1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2017-2018 HUAWEI, Inc. 4 * https://www.huawei.com/ 5 */ 6 #include <linux/security.h> 7 #include "xattr.h" 8 9 struct xattr_iter { 10 struct super_block *sb; 11 struct page *page; 12 void *kaddr; 13 14 erofs_blk_t blkaddr; 15 unsigned int ofs; 16 }; 17 18 static inline void xattr_iter_end(struct xattr_iter *it, bool atomic) 19 { 20 /* the only user of kunmap() is 'init_inode_xattrs' */ 21 if (!atomic) 22 kunmap(it->page); 23 else 24 kunmap_atomic(it->kaddr); 25 26 unlock_page(it->page); 27 put_page(it->page); 28 } 29 30 static inline void xattr_iter_end_final(struct xattr_iter *it) 31 { 32 if (!it->page) 33 return; 34 35 xattr_iter_end(it, true); 36 } 37 38 static int init_inode_xattrs(struct inode *inode) 39 { 40 struct erofs_inode *const vi = EROFS_I(inode); 41 struct xattr_iter it; 42 unsigned int i; 43 struct erofs_xattr_ibody_header *ih; 44 struct super_block *sb; 45 struct erofs_sb_info *sbi; 46 bool atomic_map; 47 int ret = 0; 48 49 /* the most case is that xattrs of this inode are initialized. */ 50 if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags)) { 51 /* 52 * paired with smp_mb() at the end of the function to ensure 53 * fields will only be observed after the bit is set. 54 */ 55 smp_mb(); 56 return 0; 57 } 58 59 if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_XATTR_BIT, TASK_KILLABLE)) 60 return -ERESTARTSYS; 61 62 /* someone has initialized xattrs for us? */ 63 if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags)) 64 goto out_unlock; 65 66 /* 67 * bypass all xattr operations if ->xattr_isize is not greater than 68 * sizeof(struct erofs_xattr_ibody_header), in detail: 69 * 1) it is not enough to contain erofs_xattr_ibody_header then 70 * ->xattr_isize should be 0 (it means no xattr); 71 * 2) it is just to contain erofs_xattr_ibody_header, which is on-disk 72 * undefined right now (maybe use later with some new sb feature). 73 */ 74 if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) { 75 erofs_err(inode->i_sb, 76 "xattr_isize %d of nid %llu is not supported yet", 77 vi->xattr_isize, vi->nid); 78 ret = -EOPNOTSUPP; 79 goto out_unlock; 80 } else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) { 81 if (vi->xattr_isize) { 82 erofs_err(inode->i_sb, 83 "bogus xattr ibody @ nid %llu", vi->nid); 84 DBG_BUGON(1); 85 ret = -EFSCORRUPTED; 86 goto out_unlock; /* xattr ondisk layout error */ 87 } 88 ret = -ENOATTR; 89 goto out_unlock; 90 } 91 92 sb = inode->i_sb; 93 sbi = EROFS_SB(sb); 94 it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize); 95 it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize); 96 97 it.page = erofs_get_meta_page(sb, it.blkaddr); 98 if (IS_ERR(it.page)) { 99 ret = PTR_ERR(it.page); 100 goto out_unlock; 101 } 102 103 /* read in shared xattr array (non-atomic, see kmalloc below) */ 104 it.kaddr = kmap(it.page); 105 atomic_map = false; 106 107 ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs); 108 109 vi->xattr_shared_count = ih->h_shared_count; 110 vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count, 111 sizeof(uint), GFP_KERNEL); 112 if (!vi->xattr_shared_xattrs) { 113 xattr_iter_end(&it, atomic_map); 114 ret = -ENOMEM; 115 goto out_unlock; 116 } 117 118 /* let's skip ibody header */ 119 it.ofs += sizeof(struct erofs_xattr_ibody_header); 120 121 for (i = 0; i < vi->xattr_shared_count; ++i) { 122 if (it.ofs >= EROFS_BLKSIZ) { 123 /* cannot be unaligned */ 124 DBG_BUGON(it.ofs != EROFS_BLKSIZ); 125 xattr_iter_end(&it, atomic_map); 126 127 it.page = erofs_get_meta_page(sb, ++it.blkaddr); 128 if (IS_ERR(it.page)) { 129 kfree(vi->xattr_shared_xattrs); 130 vi->xattr_shared_xattrs = NULL; 131 ret = PTR_ERR(it.page); 132 goto out_unlock; 133 } 134 135 it.kaddr = kmap_atomic(it.page); 136 atomic_map = true; 137 it.ofs = 0; 138 } 139 vi->xattr_shared_xattrs[i] = 140 le32_to_cpu(*(__le32 *)(it.kaddr + it.ofs)); 141 it.ofs += sizeof(__le32); 142 } 143 xattr_iter_end(&it, atomic_map); 144 145 /* paired with smp_mb() at the beginning of the function. */ 146 smp_mb(); 147 set_bit(EROFS_I_EA_INITED_BIT, &vi->flags); 148 149 out_unlock: 150 clear_and_wake_up_bit(EROFS_I_BL_XATTR_BIT, &vi->flags); 151 return ret; 152 } 153 154 /* 155 * the general idea for these return values is 156 * if 0 is returned, go on processing the current xattr; 157 * 1 (> 0) is returned, skip this round to process the next xattr; 158 * -err (< 0) is returned, an error (maybe ENOXATTR) occurred 159 * and need to be handled 160 */ 161 struct xattr_iter_handlers { 162 int (*entry)(struct xattr_iter *_it, struct erofs_xattr_entry *entry); 163 int (*name)(struct xattr_iter *_it, unsigned int processed, char *buf, 164 unsigned int len); 165 int (*alloc_buffer)(struct xattr_iter *_it, unsigned int value_sz); 166 void (*value)(struct xattr_iter *_it, unsigned int processed, char *buf, 167 unsigned int len); 168 }; 169 170 static inline int xattr_iter_fixup(struct xattr_iter *it) 171 { 172 if (it->ofs < EROFS_BLKSIZ) 173 return 0; 174 175 xattr_iter_end(it, true); 176 177 it->blkaddr += erofs_blknr(it->ofs); 178 179 it->page = erofs_get_meta_page(it->sb, it->blkaddr); 180 if (IS_ERR(it->page)) { 181 int err = PTR_ERR(it->page); 182 183 it->page = NULL; 184 return err; 185 } 186 187 it->kaddr = kmap_atomic(it->page); 188 it->ofs = erofs_blkoff(it->ofs); 189 return 0; 190 } 191 192 static int inline_xattr_iter_begin(struct xattr_iter *it, 193 struct inode *inode) 194 { 195 struct erofs_inode *const vi = EROFS_I(inode); 196 struct erofs_sb_info *const sbi = EROFS_SB(inode->i_sb); 197 unsigned int xattr_header_sz, inline_xattr_ofs; 198 199 xattr_header_sz = inlinexattr_header_size(inode); 200 if (xattr_header_sz >= vi->xattr_isize) { 201 DBG_BUGON(xattr_header_sz > vi->xattr_isize); 202 return -ENOATTR; 203 } 204 205 inline_xattr_ofs = vi->inode_isize + xattr_header_sz; 206 207 it->blkaddr = erofs_blknr(iloc(sbi, vi->nid) + inline_xattr_ofs); 208 it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs); 209 210 it->page = erofs_get_meta_page(inode->i_sb, it->blkaddr); 211 if (IS_ERR(it->page)) 212 return PTR_ERR(it->page); 213 214 it->kaddr = kmap_atomic(it->page); 215 return vi->xattr_isize - xattr_header_sz; 216 } 217 218 /* 219 * Regardless of success or failure, `xattr_foreach' will end up with 220 * `ofs' pointing to the next xattr item rather than an arbitrary position. 221 */ 222 static int xattr_foreach(struct xattr_iter *it, 223 const struct xattr_iter_handlers *op, 224 unsigned int *tlimit) 225 { 226 struct erofs_xattr_entry entry; 227 unsigned int value_sz, processed, slice; 228 int err; 229 230 /* 0. fixup blkaddr, ofs, ipage */ 231 err = xattr_iter_fixup(it); 232 if (err) 233 return err; 234 235 /* 236 * 1. read xattr entry to the memory, 237 * since we do EROFS_XATTR_ALIGN 238 * therefore entry should be in the page 239 */ 240 entry = *(struct erofs_xattr_entry *)(it->kaddr + it->ofs); 241 if (tlimit) { 242 unsigned int entry_sz = erofs_xattr_entry_size(&entry); 243 244 /* xattr on-disk corruption: xattr entry beyond xattr_isize */ 245 if (*tlimit < entry_sz) { 246 DBG_BUGON(1); 247 return -EFSCORRUPTED; 248 } 249 *tlimit -= entry_sz; 250 } 251 252 it->ofs += sizeof(struct erofs_xattr_entry); 253 value_sz = le16_to_cpu(entry.e_value_size); 254 255 /* handle entry */ 256 err = op->entry(it, &entry); 257 if (err) { 258 it->ofs += entry.e_name_len + value_sz; 259 goto out; 260 } 261 262 /* 2. handle xattr name (ofs will finally be at the end of name) */ 263 processed = 0; 264 265 while (processed < entry.e_name_len) { 266 if (it->ofs >= EROFS_BLKSIZ) { 267 DBG_BUGON(it->ofs > EROFS_BLKSIZ); 268 269 err = xattr_iter_fixup(it); 270 if (err) 271 goto out; 272 it->ofs = 0; 273 } 274 275 slice = min_t(unsigned int, PAGE_SIZE - it->ofs, 276 entry.e_name_len - processed); 277 278 /* handle name */ 279 err = op->name(it, processed, it->kaddr + it->ofs, slice); 280 if (err) { 281 it->ofs += entry.e_name_len - processed + value_sz; 282 goto out; 283 } 284 285 it->ofs += slice; 286 processed += slice; 287 } 288 289 /* 3. handle xattr value */ 290 processed = 0; 291 292 if (op->alloc_buffer) { 293 err = op->alloc_buffer(it, value_sz); 294 if (err) { 295 it->ofs += value_sz; 296 goto out; 297 } 298 } 299 300 while (processed < value_sz) { 301 if (it->ofs >= EROFS_BLKSIZ) { 302 DBG_BUGON(it->ofs > EROFS_BLKSIZ); 303 304 err = xattr_iter_fixup(it); 305 if (err) 306 goto out; 307 it->ofs = 0; 308 } 309 310 slice = min_t(unsigned int, PAGE_SIZE - it->ofs, 311 value_sz - processed); 312 op->value(it, processed, it->kaddr + it->ofs, slice); 313 it->ofs += slice; 314 processed += slice; 315 } 316 317 out: 318 /* xattrs should be 4-byte aligned (on-disk constraint) */ 319 it->ofs = EROFS_XATTR_ALIGN(it->ofs); 320 return err < 0 ? err : 0; 321 } 322 323 struct getxattr_iter { 324 struct xattr_iter it; 325 326 char *buffer; 327 int buffer_size, index; 328 struct qstr name; 329 }; 330 331 static int xattr_entrymatch(struct xattr_iter *_it, 332 struct erofs_xattr_entry *entry) 333 { 334 struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it); 335 336 return (it->index != entry->e_name_index || 337 it->name.len != entry->e_name_len) ? -ENOATTR : 0; 338 } 339 340 static int xattr_namematch(struct xattr_iter *_it, 341 unsigned int processed, char *buf, unsigned int len) 342 { 343 struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it); 344 345 return memcmp(buf, it->name.name + processed, len) ? -ENOATTR : 0; 346 } 347 348 static int xattr_checkbuffer(struct xattr_iter *_it, 349 unsigned int value_sz) 350 { 351 struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it); 352 int err = it->buffer_size < value_sz ? -ERANGE : 0; 353 354 it->buffer_size = value_sz; 355 return !it->buffer ? 1 : err; 356 } 357 358 static void xattr_copyvalue(struct xattr_iter *_it, 359 unsigned int processed, 360 char *buf, unsigned int len) 361 { 362 struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it); 363 364 memcpy(it->buffer + processed, buf, len); 365 } 366 367 static const struct xattr_iter_handlers find_xattr_handlers = { 368 .entry = xattr_entrymatch, 369 .name = xattr_namematch, 370 .alloc_buffer = xattr_checkbuffer, 371 .value = xattr_copyvalue 372 }; 373 374 static int inline_getxattr(struct inode *inode, struct getxattr_iter *it) 375 { 376 int ret; 377 unsigned int remaining; 378 379 ret = inline_xattr_iter_begin(&it->it, inode); 380 if (ret < 0) 381 return ret; 382 383 remaining = ret; 384 while (remaining) { 385 ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining); 386 if (ret != -ENOATTR) 387 break; 388 } 389 xattr_iter_end_final(&it->it); 390 391 return ret ? ret : it->buffer_size; 392 } 393 394 static int shared_getxattr(struct inode *inode, struct getxattr_iter *it) 395 { 396 struct erofs_inode *const vi = EROFS_I(inode); 397 struct super_block *const sb = inode->i_sb; 398 struct erofs_sb_info *const sbi = EROFS_SB(sb); 399 unsigned int i; 400 int ret = -ENOATTR; 401 402 for (i = 0; i < vi->xattr_shared_count; ++i) { 403 erofs_blk_t blkaddr = 404 xattrblock_addr(sbi, vi->xattr_shared_xattrs[i]); 405 406 it->it.ofs = xattrblock_offset(sbi, vi->xattr_shared_xattrs[i]); 407 408 if (!i || blkaddr != it->it.blkaddr) { 409 if (i) 410 xattr_iter_end(&it->it, true); 411 412 it->it.page = erofs_get_meta_page(sb, blkaddr); 413 if (IS_ERR(it->it.page)) 414 return PTR_ERR(it->it.page); 415 416 it->it.kaddr = kmap_atomic(it->it.page); 417 it->it.blkaddr = blkaddr; 418 } 419 420 ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL); 421 if (ret != -ENOATTR) 422 break; 423 } 424 if (vi->xattr_shared_count) 425 xattr_iter_end_final(&it->it); 426 427 return ret ? ret : it->buffer_size; 428 } 429 430 static bool erofs_xattr_user_list(struct dentry *dentry) 431 { 432 return test_opt(&EROFS_SB(dentry->d_sb)->ctx, XATTR_USER); 433 } 434 435 static bool erofs_xattr_trusted_list(struct dentry *dentry) 436 { 437 return capable(CAP_SYS_ADMIN); 438 } 439 440 int erofs_getxattr(struct inode *inode, int index, 441 const char *name, 442 void *buffer, size_t buffer_size) 443 { 444 int ret; 445 struct getxattr_iter it; 446 447 if (!name) 448 return -EINVAL; 449 450 ret = init_inode_xattrs(inode); 451 if (ret) 452 return ret; 453 454 it.index = index; 455 456 it.name.len = strlen(name); 457 if (it.name.len > EROFS_NAME_LEN) 458 return -ERANGE; 459 it.name.name = name; 460 461 it.buffer = buffer; 462 it.buffer_size = buffer_size; 463 464 it.it.sb = inode->i_sb; 465 ret = inline_getxattr(inode, &it); 466 if (ret == -ENOATTR) 467 ret = shared_getxattr(inode, &it); 468 return ret; 469 } 470 471 static int erofs_xattr_generic_get(const struct xattr_handler *handler, 472 struct dentry *unused, struct inode *inode, 473 const char *name, void *buffer, size_t size) 474 { 475 struct erofs_sb_info *const sbi = EROFS_I_SB(inode); 476 477 switch (handler->flags) { 478 case EROFS_XATTR_INDEX_USER: 479 if (!test_opt(&sbi->ctx, XATTR_USER)) 480 return -EOPNOTSUPP; 481 break; 482 case EROFS_XATTR_INDEX_TRUSTED: 483 break; 484 case EROFS_XATTR_INDEX_SECURITY: 485 break; 486 default: 487 return -EINVAL; 488 } 489 490 return erofs_getxattr(inode, handler->flags, name, buffer, size); 491 } 492 493 const struct xattr_handler erofs_xattr_user_handler = { 494 .prefix = XATTR_USER_PREFIX, 495 .flags = EROFS_XATTR_INDEX_USER, 496 .list = erofs_xattr_user_list, 497 .get = erofs_xattr_generic_get, 498 }; 499 500 const struct xattr_handler erofs_xattr_trusted_handler = { 501 .prefix = XATTR_TRUSTED_PREFIX, 502 .flags = EROFS_XATTR_INDEX_TRUSTED, 503 .list = erofs_xattr_trusted_list, 504 .get = erofs_xattr_generic_get, 505 }; 506 507 #ifdef CONFIG_EROFS_FS_SECURITY 508 const struct xattr_handler __maybe_unused erofs_xattr_security_handler = { 509 .prefix = XATTR_SECURITY_PREFIX, 510 .flags = EROFS_XATTR_INDEX_SECURITY, 511 .get = erofs_xattr_generic_get, 512 }; 513 #endif 514 515 const struct xattr_handler *erofs_xattr_handlers[] = { 516 &erofs_xattr_user_handler, 517 #ifdef CONFIG_EROFS_FS_POSIX_ACL 518 &posix_acl_access_xattr_handler, 519 &posix_acl_default_xattr_handler, 520 #endif 521 &erofs_xattr_trusted_handler, 522 #ifdef CONFIG_EROFS_FS_SECURITY 523 &erofs_xattr_security_handler, 524 #endif 525 NULL, 526 }; 527 528 struct listxattr_iter { 529 struct xattr_iter it; 530 531 struct dentry *dentry; 532 char *buffer; 533 int buffer_size, buffer_ofs; 534 }; 535 536 static int xattr_entrylist(struct xattr_iter *_it, 537 struct erofs_xattr_entry *entry) 538 { 539 struct listxattr_iter *it = 540 container_of(_it, struct listxattr_iter, it); 541 unsigned int prefix_len; 542 const char *prefix; 543 544 const struct xattr_handler *h = 545 erofs_xattr_handler(entry->e_name_index); 546 547 if (!h || (h->list && !h->list(it->dentry))) 548 return 1; 549 550 prefix = xattr_prefix(h); 551 prefix_len = strlen(prefix); 552 553 if (!it->buffer) { 554 it->buffer_ofs += prefix_len + entry->e_name_len + 1; 555 return 1; 556 } 557 558 if (it->buffer_ofs + prefix_len 559 + entry->e_name_len + 1 > it->buffer_size) 560 return -ERANGE; 561 562 memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len); 563 it->buffer_ofs += prefix_len; 564 return 0; 565 } 566 567 static int xattr_namelist(struct xattr_iter *_it, 568 unsigned int processed, char *buf, unsigned int len) 569 { 570 struct listxattr_iter *it = 571 container_of(_it, struct listxattr_iter, it); 572 573 memcpy(it->buffer + it->buffer_ofs, buf, len); 574 it->buffer_ofs += len; 575 return 0; 576 } 577 578 static int xattr_skipvalue(struct xattr_iter *_it, 579 unsigned int value_sz) 580 { 581 struct listxattr_iter *it = 582 container_of(_it, struct listxattr_iter, it); 583 584 it->buffer[it->buffer_ofs++] = '\0'; 585 return 1; 586 } 587 588 static const struct xattr_iter_handlers list_xattr_handlers = { 589 .entry = xattr_entrylist, 590 .name = xattr_namelist, 591 .alloc_buffer = xattr_skipvalue, 592 .value = NULL 593 }; 594 595 static int inline_listxattr(struct listxattr_iter *it) 596 { 597 int ret; 598 unsigned int remaining; 599 600 ret = inline_xattr_iter_begin(&it->it, d_inode(it->dentry)); 601 if (ret < 0) 602 return ret; 603 604 remaining = ret; 605 while (remaining) { 606 ret = xattr_foreach(&it->it, &list_xattr_handlers, &remaining); 607 if (ret) 608 break; 609 } 610 xattr_iter_end_final(&it->it); 611 return ret ? ret : it->buffer_ofs; 612 } 613 614 static int shared_listxattr(struct listxattr_iter *it) 615 { 616 struct inode *const inode = d_inode(it->dentry); 617 struct erofs_inode *const vi = EROFS_I(inode); 618 struct super_block *const sb = inode->i_sb; 619 struct erofs_sb_info *const sbi = EROFS_SB(sb); 620 unsigned int i; 621 int ret = 0; 622 623 for (i = 0; i < vi->xattr_shared_count; ++i) { 624 erofs_blk_t blkaddr = 625 xattrblock_addr(sbi, vi->xattr_shared_xattrs[i]); 626 627 it->it.ofs = xattrblock_offset(sbi, vi->xattr_shared_xattrs[i]); 628 if (!i || blkaddr != it->it.blkaddr) { 629 if (i) 630 xattr_iter_end(&it->it, true); 631 632 it->it.page = erofs_get_meta_page(sb, blkaddr); 633 if (IS_ERR(it->it.page)) 634 return PTR_ERR(it->it.page); 635 636 it->it.kaddr = kmap_atomic(it->it.page); 637 it->it.blkaddr = blkaddr; 638 } 639 640 ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL); 641 if (ret) 642 break; 643 } 644 if (vi->xattr_shared_count) 645 xattr_iter_end_final(&it->it); 646 647 return ret ? ret : it->buffer_ofs; 648 } 649 650 ssize_t erofs_listxattr(struct dentry *dentry, 651 char *buffer, size_t buffer_size) 652 { 653 int ret; 654 struct listxattr_iter it; 655 656 ret = init_inode_xattrs(d_inode(dentry)); 657 if (ret == -ENOATTR) 658 return 0; 659 if (ret) 660 return ret; 661 662 it.dentry = dentry; 663 it.buffer = buffer; 664 it.buffer_size = buffer_size; 665 it.buffer_ofs = 0; 666 667 it.it.sb = dentry->d_sb; 668 669 ret = inline_listxattr(&it); 670 if (ret < 0 && ret != -ENOATTR) 671 return ret; 672 return shared_listxattr(&it); 673 } 674 675 #ifdef CONFIG_EROFS_FS_POSIX_ACL 676 struct posix_acl *erofs_get_acl(struct inode *inode, int type) 677 { 678 struct posix_acl *acl; 679 int prefix, rc; 680 char *value = NULL; 681 682 switch (type) { 683 case ACL_TYPE_ACCESS: 684 prefix = EROFS_XATTR_INDEX_POSIX_ACL_ACCESS; 685 break; 686 case ACL_TYPE_DEFAULT: 687 prefix = EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT; 688 break; 689 default: 690 return ERR_PTR(-EINVAL); 691 } 692 693 rc = erofs_getxattr(inode, prefix, "", NULL, 0); 694 if (rc > 0) { 695 value = kmalloc(rc, GFP_KERNEL); 696 if (!value) 697 return ERR_PTR(-ENOMEM); 698 rc = erofs_getxattr(inode, prefix, "", value, rc); 699 } 700 701 if (rc == -ENOATTR) 702 acl = NULL; 703 else if (rc < 0) 704 acl = ERR_PTR(rc); 705 else 706 acl = posix_acl_from_xattr(&init_user_ns, value, rc); 707 kfree(value); 708 return acl; 709 } 710 #endif 711