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/binfmts.h> 12 #include <linux/fs.h> 13 #include <linux/xattr.h> 14 #include <linux/magic.h> 15 #include <linux/ima.h> 16 #include <linux/evm.h> 17 #include <linux/fsverity.h> 18 #include <keys/system_keyring.h> 19 #include <uapi/linux/fsverity.h> 20 21 #include "ima.h" 22 23 #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM 24 static char *ima_appraise_cmdline_default __initdata; 25 core_param(ima_appraise, ima_appraise_cmdline_default, charp, 0); 26 27 void __init ima_appraise_parse_cmdline(void) 28 { 29 const char *str = ima_appraise_cmdline_default; 30 bool sb_state = arch_get_secureboot(); 31 int appraisal_state = ima_appraise; 32 33 if (!str) 34 return; 35 36 if (strncmp(str, "off", 3) == 0) 37 appraisal_state = 0; 38 else if (strncmp(str, "log", 3) == 0) 39 appraisal_state = IMA_APPRAISE_LOG; 40 else if (strncmp(str, "fix", 3) == 0) 41 appraisal_state = IMA_APPRAISE_FIX; 42 else if (strncmp(str, "enforce", 7) == 0) 43 appraisal_state = IMA_APPRAISE_ENFORCE; 44 else 45 pr_err("invalid \"%s\" appraise option", str); 46 47 /* If appraisal state was changed, but secure boot is enabled, 48 * keep its default */ 49 if (sb_state) { 50 if (!(appraisal_state & IMA_APPRAISE_ENFORCE)) 51 pr_info("Secure boot enabled: ignoring ima_appraise=%s option", 52 str); 53 } else { 54 ima_appraise = appraisal_state; 55 } 56 } 57 #endif 58 59 /* 60 * is_ima_appraise_enabled - return appraise status 61 * 62 * Only return enabled, if not in ima_appraise="fix" or "log" modes. 63 */ 64 bool is_ima_appraise_enabled(void) 65 { 66 return ima_appraise & IMA_APPRAISE_ENFORCE; 67 } 68 69 /* 70 * ima_must_appraise - set appraise flag 71 * 72 * Return 1 to appraise or hash 73 */ 74 int ima_must_appraise(struct mnt_idmap *idmap, struct inode *inode, 75 int mask, enum ima_hooks func) 76 { 77 struct lsm_prop prop; 78 79 if (!ima_appraise) 80 return 0; 81 82 security_current_getlsmprop_subj(&prop); 83 return ima_match_policy(idmap, inode, current_cred(), &prop, 84 func, mask, IMA_APPRAISE | IMA_HASH, NULL, 85 NULL, NULL, NULL); 86 } 87 88 static int ima_fix_xattr(struct dentry *dentry, struct ima_iint_cache *iint) 89 { 90 int rc, offset; 91 u8 algo = iint->ima_hash->algo; 92 93 if (algo <= HASH_ALGO_SHA1) { 94 offset = 1; 95 iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST; 96 } else { 97 offset = 0; 98 iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG; 99 iint->ima_hash->xattr.ng.algo = algo; 100 } 101 rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_IMA, 102 &iint->ima_hash->xattr.data[offset], 103 (sizeof(iint->ima_hash->xattr) - offset) + 104 iint->ima_hash->length, 0); 105 return rc; 106 } 107 108 /* Return specific func appraised cached result */ 109 enum integrity_status ima_get_cache_status(struct ima_iint_cache *iint, 110 enum ima_hooks func) 111 { 112 switch (func) { 113 case MMAP_CHECK: 114 case MMAP_CHECK_REQPROT: 115 return iint->ima_mmap_status; 116 case BPRM_CHECK: 117 return iint->ima_bprm_status; 118 case CREDS_CHECK: 119 return iint->ima_creds_status; 120 case FILE_CHECK: 121 case POST_SETATTR: 122 return iint->ima_file_status; 123 case MODULE_CHECK ... MAX_CHECK - 1: 124 default: 125 return iint->ima_read_status; 126 } 127 } 128 129 static void ima_set_cache_status(struct ima_iint_cache *iint, 130 enum ima_hooks func, 131 enum integrity_status status) 132 { 133 switch (func) { 134 case MMAP_CHECK: 135 case MMAP_CHECK_REQPROT: 136 iint->ima_mmap_status = status; 137 break; 138 case BPRM_CHECK: 139 iint->ima_bprm_status = status; 140 break; 141 case CREDS_CHECK: 142 iint->ima_creds_status = status; 143 break; 144 case FILE_CHECK: 145 case POST_SETATTR: 146 iint->ima_file_status = status; 147 break; 148 case MODULE_CHECK ... MAX_CHECK - 1: 149 default: 150 iint->ima_read_status = status; 151 break; 152 } 153 } 154 155 static void ima_cache_flags(struct ima_iint_cache *iint, enum ima_hooks func) 156 { 157 switch (func) { 158 case MMAP_CHECK: 159 case MMAP_CHECK_REQPROT: 160 iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED); 161 break; 162 case BPRM_CHECK: 163 iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED); 164 break; 165 case CREDS_CHECK: 166 iint->flags |= (IMA_CREDS_APPRAISED | IMA_APPRAISED); 167 break; 168 case FILE_CHECK: 169 case POST_SETATTR: 170 iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED); 171 break; 172 case MODULE_CHECK ... MAX_CHECK - 1: 173 default: 174 iint->flags |= (IMA_READ_APPRAISED | IMA_APPRAISED); 175 break; 176 } 177 } 178 179 enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, 180 int xattr_len) 181 { 182 struct signature_v2_hdr *sig; 183 enum hash_algo ret; 184 185 if (!xattr_value || xattr_len < 2) 186 /* return default hash algo */ 187 return ima_hash_algo; 188 189 switch (xattr_value->type) { 190 case IMA_VERITY_DIGSIG: 191 sig = (typeof(sig))xattr_value; 192 if (sig->version != 3 || xattr_len <= sizeof(*sig) || 193 sig->hash_algo >= HASH_ALGO__LAST) 194 return ima_hash_algo; 195 return sig->hash_algo; 196 case EVM_IMA_XATTR_DIGSIG: 197 sig = (typeof(sig))xattr_value; 198 if (sig->version != 2 || xattr_len <= sizeof(*sig) 199 || sig->hash_algo >= HASH_ALGO__LAST) 200 return ima_hash_algo; 201 return sig->hash_algo; 202 case IMA_XATTR_DIGEST_NG: 203 /* first byte contains algorithm id */ 204 ret = xattr_value->data[0]; 205 if (ret < HASH_ALGO__LAST) 206 return ret; 207 break; 208 case IMA_XATTR_DIGEST: 209 /* this is for backward compatibility */ 210 if (xattr_len == 21) { 211 unsigned int zero = 0; 212 if (!memcmp(&xattr_value->data[16], &zero, 4)) 213 return HASH_ALGO_MD5; 214 else 215 return HASH_ALGO_SHA1; 216 } else if (xattr_len == 17) 217 return HASH_ALGO_MD5; 218 break; 219 } 220 221 /* return default hash algo */ 222 return ima_hash_algo; 223 } 224 225 int ima_read_xattr(struct dentry *dentry, 226 struct evm_ima_xattr_data **xattr_value, int xattr_len) 227 { 228 int ret; 229 230 ret = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_IMA, 231 (char **)xattr_value, xattr_len, GFP_NOFS); 232 if (ret == -EOPNOTSUPP) 233 ret = 0; 234 return ret; 235 } 236 237 /* 238 * xattr_verify - verify xattr digest or signature 239 * 240 * Verify whether the hash or signature matches the file contents. 241 * 242 * Return 0 on success, error code otherwise. 243 */ 244 static int xattr_verify(enum ima_hooks func, struct ima_iint_cache *iint, 245 struct evm_ima_xattr_data *xattr_value, int xattr_len, 246 enum integrity_status *status, const char **cause) 247 { 248 struct signature_v2_hdr *sig; 249 int rc = -EINVAL, hash_start = 0; 250 int mask; 251 252 switch (xattr_value->type) { 253 case IMA_XATTR_DIGEST_NG: 254 /* first byte contains algorithm id */ 255 hash_start = 1; 256 fallthrough; 257 case IMA_XATTR_DIGEST: 258 if (*status != INTEGRITY_PASS_IMMUTABLE) { 259 if (iint->flags & IMA_DIGSIG_REQUIRED) { 260 if (iint->flags & IMA_VERITY_REQUIRED) 261 *cause = "verity-signature-required"; 262 else 263 *cause = "IMA-signature-required"; 264 *status = INTEGRITY_FAIL; 265 break; 266 } 267 clear_bit(IMA_DIGSIG, &iint->atomic_flags); 268 } else { 269 set_bit(IMA_DIGSIG, &iint->atomic_flags); 270 } 271 if (xattr_len - sizeof(xattr_value->type) - hash_start >= 272 iint->ima_hash->length) 273 /* 274 * xattr length may be longer. md5 hash in previous 275 * version occupied 20 bytes in xattr, instead of 16 276 */ 277 rc = memcmp(&xattr_value->data[hash_start], 278 iint->ima_hash->digest, 279 iint->ima_hash->length); 280 else 281 rc = -EINVAL; 282 if (rc) { 283 *cause = "invalid-hash"; 284 *status = INTEGRITY_FAIL; 285 break; 286 } 287 *status = INTEGRITY_PASS; 288 break; 289 case EVM_IMA_XATTR_DIGSIG: 290 set_bit(IMA_DIGSIG, &iint->atomic_flags); 291 292 mask = IMA_DIGSIG_REQUIRED | IMA_VERITY_REQUIRED; 293 if ((iint->flags & mask) == mask) { 294 *cause = "verity-signature-required"; 295 *status = INTEGRITY_FAIL; 296 break; 297 } 298 299 sig = (typeof(sig))xattr_value; 300 if (sig->version > 3) { 301 *cause = "invalid-signature-version"; 302 *status = INTEGRITY_FAIL; 303 break; 304 } 305 306 if ((iint->flags & IMA_SIGV3_REQUIRED) && sig->version != 3) { 307 *cause = "IMA-sigv3-required"; 308 *status = INTEGRITY_FAIL; 309 break; 310 } 311 312 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, 313 (const char *)xattr_value, 314 xattr_len, 315 iint->ima_hash->digest, 316 iint->ima_hash->length, 317 iint->ima_hash->algo); 318 if (rc == -EOPNOTSUPP) { 319 *status = INTEGRITY_UNKNOWN; 320 break; 321 } 322 if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && 323 func == KEXEC_KERNEL_CHECK) 324 rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, 325 (const char *)xattr_value, 326 xattr_len, 327 iint->ima_hash->digest, 328 iint->ima_hash->length, 329 iint->ima_hash->algo); 330 331 if (rc) { 332 *cause = "invalid-signature"; 333 *status = INTEGRITY_FAIL; 334 } else { 335 *status = INTEGRITY_PASS; 336 } 337 break; 338 case IMA_VERITY_DIGSIG: 339 set_bit(IMA_DIGSIG, &iint->atomic_flags); 340 341 if (iint->flags & IMA_DIGSIG_REQUIRED) { 342 if (!(iint->flags & IMA_VERITY_REQUIRED)) { 343 *cause = "IMA-signature-required"; 344 *status = INTEGRITY_FAIL; 345 break; 346 } 347 } 348 349 sig = (typeof(sig))xattr_value; 350 if (sig->version != 3) { 351 *cause = "invalid-signature-version"; 352 *status = INTEGRITY_FAIL; 353 break; 354 } 355 356 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, 357 (const char *)xattr_value, 358 xattr_len, 359 iint->ima_hash->digest, 360 iint->ima_hash->length, 361 iint->ima_hash->algo); 362 if (rc == -EOPNOTSUPP) { 363 *status = INTEGRITY_UNKNOWN; 364 break; 365 } else if (rc) { 366 *cause = "invalid-verity-signature"; 367 *status = INTEGRITY_FAIL; 368 } else { 369 *status = INTEGRITY_PASS; 370 } 371 372 break; 373 default: 374 *status = INTEGRITY_UNKNOWN; 375 *cause = "unknown-ima-data"; 376 break; 377 } 378 379 return rc; 380 } 381 382 /* 383 * modsig_verify - verify modsig signature 384 * 385 * Verify whether the signature matches the file contents. 386 * 387 * Return 0 on success, error code otherwise. 388 */ 389 static int modsig_verify(enum ima_hooks func, const struct modsig *modsig, 390 enum integrity_status *status, const char **cause) 391 { 392 int rc; 393 394 rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig); 395 if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && 396 func == KEXEC_KERNEL_CHECK) 397 rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM, 398 modsig); 399 if (rc) { 400 *cause = "invalid-signature"; 401 *status = INTEGRITY_FAIL; 402 } else { 403 *status = INTEGRITY_PASS; 404 } 405 406 return rc; 407 } 408 409 /* 410 * ima_check_blacklist - determine if the binary is blacklisted. 411 * 412 * Add the hash of the blacklisted binary to the measurement list, based 413 * on policy. 414 * 415 * Returns -EPERM if the hash is blacklisted. 416 */ 417 int ima_check_blacklist(struct ima_iint_cache *iint, 418 const struct modsig *modsig, int pcr) 419 { 420 enum hash_algo hash_algo; 421 const u8 *digest = NULL; 422 u32 digestsize = 0; 423 int rc = 0; 424 425 if (!(iint->flags & IMA_CHECK_BLACKLIST)) 426 return 0; 427 428 if (iint->flags & IMA_MODSIG_ALLOWED && modsig) { 429 ima_get_modsig_digest(modsig, &hash_algo, &digest, &digestsize); 430 431 rc = is_binary_blacklisted(digest, digestsize); 432 } else if (iint->flags & IMA_DIGSIG_REQUIRED && iint->ima_hash) 433 rc = is_binary_blacklisted(iint->ima_hash->digest, iint->ima_hash->length); 434 435 if ((rc == -EPERM) && (iint->flags & IMA_MEASURE)) 436 process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize, 437 "blacklisted-hash", NONE, 438 pcr, NULL, false, NULL, 0); 439 440 return rc; 441 } 442 443 /* 444 * ima_appraise_measurement - appraise file measurement 445 * 446 * Call evm_verifyxattr() to verify the integrity of 'security.ima'. 447 * Assuming success, compare the xattr hash with the collected measurement. 448 * 449 * Return 0 on success, error code otherwise 450 */ 451 int ima_appraise_measurement(enum ima_hooks func, struct ima_iint_cache *iint, 452 struct file *file, const unsigned char *filename, 453 struct evm_ima_xattr_data *xattr_value, 454 int xattr_len, const struct modsig *modsig, 455 bool bprm_is_check) 456 { 457 static const char op[] = "appraise_data"; 458 int audit_msgno = AUDIT_INTEGRITY_DATA; 459 const char *cause = "unknown"; 460 struct dentry *dentry = file_dentry(file); 461 struct inode *inode = d_backing_inode(dentry); 462 enum integrity_status status = INTEGRITY_UNKNOWN; 463 int rc = xattr_len; 464 bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig; 465 466 /* If not appraising a modsig, we need an xattr. */ 467 if (!(inode->i_opflags & IOP_XATTR) && !try_modsig) 468 return INTEGRITY_UNKNOWN; 469 470 /* 471 * Unlike any of the other LSM hooks where the kernel enforces file 472 * integrity, enforcing file integrity for the bprm_creds_for_exec() 473 * LSM hook with the AT_EXECVE_CHECK flag is left up to the discretion 474 * of the script interpreter(userspace). Differentiate kernel and 475 * userspace enforced integrity audit messages. 476 */ 477 if (bprm_is_check) 478 audit_msgno = AUDIT_INTEGRITY_USERSPACE; 479 480 /* If reading the xattr failed and there's no modsig, error out. */ 481 if (rc <= 0 && !try_modsig) { 482 if (rc && rc != -ENODATA) 483 goto out; 484 485 if (iint->flags & IMA_DIGSIG_REQUIRED) { 486 if (iint->flags & IMA_VERITY_REQUIRED) 487 cause = "verity-signature-required"; 488 else 489 cause = "IMA-signature-required"; 490 } else { 491 cause = "missing-hash"; 492 } 493 494 status = INTEGRITY_NOLABEL; 495 if (file->f_mode & FMODE_CREATED) 496 iint->flags |= IMA_NEW_FILE; 497 if ((iint->flags & IMA_NEW_FILE) && 498 (!(iint->flags & IMA_DIGSIG_REQUIRED) || 499 (inode->i_size == 0))) 500 status = INTEGRITY_PASS; 501 goto out; 502 } 503 504 status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, 505 rc < 0 ? 0 : rc); 506 switch (status) { 507 case INTEGRITY_PASS: 508 case INTEGRITY_PASS_IMMUTABLE: 509 case INTEGRITY_UNKNOWN: 510 break; 511 case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ 512 /* It's fine not to have xattrs when using a modsig. */ 513 if (try_modsig) 514 break; 515 fallthrough; 516 case INTEGRITY_NOLABEL: /* No security.evm xattr. */ 517 cause = "missing-HMAC"; 518 goto out; 519 case INTEGRITY_FAIL_IMMUTABLE: 520 set_bit(IMA_DIGSIG, &iint->atomic_flags); 521 cause = "invalid-fail-immutable"; 522 goto out; 523 case INTEGRITY_FAIL: /* Invalid HMAC/signature. */ 524 cause = "invalid-HMAC"; 525 goto out; 526 default: 527 WARN_ONCE(true, "Unexpected integrity status %d\n", status); 528 } 529 530 if (xattr_value) 531 rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, 532 &cause); 533 534 /* 535 * If we have a modsig and either no imasig or the imasig's key isn't 536 * known, then try verifying the modsig. 537 */ 538 if (try_modsig && 539 (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG || 540 rc == -ENOKEY)) 541 rc = modsig_verify(func, modsig, &status, &cause); 542 543 out: 544 /* 545 * File signatures on some filesystems can not be properly verified. 546 * When such filesystems are mounted by an untrusted mounter or on a 547 * system not willing to accept such a risk, fail the file signature 548 * verification. 549 */ 550 if ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) && 551 ((inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) || 552 (iint->flags & IMA_FAIL_UNVERIFIABLE_SIGS))) { 553 status = INTEGRITY_FAIL; 554 cause = "unverifiable-signature"; 555 integrity_audit_msg(audit_msgno, inode, filename, 556 op, cause, rc, 0); 557 } else if (status != INTEGRITY_PASS) { 558 /* Fix mode, but don't replace file signatures. */ 559 if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig && 560 (!xattr_value || 561 xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { 562 if (!ima_fix_xattr(dentry, iint)) 563 status = INTEGRITY_PASS; 564 } else if (status == INTEGRITY_NOLABEL) { 565 if (!evm_fix_hmac(dentry, XATTR_NAME_IMA, 566 (const char *)xattr_value, 567 xattr_len)) 568 status = INTEGRITY_PASS; 569 } 570 571 /* 572 * Permit new files with file/EVM portable signatures, but 573 * without data. 574 */ 575 if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE && 576 test_bit(IMA_DIGSIG, &iint->atomic_flags)) { 577 status = INTEGRITY_PASS; 578 } 579 580 integrity_audit_msg(audit_msgno, inode, filename, 581 op, cause, rc, 0); 582 } else { 583 ima_cache_flags(iint, func); 584 } 585 586 ima_set_cache_status(iint, func, status); 587 return status; 588 } 589 590 /* 591 * ima_update_xattr - update 'security.ima' hash value 592 */ 593 void ima_update_xattr(struct ima_iint_cache *iint, struct file *file) 594 { 595 struct dentry *dentry = file_dentry(file); 596 int rc = 0; 597 598 /* do not collect and update hash for digital signatures */ 599 if (test_bit(IMA_DIGSIG, &iint->atomic_flags)) 600 return; 601 602 if ((iint->ima_file_status != INTEGRITY_PASS) && 603 !(iint->flags & IMA_HASH)) 604 return; 605 606 rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL); 607 if (rc < 0) 608 return; 609 610 inode_lock(file_inode(file)); 611 ima_fix_xattr(dentry, iint); 612 inode_unlock(file_inode(file)); 613 } 614 615 /** 616 * ima_inode_post_setattr - reflect file metadata changes 617 * @idmap: idmap of the mount the inode was found from 618 * @dentry: pointer to the affected dentry 619 * @ia_valid: for the UID and GID status 620 * 621 * Changes to a dentry's metadata might result in needing to appraise. 622 * 623 * This function is called from notify_change(), which expects the caller 624 * to lock the inode's i_mutex. 625 */ 626 static void ima_inode_post_setattr(struct mnt_idmap *idmap, 627 struct dentry *dentry, int ia_valid) 628 { 629 struct inode *inode = d_backing_inode(dentry); 630 struct ima_iint_cache *iint; 631 int action; 632 633 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode) 634 || !(inode->i_opflags & IOP_XATTR)) 635 return; 636 637 action = ima_must_appraise(idmap, inode, MAY_ACCESS, POST_SETATTR); 638 iint = ima_iint_find(inode); 639 if (iint) { 640 set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags); 641 if (!action) 642 clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); 643 } 644 } 645 646 /* 647 * ima_protect_xattr - protect 'security.ima' 648 * 649 * Ensure that not just anyone can modify or remove 'security.ima'. 650 */ 651 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, 652 const void *xattr_value, size_t xattr_value_len) 653 { 654 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) { 655 if (!capable(CAP_SYS_ADMIN)) 656 return -EPERM; 657 return 1; 658 } 659 return 0; 660 } 661 662 /* 663 * ima_reset_appraise_flags - reset ima_iint_cache flags 664 * 665 * @digsig: whether to clear/set IMA_DIGSIG flag, tristate values 666 * 0: clear IMA_DIGSIG 667 * 1: set IMA_DIGSIG 668 * -1: don't change IMA_DIGSIG 669 * 670 */ 671 static void ima_reset_appraise_flags(struct inode *inode, int digsig) 672 { 673 struct ima_iint_cache *iint; 674 675 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)) 676 return; 677 678 iint = ima_iint_find(inode); 679 if (!iint) 680 return; 681 iint->measured_pcrs = 0; 682 set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags); 683 if (digsig == 1) 684 set_bit(IMA_DIGSIG, &iint->atomic_flags); 685 else if (digsig == 0) 686 clear_bit(IMA_DIGSIG, &iint->atomic_flags); 687 } 688 689 /** 690 * validate_hash_algo() - Block setxattr with unsupported hash algorithms 691 * @dentry: object of the setxattr() 692 * @xattr_value: userland supplied xattr value 693 * @xattr_value_len: length of xattr_value 694 * 695 * The xattr value is mapped to its hash algorithm, and this algorithm 696 * must be built in the kernel for the setxattr to be allowed. 697 * 698 * Emit an audit message when the algorithm is invalid. 699 * 700 * Return: 0 on success, else an error. 701 */ 702 static int validate_hash_algo(struct dentry *dentry, 703 const struct evm_ima_xattr_data *xattr_value, 704 size_t xattr_value_len) 705 { 706 char *path = NULL, *pathbuf = NULL; 707 enum hash_algo xattr_hash_algo; 708 const char *errmsg = "unavailable-hash-algorithm"; 709 unsigned int allowed_hashes; 710 711 xattr_hash_algo = ima_get_hash_algo(xattr_value, xattr_value_len); 712 713 allowed_hashes = atomic_read(&ima_setxattr_allowed_hash_algorithms); 714 715 if (allowed_hashes) { 716 /* success if the algorithm is allowed in the ima policy */ 717 if (allowed_hashes & (1U << xattr_hash_algo)) 718 return 0; 719 720 /* 721 * We use a different audit message when the hash algorithm 722 * is denied by a policy rule, instead of not being built 723 * in the kernel image 724 */ 725 errmsg = "denied-hash-algorithm"; 726 } else { 727 if (likely(xattr_hash_algo == ima_hash_algo)) 728 return 0; 729 730 /* allow any xattr using an algorithm built in the kernel */ 731 if (crypto_has_alg(hash_algo_name[xattr_hash_algo], 0, 0)) 732 return 0; 733 } 734 735 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); 736 if (!pathbuf) 737 return -EACCES; 738 739 path = dentry_path(dentry, pathbuf, PATH_MAX); 740 741 integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path, 742 "set_data", errmsg, -EACCES, 0); 743 744 kfree(pathbuf); 745 746 return -EACCES; 747 } 748 749 static int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, 750 const char *xattr_name, const void *xattr_value, 751 size_t xattr_value_len, int flags) 752 { 753 const struct evm_ima_xattr_data *xvalue = xattr_value; 754 int digsig = 0; 755 int result; 756 int err; 757 758 result = ima_protect_xattr(dentry, xattr_name, xattr_value, 759 xattr_value_len); 760 if (result == 1) { 761 if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST)) 762 return -EINVAL; 763 764 err = validate_hash_algo(dentry, xvalue, xattr_value_len); 765 if (err) 766 return err; 767 768 digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG); 769 } else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) { 770 digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG); 771 } else { 772 digsig = -1; 773 } 774 if (result == 1 || evm_revalidate_status(xattr_name)) { 775 ima_reset_appraise_flags(d_backing_inode(dentry), digsig); 776 if (result == 1) 777 result = 0; 778 } 779 return result; 780 } 781 782 static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, 783 const char *acl_name, struct posix_acl *kacl) 784 { 785 if (evm_revalidate_status(acl_name)) 786 ima_reset_appraise_flags(d_backing_inode(dentry), -1); 787 788 return 0; 789 } 790 791 static int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, 792 const char *xattr_name) 793 { 794 int result, digsig = -1; 795 796 result = ima_protect_xattr(dentry, xattr_name, NULL, 0); 797 if (result == 1 || evm_revalidate_status(xattr_name)) { 798 if (!strcmp(xattr_name, XATTR_NAME_IMA)) 799 digsig = 0; 800 ima_reset_appraise_flags(d_backing_inode(dentry), digsig); 801 if (result == 1) 802 result = 0; 803 } 804 return result; 805 } 806 807 static int ima_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, 808 const char *acl_name) 809 { 810 return ima_inode_set_acl(idmap, dentry, acl_name, NULL); 811 } 812 813 static struct security_hook_list ima_appraise_hooks[] __ro_after_init = { 814 LSM_HOOK_INIT(inode_post_setattr, ima_inode_post_setattr), 815 LSM_HOOK_INIT(inode_setxattr, ima_inode_setxattr), 816 LSM_HOOK_INIT(inode_set_acl, ima_inode_set_acl), 817 LSM_HOOK_INIT(inode_removexattr, ima_inode_removexattr), 818 LSM_HOOK_INIT(inode_remove_acl, ima_inode_remove_acl), 819 }; 820 821 void __init init_ima_appraise_lsm(const struct lsm_id *lsmid) 822 { 823 security_add_hooks(ima_appraise_hooks, ARRAY_SIZE(ima_appraise_hooks), 824 lsmid); 825 } 826