linux/drivers/md/dm-verity.c
Mikulas Patocka 3b6b7813b1 dm verity: avoid deadlock
A deadlock was found in the prefetch code in the dm verity map
function.  This patch fixes this by transferring the prefetch
to a worker thread and skipping it completely if kmalloc fails.

If generic_make_request is called recursively, it queues the I/O
request on the current->bio_list without making the I/O request
and returns. The routine making the recursive call cannot wait
for the I/O to complete.

The deadlock occurs when one thread grabs the bufio_client
mutex and waits for an I/O to complete but the I/O is queued
on another thread's current->bio_list and is waiting to get
the mutex held by the first thread.

The fix recognises that prefetching is not essential.  If memory
can be allocated, it queues the prefetch request to the worker thread,
but if not, it does nothing.

Signed-off-by: Paul Taysom <taysom@chromium.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: stable@kernel.org
2013-03-20 17:21:25 +00:00

926 lines
23 KiB
C

/*
* Copyright (C) 2012 Red Hat, Inc.
*
* Author: Mikulas Patocka <mpatocka@redhat.com>
*
* Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
*
* This file is released under the GPLv2.
*
* In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
* default prefetch value. Data are read in "prefetch_cluster" chunks from the
* hash device. Setting this greatly improves performance when data and hash
* are on the same disk on different partitions on devices with poor random
* access behavior.
*/
#include "dm-bufio.h"
#include <linux/module.h>
#include <linux/device-mapper.h>
#include <crypto/hash.h>
#define DM_MSG_PREFIX "verity"
#define DM_VERITY_IO_VEC_INLINE 16
#define DM_VERITY_MEMPOOL_SIZE 4
#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
#define DM_VERITY_MAX_LEVELS 63
static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
struct dm_verity {
struct dm_dev *data_dev;
struct dm_dev *hash_dev;
struct dm_target *ti;
struct dm_bufio_client *bufio;
char *alg_name;
struct crypto_shash *tfm;
u8 *root_digest; /* digest of the root block */
u8 *salt; /* salt: its size is salt_size */
unsigned salt_size;
sector_t data_start; /* data offset in 512-byte sectors */
sector_t hash_start; /* hash start in blocks */
sector_t data_blocks; /* the number of data blocks */
sector_t hash_blocks; /* the number of hash blocks */
unsigned char data_dev_block_bits; /* log2(data blocksize) */
unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
unsigned char levels; /* the number of tree levels */
unsigned char version;
unsigned digest_size; /* digest size for the current hash algorithm */
unsigned shash_descsize;/* the size of temporary space for crypto */
int hash_failed; /* set to 1 if hash of any block failed */
mempool_t *vec_mempool; /* mempool of bio vector */
struct workqueue_struct *verify_wq;
/* starting blocks for each tree level. 0 is the lowest level. */
sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
};
struct dm_verity_io {
struct dm_verity *v;
/* original values of bio->bi_end_io and bio->bi_private */
bio_end_io_t *orig_bi_end_io;
void *orig_bi_private;
sector_t block;
unsigned n_blocks;
/* saved bio vector */
struct bio_vec *io_vec;
unsigned io_vec_size;
struct work_struct work;
/* A space for short vectors; longer vectors are allocated separately. */
struct bio_vec io_vec_inline[DM_VERITY_IO_VEC_INLINE];
/*
* Three variably-size fields follow this struct:
*
* u8 hash_desc[v->shash_descsize];
* u8 real_digest[v->digest_size];
* u8 want_digest[v->digest_size];
*
* To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
*/
};
struct dm_verity_prefetch_work {
struct work_struct work;
struct dm_verity *v;
sector_t block;
unsigned n_blocks;
};
static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
{
return (struct shash_desc *)(io + 1);
}
static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
{
return (u8 *)(io + 1) + v->shash_descsize;
}
static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
{
return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
}
/*
* Auxiliary structure appended to each dm-bufio buffer. If the value
* hash_verified is nonzero, hash of the block has been verified.
*
* The variable hash_verified is set to 0 when allocating the buffer, then
* it can be changed to 1 and it is never reset to 0 again.
*
* There is no lock around this value, a race condition can at worst cause
* that multiple processes verify the hash of the same buffer simultaneously
* and write 1 to hash_verified simultaneously.
* This condition is harmless, so we don't need locking.
*/
struct buffer_aux {
int hash_verified;
};
/*
* Initialize struct buffer_aux for a freshly created buffer.
*/
static void dm_bufio_alloc_callback(struct dm_buffer *buf)
{
struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
aux->hash_verified = 0;
}
/*
* Translate input sector number to the sector number on the target device.
*/
static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
{
return v->data_start + dm_target_offset(v->ti, bi_sector);
}
/*
* Return hash position of a specified block at a specified tree level
* (0 is the lowest level).
* The lowest "hash_per_block_bits"-bits of the result denote hash position
* inside a hash block. The remaining bits denote location of the hash block.
*/
static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
int level)
{
return block >> (level * v->hash_per_block_bits);
}
static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
sector_t *hash_block, unsigned *offset)
{
sector_t position = verity_position_at_level(v, block, level);
unsigned idx;
*hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
if (!offset)
return;
idx = position & ((1 << v->hash_per_block_bits) - 1);
if (!v->version)
*offset = idx * v->digest_size;
else
*offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
}
/*
* Verify hash of a metadata block pertaining to the specified data block
* ("block" argument) at a specified level ("level" argument).
*
* On successful return, io_want_digest(v, io) contains the hash value for
* a lower tree level or for the data block (if we're at the lowest leve).
*
* If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
* If "skip_unverified" is false, unverified buffer is hashed and verified
* against current value of io_want_digest(v, io).
*/
static int verity_verify_level(struct dm_verity_io *io, sector_t block,
int level, bool skip_unverified)
{
struct dm_verity *v = io->v;
struct dm_buffer *buf;
struct buffer_aux *aux;
u8 *data;
int r;
sector_t hash_block;
unsigned offset;
verity_hash_at_level(v, block, level, &hash_block, &offset);
data = dm_bufio_read(v->bufio, hash_block, &buf);
if (unlikely(IS_ERR(data)))
return PTR_ERR(data);
aux = dm_bufio_get_aux_data(buf);
if (!aux->hash_verified) {
struct shash_desc *desc;
u8 *result;
if (skip_unverified) {
r = 1;
goto release_ret_r;
}
desc = io_hash_desc(v, io);
desc->tfm = v->tfm;
desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
r = crypto_shash_init(desc);
if (r < 0) {
DMERR("crypto_shash_init failed: %d", r);
goto release_ret_r;
}
if (likely(v->version >= 1)) {
r = crypto_shash_update(desc, v->salt, v->salt_size);
if (r < 0) {
DMERR("crypto_shash_update failed: %d", r);
goto release_ret_r;
}
}
r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
if (r < 0) {
DMERR("crypto_shash_update failed: %d", r);
goto release_ret_r;
}
if (!v->version) {
r = crypto_shash_update(desc, v->salt, v->salt_size);
if (r < 0) {
DMERR("crypto_shash_update failed: %d", r);
goto release_ret_r;
}
}
result = io_real_digest(v, io);
r = crypto_shash_final(desc, result);
if (r < 0) {
DMERR("crypto_shash_final failed: %d", r);
goto release_ret_r;
}
if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
DMERR_LIMIT("metadata block %llu is corrupted",
(unsigned long long)hash_block);
v->hash_failed = 1;
r = -EIO;
goto release_ret_r;
} else
aux->hash_verified = 1;
}
data += offset;
memcpy(io_want_digest(v, io), data, v->digest_size);
dm_bufio_release(buf);
return 0;
release_ret_r:
dm_bufio_release(buf);
return r;
}
/*
* Verify one "dm_verity_io" structure.
*/
static int verity_verify_io(struct dm_verity_io *io)
{
struct dm_verity *v = io->v;
unsigned b;
int i;
unsigned vector = 0, offset = 0;
for (b = 0; b < io->n_blocks; b++) {
struct shash_desc *desc;
u8 *result;
int r;
unsigned todo;
if (likely(v->levels)) {
/*
* First, we try to get the requested hash for
* the current block. If the hash block itself is
* verified, zero is returned. If it isn't, this
* function returns 0 and we fall back to whole
* chain verification.
*/
int r = verity_verify_level(io, io->block + b, 0, true);
if (likely(!r))
goto test_block_hash;
if (r < 0)
return r;
}
memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
for (i = v->levels - 1; i >= 0; i--) {
int r = verity_verify_level(io, io->block + b, i, false);
if (unlikely(r))
return r;
}
test_block_hash:
desc = io_hash_desc(v, io);
desc->tfm = v->tfm;
desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
r = crypto_shash_init(desc);
if (r < 0) {
DMERR("crypto_shash_init failed: %d", r);
return r;
}
if (likely(v->version >= 1)) {
r = crypto_shash_update(desc, v->salt, v->salt_size);
if (r < 0) {
DMERR("crypto_shash_update failed: %d", r);
return r;
}
}
todo = 1 << v->data_dev_block_bits;
do {
struct bio_vec *bv;
u8 *page;
unsigned len;
BUG_ON(vector >= io->io_vec_size);
bv = &io->io_vec[vector];
page = kmap_atomic(bv->bv_page);
len = bv->bv_len - offset;
if (likely(len >= todo))
len = todo;
r = crypto_shash_update(desc,
page + bv->bv_offset + offset, len);
kunmap_atomic(page);
if (r < 0) {
DMERR("crypto_shash_update failed: %d", r);
return r;
}
offset += len;
if (likely(offset == bv->bv_len)) {
offset = 0;
vector++;
}
todo -= len;
} while (todo);
if (!v->version) {
r = crypto_shash_update(desc, v->salt, v->salt_size);
if (r < 0) {
DMERR("crypto_shash_update failed: %d", r);
return r;
}
}
result = io_real_digest(v, io);
r = crypto_shash_final(desc, result);
if (r < 0) {
DMERR("crypto_shash_final failed: %d", r);
return r;
}
if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
DMERR_LIMIT("data block %llu is corrupted",
(unsigned long long)(io->block + b));
v->hash_failed = 1;
return -EIO;
}
}
BUG_ON(vector != io->io_vec_size);
BUG_ON(offset);
return 0;
}
/*
* End one "io" structure with a given error.
*/
static void verity_finish_io(struct dm_verity_io *io, int error)
{
struct dm_verity *v = io->v;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
bio->bi_end_io = io->orig_bi_end_io;
bio->bi_private = io->orig_bi_private;
if (io->io_vec != io->io_vec_inline)
mempool_free(io->io_vec, v->vec_mempool);
bio_endio(bio, error);
}
static void verity_work(struct work_struct *w)
{
struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
verity_finish_io(io, verity_verify_io(io));
}
static void verity_end_io(struct bio *bio, int error)
{
struct dm_verity_io *io = bio->bi_private;
if (error) {
verity_finish_io(io, error);
return;
}
INIT_WORK(&io->work, verity_work);
queue_work(io->v->verify_wq, &io->work);
}
/*
* Prefetch buffers for the specified io.
* The root buffer is not prefetched, it is assumed that it will be cached
* all the time.
*/
static void verity_prefetch_io(struct work_struct *work)
{
struct dm_verity_prefetch_work *pw =
container_of(work, struct dm_verity_prefetch_work, work);
struct dm_verity *v = pw->v;
int i;
for (i = v->levels - 2; i >= 0; i--) {
sector_t hash_block_start;
sector_t hash_block_end;
verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
if (!i) {
unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
cluster >>= v->data_dev_block_bits;
if (unlikely(!cluster))
goto no_prefetch_cluster;
if (unlikely(cluster & (cluster - 1)))
cluster = 1 << (fls(cluster) - 1);
hash_block_start &= ~(sector_t)(cluster - 1);
hash_block_end |= cluster - 1;
if (unlikely(hash_block_end >= v->hash_blocks))
hash_block_end = v->hash_blocks - 1;
}
no_prefetch_cluster:
dm_bufio_prefetch(v->bufio, hash_block_start,
hash_block_end - hash_block_start + 1);
}
kfree(pw);
}
static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
{
struct dm_verity_prefetch_work *pw;
pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
if (!pw)
return;
INIT_WORK(&pw->work, verity_prefetch_io);
pw->v = v;
pw->block = io->block;
pw->n_blocks = io->n_blocks;
queue_work(v->verify_wq, &pw->work);
}
/*
* Bio map function. It allocates dm_verity_io structure and bio vector and
* fills them. Then it issues prefetches and the I/O.
*/
static int verity_map(struct dm_target *ti, struct bio *bio)
{
struct dm_verity *v = ti->private;
struct dm_verity_io *io;
bio->bi_bdev = v->data_dev->bdev;
bio->bi_sector = verity_map_sector(v, bio->bi_sector);
if (((unsigned)bio->bi_sector | bio_sectors(bio)) &
((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
DMERR_LIMIT("unaligned io");
return -EIO;
}
if ((bio->bi_sector + bio_sectors(bio)) >>
(v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
DMERR_LIMIT("io out of range");
return -EIO;
}
if (bio_data_dir(bio) == WRITE)
return -EIO;
io = dm_per_bio_data(bio, ti->per_bio_data_size);
io->v = v;
io->orig_bi_end_io = bio->bi_end_io;
io->orig_bi_private = bio->bi_private;
io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
io->n_blocks = bio->bi_size >> v->data_dev_block_bits;
bio->bi_end_io = verity_end_io;
bio->bi_private = io;
io->io_vec_size = bio->bi_vcnt - bio->bi_idx;
if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE)
io->io_vec = io->io_vec_inline;
else
io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO);
memcpy(io->io_vec, bio_iovec(bio),
io->io_vec_size * sizeof(struct bio_vec));
verity_submit_prefetch(v, io);
generic_make_request(bio);
return DM_MAPIO_SUBMITTED;
}
/*
* Status: V (valid) or C (corruption found)
*/
static void verity_status(struct dm_target *ti, status_type_t type,
unsigned status_flags, char *result, unsigned maxlen)
{
struct dm_verity *v = ti->private;
unsigned sz = 0;
unsigned x;
switch (type) {
case STATUSTYPE_INFO:
DMEMIT("%c", v->hash_failed ? 'C' : 'V');
break;
case STATUSTYPE_TABLE:
DMEMIT("%u %s %s %u %u %llu %llu %s ",
v->version,
v->data_dev->name,
v->hash_dev->name,
1 << v->data_dev_block_bits,
1 << v->hash_dev_block_bits,
(unsigned long long)v->data_blocks,
(unsigned long long)v->hash_start,
v->alg_name
);
for (x = 0; x < v->digest_size; x++)
DMEMIT("%02x", v->root_digest[x]);
DMEMIT(" ");
if (!v->salt_size)
DMEMIT("-");
else
for (x = 0; x < v->salt_size; x++)
DMEMIT("%02x", v->salt[x]);
break;
}
}
static int verity_ioctl(struct dm_target *ti, unsigned cmd,
unsigned long arg)
{
struct dm_verity *v = ti->private;
int r = 0;
if (v->data_start ||
ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
r = scsi_verify_blk_ioctl(NULL, cmd);
return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
cmd, arg);
}
static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
struct bio_vec *biovec, int max_size)
{
struct dm_verity *v = ti->private;
struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
if (!q->merge_bvec_fn)
return max_size;
bvm->bi_bdev = v->data_dev->bdev;
bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
}
static int verity_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
struct dm_verity *v = ti->private;
return fn(ti, v->data_dev, v->data_start, ti->len, data);
}
static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
{
struct dm_verity *v = ti->private;
if (limits->logical_block_size < 1 << v->data_dev_block_bits)
limits->logical_block_size = 1 << v->data_dev_block_bits;
if (limits->physical_block_size < 1 << v->data_dev_block_bits)
limits->physical_block_size = 1 << v->data_dev_block_bits;
blk_limits_io_min(limits, limits->logical_block_size);
}
static void verity_dtr(struct dm_target *ti)
{
struct dm_verity *v = ti->private;
if (v->verify_wq)
destroy_workqueue(v->verify_wq);
if (v->vec_mempool)
mempool_destroy(v->vec_mempool);
if (v->bufio)
dm_bufio_client_destroy(v->bufio);
kfree(v->salt);
kfree(v->root_digest);
if (v->tfm)
crypto_free_shash(v->tfm);
kfree(v->alg_name);
if (v->hash_dev)
dm_put_device(ti, v->hash_dev);
if (v->data_dev)
dm_put_device(ti, v->data_dev);
kfree(v);
}
/*
* Target parameters:
* <version> The current format is version 1.
* Vsn 0 is compatible with original Chromium OS releases.
* <data device>
* <hash device>
* <data block size>
* <hash block size>
* <the number of data blocks>
* <hash start block>
* <algorithm>
* <digest>
* <salt> Hex string or "-" if no salt.
*/
static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
struct dm_verity *v;
unsigned num;
unsigned long long num_ll;
int r;
int i;
sector_t hash_position;
char dummy;
v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
if (!v) {
ti->error = "Cannot allocate verity structure";
return -ENOMEM;
}
ti->private = v;
v->ti = ti;
if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
ti->error = "Device must be readonly";
r = -EINVAL;
goto bad;
}
if (argc != 10) {
ti->error = "Invalid argument count: exactly 10 arguments required";
r = -EINVAL;
goto bad;
}
if (sscanf(argv[0], "%d%c", &num, &dummy) != 1 ||
num < 0 || num > 1) {
ti->error = "Invalid version";
r = -EINVAL;
goto bad;
}
v->version = num;
r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
if (r) {
ti->error = "Data device lookup failed";
goto bad;
}
r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
if (r) {
ti->error = "Data device lookup failed";
goto bad;
}
if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
!num || (num & (num - 1)) ||
num < bdev_logical_block_size(v->data_dev->bdev) ||
num > PAGE_SIZE) {
ti->error = "Invalid data device block size";
r = -EINVAL;
goto bad;
}
v->data_dev_block_bits = ffs(num) - 1;
if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
!num || (num & (num - 1)) ||
num < bdev_logical_block_size(v->hash_dev->bdev) ||
num > INT_MAX) {
ti->error = "Invalid hash device block size";
r = -EINVAL;
goto bad;
}
v->hash_dev_block_bits = ffs(num) - 1;
if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
(sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
>> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
ti->error = "Invalid data blocks";
r = -EINVAL;
goto bad;
}
v->data_blocks = num_ll;
if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
ti->error = "Data device is too small";
r = -EINVAL;
goto bad;
}
if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
(sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
>> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
ti->error = "Invalid hash start";
r = -EINVAL;
goto bad;
}
v->hash_start = num_ll;
v->alg_name = kstrdup(argv[7], GFP_KERNEL);
if (!v->alg_name) {
ti->error = "Cannot allocate algorithm name";
r = -ENOMEM;
goto bad;
}
v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
if (IS_ERR(v->tfm)) {
ti->error = "Cannot initialize hash function";
r = PTR_ERR(v->tfm);
v->tfm = NULL;
goto bad;
}
v->digest_size = crypto_shash_digestsize(v->tfm);
if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
ti->error = "Digest size too big";
r = -EINVAL;
goto bad;
}
v->shash_descsize =
sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
if (!v->root_digest) {
ti->error = "Cannot allocate root digest";
r = -ENOMEM;
goto bad;
}
if (strlen(argv[8]) != v->digest_size * 2 ||
hex2bin(v->root_digest, argv[8], v->digest_size)) {
ti->error = "Invalid root digest";
r = -EINVAL;
goto bad;
}
if (strcmp(argv[9], "-")) {
v->salt_size = strlen(argv[9]) / 2;
v->salt = kmalloc(v->salt_size, GFP_KERNEL);
if (!v->salt) {
ti->error = "Cannot allocate salt";
r = -ENOMEM;
goto bad;
}
if (strlen(argv[9]) != v->salt_size * 2 ||
hex2bin(v->salt, argv[9], v->salt_size)) {
ti->error = "Invalid salt";
r = -EINVAL;
goto bad;
}
}
v->hash_per_block_bits =
fls((1 << v->hash_dev_block_bits) / v->digest_size) - 1;
v->levels = 0;
if (v->data_blocks)
while (v->hash_per_block_bits * v->levels < 64 &&
(unsigned long long)(v->data_blocks - 1) >>
(v->hash_per_block_bits * v->levels))
v->levels++;
if (v->levels > DM_VERITY_MAX_LEVELS) {
ti->error = "Too many tree levels";
r = -E2BIG;
goto bad;
}
hash_position = v->hash_start;
for (i = v->levels - 1; i >= 0; i--) {
sector_t s;
v->hash_level_block[i] = hash_position;
s = verity_position_at_level(v, v->data_blocks, i);
s = (s >> v->hash_per_block_bits) +
!!(s & ((1 << v->hash_per_block_bits) - 1));
if (hash_position + s < hash_position) {
ti->error = "Hash device offset overflow";
r = -E2BIG;
goto bad;
}
hash_position += s;
}
v->hash_blocks = hash_position;
v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
dm_bufio_alloc_callback, NULL);
if (IS_ERR(v->bufio)) {
ti->error = "Cannot initialize dm-bufio";
r = PTR_ERR(v->bufio);
v->bufio = NULL;
goto bad;
}
if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
ti->error = "Hash device is too small";
r = -E2BIG;
goto bad;
}
ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
BIO_MAX_PAGES * sizeof(struct bio_vec));
if (!v->vec_mempool) {
ti->error = "Cannot allocate vector mempool";
r = -ENOMEM;
goto bad;
}
/* WQ_UNBOUND greatly improves performance when running on ramdisk */
v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
if (!v->verify_wq) {
ti->error = "Cannot allocate workqueue";
r = -ENOMEM;
goto bad;
}
return 0;
bad:
verity_dtr(ti);
return r;
}
static struct target_type verity_target = {
.name = "verity",
.version = {1, 2, 0},
.module = THIS_MODULE,
.ctr = verity_ctr,
.dtr = verity_dtr,
.map = verity_map,
.status = verity_status,
.ioctl = verity_ioctl,
.merge = verity_merge,
.iterate_devices = verity_iterate_devices,
.io_hints = verity_io_hints,
};
static int __init dm_verity_init(void)
{
int r;
r = dm_register_target(&verity_target);
if (r < 0)
DMERR("register failed %d", r);
return r;
}
static void __exit dm_verity_exit(void)
{
dm_unregister_target(&verity_target);
}
module_init(dm_verity_init);
module_exit(dm_verity_exit);
MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
MODULE_LICENSE("GPL");