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
xattr_create(struct inode * dir,struct dentry * dentry,int mode)62 static 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 
xattr_mkdir(struct inode * dir,struct dentry * dentry,umode_t mode)69 static 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. */
xattr_unlink(struct inode * dir,struct dentry * dentry)79 static 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 
xattr_rmdir(struct inode * dir,struct dentry * dentry)94 static 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 
open_xa_root(struct super_block * sb,int flags)113 static 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 
open_xa_dir(const struct inode * inode,int flags)139 static 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. */
173 struct reiserfs_dentry_buf {
174 	struct dentry *xadir;
175 	int count;
176 	struct dentry *dentries[8];
177 };
178 
179 static int
fill_with_dentries(void * buf,const char * name,int namelen,loff_t offset,u64 ino,unsigned int d_type)180 fill_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] == '.' && (namelen < 2 ||
191 			       (namelen == 2 && name[1] == '.')))
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 
211 static void
cleanup_dentry_buf(struct reiserfs_dentry_buf * buf)212 cleanup_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 
reiserfs_for_each_xattr(struct inode * inode,int (* action)(struct dentry *,void *),void * data)220 static 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 	}
298 out_dir:
299 	dput(dir);
300 out:
301 	/* -ENODATA isn't an error */
302 	if (err == -ENODATA)
303 		err = 0;
304 	return err;
305 }
306 
delete_one_xattr(struct dentry * dentry,void * data)307 static 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 
chown_one_xattr(struct dentry * dentry,void * data)318 static 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. */
reiserfs_delete_xattrs(struct inode * inode)325 int 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 */
reiserfs_chown_xattrs(struct inode * inode,struct iattr * attrs)335 int 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. */
xattr_lookup(struct inode * inode,const char * name,int flags)348 static 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);
377 out:
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 */
reiserfs_put_page(struct page * page)386 static inline void reiserfs_put_page(struct page *page)
387 {
388 	kunmap(page);
389 	page_cache_release(page);
390 }
391 
reiserfs_get_page(struct inode * dir,size_t n)392 static 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 
xattr_hash(const char * msg,int len)412 static inline __u32 xattr_hash(const char *msg, int len)
413 {
414 	return csum_partial(msg, len, 0);
415 }
416 
417 int reiserfs_commit_write(struct file *f, struct page *page,
418 			  unsigned from, unsigned to);
419 
update_ctime(struct inode * inode)420 static 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 
lookup_and_delete_xattr(struct inode * inode,const char * name)431 static 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);
455 out_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  */
467 int
reiserfs_xattr_set_handle(struct reiserfs_transaction_handle * th,struct inode * inode,const char * name,const void * buffer,size_t buffer_size,int flags)468 reiserfs_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);
565 out_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 */
reiserfs_xattr_set(struct inode * inode,const char * name,const void * buffer,size_t buffer_size,int flags)572 int 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  */
604 int
reiserfs_xattr_get(struct inode * inode,const char * name,void * buffer,size_t buffer_size)605 reiserfs_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 
697 out_unlock:
698 	up_read(&REISERFS_I(inode)->i_xattr_sem);
699 	dput(dentry);
700 
701 out:
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 */
720 static inline const struct xattr_handler *
find_xattr_handler_prefix(const struct xattr_handler ** handlers,const char * name)721 find_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  */
741 ssize_t
reiserfs_getxattr(struct dentry * dentry,const char * name,void * buffer,size_t size)742 reiserfs_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  */
760 int
reiserfs_setxattr(struct dentry * dentry,const char * name,const void * value,size_t size,int flags)761 reiserfs_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  */
reiserfs_removexattr(struct dentry * dentry,const char * name)779 int 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 
790 struct listxattr_buf {
791 	size_t size;
792 	size_t pos;
793 	char *buf;
794 	struct dentry *dentry;
795 };
796 
listxattr_filler(void * buf,const char * name,int namelen,loff_t offset,u64 ino,unsigned int d_type)797 static 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  */
reiserfs_listxattr(struct dentry * dentry,char * buffer,size_t size)832 ssize_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);
866 out:
867 	return err;
868 }
869 
create_privroot(struct dentry * dentry)870 static 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
reiserfs_xattr_register_handlers(void)893 int __init reiserfs_xattr_register_handlers(void) { return 0; }
reiserfs_xattr_unregister_handlers(void)894 void reiserfs_xattr_unregister_handlers(void) {}
create_privroot(struct dentry * dentry)895 static int create_privroot(struct dentry *dentry) { return 0; }
896 #endif
897 
898 /* Actual operations that are exported to VFS-land */
899 const 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 
xattr_mount_check(struct super_block * s)914 static 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 
reiserfs_permission(struct inode * inode,int mask)933 int 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 
xattr_hide_revalidate(struct dentry * dentry,struct nameidata * nd)945 static int xattr_hide_revalidate(struct dentry *dentry, struct nameidata *nd)
946 {
947 	return -EPERM;
948 }
949 
950 static const struct dentry_operations xattr_lookup_poison_ops = {
951 	.d_revalidate = xattr_hide_revalidate,
952 };
953 
reiserfs_lookup_privroot(struct super_block * s)954 int 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 */
reiserfs_xattr_init(struct super_block * s,int mount_flags)978 int 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 
1008 error:
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 }
1022