diff options
Diffstat (limited to 'drivers/md/dm-verity-target.c')
| -rw-r--r-- | drivers/md/dm-verity-target.c | 1291 |
1 files changed, 1291 insertions, 0 deletions
diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c new file mode 100644 index 000000000..7671949c8 --- /dev/null +++ b/drivers/md/dm-verity-target.c @@ -0,0 +1,1291 @@ +// 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() || + (bio->bi_opf & REQ_RAHEAD))) { + 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; + } + + /* WQ_UNBOUND greatly improves performance when running on ramdisk */ + v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); + if (!v->verify_wq) { + ti->error = "Cannot allocate workqueue"; + r = -ENOMEM; + goto bad; + } + + ti->per_io_data_size = sizeof(struct dm_verity_io) + + v->ahash_reqsize + v->digest_size * 2; + + r = verity_fec_ctr(v); + if (r) + goto bad; + + ti->per_io_data_size = roundup(ti->per_io_data_size, + __alignof__(struct dm_verity_io)); + + 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}, + .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"); |