1 // SPDX-License-Identifier: GPL-2.0-only
3 * Integrity Measurement Architecture
5 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
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>
14 * implements the IMA hooks: ima_bprm_check, ima_file_mmap,
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/iversion.h>
32 #ifdef CONFIG_IMA_APPRAISE
33 int ima_appraise = IMA_APPRAISE_ENFORCE;
38 int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1;
39 static int hash_setup_done;
41 static struct notifier_block ima_lsm_policy_notifier = {
42 .notifier_call = ima_lsm_policy_change,
45 static int __init hash_setup(char *str)
47 struct ima_template_desc *template_desc = ima_template_desc_current();
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;
59 pr_err("invalid hash algorithm \"%s\" for template \"%s\"",
60 str, IMA_TEMPLATE_IMA_NAME);
66 i = match_string(hash_algo_name, HASH_ALGO__LAST, str);
68 pr_err("invalid hash algorithm \"%s\"", str);
77 __setup("ima_hash=", hash_setup);
79 enum hash_algo ima_get_current_hash_algo(void)
84 /* Prevent mmap'ing a file execute that is already mmap'ed write */
85 static int mmap_violation_check(enum ima_hooks func, struct file *file,
86 char **pathbuf, const char **pathname,
92 if ((func == MMAP_CHECK) && mapping_writably_mapped(file->f_mapping)) {
94 inode = file_inode(file);
96 if (!*pathbuf) /* ima_rdwr_violation possibly pre-fetched */
97 *pathname = ima_d_path(&file->f_path, pathbuf,
99 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, *pathname,
100 "mmap_file", "mmapped_writers", rc, 0);
106 * ima_rdwr_violation_check
108 * Only invalidate the PCR for measured files:
109 * - Opening a file for write when already open for read,
110 * results in a time of measure, time of use (ToMToU) error.
111 * - Opening a file for read when already open for write,
112 * could result in a file measurement error.
115 static void ima_rdwr_violation_check(struct file *file,
116 struct integrity_iint_cache *iint,
119 const char **pathname,
122 struct inode *inode = file_inode(file);
123 fmode_t mode = file->f_mode;
124 bool send_tomtou = false, send_writers = false;
126 if (mode & FMODE_WRITE) {
127 if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
129 iint = integrity_iint_find(inode);
130 /* IMA_MEASURE is set from reader side */
131 if (iint && test_bit(IMA_MUST_MEASURE,
132 &iint->atomic_flags))
137 set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
138 if (inode_is_open_for_write(inode) && must_measure)
142 if (!send_tomtou && !send_writers)
145 *pathname = ima_d_path(&file->f_path, pathbuf, filename);
148 ima_add_violation(file, *pathname, iint,
149 "invalid_pcr", "ToMToU");
151 ima_add_violation(file, *pathname, iint,
152 "invalid_pcr", "open_writers");
155 static void ima_check_last_writer(struct integrity_iint_cache *iint,
156 struct inode *inode, struct file *file)
158 fmode_t mode = file->f_mode;
161 if (!(mode & FMODE_WRITE))
164 mutex_lock(&iint->mutex);
165 if (atomic_read(&inode->i_writecount) == 1) {
166 update = test_and_clear_bit(IMA_UPDATE_XATTR,
167 &iint->atomic_flags);
168 if (!IS_I_VERSION(inode) ||
169 !inode_eq_iversion(inode, iint->version) ||
170 (iint->flags & IMA_NEW_FILE)) {
171 iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
172 iint->measured_pcrs = 0;
174 ima_update_xattr(iint, file);
177 mutex_unlock(&iint->mutex);
181 * ima_file_free - called on __fput()
182 * @file: pointer to file structure being freed
184 * Flag files that changed, based on i_version
186 void ima_file_free(struct file *file)
188 struct inode *inode = file_inode(file);
189 struct integrity_iint_cache *iint;
191 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
194 iint = integrity_iint_find(inode);
198 ima_check_last_writer(iint, inode, file);
201 static int process_measurement(struct file *file, const struct cred *cred,
202 u32 secid, char *buf, loff_t size, int mask,
205 struct inode *inode = file_inode(file);
206 struct integrity_iint_cache *iint = NULL;
207 struct ima_template_desc *template_desc = NULL;
208 char *pathbuf = NULL;
209 char filename[NAME_MAX];
210 const char *pathname = NULL;
211 int rc = 0, action, must_appraise = 0;
212 int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
213 struct evm_ima_xattr_data *xattr_value = NULL;
214 struct modsig *modsig = NULL;
216 bool violation_check;
217 enum hash_algo hash_algo;
218 unsigned int allowed_algos = 0;
220 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
223 /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
224 * bitmask based on the appraise/audit/measurement policy.
225 * Included is the appraise submask.
227 action = ima_get_action(file_mnt_user_ns(file), inode, cred, secid,
228 mask, func, &pcr, &template_desc, NULL,
230 violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
231 (ima_policy_flag & IMA_MEASURE));
232 if (!action && !violation_check)
235 must_appraise = action & IMA_APPRAISE;
237 /* Is the appraise rule hook specific? */
238 if (action & IMA_FILE_APPRAISE)
244 iint = integrity_inode_get(inode);
249 if (!rc && violation_check)
250 ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
251 &pathbuf, &pathname, filename);
260 mutex_lock(&iint->mutex);
262 if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
263 /* reset appraisal flags if ima_inode_post_setattr was called */
264 iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
265 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
269 * Re-evaulate the file if either the xattr has changed or the
270 * kernel has no way of detecting file change on the filesystem.
271 * (Limited to privileged mounted filesystems.)
273 if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) ||
274 ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
275 !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
276 !(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
277 iint->flags &= ~IMA_DONE_MASK;
278 iint->measured_pcrs = 0;
281 /* Determine if already appraised/measured based on bitmask
282 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
283 * IMA_AUDIT, IMA_AUDITED)
285 iint->flags |= action;
286 action &= IMA_DO_MASK;
287 action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
289 /* If target pcr is already measured, unset IMA_MEASURE action */
290 if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
291 action ^= IMA_MEASURE;
293 /* HASH sets the digital signature and update flags, nothing else */
294 if ((action & IMA_HASH) &&
295 !(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
296 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
297 if ((xattr_value && xattr_len > 2) &&
298 (xattr_value->type == EVM_IMA_XATTR_DIGSIG))
299 set_bit(IMA_DIGSIG, &iint->atomic_flags);
300 iint->flags |= IMA_HASHED;
302 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
305 /* Nothing to do, just return existing appraised status */
308 rc = mmap_violation_check(func, file, &pathbuf,
309 &pathname, filename);
311 rc = ima_get_cache_status(iint, func);
316 if ((action & IMA_APPRAISE_SUBMASK) ||
317 strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) {
318 /* read 'security.ima' */
319 xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
322 * Read the appended modsig if allowed by the policy, and allow
323 * an additional measurement list entry, if needed, based on the
324 * template format and whether the file was already measured.
326 if (iint->flags & IMA_MODSIG_ALLOWED) {
327 rc = ima_read_modsig(func, buf, size, &modsig);
329 if (!rc && ima_template_has_modsig(template_desc) &&
330 iint->flags & IMA_MEASURED)
331 action |= IMA_MEASURE;
335 hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
337 rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig);
338 if (rc != 0 && rc != -EBADF && rc != -EINVAL)
341 if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
342 pathname = ima_d_path(&file->f_path, &pathbuf, filename);
344 if (action & IMA_MEASURE)
345 ima_store_measurement(iint, file, pathname,
346 xattr_value, xattr_len, modsig, pcr,
348 if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
349 rc = ima_check_blacklist(iint, modsig, pcr);
352 rc = ima_appraise_measurement(func, iint, file,
353 pathname, xattr_value,
358 rc = mmap_violation_check(func, file, &pathbuf,
359 &pathname, filename);
361 if (action & IMA_AUDIT)
362 ima_audit_measurement(iint, pathname);
364 if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
367 /* Ensure the digest was generated using an allowed algorithm */
368 if (rc == 0 && must_appraise && allowed_algos != 0 &&
369 (allowed_algos & (1U << hash_algo)) == 0) {
372 integrity_audit_msg(AUDIT_INTEGRITY_DATA, file_inode(file),
373 pathname, "collect_data",
374 "denied-hash-algorithm", rc, 0);
377 if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
378 !(iint->flags & IMA_NEW_FILE))
380 mutex_unlock(&iint->mutex);
382 ima_free_modsig(modsig);
387 if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
389 if (file->f_mode & FMODE_WRITE)
390 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
396 * ima_file_mmap - based on policy, collect/store measurement.
397 * @file: pointer to the file to be measured (May be NULL)
398 * @prot: contains the protection that will be applied by the kernel.
400 * Measure files being mmapped executable based on the ima_must_measure()
403 * On success return 0. On integrity appraisal error, assuming the file
404 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
406 int ima_file_mmap(struct file *file, unsigned long prot)
410 if (file && (prot & PROT_EXEC)) {
411 security_task_getsecid_subj(current, &secid);
412 return process_measurement(file, current_cred(), secid, NULL,
413 0, MAY_EXEC, MMAP_CHECK);
420 * ima_file_mprotect - based on policy, limit mprotect change
421 * @prot: contains the protection that will be applied by the kernel.
423 * Files can be mmap'ed read/write and later changed to execute to circumvent
424 * IMA's mmap appraisal policy rules. Due to locking issues (mmap semaphore
425 * would be taken before i_mutex), files can not be measured or appraised at
426 * this point. Eliminate this integrity gap by denying the mprotect
427 * PROT_EXECUTE change, if an mmap appraise policy rule exists.
429 * On mprotect change success, return 0. On failure, return -EACESS.
431 int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
433 struct ima_template_desc *template = NULL;
434 struct file *file = vma->vm_file;
435 char filename[NAME_MAX];
436 char *pathbuf = NULL;
437 const char *pathname = NULL;
444 /* Is mprotect making an mmap'ed file executable? */
445 if (!(ima_policy_flag & IMA_APPRAISE) || !vma->vm_file ||
446 !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
449 security_task_getsecid_subj(current, &secid);
450 inode = file_inode(vma->vm_file);
451 action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
452 current_cred(), secid, MAY_EXEC, MMAP_CHECK,
453 &pcr, &template, NULL, NULL);
455 /* Is the mmap'ed file in policy? */
456 if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK)))
459 if (action & IMA_APPRAISE_SUBMASK)
463 pathname = ima_d_path(&file->f_path, &pathbuf, filename);
464 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, pathname,
465 "collect_data", "failed-mprotect", result, 0);
473 * ima_bprm_check - based on policy, collect/store measurement.
474 * @bprm: contains the linux_binprm structure
476 * The OS protects against an executable file, already open for write,
477 * from being executed in deny_write_access() and an executable file,
478 * already open for execute, from being modified in get_write_access().
479 * So we can be certain that what we verify and measure here is actually
480 * what is being executed.
482 * On success return 0. On integrity appraisal error, assuming the file
483 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
485 int ima_bprm_check(struct linux_binprm *bprm)
490 security_task_getsecid_subj(current, &secid);
491 ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
492 MAY_EXEC, BPRM_CHECK);
496 security_cred_getsecid(bprm->cred, &secid);
497 return process_measurement(bprm->file, bprm->cred, secid, NULL, 0,
498 MAY_EXEC, CREDS_CHECK);
502 * ima_file_check - based on policy, collect/store measurement.
503 * @file: pointer to the file to be measured
504 * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
506 * Measure files based on the ima_must_measure() policy decision.
508 * On success return 0. On integrity appraisal error, assuming the file
509 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
511 int ima_file_check(struct file *file, int mask)
515 security_task_getsecid_subj(current, &secid);
516 return process_measurement(file, current_cred(), secid, NULL, 0,
517 mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
518 MAY_APPEND), FILE_CHECK);
520 EXPORT_SYMBOL_GPL(ima_file_check);
522 static int __ima_inode_hash(struct inode *inode, char *buf, size_t buf_size)
524 struct integrity_iint_cache *iint;
527 if (!ima_policy_flag)
530 iint = integrity_iint_find(inode);
534 mutex_lock(&iint->mutex);
537 * ima_file_hash can be called when ima_collect_measurement has still
538 * not been called, we might not always have a hash.
540 if (!iint->ima_hash) {
541 mutex_unlock(&iint->mutex);
548 copied_size = min_t(size_t, iint->ima_hash->length, buf_size);
549 memcpy(buf, iint->ima_hash->digest, copied_size);
551 hash_algo = iint->ima_hash->algo;
552 mutex_unlock(&iint->mutex);
558 * ima_file_hash - return the stored measurement if a file has been hashed and
559 * is in the iint cache.
560 * @file: pointer to the file
561 * @buf: buffer in which to store the hash
562 * @buf_size: length of the buffer
564 * On success, return the hash algorithm (as defined in the enum hash_algo).
565 * If buf is not NULL, this function also outputs the hash into buf.
566 * If the hash is larger than buf_size, then only buf_size bytes will be copied.
567 * It generally just makes sense to pass a buffer capable of holding the largest
568 * possible hash: IMA_MAX_DIGEST_SIZE.
569 * The file hash returned is based on the entire file, including the appended
572 * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP.
573 * If the parameters are incorrect, return -EINVAL.
575 int ima_file_hash(struct file *file, char *buf, size_t buf_size)
580 return __ima_inode_hash(file_inode(file), buf, buf_size);
582 EXPORT_SYMBOL_GPL(ima_file_hash);
585 * ima_inode_hash - return the stored measurement if the inode has been hashed
586 * and is in the iint cache.
587 * @inode: pointer to the inode
588 * @buf: buffer in which to store the hash
589 * @buf_size: length of the buffer
591 * On success, return the hash algorithm (as defined in the enum hash_algo).
592 * If buf is not NULL, this function also outputs the hash into buf.
593 * If the hash is larger than buf_size, then only buf_size bytes will be copied.
594 * It generally just makes sense to pass a buffer capable of holding the largest
595 * possible hash: IMA_MAX_DIGEST_SIZE.
596 * The hash returned is based on the entire contents, including the appended
599 * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP.
600 * If the parameters are incorrect, return -EINVAL.
602 int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size)
607 return __ima_inode_hash(inode, buf, buf_size);
609 EXPORT_SYMBOL_GPL(ima_inode_hash);
612 * ima_post_create_tmpfile - mark newly created tmpfile as new
613 * @mnt_userns: user namespace of the mount the inode was found from
614 * @file : newly created tmpfile
616 * No measuring, appraising or auditing of newly created tmpfiles is needed.
617 * Skip calling process_measurement(), but indicate which newly, created
618 * tmpfiles are in policy.
620 void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
623 struct integrity_iint_cache *iint;
626 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
629 must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS,
634 /* Nothing to do if we can't allocate memory */
635 iint = integrity_inode_get(inode);
639 /* needed for writing the security xattrs */
640 set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
641 iint->ima_file_status = INTEGRITY_PASS;
645 * ima_post_path_mknod - mark as a new inode
646 * @mnt_userns: user namespace of the mount the inode was found from
647 * @dentry: newly created dentry
649 * Mark files created via the mknodat syscall as new, so that the
650 * file data can be written later.
652 void ima_post_path_mknod(struct user_namespace *mnt_userns,
653 struct dentry *dentry)
655 struct integrity_iint_cache *iint;
656 struct inode *inode = dentry->d_inode;
659 if (!ima_policy_flag || !S_ISREG(inode->i_mode))
662 must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS,
667 /* Nothing to do if we can't allocate memory */
668 iint = integrity_inode_get(inode);
672 /* needed for re-opening empty files */
673 iint->flags |= IMA_NEW_FILE;
677 * ima_read_file - pre-measure/appraise hook decision based on policy
678 * @file: pointer to the file to be measured/appraised/audit
679 * @read_id: caller identifier
680 * @contents: whether a subsequent call will be made to ima_post_read_file()
682 * Permit reading a file based on policy. The policy rules are written
683 * in terms of the policy identifier. Appraising the integrity of
684 * a file requires a file descriptor.
686 * For permission return 0, otherwise return -EACCES.
688 int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
695 * Do devices using pre-allocated memory run the risk of the
696 * firmware being accessible to the device prior to the completion
697 * of IMA's signature verification any more than when using two
698 * buffers? It may be desirable to include the buffer address
699 * in this API and walk all the dma_map_single() mappings to check.
703 * There will be a call made to ima_post_read_file() with
704 * a filled buffer, so we don't need to perform an extra
710 /* Read entire file for all partial reads. */
711 func = read_idmap[read_id] ?: FILE_CHECK;
712 security_task_getsecid_subj(current, &secid);
713 return process_measurement(file, current_cred(), secid, NULL,
717 const int read_idmap[READING_MAX_ID] = {
718 [READING_FIRMWARE] = FIRMWARE_CHECK,
719 [READING_MODULE] = MODULE_CHECK,
720 [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
721 [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
722 [READING_POLICY] = POLICY_CHECK
726 * ima_post_read_file - in memory collect/appraise/audit measurement
727 * @file: pointer to the file to be measured/appraised/audit
728 * @buf: pointer to in memory file contents
729 * @size: size of in memory file contents
730 * @read_id: caller identifier
732 * Measure/appraise/audit in memory file based on policy. Policy rules
733 * are written in terms of a policy identifier.
735 * On success return 0. On integrity appraisal error, assuming the file
736 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
738 int ima_post_read_file(struct file *file, void *buf, loff_t size,
739 enum kernel_read_file_id read_id)
744 /* permit signed certs */
745 if (!file && read_id == READING_X509_CERTIFICATE)
748 if (!file || !buf || size == 0) { /* should never happen */
749 if (ima_appraise & IMA_APPRAISE_ENFORCE)
754 func = read_idmap[read_id] ?: FILE_CHECK;
755 security_task_getsecid_subj(current, &secid);
756 return process_measurement(file, current_cred(), secid, buf, size,
761 * ima_load_data - appraise decision based on policy
762 * @id: kernel load data caller identifier
763 * @contents: whether the full contents will be available in a later
764 * call to ima_post_load_data().
766 * Callers of this LSM hook can not measure, appraise, or audit the
767 * data provided by userspace. Enforce policy rules requring a file
768 * signature (eg. kexec'ed kernel image).
770 * For permission return 0, otherwise return -EACCES.
772 int ima_load_data(enum kernel_load_data_id id, bool contents)
774 bool ima_enforce, sig_enforce;
777 (ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE;
780 case LOADING_KEXEC_IMAGE:
781 if (IS_ENABLED(CONFIG_KEXEC_SIG)
782 && arch_ima_get_secureboot()) {
783 pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
787 if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) {
788 pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
789 return -EACCES; /* INTEGRITY_UNKNOWN */
792 case LOADING_FIRMWARE:
793 if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE) && !contents) {
794 pr_err("Prevent firmware sysfs fallback loading.\n");
795 return -EACCES; /* INTEGRITY_UNKNOWN */
799 sig_enforce = is_module_sig_enforced();
801 if (ima_enforce && (!sig_enforce
802 && (ima_appraise & IMA_APPRAISE_MODULES))) {
803 pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
804 return -EACCES; /* INTEGRITY_UNKNOWN */
814 * ima_post_load_data - appraise decision based on policy
815 * @buf: pointer to in memory file contents
816 * @size: size of in memory file contents
817 * @id: kernel load data caller identifier
818 * @description: @id-specific description of contents
820 * Measure/appraise/audit in memory buffer based on policy. Policy rules
821 * are written in terms of a policy identifier.
823 * On success return 0. On integrity appraisal error, assuming the file
824 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
826 int ima_post_load_data(char *buf, loff_t size,
827 enum kernel_load_data_id load_id,
830 if (load_id == LOADING_FIRMWARE) {
831 if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
832 (ima_appraise & IMA_APPRAISE_ENFORCE)) {
833 pr_err("Prevent firmware loading_store.\n");
834 return -EACCES; /* INTEGRITY_UNKNOWN */
843 * process_buffer_measurement - Measure the buffer or the buffer data hash
844 * @mnt_userns: user namespace of the mount the inode was found from
845 * @inode: inode associated with the object being measured (NULL for KEY_CHECK)
846 * @buf: pointer to the buffer that needs to be added to the log.
847 * @size: size of buffer(in bytes).
848 * @eventname: event name to be used for the buffer entry.
850 * @pcr: pcr to extend the measurement
851 * @func_data: func specific data, may be NULL
852 * @buf_hash: measure buffer data hash
853 * @digest: buffer digest will be written to
854 * @digest_len: buffer length
856 * Based on policy, either the buffer data or buffer data hash is measured
858 * Return: 0 if the buffer has been successfully measured, 1 if the digest
859 * has been written to the passed location but not added to a measurement entry,
860 * a negative value otherwise.
862 int process_buffer_measurement(struct user_namespace *mnt_userns,
863 struct inode *inode, const void *buf, int size,
864 const char *eventname, enum ima_hooks func,
865 int pcr, const char *func_data,
866 bool buf_hash, u8 *digest, size_t digest_len)
869 const char *audit_cause = "ENOMEM";
870 struct ima_template_entry *entry = NULL;
871 struct integrity_iint_cache iint = {};
872 struct ima_event_data event_data = {.iint = &iint,
873 .filename = eventname,
876 struct ima_template_desc *template;
878 struct ima_digest_data hdr;
879 char digest[IMA_MAX_DIGEST_SIZE];
881 char digest_hash[IMA_MAX_DIGEST_SIZE];
882 int digest_hash_len = hash_digest_size[ima_hash_algo];
887 if (digest && digest_len < digest_hash_len)
890 if (!ima_policy_flag && !digest)
893 template = ima_template_desc_buf();
896 audit_cause = "ima_template_desc_buf";
901 * Both LSM hooks and auxilary based buffer measurements are
902 * based on policy. To avoid code duplication, differentiate
903 * between the LSM hooks and auxilary buffer measurements,
904 * retrieving the policy rule information only for the LSM hook
905 * buffer measurements.
908 security_task_getsecid_subj(current, &secid);
909 action = ima_get_action(mnt_userns, inode, current_cred(),
910 secid, 0, func, &pcr, &template,
912 if (!(action & IMA_MEASURE) && !digest)
917 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
919 iint.ima_hash = &hash.hdr;
920 iint.ima_hash->algo = ima_hash_algo;
921 iint.ima_hash->length = hash_digest_size[ima_hash_algo];
923 ret = ima_calc_buffer_hash(buf, size, iint.ima_hash);
925 audit_cause = "hashing_error";
930 memcpy(digest_hash, hash.hdr.digest, digest_hash_len);
932 ret = ima_calc_buffer_hash(digest_hash, digest_hash_len,
935 audit_cause = "hashing_error";
939 event_data.buf = digest_hash;
940 event_data.buf_len = digest_hash_len;
944 memcpy(digest, iint.ima_hash->digest, digest_hash_len);
946 if (!ima_policy_flag || (func && !(action & IMA_MEASURE)))
949 ret = ima_alloc_init_template(&event_data, &entry, template);
951 audit_cause = "alloc_entry";
955 ret = ima_store_template(entry, violation, NULL, event_data.buf, pcr);
957 audit_cause = "store_entry";
958 ima_free_template_entry(entry);
963 integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL, eventname,
964 func_measure_str(func),
965 audit_cause, ret, 0, ret);
971 * ima_kexec_cmdline - measure kexec cmdline boot args
972 * @kernel_fd: file descriptor of the kexec kernel being loaded
973 * @buf: pointer to buffer
974 * @size: size of buffer
976 * Buffers can only be measured, not appraised.
978 void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
985 f = fdget(kernel_fd);
989 process_buffer_measurement(file_mnt_user_ns(f.file), file_inode(f.file),
990 buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0,
991 NULL, false, NULL, 0);
996 * ima_measure_critical_data - measure kernel integrity critical data
997 * @event_label: unique event label for grouping and limiting critical data
998 * @event_name: event name for the record in the IMA measurement list
999 * @buf: pointer to buffer data
1000 * @buf_len: length of buffer data (in bytes)
1001 * @hash: measure buffer data hash
1002 * @digest: buffer digest will be written to
1003 * @digest_len: buffer length
1005 * Measure data critical to the integrity of the kernel into the IMA log
1006 * and extend the pcr. Examples of critical data could be various data
1007 * structures, policies, and states stored in kernel memory that can
1008 * impact the integrity of the system.
1010 * Return: 0 if the buffer has been successfully measured, 1 if the digest
1011 * has been written to the passed location but not added to a measurement entry,
1012 * a negative value otherwise.
1014 int ima_measure_critical_data(const char *event_label,
1015 const char *event_name,
1016 const void *buf, size_t buf_len,
1017 bool hash, u8 *digest, size_t digest_len)
1019 if (!event_name || !event_label || !buf || !buf_len)
1022 return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
1023 event_name, CRITICAL_DATA, 0,
1024 event_label, hash, digest,
1027 EXPORT_SYMBOL_GPL(ima_measure_critical_data);
1029 static int __init init_ima(void)
1033 ima_appraise_parse_cmdline();
1034 ima_init_template_list();
1035 hash_setup(CONFIG_IMA_DEFAULT_HASH);
1038 if (error && strcmp(hash_algo_name[ima_hash_algo],
1039 CONFIG_IMA_DEFAULT_HASH) != 0) {
1040 pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
1041 hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
1042 hash_setup_done = 0;
1043 hash_setup(CONFIG_IMA_DEFAULT_HASH);
1050 error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
1052 pr_warn("Couldn't register LSM notifier, error %d\n", error);
1055 ima_update_policy_flags();
1060 late_initcall(init_ima); /* Start IMA after the TPM is available */