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- /*
- * 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_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) {
- #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;
- }
- /*
- * Skip verity work in response to I/O error when system is shutting down.
- */
- static inline bool verity_is_system_shutting_down(void)
- {
- return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
- || system_state == SYSTEM_RESTART;
- }
- /*
- * End one "io" structure with a given error.
- */
- static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
- {
- struct dm_verity *v = io->v;
- struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
- bio->bi_end_io = io->orig_bi_end_io;
- bio->bi_status = status;
- verity_fec_finish_io(io);
- bio_endio(bio);
- }
- static void verity_work(struct work_struct *w)
- {
- struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
- verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
- }
- static void verity_end_io(struct bio *bio)
- {
- struct dm_verity_io *io = bio->bi_private;
- if (bio->bi_status &&
- (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
- verity_finish_io(io, bio->bi_status);
- return;
- }
- INIT_WORK(&io->work, verity_work);
- queue_work(io->v->verify_wq, &io->work);
- }
- /*
- * Prefetch buffers for the specified io.
- * The root buffer is not prefetched, it is assumed that it will be cached
- * all the time.
- */
- static void verity_prefetch_io(struct work_struct *work)
- {
- struct dm_verity_prefetch_work *pw =
- container_of(work, struct dm_verity_prefetch_work, work);
- struct dm_verity *v = pw->v;
- int i;
- for (i = v->levels - 2; i >= 0; i--) {
- sector_t hash_block_start;
- sector_t hash_block_end;
- verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
- verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
- if (!i) {
- unsigned cluster = 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");
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