xref: /openbmc/linux/drivers/md/dm-verity-target.c (revision dcb5620d)
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 "dm-audit.h"
20 #include <linux/module.h>
21 #include <linux/reboot.h>
22 #include <linux/scatterlist.h>
23 #include <linux/string.h>
24 #include <linux/jump_label.h>
25 
26 #define DM_MSG_PREFIX			"verity"
27 
28 #define DM_VERITY_ENV_LENGTH		42
29 #define DM_VERITY_ENV_VAR_NAME		"DM_VERITY_ERR_BLOCK_NR"
30 
31 #define DM_VERITY_DEFAULT_PREFETCH_SIZE	262144
32 
33 #define DM_VERITY_MAX_CORRUPTED_ERRS	100
34 
35 #define DM_VERITY_OPT_LOGGING		"ignore_corruption"
36 #define DM_VERITY_OPT_RESTART		"restart_on_corruption"
37 #define DM_VERITY_OPT_PANIC		"panic_on_corruption"
38 #define DM_VERITY_OPT_IGN_ZEROES	"ignore_zero_blocks"
39 #define DM_VERITY_OPT_AT_MOST_ONCE	"check_at_most_once"
40 #define DM_VERITY_OPT_TASKLET_VERIFY	"try_verify_in_tasklet"
41 
42 #define DM_VERITY_OPTS_MAX		(4 + DM_VERITY_OPTS_FEC + \
43 					 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
44 
45 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
46 
47 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
48 
49 static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
50 
51 struct dm_verity_prefetch_work {
52 	struct work_struct work;
53 	struct dm_verity *v;
54 	sector_t block;
55 	unsigned int n_blocks;
56 };
57 
58 /*
59  * Auxiliary structure appended to each dm-bufio buffer. If the value
60  * hash_verified is nonzero, hash of the block has been verified.
61  *
62  * The variable hash_verified is set to 0 when allocating the buffer, then
63  * it can be changed to 1 and it is never reset to 0 again.
64  *
65  * There is no lock around this value, a race condition can at worst cause
66  * that multiple processes verify the hash of the same buffer simultaneously
67  * and write 1 to hash_verified simultaneously.
68  * This condition is harmless, so we don't need locking.
69  */
70 struct buffer_aux {
71 	int hash_verified;
72 };
73 
74 /*
75  * Initialize struct buffer_aux for a freshly created buffer.
76  */
dm_bufio_alloc_callback(struct dm_buffer * buf)77 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
78 {
79 	struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
80 
81 	aux->hash_verified = 0;
82 }
83 
84 /*
85  * Translate input sector number to the sector number on the target device.
86  */
verity_map_sector(struct dm_verity * v,sector_t bi_sector)87 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
88 {
89 	return v->data_start + dm_target_offset(v->ti, bi_sector);
90 }
91 
92 /*
93  * Return hash position of a specified block at a specified tree level
94  * (0 is the lowest level).
95  * The lowest "hash_per_block_bits"-bits of the result denote hash position
96  * inside a hash block. The remaining bits denote location of the hash block.
97  */
verity_position_at_level(struct dm_verity * v,sector_t block,int level)98 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
99 					 int level)
100 {
101 	return block >> (level * v->hash_per_block_bits);
102 }
103 
verity_hash_update(struct dm_verity * v,struct ahash_request * req,const u8 * data,size_t len,struct crypto_wait * wait)104 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
105 				const u8 *data, size_t len,
106 				struct crypto_wait *wait)
107 {
108 	struct scatterlist sg;
109 
110 	if (likely(!is_vmalloc_addr(data))) {
111 		sg_init_one(&sg, data, len);
112 		ahash_request_set_crypt(req, &sg, NULL, len);
113 		return crypto_wait_req(crypto_ahash_update(req), wait);
114 	}
115 
116 	do {
117 		int r;
118 		size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
119 
120 		flush_kernel_vmap_range((void *)data, this_step);
121 		sg_init_table(&sg, 1);
122 		sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
123 		ahash_request_set_crypt(req, &sg, NULL, this_step);
124 		r = crypto_wait_req(crypto_ahash_update(req), wait);
125 		if (unlikely(r))
126 			return r;
127 		data += this_step;
128 		len -= this_step;
129 	} while (len);
130 
131 	return 0;
132 }
133 
134 /*
135  * Wrapper for crypto_ahash_init, which handles verity salting.
136  */
verity_hash_init(struct dm_verity * v,struct ahash_request * req,struct crypto_wait * wait,bool may_sleep)137 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
138 				struct crypto_wait *wait, bool may_sleep)
139 {
140 	int r;
141 
142 	ahash_request_set_tfm(req, v->tfm);
143 	ahash_request_set_callback(req,
144 		may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
145 		crypto_req_done, (void *)wait);
146 	crypto_init_wait(wait);
147 
148 	r = crypto_wait_req(crypto_ahash_init(req), wait);
149 
150 	if (unlikely(r < 0)) {
151 		if (r != -ENOMEM)
152 			DMERR("crypto_ahash_init failed: %d", r);
153 		return r;
154 	}
155 
156 	if (likely(v->salt_size && (v->version >= 1)))
157 		r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
158 
159 	return r;
160 }
161 
verity_hash_final(struct dm_verity * v,struct ahash_request * req,u8 * digest,struct crypto_wait * wait)162 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
163 			     u8 *digest, struct crypto_wait *wait)
164 {
165 	int r;
166 
167 	if (unlikely(v->salt_size && (!v->version))) {
168 		r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
169 
170 		if (r < 0) {
171 			DMERR("%s failed updating salt: %d", __func__, r);
172 			goto out;
173 		}
174 	}
175 
176 	ahash_request_set_crypt(req, NULL, digest, 0);
177 	r = crypto_wait_req(crypto_ahash_final(req), wait);
178 out:
179 	return r;
180 }
181 
verity_hash(struct dm_verity * v,struct ahash_request * req,const u8 * data,size_t len,u8 * digest,bool may_sleep)182 int verity_hash(struct dm_verity *v, struct ahash_request *req,
183 		const u8 *data, size_t len, u8 *digest, bool may_sleep)
184 {
185 	int r;
186 	struct crypto_wait wait;
187 
188 	r = verity_hash_init(v, req, &wait, may_sleep);
189 	if (unlikely(r < 0))
190 		goto out;
191 
192 	r = verity_hash_update(v, req, data, len, &wait);
193 	if (unlikely(r < 0))
194 		goto out;
195 
196 	r = verity_hash_final(v, req, digest, &wait);
197 
198 out:
199 	return r;
200 }
201 
verity_hash_at_level(struct dm_verity * v,sector_t block,int level,sector_t * hash_block,unsigned int * offset)202 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
203 				 sector_t *hash_block, unsigned int *offset)
204 {
205 	sector_t position = verity_position_at_level(v, block, level);
206 	unsigned int idx;
207 
208 	*hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
209 
210 	if (!offset)
211 		return;
212 
213 	idx = position & ((1 << v->hash_per_block_bits) - 1);
214 	if (!v->version)
215 		*offset = idx * v->digest_size;
216 	else
217 		*offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
218 }
219 
220 /*
221  * Handle verification errors.
222  */
verity_handle_err(struct dm_verity * v,enum verity_block_type type,unsigned long long block)223 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
224 			     unsigned long long block)
225 {
226 	char verity_env[DM_VERITY_ENV_LENGTH];
227 	char *envp[] = { verity_env, NULL };
228 	const char *type_str = "";
229 	struct mapped_device *md = dm_table_get_md(v->ti->table);
230 
231 	/* Corruption should be visible in device status in all modes */
232 	v->hash_failed = true;
233 
234 	if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
235 		goto out;
236 
237 	v->corrupted_errs++;
238 
239 	switch (type) {
240 	case DM_VERITY_BLOCK_TYPE_DATA:
241 		type_str = "data";
242 		break;
243 	case DM_VERITY_BLOCK_TYPE_METADATA:
244 		type_str = "metadata";
245 		break;
246 	default:
247 		BUG();
248 	}
249 
250 	DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
251 		    type_str, block);
252 
253 	if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
254 		DMERR("%s: reached maximum errors", v->data_dev->name);
255 		dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
256 	}
257 
258 	snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
259 		DM_VERITY_ENV_VAR_NAME, type, block);
260 
261 	kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
262 
263 out:
264 	if (v->mode == DM_VERITY_MODE_LOGGING)
265 		return 0;
266 
267 	if (v->mode == DM_VERITY_MODE_RESTART)
268 		kernel_restart("dm-verity device corrupted");
269 
270 	if (v->mode == DM_VERITY_MODE_PANIC)
271 		panic("dm-verity device corrupted");
272 
273 	return 1;
274 }
275 
276 /*
277  * Verify hash of a metadata block pertaining to the specified data block
278  * ("block" argument) at a specified level ("level" argument).
279  *
280  * On successful return, verity_io_want_digest(v, io) contains the hash value
281  * for a lower tree level or for the data block (if we're at the lowest level).
282  *
283  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
284  * If "skip_unverified" is false, unverified buffer is hashed and verified
285  * against current value of verity_io_want_digest(v, io).
286  */
verity_verify_level(struct dm_verity * v,struct dm_verity_io * io,sector_t block,int level,bool skip_unverified,u8 * want_digest)287 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
288 			       sector_t block, int level, bool skip_unverified,
289 			       u8 *want_digest)
290 {
291 	struct dm_buffer *buf;
292 	struct buffer_aux *aux;
293 	u8 *data;
294 	int r;
295 	sector_t hash_block;
296 	unsigned int offset;
297 
298 	verity_hash_at_level(v, block, level, &hash_block, &offset);
299 
300 	if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
301 		data = dm_bufio_get(v->bufio, hash_block, &buf);
302 		if (data == NULL) {
303 			/*
304 			 * In tasklet and the hash was not in the bufio cache.
305 			 * Return early and resume execution from a work-queue
306 			 * to read the hash from disk.
307 			 */
308 			return -EAGAIN;
309 		}
310 	} else
311 		data = dm_bufio_read(v->bufio, hash_block, &buf);
312 
313 	if (IS_ERR(data))
314 		return PTR_ERR(data);
315 
316 	aux = dm_bufio_get_aux_data(buf);
317 
318 	if (!aux->hash_verified) {
319 		if (skip_unverified) {
320 			r = 1;
321 			goto release_ret_r;
322 		}
323 
324 		r = verity_hash(v, verity_io_hash_req(v, io),
325 				data, 1 << v->hash_dev_block_bits,
326 				verity_io_real_digest(v, io), !io->in_tasklet);
327 		if (unlikely(r < 0))
328 			goto release_ret_r;
329 
330 		if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
331 				  v->digest_size) == 0))
332 			aux->hash_verified = 1;
333 		else if (static_branch_unlikely(&use_tasklet_enabled) &&
334 			 io->in_tasklet) {
335 			/*
336 			 * Error handling code (FEC included) cannot be run in a
337 			 * tasklet since it may sleep, so fallback to work-queue.
338 			 */
339 			r = -EAGAIN;
340 			goto release_ret_r;
341 		} else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
342 					     hash_block, data, NULL) == 0)
343 			aux->hash_verified = 1;
344 		else if (verity_handle_err(v,
345 					   DM_VERITY_BLOCK_TYPE_METADATA,
346 					   hash_block)) {
347 			struct bio *bio =
348 				dm_bio_from_per_bio_data(io,
349 							 v->ti->per_io_data_size);
350 			dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
351 					 block, 0);
352 			r = -EIO;
353 			goto release_ret_r;
354 		}
355 	}
356 
357 	data += offset;
358 	memcpy(want_digest, data, v->digest_size);
359 	r = 0;
360 
361 release_ret_r:
362 	dm_bufio_release(buf);
363 	return r;
364 }
365 
366 /*
367  * Find a hash for a given block, write it to digest and verify the integrity
368  * of the hash tree if necessary.
369  */
verity_hash_for_block(struct dm_verity * v,struct dm_verity_io * io,sector_t block,u8 * digest,bool * is_zero)370 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
371 			  sector_t block, u8 *digest, bool *is_zero)
372 {
373 	int r = 0, i;
374 
375 	if (likely(v->levels)) {
376 		/*
377 		 * First, we try to get the requested hash for
378 		 * the current block. If the hash block itself is
379 		 * verified, zero is returned. If it isn't, this
380 		 * function returns 1 and we fall back to whole
381 		 * chain verification.
382 		 */
383 		r = verity_verify_level(v, io, block, 0, true, digest);
384 		if (likely(r <= 0))
385 			goto out;
386 	}
387 
388 	memcpy(digest, v->root_digest, v->digest_size);
389 
390 	for (i = v->levels - 1; i >= 0; i--) {
391 		r = verity_verify_level(v, io, block, i, false, digest);
392 		if (unlikely(r))
393 			goto out;
394 	}
395 out:
396 	if (!r && v->zero_digest)
397 		*is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
398 	else
399 		*is_zero = false;
400 
401 	return r;
402 }
403 
404 /*
405  * Calculates the digest for the given bio
406  */
verity_for_io_block(struct dm_verity * v,struct dm_verity_io * io,struct bvec_iter * iter,struct crypto_wait * wait)407 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
408 			       struct bvec_iter *iter, struct crypto_wait *wait)
409 {
410 	unsigned int todo = 1 << v->data_dev_block_bits;
411 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
412 	struct scatterlist sg;
413 	struct ahash_request *req = verity_io_hash_req(v, io);
414 
415 	do {
416 		int r;
417 		unsigned int len;
418 		struct bio_vec bv = bio_iter_iovec(bio, *iter);
419 
420 		sg_init_table(&sg, 1);
421 
422 		len = bv.bv_len;
423 
424 		if (likely(len >= todo))
425 			len = todo;
426 		/*
427 		 * Operating on a single page at a time looks suboptimal
428 		 * until you consider the typical block size is 4,096B.
429 		 * Going through this loops twice should be very rare.
430 		 */
431 		sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
432 		ahash_request_set_crypt(req, &sg, NULL, len);
433 		r = crypto_wait_req(crypto_ahash_update(req), wait);
434 
435 		if (unlikely(r < 0)) {
436 			DMERR("%s crypto op failed: %d", __func__, r);
437 			return r;
438 		}
439 
440 		bio_advance_iter(bio, iter, len);
441 		todo -= len;
442 	} while (todo);
443 
444 	return 0;
445 }
446 
447 /*
448  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
449  * starting from iter.
450  */
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))451 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
452 			struct bvec_iter *iter,
453 			int (*process)(struct dm_verity *v,
454 				       struct dm_verity_io *io, u8 *data,
455 				       size_t len))
456 {
457 	unsigned int todo = 1 << v->data_dev_block_bits;
458 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
459 
460 	do {
461 		int r;
462 		u8 *page;
463 		unsigned int len;
464 		struct bio_vec bv = bio_iter_iovec(bio, *iter);
465 
466 		page = bvec_kmap_local(&bv);
467 		len = bv.bv_len;
468 
469 		if (likely(len >= todo))
470 			len = todo;
471 
472 		r = process(v, io, page, len);
473 		kunmap_local(page);
474 
475 		if (r < 0)
476 			return r;
477 
478 		bio_advance_iter(bio, iter, len);
479 		todo -= len;
480 	} while (todo);
481 
482 	return 0;
483 }
484 
verity_recheck_copy(struct dm_verity * v,struct dm_verity_io * io,u8 * data,size_t len)485 static int verity_recheck_copy(struct dm_verity *v, struct dm_verity_io *io,
486 			       u8 *data, size_t len)
487 {
488 	memcpy(data, io->recheck_buffer, len);
489 	io->recheck_buffer += len;
490 
491 	return 0;
492 }
493 
verity_recheck(struct dm_verity * v,struct dm_verity_io * io,struct bvec_iter start,sector_t cur_block)494 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
495 				   struct bvec_iter start, sector_t cur_block)
496 {
497 	struct page *page;
498 	void *buffer;
499 	int r;
500 	struct dm_io_request io_req;
501 	struct dm_io_region io_loc;
502 
503 	page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
504 	buffer = page_to_virt(page);
505 
506 	io_req.bi_opf = REQ_OP_READ;
507 	io_req.mem.type = DM_IO_KMEM;
508 	io_req.mem.ptr.addr = buffer;
509 	io_req.notify.fn = NULL;
510 	io_req.client = v->io;
511 	io_loc.bdev = v->data_dev->bdev;
512 	io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
513 	io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
514 	r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
515 	if (unlikely(r))
516 		goto free_ret;
517 
518 	r = verity_hash(v, verity_io_hash_req(v, io), buffer,
519 			1 << v->data_dev_block_bits,
520 			verity_io_real_digest(v, io), true);
521 	if (unlikely(r))
522 		goto free_ret;
523 
524 	if (memcmp(verity_io_real_digest(v, io),
525 		   verity_io_want_digest(v, io), v->digest_size)) {
526 		r = -EIO;
527 		goto free_ret;
528 	}
529 
530 	io->recheck_buffer = buffer;
531 	r = verity_for_bv_block(v, io, &start, verity_recheck_copy);
532 	if (unlikely(r))
533 		goto free_ret;
534 
535 	r = 0;
536 free_ret:
537 	mempool_free(page, &v->recheck_pool);
538 
539 	return r;
540 }
541 
verity_bv_zero(struct dm_verity * v,struct dm_verity_io * io,u8 * data,size_t len)542 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
543 			  u8 *data, size_t len)
544 {
545 	memset(data, 0, len);
546 	return 0;
547 }
548 
549 /*
550  * Moves the bio iter one data block forward.
551  */
verity_bv_skip_block(struct dm_verity * v,struct dm_verity_io * io,struct bvec_iter * iter)552 static inline void verity_bv_skip_block(struct dm_verity *v,
553 					struct dm_verity_io *io,
554 					struct bvec_iter *iter)
555 {
556 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
557 
558 	bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
559 }
560 
561 /*
562  * Verify one "dm_verity_io" structure.
563  */
verity_verify_io(struct dm_verity_io * io)564 static int verity_verify_io(struct dm_verity_io *io)
565 {
566 	bool is_zero;
567 	struct dm_verity *v = io->v;
568 	struct bvec_iter start;
569 	struct bvec_iter iter_copy;
570 	struct bvec_iter *iter;
571 	struct crypto_wait wait;
572 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
573 	unsigned int b;
574 
575 	if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
576 		/*
577 		 * Copy the iterator in case we need to restart
578 		 * verification in a work-queue.
579 		 */
580 		iter_copy = io->iter;
581 		iter = &iter_copy;
582 	} else
583 		iter = &io->iter;
584 
585 	for (b = 0; b < io->n_blocks; b++) {
586 		int r;
587 		sector_t cur_block = io->block + b;
588 		struct ahash_request *req = verity_io_hash_req(v, io);
589 
590 		if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
591 		    likely(test_bit(cur_block, v->validated_blocks))) {
592 			verity_bv_skip_block(v, io, iter);
593 			continue;
594 		}
595 
596 		r = verity_hash_for_block(v, io, cur_block,
597 					  verity_io_want_digest(v, io),
598 					  &is_zero);
599 		if (unlikely(r < 0))
600 			return r;
601 
602 		if (is_zero) {
603 			/*
604 			 * If we expect a zero block, don't validate, just
605 			 * return zeros.
606 			 */
607 			r = verity_for_bv_block(v, io, iter,
608 						verity_bv_zero);
609 			if (unlikely(r < 0))
610 				return r;
611 
612 			continue;
613 		}
614 
615 		r = verity_hash_init(v, req, &wait, !io->in_tasklet);
616 		if (unlikely(r < 0))
617 			return r;
618 
619 		start = *iter;
620 		r = verity_for_io_block(v, io, iter, &wait);
621 		if (unlikely(r < 0))
622 			return r;
623 
624 		r = verity_hash_final(v, req, verity_io_real_digest(v, io),
625 					&wait);
626 		if (unlikely(r < 0))
627 			return r;
628 
629 		if (likely(memcmp(verity_io_real_digest(v, io),
630 				  verity_io_want_digest(v, io), v->digest_size) == 0)) {
631 			if (v->validated_blocks)
632 				set_bit(cur_block, v->validated_blocks);
633 			continue;
634 		} else if (static_branch_unlikely(&use_tasklet_enabled) &&
635 			   io->in_tasklet) {
636 			/*
637 			 * Error handling code (FEC included) cannot be run in a
638 			 * tasklet since it may sleep, so fallback to work-queue.
639 			 */
640 			return -EAGAIN;
641 		} else if (verity_recheck(v, io, start, cur_block) == 0) {
642 			if (v->validated_blocks)
643 				set_bit(cur_block, v->validated_blocks);
644 			continue;
645 #if defined(CONFIG_DM_VERITY_FEC)
646 		} else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
647 					     cur_block, NULL, &start) == 0) {
648 			continue;
649 #endif
650 		} else {
651 			if (bio->bi_status) {
652 				/*
653 				 * Error correction failed; Just return error
654 				 */
655 				return -EIO;
656 			}
657 			if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
658 					      cur_block)) {
659 				dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
660 						 bio, cur_block, 0);
661 				return -EIO;
662 			}
663 		}
664 	}
665 
666 	return 0;
667 }
668 
669 /*
670  * Skip verity work in response to I/O error when system is shutting down.
671  */
verity_is_system_shutting_down(void)672 static inline bool verity_is_system_shutting_down(void)
673 {
674 	return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
675 		|| system_state == SYSTEM_RESTART;
676 }
677 
678 /*
679  * End one "io" structure with a given error.
680  */
verity_finish_io(struct dm_verity_io * io,blk_status_t status)681 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
682 {
683 	struct dm_verity *v = io->v;
684 	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
685 
686 	bio->bi_end_io = io->orig_bi_end_io;
687 	bio->bi_status = status;
688 
689 	if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
690 		verity_fec_finish_io(io);
691 
692 	bio_endio(bio);
693 }
694 
verity_work(struct work_struct * w)695 static void verity_work(struct work_struct *w)
696 {
697 	struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
698 
699 	io->in_tasklet = false;
700 
701 	verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
702 }
703 
verity_end_io(struct bio * bio)704 static void verity_end_io(struct bio *bio)
705 {
706 	struct dm_verity_io *io = bio->bi_private;
707 
708 	if (bio->bi_status &&
709 	    (!verity_fec_is_enabled(io->v) ||
710 	     verity_is_system_shutting_down() ||
711 	     (bio->bi_opf & REQ_RAHEAD))) {
712 		verity_finish_io(io, bio->bi_status);
713 		return;
714 	}
715 
716 	INIT_WORK(&io->work, verity_work);
717 	queue_work(io->v->verify_wq, &io->work);
718 }
719 
720 /*
721  * Prefetch buffers for the specified io.
722  * The root buffer is not prefetched, it is assumed that it will be cached
723  * all the time.
724  */
verity_prefetch_io(struct work_struct * work)725 static void verity_prefetch_io(struct work_struct *work)
726 {
727 	struct dm_verity_prefetch_work *pw =
728 		container_of(work, struct dm_verity_prefetch_work, work);
729 	struct dm_verity *v = pw->v;
730 	int i;
731 
732 	for (i = v->levels - 2; i >= 0; i--) {
733 		sector_t hash_block_start;
734 		sector_t hash_block_end;
735 
736 		verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
737 		verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
738 
739 		if (!i) {
740 			unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
741 
742 			cluster >>= v->data_dev_block_bits;
743 			if (unlikely(!cluster))
744 				goto no_prefetch_cluster;
745 
746 			if (unlikely(cluster & (cluster - 1)))
747 				cluster = 1 << __fls(cluster);
748 
749 			hash_block_start &= ~(sector_t)(cluster - 1);
750 			hash_block_end |= cluster - 1;
751 			if (unlikely(hash_block_end >= v->hash_blocks))
752 				hash_block_end = v->hash_blocks - 1;
753 		}
754 no_prefetch_cluster:
755 		dm_bufio_prefetch(v->bufio, hash_block_start,
756 				  hash_block_end - hash_block_start + 1);
757 	}
758 
759 	kfree(pw);
760 }
761 
verity_submit_prefetch(struct dm_verity * v,struct dm_verity_io * io)762 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
763 {
764 	sector_t block = io->block;
765 	unsigned int n_blocks = io->n_blocks;
766 	struct dm_verity_prefetch_work *pw;
767 
768 	if (v->validated_blocks) {
769 		while (n_blocks && test_bit(block, v->validated_blocks)) {
770 			block++;
771 			n_blocks--;
772 		}
773 		while (n_blocks && test_bit(block + n_blocks - 1,
774 					    v->validated_blocks))
775 			n_blocks--;
776 		if (!n_blocks)
777 			return;
778 	}
779 
780 	pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
781 		GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
782 
783 	if (!pw)
784 		return;
785 
786 	INIT_WORK(&pw->work, verity_prefetch_io);
787 	pw->v = v;
788 	pw->block = block;
789 	pw->n_blocks = n_blocks;
790 	queue_work(v->verify_wq, &pw->work);
791 }
792 
793 /*
794  * Bio map function. It allocates dm_verity_io structure and bio vector and
795  * fills them. Then it issues prefetches and the I/O.
796  */
verity_map(struct dm_target * ti,struct bio * bio)797 static int verity_map(struct dm_target *ti, struct bio *bio)
798 {
799 	struct dm_verity *v = ti->private;
800 	struct dm_verity_io *io;
801 
802 	bio_set_dev(bio, v->data_dev->bdev);
803 	bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
804 
805 	if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
806 	    ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
807 		DMERR_LIMIT("unaligned io");
808 		return DM_MAPIO_KILL;
809 	}
810 
811 	if (bio_end_sector(bio) >>
812 	    (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
813 		DMERR_LIMIT("io out of range");
814 		return DM_MAPIO_KILL;
815 	}
816 
817 	if (bio_data_dir(bio) == WRITE)
818 		return DM_MAPIO_KILL;
819 
820 	io = dm_per_bio_data(bio, ti->per_io_data_size);
821 	io->v = v;
822 	io->orig_bi_end_io = bio->bi_end_io;
823 	io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
824 	io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
825 
826 	bio->bi_end_io = verity_end_io;
827 	bio->bi_private = io;
828 	io->iter = bio->bi_iter;
829 
830 	verity_fec_init_io(io);
831 
832 	verity_submit_prefetch(v, io);
833 
834 	submit_bio_noacct(bio);
835 
836 	return DM_MAPIO_SUBMITTED;
837 }
838 
839 /*
840  * Status: V (valid) or C (corruption found)
841  */
verity_status(struct dm_target * ti,status_type_t type,unsigned int status_flags,char * result,unsigned int maxlen)842 static void verity_status(struct dm_target *ti, status_type_t type,
843 			  unsigned int status_flags, char *result, unsigned int maxlen)
844 {
845 	struct dm_verity *v = ti->private;
846 	unsigned int args = 0;
847 	unsigned int sz = 0;
848 	unsigned int x;
849 
850 	switch (type) {
851 	case STATUSTYPE_INFO:
852 		DMEMIT("%c", v->hash_failed ? 'C' : 'V');
853 		break;
854 	case STATUSTYPE_TABLE:
855 		DMEMIT("%u %s %s %u %u %llu %llu %s ",
856 			v->version,
857 			v->data_dev->name,
858 			v->hash_dev->name,
859 			1 << v->data_dev_block_bits,
860 			1 << v->hash_dev_block_bits,
861 			(unsigned long long)v->data_blocks,
862 			(unsigned long long)v->hash_start,
863 			v->alg_name
864 			);
865 		for (x = 0; x < v->digest_size; x++)
866 			DMEMIT("%02x", v->root_digest[x]);
867 		DMEMIT(" ");
868 		if (!v->salt_size)
869 			DMEMIT("-");
870 		else
871 			for (x = 0; x < v->salt_size; x++)
872 				DMEMIT("%02x", v->salt[x]);
873 		if (v->mode != DM_VERITY_MODE_EIO)
874 			args++;
875 		if (verity_fec_is_enabled(v))
876 			args += DM_VERITY_OPTS_FEC;
877 		if (v->zero_digest)
878 			args++;
879 		if (v->validated_blocks)
880 			args++;
881 		if (v->use_tasklet)
882 			args++;
883 		if (v->signature_key_desc)
884 			args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
885 		if (!args)
886 			return;
887 		DMEMIT(" %u", args);
888 		if (v->mode != DM_VERITY_MODE_EIO) {
889 			DMEMIT(" ");
890 			switch (v->mode) {
891 			case DM_VERITY_MODE_LOGGING:
892 				DMEMIT(DM_VERITY_OPT_LOGGING);
893 				break;
894 			case DM_VERITY_MODE_RESTART:
895 				DMEMIT(DM_VERITY_OPT_RESTART);
896 				break;
897 			case DM_VERITY_MODE_PANIC:
898 				DMEMIT(DM_VERITY_OPT_PANIC);
899 				break;
900 			default:
901 				BUG();
902 			}
903 		}
904 		if (v->zero_digest)
905 			DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
906 		if (v->validated_blocks)
907 			DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
908 		if (v->use_tasklet)
909 			DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
910 		sz = verity_fec_status_table(v, sz, result, maxlen);
911 		if (v->signature_key_desc)
912 			DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
913 				" %s", v->signature_key_desc);
914 		break;
915 
916 	case STATUSTYPE_IMA:
917 		DMEMIT_TARGET_NAME_VERSION(ti->type);
918 		DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
919 		DMEMIT(",verity_version=%u", v->version);
920 		DMEMIT(",data_device_name=%s", v->data_dev->name);
921 		DMEMIT(",hash_device_name=%s", v->hash_dev->name);
922 		DMEMIT(",verity_algorithm=%s", v->alg_name);
923 
924 		DMEMIT(",root_digest=");
925 		for (x = 0; x < v->digest_size; x++)
926 			DMEMIT("%02x", v->root_digest[x]);
927 
928 		DMEMIT(",salt=");
929 		if (!v->salt_size)
930 			DMEMIT("-");
931 		else
932 			for (x = 0; x < v->salt_size; x++)
933 				DMEMIT("%02x", v->salt[x]);
934 
935 		DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
936 		DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
937 		if (v->signature_key_desc)
938 			DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
939 
940 		if (v->mode != DM_VERITY_MODE_EIO) {
941 			DMEMIT(",verity_mode=");
942 			switch (v->mode) {
943 			case DM_VERITY_MODE_LOGGING:
944 				DMEMIT(DM_VERITY_OPT_LOGGING);
945 				break;
946 			case DM_VERITY_MODE_RESTART:
947 				DMEMIT(DM_VERITY_OPT_RESTART);
948 				break;
949 			case DM_VERITY_MODE_PANIC:
950 				DMEMIT(DM_VERITY_OPT_PANIC);
951 				break;
952 			default:
953 				DMEMIT("invalid");
954 			}
955 		}
956 		DMEMIT(";");
957 		break;
958 	}
959 }
960 
verity_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev)961 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
962 {
963 	struct dm_verity *v = ti->private;
964 
965 	*bdev = v->data_dev->bdev;
966 
967 	if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
968 		return 1;
969 	return 0;
970 }
971 
verity_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)972 static int verity_iterate_devices(struct dm_target *ti,
973 				  iterate_devices_callout_fn fn, void *data)
974 {
975 	struct dm_verity *v = ti->private;
976 
977 	return fn(ti, v->data_dev, v->data_start, ti->len, data);
978 }
979 
verity_io_hints(struct dm_target * ti,struct queue_limits * limits)980 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
981 {
982 	struct dm_verity *v = ti->private;
983 
984 	if (limits->logical_block_size < 1 << v->data_dev_block_bits)
985 		limits->logical_block_size = 1 << v->data_dev_block_bits;
986 
987 	if (limits->physical_block_size < 1 << v->data_dev_block_bits)
988 		limits->physical_block_size = 1 << v->data_dev_block_bits;
989 
990 	blk_limits_io_min(limits, limits->logical_block_size);
991 }
992 
verity_dtr(struct dm_target * ti)993 static void verity_dtr(struct dm_target *ti)
994 {
995 	struct dm_verity *v = ti->private;
996 
997 	if (v->verify_wq)
998 		destroy_workqueue(v->verify_wq);
999 
1000 	mempool_exit(&v->recheck_pool);
1001 	if (v->io)
1002 		dm_io_client_destroy(v->io);
1003 
1004 	if (v->bufio)
1005 		dm_bufio_client_destroy(v->bufio);
1006 
1007 	kvfree(v->validated_blocks);
1008 	kfree(v->salt);
1009 	kfree(v->root_digest);
1010 	kfree(v->zero_digest);
1011 
1012 	if (v->tfm)
1013 		crypto_free_ahash(v->tfm);
1014 
1015 	kfree(v->alg_name);
1016 
1017 	if (v->hash_dev)
1018 		dm_put_device(ti, v->hash_dev);
1019 
1020 	if (v->data_dev)
1021 		dm_put_device(ti, v->data_dev);
1022 
1023 	verity_fec_dtr(v);
1024 
1025 	kfree(v->signature_key_desc);
1026 
1027 	if (v->use_tasklet)
1028 		static_branch_dec(&use_tasklet_enabled);
1029 
1030 	kfree(v);
1031 
1032 	dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1033 }
1034 
verity_alloc_most_once(struct dm_verity * v)1035 static int verity_alloc_most_once(struct dm_verity *v)
1036 {
1037 	struct dm_target *ti = v->ti;
1038 
1039 	/* the bitset can only handle INT_MAX blocks */
1040 	if (v->data_blocks > INT_MAX) {
1041 		ti->error = "device too large to use check_at_most_once";
1042 		return -E2BIG;
1043 	}
1044 
1045 	v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1046 				       sizeof(unsigned long),
1047 				       GFP_KERNEL);
1048 	if (!v->validated_blocks) {
1049 		ti->error = "failed to allocate bitset for check_at_most_once";
1050 		return -ENOMEM;
1051 	}
1052 
1053 	return 0;
1054 }
1055 
verity_alloc_zero_digest(struct dm_verity * v)1056 static int verity_alloc_zero_digest(struct dm_verity *v)
1057 {
1058 	int r = -ENOMEM;
1059 	struct ahash_request *req;
1060 	u8 *zero_data;
1061 
1062 	v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1063 
1064 	if (!v->zero_digest)
1065 		return r;
1066 
1067 	req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1068 
1069 	if (!req)
1070 		return r; /* verity_dtr will free zero_digest */
1071 
1072 	zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1073 
1074 	if (!zero_data)
1075 		goto out;
1076 
1077 	r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1078 			v->zero_digest, true);
1079 
1080 out:
1081 	kfree(req);
1082 	kfree(zero_data);
1083 
1084 	return r;
1085 }
1086 
verity_is_verity_mode(const char * arg_name)1087 static inline bool verity_is_verity_mode(const char *arg_name)
1088 {
1089 	return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1090 		!strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1091 		!strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1092 }
1093 
verity_parse_verity_mode(struct dm_verity * v,const char * arg_name)1094 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1095 {
1096 	if (v->mode)
1097 		return -EINVAL;
1098 
1099 	if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1100 		v->mode = DM_VERITY_MODE_LOGGING;
1101 	else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1102 		v->mode = DM_VERITY_MODE_RESTART;
1103 	else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1104 		v->mode = DM_VERITY_MODE_PANIC;
1105 
1106 	return 0;
1107 }
1108 
verity_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,struct dm_verity_sig_opts * verify_args,bool only_modifier_opts)1109 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1110 				 struct dm_verity_sig_opts *verify_args,
1111 				 bool only_modifier_opts)
1112 {
1113 	int r = 0;
1114 	unsigned int argc;
1115 	struct dm_target *ti = v->ti;
1116 	const char *arg_name;
1117 
1118 	static const struct dm_arg _args[] = {
1119 		{0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1120 	};
1121 
1122 	r = dm_read_arg_group(_args, as, &argc, &ti->error);
1123 	if (r)
1124 		return -EINVAL;
1125 
1126 	if (!argc)
1127 		return 0;
1128 
1129 	do {
1130 		arg_name = dm_shift_arg(as);
1131 		argc--;
1132 
1133 		if (verity_is_verity_mode(arg_name)) {
1134 			if (only_modifier_opts)
1135 				continue;
1136 			r = verity_parse_verity_mode(v, arg_name);
1137 			if (r) {
1138 				ti->error = "Conflicting error handling parameters";
1139 				return r;
1140 			}
1141 			continue;
1142 
1143 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1144 			if (only_modifier_opts)
1145 				continue;
1146 			r = verity_alloc_zero_digest(v);
1147 			if (r) {
1148 				ti->error = "Cannot allocate zero digest";
1149 				return r;
1150 			}
1151 			continue;
1152 
1153 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1154 			if (only_modifier_opts)
1155 				continue;
1156 			r = verity_alloc_most_once(v);
1157 			if (r)
1158 				return r;
1159 			continue;
1160 
1161 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1162 			v->use_tasklet = true;
1163 			static_branch_inc(&use_tasklet_enabled);
1164 			continue;
1165 
1166 		} else if (verity_is_fec_opt_arg(arg_name)) {
1167 			if (only_modifier_opts)
1168 				continue;
1169 			r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1170 			if (r)
1171 				return r;
1172 			continue;
1173 
1174 		} else if (verity_verify_is_sig_opt_arg(arg_name)) {
1175 			if (only_modifier_opts)
1176 				continue;
1177 			r = verity_verify_sig_parse_opt_args(as, v,
1178 							     verify_args,
1179 							     &argc, arg_name);
1180 			if (r)
1181 				return r;
1182 			continue;
1183 
1184 		} else if (only_modifier_opts) {
1185 			/*
1186 			 * Ignore unrecognized opt, could easily be an extra
1187 			 * argument to an option whose parsing was skipped.
1188 			 * Normal parsing (@only_modifier_opts=false) will
1189 			 * properly parse all options (and their extra args).
1190 			 */
1191 			continue;
1192 		}
1193 
1194 		DMERR("Unrecognized verity feature request: %s", arg_name);
1195 		ti->error = "Unrecognized verity feature request";
1196 		return -EINVAL;
1197 	} while (argc && !r);
1198 
1199 	return r;
1200 }
1201 
1202 /*
1203  * Target parameters:
1204  *	<version>	The current format is version 1.
1205  *			Vsn 0 is compatible with original Chromium OS releases.
1206  *	<data device>
1207  *	<hash device>
1208  *	<data block size>
1209  *	<hash block size>
1210  *	<the number of data blocks>
1211  *	<hash start block>
1212  *	<algorithm>
1213  *	<digest>
1214  *	<salt>		Hex string or "-" if no salt.
1215  */
verity_ctr(struct dm_target * ti,unsigned int argc,char ** argv)1216 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1217 {
1218 	struct dm_verity *v;
1219 	struct dm_verity_sig_opts verify_args = {0};
1220 	struct dm_arg_set as;
1221 	unsigned int num;
1222 	unsigned long long num_ll;
1223 	int r;
1224 	int i;
1225 	sector_t hash_position;
1226 	char dummy;
1227 	char *root_hash_digest_to_validate;
1228 
1229 	v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1230 	if (!v) {
1231 		ti->error = "Cannot allocate verity structure";
1232 		return -ENOMEM;
1233 	}
1234 	ti->private = v;
1235 	v->ti = ti;
1236 
1237 	r = verity_fec_ctr_alloc(v);
1238 	if (r)
1239 		goto bad;
1240 
1241 	if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1242 		ti->error = "Device must be readonly";
1243 		r = -EINVAL;
1244 		goto bad;
1245 	}
1246 
1247 	if (argc < 10) {
1248 		ti->error = "Not enough arguments";
1249 		r = -EINVAL;
1250 		goto bad;
1251 	}
1252 
1253 	/* Parse optional parameters that modify primary args */
1254 	if (argc > 10) {
1255 		as.argc = argc - 10;
1256 		as.argv = argv + 10;
1257 		r = verity_parse_opt_args(&as, v, &verify_args, true);
1258 		if (r < 0)
1259 			goto bad;
1260 	}
1261 
1262 	if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1263 	    num > 1) {
1264 		ti->error = "Invalid version";
1265 		r = -EINVAL;
1266 		goto bad;
1267 	}
1268 	v->version = num;
1269 
1270 	r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1271 	if (r) {
1272 		ti->error = "Data device lookup failed";
1273 		goto bad;
1274 	}
1275 
1276 	r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1277 	if (r) {
1278 		ti->error = "Hash device lookup failed";
1279 		goto bad;
1280 	}
1281 
1282 	if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1283 	    !num || (num & (num - 1)) ||
1284 	    num < bdev_logical_block_size(v->data_dev->bdev) ||
1285 	    num > PAGE_SIZE) {
1286 		ti->error = "Invalid data device block size";
1287 		r = -EINVAL;
1288 		goto bad;
1289 	}
1290 	v->data_dev_block_bits = __ffs(num);
1291 
1292 	if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1293 	    !num || (num & (num - 1)) ||
1294 	    num < bdev_logical_block_size(v->hash_dev->bdev) ||
1295 	    num > INT_MAX) {
1296 		ti->error = "Invalid hash device block size";
1297 		r = -EINVAL;
1298 		goto bad;
1299 	}
1300 	v->hash_dev_block_bits = __ffs(num);
1301 
1302 	if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1303 	    (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1304 	    >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1305 		ti->error = "Invalid data blocks";
1306 		r = -EINVAL;
1307 		goto bad;
1308 	}
1309 	v->data_blocks = num_ll;
1310 
1311 	if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1312 		ti->error = "Data device is too small";
1313 		r = -EINVAL;
1314 		goto bad;
1315 	}
1316 
1317 	if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1318 	    (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1319 	    >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1320 		ti->error = "Invalid hash start";
1321 		r = -EINVAL;
1322 		goto bad;
1323 	}
1324 	v->hash_start = num_ll;
1325 
1326 	v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1327 	if (!v->alg_name) {
1328 		ti->error = "Cannot allocate algorithm name";
1329 		r = -ENOMEM;
1330 		goto bad;
1331 	}
1332 
1333 	v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1334 				    v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1335 	if (IS_ERR(v->tfm)) {
1336 		ti->error = "Cannot initialize hash function";
1337 		r = PTR_ERR(v->tfm);
1338 		v->tfm = NULL;
1339 		goto bad;
1340 	}
1341 
1342 	/*
1343 	 * dm-verity performance can vary greatly depending on which hash
1344 	 * algorithm implementation is used.  Help people debug performance
1345 	 * problems by logging the ->cra_driver_name.
1346 	 */
1347 	DMINFO("%s using implementation \"%s\"", v->alg_name,
1348 	       crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1349 
1350 	v->digest_size = crypto_ahash_digestsize(v->tfm);
1351 	if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1352 		ti->error = "Digest size too big";
1353 		r = -EINVAL;
1354 		goto bad;
1355 	}
1356 	v->ahash_reqsize = sizeof(struct ahash_request) +
1357 		crypto_ahash_reqsize(v->tfm);
1358 
1359 	v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1360 	if (!v->root_digest) {
1361 		ti->error = "Cannot allocate root digest";
1362 		r = -ENOMEM;
1363 		goto bad;
1364 	}
1365 	if (strlen(argv[8]) != v->digest_size * 2 ||
1366 	    hex2bin(v->root_digest, argv[8], v->digest_size)) {
1367 		ti->error = "Invalid root digest";
1368 		r = -EINVAL;
1369 		goto bad;
1370 	}
1371 	root_hash_digest_to_validate = argv[8];
1372 
1373 	if (strcmp(argv[9], "-")) {
1374 		v->salt_size = strlen(argv[9]) / 2;
1375 		v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1376 		if (!v->salt) {
1377 			ti->error = "Cannot allocate salt";
1378 			r = -ENOMEM;
1379 			goto bad;
1380 		}
1381 		if (strlen(argv[9]) != v->salt_size * 2 ||
1382 		    hex2bin(v->salt, argv[9], v->salt_size)) {
1383 			ti->error = "Invalid salt";
1384 			r = -EINVAL;
1385 			goto bad;
1386 		}
1387 	}
1388 
1389 	argv += 10;
1390 	argc -= 10;
1391 
1392 	/* Optional parameters */
1393 	if (argc) {
1394 		as.argc = argc;
1395 		as.argv = argv;
1396 		r = verity_parse_opt_args(&as, v, &verify_args, false);
1397 		if (r < 0)
1398 			goto bad;
1399 	}
1400 
1401 	/* Root hash signature is  a optional parameter*/
1402 	r = verity_verify_root_hash(root_hash_digest_to_validate,
1403 				    strlen(root_hash_digest_to_validate),
1404 				    verify_args.sig,
1405 				    verify_args.sig_size);
1406 	if (r < 0) {
1407 		ti->error = "Root hash verification failed";
1408 		goto bad;
1409 	}
1410 	v->hash_per_block_bits =
1411 		__fls((1 << v->hash_dev_block_bits) / v->digest_size);
1412 
1413 	v->levels = 0;
1414 	if (v->data_blocks)
1415 		while (v->hash_per_block_bits * v->levels < 64 &&
1416 		       (unsigned long long)(v->data_blocks - 1) >>
1417 		       (v->hash_per_block_bits * v->levels))
1418 			v->levels++;
1419 
1420 	if (v->levels > DM_VERITY_MAX_LEVELS) {
1421 		ti->error = "Too many tree levels";
1422 		r = -E2BIG;
1423 		goto bad;
1424 	}
1425 
1426 	hash_position = v->hash_start;
1427 	for (i = v->levels - 1; i >= 0; i--) {
1428 		sector_t s;
1429 
1430 		v->hash_level_block[i] = hash_position;
1431 		s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1432 					>> ((i + 1) * v->hash_per_block_bits);
1433 		if (hash_position + s < hash_position) {
1434 			ti->error = "Hash device offset overflow";
1435 			r = -E2BIG;
1436 			goto bad;
1437 		}
1438 		hash_position += s;
1439 	}
1440 	v->hash_blocks = hash_position;
1441 
1442 	r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1443 	if (unlikely(r)) {
1444 		ti->error = "Cannot allocate mempool";
1445 		goto bad;
1446 	}
1447 
1448 	v->io = dm_io_client_create();
1449 	if (IS_ERR(v->io)) {
1450 		r = PTR_ERR(v->io);
1451 		v->io = NULL;
1452 		ti->error = "Cannot allocate dm io";
1453 		goto bad;
1454 	}
1455 
1456 	v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1457 		1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1458 		dm_bufio_alloc_callback, NULL,
1459 		v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1460 	if (IS_ERR(v->bufio)) {
1461 		ti->error = "Cannot initialize dm-bufio";
1462 		r = PTR_ERR(v->bufio);
1463 		v->bufio = NULL;
1464 		goto bad;
1465 	}
1466 
1467 	if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1468 		ti->error = "Hash device is too small";
1469 		r = -E2BIG;
1470 		goto bad;
1471 	}
1472 
1473 	/*
1474 	 * Using WQ_HIGHPRI improves throughput and completion latency by
1475 	 * reducing wait times when reading from a dm-verity device.
1476 	 *
1477 	 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1478 	 * allows verify_wq to preempt softirq since verification in tasklet
1479 	 * will fall-back to using it for error handling (or if the bufio cache
1480 	 * doesn't have required hashes).
1481 	 */
1482 	v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1483 	if (!v->verify_wq) {
1484 		ti->error = "Cannot allocate workqueue";
1485 		r = -ENOMEM;
1486 		goto bad;
1487 	}
1488 
1489 	ti->per_io_data_size = sizeof(struct dm_verity_io) +
1490 				v->ahash_reqsize + v->digest_size * 2;
1491 
1492 	r = verity_fec_ctr(v);
1493 	if (r)
1494 		goto bad;
1495 
1496 	ti->per_io_data_size = roundup(ti->per_io_data_size,
1497 				       __alignof__(struct dm_verity_io));
1498 
1499 	verity_verify_sig_opts_cleanup(&verify_args);
1500 
1501 	dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1502 
1503 	return 0;
1504 
1505 bad:
1506 
1507 	verity_verify_sig_opts_cleanup(&verify_args);
1508 	dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1509 	verity_dtr(ti);
1510 
1511 	return r;
1512 }
1513 
1514 /*
1515  * Get the verity mode (error behavior) of a verity target.
1516  *
1517  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1518  * target.
1519  */
dm_verity_get_mode(struct dm_target * ti)1520 int dm_verity_get_mode(struct dm_target *ti)
1521 {
1522 	struct dm_verity *v = ti->private;
1523 
1524 	if (!dm_is_verity_target(ti))
1525 		return -EINVAL;
1526 
1527 	return v->mode;
1528 }
1529 
1530 /*
1531  * Get the root digest of a verity target.
1532  *
1533  * Returns a copy of the root digest, the caller is responsible for
1534  * freeing the memory of the digest.
1535  */
dm_verity_get_root_digest(struct dm_target * ti,u8 ** root_digest,unsigned int * digest_size)1536 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1537 {
1538 	struct dm_verity *v = ti->private;
1539 
1540 	if (!dm_is_verity_target(ti))
1541 		return -EINVAL;
1542 
1543 	*root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1544 	if (*root_digest == NULL)
1545 		return -ENOMEM;
1546 
1547 	*digest_size = v->digest_size;
1548 
1549 	return 0;
1550 }
1551 
1552 static struct target_type verity_target = {
1553 	.name		= "verity",
1554 	.features	= DM_TARGET_IMMUTABLE,
1555 	.version	= {1, 9, 0},
1556 	.module		= THIS_MODULE,
1557 	.ctr		= verity_ctr,
1558 	.dtr		= verity_dtr,
1559 	.map		= verity_map,
1560 	.status		= verity_status,
1561 	.prepare_ioctl	= verity_prepare_ioctl,
1562 	.iterate_devices = verity_iterate_devices,
1563 	.io_hints	= verity_io_hints,
1564 };
1565 module_dm(verity);
1566 
1567 /*
1568  * Check whether a DM target is a verity target.
1569  */
dm_is_verity_target(struct dm_target * ti)1570 bool dm_is_verity_target(struct dm_target *ti)
1571 {
1572 	return ti->type == &verity_target;
1573 }
1574 
1575 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1576 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1577 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1578 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1579 MODULE_LICENSE("GPL");
1580