                 err = -ENODATA;
400                 if (xattr_may_create(flags))
401                         err = xattr_create(d_inode(xadir), xafile,
402                                               0700|S_IFREG);
403         }
404 
405         if (err)
406                 dput(xafile);
407 out:
408         inode_unlock(d_inode(xadir));
409         dput(xadir);
410         if (err)
411                 return ERR_PTR(err);
412         return xafile;
413 }
414 
415 /* Internal operations on file data */
416 static inline void reiserfs_put_page(struct page *page)
417 {
418         kunmap(page);
419         put_page(page);
420 }
421 
422 static struct page *reiserfs_get_page(struct inode *dir, size_t n)
423 {
424         struct address_space *mapping = dir->i_mapping;
425         struct page *page;
426         /*
427          * We can deadlock if we try to free dentries,
428          * and an unlink/rmdir has just occurred - GFP_NOFS avoids this
429          */
430         mapping_set_gfp_mask(mapping, GFP_NOFS);
431         page = read_mapping_page(mapping, n >> PAGE_SHIFT, NULL);
432         if (!IS_ERR(page)) {
433                 kmap(page);
434                 if (PageError(page))
435                         goto fail;
436         }
437         return page;
438 
439 fail:
440         reiserfs_put_page(page);
441         return ERR_PTR(-EIO);
442 }
443 
444 static inline __u32 xattr_hash(const char *msg, int len)
445 {
446         return csum_partial(msg, len, 0);
447 }
448 
449 int reiserfs_commit_write(struct file *f, struct page *page,
450                           unsigned from, unsigned to);
451 
452 static void update_ctime(struct inode *inode)
453 {
454         struct timespec now = current_time(inode);
455 
456         if (inode_unhashed(inode) || !inode->i_nlink ||
457             timespec_equal(&inode->i_ctime, &now))
458                 return;
459 
460         inode->i_ctime = current_time(inode);
461         mark_inode_dirty(inode);
462 }
463 
464 static int lookup_and_delete_xattr(struct inode *inode, const char *name)
465 {
466         int err = 0;
467         struct dentry *dentry, *xadir;
468 
469         xadir = open_xa_dir(inode, XATTR_REPLACE);
470         if (IS_ERR(xadir))
471                 return PTR_ERR(xadir);
472 
473         inode_lock_nested(d_inode(xadir), I_MUTEX_XATTR);
474         dentry = lookup_one_len(name, xadir, strlen(name));
475         if (IS_ERR(dentry)) {
476                 err = PTR_ERR(dentry);
477                 goto out_dput;
478         }
479 
480         if (d_really_is_positive(dentry)) {
481                 err = xattr_unlink(d_inode(xadir), dentry);
482                 update_ctime(inode);
483         }
484 
485         dput(dentry);
486 out_dput:
487         inode_unlock(d_inode(xadir));
488         dput(xadir);
489         return err;
490 }
491 
492 
493 /* Generic extended attribute operations that can be used by xa plugins */
494 
495 /*
496  * inode->i_mutex: down
497  */
498 int
499 reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
500                           struct inode *inode, const char *name,
501                           const void *buffer, size_t buffer_size, int flags)
502 {
503         int err = 0;
504         struct dentry *dentry;
505         struct page *page;
506         char *data;
507         size_t file_pos = 0;
508         size_t buffer_pos = 0;
509         size_t new_size;
510         __u32 xahash = 0;
511 
512         if (get_inode_sd_version(inode) == STAT_DATA_V1)
513                 return -EOPNOTSUPP;
514 
515         if (!buffer) {
516                 err = lookup_and_delete_xattr(inode, name);
517                 return err;
518         }
519 
520         dentry = xattr_lookup(inode, name, flags);
521         if (IS_ERR(dentry))
522                 return PTR_ERR(dentry);
523 
524         down_write(&REISERFS_I(inode)->i_xattr_sem);
525 
526         xahash = xattr_hash(buffer, buffer_size);
527         while (buffer_pos < buffer_size || buffer_pos == 0) {
528                 size_t chunk;
529                 size_t skip = 0;
530                 size_t page_offset = (file_pos & (PAGE_SIZE - 1));
531 
532                 if (buffer_size - buffer_pos > PAGE_SIZE)
533                         chunk = PAGE_SIZE;
534                 else
535                         chunk = buffer_size - buffer_pos;
536 
537                 page = reiserfs_get_page(d_inode(dentry), file_pos);
538                 if (IS_ERR(page)) {
539                         err = PTR_ERR(page);
540                         goto out_unlock;
541                 }
542 
543                 lock_page(page);
544                 data = page_address(page);
545 
546                 if (file_pos == 0) {
547                         struct reiserfs_xattr_header *rxh;
548 
549                         skip = file_pos = sizeof(struct reiserfs_xattr_header);
550                         if (chunk + skip > PAGE_SIZE)
551                                 chunk = PAGE_SIZE - skip;
552                         rxh = (struct reiserfs_xattr_header *)data;
553                         rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
554                         rxh->h_hash = cpu_to_le32(xahash);
555                 }
556 
557                 reiserfs_write_lock(inode->i_sb);
558                 err = __reiserfs_write_begin(page, page_offset, chunk + skip);
559                 if (!err) {
560                         if (buffer)
561                                 memcpy(data + skip, buffer + buffer_pos, chunk);
562                         err = reiserfs_commit_write(NULL, page, page_offset,
563                                                     page_offset + chunk +
564                                                     skip);
565                 }
566                 reiserfs_write_unlock(inode->i_sb);
567                 unlock_page(page);
568                 reiserfs_put_page(page);
569                 buffer_pos += chunk;
570                 file_pos += chunk;
571                 skip = 0;
572                 if (err || buffer_size == 0 || !buffer)
573                         break;
574         }
575 
576         new_size = buffer_size + sizeof(struct reiserfs_xattr_header);
577         if (!err && new_size < i_size_read(d_inode(dentry))) {
578                 struct iattr newattrs = {
579                         .ia_ctime = current_time(inode),
580                         .ia_size = new_size,
581                         .ia_valid = ATTR_SIZE | ATTR_CTIME,
582                 };
583 
584                 inode_lock_nested(d_inode(dentry), I_MUTEX_XATTR);
585                 inode_dio_wait(d_inode(dentry));
586 
587                 err = reiserfs_setattr(dentry, &newattrs);
588                 inode_unlock(d_inode(dentry));
589         } else
590                 update_ctime(inode);
591 out_unlock:
592         up_write(&REISERFS_I(inode)->i_xattr_sem);
593         dput(dentry);
594         return err;
595 }
596 
597 /* We need to start a transaction to maintain lock ordering */
598 int reiserfs_xattr_set(struct inode *inode, const char *name,
599                        const void *buffer, size_t buffer_size, int flags)
600 {
601 
602         struct reiserfs_transaction_handle th;
603         int error, error2;
604         size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size);
605 
606         if (!(flags & XATTR_REPLACE))
607                 jbegin_count += reiserfs_xattr_jcreate_nblocks(inode);
608 
609         reiserfs_write_lock(inode->i_sb);
610         error = journal_begin(&th, inode->i_sb, jbegin_count);
611         reiserfs_write_unlock(inode->i_sb);
612         if (error) {
613                 return error;
614         }
615 
616         error = reiserfs_xattr_set_handle(&th, inode, name,
617                                           buffer, buffer_size, flags);
618 
619         reiserfs_write_lock(inode->i_sb);
620         error2 = journal_end(&th);
621         reiserfs_write_unlock(inode->i_sb);
622         if (error == 0)
623                 error = error2;
624 
625         return error;
626 }
627 
628 /*
629  * inode->i_mutex: down
630  */
631 int
632 reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer,
633                    size_t buffer_size)
634 {
635         ssize_t err = 0;
636         struct dentry *dentry;
637         size_t isize;
638         size_t file_pos = 0;
639         size_t buffer_pos = 0;
640         struct page *page;
641         __u32 hash = 0;
642 
643         if (name == NULL)
644                 return -EINVAL;
645 
646         /*
647          * We can't have xattrs attached to v1 items since they don't have
648          * generation numbers
649          */
650         if (get_inode_sd_version(inode) == STAT_DATA_V1)
651                 return -EOPNOTSUPP;
652 
653         dentry = xattr_lookup(inode, name, XATTR_REPLACE);
654         if (IS_ERR(dentry)) {
655                 err = PTR_ERR(dentry);
656                 goto out;
657         }
658 
659         down_read(&REISERFS_I(inode)->i_xattr_sem);
660 
661         isize = i_size_read(d_inode(dentry));
662 
663         /* Just return the size needed */
664         if (buffer == NULL) {
665                 err = isize - sizeof(struct reiserfs_xattr_header);
666                 goto out_unlock;
667         }
668 
669         if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
670                 err = -ERANGE;
671                 goto out_unlock;
672         }
673 
674         while (file_pos < isize) {
675                 size_t chunk;
676                 char *data;
677                 size_t skip = 0;
678 
679                 if (isize - file_pos > PAGE_SIZE)
680                         chunk = PAGE_SIZE;
681                 else
682                         chunk = isize - file_pos;
683 
684                 page = reiserfs_get_page(d_inode(dentry), file_pos);
685                 if (IS_ERR(page)) {
686                         err = PTR_ERR(page);
687                         goto out_unlock;
688                 }
689 
690                 lock_page(page);
691                 data = page_address(page);
692                 if (file_pos == 0) {
693                         struct reiserfs_xattr_header *rxh =
694                             (struct reiserfs_xattr_header *)data;
695                         skip = file_pos = sizeof(struct reiserfs_xattr_header);
696                         chunk -= skip;
697                         /* Magic doesn't match up.. */
698                         if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
699                                 unlock_page(page);
700                                 reiserfs_put_page(page);
701                                 reiserfs_warning(inode->i_sb, "jdm-20001",
702                                                  "Invalid magic for xattr (%s) "
703                                                  "associated with %k", name,
704                                                  INODE_PKEY(inode));
705                                 err = -EIO;
706                                 goto out_unlock;
707                         }
708                         hash = le32_to_cpu(rxh->h_hash);
709                 }
710                 memcpy(buffer + buffer_pos, data + skip, chunk);
711                 unlock_page(page);
712                 reiserfs_put_page(page);
713                 file_pos += chunk;
714                 buffer_pos += chunk;
715                 skip = 0;
716         }
717         err = isize - sizeof(struct reiserfs_xattr_header);
718 
719         if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
720             hash) {
721                 reiserfs_warning(inode->i_sb, "jdm-20002",
722                                  "Invalid hash for xattr (%s) associated "
723                                  "with %k", name, INODE_PKEY(inode));
724                 err = -EIO;
725         }
726 
727 out_unlock:
728         up_read(&REISERFS_I(inode)->i_xattr_sem);
729         dput(dentry);
730 
731 out:
732         return err;
733 }
734 
735 /*
736  * In order to implement different sets of xattr operations for each xattr
737  * prefix with the generic xattr API, a filesystem should create a
738  * null-terminated array of struct xattr_handler (one for each prefix) and
739  * hang a pointer to it off of the s_xattr field of the superblock.
740  *
741  * The generic_fooxattr() functions will use this list to dispatch xattr
742  * operations to the correct xattr_handler.
743  */
744 #define for_each_xattr_handler(handlers, handler)               \
745                 for ((handler) = *(handlers)++;                 \
746                         (handler) != NULL;                      \
747                         (handler) = *(handlers)++)
748 
749 /* This is the implementation for the xattr plugin infrastructure */
750 static inline const struct xattr_handler *
751 find_xattr_handler_prefix(const struct xattr_handler **handlers,
752                            const char *name)
753 {
754         const struct xattr_handler *xah;
755 
756         if (!handlers)
757                 return NULL;
758 
759         for_each_xattr_handler(handlers, xah) {
760                 const char *prefix = xattr_prefix(xah);
761                 if (strncmp(prefix, name, strlen(prefix)) == 0)
762                         break;
763         }
764 
765         return xah;
766 }
767 
768 struct listxattr_buf {
769         struct dir_context ctx;
770         size_t size;
771         size_t pos;
772         char *buf;
773         struct dentry *dentry;
774 };
775 
776 static int listxattr_filler(struct dir_context *ctx, const char *name,
777                             int namelen, loff_t offset, u64 ino,
778                             unsigned int d_type)
779 {
780         struct listxattr_buf *b =
781                 container_of(ctx, struct listxattr_buf, ctx);
782         size_t size;
783 
784         if (name[0] != '.' ||
785             (namelen != 1 && (name[1] != '.' || namelen != 2))) {
786                 const struct xattr_handler *handler;
787 
788                 handler = find_xattr_handler_prefix(b->dentry->d_sb->s_xattr,
789                                                     name);
790                 if (!handler /* Unsupported xattr name */ ||
791                     (handler->list && !handler->list(b->dentry)))
792                         return 0;
793                 size = namelen + 1;
794                 if (b->buf) {
795                         if (size > b->size)
796                                 return -ERANGE;
797                         memcpy(b->buf + b->pos, name, namelen);
798                         b->buf[b->pos + namelen] = 0;
799                 }
800                 b->pos += size;
801         }
802         return 0;
803 }
804 
805 /*
806  * Inode operation listxattr()
807  *
808  * We totally ignore the generic listxattr here because it would be stupid
809  * not to. Since the xattrs are organized in a directory, we can just
810  * readdir to find them.
811  */
812 ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
813 {
814         struct dentry *dir;
815         int err = 0;
816         struct listxattr_buf buf = {
817                 .ctx.actor = listxattr_filler,
818                 .dentry = dentry,
819                 .buf = buffer,
820                 .size = buffer ? size : 0,
821         };
822 
823         if (d_really_is_negative(dentry))
824                 return -EINVAL;
825 
826         if (!dentry->d_sb->s_xattr ||
827             get_inode_sd_version(d_inode(dentry)) == STAT_DATA_V1)
828                 return -EOPNOTSUPP;
829 
830         dir = open_xa_dir(d_inode(dentry), XATTR_REPLACE);
831         if (IS_ERR(dir)) {
832                 err = PTR_ERR(dir);
833                 if (err == -ENODATA)
834                         err = 0;  /* Not an error if there aren't any xattrs */
835                 goto out;
836         }
837 
838         inode_lock_nested(d_inode(dir), I_MUTEX_XATTR);
839         err = reiserfs_readdir_inode(d_inode(dir), &buf.ctx);
840         inode_unlock(d_inode(dir));
841 
842         if (!err)
843                 err = buf.pos;
844 
845         dput(dir);
846 out:
847         return err;
848 }
849 
850 static int create_privroot(struct dentry *dentry)
851 {
852         int err;
853         struct inode *inode = d_inode(dentry->d_parent);
854 
855         WARN_ON_ONCE(!inode_is_locked(inode));
856 
857         err = xattr_mkdir(inode, dentry, 0700);
858         if (err || d_really_is_negative(dentry)) {
859                 reiserfs_warning(dentry->d_sb, "jdm-20006",
860                                  "xattrs/ACLs enabled and couldn't "
861                                  "find/create .reiserfs_priv. "
862                                  "Failing mount.");
863                 return -EOPNOTSUPP;
864         }
865 
866         d_inode(dentry)->i_flags |= S_PRIVATE;
867         reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
868                       "storage.\n", PRIVROOT_NAME);
869 
870         return 0;
871 }
872 
873 #else
874 int __init reiserfs_xattr_register_handlers(void) { return 0; }
875 void reiserfs_xattr_unregister_handlers(void) {}
876 static int create_privroot(struct dentry *dentry) { return 0; }
877 #endif
878 
879 /* Actual operations that are exported to VFS-land */
880 static const struct xattr_handler *reiserfs_xattr_handlers[] = {
881 #ifdef CONFIG_REISERFS_FS_XATTR
882         &reiserfs_xattr_user_handler,
883         &reiserfs_xattr_trusted_handler,
884 #endif
885 #ifdef CONFIG_REISERFS_FS_SECURITY
886         &reiserfs_xattr_security_handler,
887 #endif
888 #ifdef CONFIG_REISERFS_FS_POSIX_ACL
889         &posix_acl_access_xattr_handler,
890         &posix_acl_default_xattr_handler,
891 #endif
892         NULL
893 };
894 
895 static int xattr_mount_check(struct super_block *s)
896 {
897         /*
898          * We need generation numbers to ensure that the oid mapping is correct
899          * v3.5 filesystems don't have them.
900          */
901         if (old_format_only(s)) {
902                 if (reiserfs_xattrs_optional(s)) {
903                         /*
904                          * Old format filesystem, but optional xattrs have
905                          * been enabled. Error out.
906                          */
907                         reiserfs_warning(s, "jdm-2005",
908                                          "xattrs/ACLs not supported "
909                                          "on pre-v3.6 format filesystems. "
910                                          "Failing mount.");
911                         return -EOPNOTSUPP;
912                 }
913         }
914 
915         return 0;
916 }
917 
918 int reiserfs_permission(struct inode *inode, int mask)
919 {
920         /*
921          * We don't do permission checks on the internal objects.
922          * Permissions are determined by the "owning" object.
923          */
924         if (IS_PRIVATE(inode))
925                 return 0;
926 
927         return generic_permission(inode, mask);
928 }
929 
930 static int xattr_hide_revalidate(struct dentry *dentry, unsigned int flags)
931 {
932         return -EPERM;
933 }
934 
935 static const struct dentry_operations xattr_lookup_poison_ops = {
936         .d_revalidate = xattr_hide_revalidate,
937 };
938 
939 int reiserfs_lookup_privroot(struct super_block *s)
940 {
941         struct dentry *dentry;
942         int err = 0;
943 
944         /* If we don't have the privroot located yet - go find it */
945         inode_lock(d_inode(s->s_root));
946         dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
947                                 strlen(PRIVROOT_NAME));
948         if (!IS_ERR(dentry)) {
949                 REISERFS_SB(s)->priv_root = dentry;
950                 d_set_d_op(dentry, &xattr_lookup_poison_ops);
951                 if (d_really_is_positive(dentry))
952                         d_inode(dentry)->i_flags |= S_PRIVATE;
953         } else
954                 err = PTR_ERR(dentry);
955         inode_unlock(d_inode(s->s_root));
956 
957         return err;
958 }
959 
960 /*
961  * We need to take a copy of the mount flags since things like
962  * SB_RDONLY don't get set until *after* we're called.
963  * mount_flags != mount_options
964  */
965 int reiserfs_xattr_init(struct super_block *s, int mount_flags)
966 {
967         int err = 0;
968         struct dentry *privroot = REISERFS_SB(s)->priv_root;
969 
970         err = xattr_mount_check(s);
971         if (err)
972                 goto error;
973 
974         if (d_really_is_negative(privroot) && !(mount_flags & SB_RDONLY)) {
975                 inode_lock(d_inode(s->s_root));
976                 err = create_privroot(REISERFS_SB(s)->priv_root);
977                 inode_unlock(d_inode(s->s_root));
978         }
979 
980         if (d_really_is_positive(privroot)) {
981                 s->s_xattr = reiserfs_xattr_handlers;
982                 inode_lock(d_inode(privroot));
983                 if (!REISERFS_SB(s)->xattr_root) {
984                         struct dentry *dentry;
985 
986                         dentry = lookup_one_len(XAROOT_NAME, privroot,
987                                                 strlen(XAROOT_NAME));
988                         if (!IS_ERR(dentry))
989                                 REISERFS_SB(s)->xattr_root = dentry;
990                         else
991                                 err = PTR_ERR(dentry);
992                 }
993                 inode_unlock(d_inode(privroot));
994         }
995 
996 error:
997         if (err) {
998                 clear_bit(REISERFS_XATTRS_USER, &REISERFS_SB(s)->s_mount_opt);
999                 clear_bit(REISERFS_POSIXACL, &REISERFS_SB(s)->s_mount_opt);
1000         }
1001 
1002         /* The super_block SB_POSIXACL must mirror the (no)acl mount option. */
1003         if (reiserfs_posixacl(s))
1004                 s->s_flags |= SB_POSIXACL;
1005         else
1006                 s->s_flags &= ~SB_POSIXACL;
1007 
1008         return err;
1009 }
1010 

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