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 23static char *ima_appraise_cmdline_default __initdata; 24core_param(ima_appraise, ima_appraise_cmdline_default, charp, 0); 25 26void __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 */ 63bool 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 */ 73int 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 87static 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 */ 108enum 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 128static 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 154static 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 178enum 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 224int 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 */ 251static 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 */ 277static 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, &hash.hdr); 382 if (rc) { 383 *cause = "sigv3-hashing-error"; 384 *status = INTEGRITY_FAIL; 385 break; 386 } 387 388 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, 389 (const char *)xattr_value, 390 xattr_len, hash.digest, 391 hash.hdr.length); 392 if (rc) { 393 *cause = "invalid-verity-signature"; 394 *status = INTEGRITY_FAIL; 395 } else { 396 *status = INTEGRITY_PASS; 397 } 398 399 break; 400 default: 401 *status = INTEGRITY_UNKNOWN; 402 *cause = "unknown-ima-data"; 403 break; 404 } 405 406 return rc; 407} 408 409/* 410 * modsig_verify - verify modsig signature 411 * 412 * Verify whether the signature matches the file contents. 413 * 414 * Return 0 on success, error code otherwise. 415 */ 416static int modsig_verify(enum ima_hooks func, const struct modsig *modsig, 417 enum integrity_status *status, const char **cause) 418{ 419 int rc; 420 421 rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig); 422 if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && 423 func == KEXEC_KERNEL_CHECK) 424 rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM, 425 modsig); 426 if (rc) { 427 *cause = "invalid-signature"; 428 *status = INTEGRITY_FAIL; 429 } else { 430 *status = INTEGRITY_PASS; 431 } 432 433 return rc; 434} 435 436/* 437 * ima_check_blacklist - determine if the binary is blacklisted. 438 * 439 * Add the hash of the blacklisted binary to the measurement list, based 440 * on policy. 441 * 442 * Returns -EPERM if the hash is blacklisted. 443 */ 444int ima_check_blacklist(struct ima_iint_cache *iint, 445 const struct modsig *modsig, int pcr) 446{ 447 enum hash_algo hash_algo; 448 const u8 *digest = NULL; 449 u32 digestsize = 0; 450 int rc = 0; 451 452 if (!(iint->flags & IMA_CHECK_BLACKLIST)) 453 return 0; 454 455 if (iint->flags & IMA_MODSIG_ALLOWED && modsig) { 456 ima_get_modsig_digest(modsig, &hash_algo, &digest, &digestsize); 457 458 rc = is_binary_blacklisted(digest, digestsize); 459 } else if (iint->flags & IMA_DIGSIG_REQUIRED && iint->ima_hash) 460 rc = is_binary_blacklisted(iint->ima_hash->digest, iint->ima_hash->length); 461 462 if ((rc == -EPERM) && (iint->flags & IMA_MEASURE)) 463 process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize, 464 "blacklisted-hash", NONE, 465 pcr, NULL, false, NULL, 0); 466 467 return rc; 468} 469 470/* 471 * ima_appraise_measurement - appraise file measurement 472 * 473 * Call evm_verifyxattr() to verify the integrity of 'security.ima'. 474 * Assuming success, compare the xattr hash with the collected measurement. 475 * 476 * Return 0 on success, error code otherwise 477 */ 478int ima_appraise_measurement(enum ima_hooks func, struct ima_iint_cache *iint, 479 struct file *file, const unsigned char *filename, 480 struct evm_ima_xattr_data *xattr_value, 481 int xattr_len, const struct modsig *modsig) 482{ 483 static const char op[] = "appraise_data"; 484 const char *cause = "unknown"; 485 struct dentry *dentry = file_dentry(file); 486 struct inode *inode = d_backing_inode(dentry); 487 enum integrity_status status = INTEGRITY_UNKNOWN; 488 int rc = xattr_len; 489 bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig; 490 491 /* If not appraising a modsig, we need an xattr. */ 492 if (!(inode->i_opflags & IOP_XATTR) && !try_modsig) 493 return INTEGRITY_UNKNOWN; 494 495 /* If reading the xattr failed and there's no modsig, error out. */ 496 if (rc <= 0 && !try_modsig) { 497 if (rc && rc != -ENODATA) 498 goto out; 499 500 if (iint->flags & IMA_DIGSIG_REQUIRED) { 501 if (iint->flags & IMA_VERITY_REQUIRED) 502 cause = "verity-signature-required"; 503 else 504 cause = "IMA-signature-required"; 505 } else { 506 cause = "missing-hash"; 507 } 508 509 status = INTEGRITY_NOLABEL; 510 if (file->f_mode & FMODE_CREATED) 511 iint->flags |= IMA_NEW_FILE; 512 if ((iint->flags & IMA_NEW_FILE) && 513 (!(iint->flags & IMA_DIGSIG_REQUIRED) || 514 (inode->i_size == 0))) 515 status = INTEGRITY_PASS; 516 goto out; 517 } 518 519 status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, 520 rc < 0 ? 0 : rc); 521 switch (status) { 522 case INTEGRITY_PASS: 523 case INTEGRITY_PASS_IMMUTABLE: 524 case INTEGRITY_UNKNOWN: 525 break; 526 case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ 527 /* It's fine not to have xattrs when using a modsig. */ 528 if (try_modsig) 529 break; 530 fallthrough; 531 case INTEGRITY_NOLABEL: /* No security.evm xattr. */ 532 cause = "missing-HMAC"; 533 goto out; 534 case INTEGRITY_FAIL_IMMUTABLE: 535 set_bit(IMA_DIGSIG, &iint->atomic_flags); 536 cause = "invalid-fail-immutable"; 537 goto out; 538 case INTEGRITY_FAIL: /* Invalid HMAC/signature. */ 539 cause = "invalid-HMAC"; 540 goto out; 541 default: 542 WARN_ONCE(true, "Unexpected integrity status %d\n", status); 543 } 544 545 if (xattr_value) 546 rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, 547 &cause); 548 549 /* 550 * If we have a modsig and either no imasig or the imasig's key isn't 551 * known, then try verifying the modsig. 552 */ 553 if (try_modsig && 554 (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG || 555 rc == -ENOKEY)) 556 rc = modsig_verify(func, modsig, &status, &cause); 557 558out: 559 /* 560 * File signatures on some filesystems can not be properly verified. 561 * When such filesystems are mounted by an untrusted mounter or on a 562 * system not willing to accept such a risk, fail the file signature 563 * verification. 564 */ 565 if ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) && 566 ((inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) || 567 (iint->flags & IMA_FAIL_UNVERIFIABLE_SIGS))) { 568 status = INTEGRITY_FAIL; 569 cause = "unverifiable-signature"; 570 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, 571 op, cause, rc, 0); 572 } else if (status != INTEGRITY_PASS) { 573 /* Fix mode, but don't replace file signatures. */ 574 if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig && 575 (!xattr_value || 576 xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { 577 if (!ima_fix_xattr(dentry, iint)) 578 status = INTEGRITY_PASS; 579 } 580 581 /* 582 * Permit new files with file/EVM portable signatures, but 583 * without data. 584 */ 585 if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE && 586 test_bit(IMA_DIGSIG, &iint->atomic_flags)) { 587 status = INTEGRITY_PASS; 588 } 589 590 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, 591 op, cause, rc, 0); 592 } else { 593 ima_cache_flags(iint, func); 594 } 595 596 ima_set_cache_status(iint, func, status); 597 return status; 598} 599 600/* 601 * ima_update_xattr - update 'security.ima' hash value 602 */ 603void ima_update_xattr(struct ima_iint_cache *iint, struct file *file) 604{ 605 struct dentry *dentry = file_dentry(file); 606 int rc = 0; 607 608 /* do not collect and update hash for digital signatures */ 609 if (test_bit(IMA_DIGSIG, &iint->atomic_flags)) 610 return; 611 612 if ((iint->ima_file_status != INTEGRITY_PASS) && 613 !(iint->flags & IMA_HASH)) 614 return; 615 616 rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL); 617 if (rc < 0) 618 return; 619 620 inode_lock(file_inode(file)); 621 ima_fix_xattr(dentry, iint); 622 inode_unlock(file_inode(file)); 623} 624 625/** 626 * ima_inode_post_setattr - reflect file metadata changes 627 * @idmap: idmap of the mount the inode was found from 628 * @dentry: pointer to the affected dentry 629 * @ia_valid: for the UID and GID status 630 * 631 * Changes to a dentry's metadata might result in needing to appraise. 632 * 633 * This function is called from notify_change(), which expects the caller 634 * to lock the inode's i_mutex. 635 */ 636static void ima_inode_post_setattr(struct mnt_idmap *idmap, 637 struct dentry *dentry, int ia_valid) 638{ 639 struct inode *inode = d_backing_inode(dentry); 640 struct ima_iint_cache *iint; 641 int action; 642 643 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode) 644 || !(inode->i_opflags & IOP_XATTR)) 645 return; 646 647 action = ima_must_appraise(idmap, inode, MAY_ACCESS, POST_SETATTR); 648 iint = ima_iint_find(inode); 649 if (iint) { 650 set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags); 651 if (!action) 652 clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); 653 } 654} 655 656/* 657 * ima_protect_xattr - protect 'security.ima' 658 * 659 * Ensure that not just anyone can modify or remove 'security.ima'. 660 */ 661static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, 662 const void *xattr_value, size_t xattr_value_len) 663{ 664 if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) { 665 if (!capable(CAP_SYS_ADMIN)) 666 return -EPERM; 667 return 1; 668 } 669 return 0; 670} 671 672static void ima_reset_appraise_flags(struct inode *inode, int digsig) 673{ 674 struct ima_iint_cache *iint; 675 676 if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)) 677 return; 678 679 iint = ima_iint_find(inode); 680 if (!iint) 681 return; 682 iint->measured_pcrs = 0; 683 set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags); 684 if (digsig) 685 set_bit(IMA_DIGSIG, &iint->atomic_flags); 686 else 687 clear_bit(IMA_DIGSIG, &iint->atomic_flags); 688} 689 690/** 691 * validate_hash_algo() - Block setxattr with unsupported hash algorithms 692 * @dentry: object of the setxattr() 693 * @xattr_value: userland supplied xattr value 694 * @xattr_value_len: length of xattr_value 695 * 696 * The xattr value is mapped to its hash algorithm, and this algorithm 697 * must be built in the kernel for the setxattr to be allowed. 698 * 699 * Emit an audit message when the algorithm is invalid. 700 * 701 * Return: 0 on success, else an error. 702 */ 703static int validate_hash_algo(struct dentry *dentry, 704 const struct evm_ima_xattr_data *xattr_value, 705 size_t xattr_value_len) 706{ 707 char *path = NULL, *pathbuf = NULL; 708 enum hash_algo xattr_hash_algo; 709 const char *errmsg = "unavailable-hash-algorithm"; 710 unsigned int allowed_hashes; 711 712 xattr_hash_algo = ima_get_hash_algo(xattr_value, xattr_value_len); 713 714 allowed_hashes = atomic_read(&ima_setxattr_allowed_hash_algorithms); 715 716 if (allowed_hashes) { 717 /* success if the algorithm is allowed in the ima policy */ 718 if (allowed_hashes & (1U << xattr_hash_algo)) 719 return 0; 720 721 /* 722 * We use a different audit message when the hash algorithm 723 * is denied by a policy rule, instead of not being built 724 * in the kernel image 725 */ 726 errmsg = "denied-hash-algorithm"; 727 } else { 728 if (likely(xattr_hash_algo == ima_hash_algo)) 729 return 0; 730 731 /* allow any xattr using an algorithm built in the kernel */ 732 if (crypto_has_alg(hash_algo_name[xattr_hash_algo], 0, 0)) 733 return 0; 734 } 735 736 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); 737 if (!pathbuf) 738 return -EACCES; 739 740 path = dentry_path(dentry, pathbuf, PATH_MAX); 741 742 integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path, 743 "set_data", errmsg, -EACCES, 0); 744 745 kfree(pathbuf); 746 747 return -EACCES; 748} 749 750static int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, 751 const char *xattr_name, const void *xattr_value, 752 size_t xattr_value_len, int flags) 753{ 754 const struct evm_ima_xattr_data *xvalue = xattr_value; 755 int digsig = 0; 756 int result; 757 int err; 758 759 result = ima_protect_xattr(dentry, xattr_name, xattr_value, 760 xattr_value_len); 761 if (result == 1) { 762 if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST)) 763 return -EINVAL; 764 765 err = validate_hash_algo(dentry, xvalue, xattr_value_len); 766 if (err) 767 return err; 768 769 digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG); 770 } else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) { 771 digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG); 772 } 773 if (result == 1 || evm_revalidate_status(xattr_name)) { 774 ima_reset_appraise_flags(d_backing_inode(dentry), digsig); 775 if (result == 1) 776 result = 0; 777 } 778 return result; 779} 780 781static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, 782 const char *acl_name, struct posix_acl *kacl) 783{ 784 if (evm_revalidate_status(acl_name)) 785 ima_reset_appraise_flags(d_backing_inode(dentry), 0); 786 787 return 0; 788} 789 790static int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, 791 const char *xattr_name) 792{ 793 int result; 794 795 result = ima_protect_xattr(dentry, xattr_name, NULL, 0); 796 if (result == 1 || evm_revalidate_status(xattr_name)) { 797 ima_reset_appraise_flags(d_backing_inode(dentry), 0); 798 if (result == 1) 799 result = 0; 800 } 801 return result; 802} 803 804static int ima_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, 805 const char *acl_name) 806{ 807 return ima_inode_set_acl(idmap, dentry, acl_name, NULL); 808} 809 810static struct security_hook_list ima_appraise_hooks[] __ro_after_init = { 811 LSM_HOOK_INIT(inode_post_setattr, ima_inode_post_setattr), 812 LSM_HOOK_INIT(inode_setxattr, ima_inode_setxattr), 813 LSM_HOOK_INIT(inode_set_acl, ima_inode_set_acl), 814 LSM_HOOK_INIT(inode_removexattr, ima_inode_removexattr), 815 LSM_HOOK_INIT(inode_remove_acl, ima_inode_remove_acl), 816}; 817 818void __init init_ima_appraise_lsm(const struct lsm_id *lsmid) 819{ 820 security_add_hooks(ima_appraise_hooks, ARRAY_SIZE(ima_appraise_hooks), 821 lsmid); 822} 823