Root/drivers/md/dm-verity.c

1/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
7 *
8 * This file is released under the GPLv2.
9 *
10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
12 * hash device. Setting this greatly improves performance when data and hash
13 * are on the same disk on different partitions on devices with poor random
14 * access behavior.
15 */
16
17#include "dm-bufio.h"
18
19#include <linux/module.h>
20#include <linux/device-mapper.h>
21#include <crypto/hash.h>
22
23#define DM_MSG_PREFIX "verity"
24
25#define DM_VERITY_IO_VEC_INLINE 16
26#define DM_VERITY_MEMPOOL_SIZE 4
27#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
28
29#define DM_VERITY_MAX_LEVELS 63
30
31static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
32
33module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
34
35struct dm_verity {
36    struct dm_dev *data_dev;
37    struct dm_dev *hash_dev;
38    struct dm_target *ti;
39    struct dm_bufio_client *bufio;
40    char *alg_name;
41    struct crypto_shash *tfm;
42    u8 *root_digest; /* digest of the root block */
43    u8 *salt; /* salt: its size is salt_size */
44    unsigned salt_size;
45    sector_t data_start; /* data offset in 512-byte sectors */
46    sector_t hash_start; /* hash start in blocks */
47    sector_t data_blocks; /* the number of data blocks */
48    sector_t hash_blocks; /* the number of hash blocks */
49    unsigned char data_dev_block_bits; /* log2(data blocksize) */
50    unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
51    unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
52    unsigned char levels; /* the number of tree levels */
53    unsigned char version;
54    unsigned digest_size; /* digest size for the current hash algorithm */
55    unsigned shash_descsize;/* the size of temporary space for crypto */
56    int hash_failed; /* set to 1 if hash of any block failed */
57
58    mempool_t *vec_mempool; /* mempool of bio vector */
59
60    struct workqueue_struct *verify_wq;
61
62    /* starting blocks for each tree level. 0 is the lowest level. */
63    sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
64};
65
66struct dm_verity_io {
67    struct dm_verity *v;
68
69    /* original values of bio->bi_end_io and bio->bi_private */
70    bio_end_io_t *orig_bi_end_io;
71    void *orig_bi_private;
72
73    sector_t block;
74    unsigned n_blocks;
75
76    /* saved bio vector */
77    struct bio_vec *io_vec;
78    unsigned io_vec_size;
79
80    struct work_struct work;
81
82    /* A space for short vectors; longer vectors are allocated separately. */
83    struct bio_vec io_vec_inline[DM_VERITY_IO_VEC_INLINE];
84
85    /*
86     * Three variably-size fields follow this struct:
87     *
88     * u8 hash_desc[v->shash_descsize];
89     * u8 real_digest[v->digest_size];
90     * u8 want_digest[v->digest_size];
91     *
92     * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
93     */
94};
95
96struct dm_verity_prefetch_work {
97    struct work_struct work;
98    struct dm_verity *v;
99    sector_t block;
100    unsigned n_blocks;
101};
102
103static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
104{
105    return (struct shash_desc *)(io + 1);
106}
107
108static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
109{
110    return (u8 *)(io + 1) + v->shash_descsize;
111}
112
113static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
114{
115    return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
116}
117
118/*
119 * Auxiliary structure appended to each dm-bufio buffer. If the value
120 * hash_verified is nonzero, hash of the block has been verified.
121 *
122 * The variable hash_verified is set to 0 when allocating the buffer, then
123 * it can be changed to 1 and it is never reset to 0 again.
124 *
125 * There is no lock around this value, a race condition can at worst cause
126 * that multiple processes verify the hash of the same buffer simultaneously
127 * and write 1 to hash_verified simultaneously.
128 * This condition is harmless, so we don't need locking.
129 */
130struct buffer_aux {
131    int hash_verified;
132};
133
134/*
135 * Initialize struct buffer_aux for a freshly created buffer.
136 */
137static void dm_bufio_alloc_callback(struct dm_buffer *buf)
138{
139    struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
140
141    aux->hash_verified = 0;
142}
143
144/*
145 * Translate input sector number to the sector number on the target device.
146 */
147static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
148{
149    return v->data_start + dm_target_offset(v->ti, bi_sector);
150}
151
152/*
153 * Return hash position of a specified block at a specified tree level
154 * (0 is the lowest level).
155 * The lowest "hash_per_block_bits"-bits of the result denote hash position
156 * inside a hash block. The remaining bits denote location of the hash block.
157 */
158static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
159                     int level)
160{
161    return block >> (level * v->hash_per_block_bits);
162}
163
164static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
165                 sector_t *hash_block, unsigned *offset)
166{
167    sector_t position = verity_position_at_level(v, block, level);
168    unsigned idx;
169
170    *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
171
172    if (!offset)
173        return;
174
175    idx = position & ((1 << v->hash_per_block_bits) - 1);
176    if (!v->version)
177        *offset = idx * v->digest_size;
178    else
179        *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
180}
181
182/*
183 * Verify hash of a metadata block pertaining to the specified data block
184 * ("block" argument) at a specified level ("level" argument).
185 *
186 * On successful return, io_want_digest(v, io) contains the hash value for
187 * a lower tree level or for the data block (if we're at the lowest leve).
188 *
189 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
190 * If "skip_unverified" is false, unverified buffer is hashed and verified
191 * against current value of io_want_digest(v, io).
192 */
193static int verity_verify_level(struct dm_verity_io *io, sector_t block,
194                   int level, bool skip_unverified)
195{
196    struct dm_verity *v = io->v;
197    struct dm_buffer *buf;
198    struct buffer_aux *aux;
199    u8 *data;
200    int r;
201    sector_t hash_block;
202    unsigned offset;
203
204    verity_hash_at_level(v, block, level, &hash_block, &offset);
205
206    data = dm_bufio_read(v->bufio, hash_block, &buf);
207    if (unlikely(IS_ERR(data)))
208        return PTR_ERR(data);
209
210    aux = dm_bufio_get_aux_data(buf);
211
212    if (!aux->hash_verified) {
213        struct shash_desc *desc;
214        u8 *result;
215
216        if (skip_unverified) {
217            r = 1;
218            goto release_ret_r;
219        }
220
221        desc = io_hash_desc(v, io);
222        desc->tfm = v->tfm;
223        desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
224        r = crypto_shash_init(desc);
225        if (r < 0) {
226            DMERR("crypto_shash_init failed: %d", r);
227            goto release_ret_r;
228        }
229
230        if (likely(v->version >= 1)) {
231            r = crypto_shash_update(desc, v->salt, v->salt_size);
232            if (r < 0) {
233                DMERR("crypto_shash_update failed: %d", r);
234                goto release_ret_r;
235            }
236        }
237
238        r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
239        if (r < 0) {
240            DMERR("crypto_shash_update failed: %d", r);
241            goto release_ret_r;
242        }
243
244        if (!v->version) {
245            r = crypto_shash_update(desc, v->salt, v->salt_size);
246            if (r < 0) {
247                DMERR("crypto_shash_update failed: %d", r);
248                goto release_ret_r;
249            }
250        }
251
252        result = io_real_digest(v, io);
253        r = crypto_shash_final(desc, result);
254        if (r < 0) {
255            DMERR("crypto_shash_final failed: %d", r);
256            goto release_ret_r;
257        }
258        if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
259            DMERR_LIMIT("metadata block %llu is corrupted",
260                (unsigned long long)hash_block);
261            v->hash_failed = 1;
262            r = -EIO;
263            goto release_ret_r;
264        } else
265            aux->hash_verified = 1;
266    }
267
268    data += offset;
269
270    memcpy(io_want_digest(v, io), data, v->digest_size);
271
272    dm_bufio_release(buf);
273    return 0;
274
275release_ret_r:
276    dm_bufio_release(buf);
277
278    return r;
279}
280
281/*
282 * Verify one "dm_verity_io" structure.
283 */
284static int verity_verify_io(struct dm_verity_io *io)
285{
286    struct dm_verity *v = io->v;
287    unsigned b;
288    int i;
289    unsigned vector = 0, offset = 0;
290
291    for (b = 0; b < io->n_blocks; b++) {
292        struct shash_desc *desc;
293        u8 *result;
294        int r;
295        unsigned todo;
296
297        if (likely(v->levels)) {
298            /*
299             * First, we try to get the requested hash for
300             * the current block. If the hash block itself is
301             * verified, zero is returned. If it isn't, this
302             * function returns 0 and we fall back to whole
303             * chain verification.
304             */
305            int r = verity_verify_level(io, io->block + b, 0, true);
306            if (likely(!r))
307                goto test_block_hash;
308            if (r < 0)
309                return r;
310        }
311
312        memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
313
314        for (i = v->levels - 1; i >= 0; i--) {
315            int r = verity_verify_level(io, io->block + b, i, false);
316            if (unlikely(r))
317                return r;
318        }
319
320test_block_hash:
321        desc = io_hash_desc(v, io);
322        desc->tfm = v->tfm;
323        desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
324        r = crypto_shash_init(desc);
325        if (r < 0) {
326            DMERR("crypto_shash_init failed: %d", r);
327            return r;
328        }
329
330        if (likely(v->version >= 1)) {
331            r = crypto_shash_update(desc, v->salt, v->salt_size);
332            if (r < 0) {
333                DMERR("crypto_shash_update failed: %d", r);
334                return r;
335            }
336        }
337
338        todo = 1 << v->data_dev_block_bits;
339        do {
340            struct bio_vec *bv;
341            u8 *page;
342            unsigned len;
343
344            BUG_ON(vector >= io->io_vec_size);
345            bv = &io->io_vec[vector];
346            page = kmap_atomic(bv->bv_page);
347            len = bv->bv_len - offset;
348            if (likely(len >= todo))
349                len = todo;
350            r = crypto_shash_update(desc,
351                    page + bv->bv_offset + offset, len);
352            kunmap_atomic(page);
353            if (r < 0) {
354                DMERR("crypto_shash_update failed: %d", r);
355                return r;
356            }
357            offset += len;
358            if (likely(offset == bv->bv_len)) {
359                offset = 0;
360                vector++;
361            }
362            todo -= len;
363        } while (todo);
364
365        if (!v->version) {
366            r = crypto_shash_update(desc, v->salt, v->salt_size);
367            if (r < 0) {
368                DMERR("crypto_shash_update failed: %d", r);
369                return r;
370            }
371        }
372
373        result = io_real_digest(v, io);
374        r = crypto_shash_final(desc, result);
375        if (r < 0) {
376            DMERR("crypto_shash_final failed: %d", r);
377            return r;
378        }
379        if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
380            DMERR_LIMIT("data block %llu is corrupted",
381                (unsigned long long)(io->block + b));
382            v->hash_failed = 1;
383            return -EIO;
384        }
385    }
386    BUG_ON(vector != io->io_vec_size);
387    BUG_ON(offset);
388
389    return 0;
390}
391
392/*
393 * End one "io" structure with a given error.
394 */
395static void verity_finish_io(struct dm_verity_io *io, int error)
396{
397    struct dm_verity *v = io->v;
398    struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
399
400    bio->bi_end_io = io->orig_bi_end_io;
401    bio->bi_private = io->orig_bi_private;
402
403    if (io->io_vec != io->io_vec_inline)
404        mempool_free(io->io_vec, v->vec_mempool);
405
406    bio_endio(bio, error);
407}
408
409static void verity_work(struct work_struct *w)
410{
411    struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
412
413    verity_finish_io(io, verity_verify_io(io));
414}
415
416static void verity_end_io(struct bio *bio, int error)
417{
418    struct dm_verity_io *io = bio->bi_private;
419
420    if (error) {
421        verity_finish_io(io, error);
422        return;
423    }
424
425    INIT_WORK(&io->work, verity_work);
426    queue_work(io->v->verify_wq, &io->work);
427}
428
429/*
430 * Prefetch buffers for the specified io.
431 * The root buffer is not prefetched, it is assumed that it will be cached
432 * all the time.
433 */
434static void verity_prefetch_io(struct work_struct *work)
435{
436    struct dm_verity_prefetch_work *pw =
437        container_of(work, struct dm_verity_prefetch_work, work);
438    struct dm_verity *v = pw->v;
439    int i;
440
441    for (i = v->levels - 2; i >= 0; i--) {
442        sector_t hash_block_start;
443        sector_t hash_block_end;
444        verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
445        verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
446        if (!i) {
447            unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
448
449            cluster >>= v->data_dev_block_bits;
450            if (unlikely(!cluster))
451                goto no_prefetch_cluster;
452
453            if (unlikely(cluster & (cluster - 1)))
454                cluster = 1 << (fls(cluster) - 1);
455
456            hash_block_start &= ~(sector_t)(cluster - 1);
457            hash_block_end |= cluster - 1;
458            if (unlikely(hash_block_end >= v->hash_blocks))
459                hash_block_end = v->hash_blocks - 1;
460        }
461no_prefetch_cluster:
462        dm_bufio_prefetch(v->bufio, hash_block_start,
463                  hash_block_end - hash_block_start + 1);
464    }
465
466    kfree(pw);
467}
468
469static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
470{
471    struct dm_verity_prefetch_work *pw;
472
473    pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
474        GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
475
476    if (!pw)
477        return;
478
479    INIT_WORK(&pw->work, verity_prefetch_io);
480    pw->v = v;
481    pw->block = io->block;
482    pw->n_blocks = io->n_blocks;
483    queue_work(v->verify_wq, &pw->work);
484}
485
486/*
487 * Bio map function. It allocates dm_verity_io structure and bio vector and
488 * fills them. Then it issues prefetches and the I/O.
489 */
490static int verity_map(struct dm_target *ti, struct bio *bio)
491{
492    struct dm_verity *v = ti->private;
493    struct dm_verity_io *io;
494
495    bio->bi_bdev = v->data_dev->bdev;
496    bio->bi_sector = verity_map_sector(v, bio->bi_sector);
497
498    if (((unsigned)bio->bi_sector | bio_sectors(bio)) &
499        ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
500        DMERR_LIMIT("unaligned io");
501        return -EIO;
502    }
503
504    if ((bio->bi_sector + bio_sectors(bio)) >>
505        (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
506        DMERR_LIMIT("io out of range");
507        return -EIO;
508    }
509
510    if (bio_data_dir(bio) == WRITE)
511        return -EIO;
512
513    io = dm_per_bio_data(bio, ti->per_bio_data_size);
514    io->v = v;
515    io->orig_bi_end_io = bio->bi_end_io;
516    io->orig_bi_private = bio->bi_private;
517    io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
518    io->n_blocks = bio->bi_size >> v->data_dev_block_bits;
519
520    bio->bi_end_io = verity_end_io;
521    bio->bi_private = io;
522    io->io_vec_size = bio->bi_vcnt - bio->bi_idx;
523    if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE)
524        io->io_vec = io->io_vec_inline;
525    else
526        io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO);
527    memcpy(io->io_vec, bio_iovec(bio),
528           io->io_vec_size * sizeof(struct bio_vec));
529
530    verity_submit_prefetch(v, io);
531
532    generic_make_request(bio);
533
534    return DM_MAPIO_SUBMITTED;
535}
536
537/*
538 * Status: V (valid) or C (corruption found)
539 */
540static void verity_status(struct dm_target *ti, status_type_t type,
541              unsigned status_flags, char *result, unsigned maxlen)
542{
543    struct dm_verity *v = ti->private;
544    unsigned sz = 0;
545    unsigned x;
546
547    switch (type) {
548    case STATUSTYPE_INFO:
549        DMEMIT("%c", v->hash_failed ? 'C' : 'V');
550        break;
551    case STATUSTYPE_TABLE:
552        DMEMIT("%u %s %s %u %u %llu %llu %s ",
553            v->version,
554            v->data_dev->name,
555            v->hash_dev->name,
556            1 << v->data_dev_block_bits,
557            1 << v->hash_dev_block_bits,
558            (unsigned long long)v->data_blocks,
559            (unsigned long long)v->hash_start,
560            v->alg_name
561            );
562        for (x = 0; x < v->digest_size; x++)
563            DMEMIT("%02x", v->root_digest[x]);
564        DMEMIT(" ");
565        if (!v->salt_size)
566            DMEMIT("-");
567        else
568            for (x = 0; x < v->salt_size; x++)
569                DMEMIT("%02x", v->salt[x]);
570        break;
571    }
572}
573
574static int verity_ioctl(struct dm_target *ti, unsigned cmd,
575            unsigned long arg)
576{
577    struct dm_verity *v = ti->private;
578    int r = 0;
579
580    if (v->data_start ||
581        ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
582        r = scsi_verify_blk_ioctl(NULL, cmd);
583
584    return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
585                     cmd, arg);
586}
587
588static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
589            struct bio_vec *biovec, int max_size)
590{
591    struct dm_verity *v = ti->private;
592    struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
593
594    if (!q->merge_bvec_fn)
595        return max_size;
596
597    bvm->bi_bdev = v->data_dev->bdev;
598    bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
599
600    return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
601}
602
603static int verity_iterate_devices(struct dm_target *ti,
604                  iterate_devices_callout_fn fn, void *data)
605{
606    struct dm_verity *v = ti->private;
607
608    return fn(ti, v->data_dev, v->data_start, ti->len, data);
609}
610
611static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
612{
613    struct dm_verity *v = ti->private;
614
615    if (limits->logical_block_size < 1 << v->data_dev_block_bits)
616        limits->logical_block_size = 1 << v->data_dev_block_bits;
617
618    if (limits->physical_block_size < 1 << v->data_dev_block_bits)
619        limits->physical_block_size = 1 << v->data_dev_block_bits;
620
621    blk_limits_io_min(limits, limits->logical_block_size);
622}
623
624static void verity_dtr(struct dm_target *ti)
625{
626    struct dm_verity *v = ti->private;
627
628    if (v->verify_wq)
629        destroy_workqueue(v->verify_wq);
630
631    if (v->vec_mempool)
632        mempool_destroy(v->vec_mempool);
633
634    if (v->bufio)
635        dm_bufio_client_destroy(v->bufio);
636
637    kfree(v->salt);
638    kfree(v->root_digest);
639
640    if (v->tfm)
641        crypto_free_shash(v->tfm);
642
643    kfree(v->alg_name);
644
645    if (v->hash_dev)
646        dm_put_device(ti, v->hash_dev);
647
648    if (v->data_dev)
649        dm_put_device(ti, v->data_dev);
650
651    kfree(v);
652}
653
654/*
655 * Target parameters:
656 * <version> The current format is version 1.
657 * Vsn 0 is compatible with original Chromium OS releases.
658 * <data device>
659 * <hash device>
660 * <data block size>
661 * <hash block size>
662 * <the number of data blocks>
663 * <hash start block>
664 * <algorithm>
665 * <digest>
666 * <salt> Hex string or "-" if no salt.
667 */
668static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
669{
670    struct dm_verity *v;
671    unsigned num;
672    unsigned long long num_ll;
673    int r;
674    int i;
675    sector_t hash_position;
676    char dummy;
677
678    v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
679    if (!v) {
680        ti->error = "Cannot allocate verity structure";
681        return -ENOMEM;
682    }
683    ti->private = v;
684    v->ti = ti;
685
686    if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
687        ti->error = "Device must be readonly";
688        r = -EINVAL;
689        goto bad;
690    }
691
692    if (argc != 10) {
693        ti->error = "Invalid argument count: exactly 10 arguments required";
694        r = -EINVAL;
695        goto bad;
696    }
697
698    if (sscanf(argv[0], "%d%c", &num, &dummy) != 1 ||
699        num < 0 || num > 1) {
700        ti->error = "Invalid version";
701        r = -EINVAL;
702        goto bad;
703    }
704    v->version = num;
705
706    r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
707    if (r) {
708        ti->error = "Data device lookup failed";
709        goto bad;
710    }
711
712    r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
713    if (r) {
714        ti->error = "Data device lookup failed";
715        goto bad;
716    }
717
718    if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
719        !num || (num & (num - 1)) ||
720        num < bdev_logical_block_size(v->data_dev->bdev) ||
721        num > PAGE_SIZE) {
722        ti->error = "Invalid data device block size";
723        r = -EINVAL;
724        goto bad;
725    }
726    v->data_dev_block_bits = ffs(num) - 1;
727
728    if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
729        !num || (num & (num - 1)) ||
730        num < bdev_logical_block_size(v->hash_dev->bdev) ||
731        num > INT_MAX) {
732        ti->error = "Invalid hash device block size";
733        r = -EINVAL;
734        goto bad;
735    }
736    v->hash_dev_block_bits = ffs(num) - 1;
737
738    if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
739        (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
740        >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
741        ti->error = "Invalid data blocks";
742        r = -EINVAL;
743        goto bad;
744    }
745    v->data_blocks = num_ll;
746
747    if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
748        ti->error = "Data device is too small";
749        r = -EINVAL;
750        goto bad;
751    }
752
753    if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
754        (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
755        >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
756        ti->error = "Invalid hash start";
757        r = -EINVAL;
758        goto bad;
759    }
760    v->hash_start = num_ll;
761
762    v->alg_name = kstrdup(argv[7], GFP_KERNEL);
763    if (!v->alg_name) {
764        ti->error = "Cannot allocate algorithm name";
765        r = -ENOMEM;
766        goto bad;
767    }
768
769    v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
770    if (IS_ERR(v->tfm)) {
771        ti->error = "Cannot initialize hash function";
772        r = PTR_ERR(v->tfm);
773        v->tfm = NULL;
774        goto bad;
775    }
776    v->digest_size = crypto_shash_digestsize(v->tfm);
777    if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
778        ti->error = "Digest size too big";
779        r = -EINVAL;
780        goto bad;
781    }
782    v->shash_descsize =
783        sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
784
785    v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
786    if (!v->root_digest) {
787        ti->error = "Cannot allocate root digest";
788        r = -ENOMEM;
789        goto bad;
790    }
791    if (strlen(argv[8]) != v->digest_size * 2 ||
792        hex2bin(v->root_digest, argv[8], v->digest_size)) {
793        ti->error = "Invalid root digest";
794        r = -EINVAL;
795        goto bad;
796    }
797
798    if (strcmp(argv[9], "-")) {
799        v->salt_size = strlen(argv[9]) / 2;
800        v->salt = kmalloc(v->salt_size, GFP_KERNEL);
801        if (!v->salt) {
802            ti->error = "Cannot allocate salt";
803            r = -ENOMEM;
804            goto bad;
805        }
806        if (strlen(argv[9]) != v->salt_size * 2 ||
807            hex2bin(v->salt, argv[9], v->salt_size)) {
808            ti->error = "Invalid salt";
809            r = -EINVAL;
810            goto bad;
811        }
812    }
813
814    v->hash_per_block_bits =
815        fls((1 << v->hash_dev_block_bits) / v->digest_size) - 1;
816
817    v->levels = 0;
818    if (v->data_blocks)
819        while (v->hash_per_block_bits * v->levels < 64 &&
820               (unsigned long long)(v->data_blocks - 1) >>
821               (v->hash_per_block_bits * v->levels))
822            v->levels++;
823
824    if (v->levels > DM_VERITY_MAX_LEVELS) {
825        ti->error = "Too many tree levels";
826        r = -E2BIG;
827        goto bad;
828    }
829
830    hash_position = v->hash_start;
831    for (i = v->levels - 1; i >= 0; i--) {
832        sector_t s;
833        v->hash_level_block[i] = hash_position;
834        s = verity_position_at_level(v, v->data_blocks, i);
835        s = (s >> v->hash_per_block_bits) +
836            !!(s & ((1 << v->hash_per_block_bits) - 1));
837        if (hash_position + s < hash_position) {
838            ti->error = "Hash device offset overflow";
839            r = -E2BIG;
840            goto bad;
841        }
842        hash_position += s;
843    }
844    v->hash_blocks = hash_position;
845
846    v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
847        1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
848        dm_bufio_alloc_callback, NULL);
849    if (IS_ERR(v->bufio)) {
850        ti->error = "Cannot initialize dm-bufio";
851        r = PTR_ERR(v->bufio);
852        v->bufio = NULL;
853        goto bad;
854    }
855
856    if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
857        ti->error = "Hash device is too small";
858        r = -E2BIG;
859        goto bad;
860    }
861
862    ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
863
864    v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
865                    BIO_MAX_PAGES * sizeof(struct bio_vec));
866    if (!v->vec_mempool) {
867        ti->error = "Cannot allocate vector mempool";
868        r = -ENOMEM;
869        goto bad;
870    }
871
872    /* WQ_UNBOUND greatly improves performance when running on ramdisk */
873    v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
874    if (!v->verify_wq) {
875        ti->error = "Cannot allocate workqueue";
876        r = -ENOMEM;
877        goto bad;
878    }
879
880    return 0;
881
882bad:
883    verity_dtr(ti);
884
885    return r;
886}
887
888static struct target_type verity_target = {
889    .name = "verity",
890    .version = {1, 2, 0},
891    .module = THIS_MODULE,
892    .ctr = verity_ctr,
893    .dtr = verity_dtr,
894    .map = verity_map,
895    .status = verity_status,
896    .ioctl = verity_ioctl,
897    .merge = verity_merge,
898    .iterate_devices = verity_iterate_devices,
899    .io_hints = verity_io_hints,
900};
901
902static int __init dm_verity_init(void)
903{
904    int r;
905
906    r = dm_register_target(&verity_target);
907    if (r < 0)
908        DMERR("register failed %d", r);
909
910    return r;
911}
912
913static void __exit dm_verity_exit(void)
914{
915    dm_unregister_target(&verity_target);
916}
917
918module_init(dm_verity_init);
919module_exit(dm_verity_exit);
920
921MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
922MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
923MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
924MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
925MODULE_LICENSE("GPL");
926

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