Hi "Mickaël, I love your patch! Yet something to improve: [auto build test ERROR on cfb92440ee71adcc2105b0890bb01ac3cddb8507] url: https://github.com/0day-ci/linux/commits/Micka-l-Sala-n/Landlock-file-linking-and-renaming-support/20220222-051842 base: cfb92440ee71adcc2105b0890bb01ac3cddb8507 config: hexagon-randconfig-r002-20220221 (https://download.01.org/0day-ci/archive/20220222/202202221149.qLO9DEqo-lkp@xxxxxxxxx/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/0day-ci/linux/commit/c68b879f54d6262963d435a18cedbc238b7faeaf git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Micka-l-Sala-n/Landlock-file-linking-and-renaming-support/20220222-051842 git checkout c68b879f54d6262963d435a18cedbc238b7faeaf # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All errors (new ones prefixed by >>): >> security/landlock/fs.c:463:2: error: call to __compiletime_assert_228 declared with 'error' attribute: BUILD_BUG_ON failed: !layer_masks_dst_parent BUILD_BUG_ON(!layer_masks_dst_parent); ^ include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON' BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) ^ include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG' #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) ^ include/linux/compiler_types.h:346:2: note: expanded from macro 'compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ include/linux/compiler_types.h:334:2: note: expanded from macro '_compiletime_assert' __compiletime_assert(condition, msg, prefix, suffix) ^ include/linux/compiler_types.h:327:4: note: expanded from macro '__compiletime_assert' prefix ## suffix(); \ ^ <scratch space>:170:1: note: expanded from here __compiletime_assert_228 ^ >> security/landlock/fs.c:670:2: error: call to __compiletime_assert_229 declared with 'error' attribute: BUILD_BUG_ON failed: !layer_masks_dom BUILD_BUG_ON(!layer_masks_dom); ^ include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON' BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) ^ include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG' #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) ^ include/linux/compiler_types.h:346:2: note: expanded from macro 'compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ include/linux/compiler_types.h:334:2: note: expanded from macro '_compiletime_assert' __compiletime_assert(condition, msg, prefix, suffix) ^ include/linux/compiler_types.h:327:4: note: expanded from macro '__compiletime_assert' prefix ## suffix(); \ ^ <scratch space>:174:1: note: expanded from here __compiletime_assert_229 ^ 2 errors generated. vim +/error +463 security/landlock/fs.c 401 402 /** 403 * check_access_path_dual - Check a source and a destination accesses 404 * 405 * @domain: Domain to check against. 406 * @path: File hierarchy to walk through. 407 * @child_is_directory: Must be set to true if the (original) leaf is a 408 * directory, false otherwise. 409 * @access_request_dst_parent: Accesses to check, once @layer_masks_dst_parent 410 * is equal to @layer_masks_src_parent (if any). 411 * @layer_masks_dst_parent: Pointer to a matrix of layer masks per access 412 * masks, identifying the layers that forbid a specific access. Bits from 413 * this matrix can be unset according to the @path walk. An empty matrix 414 * means that @domain allows all possible Landlock accesses (i.e. not only 415 * those identified by @access_request_dst_parent). This matrix can 416 * initially refer to domain layer masks and, when the accesses for the 417 * destination and source are the same, to request layer masks. 418 * @access_request_src_parent: Similar to @access_request_dst_parent but for an 419 * initial source path request. Only taken into account if 420 * @layer_masks_src_parent is not NULL. 421 * @layer_masks_src_parent: Similar to @layer_masks_dst_parent but for an 422 * initial source path walk. This can be NULL if only dealing with a 423 * destination access request (i.e. not a rename nor a link action). 424 * @layer_masks_child: Similar to @layer_masks_src_parent but only for the 425 * linked or renamed inode (without hierarchy). This is only used if 426 * @layer_masks_src_parent is not NULL. 427 * 428 * This helper first checks that the destination has a superset of restrictions 429 * compared to the source (if any) for a common path. It then checks that the 430 * collected accesses and the remaining ones are enough to allow the request. 431 * 432 * Returns: 433 * - 0 if the access request is granted; 434 * - -EACCES if it is denied because of access right other than 435 * LANDLOCK_ACCESS_FS_REFER; 436 * - -EXDEV if the renaming or linking would be a privileged escalation 437 * (according to each layered policies), or if LANDLOCK_ACCESS_FS_REFER is 438 * not allowed by the source or the destination. 439 */ 440 static int check_access_path_dual(const struct landlock_ruleset *const domain, 441 const struct path *const path, 442 bool child_is_directory, 443 const access_mask_t access_request_dst_parent, 444 layer_mask_t (*const 445 layer_masks_dst_parent)[LANDLOCK_NUM_ACCESS_FS], 446 const access_mask_t access_request_src_parent, 447 layer_mask_t (*layer_masks_src_parent)[LANDLOCK_NUM_ACCESS_FS], 448 layer_mask_t (*layer_masks_child)[LANDLOCK_NUM_ACCESS_FS]) 449 { 450 bool allowed_dst_parent = false, allowed_src_parent = false, is_dom_check; 451 struct path walker_path; 452 access_mask_t access_masked_dst_parent, access_masked_src_parent; 453 454 if (!access_request_dst_parent && !access_request_src_parent) 455 return 0; 456 if (WARN_ON_ONCE(!domain || !path)) 457 return 0; 458 if (is_nouser_or_private(path->dentry)) 459 return 0; 460 if (WARN_ON_ONCE(domain->num_layers < 1)) 461 return -EACCES; 462 > 463 BUILD_BUG_ON(!layer_masks_dst_parent); 464 if (layer_masks_src_parent) { 465 if (WARN_ON_ONCE(!layer_masks_child)) 466 return -EACCES; 467 access_masked_dst_parent = access_masked_src_parent = 468 get_handled_accesses(domain); 469 is_dom_check = true; 470 } else { 471 if (WARN_ON_ONCE(layer_masks_child)) 472 return -EACCES; 473 access_masked_dst_parent = access_request_dst_parent; 474 access_masked_src_parent = access_request_src_parent; 475 is_dom_check = false; 476 } 477 478 walker_path = *path; 479 path_get(&walker_path); 480 /* 481 * We need to walk through all the hierarchy to not miss any relevant 482 * restriction. 483 */ 484 while (true) { 485 struct dentry *parent_dentry; 486 const struct landlock_rule *rule; 487 488 /* 489 * If at least all accesses allowed on the destination are 490 * already allowed on the source, respectively if there is at 491 * least as much as restrictions on the destination than on the 492 * source, then we can safely refer files from the source to 493 * the destination without risking a privilege escalation. 494 * This is crucial for standalone multilayered security 495 * policies. Furthermore, this helps avoid policy writers to 496 * shoot themselves in the foot. 497 */ 498 if (is_dom_check && is_superset(child_is_directory, 499 layer_masks_dst_parent, 500 layer_masks_src_parent, 501 layer_masks_child)) { 502 allowed_dst_parent = 503 scope_to_request(access_request_dst_parent, 504 layer_masks_dst_parent); 505 allowed_src_parent = 506 scope_to_request(access_request_src_parent, 507 layer_masks_src_parent); 508 509 /* Stops when all accesses are granted. */ 510 if (allowed_dst_parent && allowed_src_parent) 511 break; 512 513 /* 514 * Downgrades checks from domain handled accesses to 515 * requested accesses. 516 */ 517 is_dom_check = false; 518 access_masked_dst_parent = access_request_dst_parent; 519 access_masked_src_parent = access_request_src_parent; 520 } 521 522 rule = find_rule(domain, walker_path.dentry); 523 allowed_dst_parent = unmask_layers(rule, access_masked_dst_parent, 524 layer_masks_dst_parent); 525 allowed_src_parent = unmask_layers(rule, access_masked_src_parent, 526 layer_masks_src_parent); 527 528 /* Stops when a rule from each layer grants access. */ 529 if (allowed_dst_parent && allowed_src_parent) 530 break; 531 532 jump_up: 533 if (walker_path.dentry == walker_path.mnt->mnt_root) { 534 if (follow_up(&walker_path)) { 535 /* Ignores hidden mount points. */ 536 goto jump_up; 537 } else { 538 /* 539 * Stops at the real root. Denies access 540 * because not all layers have granted access. 541 */ 542 allowed_dst_parent = false; 543 break; 544 } 545 } 546 if (unlikely(IS_ROOT(walker_path.dentry))) { 547 /* 548 * Stops at disconnected root directories. Only allows 549 * access to internal filesystems (e.g. nsfs, which is 550 * reachable through /proc/<pid>/ns/<namespace>). 551 */ 552 allowed_dst_parent = !!(walker_path.mnt->mnt_flags & 553 MNT_INTERNAL); 554 break; 555 } 556 parent_dentry = dget_parent(walker_path.dentry); 557 dput(walker_path.dentry); 558 walker_path.dentry = parent_dentry; 559 } 560 path_put(&walker_path); 561 562 if (allowed_dst_parent && allowed_src_parent) 563 return 0; 564 565 /* 566 * Unfortunately, we cannot prioritize EACCES over EXDEV for all 567 * RENAME_EXCHANGE cases because it depends on the source and 568 * destination order. This could be changed with a new 569 * security_path_rename hook implementation. 570 */ 571 if (likely(is_eacces(layer_masks_dst_parent, access_request_dst_parent) 572 || is_eacces(layer_masks_src_parent, 573 access_request_src_parent))) 574 return -EACCES; 575 576 /* 577 * Gracefully forbids reparenting if the destination directory 578 * hierarchy is not a superset of restrictions of the source directory 579 * hierarchy, or if LANDLOCK_ACCESS_FS_REFER is not allowed by the 580 * source or the destination. 581 */ 582 return -EXDEV; 583 } 584 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
