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	*/
77	static void dm_bufio_alloc_callback(struct dm_buffer *buf)
78	{
79	struct buffer_aux *aux = dm_bufio_get_aux_data(b: buf);
80
81	aux->hash_verified = 0;
82	}
83
84	/*
85	* Translate input sector number to the sector number on the target device.
86	*/
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	*/
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
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, src: &sg, NULL, nbytes: len);
113	return crypto_wait_req(err: 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(vaddr: (void *)data, size: this_step);
121	sg_init_table(&sg, 1);
122	sg_set_page(sg: &sg, page: vmalloc_to_page(addr: data), len: this_step, offset_in_page(data));
123	ahash_request_set_crypt(req, src: &sg, NULL, nbytes: this_step);
124	r = crypto_wait_req(err: 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	*/
137	static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
138	struct crypto_wait *wait)
139	{
140	int r;
141
142	ahash_request_set_tfm(req, tfm: v->tfm);
143	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
144	CRYPTO_TFM_REQ_MAY_BACKLOG,
145	compl: crypto_req_done, data: (void *)wait);
146	crypto_init_wait(wait);
147
148	r = crypto_wait_req(err: crypto_ahash_init(req), wait);
149
150	if (unlikely(r < 0)) {
151	DMERR("crypto_ahash_init failed: %d", r);
152	return r;
153	}
154
155	if (likely(v->salt_size && (v->version >= 1)))
156	r = verity_hash_update(v, req, data: v->salt, len: v->salt_size, wait);
157
158	return r;
159	}
160
161	static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
162	u8 *digest, struct crypto_wait *wait)
163	{
164	int r;
165
166	if (unlikely(v->salt_size && (!v->version))) {
167	r = verity_hash_update(v, req, data: v->salt, len: v->salt_size, wait);
168
169	if (r < 0) {
170	DMERR("%s failed updating salt: %d", __func__, r);
171	goto out;
172	}
173	}
174
175	ahash_request_set_crypt(req, NULL, result: digest, nbytes: 0);
176	r = crypto_wait_req(err: crypto_ahash_final(req), wait);
177	out:
178	return r;
179	}
180
181	int verity_hash(struct dm_verity *v, struct ahash_request *req,
182	const u8 *data, size_t len, u8 *digest)
183	{
184	int r;
185	struct crypto_wait wait;
186
187	r = verity_hash_init(v, req, wait: &wait);
188	if (unlikely(r < 0))
189	goto out;
190
191	r = verity_hash_update(v, req, data, len, wait: &wait);
192	if (unlikely(r < 0))
193	goto out;
194
195	r = verity_hash_final(v, req, digest, wait: &wait);
196
197	out:
198	return r;
199	}
200
201	static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
202	sector_t *hash_block, unsigned int *offset)
203	{
204	sector_t position = verity_position_at_level(v, block, level);
205	unsigned int idx;
206
207	*hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
208
209	if (!offset)
210	return;
211
212	idx = position & ((1 << v->hash_per_block_bits) - 1);
213	if (!v->version)
214	*offset = idx * v->digest_size;
215	else
216	*offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
217	}
218
219	/*
220	* Handle verification errors.
221	*/
222	static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
223	unsigned long long block)
224	{
225	char verity_env[DM_VERITY_ENV_LENGTH];
226	char *envp[] = { verity_env, NULL };
227	const char *type_str = "";
228	struct mapped_device *md = dm_table_get_md(t: v->ti->table);
229
230	/* Corruption should be visible in device status in all modes */
231	v->hash_failed = true;
232
233	if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
234	goto out;
235
236	v->corrupted_errs++;
237
238	switch (type) {
239	case DM_VERITY_BLOCK_TYPE_DATA:
240	type_str = "data";
241	break;
242	case DM_VERITY_BLOCK_TYPE_METADATA:
243	type_str = "metadata";
244	break;
245	default:
246	BUG();
247	}
248
249	DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
250	type_str, block);
251
252	if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
253	DMERR("%s: reached maximum errors", v->data_dev->name);
254	dm_audit_log_target(DM_MSG_PREFIX, op: "max-corrupted-errors", ti: v->ti, result: 0);
255	}
256
257	snprintf(buf: verity_env, DM_VERITY_ENV_LENGTH, fmt: "%s=%d,%llu",
258	DM_VERITY_ENV_VAR_NAME, type, block);
259
260	kobject_uevent_env(kobj: &disk_to_dev(dm_disk(md))->kobj, action: KOBJ_CHANGE, envp);
261
262	out:
263	if (v->mode == DM_VERITY_MODE_LOGGING)
264	return 0;
265
266	if (v->mode == DM_VERITY_MODE_RESTART)
267	kernel_restart(cmd: "dm-verity device corrupted");
268
269	if (v->mode == DM_VERITY_MODE_PANIC)
270	panic(fmt: "dm-verity device corrupted");
271
272	return 1;
273	}
274
275	/*
276	* Verify hash of a metadata block pertaining to the specified data block
277	* ("block" argument) at a specified level ("level" argument).
278	*
279	* On successful return, verity_io_want_digest(v, io) contains the hash value
280	* for a lower tree level or for the data block (if we're at the lowest level).
281	*
282	* If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
283	* If "skip_unverified" is false, unverified buffer is hashed and verified
284	* against current value of verity_io_want_digest(v, io).
285	*/
286	static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
287	sector_t block, int level, bool skip_unverified,
288	u8 *want_digest)
289	{
290	struct dm_buffer *buf;
291	struct buffer_aux *aux;
292	u8 *data;
293	int r;
294	sector_t hash_block;
295	unsigned int offset;
296
297	verity_hash_at_level(v, block, level, hash_block: &hash_block, offset: &offset);
298
299	if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
300	data = dm_bufio_get(c: v->bufio, block: hash_block, bp: &buf);
301	if (data == NULL) {
302	/*
303	* In tasklet and the hash was not in the bufio cache.
304	* Return early and resume execution from a work-queue
305	* to read the hash from disk.
306	*/
307	return -EAGAIN;
308	}
309	} else
310	data = dm_bufio_read(c: v->bufio, block: hash_block, bp: &buf);
311
312	if (IS_ERR(ptr: data))
313	return PTR_ERR(ptr: data);
314
315	aux = dm_bufio_get_aux_data(b: buf);
316
317	if (!aux->hash_verified) {
318	if (skip_unverified) {
319	r = 1;
320	goto release_ret_r;
321	}
322
323	r = verity_hash(v, req: verity_io_hash_req(v, io),
324	data, len: 1 << v->hash_dev_block_bits,
325	digest: verity_io_real_digest(v, io));
326	if (unlikely(r < 0))
327	goto release_ret_r;
328
329	if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
330	v->digest_size) == 0))
331	aux->hash_verified = 1;
332	else if (static_branch_unlikely(&use_tasklet_enabled) &&
333	io->in_tasklet) {
334	/*
335	* Error handling code (FEC included) cannot be run in a
336	* tasklet since it may sleep, so fallback to work-queue.
337	*/
338	r = -EAGAIN;
339	goto release_ret_r;
340	} else if (verity_fec_decode(v, io, type: DM_VERITY_BLOCK_TYPE_METADATA,
341	block: hash_block, dest: data, NULL) == 0)
342	aux->hash_verified = 1;
343	else if (verity_handle_err(v,
344	type: DM_VERITY_BLOCK_TYPE_METADATA,
345	block: hash_block)) {
346	struct bio *bio =
347	dm_bio_from_per_bio_data(data: io,
348	data_size: v->ti->per_io_data_size);
349	dm_audit_log_bio(DM_MSG_PREFIX, op: "verify-metadata", bio,
350	sector: block, result: 0);
351	r = -EIO;
352	goto release_ret_r;
353	}
354	}
355
356	data += offset;
357	memcpy(want_digest, data, v->digest_size);
358	r = 0;
359
360	release_ret_r:
361	dm_bufio_release(b: buf);
362	return r;
363	}
364
365	/*
366	* Find a hash for a given block, write it to digest and verify the integrity
367	* of the hash tree if necessary.
368	*/
369	int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
370	sector_t block, u8 *digest, bool *is_zero)
371	{
372	int r = 0, i;
373
374	if (likely(v->levels)) {
375	/*
376	* First, we try to get the requested hash for
377	* the current block. If the hash block itself is
378	* verified, zero is returned. If it isn't, this
379	* function returns 1 and we fall back to whole
380	* chain verification.
381	*/
382	r = verity_verify_level(v, io, block, level: 0, skip_unverified: true, want_digest: digest);
383	if (likely(r <= 0))
384	goto out;
385	}
386
387	memcpy(digest, v->root_digest, v->digest_size);
388
389	for (i = v->levels - 1; i >= 0; i--) {
390	r = verity_verify_level(v, io, block, level: i, skip_unverified: false, want_digest: digest);
391	if (unlikely(r))
392	goto out;
393	}
394	out:
395	if (!r && v->zero_digest)
396	*is_zero = !memcmp(p: v->zero_digest, q: digest, size: v->digest_size);
397	else
398	*is_zero = false;
399
400	return r;
401	}
402
403	/*
404	* Calculates the digest for the given bio
405	*/
406	static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
407	struct bvec_iter *iter, struct crypto_wait *wait)
408	{
409	unsigned int todo = 1 << v->data_dev_block_bits;
410	struct bio *bio = dm_bio_from_per_bio_data(data: io, data_size: v->ti->per_io_data_size);
411	struct scatterlist sg;
412	struct ahash_request *req = verity_io_hash_req(v, io);
413
414	do {
415	int r;
416	unsigned int len;
417	struct bio_vec bv = bio_iter_iovec(bio, *iter);
418
419	sg_init_table(&sg, 1);
420
421	len = bv.bv_len;
422
423	if (likely(len >= todo))
424	len = todo;
425	/*
426	* Operating on a single page at a time looks suboptimal
427	* until you consider the typical block size is 4,096B.
428	* Going through this loops twice should be very rare.
429	*/
430	sg_set_page(sg: &sg, page: bv.bv_page, len, offset: bv.bv_offset);
431	ahash_request_set_crypt(req, src: &sg, NULL, nbytes: len);
432	r = crypto_wait_req(err: crypto_ahash_update(req), wait);
433
434	if (unlikely(r < 0)) {
435	DMERR("%s crypto op failed: %d", __func__, r);
436	return r;
437	}
438
439	bio_advance_iter(bio, iter, bytes: len);
440	todo -= len;
441	} while (todo);
442
443	return 0;
444	}
445
446	/*
447	* Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
448	* starting from iter.
449	*/
450	int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
451	struct bvec_iter *iter,
452	int (*process)(struct dm_verity *v,
453	struct dm_verity_io *io, u8 *data,
454	size_t len))
455	{
456	unsigned int todo = 1 << v->data_dev_block_bits;
457	struct bio *bio = dm_bio_from_per_bio_data(data: io, data_size: v->ti->per_io_data_size);
458
459	do {
460	int r;
461	u8 *page;
462	unsigned int len;
463	struct bio_vec bv = bio_iter_iovec(bio, *iter);
464
465	page = bvec_kmap_local(bvec: &bv);
466	len = bv.bv_len;
467
468	if (likely(len >= todo))
469	len = todo;
470
471	r = process(v, io, page, len);
472	kunmap_local(page);
473
474	if (r < 0)
475	return r;
476
477	bio_advance_iter(bio, iter, bytes: len);
478	todo -= len;
479	} while (todo);
480
481	return 0;
482	}
483
484	static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
485	u8 *data, size_t len)
486	{
487	memset(data, 0, len);
488	return 0;
489	}
490
491	/*
492	* Moves the bio iter one data block forward.
493	*/
494	static inline void verity_bv_skip_block(struct dm_verity *v,
495	struct dm_verity_io *io,
496	struct bvec_iter *iter)
497	{
498	struct bio *bio = dm_bio_from_per_bio_data(data: io, data_size: v->ti->per_io_data_size);
499
500	bio_advance_iter(bio, iter, bytes: 1 << v->data_dev_block_bits);
501	}
502
503	/*
504	* Verify one "dm_verity_io" structure.
505	*/
506	static int verity_verify_io(struct dm_verity_io *io)
507	{
508	bool is_zero;
509	struct dm_verity *v = io->v;
510	#if defined(CONFIG_DM_VERITY_FEC)
511	struct bvec_iter start;
512	#endif
513	struct bvec_iter iter_copy;
514	struct bvec_iter *iter;
515	struct crypto_wait wait;
516	struct bio *bio = dm_bio_from_per_bio_data(data: io, data_size: v->ti->per_io_data_size);
517	unsigned int b;
518
519	if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
520	/*
521	* Copy the iterator in case we need to restart
522	* verification in a work-queue.
523	*/
524	iter_copy = io->iter;
525	iter = &iter_copy;
526	} else
527	iter = &io->iter;
528
529	for (b = 0; b < io->n_blocks; b++) {
530	int r;
531	sector_t cur_block = io->block + b;
532	struct ahash_request *req = verity_io_hash_req(v, io);
533
534	if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
535	likely(test_bit(cur_block, v->validated_blocks))) {
536	verity_bv_skip_block(v, io, iter);
537	continue;
538	}
539
540	r = verity_hash_for_block(v, io, block: cur_block,
541	digest: verity_io_want_digest(v, io),
542	is_zero: &is_zero);
543	if (unlikely(r < 0))
544	return r;
545
546	if (is_zero) {
547	/*
548	* If we expect a zero block, don't validate, just
549	* return zeros.
550	*/
551	r = verity_for_bv_block(v, io, iter,
552	process: verity_bv_zero);
553	if (unlikely(r < 0))
554	return r;
555
556	continue;
557	}
558
559	r = verity_hash_init(v, req, wait: &wait);
560	if (unlikely(r < 0))
561	return r;
562
563	#if defined(CONFIG_DM_VERITY_FEC)
564	if (verity_fec_is_enabled(v))
565	start = *iter;
566	#endif
567	r = verity_for_io_block(v, io, iter, wait: &wait);
568	if (unlikely(r < 0))
569	return r;
570
571	r = verity_hash_final(v, req, digest: verity_io_real_digest(v, io),
572	wait: &wait);
573	if (unlikely(r < 0))
574	return r;
575
576	if (likely(memcmp(verity_io_real_digest(v, io),
577	verity_io_want_digest(v, io), v->digest_size) == 0)) {
578	if (v->validated_blocks)
579	set_bit(nr: cur_block, addr: v->validated_blocks);
580	continue;
581	} else if (static_branch_unlikely(&use_tasklet_enabled) &&
582	io->in_tasklet) {
583	/*
584	* Error handling code (FEC included) cannot be run in a
585	* tasklet since it may sleep, so fallback to work-queue.
586	*/
587	return -EAGAIN;
588	#if defined(CONFIG_DM_VERITY_FEC)
589	} else if (verity_fec_decode(v, io, type: DM_VERITY_BLOCK_TYPE_DATA,
590	block: cur_block, NULL, iter: &start) == 0) {
591	continue;
592	#endif
593	} else {
594	if (bio->bi_status) {
595	/*
596	* Error correction failed; Just return error
597	*/
598	return -EIO;
599	}
600	if (verity_handle_err(v, type: DM_VERITY_BLOCK_TYPE_DATA,
601	block: cur_block)) {
602	dm_audit_log_bio(DM_MSG_PREFIX, op: "verify-data",
603	bio, sector: cur_block, result: 0);
604	return -EIO;
605	}
606	}
607	}
608
609	return 0;
610	}
611
612	/*
613	* Skip verity work in response to I/O error when system is shutting down.
614	*/
615	static inline bool verity_is_system_shutting_down(void)
616	{
617	return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
618	|| system_state == SYSTEM_RESTART;
619	}
620
621	/*
622	* End one "io" structure with a given error.
623	*/
624	static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
625	{
626	struct dm_verity *v = io->v;
627	struct bio *bio = dm_bio_from_per_bio_data(data: io, data_size: v->ti->per_io_data_size);
628
629	bio->bi_end_io = io->orig_bi_end_io;
630	bio->bi_status = status;
631
632	if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
633	verity_fec_finish_io(io);
634
635	bio_endio(bio);
636	}
637
638	static void verity_work(struct work_struct *w)
639	{
640	struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
641
642	io->in_tasklet = false;
643
644	verity_fec_init_io(io);
645	verity_finish_io(io, status: errno_to_blk_status(errno: verity_verify_io(io)));
646	}
647
648	static void verity_tasklet(unsigned long data)
649	{
650	struct dm_verity_io *io = (struct dm_verity_io *)data;
651	int err;
652
653	io->in_tasklet = true;
654	err = verity_verify_io(io);
655	if (err == -EAGAIN) {
656	/* fallback to retrying with work-queue */
657	INIT_WORK(&io->work, verity_work);
658	queue_work(wq: io->v->verify_wq, work: &io->work);
659	return;
660	}
661
662	verity_finish_io(io, status: errno_to_blk_status(errno: err));
663	}
664
665	static void verity_end_io(struct bio *bio)
666	{
667	struct dm_verity_io *io = bio->bi_private;
668
669	if (bio->bi_status &&
670	(!verity_fec_is_enabled(v: io->v) || verity_is_system_shutting_down())) {
671	verity_finish_io(io, status: bio->bi_status);
672	return;
673	}
674
675	if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
676	tasklet_init(t: &io->tasklet, func: verity_tasklet, data: (unsigned long)io);
677	tasklet_schedule(t: &io->tasklet);
678	} else {
679	INIT_WORK(&io->work, verity_work);
680	queue_work(wq: io->v->verify_wq, work: &io->work);
681	}
682	}
683
684	/*
685	* Prefetch buffers for the specified io.
686	* The root buffer is not prefetched, it is assumed that it will be cached
687	* all the time.
688	*/
689	static void verity_prefetch_io(struct work_struct *work)
690	{
691	struct dm_verity_prefetch_work *pw =
692	container_of(work, struct dm_verity_prefetch_work, work);
693	struct dm_verity *v = pw->v;
694	int i;
695
696	for (i = v->levels - 2; i >= 0; i--) {
697	sector_t hash_block_start;
698	sector_t hash_block_end;
699
700	verity_hash_at_level(v, block: pw->block, level: i, hash_block: &hash_block_start, NULL);
701	verity_hash_at_level(v, block: pw->block + pw->n_blocks - 1, level: i, hash_block: &hash_block_end, NULL);
702
703	if (!i) {
704	unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
705
706	cluster >>= v->data_dev_block_bits;
707	if (unlikely(!cluster))
708	goto no_prefetch_cluster;
709
710	if (unlikely(cluster & (cluster - 1)))
711	cluster = 1 << __fls(word: cluster);
712
713	hash_block_start &= ~(sector_t)(cluster - 1);
714	hash_block_end |= cluster - 1;
715	if (unlikely(hash_block_end >= v->hash_blocks))
716	hash_block_end = v->hash_blocks - 1;
717	}
718	no_prefetch_cluster:
719	dm_bufio_prefetch(c: v->bufio, block: hash_block_start,
720	n_blocks: hash_block_end - hash_block_start + 1);
721	}
722
723	kfree(objp: pw);
724	}
725
726	static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
727	{
728	sector_t block = io->block;
729	unsigned int n_blocks = io->n_blocks;
730	struct dm_verity_prefetch_work *pw;
731
732	if (v->validated_blocks) {
733	while (n_blocks && test_bit(block, v->validated_blocks)) {
734	block++;
735	n_blocks--;
736	}
737	while (n_blocks && test_bit(block + n_blocks - 1,
738	v->validated_blocks))
739	n_blocks--;
740	if (!n_blocks)
741	return;
742	}
743
744	pw = kmalloc(size: sizeof(struct dm_verity_prefetch_work),
745	GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
746
747	if (!pw)
748	return;
749
750	INIT_WORK(&pw->work, verity_prefetch_io);
751	pw->v = v;
752	pw->block = block;
753	pw->n_blocks = n_blocks;
754	queue_work(wq: v->verify_wq, work: &pw->work);
755	}
756
757	/*
758	* Bio map function. It allocates dm_verity_io structure and bio vector and
759	* fills them. Then it issues prefetches and the I/O.
760	*/
761	static int verity_map(struct dm_target *ti, struct bio *bio)
762	{
763	struct dm_verity *v = ti->private;
764	struct dm_verity_io *io;
765
766	bio_set_dev(bio, bdev: v->data_dev->bdev);
767	bio->bi_iter.bi_sector = verity_map_sector(v, bi_sector: bio->bi_iter.bi_sector);
768
769	if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
770	((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
771	DMERR_LIMIT("unaligned io");
772	return DM_MAPIO_KILL;
773	}
774
775	if (bio_end_sector(bio) >>
776	(v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
777	DMERR_LIMIT("io out of range");
778	return DM_MAPIO_KILL;
779	}
780
781	if (bio_data_dir(bio) == WRITE)
782	return DM_MAPIO_KILL;
783
784	io = dm_per_bio_data(bio, data_size: ti->per_io_data_size);
785	io->v = v;
786	io->orig_bi_end_io = bio->bi_end_io;
787	io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
788	io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
789
790	bio->bi_end_io = verity_end_io;
791	bio->bi_private = io;
792	io->iter = bio->bi_iter;
793
794	verity_submit_prefetch(v, io);
795
796	submit_bio_noacct(bio);
797
798	return DM_MAPIO_SUBMITTED;
799	}
800
801	/*
802	* Status: V (valid) or C (corruption found)
803	*/
804	static void verity_status(struct dm_target *ti, status_type_t type,
805	unsigned int status_flags, char *result, unsigned int maxlen)
806	{
807	struct dm_verity *v = ti->private;
808	unsigned int args = 0;
809	unsigned int sz = 0;
810	unsigned int x;
811
812	switch (type) {
813	case STATUSTYPE_INFO:
814	DMEMIT("%c", v->hash_failed ? 'C' : 'V');
815	break;
816	case STATUSTYPE_TABLE:
817	DMEMIT("%u %s %s %u %u %llu %llu %s ",
818	v->version,
819	v->data_dev->name,
820	v->hash_dev->name,
821	1 << v->data_dev_block_bits,
822	1 << v->hash_dev_block_bits,
823	(unsigned long long)v->data_blocks,
824	(unsigned long long)v->hash_start,
825	v->alg_name
826	);
827	for (x = 0; x < v->digest_size; x++)
828	DMEMIT("%02x", v->root_digest[x]);
829	DMEMIT(" ");
830	if (!v->salt_size)
831	DMEMIT("-");
832	else
833	for (x = 0; x < v->salt_size; x++)
834	DMEMIT("%02x", v->salt[x]);
835	if (v->mode != DM_VERITY_MODE_EIO)
836	args++;
837	if (verity_fec_is_enabled(v))
838	args += DM_VERITY_OPTS_FEC;
839	if (v->zero_digest)
840	args++;
841	if (v->validated_blocks)
842	args++;
843	if (v->use_tasklet)
844	args++;
845	if (v->signature_key_desc)
846	args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
847	if (!args)
848	return;
849	DMEMIT(" %u", args);
850	if (v->mode != DM_VERITY_MODE_EIO) {
851	DMEMIT(" ");
852	switch (v->mode) {
853	case DM_VERITY_MODE_LOGGING:
854	DMEMIT(DM_VERITY_OPT_LOGGING);
855	break;
856	case DM_VERITY_MODE_RESTART:
857	DMEMIT(DM_VERITY_OPT_RESTART);
858	break;
859	case DM_VERITY_MODE_PANIC:
860	DMEMIT(DM_VERITY_OPT_PANIC);
861	break;
862	default:
863	BUG();
864	}
865	}
866	if (v->zero_digest)
867	DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
868	if (v->validated_blocks)
869	DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
870	if (v->use_tasklet)
871	DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
872	sz = verity_fec_status_table(v, sz, result, maxlen);
873	if (v->signature_key_desc)
874	DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
875	" %s", v->signature_key_desc);
876	break;
877
878	case STATUSTYPE_IMA:
879	DMEMIT_TARGET_NAME_VERSION(ti->type);
880	DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
881	DMEMIT(",verity_version=%u", v->version);
882	DMEMIT(",data_device_name=%s", v->data_dev->name);
883	DMEMIT(",hash_device_name=%s", v->hash_dev->name);
884	DMEMIT(",verity_algorithm=%s", v->alg_name);
885
886	DMEMIT(",root_digest=");
887	for (x = 0; x < v->digest_size; x++)
888	DMEMIT("%02x", v->root_digest[x]);
889
890	DMEMIT(",salt=");
891	if (!v->salt_size)
892	DMEMIT("-");
893	else
894	for (x = 0; x < v->salt_size; x++)
895	DMEMIT("%02x", v->salt[x]);
896
897	DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
898	DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
899	if (v->signature_key_desc)
900	DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
901
902	if (v->mode != DM_VERITY_MODE_EIO) {
903	DMEMIT(",verity_mode=");
904	switch (v->mode) {
905	case DM_VERITY_MODE_LOGGING:
906	DMEMIT(DM_VERITY_OPT_LOGGING);
907	break;
908	case DM_VERITY_MODE_RESTART:
909	DMEMIT(DM_VERITY_OPT_RESTART);
910	break;
911	case DM_VERITY_MODE_PANIC:
912	DMEMIT(DM_VERITY_OPT_PANIC);
913	break;
914	default:
915	DMEMIT("invalid");
916	}
917	}
918	DMEMIT(";");
919	break;
920	}
921	}
922
923	static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
924	{
925	struct dm_verity *v = ti->private;
926
927	*bdev = v->data_dev->bdev;
928
929	if (v->data_start || ti->len != bdev_nr_sectors(bdev: v->data_dev->bdev))
930	return 1;
931	return 0;
932	}
933
934	static int verity_iterate_devices(struct dm_target *ti,
935	iterate_devices_callout_fn fn, void *data)
936	{
937	struct dm_verity *v = ti->private;
938
939	return fn(ti, v->data_dev, v->data_start, ti->len, data);
940	}
941
942	static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
943	{
944	struct dm_verity *v = ti->private;
945
946	if (limits->logical_block_size < 1 << v->data_dev_block_bits)
947	limits->logical_block_size = 1 << v->data_dev_block_bits;
948
949	if (limits->physical_block_size < 1 << v->data_dev_block_bits)
950	limits->physical_block_size = 1 << v->data_dev_block_bits;
951
952	blk_limits_io_min(limits, min: limits->logical_block_size);
953	}
954
955	static void verity_dtr(struct dm_target *ti)
956	{
957	struct dm_verity *v = ti->private;
958
959	if (v->verify_wq)
960	destroy_workqueue(wq: v->verify_wq);
961
962	if (v->bufio)
963	dm_bufio_client_destroy(c: v->bufio);
964
965	kvfree(addr: v->validated_blocks);
966	kfree(objp: v->salt);
967	kfree(objp: v->root_digest);
968	kfree(objp: v->zero_digest);
969
970	if (v->tfm)
971	crypto_free_ahash(tfm: v->tfm);
972
973	kfree(objp: v->alg_name);
974
975	if (v->hash_dev)
976	dm_put_device(ti, d: v->hash_dev);
977
978	if (v->data_dev)
979	dm_put_device(ti, d: v->data_dev);
980
981	verity_fec_dtr(v);
982
983	kfree(objp: v->signature_key_desc);
984
985	if (v->use_tasklet)
986	static_branch_dec(&use_tasklet_enabled);
987
988	kfree(objp: v);
989
990	dm_audit_log_dtr(DM_MSG_PREFIX, ti, result: 1);
991	}
992
993	static int verity_alloc_most_once(struct dm_verity *v)
994	{
995	struct dm_target *ti = v->ti;
996
997	/* the bitset can only handle INT_MAX blocks */
998	if (v->data_blocks > INT_MAX) {
999	ti->error = "device too large to use check_at_most_once";
1000	return -E2BIG;
1001	}
1002
1003	v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1004	size: sizeof(unsigned long),
1005	GFP_KERNEL);
1006	if (!v->validated_blocks) {
1007	ti->error = "failed to allocate bitset for check_at_most_once";
1008	return -ENOMEM;
1009	}
1010
1011	return 0;
1012	}
1013
1014	static int verity_alloc_zero_digest(struct dm_verity *v)
1015	{
1016	int r = -ENOMEM;
1017	struct ahash_request *req;
1018	u8 *zero_data;
1019
1020	v->zero_digest = kmalloc(size: v->digest_size, GFP_KERNEL);
1021
1022	if (!v->zero_digest)
1023	return r;
1024
1025	req = kmalloc(size: v->ahash_reqsize, GFP_KERNEL);
1026
1027	if (!req)
1028	return r; /* verity_dtr will free zero_digest */
1029
1030	zero_data = kzalloc(size: 1 << v->data_dev_block_bits, GFP_KERNEL);
1031
1032	if (!zero_data)
1033	goto out;
1034
1035	r = verity_hash(v, req, data: zero_data, len: 1 << v->data_dev_block_bits,
1036	digest: v->zero_digest);
1037
1038	out:
1039	kfree(objp: req);
1040	kfree(objp: zero_data);
1041
1042	return r;
1043	}
1044
1045	static inline bool verity_is_verity_mode(const char *arg_name)
1046	{
1047	return (!strcasecmp(s1: arg_name, DM_VERITY_OPT_LOGGING) ||
1048	!strcasecmp(s1: arg_name, DM_VERITY_OPT_RESTART) ||
1049	!strcasecmp(s1: arg_name, DM_VERITY_OPT_PANIC));
1050	}
1051
1052	static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1053	{
1054	if (v->mode)
1055	return -EINVAL;
1056
1057	if (!strcasecmp(s1: arg_name, DM_VERITY_OPT_LOGGING))
1058	v->mode = DM_VERITY_MODE_LOGGING;
1059	else if (!strcasecmp(s1: arg_name, DM_VERITY_OPT_RESTART))
1060	v->mode = DM_VERITY_MODE_RESTART;
1061	else if (!strcasecmp(s1: arg_name, DM_VERITY_OPT_PANIC))
1062	v->mode = DM_VERITY_MODE_PANIC;
1063
1064	return 0;
1065	}
1066
1067	static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1068	struct dm_verity_sig_opts *verify_args,
1069	bool only_modifier_opts)
1070	{
1071	int r = 0;
1072	unsigned int argc;
1073	struct dm_target *ti = v->ti;
1074	const char *arg_name;
1075
1076	static const struct dm_arg _args[] = {
1077	{0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1078	};
1079
1080	r = dm_read_arg_group(arg: _args, arg_set: as, num_args: &argc, error: &ti->error);
1081	if (r)
1082	return -EINVAL;
1083
1084	if (!argc)
1085	return 0;
1086
1087	do {
1088	arg_name = dm_shift_arg(as);
1089	argc--;
1090
1091	if (verity_is_verity_mode(arg_name)) {
1092	if (only_modifier_opts)
1093	continue;
1094	r = verity_parse_verity_mode(v, arg_name);
1095	if (r) {
1096	ti->error = "Conflicting error handling parameters";
1097	return r;
1098	}
1099	continue;
1100
1101	} else if (!strcasecmp(s1: arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1102	if (only_modifier_opts)
1103	continue;
1104	r = verity_alloc_zero_digest(v);
1105	if (r) {
1106	ti->error = "Cannot allocate zero digest";
1107	return r;
1108	}
1109	continue;
1110
1111	} else if (!strcasecmp(s1: arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1112	if (only_modifier_opts)
1113	continue;
1114	r = verity_alloc_most_once(v);
1115	if (r)
1116	return r;
1117	continue;
1118
1119	} else if (!strcasecmp(s1: arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1120	v->use_tasklet = true;
1121	static_branch_inc(&use_tasklet_enabled);
1122	continue;
1123
1124	} else if (verity_is_fec_opt_arg(arg_name)) {
1125	if (only_modifier_opts)
1126	continue;
1127	r = verity_fec_parse_opt_args(as, v, argc: &argc, arg_name);
1128	if (r)
1129	return r;
1130	continue;
1131
1132	} else if (verity_verify_is_sig_opt_arg(arg_name)) {
1133	if (only_modifier_opts)
1134	continue;
1135	r = verity_verify_sig_parse_opt_args(as, v,
1136	sig_opts: verify_args,
1137	argc: &argc, arg_name);
1138	if (r)
1139	return r;
1140	continue;
1141
1142	} else if (only_modifier_opts) {
1143	/*
1144	* Ignore unrecognized opt, could easily be an extra
1145	* argument to an option whose parsing was skipped.
1146	* Normal parsing (@only_modifier_opts=false) will
1147	* properly parse all options (and their extra args).
1148	*/
1149	continue;
1150	}
1151
1152	DMERR("Unrecognized verity feature request: %s", arg_name);
1153	ti->error = "Unrecognized verity feature request";
1154	return -EINVAL;
1155	} while (argc && !r);
1156
1157	return r;
1158	}
1159
1160	/*
1161	* Target parameters:
1162	* <version> The current format is version 1.
1163	* Vsn 0 is compatible with original Chromium OS releases.
1164	* <data device>
1165	* <hash device>
1166	* <data block size>
1167	* <hash block size>
1168	* <the number of data blocks>
1169	* <hash start block>
1170	* <algorithm>
1171	* <digest>
1172	* <salt> Hex string or "-" if no salt.
1173	*/
1174	static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1175	{
1176	struct dm_verity *v;
1177	struct dm_verity_sig_opts verify_args = {0};
1178	struct dm_arg_set as;
1179	unsigned int num;
1180	unsigned long long num_ll;
1181	int r;
1182	int i;
1183	sector_t hash_position;
1184	char dummy;
1185	char *root_hash_digest_to_validate;
1186
1187	v = kzalloc(size: sizeof(struct dm_verity), GFP_KERNEL);
1188	if (!v) {
1189	ti->error = "Cannot allocate verity structure";
1190	return -ENOMEM;
1191	}
1192	ti->private = v;
1193	v->ti = ti;
1194
1195	r = verity_fec_ctr_alloc(v);
1196	if (r)
1197	goto bad;
1198
1199	if ((dm_table_get_mode(t: ti->table) & ~BLK_OPEN_READ)) {
1200	ti->error = "Device must be readonly";
1201	r = -EINVAL;
1202	goto bad;
1203	}
1204
1205	if (argc < 10) {
1206	ti->error = "Not enough arguments";
1207	r = -EINVAL;
1208	goto bad;
1209	}
1210
1211	/* Parse optional parameters that modify primary args */
1212	if (argc > 10) {
1213	as.argc = argc - 10;
1214	as.argv = argv + 10;
1215	r = verity_parse_opt_args(as: &as, v, verify_args: &verify_args, only_modifier_opts: true);
1216	if (r < 0)
1217	goto bad;
1218	}
1219
1220	if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1221	num > 1) {
1222	ti->error = "Invalid version";
1223	r = -EINVAL;
1224	goto bad;
1225	}
1226	v->version = num;
1227
1228	r = dm_get_device(ti, path: argv[1], BLK_OPEN_READ, result: &v->data_dev);
1229	if (r) {
1230	ti->error = "Data device lookup failed";
1231	goto bad;
1232	}
1233
1234	r = dm_get_device(ti, path: argv[2], BLK_OPEN_READ, result: &v->hash_dev);
1235	if (r) {
1236	ti->error = "Hash device lookup failed";
1237	goto bad;
1238	}
1239
1240	if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1241	!num || (num & (num - 1)) ||
1242	num < bdev_logical_block_size(bdev: v->data_dev->bdev) ||
1243	num > PAGE_SIZE) {
1244	ti->error = "Invalid data device block size";
1245	r = -EINVAL;
1246	goto bad;
1247	}
1248	v->data_dev_block_bits = __ffs(num);
1249
1250	if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1251	!num || (num & (num - 1)) ||
1252	num < bdev_logical_block_size(bdev: v->hash_dev->bdev) ||
1253	num > INT_MAX) {
1254	ti->error = "Invalid hash device block size";
1255	r = -EINVAL;
1256	goto bad;
1257	}
1258	v->hash_dev_block_bits = __ffs(num);
1259
1260	if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1261	(sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1262	>> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1263	ti->error = "Invalid data blocks";
1264	r = -EINVAL;
1265	goto bad;
1266	}
1267	v->data_blocks = num_ll;
1268
1269	if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1270	ti->error = "Data device is too small";
1271	r = -EINVAL;
1272	goto bad;
1273	}
1274
1275	if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1276	(sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1277	>> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1278	ti->error = "Invalid hash start";
1279	r = -EINVAL;
1280	goto bad;
1281	}
1282	v->hash_start = num_ll;
1283
1284	v->alg_name = kstrdup(s: argv[7], GFP_KERNEL);
1285	if (!v->alg_name) {
1286	ti->error = "Cannot allocate algorithm name";
1287	r = -ENOMEM;
1288	goto bad;
1289	}
1290
1291	v->tfm = crypto_alloc_ahash(alg_name: v->alg_name, type: 0,
1292	mask: v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1293	if (IS_ERR(ptr: v->tfm)) {
1294	ti->error = "Cannot initialize hash function";
1295	r = PTR_ERR(ptr: v->tfm);
1296	v->tfm = NULL;
1297	goto bad;
1298	}
1299
1300	/*
1301	* dm-verity performance can vary greatly depending on which hash
1302	* algorithm implementation is used. Help people debug performance
1303	* problems by logging the ->cra_driver_name.
1304	*/
1305	DMINFO("%s using implementation \"%s\"", v->alg_name,
1306	crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1307
1308	v->digest_size = crypto_ahash_digestsize(tfm: v->tfm);
1309	if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1310	ti->error = "Digest size too big";
1311	r = -EINVAL;
1312	goto bad;
1313	}
1314	v->ahash_reqsize = sizeof(struct ahash_request) +
1315	crypto_ahash_reqsize(tfm: v->tfm);
1316
1317	v->root_digest = kmalloc(size: v->digest_size, GFP_KERNEL);
1318	if (!v->root_digest) {
1319	ti->error = "Cannot allocate root digest";
1320	r = -ENOMEM;
1321	goto bad;
1322	}
1323	if (strlen(argv[8]) != v->digest_size * 2 ||
1324	hex2bin(dst: v->root_digest, src: argv[8], count: v->digest_size)) {
1325	ti->error = "Invalid root digest";
1326	r = -EINVAL;
1327	goto bad;
1328	}
1329	root_hash_digest_to_validate = argv[8];
1330
1331	if (strcmp(argv[9], "-")) {
1332	v->salt_size = strlen(argv[9]) / 2;
1333	v->salt = kmalloc(size: v->salt_size, GFP_KERNEL);
1334	if (!v->salt) {
1335	ti->error = "Cannot allocate salt";
1336	r = -ENOMEM;
1337	goto bad;
1338	}
1339	if (strlen(argv[9]) != v->salt_size * 2 ||
1340	hex2bin(dst: v->salt, src: argv[9], count: v->salt_size)) {
1341	ti->error = "Invalid salt";
1342	r = -EINVAL;
1343	goto bad;
1344	}
1345	}
1346
1347	argv += 10;
1348	argc -= 10;
1349
1350	/* Optional parameters */
1351	if (argc) {
1352	as.argc = argc;
1353	as.argv = argv;
1354	r = verity_parse_opt_args(as: &as, v, verify_args: &verify_args, only_modifier_opts: false);
1355	if (r < 0)
1356	goto bad;
1357	}
1358
1359	/* Root hash signature is a optional parameter*/
1360	r = verity_verify_root_hash(data: root_hash_digest_to_validate,
1361	strlen(root_hash_digest_to_validate),
1362	sig_data: verify_args.sig,
1363	sig_len: verify_args.sig_size);
1364	if (r < 0) {
1365	ti->error = "Root hash verification failed";
1366	goto bad;
1367	}
1368	v->hash_per_block_bits =
1369	__fls(word: (1 << v->hash_dev_block_bits) / v->digest_size);
1370
1371	v->levels = 0;
1372	if (v->data_blocks)
1373	while (v->hash_per_block_bits * v->levels < 64 &&
1374	(unsigned long long)(v->data_blocks - 1) >>
1375	(v->hash_per_block_bits * v->levels))
1376	v->levels++;
1377
1378	if (v->levels > DM_VERITY_MAX_LEVELS) {
1379	ti->error = "Too many tree levels";
1380	r = -E2BIG;
1381	goto bad;
1382	}
1383
1384	hash_position = v->hash_start;
1385	for (i = v->levels - 1; i >= 0; i--) {
1386	sector_t s;
1387
1388	v->hash_level_block[i] = hash_position;
1389	s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1390	>> ((i + 1) * v->hash_per_block_bits);
1391	if (hash_position + s < hash_position) {
1392	ti->error = "Hash device offset overflow";
1393	r = -E2BIG;
1394	goto bad;
1395	}
1396	hash_position += s;
1397	}
1398	v->hash_blocks = hash_position;
1399
1400	v->bufio = dm_bufio_client_create(bdev: v->hash_dev->bdev,
1401	block_size: 1 << v->hash_dev_block_bits, reserved_buffers: 1, aux_size: sizeof(struct buffer_aux),
1402	alloc_callback: dm_bufio_alloc_callback, NULL,
1403	flags: v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1404	if (IS_ERR(ptr: v->bufio)) {
1405	ti->error = "Cannot initialize dm-bufio";
1406	r = PTR_ERR(ptr: v->bufio);
1407	v->bufio = NULL;
1408	goto bad;
1409	}
1410
1411	if (dm_bufio_get_device_size(c: v->bufio) < v->hash_blocks) {
1412	ti->error = "Hash device is too small";
1413	r = -E2BIG;
1414	goto bad;
1415	}
1416
1417	/*
1418	* Using WQ_HIGHPRI improves throughput and completion latency by
1419	* reducing wait times when reading from a dm-verity device.
1420	*
1421	* Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1422	* allows verify_wq to preempt softirq since verification in tasklet
1423	* will fall-back to using it for error handling (or if the bufio cache
1424	* doesn't have required hashes).
1425	*/
1426	v->verify_wq = alloc_workqueue(fmt: "kverityd", flags: WQ_MEM_RECLAIM | WQ_HIGHPRI, max_active: 0);
1427	if (!v->verify_wq) {
1428	ti->error = "Cannot allocate workqueue";
1429	r = -ENOMEM;
1430	goto bad;
1431	}
1432
1433	ti->per_io_data_size = sizeof(struct dm_verity_io) +
1434	v->ahash_reqsize + v->digest_size * 2;
1435
1436	r = verity_fec_ctr(v);
1437	if (r)
1438	goto bad;
1439
1440	ti->per_io_data_size = roundup(ti->per_io_data_size,
1441	__alignof__(struct dm_verity_io));
1442
1443	verity_verify_sig_opts_cleanup(sig_opts: &verify_args);
1444
1445	dm_audit_log_ctr(DM_MSG_PREFIX, ti, result: 1);
1446
1447	return 0;
1448
1449	bad:
1450
1451	verity_verify_sig_opts_cleanup(sig_opts: &verify_args);
1452	dm_audit_log_ctr(DM_MSG_PREFIX, ti, result: 0);
1453	verity_dtr(ti);
1454
1455	return r;
1456	}
1457
1458	/*
1459	* Check whether a DM target is a verity target.
1460	*/
1461	bool dm_is_verity_target(struct dm_target *ti)
1462	{
1463	return ti->type->module == THIS_MODULE;
1464	}
1465
1466	/*
1467	* Get the verity mode (error behavior) of a verity target.
1468	*
1469	* Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1470	* target.
1471	*/
1472	int dm_verity_get_mode(struct dm_target *ti)
1473	{
1474	struct dm_verity *v = ti->private;
1475
1476	if (!dm_is_verity_target(ti))
1477	return -EINVAL;
1478
1479	return v->mode;
1480	}
1481
1482	/*
1483	* Get the root digest of a verity target.
1484	*
1485	* Returns a copy of the root digest, the caller is responsible for
1486	* freeing the memory of the digest.
1487	*/
1488	int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1489	{
1490	struct dm_verity *v = ti->private;
1491
1492	if (!dm_is_verity_target(ti))
1493	return -EINVAL;
1494
1495	*root_digest = kmemdup(p: v->root_digest, size: v->digest_size, GFP_KERNEL);
1496	if (*root_digest == NULL)
1497	return -ENOMEM;
1498
1499	*digest_size = v->digest_size;
1500
1501	return 0;
1502	}
1503
1504	static struct target_type verity_target = {
1505	.name = "verity",
1506	.features = DM_TARGET_IMMUTABLE,
1507	.version = {1, 9, 0},
1508	.module = THIS_MODULE,
1509	.ctr = verity_ctr,
1510	.dtr = verity_dtr,
1511	.map = verity_map,
1512	.status = verity_status,
1513	.prepare_ioctl = verity_prepare_ioctl,
1514	.iterate_devices = verity_iterate_devices,
1515	.io_hints = verity_io_hints,
1516	};
1517	module_dm(verity);
1518
1519	MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1520	MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1521	MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1522	MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1523	MODULE_LICENSE("GPL");
1524