// SPDX-License-Identifier: GPL-2.0-only
|
/*
|
* Copyright (C) 2012 Red Hat, Inc.
|
*
|
* Author: Mikulas Patocka <mpatocka@redhat.com>
|
*
|
* Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
|
*
|
* 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 "dm-verity-verify-sig.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_PANIC "panic_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 (3 + DM_VERITY_OPTS_FEC + \
|
DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
|
|
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_LIMIT("%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");
|
|
if (v->mode == DM_VERITY_MODE_PANIC)
|
panic("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;
|
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
|
|
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 && bio->bi_status == BLK_STS_OK &&
|
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 (bio->bi_status) {
|
/*
|
* Error correction failed; Just return error
|
*/
|
return -EIO;
|
}
|
if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
|
cur_block))
|
return -EIO;
|
}
|
}
|
|
return 0;
|
}
|
|
/*
|
* Skip verity work in response to I/O error when system is shutting down.
|
*/
|
static inline bool verity_is_system_shutting_down(void)
|
{
|
return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
|
|| system_state == SYSTEM_RESTART;
|
}
|
|
/*
|
* 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_is_system_shutting_down())) {
|
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)
|
{
|
sector_t block = io->block;
|
unsigned int n_blocks = io->n_blocks;
|
struct dm_verity_prefetch_work *pw;
|
|
if (v->validated_blocks) {
|
while (n_blocks && test_bit(block, v->validated_blocks)) {
|
block++;
|
n_blocks--;
|
}
|
while (n_blocks && test_bit(block + n_blocks - 1,
|
v->validated_blocks))
|
n_blocks--;
|
if (!n_blocks)
|
return;
|
}
|
|
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 = block;
|
pw->n_blocks = 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);
|
|
submit_bio_noacct(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 (v->signature_key_desc)
|
args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
|
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;
|
case DM_VERITY_MODE_PANIC:
|
DMEMIT(DM_VERITY_OPT_PANIC);
|
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);
|
if (v->signature_key_desc)
|
DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
|
" %s", v->signature_key_desc);
|
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->signature_key_desc);
|
|
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,
|
struct dm_verity_sig_opts *verify_args)
|
{
|
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_PANIC)) {
|
v->mode = DM_VERITY_MODE_PANIC;
|
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;
|
} else if (verity_verify_is_sig_opt_arg(arg_name)) {
|
r = verity_verify_sig_parse_opt_args(as, v,
|
verify_args,
|
&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_verity_sig_opts verify_args = {0};
|
struct dm_arg_set as;
|
unsigned int num;
|
unsigned long long num_ll;
|
int r;
|
int i;
|
sector_t hash_position;
|
char dummy;
|
char *root_hash_digest_to_validate;
|
|
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;
|
}
|
root_hash_digest_to_validate = argv[8];
|
|
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, &verify_args);
|
if (r < 0)
|
goto bad;
|
}
|
|
/* Root hash signature is a optional parameter*/
|
r = verity_verify_root_hash(root_hash_digest_to_validate,
|
strlen(root_hash_digest_to_validate),
|
verify_args.sig,
|
verify_args.sig_size);
|
if (r < 0) {
|
ti->error = "Root hash verification failed";
|
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;
|
}
|
|
/*
|
* Using WQ_HIGHPRI improves throughput and completion latency by
|
* reducing wait times when reading from a dm-verity device.
|
*
|
* Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
|
* allows verify_wq to preempt softirq since verification in tasklet
|
* will fall-back to using it for error handling (or if the bufio cache
|
* doesn't have required hashes).
|
*/
|
v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
|
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));
|
|
verity_verify_sig_opts_cleanup(&verify_args);
|
|
return 0;
|
|
bad:
|
|
verity_verify_sig_opts_cleanup(&verify_args);
|
verity_dtr(ti);
|
|
return r;
|
}
|
|
static struct target_type verity_target = {
|
.name = "verity",
|
.features = DM_TARGET_IMMUTABLE,
|
.version = {1, 7, 0},
|
.features = DM_TARGET_IMMUTABLE,
|
.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");
|
