| /* |
| * Copyright (C) 2012 Red Hat, Inc. |
| * |
| * Author: Mikulas Patocka <mpatocka@redhat.com> |
| * |
| * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors |
| * |
| * This file is released under the GPLv2. |
| * |
| * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set |
| * default prefetch value. Data are read in "prefetch_cluster" chunks from the |
| * hash device. Setting this greatly improves performance when data and hash |
| * are on the same disk on different partitions on devices with poor random |
| * access behavior. |
| */ |
| |
| #include "dm-verity.h" |
| #include "dm-verity-fec.h" |
| |
| #include <linux/module.h> |
| #include <linux/reboot.h> |
| |
| #define DM_MSG_PREFIX "verity" |
| |
| #define DM_VERITY_ENV_LENGTH 42 |
| #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" |
| |
| #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 |
| |
| #define DM_VERITY_MAX_CORRUPTED_ERRS 100 |
| |
| #define DM_VERITY_OPT_LOGGING "ignore_corruption" |
| #define DM_VERITY_OPT_RESTART "restart_on_corruption" |
| #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" |
| #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" |
| |
| #define DM_VERITY_OPTS_MAX (2 + DM_VERITY_OPTS_FEC) |
| |
| static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; |
| |
| module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR); |
| |
| struct dm_verity_prefetch_work { |
| struct work_struct work; |
| struct dm_verity *v; |
| sector_t block; |
| unsigned n_blocks; |
| }; |
| |
| /* |
| * Auxiliary structure appended to each dm-bufio buffer. If the value |
| * hash_verified is nonzero, hash of the block has been verified. |
| * |
| * The variable hash_verified is set to 0 when allocating the buffer, then |
| * it can be changed to 1 and it is never reset to 0 again. |
| * |
| * There is no lock around this value, a race condition can at worst cause |
| * that multiple processes verify the hash of the same buffer simultaneously |
| * and write 1 to hash_verified simultaneously. |
| * This condition is harmless, so we don't need locking. |
| */ |
| struct buffer_aux { |
| int hash_verified; |
| }; |
| |
| /* |
| * Initialize struct buffer_aux for a freshly created buffer. |
| */ |
| static void dm_bufio_alloc_callback(struct dm_buffer *buf) |
| { |
| struct buffer_aux *aux = dm_bufio_get_aux_data(buf); |
| |
| aux->hash_verified = 0; |
| } |
| |
| /* |
| * Translate input sector number to the sector number on the target device. |
| */ |
| static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) |
| { |
| return v->data_start + dm_target_offset(v->ti, bi_sector); |
| } |
| |
| /* |
| * Return hash position of a specified block at a specified tree level |
| * (0 is the lowest level). |
| * The lowest "hash_per_block_bits"-bits of the result denote hash position |
| * inside a hash block. The remaining bits denote location of the hash block. |
| */ |
| static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, |
| int level) |
| { |
| return block >> (level * v->hash_per_block_bits); |
| } |
| |
| /* |
| * Callback function for asynchrnous crypto API completion notification |
| */ |
| static void verity_op_done(struct crypto_async_request *base, int err) |
| { |
| struct verity_result *res = (struct verity_result *)base->data; |
| |
| if (err == -EINPROGRESS) |
| return; |
| |
| res->err = err; |
| complete(&res->completion); |
| } |
| |
| /* |
| * Wait for async crypto API callback |
| */ |
| static inline int verity_complete_op(struct verity_result *res, int ret) |
| { |
| switch (ret) { |
| case 0: |
| break; |
| |
| case -EINPROGRESS: |
| case -EBUSY: |
| ret = wait_for_completion_interruptible(&res->completion); |
| if (!ret) |
| ret = res->err; |
| reinit_completion(&res->completion); |
| break; |
| |
| default: |
| DMERR("verity_wait_hash: crypto op submission failed: %d", ret); |
| } |
| |
| if (unlikely(ret < 0)) |
| DMERR("verity_wait_hash: crypto op failed: %d", ret); |
| |
| return ret; |
| } |
| |
| static int verity_hash_update(struct dm_verity *v, struct ahash_request *req, |
| const u8 *data, size_t len, |
| struct verity_result *res) |
| { |
| struct scatterlist sg; |
| |
| if (likely(!is_vmalloc_addr(data))) { |
| sg_init_one(&sg, data, len); |
| ahash_request_set_crypt(req, &sg, NULL, len); |
| return verity_complete_op(res, crypto_ahash_update(req)); |
| } 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 = verity_complete_op(res, crypto_ahash_update(req)); |
| 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 verity_result *res) |
| { |
| int r; |
| |
| ahash_request_set_tfm(req, v->tfm); |
| ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | |
| CRYPTO_TFM_REQ_MAY_BACKLOG, |
| verity_op_done, (void *)res); |
| init_completion(&res->completion); |
| |
| r = verity_complete_op(res, crypto_ahash_init(req)); |
| |
| 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, res); |
| |
| return r; |
| } |
| |
| static int verity_hash_final(struct dm_verity *v, struct ahash_request *req, |
| u8 *digest, struct verity_result *res) |
| { |
| int r; |
| |
| if (unlikely(v->salt_size && (!v->version))) { |
| r = verity_hash_update(v, req, v->salt, v->salt_size, res); |
| |
| if (r < 0) { |
| DMERR("verity_hash_final failed updating salt: %d", r); |
| goto out; |
| } |
| } |
| |
| ahash_request_set_crypt(req, NULL, digest, 0); |
| r = verity_complete_op(res, crypto_ahash_final(req)); |
| 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 verity_result res; |
| |
| r = verity_hash_init(v, req, &res); |
| if (unlikely(r < 0)) |
| goto out; |
| |
| r = verity_hash_update(v, req, data, len, &res); |
| if (unlikely(r < 0)) |
| goto out; |
| |
| r = verity_hash_final(v, req, digest, &res); |
| |
| out: |
| return r; |
| } |
| |
| static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, |
| sector_t *hash_block, unsigned *offset) |
| { |
| sector_t position = verity_position_at_level(v, block, level); |
| unsigned idx; |
| |
| *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); |
| |
| if (!offset) |
| return; |
| |
| idx = position & ((1 << v->hash_per_block_bits) - 1); |
| if (!v->version) |
| *offset = idx * v->digest_size; |
| else |
| *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); |
| } |
| |
| /* |
| * Handle verification errors. |
| */ |
| static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, |
| unsigned long long block) |
| { |
| char verity_env[DM_VERITY_ENV_LENGTH]; |
| char *envp[] = { verity_env, NULL }; |
| const char *type_str = ""; |
| struct mapped_device *md = dm_table_get_md(v->ti->table); |
| |
| /* Corruption should be visible in device status in all modes */ |
| v->hash_failed = 1; |
| |
| if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) |
| goto out; |
| |
| v->corrupted_errs++; |
| |
| switch (type) { |
| case DM_VERITY_BLOCK_TYPE_DATA: |
| type_str = "data"; |
| break; |
| case DM_VERITY_BLOCK_TYPE_METADATA: |
| type_str = "metadata"; |
| break; |
| default: |
| BUG(); |
| } |
| |
| DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str, |
| block); |
| |
| if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) |
| DMERR("%s: reached maximum errors", v->data_dev->name); |
| |
| snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", |
| DM_VERITY_ENV_VAR_NAME, type, block); |
| |
| kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); |
| |
| out: |
| if (v->mode == DM_VERITY_MODE_LOGGING) |
| return 0; |
| |
| if (v->mode == DM_VERITY_MODE_RESTART) { |
| #ifdef CONFIG_DM_VERITY_AVB |
| dm_verity_avb_error_handler(); |
| #endif |
| kernel_restart("dm-verity device corrupted"); |
| } |
| |
| return 1; |
| } |
| |
| /* |
| * Verify hash of a metadata block pertaining to the specified data block |
| * ("block" argument) at a specified level ("level" argument). |
| * |
| * On successful return, verity_io_want_digest(v, io) contains the hash value |
| * for a lower tree level or for the data block (if we're at the lowest level). |
| * |
| * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. |
| * If "skip_unverified" is false, unverified buffer is hashed and verified |
| * against current value of verity_io_want_digest(v, io). |
| */ |
| static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, |
| sector_t block, int level, bool skip_unverified, |
| u8 *want_digest) |
| { |
| struct dm_buffer *buf; |
| struct buffer_aux *aux; |
| u8 *data; |
| int r; |
| sector_t hash_block; |
| unsigned offset; |
| |
| verity_hash_at_level(v, block, level, &hash_block, &offset); |
| |
| data = dm_bufio_read(v->bufio, hash_block, &buf); |
| if (IS_ERR(data)) |
| return PTR_ERR(data); |
| |
| aux = dm_bufio_get_aux_data(buf); |
| |
| if (!aux->hash_verified) { |
| if (skip_unverified) { |
| r = 1; |
| goto release_ret_r; |
| } |
| |
| r = verity_hash(v, verity_io_hash_req(v, io), |
| data, 1 << v->hash_dev_block_bits, |
| verity_io_real_digest(v, io)); |
| if (unlikely(r < 0)) |
| goto release_ret_r; |
| |
| if (likely(memcmp(verity_io_real_digest(v, io), want_digest, |
| v->digest_size) == 0)) |
| aux->hash_verified = 1; |
| else if (verity_fec_decode(v, io, |
| DM_VERITY_BLOCK_TYPE_METADATA, |
| hash_block, data, NULL) == 0) |
| aux->hash_verified = 1; |
| else if (verity_handle_err(v, |
| DM_VERITY_BLOCK_TYPE_METADATA, |
| hash_block)) { |
| r = -EIO; |
| goto release_ret_r; |
| } |
| } |
| |
| data += offset; |
| memcpy(want_digest, data, v->digest_size); |
| r = 0; |
| |
| release_ret_r: |
| dm_bufio_release(buf); |
| return r; |
| } |
| |
| /* |
| * Find a hash for a given block, write it to digest and verify the integrity |
| * of the hash tree if necessary. |
| */ |
| int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, |
| sector_t block, u8 *digest, bool *is_zero) |
| { |
| int r = 0, i; |
| |
| if (likely(v->levels)) { |
| /* |
| * First, we try to get the requested hash for |
| * the current block. If the hash block itself is |
| * verified, zero is returned. If it isn't, this |
| * function returns 1 and we fall back to whole |
| * chain verification. |
| */ |
| r = verity_verify_level(v, io, block, 0, true, digest); |
| if (likely(r <= 0)) |
| goto out; |
| } |
| |
| memcpy(digest, v->root_digest, v->digest_size); |
| |
| for (i = v->levels - 1; i >= 0; i--) { |
| r = verity_verify_level(v, io, block, i, false, digest); |
| if (unlikely(r)) |
| goto out; |
| } |
| out: |
| if (!r && v->zero_digest) |
| *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); |
| else |
| *is_zero = false; |
| |
| return r; |
| } |
| |
| /* |
| * Calculates the digest for the given bio |
| */ |
| int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, |
| struct bvec_iter *iter, struct verity_result *res) |
| { |
| 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 = verity_complete_op(res, crypto_ahash_update(req)); |
| |
| 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 verity_result res; |
| |
| for (b = 0; b < io->n_blocks; b++) { |
| int r; |
| sector_t cur_block = io->block + b; |
| struct ahash_request *req = verity_io_hash_req(v, io); |
| |
| if (v->validated_blocks && |
| likely(test_bit(cur_block, v->validated_blocks))) { |
| verity_bv_skip_block(v, io, &io->iter); |
| continue; |
| } |
| |
| r = verity_hash_for_block(v, io, cur_block, |
| verity_io_want_digest(v, io), |
| &is_zero); |
| if (unlikely(r < 0)) |
| return r; |
| |
| if (is_zero) { |
| /* |
| * If we expect a zero block, don't validate, just |
| * return zeros. |
| */ |
| r = verity_for_bv_block(v, io, &io->iter, |
| verity_bv_zero); |
| if (unlikely(r < 0)) |
| return r; |
| |
| continue; |
| } |
| |
| r = verity_hash_init(v, req, &res); |
| if (unlikely(r < 0)) |
| return r; |
| |
| start = io->iter; |
| r = verity_for_io_block(v, io, &io->iter, &res); |
| if (unlikely(r < 0)) |
| return r; |
| |
| r = verity_hash_final(v, req, verity_io_real_digest(v, io), |
| &res); |
| if (unlikely(r < 0)) |
| return r; |
| |
| if (likely(memcmp(verity_io_real_digest(v, io), |
| verity_io_want_digest(v, io), v->digest_size) == 0)) { |
| if (v->validated_blocks) |
| set_bit(cur_block, v->validated_blocks); |
| continue; |
| } |
| else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, |
| cur_block, NULL, &start) == 0) |
| continue; |
| else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, |
| cur_block)) |
| return -EIO; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * End one "io" structure with a given error. |
| */ |
| static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) |
| { |
| struct dm_verity *v = io->v; |
| struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); |
| |
| bio->bi_end_io = io->orig_bi_end_io; |
| bio->bi_status = status; |
| |
| verity_fec_finish_io(io); |
| |
| bio_endio(bio); |
| } |
| |
| static void verity_work(struct work_struct *w) |
| { |
| struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); |
| |
| verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); |
| } |
| |
| static void verity_end_io(struct bio *bio) |
| { |
| struct dm_verity_io *io = bio->bi_private; |
| |
| if (bio->bi_status && !verity_fec_is_enabled(io->v)) { |
| verity_finish_io(io, bio->bi_status); |
| return; |
| } |
| |
| INIT_WORK(&io->work, verity_work); |
| queue_work(io->v->verify_wq, &io->work); |
| } |
| |
| /* |
| * Prefetch buffers for the specified io. |
| * The root buffer is not prefetched, it is assumed that it will be cached |
| * all the time. |
| */ |
| static void verity_prefetch_io(struct work_struct *work) |
| { |
| struct dm_verity_prefetch_work *pw = |
| container_of(work, struct dm_verity_prefetch_work, work); |
| struct dm_verity *v = pw->v; |
| int i; |
| |
| for (i = v->levels - 2; i >= 0; i--) { |
| sector_t hash_block_start; |
| sector_t hash_block_end; |
| verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); |
| verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); |
| if (!i) { |
| unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster); |
| |
| cluster >>= v->data_dev_block_bits; |
| if (unlikely(!cluster)) |
| goto no_prefetch_cluster; |
| |
| if (unlikely(cluster & (cluster - 1))) |
| cluster = 1 << __fls(cluster); |
| |
| hash_block_start &= ~(sector_t)(cluster - 1); |
| hash_block_end |= cluster - 1; |
| if (unlikely(hash_block_end >= v->hash_blocks)) |
| hash_block_end = v->hash_blocks - 1; |
| } |
| no_prefetch_cluster: |
| dm_bufio_prefetch(v->bufio, hash_block_start, |
| hash_block_end - hash_block_start + 1); |
| } |
| |
| kfree(pw); |
| } |
| |
| static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) |
| { |
| struct dm_verity_prefetch_work *pw; |
| |
| pw = kmalloc(sizeof(struct dm_verity_prefetch_work), |
| GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); |
| |
| if (!pw) |
| return; |
| |
| INIT_WORK(&pw->work, verity_prefetch_io); |
| pw->v = v; |
| pw->block = io->block; |
| pw->n_blocks = io->n_blocks; |
| queue_work(v->verify_wq, &pw->work); |
| } |
| |
| /* |
| * Bio map function. It allocates dm_verity_io structure and bio vector and |
| * fills them. Then it issues prefetches and the I/O. |
| */ |
| int verity_map(struct dm_target *ti, struct bio *bio) |
| { |
| struct dm_verity *v = ti->private; |
| struct dm_verity_io *io; |
| |
| bio_set_dev(bio, v->data_dev->bdev); |
| bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); |
| |
| if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) & |
| ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { |
| DMERR_LIMIT("unaligned io"); |
| return DM_MAPIO_KILL; |
| } |
| |
| if (bio_end_sector(bio) >> |
| (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { |
| DMERR_LIMIT("io out of range"); |
| return DM_MAPIO_KILL; |
| } |
| |
| if (bio_data_dir(bio) == WRITE) |
| return DM_MAPIO_KILL; |
| |
| io = dm_per_bio_data(bio, ti->per_io_data_size); |
| io->v = v; |
| io->orig_bi_end_io = bio->bi_end_io; |
| io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); |
| io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; |
| |
| bio->bi_end_io = verity_end_io; |
| bio->bi_private = io; |
| io->iter = bio->bi_iter; |
| |
| verity_fec_init_io(io); |
| |
| verity_submit_prefetch(v, io); |
| |
| generic_make_request(bio); |
| |
| return DM_MAPIO_SUBMITTED; |
| } |
| |
| /* |
| * Status: V (valid) or C (corruption found) |
| */ |
| void verity_status(struct dm_target *ti, status_type_t type, |
| unsigned status_flags, char *result, unsigned maxlen) |
| { |
| struct dm_verity *v = ti->private; |
| unsigned args = 0; |
| unsigned sz = 0; |
| unsigned x; |
| |
| switch (type) { |
| case STATUSTYPE_INFO: |
| DMEMIT("%c", v->hash_failed ? 'C' : 'V'); |
| break; |
| case STATUSTYPE_TABLE: |
| DMEMIT("%u %s %s %u %u %llu %llu %s ", |
| v->version, |
| v->data_dev->name, |
| v->hash_dev->name, |
| 1 << v->data_dev_block_bits, |
| 1 << v->hash_dev_block_bits, |
| (unsigned long long)v->data_blocks, |
| (unsigned long long)v->hash_start, |
| v->alg_name |
| ); |
| for (x = 0; x < v->digest_size; x++) |
| DMEMIT("%02x", v->root_digest[x]); |
| DMEMIT(" "); |
| if (!v->salt_size) |
| DMEMIT("-"); |
| else |
| for (x = 0; x < v->salt_size; x++) |
| DMEMIT("%02x", v->salt[x]); |
| if (v->mode != DM_VERITY_MODE_EIO) |
| args++; |
| if (verity_fec_is_enabled(v)) |
| args += DM_VERITY_OPTS_FEC; |
| if (v->zero_digest) |
| args++; |
| if (v->validated_blocks) |
| args++; |
| if (!args) |
| return; |
| DMEMIT(" %u", args); |
| if (v->mode != DM_VERITY_MODE_EIO) { |
| DMEMIT(" "); |
| switch (v->mode) { |
| case DM_VERITY_MODE_LOGGING: |
| DMEMIT(DM_VERITY_OPT_LOGGING); |
| break; |
| case DM_VERITY_MODE_RESTART: |
| DMEMIT(DM_VERITY_OPT_RESTART); |
| break; |
| default: |
| BUG(); |
| } |
| } |
| if (v->zero_digest) |
| DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); |
| if (v->validated_blocks) |
| DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); |
| sz = verity_fec_status_table(v, sz, result, maxlen); |
| break; |
| } |
| } |
| |
| int verity_prepare_ioctl(struct dm_target *ti, |
| struct block_device **bdev, fmode_t *mode) |
| { |
| 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; |
| } |
| |
| 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); |
| } |
| |
| 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); |
| } |
| |
| void verity_dtr(struct dm_target *ti) |
| { |
| struct dm_verity *v = ti->private; |
| |
| if (v->verify_wq) |
| destroy_workqueue(v->verify_wq); |
| |
| if (v->bufio) |
| dm_bufio_client_destroy(v->bufio); |
| |
| kvfree(v->validated_blocks); |
| kfree(v->salt); |
| kfree(v->root_digest); |
| kfree(v->zero_digest); |
| |
| if (v->tfm) |
| crypto_free_ahash(v->tfm); |
| |
| kfree(v->alg_name); |
| |
| if (v->hash_dev) |
| dm_put_device(ti, v->hash_dev); |
| |
| if (v->data_dev) |
| dm_put_device(ti, v->data_dev); |
| |
| verity_fec_dtr(v); |
| |
| kfree(v); |
| } |
| |
| static int verity_alloc_most_once(struct dm_verity *v) |
| { |
| struct dm_target *ti = v->ti; |
| |
| /* the bitset can only handle INT_MAX blocks */ |
| if (v->data_blocks > INT_MAX) { |
| ti->error = "device too large to use check_at_most_once"; |
| return -E2BIG; |
| } |
| |
| v->validated_blocks = kvzalloc(BITS_TO_LONGS(v->data_blocks) * |
| sizeof(unsigned long), GFP_KERNEL); |
| if (!v->validated_blocks) { |
| ti->error = "failed to allocate bitset for check_at_most_once"; |
| return -ENOMEM; |
| } |
| |
| return 0; |
| } |
| |
| static int verity_alloc_zero_digest(struct dm_verity *v) |
| { |
| int r = -ENOMEM; |
| struct ahash_request *req; |
| u8 *zero_data; |
| |
| v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); |
| |
| if (!v->zero_digest) |
| return r; |
| |
| req = kmalloc(v->ahash_reqsize, GFP_KERNEL); |
| |
| if (!req) |
| return r; /* verity_dtr will free zero_digest */ |
| |
| zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); |
| |
| if (!zero_data) |
| goto out; |
| |
| r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, |
| v->zero_digest); |
| |
| out: |
| kfree(req); |
| kfree(zero_data); |
| |
| return r; |
| } |
| |
| static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v) |
| { |
| int r; |
| unsigned argc; |
| struct dm_target *ti = v->ti; |
| const char *arg_name; |
| |
| static const struct dm_arg _args[] = { |
| {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, |
| }; |
| |
| r = dm_read_arg_group(_args, as, &argc, &ti->error); |
| if (r) |
| return -EINVAL; |
| |
| if (!argc) |
| return 0; |
| |
| do { |
| arg_name = dm_shift_arg(as); |
| argc--; |
| |
| if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) { |
| v->mode = DM_VERITY_MODE_LOGGING; |
| continue; |
| |
| } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) { |
| v->mode = DM_VERITY_MODE_RESTART; |
| continue; |
| |
| } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { |
| r = verity_alloc_zero_digest(v); |
| if (r) { |
| ti->error = "Cannot allocate zero digest"; |
| return r; |
| } |
| continue; |
| |
| } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { |
| r = verity_alloc_most_once(v); |
| if (r) |
| return r; |
| continue; |
| |
| } else if (verity_is_fec_opt_arg(arg_name)) { |
| r = verity_fec_parse_opt_args(as, v, &argc, arg_name); |
| if (r) |
| return r; |
| continue; |
| } |
| |
| ti->error = "Unrecognized verity feature request"; |
| return -EINVAL; |
| } while (argc && !r); |
| |
| return r; |
| } |
| |
| /* |
| * Target parameters: |
| * <version> The current format is version 1. |
| * Vsn 0 is compatible with original Chromium OS releases. |
| * <data device> |
| * <hash device> |
| * <data block size> |
| * <hash block size> |
| * <the number of data blocks> |
| * <hash start block> |
| * <algorithm> |
| * <digest> |
| * <salt> Hex string or "-" if no salt. |
| */ |
| int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) |
| { |
| struct dm_verity *v; |
| struct dm_arg_set as; |
| unsigned int num; |
| unsigned long long num_ll; |
| int r; |
| int i; |
| sector_t hash_position; |
| char dummy; |
| |
| v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); |
| if (!v) { |
| ti->error = "Cannot allocate verity structure"; |
| return -ENOMEM; |
| } |
| ti->private = v; |
| v->ti = ti; |
| |
| r = verity_fec_ctr_alloc(v); |
| if (r) |
| goto bad; |
| |
| if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { |
| ti->error = "Device must be readonly"; |
| r = -EINVAL; |
| goto bad; |
| } |
| |
| if (argc < 10) { |
| ti->error = "Not enough arguments"; |
| r = -EINVAL; |
| goto bad; |
| } |
| |
| if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || |
| num > 1) { |
| ti->error = "Invalid version"; |
| r = -EINVAL; |
| goto bad; |
| } |
| v->version = num; |
| |
| r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); |
| if (r) { |
| ti->error = "Data device lookup failed"; |
| goto bad; |
| } |
| |
| r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); |
| if (r) { |
| ti->error = "Hash device lookup failed"; |
| goto bad; |
| } |
| |
| if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || |
| !num || (num & (num - 1)) || |
| num < bdev_logical_block_size(v->data_dev->bdev) || |
| num > PAGE_SIZE) { |
| ti->error = "Invalid data device block size"; |
| r = -EINVAL; |
| goto bad; |
| } |
| v->data_dev_block_bits = __ffs(num); |
| |
| if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || |
| !num || (num & (num - 1)) || |
| num < bdev_logical_block_size(v->hash_dev->bdev) || |
| num > INT_MAX) { |
| ti->error = "Invalid hash device block size"; |
| r = -EINVAL; |
| goto bad; |
| } |
| v->hash_dev_block_bits = __ffs(num); |
| |
| if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || |
| (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) |
| >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { |
| ti->error = "Invalid data blocks"; |
| r = -EINVAL; |
| goto bad; |
| } |
| v->data_blocks = num_ll; |
| |
| if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { |
| ti->error = "Data device is too small"; |
| r = -EINVAL; |
| goto bad; |
| } |
| |
| if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || |
| (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) |
| >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { |
| ti->error = "Invalid hash start"; |
| r = -EINVAL; |
| goto bad; |
| } |
| v->hash_start = num_ll; |
| |
| v->alg_name = kstrdup(argv[7], GFP_KERNEL); |
| if (!v->alg_name) { |
| ti->error = "Cannot allocate algorithm name"; |
| r = -ENOMEM; |
| goto bad; |
| } |
| |
| v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0); |
| if (IS_ERR(v->tfm)) { |
| ti->error = "Cannot initialize hash function"; |
| r = PTR_ERR(v->tfm); |
| v->tfm = NULL; |
| goto bad; |
| } |
| |
| /* |
| * dm-verity performance can vary greatly depending on which hash |
| * algorithm implementation is used. Help people debug performance |
| * problems by logging the ->cra_driver_name. |
| */ |
| DMINFO("%s using implementation \"%s\"", v->alg_name, |
| crypto_hash_alg_common(v->tfm)->base.cra_driver_name); |
| |
| v->digest_size = crypto_ahash_digestsize(v->tfm); |
| if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { |
| ti->error = "Digest size too big"; |
| r = -EINVAL; |
| goto bad; |
| } |
| v->ahash_reqsize = sizeof(struct ahash_request) + |
| crypto_ahash_reqsize(v->tfm); |
| |
| v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); |
| if (!v->root_digest) { |
| ti->error = "Cannot allocate root digest"; |
| r = -ENOMEM; |
| goto bad; |
| } |
| if (strlen(argv[8]) != v->digest_size * 2 || |
| hex2bin(v->root_digest, argv[8], v->digest_size)) { |
| ti->error = "Invalid root digest"; |
| r = -EINVAL; |
| goto bad; |
| } |
| |
| if (strcmp(argv[9], "-")) { |
| v->salt_size = strlen(argv[9]) / 2; |
| v->salt = kmalloc(v->salt_size, GFP_KERNEL); |
| if (!v->salt) { |
| ti->error = "Cannot allocate salt"; |
| r = -ENOMEM; |
| goto bad; |
| } |
| if (strlen(argv[9]) != v->salt_size * 2 || |
| hex2bin(v->salt, argv[9], v->salt_size)) { |
| ti->error = "Invalid salt"; |
| r = -EINVAL; |
| goto bad; |
| } |
| } |
| |
| argv += 10; |
| argc -= 10; |
| |
| /* Optional parameters */ |
| if (argc) { |
| as.argc = argc; |
| as.argv = argv; |
| |
| r = verity_parse_opt_args(&as, v); |
| if (r < 0) |
| goto bad; |
| } |
| |
| #ifdef CONFIG_DM_ANDROID_VERITY_AT_MOST_ONCE_DEFAULT_ENABLED |
| if (!v->validated_blocks) { |
| r = verity_alloc_most_once(v); |
| if (r) |
| goto bad; |
| } |
| #endif |
| |
| v->hash_per_block_bits = |
| __fls((1 << v->hash_dev_block_bits) / v->digest_size); |
| |
| v->levels = 0; |
| if (v->data_blocks) |
| while (v->hash_per_block_bits * v->levels < 64 && |
| (unsigned long long)(v->data_blocks - 1) >> |
| (v->hash_per_block_bits * v->levels)) |
| v->levels++; |
| |
| if (v->levels > DM_VERITY_MAX_LEVELS) { |
| ti->error = "Too many tree levels"; |
| r = -E2BIG; |
| goto bad; |
| } |
| |
| hash_position = v->hash_start; |
| for (i = v->levels - 1; i >= 0; i--) { |
| sector_t s; |
| v->hash_level_block[i] = hash_position; |
| s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) |
| >> ((i + 1) * v->hash_per_block_bits); |
| if (hash_position + s < hash_position) { |
| ti->error = "Hash device offset overflow"; |
| r = -E2BIG; |
| goto bad; |
| } |
| hash_position += s; |
| } |
| v->hash_blocks = hash_position; |
| |
| v->bufio = dm_bufio_client_create(v->hash_dev->bdev, |
| 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), |
| dm_bufio_alloc_callback, NULL); |
| if (IS_ERR(v->bufio)) { |
| ti->error = "Cannot initialize dm-bufio"; |
| r = PTR_ERR(v->bufio); |
| v->bufio = NULL; |
| goto bad; |
| } |
| |
| if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { |
| ti->error = "Hash device is too small"; |
| r = -E2BIG; |
| goto bad; |
| } |
| |
| /* WQ_UNBOUND greatly improves performance when running on ramdisk */ |
| v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); |
| if (!v->verify_wq) { |
| ti->error = "Cannot allocate workqueue"; |
| r = -ENOMEM; |
| goto bad; |
| } |
| |
| ti->per_io_data_size = sizeof(struct dm_verity_io) + |
| v->ahash_reqsize + v->digest_size * 2; |
| |
| r = verity_fec_ctr(v); |
| if (r) |
| goto bad; |
| |
| ti->per_io_data_size = roundup(ti->per_io_data_size, |
| __alignof__(struct dm_verity_io)); |
| |
| return 0; |
| |
| bad: |
| verity_dtr(ti); |
| |
| return r; |
| } |
| |
| static struct target_type verity_target = { |
| .name = "verity", |
| .version = {1, 4, 0}, |
| .module = THIS_MODULE, |
| .ctr = verity_ctr, |
| .dtr = verity_dtr, |
| .map = verity_map, |
| .status = verity_status, |
| .prepare_ioctl = verity_prepare_ioctl, |
| .iterate_devices = verity_iterate_devices, |
| .io_hints = verity_io_hints, |
| }; |
| |
| static int __init dm_verity_init(void) |
| { |
| int r; |
| |
| r = dm_register_target(&verity_target); |
| if (r < 0) |
| DMERR("register failed %d", r); |
| |
| return r; |
| } |
| |
| static void __exit dm_verity_exit(void) |
| { |
| dm_unregister_target(&verity_target); |
| } |
| |
| module_init(dm_verity_init); |
| module_exit(dm_verity_exit); |
| |
| MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); |
| MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); |
| MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); |
| MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); |
| MODULE_LICENSE("GPL"); |