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 #include <crypto/hash_info.h>
28 #include "ima.h"
29 
30 struct ahash_completion {
31 	struct completion completion;
32 	int err;
33 };
34 
35 /* minimum file size for ahash use */
36 static unsigned long ima_ahash_minsize;
37 module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
38 MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");
39 
40 /* default is 0 - 1 page. */
41 static int ima_maxorder;
42 static unsigned int ima_bufsize = PAGE_SIZE;
43 
44 static int param_set_bufsize(const char *val, const struct kernel_param *kp)
45 {
46 	unsigned long long size;
47 	int order;
48 
49 	size = memparse(val, NULL);
50 	order = get_order(size);
51 	if (order >= MAX_ORDER)
52 		return -EINVAL;
53 	ima_maxorder = order;
54 	ima_bufsize = PAGE_SIZE << order;
55 	return 0;
56 }
57 
58 static const struct kernel_param_ops param_ops_bufsize = {
59 	.set = param_set_bufsize,
60 	.get = param_get_uint,
61 };
62 #define param_check_bufsize(name, p) __param_check(name, p, unsigned int)
63 
64 module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
65 MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
66 
67 static struct crypto_shash *ima_shash_tfm;
68 static struct crypto_ahash *ima_ahash_tfm;
69 
70 int __init ima_init_crypto(void)
71 {
72 	long rc;
73 
74 	ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
75 	if (IS_ERR(ima_shash_tfm)) {
76 		rc = PTR_ERR(ima_shash_tfm);
77 		pr_err("Can not allocate %s (reason: %ld)\n",
78 		       hash_algo_name[ima_hash_algo], rc);
79 		return rc;
80 	}
81 	return 0;
82 }
83 
84 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
85 {
86 	struct crypto_shash *tfm = ima_shash_tfm;
87 	int rc;
88 
89 	if (algo < 0 || algo >= HASH_ALGO__LAST)
90 		algo = ima_hash_algo;
91 
92 	if (algo != ima_hash_algo) {
93 		tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
94 		if (IS_ERR(tfm)) {
95 			rc = PTR_ERR(tfm);
96 			pr_err("Can not allocate %s (reason: %d)\n",
97 			       hash_algo_name[algo], rc);
98 		}
99 	}
100 	return tfm;
101 }
102 
103 static void ima_free_tfm(struct crypto_shash *tfm)
104 {
105 	if (tfm != ima_shash_tfm)
106 		crypto_free_shash(tfm);
107 }
108 
109 /**
110  * ima_alloc_pages() - Allocate contiguous pages.
111  * @max_size:       Maximum amount of memory to allocate.
112  * @allocated_size: Returned size of actual allocation.
113  * @last_warn:      Should the min_size allocation warn or not.
114  *
115  * Tries to do opportunistic allocation for memory first trying to allocate
116  * max_size amount of memory and then splitting that until zero order is
117  * reached. Allocation is tried without generating allocation warnings unless
118  * last_warn is set. Last_warn set affects only last allocation of zero order.
119  *
120  * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
121  *
122  * Return pointer to allocated memory, or NULL on failure.
123  */
124 static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size,
125 			     int last_warn)
126 {
127 	void *ptr;
128 	int order = ima_maxorder;
129 	gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY;
130 
131 	if (order)
132 		order = min(get_order(max_size), order);
133 
134 	for (; order; order--) {
135 		ptr = (void *)__get_free_pages(gfp_mask, order);
136 		if (ptr) {
137 			*allocated_size = PAGE_SIZE << order;
138 			return ptr;
139 		}
140 	}
141 
142 	/* order is zero - one page */
143 
144 	gfp_mask = GFP_KERNEL;
145 
146 	if (!last_warn)
147 		gfp_mask |= __GFP_NOWARN;
148 
149 	ptr = (void *)__get_free_pages(gfp_mask, 0);
150 	if (ptr) {
151 		*allocated_size = PAGE_SIZE;
152 		return ptr;
153 	}
154 
155 	*allocated_size = 0;
156 	return NULL;
157 }
158 
159 /**
160  * ima_free_pages() - Free pages allocated by ima_alloc_pages().
161  * @ptr:  Pointer to allocated pages.
162  * @size: Size of allocated buffer.
163  */
164 static void ima_free_pages(void *ptr, size_t size)
165 {
166 	if (!ptr)
167 		return;
168 	free_pages((unsigned long)ptr, get_order(size));
169 }
170 
171 static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
172 {
173 	struct crypto_ahash *tfm = ima_ahash_tfm;
174 	int rc;
175 
176 	if (algo < 0 || algo >= HASH_ALGO__LAST)
177 		algo = ima_hash_algo;
178 
179 	if (algo != ima_hash_algo || !tfm) {
180 		tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
181 		if (!IS_ERR(tfm)) {
182 			if (algo == ima_hash_algo)
183 				ima_ahash_tfm = tfm;
184 		} else {
185 			rc = PTR_ERR(tfm);
186 			pr_err("Can not allocate %s (reason: %d)\n",
187 			       hash_algo_name[algo], rc);
188 		}
189 	}
190 	return tfm;
191 }
192 
193 static void ima_free_atfm(struct crypto_ahash *tfm)
194 {
195 	if (tfm != ima_ahash_tfm)
196 		crypto_free_ahash(tfm);
197 }
198 
199 static void ahash_complete(struct crypto_async_request *req, int err)
200 {
201 	struct ahash_completion *res = req->data;
202 
203 	if (err == -EINPROGRESS)
204 		return;
205 	res->err = err;
206 	complete(&res->completion);
207 }
208 
209 static int ahash_wait(int err, struct ahash_completion *res)
210 {
211 	switch (err) {
212 	case 0:
213 		break;
214 	case -EINPROGRESS:
215 	case -EBUSY:
216 		wait_for_completion(&res->completion);
217 		reinit_completion(&res->completion);
218 		err = res->err;
219 		/* fall through */
220 	default:
221 		pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);
222 	}
223 
224 	return err;
225 }
226 
227 static int ima_calc_file_hash_atfm(struct file *file,
228 				   struct ima_digest_data *hash,
229 				   struct crypto_ahash *tfm)
230 {
231 	loff_t i_size, offset;
232 	char *rbuf[2] = { NULL, };
233 	int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
234 	struct ahash_request *req;
235 	struct scatterlist sg[1];
236 	struct ahash_completion res;
237 	size_t rbuf_size[2];
238 
239 	hash->length = crypto_ahash_digestsize(tfm);
240 
241 	req = ahash_request_alloc(tfm, GFP_KERNEL);
242 	if (!req)
243 		return -ENOMEM;
244 
245 	init_completion(&res.completion);
246 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
247 				   CRYPTO_TFM_REQ_MAY_SLEEP,
248 				   ahash_complete, &res);
249 
250 	rc = ahash_wait(crypto_ahash_init(req), &res);
251 	if (rc)
252 		goto out1;
253 
254 	i_size = i_size_read(file_inode(file));
255 
256 	if (i_size == 0)
257 		goto out2;
258 
259 	/*
260 	 * Try to allocate maximum size of memory.
261 	 * Fail if even a single page cannot be allocated.
262 	 */
263 	rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
264 	if (!rbuf[0]) {
265 		rc = -ENOMEM;
266 		goto out1;
267 	}
268 
269 	/* Only allocate one buffer if that is enough. */
270 	if (i_size > rbuf_size[0]) {
271 		/*
272 		 * Try to allocate secondary buffer. If that fails fallback to
273 		 * using single buffering. Use previous memory allocation size
274 		 * as baseline for possible allocation size.
275 		 */
276 		rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
277 					  &rbuf_size[1], 0);
278 	}
279 
280 	if (!(file->f_mode & FMODE_READ)) {
281 		file->f_mode |= FMODE_READ;
282 		read = 1;
283 	}
284 
285 	for (offset = 0; offset < i_size; offset += rbuf_len) {
286 		if (!rbuf[1] && offset) {
287 			/* Not using two buffers, and it is not the first
288 			 * read/request, wait for the completion of the
289 			 * previous ahash_update() request.
290 			 */
291 			rc = ahash_wait(ahash_rc, &res);
292 			if (rc)
293 				goto out3;
294 		}
295 		/* read buffer */
296 		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
297 		rc = integrity_kernel_read(file, offset, rbuf[active],
298 					   rbuf_len);
299 		if (rc != rbuf_len)
300 			goto out3;
301 
302 		if (rbuf[1] && offset) {
303 			/* Using two buffers, and it is not the first
304 			 * read/request, wait for the completion of the
305 			 * previous ahash_update() request.
306 			 */
307 			rc = ahash_wait(ahash_rc, &res);
308 			if (rc)
309 				goto out3;
310 		}
311 
312 		sg_init_one(&sg[0], rbuf[active], rbuf_len);
313 		ahash_request_set_crypt(req, sg, NULL, rbuf_len);
314 
315 		ahash_rc = crypto_ahash_update(req);
316 
317 		if (rbuf[1])
318 			active = !active; /* swap buffers, if we use two */
319 	}
320 	/* wait for the last update request to complete */
321 	rc = ahash_wait(ahash_rc, &res);
322 out3:
323 	if (read)
324 		file->f_mode &= ~FMODE_READ;
325 	ima_free_pages(rbuf[0], rbuf_size[0]);
326 	ima_free_pages(rbuf[1], rbuf_size[1]);
327 out2:
328 	if (!rc) {
329 		ahash_request_set_crypt(req, NULL, hash->digest, 0);
330 		rc = ahash_wait(crypto_ahash_final(req), &res);
331 	}
332 out1:
333 	ahash_request_free(req);
334 	return rc;
335 }
336 
337 static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
338 {
339 	struct crypto_ahash *tfm;
340 	int rc;
341 
342 	tfm = ima_alloc_atfm(hash->algo);
343 	if (IS_ERR(tfm))
344 		return PTR_ERR(tfm);
345 
346 	rc = ima_calc_file_hash_atfm(file, hash, tfm);
347 
348 	ima_free_atfm(tfm);
349 
350 	return rc;
351 }
352 
353 static int ima_calc_file_hash_tfm(struct file *file,
354 				  struct ima_digest_data *hash,
355 				  struct crypto_shash *tfm)
356 {
357 	loff_t i_size, offset = 0;
358 	char *rbuf;
359 	int rc, read = 0;
360 	SHASH_DESC_ON_STACK(shash, tfm);
361 
362 	shash->tfm = tfm;
363 	shash->flags = 0;
364 
365 	hash->length = crypto_shash_digestsize(tfm);
366 
367 	rc = crypto_shash_init(shash);
368 	if (rc != 0)
369 		return rc;
370 
371 	i_size = i_size_read(file_inode(file));
372 
373 	if (i_size == 0)
374 		goto out;
375 
376 	rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
377 	if (!rbuf)
378 		return -ENOMEM;
379 
380 	if (!(file->f_mode & FMODE_READ)) {
381 		file->f_mode |= FMODE_READ;
382 		read = 1;
383 	}
384 
385 	while (offset < i_size) {
386 		int rbuf_len;
387 
388 		rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
389 		if (rbuf_len < 0) {
390 			rc = rbuf_len;
391 			break;
392 		}
393 		if (rbuf_len == 0)
394 			break;
395 		offset += rbuf_len;
396 
397 		rc = crypto_shash_update(shash, rbuf, rbuf_len);
398 		if (rc)
399 			break;
400 	}
401 	if (read)
402 		file->f_mode &= ~FMODE_READ;
403 	kfree(rbuf);
404 out:
405 	if (!rc)
406 		rc = crypto_shash_final(shash, hash->digest);
407 	return rc;
408 }
409 
410 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
411 {
412 	struct crypto_shash *tfm;
413 	int rc;
414 
415 	tfm = ima_alloc_tfm(hash->algo);
416 	if (IS_ERR(tfm))
417 		return PTR_ERR(tfm);
418 
419 	rc = ima_calc_file_hash_tfm(file, hash, tfm);
420 
421 	ima_free_tfm(tfm);
422 
423 	return rc;
424 }
425 
426 /*
427  * ima_calc_file_hash - calculate file hash
428  *
429  * Asynchronous hash (ahash) allows using HW acceleration for calculating
430  * a hash. ahash performance varies for different data sizes on different
431  * crypto accelerators. shash performance might be better for smaller files.
432  * The 'ima.ahash_minsize' module parameter allows specifying the best
433  * minimum file size for using ahash on the system.
434  *
435  * If the ima.ahash_minsize parameter is not specified, this function uses
436  * shash for the hash calculation.  If ahash fails, it falls back to using
437  * shash.
438  */
439 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
440 {
441 	loff_t i_size;
442 	int rc;
443 
444 	i_size = i_size_read(file_inode(file));
445 
446 	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
447 		rc = ima_calc_file_ahash(file, hash);
448 		if (!rc)
449 			return 0;
450 	}
451 
452 	return ima_calc_file_shash(file, hash);
453 }
454 
455 /*
456  * Calculate the hash of template data
457  */
458 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
459 					 struct ima_template_desc *td,
460 					 int num_fields,
461 					 struct ima_digest_data *hash,
462 					 struct crypto_shash *tfm)
463 {
464 	SHASH_DESC_ON_STACK(shash, tfm);
465 	int rc, i;
466 
467 	shash->tfm = tfm;
468 	shash->flags = 0;
469 
470 	hash->length = crypto_shash_digestsize(tfm);
471 
472 	rc = crypto_shash_init(shash);
473 	if (rc != 0)
474 		return rc;
475 
476 	for (i = 0; i < num_fields; i++) {
477 		u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
478 		u8 *data_to_hash = field_data[i].data;
479 		u32 datalen = field_data[i].len;
480 
481 		if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
482 			rc = crypto_shash_update(shash,
483 						(const u8 *) &field_data[i].len,
484 						sizeof(field_data[i].len));
485 			if (rc)
486 				break;
487 		} else if (strcmp(td->fields[i]->field_id, "n") == 0) {
488 			memcpy(buffer, data_to_hash, datalen);
489 			data_to_hash = buffer;
490 			datalen = IMA_EVENT_NAME_LEN_MAX + 1;
491 		}
492 		rc = crypto_shash_update(shash, data_to_hash, datalen);
493 		if (rc)
494 			break;
495 	}
496 
497 	if (!rc)
498 		rc = crypto_shash_final(shash, hash->digest);
499 
500 	return rc;
501 }
502 
503 int ima_calc_field_array_hash(struct ima_field_data *field_data,
504 			      struct ima_template_desc *desc, int num_fields,
505 			      struct ima_digest_data *hash)
506 {
507 	struct crypto_shash *tfm;
508 	int rc;
509 
510 	tfm = ima_alloc_tfm(hash->algo);
511 	if (IS_ERR(tfm))
512 		return PTR_ERR(tfm);
513 
514 	rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
515 					   hash, tfm);
516 
517 	ima_free_tfm(tfm);
518 
519 	return rc;
520 }
521 
522 static void __init ima_pcrread(int idx, u8 *pcr)
523 {
524 	if (!ima_used_chip)
525 		return;
526 
527 	if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
528 		pr_err("Error Communicating to TPM chip\n");
529 }
530 
531 /*
532  * Calculate the boot aggregate hash
533  */
534 static int __init ima_calc_boot_aggregate_tfm(char *digest,
535 					      struct crypto_shash *tfm)
536 {
537 	u8 pcr_i[TPM_DIGEST_SIZE];
538 	int rc, i;
539 	SHASH_DESC_ON_STACK(shash, tfm);
540 
541 	shash->tfm = tfm;
542 	shash->flags = 0;
543 
544 	rc = crypto_shash_init(shash);
545 	if (rc != 0)
546 		return rc;
547 
548 	/* cumulative sha1 over tpm registers 0-7 */
549 	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
550 		ima_pcrread(i, pcr_i);
551 		/* now accumulate with current aggregate */
552 		rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE);
553 	}
554 	if (!rc)
555 		crypto_shash_final(shash, digest);
556 	return rc;
557 }
558 
559 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
560 {
561 	struct crypto_shash *tfm;
562 	int rc;
563 
564 	tfm = ima_alloc_tfm(hash->algo);
565 	if (IS_ERR(tfm))
566 		return PTR_ERR(tfm);
567 
568 	hash->length = crypto_shash_digestsize(tfm);
569 	rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);
570 
571 	ima_free_tfm(tfm);
572 
573 	return rc;
574 }
575