summaryrefslogtreecommitdiff
path: root/security/integrity/ima/ima_crypto.c
blob: 38f2ed830dd6fb23c216b014e39405318705d8ee (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
/*
 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
 *
 * Authors:
 * Mimi Zohar <zohar@us.ibm.com>
 * Kylene Hall <kjhall@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2 of the License.
 *
 * File: ima_crypto.c
 *	Calculates md5/sha1 file hash, template hash, boot-aggreate hash
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/ratelimit.h>
#include <linux/file.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <crypto/hash.h>

#include "ima.h"

struct ahash_completion {
	struct completion completion;
	int err;
};

/* minimum file size for ahash use */
static unsigned long ima_ahash_minsize;
module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");

/* default is 0 - 1 page. */
static int ima_maxorder;
static unsigned int ima_bufsize = PAGE_SIZE;

static int param_set_bufsize(const char *val, const struct kernel_param *kp)
{
	unsigned long long size;
	int order;

	size = memparse(val, NULL);
	order = get_order(size);
	if (order >= MAX_ORDER)
		return -EINVAL;
	ima_maxorder = order;
	ima_bufsize = PAGE_SIZE << order;
	return 0;
}

static const struct kernel_param_ops param_ops_bufsize = {
	.set = param_set_bufsize,
	.get = param_get_uint,
};
#define param_check_bufsize(name, p) __param_check(name, p, unsigned int)

module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");

static struct crypto_shash *ima_shash_tfm;
static struct crypto_ahash *ima_ahash_tfm;

int __init ima_init_crypto(void)
{
	long rc;

	ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
	if (IS_ERR(ima_shash_tfm)) {
		rc = PTR_ERR(ima_shash_tfm);
		pr_err("Can not allocate %s (reason: %ld)\n",
		       hash_algo_name[ima_hash_algo], rc);
		return rc;
	}
	return 0;
}

static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
{
	struct crypto_shash *tfm = ima_shash_tfm;
	int rc;

	if (algo < 0 || algo >= HASH_ALGO__LAST)
		algo = ima_hash_algo;

	if (algo != ima_hash_algo) {
		tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
		if (IS_ERR(tfm)) {
			rc = PTR_ERR(tfm);
			pr_err("Can not allocate %s (reason: %d)\n",
			       hash_algo_name[algo], rc);
		}
	}
	return tfm;
}

static void ima_free_tfm(struct crypto_shash *tfm)
{
	if (tfm != ima_shash_tfm)
		crypto_free_shash(tfm);
}

/**
 * ima_alloc_pages() - Allocate contiguous pages.
 * @max_size:       Maximum amount of memory to allocate.
 * @allocated_size: Returned size of actual allocation.
 * @last_warn:      Should the min_size allocation warn or not.
 *
 * Tries to do opportunistic allocation for memory first trying to allocate
 * max_size amount of memory and then splitting that until zero order is
 * reached. Allocation is tried without generating allocation warnings unless
 * last_warn is set. Last_warn set affects only last allocation of zero order.
 *
 * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
 *
 * Return pointer to allocated memory, or NULL on failure.
 */
static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size,
			     int last_warn)
{
	void *ptr;
	int order = ima_maxorder;
	gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY;

	if (order)
		order = min(get_order(max_size), order);

	for (; order; order--) {
		ptr = (void *)__get_free_pages(gfp_mask, order);
		if (ptr) {
			*allocated_size = PAGE_SIZE << order;
			return ptr;
		}
	}

	/* order is zero - one page */

	gfp_mask = GFP_KERNEL;

	if (!last_warn)
		gfp_mask |= __GFP_NOWARN;

	ptr = (void *)__get_free_pages(gfp_mask, 0);
	if (ptr) {
		*allocated_size = PAGE_SIZE;
		return ptr;
	}

	*allocated_size = 0;
	return NULL;
}

/**
 * ima_free_pages() - Free pages allocated by ima_alloc_pages().
 * @ptr:  Pointer to allocated pages.
 * @size: Size of allocated buffer.
 */
static void ima_free_pages(void *ptr, size_t size)
{
	if (!ptr)
		return;
	free_pages((unsigned long)ptr, get_order(size));
}

static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
{
	struct crypto_ahash *tfm = ima_ahash_tfm;
	int rc;

	if (algo < 0 || algo >= HASH_ALGO__LAST)
		algo = ima_hash_algo;

	if (algo != ima_hash_algo || !tfm) {
		tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
		if (!IS_ERR(tfm)) {
			if (algo == ima_hash_algo)
				ima_ahash_tfm = tfm;
		} else {
			rc = PTR_ERR(tfm);
			pr_err("Can not allocate %s (reason: %d)\n",
			       hash_algo_name[algo], rc);
		}
	}
	return tfm;
}

static void ima_free_atfm(struct crypto_ahash *tfm)
{
	if (tfm != ima_ahash_tfm)
		crypto_free_ahash(tfm);
}

static void ahash_complete(struct crypto_async_request *req, int err)
{
	struct ahash_completion *res = req->data;

	if (err == -EINPROGRESS)
		return;
	res->err = err;
	complete(&res->completion);
}

static int ahash_wait(int err, struct ahash_completion *res)
{
	switch (err) {
	case 0:
		break;
	case -EINPROGRESS:
	case -EBUSY:
		wait_for_completion(&res->completion);
		reinit_completion(&res->completion);
		err = res->err;
		/* fall through */
	default:
		pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);
	}

	return err;
}

static int ima_calc_file_hash_atfm(struct file *file,
				   struct ima_digest_data *hash,
				   struct crypto_ahash *tfm)
{
	loff_t i_size, offset;
	char *rbuf[2] = { NULL, };
	int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
	struct ahash_request *req;
	struct scatterlist sg[1];
	struct ahash_completion res;
	size_t rbuf_size[2];

	hash->length = crypto_ahash_digestsize(tfm);

	req = ahash_request_alloc(tfm, GFP_KERNEL);
	if (!req)
		return -ENOMEM;

	init_completion(&res.completion);
	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
				   CRYPTO_TFM_REQ_MAY_SLEEP,
				   ahash_complete, &res);

	rc = ahash_wait(crypto_ahash_init(req), &res);
	if (rc)
		goto out1;

	i_size = i_size_read(file_inode(file));

	if (i_size == 0)
		goto out2;

	/*
	 * Try to allocate maximum size of memory.
	 * Fail if even a single page cannot be allocated.
	 */
	rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
	if (!rbuf[0]) {
		rc = -ENOMEM;
		goto out1;
	}

	/* Only allocate one buffer if that is enough. */
	if (i_size > rbuf_size[0]) {
		/*
		 * Try to allocate secondary buffer. If that fails fallback to
		 * using single buffering. Use previous memory allocation size
		 * as baseline for possible allocation size.
		 */
		rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
					  &rbuf_size[1], 0);
	}

	if (!(file->f_mode & FMODE_READ)) {
		file->f_mode |= FMODE_READ;
		read = 1;
	}

	for (offset = 0; offset < i_size; offset += rbuf_len) {
		if (!rbuf[1] && offset) {
			/* Not using two buffers, and it is not the first
			 * read/request, wait for the completion of the
			 * previous ahash_update() request.
			 */
			rc = ahash_wait(ahash_rc, &res);
			if (rc)
				goto out3;
		}
		/* read buffer */
		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
		rc = integrity_kernel_read(file, offset, rbuf[active],
					   rbuf_len);
		if (rc != rbuf_len)
			goto out3;

		if (rbuf[1] && offset) {
			/* Using two buffers, and it is not the first
			 * read/request, wait for the completion of the
			 * previous ahash_update() request.
			 */
			rc = ahash_wait(ahash_rc, &res);
			if (rc)
				goto out3;
		}

		sg_init_one(&sg[0], rbuf[active], rbuf_len);
		ahash_request_set_crypt(req, sg, NULL, rbuf_len);

		ahash_rc = crypto_ahash_update(req);

		if (rbuf[1])
			active = !active; /* swap buffers, if we use two */
	}
	/* wait for the last update request to complete */
	rc = ahash_wait(ahash_rc, &res);
out3:
	if (read)
		file->f_mode &= ~FMODE_READ;
	ima_free_pages(rbuf[0], rbuf_size[0]);
	ima_free_pages(rbuf[1], rbuf_size[1]);
out2:
	if (!rc) {
		ahash_request_set_crypt(req, NULL, hash->digest, 0);
		rc = ahash_wait(crypto_ahash_final(req), &res);
	}
out1:
	ahash_request_free(req);
	return rc;
}

static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
{
	struct crypto_ahash *tfm;
	int rc;

	tfm = ima_alloc_atfm(hash->algo);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	rc = ima_calc_file_hash_atfm(file, hash, tfm);

	ima_free_atfm(tfm);

	return rc;
}

static int ima_calc_file_hash_tfm(struct file *file,
				  struct ima_digest_data *hash,
				  struct crypto_shash *tfm)
{
	loff_t i_size, offset = 0;
	char *rbuf;
	int rc, read = 0;
	SHASH_DESC_ON_STACK(shash, tfm);

	shash->tfm = tfm;
	shash->flags = 0;

	hash->length = crypto_shash_digestsize(tfm);

	rc = crypto_shash_init(shash);
	if (rc != 0)
		return rc;

	i_size = i_size_read(file_inode(file));

	if (i_size == 0)
		goto out;

	rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
	if (!rbuf)
		return -ENOMEM;

	if (!(file->f_mode & FMODE_READ)) {
		file->f_mode |= FMODE_READ;
		read = 1;
	}

	while (offset < i_size) {
		int rbuf_len;

		rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
		if (rbuf_len < 0) {
			rc = rbuf_len;
			break;
		}
		if (rbuf_len == 0)
			break;
		offset += rbuf_len;

		rc = crypto_shash_update(shash, rbuf, rbuf_len);
		if (rc)
			break;
	}
	if (read)
		file->f_mode &= ~FMODE_READ;
	kfree(rbuf);
out:
	if (!rc)
		rc = crypto_shash_final(shash, hash->digest);
	return rc;
}

static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	rc = ima_calc_file_hash_tfm(file, hash, tfm);

	ima_free_tfm(tfm);

	return rc;
}

/*
 * ima_calc_file_hash - calculate file hash
 *
 * Asynchronous hash (ahash) allows using HW acceleration for calculating
 * a hash. ahash performance varies for different data sizes on different
 * crypto accelerators. shash performance might be better for smaller files.
 * The 'ima.ahash_minsize' module parameter allows specifying the best
 * minimum file size for using ahash on the system.
 *
 * If the ima.ahash_minsize parameter is not specified, this function uses
 * shash for the hash calculation.  If ahash fails, it falls back to using
 * shash.
 */
int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
{
	loff_t i_size;
	int rc;

	i_size = i_size_read(file_inode(file));

	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
		rc = ima_calc_file_ahash(file, hash);
		if (!rc)
			return 0;
	}

	return ima_calc_file_shash(file, hash);
}

/*
 * Calculate the hash of template data
 */
static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
					 struct ima_template_desc *td,
					 int num_fields,
					 struct ima_digest_data *hash,
					 struct crypto_shash *tfm)
{
	SHASH_DESC_ON_STACK(shash, tfm);
	int rc, i;

	shash->tfm = tfm;
	shash->flags = 0;

	hash->length = crypto_shash_digestsize(tfm);

	rc = crypto_shash_init(shash);
	if (rc != 0)
		return rc;

	for (i = 0; i < num_fields; i++) {
		u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
		u8 *data_to_hash = field_data[i].data;
		u32 datalen = field_data[i].len;

		if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
			rc = crypto_shash_update(shash,
						(const u8 *) &field_data[i].len,
						sizeof(field_data[i].len));
			if (rc)
				break;
		} else if (strcmp(td->fields[i]->field_id, "n") == 0) {
			memcpy(buffer, data_to_hash, datalen);
			data_to_hash = buffer;
			datalen = IMA_EVENT_NAME_LEN_MAX + 1;
		}
		rc = crypto_shash_update(shash, data_to_hash, datalen);
		if (rc)
			break;
	}

	if (!rc)
		rc = crypto_shash_final(shash, hash->digest);

	return rc;
}

int ima_calc_field_array_hash(struct ima_field_data *field_data,
			      struct ima_template_desc *desc, int num_fields,
			      struct ima_digest_data *hash)
{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
					   hash, tfm);

	ima_free_tfm(tfm);

	return rc;
}

static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
				  struct ima_digest_data *hash,
				  struct crypto_ahash *tfm)
{
	struct ahash_request *req;
	struct scatterlist sg;
	struct ahash_completion res;
	int rc, ahash_rc = 0;

	hash->length = crypto_ahash_digestsize(tfm);

	req = ahash_request_alloc(tfm, GFP_KERNEL);
	if (!req)
		return -ENOMEM;

	init_completion(&res.completion);
	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
				   CRYPTO_TFM_REQ_MAY_SLEEP,
				   ahash_complete, &res);

	rc = ahash_wait(crypto_ahash_init(req), &res);
	if (rc)
		goto out;

	sg_init_one(&sg, buf, len);
	ahash_request_set_crypt(req, &sg, NULL, len);

	ahash_rc = crypto_ahash_update(req);

	/* wait for the update request to complete */
	rc = ahash_wait(ahash_rc, &res);
	if (!rc) {
		ahash_request_set_crypt(req, NULL, hash->digest, 0);
		rc = ahash_wait(crypto_ahash_final(req), &res);
	}
out:
	ahash_request_free(req);
	return rc;
}

static int calc_buffer_ahash(const void *buf, loff_t len,
			     struct ima_digest_data *hash)
{
	struct crypto_ahash *tfm;
	int rc;

	tfm = ima_alloc_atfm(hash->algo);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);

	ima_free_atfm(tfm);

	return rc;
}

static int calc_buffer_shash_tfm(const void *buf, loff_t size,
				struct ima_digest_data *hash,
				struct crypto_shash *tfm)
{
	SHASH_DESC_ON_STACK(shash, tfm);
	unsigned int len;
	int rc;

	shash->tfm = tfm;
	shash->flags = 0;

	hash->length = crypto_shash_digestsize(tfm);

	rc = crypto_shash_init(shash);
	if (rc != 0)
		return rc;

	while (size) {
		len = size < PAGE_SIZE ? size : PAGE_SIZE;
		rc = crypto_shash_update(shash, buf, len);
		if (rc)
			break;
		buf += len;
		size -= len;
	}

	if (!rc)
		rc = crypto_shash_final(shash, hash->digest);
	return rc;
}

static int calc_buffer_shash(const void *buf, loff_t len,
			     struct ima_digest_data *hash)
{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	rc = calc_buffer_shash_tfm(buf, len, hash, tfm);

	ima_free_tfm(tfm);
	return rc;
}

int ima_calc_buffer_hash(const void *buf, loff_t len,
			 struct ima_digest_data *hash)
{
	int rc;

	if (ima_ahash_minsize && len >= ima_ahash_minsize) {
		rc = calc_buffer_ahash(buf, len, hash);
		if (!rc)
			return 0;
	}

	return calc_buffer_shash(buf, len, hash);
}

static void __init ima_pcrread(int idx, u8 *pcr)
{
	if (!ima_used_chip)
		return;

	if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
		pr_err("Error Communicating to TPM chip\n");
}

/*
 * Calculate the boot aggregate hash
 */
static int __init ima_calc_boot_aggregate_tfm(char *digest,
					      struct crypto_shash *tfm)
{
	u8 pcr_i[TPM_DIGEST_SIZE];
	int rc, i;
	SHASH_DESC_ON_STACK(shash, tfm);

	shash->tfm = tfm;
	shash->flags = 0;

	rc = crypto_shash_init(shash);
	if (rc != 0)
		return rc;

	/* cumulative sha1 over tpm registers 0-7 */
	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
		ima_pcrread(i, pcr_i);
		/* now accumulate with current aggregate */
		rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE);
	}
	if (!rc)
		crypto_shash_final(shash, digest);
	return rc;
}

int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
{
	struct crypto_shash *tfm;
	int rc;

	tfm = ima_alloc_tfm(hash->algo);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	hash->length = crypto_shash_digestsize(tfm);
	rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);

	ima_free_tfm(tfm);

	return rc;
}