1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2011 IBM Corporation 4 * 5 * Author: 6 * Mimi Zohar <zohar@us.ibm.com> 7 */ 8 #include <linux/module.h> 9 #include <linux/init.h> 10 #include <linux/file.h> 11 #include <linux/fs.h> 12 #include <linux/xattr.h> 13 #include <linux/magic.h> 14 #include <linux/ima.h> 15 #include <linux/evm.h> 16 #include <linux/fsverity.h> 17 #include <keys/system_keyring.h> 18 #include <uapi/linux/fsverity.h> 19 20 #include "ima.h" 21 22 #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM 23 static char *ima_appraise_cmdline_default __initdata; 24 core_param(ima_appraise, ima_appraise_cmdline_default, charp, 0); 25 26 void __init ima_appraise_parse_cmdline(void) 27 { 28 const char *str = ima_appraise_cmdline_default; 29 bool sb_state = arch_ima_get_secureboot(); 30 int appraisal_state = ima_appraise; 31 32 if (!str) 33 return; 34 35 if (strncmp(str, "off", 3) == 0) 36 appraisal_state = 0; 37 else if (strncmp(str, "log", 3) == 0) 38 appraisal_state = IMA_APPRAISE_LOG; 39 else if (strncmp(str, "fix", 3) == 0) 40 appraisal_state = IMA_APPRAISE_FIX; 41 else if (strncmp(str, "enforce", 7) == 0) 42 appraisal_state = IMA_APPRAISE_ENFORCE; 43 else 44 pr_err("invalid \"%s\" appraise option", str); 45 46 /* If appraisal state was changed, but secure boot is enabled, 47 * keep its default */ 48 if (sb_state) { 49 if (!(appraisal_state & IMA_APPRAISE_ENFORCE)) 50 pr_info("Secure boot enabled: ignoring ima_appraise=%s option", 51 str); 52 } else { 53 ima_appraise = appraisal_state; 54 } 55 } 56 #endif 57 58 /* 59 * is_ima_appraise_enabled - return appraise status 60 * 61 * Only return enabled, if not in ima_appraise="fix" or "log" modes. 62 */ 63 bool is_ima_appraise_enabled(void) 64 { 65 return ima_appraise & IMA_APPRAISE_ENFORCE; 66 } 67 68 /* 69 * ima_must_appraise - set appraise flag 70 * 71 * Return 1 to appraise or hash 72 */ 73 int ima_must_appraise(struct mnt_idmap *idmap, struct inode *inode, 74 int mask, enum ima_hooks func) 75 { 76 u32 secid; 77 78 if (!ima_appraise) 79 return 0; 80 81 security_current_getsecid_subj(&secid); 82 return ima_match_policy(idmap, inode, current_cred(), secid, 83 func, mask, IMA_APPRAISE | IMA_HASH, NULL, 84 NULL, NULL, NULL); 85 } 86 87 static int ima_fix_xattr(struct dentry *dentry, struct ima_iint_cache *iint) 88 { 89 int rc, offset; 90 u8 algo = iint->ima_hash->algo; 91 92 if (algo <= HASH_ALGO_SHA1) { 93 offset = 1; 94 iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST; 95 } else { 96 offset = 0; 97 iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG; 98 iint->ima_hash->xattr.ng.algo = algo; 99 } 100 rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_IMA, 101 &iint->ima_hash->xattr.data[offset], 102 (sizeof(iint->ima_hash->xattr) - offset) + 103 iint->ima_hash->length, 0); 104 return rc; 105 } 106 107 /* Return specific func appraised cached result */ 108 enum integrity_status ima_get_cache_status(struct ima_iint_cache *iint, 109 enum ima_hooks func) 110 { 111 switch (func) { 112 case MMAP_CHECK: 113 case MMAP_CHECK_REQPROT: 114 return iint->ima_mmap_status; 115 case BPRM_CHECK: 116 return iint->ima_bprm_status; 117 case CREDS_CHECK: 118 return iint->ima_creds_status; 119 case FILE_CHECK: 120 case POST_SETATTR: 121 return iint->ima_file_status; 122 case MODULE_CHECK ... MAX_CHECK - 1: 123 default: 124 return iint->ima_read_status; 125 } 126 } 127 128 static void ima_set_cache_status(struct ima_iint_cache *iint, 129 enum ima_hooks func, 130 enum integrity_status status) 131 { 132 switch (func) { 133 case MMAP_CHECK: 134 case MMAP_CHECK_REQPROT: 135 iint->ima_mmap_status = status; 136 break; 137 case BPRM_CHECK: 138 iint->ima_bprm_status = status; 139 break; 140 case CREDS_CHECK: 141 iint->ima_creds_status = status; 142 break; 143 case FILE_CHECK: 144 case POST_SETATTR: 145 iint->ima_file_status = status; 146 break; 147 case MODULE_CHECK ... MAX_CHECK - 1: 148 default: 149 iint->ima_read_status = status; 150 break; 151 } 152 } 153 154 static void ima_cache_flags(struct ima_iint_cache *iint, enum ima_hooks func) 155 { 156 switch (func) { 157 case MMAP_CHECK: 158 case MMAP_CHECK_REQPROT: 159 iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED); 160 break; 161 case BPRM_CHECK: 162 iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED); 163 break; 164 case CREDS_CHECK: 165 iint->flags |= (IMA_CREDS_APPRAISED | IMA_APPRAISED); 166 break; 167 case FILE_CHECK: 168 case POST_SETATTR: 169 iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED); 170 break; 171 case MODULE_CHECK ... MAX_CHECK - 1: 172 default: 173 iint->flags |= (IMA_READ_APPRAISED | IMA_APPRAISED); 174 break; 175 } 176 } 177 178 enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, 179 int xattr_len) 180 { 181 struct signature_v2_hdr *sig; 182 enum hash_algo ret; 183 184 if (!xattr_value || xattr_len < 2) 185 /* return default hash algo */ 186 return ima_hash_algo; 187 188 switch (xattr_value->type) { 189 case IMA_VERITY_DIGSIG: 190 sig = (typeof(sig))xattr_value; 191 if (sig->version != 3 || xattr_len <= sizeof(*sig) || 192 sig->hash_algo >= HASH_ALGO__LAST) 193 return ima_hash_algo; 194 return sig->hash_algo; 195 case EVM_IMA_XATTR_DIGSIG: 196 sig = (typeof(sig))xattr_value; 197 if (sig->version != 2 || xattr_len <= sizeof(*sig) 198 || sig->hash_algo >= HASH_ALGO__LAST) 199 return ima_hash_algo; 200 return sig->hash_algo; 201 case IMA_XATTR_DIGEST_NG: 202 /* first byte contains algorithm id */ 203 ret = xattr_value->data[0]; 204 if (ret < HASH_ALGO__LAST) 205 return ret; 206 break; 207 case IMA_XATTR_DIGEST: 208 /* this is for backward compatibility */ 209 if (xattr_len == 21) { 210 unsigned int zero = 0; 211 if (!memcmp(&xattr_value->data[16], &zero, 4)) 212 return HASH_ALGO_MD5; 213 else 214 return HASH_ALGO_SHA1; 215 } else if (xattr_len == 17) 216 return HASH_ALGO_MD5; 217 break; 218 } 219 220 /* return default hash algo */ 221 return ima_hash_algo; 222 } 223 224 int ima_read_xattr(struct dentry *dentry, 225 struct evm_ima_xattr_data **xattr_value, int xattr_len) 226 { 227 int ret; 228 229 ret = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_IMA, 230 (char **)xattr_value, xattr_len, GFP_NOFS); 231 if (ret == -EOPNOTSUPP) 232 ret = 0; 233 return ret; 234 } 235 236 /* 237 * calc_file_id_hash - calculate the hash of the ima_file_id struct data 238 * @type: xattr type [enum evm_ima_xattr_type] 239 * @algo: hash algorithm [enum hash_algo] 240 * @digest: pointer to the digest to be hashed 241 * @hash: (out) pointer to the hash 242 * 243 * IMA signature version 3 disambiguates the data that is signed by 244 * indirectly signing the hash of the ima_file_id structure data. 245 * 246 * Signing the ima_file_id struct is currently only supported for 247 * IMA_VERITY_DIGSIG type xattrs. 248 * 249 * Return 0 on success, error code otherwise. 250 */ 251 static int calc_file_id_hash(enum evm_ima_xattr_type type, 252 enum hash_algo algo, const u8 *digest, 253 struct ima_digest_data *hash) 254 { 255 struct ima_file_id file_id = { 256 .hash_type = IMA_VERITY_DIGSIG, .hash_algorithm = algo}; 257 unsigned int unused = HASH_MAX_DIGESTSIZE - hash_digest_size[algo]; 258 259 if (type != IMA_VERITY_DIGSIG) 260 return -EINVAL; 261 262 memcpy(file_id.hash, digest, hash_digest_size[algo]); 263 264 hash->algo = algo; 265 hash->length = hash_digest_size[algo]; 266 267 return ima_calc_buffer_hash(&file_id, sizeof(file_id) - unused, hash); 268 } 269 270 /* 271 * xattr_verify - verify xattr digest or signature 272 * 273 * Verify whether the hash or signature matches the file contents. 274 * 275 * Return 0 on success, error code otherwise. 276 */ 277 static int xattr_verify(enum ima_hooks func, struct ima_iint_cache *iint, 278 struct evm_ima_xattr_data *xattr_value, int xattr_len, 279 enum integrity_status *status, const char **cause) 280 { 281 struct ima_max_digest_data hash; 282 struct signature_v2_hdr *sig; 283 int rc = -EINVAL, hash_start = 0; 284 int mask; 285 286 switch (xattr_value->type) { 287 case IMA_XATTR_DIGEST_NG: 288 /* first byte contains algorithm id */ 289 hash_start = 1; 290 fallthrough; 291 case IMA_XATTR_DIGEST: 292 if (*status != INTEGRITY_PASS_IMMUTABLE) { 293 if (iint->flags & IMA_DIGSIG_REQUIRED) { 294 if (iint->flags & IMA_VERITY_REQUIRED) 295 *cause = "verity-signature-required"; 296 else 297 *cause = "IMA-signature-required"; 298 *status = INTEGRITY_FAIL; 299 break; 300 } 301 clear_bit(IMA_DIGSIG, &iint->atomic_flags); 302 } else { 303 set_bit(IMA_DIGSIG, &iint->atomic_flags); 304 } 305 if (xattr_len - sizeof(xattr_value->type) - hash_start >= 306 iint->ima_hash->length) 307 /* 308 * xattr length may be longer. md5 hash in previous 309 * version occupied 20 bytes in xattr, instead of 16 310 */ 311 rc = memcmp(&xattr_value->data[hash_start], 312 iint->ima_hash->digest, 313 iint->ima_hash->length); 314 else 315 rc = -EINVAL; 316 if (rc) { 317 *cause = "invalid-hash"; 318 *status = INTEGRITY_FAIL; 319 break; 320 } 321 *status = INTEGRITY_PASS; 322 break; 323 case EVM_IMA_XATTR_DIGSIG: 324 set_bit(IMA_DIGSIG, &iint->atomic_flags); 325 326 mask = IMA_DIGSIG_REQUIRED | IMA_VERITY_REQUIRED; 327 if ((iint->flags & mask) == mask) { 328 *cause = "verity-signature-required"; 329 *status = INTEGRITY_FAIL; 330 break; 331 } 332 333 sig = (typeof(sig))xattr_value; 334 if (sig->version >= 3) { 335 *cause = "invalid-signature-version"; 336 *status = INTEGRITY_FAIL; 337 break; 338 } 339 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, 340 (const char *)xattr_value, 341 xattr_len, 342 iint->ima_hash->digest, 343 iint->ima_hash->length); 344 if (rc == -EOPNOTSUPP) { 345 *status = INTEGRITY_UNKNOWN; 346 break; 347 } 348 if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && 349 func == KEXEC_KERNEL_CHECK) 350 rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, 351 (const char *)xattr_value, 352 xattr_len, 353 iint->ima_hash->digest, 354 iint->ima_hash->length); 355 if (rc) { 356 *cause = "invalid-signature"; 357 *status = INTEGRITY_FAIL; 358 } else { 359 *status = INTEGRITY_PASS; 360 } 361 break; 362 case IMA_VERITY_DIGSIG: 363 set_bit(IMA_DIGSIG, &iint->atomic_flags); 364 365 if (iint->flags & IMA_DIGSIG_REQUIRED) { 366 if (!(iint->flags & IMA_VERITY_REQUIRED)) { 367 *cause = "IMA-signature-required"; 368 *status = INTEGRITY_FAIL; 369 break; 370 } 371 } 372 373 sig = (typeof(sig))xattr_value; 374 if (sig->version != 3) { 375 *cause = "invalid-signature-version"; 376 *status = INTEGRITY_FAIL; 377 break; 378 } 379 380 rc = calc_file_id_hash(IMA_VERITY_DIGSIG, iint->ima_hash->algo, 381 iint->ima_hash->digest, 382 container_of(&hash.hdr, 383 struct ima_digest_data, hdr)); 384 if (rc) { 385 *cause = "sigv3-hashing-error"; 386 *status = INTEGRITY_FAIL; 387 break; 388 } 389 390 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, 391 (const char *)xattr_value, 392 xattr_len, hash.digest, 393 hash.hdr.length); 394 if (rc) { 395 *cause = "invalid-verity-signature"; 396 *status = INTEGRITY_FAIL; 397 } else { 398 *status = INTEGRITY_PASS; 399 } 400 401 break; 402 default: 403 *status = INTEGRITY_UNKNOWN; 404 *cause = "unknown-ima-data"; 405 break; 406 } 407 408 return rc; 409 } 410 411 /* 412 * modsig_verify - verify modsig signature 413 * 414 * Verify whether the signature matches the file contents. 415 * 416 * Return 0 on success, error code otherwise. 417 */ 418 static int modsig_verify(enum ima_hooks func, const struct modsig *modsig, 419 enum integrity_status *status, const char **cause) 420 { 421 int rc; 422 423 rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig); 424 if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && 425 func == KEXEC_KERNEL_CHECK) 426 rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM, 427 modsig); 428 if (rc) { 429 *cause = "invalid-signature"; 430 *status = INTEGRITY_FAIL; 431 } else { 432 *status = INTEGRITY_PASS; 433 } 434 435 return rc; 436 } 437 438 /* 439 * ima_check_blacklist - determine if the binary is blacklisted. 440 * 441 * Add the hash of the blacklisted binary to the measurement list, based 442 * on policy. 443 * 444 * Returns -EPERM if the hash is blacklisted. 445 */ 446 int ima_check_blacklist(struct ima_iint_cache *iint, 447 const struct modsig *modsig, int pcr) 448 { 449 enum hash_algo hash_algo; 450 const u8 *digest = NULL; 451 u32 digestsize = 0; 452 int rc = 0; 453 454 if (!(iint->flags & IMA_CHECK_BLACKLIST)) 455 return 0; 456 457 if (iint->flags & IMA_MODSIG_ALLOWED && modsig) { 458 ima_get_modsig_digest(modsig, &hash_algo, &digest, &digestsize); 459 460 rc = is_binary_blacklisted(digest, digestsize); 461 } else if (iint->flags & IMA_DIGSIG_REQUIRED && iint->ima_hash) 462 rc = is_binary_blacklisted(iint->ima_hash->digest, iint->ima_hash->length); 463 464 if ((rc == -EPERM) && (iint->flags & IMA_MEASURE)) 465 process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize, 466 "blacklisted-hash", NONE, 467 pcr, NULL, false, NULL, 0); 468 469 return rc; 470 } 471 472 /* 473 * ima_appraise_measurement - appraise file measurement 474 * 475 * Call evm_verifyxattr() to verify the integrity of 'security.ima'. 476 * Assuming success, compare the xattr hash with the collected measurement. 477 * 478 * Return 0 on success, error code otherwise 479 */ 480 int ima_appraise_measurement(enum ima_hooks func, struct ima_iint_cache *iint, 481 struct file *file, const unsigned char *filename, 482 struct evm_ima_xattr_data *xattr_value, 483 int xattr_len, const struct modsig *modsig) 484 { 485 static const char op[] = "appraise_data"; 486 const char *cause = "unknown"; 487 struct dentry *dentry = file_dentry(file); 488 struct inode *inode = d_backing_inode(dentry); 489 enum integrity_status status = INTEGRITY_UNKNOWN; 490 int rc = xattr_len; 491 bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig; 492 493 /* If not appraising a modsig, we need an xattr. */ 494 if (!(inode->i_opflags & IOP_XATTR) && !try_modsig) 495 return INTEGRITY_UNKNOWN; 496 497 /* If reading the xattr failed and there's no modsig, error out. */ 498 if (rc <= 0 && !try_modsig) { 499 if (rc && rc != -ENODATA) 500 goto out; 501 502 if (iint->flags & IMA_DIGSIG_REQUIRED) { 503 if (iint->flags & IMA_VERITY_REQUIRED) 504 cause = "verity-signature-required"; 505 else 506 cause = "IMA-signature-required"; 507 } else { 508 cause = "missing-hash"; 509 } 510 511 status = INTEGRITY_NOLABEL; 512 if (file->f_mode & FMODE_CREATED) 513 iint->flags |= IMA_NEW_FILE; 514 if ((iint->flags & IMA_NEW_FILE) && 515 (!(iint->flags & IMA_DIGSIG_REQUIRED) || 516 (inode->i_size == 0))) 517 status = INTEGRITY_PASS; 518 goto out; 519 } 520 521 status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, 522 rc < 0 ? 0 : rc); 523 switch (status) { 524 case INTEGRITY_PASS: 525 case INTEGRITY_PASS_IMMUTABLE: 526 case INTEGRITY_UNKNOWN: 527 break; 528 case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ 529 /* It's fine not to have xattrs when using a modsig. */ 530 if (try_modsig) 531 break; 532 fallthrough; 533 case INTEGRITY_NOLABEL: /* No security.evm xattr. */ 534 cause = "missing-HMAC"; 535 goto out; 536 case INTEGRITY_FAIL_IMMUTABLE: 537 set_bit(IMA_DIGSIG, &iint->atomic_flags); 538 cause = "invalid-fail-immutable"; 539 goto out; 540 case INTEGRITY_FAIL: /* Invalid HMAC/signature. */ 541 cause = "invalid-HMAC"; 542 goto out; 543 default: 544 WARN_ONCE(true, "Unexpected integrity status %d\n", status); 545 } 546 547 if (xattr_value) 548 rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, 549 &cause); 550 551 /* 552 * If we have a modsig and either no imasig or the imasig's key isn't 553 * known, then try verifying the modsig. 554 */ 555 if (try_modsig && 556 (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG || 557 rc == -ENOKEY)) 558 rc = modsig_verify(func, modsig, &status, &cause); 559 560 out: 561 /* 562 * File signatures on some filesystems can not be properly verified. 563 * When such filesystems are mounted by an untrusted mounter or on a 564 * system not willing to accept such a risk, fail the file signature 565 * verification. 566 */ 567 if ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) && 568 ((inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) || 569 (iint->flags & IMA_FAIL_UNVERIFIABLE_SIGS))) { 570 status = INTEGRITY_FAIL; 571 cause = "unverifiable-signature"; 572 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, 573 op, cause, rc, 0); 574 } else if (status != INTEGRITY_PASS) { 575 /* Fix mode, but don't replace file signatures. */ 576 if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig && 577 (!xattr_value || 578 xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { 579 if (!ima_fix_xattr(dentry, iint)) 580 status = INTEGRITY_PASS; 581 } 582 583 /* 584 * Permit new files with file/EVM portable signatures, but 585 * without data. 586 */ 587 if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE && 588 test_bit(IMA_DIGSIG, &iint->atomic_flags)) { 589 status = INTEGRITY_PASS; 590 } 591 592 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, 593 op, cause, rc, 0); 594 } else { 595 ima_cache_flags(iint, func); 596 } 597 598 ima_set_cache_status(iint, func, status); 599 return status; 600 } 601 602 /* 603 * ima_update_xattr - update 'security.ima' hash value 604 */ 605 void ima_update_xattr(struct ima_iint_cache *iint, struct file *file) 606 { 607 struct dentry *dentry = file_dentry(file); 608 int rc = 0; 609 610 /* do not collect and update hash for digital signatures */ 611 if (test_bit(IMA_DIGSIG, &iint->atomic_flags)) 612 return; 613 614 if ((iint->ima_file_status != INTEGRITY_PASS) && 615 !(iint->flags & IMA_HASH)) 616 return; 617 618 rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL); 619 if (rc < 0) 620 return; 621 622 inode_lock(file_inode(file)); 623 ima_fix_xattr(dentry, iint); 624 inode_unlock(file_inode(file)); 625 } 626 627 /** 628 * ima_inode_post_setattr - reflect file metadata changes 629 * @idmap: idmap of the mount the inode was found from 630 * @dentry: pointer to the affected dentry 631 * @ia_valid: for the UID and GID status 632 * 633 * Changes to a dentry's metadata might result in needing to appraise. 634 * 635 * This function is called from notify_change(), which expects the caller 636 * to lock the inode's i_mutex. 637 */ 638 static void ima_inode_post_setattr(struct mnt_idmap *idmap, 639 struct dentry *dentry, int ia_valid) 640 { 641 struct inode *inode = d_backing_inode(dentry); 642 struct ima_iint_cache *iint; 643 int action; 644 645 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode) 646 || !(inode->i_opflags & IOP_XATTR)) 647 return; 648 649 action = ima_must_appraise(idmap, inode, MAY_ACCESS, POST_SETATTR); 650 iint = ima_iint_find(inode); 651 if (iint) { 652 set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags); 653 if (!action) 654 clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); 655 } 656 } 657 658 /* 659 * ima_protect_xattr - protect 'security.ima' 660 * 661 * Ensure that not just anyone can modify or remove 'security.ima'. 662 */ 663 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, 664 const void *xattr_value, size_t xattr_value_len) 665 { 666 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) { 667 if (!capable(CAP_SYS_ADMIN)) 668 return -EPERM; 669 return 1; 670 } 671 return 0; 672 } 673 674 static void ima_reset_appraise_flags(struct inode *inode, int digsig) 675 { 676 struct ima_iint_cache *iint; 677 678 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)) 679 return; 680 681 iint = ima_iint_find(inode); 682 if (!iint) 683 return; 684 iint->measured_pcrs = 0; 685 set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags); 686 if (digsig) 687 set_bit(IMA_DIGSIG, &iint->atomic_flags); 688 else 689 clear_bit(IMA_DIGSIG, &iint->atomic_flags); 690 } 691 692 /** 693 * validate_hash_algo() - Block setxattr with unsupported hash algorithms 694 * @dentry: object of the setxattr() 695 * @xattr_value: userland supplied xattr value 696 * @xattr_value_len: length of xattr_value 697 * 698 * The xattr value is mapped to its hash algorithm, and this algorithm 699 * must be built in the kernel for the setxattr to be allowed. 700 * 701 * Emit an audit message when the algorithm is invalid. 702 * 703 * Return: 0 on success, else an error. 704 */ 705 static int validate_hash_algo(struct dentry *dentry, 706 const struct evm_ima_xattr_data *xattr_value, 707 size_t xattr_value_len) 708 { 709 char *path = NULL, *pathbuf = NULL; 710 enum hash_algo xattr_hash_algo; 711 const char *errmsg = "unavailable-hash-algorithm"; 712 unsigned int allowed_hashes; 713 714 xattr_hash_algo = ima_get_hash_algo(xattr_value, xattr_value_len); 715 716 allowed_hashes = atomic_read(&ima_setxattr_allowed_hash_algorithms); 717 718 if (allowed_hashes) { 719 /* success if the algorithm is allowed in the ima policy */ 720 if (allowed_hashes & (1U << xattr_hash_algo)) 721 return 0; 722 723 /* 724 * We use a different audit message when the hash algorithm 725 * is denied by a policy rule, instead of not being built 726 * in the kernel image 727 */ 728 errmsg = "denied-hash-algorithm"; 729 } else { 730 if (likely(xattr_hash_algo == ima_hash_algo)) 731 return 0; 732 733 /* allow any xattr using an algorithm built in the kernel */ 734 if (crypto_has_alg(hash_algo_name[xattr_hash_algo], 0, 0)) 735 return 0; 736 } 737 738 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); 739 if (!pathbuf) 740 return -EACCES; 741 742 path = dentry_path(dentry, pathbuf, PATH_MAX); 743 744 integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path, 745 "set_data", errmsg, -EACCES, 0); 746 747 kfree(pathbuf); 748 749 return -EACCES; 750 } 751 752 static int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, 753 const char *xattr_name, const void *xattr_value, 754 size_t xattr_value_len, int flags) 755 { 756 const struct evm_ima_xattr_data *xvalue = xattr_value; 757 int digsig = 0; 758 int result; 759 int err; 760 761 result = ima_protect_xattr(dentry, xattr_name, xattr_value, 762 xattr_value_len); 763 if (result == 1) { 764 if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST)) 765 return -EINVAL; 766 767 err = validate_hash_algo(dentry, xvalue, xattr_value_len); 768 if (err) 769 return err; 770 771 digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG); 772 } else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) { 773 digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG); 774 } 775 if (result == 1 || evm_revalidate_status(xattr_name)) { 776 ima_reset_appraise_flags(d_backing_inode(dentry), digsig); 777 if (result == 1) 778 result = 0; 779 } 780 return result; 781 } 782 783 static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, 784 const char *acl_name, struct posix_acl *kacl) 785 { 786 if (evm_revalidate_status(acl_name)) 787 ima_reset_appraise_flags(d_backing_inode(dentry), 0); 788 789 return 0; 790 } 791 792 static int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, 793 const char *xattr_name) 794 { 795 int result; 796 797 result = ima_protect_xattr(dentry, xattr_name, NULL, 0); 798 if (result == 1 || evm_revalidate_status(xattr_name)) { 799 ima_reset_appraise_flags(d_backing_inode(dentry), 0); 800 if (result == 1) 801 result = 0; 802 } 803 return result; 804 } 805 806 static int ima_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, 807 const char *acl_name) 808 { 809 return ima_inode_set_acl(idmap, dentry, acl_name, NULL); 810 } 811 812 static struct security_hook_list ima_appraise_hooks[] __ro_after_init = { 813 LSM_HOOK_INIT(inode_post_setattr, ima_inode_post_setattr), 814 LSM_HOOK_INIT(inode_setxattr, ima_inode_setxattr), 815 LSM_HOOK_INIT(inode_set_acl, ima_inode_set_acl), 816 LSM_HOOK_INIT(inode_removexattr, ima_inode_removexattr), 817 LSM_HOOK_INIT(inode_remove_acl, ima_inode_remove_acl), 818 }; 819 820 void __init init_ima_appraise_lsm(const struct lsm_id *lsmid) 821 { 822 security_add_hooks(ima_appraise_hooks, ARRAY_SIZE(ima_appraise_hooks), 823 lsmid); 824 } 825