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