1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2012 Red Hat, Inc.
4  *
5  * Author: Mikulas Patocka <mpatocka@redhat.com>
6  *
7  * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
8  *
9  * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
10  * default prefetch value. Data are read in "prefetch_cluster" chunks from the
11  * hash device. Setting this greatly improves performance when data and hash
12  * are on the same disk on different partitions on devices with poor random
13  * access behavior.
14  */
15 
16 #include "dm-verity.h"
17 #include "dm-verity-fec.h"
18 #include "dm-verity-verify-sig.h"
19 #include <linux/module.h>
20 #include <linux/reboot.h>
21 #include <linux/scatterlist.h>
22 #include <linux/string.h>
23 #include <linux/jump_label.h>
24 
25 #define DM_MSG_PREFIX			"verity"
26 
27 #define DM_VERITY_ENV_LENGTH		42
28 #define DM_VERITY_ENV_VAR_NAME		"DM_VERITY_ERR_BLOCK_NR"
29 
30 #define DM_VERITY_DEFAULT_PREFETCH_SIZE	262144
31 
32 #define DM_VERITY_MAX_CORRUPTED_ERRS	100
33 
34 #define DM_VERITY_OPT_LOGGING		"ignore_corruption"
35 #define DM_VERITY_OPT_RESTART		"restart_on_corruption"
36 #define DM_VERITY_OPT_PANIC		"panic_on_corruption"
37 #define DM_VERITY_OPT_IGN_ZEROES	"ignore_zero_blocks"
38 #define DM_VERITY_OPT_AT_MOST_ONCE	"check_at_most_once"
39 #define DM_VERITY_OPT_TASKLET_VERIFY	"try_verify_in_tasklet"
40 
41 #define DM_VERITY_OPTS_MAX		(4 + DM_VERITY_OPTS_FEC + \
42 					 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
43 
44 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
45 
46 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
47 
48 static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
49 
50 struct dm_verity_prefetch_work {
51 	struct work_struct work;
52 	struct dm_verity *v;
53 	sector_t block;
54 	unsigned n_blocks;
55 };
56 
57 /*
58  * Auxiliary structure appended to each dm-bufio buffer. If the value
59  * hash_verified is nonzero, hash of the block has been verified.
60  *
61  * The variable hash_verified is set to 0 when allocating the buffer, then
62  * it can be changed to 1 and it is never reset to 0 again.
63  *
64  * There is no lock around this value, a race condition can at worst cause
65  * that multiple processes verify the hash of the same buffer simultaneously
66  * and write 1 to hash_verified simultaneously.
67  * This condition is harmless, so we don't need locking.
68  */
69 struct buffer_aux {
70 	int hash_verified;
71 };
72 
73 /*
74  * Initialize struct buffer_aux for a freshly created buffer.
75  */
dm_bufio_alloc_callback(struct dm_buffer * buf)76 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
77 {
78 	struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
79 
80 	aux->hash_verified = 0;
81 }
82 
83 /*
84  * Translate input sector number to the sector number on the target device.
85  */
verity_map_sector(struct dm_verity * v,sector_t bi_sector)86 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
87 {
88 	return v->data_start + dm_target_offset(v->ti, bi_sector);
89 }
90 
91 /*
92  * Return hash position of a specified block at a specified tree level
93  * (0 is the lowest level).
94  * The lowest "hash_per_block_bits"-bits of the result denote hash position
95  * inside a hash block. The remaining bits denote location of the hash block.
96  */
verity_position_at_level(struct dm_verity * v,sector_t block,int level)97 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
98 					 int level)
99 {
100 	return block >> (level * v->hash_per_block_bits);
101 }
102 
verity_hash_update(struct dm_verity * v,struct ahash_request * req,const u8 * data,size_t len,struct crypto_wait * wait)103 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
104 				const u8 *data, size_t len,
105 				struct crypto_wait *wait)
106 {
107 	struct scatterlist sg;
108 
109 	if (likely(!is_vmalloc_addr(data))) {
110 		sg_init_one(&sg, data, len);
111 		ahash_request_set_crypt(req, &sg, NULL, len);
112 		return crypto_wait_req(crypto_ahash_update(req), wait);
113 	} else {
114 		do {
115 			int r;
116 			size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
117 			flush_kernel_vmap_range((void *)data, this_step);
118 			sg_init_table(&sg, 1);
119 			sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
120 			ahash_request_set_crypt(req, &sg, NULL, this_step);
121 			r = crypto_wait_req(crypto_ahash_update(req), wait);
122 			if (unlikely(r))
123 				return r;
124 			data += this_step;
125 			len -= this_step;
126 		} while (len);
127 		return 0;
128 	}
129 }
130 
131 /*
132  * Wrapper for crypto_ahash_init, which handles verity salting.
133  */
verity_hash_init(struct dm_verity * v,struct ahash_request * req,struct crypto_wait * wait)134 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
135 				struct crypto_wait *wait)
136 {
137 	int r;
138 
139 	ahash_request_set_tfm(req, v->tfm);
140 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
141 					CRYPTO_TFM_REQ_MAY_BACKLOG,
142 					crypto_req_done, (void *)wait);
143 	crypto_init_wait(wait);
144 
145 	r = crypto_wait_req(crypto_ahash_init(req), wait);
146 
147 	if (unlikely(r < 0)) {
148 		DMERR("crypto_ahash_init failed: %d", r);
149 		return r;
150 	}
151 
152 	if (likely(v->salt_size && (v->version >= 1)))
153 		r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
154 
155 	return r;
156 }
157 
verity_hash_final(struct dm_verity * v,struct ahash_request * req,u8 * digest,struct crypto_wait * wait)158 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
159 			     u8 *digest, struct crypto_wait *wait)
160 {
161 	int r;
162 
163 	if (unlikely(v->salt_size && (!v->version))) {
164 		r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
165 
166 		if (r < 0) {
167 			DMERR("verity_hash_final failed updating salt: %d", r);
168 			goto out;
169 		}
170 	}
171 
172 	ahash_request_set_crypt(req, NULL, digest, 0);
173 	r = crypto_wait_req(crypto_ahash_final(req), wait);
174 out:
175 	return r;
176 }
177 
verity_hash(struct dm_verity * v,struct ahash_request * req,const u8 * data,size_t len,u8 * digest)178 int verity_hash(struct dm_verity *v, struct ahash_request *req,
179 		const u8 *data, size_t len, u8 *digest)
180 {
181 	int r;
182 	struct crypto_wait wait;
183 
184 	r = verity_hash_init(v, req, &wait);
185 	if (unlikely(r < 0))
186 		goto out;
187 
188 	r = verity_hash_update(v, req, data, len, &wait);
189 	if (unlikely(r < 0))
190 		goto out;
191 
192 	r = verity_hash_final(v, req, digest, &wait);
193 
194 out:
195 	return r;
196 }
197 
verity_hash_at_level(struct dm_verity * v,sector_t block,int level,sector_t * hash_block,unsigned * offset)198 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
199 				 sector_t *hash_block, unsigned *offset)
200 {
201 	sector_t position = verity_position_at_level(v, block, level);
202 	unsigned idx;
203 
204 	*hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
205 
206 	if (!offset)
207 		return;
208 
209 	idx = position & ((1 << v->hash_per_block_bits) - 1);
210 	if (!v->version)
211 		*offset = idx * v->digest_size;
212 	else
213 		*offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
214 }
215 
216 /*
217  * Handle verification errors.
218  */
verity_handle_err(struct dm_verity * v,enum verity_block_type type,unsigned long long block)219 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
220 			     unsigned long long block)
221 {
222 	char verity_env[DM_VERITY_ENV_LENGTH];
223 	char *envp[] = { verity_env, NULL };
224 	const char *type_str = "";
225 	struct mapped_device *md = dm_table_get_md(v->ti->table);
226 
227 	/* Corruption should be visible in device status in all modes */
228 	v->hash_failed = true;
229 
230 	if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
231 		goto out;
232 
233 	v->corrupted_errs++;
234 
235 	switch (type) {
236 	case DM_VERITY_BLOCK_TYPE_DATA:
237 		type_str = "data";
238 		break;
239 	case DM_VERITY_BLOCK_TYPE_METADATA:
240 		type_str = "metadata";
241 		break;
242 	default:
243 		BUG();
244 	}
245 
246 	DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
247 		    type_str, block);
248 
249 	if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
250 		DMERR("%s: reached maximum errors", v->data_dev->name);
251 
252 	snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
253 		DM_VERITY_ENV_VAR_NAME, type, block);
254 
255 	kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
256 
257 out:
258 	if (v->mode == DM_VERITY_MODE_LOGGING)
259 		return 0;
260 
261 	if (v->mode == DM_VERITY_MODE_RESTART)
262 		kernel_restart("dm-verity device corrupted");
263 
264 	if (v->mode == DM_VERITY_MODE_PANIC)
265 		panic("dm-verity device corrupted");
266 
267 	return 1;
268 }
269 
270 /*
271  * Verify hash of a metadata block pertaining to the specified data block
272  * ("block" argument) at a specified level ("level" argument).
273  *
274  * On successful return, verity_io_want_digest(v, io) contains the hash value
275  * for a lower tree level or for the data block (if we're at the lowest level).
276  *
277  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
278  * If "skip_unverified" is false, unverified buffer is hashed and verified
279  * against current value of verity_io_want_digest(v, io).
280  */
verity_verify_level(struct dm_verity * v,struct dm_verity_io * io,sector_t block,int level,bool skip_unverified,u8 * want_digest)281 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
282 			       sector_t block, int level, bool skip_unverified,
283 			       u8 *want_digest)
284 {
285 	struct dm_buffer *buf;
286 	struct buffer_aux *aux;
287 	u8 *data;
288 	int r;
289 	sector_t hash_block;
290 	unsigned offset;
291 
292 	verity_hash_at_level(v, block, level, &hash_block, &offset);
293 
294 	if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
295 		data = dm_bufio_get(v->bufio, hash_block, &buf);
296 		if (data == NULL) {
297 			/*
298 			 * In tasklet and the hash was not in the bufio cache.
299 			 * Return early and resume execution from a work-queue
300 			 * to read the hash from disk.
301 			 */
302 			return -EAGAIN;
303 		}
304 	} else
305 		data = dm_bufio_read(v->bufio, hash_block, &buf);
306 
307 	if (IS_ERR(data))
308 		return PTR_ERR(data);
309 
310 	aux = dm_bufio_get_aux_data(buf);
311 
312 	if (!aux->hash_verified) {
313 		if (skip_unverified) {
314 			r = 1;
315 			goto release_ret_r;
316 		}
317 
318 		r = verity_hash(v, verity_io_hash_req(v, io),
319 				data, 1 << v->hash_dev_block_bits,
320 				verity_io_real_digest(v, io));
321 		if (unlikely(r < 0))
322 			goto release_ret_r;
323 
324 		if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
325 				  v->digest_size) == 0))
326 			aux->hash_verified = 1;
327 		else if (static_branch_unlikely(&use_tasklet_enabled) &&
328 			 io->in_tasklet) {
329 			/*
330 			 * Error handling code (FEC included) cannot be run in a
331 			 * tasklet since it may sleep, so fallback to work-queue.
332 			 */
333 			r = -EAGAIN;
334 			goto release_ret_r;
335 		}
336 		else if (verity_fec_decode(v, io,
337 					   DM_VERITY_BLOCK_TYPE_METADATA,
338 					   hash_block, data, NULL) == 0)
339 			aux->hash_verified = 1;
340 		else if (verity_handle_err(v,
341 					   DM_VERITY_BLOCK_TYPE_METADATA,
342 					   hash_block)) {
343 			r = -EIO;
344 			goto release_ret_r;
345 		}
346 	}
347 
348 	data += offset;
349 	memcpy(want_digest, data, v->digest_size);
350 	r = 0;
351 
352 release_ret_r:
353 	dm_bufio_release(buf);
354 	return r;
355 }
356 
357 /*
358  * Find a hash for a given block, write it to digest and verify the integrity
359  * of the hash tree if necessary.
360  */
verity_hash_for_block(struct dm_verity * v,struct dm_verity_io * io,sector_t block,u8 * digest,bool * is_zero)361 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
362 			  sector_t block, u8 *digest, bool *is_zero)
363 {
364 	int r = 0, i;
365 
366 	if (likely(v->levels)) {
367 		/*
368 		 * First, we try to get the requested hash for
369 		 * the current block. If the hash block itself is
370 		 * verified, zero is returned. If it isn't, this
371 		 * function returns 1 and we fall back to whole
372 		 * chain verification.
373 		 */
374 		r = verity_verify_level(v, io, block, 0, true, digest);
375 		if (likely(r <= 0))
376 			goto out;
377 	}
378 
379 	memcpy(digest, v->root_digest, v->digest_size);
380 
381 	for (i = v->levels - 1; i >= 0; i--) {
382 		r = verity_verify_level(v, io, block, i, false, digest);
383 		if (unlikely(r))
384 			goto out;
385 	}
386 out:
387 	if (!r && v->zero_digest)
388 		*is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
389 	else
390 		*is_zero = false;
391 
392 	return r;
393 }
394 
395 /*
396  * Calculates the digest for the given bio
397  */
verity_for_io_block(struct dm_verity * v,struct dm_verity_io * io,struct bvec_iter * iter,struct crypto_wait * wait)398 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
399 			       struct bvec_iter *iter, struct crypto_wait *wait)
400 {
401 	unsigned int todo = 1 << v->data_dev_block_bits;
402 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
403 	struct scatterlist sg;
404 	struct ahash_request *req = verity_io_hash_req(v, io);
405 
406 	do {
407 		int r;
408 		unsigned int len;
409 		struct bio_vec bv = bio_iter_iovec(bio, *iter);
410 
411 		sg_init_table(&sg, 1);
412 
413 		len = bv.bv_len;
414 
415 		if (likely(len >= todo))
416 			len = todo;
417 		/*
418 		 * Operating on a single page at a time looks suboptimal
419 		 * until you consider the typical block size is 4,096B.
420 		 * Going through this loops twice should be very rare.
421 		 */
422 		sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
423 		ahash_request_set_crypt(req, &sg, NULL, len);
424 		r = crypto_wait_req(crypto_ahash_update(req), wait);
425 
426 		if (unlikely(r < 0)) {
427 			DMERR("verity_for_io_block crypto op failed: %d", r);
428 			return r;
429 		}
430 
431 		bio_advance_iter(bio, iter, len);
432 		todo -= len;
433 	} while (todo);
434 
435 	return 0;
436 }
437 
438 /*
439  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
440  * starting from iter.
441  */
verity_for_bv_block(struct dm_verity * v,struct dm_verity_io * io,struct bvec_iter * iter,int (* process)(struct dm_verity * v,struct dm_verity_io * io,u8 * data,size_t len))442 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
443 			struct bvec_iter *iter,
444 			int (*process)(struct dm_verity *v,
445 				       struct dm_verity_io *io, u8 *data,
446 				       size_t len))
447 {
448 	unsigned todo = 1 << v->data_dev_block_bits;
449 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
450 
451 	do {
452 		int r;
453 		u8 *page;
454 		unsigned len;
455 		struct bio_vec bv = bio_iter_iovec(bio, *iter);
456 
457 		page = bvec_kmap_local(&bv);
458 		len = bv.bv_len;
459 
460 		if (likely(len >= todo))
461 			len = todo;
462 
463 		r = process(v, io, page, len);
464 		kunmap_local(page);
465 
466 		if (r < 0)
467 			return r;
468 
469 		bio_advance_iter(bio, iter, len);
470 		todo -= len;
471 	} while (todo);
472 
473 	return 0;
474 }
475 
verity_bv_zero(struct dm_verity * v,struct dm_verity_io * io,u8 * data,size_t len)476 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
477 			  u8 *data, size_t len)
478 {
479 	memset(data, 0, len);
480 	return 0;
481 }
482 
483 /*
484  * Moves the bio iter one data block forward.
485  */
verity_bv_skip_block(struct dm_verity * v,struct dm_verity_io * io,struct bvec_iter * iter)486 static inline void verity_bv_skip_block(struct dm_verity *v,
487 					struct dm_verity_io *io,
488 					struct bvec_iter *iter)
489 {
490 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
491 
492 	bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
493 }
494 
495 /*
496  * Verify one "dm_verity_io" structure.
497  */
verity_verify_io(struct dm_verity_io * io)498 static int verity_verify_io(struct dm_verity_io *io)
499 {
500 	bool is_zero;
501 	struct dm_verity *v = io->v;
502 #if defined(CONFIG_DM_VERITY_FEC)
503 	struct bvec_iter start;
504 #endif
505 	struct bvec_iter iter_copy;
506 	struct bvec_iter *iter;
507 	struct crypto_wait wait;
508 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
509 	unsigned int b;
510 
511 	if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
512 		/*
513 		 * Copy the iterator in case we need to restart
514 		 * verification in a work-queue.
515 		 */
516 		iter_copy = io->iter;
517 		iter = &iter_copy;
518 	} else
519 		iter = &io->iter;
520 
521 	for (b = 0; b < io->n_blocks; b++) {
522 		int r;
523 		sector_t cur_block = io->block + b;
524 		struct ahash_request *req = verity_io_hash_req(v, io);
525 
526 		if (v->validated_blocks &&
527 		    likely(test_bit(cur_block, v->validated_blocks))) {
528 			verity_bv_skip_block(v, io, iter);
529 			continue;
530 		}
531 
532 		r = verity_hash_for_block(v, io, cur_block,
533 					  verity_io_want_digest(v, io),
534 					  &is_zero);
535 		if (unlikely(r < 0))
536 			return r;
537 
538 		if (is_zero) {
539 			/*
540 			 * If we expect a zero block, don't validate, just
541 			 * return zeros.
542 			 */
543 			r = verity_for_bv_block(v, io, iter,
544 						verity_bv_zero);
545 			if (unlikely(r < 0))
546 				return r;
547 
548 			continue;
549 		}
550 
551 		r = verity_hash_init(v, req, &wait);
552 		if (unlikely(r < 0))
553 			return r;
554 
555 #if defined(CONFIG_DM_VERITY_FEC)
556 		if (verity_fec_is_enabled(v))
557 			start = *iter;
558 #endif
559 		r = verity_for_io_block(v, io, iter, &wait);
560 		if (unlikely(r < 0))
561 			return r;
562 
563 		r = verity_hash_final(v, req, verity_io_real_digest(v, io),
564 					&wait);
565 		if (unlikely(r < 0))
566 			return r;
567 
568 		if (likely(memcmp(verity_io_real_digest(v, io),
569 				  verity_io_want_digest(v, io), v->digest_size) == 0)) {
570 			if (v->validated_blocks)
571 				set_bit(cur_block, v->validated_blocks);
572 			continue;
573 		} else if (static_branch_unlikely(&use_tasklet_enabled) &&
574 			   io->in_tasklet) {
575 			/*
576 			 * Error handling code (FEC included) cannot be run in a
577 			 * tasklet since it may sleep, so fallback to work-queue.
578 			 */
579 			return -EAGAIN;
580 #if defined(CONFIG_DM_VERITY_FEC)
581 		} else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
582 					     cur_block, NULL, &start) == 0) {
583 			continue;
584 #endif
585 		} else {
586 			if (bio->bi_status) {
587 				/*
588 				 * Error correction failed; Just return error
589 				 */
590 				return -EIO;
591 			}
592 			if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
593 					      cur_block))
594 				return -EIO;
595 		}
596 	}
597 
598 	return 0;
599 }
600 
601 /*
602  * Skip verity work in response to I/O error when system is shutting down.
603  */
verity_is_system_shutting_down(void)604 static inline bool verity_is_system_shutting_down(void)
605 {
606 	return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
607 		|| system_state == SYSTEM_RESTART;
608 }
609 
610 /*
611  * End one "io" structure with a given error.
612  */
verity_finish_io(struct dm_verity_io * io,blk_status_t status)613 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
614 {
615 	struct dm_verity *v = io->v;
616 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
617 
618 	bio->bi_end_io = io->orig_bi_end_io;
619 	bio->bi_status = status;
620 
621 	if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
622 		verity_fec_finish_io(io);
623 
624 	bio_endio(bio);
625 }
626 
verity_work(struct work_struct * w)627 static void verity_work(struct work_struct *w)
628 {
629 	struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
630 
631 	io->in_tasklet = false;
632 
633 	verity_fec_init_io(io);
634 	verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
635 }
636 
verity_tasklet(unsigned long data)637 static void verity_tasklet(unsigned long data)
638 {
639 	struct dm_verity_io *io = (struct dm_verity_io *)data;
640 	int err;
641 
642 	io->in_tasklet = true;
643 	err = verity_verify_io(io);
644 	if (err == -EAGAIN) {
645 		/* fallback to retrying with work-queue */
646 		INIT_WORK(&io->work, verity_work);
647 		queue_work(io->v->verify_wq, &io->work);
648 		return;
649 	}
650 
651 	verity_finish_io(io, errno_to_blk_status(err));
652 }
653 
verity_end_io(struct bio * bio)654 static void verity_end_io(struct bio *bio)
655 {
656 	struct dm_verity_io *io = bio->bi_private;
657 
658 	if (bio->bi_status &&
659 	    (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
660 		verity_finish_io(io, bio->bi_status);
661 		return;
662 	}
663 
664 	if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
665 		tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
666 		tasklet_schedule(&io->tasklet);
667 	} else {
668 		INIT_WORK(&io->work, verity_work);
669 		queue_work(io->v->verify_wq, &io->work);
670 	}
671 }
672 
673 /*
674  * Prefetch buffers for the specified io.
675  * The root buffer is not prefetched, it is assumed that it will be cached
676  * all the time.
677  */
verity_prefetch_io(struct work_struct * work)678 static void verity_prefetch_io(struct work_struct *work)
679 {
680 	struct dm_verity_prefetch_work *pw =
681 		container_of(work, struct dm_verity_prefetch_work, work);
682 	struct dm_verity *v = pw->v;
683 	int i;
684 
685 	for (i = v->levels - 2; i >= 0; i--) {
686 		sector_t hash_block_start;
687 		sector_t hash_block_end;
688 		verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
689 		verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
690 		if (!i) {
691 			unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
692 
693 			cluster >>= v->data_dev_block_bits;
694 			if (unlikely(!cluster))
695 				goto no_prefetch_cluster;
696 
697 			if (unlikely(cluster & (cluster - 1)))
698 				cluster = 1 << __fls(cluster);
699 
700 			hash_block_start &= ~(sector_t)(cluster - 1);
701 			hash_block_end |= cluster - 1;
702 			if (unlikely(hash_block_end >= v->hash_blocks))
703 				hash_block_end = v->hash_blocks - 1;
704 		}
705 no_prefetch_cluster:
706 		dm_bufio_prefetch(v->bufio, hash_block_start,
707 				  hash_block_end - hash_block_start + 1);
708 	}
709 
710 	kfree(pw);
711 }
712 
verity_submit_prefetch(struct dm_verity * v,struct dm_verity_io * io)713 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
714 {
715 	sector_t block = io->block;
716 	unsigned int n_blocks = io->n_blocks;
717 	struct dm_verity_prefetch_work *pw;
718 
719 	if (v->validated_blocks) {
720 		while (n_blocks && test_bit(block, v->validated_blocks)) {
721 			block++;
722 			n_blocks--;
723 		}
724 		while (n_blocks && test_bit(block + n_blocks - 1,
725 					    v->validated_blocks))
726 			n_blocks--;
727 		if (!n_blocks)
728 			return;
729 	}
730 
731 	pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
732 		GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
733 
734 	if (!pw)
735 		return;
736 
737 	INIT_WORK(&pw->work, verity_prefetch_io);
738 	pw->v = v;
739 	pw->block = block;
740 	pw->n_blocks = n_blocks;
741 	queue_work(v->verify_wq, &pw->work);
742 }
743 
744 /*
745  * Bio map function. It allocates dm_verity_io structure and bio vector and
746  * fills them. Then it issues prefetches and the I/O.
747  */
verity_map(struct dm_target * ti,struct bio * bio)748 static int verity_map(struct dm_target *ti, struct bio *bio)
749 {
750 	struct dm_verity *v = ti->private;
751 	struct dm_verity_io *io;
752 
753 	bio_set_dev(bio, v->data_dev->bdev);
754 	bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
755 
756 	if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
757 	    ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
758 		DMERR_LIMIT("unaligned io");
759 		return DM_MAPIO_KILL;
760 	}
761 
762 	if (bio_end_sector(bio) >>
763 	    (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
764 		DMERR_LIMIT("io out of range");
765 		return DM_MAPIO_KILL;
766 	}
767 
768 	if (bio_data_dir(bio) == WRITE)
769 		return DM_MAPIO_KILL;
770 
771 	io = dm_per_bio_data(bio, ti->per_io_data_size);
772 	io->v = v;
773 	io->orig_bi_end_io = bio->bi_end_io;
774 	io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
775 	io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
776 
777 	bio->bi_end_io = verity_end_io;
778 	bio->bi_private = io;
779 	io->iter = bio->bi_iter;
780 
781 	verity_submit_prefetch(v, io);
782 
783 	submit_bio_noacct(bio);
784 
785 	return DM_MAPIO_SUBMITTED;
786 }
787 
788 /*
789  * Status: V (valid) or C (corruption found)
790  */
verity_status(struct dm_target * ti,status_type_t type,unsigned status_flags,char * result,unsigned maxlen)791 static void verity_status(struct dm_target *ti, status_type_t type,
792 			  unsigned status_flags, char *result, unsigned maxlen)
793 {
794 	struct dm_verity *v = ti->private;
795 	unsigned args = 0;
796 	unsigned sz = 0;
797 	unsigned x;
798 
799 	switch (type) {
800 	case STATUSTYPE_INFO:
801 		DMEMIT("%c", v->hash_failed ? 'C' : 'V');
802 		break;
803 	case STATUSTYPE_TABLE:
804 		DMEMIT("%u %s %s %u %u %llu %llu %s ",
805 			v->version,
806 			v->data_dev->name,
807 			v->hash_dev->name,
808 			1 << v->data_dev_block_bits,
809 			1 << v->hash_dev_block_bits,
810 			(unsigned long long)v->data_blocks,
811 			(unsigned long long)v->hash_start,
812 			v->alg_name
813 			);
814 		for (x = 0; x < v->digest_size; x++)
815 			DMEMIT("%02x", v->root_digest[x]);
816 		DMEMIT(" ");
817 		if (!v->salt_size)
818 			DMEMIT("-");
819 		else
820 			for (x = 0; x < v->salt_size; x++)
821 				DMEMIT("%02x", v->salt[x]);
822 		if (v->mode != DM_VERITY_MODE_EIO)
823 			args++;
824 		if (verity_fec_is_enabled(v))
825 			args += DM_VERITY_OPTS_FEC;
826 		if (v->zero_digest)
827 			args++;
828 		if (v->validated_blocks)
829 			args++;
830 		if (v->use_tasklet)
831 			args++;
832 		if (v->signature_key_desc)
833 			args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
834 		if (!args)
835 			return;
836 		DMEMIT(" %u", args);
837 		if (v->mode != DM_VERITY_MODE_EIO) {
838 			DMEMIT(" ");
839 			switch (v->mode) {
840 			case DM_VERITY_MODE_LOGGING:
841 				DMEMIT(DM_VERITY_OPT_LOGGING);
842 				break;
843 			case DM_VERITY_MODE_RESTART:
844 				DMEMIT(DM_VERITY_OPT_RESTART);
845 				break;
846 			case DM_VERITY_MODE_PANIC:
847 				DMEMIT(DM_VERITY_OPT_PANIC);
848 				break;
849 			default:
850 				BUG();
851 			}
852 		}
853 		if (v->zero_digest)
854 			DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
855 		if (v->validated_blocks)
856 			DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
857 		if (v->use_tasklet)
858 			DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
859 		sz = verity_fec_status_table(v, sz, result, maxlen);
860 		if (v->signature_key_desc)
861 			DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
862 				" %s", v->signature_key_desc);
863 		break;
864 
865 	case STATUSTYPE_IMA:
866 		DMEMIT_TARGET_NAME_VERSION(ti->type);
867 		DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
868 		DMEMIT(",verity_version=%u", v->version);
869 		DMEMIT(",data_device_name=%s", v->data_dev->name);
870 		DMEMIT(",hash_device_name=%s", v->hash_dev->name);
871 		DMEMIT(",verity_algorithm=%s", v->alg_name);
872 
873 		DMEMIT(",root_digest=");
874 		for (x = 0; x < v->digest_size; x++)
875 			DMEMIT("%02x", v->root_digest[x]);
876 
877 		DMEMIT(",salt=");
878 		if (!v->salt_size)
879 			DMEMIT("-");
880 		else
881 			for (x = 0; x < v->salt_size; x++)
882 				DMEMIT("%02x", v->salt[x]);
883 
884 		DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
885 		DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
886 		if (v->signature_key_desc)
887 			DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
888 
889 		if (v->mode != DM_VERITY_MODE_EIO) {
890 			DMEMIT(",verity_mode=");
891 			switch (v->mode) {
892 			case DM_VERITY_MODE_LOGGING:
893 				DMEMIT(DM_VERITY_OPT_LOGGING);
894 				break;
895 			case DM_VERITY_MODE_RESTART:
896 				DMEMIT(DM_VERITY_OPT_RESTART);
897 				break;
898 			case DM_VERITY_MODE_PANIC:
899 				DMEMIT(DM_VERITY_OPT_PANIC);
900 				break;
901 			default:
902 				DMEMIT("invalid");
903 			}
904 		}
905 		DMEMIT(";");
906 		break;
907 	}
908 }
909 
verity_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev)910 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
911 {
912 	struct dm_verity *v = ti->private;
913 
914 	*bdev = v->data_dev->bdev;
915 
916 	if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
917 		return 1;
918 	return 0;
919 }
920 
verity_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)921 static int verity_iterate_devices(struct dm_target *ti,
922 				  iterate_devices_callout_fn fn, void *data)
923 {
924 	struct dm_verity *v = ti->private;
925 
926 	return fn(ti, v->data_dev, v->data_start, ti->len, data);
927 }
928 
verity_io_hints(struct dm_target * ti,struct queue_limits * limits)929 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
930 {
931 	struct dm_verity *v = ti->private;
932 
933 	if (limits->logical_block_size < 1 << v->data_dev_block_bits)
934 		limits->logical_block_size = 1 << v->data_dev_block_bits;
935 
936 	if (limits->physical_block_size < 1 << v->data_dev_block_bits)
937 		limits->physical_block_size = 1 << v->data_dev_block_bits;
938 
939 	blk_limits_io_min(limits, limits->logical_block_size);
940 }
941 
verity_dtr(struct dm_target * ti)942 static void verity_dtr(struct dm_target *ti)
943 {
944 	struct dm_verity *v = ti->private;
945 
946 	if (v->verify_wq)
947 		destroy_workqueue(v->verify_wq);
948 
949 	if (v->bufio)
950 		dm_bufio_client_destroy(v->bufio);
951 
952 	kvfree(v->validated_blocks);
953 	kfree(v->salt);
954 	kfree(v->root_digest);
955 	kfree(v->zero_digest);
956 
957 	if (v->tfm)
958 		crypto_free_ahash(v->tfm);
959 
960 	kfree(v->alg_name);
961 
962 	if (v->hash_dev)
963 		dm_put_device(ti, v->hash_dev);
964 
965 	if (v->data_dev)
966 		dm_put_device(ti, v->data_dev);
967 
968 	verity_fec_dtr(v);
969 
970 	kfree(v->signature_key_desc);
971 
972 	if (v->use_tasklet)
973 		static_branch_dec(&use_tasklet_enabled);
974 
975 	kfree(v);
976 }
977 
verity_alloc_most_once(struct dm_verity * v)978 static int verity_alloc_most_once(struct dm_verity *v)
979 {
980 	struct dm_target *ti = v->ti;
981 
982 	/* the bitset can only handle INT_MAX blocks */
983 	if (v->data_blocks > INT_MAX) {
984 		ti->error = "device too large to use check_at_most_once";
985 		return -E2BIG;
986 	}
987 
988 	v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
989 				       sizeof(unsigned long),
990 				       GFP_KERNEL);
991 	if (!v->validated_blocks) {
992 		ti->error = "failed to allocate bitset for check_at_most_once";
993 		return -ENOMEM;
994 	}
995 
996 	return 0;
997 }
998 
verity_alloc_zero_digest(struct dm_verity * v)999 static int verity_alloc_zero_digest(struct dm_verity *v)
1000 {
1001 	int r = -ENOMEM;
1002 	struct ahash_request *req;
1003 	u8 *zero_data;
1004 
1005 	v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1006 
1007 	if (!v->zero_digest)
1008 		return r;
1009 
1010 	req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1011 
1012 	if (!req)
1013 		return r; /* verity_dtr will free zero_digest */
1014 
1015 	zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1016 
1017 	if (!zero_data)
1018 		goto out;
1019 
1020 	r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1021 			v->zero_digest);
1022 
1023 out:
1024 	kfree(req);
1025 	kfree(zero_data);
1026 
1027 	return r;
1028 }
1029 
verity_is_verity_mode(const char * arg_name)1030 static inline bool verity_is_verity_mode(const char *arg_name)
1031 {
1032 	return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1033 		!strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1034 		!strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1035 }
1036 
verity_parse_verity_mode(struct dm_verity * v,const char * arg_name)1037 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1038 {
1039 	if (v->mode)
1040 		return -EINVAL;
1041 
1042 	if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1043 		v->mode = DM_VERITY_MODE_LOGGING;
1044 	else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1045 		v->mode = DM_VERITY_MODE_RESTART;
1046 	else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1047 		v->mode = DM_VERITY_MODE_PANIC;
1048 
1049 	return 0;
1050 }
1051 
verity_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,struct dm_verity_sig_opts * verify_args,bool only_modifier_opts)1052 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1053 				 struct dm_verity_sig_opts *verify_args,
1054 				 bool only_modifier_opts)
1055 {
1056 	int r = 0;
1057 	unsigned argc;
1058 	struct dm_target *ti = v->ti;
1059 	const char *arg_name;
1060 
1061 	static const struct dm_arg _args[] = {
1062 		{0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1063 	};
1064 
1065 	r = dm_read_arg_group(_args, as, &argc, &ti->error);
1066 	if (r)
1067 		return -EINVAL;
1068 
1069 	if (!argc)
1070 		return 0;
1071 
1072 	do {
1073 		arg_name = dm_shift_arg(as);
1074 		argc--;
1075 
1076 		if (verity_is_verity_mode(arg_name)) {
1077 			if (only_modifier_opts)
1078 				continue;
1079 			r = verity_parse_verity_mode(v, arg_name);
1080 			if (r) {
1081 				ti->error = "Conflicting error handling parameters";
1082 				return r;
1083 			}
1084 			continue;
1085 
1086 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1087 			if (only_modifier_opts)
1088 				continue;
1089 			r = verity_alloc_zero_digest(v);
1090 			if (r) {
1091 				ti->error = "Cannot allocate zero digest";
1092 				return r;
1093 			}
1094 			continue;
1095 
1096 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1097 			if (only_modifier_opts)
1098 				continue;
1099 			r = verity_alloc_most_once(v);
1100 			if (r)
1101 				return r;
1102 			continue;
1103 
1104 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1105 			v->use_tasklet = true;
1106 			static_branch_inc(&use_tasklet_enabled);
1107 			continue;
1108 
1109 		} else if (verity_is_fec_opt_arg(arg_name)) {
1110 			if (only_modifier_opts)
1111 				continue;
1112 			r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1113 			if (r)
1114 				return r;
1115 			continue;
1116 
1117 		} else if (verity_verify_is_sig_opt_arg(arg_name)) {
1118 			if (only_modifier_opts)
1119 				continue;
1120 			r = verity_verify_sig_parse_opt_args(as, v,
1121 							     verify_args,
1122 							     &argc, arg_name);
1123 			if (r)
1124 				return r;
1125 			continue;
1126 
1127 		} else if (only_modifier_opts) {
1128 			/*
1129 			 * Ignore unrecognized opt, could easily be an extra
1130 			 * argument to an option whose parsing was skipped.
1131 			 * Normal parsing (@only_modifier_opts=false) will
1132 			 * properly parse all options (and their extra args).
1133 			 */
1134 			continue;
1135 		}
1136 
1137 		DMERR("Unrecognized verity feature request: %s", arg_name);
1138 		ti->error = "Unrecognized verity feature request";
1139 		return -EINVAL;
1140 	} while (argc && !r);
1141 
1142 	return r;
1143 }
1144 
1145 /*
1146  * Target parameters:
1147  *	<version>	The current format is version 1.
1148  *			Vsn 0 is compatible with original Chromium OS releases.
1149  *	<data device>
1150  *	<hash device>
1151  *	<data block size>
1152  *	<hash block size>
1153  *	<the number of data blocks>
1154  *	<hash start block>
1155  *	<algorithm>
1156  *	<digest>
1157  *	<salt>		Hex string or "-" if no salt.
1158  */
verity_ctr(struct dm_target * ti,unsigned argc,char ** argv)1159 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
1160 {
1161 	struct dm_verity *v;
1162 	struct dm_verity_sig_opts verify_args = {0};
1163 	struct dm_arg_set as;
1164 	unsigned int num;
1165 	unsigned int wq_flags;
1166 	unsigned long long num_ll;
1167 	int r;
1168 	int i;
1169 	sector_t hash_position;
1170 	char dummy;
1171 	char *root_hash_digest_to_validate;
1172 
1173 	v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1174 	if (!v) {
1175 		ti->error = "Cannot allocate verity structure";
1176 		return -ENOMEM;
1177 	}
1178 	ti->private = v;
1179 	v->ti = ti;
1180 
1181 	r = verity_fec_ctr_alloc(v);
1182 	if (r)
1183 		goto bad;
1184 
1185 	if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
1186 		ti->error = "Device must be readonly";
1187 		r = -EINVAL;
1188 		goto bad;
1189 	}
1190 
1191 	if (argc < 10) {
1192 		ti->error = "Not enough arguments";
1193 		r = -EINVAL;
1194 		goto bad;
1195 	}
1196 
1197 	/* Parse optional parameters that modify primary args */
1198 	if (argc > 10) {
1199 		as.argc = argc - 10;
1200 		as.argv = argv + 10;
1201 		r = verity_parse_opt_args(&as, v, &verify_args, true);
1202 		if (r < 0)
1203 			goto bad;
1204 	}
1205 
1206 	if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1207 	    num > 1) {
1208 		ti->error = "Invalid version";
1209 		r = -EINVAL;
1210 		goto bad;
1211 	}
1212 	v->version = num;
1213 
1214 	r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1215 	if (r) {
1216 		ti->error = "Data device lookup failed";
1217 		goto bad;
1218 	}
1219 
1220 	r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1221 	if (r) {
1222 		ti->error = "Hash device lookup failed";
1223 		goto bad;
1224 	}
1225 
1226 	if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1227 	    !num || (num & (num - 1)) ||
1228 	    num < bdev_logical_block_size(v->data_dev->bdev) ||
1229 	    num > PAGE_SIZE) {
1230 		ti->error = "Invalid data device block size";
1231 		r = -EINVAL;
1232 		goto bad;
1233 	}
1234 	v->data_dev_block_bits = __ffs(num);
1235 
1236 	if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1237 	    !num || (num & (num - 1)) ||
1238 	    num < bdev_logical_block_size(v->hash_dev->bdev) ||
1239 	    num > INT_MAX) {
1240 		ti->error = "Invalid hash device block size";
1241 		r = -EINVAL;
1242 		goto bad;
1243 	}
1244 	v->hash_dev_block_bits = __ffs(num);
1245 
1246 	if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1247 	    (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1248 	    >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1249 		ti->error = "Invalid data blocks";
1250 		r = -EINVAL;
1251 		goto bad;
1252 	}
1253 	v->data_blocks = num_ll;
1254 
1255 	if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1256 		ti->error = "Data device is too small";
1257 		r = -EINVAL;
1258 		goto bad;
1259 	}
1260 
1261 	if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1262 	    (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1263 	    >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1264 		ti->error = "Invalid hash start";
1265 		r = -EINVAL;
1266 		goto bad;
1267 	}
1268 	v->hash_start = num_ll;
1269 
1270 	v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1271 	if (!v->alg_name) {
1272 		ti->error = "Cannot allocate algorithm name";
1273 		r = -ENOMEM;
1274 		goto bad;
1275 	}
1276 
1277 	v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1278 				    v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1279 	if (IS_ERR(v->tfm)) {
1280 		ti->error = "Cannot initialize hash function";
1281 		r = PTR_ERR(v->tfm);
1282 		v->tfm = NULL;
1283 		goto bad;
1284 	}
1285 
1286 	/*
1287 	 * dm-verity performance can vary greatly depending on which hash
1288 	 * algorithm implementation is used.  Help people debug performance
1289 	 * problems by logging the ->cra_driver_name.
1290 	 */
1291 	DMINFO("%s using implementation \"%s\"", v->alg_name,
1292 	       crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1293 
1294 	v->digest_size = crypto_ahash_digestsize(v->tfm);
1295 	if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1296 		ti->error = "Digest size too big";
1297 		r = -EINVAL;
1298 		goto bad;
1299 	}
1300 	v->ahash_reqsize = sizeof(struct ahash_request) +
1301 		crypto_ahash_reqsize(v->tfm);
1302 
1303 	v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1304 	if (!v->root_digest) {
1305 		ti->error = "Cannot allocate root digest";
1306 		r = -ENOMEM;
1307 		goto bad;
1308 	}
1309 	if (strlen(argv[8]) != v->digest_size * 2 ||
1310 	    hex2bin(v->root_digest, argv[8], v->digest_size)) {
1311 		ti->error = "Invalid root digest";
1312 		r = -EINVAL;
1313 		goto bad;
1314 	}
1315 	root_hash_digest_to_validate = argv[8];
1316 
1317 	if (strcmp(argv[9], "-")) {
1318 		v->salt_size = strlen(argv[9]) / 2;
1319 		v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1320 		if (!v->salt) {
1321 			ti->error = "Cannot allocate salt";
1322 			r = -ENOMEM;
1323 			goto bad;
1324 		}
1325 		if (strlen(argv[9]) != v->salt_size * 2 ||
1326 		    hex2bin(v->salt, argv[9], v->salt_size)) {
1327 			ti->error = "Invalid salt";
1328 			r = -EINVAL;
1329 			goto bad;
1330 		}
1331 	}
1332 
1333 	argv += 10;
1334 	argc -= 10;
1335 
1336 	/* Optional parameters */
1337 	if (argc) {
1338 		as.argc = argc;
1339 		as.argv = argv;
1340 		r = verity_parse_opt_args(&as, v, &verify_args, false);
1341 		if (r < 0)
1342 			goto bad;
1343 	}
1344 
1345 	/* Root hash signature is  a optional parameter*/
1346 	r = verity_verify_root_hash(root_hash_digest_to_validate,
1347 				    strlen(root_hash_digest_to_validate),
1348 				    verify_args.sig,
1349 				    verify_args.sig_size);
1350 	if (r < 0) {
1351 		ti->error = "Root hash verification failed";
1352 		goto bad;
1353 	}
1354 	v->hash_per_block_bits =
1355 		__fls((1 << v->hash_dev_block_bits) / v->digest_size);
1356 
1357 	v->levels = 0;
1358 	if (v->data_blocks)
1359 		while (v->hash_per_block_bits * v->levels < 64 &&
1360 		       (unsigned long long)(v->data_blocks - 1) >>
1361 		       (v->hash_per_block_bits * v->levels))
1362 			v->levels++;
1363 
1364 	if (v->levels > DM_VERITY_MAX_LEVELS) {
1365 		ti->error = "Too many tree levels";
1366 		r = -E2BIG;
1367 		goto bad;
1368 	}
1369 
1370 	hash_position = v->hash_start;
1371 	for (i = v->levels - 1; i >= 0; i--) {
1372 		sector_t s;
1373 		v->hash_level_block[i] = hash_position;
1374 		s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1375 					>> ((i + 1) * v->hash_per_block_bits);
1376 		if (hash_position + s < hash_position) {
1377 			ti->error = "Hash device offset overflow";
1378 			r = -E2BIG;
1379 			goto bad;
1380 		}
1381 		hash_position += s;
1382 	}
1383 	v->hash_blocks = hash_position;
1384 
1385 	v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1386 		1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1387 		dm_bufio_alloc_callback, NULL,
1388 		v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1389 	if (IS_ERR(v->bufio)) {
1390 		ti->error = "Cannot initialize dm-bufio";
1391 		r = PTR_ERR(v->bufio);
1392 		v->bufio = NULL;
1393 		goto bad;
1394 	}
1395 
1396 	if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1397 		ti->error = "Hash device is too small";
1398 		r = -E2BIG;
1399 		goto bad;
1400 	}
1401 
1402 	/* WQ_UNBOUND greatly improves performance when running on ramdisk */
1403 	wq_flags = WQ_MEM_RECLAIM | WQ_UNBOUND;
1404 	/*
1405 	 * Using WQ_HIGHPRI improves throughput and completion latency by
1406 	 * reducing wait times when reading from a dm-verity device.
1407 	 *
1408 	 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1409 	 * allows verify_wq to preempt softirq since verification in tasklet
1410 	 * will fall-back to using it for error handling (or if the bufio cache
1411 	 * doesn't have required hashes).
1412 	 */
1413 	wq_flags |= WQ_HIGHPRI;
1414 	v->verify_wq = alloc_workqueue("kverityd", wq_flags, num_online_cpus());
1415 	if (!v->verify_wq) {
1416 		ti->error = "Cannot allocate workqueue";
1417 		r = -ENOMEM;
1418 		goto bad;
1419 	}
1420 
1421 	ti->per_io_data_size = sizeof(struct dm_verity_io) +
1422 				v->ahash_reqsize + v->digest_size * 2;
1423 
1424 	r = verity_fec_ctr(v);
1425 	if (r)
1426 		goto bad;
1427 
1428 	ti->per_io_data_size = roundup(ti->per_io_data_size,
1429 				       __alignof__(struct dm_verity_io));
1430 
1431 	verity_verify_sig_opts_cleanup(&verify_args);
1432 
1433 	return 0;
1434 
1435 bad:
1436 
1437 	verity_verify_sig_opts_cleanup(&verify_args);
1438 	verity_dtr(ti);
1439 
1440 	return r;
1441 }
1442 
1443 /*
1444  * Check whether a DM target is a verity target.
1445  */
dm_is_verity_target(struct dm_target * ti)1446 bool dm_is_verity_target(struct dm_target *ti)
1447 {
1448 	return ti->type->module == THIS_MODULE;
1449 }
1450 
1451 /*
1452  * Get the verity mode (error behavior) of a verity target.
1453  *
1454  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1455  * target.
1456  */
dm_verity_get_mode(struct dm_target * ti)1457 int dm_verity_get_mode(struct dm_target *ti)
1458 {
1459 	struct dm_verity *v = ti->private;
1460 
1461 	if (!dm_is_verity_target(ti))
1462 		return -EINVAL;
1463 
1464 	return v->mode;
1465 }
1466 
1467 /*
1468  * Get the root digest of a verity target.
1469  *
1470  * Returns a copy of the root digest, the caller is responsible for
1471  * freeing the memory of the digest.
1472  */
dm_verity_get_root_digest(struct dm_target * ti,u8 ** root_digest,unsigned int * digest_size)1473 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1474 {
1475 	struct dm_verity *v = ti->private;
1476 
1477 	if (!dm_is_verity_target(ti))
1478 		return -EINVAL;
1479 
1480 	*root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1481 	if (*root_digest == NULL)
1482 		return -ENOMEM;
1483 
1484 	*digest_size = v->digest_size;
1485 
1486 	return 0;
1487 }
1488 
1489 static struct target_type verity_target = {
1490 	.name		= "verity",
1491 	.features	= DM_TARGET_IMMUTABLE,
1492 	.version	= {1, 9, 0},
1493 	.module		= THIS_MODULE,
1494 	.ctr		= verity_ctr,
1495 	.dtr		= verity_dtr,
1496 	.map		= verity_map,
1497 	.status		= verity_status,
1498 	.prepare_ioctl	= verity_prepare_ioctl,
1499 	.iterate_devices = verity_iterate_devices,
1500 	.io_hints	= verity_io_hints,
1501 };
1502 
dm_verity_init(void)1503 static int __init dm_verity_init(void)
1504 {
1505 	int r;
1506 
1507 	r = dm_register_target(&verity_target);
1508 	if (r < 0)
1509 		DMERR("register failed %d", r);
1510 
1511 	return r;
1512 }
1513 
dm_verity_exit(void)1514 static void __exit dm_verity_exit(void)
1515 {
1516 	dm_unregister_target(&verity_target);
1517 }
1518 
1519 module_init(dm_verity_init);
1520 module_exit(dm_verity_exit);
1521 
1522 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1523 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1524 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1525 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1526 MODULE_LICENSE("GPL");
1527