linux/drivers/md/dm-verity-target.c
Eric Biggers bbf6a56692 dm verity: log the hash algorithm implementation
Log the hash algorithm's driver name when a dm-verity target is created.
This will help people determine whether the expected implementation is
being used.  It can make an enormous difference; e.g., SHA-256 on ARM
can be 8x faster with the crypto extensions than without.  It can also
be useful to know if an implementation using an external crypto
accelerator is being used instead of a software implementation.

Example message:

[   35.281945] device-mapper: verity: sha256 using implementation "sha256-ce"

We've already found the similar message in fs/crypto/keyinfo.c to be
very useful.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-12-18 09:02:27 -05:00

1213 lines
29 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-verity.h"
#include "dm-verity-fec.h"
#include <linux/module.h>
#include <linux/reboot.h>
#define DM_MSG_PREFIX "verity"
#define DM_VERITY_ENV_LENGTH 42
#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
#define DM_VERITY_MAX_CORRUPTED_ERRS 100
#define DM_VERITY_OPT_LOGGING "ignore_corruption"
#define DM_VERITY_OPT_RESTART "restart_on_corruption"
#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
#define DM_VERITY_OPTS_MAX (2 + DM_VERITY_OPTS_FEC)
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_prefetch_work {
struct work_struct work;
struct dm_verity *v;
sector_t block;
unsigned n_blocks;
};
/*
* 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 int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
const u8 *data, size_t len,
struct crypto_wait *wait)
{
struct scatterlist sg;
if (likely(!is_vmalloc_addr(data))) {
sg_init_one(&sg, data, len);
ahash_request_set_crypt(req, &sg, NULL, len);
return crypto_wait_req(crypto_ahash_update(req), wait);
} else {
do {
int r;
size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
flush_kernel_vmap_range((void *)data, this_step);
sg_init_table(&sg, 1);
sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
ahash_request_set_crypt(req, &sg, NULL, this_step);
r = crypto_wait_req(crypto_ahash_update(req), wait);
if (unlikely(r))
return r;
data += this_step;
len -= this_step;
} while (len);
return 0;
}
}
/*
* Wrapper for crypto_ahash_init, which handles verity salting.
*/
static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
struct crypto_wait *wait)
{
int r;
ahash_request_set_tfm(req, v->tfm);
ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, (void *)wait);
crypto_init_wait(wait);
r = crypto_wait_req(crypto_ahash_init(req), wait);
if (unlikely(r < 0)) {
DMERR("crypto_ahash_init failed: %d", r);
return r;
}
if (likely(v->salt_size && (v->version >= 1)))
r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
return r;
}
static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
u8 *digest, struct crypto_wait *wait)
{
int r;
if (unlikely(v->salt_size && (!v->version))) {
r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
if (r < 0) {
DMERR("verity_hash_final failed updating salt: %d", r);
goto out;
}
}
ahash_request_set_crypt(req, NULL, digest, 0);
r = crypto_wait_req(crypto_ahash_final(req), wait);
out:
return r;
}
int verity_hash(struct dm_verity *v, struct ahash_request *req,
const u8 *data, size_t len, u8 *digest)
{
int r;
struct crypto_wait wait;
r = verity_hash_init(v, req, &wait);
if (unlikely(r < 0))
goto out;
r = verity_hash_update(v, req, data, len, &wait);
if (unlikely(r < 0))
goto out;
r = verity_hash_final(v, req, digest, &wait);
out:
return r;
}
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);
}
/*
* Handle verification errors.
*/
static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
unsigned long long block)
{
char verity_env[DM_VERITY_ENV_LENGTH];
char *envp[] = { verity_env, NULL };
const char *type_str = "";
struct mapped_device *md = dm_table_get_md(v->ti->table);
/* Corruption should be visible in device status in all modes */
v->hash_failed = 1;
if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
goto out;
v->corrupted_errs++;
switch (type) {
case DM_VERITY_BLOCK_TYPE_DATA:
type_str = "data";
break;
case DM_VERITY_BLOCK_TYPE_METADATA:
type_str = "metadata";
break;
default:
BUG();
}
DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
block);
if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
DMERR("%s: reached maximum errors", v->data_dev->name);
snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
DM_VERITY_ENV_VAR_NAME, type, block);
kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
out:
if (v->mode == DM_VERITY_MODE_LOGGING)
return 0;
if (v->mode == DM_VERITY_MODE_RESTART)
kernel_restart("dm-verity device corrupted");
return 1;
}
/*
* Verify hash of a metadata block pertaining to the specified data block
* ("block" argument) at a specified level ("level" argument).
*
* On successful return, verity_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 level).
*
* 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 verity_io_want_digest(v, io).
*/
static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
sector_t block, int level, bool skip_unverified,
u8 *want_digest)
{
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 (IS_ERR(data))
return PTR_ERR(data);
aux = dm_bufio_get_aux_data(buf);
if (!aux->hash_verified) {
if (skip_unverified) {
r = 1;
goto release_ret_r;
}
r = verity_hash(v, verity_io_hash_req(v, io),
data, 1 << v->hash_dev_block_bits,
verity_io_real_digest(v, io));
if (unlikely(r < 0))
goto release_ret_r;
if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
v->digest_size) == 0))
aux->hash_verified = 1;
else if (verity_fec_decode(v, io,
DM_VERITY_BLOCK_TYPE_METADATA,
hash_block, data, NULL) == 0)
aux->hash_verified = 1;
else if (verity_handle_err(v,
DM_VERITY_BLOCK_TYPE_METADATA,
hash_block)) {
r = -EIO;
goto release_ret_r;
}
}
data += offset;
memcpy(want_digest, data, v->digest_size);
r = 0;
release_ret_r:
dm_bufio_release(buf);
return r;
}
/*
* Find a hash for a given block, write it to digest and verify the integrity
* of the hash tree if necessary.
*/
int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
sector_t block, u8 *digest, bool *is_zero)
{
int r = 0, i;
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 1 and we fall back to whole
* chain verification.
*/
r = verity_verify_level(v, io, block, 0, true, digest);
if (likely(r <= 0))
goto out;
}
memcpy(digest, v->root_digest, v->digest_size);
for (i = v->levels - 1; i >= 0; i--) {
r = verity_verify_level(v, io, block, i, false, digest);
if (unlikely(r))
goto out;
}
out:
if (!r && v->zero_digest)
*is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
else
*is_zero = false;
return r;
}
/*
* Calculates the digest for the given bio
*/
static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
struct bvec_iter *iter, struct crypto_wait *wait)
{
unsigned int todo = 1 << v->data_dev_block_bits;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
struct scatterlist sg;
struct ahash_request *req = verity_io_hash_req(v, io);
do {
int r;
unsigned int len;
struct bio_vec bv = bio_iter_iovec(bio, *iter);
sg_init_table(&sg, 1);
len = bv.bv_len;
if (likely(len >= todo))
len = todo;
/*
* Operating on a single page at a time looks suboptimal
* until you consider the typical block size is 4,096B.
* Going through this loops twice should be very rare.
*/
sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
ahash_request_set_crypt(req, &sg, NULL, len);
r = crypto_wait_req(crypto_ahash_update(req), wait);
if (unlikely(r < 0)) {
DMERR("verity_for_io_block crypto op failed: %d", r);
return r;
}
bio_advance_iter(bio, iter, len);
todo -= len;
} while (todo);
return 0;
}
/*
* Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
* starting from iter.
*/
int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
struct bvec_iter *iter,
int (*process)(struct dm_verity *v,
struct dm_verity_io *io, u8 *data,
size_t len))
{
unsigned todo = 1 << v->data_dev_block_bits;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
do {
int r;
u8 *page;
unsigned len;
struct bio_vec bv = bio_iter_iovec(bio, *iter);
page = kmap_atomic(bv.bv_page);
len = bv.bv_len;
if (likely(len >= todo))
len = todo;
r = process(v, io, page + bv.bv_offset, len);
kunmap_atomic(page);
if (r < 0)
return r;
bio_advance_iter(bio, iter, len);
todo -= len;
} while (todo);
return 0;
}
static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
u8 *data, size_t len)
{
memset(data, 0, len);
return 0;
}
/*
* Moves the bio iter one data block forward.
*/
static inline void verity_bv_skip_block(struct dm_verity *v,
struct dm_verity_io *io,
struct bvec_iter *iter)
{
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
}
/*
* Verify one "dm_verity_io" structure.
*/
static int verity_verify_io(struct dm_verity_io *io)
{
bool is_zero;
struct dm_verity *v = io->v;
struct bvec_iter start;
unsigned b;
struct crypto_wait wait;
for (b = 0; b < io->n_blocks; b++) {
int r;
sector_t cur_block = io->block + b;
struct ahash_request *req = verity_io_hash_req(v, io);
if (v->validated_blocks &&
likely(test_bit(cur_block, v->validated_blocks))) {
verity_bv_skip_block(v, io, &io->iter);
continue;
}
r = verity_hash_for_block(v, io, cur_block,
verity_io_want_digest(v, io),
&is_zero);
if (unlikely(r < 0))
return r;
if (is_zero) {
/*
* If we expect a zero block, don't validate, just
* return zeros.
*/
r = verity_for_bv_block(v, io, &io->iter,
verity_bv_zero);
if (unlikely(r < 0))
return r;
continue;
}
r = verity_hash_init(v, req, &wait);
if (unlikely(r < 0))
return r;
start = io->iter;
r = verity_for_io_block(v, io, &io->iter, &wait);
if (unlikely(r < 0))
return r;
r = verity_hash_final(v, req, verity_io_real_digest(v, io),
&wait);
if (unlikely(r < 0))
return r;
if (likely(memcmp(verity_io_real_digest(v, io),
verity_io_want_digest(v, io), v->digest_size) == 0)) {
if (v->validated_blocks)
set_bit(cur_block, v->validated_blocks);
continue;
}
else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
cur_block, NULL, &start) == 0)
continue;
else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
cur_block))
return -EIO;
}
return 0;
}
/*
* End one "io" structure with a given error.
*/
static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
{
struct dm_verity *v = io->v;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
bio->bi_end_io = io->orig_bi_end_io;
bio->bi_status = status;
verity_fec_finish_io(io);
bio_endio(bio);
}
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, errno_to_blk_status(verity_verify_io(io)));
}
static void verity_end_io(struct bio *bio)
{
struct dm_verity_io *io = bio->bi_private;
if (bio->bi_status && !verity_fec_is_enabled(io->v)) {
verity_finish_io(io, bio->bi_status);
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 = READ_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);
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_set_dev(bio, v->data_dev->bdev);
bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
DMERR_LIMIT("unaligned io");
return DM_MAPIO_KILL;
}
if (bio_end_sector(bio) >>
(v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
DMERR_LIMIT("io out of range");
return DM_MAPIO_KILL;
}
if (bio_data_dir(bio) == WRITE)
return DM_MAPIO_KILL;
io = dm_per_bio_data(bio, ti->per_io_data_size);
io->v = v;
io->orig_bi_end_io = bio->bi_end_io;
io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
bio->bi_end_io = verity_end_io;
bio->bi_private = io;
io->iter = bio->bi_iter;
verity_fec_init_io(io);
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 args = 0;
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]);
if (v->mode != DM_VERITY_MODE_EIO)
args++;
if (verity_fec_is_enabled(v))
args += DM_VERITY_OPTS_FEC;
if (v->zero_digest)
args++;
if (v->validated_blocks)
args++;
if (!args)
return;
DMEMIT(" %u", args);
if (v->mode != DM_VERITY_MODE_EIO) {
DMEMIT(" ");
switch (v->mode) {
case DM_VERITY_MODE_LOGGING:
DMEMIT(DM_VERITY_OPT_LOGGING);
break;
case DM_VERITY_MODE_RESTART:
DMEMIT(DM_VERITY_OPT_RESTART);
break;
default:
BUG();
}
}
if (v->zero_digest)
DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
if (v->validated_blocks)
DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
sz = verity_fec_status_table(v, sz, result, maxlen);
break;
}
}
static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
{
struct dm_verity *v = ti->private;
*bdev = v->data_dev->bdev;
if (v->data_start ||
ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
return 1;
return 0;
}
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->bufio)
dm_bufio_client_destroy(v->bufio);
kvfree(v->validated_blocks);
kfree(v->salt);
kfree(v->root_digest);
kfree(v->zero_digest);
if (v->tfm)
crypto_free_ahash(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);
verity_fec_dtr(v);
kfree(v);
}
static int verity_alloc_most_once(struct dm_verity *v)
{
struct dm_target *ti = v->ti;
/* the bitset can only handle INT_MAX blocks */
if (v->data_blocks > INT_MAX) {
ti->error = "device too large to use check_at_most_once";
return -E2BIG;
}
v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
sizeof(unsigned long),
GFP_KERNEL);
if (!v->validated_blocks) {
ti->error = "failed to allocate bitset for check_at_most_once";
return -ENOMEM;
}
return 0;
}
static int verity_alloc_zero_digest(struct dm_verity *v)
{
int r = -ENOMEM;
struct ahash_request *req;
u8 *zero_data;
v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
if (!v->zero_digest)
return r;
req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
if (!req)
return r; /* verity_dtr will free zero_digest */
zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
if (!zero_data)
goto out;
r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
v->zero_digest);
out:
kfree(req);
kfree(zero_data);
return r;
}
static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
{
int r;
unsigned argc;
struct dm_target *ti = v->ti;
const char *arg_name;
static const struct dm_arg _args[] = {
{0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
};
r = dm_read_arg_group(_args, as, &argc, &ti->error);
if (r)
return -EINVAL;
if (!argc)
return 0;
do {
arg_name = dm_shift_arg(as);
argc--;
if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
v->mode = DM_VERITY_MODE_LOGGING;
continue;
} else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
v->mode = DM_VERITY_MODE_RESTART;
continue;
} else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
r = verity_alloc_zero_digest(v);
if (r) {
ti->error = "Cannot allocate zero digest";
return r;
}
continue;
} else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
r = verity_alloc_most_once(v);
if (r)
return r;
continue;
} else if (verity_is_fec_opt_arg(arg_name)) {
r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
if (r)
return r;
continue;
}
ti->error = "Unrecognized verity feature request";
return -EINVAL;
} while (argc && !r);
return r;
}
/*
* 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;
struct dm_arg_set as;
unsigned int 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;
r = verity_fec_ctr_alloc(v);
if (r)
goto bad;
if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
ti->error = "Device must be readonly";
r = -EINVAL;
goto bad;
}
if (argc < 10) {
ti->error = "Not enough arguments";
r = -EINVAL;
goto bad;
}
if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
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 = "Hash 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);
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);
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_ahash(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;
}
/*
* dm-verity performance can vary greatly depending on which hash
* algorithm implementation is used. Help people debug performance
* problems by logging the ->cra_driver_name.
*/
DMINFO("%s using implementation \"%s\"", v->alg_name,
crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
v->digest_size = crypto_ahash_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->ahash_reqsize = sizeof(struct ahash_request) +
crypto_ahash_reqsize(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;
}
}
argv += 10;
argc -= 10;
/* Optional parameters */
if (argc) {
as.argc = argc;
as.argv = argv;
r = verity_parse_opt_args(&as, v);
if (r < 0)
goto bad;
}
v->hash_per_block_bits =
__fls((1 << v->hash_dev_block_bits) / v->digest_size);
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 = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
>> ((i + 1) * v->hash_per_block_bits);
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;
}
/* 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;
}
ti->per_io_data_size = sizeof(struct dm_verity_io) +
v->ahash_reqsize + v->digest_size * 2;
r = verity_fec_ctr(v);
if (r)
goto bad;
ti->per_io_data_size = roundup(ti->per_io_data_size,
__alignof__(struct dm_verity_io));
return 0;
bad:
verity_dtr(ti);
return r;
}
static struct target_type verity_target = {
.name = "verity",
.version = {1, 4, 0},
.module = THIS_MODULE,
.ctr = verity_ctr,
.dtr = verity_dtr,
.map = verity_map,
.status = verity_status,
.prepare_ioctl = verity_prepare_ioctl,
.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");