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/printk.h> 60 #include <linux/slab.h> 61 #include <linux/mbcache.h> 62 #include <linux/quotaops.h> 63 #include <linux/rwsem.h> 64 #include <linux/security.h> 65 #include "ext2.h" 66 #include "xattr.h" 67 #include "acl.h" 68 69 #define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data)) 70 #define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr)) 71 #define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1) 72 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) 73 74 #ifdef EXT2_XATTR_DEBUG 75 # define ea_idebug(inode, f...) do { \ 76 printk(KERN_DEBUG "inode %s:%ld: ", \ 77 inode->i_sb->s_id, inode->i_ino); \ 78 printk(f); \ 79 printk("\n"); \ 80 } while (0) 81 # define ea_bdebug(bh, f...) do { \ 82 printk(KERN_DEBUG "block %pg:%lu: ", \ 83 bh->b_bdev, (unsigned long) bh->b_blocknr); \ 84 printk(f); \ 85 printk("\n"); \ 86 } while (0) 87 #else 88 # define ea_idebug(inode, f...) no_printk(f) 89 # define ea_bdebug(bh, f...) no_printk(f) 90 #endif 91 92 static int ext2_xattr_set2(struct inode *, struct buffer_head *, 93 struct ext2_xattr_header *); 94 95 static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *); 96 static struct buffer_head *ext2_xattr_cache_find(struct inode *, 97 struct ext2_xattr_header *); 98 static void ext2_xattr_rehash(struct ext2_xattr_header *, 99 struct ext2_xattr_entry *); 100 101 static const struct xattr_handler *ext2_xattr_handler_map[] = { 102 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler, 103 #ifdef CONFIG_EXT2_FS_POSIX_ACL 104 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler, 105 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler, 106 #endif 107 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler, 108 #ifdef CONFIG_EXT2_FS_SECURITY 109 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler, 110 #endif 111 }; 112 113 const struct xattr_handler *ext2_xattr_handlers[] = { 114 &ext2_xattr_user_handler, 115 &ext2_xattr_trusted_handler, 116 #ifdef CONFIG_EXT2_FS_POSIX_ACL 117 &posix_acl_access_xattr_handler, 118 &posix_acl_default_xattr_handler, 119 #endif 120 #ifdef CONFIG_EXT2_FS_SECURITY 121 &ext2_xattr_security_handler, 122 #endif 123 NULL 124 }; 125 126 #define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache) 127 128 static inline const struct xattr_handler * 129 ext2_xattr_handler(int name_index) 130 { 131 const struct xattr_handler *handler = NULL; 132 133 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map)) 134 handler = ext2_xattr_handler_map[name_index]; 135 return handler; 136 } 137 138 static bool 139 ext2_xattr_header_valid(struct ext2_xattr_header *header) 140 { 141 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 142 header->h_blocks != cpu_to_le32(1)) 143 return false; 144 145 return true; 146 } 147 148 static bool 149 ext2_xattr_entry_valid(struct ext2_xattr_entry *entry, 150 char *end, size_t end_offs) 151 { 152 struct ext2_xattr_entry *next; 153 size_t size; 154 155 next = EXT2_XATTR_NEXT(entry); 156 if ((char *)next >= end) 157 return false; 158 159 if (entry->e_value_block != 0) 160 return false; 161 162 size = le32_to_cpu(entry->e_value_size); 163 if (size > end_offs || 164 le16_to_cpu(entry->e_value_offs) + size > end_offs) 165 return false; 166 167 return true; 168 } 169 170 static int 171 ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name, 172 struct ext2_xattr_entry *entry) 173 { 174 int cmp; 175 176 cmp = name_index - entry->e_name_index; 177 if (!cmp) 178 cmp = name_len - entry->e_name_len; 179 if (!cmp) 180 cmp = memcmp(name, entry->e_name, name_len); 181 182 return cmp; 183 } 184 185 /* 186 * ext2_xattr_get() 187 * 188 * Copy an extended attribute into the buffer 189 * provided, or compute the buffer size required. 190 * Buffer is NULL to compute the size of the buffer required. 191 * 192 * Returns a negative error number on failure, or the number of bytes 193 * used / required on success. 194 */ 195 int 196 ext2_xattr_get(struct inode *inode, int name_index, const char *name, 197 void *buffer, size_t buffer_size) 198 { 199 struct buffer_head *bh = NULL; 200 struct ext2_xattr_entry *entry; 201 size_t name_len, size; 202 char *end; 203 int error, not_found; 204 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 205 206 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", 207 name_index, name, buffer, (long)buffer_size); 208 209 if (name == NULL) 210 return -EINVAL; 211 name_len = strlen(name); 212 if (name_len > 255) 213 return -ERANGE; 214 215 down_read(&EXT2_I(inode)->xattr_sem); 216 error = -ENODATA; 217 if (!EXT2_I(inode)->i_file_acl) 218 goto cleanup; 219 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 220 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 221 error = -EIO; 222 if (!bh) 223 goto cleanup; 224 ea_bdebug(bh, "b_count=%d, refcount=%d", 225 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 226 end = bh->b_data + bh->b_size; 227 if (!ext2_xattr_header_valid(HDR(bh))) { 228 bad_block: 229 ext2_error(inode->i_sb, "ext2_xattr_get", 230 "inode %ld: bad block %d", inode->i_ino, 231 EXT2_I(inode)->i_file_acl); 232 error = -EIO; 233 goto cleanup; 234 } 235 236 /* find named attribute */ 237 entry = FIRST_ENTRY(bh); 238 while (!IS_LAST_ENTRY(entry)) { 239 if (!ext2_xattr_entry_valid(entry, end, 240 inode->i_sb->s_blocksize)) 241 goto bad_block; 242 243 not_found = ext2_xattr_cmp_entry(name_index, name_len, name, 244 entry); 245 if (!not_found) 246 goto found; 247 if (not_found < 0) 248 break; 249 250 entry = EXT2_XATTR_NEXT(entry); 251 } 252 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 253 ea_idebug(inode, "cache insert failed"); 254 error = -ENODATA; 255 goto cleanup; 256 found: 257 size = le32_to_cpu(entry->e_value_size); 258 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 259 ea_idebug(inode, "cache insert failed"); 260 if (buffer) { 261 error = -ERANGE; 262 if (size > buffer_size) 263 goto cleanup; 264 /* return value of attribute */ 265 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), 266 size); 267 } 268 error = size; 269 270 cleanup: 271 brelse(bh); 272 up_read(&EXT2_I(inode)->xattr_sem); 273 274 return error; 275 } 276 277 /* 278 * ext2_xattr_list() 279 * 280 * Copy a list of attribute names into the buffer 281 * provided, or compute the buffer size required. 282 * Buffer is NULL to compute the size of the buffer required. 283 * 284 * Returns a negative error number on failure, or the number of bytes 285 * used / required on success. 286 */ 287 static int 288 ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) 289 { 290 struct inode *inode = d_inode(dentry); 291 struct buffer_head *bh = NULL; 292 struct ext2_xattr_entry *entry; 293 char *end; 294 size_t rest = buffer_size; 295 int error; 296 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 297 298 ea_idebug(inode, "buffer=%p, buffer_size=%ld", 299 buffer, (long)buffer_size); 300 301 down_read(&EXT2_I(inode)->xattr_sem); 302 error = 0; 303 if (!EXT2_I(inode)->i_file_acl) 304 goto cleanup; 305 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 306 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 307 error = -EIO; 308 if (!bh) 309 goto cleanup; 310 ea_bdebug(bh, "b_count=%d, refcount=%d", 311 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 312 end = bh->b_data + bh->b_size; 313 if (!ext2_xattr_header_valid(HDR(bh))) { 314 bad_block: 315 ext2_error(inode->i_sb, "ext2_xattr_list", 316 "inode %ld: bad block %d", inode->i_ino, 317 EXT2_I(inode)->i_file_acl); 318 error = -EIO; 319 goto cleanup; 320 } 321 322 /* check the on-disk data structure */ 323 entry = FIRST_ENTRY(bh); 324 while (!IS_LAST_ENTRY(entry)) { 325 if (!ext2_xattr_entry_valid(entry, end, 326 inode->i_sb->s_blocksize)) 327 goto bad_block; 328 entry = EXT2_XATTR_NEXT(entry); 329 } 330 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 331 ea_idebug(inode, "cache insert failed"); 332 333 /* list the attribute names */ 334 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); 335 entry = EXT2_XATTR_NEXT(entry)) { 336 const struct xattr_handler *handler = 337 ext2_xattr_handler(entry->e_name_index); 338 339 if (handler && (!handler->list || handler->list(dentry))) { 340 const char *prefix = handler->prefix ?: handler->name; 341 size_t prefix_len = strlen(prefix); 342 size_t size = prefix_len + entry->e_name_len + 1; 343 344 if (buffer) { 345 if (size > rest) { 346 error = -ERANGE; 347 goto cleanup; 348 } 349 memcpy(buffer, prefix, prefix_len); 350 buffer += prefix_len; 351 memcpy(buffer, entry->e_name, entry->e_name_len); 352 buffer += entry->e_name_len; 353 *buffer++ = 0; 354 } 355 rest -= size; 356 } 357 } 358 error = buffer_size - rest; /* total size */ 359 360 cleanup: 361 brelse(bh); 362 up_read(&EXT2_I(inode)->xattr_sem); 363 364 return error; 365 } 366 367 /* 368 * Inode operation listxattr() 369 * 370 * d_inode(dentry)->i_mutex: don't care 371 */ 372 ssize_t 373 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) 374 { 375 return ext2_xattr_list(dentry, buffer, size); 376 } 377 378 /* 379 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is 380 * not set, set it. 381 */ 382 static void ext2_xattr_update_super_block(struct super_block *sb) 383 { 384 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR)) 385 return; 386 387 spin_lock(&EXT2_SB(sb)->s_lock); 388 ext2_update_dynamic_rev(sb); 389 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR); 390 spin_unlock(&EXT2_SB(sb)->s_lock); 391 mark_buffer_dirty(EXT2_SB(sb)->s_sbh); 392 } 393 394 /* 395 * ext2_xattr_set() 396 * 397 * Create, replace or remove an extended attribute for this inode. Value 398 * is NULL to remove an existing extended attribute, and non-NULL to 399 * either replace an existing extended attribute, or create a new extended 400 * attribute. The flags XATTR_REPLACE and XATTR_CREATE 401 * specify that an extended attribute must exist and must not exist 402 * previous to the call, respectively. 403 * 404 * Returns 0, or a negative error number on failure. 405 */ 406 int 407 ext2_xattr_set(struct inode *inode, int name_index, const char *name, 408 const void *value, size_t value_len, int flags) 409 { 410 struct super_block *sb = inode->i_sb; 411 struct buffer_head *bh = NULL; 412 struct ext2_xattr_header *header = NULL; 413 struct ext2_xattr_entry *here = NULL, *last = NULL; 414 size_t name_len, free, min_offs = sb->s_blocksize; 415 int not_found = 1, error; 416 char *end; 417 418 /* 419 * header -- Points either into bh, or to a temporarily 420 * allocated buffer. 421 * here -- The named entry found, or the place for inserting, within 422 * the block pointed to by header. 423 * last -- Points right after the last named entry within the block 424 * pointed to by header. 425 * min_offs -- The offset of the first value (values are aligned 426 * towards the end of the block). 427 * end -- Points right after the block pointed to by header. 428 */ 429 430 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", 431 name_index, name, value, (long)value_len); 432 433 if (value == NULL) 434 value_len = 0; 435 if (name == NULL) 436 return -EINVAL; 437 name_len = strlen(name); 438 if (name_len > 255 || value_len > sb->s_blocksize) 439 return -ERANGE; 440 down_write(&EXT2_I(inode)->xattr_sem); 441 if (EXT2_I(inode)->i_file_acl) { 442 /* The inode already has an extended attribute block. */ 443 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 444 error = -EIO; 445 if (!bh) 446 goto cleanup; 447 ea_bdebug(bh, "b_count=%d, refcount=%d", 448 atomic_read(&(bh->b_count)), 449 le32_to_cpu(HDR(bh)->h_refcount)); 450 header = HDR(bh); 451 end = bh->b_data + bh->b_size; 452 if (!ext2_xattr_header_valid(header)) { 453 bad_block: 454 ext2_error(sb, "ext2_xattr_set", 455 "inode %ld: bad block %d", inode->i_ino, 456 EXT2_I(inode)->i_file_acl); 457 error = -EIO; 458 goto cleanup; 459 } 460 /* 461 * Find the named attribute. If not found, 'here' will point 462 * to entry where the new attribute should be inserted to 463 * maintain sorting. 464 */ 465 last = FIRST_ENTRY(bh); 466 while (!IS_LAST_ENTRY(last)) { 467 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize)) 468 goto bad_block; 469 if (last->e_value_size) { 470 size_t offs = le16_to_cpu(last->e_value_offs); 471 if (offs < min_offs) 472 min_offs = offs; 473 } 474 if (not_found > 0) { 475 not_found = ext2_xattr_cmp_entry(name_index, 476 name_len, 477 name, last); 478 if (not_found <= 0) 479 here = last; 480 } 481 last = EXT2_XATTR_NEXT(last); 482 } 483 if (not_found > 0) 484 here = last; 485 486 /* Check whether we have enough space left. */ 487 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 488 } else { 489 /* We will use a new extended attribute block. */ 490 free = sb->s_blocksize - 491 sizeof(struct ext2_xattr_header) - sizeof(__u32); 492 } 493 494 if (not_found) { 495 /* Request to remove a nonexistent attribute? */ 496 error = -ENODATA; 497 if (flags & XATTR_REPLACE) 498 goto cleanup; 499 error = 0; 500 if (value == NULL) 501 goto cleanup; 502 } else { 503 /* Request to create an existing attribute? */ 504 error = -EEXIST; 505 if (flags & XATTR_CREATE) 506 goto cleanup; 507 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size)); 508 free += EXT2_XATTR_LEN(name_len); 509 } 510 error = -ENOSPC; 511 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 512 goto cleanup; 513 514 /* Here we know that we can set the new attribute. */ 515 516 if (header) { 517 /* assert(header == HDR(bh)); */ 518 lock_buffer(bh); 519 if (header->h_refcount == cpu_to_le32(1)) { 520 __u32 hash = le32_to_cpu(header->h_hash); 521 522 ea_bdebug(bh, "modifying in-place"); 523 /* 524 * This must happen under buffer lock for 525 * ext2_xattr_set2() to reliably detect modified block 526 */ 527 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, 528 bh->b_blocknr); 529 530 /* keep the buffer locked while modifying it. */ 531 } else { 532 int offset; 533 534 unlock_buffer(bh); 535 ea_bdebug(bh, "cloning"); 536 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL); 537 error = -ENOMEM; 538 if (header == NULL) 539 goto cleanup; 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 min_offs += size; 592 593 /* Adjust all value offsets. */ 594 last = ENTRY(header+1); 595 while (!IS_LAST_ENTRY(last)) { 596 size_t o = le16_to_cpu(last->e_value_offs); 597 if (o < offs) 598 last->e_value_offs = 599 cpu_to_le16(o + size); 600 last = EXT2_XATTR_NEXT(last); 601 } 602 603 here->e_value_offs = 0; 604 } 605 if (value == NULL) { 606 /* Remove the old name. */ 607 size_t size = EXT2_XATTR_LEN(name_len); 608 last = ENTRY((char *)last - size); 609 memmove(here, (char*)here + size, 610 (char*)last - (char*)here); 611 memset(last, 0, size); 612 } 613 } 614 615 if (value != NULL) { 616 /* Insert the new value. */ 617 here->e_value_size = cpu_to_le32(value_len); 618 if (value_len) { 619 size_t size = EXT2_XATTR_SIZE(value_len); 620 char *val = (char *)header + min_offs - size; 621 here->e_value_offs = 622 cpu_to_le16((char *)val - (char *)header); 623 memset(val + size - EXT2_XATTR_PAD, 0, 624 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 625 memcpy(val, value, value_len); 626 } 627 } 628 629 skip_replace: 630 if (IS_LAST_ENTRY(ENTRY(header+1))) { 631 /* This block is now empty. */ 632 if (bh && header == HDR(bh)) 633 unlock_buffer(bh); /* we were modifying in-place. */ 634 error = ext2_xattr_set2(inode, bh, NULL); 635 } else { 636 ext2_xattr_rehash(header, here); 637 if (bh && header == HDR(bh)) 638 unlock_buffer(bh); /* we were modifying in-place. */ 639 error = ext2_xattr_set2(inode, bh, header); 640 } 641 642 cleanup: 643 if (!(bh && header == HDR(bh))) 644 kfree(header); 645 brelse(bh); 646 up_write(&EXT2_I(inode)->xattr_sem); 647 648 return error; 649 } 650 651 /* 652 * Second half of ext2_xattr_set(): Update the file system. 653 */ 654 static int 655 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 656 struct ext2_xattr_header *header) 657 { 658 struct super_block *sb = inode->i_sb; 659 struct buffer_head *new_bh = NULL; 660 int error; 661 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 662 663 if (header) { 664 new_bh = ext2_xattr_cache_find(inode, header); 665 if (new_bh) { 666 /* We found an identical block in the cache. */ 667 if (new_bh == old_bh) { 668 ea_bdebug(new_bh, "keeping this block"); 669 } else { 670 /* The old block is released after updating 671 the inode. */ 672 ea_bdebug(new_bh, "reusing block"); 673 674 error = dquot_alloc_block(inode, 1); 675 if (error) { 676 unlock_buffer(new_bh); 677 goto cleanup; 678 } 679 le32_add_cpu(&HDR(new_bh)->h_refcount, 1); 680 ea_bdebug(new_bh, "refcount now=%d", 681 le32_to_cpu(HDR(new_bh)->h_refcount)); 682 } 683 unlock_buffer(new_bh); 684 } else if (old_bh && header == HDR(old_bh)) { 685 /* Keep this block. No need to lock the block as we 686 don't need to change the reference count. */ 687 new_bh = old_bh; 688 get_bh(new_bh); 689 ext2_xattr_cache_insert(ea_block_cache, new_bh); 690 } else { 691 /* We need to allocate a new block */ 692 ext2_fsblk_t goal = ext2_group_first_block_no(sb, 693 EXT2_I(inode)->i_block_group); 694 int block = ext2_new_block(inode, goal, &error); 695 if (error) 696 goto cleanup; 697 ea_idebug(inode, "creating block %d", block); 698 699 new_bh = sb_getblk(sb, block); 700 if (unlikely(!new_bh)) { 701 ext2_free_blocks(inode, block, 1); 702 mark_inode_dirty(inode); 703 error = -ENOMEM; 704 goto cleanup; 705 } 706 lock_buffer(new_bh); 707 memcpy(new_bh->b_data, header, new_bh->b_size); 708 set_buffer_uptodate(new_bh); 709 unlock_buffer(new_bh); 710 ext2_xattr_cache_insert(ea_block_cache, new_bh); 711 712 ext2_xattr_update_super_block(sb); 713 } 714 mark_buffer_dirty(new_bh); 715 if (IS_SYNC(inode)) { 716 sync_dirty_buffer(new_bh); 717 error = -EIO; 718 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 719 goto cleanup; 720 } 721 } 722 723 /* Update the inode. */ 724 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 725 inode->i_ctime = current_time(inode); 726 if (IS_SYNC(inode)) { 727 error = sync_inode_metadata(inode, 1); 728 /* In case sync failed due to ENOSPC the inode was actually 729 * written (only some dirty data were not) so we just proceed 730 * as if nothing happened and cleanup the unused block */ 731 if (error && error != -ENOSPC) { 732 if (new_bh && new_bh != old_bh) { 733 dquot_free_block_nodirty(inode, 1); 734 mark_inode_dirty(inode); 735 } 736 goto cleanup; 737 } 738 } else 739 mark_inode_dirty(inode); 740 741 error = 0; 742 if (old_bh && old_bh != new_bh) { 743 /* 744 * If there was an old block and we are no longer using it, 745 * release the old block. 746 */ 747 lock_buffer(old_bh); 748 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { 749 __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash); 750 751 /* 752 * This must happen under buffer lock for 753 * ext2_xattr_set2() to reliably detect freed block 754 */ 755 mb_cache_entry_delete(ea_block_cache, hash, 756 old_bh->b_blocknr); 757 /* Free the old block. */ 758 ea_bdebug(old_bh, "freeing"); 759 ext2_free_blocks(inode, old_bh->b_blocknr, 1); 760 mark_inode_dirty(inode); 761 /* We let our caller release old_bh, so we 762 * need to duplicate the buffer before. */ 763 get_bh(old_bh); 764 bforget(old_bh); 765 } else { 766 /* Decrement the refcount only. */ 767 le32_add_cpu(&HDR(old_bh)->h_refcount, -1); 768 dquot_free_block_nodirty(inode, 1); 769 mark_inode_dirty(inode); 770 mark_buffer_dirty(old_bh); 771 ea_bdebug(old_bh, "refcount now=%d", 772 le32_to_cpu(HDR(old_bh)->h_refcount)); 773 } 774 unlock_buffer(old_bh); 775 } 776 777 cleanup: 778 brelse(new_bh); 779 780 return error; 781 } 782 783 /* 784 * ext2_xattr_delete_inode() 785 * 786 * Free extended attribute resources associated with this inode. This 787 * is called immediately before an inode is freed. 788 */ 789 void 790 ext2_xattr_delete_inode(struct inode *inode) 791 { 792 struct buffer_head *bh = NULL; 793 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb); 794 795 /* 796 * We are the only ones holding inode reference. The xattr_sem should 797 * better be unlocked! We could as well just not acquire xattr_sem at 798 * all but this makes the code more futureproof. OTOH we need trylock 799 * here to avoid false-positive warning from lockdep about reclaim 800 * circular dependency. 801 */ 802 if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem))) 803 return; 804 if (!EXT2_I(inode)->i_file_acl) 805 goto cleanup; 806 807 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) { 808 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 809 "inode %ld: xattr block %d is out of data blocks range", 810 inode->i_ino, EXT2_I(inode)->i_file_acl); 811 goto cleanup; 812 } 813 814 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 815 if (!bh) { 816 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 817 "inode %ld: block %d read error", inode->i_ino, 818 EXT2_I(inode)->i_file_acl); 819 goto cleanup; 820 } 821 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 822 if (!ext2_xattr_header_valid(HDR(bh))) { 823 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 824 "inode %ld: bad block %d", inode->i_ino, 825 EXT2_I(inode)->i_file_acl); 826 goto cleanup; 827 } 828 lock_buffer(bh); 829 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 830 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 831 832 /* 833 * This must happen under buffer lock for ext2_xattr_set2() to 834 * reliably detect freed block 835 */ 836 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, 837 bh->b_blocknr); 838 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); 839 get_bh(bh); 840 bforget(bh); 841 unlock_buffer(bh); 842 } else { 843 le32_add_cpu(&HDR(bh)->h_refcount, -1); 844 ea_bdebug(bh, "refcount now=%d", 845 le32_to_cpu(HDR(bh)->h_refcount)); 846 unlock_buffer(bh); 847 mark_buffer_dirty(bh); 848 if (IS_SYNC(inode)) 849 sync_dirty_buffer(bh); 850 dquot_free_block_nodirty(inode, 1); 851 } 852 EXT2_I(inode)->i_file_acl = 0; 853 854 cleanup: 855 brelse(bh); 856 up_write(&EXT2_I(inode)->xattr_sem); 857 } 858 859 /* 860 * ext2_xattr_cache_insert() 861 * 862 * Create a new entry in the extended attribute cache, and insert 863 * it unless such an entry is already in the cache. 864 * 865 * Returns 0, or a negative error number on failure. 866 */ 867 static int 868 ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh) 869 { 870 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 871 int error; 872 873 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, 874 true); 875 if (error) { 876 if (error == -EBUSY) { 877 ea_bdebug(bh, "already in cache"); 878 error = 0; 879 } 880 } else 881 ea_bdebug(bh, "inserting [%x]", (int)hash); 882 return error; 883 } 884 885 /* 886 * ext2_xattr_cmp() 887 * 888 * Compare two extended attribute blocks for equality. 889 * 890 * Returns 0 if the blocks are equal, 1 if they differ, and 891 * a negative error number on errors. 892 */ 893 static int 894 ext2_xattr_cmp(struct ext2_xattr_header *header1, 895 struct ext2_xattr_header *header2) 896 { 897 struct ext2_xattr_entry *entry1, *entry2; 898 899 entry1 = ENTRY(header1+1); 900 entry2 = ENTRY(header2+1); 901 while (!IS_LAST_ENTRY(entry1)) { 902 if (IS_LAST_ENTRY(entry2)) 903 return 1; 904 if (entry1->e_hash != entry2->e_hash || 905 entry1->e_name_index != entry2->e_name_index || 906 entry1->e_name_len != entry2->e_name_len || 907 entry1->e_value_size != entry2->e_value_size || 908 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 909 return 1; 910 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 911 return -EIO; 912 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 913 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 914 le32_to_cpu(entry1->e_value_size))) 915 return 1; 916 917 entry1 = EXT2_XATTR_NEXT(entry1); 918 entry2 = EXT2_XATTR_NEXT(entry2); 919 } 920 if (!IS_LAST_ENTRY(entry2)) 921 return 1; 922 return 0; 923 } 924 925 /* 926 * ext2_xattr_cache_find() 927 * 928 * Find an identical extended attribute block. 929 * 930 * Returns a locked buffer head to the block found, or NULL if such 931 * a block was not found or an error occurred. 932 */ 933 static struct buffer_head * 934 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 935 { 936 __u32 hash = le32_to_cpu(header->h_hash); 937 struct mb_cache_entry *ce; 938 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 939 940 if (!header->h_hash) 941 return NULL; /* never share */ 942 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 943 again: 944 ce = mb_cache_entry_find_first(ea_block_cache, hash); 945 while (ce) { 946 struct buffer_head *bh; 947 948 bh = sb_bread(inode->i_sb, ce->e_value); 949 if (!bh) { 950 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 951 "inode %ld: block %ld read error", 952 inode->i_ino, (unsigned long) ce->e_value); 953 } else { 954 lock_buffer(bh); 955 /* 956 * We have to be careful about races with freeing or 957 * rehashing of xattr block. Once we hold buffer lock 958 * xattr block's state is stable so we can check 959 * whether the block got freed / rehashed or not. 960 * Since we unhash mbcache entry under buffer lock when 961 * freeing / rehashing xattr block, checking whether 962 * entry is still hashed is reliable. 963 */ 964 if (hlist_bl_unhashed(&ce->e_hash_list)) { 965 mb_cache_entry_put(ea_block_cache, ce); 966 unlock_buffer(bh); 967 brelse(bh); 968 goto again; 969 } else if (le32_to_cpu(HDR(bh)->h_refcount) > 970 EXT2_XATTR_REFCOUNT_MAX) { 971 ea_idebug(inode, "block %ld refcount %d>%d", 972 (unsigned long) ce->e_value, 973 le32_to_cpu(HDR(bh)->h_refcount), 974 EXT2_XATTR_REFCOUNT_MAX); 975 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 976 ea_bdebug(bh, "b_count=%d", 977 atomic_read(&(bh->b_count))); 978 mb_cache_entry_touch(ea_block_cache, ce); 979 mb_cache_entry_put(ea_block_cache, ce); 980 return bh; 981 } 982 unlock_buffer(bh); 983 brelse(bh); 984 } 985 ce = mb_cache_entry_find_next(ea_block_cache, ce); 986 } 987 return NULL; 988 } 989 990 #define NAME_HASH_SHIFT 5 991 #define VALUE_HASH_SHIFT 16 992 993 /* 994 * ext2_xattr_hash_entry() 995 * 996 * Compute the hash of an extended attribute. 997 */ 998 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 999 struct ext2_xattr_entry *entry) 1000 { 1001 __u32 hash = 0; 1002 char *name = entry->e_name; 1003 int n; 1004 1005 for (n=0; n < entry->e_name_len; n++) { 1006 hash = (hash << NAME_HASH_SHIFT) ^ 1007 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 1008 *name++; 1009 } 1010 1011 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 1012 __le32 *value = (__le32 *)((char *)header + 1013 le16_to_cpu(entry->e_value_offs)); 1014 for (n = (le32_to_cpu(entry->e_value_size) + 1015 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 1016 hash = (hash << VALUE_HASH_SHIFT) ^ 1017 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 1018 le32_to_cpu(*value++); 1019 } 1020 } 1021 entry->e_hash = cpu_to_le32(hash); 1022 } 1023 1024 #undef NAME_HASH_SHIFT 1025 #undef VALUE_HASH_SHIFT 1026 1027 #define BLOCK_HASH_SHIFT 16 1028 1029 /* 1030 * ext2_xattr_rehash() 1031 * 1032 * Re-compute the extended attribute hash value after an entry has changed. 1033 */ 1034 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 1035 struct ext2_xattr_entry *entry) 1036 { 1037 struct ext2_xattr_entry *here; 1038 __u32 hash = 0; 1039 1040 ext2_xattr_hash_entry(header, entry); 1041 here = ENTRY(header+1); 1042 while (!IS_LAST_ENTRY(here)) { 1043 if (!here->e_hash) { 1044 /* Block is not shared if an entry's hash value == 0 */ 1045 hash = 0; 1046 break; 1047 } 1048 hash = (hash << BLOCK_HASH_SHIFT) ^ 1049 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1050 le32_to_cpu(here->e_hash); 1051 here = EXT2_XATTR_NEXT(here); 1052 } 1053 header->h_hash = cpu_to_le32(hash); 1054 } 1055 1056 #undef BLOCK_HASH_SHIFT 1057 1058 #define HASH_BUCKET_BITS 10 1059 1060 struct mb_cache *ext2_xattr_create_cache(void) 1061 { 1062 return mb_cache_create(HASH_BUCKET_BITS); 1063 } 1064 1065 void ext2_xattr_destroy_cache(struct mb_cache *cache) 1066 { 1067 if (cache) 1068 mb_cache_destroy(cache); 1069 } 1070