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