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 <linux/reiserfs_fs.h> 37 #include <linux/capability.h> 38 #include <linux/dcache.h> 39 #include <linux/namei.h> 40 #include <linux/errno.h> 41 #include <linux/fs.h> 42 #include <linux/file.h> 43 #include <linux/pagemap.h> 44 #include <linux/xattr.h> 45 #include <linux/reiserfs_xattr.h> 46 #include <linux/reiserfs_acl.h> 47 #include <asm/uaccess.h> 48 #include <net/checksum.h> 49 #include <linux/stat.h> 50 #include <linux/quotaops.h> 51 52 #define PRIVROOT_NAME ".reiserfs_priv" 53 #define XAROOT_NAME "xattrs" 54 55 56 /* Helpers for inode ops. We do this so that we don't have all the VFS 57 * overhead and also for proper i_mutex annotation. 58 * dir->i_mutex must be held for all of them. */ 59 #ifdef CONFIG_REISERFS_FS_XATTR 60 static int xattr_create(struct inode *dir, struct dentry *dentry, int mode) 61 { 62 BUG_ON(!mutex_is_locked(&dir->i_mutex)); 63 vfs_dq_init(dir); 64 return dir->i_op->create(dir, dentry, mode, NULL); 65 } 66 #endif 67 68 static int xattr_mkdir(struct inode *dir, struct dentry *dentry, int mode) 69 { 70 BUG_ON(!mutex_is_locked(&dir->i_mutex)); 71 vfs_dq_init(dir); 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. */ 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 vfs_dq_init(dir); 84 85 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD); 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 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 vfs_dq_init(dir); 99 100 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD); 101 dentry_unhash(dentry); 102 error = dir->i_op->rmdir(dir, dentry); 103 if (!error) 104 dentry->d_inode->i_flags |= S_DEAD; 105 mutex_unlock(&dentry->d_inode->i_mutex); 106 if (!error) 107 d_delete(dentry); 108 dput(dentry); 109 110 return error; 111 } 112 113 #define xattr_may_create(flags) (!flags || flags & XATTR_CREATE) 114 115 static struct dentry *open_xa_root(struct super_block *sb, int flags) 116 { 117 struct dentry *privroot = REISERFS_SB(sb)->priv_root; 118 struct dentry *xaroot; 119 if (!privroot->d_inode) 120 return ERR_PTR(-ENODATA); 121 122 mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR); 123 124 xaroot = dget(REISERFS_SB(sb)->xattr_root); 125 if (!xaroot) 126 xaroot = ERR_PTR(-ENODATA); 127 else if (!xaroot->d_inode) { 128 int err = -ENODATA; 129 if (xattr_may_create(flags)) 130 err = xattr_mkdir(privroot->d_inode, xaroot, 0700); 131 if (err) { 132 dput(xaroot); 133 xaroot = ERR_PTR(err); 134 } 135 } 136 137 mutex_unlock(&privroot->d_inode->i_mutex); 138 return xaroot; 139 } 140 141 static struct dentry *open_xa_dir(const struct inode *inode, int flags) 142 { 143 struct dentry *xaroot, *xadir; 144 char namebuf[17]; 145 146 xaroot = open_xa_root(inode->i_sb, flags); 147 if (IS_ERR(xaroot)) 148 return xaroot; 149 150 snprintf(namebuf, sizeof(namebuf), "%X.%X", 151 le32_to_cpu(INODE_PKEY(inode)->k_objectid), 152 inode->i_generation); 153 154 mutex_lock_nested(&xaroot->d_inode->i_mutex, I_MUTEX_XATTR); 155 156 xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf)); 157 if (!IS_ERR(xadir) && !xadir->d_inode) { 158 int err = -ENODATA; 159 if (xattr_may_create(flags)) 160 err = xattr_mkdir(xaroot->d_inode, xadir, 0700); 161 if (err) { 162 dput(xadir); 163 xadir = ERR_PTR(err); 164 } 165 } 166 167 mutex_unlock(&xaroot->d_inode->i_mutex); 168 dput(xaroot); 169 return xadir; 170 } 171 172 /* The following are side effects of other operations that aren't explicitly 173 * modifying extended attributes. This includes operations such as permissions 174 * or ownership changes, object deletions, etc. */ 175 struct reiserfs_dentry_buf { 176 struct dentry *xadir; 177 int count; 178 struct dentry *dentries[8]; 179 }; 180 181 static int 182 fill_with_dentries(void *buf, const char *name, int namelen, loff_t offset, 183 u64 ino, unsigned int d_type) 184 { 185 struct reiserfs_dentry_buf *dbuf = buf; 186 struct dentry *dentry; 187 WARN_ON_ONCE(!mutex_is_locked(&dbuf->xadir->d_inode->i_mutex)); 188 189 if (dbuf->count == ARRAY_SIZE(dbuf->dentries)) 190 return -ENOSPC; 191 192 if (name[0] == '.' && (name[1] == '\0' || 193 (name[1] == '.' && name[2] == '\0'))) 194 return 0; 195 196 dentry = lookup_one_len(name, dbuf->xadir, namelen); 197 if (IS_ERR(dentry)) { 198 return PTR_ERR(dentry); 199 } else if (!dentry->d_inode) { 200 /* A directory entry exists, but no file? */ 201 reiserfs_error(dentry->d_sb, "xattr-20003", 202 "Corrupted directory: xattr %s listed but " 203 "not found for file %s.\n", 204 dentry->d_name.name, dbuf->xadir->d_name.name); 205 dput(dentry); 206 return -EIO; 207 } 208 209 dbuf->dentries[dbuf->count++] = dentry; 210 return 0; 211 } 212 213 static void 214 cleanup_dentry_buf(struct reiserfs_dentry_buf *buf) 215 { 216 int i; 217 for (i = 0; i < buf->count; i++) 218 if (buf->dentries[i]) 219 dput(buf->dentries[i]); 220 } 221 222 static int reiserfs_for_each_xattr(struct inode *inode, 223 int (*action)(struct dentry *, void *), 224 void *data) 225 { 226 struct dentry *dir; 227 int i, err = 0; 228 loff_t pos = 0; 229 struct reiserfs_dentry_buf buf = { 230 .count = 0, 231 }; 232 233 /* Skip out, an xattr has no xattrs associated with it */ 234 if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1) 235 return 0; 236 237 dir = open_xa_dir(inode, XATTR_REPLACE); 238 if (IS_ERR(dir)) { 239 err = PTR_ERR(dir); 240 goto out; 241 } else if (!dir->d_inode) { 242 err = 0; 243 goto out_dir; 244 } 245 246 reiserfs_mutex_lock_nested_safe(&dir->d_inode->i_mutex, I_MUTEX_XATTR, 247 inode->i_sb); 248 buf.xadir = dir; 249 err = reiserfs_readdir_dentry(dir, &buf, fill_with_dentries, &pos); 250 while ((err == 0 || err == -ENOSPC) && buf.count) { 251 err = 0; 252 253 for (i = 0; i < buf.count && buf.dentries[i]; i++) { 254 int lerr = 0; 255 struct dentry *dentry = buf.dentries[i]; 256 257 if (err == 0 && !S_ISDIR(dentry->d_inode->i_mode)) 258 lerr = action(dentry, data); 259 260 dput(dentry); 261 buf.dentries[i] = NULL; 262 err = lerr ?: err; 263 } 264 buf.count = 0; 265 if (!err) 266 err = reiserfs_readdir_dentry(dir, &buf, 267 fill_with_dentries, &pos); 268 } 269 mutex_unlock(&dir->d_inode->i_mutex); 270 271 /* Clean up after a failed readdir */ 272 cleanup_dentry_buf(&buf); 273 274 if (!err) { 275 /* We start a transaction here to avoid a ABBA situation 276 * between the xattr root's i_mutex and the journal lock. 277 * This doesn't incur much additional overhead since the 278 * new transaction will just nest inside the 279 * outer transaction. */ 280 int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 + 281 4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb); 282 struct reiserfs_transaction_handle th; 283 err = journal_begin(&th, inode->i_sb, blocks); 284 if (!err) { 285 int jerror; 286 mutex_lock_nested(&dir->d_parent->d_inode->i_mutex, 287 I_MUTEX_XATTR); 288 err = action(dir, data); 289 jerror = journal_end(&th, inode->i_sb, blocks); 290 mutex_unlock(&dir->d_parent->d_inode->i_mutex); 291 err = jerror ?: err; 292 } 293 } 294 out_dir: 295 dput(dir); 296 out: 297 /* -ENODATA isn't an error */ 298 if (err == -ENODATA) 299 err = 0; 300 return err; 301 } 302 303 static int delete_one_xattr(struct dentry *dentry, void *data) 304 { 305 struct inode *dir = dentry->d_parent->d_inode; 306 307 /* This is the xattr dir, handle specially. */ 308 if (S_ISDIR(dentry->d_inode->i_mode)) 309 return xattr_rmdir(dir, dentry); 310 311 return xattr_unlink(dir, dentry); 312 } 313 314 static int chown_one_xattr(struct dentry *dentry, void *data) 315 { 316 struct iattr *attrs = data; 317 return reiserfs_setattr(dentry, attrs); 318 } 319 320 /* No i_mutex, but the inode is unconnected. */ 321 int reiserfs_delete_xattrs(struct inode *inode) 322 { 323 int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL); 324 if (err) 325 reiserfs_warning(inode->i_sb, "jdm-20004", 326 "Couldn't delete all xattrs (%d)\n", err); 327 return err; 328 } 329 330 /* inode->i_mutex: down */ 331 int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs) 332 { 333 int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs); 334 if (err) 335 reiserfs_warning(inode->i_sb, "jdm-20007", 336 "Couldn't chown all xattrs (%d)\n", err); 337 return err; 338 } 339 340 #ifdef CONFIG_REISERFS_FS_XATTR 341 /* Returns a dentry corresponding to a specific extended attribute file 342 * for the inode. If flags allow, the file is created. Otherwise, a 343 * valid or negative dentry, or an error is returned. */ 344 static struct dentry *xattr_lookup(struct inode *inode, const char *name, 345 int flags) 346 { 347 struct dentry *xadir, *xafile; 348 int err = 0; 349 350 xadir = open_xa_dir(inode, flags); 351 if (IS_ERR(xadir)) 352 return ERR_CAST(xadir); 353 354 mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR); 355 xafile = lookup_one_len(name, xadir, strlen(name)); 356 if (IS_ERR(xafile)) { 357 err = PTR_ERR(xafile); 358 goto out; 359 } 360 361 if (xafile->d_inode && (flags & XATTR_CREATE)) 362 err = -EEXIST; 363 364 if (!xafile->d_inode) { 365 err = -ENODATA; 366 if (xattr_may_create(flags)) 367 err = xattr_create(xadir->d_inode, xafile, 368 0700|S_IFREG); 369 } 370 371 if (err) 372 dput(xafile); 373 out: 374 mutex_unlock(&xadir->d_inode->i_mutex); 375 dput(xadir); 376 if (err) 377 return ERR_PTR(err); 378 return xafile; 379 } 380 381 /* Internal operations on file data */ 382 static inline void reiserfs_put_page(struct page *page) 383 { 384 kunmap(page); 385 page_cache_release(page); 386 } 387 388 static struct page *reiserfs_get_page(struct inode *dir, size_t n) 389 { 390 struct address_space *mapping = dir->i_mapping; 391 struct page *page; 392 /* We can deadlock if we try to free dentries, 393 and an unlink/rmdir has just occured - GFP_NOFS avoids this */ 394 mapping_set_gfp_mask(mapping, GFP_NOFS); 395 page = read_mapping_page(mapping, n >> PAGE_CACHE_SHIFT, NULL); 396 if (!IS_ERR(page)) { 397 kmap(page); 398 if (PageError(page)) 399 goto fail; 400 } 401 return page; 402 403 fail: 404 reiserfs_put_page(page); 405 return ERR_PTR(-EIO); 406 } 407 408 static inline __u32 xattr_hash(const char *msg, int len) 409 { 410 return csum_partial(msg, len, 0); 411 } 412 413 int reiserfs_commit_write(struct file *f, struct page *page, 414 unsigned from, unsigned to); 415 int reiserfs_prepare_write(struct file *f, struct page *page, 416 unsigned from, unsigned to); 417 418 static void update_ctime(struct inode *inode) 419 { 420 struct timespec now = current_fs_time(inode->i_sb); 421 if (hlist_unhashed(&inode->i_hash) || !inode->i_nlink || 422 timespec_equal(&inode->i_ctime, &now)) 423 return; 424 425 inode->i_ctime = CURRENT_TIME_SEC; 426 mark_inode_dirty(inode); 427 } 428 429 static int lookup_and_delete_xattr(struct inode *inode, const char *name) 430 { 431 int err = 0; 432 struct dentry *dentry, *xadir; 433 434 xadir = open_xa_dir(inode, XATTR_REPLACE); 435 if (IS_ERR(xadir)) 436 return PTR_ERR(xadir); 437 438 mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR); 439 dentry = lookup_one_len(name, xadir, strlen(name)); 440 if (IS_ERR(dentry)) { 441 err = PTR_ERR(dentry); 442 goto out_dput; 443 } 444 445 if (dentry->d_inode) { 446 err = xattr_unlink(xadir->d_inode, dentry); 447 update_ctime(inode); 448 } 449 450 dput(dentry); 451 out_dput: 452 mutex_unlock(&xadir->d_inode->i_mutex); 453 dput(xadir); 454 return err; 455 } 456 457 458 /* Generic extended attribute operations that can be used by xa plugins */ 459 460 /* 461 * inode->i_mutex: down 462 */ 463 int 464 reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th, 465 struct inode *inode, const char *name, 466 const void *buffer, size_t buffer_size, int flags) 467 { 468 int err = 0; 469 struct dentry *dentry; 470 struct page *page; 471 char *data; 472 size_t file_pos = 0; 473 size_t buffer_pos = 0; 474 size_t new_size; 475 __u32 xahash = 0; 476 477 if (get_inode_sd_version(inode) == STAT_DATA_V1) 478 return -EOPNOTSUPP; 479 480 if (!buffer) 481 return lookup_and_delete_xattr(inode, name); 482 483 dentry = xattr_lookup(inode, name, flags); 484 if (IS_ERR(dentry)) 485 return PTR_ERR(dentry); 486 487 reiserfs_down_read_safe(&REISERFS_I(inode)->i_xattr_sem, inode->i_sb); 488 489 xahash = xattr_hash(buffer, buffer_size); 490 while (buffer_pos < buffer_size || buffer_pos == 0) { 491 size_t chunk; 492 size_t skip = 0; 493 size_t page_offset = (file_pos & (PAGE_CACHE_SIZE - 1)); 494 if (buffer_size - buffer_pos > PAGE_CACHE_SIZE) 495 chunk = PAGE_CACHE_SIZE; 496 else 497 chunk = buffer_size - buffer_pos; 498 499 page = reiserfs_get_page(dentry->d_inode, file_pos); 500 if (IS_ERR(page)) { 501 err = PTR_ERR(page); 502 goto out_unlock; 503 } 504 505 lock_page(page); 506 data = page_address(page); 507 508 if (file_pos == 0) { 509 struct reiserfs_xattr_header *rxh; 510 skip = file_pos = sizeof(struct reiserfs_xattr_header); 511 if (chunk + skip > PAGE_CACHE_SIZE) 512 chunk = PAGE_CACHE_SIZE - skip; 513 rxh = (struct reiserfs_xattr_header *)data; 514 rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC); 515 rxh->h_hash = cpu_to_le32(xahash); 516 } 517 518 err = reiserfs_prepare_write(NULL, page, page_offset, 519 page_offset + chunk + skip); 520 if (!err) { 521 if (buffer) 522 memcpy(data + skip, buffer + buffer_pos, chunk); 523 err = reiserfs_commit_write(NULL, page, page_offset, 524 page_offset + chunk + 525 skip); 526 } 527 unlock_page(page); 528 reiserfs_put_page(page); 529 buffer_pos += chunk; 530 file_pos += chunk; 531 skip = 0; 532 if (err || buffer_size == 0 || !buffer) 533 break; 534 } 535 536 new_size = buffer_size + sizeof(struct reiserfs_xattr_header); 537 if (!err && new_size < i_size_read(dentry->d_inode)) { 538 struct iattr newattrs = { 539 .ia_ctime = current_fs_time(inode->i_sb), 540 .ia_size = buffer_size, 541 .ia_valid = ATTR_SIZE | ATTR_CTIME, 542 }; 543 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR); 544 down_write(&dentry->d_inode->i_alloc_sem); 545 err = reiserfs_setattr(dentry, &newattrs); 546 up_write(&dentry->d_inode->i_alloc_sem); 547 mutex_unlock(&dentry->d_inode->i_mutex); 548 } else 549 update_ctime(inode); 550 out_unlock: 551 up_write(&REISERFS_I(inode)->i_xattr_sem); 552 dput(dentry); 553 return err; 554 } 555 556 /* We need to start a transaction to maintain lock ordering */ 557 int reiserfs_xattr_set(struct inode *inode, const char *name, 558 const void *buffer, size_t buffer_size, int flags) 559 { 560 561 struct reiserfs_transaction_handle th; 562 int error, error2; 563 size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size); 564 565 if (!(flags & XATTR_REPLACE)) 566 jbegin_count += reiserfs_xattr_jcreate_nblocks(inode); 567 568 reiserfs_write_lock(inode->i_sb); 569 error = journal_begin(&th, inode->i_sb, jbegin_count); 570 if (error) { 571 reiserfs_write_unlock(inode->i_sb); 572 return error; 573 } 574 575 error = reiserfs_xattr_set_handle(&th, inode, name, 576 buffer, buffer_size, flags); 577 578 error2 = journal_end(&th, inode->i_sb, jbegin_count); 579 if (error == 0) 580 error = error2; 581 reiserfs_write_unlock(inode->i_sb); 582 583 return error; 584 } 585 586 /* 587 * inode->i_mutex: down 588 */ 589 int 590 reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer, 591 size_t buffer_size) 592 { 593 ssize_t err = 0; 594 struct dentry *dentry; 595 size_t isize; 596 size_t file_pos = 0; 597 size_t buffer_pos = 0; 598 struct page *page; 599 __u32 hash = 0; 600 601 if (name == NULL) 602 return -EINVAL; 603 604 /* We can't have xattrs attached to v1 items since they don't have 605 * generation numbers */ 606 if (get_inode_sd_version(inode) == STAT_DATA_V1) 607 return -EOPNOTSUPP; 608 609 dentry = xattr_lookup(inode, name, XATTR_REPLACE); 610 if (IS_ERR(dentry)) { 611 err = PTR_ERR(dentry); 612 goto out; 613 } 614 615 down_read(&REISERFS_I(inode)->i_xattr_sem); 616 617 isize = i_size_read(dentry->d_inode); 618 619 /* Just return the size needed */ 620 if (buffer == NULL) { 621 err = isize - sizeof(struct reiserfs_xattr_header); 622 goto out_unlock; 623 } 624 625 if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) { 626 err = -ERANGE; 627 goto out_unlock; 628 } 629 630 while (file_pos < isize) { 631 size_t chunk; 632 char *data; 633 size_t skip = 0; 634 if (isize - file_pos > PAGE_CACHE_SIZE) 635 chunk = PAGE_CACHE_SIZE; 636 else 637 chunk = isize - file_pos; 638 639 page = reiserfs_get_page(dentry->d_inode, file_pos); 640 if (IS_ERR(page)) { 641 err = PTR_ERR(page); 642 goto out_unlock; 643 } 644 645 lock_page(page); 646 data = page_address(page); 647 if (file_pos == 0) { 648 struct reiserfs_xattr_header *rxh = 649 (struct reiserfs_xattr_header *)data; 650 skip = file_pos = sizeof(struct reiserfs_xattr_header); 651 chunk -= skip; 652 /* Magic doesn't match up.. */ 653 if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) { 654 unlock_page(page); 655 reiserfs_put_page(page); 656 reiserfs_warning(inode->i_sb, "jdm-20001", 657 "Invalid magic for xattr (%s) " 658 "associated with %k", name, 659 INODE_PKEY(inode)); 660 err = -EIO; 661 goto out_unlock; 662 } 663 hash = le32_to_cpu(rxh->h_hash); 664 } 665 memcpy(buffer + buffer_pos, data + skip, chunk); 666 unlock_page(page); 667 reiserfs_put_page(page); 668 file_pos += chunk; 669 buffer_pos += chunk; 670 skip = 0; 671 } 672 err = isize - sizeof(struct reiserfs_xattr_header); 673 674 if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) != 675 hash) { 676 reiserfs_warning(inode->i_sb, "jdm-20002", 677 "Invalid hash for xattr (%s) associated " 678 "with %k", name, INODE_PKEY(inode)); 679 err = -EIO; 680 } 681 682 out_unlock: 683 up_read(&REISERFS_I(inode)->i_xattr_sem); 684 dput(dentry); 685 686 out: 687 return err; 688 } 689 690 /* 691 * In order to implement different sets of xattr operations for each xattr 692 * prefix with the generic xattr API, a filesystem should create a 693 * null-terminated array of struct xattr_handler (one for each prefix) and 694 * hang a pointer to it off of the s_xattr field of the superblock. 695 * 696 * The generic_fooxattr() functions will use this list to dispatch xattr 697 * operations to the correct xattr_handler. 698 */ 699 #define for_each_xattr_handler(handlers, handler) \ 700 for ((handler) = *(handlers)++; \ 701 (handler) != NULL; \ 702 (handler) = *(handlers)++) 703 704 /* This is the implementation for the xattr plugin infrastructure */ 705 static inline struct xattr_handler * 706 find_xattr_handler_prefix(struct xattr_handler **handlers, 707 const char *name) 708 { 709 struct xattr_handler *xah; 710 711 if (!handlers) 712 return NULL; 713 714 for_each_xattr_handler(handlers, xah) { 715 if (strncmp(xah->prefix, name, strlen(xah->prefix)) == 0) 716 break; 717 } 718 719 return xah; 720 } 721 722 723 /* 724 * Inode operation getxattr() 725 */ 726 ssize_t 727 reiserfs_getxattr(struct dentry * dentry, const char *name, void *buffer, 728 size_t size) 729 { 730 struct inode *inode = dentry->d_inode; 731 struct xattr_handler *handler; 732 733 handler = find_xattr_handler_prefix(inode->i_sb->s_xattr, name); 734 735 if (!handler || get_inode_sd_version(inode) == STAT_DATA_V1) 736 return -EOPNOTSUPP; 737 738 return handler->get(inode, name, buffer, size); 739 } 740 741 /* 742 * Inode operation setxattr() 743 * 744 * dentry->d_inode->i_mutex down 745 */ 746 int 747 reiserfs_setxattr(struct dentry *dentry, const char *name, const void *value, 748 size_t size, int flags) 749 { 750 struct inode *inode = dentry->d_inode; 751 struct xattr_handler *handler; 752 753 handler = find_xattr_handler_prefix(inode->i_sb->s_xattr, name); 754 755 if (!handler || get_inode_sd_version(inode) == STAT_DATA_V1) 756 return -EOPNOTSUPP; 757 758 return handler->set(inode, name, value, size, flags); 759 } 760 761 /* 762 * Inode operation removexattr() 763 * 764 * dentry->d_inode->i_mutex down 765 */ 766 int reiserfs_removexattr(struct dentry *dentry, const char *name) 767 { 768 struct inode *inode = dentry->d_inode; 769 struct xattr_handler *handler; 770 handler = find_xattr_handler_prefix(inode->i_sb->s_xattr, name); 771 772 if (!handler || get_inode_sd_version(inode) == STAT_DATA_V1) 773 return -EOPNOTSUPP; 774 775 return handler->set(inode, name, NULL, 0, XATTR_REPLACE); 776 } 777 778 struct listxattr_buf { 779 size_t size; 780 size_t pos; 781 char *buf; 782 struct inode *inode; 783 }; 784 785 static int listxattr_filler(void *buf, const char *name, int namelen, 786 loff_t offset, u64 ino, unsigned int d_type) 787 { 788 struct listxattr_buf *b = (struct listxattr_buf *)buf; 789 size_t size; 790 if (name[0] != '.' || 791 (namelen != 1 && (name[1] != '.' || namelen != 2))) { 792 struct xattr_handler *handler; 793 handler = find_xattr_handler_prefix(b->inode->i_sb->s_xattr, 794 name); 795 if (!handler) /* Unsupported xattr name */ 796 return 0; 797 if (b->buf) { 798 size = handler->list(b->inode, b->buf + b->pos, 799 b->size, name, namelen); 800 if (size > b->size) 801 return -ERANGE; 802 } else { 803 size = handler->list(b->inode, NULL, 0, name, namelen); 804 } 805 806 b->pos += size; 807 } 808 return 0; 809 } 810 811 /* 812 * Inode operation listxattr() 813 * 814 * We totally ignore the generic listxattr here because it would be stupid 815 * not to. Since the xattrs are organized in a directory, we can just 816 * readdir to find them. 817 */ 818 ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size) 819 { 820 struct dentry *dir; 821 int err = 0; 822 loff_t pos = 0; 823 struct listxattr_buf buf = { 824 .inode = dentry->d_inode, 825 .buf = buffer, 826 .size = buffer ? size : 0, 827 }; 828 829 if (!dentry->d_inode) 830 return -EINVAL; 831 832 if (!dentry->d_sb->s_xattr || 833 get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1) 834 return -EOPNOTSUPP; 835 836 dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE); 837 if (IS_ERR(dir)) { 838 err = PTR_ERR(dir); 839 if (err == -ENODATA) 840 err = 0; /* Not an error if there aren't any xattrs */ 841 goto out; 842 } 843 844 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR); 845 err = reiserfs_readdir_dentry(dir, &buf, listxattr_filler, &pos); 846 mutex_unlock(&dir->d_inode->i_mutex); 847 848 if (!err) 849 err = buf.pos; 850 851 dput(dir); 852 out: 853 return err; 854 } 855 856 static int reiserfs_check_acl(struct inode *inode, int mask) 857 { 858 struct posix_acl *acl; 859 int error = -EAGAIN; /* do regular unix permission checks by default */ 860 861 acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS); 862 863 if (acl) { 864 if (!IS_ERR(acl)) { 865 error = posix_acl_permission(inode, acl, mask); 866 posix_acl_release(acl); 867 } else if (PTR_ERR(acl) != -ENODATA) 868 error = PTR_ERR(acl); 869 } 870 871 return error; 872 } 873 874 static int create_privroot(struct dentry *dentry) 875 { 876 int err; 877 struct inode *inode = dentry->d_parent->d_inode; 878 WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex)); 879 880 err = xattr_mkdir(inode, dentry, 0700); 881 if (err || !dentry->d_inode) { 882 reiserfs_warning(dentry->d_sb, "jdm-20006", 883 "xattrs/ACLs enabled and couldn't " 884 "find/create .reiserfs_priv. " 885 "Failing mount."); 886 return -EOPNOTSUPP; 887 } 888 889 dentry->d_inode->i_flags |= S_PRIVATE; 890 reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr " 891 "storage.\n", PRIVROOT_NAME); 892 893 return 0; 894 } 895 896 #else 897 int __init reiserfs_xattr_register_handlers(void) { return 0; } 898 void reiserfs_xattr_unregister_handlers(void) {} 899 static int create_privroot(struct dentry *dentry) { return 0; } 900 #endif 901 902 /* Actual operations that are exported to VFS-land */ 903 struct xattr_handler *reiserfs_xattr_handlers[] = { 904 #ifdef CONFIG_REISERFS_FS_XATTR 905 &reiserfs_xattr_user_handler, 906 &reiserfs_xattr_trusted_handler, 907 #endif 908 #ifdef CONFIG_REISERFS_FS_SECURITY 909 &reiserfs_xattr_security_handler, 910 #endif 911 #ifdef CONFIG_REISERFS_FS_POSIX_ACL 912 &reiserfs_posix_acl_access_handler, 913 &reiserfs_posix_acl_default_handler, 914 #endif 915 NULL 916 }; 917 918 static int xattr_mount_check(struct super_block *s) 919 { 920 /* We need generation numbers to ensure that the oid mapping is correct 921 * v3.5 filesystems don't have them. */ 922 if (old_format_only(s)) { 923 if (reiserfs_xattrs_optional(s)) { 924 /* Old format filesystem, but optional xattrs have 925 * been enabled. Error out. */ 926 reiserfs_warning(s, "jdm-2005", 927 "xattrs/ACLs not supported " 928 "on pre-v3.6 format filesystems. " 929 "Failing mount."); 930 return -EOPNOTSUPP; 931 } 932 } 933 934 return 0; 935 } 936 937 int reiserfs_permission(struct inode *inode, int mask) 938 { 939 /* 940 * We don't do permission checks on the internal objects. 941 * Permissions are determined by the "owning" object. 942 */ 943 if (IS_PRIVATE(inode)) 944 return 0; 945 946 #ifdef CONFIG_REISERFS_FS_XATTR 947 /* 948 * Stat data v1 doesn't support ACLs. 949 */ 950 if (get_inode_sd_version(inode) != STAT_DATA_V1) 951 return generic_permission(inode, mask, reiserfs_check_acl); 952 #endif 953 return generic_permission(inode, mask, NULL); 954 } 955 956 /* This will catch lookups from the fs root to .reiserfs_priv */ 957 static int 958 xattr_lookup_poison(struct dentry *dentry, struct qstr *q1, struct qstr *name) 959 { 960 struct dentry *priv_root = REISERFS_SB(dentry->d_sb)->priv_root; 961 if (container_of(q1, struct dentry, d_name) == priv_root) 962 return -ENOENT; 963 if (q1->len == name->len && 964 !memcmp(q1->name, name->name, name->len)) 965 return 0; 966 return 1; 967 } 968 969 static const struct dentry_operations xattr_lookup_poison_ops = { 970 .d_compare = xattr_lookup_poison, 971 }; 972 973 int reiserfs_lookup_privroot(struct super_block *s) 974 { 975 struct dentry *dentry; 976 int err = 0; 977 978 /* If we don't have the privroot located yet - go find it */ 979 reiserfs_mutex_lock_safe(&s->s_root->d_inode->i_mutex, s); 980 dentry = lookup_one_len(PRIVROOT_NAME, s->s_root, 981 strlen(PRIVROOT_NAME)); 982 if (!IS_ERR(dentry)) { 983 REISERFS_SB(s)->priv_root = dentry; 984 if (!reiserfs_expose_privroot(s)) 985 s->s_root->d_op = &xattr_lookup_poison_ops; 986 if (dentry->d_inode) 987 dentry->d_inode->i_flags |= S_PRIVATE; 988 } else 989 err = PTR_ERR(dentry); 990 mutex_unlock(&s->s_root->d_inode->i_mutex); 991 992 return err; 993 } 994 995 /* We need to take a copy of the mount flags since things like 996 * MS_RDONLY don't get set until *after* we're called. 997 * mount_flags != mount_options */ 998 int reiserfs_xattr_init(struct super_block *s, int mount_flags) 999 { 1000 int err = 0; 1001 struct dentry *privroot = REISERFS_SB(s)->priv_root; 1002 1003 err = xattr_mount_check(s); 1004 if (err) 1005 goto error; 1006 1007 if (!privroot->d_inode && !(mount_flags & MS_RDONLY)) { 1008 reiserfs_mutex_lock_safe(&s->s_root->d_inode->i_mutex, s); 1009 err = create_privroot(REISERFS_SB(s)->priv_root); 1010 mutex_unlock(&s->s_root->d_inode->i_mutex); 1011 } 1012 1013 if (privroot->d_inode) { 1014 s->s_xattr = reiserfs_xattr_handlers; 1015 reiserfs_mutex_lock_safe(&privroot->d_inode->i_mutex, s); 1016 if (!REISERFS_SB(s)->xattr_root) { 1017 struct dentry *dentry; 1018 dentry = lookup_one_len(XAROOT_NAME, privroot, 1019 strlen(XAROOT_NAME)); 1020 if (!IS_ERR(dentry)) 1021 REISERFS_SB(s)->xattr_root = dentry; 1022 else 1023 err = PTR_ERR(dentry); 1024 } 1025 mutex_unlock(&privroot->d_inode->i_mutex); 1026 } 1027 1028 error: 1029 if (err) { 1030 clear_bit(REISERFS_XATTRS_USER, &(REISERFS_SB(s)->s_mount_opt)); 1031 clear_bit(REISERFS_POSIXACL, &(REISERFS_SB(s)->s_mount_opt)); 1032 } 1033 1034 /* The super_block MS_POSIXACL must mirror the (no)acl mount option. */ 1035 if (reiserfs_posixacl(s)) 1036 s->s_flags |= MS_POSIXACL; 1037 else 1038 s->s_flags &= ~MS_POSIXACL; 1039 1040 return err; 1041 } 1042