summaryrefslogtreecommitdiff
path: root/security/integrity/ima/ima_appraise.c
blob: 3e0fbbd995342fcf80be6d5254bfe1bd78e01edc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011 IBM Corporation
 *
 * Author:
 * Mimi Zohar <zohar@us.ibm.com>
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/xattr.h>
#include <linux/magic.h>
#include <linux/ima.h>
#include <linux/evm.h>
#include <linux/fsverity.h>
#include <keys/system_keyring.h>
#include <uapi/linux/fsverity.h>

#include "ima.h"

#ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
static char *ima_appraise_cmdline_default __initdata;
core_param(ima_appraise, ima_appraise_cmdline_default, charp, 0);

void __init ima_appraise_parse_cmdline(void)
{
	const char *str = ima_appraise_cmdline_default;
	bool sb_state = arch_ima_get_secureboot();
	int appraisal_state = ima_appraise;

	if (!str)
		return;

	if (strncmp(str, "off", 3) == 0)
		appraisal_state = 0;
	else if (strncmp(str, "log", 3) == 0)
		appraisal_state = IMA_APPRAISE_LOG;
	else if (strncmp(str, "fix", 3) == 0)
		appraisal_state = IMA_APPRAISE_FIX;
	else if (strncmp(str, "enforce", 7) == 0)
		appraisal_state = IMA_APPRAISE_ENFORCE;
	else
		pr_err("invalid \"%s\" appraise option", str);

	/* If appraisal state was changed, but secure boot is enabled,
	 * keep its default */
	if (sb_state) {
		if (!(appraisal_state & IMA_APPRAISE_ENFORCE))
			pr_info("Secure boot enabled: ignoring ima_appraise=%s option",
				str);
	} else {
		ima_appraise = appraisal_state;
	}
}
#endif

/*
 * is_ima_appraise_enabled - return appraise status
 *
 * Only return enabled, if not in ima_appraise="fix" or "log" modes.
 */
bool is_ima_appraise_enabled(void)
{
	return ima_appraise & IMA_APPRAISE_ENFORCE;
}

/*
 * ima_must_appraise - set appraise flag
 *
 * Return 1 to appraise or hash
 */
int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
		      int mask, enum ima_hooks func)
{
	u32 secid;

	if (!ima_appraise)
		return 0;

	security_current_getsecid_subj(&secid);
	return ima_match_policy(mnt_userns, inode, current_cred(), secid,
				func, mask, IMA_APPRAISE | IMA_HASH, NULL,
				NULL, NULL, NULL);
}

static int ima_fix_xattr(struct dentry *dentry,
			 struct integrity_iint_cache *iint)
{
	int rc, offset;
	u8 algo = iint->ima_hash->algo;

	if (algo <= HASH_ALGO_SHA1) {
		offset = 1;
		iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST;
	} else {
		offset = 0;
		iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
		iint->ima_hash->xattr.ng.algo = algo;
	}
	rc = __vfs_setxattr_noperm(&init_user_ns, dentry, XATTR_NAME_IMA,
				   &iint->ima_hash->xattr.data[offset],
				   (sizeof(iint->ima_hash->xattr) - offset) +
				   iint->ima_hash->length, 0);
	return rc;
}

/* Return specific func appraised cached result */
enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
					   enum ima_hooks func)
{
	switch (func) {
	case MMAP_CHECK:
		return iint->ima_mmap_status;
	case BPRM_CHECK:
		return iint->ima_bprm_status;
	case CREDS_CHECK:
		return iint->ima_creds_status;
	case FILE_CHECK:
	case POST_SETATTR:
		return iint->ima_file_status;
	case MODULE_CHECK ... MAX_CHECK - 1:
	default:
		return iint->ima_read_status;
	}
}

static void ima_set_cache_status(struct integrity_iint_cache *iint,
				 enum ima_hooks func,
				 enum integrity_status status)
{
	switch (func) {
	case MMAP_CHECK:
		iint->ima_mmap_status = status;
		break;
	case BPRM_CHECK:
		iint->ima_bprm_status = status;
		break;
	case CREDS_CHECK:
		iint->ima_creds_status = status;
		break;
	case FILE_CHECK:
	case POST_SETATTR:
		iint->ima_file_status = status;
		break;
	case MODULE_CHECK ... MAX_CHECK - 1:
	default:
		iint->ima_read_status = status;
		break;
	}
}

static void ima_cache_flags(struct integrity_iint_cache *iint,
			     enum ima_hooks func)
{
	switch (func) {
	case MMAP_CHECK:
		iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
		break;
	case BPRM_CHECK:
		iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
		break;
	case CREDS_CHECK:
		iint->flags |= (IMA_CREDS_APPRAISED | IMA_APPRAISED);
		break;
	case FILE_CHECK:
	case POST_SETATTR:
		iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
		break;
	case MODULE_CHECK ... MAX_CHECK - 1:
	default:
		iint->flags |= (IMA_READ_APPRAISED | IMA_APPRAISED);
		break;
	}
}

enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value,
				 int xattr_len)
{
	struct signature_v2_hdr *sig;
	enum hash_algo ret;

	if (!xattr_value || xattr_len < 2)
		/* return default hash algo */
		return ima_hash_algo;

	switch (xattr_value->type) {
	case IMA_VERITY_DIGSIG:
		sig = (typeof(sig))xattr_value;
		if (sig->version != 3 || xattr_len <= sizeof(*sig) ||
		    sig->hash_algo >= HASH_ALGO__LAST)
			return ima_hash_algo;
		return sig->hash_algo;
	case EVM_IMA_XATTR_DIGSIG:
		sig = (typeof(sig))xattr_value;
		if (sig->version != 2 || xattr_len <= sizeof(*sig)
		    || sig->hash_algo >= HASH_ALGO__LAST)
			return ima_hash_algo;
		return sig->hash_algo;
	case IMA_XATTR_DIGEST_NG:
		/* first byte contains algorithm id */
		ret = xattr_value->data[0];
		if (ret < HASH_ALGO__LAST)
			return ret;
		break;
	case IMA_XATTR_DIGEST:
		/* this is for backward compatibility */
		if (xattr_len == 21) {
			unsigned int zero = 0;
			if (!memcmp(&xattr_value->data[16], &zero, 4))
				return HASH_ALGO_MD5;
			else
				return HASH_ALGO_SHA1;
		} else if (xattr_len == 17)
			return HASH_ALGO_MD5;
		break;
	}

	/* return default hash algo */
	return ima_hash_algo;
}

int ima_read_xattr(struct dentry *dentry,
		   struct evm_ima_xattr_data **xattr_value)
{
	ssize_t ret;

	ret = vfs_getxattr_alloc(&init_user_ns, dentry, XATTR_NAME_IMA,
				 (char **)xattr_value, 0, GFP_NOFS);
	if (ret == -EOPNOTSUPP)
		ret = 0;
	return ret;
}

/*
 * calc_file_id_hash - calculate the hash of the ima_file_id struct data
 * @type: xattr type [enum evm_ima_xattr_type]
 * @algo: hash algorithm [enum hash_algo]
 * @digest: pointer to the digest to be hashed
 * @hash: (out) pointer to the hash
 *
 * IMA signature version 3 disambiguates the data that is signed by
 * indirectly signing the hash of the ima_file_id structure data.
 *
 * Signing the ima_file_id struct is currently only supported for
 * IMA_VERITY_DIGSIG type xattrs.
 *
 * Return 0 on success, error code otherwise.
 */
static int calc_file_id_hash(enum evm_ima_xattr_type type,
			     enum hash_algo algo, const u8 *digest,
			     struct ima_digest_data *hash)
{
	struct ima_file_id file_id = {
		.hash_type = IMA_VERITY_DIGSIG, .hash_algorithm = algo};
	unsigned int unused = HASH_MAX_DIGESTSIZE - hash_digest_size[algo];

	if (type != IMA_VERITY_DIGSIG)
		return -EINVAL;

	memcpy(file_id.hash, digest, hash_digest_size[algo]);

	hash->algo = algo;
	hash->length = hash_digest_size[algo];

	return ima_calc_buffer_hash(&file_id, sizeof(file_id) - unused, hash);
}

/*
 * xattr_verify - verify xattr digest or signature
 *
 * Verify whether the hash or signature matches the file contents.
 *
 * Return 0 on success, error code otherwise.
 */
static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint,
			struct evm_ima_xattr_data *xattr_value, int xattr_len,
			enum integrity_status *status, const char **cause)
{
	struct ima_max_digest_data hash;
	struct signature_v2_hdr *sig;
	int rc = -EINVAL, hash_start = 0;
	int mask;

	switch (xattr_value->type) {
	case IMA_XATTR_DIGEST_NG:
		/* first byte contains algorithm id */
		hash_start = 1;
		fallthrough;
	case IMA_XATTR_DIGEST:
		if (*status != INTEGRITY_PASS_IMMUTABLE) {
			if (iint->flags & IMA_DIGSIG_REQUIRED) {
				if (iint->flags & IMA_VERITY_REQUIRED)
					*cause = "verity-signature-required";
				else
					*cause = "IMA-signature-required";
				*status = INTEGRITY_FAIL;
				break;
			}
			clear_bit(IMA_DIGSIG, &iint->atomic_flags);
		} else {
			set_bit(IMA_DIGSIG, &iint->atomic_flags);
		}
		if (xattr_len - sizeof(xattr_value->type) - hash_start >=
				iint->ima_hash->length)
			/*
			 * xattr length may be longer. md5 hash in previous
			 * version occupied 20 bytes in xattr, instead of 16
			 */
			rc = memcmp(&xattr_value->data[hash_start],
				    iint->ima_hash->digest,
				    iint->ima_hash->length);
		else
			rc = -EINVAL;
		if (rc) {
			*cause = "invalid-hash";
			*status = INTEGRITY_FAIL;
			break;
		}
		*status = INTEGRITY_PASS;
		break;
	case EVM_IMA_XATTR_DIGSIG:
		set_bit(IMA_DIGSIG, &iint->atomic_flags);

		mask = IMA_DIGSIG_REQUIRED | IMA_VERITY_REQUIRED;
		if ((iint->flags & mask) == mask) {
			*cause = "verity-signature-required";
			*status = INTEGRITY_FAIL;
			break;
		}

		sig = (typeof(sig))xattr_value;
		if (sig->version >= 3) {
			*cause = "invalid-signature-version";
			*status = INTEGRITY_FAIL;
			break;
		}
		rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
					     (const char *)xattr_value,
					     xattr_len,
					     iint->ima_hash->digest,
					     iint->ima_hash->length);
		if (rc == -EOPNOTSUPP) {
			*status = INTEGRITY_UNKNOWN;
			break;
		}
		if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
		    func == KEXEC_KERNEL_CHECK)
			rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM,
						     (const char *)xattr_value,
						     xattr_len,
						     iint->ima_hash->digest,
						     iint->ima_hash->length);
		if (rc) {
			*cause = "invalid-signature";
			*status = INTEGRITY_FAIL;
		} else {
			*status = INTEGRITY_PASS;
		}
		break;
	case IMA_VERITY_DIGSIG:
		set_bit(IMA_DIGSIG, &iint->atomic_flags);

		if (iint->flags & IMA_DIGSIG_REQUIRED) {
			if (!(iint->flags & IMA_VERITY_REQUIRED)) {
				*cause = "IMA-signature-required";
				*status = INTEGRITY_FAIL;
				break;
			}
		}

		sig = (typeof(sig))xattr_value;
		if (sig->version != 3) {
			*cause = "invalid-signature-version";
			*status = INTEGRITY_FAIL;
			break;
		}

		rc = calc_file_id_hash(IMA_VERITY_DIGSIG, iint->ima_hash->algo,
				       iint->ima_hash->digest, &hash.hdr);
		if (rc) {
			*cause = "sigv3-hashing-error";
			*status = INTEGRITY_FAIL;
			break;
		}

		rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
					     (const char *)xattr_value,
					     xattr_len, hash.digest,
					     hash.hdr.length);
		if (rc) {
			*cause = "invalid-verity-signature";
			*status = INTEGRITY_FAIL;
		} else {
			*status = INTEGRITY_PASS;
		}

		break;
	default:
		*status = INTEGRITY_UNKNOWN;
		*cause = "unknown-ima-data";
		break;
	}

	return rc;
}

/*
 * modsig_verify - verify modsig signature
 *
 * Verify whether the signature matches the file contents.
 *
 * Return 0 on success, error code otherwise.
 */
static int modsig_verify(enum ima_hooks func, const struct modsig *modsig,
			 enum integrity_status *status, const char **cause)
{
	int rc;

	rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig);
	if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
	    func == KEXEC_KERNEL_CHECK)
		rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM,
					     modsig);
	if (rc) {
		*cause = "invalid-signature";
		*status = INTEGRITY_FAIL;
	} else {
		*status = INTEGRITY_PASS;
	}

	return rc;
}

/*
 * ima_check_blacklist - determine if the binary is blacklisted.
 *
 * Add the hash of the blacklisted binary to the measurement list, based
 * on policy.
 *
 * Returns -EPERM if the hash is blacklisted.
 */
int ima_check_blacklist(struct integrity_iint_cache *iint,
			const struct modsig *modsig, int pcr)
{
	enum hash_algo hash_algo;
	const u8 *digest = NULL;
	u32 digestsize = 0;
	int rc = 0;

	if (!(iint->flags & IMA_CHECK_BLACKLIST))
		return 0;

	if (iint->flags & IMA_MODSIG_ALLOWED && modsig) {
		ima_get_modsig_digest(modsig, &hash_algo, &digest, &digestsize);

		rc = is_binary_blacklisted(digest, digestsize);
		if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
			process_buffer_measurement(&init_user_ns, NULL, digest, digestsize,
						   "blacklisted-hash", NONE,
						   pcr, NULL, false, NULL, 0);
	}

	return rc;
}

/*
 * ima_appraise_measurement - appraise file measurement
 *
 * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
 * Assuming success, compare the xattr hash with the collected measurement.
 *
 * Return 0 on success, error code otherwise
 */
int ima_appraise_measurement(enum ima_hooks func,
			     struct integrity_iint_cache *iint,
			     struct file *file, const unsigned char *filename,
			     struct evm_ima_xattr_data *xattr_value,
			     int xattr_len, const struct modsig *modsig)
{
	static const char op[] = "appraise_data";
	const char *cause = "unknown";
	struct dentry *dentry = file_dentry(file);
	struct inode *inode = d_backing_inode(dentry);
	enum integrity_status status = INTEGRITY_UNKNOWN;
	int rc = xattr_len;
	bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig;

	/* If not appraising a modsig, we need an xattr. */
	if (!(inode->i_opflags & IOP_XATTR) && !try_modsig)
		return INTEGRITY_UNKNOWN;

	/* If reading the xattr failed and there's no modsig, error out. */
	if (rc <= 0 && !try_modsig) {
		if (rc && rc != -ENODATA)
			goto out;

		if (iint->flags & IMA_DIGSIG_REQUIRED) {
			if (iint->flags & IMA_VERITY_REQUIRED)
				cause = "verity-signature-required";
			else
				cause = "IMA-signature-required";
		} else {
			cause = "missing-hash";
		}

		status = INTEGRITY_NOLABEL;
		if (file->f_mode & FMODE_CREATED)
			iint->flags |= IMA_NEW_FILE;
		if ((iint->flags & IMA_NEW_FILE) &&
		    (!(iint->flags & IMA_DIGSIG_REQUIRED) ||
		     (inode->i_size == 0)))
			status = INTEGRITY_PASS;
		goto out;
	}

	status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value,
				 rc < 0 ? 0 : rc, iint);
	switch (status) {
	case INTEGRITY_PASS:
	case INTEGRITY_PASS_IMMUTABLE:
	case INTEGRITY_UNKNOWN:
		break;
	case INTEGRITY_NOXATTRS:	/* No EVM protected xattrs. */
		/* It's fine not to have xattrs when using a modsig. */
		if (try_modsig)
			break;
		fallthrough;
	case INTEGRITY_NOLABEL:		/* No security.evm xattr. */
		cause = "missing-HMAC";
		goto out;
	case INTEGRITY_FAIL_IMMUTABLE:
		set_bit(IMA_DIGSIG, &iint->atomic_flags);
		cause = "invalid-fail-immutable";
		goto out;
	case INTEGRITY_FAIL:		/* Invalid HMAC/signature. */
		cause = "invalid-HMAC";
		goto out;
	default:
		WARN_ONCE(true, "Unexpected integrity status %d\n", status);
	}

	if (xattr_value)
		rc = xattr_verify(func, iint, xattr_value, xattr_len, &status,
				  &cause);

	/*
	 * If we have a modsig and either no imasig or the imasig's key isn't
	 * known, then try verifying the modsig.
	 */
	if (try_modsig &&
	    (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG ||
	     rc == -ENOKEY))
		rc = modsig_verify(func, modsig, &status, &cause);

out:
	/*
	 * File signatures on some filesystems can not be properly verified.
	 * When such filesystems are mounted by an untrusted mounter or on a
	 * system not willing to accept such a risk, fail the file signature
	 * verification.
	 */
	if ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
	    ((inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) ||
	     (iint->flags & IMA_FAIL_UNVERIFIABLE_SIGS))) {
		status = INTEGRITY_FAIL;
		cause = "unverifiable-signature";
		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
				    op, cause, rc, 0);
	} else if (status != INTEGRITY_PASS) {
		/* Fix mode, but don't replace file signatures. */
		if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig &&
		    (!xattr_value ||
		     xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
			if (!ima_fix_xattr(dentry, iint))
				status = INTEGRITY_PASS;
		}

		/*
		 * Permit new files with file/EVM portable signatures, but
		 * without data.
		 */
		if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE &&
		    test_bit(IMA_DIGSIG, &iint->atomic_flags)) {
			status = INTEGRITY_PASS;
		}

		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
				    op, cause, rc, 0);
	} else {
		ima_cache_flags(iint, func);
	}

	ima_set_cache_status(iint, func, status);
	return status;
}

/*
 * ima_update_xattr - update 'security.ima' hash value
 */
void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
{
	struct dentry *dentry = file_dentry(file);
	int rc = 0;

	/* do not collect and update hash for digital signatures */
	if (test_bit(IMA_DIGSIG, &iint->atomic_flags))
		return;

	if ((iint->ima_file_status != INTEGRITY_PASS) &&
	    !(iint->flags & IMA_HASH))
		return;

	rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL);
	if (rc < 0)
		return;

	inode_lock(file_inode(file));
	ima_fix_xattr(dentry, iint);
	inode_unlock(file_inode(file));
}

/**
 * ima_inode_post_setattr - reflect file metadata changes
 * @mnt_userns:	user namespace of the mount the inode was found from
 * @dentry: pointer to the affected dentry
 *
 * Changes to a dentry's metadata might result in needing to appraise.
 *
 * This function is called from notify_change(), which expects the caller
 * to lock the inode's i_mutex.
 */
void ima_inode_post_setattr(struct user_namespace *mnt_userns,
			    struct dentry *dentry)
{
	struct inode *inode = d_backing_inode(dentry);
	struct integrity_iint_cache *iint;
	int action;

	if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
	    || !(inode->i_opflags & IOP_XATTR))
		return;

	action = ima_must_appraise(mnt_userns, inode, MAY_ACCESS, POST_SETATTR);
	iint = integrity_iint_find(inode);
	if (iint) {
		set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags);
		if (!action)
			clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
	}
}

/*
 * ima_protect_xattr - protect 'security.ima'
 *
 * Ensure that not just anyone can modify or remove 'security.ima'.
 */
static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
			     const void *xattr_value, size_t xattr_value_len)
{
	if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
		return 1;
	}
	return 0;
}

static void ima_reset_appraise_flags(struct inode *inode, int digsig)
{
	struct integrity_iint_cache *iint;

	if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode))
		return;

	iint = integrity_iint_find(inode);
	if (!iint)
		return;
	iint->measured_pcrs = 0;
	set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags);
	if (digsig)
		set_bit(IMA_DIGSIG, &iint->atomic_flags);
	else
		clear_bit(IMA_DIGSIG, &iint->atomic_flags);
}

/**
 * validate_hash_algo() - Block setxattr with unsupported hash algorithms
 * @dentry: object of the setxattr()
 * @xattr_value: userland supplied xattr value
 * @xattr_value_len: length of xattr_value
 *
 * The xattr value is mapped to its hash algorithm, and this algorithm
 * must be built in the kernel for the setxattr to be allowed.
 *
 * Emit an audit message when the algorithm is invalid.
 *
 * Return: 0 on success, else an error.
 */
static int validate_hash_algo(struct dentry *dentry,
			      const struct evm_ima_xattr_data *xattr_value,
			      size_t xattr_value_len)
{
	char *path = NULL, *pathbuf = NULL;
	enum hash_algo xattr_hash_algo;
	const char *errmsg = "unavailable-hash-algorithm";
	unsigned int allowed_hashes;

	xattr_hash_algo = ima_get_hash_algo(xattr_value, xattr_value_len);

	allowed_hashes = atomic_read(&ima_setxattr_allowed_hash_algorithms);

	if (allowed_hashes) {
		/* success if the algorithm is allowed in the ima policy */
		if (allowed_hashes & (1U << xattr_hash_algo))
			return 0;

		/*
		 * We use a different audit message when the hash algorithm
		 * is denied by a policy rule, instead of not being built
		 * in the kernel image
		 */
		errmsg = "denied-hash-algorithm";
	} else {
		if (likely(xattr_hash_algo == ima_hash_algo))
			return 0;

		/* allow any xattr using an algorithm built in the kernel */
		if (crypto_has_alg(hash_algo_name[xattr_hash_algo], 0, 0))
			return 0;
	}

	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
	if (!pathbuf)
		return -EACCES;

	path = dentry_path(dentry, pathbuf, PATH_MAX);

	integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path,
			    "set_data", errmsg, -EACCES, 0);

	kfree(pathbuf);

	return -EACCES;
}

int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
		       const void *xattr_value, size_t xattr_value_len)
{
	const struct evm_ima_xattr_data *xvalue = xattr_value;
	int digsig = 0;
	int result;
	int err;

	result = ima_protect_xattr(dentry, xattr_name, xattr_value,
				   xattr_value_len);
	if (result == 1) {
		if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
			return -EINVAL;

		err = validate_hash_algo(dentry, xvalue, xattr_value_len);
		if (err)
			return err;

		digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
	} else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) {
		digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG);
	}
	if (result == 1 || evm_revalidate_status(xattr_name)) {
		ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
		if (result == 1)
			result = 0;
	}
	return result;
}

int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
{
	int result;

	result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
	if (result == 1 || evm_revalidate_status(xattr_name)) {
		ima_reset_appraise_flags(d_backing_inode(dentry), 0);
		if (result == 1)
			result = 0;
	}
	return result;
}