1 /*
2  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
3  *
4  * Authors:
5  * Mimi Zohar <zohar@us.ibm.com>
6  * Kylene Hall <kjhall@us.ibm.com>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation, version 2 of the License.
11  *
12  * File: ima_crypto.c
13  *	Calculates md5/sha1 file hash, template hash, boot-aggreate hash
14  */
15 
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17 
18 #include <linux/kernel.h>
19 #include <linux/moduleparam.h>
20 #include <linux/ratelimit.h>
21 #include <linux/file.h>
22 #include <linux/crypto.h>
23 #include <linux/scatterlist.h>
24 #include <linux/err.h>
25 #include <linux/slab.h>
26 #include <crypto/hash.h>
27 
28 #include "ima.h"
29 
30 /* minimum file size for ahash use */
31 static unsigned long ima_ahash_minsize;
32 module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
33 MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");
34 
35 /* default is 0 - 1 page. */
36 static int ima_maxorder;
37 static unsigned int ima_bufsize = PAGE_SIZE;
38 
39 static int param_set_bufsize(const char *val, const struct kernel_param *kp)
40 {
41 	unsigned long long size;
42 	int order;
43 
44 	size = memparse(val, NULL);
45 	order = get_order(size);
46 	if (order >= MAX_ORDER)
47 		return -EINVAL;
48 	ima_maxorder = order;
49 	ima_bufsize = PAGE_SIZE << order;
50 	return 0;
51 }
52 
53 static const struct kernel_param_ops param_ops_bufsize = {
54 	.set = param_set_bufsize,
55 	.get = param_get_uint,
56 };
57 #define param_check_bufsize(name, p) __param_check(name, p, unsigned int)
58 
59 module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
60 MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
61 
62 static struct crypto_shash *ima_shash_tfm;
63 static struct crypto_ahash *ima_ahash_tfm;
64 
65 int __init ima_init_crypto(void)
66 {
67 	long rc;
68 
69 	ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
70 	if (IS_ERR(ima_shash_tfm)) {
71 		rc = PTR_ERR(ima_shash_tfm);
72 		pr_err("Can not allocate %s (reason: %ld)\n",
73 		       hash_algo_name[ima_hash_algo], rc);
74 		return rc;
75 	}
76 	pr_info("Allocated hash algorithm: %s\n",
77 		hash_algo_name[ima_hash_algo]);
78 	return 0;
79 }
80 
81 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
82 {
83 	struct crypto_shash *tfm = ima_shash_tfm;
84 	int rc;
85 
86 	if (algo < 0 || algo >= HASH_ALGO__LAST)
87 		algo = ima_hash_algo;
88 
89 	if (algo != ima_hash_algo) {
90 		tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
91 		if (IS_ERR(tfm)) {
92 			rc = PTR_ERR(tfm);
93 			pr_err("Can not allocate %s (reason: %d)\n",
94 			       hash_algo_name[algo], rc);
95 		}
96 	}
97 	return tfm;
98 }
99 
100 static void ima_free_tfm(struct crypto_shash *tfm)
101 {
102 	if (tfm != ima_shash_tfm)
103 		crypto_free_shash(tfm);
104 }
105 
106 /**
107  * ima_alloc_pages() - Allocate contiguous pages.
108  * @max_size:       Maximum amount of memory to allocate.
109  * @allocated_size: Returned size of actual allocation.
110  * @last_warn:      Should the min_size allocation warn or not.
111  *
112  * Tries to do opportunistic allocation for memory first trying to allocate
113  * max_size amount of memory and then splitting that until zero order is
114  * reached. Allocation is tried without generating allocation warnings unless
115  * last_warn is set. Last_warn set affects only last allocation of zero order.
116  *
117  * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
118  *
119  * Return pointer to allocated memory, or NULL on failure.
120  */
121 static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size,
122 			     int last_warn)
123 {
124 	void *ptr;
125 	int order = ima_maxorder;
126 	gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY;
127 
128 	if (order)
129 		order = min(get_order(max_size), order);
130 
131 	for (; order; order--) {
132 		ptr = (void *)__get_free_pages(gfp_mask, order);
133 		if (ptr) {
134 			*allocated_size = PAGE_SIZE << order;
135 			return ptr;
136 		}
137 	}
138 
139 	/* order is zero - one page */
140 
141 	gfp_mask = GFP_KERNEL;
142 
143 	if (!last_warn)
144 		gfp_mask |= __GFP_NOWARN;
145 
146 	ptr = (void *)__get_free_pages(gfp_mask, 0);
147 	if (ptr) {
148 		*allocated_size = PAGE_SIZE;
149 		return ptr;
150 	}
151 
152 	*allocated_size = 0;
153 	return NULL;
154 }
155 
156 /**
157  * ima_free_pages() - Free pages allocated by ima_alloc_pages().
158  * @ptr:  Pointer to allocated pages.
159  * @size: Size of allocated buffer.
160  */
161 static void ima_free_pages(void *ptr, size_t size)
162 {
163 	if (!ptr)
164 		return;
165 	free_pages((unsigned long)ptr, get_order(size));
166 }
167 
168 static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
169 {
170 	struct crypto_ahash *tfm = ima_ahash_tfm;
171 	int rc;
172 
173 	if (algo < 0 || algo >= HASH_ALGO__LAST)
174 		algo = ima_hash_algo;
175 
176 	if (algo != ima_hash_algo || !tfm) {
177 		tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
178 		if (!IS_ERR(tfm)) {
179 			if (algo == ima_hash_algo)
180 				ima_ahash_tfm = tfm;
181 		} else {
182 			rc = PTR_ERR(tfm);
183 			pr_err("Can not allocate %s (reason: %d)\n",
184 			       hash_algo_name[algo], rc);
185 		}
186 	}
187 	return tfm;
188 }
189 
190 static void ima_free_atfm(struct crypto_ahash *tfm)
191 {
192 	if (tfm != ima_ahash_tfm)
193 		crypto_free_ahash(tfm);
194 }
195 
196 static inline int ahash_wait(int err, struct crypto_wait *wait)
197 {
198 
199 	err = crypto_wait_req(err, wait);
200 
201 	if (err)
202 		pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);
203 
204 	return err;
205 }
206 
207 static int ima_calc_file_hash_atfm(struct file *file,
208 				   struct ima_digest_data *hash,
209 				   struct crypto_ahash *tfm)
210 {
211 	loff_t i_size, offset;
212 	char *rbuf[2] = { NULL, };
213 	int rc, rbuf_len, active = 0, ahash_rc = 0;
214 	struct ahash_request *req;
215 	struct scatterlist sg[1];
216 	struct crypto_wait wait;
217 	size_t rbuf_size[2];
218 
219 	hash->length = crypto_ahash_digestsize(tfm);
220 
221 	req = ahash_request_alloc(tfm, GFP_KERNEL);
222 	if (!req)
223 		return -ENOMEM;
224 
225 	crypto_init_wait(&wait);
226 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
227 				   CRYPTO_TFM_REQ_MAY_SLEEP,
228 				   crypto_req_done, &wait);
229 
230 	rc = ahash_wait(crypto_ahash_init(req), &wait);
231 	if (rc)
232 		goto out1;
233 
234 	i_size = i_size_read(file_inode(file));
235 
236 	if (i_size == 0)
237 		goto out2;
238 
239 	/*
240 	 * Try to allocate maximum size of memory.
241 	 * Fail if even a single page cannot be allocated.
242 	 */
243 	rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
244 	if (!rbuf[0]) {
245 		rc = -ENOMEM;
246 		goto out1;
247 	}
248 
249 	/* Only allocate one buffer if that is enough. */
250 	if (i_size > rbuf_size[0]) {
251 		/*
252 		 * Try to allocate secondary buffer. If that fails fallback to
253 		 * using single buffering. Use previous memory allocation size
254 		 * as baseline for possible allocation size.
255 		 */
256 		rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
257 					  &rbuf_size[1], 0);
258 	}
259 
260 	for (offset = 0; offset < i_size; offset += rbuf_len) {
261 		if (!rbuf[1] && offset) {
262 			/* Not using two buffers, and it is not the first
263 			 * read/request, wait for the completion of the
264 			 * previous ahash_update() request.
265 			 */
266 			rc = ahash_wait(ahash_rc, &wait);
267 			if (rc)
268 				goto out3;
269 		}
270 		/* read buffer */
271 		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
272 		rc = integrity_kernel_read(file, offset, rbuf[active],
273 					   rbuf_len);
274 		if (rc != rbuf_len)
275 			goto out3;
276 
277 		if (rbuf[1] && offset) {
278 			/* Using two buffers, and it is not the first
279 			 * read/request, wait for the completion of the
280 			 * previous ahash_update() request.
281 			 */
282 			rc = ahash_wait(ahash_rc, &wait);
283 			if (rc)
284 				goto out3;
285 		}
286 
287 		sg_init_one(&sg[0], rbuf[active], rbuf_len);
288 		ahash_request_set_crypt(req, sg, NULL, rbuf_len);
289 
290 		ahash_rc = crypto_ahash_update(req);
291 
292 		if (rbuf[1])
293 			active = !active; /* swap buffers, if we use two */
294 	}
295 	/* wait for the last update request to complete */
296 	rc = ahash_wait(ahash_rc, &wait);
297 out3:
298 	ima_free_pages(rbuf[0], rbuf_size[0]);
299 	ima_free_pages(rbuf[1], rbuf_size[1]);
300 out2:
301 	if (!rc) {
302 		ahash_request_set_crypt(req, NULL, hash->digest, 0);
303 		rc = ahash_wait(crypto_ahash_final(req), &wait);
304 	}
305 out1:
306 	ahash_request_free(req);
307 	return rc;
308 }
309 
310 static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
311 {
312 	struct crypto_ahash *tfm;
313 	int rc;
314 
315 	tfm = ima_alloc_atfm(hash->algo);
316 	if (IS_ERR(tfm))
317 		return PTR_ERR(tfm);
318 
319 	rc = ima_calc_file_hash_atfm(file, hash, tfm);
320 
321 	ima_free_atfm(tfm);
322 
323 	return rc;
324 }
325 
326 static int ima_calc_file_hash_tfm(struct file *file,
327 				  struct ima_digest_data *hash,
328 				  struct crypto_shash *tfm)
329 {
330 	loff_t i_size, offset = 0;
331 	char *rbuf;
332 	int rc;
333 	SHASH_DESC_ON_STACK(shash, tfm);
334 
335 	shash->tfm = tfm;
336 	shash->flags = 0;
337 
338 	hash->length = crypto_shash_digestsize(tfm);
339 
340 	rc = crypto_shash_init(shash);
341 	if (rc != 0)
342 		return rc;
343 
344 	i_size = i_size_read(file_inode(file));
345 
346 	if (i_size == 0)
347 		goto out;
348 
349 	rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
350 	if (!rbuf)
351 		return -ENOMEM;
352 
353 	while (offset < i_size) {
354 		int rbuf_len;
355 
356 		rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
357 		if (rbuf_len < 0) {
358 			rc = rbuf_len;
359 			break;
360 		}
361 		if (rbuf_len == 0)
362 			break;
363 		offset += rbuf_len;
364 
365 		rc = crypto_shash_update(shash, rbuf, rbuf_len);
366 		if (rc)
367 			break;
368 	}
369 	kfree(rbuf);
370 out:
371 	if (!rc)
372 		rc = crypto_shash_final(shash, hash->digest);
373 	return rc;
374 }
375 
376 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
377 {
378 	struct crypto_shash *tfm;
379 	int rc;
380 
381 	tfm = ima_alloc_tfm(hash->algo);
382 	if (IS_ERR(tfm))
383 		return PTR_ERR(tfm);
384 
385 	rc = ima_calc_file_hash_tfm(file, hash, tfm);
386 
387 	ima_free_tfm(tfm);
388 
389 	return rc;
390 }
391 
392 /*
393  * ima_calc_file_hash - calculate file hash
394  *
395  * Asynchronous hash (ahash) allows using HW acceleration for calculating
396  * a hash. ahash performance varies for different data sizes on different
397  * crypto accelerators. shash performance might be better for smaller files.
398  * The 'ima.ahash_minsize' module parameter allows specifying the best
399  * minimum file size for using ahash on the system.
400  *
401  * If the ima.ahash_minsize parameter is not specified, this function uses
402  * shash for the hash calculation.  If ahash fails, it falls back to using
403  * shash.
404  */
405 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
406 {
407 	loff_t i_size;
408 	int rc;
409 	struct file *f = file;
410 	bool new_file_instance = false, modified_flags = false;
411 
412 	/*
413 	 * For consistency, fail file's opened with the O_DIRECT flag on
414 	 * filesystems mounted with/without DAX option.
415 	 */
416 	if (file->f_flags & O_DIRECT) {
417 		hash->length = hash_digest_size[ima_hash_algo];
418 		hash->algo = ima_hash_algo;
419 		return -EINVAL;
420 	}
421 
422 	/* Open a new file instance in O_RDONLY if we cannot read */
423 	if (!(file->f_mode & FMODE_READ)) {
424 		int flags = file->f_flags & ~(O_WRONLY | O_APPEND |
425 				O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL);
426 		flags |= O_RDONLY;
427 		f = dentry_open(&file->f_path, flags, file->f_cred);
428 		if (IS_ERR(f)) {
429 			/*
430 			 * Cannot open the file again, lets modify f_flags
431 			 * of original and continue
432 			 */
433 			pr_info_ratelimited("Unable to reopen file for reading.\n");
434 			f = file;
435 			f->f_flags |= FMODE_READ;
436 			modified_flags = true;
437 		} else {
438 			new_file_instance = true;
439 		}
440 	}
441 
442 	i_size = i_size_read(file_inode(f));
443 
444 	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
445 		rc = ima_calc_file_ahash(f, hash);
446 		if (!rc)
447 			goto out;
448 	}
449 
450 	rc = ima_calc_file_shash(f, hash);
451 out:
452 	if (new_file_instance)
453 		fput(f);
454 	else if (modified_flags)
455 		f->f_flags &= ~FMODE_READ;
456 	return rc;
457 }
458 
459 /*
460  * Calculate the hash of template data
461  */
462 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
463 					 struct ima_template_desc *td,
464 					 int num_fields,
465 					 struct ima_digest_data *hash,
466 					 struct crypto_shash *tfm)
467 {
468 	SHASH_DESC_ON_STACK(shash, tfm);
469 	int rc, i;
470 
471 	shash->tfm = tfm;
472 	shash->flags = 0;
473 
474 	hash->length = crypto_shash_digestsize(tfm);
475 
476 	rc = crypto_shash_init(shash);
477 	if (rc != 0)
478 		return rc;
479 
480 	for (i = 0; i < num_fields; i++) {
481 		u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
482 		u8 *data_to_hash = field_data[i].data;
483 		u32 datalen = field_data[i].len;
484 		u32 datalen_to_hash =
485 		    !ima_canonical_fmt ? datalen : cpu_to_le32(datalen);
486 
487 		if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
488 			rc = crypto_shash_update(shash,
489 						(const u8 *) &datalen_to_hash,
490 						sizeof(datalen_to_hash));
491 			if (rc)
492 				break;
493 		} else if (strcmp(td->fields[i]->field_id, "n") == 0) {
494 			memcpy(buffer, data_to_hash, datalen);
495 			data_to_hash = buffer;
496 			datalen = IMA_EVENT_NAME_LEN_MAX + 1;
497 		}
498 		rc = crypto_shash_update(shash, data_to_hash, datalen);
499 		if (rc)
500 			break;
501 	}
502 
503 	if (!rc)
504 		rc = crypto_shash_final(shash, hash->digest);
505 
506 	return rc;
507 }
508 
509 int ima_calc_field_array_hash(struct ima_field_data *field_data,
510 			      struct ima_template_desc *desc, int num_fields,
511 			      struct ima_digest_data *hash)
512 {
513 	struct crypto_shash *tfm;
514 	int rc;
515 
516 	tfm = ima_alloc_tfm(hash->algo);
517 	if (IS_ERR(tfm))
518 		return PTR_ERR(tfm);
519 
520 	rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
521 					   hash, tfm);
522 
523 	ima_free_tfm(tfm);
524 
525 	return rc;
526 }
527 
528 static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
529 				  struct ima_digest_data *hash,
530 				  struct crypto_ahash *tfm)
531 {
532 	struct ahash_request *req;
533 	struct scatterlist sg;
534 	struct crypto_wait wait;
535 	int rc, ahash_rc = 0;
536 
537 	hash->length = crypto_ahash_digestsize(tfm);
538 
539 	req = ahash_request_alloc(tfm, GFP_KERNEL);
540 	if (!req)
541 		return -ENOMEM;
542 
543 	crypto_init_wait(&wait);
544 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
545 				   CRYPTO_TFM_REQ_MAY_SLEEP,
546 				   crypto_req_done, &wait);
547 
548 	rc = ahash_wait(crypto_ahash_init(req), &wait);
549 	if (rc)
550 		goto out;
551 
552 	sg_init_one(&sg, buf, len);
553 	ahash_request_set_crypt(req, &sg, NULL, len);
554 
555 	ahash_rc = crypto_ahash_update(req);
556 
557 	/* wait for the update request to complete */
558 	rc = ahash_wait(ahash_rc, &wait);
559 	if (!rc) {
560 		ahash_request_set_crypt(req, NULL, hash->digest, 0);
561 		rc = ahash_wait(crypto_ahash_final(req), &wait);
562 	}
563 out:
564 	ahash_request_free(req);
565 	return rc;
566 }
567 
568 static int calc_buffer_ahash(const void *buf, loff_t len,
569 			     struct ima_digest_data *hash)
570 {
571 	struct crypto_ahash *tfm;
572 	int rc;
573 
574 	tfm = ima_alloc_atfm(hash->algo);
575 	if (IS_ERR(tfm))
576 		return PTR_ERR(tfm);
577 
578 	rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);
579 
580 	ima_free_atfm(tfm);
581 
582 	return rc;
583 }
584 
585 static int calc_buffer_shash_tfm(const void *buf, loff_t size,
586 				struct ima_digest_data *hash,
587 				struct crypto_shash *tfm)
588 {
589 	SHASH_DESC_ON_STACK(shash, tfm);
590 	unsigned int len;
591 	int rc;
592 
593 	shash->tfm = tfm;
594 	shash->flags = 0;
595 
596 	hash->length = crypto_shash_digestsize(tfm);
597 
598 	rc = crypto_shash_init(shash);
599 	if (rc != 0)
600 		return rc;
601 
602 	while (size) {
603 		len = size < PAGE_SIZE ? size : PAGE_SIZE;
604 		rc = crypto_shash_update(shash, buf, len);
605 		if (rc)
606 			break;
607 		buf += len;
608 		size -= len;
609 	}
610 
611 	if (!rc)
612 		rc = crypto_shash_final(shash, hash->digest);
613 	return rc;
614 }
615 
616 static int calc_buffer_shash(const void *buf, loff_t len,
617 			     struct ima_digest_data *hash)
618 {
619 	struct crypto_shash *tfm;
620 	int rc;
621 
622 	tfm = ima_alloc_tfm(hash->algo);
623 	if (IS_ERR(tfm))
624 		return PTR_ERR(tfm);
625 
626 	rc = calc_buffer_shash_tfm(buf, len, hash, tfm);
627 
628 	ima_free_tfm(tfm);
629 	return rc;
630 }
631 
632 int ima_calc_buffer_hash(const void *buf, loff_t len,
633 			 struct ima_digest_data *hash)
634 {
635 	int rc;
636 
637 	if (ima_ahash_minsize && len >= ima_ahash_minsize) {
638 		rc = calc_buffer_ahash(buf, len, hash);
639 		if (!rc)
640 			return 0;
641 	}
642 
643 	return calc_buffer_shash(buf, len, hash);
644 }
645 
646 static void __init ima_pcrread(u32 idx, struct tpm_digest *d)
647 {
648 	if (!ima_tpm_chip)
649 		return;
650 
651 	if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0)
652 		pr_err("Error Communicating to TPM chip\n");
653 }
654 
655 /*
656  * Calculate the boot aggregate hash
657  */
658 static int __init ima_calc_boot_aggregate_tfm(char *digest,
659 					      struct crypto_shash *tfm)
660 {
661 	struct tpm_digest d = { .alg_id = TPM_ALG_SHA1, .digest = {0} };
662 	int rc;
663 	u32 i;
664 	SHASH_DESC_ON_STACK(shash, tfm);
665 
666 	shash->tfm = tfm;
667 	shash->flags = 0;
668 
669 	rc = crypto_shash_init(shash);
670 	if (rc != 0)
671 		return rc;
672 
673 	/* cumulative sha1 over tpm registers 0-7 */
674 	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
675 		ima_pcrread(i, &d);
676 		/* now accumulate with current aggregate */
677 		rc = crypto_shash_update(shash, d.digest, TPM_DIGEST_SIZE);
678 	}
679 	if (!rc)
680 		crypto_shash_final(shash, digest);
681 	return rc;
682 }
683 
684 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
685 {
686 	struct crypto_shash *tfm;
687 	int rc;
688 
689 	tfm = ima_alloc_tfm(hash->algo);
690 	if (IS_ERR(tfm))
691 		return PTR_ERR(tfm);
692 
693 	hash->length = crypto_shash_digestsize(tfm);
694 	rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);
695 
696 	ima_free_tfm(tfm);
697 
698 	return rc;
699 }
700