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, rc, iint); 518 switch (status) { 519 case INTEGRITY_PASS: 520 case INTEGRITY_PASS_IMMUTABLE: 521 case INTEGRITY_UNKNOWN: 522 break; 523 case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ 524 /* It's fine not to have xattrs when using a modsig. */ 525 if (try_modsig) 526 break; 527 fallthrough; 528 case INTEGRITY_NOLABEL: /* No security.evm xattr. */ 529 cause = "missing-HMAC"; 530 goto out; 531 case INTEGRITY_FAIL_IMMUTABLE: 532 set_bit(IMA_DIGSIG, &iint->atomic_flags); 533 cause = "invalid-fail-immutable"; 534 goto out; 535 case INTEGRITY_FAIL: /* Invalid HMAC/signature. */ 536 cause = "invalid-HMAC"; 537 goto out; 538 default: 539 WARN_ONCE(true, "Unexpected integrity status %d\n", status); 540 } 541 542 if (xattr_value) 543 rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, 544 &cause); 545 546 /* 547 * If we have a modsig and either no imasig or the imasig's key isn't 548 * known, then try verifying the modsig. 549 */ 550 if (try_modsig && 551 (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG || 552 rc == -ENOKEY)) 553 rc = modsig_verify(func, modsig, &status, &cause); 554 555 out: 556 /* 557 * File signatures on some filesystems can not be properly verified. 558 * When such filesystems are mounted by an untrusted mounter or on a 559 * system not willing to accept such a risk, fail the file signature 560 * verification. 561 */ 562 if ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) && 563 ((inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) || 564 (iint->flags & IMA_FAIL_UNVERIFIABLE_SIGS))) { 565 status = INTEGRITY_FAIL; 566 cause = "unverifiable-signature"; 567 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, 568 op, cause, rc, 0); 569 } else if (status != INTEGRITY_PASS) { 570 /* Fix mode, but don't replace file signatures. */ 571 if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig && 572 (!xattr_value || 573 xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { 574 if (!ima_fix_xattr(dentry, iint)) 575 status = INTEGRITY_PASS; 576 } 577 578 /* 579 * Permit new files with file/EVM portable signatures, but 580 * without data. 581 */ 582 if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE && 583 test_bit(IMA_DIGSIG, &iint->atomic_flags)) { 584 status = INTEGRITY_PASS; 585 } 586 587 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, 588 op, cause, rc, 0); 589 } else { 590 ima_cache_flags(iint, func); 591 } 592 593 ima_set_cache_status(iint, func, status); 594 return status; 595 } 596 597 /* 598 * ima_update_xattr - update 'security.ima' hash value 599 */ 600 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file) 601 { 602 struct dentry *dentry = file_dentry(file); 603 int rc = 0; 604 605 /* do not collect and update hash for digital signatures */ 606 if (test_bit(IMA_DIGSIG, &iint->atomic_flags)) 607 return; 608 609 if ((iint->ima_file_status != INTEGRITY_PASS) && 610 !(iint->flags & IMA_HASH)) 611 return; 612 613 rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL); 614 if (rc < 0) 615 return; 616 617 inode_lock(file_inode(file)); 618 ima_fix_xattr(dentry, iint); 619 inode_unlock(file_inode(file)); 620 } 621 622 /** 623 * ima_inode_post_setattr - reflect file metadata changes 624 * @mnt_userns: user namespace of the mount the inode was found from 625 * @dentry: pointer to the affected dentry 626 * 627 * Changes to a dentry's metadata might result in needing to appraise. 628 * 629 * This function is called from notify_change(), which expects the caller 630 * to lock the inode's i_mutex. 631 */ 632 void ima_inode_post_setattr(struct user_namespace *mnt_userns, 633 struct dentry *dentry) 634 { 635 struct inode *inode = d_backing_inode(dentry); 636 struct integrity_iint_cache *iint; 637 int action; 638 639 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode) 640 || !(inode->i_opflags & IOP_XATTR)) 641 return; 642 643 action = ima_must_appraise(mnt_userns, inode, MAY_ACCESS, POST_SETATTR); 644 iint = integrity_iint_find(inode); 645 if (iint) { 646 set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags); 647 if (!action) 648 clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); 649 } 650 } 651 652 /* 653 * ima_protect_xattr - protect 'security.ima' 654 * 655 * Ensure that not just anyone can modify or remove 'security.ima'. 656 */ 657 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, 658 const void *xattr_value, size_t xattr_value_len) 659 { 660 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) { 661 if (!capable(CAP_SYS_ADMIN)) 662 return -EPERM; 663 return 1; 664 } 665 return 0; 666 } 667 668 static void ima_reset_appraise_flags(struct inode *inode, int digsig) 669 { 670 struct integrity_iint_cache *iint; 671 672 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)) 673 return; 674 675 iint = integrity_iint_find(inode); 676 if (!iint) 677 return; 678 iint->measured_pcrs = 0; 679 set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags); 680 if (digsig) 681 set_bit(IMA_DIGSIG, &iint->atomic_flags); 682 else 683 clear_bit(IMA_DIGSIG, &iint->atomic_flags); 684 } 685 686 /** 687 * validate_hash_algo() - Block setxattr with unsupported hash algorithms 688 * @dentry: object of the setxattr() 689 * @xattr_value: userland supplied xattr value 690 * @xattr_value_len: length of xattr_value 691 * 692 * The xattr value is mapped to its hash algorithm, and this algorithm 693 * must be built in the kernel for the setxattr to be allowed. 694 * 695 * Emit an audit message when the algorithm is invalid. 696 * 697 * Return: 0 on success, else an error. 698 */ 699 static int validate_hash_algo(struct dentry *dentry, 700 const struct evm_ima_xattr_data *xattr_value, 701 size_t xattr_value_len) 702 { 703 char *path = NULL, *pathbuf = NULL; 704 enum hash_algo xattr_hash_algo; 705 const char *errmsg = "unavailable-hash-algorithm"; 706 unsigned int allowed_hashes; 707 708 xattr_hash_algo = ima_get_hash_algo(xattr_value, xattr_value_len); 709 710 allowed_hashes = atomic_read(&ima_setxattr_allowed_hash_algorithms); 711 712 if (allowed_hashes) { 713 /* success if the algorithm is allowed in the ima policy */ 714 if (allowed_hashes & (1U << xattr_hash_algo)) 715 return 0; 716 717 /* 718 * We use a different audit message when the hash algorithm 719 * is denied by a policy rule, instead of not being built 720 * in the kernel image 721 */ 722 errmsg = "denied-hash-algorithm"; 723 } else { 724 if (likely(xattr_hash_algo == ima_hash_algo)) 725 return 0; 726 727 /* allow any xattr using an algorithm built in the kernel */ 728 if (crypto_has_alg(hash_algo_name[xattr_hash_algo], 0, 0)) 729 return 0; 730 } 731 732 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); 733 if (!pathbuf) 734 return -EACCES; 735 736 path = dentry_path(dentry, pathbuf, PATH_MAX); 737 738 integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path, 739 "set_data", errmsg, -EACCES, 0); 740 741 kfree(pathbuf); 742 743 return -EACCES; 744 } 745 746 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, 747 const void *xattr_value, size_t xattr_value_len) 748 { 749 const struct evm_ima_xattr_data *xvalue = xattr_value; 750 int digsig = 0; 751 int result; 752 753 result = ima_protect_xattr(dentry, xattr_name, xattr_value, 754 xattr_value_len); 755 if (result == 1) { 756 if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST)) 757 return -EINVAL; 758 digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG); 759 } else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) { 760 digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG); 761 } 762 if (result == 1 || evm_revalidate_status(xattr_name)) { 763 result = validate_hash_algo(dentry, xvalue, xattr_value_len); 764 if (result) 765 return result; 766 767 ima_reset_appraise_flags(d_backing_inode(dentry), digsig); 768 } 769 return result; 770 } 771 772 int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name) 773 { 774 int result; 775 776 result = ima_protect_xattr(dentry, xattr_name, NULL, 0); 777 if (result == 1 || evm_revalidate_status(xattr_name)) { 778 ima_reset_appraise_flags(d_backing_inode(dentry), 0); 779 if (result == 1) 780 result = 0; 781 } 782 return result; 783 } 784