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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         int err;
189         struct dentry *dentries[8];
190 };
191 
192 static int
193 fill_with_dentries(struct dir_context *ctx, const char *name, int namelen,
194                    loff_t offset, u64 ino, unsigned int d_type)
195 {
196         struct reiserfs_dentry_buf *dbuf =
197                 container_of(ctx, struct reiserfs_dentry_buf, ctx);
198         struct dentry *dentry;
199 
200         WARN_ON_ONCE(!inode_is_locked(d_inode(dbuf->xadir)));
201 
202         if (dbuf->count == ARRAY_SIZE(dbuf->dentries))
203                 return -ENOSPC;
204 
205         if (name[0] == '.' && (namelen < 2 ||
206                                (namelen == 2 && name[1] == '.')))
207                 return 0;
208 
209         dentry = lookup_one_len(name, dbuf->xadir, namelen);
210         if (IS_ERR(dentry)) {
211                 dbuf->err = PTR_ERR(dentry);
212                 return PTR_ERR(dentry);
213         } else if (d_really_is_negative(dentry)) {
214                 /* A directory entry exists, but no file? */
215                 reiserfs_error(dentry->d_sb, "xattr-20003",
216                                "Corrupted directory: xattr %pd listed but "
217                                "not found for file %pd.\n",
218                                dentry, dbuf->xadir);
219                 dput(dentry);
220                 dbuf->err = -EIO;
221                 return -EIO;
222         }
223 
224         dbuf->dentries[dbuf->count++] = dentry;
225         return 0;
226 }
227 
228 static void
229 cleanup_dentry_buf(struct reiserfs_dentry_buf *buf)
230 {
231         int i;
232 
233         for (i = 0; i < buf->count; i++)
234                 if (buf->dentries[i])
235                         dput(buf->dentries[i]);
236 }
237 
238 static int reiserfs_for_each_xattr(struct inode *inode,
239                                    int (*action)(struct dentry *, void *),
240                                    void *data)
241 {
242         struct dentry *dir;
243         int i, err = 0;
244         struct reiserfs_dentry_buf buf = {
245                 .ctx.actor = fill_with_dentries,
246         };
247 
248         /* Skip out, an xattr has no xattrs associated with it */
249         if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1)
250                 return 0;
251 
252         dir = open_xa_dir(inode, XATTR_REPLACE);
253         if (IS_ERR(dir)) {
254                 err = PTR_ERR(dir);
255                 goto out;
256         } else if (d_really_is_negative(dir)) {
257                 err = 0;
258                 goto out_dir;
259         }
260 
261         inode_lock_nested(d_inode(dir), I_MUTEX_XATTR);
262 
263         buf.xadir = dir;
264         while (1) {
265                 err = reiserfs_readdir_inode(d_inode(dir), &buf.ctx);
266                 if (err)
267                         break;
268                 if (buf.err) {
269                         err = buf.err;
270                         break;
271                 }
272                 if (!buf.count)
273                         break;
274                 for (i = 0; !err && i < buf.count && buf.dentries[i]; i++) {
275                         struct dentry *dentry = buf.dentries[i];
276 
277                         if (!d_is_dir(dentry))
278                                 err = action(dentry, data);
279 
280                         dput(dentry);
281                         buf.dentries[i] = NULL;
282                 }
283                 if (err)
284                         break;
285                 buf.count = 0;
286         }
287         inode_unlock(d_inode(dir));
288 
289         cleanup_dentry_buf(&buf);
290 
291         if (!err) {
292                 /*
293                  * We start a transaction here to avoid a ABBA situation
294                  * between the xattr root's i_mutex and the journal lock.
295                  * This doesn't incur much additional overhead since the
296                  * new transaction will just nest inside the
297                  * outer transaction.
298                  */
299                 int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 +
300                              4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb);
301                 struct reiserfs_transaction_handle th;
302 
303                 reiserfs_write_lock(inode->i_sb);
304                 err = journal_begin(&th, inode->i_sb, blocks);
305                 reiserfs_write_unlock(inode->i_sb);
306                 if (!err) {
307                         int jerror;
308 
309                         inode_lock_nested(d_inode(dir->d_parent),
310                                           I_MUTEX_XATTR);
311                         err = action(dir, data);
312                         reiserfs_write_lock(inode->i_sb);
313                         jerror = journal_end(&th);
314                         reiserfs_write_unlock(inode->i_sb);
315                         inode_unlock(d_inode(dir->d_parent));
316                         err = jerror ?: err;
317                 }
318         }
319 out_dir:
320         dput(dir);
321 out:
322         /* -ENODATA isn't an error */
323         if (err == -ENODATA)
324                 err = 0;
325         return err;
326 }
327 
328 static int delete_one_xattr(struct dentry *dentry, void *data)
329 {
330         struct inode *dir = d_inode(dentry->d_parent);
331 
332         /* This is the xattr dir, handle specially. */
333         if (d_is_dir(dentry))
334                 return xattr_rmdir(dir, dentry);
335 
336         return xattr_unlink(dir, dentry);
337 }
338 
339 static int chown_one_xattr(struct dentry *dentry, void *data)
340 {
341         struct iattr *attrs = data;
342         int ia_valid = attrs->ia_valid;
343         int err;
344 
345         /*
346          * We only want the ownership bits. Otherwise, we'll do
347          * things like change a directory to a regular file if
348          * ATTR_MODE is set.
349          */
350         attrs->ia_valid &= (ATTR_UID|ATTR_GID);
351         err = reiserfs_setattr(dentry, attrs);
352         attrs->ia_valid = ia_valid;
353 
354         return err;
355 }
356 
357 /* No i_mutex, but the inode is unconnected. */
358 int reiserfs_delete_xattrs(struct inode *inode)
359 {
360         int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL);
361 
362         if (err)
363                 reiserfs_warning(inode->i_sb, "jdm-20004",
364                                  "Couldn't delete all xattrs (%d)\n", err);
365         return err;
366 }
367 
368 /* inode->i_mutex: down */
369 int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
370 {
371         int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs);
372 
373         if (err)
374                 reiserfs_warning(inode->i_sb, "jdm-20007",
375                                  "Couldn't chown all xattrs (%d)\n", err);
376         return err;
377 }
378 
379 #ifdef CONFIG_REISERFS_FS_XATTR
380 /*
381  * Returns a dentry corresponding to a specific extended attribute file
382  * for the inode. If flags allow, the file is created. Otherwise, a
383  * valid or negative dentry, or an error is returned.
384  */
385 static struct dentry *xattr_lookup(struct inode *inode, const char *name,
386                                     int flags)
387 {
388         struct dentry *xadir, *xafile;
389         int err = 0;
390 
391         xadir = open_xa_dir(inode, flags);
392         if (IS_ERR(xadir))
393                 return ERR_CAST(xadir);
394 
395         inode_lock_nested(d_inode(xadir), I_MUTEX_XATTR);
396         xafile = lookup_one_len(name, xadir, strlen(name));
397         if (IS_ERR(xafile)) {
398                 err = PTR_ERR(xafile);
399                 goto out;
400         }
401 
402         if (d_really_is_positive(xafile) && (flags & XATTR_CREATE))
403                 err = -EEXIST;
404 
405         if (d_really_is_negative(xafile)) {
406                 err = -ENODATA;
407                 if (xattr_may_create(flags))
408                         err = xattr_create(d_inode(xadir), xafile,
409                                               0700|S_IFREG);
410         }
411 
412         if (err)
413                 dput(xafile);
414 out:
415         inode_unlock(d_inode(xadir));
416         dput(xadir);
417         if (err)
418                 return ERR_PTR(err);
419         return xafile;
420 }
421 
422 /* Internal operations on file data */
423 static inline void reiserfs_put_page(struct page *page)
424 {
425         kunmap(page);
426         put_page(page);
427 }
428 
429 static struct page *reiserfs_get_page(struct inode *dir, size_t n)
430 {
431         struct address_space *mapping = dir->i_mapping;
432         struct page *page;
433         /*
434          * We can deadlock if we try to free dentries,
435          * and an unlink/rmdir has just occurred - GFP_NOFS avoids this
436          */
437         mapping_set_gfp_mask(mapping, GFP_NOFS);
438         page = read_mapping_page(mapping, n >> PAGE_SHIFT, NULL);
439         if (!IS_ERR(page)) {
440                 kmap(page);
441                 if (PageError(page))
442                         goto fail;
443         }
444         return page;
445 
446 fail:
447         reiserfs_put_page(page);
448         return ERR_PTR(-EIO);
449 }
450 
451 static inline __u32 xattr_hash(const char *msg, int len)
452 {
453         return csum_partial(msg, len, 0);
454 }
455 
456 int reiserfs_commit_write(struct file *f, struct page *page,
457                           unsigned from, unsigned to);
458 
459 static void update_ctime(struct inode *inode)
460 {
461         struct timespec64 now = current_time(inode);
462 
463         if (inode_unhashed(inode) || !inode->i_nlink ||
464             timespec64_equal(&inode->i_ctime, &now))
465                 return;
466 
467         inode->i_ctime = current_time(inode);
468         mark_inode_dirty(inode);
469 }
470 
471 static int lookup_and_delete_xattr(struct inode *inode, const char *name)
472 {
473         int err = 0;
474         struct dentry *dentry, *xadir;
475 
476         xadir = open_xa_dir(inode, XATTR_REPLACE);
477         if (IS_ERR(xadir))
478                 return PTR_ERR(xadir);
479 
480         inode_lock_nested(d_inode(xadir), I_MUTEX_XATTR);
481         dentry = lookup_one_len(name, xadir, strlen(name));
482         if (IS_ERR(dentry)) {
483                 err = PTR_ERR(dentry);
484                 goto out_dput;
485         }
486 
487         if (d_really_is_positive(dentry)) {
488                 err = xattr_unlink(d_inode(xadir), dentry);
489                 update_ctime(inode);
490         }
491 
492         dput(dentry);
493 out_dput:
494         inode_unlock(d_inode(xadir));
495         dput(xadir);
496         return err;
497 }
498 
499 
500 /* Generic extended attribute operations that can be used by xa plugins */
501 
502 /*
503  * inode->i_mutex: down
504  */
505 int
506 reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
507                           struct inode *inode, const char *name,
508                           const void *buffer, size_t buffer_size, int flags)
509 {
510         int err = 0;
511         struct dentry *dentry;
512         struct page *page;
513         char *data;
514         size_t file_pos = 0;
515         size_t buffer_pos = 0;
516         size_t new_size;
517         __u32 xahash = 0;
518 
519         if (get_inode_sd_version(inode) == STAT_DATA_V1)
520                 return -EOPNOTSUPP;
521 
522         if (!buffer) {
523                 err = lookup_and_delete_xattr(inode, name);
524                 return err;
525         }
526 
527         dentry = xattr_lookup(inode, name, flags);
528         if (IS_ERR(dentry))
529                 return PTR_ERR(dentry);
530 
531         down_write(&REISERFS_I(inode)->i_xattr_sem);
532 
533         xahash = xattr_hash(buffer, buffer_size);
534         while (buffer_pos < buffer_size || buffer_pos == 0) {
535                 size_t chunk;
536                 size_t skip = 0;
537                 size_t page_offset = (file_pos & (PAGE_SIZE - 1));
538 
539                 if (buffer_size - buffer_pos > PAGE_SIZE)
540                         chunk = PAGE_SIZE;
541                 else
542                         chunk = buffer_size - buffer_pos;
543 
544                 page = reiserfs_get_page(d_inode(dentry), file_pos);
545                 if (IS_ERR(page)) {
546                         err = PTR_ERR(page);
547                         goto out_unlock;
548                 }
549 
550                 lock_page(page);
551                 data = page_address(page);
552 
553                 if (file_pos == 0) {
554                         struct reiserfs_xattr_header *rxh;
555 
556                         skip = file_pos = sizeof(struct reiserfs_xattr_header);
557                         if (chunk + skip > PAGE_SIZE)
558                                 chunk = PAGE_SIZE - skip;
559                         rxh = (struct reiserfs_xattr_header *)data;
560                         rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
561                         rxh->h_hash = cpu_to_le32(xahash);
562                 }
563 
564                 reiserfs_write_lock(inode->i_sb);
565                 err = __reiserfs_write_begin(page, page_offset, chunk + skip);
566                 if (!err) {
567                         if (buffer)
568                                 memcpy(data + skip, buffer + buffer_pos, chunk);
569                         err = reiserfs_commit_write(NULL, page, page_offset,
570                                                     page_offset + chunk +
571                                                     skip);
572                 }
573                 reiserfs_write_unlock(inode->i_sb);
574                 unlock_page(page);
575                 reiserfs_put_page(page);
576                 buffer_pos += chunk;
577                 file_pos += chunk;
578                 skip = 0;
579                 if (err || buffer_size == 0 || !buffer)
580                         break;
581         }
582 
583         new_size = buffer_size + sizeof(struct reiserfs_xattr_header);
584         if (!err && new_size < i_size_read(d_inode(dentry))) {
585                 struct iattr newattrs = {
586                         .ia_ctime = current_time(inode),
587                         .ia_size = new_size,
588                         .ia_valid = ATTR_SIZE | ATTR_CTIME,
589                 };
590 
591                 inode_lock_nested(d_inode(dentry), I_MUTEX_XATTR);
592                 inode_dio_wait(d_inode(dentry));
593 
594                 err = reiserfs_setattr(dentry, &newattrs);
595                 inode_unlock(d_inode(dentry));
596         } else
597                 update_ctime(inode);
598 out_unlock:
599         up_write(&REISERFS_I(inode)->i_xattr_sem);
600         dput(dentry);
601         return err;
602 }
603 
604 /* We need to start a transaction to maintain lock ordering */
605 int reiserfs_xattr_set(struct inode *inode, const char *name,
606                        const void *buffer, size_t buffer_size, int flags)
607 {
608 
609         struct reiserfs_transaction_handle th;
610         int error, error2;
611         size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size);
612 
613         if (!(flags & XATTR_REPLACE))
614                 jbegin_count += reiserfs_xattr_jcreate_nblocks(inode);
615 
616         reiserfs_write_lock(inode->i_sb);
617         error = journal_begin(&th, inode->i_sb, jbegin_count);
618         reiserfs_write_unlock(inode->i_sb);
619         if (error) {
620                 return error;
621         }
622 
623         error = reiserfs_xattr_set_handle(&th, inode, name,
624                                           buffer, buffer_size, flags);
625 
626         reiserfs_write_lock(inode->i_sb);
627         error2 = journal_end(&th);
628         reiserfs_write_unlock(inode->i_sb);
629         if (error == 0)
630                 error = error2;
631 
632         return error;
633 }
634 
635 /*
636  * inode->i_mutex: down
637  */
638 int
639 reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer,
640                    size_t buffer_size)
641 {
642         ssize_t err = 0;
643         struct dentry *dentry;
644         size_t isize;
645         size_t file_pos = 0;
646         size_t buffer_pos = 0;
647         struct page *page;
648         __u32 hash = 0;
649 
650         if (name == NULL)
651                 return -EINVAL;
652 
653         /*
654          * We can't have xattrs attached to v1 items since they don't have
655          * generation numbers
656          */
657         if (get_inode_sd_version(inode) == STAT_DATA_V1)
658                 return -EOPNOTSUPP;
659 
660         dentry = xattr_lookup(inode, name, XATTR_REPLACE);
661         if (IS_ERR(dentry)) {
662                 err = PTR_ERR(dentry);
663                 goto out;
664         }
665 
666         down_read(&REISERFS_I(inode)->i_xattr_sem);
667 
668         isize = i_size_read(d_inode(dentry));
669 
670         /* Just return the size needed */
671         if (buffer == NULL) {
672                 err = isize - sizeof(struct reiserfs_xattr_header);
673                 goto out_unlock;
674         }
675 
676         if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
677                 err = -ERANGE;
678                 goto out_unlock;
679         }
680 
681         while (file_pos < isize) {
682                 size_t chunk;
683                 char *data;
684                 size_t skip = 0;
685 
686                 if (isize - file_pos > PAGE_SIZE)
687                         chunk = PAGE_SIZE;
688                 else
689                         chunk = isize - file_pos;
690 
691                 page = reiserfs_get_page(d_inode(dentry), file_pos);
692                 if (IS_ERR(page)) {
693                         err = PTR_ERR(page);
694                         goto out_unlock;
695                 }
696 
697                 lock_page(page);
698                 data = page_address(page);
699                 if (file_pos == 0) {
700                         struct reiserfs_xattr_header *rxh =
701                             (struct reiserfs_xattr_header *)data;
702                         skip = file_pos = sizeof(struct reiserfs_xattr_header);
703                         chunk -= skip;
704                         /* Magic doesn't match up.. */
705                         if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
706                                 unlock_page(page);
707                                 reiserfs_put_page(page);
708                                 reiserfs_warning(inode->i_sb, "jdm-20001",
709                                                  "Invalid magic for xattr (%s) "
710                                                  "associated with %k", name,
711                                                  INODE_PKEY(inode));
712                                 err = -EIO;
713                                 goto out_unlock;
714                         }
715                         hash = le32_to_cpu(rxh->h_hash);
716                 }
717                 memcpy(buffer + buffer_pos, data + skip, chunk);
718                 unlock_page(page);
719                 reiserfs_put_page(page);
720                 file_pos += chunk;
721                 buffer_pos += chunk;
722                 skip = 0;
723         }
724         err = isize - sizeof(struct reiserfs_xattr_header);
725 
726         if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
727             hash) {
728                 reiserfs_warning(inode->i_sb, "jdm-20002",
729                                  "Invalid hash for xattr (%s) associated "
730                                  "with %k", name, INODE_PKEY(inode));
731                 err = -EIO;
732         }
733 
734 out_unlock:
735         up_read(&REISERFS_I(inode)->i_xattr_sem);
736         dput(dentry);
737 
738 out:
739         return err;
740 }
741 
742 /*
743  * In order to implement different sets of xattr operations for each xattr
744  * prefix with the generic xattr API, a filesystem should create a
745  * null-terminated array of struct xattr_handler (one for each prefix) and
746  * hang a pointer to it off of the s_xattr field of the superblock.
747  *
748  * The generic_fooxattr() functions will use this list to dispatch xattr
749  * operations to the correct xattr_handler.
750  */
751 #define for_each_xattr_handler(handlers, handler)               \
752                 for ((handler) = *(handlers)++;                 \
753                         (handler) != NULL;                      \
754                         (handler) = *(handlers)++)
755 
756 /* This is the implementation for the xattr plugin infrastructure */
757 static inline const struct xattr_handler *
758 find_xattr_handler_prefix(const struct xattr_handler **handlers,
759                            const char *name)
760 {
761         const struct xattr_handler *xah;
762 
763         if (!handlers)
764                 return NULL;
765 
766         for_each_xattr_handler(handlers, xah) {
767                 const char *prefix = xattr_prefix(xah);
768                 if (strncmp(prefix, name, strlen(prefix)) == 0)
769                         break;
770         }
771 
772         return xah;
773 }
774 
775 struct listxattr_buf {
776         struct dir_context ctx;
777         size_t size;
778         size_t pos;
779         char *buf;
780         struct dentry *dentry;
781 };
782 
783 static int listxattr_filler(struct dir_context *ctx, const char *name,
784                             int namelen, loff_t offset, u64 ino,
785                             unsigned int d_type)
786 {
787         struct listxattr_buf *b =
788                 container_of(ctx, struct listxattr_buf, ctx);
789         size_t size;
790 
791         if (name[0] != '.' ||
792             (namelen != 1 && (name[1] != '.' || namelen != 2))) {
793                 const struct xattr_handler *handler;
794 
795                 handler = find_xattr_handler_prefix(b->dentry->d_sb->s_xattr,
796                                                     name);
797                 if (!handler /* Unsupported xattr name */ ||
798                     (handler->list && !handler->list(b->dentry)))
799                         return 0;
800                 size = namelen + 1;
801                 if (b->buf) {
802                         if (b->pos + size > b->size) {
803                                 b->pos = -ERANGE;
804                                 return -ERANGE;
805                         }
806                         memcpy(b->buf + b->pos, name, namelen);
807                         b->buf[b->pos + namelen] = 0;
808                 }
809                 b->pos += size;
810         }
811         return 0;
812 }
813 
814 /*
815  * Inode operation listxattr()
816  *
817  * We totally ignore the generic listxattr here because it would be stupid
818  * not to. Since the xattrs are organized in a directory, we can just
819  * readdir to find them.
820  */
821 ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
822 {
823         struct dentry *dir;
824         int err = 0;
825         struct listxattr_buf buf = {
826                 .ctx.actor = listxattr_filler,
827                 .dentry = dentry,
828                 .buf = buffer,
829                 .size = buffer ? size : 0,
830         };
831 
832         if (d_really_is_negative(dentry))
833                 return -EINVAL;
834 
835         if (!dentry->d_sb->s_xattr ||
836             get_inode_sd_version(d_inode(dentry)) == STAT_DATA_V1)
837                 return -EOPNOTSUPP;
838 
839         dir = open_xa_dir(d_inode(dentry), XATTR_REPLACE);
840         if (IS_ERR(dir)) {
841                 err = PTR_ERR(dir);
842                 if (err == -ENODATA)
843                         err = 0;  /* Not an error if there aren't any xattrs */
844                 goto out;
845         }
846 
847         inode_lock_nested(d_inode(dir), I_MUTEX_XATTR);
848         err = reiserfs_readdir_inode(d_inode(dir), &buf.ctx);
849         inode_unlock(d_inode(dir));
850 
851         if (!err)
852                 err = buf.pos;
853 
854         dput(dir);
855 out:
856         return err;
857 }
858 
859 static int create_privroot(struct dentry *dentry)
860 {
861         int err;
862         struct inode *inode = d_inode(dentry->d_parent);
863 
864         WARN_ON_ONCE(!inode_is_locked(inode));
865 
866         err = xattr_mkdir(inode, dentry, 0700);
867         if (err || d_really_is_negative(dentry)) {
868                 reiserfs_warning(dentry->d_sb, "jdm-20006",
869                                  "xattrs/ACLs enabled and couldn't "
870                                  "find/create .reiserfs_priv. "
871                                  "Failing mount.");
872                 return -EOPNOTSUPP;
873         }
874 
875         d_inode(dentry)->i_flags |= S_PRIVATE;
876         reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
877                       "storage.\n", PRIVROOT_NAME);
878 
879         return 0;
880 }
881 
882 #else
883 int __init reiserfs_xattr_register_handlers(void) { return 0; }
884 void reiserfs_xattr_unregister_handlers(void) {}
885 static int create_privroot(struct dentry *dentry) { return 0; }
886 #endif
887 
888 /* Actual operations that are exported to VFS-land */
889 static const struct xattr_handler *reiserfs_xattr_handlers[] = {
890 #ifdef CONFIG_REISERFS_FS_XATTR
891         &reiserfs_xattr_user_handler,
892         &reiserfs_xattr_trusted_handler,
893 #endif
894 #ifdef CONFIG_REISERFS_FS_SECURITY
895         &reiserfs_xattr_security_handler,
896 #endif
897 #ifdef CONFIG_REISERFS_FS_POSIX_ACL
898         &posix_acl_access_xattr_handler,
899         &posix_acl_default_xattr_handler,
900 #endif
901         NULL
902 };
903 
904 static int xattr_mount_check(struct super_block *s)
905 {
906         /*
907          * We need generation numbers to ensure that the oid mapping is correct
908          * v3.5 filesystems don't have them.
909          */
910         if (old_format_only(s)) {
911                 if (reiserfs_xattrs_optional(s)) {
912                         /*
913                          * Old format filesystem, but optional xattrs have
914                          * been enabled. Error out.
915                          */
916                         reiserfs_warning(s, "jdm-2005",
917                                          "xattrs/ACLs not supported "
918                                          "on pre-v3.6 format filesystems. "
919                                          "Failing mount.");
920                         return -EOPNOTSUPP;
921                 }
922         }
923 
924         return 0;
925 }
926 
927 int reiserfs_permission(struct inode *inode, int mask)
928 {
929         /*
930          * We don't do permission checks on the internal objects.
931          * Permissions are determined by the "owning" object.
932          */
933         if (IS_PRIVATE(inode))
934                 return 0;
935 
936         return generic_permission(inode, mask);
937 }
938 
939 static int xattr_hide_revalidate(struct dentry *dentry, unsigned int flags)
940 {
941         return -EPERM;
942 }
943 
944 static const struct dentry_operations xattr_lookup_poison_ops = {
945         .d_revalidate = xattr_hide_revalidate,
946 };
947 
948 int reiserfs_lookup_privroot(struct super_block *s)
949 {
950         struct dentry *dentry;
951         int err = 0;
952 
953         /* If we don't have the privroot located yet - go find it */
954         inode_lock(d_inode(s->s_root));
955         dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
956                                 strlen(PRIVROOT_NAME));
957         if (!IS_ERR(dentry)) {
958                 REISERFS_SB(s)->priv_root = dentry;
959                 d_set_d_op(dentry, &xattr_lookup_poison_ops);
960                 if (d_really_is_positive(dentry))
961                         d_inode(dentry)->i_flags |= S_PRIVATE;
962         } else
963                 err = PTR_ERR(dentry);
964         inode_unlock(d_inode(s->s_root));
965 
966         return err;
967 }
968 
969 /*
970  * We need to take a copy of the mount flags since things like
971  * SB_RDONLY don't get set until *after* we're called.
972  * mount_flags != mount_options
973  */
974 int reiserfs_xattr_init(struct super_block *s, int mount_flags)
975 {
976         int err = 0;
977         struct dentry *privroot = REISERFS_SB(s)->priv_root;
978 
979         err = xattr_mount_check(s);
980         if (err)
981                 goto error;
982 
983         if (d_really_is_negative(privroot) && !(mount_flags & SB_RDONLY)) {
984                 inode_lock(d_inode(s->s_root));
985                 err = create_privroot(REISERFS_SB(s)->priv_root);
986                 inode_unlock(d_inode(s->s_root));
987         }
988 
989         if (d_really_is_positive(privroot)) {
990                 s->s_xattr = reiserfs_xattr_handlers;
991                 inode_lock(d_inode(privroot));
992                 if (!REISERFS_SB(s)->xattr_root) {
993                         struct dentry *dentry;
994 
995                         dentry = lookup_one_len(XAROOT_NAME, privroot,
996                                                 strlen(XAROOT_NAME));
997                         if (!IS_ERR(dentry))
998                                 REISERFS_SB(s)->xattr_root = dentry;
999                         else
1000                                 err = PTR_ERR(dentry);
1001                 }
1002                 inode_unlock(d_inode(privroot));
1003         }
1004 
1005 error:
1006         if (err) {
1007                 clear_bit(REISERFS_XATTRS_USER, &REISERFS_SB(s)->s_mount_opt);
1008                 clear_bit(REISERFS_POSIXACL, &REISERFS_SB(s)->s_mount_opt);
1009         }
1010 
1011         /* The super_block SB_POSIXACL must mirror the (no)acl mount option. */
1012         if (reiserfs_posixacl(s))
1013                 s->s_flags |= SB_POSIXACL;
1014         else
1015                 s->s_flags &= ~SB_POSIXACL;
1016 
1017         return err;
1018 }
1019 

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