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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>
#include <linux/security.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_ERROR_RESTART "restart_on_error"
#define DM_VERITY_OPT_ERROR_PANIC "panic_on_error"
#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 (5 + 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_bh_wq_enabled);
/* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
static DEFINE_STATIC_KEY_FALSE(ahash_enabled);
struct dm_verity_prefetch_work {
struct work_struct work;
struct dm_verity *v;
unsigned short ioprio;
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 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_ahash_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_ahash_init(struct dm_verity *v, struct ahash_request *req,
struct crypto_wait *wait, bool may_sleep)
{
int r;
ahash_request_set_tfm(req, v->ahash_tfm);
ahash_request_set_callback(req,
may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
crypto_req_done, (void *)wait);
crypto_init_wait(wait);
r = crypto_wait_req(crypto_ahash_init(req), wait);
if (unlikely(r < 0)) {
if (r != -ENOMEM)
DMERR("crypto_ahash_init failed: %d", r);
return r;
}
if (likely(v->salt_size && (v->version >= 1)))
r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
return r;
}
static int verity_ahash_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_ahash_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 dm_verity_io *io,
const u8 *data, size_t len, u8 *digest, bool may_sleep)
{
int r;
if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) {
struct ahash_request *req = verity_io_hash_req(v, io);
struct crypto_wait wait;
r = verity_ahash_init(v, req, &wait, may_sleep) ?:
verity_ahash_update(v, req, data, len, &wait) ?:
verity_ahash_final(v, req, digest, &wait);
} else {
struct shash_desc *desc = verity_io_hash_req(v, io);
desc->tfm = v->shash_tfm;
r = crypto_shash_import(desc, v->initial_hashstate) ?:
crypto_shash_finup(desc, data, len, digest);
}
if (unlikely(r))
DMERR("Error hashing block: %d", r);
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;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
verity_hash_at_level(v, block, level, &hash_block, &offset);
if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
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_with_ioprio(v->bufio, hash_block,
&buf, bio_prio(bio));
}
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, io, data, 1 << v->hash_dev_block_bits,
verity_io_real_digest(v, io), !io->in_bh);
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_bh_wq_enabled) && io->in_bh) {
/*
* 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) == 0)
aux->hash_verified = 1;
else if (verity_handle_err(v,
DM_VERITY_BLOCK_TYPE_METADATA,
hash_block)) {
struct bio *bio;
io->had_mismatch = true;
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;
}
static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
sector_t cur_block, u8 *dest)
{
struct page *page;
void *buffer;
int r;
struct dm_io_request io_req;
struct dm_io_region io_loc;
page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
buffer = page_to_virt(page);
io_req.bi_opf = REQ_OP_READ;
io_req.mem.type = DM_IO_KMEM;
io_req.mem.ptr.addr = buffer;
io_req.notify.fn = NULL;
io_req.client = v->io;
io_loc.bdev = v->data_dev->bdev;
io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
if (unlikely(r))
goto free_ret;
r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
verity_io_real_digest(v, io), true);
if (unlikely(r))
goto free_ret;
if (memcmp(verity_io_real_digest(v, io),
verity_io_want_digest(v, io), v->digest_size)) {
r = -EIO;
goto free_ret;
}
memcpy(dest, buffer, 1 << v->data_dev_block_bits);
r = 0;
free_ret:
mempool_free(page, &v->recheck_pool);
return r;
}
static int verity_handle_data_hash_mismatch(struct dm_verity *v,
struct dm_verity_io *io,
struct bio *bio, sector_t blkno,
u8 *data)
{
if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
/*
* Error handling code (FEC included) cannot be run in the
* BH workqueue, so fallback to a standard workqueue.
*/
return -EAGAIN;
}
if (verity_recheck(v, io, blkno, data) == 0) {
if (v->validated_blocks)
set_bit(blkno, v->validated_blocks);
return 0;
}
#if defined(CONFIG_DM_VERITY_FEC)
if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno,
data) == 0)
return 0;
#endif
if (bio->bi_status)
return -EIO; /* Error correction failed; Just return error */
if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
io->had_mismatch = true;
dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
return -EIO;
}
return 0;
}
/*
* Verify one "dm_verity_io" structure.
*/
static int verity_verify_io(struct dm_verity_io *io)
{
struct dm_verity *v = io->v;
const unsigned int block_size = 1 << v->data_dev_block_bits;
struct bvec_iter iter_copy;
struct bvec_iter *iter;
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
unsigned int b;
if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
/*
* 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++, bio_advance_iter(bio, iter, block_size)) {
int r;
sector_t cur_block = io->block + b;
bool is_zero;
struct bio_vec bv;
void *data;
if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
likely(test_bit(cur_block, v->validated_blocks)))
continue;
r = verity_hash_for_block(v, io, cur_block,
verity_io_want_digest(v, io),
&is_zero);
if (unlikely(r < 0))
return r;
bv = bio_iter_iovec(bio, *iter);
if (unlikely(bv.bv_len < block_size)) {
/*
* Data block spans pages. This should not happen,
* since dm-verity sets dma_alignment to the data block
* size minus 1, and dm-verity also doesn't allow the
* data block size to be greater than PAGE_SIZE.
*/
DMERR_LIMIT("unaligned io (data block spans pages)");
return -EIO;
}
data = bvec_kmap_local(&bv);
if (is_zero) {
/*
* If we expect a zero block, don't validate, just
* return zeros.
*/
memset(data, 0, block_size);
kunmap_local(data);
continue;
}
r = verity_hash(v, io, data, block_size,
verity_io_real_digest(v, io), !io->in_bh);
if (unlikely(r < 0)) {
kunmap_local(data);
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);
kunmap_local(data);
continue;
}
r = verity_handle_data_hash_mismatch(v, io, bio, cur_block,
data);
kunmap_local(data);
if (unlikely(r))
return r;
}
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;
}
static void restart_io_error(struct work_struct *w)
{
kernel_restart("dm-verity device has I/O error");
}
/*
* 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_bh_wq_enabled) || !io->in_bh)
verity_fec_finish_io(io);
if (unlikely(status != BLK_STS_OK) &&
unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
!io->had_mismatch &&
!verity_is_system_shutting_down()) {
if (v->error_mode == DM_VERITY_MODE_PANIC) {
panic("dm-verity device has I/O error");
}
if (v->error_mode == DM_VERITY_MODE_RESTART) {
static DECLARE_WORK(restart_work, restart_io_error);
queue_work(v->verify_wq, &restart_work);
/*
* We deliberately don't call bio_endio here, because
* the machine will be restarted anyway.
*/
return;
}
}
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_bh = false;
verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
}
static void verity_bh_work(struct work_struct *w)
{
struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
int err;
io->in_bh = true;
err = verity_verify_io(io);
if (err == -EAGAIN || err == -ENOMEM) {
/* 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() ||
(bio->bi_opf & REQ_RAHEAD))) {
verity_finish_io(io, bio->bi_status);
return;
}
if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) {
INIT_WORK(&io->bh_work, verity_bh_work);
queue_work(system_bh_wq, &io->bh_work);
} 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_with_ioprio(v->bufio, hash_block_start,
hash_block_end - hash_block_start + 1,
pw->ioprio);
}
kfree(pw);
}
static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
unsigned short ioprio)
{
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;
pw->ioprio = ioprio;
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;
io->had_mismatch = false;
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, bio_prio(bio));
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 (v->error_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_bh_wq)
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->error_mode != DM_VERITY_MODE_EIO) {
DMEMIT(" ");
switch (v->error_mode) {
case DM_VERITY_MODE_RESTART:
DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
break;
case DM_VERITY_MODE_PANIC:
DMEMIT(DM_VERITY_OPT_ERROR_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_bh_wq)
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");
}
}
if (v->error_mode != DM_VERITY_MODE_EIO) {
DMEMIT(",verity_error_mode=");
switch (v->error_mode) {
case DM_VERITY_MODE_RESTART:
DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
break;
case DM_VERITY_MODE_PANIC:
DMEMIT(DM_VERITY_OPT_ERROR_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 (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, 0, 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;
limits->io_min = limits->logical_block_size;
/*
* Similar to what dm-crypt does, opt dm-verity out of support for
* direct I/O that is aligned to less than the traditional direct I/O
* alignment requirement of logical_block_size. This prevents dm-verity
* data blocks from crossing pages, eliminating various edge cases.
*/
limits->dma_alignment = limits->logical_block_size - 1;
}
#ifdef CONFIG_SECURITY
static int verity_init_sig(struct dm_verity *v, const void *sig,
size_t sig_size)
{
v->sig_size = sig_size;
if (sig) {
v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL);
if (!v->root_digest_sig)
return -ENOMEM;
}