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 
337 	hash->length = crypto_shash_digestsize(tfm);
338 
339 	rc = crypto_shash_init(shash);
340 	if (rc != 0)
341 		return rc;
342 
343 	i_size = i_size_read(file_inode(file));
344 
345 	if (i_size == 0)
346 		goto out;
347 
348 	rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
349 	if (!rbuf)
350 		return -ENOMEM;
351 
352 	while (offset < i_size) {
353 		int rbuf_len;
354 
355 		rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
356 		if (rbuf_len < 0) {
357 			rc = rbuf_len;
358 			break;
359 		}
360 		if (rbuf_len == 0)
361 			break;
362 		offset += rbuf_len;
363 
364 		rc = crypto_shash_update(shash, rbuf, rbuf_len);
365 		if (rc)
366 			break;
367 	}
368 	kfree(rbuf);
369 out:
370 	if (!rc)
371 		rc = crypto_shash_final(shash, hash->digest);
372 	return rc;
373 }
374 
375 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
376 {
377 	struct crypto_shash *tfm;
378 	int rc;
379 
380 	tfm = ima_alloc_tfm(hash->algo);
381 	if (IS_ERR(tfm))
382 		return PTR_ERR(tfm);
383 
384 	rc = ima_calc_file_hash_tfm(file, hash, tfm);
385 
386 	ima_free_tfm(tfm);
387 
388 	return rc;
389 }
390 
391 /*
392  * ima_calc_file_hash - calculate file hash
393  *
394  * Asynchronous hash (ahash) allows using HW acceleration for calculating
395  * a hash. ahash performance varies for different data sizes on different
396  * crypto accelerators. shash performance might be better for smaller files.
397  * The 'ima.ahash_minsize' module parameter allows specifying the best
398  * minimum file size for using ahash on the system.
399  *
400  * If the ima.ahash_minsize parameter is not specified, this function uses
401  * shash for the hash calculation.  If ahash fails, it falls back to using
402  * shash.
403  */
404 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
405 {
406 	loff_t i_size;
407 	int rc;
408 	struct file *f = file;
409 	bool new_file_instance = false, modified_flags = false;
410 
411 	/*
412 	 * For consistency, fail file's opened with the O_DIRECT flag on
413 	 * filesystems mounted with/without DAX option.
414 	 */
415 	if (file->f_flags & O_DIRECT) {
416 		hash->length = hash_digest_size[ima_hash_algo];
417 		hash->algo = ima_hash_algo;
418 		return -EINVAL;
419 	}
420 
421 	/* Open a new file instance in O_RDONLY if we cannot read */
422 	if (!(file->f_mode & FMODE_READ)) {
423 		int flags = file->f_flags & ~(O_WRONLY | O_APPEND |
424 				O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL);
425 		flags |= O_RDONLY;
426 		f = dentry_open(&file->f_path, flags, file->f_cred);
427 		if (IS_ERR(f)) {
428 			/*
429 			 * Cannot open the file again, lets modify f_flags
430 			 * of original and continue
431 			 */
432 			pr_info_ratelimited("Unable to reopen file for reading.\n");
433 			f = file;
434 			f->f_flags |= FMODE_READ;
435 			modified_flags = true;
436 		} else {
437 			new_file_instance = true;
438 		}
439 	}
440 
441 	i_size = i_size_read(file_inode(f));
442 
443 	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
444 		rc = ima_calc_file_ahash(f, hash);
445 		if (!rc)
446 			goto out;
447 	}
448 
449 	rc = ima_calc_file_shash(f, hash);
450 out:
451 	if (new_file_instance)
452 		fput(f);
453 	else if (modified_flags)
454 		f->f_flags &= ~FMODE_READ;
455 	return rc;
456 }
457 
458 /*
459  * Calculate the hash of template data
460  */
461 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
462 					 struct ima_template_desc *td,
463 					 int num_fields,
464 					 struct ima_digest_data *hash,
465 					 struct crypto_shash *tfm)
466 {
467 	SHASH_DESC_ON_STACK(shash, tfm);
468 	int rc, i;
469 
470 	shash->tfm = tfm;
471 
472 	hash->length = crypto_shash_digestsize(tfm);
473 
474 	rc = crypto_shash_init(shash);
475 	if (rc != 0)
476 		return rc;
477 
478 	for (i = 0; i < num_fields; i++) {
479 		u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
480 		u8 *data_to_hash = field_data[i].data;
481 		u32 datalen = field_data[i].len;
482 		u32 datalen_to_hash =
483 		    !ima_canonical_fmt ? datalen : cpu_to_le32(datalen);
484 
485 		if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
486 			rc = crypto_shash_update(shash,
487 						(const u8 *) &datalen_to_hash,
488 						sizeof(datalen_to_hash));
489 			if (rc)
490 				break;
491 		} else if (strcmp(td->fields[i]->field_id, "n") == 0) {
492 			memcpy(buffer, data_to_hash, datalen);
493 			data_to_hash = buffer;
494 			datalen = IMA_EVENT_NAME_LEN_MAX + 1;
495 		}
496 		rc = crypto_shash_update(shash, data_to_hash, datalen);
497 		if (rc)
498 			break;
499 	}
500 
501 	if (!rc)
502 		rc = crypto_shash_final(shash, hash->digest);
503 
504 	return rc;
505 }
506 
507 int ima_calc_field_array_hash(struct ima_field_data *field_data,
508 			      struct ima_template_desc *desc, int num_fields,
509 			      struct ima_digest_data *hash)
510 {
511 	struct crypto_shash *tfm;
512 	int rc;
513 
514 	tfm = ima_alloc_tfm(hash->algo);
515 	if (IS_ERR(tfm))
516 		return PTR_ERR(tfm);
517 
518 	rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
519 					   hash, tfm);
520 
521 	ima_free_tfm(tfm);
522 
523 	return rc;
524 }
525 
526 static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
527 				  struct ima_digest_data *hash,
528 				  struct crypto_ahash *tfm)
529 {
530 	struct ahash_request *req;
531 	struct scatterlist sg;
532 	struct crypto_wait wait;
533 	int rc, ahash_rc = 0;
534 
535 	hash->length = crypto_ahash_digestsize(tfm);
536 
537 	req = ahash_request_alloc(tfm, GFP_KERNEL);
538 	if (!req)
539 		return -ENOMEM;
540 
541 	crypto_init_wait(&wait);
542 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
543 				   CRYPTO_TFM_REQ_MAY_SLEEP,
544 				   crypto_req_done, &wait);
545 
546 	rc = ahash_wait(crypto_ahash_init(req), &wait);
547 	if (rc)
548 		goto out;
549 
550 	sg_init_one(&sg, buf, len);
551 	ahash_request_set_crypt(req, &sg, NULL, len);
552 
553 	ahash_rc = crypto_ahash_update(req);
554 
555 	/* wait for the update request to complete */
556 	rc = ahash_wait(ahash_rc, &wait);
557 	if (!rc) {
558 		ahash_request_set_crypt(req, NULL, hash->digest, 0);
559 		rc = ahash_wait(crypto_ahash_final(req), &wait);
560 	}
561 out:
562 	ahash_request_free(req);
563 	return rc;
564 }
565 
566 static int calc_buffer_ahash(const void *buf, loff_t len,
567 			     struct ima_digest_data *hash)
568 {
569 	struct crypto_ahash *tfm;
570 	int rc;
571 
572 	tfm = ima_alloc_atfm(hash->algo);
573 	if (IS_ERR(tfm))
574 		return PTR_ERR(tfm);
575 
576 	rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);
577 
578 	ima_free_atfm(tfm);
579 
580 	return rc;
581 }
582 
583 static int calc_buffer_shash_tfm(const void *buf, loff_t size,
584 				struct ima_digest_data *hash,
585 				struct crypto_shash *tfm)
586 {
587 	SHASH_DESC_ON_STACK(shash, tfm);
588 	unsigned int len;
589 	int rc;
590 
591 	shash->tfm = tfm;
592 
593 	hash->length = crypto_shash_digestsize(tfm);
594 
595 	rc = crypto_shash_init(shash);
596 	if (rc != 0)
597 		return rc;
598 
599 	while (size) {
600 		len = size < PAGE_SIZE ? size : PAGE_SIZE;
601 		rc = crypto_shash_update(shash, buf, len);
602 		if (rc)
603 			break;
604 		buf += len;
605 		size -= len;
606 	}
607 
608 	if (!rc)
609 		rc = crypto_shash_final(shash, hash->digest);
610 	return rc;
611 }
612 
613 static int calc_buffer_shash(const void *buf, loff_t len,
614 			     struct ima_digest_data *hash)
615 {
616 	struct crypto_shash *tfm;
617 	int rc;
618 
619 	tfm = ima_alloc_tfm(hash->algo);
620 	if (IS_ERR(tfm))
621 		return PTR_ERR(tfm);
622 
623 	rc = calc_buffer_shash_tfm(buf, len, hash, tfm);
624 
625 	ima_free_tfm(tfm);
626 	return rc;
627 }
628 
629 int ima_calc_buffer_hash(const void *buf, loff_t len,
630 			 struct ima_digest_data *hash)
631 {
632 	int rc;
633 
634 	if (ima_ahash_minsize && len >= ima_ahash_minsize) {
635 		rc = calc_buffer_ahash(buf, len, hash);
636 		if (!rc)
637 			return 0;
638 	}
639 
640 	return calc_buffer_shash(buf, len, hash);
641 }
642 
643 static void __init ima_pcrread(u32 idx, struct tpm_digest *d)
644 {
645 	if (!ima_tpm_chip)
646 		return;
647 
648 	if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0)
649 		pr_err("Error Communicating to TPM chip\n");
650 }
651 
652 /*
653  * Calculate the boot aggregate hash
654  */
655 static int __init ima_calc_boot_aggregate_tfm(char *digest,
656 					      struct crypto_shash *tfm)
657 {
658 	struct tpm_digest d = { .alg_id = TPM_ALG_SHA1, .digest = {0} };
659 	int rc;
660 	u32 i;
661 	SHASH_DESC_ON_STACK(shash, tfm);
662 
663 	shash->tfm = tfm;
664 
665 	rc = crypto_shash_init(shash);
666 	if (rc != 0)
667 		return rc;
668 
669 	/* cumulative sha1 over tpm registers 0-7 */
670 	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
671 		ima_pcrread(i, &d);
672 		/* now accumulate with current aggregate */
673 		rc = crypto_shash_update(shash, d.digest, TPM_DIGEST_SIZE);
674 	}
675 	if (!rc)
676 		crypto_shash_final(shash, digest);
677 	return rc;
678 }
679 
680 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
681 {
682 	struct crypto_shash *tfm;
683 	int rc;
684 
685 	tfm = ima_alloc_tfm(hash->algo);
686 	if (IS_ERR(tfm))
687 		return PTR_ERR(tfm);
688 
689 	hash->length = crypto_shash_digestsize(tfm);
690 	rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);
691 
692 	ima_free_tfm(tfm);
693 
694 	return rc;
695 }
696