1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext2/xattr.c 4 * 5 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de> 6 * 7 * Fix by Harrison Xing <harrison@mountainviewdata.com>. 8 * Extended attributes for symlinks and special files added per 9 * suggestion of Luka Renko <luka.renko@hermes.si>. 10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>, 11 * Red Hat Inc. 12 * 13 */ 14 15 /* 16 * Extended attributes are stored on disk blocks allocated outside of 17 * any inode. The i_file_acl field is then made to point to this allocated 18 * block. If all extended attributes of an inode are identical, these 19 * inodes may share the same extended attribute block. Such situations 20 * are automatically detected by keeping a cache of recent attribute block 21 * numbers and hashes over the block's contents in memory. 22 * 23 * 24 * Extended attribute block layout: 25 * 26 * +------------------+ 27 * | header | 28 * | entry 1 | | 29 * | entry 2 | | growing downwards 30 * | entry 3 | v 31 * | four null bytes | 32 * | . . . | 33 * | value 1 | ^ 34 * | value 3 | | growing upwards 35 * | value 2 | | 36 * +------------------+ 37 * 38 * The block header is followed by multiple entry descriptors. These entry 39 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD 40 * byte boundaries. The entry descriptors are sorted by attribute name, 41 * so that two extended attribute blocks can be compared efficiently. 42 * 43 * Attribute values are aligned to the end of the block, stored in 44 * no specific order. They are also padded to EXT2_XATTR_PAD byte 45 * boundaries. No additional gaps are left between them. 46 * 47 * Locking strategy 48 * ---------------- 49 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem. 50 * EA blocks are only changed if they are exclusive to an inode, so 51 * holding xattr_sem also means that nothing but the EA block's reference 52 * count will change. Multiple writers to an EA block are synchronized 53 * by the bh lock. No more than a single bh lock is held at any time 54 * to avoid deadlocks. 55 */ 56 57 #include <linux/buffer_head.h> 58 #include <linux/init.h> 59 #include <linux/slab.h> 60 #include <linux/mbcache.h> 61 #include <linux/quotaops.h> 62 #include <linux/rwsem.h> 63 #include <linux/security.h> 64 #include "ext2.h" 65 #include "xattr.h" 66 #include "acl.h" 67 68 #define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data)) 69 #define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr)) 70 #define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1) 71 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) 72 73 #ifdef EXT2_XATTR_DEBUG 74 # define ea_idebug(inode, f...) do { \ 75 printk(KERN_DEBUG "inode %s:%ld: ", \ 76 inode->i_sb->s_id, inode->i_ino); \ 77 printk(f); \ 78 printk("\n"); \ 79 } while (0) 80 # define ea_bdebug(bh, f...) do { \ 81 printk(KERN_DEBUG "block %pg:%lu: ", \ 82 bh->b_bdev, (unsigned long) bh->b_blocknr); \ 83 printk(f); \ 84 printk("\n"); \ 85 } while (0) 86 #else 87 # define ea_idebug(f...) 88 # define ea_bdebug(f...) 89 #endif 90 91 static int ext2_xattr_set2(struct inode *, struct buffer_head *, 92 struct ext2_xattr_header *); 93 94 static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *); 95 static struct buffer_head *ext2_xattr_cache_find(struct inode *, 96 struct ext2_xattr_header *); 97 static void ext2_xattr_rehash(struct ext2_xattr_header *, 98 struct ext2_xattr_entry *); 99 100 static const struct xattr_handler *ext2_xattr_handler_map[] = { 101 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler, 102 #ifdef CONFIG_EXT2_FS_POSIX_ACL 103 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler, 104 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler, 105 #endif 106 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler, 107 #ifdef CONFIG_EXT2_FS_SECURITY 108 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler, 109 #endif 110 }; 111 112 const struct xattr_handler *ext2_xattr_handlers[] = { 113 &ext2_xattr_user_handler, 114 &ext2_xattr_trusted_handler, 115 #ifdef CONFIG_EXT2_FS_POSIX_ACL 116 &posix_acl_access_xattr_handler, 117 &posix_acl_default_xattr_handler, 118 #endif 119 #ifdef CONFIG_EXT2_FS_SECURITY 120 &ext2_xattr_security_handler, 121 #endif 122 NULL 123 }; 124 125 #define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache) 126 127 static inline const struct xattr_handler * 128 ext2_xattr_handler(int name_index) 129 { 130 const struct xattr_handler *handler = NULL; 131 132 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map)) 133 handler = ext2_xattr_handler_map[name_index]; 134 return handler; 135 } 136 137 static bool 138 ext2_xattr_header_valid(struct ext2_xattr_header *header) 139 { 140 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 141 header->h_blocks != cpu_to_le32(1)) 142 return false; 143 144 return true; 145 } 146 147 static bool 148 ext2_xattr_entry_valid(struct ext2_xattr_entry *entry, 149 char *end, size_t end_offs) 150 { 151 struct ext2_xattr_entry *next; 152 size_t size; 153 154 next = EXT2_XATTR_NEXT(entry); 155 if ((char *)next >= end) 156 return false; 157 158 if (entry->e_value_block != 0) 159 return false; 160 161 size = le32_to_cpu(entry->e_value_size); 162 if (size > end_offs || 163 le16_to_cpu(entry->e_value_offs) + size > end_offs) 164 return false; 165 166 return true; 167 } 168 169 static int 170 ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name, 171 struct ext2_xattr_entry *entry) 172 { 173 int cmp; 174 175 cmp = name_index - entry->e_name_index; 176 if (!cmp) 177 cmp = name_len - entry->e_name_len; 178 if (!cmp) 179 cmp = memcmp(name, entry->e_name, name_len); 180 181 return cmp; 182 } 183 184 /* 185 * ext2_xattr_get() 186 * 187 * Copy an extended attribute into the buffer 188 * provided, or compute the buffer size required. 189 * Buffer is NULL to compute the size of the buffer required. 190 * 191 * Returns a negative error number on failure, or the number of bytes 192 * used / required on success. 193 */ 194 int 195 ext2_xattr_get(struct inode *inode, int name_index, const char *name, 196 void *buffer, size_t buffer_size) 197 { 198 struct buffer_head *bh = NULL; 199 struct ext2_xattr_entry *entry; 200 size_t name_len, size; 201 char *end; 202 int error, not_found; 203 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 204 205 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", 206 name_index, name, buffer, (long)buffer_size); 207 208 if (name == NULL) 209 return -EINVAL; 210 name_len = strlen(name); 211 if (name_len > 255) 212 return -ERANGE; 213 214 down_read(&EXT2_I(inode)->xattr_sem); 215 error = -ENODATA; 216 if (!EXT2_I(inode)->i_file_acl) 217 goto cleanup; 218 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 219 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 220 error = -EIO; 221 if (!bh) 222 goto cleanup; 223 ea_bdebug(bh, "b_count=%d, refcount=%d", 224 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 225 end = bh->b_data + bh->b_size; 226 if (!ext2_xattr_header_valid(HDR(bh))) { 227 bad_block: 228 ext2_error(inode->i_sb, "ext2_xattr_get", 229 "inode %ld: bad block %d", inode->i_ino, 230 EXT2_I(inode)->i_file_acl); 231 error = -EIO; 232 goto cleanup; 233 } 234 235 /* find named attribute */ 236 entry = FIRST_ENTRY(bh); 237 while (!IS_LAST_ENTRY(entry)) { 238 if (!ext2_xattr_entry_valid(entry, end, 239 inode->i_sb->s_blocksize)) 240 goto bad_block; 241 242 not_found = ext2_xattr_cmp_entry(name_index, name_len, name, 243 entry); 244 if (!not_found) 245 goto found; 246 if (not_found < 0) 247 break; 248 249 entry = EXT2_XATTR_NEXT(entry); 250 } 251 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 252 ea_idebug(inode, "cache insert failed"); 253 error = -ENODATA; 254 goto cleanup; 255 found: 256 size = le32_to_cpu(entry->e_value_size); 257 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 258 ea_idebug(inode, "cache insert failed"); 259 if (buffer) { 260 error = -ERANGE; 261 if (size > buffer_size) 262 goto cleanup; 263 /* return value of attribute */ 264 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), 265 size); 266 } 267 error = size; 268 269 cleanup: 270 brelse(bh); 271 up_read(&EXT2_I(inode)->xattr_sem); 272 273 return error; 274 } 275 276 /* 277 * ext2_xattr_list() 278 * 279 * Copy a list of attribute names into the buffer 280 * provided, or compute the buffer size required. 281 * Buffer is NULL to compute the size of the buffer required. 282 * 283 * Returns a negative error number on failure, or the number of bytes 284 * used / required on success. 285 */ 286 static int 287 ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) 288 { 289 struct inode *inode = d_inode(dentry); 290 struct buffer_head *bh = NULL; 291 struct ext2_xattr_entry *entry; 292 char *end; 293 size_t rest = buffer_size; 294 int error; 295 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 296 297 ea_idebug(inode, "buffer=%p, buffer_size=%ld", 298 buffer, (long)buffer_size); 299 300 down_read(&EXT2_I(inode)->xattr_sem); 301 error = 0; 302 if (!EXT2_I(inode)->i_file_acl) 303 goto cleanup; 304 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 305 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 306 error = -EIO; 307 if (!bh) 308 goto cleanup; 309 ea_bdebug(bh, "b_count=%d, refcount=%d", 310 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 311 end = bh->b_data + bh->b_size; 312 if (!ext2_xattr_header_valid(HDR(bh))) { 313 bad_block: 314 ext2_error(inode->i_sb, "ext2_xattr_list", 315 "inode %ld: bad block %d", inode->i_ino, 316 EXT2_I(inode)->i_file_acl); 317 error = -EIO; 318 goto cleanup; 319 } 320 321 /* check the on-disk data structure */ 322 entry = FIRST_ENTRY(bh); 323 while (!IS_LAST_ENTRY(entry)) { 324 if (!ext2_xattr_entry_valid(entry, end, 325 inode->i_sb->s_blocksize)) 326 goto bad_block; 327 entry = EXT2_XATTR_NEXT(entry); 328 } 329 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 330 ea_idebug(inode, "cache insert failed"); 331 332 /* list the attribute names */ 333 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); 334 entry = EXT2_XATTR_NEXT(entry)) { 335 const struct xattr_handler *handler = 336 ext2_xattr_handler(entry->e_name_index); 337 338 if (handler && (!handler->list || handler->list(dentry))) { 339 const char *prefix = handler->prefix ?: handler->name; 340 size_t prefix_len = strlen(prefix); 341 size_t size = prefix_len + entry->e_name_len + 1; 342 343 if (buffer) { 344 if (size > rest) { 345 error = -ERANGE; 346 goto cleanup; 347 } 348 memcpy(buffer, prefix, prefix_len); 349 buffer += prefix_len; 350 memcpy(buffer, entry->e_name, entry->e_name_len); 351 buffer += entry->e_name_len; 352 *buffer++ = 0; 353 } 354 rest -= size; 355 } 356 } 357 error = buffer_size - rest; /* total size */ 358 359 cleanup: 360 brelse(bh); 361 up_read(&EXT2_I(inode)->xattr_sem); 362 363 return error; 364 } 365 366 /* 367 * Inode operation listxattr() 368 * 369 * d_inode(dentry)->i_mutex: don't care 370 */ 371 ssize_t 372 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) 373 { 374 return ext2_xattr_list(dentry, buffer, size); 375 } 376 377 /* 378 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is 379 * not set, set it. 380 */ 381 static void ext2_xattr_update_super_block(struct super_block *sb) 382 { 383 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR)) 384 return; 385 386 spin_lock(&EXT2_SB(sb)->s_lock); 387 ext2_update_dynamic_rev(sb); 388 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR); 389 spin_unlock(&EXT2_SB(sb)->s_lock); 390 mark_buffer_dirty(EXT2_SB(sb)->s_sbh); 391 } 392 393 /* 394 * ext2_xattr_set() 395 * 396 * Create, replace or remove an extended attribute for this inode. Value 397 * is NULL to remove an existing extended attribute, and non-NULL to 398 * either replace an existing extended attribute, or create a new extended 399 * attribute. The flags XATTR_REPLACE and XATTR_CREATE 400 * specify that an extended attribute must exist and must not exist 401 * previous to the call, respectively. 402 * 403 * Returns 0, or a negative error number on failure. 404 */ 405 int 406 ext2_xattr_set(struct inode *inode, int name_index, const char *name, 407 const void *value, size_t value_len, int flags) 408 { 409 struct super_block *sb = inode->i_sb; 410 struct buffer_head *bh = NULL; 411 struct ext2_xattr_header *header = NULL; 412 struct ext2_xattr_entry *here = NULL, *last = NULL; 413 size_t name_len, free, min_offs = sb->s_blocksize; 414 int not_found = 1, error; 415 char *end; 416 417 /* 418 * header -- Points either into bh, or to a temporarily 419 * allocated buffer. 420 * here -- The named entry found, or the place for inserting, within 421 * the block pointed to by header. 422 * last -- Points right after the last named entry within the block 423 * pointed to by header. 424 * min_offs -- The offset of the first value (values are aligned 425 * towards the end of the block). 426 * end -- Points right after the block pointed to by header. 427 */ 428 429 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", 430 name_index, name, value, (long)value_len); 431 432 if (value == NULL) 433 value_len = 0; 434 if (name == NULL) 435 return -EINVAL; 436 name_len = strlen(name); 437 if (name_len > 255 || value_len > sb->s_blocksize) 438 return -ERANGE; 439 down_write(&EXT2_I(inode)->xattr_sem); 440 if (EXT2_I(inode)->i_file_acl) { 441 /* The inode already has an extended attribute block. */ 442 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 443 error = -EIO; 444 if (!bh) 445 goto cleanup; 446 ea_bdebug(bh, "b_count=%d, refcount=%d", 447 atomic_read(&(bh->b_count)), 448 le32_to_cpu(HDR(bh)->h_refcount)); 449 header = HDR(bh); 450 end = bh->b_data + bh->b_size; 451 if (!ext2_xattr_header_valid(header)) { 452 bad_block: 453 ext2_error(sb, "ext2_xattr_set", 454 "inode %ld: bad block %d", inode->i_ino, 455 EXT2_I(inode)->i_file_acl); 456 error = -EIO; 457 goto cleanup; 458 } 459 /* 460 * Find the named attribute. If not found, 'here' will point 461 * to entry where the new attribute should be inserted to 462 * maintain sorting. 463 */ 464 last = FIRST_ENTRY(bh); 465 while (!IS_LAST_ENTRY(last)) { 466 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize)) 467 goto bad_block; 468 if (last->e_value_size) { 469 size_t offs = le16_to_cpu(last->e_value_offs); 470 if (offs < min_offs) 471 min_offs = offs; 472 } 473 if (not_found > 0) { 474 not_found = ext2_xattr_cmp_entry(name_index, 475 name_len, 476 name, last); 477 if (not_found <= 0) 478 here = last; 479 } 480 last = EXT2_XATTR_NEXT(last); 481 } 482 if (not_found > 0) 483 here = last; 484 485 /* Check whether we have enough space left. */ 486 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 487 } else { 488 /* We will use a new extended attribute block. */ 489 free = sb->s_blocksize - 490 sizeof(struct ext2_xattr_header) - sizeof(__u32); 491 } 492 493 if (not_found) { 494 /* Request to remove a nonexistent attribute? */ 495 error = -ENODATA; 496 if (flags & XATTR_REPLACE) 497 goto cleanup; 498 error = 0; 499 if (value == NULL) 500 goto cleanup; 501 } else { 502 /* Request to create an existing attribute? */ 503 error = -EEXIST; 504 if (flags & XATTR_CREATE) 505 goto cleanup; 506 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size)); 507 free += EXT2_XATTR_LEN(name_len); 508 } 509 error = -ENOSPC; 510 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 511 goto cleanup; 512 513 /* Here we know that we can set the new attribute. */ 514 515 if (header) { 516 /* assert(header == HDR(bh)); */ 517 lock_buffer(bh); 518 if (header->h_refcount == cpu_to_le32(1)) { 519 __u32 hash = le32_to_cpu(header->h_hash); 520 521 ea_bdebug(bh, "modifying in-place"); 522 /* 523 * This must happen under buffer lock for 524 * ext2_xattr_set2() to reliably detect modified block 525 */ 526 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, 527 bh->b_blocknr); 528 529 /* keep the buffer locked while modifying it. */ 530 } else { 531 int offset; 532 533 unlock_buffer(bh); 534 ea_bdebug(bh, "cloning"); 535 header = kmalloc(bh->b_size, GFP_KERNEL); 536 error = -ENOMEM; 537 if (header == NULL) 538 goto cleanup; 539 memcpy(header, HDR(bh), bh->b_size); 540 header->h_refcount = cpu_to_le32(1); 541 542 offset = (char *)here - bh->b_data; 543 here = ENTRY((char *)header + offset); 544 offset = (char *)last - bh->b_data; 545 last = ENTRY((char *)header + offset); 546 } 547 } else { 548 /* Allocate a buffer where we construct the new block. */ 549 header = kzalloc(sb->s_blocksize, GFP_KERNEL); 550 error = -ENOMEM; 551 if (header == NULL) 552 goto cleanup; 553 end = (char *)header + sb->s_blocksize; 554 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); 555 header->h_blocks = header->h_refcount = cpu_to_le32(1); 556 last = here = ENTRY(header+1); 557 } 558 559 /* Iff we are modifying the block in-place, bh is locked here. */ 560 561 if (not_found) { 562 /* Insert the new name. */ 563 size_t size = EXT2_XATTR_LEN(name_len); 564 size_t rest = (char *)last - (char *)here; 565 memmove((char *)here + size, here, rest); 566 memset(here, 0, size); 567 here->e_name_index = name_index; 568 here->e_name_len = name_len; 569 memcpy(here->e_name, name, name_len); 570 } else { 571 if (here->e_value_size) { 572 char *first_val = (char *)header + min_offs; 573 size_t offs = le16_to_cpu(here->e_value_offs); 574 char *val = (char *)header + offs; 575 size_t size = EXT2_XATTR_SIZE( 576 le32_to_cpu(here->e_value_size)); 577 578 if (size == EXT2_XATTR_SIZE(value_len)) { 579 /* The old and the new value have the same 580 size. Just replace. */ 581 here->e_value_size = cpu_to_le32(value_len); 582 memset(val + size - EXT2_XATTR_PAD, 0, 583 EXT2_XATTR_PAD); /* Clear pad bytes. */ 584 memcpy(val, value, value_len); 585 goto skip_replace; 586 } 587 588 /* Remove the old value. */ 589 memmove(first_val + size, first_val, val - first_val); 590 memset(first_val, 0, size); 591 here->e_value_offs = 0; 592 min_offs += size; 593 594 /* Adjust all value offsets. */ 595 last = ENTRY(header+1); 596 while (!IS_LAST_ENTRY(last)) { 597 size_t o = le16_to_cpu(last->e_value_offs); 598 if (o < offs) 599 last->e_value_offs = 600 cpu_to_le16(o + size); 601 last = EXT2_XATTR_NEXT(last); 602 } 603 } 604 if (value == NULL) { 605 /* Remove the old name. */ 606 size_t size = EXT2_XATTR_LEN(name_len); 607 last = ENTRY((char *)last - size); 608 memmove(here, (char*)here + size, 609 (char*)last - (char*)here); 610 memset(last, 0, size); 611 } 612 } 613 614 if (value != NULL) { 615 /* Insert the new value. */ 616 here->e_value_size = cpu_to_le32(value_len); 617 if (value_len) { 618 size_t size = EXT2_XATTR_SIZE(value_len); 619 char *val = (char *)header + min_offs - size; 620 here->e_value_offs = 621 cpu_to_le16((char *)val - (char *)header); 622 memset(val + size - EXT2_XATTR_PAD, 0, 623 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 624 memcpy(val, value, value_len); 625 } 626 } 627 628 skip_replace: 629 if (IS_LAST_ENTRY(ENTRY(header+1))) { 630 /* This block is now empty. */ 631 if (bh && header == HDR(bh)) 632 unlock_buffer(bh); /* we were modifying in-place. */ 633 error = ext2_xattr_set2(inode, bh, NULL); 634 } else { 635 ext2_xattr_rehash(header, here); 636 if (bh && header == HDR(bh)) 637 unlock_buffer(bh); /* we were modifying in-place. */ 638 error = ext2_xattr_set2(inode, bh, header); 639 } 640 641 cleanup: 642 if (!(bh && header == HDR(bh))) 643 kfree(header); 644 brelse(bh); 645 up_write(&EXT2_I(inode)->xattr_sem); 646 647 return error; 648 } 649 650 /* 651 * Second half of ext2_xattr_set(): Update the file system. 652 */ 653 static int 654 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 655 struct ext2_xattr_header *header) 656 { 657 struct super_block *sb = inode->i_sb; 658 struct buffer_head *new_bh = NULL; 659 int error; 660 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 661 662 if (header) { 663 new_bh = ext2_xattr_cache_find(inode, header); 664 if (new_bh) { 665 /* We found an identical block in the cache. */ 666 if (new_bh == old_bh) { 667 ea_bdebug(new_bh, "keeping this block"); 668 } else { 669 /* The old block is released after updating 670 the inode. */ 671 ea_bdebug(new_bh, "reusing block"); 672 673 error = dquot_alloc_block(inode, 1); 674 if (error) { 675 unlock_buffer(new_bh); 676 goto cleanup; 677 } 678 le32_add_cpu(&HDR(new_bh)->h_refcount, 1); 679 ea_bdebug(new_bh, "refcount now=%d", 680 le32_to_cpu(HDR(new_bh)->h_refcount)); 681 } 682 unlock_buffer(new_bh); 683 } else if (old_bh && header == HDR(old_bh)) { 684 /* Keep this block. No need to lock the block as we 685 don't need to change the reference count. */ 686 new_bh = old_bh; 687 get_bh(new_bh); 688 ext2_xattr_cache_insert(ea_block_cache, new_bh); 689 } else { 690 /* We need to allocate a new block */ 691 ext2_fsblk_t goal = ext2_group_first_block_no(sb, 692 EXT2_I(inode)->i_block_group); 693 int block = ext2_new_block(inode, goal, &error); 694 if (error) 695 goto cleanup; 696 ea_idebug(inode, "creating block %d", block); 697 698 new_bh = sb_getblk(sb, block); 699 if (unlikely(!new_bh)) { 700 ext2_free_blocks(inode, block, 1); 701 mark_inode_dirty(inode); 702 error = -ENOMEM; 703 goto cleanup; 704 } 705 lock_buffer(new_bh); 706 memcpy(new_bh->b_data, header, new_bh->b_size); 707 set_buffer_uptodate(new_bh); 708 unlock_buffer(new_bh); 709 ext2_xattr_cache_insert(ea_block_cache, new_bh); 710 711 ext2_xattr_update_super_block(sb); 712 } 713 mark_buffer_dirty(new_bh); 714 if (IS_SYNC(inode)) { 715 sync_dirty_buffer(new_bh); 716 error = -EIO; 717 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 718 goto cleanup; 719 } 720 } 721 722 /* Update the inode. */ 723 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 724 inode->i_ctime = current_time(inode); 725 if (IS_SYNC(inode)) { 726 error = sync_inode_metadata(inode, 1); 727 /* In case sync failed due to ENOSPC the inode was actually 728 * written (only some dirty data were not) so we just proceed 729 * as if nothing happened and cleanup the unused block */ 730 if (error && error != -ENOSPC) { 731 if (new_bh && new_bh != old_bh) { 732 dquot_free_block_nodirty(inode, 1); 733 mark_inode_dirty(inode); 734 } 735 goto cleanup; 736 } 737 } else 738 mark_inode_dirty(inode); 739 740 error = 0; 741 if (old_bh && old_bh != new_bh) { 742 /* 743 * If there was an old block and we are no longer using it, 744 * release the old block. 745 */ 746 lock_buffer(old_bh); 747 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { 748 __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash); 749 750 /* 751 * This must happen under buffer lock for 752 * ext2_xattr_set2() to reliably detect freed block 753 */ 754 mb_cache_entry_delete(ea_block_cache, hash, 755 old_bh->b_blocknr); 756 /* Free the old block. */ 757 ea_bdebug(old_bh, "freeing"); 758 ext2_free_blocks(inode, old_bh->b_blocknr, 1); 759 mark_inode_dirty(inode); 760 /* We let our caller release old_bh, so we 761 * need to duplicate the buffer before. */ 762 get_bh(old_bh); 763 bforget(old_bh); 764 } else { 765 /* Decrement the refcount only. */ 766 le32_add_cpu(&HDR(old_bh)->h_refcount, -1); 767 dquot_free_block_nodirty(inode, 1); 768 mark_inode_dirty(inode); 769 mark_buffer_dirty(old_bh); 770 ea_bdebug(old_bh, "refcount now=%d", 771 le32_to_cpu(HDR(old_bh)->h_refcount)); 772 } 773 unlock_buffer(old_bh); 774 } 775 776 cleanup: 777 brelse(new_bh); 778 779 return error; 780 } 781 782 /* 783 * ext2_xattr_delete_inode() 784 * 785 * Free extended attribute resources associated with this inode. This 786 * is called immediately before an inode is freed. 787 */ 788 void 789 ext2_xattr_delete_inode(struct inode *inode) 790 { 791 struct buffer_head *bh = NULL; 792 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb); 793 794 down_write(&EXT2_I(inode)->xattr_sem); 795 if (!EXT2_I(inode)->i_file_acl) 796 goto cleanup; 797 798 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 0)) { 799 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 800 "inode %ld: xattr block %d is out of data blocks range", 801 inode->i_ino, EXT2_I(inode)->i_file_acl); 802 goto cleanup; 803 } 804 805 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 806 if (!bh) { 807 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 808 "inode %ld: block %d read error", inode->i_ino, 809 EXT2_I(inode)->i_file_acl); 810 goto cleanup; 811 } 812 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 813 if (!ext2_xattr_header_valid(HDR(bh))) { 814 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 815 "inode %ld: bad block %d", inode->i_ino, 816 EXT2_I(inode)->i_file_acl); 817 goto cleanup; 818 } 819 lock_buffer(bh); 820 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 821 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 822 823 /* 824 * This must happen under buffer lock for ext2_xattr_set2() to 825 * reliably detect freed block 826 */ 827 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, 828 bh->b_blocknr); 829 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); 830 get_bh(bh); 831 bforget(bh); 832 unlock_buffer(bh); 833 } else { 834 le32_add_cpu(&HDR(bh)->h_refcount, -1); 835 ea_bdebug(bh, "refcount now=%d", 836 le32_to_cpu(HDR(bh)->h_refcount)); 837 unlock_buffer(bh); 838 mark_buffer_dirty(bh); 839 if (IS_SYNC(inode)) 840 sync_dirty_buffer(bh); 841 dquot_free_block_nodirty(inode, 1); 842 } 843 EXT2_I(inode)->i_file_acl = 0; 844 845 cleanup: 846 brelse(bh); 847 up_write(&EXT2_I(inode)->xattr_sem); 848 } 849 850 /* 851 * ext2_xattr_cache_insert() 852 * 853 * Create a new entry in the extended attribute cache, and insert 854 * it unless such an entry is already in the cache. 855 * 856 * Returns 0, or a negative error number on failure. 857 */ 858 static int 859 ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh) 860 { 861 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 862 int error; 863 864 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, 865 true); 866 if (error) { 867 if (error == -EBUSY) { 868 ea_bdebug(bh, "already in cache (%d cache entries)", 869 atomic_read(&ext2_xattr_cache->c_entry_count)); 870 error = 0; 871 } 872 } else 873 ea_bdebug(bh, "inserting [%x]", (int)hash); 874 return error; 875 } 876 877 /* 878 * ext2_xattr_cmp() 879 * 880 * Compare two extended attribute blocks for equality. 881 * 882 * Returns 0 if the blocks are equal, 1 if they differ, and 883 * a negative error number on errors. 884 */ 885 static int 886 ext2_xattr_cmp(struct ext2_xattr_header *header1, 887 struct ext2_xattr_header *header2) 888 { 889 struct ext2_xattr_entry *entry1, *entry2; 890 891 entry1 = ENTRY(header1+1); 892 entry2 = ENTRY(header2+1); 893 while (!IS_LAST_ENTRY(entry1)) { 894 if (IS_LAST_ENTRY(entry2)) 895 return 1; 896 if (entry1->e_hash != entry2->e_hash || 897 entry1->e_name_index != entry2->e_name_index || 898 entry1->e_name_len != entry2->e_name_len || 899 entry1->e_value_size != entry2->e_value_size || 900 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 901 return 1; 902 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 903 return -EIO; 904 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 905 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 906 le32_to_cpu(entry1->e_value_size))) 907 return 1; 908 909 entry1 = EXT2_XATTR_NEXT(entry1); 910 entry2 = EXT2_XATTR_NEXT(entry2); 911 } 912 if (!IS_LAST_ENTRY(entry2)) 913 return 1; 914 return 0; 915 } 916 917 /* 918 * ext2_xattr_cache_find() 919 * 920 * Find an identical extended attribute block. 921 * 922 * Returns a locked buffer head to the block found, or NULL if such 923 * a block was not found or an error occurred. 924 */ 925 static struct buffer_head * 926 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 927 { 928 __u32 hash = le32_to_cpu(header->h_hash); 929 struct mb_cache_entry *ce; 930 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 931 932 if (!header->h_hash) 933 return NULL; /* never share */ 934 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 935 again: 936 ce = mb_cache_entry_find_first(ea_block_cache, hash); 937 while (ce) { 938 struct buffer_head *bh; 939 940 bh = sb_bread(inode->i_sb, ce->e_value); 941 if (!bh) { 942 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 943 "inode %ld: block %ld read error", 944 inode->i_ino, (unsigned long) ce->e_value); 945 } else { 946 lock_buffer(bh); 947 /* 948 * We have to be careful about races with freeing or 949 * rehashing of xattr block. Once we hold buffer lock 950 * xattr block's state is stable so we can check 951 * whether the block got freed / rehashed or not. 952 * Since we unhash mbcache entry under buffer lock when 953 * freeing / rehashing xattr block, checking whether 954 * entry is still hashed is reliable. 955 */ 956 if (hlist_bl_unhashed(&ce->e_hash_list)) { 957 mb_cache_entry_put(ea_block_cache, ce); 958 unlock_buffer(bh); 959 brelse(bh); 960 goto again; 961 } else if (le32_to_cpu(HDR(bh)->h_refcount) > 962 EXT2_XATTR_REFCOUNT_MAX) { 963 ea_idebug(inode, "block %ld refcount %d>%d", 964 (unsigned long) ce->e_value, 965 le32_to_cpu(HDR(bh)->h_refcount), 966 EXT2_XATTR_REFCOUNT_MAX); 967 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 968 ea_bdebug(bh, "b_count=%d", 969 atomic_read(&(bh->b_count))); 970 mb_cache_entry_touch(ea_block_cache, ce); 971 mb_cache_entry_put(ea_block_cache, ce); 972 return bh; 973 } 974 unlock_buffer(bh); 975 brelse(bh); 976 } 977 ce = mb_cache_entry_find_next(ea_block_cache, ce); 978 } 979 return NULL; 980 } 981 982 #define NAME_HASH_SHIFT 5 983 #define VALUE_HASH_SHIFT 16 984 985 /* 986 * ext2_xattr_hash_entry() 987 * 988 * Compute the hash of an extended attribute. 989 */ 990 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 991 struct ext2_xattr_entry *entry) 992 { 993 __u32 hash = 0; 994 char *name = entry->e_name; 995 int n; 996 997 for (n=0; n < entry->e_name_len; n++) { 998 hash = (hash << NAME_HASH_SHIFT) ^ 999 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 1000 *name++; 1001 } 1002 1003 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 1004 __le32 *value = (__le32 *)((char *)header + 1005 le16_to_cpu(entry->e_value_offs)); 1006 for (n = (le32_to_cpu(entry->e_value_size) + 1007 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 1008 hash = (hash << VALUE_HASH_SHIFT) ^ 1009 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 1010 le32_to_cpu(*value++); 1011 } 1012 } 1013 entry->e_hash = cpu_to_le32(hash); 1014 } 1015 1016 #undef NAME_HASH_SHIFT 1017 #undef VALUE_HASH_SHIFT 1018 1019 #define BLOCK_HASH_SHIFT 16 1020 1021 /* 1022 * ext2_xattr_rehash() 1023 * 1024 * Re-compute the extended attribute hash value after an entry has changed. 1025 */ 1026 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 1027 struct ext2_xattr_entry *entry) 1028 { 1029 struct ext2_xattr_entry *here; 1030 __u32 hash = 0; 1031 1032 ext2_xattr_hash_entry(header, entry); 1033 here = ENTRY(header+1); 1034 while (!IS_LAST_ENTRY(here)) { 1035 if (!here->e_hash) { 1036 /* Block is not shared if an entry's hash value == 0 */ 1037 hash = 0; 1038 break; 1039 } 1040 hash = (hash << BLOCK_HASH_SHIFT) ^ 1041 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1042 le32_to_cpu(here->e_hash); 1043 here = EXT2_XATTR_NEXT(here); 1044 } 1045 header->h_hash = cpu_to_le32(hash); 1046 } 1047 1048 #undef BLOCK_HASH_SHIFT 1049 1050 #define HASH_BUCKET_BITS 10 1051 1052 struct mb_cache *ext2_xattr_create_cache(void) 1053 { 1054 return mb_cache_create(HASH_BUCKET_BITS); 1055 } 1056 1057 void ext2_xattr_destroy_cache(struct mb_cache *cache) 1058 { 1059 if (cache) 1060 mb_cache_destroy(cache); 1061 } 1062