1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Landlock - Filesystem management and hooks 4 * 5 * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net> 6 * Copyright © 2018-2020 ANSSI 7 * Copyright © 2021-2025 Microsoft Corporation 8 * Copyright © 2022 Günther Noack <gnoack3000@gmail.com> 9 * Copyright © 2023-2024 Google LLC 10 */ 11 12 #include <asm/ioctls.h> 13 #include <kunit/test.h> 14 #include <linux/atomic.h> 15 #include <linux/bitops.h> 16 #include <linux/bits.h> 17 #include <linux/compiler_types.h> 18 #include <linux/dcache.h> 19 #include <linux/err.h> 20 #include <linux/falloc.h> 21 #include <linux/fs.h> 22 #include <linux/init.h> 23 #include <linux/kernel.h> 24 #include <linux/limits.h> 25 #include <linux/list.h> 26 #include <linux/lsm_audit.h> 27 #include <linux/lsm_hooks.h> 28 #include <linux/mount.h> 29 #include <linux/namei.h> 30 #include <linux/path.h> 31 #include <linux/pid.h> 32 #include <linux/rcupdate.h> 33 #include <linux/sched/signal.h> 34 #include <linux/spinlock.h> 35 #include <linux/stat.h> 36 #include <linux/types.h> 37 #include <linux/wait_bit.h> 38 #include <linux/workqueue.h> 39 #include <uapi/linux/fiemap.h> 40 #include <uapi/linux/landlock.h> 41 42 #include "access.h" 43 #include "audit.h" 44 #include "common.h" 45 #include "cred.h" 46 #include "domain.h" 47 #include "fs.h" 48 #include "limits.h" 49 #include "object.h" 50 #include "ruleset.h" 51 #include "setup.h" 52 53 /* Underlying object management */ 54 55 static void release_inode(struct landlock_object *const object) 56 __releases(object->lock) 57 { 58 struct inode *const inode = object->underobj; 59 struct super_block *sb; 60 61 if (!inode) { 62 spin_unlock(&object->lock); 63 return; 64 } 65 66 /* 67 * Protects against concurrent use by hook_sb_delete() of the reference 68 * to the underlying inode. 69 */ 70 object->underobj = NULL; 71 /* 72 * Makes sure that if the filesystem is concurrently unmounted, 73 * hook_sb_delete() will wait for us to finish iput(). 74 */ 75 sb = inode->i_sb; 76 atomic_long_inc(&landlock_superblock(sb)->inode_refs); 77 spin_unlock(&object->lock); 78 /* 79 * Because object->underobj was not NULL, hook_sb_delete() and 80 * get_inode_object() guarantee that it is safe to reset 81 * landlock_inode(inode)->object while it is not NULL. It is therefore 82 * not necessary to lock inode->i_lock. 83 */ 84 rcu_assign_pointer(landlock_inode(inode)->object, NULL); 85 /* 86 * Now, new rules can safely be tied to @inode with get_inode_object(). 87 */ 88 89 iput(inode); 90 if (atomic_long_dec_and_test(&landlock_superblock(sb)->inode_refs)) 91 wake_up_var(&landlock_superblock(sb)->inode_refs); 92 } 93 94 static const struct landlock_object_underops landlock_fs_underops = { 95 .release = release_inode 96 }; 97 98 /* IOCTL helpers */ 99 100 /** 101 * is_masked_device_ioctl - Determine whether an IOCTL command is always 102 * permitted with Landlock for device files. These commands can not be 103 * restricted on device files by enforcing a Landlock policy. 104 * 105 * @cmd: The IOCTL command that is supposed to be run. 106 * 107 * By default, any IOCTL on a device file requires the 108 * LANDLOCK_ACCESS_FS_IOCTL_DEV right. However, we blanket-permit some 109 * commands, if: 110 * 111 * 1. The command is implemented in fs/ioctl.c's do_vfs_ioctl(), 112 * not in f_ops->unlocked_ioctl() or f_ops->compat_ioctl(). 113 * 114 * 2. The command is harmless when invoked on devices. 115 * 116 * We also permit commands that do not make sense for devices, but where the 117 * do_vfs_ioctl() implementation returns a more conventional error code. 118 * 119 * Any new IOCTL commands that are implemented in fs/ioctl.c's do_vfs_ioctl() 120 * should be considered for inclusion here. 121 * 122 * Returns: true if the IOCTL @cmd can not be restricted with Landlock for 123 * device files. 124 */ 125 static __attribute_const__ bool is_masked_device_ioctl(const unsigned int cmd) 126 { 127 switch (cmd) { 128 /* 129 * FIOCLEX, FIONCLEX, FIONBIO and FIOASYNC manipulate the FD's 130 * close-on-exec and the file's buffered-IO and async flags. These 131 * operations are also available through fcntl(2), and are 132 * unconditionally permitted in Landlock. 133 */ 134 case FIOCLEX: 135 case FIONCLEX: 136 case FIONBIO: 137 case FIOASYNC: 138 /* 139 * FIOQSIZE queries the size of a regular file, directory, or link. 140 * 141 * We still permit it, because it always returns -ENOTTY for 142 * other file types. 143 */ 144 case FIOQSIZE: 145 /* 146 * FIFREEZE and FITHAW freeze and thaw the file system which the 147 * given file belongs to. Requires CAP_SYS_ADMIN. 148 * 149 * These commands operate on the file system's superblock rather 150 * than on the file itself. The same operations can also be 151 * done through any other file or directory on the same file 152 * system, so it is safe to permit these. 153 */ 154 case FIFREEZE: 155 case FITHAW: 156 /* 157 * FS_IOC_FIEMAP queries information about the allocation of 158 * blocks within a file. 159 * 160 * This IOCTL command only makes sense for regular files and is 161 * not implemented by devices. It is harmless to permit. 162 */ 163 case FS_IOC_FIEMAP: 164 /* 165 * FIGETBSZ queries the file system's block size for a file or 166 * directory. 167 * 168 * This command operates on the file system's superblock rather 169 * than on the file itself. The same operation can also be done 170 * through any other file or directory on the same file system, 171 * so it is safe to permit it. 172 */ 173 case FIGETBSZ: 174 /* 175 * FICLONE, FICLONERANGE and FIDEDUPERANGE make files share 176 * their underlying storage ("reflink") between source and 177 * destination FDs, on file systems which support that. 178 * 179 * These IOCTL commands only apply to regular files 180 * and are harmless to permit for device files. 181 */ 182 case FICLONE: 183 case FICLONERANGE: 184 case FIDEDUPERANGE: 185 /* 186 * FS_IOC_GETFSUUID and FS_IOC_GETFSSYSFSPATH both operate on 187 * the file system superblock, not on the specific file, so 188 * these operations are available through any other file on the 189 * same file system as well. 190 */ 191 case FS_IOC_GETFSUUID: 192 case FS_IOC_GETFSSYSFSPATH: 193 return true; 194 195 /* 196 * FIONREAD, FS_IOC_GETFLAGS, FS_IOC_SETFLAGS, FS_IOC_FSGETXATTR and 197 * FS_IOC_FSSETXATTR are forwarded to device implementations. 198 */ 199 200 /* 201 * file_ioctl() commands (FIBMAP, FS_IOC_RESVSP, FS_IOC_RESVSP64, 202 * FS_IOC_UNRESVSP, FS_IOC_UNRESVSP64 and FS_IOC_ZERO_RANGE) are 203 * forwarded to device implementations, so not permitted. 204 */ 205 206 /* Other commands are guarded by the access right. */ 207 default: 208 return false; 209 } 210 } 211 212 /* 213 * is_masked_device_ioctl_compat - same as the helper above, but checking the 214 * "compat" IOCTL commands. 215 * 216 * The IOCTL commands with special handling in compat-mode should behave the 217 * same as their non-compat counterparts. 218 */ 219 static __attribute_const__ bool 220 is_masked_device_ioctl_compat(const unsigned int cmd) 221 { 222 switch (cmd) { 223 /* FICLONE is permitted, same as in the non-compat variant. */ 224 case FICLONE: 225 return true; 226 227 #if defined(CONFIG_X86_64) 228 /* 229 * FS_IOC_RESVSP_32, FS_IOC_RESVSP64_32, FS_IOC_UNRESVSP_32, 230 * FS_IOC_UNRESVSP64_32, FS_IOC_ZERO_RANGE_32: not blanket-permitted, 231 * for consistency with their non-compat variants. 232 */ 233 case FS_IOC_RESVSP_32: 234 case FS_IOC_RESVSP64_32: 235 case FS_IOC_UNRESVSP_32: 236 case FS_IOC_UNRESVSP64_32: 237 case FS_IOC_ZERO_RANGE_32: 238 #endif 239 240 /* 241 * FS_IOC32_GETFLAGS, FS_IOC32_SETFLAGS are forwarded to their device 242 * implementations. 243 */ 244 case FS_IOC32_GETFLAGS: 245 case FS_IOC32_SETFLAGS: 246 return false; 247 default: 248 return is_masked_device_ioctl(cmd); 249 } 250 } 251 252 /* Ruleset management */ 253 254 static struct landlock_object *get_inode_object(struct inode *const inode) 255 { 256 struct landlock_object *object, *new_object; 257 struct landlock_inode_security *inode_sec = landlock_inode(inode); 258 259 rcu_read_lock(); 260 retry: 261 object = rcu_dereference(inode_sec->object); 262 if (object) { 263 if (likely(refcount_inc_not_zero(&object->usage))) { 264 rcu_read_unlock(); 265 return object; 266 } 267 /* 268 * We are racing with release_inode(), the object is going 269 * away. Wait for release_inode(), then retry. 270 */ 271 spin_lock(&object->lock); 272 spin_unlock(&object->lock); 273 goto retry; 274 } 275 rcu_read_unlock(); 276 277 /* 278 * If there is no object tied to @inode, then create a new one (without 279 * holding any locks). 280 */ 281 new_object = landlock_create_object(&landlock_fs_underops, inode); 282 if (IS_ERR(new_object)) 283 return new_object; 284 285 /* 286 * Protects against concurrent calls to get_inode_object() or 287 * hook_sb_delete(). 288 */ 289 spin_lock(&inode->i_lock); 290 if (unlikely(rcu_access_pointer(inode_sec->object))) { 291 /* Someone else just created the object, bail out and retry. */ 292 spin_unlock(&inode->i_lock); 293 kfree(new_object); 294 295 rcu_read_lock(); 296 goto retry; 297 } 298 299 /* 300 * @inode will be released by hook_sb_delete() on its superblock 301 * shutdown, or by release_inode() when no more ruleset references the 302 * related object. 303 */ 304 ihold(inode); 305 rcu_assign_pointer(inode_sec->object, new_object); 306 spin_unlock(&inode->i_lock); 307 return new_object; 308 } 309 310 /* All access rights that can be tied to files. */ 311 /* clang-format off */ 312 #define ACCESS_FILE ( \ 313 LANDLOCK_ACCESS_FS_EXECUTE | \ 314 LANDLOCK_ACCESS_FS_WRITE_FILE | \ 315 LANDLOCK_ACCESS_FS_READ_FILE | \ 316 LANDLOCK_ACCESS_FS_TRUNCATE | \ 317 LANDLOCK_ACCESS_FS_IOCTL_DEV) 318 /* clang-format on */ 319 320 /* 321 * @path: Should have been checked by get_path_from_fd(). 322 */ 323 int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, 324 const struct path *const path, 325 access_mask_t access_rights) 326 { 327 int err; 328 struct landlock_id id = { 329 .type = LANDLOCK_KEY_INODE, 330 }; 331 332 /* Files only get access rights that make sense. */ 333 if (!d_is_dir(path->dentry) && 334 (access_rights | ACCESS_FILE) != ACCESS_FILE) 335 return -EINVAL; 336 if (WARN_ON_ONCE(ruleset->num_layers != 1)) 337 return -EINVAL; 338 339 /* Transforms relative access rights to absolute ones. */ 340 access_rights |= LANDLOCK_MASK_ACCESS_FS & 341 ~landlock_get_fs_access_mask(ruleset, 0); 342 id.key.object = get_inode_object(d_backing_inode(path->dentry)); 343 if (IS_ERR(id.key.object)) 344 return PTR_ERR(id.key.object); 345 mutex_lock(&ruleset->lock); 346 err = landlock_insert_rule(ruleset, id, access_rights); 347 mutex_unlock(&ruleset->lock); 348 /* 349 * No need to check for an error because landlock_insert_rule() 350 * increments the refcount for the new object if needed. 351 */ 352 landlock_put_object(id.key.object); 353 return err; 354 } 355 356 /* Access-control management */ 357 358 /* 359 * The lifetime of the returned rule is tied to @domain. 360 * 361 * Returns NULL if no rule is found or if @dentry is negative. 362 */ 363 static const struct landlock_rule * 364 find_rule(const struct landlock_ruleset *const domain, 365 const struct dentry *const dentry) 366 { 367 const struct landlock_rule *rule; 368 const struct inode *inode; 369 struct landlock_id id = { 370 .type = LANDLOCK_KEY_INODE, 371 }; 372 373 /* Ignores nonexistent leafs. */ 374 if (d_is_negative(dentry)) 375 return NULL; 376 377 inode = d_backing_inode(dentry); 378 rcu_read_lock(); 379 id.key.object = rcu_dereference(landlock_inode(inode)->object); 380 rule = landlock_find_rule(domain, id); 381 rcu_read_unlock(); 382 return rule; 383 } 384 385 /* 386 * Allows access to pseudo filesystems that will never be mountable (e.g. 387 * sockfs, pipefs), but can still be reachable through 388 * /proc/<pid>/fd/<file-descriptor> 389 */ 390 static bool is_nouser_or_private(const struct dentry *dentry) 391 { 392 return (dentry->d_sb->s_flags & SB_NOUSER) || 393 (d_is_positive(dentry) && 394 unlikely(IS_PRIVATE(d_backing_inode(dentry)))); 395 } 396 397 static const struct access_masks any_fs = { 398 .fs = ~0, 399 }; 400 401 /* 402 * Check that a destination file hierarchy has more restrictions than a source 403 * file hierarchy. This is only used for link and rename actions. 404 * 405 * @layer_masks_child2: Optional child masks. 406 */ 407 static bool no_more_access( 408 const layer_mask_t (*const layer_masks_parent1)[LANDLOCK_NUM_ACCESS_FS], 409 const layer_mask_t (*const layer_masks_child1)[LANDLOCK_NUM_ACCESS_FS], 410 const bool child1_is_directory, 411 const layer_mask_t (*const layer_masks_parent2)[LANDLOCK_NUM_ACCESS_FS], 412 const layer_mask_t (*const layer_masks_child2)[LANDLOCK_NUM_ACCESS_FS], 413 const bool child2_is_directory) 414 { 415 unsigned long access_bit; 416 417 for (access_bit = 0; access_bit < ARRAY_SIZE(*layer_masks_parent2); 418 access_bit++) { 419 /* Ignores accesses that only make sense for directories. */ 420 const bool is_file_access = 421 !!(BIT_ULL(access_bit) & ACCESS_FILE); 422 423 if (child1_is_directory || is_file_access) { 424 /* 425 * Checks if the destination restrictions are a 426 * superset of the source ones (i.e. inherited access 427 * rights without child exceptions): 428 * restrictions(parent2) >= restrictions(child1) 429 */ 430 if ((((*layer_masks_parent1)[access_bit] & 431 (*layer_masks_child1)[access_bit]) | 432 (*layer_masks_parent2)[access_bit]) != 433 (*layer_masks_parent2)[access_bit]) 434 return false; 435 } 436 437 if (!layer_masks_child2) 438 continue; 439 if (child2_is_directory || is_file_access) { 440 /* 441 * Checks inverted restrictions for RENAME_EXCHANGE: 442 * restrictions(parent1) >= restrictions(child2) 443 */ 444 if ((((*layer_masks_parent2)[access_bit] & 445 (*layer_masks_child2)[access_bit]) | 446 (*layer_masks_parent1)[access_bit]) != 447 (*layer_masks_parent1)[access_bit]) 448 return false; 449 } 450 } 451 return true; 452 } 453 454 #define NMA_TRUE(...) KUNIT_EXPECT_TRUE(test, no_more_access(__VA_ARGS__)) 455 #define NMA_FALSE(...) KUNIT_EXPECT_FALSE(test, no_more_access(__VA_ARGS__)) 456 457 #ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST 458 459 static void test_no_more_access(struct kunit *const test) 460 { 461 const layer_mask_t rx0[LANDLOCK_NUM_ACCESS_FS] = { 462 [BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(0), 463 [BIT_INDEX(LANDLOCK_ACCESS_FS_READ_FILE)] = BIT_ULL(0), 464 }; 465 const layer_mask_t mx0[LANDLOCK_NUM_ACCESS_FS] = { 466 [BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(0), 467 [BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_REG)] = BIT_ULL(0), 468 }; 469 const layer_mask_t x0[LANDLOCK_NUM_ACCESS_FS] = { 470 [BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(0), 471 }; 472 const layer_mask_t x1[LANDLOCK_NUM_ACCESS_FS] = { 473 [BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(1), 474 }; 475 const layer_mask_t x01[LANDLOCK_NUM_ACCESS_FS] = { 476 [BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(0) | 477 BIT_ULL(1), 478 }; 479 const layer_mask_t allows_all[LANDLOCK_NUM_ACCESS_FS] = {}; 480 481 /* Checks without restriction. */ 482 NMA_TRUE(&x0, &allows_all, false, &allows_all, NULL, false); 483 NMA_TRUE(&allows_all, &x0, false, &allows_all, NULL, false); 484 NMA_FALSE(&x0, &x0, false, &allows_all, NULL, false); 485 486 /* 487 * Checks that we can only refer a file if no more access could be 488 * inherited. 489 */ 490 NMA_TRUE(&x0, &x0, false, &rx0, NULL, false); 491 NMA_TRUE(&rx0, &rx0, false, &rx0, NULL, false); 492 NMA_FALSE(&rx0, &rx0, false, &x0, NULL, false); 493 NMA_FALSE(&rx0, &rx0, false, &x1, NULL, false); 494 495 /* Checks allowed referring with different nested domains. */ 496 NMA_TRUE(&x0, &x1, false, &x0, NULL, false); 497 NMA_TRUE(&x1, &x0, false, &x0, NULL, false); 498 NMA_TRUE(&x0, &x01, false, &x0, NULL, false); 499 NMA_TRUE(&x0, &x01, false, &rx0, NULL, false); 500 NMA_TRUE(&x01, &x0, false, &x0, NULL, false); 501 NMA_TRUE(&x01, &x0, false, &rx0, NULL, false); 502 NMA_FALSE(&x01, &x01, false, &x0, NULL, false); 503 504 /* Checks that file access rights are also enforced for a directory. */ 505 NMA_FALSE(&rx0, &rx0, true, &x0, NULL, false); 506 507 /* Checks that directory access rights don't impact file referring... */ 508 NMA_TRUE(&mx0, &mx0, false, &x0, NULL, false); 509 /* ...but only directory referring. */ 510 NMA_FALSE(&mx0, &mx0, true, &x0, NULL, false); 511 512 /* Checks directory exchange. */ 513 NMA_TRUE(&mx0, &mx0, true, &mx0, &mx0, true); 514 NMA_TRUE(&mx0, &mx0, true, &mx0, &x0, true); 515 NMA_FALSE(&mx0, &mx0, true, &x0, &mx0, true); 516 NMA_FALSE(&mx0, &mx0, true, &x0, &x0, true); 517 NMA_FALSE(&mx0, &mx0, true, &x1, &x1, true); 518 519 /* Checks file exchange with directory access rights... */ 520 NMA_TRUE(&mx0, &mx0, false, &mx0, &mx0, false); 521 NMA_TRUE(&mx0, &mx0, false, &mx0, &x0, false); 522 NMA_TRUE(&mx0, &mx0, false, &x0, &mx0, false); 523 NMA_TRUE(&mx0, &mx0, false, &x0, &x0, false); 524 /* ...and with file access rights. */ 525 NMA_TRUE(&rx0, &rx0, false, &rx0, &rx0, false); 526 NMA_TRUE(&rx0, &rx0, false, &rx0, &x0, false); 527 NMA_FALSE(&rx0, &rx0, false, &x0, &rx0, false); 528 NMA_FALSE(&rx0, &rx0, false, &x0, &x0, false); 529 NMA_FALSE(&rx0, &rx0, false, &x1, &x1, false); 530 531 /* 532 * Allowing the following requests should not be a security risk 533 * because domain 0 denies execute access, and domain 1 is always 534 * nested with domain 0. However, adding an exception for this case 535 * would mean to check all nested domains to make sure none can get 536 * more privileges (e.g. processes only sandboxed by domain 0). 537 * Moreover, this behavior (i.e. composition of N domains) could then 538 * be inconsistent compared to domain 1's ruleset alone (e.g. it might 539 * be denied to link/rename with domain 1's ruleset, whereas it would 540 * be allowed if nested on top of domain 0). Another drawback would be 541 * to create a cover channel that could enable sandboxed processes to 542 * infer most of the filesystem restrictions from their domain. To 543 * make it simple, efficient, safe, and more consistent, this case is 544 * always denied. 545 */ 546 NMA_FALSE(&x1, &x1, false, &x0, NULL, false); 547 NMA_FALSE(&x1, &x1, false, &rx0, NULL, false); 548 NMA_FALSE(&x1, &x1, true, &x0, NULL, false); 549 NMA_FALSE(&x1, &x1, true, &rx0, NULL, false); 550 551 /* Checks the same case of exclusive domains with a file... */ 552 NMA_TRUE(&x1, &x1, false, &x01, NULL, false); 553 NMA_FALSE(&x1, &x1, false, &x01, &x0, false); 554 NMA_FALSE(&x1, &x1, false, &x01, &x01, false); 555 NMA_FALSE(&x1, &x1, false, &x0, &x0, false); 556 /* ...and with a directory. */ 557 NMA_FALSE(&x1, &x1, false, &x0, &x0, true); 558 NMA_FALSE(&x1, &x1, true, &x0, &x0, false); 559 NMA_FALSE(&x1, &x1, true, &x0, &x0, true); 560 } 561 562 #endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ 563 564 #undef NMA_TRUE 565 #undef NMA_FALSE 566 567 static bool is_layer_masks_allowed( 568 layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) 569 { 570 return !memchr_inv(layer_masks, 0, sizeof(*layer_masks)); 571 } 572 573 /* 574 * Removes @layer_masks accesses that are not requested. 575 * 576 * Returns true if the request is allowed, false otherwise. 577 */ 578 static bool 579 scope_to_request(const access_mask_t access_request, 580 layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) 581 { 582 const unsigned long access_req = access_request; 583 unsigned long access_bit; 584 585 if (WARN_ON_ONCE(!layer_masks)) 586 return true; 587 588 for_each_clear_bit(access_bit, &access_req, ARRAY_SIZE(*layer_masks)) 589 (*layer_masks)[access_bit] = 0; 590 591 return is_layer_masks_allowed(layer_masks); 592 } 593 594 #ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST 595 596 static void test_scope_to_request_with_exec_none(struct kunit *const test) 597 { 598 /* Allows everything. */ 599 layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {}; 600 601 /* Checks and scopes with execute. */ 602 KUNIT_EXPECT_TRUE(test, scope_to_request(LANDLOCK_ACCESS_FS_EXECUTE, 603 &layer_masks)); 604 KUNIT_EXPECT_EQ(test, 0, 605 layer_masks[BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)]); 606 KUNIT_EXPECT_EQ(test, 0, 607 layer_masks[BIT_INDEX(LANDLOCK_ACCESS_FS_WRITE_FILE)]); 608 } 609 610 static void test_scope_to_request_with_exec_some(struct kunit *const test) 611 { 612 /* Denies execute and write. */ 613 layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = { 614 [BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(0), 615 [BIT_INDEX(LANDLOCK_ACCESS_FS_WRITE_FILE)] = BIT_ULL(1), 616 }; 617 618 /* Checks and scopes with execute. */ 619 KUNIT_EXPECT_FALSE(test, scope_to_request(LANDLOCK_ACCESS_FS_EXECUTE, 620 &layer_masks)); 621 KUNIT_EXPECT_EQ(test, BIT_ULL(0), 622 layer_masks[BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)]); 623 KUNIT_EXPECT_EQ(test, 0, 624 layer_masks[BIT_INDEX(LANDLOCK_ACCESS_FS_WRITE_FILE)]); 625 } 626 627 static void test_scope_to_request_without_access(struct kunit *const test) 628 { 629 /* Denies execute and write. */ 630 layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = { 631 [BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(0), 632 [BIT_INDEX(LANDLOCK_ACCESS_FS_WRITE_FILE)] = BIT_ULL(1), 633 }; 634 635 /* Checks and scopes without access request. */ 636 KUNIT_EXPECT_TRUE(test, scope_to_request(0, &layer_masks)); 637 KUNIT_EXPECT_EQ(test, 0, 638 layer_masks[BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)]); 639 KUNIT_EXPECT_EQ(test, 0, 640 layer_masks[BIT_INDEX(LANDLOCK_ACCESS_FS_WRITE_FILE)]); 641 } 642 643 #endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ 644 645 /* 646 * Returns true if there is at least one access right different than 647 * LANDLOCK_ACCESS_FS_REFER. 648 */ 649 static bool 650 is_eacces(const layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS], 651 const access_mask_t access_request) 652 { 653 unsigned long access_bit; 654 /* LANDLOCK_ACCESS_FS_REFER alone must return -EXDEV. */ 655 const unsigned long access_check = access_request & 656 ~LANDLOCK_ACCESS_FS_REFER; 657 658 if (!layer_masks) 659 return false; 660 661 for_each_set_bit(access_bit, &access_check, ARRAY_SIZE(*layer_masks)) { 662 if ((*layer_masks)[access_bit]) 663 return true; 664 } 665 return false; 666 } 667 668 #define IE_TRUE(...) KUNIT_EXPECT_TRUE(test, is_eacces(__VA_ARGS__)) 669 #define IE_FALSE(...) KUNIT_EXPECT_FALSE(test, is_eacces(__VA_ARGS__)) 670 671 #ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST 672 673 static void test_is_eacces_with_none(struct kunit *const test) 674 { 675 const layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {}; 676 677 IE_FALSE(&layer_masks, 0); 678 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_REFER); 679 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_EXECUTE); 680 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_WRITE_FILE); 681 } 682 683 static void test_is_eacces_with_refer(struct kunit *const test) 684 { 685 const layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = { 686 [BIT_INDEX(LANDLOCK_ACCESS_FS_REFER)] = BIT_ULL(0), 687 }; 688 689 IE_FALSE(&layer_masks, 0); 690 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_REFER); 691 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_EXECUTE); 692 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_WRITE_FILE); 693 } 694 695 static void test_is_eacces_with_write(struct kunit *const test) 696 { 697 const layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = { 698 [BIT_INDEX(LANDLOCK_ACCESS_FS_WRITE_FILE)] = BIT_ULL(0), 699 }; 700 701 IE_FALSE(&layer_masks, 0); 702 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_REFER); 703 IE_FALSE(&layer_masks, LANDLOCK_ACCESS_FS_EXECUTE); 704 705 IE_TRUE(&layer_masks, LANDLOCK_ACCESS_FS_WRITE_FILE); 706 } 707 708 #endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ 709 710 #undef IE_TRUE 711 #undef IE_FALSE 712 713 /** 714 * is_access_to_paths_allowed - Check accesses for requests with a common path 715 * 716 * @domain: Domain to check against. 717 * @path: File hierarchy to walk through. For refer checks, this would be 718 * the common mountpoint. 719 * @access_request_parent1: Accesses to check, once @layer_masks_parent1 is 720 * equal to @layer_masks_parent2 (if any). This is tied to the unique 721 * requested path for most actions, or the source in case of a refer action 722 * (i.e. rename or link), or the source and destination in case of 723 * RENAME_EXCHANGE. 724 * @layer_masks_parent1: Pointer to a matrix of layer masks per access 725 * masks, identifying the layers that forbid a specific access. Bits from 726 * this matrix can be unset according to the @path walk. An empty matrix 727 * means that @domain allows all possible Landlock accesses (i.e. not only 728 * those identified by @access_request_parent1). This matrix can 729 * initially refer to domain layer masks and, when the accesses for the 730 * destination and source are the same, to requested layer masks. 731 * @log_request_parent1: Audit request to fill if the related access is denied. 732 * @dentry_child1: Dentry to the initial child of the parent1 path. This 733 * pointer must be NULL for non-refer actions (i.e. not link nor rename). 734 * @access_request_parent2: Similar to @access_request_parent1 but for a 735 * request involving a source and a destination. This refers to the 736 * destination, except in case of RENAME_EXCHANGE where it also refers to 737 * the source. Must be set to 0 when using a simple path request. 738 * @layer_masks_parent2: Similar to @layer_masks_parent1 but for a refer 739 * action. This must be NULL otherwise. 740 * @log_request_parent2: Audit request to fill if the related access is denied. 741 * @dentry_child2: Dentry to the initial child of the parent2 path. This 742 * pointer is only set for RENAME_EXCHANGE actions and must be NULL 743 * otherwise. 744 * 745 * This helper first checks that the destination has a superset of restrictions 746 * compared to the source (if any) for a common path. Because of 747 * RENAME_EXCHANGE actions, source and destinations may be swapped. It then 748 * checks that the collected accesses and the remaining ones are enough to 749 * allow the request. 750 * 751 * Returns: 752 * - true if the access request is granted; 753 * - false otherwise. 754 */ 755 static bool is_access_to_paths_allowed( 756 const struct landlock_ruleset *const domain, 757 const struct path *const path, 758 const access_mask_t access_request_parent1, 759 layer_mask_t (*const layer_masks_parent1)[LANDLOCK_NUM_ACCESS_FS], 760 struct landlock_request *const log_request_parent1, 761 struct dentry *const dentry_child1, 762 const access_mask_t access_request_parent2, 763 layer_mask_t (*const layer_masks_parent2)[LANDLOCK_NUM_ACCESS_FS], 764 struct landlock_request *const log_request_parent2, 765 struct dentry *const dentry_child2) 766 { 767 bool allowed_parent1 = false, allowed_parent2 = false, is_dom_check, 768 child1_is_directory = true, child2_is_directory = true; 769 struct path walker_path; 770 access_mask_t access_masked_parent1, access_masked_parent2; 771 layer_mask_t _layer_masks_child1[LANDLOCK_NUM_ACCESS_FS], 772 _layer_masks_child2[LANDLOCK_NUM_ACCESS_FS]; 773 layer_mask_t(*layer_masks_child1)[LANDLOCK_NUM_ACCESS_FS] = NULL, 774 (*layer_masks_child2)[LANDLOCK_NUM_ACCESS_FS] = NULL; 775 776 if (!access_request_parent1 && !access_request_parent2) 777 return true; 778 779 if (WARN_ON_ONCE(!path)) 780 return true; 781 782 if (is_nouser_or_private(path->dentry)) 783 return true; 784 785 if (WARN_ON_ONCE(!layer_masks_parent1)) 786 return false; 787 788 allowed_parent1 = is_layer_masks_allowed(layer_masks_parent1); 789 790 if (unlikely(layer_masks_parent2)) { 791 if (WARN_ON_ONCE(!dentry_child1)) 792 return false; 793 794 allowed_parent2 = is_layer_masks_allowed(layer_masks_parent2); 795 796 /* 797 * For a double request, first check for potential privilege 798 * escalation by looking at domain handled accesses (which are 799 * a superset of the meaningful requested accesses). 800 */ 801 access_masked_parent1 = access_masked_parent2 = 802 landlock_union_access_masks(domain).fs; 803 is_dom_check = true; 804 } else { 805 if (WARN_ON_ONCE(dentry_child1 || dentry_child2)) 806 return false; 807 /* For a simple request, only check for requested accesses. */ 808 access_masked_parent1 = access_request_parent1; 809 access_masked_parent2 = access_request_parent2; 810 is_dom_check = false; 811 } 812 813 if (unlikely(dentry_child1)) { 814 landlock_unmask_layers( 815 find_rule(domain, dentry_child1), 816 landlock_init_layer_masks( 817 domain, LANDLOCK_MASK_ACCESS_FS, 818 &_layer_masks_child1, LANDLOCK_KEY_INODE), 819 &_layer_masks_child1, ARRAY_SIZE(_layer_masks_child1)); 820 layer_masks_child1 = &_layer_masks_child1; 821 child1_is_directory = d_is_dir(dentry_child1); 822 } 823 if (unlikely(dentry_child2)) { 824 landlock_unmask_layers( 825 find_rule(domain, dentry_child2), 826 landlock_init_layer_masks( 827 domain, LANDLOCK_MASK_ACCESS_FS, 828 &_layer_masks_child2, LANDLOCK_KEY_INODE), 829 &_layer_masks_child2, ARRAY_SIZE(_layer_masks_child2)); 830 layer_masks_child2 = &_layer_masks_child2; 831 child2_is_directory = d_is_dir(dentry_child2); 832 } 833 834 walker_path = *path; 835 path_get(&walker_path); 836 /* 837 * We need to walk through all the hierarchy to not miss any relevant 838 * restriction. 839 */ 840 while (true) { 841 const struct landlock_rule *rule; 842 843 /* 844 * If at least all accesses allowed on the destination are 845 * already allowed on the source, respectively if there is at 846 * least as much as restrictions on the destination than on the 847 * source, then we can safely refer files from the source to 848 * the destination without risking a privilege escalation. 849 * This also applies in the case of RENAME_EXCHANGE, which 850 * implies checks on both direction. This is crucial for 851 * standalone multilayered security policies. Furthermore, 852 * this helps avoid policy writers to shoot themselves in the 853 * foot. 854 */ 855 if (unlikely(is_dom_check && 856 no_more_access( 857 layer_masks_parent1, layer_masks_child1, 858 child1_is_directory, layer_masks_parent2, 859 layer_masks_child2, 860 child2_is_directory))) { 861 /* 862 * Now, downgrades the remaining checks from domain 863 * handled accesses to requested accesses. 864 */ 865 is_dom_check = false; 866 access_masked_parent1 = access_request_parent1; 867 access_masked_parent2 = access_request_parent2; 868 869 allowed_parent1 = 870 allowed_parent1 || 871 scope_to_request(access_masked_parent1, 872 layer_masks_parent1); 873 allowed_parent2 = 874 allowed_parent2 || 875 scope_to_request(access_masked_parent2, 876 layer_masks_parent2); 877 878 /* Stops when all accesses are granted. */ 879 if (allowed_parent1 && allowed_parent2) 880 break; 881 } 882 883 rule = find_rule(domain, walker_path.dentry); 884 allowed_parent1 = allowed_parent1 || 885 landlock_unmask_layers( 886 rule, access_masked_parent1, 887 layer_masks_parent1, 888 ARRAY_SIZE(*layer_masks_parent1)); 889 allowed_parent2 = allowed_parent2 || 890 landlock_unmask_layers( 891 rule, access_masked_parent2, 892 layer_masks_parent2, 893 ARRAY_SIZE(*layer_masks_parent2)); 894 895 /* Stops when a rule from each layer grants access. */ 896 if (allowed_parent1 && allowed_parent2) 897 break; 898 899 jump_up: 900 if (walker_path.dentry == walker_path.mnt->mnt_root) { 901 if (follow_up(&walker_path)) { 902 /* Ignores hidden mount points. */ 903 goto jump_up; 904 } else { 905 /* 906 * Stops at the real root. Denies access 907 * because not all layers have granted access. 908 */ 909 break; 910 } 911 } 912 913 if (unlikely(IS_ROOT(walker_path.dentry))) { 914 if (likely(walker_path.mnt->mnt_flags & MNT_INTERNAL)) { 915 /* 916 * Stops and allows access when reaching disconnected root 917 * directories that are part of internal filesystems (e.g. nsfs, 918 * which is reachable through /proc/<pid>/ns/<namespace>). 919 */ 920 allowed_parent1 = true; 921 allowed_parent2 = true; 922 break; 923 } 924 925 /* 926 * We reached a disconnected root directory from a bind mount. 927 * Let's continue the walk with the mount point we missed. 928 */ 929 dput(walker_path.dentry); 930 walker_path.dentry = walker_path.mnt->mnt_root; 931 dget(walker_path.dentry); 932 } else { 933 struct dentry *const parent_dentry = 934 dget_parent(walker_path.dentry); 935 936 dput(walker_path.dentry); 937 walker_path.dentry = parent_dentry; 938 } 939 } 940 path_put(&walker_path); 941 942 if (!allowed_parent1) { 943 log_request_parent1->type = LANDLOCK_REQUEST_FS_ACCESS; 944 log_request_parent1->audit.type = LSM_AUDIT_DATA_PATH; 945 log_request_parent1->audit.u.path = *path; 946 log_request_parent1->access = access_masked_parent1; 947 log_request_parent1->layer_masks = layer_masks_parent1; 948 log_request_parent1->layer_masks_size = 949 ARRAY_SIZE(*layer_masks_parent1); 950 } 951 952 if (!allowed_parent2) { 953 log_request_parent2->type = LANDLOCK_REQUEST_FS_ACCESS; 954 log_request_parent2->audit.type = LSM_AUDIT_DATA_PATH; 955 log_request_parent2->audit.u.path = *path; 956 log_request_parent2->access = access_masked_parent2; 957 log_request_parent2->layer_masks = layer_masks_parent2; 958 log_request_parent2->layer_masks_size = 959 ARRAY_SIZE(*layer_masks_parent2); 960 } 961 return allowed_parent1 && allowed_parent2; 962 } 963 964 static int current_check_access_path(const struct path *const path, 965 access_mask_t access_request) 966 { 967 const struct access_masks masks = { 968 .fs = access_request, 969 }; 970 const struct landlock_cred_security *const subject = 971 landlock_get_applicable_subject(current_cred(), masks, NULL); 972 layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {}; 973 struct landlock_request request = {}; 974 975 if (!subject) 976 return 0; 977 978 access_request = landlock_init_layer_masks(subject->domain, 979 access_request, &layer_masks, 980 LANDLOCK_KEY_INODE); 981 if (is_access_to_paths_allowed(subject->domain, path, access_request, 982 &layer_masks, &request, NULL, 0, NULL, 983 NULL, NULL)) 984 return 0; 985 986 landlock_log_denial(subject, &request); 987 return -EACCES; 988 } 989 990 static __attribute_const__ access_mask_t get_mode_access(const umode_t mode) 991 { 992 switch (mode & S_IFMT) { 993 case S_IFLNK: 994 return LANDLOCK_ACCESS_FS_MAKE_SYM; 995 case S_IFDIR: 996 return LANDLOCK_ACCESS_FS_MAKE_DIR; 997 case S_IFCHR: 998 return LANDLOCK_ACCESS_FS_MAKE_CHAR; 999 case S_IFBLK: 1000 return LANDLOCK_ACCESS_FS_MAKE_BLOCK; 1001 case S_IFIFO: 1002 return LANDLOCK_ACCESS_FS_MAKE_FIFO; 1003 case S_IFSOCK: 1004 return LANDLOCK_ACCESS_FS_MAKE_SOCK; 1005 case S_IFREG: 1006 case 0: 1007 /* A zero mode translates to S_IFREG. */ 1008 default: 1009 /* Treats weird files as regular files. */ 1010 return LANDLOCK_ACCESS_FS_MAKE_REG; 1011 } 1012 } 1013 1014 static access_mask_t maybe_remove(const struct dentry *const dentry) 1015 { 1016 if (d_is_negative(dentry)) 1017 return 0; 1018 return d_is_dir(dentry) ? LANDLOCK_ACCESS_FS_REMOVE_DIR : 1019 LANDLOCK_ACCESS_FS_REMOVE_FILE; 1020 } 1021 1022 /** 1023 * collect_domain_accesses - Walk through a file path and collect accesses 1024 * 1025 * @domain: Domain to check against. 1026 * @mnt_root: Last directory to check. 1027 * @dir: Directory to start the walk from. 1028 * @layer_masks_dom: Where to store the collected accesses. 1029 * 1030 * This helper is useful to begin a path walk from the @dir directory to a 1031 * @mnt_root directory used as a mount point. This mount point is the common 1032 * ancestor between the source and the destination of a renamed and linked 1033 * file. While walking from @dir to @mnt_root, we record all the domain's 1034 * allowed accesses in @layer_masks_dom. 1035 * 1036 * Because of disconnected directories, this walk may not reach @mnt_dir. In 1037 * this case, the walk will continue to @mnt_dir after this call. 1038 * 1039 * This is similar to is_access_to_paths_allowed() but much simpler because it 1040 * only handles walking on the same mount point and only checks one set of 1041 * accesses. 1042 * 1043 * Returns: 1044 * - true if all the domain access rights are allowed for @dir; 1045 * - false if the walk reached @mnt_root. 1046 */ 1047 static bool collect_domain_accesses( 1048 const struct landlock_ruleset *const domain, 1049 const struct dentry *const mnt_root, struct dentry *dir, 1050 layer_mask_t (*const layer_masks_dom)[LANDLOCK_NUM_ACCESS_FS]) 1051 { 1052 unsigned long access_dom; 1053 bool ret = false; 1054 1055 if (WARN_ON_ONCE(!domain || !mnt_root || !dir || !layer_masks_dom)) 1056 return true; 1057 if (is_nouser_or_private(dir)) 1058 return true; 1059 1060 access_dom = landlock_init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS, 1061 layer_masks_dom, 1062 LANDLOCK_KEY_INODE); 1063 1064 dget(dir); 1065 while (true) { 1066 struct dentry *parent_dentry; 1067 1068 /* Gets all layers allowing all domain accesses. */ 1069 if (landlock_unmask_layers(find_rule(domain, dir), access_dom, 1070 layer_masks_dom, 1071 ARRAY_SIZE(*layer_masks_dom))) { 1072 /* 1073 * Stops when all handled accesses are allowed by at 1074 * least one rule in each layer. 1075 */ 1076 ret = true; 1077 break; 1078 } 1079 1080 /* 1081 * Stops at the mount point or the filesystem root for a disconnected 1082 * directory. 1083 */ 1084 if (dir == mnt_root || unlikely(IS_ROOT(dir))) 1085 break; 1086 1087 parent_dentry = dget_parent(dir); 1088 dput(dir); 1089 dir = parent_dentry; 1090 } 1091 dput(dir); 1092 return ret; 1093 } 1094 1095 /** 1096 * current_check_refer_path - Check if a rename or link action is allowed 1097 * 1098 * @old_dentry: File or directory requested to be moved or linked. 1099 * @new_dir: Destination parent directory. 1100 * @new_dentry: Destination file or directory. 1101 * @removable: Sets to true if it is a rename operation. 1102 * @exchange: Sets to true if it is a rename operation with RENAME_EXCHANGE. 1103 * 1104 * Because of its unprivileged constraints, Landlock relies on file hierarchies 1105 * (and not only inodes) to tie access rights to files. Being able to link or 1106 * rename a file hierarchy brings some challenges. Indeed, moving or linking a 1107 * file (i.e. creating a new reference to an inode) can have an impact on the 1108 * actions allowed for a set of files if it would change its parent directory 1109 * (i.e. reparenting). 1110 * 1111 * To avoid trivial access right bypasses, Landlock first checks if the file or 1112 * directory requested to be moved would gain new access rights inherited from 1113 * its new hierarchy. Before returning any error, Landlock then checks that 1114 * the parent source hierarchy and the destination hierarchy would allow the 1115 * link or rename action. If it is not the case, an error with EACCES is 1116 * returned to inform user space that there is no way to remove or create the 1117 * requested source file type. If it should be allowed but the new inherited 1118 * access rights would be greater than the source access rights, then the 1119 * kernel returns an error with EXDEV. Prioritizing EACCES over EXDEV enables 1120 * user space to abort the whole operation if there is no way to do it, or to 1121 * manually copy the source to the destination if this remains allowed, e.g. 1122 * because file creation is allowed on the destination directory but not direct 1123 * linking. 1124 * 1125 * To achieve this goal, the kernel needs to compare two file hierarchies: the 1126 * one identifying the source file or directory (including itself), and the 1127 * destination one. This can be seen as a multilayer partial ordering problem. 1128 * The kernel walks through these paths and collects in a matrix the access 1129 * rights that are denied per layer. These matrices are then compared to see 1130 * if the destination one has more (or the same) restrictions as the source 1131 * one. If this is the case, the requested action will not return EXDEV, which 1132 * doesn't mean the action is allowed. The parent hierarchy of the source 1133 * (i.e. parent directory), and the destination hierarchy must also be checked 1134 * to verify that they explicitly allow such action (i.e. referencing, 1135 * creation and potentially removal rights). The kernel implementation is then 1136 * required to rely on potentially four matrices of access rights: one for the 1137 * source file or directory (i.e. the child), a potentially other one for the 1138 * other source/destination (in case of RENAME_EXCHANGE), one for the source 1139 * parent hierarchy and a last one for the destination hierarchy. These 1140 * ephemeral matrices take some space on the stack, which limits the number of 1141 * layers to a deemed reasonable number: 16. 1142 * 1143 * Returns: 1144 * - 0 if access is allowed; 1145 * - -EXDEV if @old_dentry would inherit new access rights from @new_dir; 1146 * - -EACCES if file removal or creation is denied. 1147 */ 1148 static int current_check_refer_path(struct dentry *const old_dentry, 1149 const struct path *const new_dir, 1150 struct dentry *const new_dentry, 1151 const bool removable, const bool exchange) 1152 { 1153 const struct landlock_cred_security *const subject = 1154 landlock_get_applicable_subject(current_cred(), any_fs, NULL); 1155 bool allow_parent1, allow_parent2; 1156 access_mask_t access_request_parent1, access_request_parent2; 1157 struct path mnt_dir; 1158 struct dentry *old_parent; 1159 layer_mask_t layer_masks_parent1[LANDLOCK_NUM_ACCESS_FS] = {}, 1160 layer_masks_parent2[LANDLOCK_NUM_ACCESS_FS] = {}; 1161 struct landlock_request request1 = {}, request2 = {}; 1162 1163 if (!subject) 1164 return 0; 1165 1166 if (unlikely(d_is_negative(old_dentry))) 1167 return -ENOENT; 1168 if (exchange) { 1169 if (unlikely(d_is_negative(new_dentry))) 1170 return -ENOENT; 1171 access_request_parent1 = 1172 get_mode_access(d_backing_inode(new_dentry)->i_mode); 1173 } else { 1174 access_request_parent1 = 0; 1175 } 1176 access_request_parent2 = 1177 get_mode_access(d_backing_inode(old_dentry)->i_mode); 1178 if (removable) { 1179 access_request_parent1 |= maybe_remove(old_dentry); 1180 access_request_parent2 |= maybe_remove(new_dentry); 1181 } 1182 1183 /* The mount points are the same for old and new paths, cf. EXDEV. */ 1184 if (old_dentry->d_parent == new_dir->dentry) { 1185 /* 1186 * The LANDLOCK_ACCESS_FS_REFER access right is not required 1187 * for same-directory referer (i.e. no reparenting). 1188 */ 1189 access_request_parent1 = landlock_init_layer_masks( 1190 subject->domain, 1191 access_request_parent1 | access_request_parent2, 1192 &layer_masks_parent1, LANDLOCK_KEY_INODE); 1193 if (is_access_to_paths_allowed(subject->domain, new_dir, 1194 access_request_parent1, 1195 &layer_masks_parent1, &request1, 1196 NULL, 0, NULL, NULL, NULL)) 1197 return 0; 1198 1199 landlock_log_denial(subject, &request1); 1200 return -EACCES; 1201 } 1202 1203 access_request_parent1 |= LANDLOCK_ACCESS_FS_REFER; 1204 access_request_parent2 |= LANDLOCK_ACCESS_FS_REFER; 1205 1206 /* Saves the common mount point. */ 1207 mnt_dir.mnt = new_dir->mnt; 1208 mnt_dir.dentry = new_dir->mnt->mnt_root; 1209 1210 /* 1211 * old_dentry may be the root of the common mount point and 1212 * !IS_ROOT(old_dentry) at the same time (e.g. with open_tree() and 1213 * OPEN_TREE_CLONE). We do not need to call dget(old_parent) because 1214 * we keep a reference to old_dentry. 1215 */ 1216 old_parent = (old_dentry == mnt_dir.dentry) ? old_dentry : 1217 old_dentry->d_parent; 1218 1219 /* new_dir->dentry is equal to new_dentry->d_parent */ 1220 allow_parent1 = collect_domain_accesses(subject->domain, mnt_dir.dentry, 1221 old_parent, 1222 &layer_masks_parent1); 1223 allow_parent2 = collect_domain_accesses(subject->domain, mnt_dir.dentry, 1224 new_dir->dentry, 1225 &layer_masks_parent2); 1226 1227 if (allow_parent1 && allow_parent2) 1228 return 0; 1229 1230 /* 1231 * To be able to compare source and destination domain access rights, 1232 * take into account the @old_dentry access rights aggregated with its 1233 * parent access rights. This will be useful to compare with the 1234 * destination parent access rights. 1235 */ 1236 if (is_access_to_paths_allowed( 1237 subject->domain, &mnt_dir, access_request_parent1, 1238 &layer_masks_parent1, &request1, old_dentry, 1239 access_request_parent2, &layer_masks_parent2, &request2, 1240 exchange ? new_dentry : NULL)) 1241 return 0; 1242 1243 if (request1.access) { 1244 request1.audit.u.path.dentry = old_parent; 1245 landlock_log_denial(subject, &request1); 1246 } 1247 if (request2.access) { 1248 request2.audit.u.path.dentry = new_dir->dentry; 1249 landlock_log_denial(subject, &request2); 1250 } 1251 1252 /* 1253 * This prioritizes EACCES over EXDEV for all actions, including 1254 * renames with RENAME_EXCHANGE. 1255 */ 1256 if (likely(is_eacces(&layer_masks_parent1, access_request_parent1) || 1257 is_eacces(&layer_masks_parent2, access_request_parent2))) 1258 return -EACCES; 1259 1260 /* 1261 * Gracefully forbids reparenting if the destination directory 1262 * hierarchy is not a superset of restrictions of the source directory 1263 * hierarchy, or if LANDLOCK_ACCESS_FS_REFER is not allowed by the 1264 * source or the destination. 1265 */ 1266 return -EXDEV; 1267 } 1268 1269 /* Inode hooks */ 1270 1271 static void hook_inode_free_security_rcu(void *inode_security) 1272 { 1273 struct landlock_inode_security *inode_sec; 1274 1275 /* 1276 * All inodes must already have been untied from their object by 1277 * release_inode() or hook_sb_delete(). 1278 */ 1279 inode_sec = inode_security + landlock_blob_sizes.lbs_inode; 1280 WARN_ON_ONCE(inode_sec->object); 1281 } 1282 1283 /* Super-block hooks */ 1284 1285 /* 1286 * Release the inodes used in a security policy. 1287 * 1288 * Cf. fsnotify_unmount_inodes() and evict_inodes() 1289 */ 1290 static void hook_sb_delete(struct super_block *const sb) 1291 { 1292 struct inode *inode, *prev_inode = NULL; 1293 1294 if (!landlock_initialized) 1295 return; 1296 1297 spin_lock(&sb->s_inode_list_lock); 1298 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { 1299 struct landlock_object *object; 1300 1301 /* Only handles referenced inodes. */ 1302 if (!icount_read(inode)) 1303 continue; 1304 1305 /* 1306 * Protects against concurrent modification of inode (e.g. 1307 * from get_inode_object()). 1308 */ 1309 spin_lock(&inode->i_lock); 1310 /* 1311 * Checks I_FREEING and I_WILL_FREE to protect against a race 1312 * condition when release_inode() just called iput(), which 1313 * could lead to a NULL dereference of inode->security or a 1314 * second call to iput() for the same Landlock object. Also 1315 * checks I_NEW because such inode cannot be tied to an object. 1316 */ 1317 if (inode_state_read(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) { 1318 spin_unlock(&inode->i_lock); 1319 continue; 1320 } 1321 1322 rcu_read_lock(); 1323 object = rcu_dereference(landlock_inode(inode)->object); 1324 if (!object) { 1325 rcu_read_unlock(); 1326 spin_unlock(&inode->i_lock); 1327 continue; 1328 } 1329 /* Keeps a reference to this inode until the next loop walk. */ 1330 __iget(inode); 1331 spin_unlock(&inode->i_lock); 1332 1333 /* 1334 * If there is no concurrent release_inode() ongoing, then we 1335 * are in charge of calling iput() on this inode, otherwise we 1336 * will just wait for it to finish. 1337 */ 1338 spin_lock(&object->lock); 1339 if (object->underobj == inode) { 1340 object->underobj = NULL; 1341 spin_unlock(&object->lock); 1342 rcu_read_unlock(); 1343 1344 /* 1345 * Because object->underobj was not NULL, 1346 * release_inode() and get_inode_object() guarantee 1347 * that it is safe to reset 1348 * landlock_inode(inode)->object while it is not NULL. 1349 * It is therefore not necessary to lock inode->i_lock. 1350 */ 1351 rcu_assign_pointer(landlock_inode(inode)->object, NULL); 1352 /* 1353 * At this point, we own the ihold() reference that was 1354 * originally set up by get_inode_object() and the 1355 * __iget() reference that we just set in this loop 1356 * walk. Therefore there are at least two references 1357 * on the inode. 1358 */ 1359 iput_not_last(inode); 1360 } else { 1361 spin_unlock(&object->lock); 1362 rcu_read_unlock(); 1363 } 1364 1365 if (prev_inode) { 1366 /* 1367 * At this point, we still own the __iget() reference 1368 * that we just set in this loop walk. Therefore we 1369 * can drop the list lock and know that the inode won't 1370 * disappear from under us until the next loop walk. 1371 */ 1372 spin_unlock(&sb->s_inode_list_lock); 1373 /* 1374 * We can now actually put the inode reference from the 1375 * previous loop walk, which is not needed anymore. 1376 */ 1377 iput(prev_inode); 1378 cond_resched(); 1379 spin_lock(&sb->s_inode_list_lock); 1380 } 1381 prev_inode = inode; 1382 } 1383 spin_unlock(&sb->s_inode_list_lock); 1384 1385 /* Puts the inode reference from the last loop walk, if any. */ 1386 if (prev_inode) 1387 iput(prev_inode); 1388 /* Waits for pending iput() in release_inode(). */ 1389 wait_var_event(&landlock_superblock(sb)->inode_refs, 1390 !atomic_long_read(&landlock_superblock(sb)->inode_refs)); 1391 } 1392 1393 static void 1394 log_fs_change_topology_path(const struct landlock_cred_security *const subject, 1395 size_t handle_layer, const struct path *const path) 1396 { 1397 landlock_log_denial(subject, &(struct landlock_request) { 1398 .type = LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY, 1399 .audit = { 1400 .type = LSM_AUDIT_DATA_PATH, 1401 .u.path = *path, 1402 }, 1403 .layer_plus_one = handle_layer + 1, 1404 }); 1405 } 1406 1407 static void log_fs_change_topology_dentry( 1408 const struct landlock_cred_security *const subject, size_t handle_layer, 1409 struct dentry *const dentry) 1410 { 1411 landlock_log_denial(subject, &(struct landlock_request) { 1412 .type = LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY, 1413 .audit = { 1414 .type = LSM_AUDIT_DATA_DENTRY, 1415 .u.dentry = dentry, 1416 }, 1417 .layer_plus_one = handle_layer + 1, 1418 }); 1419 } 1420 1421 /* 1422 * Because a Landlock security policy is defined according to the filesystem 1423 * topology (i.e. the mount namespace), changing it may grant access to files 1424 * not previously allowed. 1425 * 1426 * To make it simple, deny any filesystem topology modification by landlocked 1427 * processes. Non-landlocked processes may still change the namespace of a 1428 * landlocked process, but this kind of threat must be handled by a system-wide 1429 * access-control security policy. 1430 * 1431 * This could be lifted in the future if Landlock can safely handle mount 1432 * namespace updates requested by a landlocked process. Indeed, we could 1433 * update the current domain (which is currently read-only) by taking into 1434 * account the accesses of the source and the destination of a new mount point. 1435 * However, it would also require to make all the child domains dynamically 1436 * inherit these new constraints. Anyway, for backward compatibility reasons, 1437 * a dedicated user space option would be required (e.g. as a ruleset flag). 1438 */ 1439 static int hook_sb_mount(const char *const dev_name, 1440 const struct path *const path, const char *const type, 1441 const unsigned long flags, void *const data) 1442 { 1443 size_t handle_layer; 1444 const struct landlock_cred_security *const subject = 1445 landlock_get_applicable_subject(current_cred(), any_fs, 1446 &handle_layer); 1447 1448 if (!subject) 1449 return 0; 1450 1451 log_fs_change_topology_path(subject, handle_layer, path); 1452 return -EPERM; 1453 } 1454 1455 static int hook_move_mount(const struct path *const from_path, 1456 const struct path *const to_path) 1457 { 1458 size_t handle_layer; 1459 const struct landlock_cred_security *const subject = 1460 landlock_get_applicable_subject(current_cred(), any_fs, 1461 &handle_layer); 1462 1463 if (!subject) 1464 return 0; 1465 1466 log_fs_change_topology_path(subject, handle_layer, to_path); 1467 return -EPERM; 1468 } 1469 1470 /* 1471 * Removing a mount point may reveal a previously hidden file hierarchy, which 1472 * may then grant access to files, which may have previously been forbidden. 1473 */ 1474 static int hook_sb_umount(struct vfsmount *const mnt, const int flags) 1475 { 1476 size_t handle_layer; 1477 const struct landlock_cred_security *const subject = 1478 landlock_get_applicable_subject(current_cred(), any_fs, 1479 &handle_layer); 1480 1481 if (!subject) 1482 return 0; 1483 1484 log_fs_change_topology_dentry(subject, handle_layer, mnt->mnt_root); 1485 return -EPERM; 1486 } 1487 1488 static int hook_sb_remount(struct super_block *const sb, void *const mnt_opts) 1489 { 1490 size_t handle_layer; 1491 const struct landlock_cred_security *const subject = 1492 landlock_get_applicable_subject(current_cred(), any_fs, 1493 &handle_layer); 1494 1495 if (!subject) 1496 return 0; 1497 1498 log_fs_change_topology_dentry(subject, handle_layer, sb->s_root); 1499 return -EPERM; 1500 } 1501 1502 /* 1503 * pivot_root(2), like mount(2), changes the current mount namespace. It must 1504 * then be forbidden for a landlocked process. 1505 * 1506 * However, chroot(2) may be allowed because it only changes the relative root 1507 * directory of the current process. Moreover, it can be used to restrict the 1508 * view of the filesystem. 1509 */ 1510 static int hook_sb_pivotroot(const struct path *const old_path, 1511 const struct path *const new_path) 1512 { 1513 size_t handle_layer; 1514 const struct landlock_cred_security *const subject = 1515 landlock_get_applicable_subject(current_cred(), any_fs, 1516 &handle_layer); 1517 1518 if (!subject) 1519 return 0; 1520 1521 log_fs_change_topology_path(subject, handle_layer, new_path); 1522 return -EPERM; 1523 } 1524 1525 /* Path hooks */ 1526 1527 static int hook_path_link(struct dentry *const old_dentry, 1528 const struct path *const new_dir, 1529 struct dentry *const new_dentry) 1530 { 1531 return current_check_refer_path(old_dentry, new_dir, new_dentry, false, 1532 false); 1533 } 1534 1535 static int hook_path_rename(const struct path *const old_dir, 1536 struct dentry *const old_dentry, 1537 const struct path *const new_dir, 1538 struct dentry *const new_dentry, 1539 const unsigned int flags) 1540 { 1541 /* old_dir refers to old_dentry->d_parent and new_dir->mnt */ 1542 return current_check_refer_path(old_dentry, new_dir, new_dentry, true, 1543 !!(flags & RENAME_EXCHANGE)); 1544 } 1545 1546 static int hook_path_mkdir(const struct path *const dir, 1547 struct dentry *const dentry, const umode_t mode) 1548 { 1549 return current_check_access_path(dir, LANDLOCK_ACCESS_FS_MAKE_DIR); 1550 } 1551 1552 static int hook_path_mknod(const struct path *const dir, 1553 struct dentry *const dentry, const umode_t mode, 1554 const unsigned int dev) 1555 { 1556 return current_check_access_path(dir, get_mode_access(mode)); 1557 } 1558 1559 static int hook_path_symlink(const struct path *const dir, 1560 struct dentry *const dentry, 1561 const char *const old_name) 1562 { 1563 return current_check_access_path(dir, LANDLOCK_ACCESS_FS_MAKE_SYM); 1564 } 1565 1566 static int hook_path_unlink(const struct path *const dir, 1567 struct dentry *const dentry) 1568 { 1569 return current_check_access_path(dir, LANDLOCK_ACCESS_FS_REMOVE_FILE); 1570 } 1571 1572 static int hook_path_rmdir(const struct path *const dir, 1573 struct dentry *const dentry) 1574 { 1575 return current_check_access_path(dir, LANDLOCK_ACCESS_FS_REMOVE_DIR); 1576 } 1577 1578 static int hook_path_truncate(const struct path *const path) 1579 { 1580 return current_check_access_path(path, LANDLOCK_ACCESS_FS_TRUNCATE); 1581 } 1582 1583 /* File hooks */ 1584 1585 /** 1586 * get_required_file_open_access - Get access needed to open a file 1587 * 1588 * @file: File being opened. 1589 * 1590 * Returns the access rights that are required for opening the given file, 1591 * depending on the file type and open mode. 1592 */ 1593 static access_mask_t 1594 get_required_file_open_access(const struct file *const file) 1595 { 1596 access_mask_t access = 0; 1597 1598 if (file->f_mode & FMODE_READ) { 1599 /* A directory can only be opened in read mode. */ 1600 if (S_ISDIR(file_inode(file)->i_mode)) 1601 return LANDLOCK_ACCESS_FS_READ_DIR; 1602 access = LANDLOCK_ACCESS_FS_READ_FILE; 1603 } 1604 if (file->f_mode & FMODE_WRITE) 1605 access |= LANDLOCK_ACCESS_FS_WRITE_FILE; 1606 /* __FMODE_EXEC is indeed part of f_flags, not f_mode. */ 1607 if (file->f_flags & __FMODE_EXEC) 1608 access |= LANDLOCK_ACCESS_FS_EXECUTE; 1609 return access; 1610 } 1611 1612 static int hook_file_alloc_security(struct file *const file) 1613 { 1614 /* 1615 * Grants all access rights, even if most of them are not checked later 1616 * on. It is more consistent. 1617 * 1618 * Notably, file descriptors for regular files can also be acquired 1619 * without going through the file_open hook, for example when using 1620 * memfd_create(2). 1621 */ 1622 landlock_file(file)->allowed_access = LANDLOCK_MASK_ACCESS_FS; 1623 return 0; 1624 } 1625 1626 static bool is_device(const struct file *const file) 1627 { 1628 const struct inode *inode = file_inode(file); 1629 1630 return S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode); 1631 } 1632 1633 static int hook_file_open(struct file *const file) 1634 { 1635 layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {}; 1636 access_mask_t open_access_request, full_access_request, allowed_access, 1637 optional_access; 1638 const struct landlock_cred_security *const subject = 1639 landlock_get_applicable_subject(file->f_cred, any_fs, NULL); 1640 struct landlock_request request = {}; 1641 1642 if (!subject) 1643 return 0; 1644 1645 /* 1646 * Because a file may be opened with O_PATH, get_required_file_open_access() 1647 * may return 0. This case will be handled with a future Landlock 1648 * evolution. 1649 */ 1650 open_access_request = get_required_file_open_access(file); 1651 1652 /* 1653 * We look up more access than what we immediately need for open(), so 1654 * that we can later authorize operations on opened files. 1655 */ 1656 optional_access = LANDLOCK_ACCESS_FS_TRUNCATE; 1657 if (is_device(file)) 1658 optional_access |= LANDLOCK_ACCESS_FS_IOCTL_DEV; 1659 1660 full_access_request = open_access_request | optional_access; 1661 1662 if (is_access_to_paths_allowed( 1663 subject->domain, &file->f_path, 1664 landlock_init_layer_masks(subject->domain, 1665 full_access_request, &layer_masks, 1666 LANDLOCK_KEY_INODE), 1667 &layer_masks, &request, NULL, 0, NULL, NULL, NULL)) { 1668 allowed_access = full_access_request; 1669 } else { 1670 unsigned long access_bit; 1671 const unsigned long access_req = full_access_request; 1672 1673 /* 1674 * Calculate the actual allowed access rights from layer_masks. 1675 * Add each access right to allowed_access which has not been 1676 * vetoed by any layer. 1677 */ 1678 allowed_access = 0; 1679 for_each_set_bit(access_bit, &access_req, 1680 ARRAY_SIZE(layer_masks)) { 1681 if (!layer_masks[access_bit]) 1682 allowed_access |= BIT_ULL(access_bit); 1683 } 1684 } 1685 1686 /* 1687 * For operations on already opened files (i.e. ftruncate()), it is the 1688 * access rights at the time of open() which decide whether the 1689 * operation is permitted. Therefore, we record the relevant subset of 1690 * file access rights in the opened struct file. 1691 */ 1692 landlock_file(file)->allowed_access = allowed_access; 1693 #ifdef CONFIG_AUDIT 1694 landlock_file(file)->deny_masks = landlock_get_deny_masks( 1695 _LANDLOCK_ACCESS_FS_OPTIONAL, optional_access, &layer_masks, 1696 ARRAY_SIZE(layer_masks)); 1697 #endif /* CONFIG_AUDIT */ 1698 1699 if ((open_access_request & allowed_access) == open_access_request) 1700 return 0; 1701 1702 /* Sets access to reflect the actual request. */ 1703 request.access = open_access_request; 1704 landlock_log_denial(subject, &request); 1705 return -EACCES; 1706 } 1707 1708 static int hook_file_truncate(struct file *const file) 1709 { 1710 /* 1711 * Allows truncation if the truncate right was available at the time of 1712 * opening the file, to get a consistent access check as for read, write 1713 * and execute operations. 1714 * 1715 * Note: For checks done based on the file's Landlock allowed access, we 1716 * enforce them independently of whether the current thread is in a 1717 * Landlock domain, so that open files passed between independent 1718 * processes retain their behaviour. 1719 */ 1720 if (landlock_file(file)->allowed_access & LANDLOCK_ACCESS_FS_TRUNCATE) 1721 return 0; 1722 1723 landlock_log_denial(landlock_cred(file->f_cred), &(struct landlock_request) { 1724 .type = LANDLOCK_REQUEST_FS_ACCESS, 1725 .audit = { 1726 .type = LSM_AUDIT_DATA_FILE, 1727 .u.file = file, 1728 }, 1729 .all_existing_optional_access = _LANDLOCK_ACCESS_FS_OPTIONAL, 1730 .access = LANDLOCK_ACCESS_FS_TRUNCATE, 1731 #ifdef CONFIG_AUDIT 1732 .deny_masks = landlock_file(file)->deny_masks, 1733 #endif /* CONFIG_AUDIT */ 1734 }); 1735 return -EACCES; 1736 } 1737 1738 static int hook_file_ioctl_common(const struct file *const file, 1739 const unsigned int cmd, const bool is_compat) 1740 { 1741 access_mask_t allowed_access = landlock_file(file)->allowed_access; 1742 1743 /* 1744 * It is the access rights at the time of opening the file which 1745 * determine whether IOCTL can be used on the opened file later. 1746 * 1747 * The access right is attached to the opened file in hook_file_open(). 1748 */ 1749 if (allowed_access & LANDLOCK_ACCESS_FS_IOCTL_DEV) 1750 return 0; 1751 1752 if (!is_device(file)) 1753 return 0; 1754 1755 if (unlikely(is_compat) ? is_masked_device_ioctl_compat(cmd) : 1756 is_masked_device_ioctl(cmd)) 1757 return 0; 1758 1759 landlock_log_denial(landlock_cred(file->f_cred), &(struct landlock_request) { 1760 .type = LANDLOCK_REQUEST_FS_ACCESS, 1761 .audit = { 1762 .type = LSM_AUDIT_DATA_IOCTL_OP, 1763 .u.op = &(struct lsm_ioctlop_audit) { 1764 .path = file->f_path, 1765 .cmd = cmd, 1766 }, 1767 }, 1768 .all_existing_optional_access = _LANDLOCK_ACCESS_FS_OPTIONAL, 1769 .access = LANDLOCK_ACCESS_FS_IOCTL_DEV, 1770 #ifdef CONFIG_AUDIT 1771 .deny_masks = landlock_file(file)->deny_masks, 1772 #endif /* CONFIG_AUDIT */ 1773 }); 1774 return -EACCES; 1775 } 1776 1777 static int hook_file_ioctl(struct file *file, unsigned int cmd, 1778 unsigned long arg) 1779 { 1780 return hook_file_ioctl_common(file, cmd, false); 1781 } 1782 1783 static int hook_file_ioctl_compat(struct file *file, unsigned int cmd, 1784 unsigned long arg) 1785 { 1786 return hook_file_ioctl_common(file, cmd, true); 1787 } 1788 1789 /* 1790 * Always allow sending signals between threads of the same process. This 1791 * ensures consistency with hook_task_kill(). 1792 */ 1793 static bool control_current_fowner(struct fown_struct *const fown) 1794 { 1795 struct task_struct *p; 1796 1797 /* 1798 * Lock already held by __f_setown(), see commit 26f204380a3c ("fs: Fix 1799 * file_set_fowner LSM hook inconsistencies"). 1800 */ 1801 lockdep_assert_held(&fown->lock); 1802 1803 /* 1804 * Some callers (e.g. fcntl_dirnotify) may not be in an RCU read-side 1805 * critical section. 1806 */ 1807 guard(rcu)(); 1808 p = pid_task(fown->pid, fown->pid_type); 1809 if (!p) 1810 return true; 1811 1812 return !same_thread_group(p, current); 1813 } 1814 1815 static void hook_file_set_fowner(struct file *file) 1816 { 1817 struct landlock_ruleset *prev_dom; 1818 struct landlock_cred_security fown_subject = {}; 1819 size_t fown_layer = 0; 1820 1821 if (control_current_fowner(file_f_owner(file))) { 1822 static const struct access_masks signal_scope = { 1823 .scope = LANDLOCK_SCOPE_SIGNAL, 1824 }; 1825 const struct landlock_cred_security *new_subject = 1826 landlock_get_applicable_subject( 1827 current_cred(), signal_scope, &fown_layer); 1828 if (new_subject) { 1829 landlock_get_ruleset(new_subject->domain); 1830 fown_subject = *new_subject; 1831 } 1832 } 1833 1834 prev_dom = landlock_file(file)->fown_subject.domain; 1835 landlock_file(file)->fown_subject = fown_subject; 1836 #ifdef CONFIG_AUDIT 1837 landlock_file(file)->fown_layer = fown_layer; 1838 #endif /* CONFIG_AUDIT*/ 1839 1840 /* May be called in an RCU read-side critical section. */ 1841 landlock_put_ruleset_deferred(prev_dom); 1842 } 1843 1844 static void hook_file_free_security(struct file *file) 1845 { 1846 landlock_put_ruleset_deferred(landlock_file(file)->fown_subject.domain); 1847 } 1848 1849 static struct security_hook_list landlock_hooks[] __ro_after_init = { 1850 LSM_HOOK_INIT(inode_free_security_rcu, hook_inode_free_security_rcu), 1851 1852 LSM_HOOK_INIT(sb_delete, hook_sb_delete), 1853 LSM_HOOK_INIT(sb_mount, hook_sb_mount), 1854 LSM_HOOK_INIT(move_mount, hook_move_mount), 1855 LSM_HOOK_INIT(sb_umount, hook_sb_umount), 1856 LSM_HOOK_INIT(sb_remount, hook_sb_remount), 1857 LSM_HOOK_INIT(sb_pivotroot, hook_sb_pivotroot), 1858 1859 LSM_HOOK_INIT(path_link, hook_path_link), 1860 LSM_HOOK_INIT(path_rename, hook_path_rename), 1861 LSM_HOOK_INIT(path_mkdir, hook_path_mkdir), 1862 LSM_HOOK_INIT(path_mknod, hook_path_mknod), 1863 LSM_HOOK_INIT(path_symlink, hook_path_symlink), 1864 LSM_HOOK_INIT(path_unlink, hook_path_unlink), 1865 LSM_HOOK_INIT(path_rmdir, hook_path_rmdir), 1866 LSM_HOOK_INIT(path_truncate, hook_path_truncate), 1867 1868 LSM_HOOK_INIT(file_alloc_security, hook_file_alloc_security), 1869 LSM_HOOK_INIT(file_open, hook_file_open), 1870 LSM_HOOK_INIT(file_truncate, hook_file_truncate), 1871 LSM_HOOK_INIT(file_ioctl, hook_file_ioctl), 1872 LSM_HOOK_INIT(file_ioctl_compat, hook_file_ioctl_compat), 1873 LSM_HOOK_INIT(file_set_fowner, hook_file_set_fowner), 1874 LSM_HOOK_INIT(file_free_security, hook_file_free_security), 1875 }; 1876 1877 __init void landlock_add_fs_hooks(void) 1878 { 1879 security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), 1880 &landlock_lsmid); 1881 } 1882 1883 #ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST 1884 1885 /* clang-format off */ 1886 static struct kunit_case test_cases[] = { 1887 KUNIT_CASE(test_no_more_access), 1888 KUNIT_CASE(test_scope_to_request_with_exec_none), 1889 KUNIT_CASE(test_scope_to_request_with_exec_some), 1890 KUNIT_CASE(test_scope_to_request_without_access), 1891 KUNIT_CASE(test_is_eacces_with_none), 1892 KUNIT_CASE(test_is_eacces_with_refer), 1893 KUNIT_CASE(test_is_eacces_with_write), 1894 {} 1895 }; 1896 /* clang-format on */ 1897 1898 static struct kunit_suite test_suite = { 1899 .name = "landlock_fs", 1900 .test_cases = test_cases, 1901 }; 1902 1903 kunit_test_suite(test_suite); 1904 1905 #endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ 1906