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linux-zen-desktop/drivers/md/dm-verity-target.c

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// 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 "dm-audit.h"
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/scatterlist.h>
#include <linux/string.h>
#include <linux/jump_label.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_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
#define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \
DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
struct dm_verity_prefetch_work {
struct work_struct work;
struct dm_verity *v;
sector_t block;
unsigned int 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);
}
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("%s failed updating salt: %d", __func__, 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 int *offset)
{
sector_t position = verity_position_at_level(v, block, level);
unsigned int 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 = true;
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);
dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
}
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 int offset;
verity_hash_at_level(v, block, level, &hash_block, &offset);
if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
data = dm_bufio_get(v->bufio, hash_block, &buf);
if (data == NULL) {
/*
* In tasklet and the hash was not in the bufio cache.
* Return early and resume execution from a work-queue
* to read the hash from disk.
*/
return -EAGAIN;
}
} else
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 (static_branch_unlikely(&use_tasklet_enabled) &&
io->in_tasklet) {
/*
* Error handling code (FEC included) cannot be run in a
* tasklet since it may sleep, so fallback to work-queue.
*/
r = -EAGAIN;
goto release_ret_r;
} 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)) {
struct bio *bio =
dm_bio_from_per_bio_data(io,
v->ti->per_io_data_size);
dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
block, 0);
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("%s crypto op failed: %d", __func__, 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 int 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 int len;
struct bio_vec bv = bio_iter_iovec(bio, *iter);
page = bvec_kmap_local(&bv);
len = bv.bv_len;
if (likely(len >= todo))
len = todo;
r = process(v, io, page, len);
kunmap_local(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;
#if defined(CONFIG_DM_VERITY_FEC)
struct bvec_iter start;
#endif
struct bvec_iter iter_copy;
struct bvec_iter *iter;
struct crypto_wait wait;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
unsigned int b;
if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
/*
* Copy the iterator in case we need to restart
* verification in a work-queue.
*/
iter_copy = io->iter;
iter = &iter_copy;
} else
iter = &io->iter;
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, 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, iter,
verity_bv_zero);
if (unlikely(r < 0))
return r;
continue;
}
r = verity_hash_init(v, req, &wait);
if (unlikely(r < 0))
return r;
#if defined(CONFIG_DM_VERITY_FEC)
if (verity_fec_is_enabled(v))
start = *iter;
#endif
r = verity_for_io_block(v, 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 (static_branch_unlikely(&use_tasklet_enabled) &&
io->in_tasklet) {
/*
* Error handling code (FEC included) cannot be run in a
* tasklet since it may sleep, so fallback to work-queue.
*/
return -EAGAIN;
#if defined(CONFIG_DM_VERITY_FEC)
} else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
cur_block, NULL, &start) == 0) {
continue;
#endif
} 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)) {
dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
bio, cur_block, 0);
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;
if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
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);
io->in_tasklet = false;
verity_fec_init_io(io);
verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
}
static void verity_tasklet(unsigned long data)
{
struct dm_verity_io *io = (struct dm_verity_io *)data;
int err;
io->in_tasklet = true;
err = verity_verify_io(io);
if (err == -EAGAIN) {
/* fallback to retrying with work-queue */
INIT_WORK(&io->work, verity_work);
queue_work(io->v->verify_wq, &io->work);
return;
}
verity_finish_io(io, errno_to_blk_status(err));
}
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;
}
if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
tasklet_schedule(&io->tasklet);
} else {
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 int 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 int)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_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 int status_flags, char *result, unsigned int maxlen)
{
struct dm_verity *v = ti->private;
unsigned int args = 0;
unsigned int sz = 0;
unsigned int 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->use_tasklet)
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);
if (v->use_tasklet)
DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
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;
case STATUSTYPE_IMA:
DMEMIT_TARGET_NAME_VERSION(ti->type);
DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
DMEMIT(",verity_version=%u", v->version);
DMEMIT(",data_device_name=%s", v->data_dev->name);
DMEMIT(",hash_device_name=%s", v->hash_dev->name);
DMEMIT(",verity_algorithm=%s", v->alg_name);
DMEMIT(",root_digest=");
for (x = 0; x < v->digest_size; x++)
DMEMIT("%02x", v->root_digest[x]);
DMEMIT(",salt=");
if (!v->salt_size)
DMEMIT("-");
else
for (x = 0; x < v->salt_size; x++)
DMEMIT("%02x", v->salt[x]);
DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
if (v->signature_key_desc)
DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
if (v->mode != DM_VERITY_MODE_EIO) {
DMEMIT(",verity_mode=");
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:
DMEMIT("invalid");
}
}
DMEMIT(";");
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 != bdev_nr_sectors(v->data_dev->bdev))
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);
if (v->use_tasklet)
static_branch_dec(&use_tasklet_enabled);
kfree(v);
dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
}
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 inline bool verity_is_verity_mode(const char *arg_name)
{
return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
!strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
!strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
}
static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
{
if (v->mode)
return -EINVAL;
if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
v->mode = DM_VERITY_MODE_LOGGING;
else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
v->mode = DM_VERITY_MODE_RESTART;
else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
v->mode = DM_VERITY_MODE_PANIC;
return 0;
}
static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
struct dm_verity_sig_opts *verify_args,
bool only_modifier_opts)
{
int r = 0;
unsigned int 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 (verity_is_verity_mode(arg_name)) {
if (only_modifier_opts)
continue;
r = verity_parse_verity_mode(v, arg_name);
if (r) {
ti->error = "Conflicting error handling parameters";
return r;
}
continue;
} else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
if (only_modifier_opts)
continue;
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)) {
if (only_modifier_opts)
continue;
r = verity_alloc_most_once(v);
if (r)
return r;
continue;
} else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
v->use_tasklet = true;
static_branch_inc(&use_tasklet_enabled);
continue;
} else if (verity_is_fec_opt_arg(arg_name)) {
if (only_modifier_opts)
continue;
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)) {
if (only_modifier_opts)
continue;
r = verity_verify_sig_parse_opt_args(as, v,
verify_args,
&argc, arg_name);
if (r)
return r;
continue;
} else if (only_modifier_opts) {
/*
* Ignore unrecognized opt, could easily be an extra
* argument to an option whose parsing was skipped.
* Normal parsing (@only_modifier_opts=false) will
* properly parse all options (and their extra args).
*/
continue;
}
DMERR("Unrecognized verity feature request: %s", arg_name);
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 int 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) & ~BLK_OPEN_READ)) {
ti->error = "Device must be readonly";
r = -EINVAL;
goto bad;
}
if (argc < 10) {
ti->error = "Not enough arguments";
r = -EINVAL;
goto bad;
}
/* Parse optional parameters that modify primary args */
if (argc > 10) {
as.argc = argc - 10;
as.argv = argv + 10;
r = verity_parse_opt_args(&as, v, &verify_args, true);
if (r < 0)
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], BLK_OPEN_READ, &v->data_dev);
if (r) {
ti->error = "Data device lookup failed";
goto bad;
}
r = dm_get_device(ti, argv[2], BLK_OPEN_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,
v->use_tasklet ? CRYPTO_ALG_ASYNC : 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, false);
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,
v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
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);
dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
return 0;
bad:
verity_verify_sig_opts_cleanup(&verify_args);
dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
verity_dtr(ti);
return r;
}
/*
* Check whether a DM target is a verity target.
*/
bool dm_is_verity_target(struct dm_target *ti)
{
return ti->type->module == THIS_MODULE;
}
/*
* Get the verity mode (error behavior) of a verity target.
*
* Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
* target.
*/
int dm_verity_get_mode(struct dm_target *ti)
{
struct dm_verity *v = ti->private;
if (!dm_is_verity_target(ti))
return -EINVAL;
return v->mode;
}
/*
* Get the root digest of a verity target.
*
* Returns a copy of the root digest, the caller is responsible for
* freeing the memory of the digest.
*/
int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
{
struct dm_verity *v = ti->private;
if (!dm_is_verity_target(ti))
return -EINVAL;
*root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
if (*root_digest == NULL)
return -ENOMEM;
*digest_size = v->digest_size;
return 0;
}
static struct target_type verity_target = {
.name = "verity",
.features = DM_TARGET_IMMUTABLE,
.version = {1, 9, 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,
};
module_dm(verity);
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");
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