1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * Integrity Measurement Architecture 4 * 5 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 6 * 7 * Authors: 8 * Reiner Sailer <sailer@watson.ibm.com> 9 * Serge Hallyn <serue@us.ibm.com> 10 * Kylene Hall <kylene@us.ibm.com> 11 * Mimi Zohar <zohar@us.ibm.com> 12 * 13 * File: ima_main.c 14 * implements the IMA hooks: ima_bprm_check, ima_file_mmap, 15 * and ima_file_check. 16 */ 17 18#include <linux/module.h> 19#include <linux/file.h> 20#include <linux/binfmts.h> 21#include <linux/kernel_read_file.h> 22#include <linux/mount.h> 23#include <linux/mman.h> 24#include <linux/slab.h> 25#include <linux/xattr.h> 26#include <linux/ima.h> 27#include <linux/fs.h> 28#include <linux/iversion.h> 29 30#include "ima.h" 31 32#ifdef CONFIG_IMA_APPRAISE 33int ima_appraise = IMA_APPRAISE_ENFORCE; 34#else 35int ima_appraise; 36#endif 37 38int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1; 39static int hash_setup_done; 40 41static struct notifier_block ima_lsm_policy_notifier = { 42 .notifier_call = ima_lsm_policy_change, 43}; 44 45static int __init hash_setup(char *str) 46{ 47 struct ima_template_desc *template_desc = ima_template_desc_current(); 48 int i; 49 50 if (hash_setup_done) 51 return 1; 52 53 if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) { 54 if (strncmp(str, "sha1", 4) == 0) { 55 ima_hash_algo = HASH_ALGO_SHA1; 56 } else if (strncmp(str, "md5", 3) == 0) { 57 ima_hash_algo = HASH_ALGO_MD5; 58 } else { 59 pr_err("invalid hash algorithm \"%s\" for template \"%s\"", 60 str, IMA_TEMPLATE_IMA_NAME); 61 return 1; 62 } 63 goto out; 64 } 65 66 i = match_string(hash_algo_name, HASH_ALGO__LAST, str); 67 if (i < 0) { 68 pr_err("invalid hash algorithm \"%s\"", str); 69 return 1; 70 } 71 72 ima_hash_algo = i; 73out: 74 hash_setup_done = 1; 75 return 1; 76} 77__setup("ima_hash=", hash_setup); 78 79enum hash_algo ima_get_current_hash_algo(void) 80{ 81 return ima_hash_algo; 82} 83 84/* Prevent mmap'ing a file execute that is already mmap'ed write */ 85static int mmap_violation_check(enum ima_hooks func, struct file *file, 86 char **pathbuf, const char **pathname, 87 char *filename) 88{ 89 struct inode *inode; 90 int rc = 0; 91 92 if ((func == MMAP_CHECK || func == MMAP_CHECK_REQPROT) && 93 mapping_writably_mapped(file->f_mapping)) { 94 rc = -ETXTBSY; 95 inode = file_inode(file); 96 97 if (!*pathbuf) /* ima_rdwr_violation possibly pre-fetched */ 98 *pathname = ima_d_path(&file->f_path, pathbuf, 99 filename); 100 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, *pathname, 101 "mmap_file", "mmapped_writers", rc, 0); 102 } 103 return rc; 104} 105 106/* 107 * ima_rdwr_violation_check 108 * 109 * Only invalidate the PCR for measured files: 110 * - Opening a file for write when already open for read, 111 * results in a time of measure, time of use (ToMToU) error. 112 * - Opening a file for read when already open for write, 113 * could result in a file measurement error. 114 * 115 */ 116static void ima_rdwr_violation_check(struct file *file, 117 struct ima_iint_cache *iint, 118 int must_measure, 119 char **pathbuf, 120 const char **pathname, 121 char *filename) 122{ 123 struct inode *inode = file_inode(file); 124 fmode_t mode = file->f_mode; 125 bool send_tomtou = false, send_writers = false; 126 127 if (mode & FMODE_WRITE) { 128 if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) { 129 if (!iint) 130 iint = ima_iint_find(inode); 131 /* IMA_MEASURE is set from reader side */ 132 if (iint && test_bit(IMA_MUST_MEASURE, 133 &iint->atomic_flags)) 134 send_tomtou = true; 135 } 136 } else { 137 if (must_measure) 138 set_bit(IMA_MUST_MEASURE, &iint->atomic_flags); 139 if (inode_is_open_for_write(inode) && must_measure) 140 send_writers = true; 141 } 142 143 if (!send_tomtou && !send_writers) 144 return; 145 146 *pathname = ima_d_path(&file->f_path, pathbuf, filename); 147 148 if (send_tomtou) 149 ima_add_violation(file, *pathname, iint, 150 "invalid_pcr", "ToMToU"); 151 if (send_writers) 152 ima_add_violation(file, *pathname, iint, 153 "invalid_pcr", "open_writers"); 154} 155 156static void ima_check_last_writer(struct ima_iint_cache *iint, 157 struct inode *inode, struct file *file) 158{ 159 fmode_t mode = file->f_mode; 160 bool update; 161 162 if (!(mode & FMODE_WRITE)) 163 return; 164 165 mutex_lock(&iint->mutex); 166 if (atomic_read(&inode->i_writecount) == 1) { 167 struct kstat stat; 168 169 update = test_and_clear_bit(IMA_UPDATE_XATTR, 170 &iint->atomic_flags); 171 if ((iint->flags & IMA_NEW_FILE) || 172 vfs_getattr_nosec(&file->f_path, &stat, 173 STATX_CHANGE_COOKIE, 174 AT_STATX_SYNC_AS_STAT) || 175 !(stat.result_mask & STATX_CHANGE_COOKIE) || 176 stat.change_cookie != iint->version) { 177 iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE); 178 iint->measured_pcrs = 0; 179 if (update) 180 ima_update_xattr(iint, file); 181 } 182 } 183 mutex_unlock(&iint->mutex); 184} 185 186/** 187 * ima_file_free - called on __fput() 188 * @file: pointer to file structure being freed 189 * 190 * Flag files that changed, based on i_version 191 */ 192static void ima_file_free(struct file *file) 193{ 194 struct inode *inode = file_inode(file); 195 struct ima_iint_cache *iint; 196 197 if (!ima_policy_flag || !S_ISREG(inode->i_mode)) 198 return; 199 200 iint = ima_iint_find(inode); 201 if (!iint) 202 return; 203 204 ima_check_last_writer(iint, inode, file); 205} 206 207static int process_measurement(struct file *file, const struct cred *cred, 208 u32 secid, char *buf, loff_t size, int mask, 209 enum ima_hooks func) 210{ 211 struct inode *backing_inode, *inode = file_inode(file); 212 struct ima_iint_cache *iint = NULL; 213 struct ima_template_desc *template_desc = NULL; 214 char *pathbuf = NULL; 215 char filename[NAME_MAX]; 216 const char *pathname = NULL; 217 int rc = 0, action, must_appraise = 0; 218 int pcr = CONFIG_IMA_MEASURE_PCR_IDX; 219 struct evm_ima_xattr_data *xattr_value = NULL; 220 struct modsig *modsig = NULL; 221 int xattr_len = 0; 222 bool violation_check; 223 enum hash_algo hash_algo; 224 unsigned int allowed_algos = 0; 225 226 if (!ima_policy_flag || !S_ISREG(inode->i_mode)) 227 return 0; 228 229 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action 230 * bitmask based on the appraise/audit/measurement policy. 231 * Included is the appraise submask. 232 */ 233 action = ima_get_action(file_mnt_idmap(file), inode, cred, secid, 234 mask, func, &pcr, &template_desc, NULL, 235 &allowed_algos); 236 violation_check = ((func == FILE_CHECK || func == MMAP_CHECK || 237 func == MMAP_CHECK_REQPROT) && 238 (ima_policy_flag & IMA_MEASURE)); 239 if (!action && !violation_check) 240 return 0; 241 242 must_appraise = action & IMA_APPRAISE; 243 244 /* Is the appraise rule hook specific? */ 245 if (action & IMA_FILE_APPRAISE) 246 func = FILE_CHECK; 247 248 inode_lock(inode); 249 250 if (action) { 251 iint = ima_inode_get(inode); 252 if (!iint) 253 rc = -ENOMEM; 254 } 255 256 if (!rc && violation_check) 257 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE, 258 &pathbuf, &pathname, filename); 259 260 inode_unlock(inode); 261 262 if (rc) 263 goto out; 264 if (!action) 265 goto out; 266 267 mutex_lock(&iint->mutex); 268 269 if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags)) 270 /* reset appraisal flags if ima_inode_post_setattr was called */ 271 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED | 272 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK | 273 IMA_NONACTION_FLAGS); 274 275 /* 276 * Re-evaulate the file if either the xattr has changed or the 277 * kernel has no way of detecting file change on the filesystem. 278 * (Limited to privileged mounted filesystems.) 279 */ 280 if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) || 281 ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) && 282 !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) && 283 !(action & IMA_FAIL_UNVERIFIABLE_SIGS))) { 284 iint->flags &= ~IMA_DONE_MASK; 285 iint->measured_pcrs = 0; 286 } 287 288 /* Detect and re-evaluate changes made to the backing file. */ 289 backing_inode = d_real_inode(file_dentry(file)); 290 if (backing_inode != inode && 291 (action & IMA_DO_MASK) && (iint->flags & IMA_DONE_MASK)) { 292 if (!IS_I_VERSION(backing_inode) || 293 backing_inode->i_sb->s_dev != iint->real_dev || 294 backing_inode->i_ino != iint->real_ino || 295 !inode_eq_iversion(backing_inode, iint->version)) { 296 iint->flags &= ~IMA_DONE_MASK; 297 iint->measured_pcrs = 0; 298 } 299 } 300 301 /* Determine if already appraised/measured based on bitmask 302 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, 303 * IMA_AUDIT, IMA_AUDITED) 304 */ 305 iint->flags |= action; 306 action &= IMA_DO_MASK; 307 action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1); 308 309 /* If target pcr is already measured, unset IMA_MEASURE action */ 310 if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr))) 311 action ^= IMA_MEASURE; 312 313 /* HASH sets the digital signature and update flags, nothing else */ 314 if ((action & IMA_HASH) && 315 !(test_bit(IMA_DIGSIG, &iint->atomic_flags))) { 316 xattr_len = ima_read_xattr(file_dentry(file), 317 &xattr_value, xattr_len); 318 if ((xattr_value && xattr_len > 2) && 319 (xattr_value->type == EVM_IMA_XATTR_DIGSIG)) 320 set_bit(IMA_DIGSIG, &iint->atomic_flags); 321 iint->flags |= IMA_HASHED; 322 action ^= IMA_HASH; 323 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); 324 } 325 326 /* Nothing to do, just return existing appraised status */ 327 if (!action) { 328 if (must_appraise) { 329 rc = mmap_violation_check(func, file, &pathbuf, 330 &pathname, filename); 331 if (!rc) 332 rc = ima_get_cache_status(iint, func); 333 } 334 goto out_locked; 335 } 336 337 if ((action & IMA_APPRAISE_SUBMASK) || 338 strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) { 339 /* read 'security.ima' */ 340 xattr_len = ima_read_xattr(file_dentry(file), 341 &xattr_value, xattr_len); 342 343 /* 344 * Read the appended modsig if allowed by the policy, and allow 345 * an additional measurement list entry, if needed, based on the 346 * template format and whether the file was already measured. 347 */ 348 if (iint->flags & IMA_MODSIG_ALLOWED) { 349 rc = ima_read_modsig(func, buf, size, &modsig); 350 351 if (!rc && ima_template_has_modsig(template_desc) && 352 iint->flags & IMA_MEASURED) 353 action |= IMA_MEASURE; 354 } 355 } 356 357 hash_algo = ima_get_hash_algo(xattr_value, xattr_len); 358 359 rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig); 360 if (rc != 0 && rc != -EBADF && rc != -EINVAL) 361 goto out_locked; 362 363 if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */ 364 pathname = ima_d_path(&file->f_path, &pathbuf, filename); 365 366 if (action & IMA_MEASURE) 367 ima_store_measurement(iint, file, pathname, 368 xattr_value, xattr_len, modsig, pcr, 369 template_desc); 370 if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) { 371 rc = ima_check_blacklist(iint, modsig, pcr); 372 if (rc != -EPERM) { 373 inode_lock(inode); 374 rc = ima_appraise_measurement(func, iint, file, 375 pathname, xattr_value, 376 xattr_len, modsig); 377 inode_unlock(inode); 378 } 379 if (!rc) 380 rc = mmap_violation_check(func, file, &pathbuf, 381 &pathname, filename); 382 } 383 if (action & IMA_AUDIT) 384 ima_audit_measurement(iint, pathname); 385 386 if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO)) 387 rc = 0; 388 389 /* Ensure the digest was generated using an allowed algorithm */ 390 if (rc == 0 && must_appraise && allowed_algos != 0 && 391 (allowed_algos & (1U << hash_algo)) == 0) { 392 rc = -EACCES; 393 394 integrity_audit_msg(AUDIT_INTEGRITY_DATA, file_inode(file), 395 pathname, "collect_data", 396 "denied-hash-algorithm", rc, 0); 397 } 398out_locked: 399 if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) && 400 !(iint->flags & IMA_NEW_FILE)) 401 rc = -EACCES; 402 mutex_unlock(&iint->mutex); 403 kfree(xattr_value); 404 ima_free_modsig(modsig); 405out: 406 if (pathbuf) 407 __putname(pathbuf); 408 if (must_appraise) { 409 if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE)) 410 return -EACCES; 411 if (file->f_mode & FMODE_WRITE) 412 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); 413 } 414 return 0; 415} 416 417/** 418 * ima_file_mmap - based on policy, collect/store measurement. 419 * @file: pointer to the file to be measured (May be NULL) 420 * @reqprot: protection requested by the application 421 * @prot: protection that will be applied by the kernel 422 * @flags: operational flags 423 * 424 * Measure files being mmapped executable based on the ima_must_measure() 425 * policy decision. 426 * 427 * On success return 0. On integrity appraisal error, assuming the file 428 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. 429 */ 430static int ima_file_mmap(struct file *file, unsigned long reqprot, 431 unsigned long prot, unsigned long flags) 432{ 433 u32 secid; 434 int ret; 435 436 if (!file) 437 return 0; 438 439 security_current_getsecid_subj(&secid); 440 441 if (reqprot & PROT_EXEC) { 442 ret = process_measurement(file, current_cred(), secid, NULL, 443 0, MAY_EXEC, MMAP_CHECK_REQPROT); 444 if (ret) 445 return ret; 446 } 447 448 if (prot & PROT_EXEC) 449 return process_measurement(file, current_cred(), secid, NULL, 450 0, MAY_EXEC, MMAP_CHECK); 451 452 return 0; 453} 454 455/** 456 * ima_file_mprotect - based on policy, limit mprotect change 457 * @vma: vm_area_struct protection is set to 458 * @reqprot: protection requested by the application 459 * @prot: protection that will be applied by the kernel 460 * 461 * Files can be mmap'ed read/write and later changed to execute to circumvent 462 * IMA's mmap appraisal policy rules. Due to locking issues (mmap semaphore 463 * would be taken before i_mutex), files can not be measured or appraised at 464 * this point. Eliminate this integrity gap by denying the mprotect 465 * PROT_EXECUTE change, if an mmap appraise policy rule exists. 466 * 467 * On mprotect change success, return 0. On failure, return -EACESS. 468 */ 469static int ima_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot, 470 unsigned long prot) 471{ 472 struct ima_template_desc *template = NULL; 473 struct file *file; 474 char filename[NAME_MAX]; 475 char *pathbuf = NULL; 476 const char *pathname = NULL; 477 struct inode *inode; 478 int result = 0; 479 int action; 480 u32 secid; 481 int pcr; 482 483 /* Is mprotect making an mmap'ed file executable? */ 484 if (!(ima_policy_flag & IMA_APPRAISE) || !vma->vm_file || 485 !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC)) 486 return 0; 487 488 security_current_getsecid_subj(&secid); 489 inode = file_inode(vma->vm_file); 490 action = ima_get_action(file_mnt_idmap(vma->vm_file), inode, 491 current_cred(), secid, MAY_EXEC, MMAP_CHECK, 492 &pcr, &template, NULL, NULL); 493 action |= ima_get_action(file_mnt_idmap(vma->vm_file), inode, 494 current_cred(), secid, MAY_EXEC, 495 MMAP_CHECK_REQPROT, &pcr, &template, NULL, 496 NULL); 497 498 /* Is the mmap'ed file in policy? */ 499 if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK))) 500 return 0; 501 502 if (action & IMA_APPRAISE_SUBMASK) 503 result = -EPERM; 504 505 file = vma->vm_file; 506 pathname = ima_d_path(&file->f_path, &pathbuf, filename); 507 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, pathname, 508 "collect_data", "failed-mprotect", result, 0); 509 if (pathbuf) 510 __putname(pathbuf); 511 512 return result; 513} 514 515/** 516 * ima_bprm_check - based on policy, collect/store measurement. 517 * @bprm: contains the linux_binprm structure 518 * 519 * The OS protects against an executable file, already open for write, 520 * from being executed in deny_write_access() and an executable file, 521 * already open for execute, from being modified in get_write_access(). 522 * So we can be certain that what we verify and measure here is actually 523 * what is being executed. 524 * 525 * On success return 0. On integrity appraisal error, assuming the file 526 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. 527 */ 528static int ima_bprm_check(struct linux_binprm *bprm) 529{ 530 int ret; 531 u32 secid; 532 533 security_current_getsecid_subj(&secid); 534 ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0, 535 MAY_EXEC, BPRM_CHECK); 536 if (ret) 537 return ret; 538 539 security_cred_getsecid(bprm->cred, &secid); 540 return process_measurement(bprm->file, bprm->cred, secid, NULL, 0, 541 MAY_EXEC, CREDS_CHECK); 542} 543 544/** 545 * ima_file_check - based on policy, collect/store measurement. 546 * @file: pointer to the file to be measured 547 * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND 548 * 549 * Measure files based on the ima_must_measure() policy decision. 550 * 551 * On success return 0. On integrity appraisal error, assuming the file 552 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. 553 */ 554static int ima_file_check(struct file *file, int mask) 555{ 556 u32 secid; 557 558 security_current_getsecid_subj(&secid); 559 return process_measurement(file, current_cred(), secid, NULL, 0, 560 mask & (MAY_READ | MAY_WRITE | MAY_EXEC | 561 MAY_APPEND), FILE_CHECK); 562} 563 564static int __ima_inode_hash(struct inode *inode, struct file *file, char *buf, 565 size_t buf_size) 566{ 567 struct ima_iint_cache *iint = NULL, tmp_iint; 568 int rc, hash_algo; 569 570 if (ima_policy_flag) { 571 iint = ima_iint_find(inode); 572 if (iint) 573 mutex_lock(&iint->mutex); 574 } 575 576 if ((!iint || !(iint->flags & IMA_COLLECTED)) && file) { 577 if (iint) 578 mutex_unlock(&iint->mutex); 579 580 memset(&tmp_iint, 0, sizeof(tmp_iint)); 581 mutex_init(&tmp_iint.mutex); 582 583 rc = ima_collect_measurement(&tmp_iint, file, NULL, 0, 584 ima_hash_algo, NULL); 585 if (rc < 0) { 586 /* ima_hash could be allocated in case of failure. */ 587 if (rc != -ENOMEM) 588 kfree(tmp_iint.ima_hash); 589 590 return -EOPNOTSUPP; 591 } 592 593 iint = &tmp_iint; 594 mutex_lock(&iint->mutex); 595 } 596 597 if (!iint) 598 return -EOPNOTSUPP; 599 600 /* 601 * ima_file_hash can be called when ima_collect_measurement has still 602 * not been called, we might not always have a hash. 603 */ 604 if (!iint->ima_hash || !(iint->flags & IMA_COLLECTED)) { 605 mutex_unlock(&iint->mutex); 606 return -EOPNOTSUPP; 607 } 608 609 if (buf) { 610 size_t copied_size; 611 612 copied_size = min_t(size_t, iint->ima_hash->length, buf_size); 613 memcpy(buf, iint->ima_hash->digest, copied_size); 614 } 615 hash_algo = iint->ima_hash->algo; 616 mutex_unlock(&iint->mutex); 617 618 if (iint == &tmp_iint) 619 kfree(iint->ima_hash); 620 621 return hash_algo; 622} 623 624/** 625 * ima_file_hash - return a measurement of the file 626 * @file: pointer to the file 627 * @buf: buffer in which to store the hash 628 * @buf_size: length of the buffer 629 * 630 * On success, return the hash algorithm (as defined in the enum hash_algo). 631 * If buf is not NULL, this function also outputs the hash into buf. 632 * If the hash is larger than buf_size, then only buf_size bytes will be copied. 633 * It generally just makes sense to pass a buffer capable of holding the largest 634 * possible hash: IMA_MAX_DIGEST_SIZE. 635 * The file hash returned is based on the entire file, including the appended 636 * signature. 637 * 638 * If the measurement cannot be performed, return -EOPNOTSUPP. 639 * If the parameters are incorrect, return -EINVAL. 640 */ 641int ima_file_hash(struct file *file, char *buf, size_t buf_size) 642{ 643 if (!file) 644 return -EINVAL; 645 646 return __ima_inode_hash(file_inode(file), file, buf, buf_size); 647} 648EXPORT_SYMBOL_GPL(ima_file_hash); 649 650/** 651 * ima_inode_hash - return the stored measurement if the inode has been hashed 652 * and is in the iint cache. 653 * @inode: pointer to the inode 654 * @buf: buffer in which to store the hash 655 * @buf_size: length of the buffer 656 * 657 * On success, return the hash algorithm (as defined in the enum hash_algo). 658 * If buf is not NULL, this function also outputs the hash into buf. 659 * If the hash is larger than buf_size, then only buf_size bytes will be copied. 660 * It generally just makes sense to pass a buffer capable of holding the largest 661 * possible hash: IMA_MAX_DIGEST_SIZE. 662 * The hash returned is based on the entire contents, including the appended 663 * signature. 664 * 665 * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. 666 * If the parameters are incorrect, return -EINVAL. 667 */ 668int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) 669{ 670 if (!inode) 671 return -EINVAL; 672 673 return __ima_inode_hash(inode, NULL, buf, buf_size); 674} 675EXPORT_SYMBOL_GPL(ima_inode_hash); 676 677/** 678 * ima_post_create_tmpfile - mark newly created tmpfile as new 679 * @idmap: idmap of the mount the inode was found from 680 * @inode: inode of the newly created tmpfile 681 * 682 * No measuring, appraising or auditing of newly created tmpfiles is needed. 683 * Skip calling process_measurement(), but indicate which newly, created 684 * tmpfiles are in policy. 685 */ 686static void ima_post_create_tmpfile(struct mnt_idmap *idmap, 687 struct inode *inode) 688 689{ 690 struct ima_iint_cache *iint; 691 int must_appraise; 692 693 if (!ima_policy_flag || !S_ISREG(inode->i_mode)) 694 return; 695 696 must_appraise = ima_must_appraise(idmap, inode, MAY_ACCESS, 697 FILE_CHECK); 698 if (!must_appraise) 699 return; 700 701 /* Nothing to do if we can't allocate memory */ 702 iint = ima_inode_get(inode); 703 if (!iint) 704 return; 705 706 /* needed for writing the security xattrs */ 707 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); 708 iint->ima_file_status = INTEGRITY_PASS; 709} 710 711/** 712 * ima_post_path_mknod - mark as a new inode 713 * @idmap: idmap of the mount the inode was found from 714 * @dentry: newly created dentry 715 * 716 * Mark files created via the mknodat syscall as new, so that the 717 * file data can be written later. 718 */ 719static void ima_post_path_mknod(struct mnt_idmap *idmap, struct dentry *dentry) 720{ 721 struct ima_iint_cache *iint; 722 struct inode *inode = dentry->d_inode; 723 int must_appraise; 724 725 if (!ima_policy_flag || !S_ISREG(inode->i_mode)) 726 return; 727 728 must_appraise = ima_must_appraise(idmap, inode, MAY_ACCESS, 729 FILE_CHECK); 730 if (!must_appraise) 731 return; 732 733 /* Nothing to do if we can't allocate memory */ 734 iint = ima_inode_get(inode); 735 if (!iint) 736 return; 737 738 /* needed for re-opening empty files */ 739 iint->flags |= IMA_NEW_FILE; 740} 741 742/** 743 * ima_read_file - pre-measure/appraise hook decision based on policy 744 * @file: pointer to the file to be measured/appraised/audit 745 * @read_id: caller identifier 746 * @contents: whether a subsequent call will be made to ima_post_read_file() 747 * 748 * Permit reading a file based on policy. The policy rules are written 749 * in terms of the policy identifier. Appraising the integrity of 750 * a file requires a file descriptor. 751 * 752 * For permission return 0, otherwise return -EACCES. 753 */ 754static int ima_read_file(struct file *file, enum kernel_read_file_id read_id, 755 bool contents) 756{ 757 enum ima_hooks func; 758 u32 secid; 759 760 /* 761 * Do devices using pre-allocated memory run the risk of the 762 * firmware being accessible to the device prior to the completion 763 * of IMA's signature verification any more than when using two 764 * buffers? It may be desirable to include the buffer address 765 * in this API and walk all the dma_map_single() mappings to check. 766 */ 767 768 /* 769 * There will be a call made to ima_post_read_file() with 770 * a filled buffer, so we don't need to perform an extra 771 * read early here. 772 */ 773 if (contents) 774 return 0; 775 776 /* Read entire file for all partial reads. */ 777 func = read_idmap[read_id] ?: FILE_CHECK; 778 security_current_getsecid_subj(&secid); 779 return process_measurement(file, current_cred(), secid, NULL, 780 0, MAY_READ, func); 781} 782 783const int read_idmap[READING_MAX_ID] = { 784 [READING_FIRMWARE] = FIRMWARE_CHECK, 785 [READING_MODULE] = MODULE_CHECK, 786 [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK, 787 [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK, 788 [READING_POLICY] = POLICY_CHECK 789}; 790 791/** 792 * ima_post_read_file - in memory collect/appraise/audit measurement 793 * @file: pointer to the file to be measured/appraised/audit 794 * @buf: pointer to in memory file contents 795 * @size: size of in memory file contents 796 * @read_id: caller identifier 797 * 798 * Measure/appraise/audit in memory file based on policy. Policy rules 799 * are written in terms of a policy identifier. 800 * 801 * On success return 0. On integrity appraisal error, assuming the file 802 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. 803 */ 804static int ima_post_read_file(struct file *file, char *buf, loff_t size, 805 enum kernel_read_file_id read_id) 806{ 807 enum ima_hooks func; 808 u32 secid; 809 810 /* permit signed certs */ 811 if (!file && read_id == READING_X509_CERTIFICATE) 812 return 0; 813 814 if (!file || !buf || size == 0) { /* should never happen */ 815 if (ima_appraise & IMA_APPRAISE_ENFORCE) 816 return -EACCES; 817 return 0; 818 } 819 820 func = read_idmap[read_id] ?: FILE_CHECK; 821 security_current_getsecid_subj(&secid); 822 return process_measurement(file, current_cred(), secid, buf, size, 823 MAY_READ, func); 824} 825 826/** 827 * ima_load_data - appraise decision based on policy 828 * @id: kernel load data caller identifier 829 * @contents: whether the full contents will be available in a later 830 * call to ima_post_load_data(). 831 * 832 * Callers of this LSM hook can not measure, appraise, or audit the 833 * data provided by userspace. Enforce policy rules requiring a file 834 * signature (eg. kexec'ed kernel image). 835 * 836 * For permission return 0, otherwise return -EACCES. 837 */ 838static int ima_load_data(enum kernel_load_data_id id, bool contents) 839{ 840 bool ima_enforce, sig_enforce; 841 842 ima_enforce = 843 (ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE; 844 845 switch (id) { 846 case LOADING_KEXEC_IMAGE: 847 if (IS_ENABLED(CONFIG_KEXEC_SIG) 848 && arch_ima_get_secureboot()) { 849 pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); 850 return -EACCES; 851 } 852 853 if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) { 854 pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); 855 return -EACCES; /* INTEGRITY_UNKNOWN */ 856 } 857 break; 858 case LOADING_FIRMWARE: 859 if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE) && !contents) { 860 pr_err("Prevent firmware sysfs fallback loading.\n"); 861 return -EACCES; /* INTEGRITY_UNKNOWN */ 862 } 863 break; 864 case LOADING_MODULE: 865 sig_enforce = is_module_sig_enforced(); 866 867 if (ima_enforce && (!sig_enforce 868 && (ima_appraise & IMA_APPRAISE_MODULES))) { 869 pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n"); 870 return -EACCES; /* INTEGRITY_UNKNOWN */ 871 } 872 break; 873 default: 874 break; 875 } 876 return 0; 877} 878 879/** 880 * ima_post_load_data - appraise decision based on policy 881 * @buf: pointer to in memory file contents 882 * @size: size of in memory file contents 883 * @load_id: kernel load data caller identifier 884 * @description: @load_id-specific description of contents 885 * 886 * Measure/appraise/audit in memory buffer based on policy. Policy rules 887 * are written in terms of a policy identifier. 888 * 889 * On success return 0. On integrity appraisal error, assuming the file 890 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. 891 */ 892static int ima_post_load_data(char *buf, loff_t size, 893 enum kernel_load_data_id load_id, 894 char *description) 895{ 896 if (load_id == LOADING_FIRMWARE) { 897 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && 898 (ima_appraise & IMA_APPRAISE_ENFORCE)) { 899 pr_err("Prevent firmware loading_store.\n"); 900 return -EACCES; /* INTEGRITY_UNKNOWN */ 901 } 902 return 0; 903 } 904 905 return 0; 906} 907 908/** 909 * process_buffer_measurement - Measure the buffer or the buffer data hash 910 * @idmap: idmap of the mount the inode was found from 911 * @inode: inode associated with the object being measured (NULL for KEY_CHECK) 912 * @buf: pointer to the buffer that needs to be added to the log. 913 * @size: size of buffer(in bytes). 914 * @eventname: event name to be used for the buffer entry. 915 * @func: IMA hook 916 * @pcr: pcr to extend the measurement 917 * @func_data: func specific data, may be NULL 918 * @buf_hash: measure buffer data hash 919 * @digest: buffer digest will be written to 920 * @digest_len: buffer length 921 * 922 * Based on policy, either the buffer data or buffer data hash is measured 923 * 924 * Return: 0 if the buffer has been successfully measured, 1 if the digest 925 * has been written to the passed location but not added to a measurement entry, 926 * a negative value otherwise. 927 */ 928int process_buffer_measurement(struct mnt_idmap *idmap, 929 struct inode *inode, const void *buf, int size, 930 const char *eventname, enum ima_hooks func, 931 int pcr, const char *func_data, 932 bool buf_hash, u8 *digest, size_t digest_len) 933{ 934 int ret = 0; 935 const char *audit_cause = "ENOMEM"; 936 struct ima_template_entry *entry = NULL; 937 struct ima_iint_cache iint = {}; 938 struct ima_event_data event_data = {.iint = &iint, 939 .filename = eventname, 940 .buf = buf, 941 .buf_len = size}; 942 struct ima_template_desc *template; 943 struct ima_max_digest_data hash; 944 char digest_hash[IMA_MAX_DIGEST_SIZE]; 945 int digest_hash_len = hash_digest_size[ima_hash_algo]; 946 int violation = 0; 947 int action = 0; 948 u32 secid; 949 950 if (digest && digest_len < digest_hash_len) 951 return -EINVAL; 952 953 if (!ima_policy_flag && !digest) 954 return -ENOENT; 955 956 template = ima_template_desc_buf(); 957 if (!template) { 958 ret = -EINVAL; 959 audit_cause = "ima_template_desc_buf"; 960 goto out; 961 } 962 963 /* 964 * Both LSM hooks and auxilary based buffer measurements are 965 * based on policy. To avoid code duplication, differentiate 966 * between the LSM hooks and auxilary buffer measurements, 967 * retrieving the policy rule information only for the LSM hook 968 * buffer measurements. 969 */ 970 if (func) { 971 security_current_getsecid_subj(&secid); 972 action = ima_get_action(idmap, inode, current_cred(), 973 secid, 0, func, &pcr, &template, 974 func_data, NULL); 975 if (!(action & IMA_MEASURE) && !digest) 976 return -ENOENT; 977 } 978 979 if (!pcr) 980 pcr = CONFIG_IMA_MEASURE_PCR_IDX; 981 982 iint.ima_hash = &hash.hdr; 983 iint.ima_hash->algo = ima_hash_algo; 984 iint.ima_hash->length = hash_digest_size[ima_hash_algo]; 985 986 ret = ima_calc_buffer_hash(buf, size, iint.ima_hash); 987 if (ret < 0) { 988 audit_cause = "hashing_error"; 989 goto out; 990 } 991 992 if (buf_hash) { 993 memcpy(digest_hash, hash.hdr.digest, digest_hash_len); 994 995 ret = ima_calc_buffer_hash(digest_hash, digest_hash_len, 996 iint.ima_hash); 997 if (ret < 0) { 998 audit_cause = "hashing_error"; 999 goto out; 1000 } 1001 1002 event_data.buf = digest_hash; 1003 event_data.buf_len = digest_hash_len; 1004 } 1005 1006 if (digest) 1007 memcpy(digest, iint.ima_hash->digest, digest_hash_len); 1008 1009 if (!ima_policy_flag || (func && !(action & IMA_MEASURE))) 1010 return 1; 1011 1012 ret = ima_alloc_init_template(&event_data, &entry, template); 1013 if (ret < 0) { 1014 audit_cause = "alloc_entry"; 1015 goto out; 1016 } 1017 1018 ret = ima_store_template(entry, violation, NULL, event_data.buf, pcr); 1019 if (ret < 0) { 1020 audit_cause = "store_entry"; 1021 ima_free_template_entry(entry); 1022 } 1023 1024out: 1025 if (ret < 0) 1026 integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL, eventname, 1027 func_measure_str(func), 1028 audit_cause, ret, 0, ret); 1029 1030 return ret; 1031} 1032 1033/** 1034 * ima_kexec_cmdline - measure kexec cmdline boot args 1035 * @kernel_fd: file descriptor of the kexec kernel being loaded 1036 * @buf: pointer to buffer 1037 * @size: size of buffer 1038 * 1039 * Buffers can only be measured, not appraised. 1040 */ 1041void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) 1042{ 1043 struct fd f; 1044 1045 if (!buf || !size) 1046 return; 1047 1048 f = fdget(kernel_fd); 1049 if (!f.file) 1050 return; 1051 1052 process_buffer_measurement(file_mnt_idmap(f.file), file_inode(f.file), 1053 buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0, 1054 NULL, false, NULL, 0); 1055 fdput(f); 1056} 1057 1058/** 1059 * ima_measure_critical_data - measure kernel integrity critical data 1060 * @event_label: unique event label for grouping and limiting critical data 1061 * @event_name: event name for the record in the IMA measurement list 1062 * @buf: pointer to buffer data 1063 * @buf_len: length of buffer data (in bytes) 1064 * @hash: measure buffer data hash 1065 * @digest: buffer digest will be written to 1066 * @digest_len: buffer length 1067 * 1068 * Measure data critical to the integrity of the kernel into the IMA log 1069 * and extend the pcr. Examples of critical data could be various data 1070 * structures, policies, and states stored in kernel memory that can 1071 * impact the integrity of the system. 1072 * 1073 * Return: 0 if the buffer has been successfully measured, 1 if the digest 1074 * has been written to the passed location but not added to a measurement entry, 1075 * a negative value otherwise. 1076 */ 1077int ima_measure_critical_data(const char *event_label, 1078 const char *event_name, 1079 const void *buf, size_t buf_len, 1080 bool hash, u8 *digest, size_t digest_len) 1081{ 1082 if (!event_name || !event_label || !buf || !buf_len) 1083 return -ENOPARAM; 1084 1085 return process_buffer_measurement(&nop_mnt_idmap, NULL, buf, buf_len, 1086 event_name, CRITICAL_DATA, 0, 1087 event_label, hash, digest, 1088 digest_len); 1089} 1090EXPORT_SYMBOL_GPL(ima_measure_critical_data); 1091 1092#ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS 1093 1094/** 1095 * ima_kernel_module_request - Prevent crypto-pkcs1pad(rsa,*) requests 1096 * @kmod_name: kernel module name 1097 * 1098 * Avoid a verification loop where verifying the signature of the modprobe 1099 * binary requires executing modprobe itself. Since the modprobe iint->mutex 1100 * is already held when the signature verification is performed, a deadlock 1101 * occurs as soon as modprobe is executed within the critical region, since 1102 * the same lock cannot be taken again. 1103 * 1104 * This happens when public_key_verify_signature(), in case of RSA algorithm, 1105 * use alg_name to store internal information in order to construct an 1106 * algorithm on the fly, but crypto_larval_lookup() will try to use alg_name 1107 * in order to load a kernel module with same name. 1108 * 1109 * Since we don't have any real "crypto-pkcs1pad(rsa,*)" kernel modules, 1110 * we are safe to fail such module request from crypto_larval_lookup(), and 1111 * avoid the verification loop. 1112 * 1113 * Return: Zero if it is safe to load the kernel module, -EINVAL otherwise. 1114 */ 1115static int ima_kernel_module_request(char *kmod_name) 1116{ 1117 if (strncmp(kmod_name, "crypto-pkcs1pad(rsa,", 20) == 0) 1118 return -EINVAL; 1119 1120 return 0; 1121} 1122 1123#endif /* CONFIG_INTEGRITY_ASYMMETRIC_KEYS */ 1124 1125static int __init init_ima(void) 1126{ 1127 int error; 1128 1129 ima_appraise_parse_cmdline(); 1130 ima_init_template_list(); 1131 hash_setup(CONFIG_IMA_DEFAULT_HASH); 1132 error = ima_init(); 1133 1134 if (error && strcmp(hash_algo_name[ima_hash_algo], 1135 CONFIG_IMA_DEFAULT_HASH) != 0) { 1136 pr_info("Allocating %s failed, going to use default hash algorithm %s\n", 1137 hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH); 1138 hash_setup_done = 0; 1139 hash_setup(CONFIG_IMA_DEFAULT_HASH); 1140 error = ima_init(); 1141 } 1142 1143 if (error) 1144 return error; 1145 1146 error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier); 1147 if (error) 1148 pr_warn("Couldn't register LSM notifier, error %d\n", error); 1149 1150 if (!error) 1151 ima_update_policy_flags(); 1152 1153 return error; 1154} 1155 1156static struct security_hook_list ima_hooks[] __ro_after_init = { 1157 LSM_HOOK_INIT(bprm_check_security, ima_bprm_check), 1158 LSM_HOOK_INIT(file_post_open, ima_file_check), 1159 LSM_HOOK_INIT(inode_post_create_tmpfile, ima_post_create_tmpfile), 1160 LSM_HOOK_INIT(file_release, ima_file_free), 1161 LSM_HOOK_INIT(mmap_file, ima_file_mmap), 1162 LSM_HOOK_INIT(file_mprotect, ima_file_mprotect), 1163 LSM_HOOK_INIT(kernel_load_data, ima_load_data), 1164 LSM_HOOK_INIT(kernel_post_load_data, ima_post_load_data), 1165 LSM_HOOK_INIT(kernel_read_file, ima_read_file), 1166 LSM_HOOK_INIT(kernel_post_read_file, ima_post_read_file), 1167 LSM_HOOK_INIT(path_post_mknod, ima_post_path_mknod), 1168#ifdef CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS 1169 LSM_HOOK_INIT(key_post_create_or_update, ima_post_key_create_or_update), 1170#endif 1171#ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS 1172 LSM_HOOK_INIT(kernel_module_request, ima_kernel_module_request), 1173#endif 1174 LSM_HOOK_INIT(inode_free_security, ima_inode_free), 1175}; 1176 1177static const struct lsm_id ima_lsmid = { 1178 .name = "ima", 1179 .id = LSM_ID_IMA, 1180}; 1181 1182static int __init init_ima_lsm(void) 1183{ 1184 ima_iintcache_init(); 1185 security_add_hooks(ima_hooks, ARRAY_SIZE(ima_hooks), &ima_lsmid); 1186 init_ima_appraise_lsm(&ima_lsmid); 1187 return 0; 1188} 1189 1190struct lsm_blob_sizes ima_blob_sizes __ro_after_init = { 1191 .lbs_inode = sizeof(struct ima_iint_cache *), 1192}; 1193 1194DEFINE_LSM(ima) = { 1195 .name = "ima", 1196 .init = init_ima_lsm, 1197 .order = LSM_ORDER_LAST, 1198 .blobs = &ima_blob_sizes, 1199}; 1200 1201late_initcall(init_ima); /* Start IMA after the TPM is available */ 1202