diff options
Diffstat (limited to 'drivers/md/dm-verity-target.c')
| -rw-r--r-- | drivers/md/dm-verity-target.c | 1721 |
1 files changed, 1721 insertions, 0 deletions
diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c new file mode 100644 index 000000000000..66a00a8ccb39 --- /dev/null +++ b/drivers/md/dm-verity-target.c @@ -0,0 +1,1721 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Red Hat, Inc. + * + * Author: Mikulas Patocka <mpatocka@redhat.com> + * + * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors + * + * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set + * default prefetch value. Data are read in "prefetch_cluster" chunks from the + * hash device. Setting this greatly improves performance when data and hash + * are on the same disk on different partitions on devices with poor random + * access behavior. + */ + +#include "dm-verity.h" +#include "dm-verity-fec.h" +#include "dm-verity-verify-sig.h" +#include "dm-audit.h" +#include <linux/module.h> +#include <linux/reboot.h> +#include <linux/string.h> +#include <linux/jump_label.h> +#include <linux/security.h> + +#define DM_MSG_PREFIX "verity" + +#define DM_VERITY_ENV_LENGTH 42 +#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" + +#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 +#define DM_VERITY_USE_BH_DEFAULT_BYTES 8192 + +#define DM_VERITY_MAX_CORRUPTED_ERRS 100 + +#define DM_VERITY_OPT_LOGGING "ignore_corruption" +#define DM_VERITY_OPT_RESTART "restart_on_corruption" +#define DM_VERITY_OPT_PANIC "panic_on_corruption" +#define DM_VERITY_OPT_ERROR_RESTART "restart_on_error" +#define DM_VERITY_OPT_ERROR_PANIC "panic_on_error" +#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" +#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" +#define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet" + +#define DM_VERITY_OPTS_MAX (5 + DM_VERITY_OPTS_FEC + \ + DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) + +static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; + +module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644); + +static unsigned int dm_verity_use_bh_bytes[4] = { + DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_NONE + DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_RT + DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_BE + 0 // IOPRIO_CLASS_IDLE +}; + +module_param_array_named(use_bh_bytes, dm_verity_use_bh_bytes, uint, NULL, 0644); + +static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled); + +struct dm_verity_prefetch_work { + struct work_struct work; + struct dm_verity *v; + unsigned short ioprio; + sector_t block; + unsigned int n_blocks; +}; + +/* + * Auxiliary structure appended to each dm-bufio buffer. If the value + * hash_verified is nonzero, hash of the block has been verified. + * + * The variable hash_verified is set to 0 when allocating the buffer, then + * it can be changed to 1 and it is never reset to 0 again. + * + * There is no lock around this value, a race condition can at worst cause + * that multiple processes verify the hash of the same buffer simultaneously + * and write 1 to hash_verified simultaneously. + * This condition is harmless, so we don't need locking. + */ +struct buffer_aux { + int hash_verified; +}; + +/* + * Initialize struct buffer_aux for a freshly created buffer. + */ +static void dm_bufio_alloc_callback(struct dm_buffer *buf) +{ + struct buffer_aux *aux = dm_bufio_get_aux_data(buf); + + aux->hash_verified = 0; +} + +/* + * Translate input sector number to the sector number on the target device. + */ +static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) +{ + return dm_target_offset(v->ti, bi_sector); +} + +/* + * Return hash position of a specified block at a specified tree level + * (0 is the lowest level). + * The lowest "hash_per_block_bits"-bits of the result denote hash position + * inside a hash block. The remaining bits denote location of the hash block. + */ +static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, + int level) +{ + return block >> (level * v->hash_per_block_bits); +} + +int verity_hash(struct dm_verity *v, struct dm_verity_io *io, + const u8 *data, size_t len, u8 *digest) +{ + struct shash_desc *desc = &io->hash_desc; + int r; + + desc->tfm = v->shash_tfm; + if (unlikely(v->initial_hashstate == NULL)) { + /* Version 0: salt at end */ + r = crypto_shash_init(desc) ?: + crypto_shash_update(desc, data, len) ?: + crypto_shash_update(desc, v->salt, v->salt_size) ?: + crypto_shash_final(desc, digest); + } else { + /* Version 1: salt at beginning */ + r = crypto_shash_import(desc, v->initial_hashstate) ?: + crypto_shash_finup(desc, data, len, digest); + } + if (unlikely(r)) + DMERR("Error hashing block: %d", r); + return r; +} + +static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, + sector_t *hash_block, unsigned int *offset) +{ + sector_t position = verity_position_at_level(v, block, level); + unsigned int idx; + + *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); + + if (!offset) + return; + + idx = position & ((1 << v->hash_per_block_bits) - 1); + if (!v->version) + *offset = idx * v->digest_size; + else + *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); +} + +/* + * Handle verification errors. + */ +static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, + unsigned long long block) +{ + char verity_env[DM_VERITY_ENV_LENGTH]; + char *envp[] = { verity_env, NULL }; + const char *type_str = ""; + struct mapped_device *md = dm_table_get_md(v->ti->table); + + /* Corruption should be visible in device status in all modes */ + v->hash_failed = true; + + if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) + goto out; + + v->corrupted_errs++; + + switch (type) { + case DM_VERITY_BLOCK_TYPE_DATA: + type_str = "data"; + break; + case DM_VERITY_BLOCK_TYPE_METADATA: + type_str = "metadata"; + break; + default: + BUG(); + } + + DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, + type_str, block); + + if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { + DMERR("%s: reached maximum errors", v->data_dev->name); + dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); + } + + snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", + DM_VERITY_ENV_VAR_NAME, type, block); + + kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); + +out: + if (v->mode == DM_VERITY_MODE_LOGGING) + return 0; + + if (v->mode == DM_VERITY_MODE_RESTART) + kernel_restart("dm-verity device corrupted"); + + if (v->mode == DM_VERITY_MODE_PANIC) + panic("dm-verity device corrupted"); + + return 1; +} + +/* + * Verify hash of a metadata block pertaining to the specified data block + * ("block" argument) at a specified level ("level" argument). + * + * On successful return, verity_io_want_digest(v, io) contains the hash value + * for a lower tree level or for the data block (if we're at the lowest level). + * + * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. + * If "skip_unverified" is false, unverified buffer is hashed and verified + * against current value of verity_io_want_digest(v, io). + */ +static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, + sector_t block, int level, bool skip_unverified, + u8 *want_digest) +{ + struct dm_buffer *buf; + struct buffer_aux *aux; + u8 *data; + int r; + sector_t hash_block; + unsigned int offset; + struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); + + verity_hash_at_level(v, block, level, &hash_block, &offset); + + if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { + data = dm_bufio_get(v->bufio, hash_block, &buf); + if (IS_ERR_OR_NULL(data)) { + /* + * In tasklet and the hash was not in the bufio cache. + * Return early and resume execution from a work-queue + * to read the hash from disk. + */ + return -EAGAIN; + } + } else { + data = dm_bufio_read_with_ioprio(v->bufio, hash_block, + &buf, bio->bi_ioprio); + } + + if (IS_ERR(data)) { + if (skip_unverified) + return 1; + r = PTR_ERR(data); + data = dm_bufio_new(v->bufio, hash_block, &buf); + if (IS_ERR(data)) + return r; + if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, + hash_block, data) == 0) { + aux = dm_bufio_get_aux_data(buf); + aux->hash_verified = 1; + goto release_ok; + } else { + dm_bufio_release(buf); + dm_bufio_forget(v->bufio, hash_block); + return r; + } + } + + aux = dm_bufio_get_aux_data(buf); + + if (!aux->hash_verified) { + if (skip_unverified) { + r = 1; + goto release_ret_r; + } + + r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits, + verity_io_real_digest(v, io)); + if (unlikely(r < 0)) + goto release_ret_r; + + if (likely(memcmp(verity_io_real_digest(v, io), want_digest, + v->digest_size) == 0)) + aux->hash_verified = 1; + else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { + /* + * Error handling code (FEC included) cannot be run in a + * tasklet since it may sleep, so fallback to work-queue. + */ + r = -EAGAIN; + goto release_ret_r; + } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, + hash_block, data) == 0) + aux->hash_verified = 1; + else if (verity_handle_err(v, + DM_VERITY_BLOCK_TYPE_METADATA, + hash_block)) { + struct bio *bio; + io->had_mismatch = true; + bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); + dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, + block, 0); + r = -EIO; + goto release_ret_r; + } + } + +release_ok: + data += offset; + memcpy(want_digest, data, v->digest_size); + r = 0; + +release_ret_r: + dm_bufio_release(buf); + return r; +} + +/* + * Find a hash for a given block, write it to digest and verify the integrity + * of the hash tree if necessary. + */ +int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, + sector_t block, u8 *digest, bool *is_zero) +{ + int r = 0, i; + + if (likely(v->levels)) { + /* + * First, we try to get the requested hash for + * the current block. If the hash block itself is + * verified, zero is returned. If it isn't, this + * function returns 1 and we fall back to whole + * chain verification. + */ + r = verity_verify_level(v, io, block, 0, true, digest); + if (likely(r <= 0)) + goto out; + } + + memcpy(digest, v->root_digest, v->digest_size); + + for (i = v->levels - 1; i >= 0; i--) { + r = verity_verify_level(v, io, block, i, false, digest); + if (unlikely(r)) + goto out; + } +out: + if (!r && v->zero_digest) + *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); + else + *is_zero = false; + + return r; +} + +static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io, + sector_t cur_block, u8 *dest) +{ + struct page *page; + void *buffer; + int r; + struct dm_io_request io_req; + struct dm_io_region io_loc; + + page = mempool_alloc(&v->recheck_pool, GFP_NOIO); + buffer = page_to_virt(page); + + io_req.bi_opf = REQ_OP_READ; + io_req.mem.type = DM_IO_KMEM; + io_req.mem.ptr.addr = buffer; + io_req.notify.fn = NULL; + io_req.client = v->io; + io_loc.bdev = v->data_dev->bdev; + io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT); + io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT); + r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT); + if (unlikely(r)) + goto free_ret; + + r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits, + verity_io_real_digest(v, io)); + if (unlikely(r)) + goto free_ret; + + if (memcmp(verity_io_real_digest(v, io), + verity_io_want_digest(v, io), v->digest_size)) { + r = -EIO; + goto free_ret; + } + + memcpy(dest, buffer, 1 << v->data_dev_block_bits); + r = 0; +free_ret: + mempool_free(page, &v->recheck_pool); + + return r; +} + +static int verity_handle_data_hash_mismatch(struct dm_verity *v, + struct dm_verity_io *io, + struct bio *bio, sector_t blkno, + u8 *data) +{ + if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { + /* + * Error handling code (FEC included) cannot be run in the + * BH workqueue, so fallback to a standard workqueue. + */ + return -EAGAIN; + } + if (verity_recheck(v, io, blkno, data) == 0) { + if (v->validated_blocks) + set_bit(blkno, v->validated_blocks); + return 0; + } +#if defined(CONFIG_DM_VERITY_FEC) + if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno, + data) == 0) + return 0; +#endif + if (bio->bi_status) + return -EIO; /* Error correction failed; Just return error */ + + if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) { + io->had_mismatch = true; + dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0); + return -EIO; + } + return 0; +} + +/* + * Verify one "dm_verity_io" structure. + */ +static int verity_verify_io(struct dm_verity_io *io) +{ + struct dm_verity *v = io->v; + const unsigned int block_size = 1 << v->data_dev_block_bits; + struct bvec_iter iter_copy; + struct bvec_iter *iter; + struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); + unsigned int b; + + if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { + /* + * Copy the iterator in case we need to restart + * verification in a work-queue. + */ + iter_copy = io->iter; + iter = &iter_copy; + } else + iter = &io->iter; + + for (b = 0; b < io->n_blocks; + b++, bio_advance_iter(bio, iter, block_size)) { + int r; + sector_t cur_block = io->block + b; + bool is_zero; + struct bio_vec bv; + void *data; + + if (v->validated_blocks && bio->bi_status == BLK_STS_OK && + likely(test_bit(cur_block, v->validated_blocks))) + continue; + + r = verity_hash_for_block(v, io, cur_block, + verity_io_want_digest(v, io), + &is_zero); + if (unlikely(r < 0)) + return r; + + bv = bio_iter_iovec(bio, *iter); + if (unlikely(bv.bv_len < block_size)) { + /* + * Data block spans pages. This should not happen, + * since dm-verity sets dma_alignment to the data block + * size minus 1, and dm-verity also doesn't allow the + * data block size to be greater than PAGE_SIZE. + */ + DMERR_LIMIT("unaligned io (data block spans pages)"); + return -EIO; + } + + data = bvec_kmap_local(&bv); + + if (is_zero) { + /* + * If we expect a zero block, don't validate, just + * return zeros. + */ + memset(data, 0, block_size); + kunmap_local(data); + continue; + } + + r = verity_hash(v, io, data, block_size, + verity_io_real_digest(v, io)); + if (unlikely(r < 0)) { + kunmap_local(data); + return r; + } + + if (likely(memcmp(verity_io_real_digest(v, io), + verity_io_want_digest(v, io), v->digest_size) == 0)) { + if (v->validated_blocks) + set_bit(cur_block, v->validated_blocks); + kunmap_local(data); + continue; + } + r = verity_handle_data_hash_mismatch(v, io, bio, cur_block, + data); + kunmap_local(data); + if (unlikely(r)) + return r; + } + + return 0; +} + +/* + * Skip verity work in response to I/O error when system is shutting down. + */ +static inline bool verity_is_system_shutting_down(void) +{ + return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF + || system_state == SYSTEM_RESTART; +} + +static void restart_io_error(struct work_struct *w) +{ + kernel_restart("dm-verity device has I/O error"); +} + +/* + * End one "io" structure with a given error. + */ +static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) +{ + struct dm_verity *v = io->v; + struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); + + bio->bi_end_io = io->orig_bi_end_io; + bio->bi_status = status; + + if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh) + verity_fec_finish_io(io); + + if (unlikely(status != BLK_STS_OK) && + unlikely(!(bio->bi_opf & REQ_RAHEAD)) && + !io->had_mismatch && + !verity_is_system_shutting_down()) { + if (v->error_mode == DM_VERITY_MODE_PANIC) { + panic("dm-verity device has I/O error"); + } + if (v->error_mode == DM_VERITY_MODE_RESTART) { + static DECLARE_WORK(restart_work, restart_io_error); + queue_work(v->verify_wq, &restart_work); + /* + * We deliberately don't call bio_endio here, because + * the machine will be restarted anyway. + */ + return; + } + } + + bio_endio(bio); +} + +static void verity_work(struct work_struct *w) +{ + struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); + + io->in_bh = false; + + verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); +} + +static void verity_bh_work(struct work_struct *w) +{ + struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work); + int err; + + io->in_bh = true; + err = verity_verify_io(io); + if (err == -EAGAIN || err == -ENOMEM) { + /* fallback to retrying with work-queue */ + INIT_WORK(&io->work, verity_work); + queue_work(io->v->verify_wq, &io->work); + return; + } + + verity_finish_io(io, errno_to_blk_status(err)); +} + +static inline bool verity_use_bh(unsigned int bytes, unsigned short ioprio) +{ + return ioprio <= IOPRIO_CLASS_IDLE && + bytes <= READ_ONCE(dm_verity_use_bh_bytes[ioprio]) && + !need_resched(); +} + +static void verity_end_io(struct bio *bio) +{ + struct dm_verity_io *io = bio->bi_private; + unsigned short ioprio = IOPRIO_PRIO_CLASS(bio->bi_ioprio); + unsigned int bytes = io->n_blocks << io->v->data_dev_block_bits; + + if (bio->bi_status && + (!verity_fec_is_enabled(io->v) || + verity_is_system_shutting_down() || + (bio->bi_opf & REQ_RAHEAD))) { + verity_finish_io(io, bio->bi_status); + return; + } + + if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq && + verity_use_bh(bytes, ioprio)) { + if (in_hardirq() || irqs_disabled()) { + INIT_WORK(&io->bh_work, verity_bh_work); + queue_work(system_bh_wq, &io->bh_work); + } else { + verity_bh_work(&io->bh_work); + } + } else { + INIT_WORK(&io->work, verity_work); + queue_work(io->v->verify_wq, &io->work); + } +} + +/* + * Prefetch buffers for the specified io. + * The root buffer is not prefetched, it is assumed that it will be cached + * all the time. + */ +static void verity_prefetch_io(struct work_struct *work) +{ + struct dm_verity_prefetch_work *pw = + container_of(work, struct dm_verity_prefetch_work, work); + struct dm_verity *v = pw->v; + int i; + + for (i = v->levels - 2; i >= 0; i--) { + sector_t hash_block_start; + sector_t hash_block_end; + + verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); + verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); + + if (!i) { + unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); + + cluster >>= v->data_dev_block_bits; + if (unlikely(!cluster)) + goto no_prefetch_cluster; + + if (unlikely(cluster & (cluster - 1))) + cluster = 1 << __fls(cluster); + + hash_block_start &= ~(sector_t)(cluster - 1); + hash_block_end |= cluster - 1; + if (unlikely(hash_block_end >= v->hash_blocks)) + hash_block_end = v->hash_blocks - 1; + } +no_prefetch_cluster: + dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start, + hash_block_end - hash_block_start + 1, + pw->ioprio); + } + + kfree(pw); +} + +static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io, + unsigned short ioprio) +{ + sector_t block = io->block; + unsigned int n_blocks = io->n_blocks; + struct dm_verity_prefetch_work *pw; + + if (v->validated_blocks) { + while (n_blocks && test_bit(block, v->validated_blocks)) { + block++; + n_blocks--; + } + while (n_blocks && test_bit(block + n_blocks - 1, + v->validated_blocks)) + n_blocks--; + if (!n_blocks) + return; + } + + pw = kmalloc(sizeof(struct dm_verity_prefetch_work), + GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); + + if (!pw) + return; + + INIT_WORK(&pw->work, verity_prefetch_io); + pw->v = v; + pw->block = block; + pw->n_blocks = n_blocks; + pw->ioprio = ioprio; + queue_work(v->verify_wq, &pw->work); +} + +/* + * Bio map function. It allocates dm_verity_io structure and bio vector and + * fills them. Then it issues prefetches and the I/O. + */ +static int verity_map(struct dm_target *ti, struct bio *bio) +{ + struct dm_verity *v = ti->private; + struct dm_verity_io *io; + + bio_set_dev(bio, v->data_dev->bdev); + bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); + + if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & + ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { + DMERR_LIMIT("unaligned io"); + return DM_MAPIO_KILL; + } + + if (bio_end_sector(bio) >> + (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { + DMERR_LIMIT("io out of range"); + return DM_MAPIO_KILL; + } + + if (bio_data_dir(bio) == WRITE) + return DM_MAPIO_KILL; + + io = dm_per_bio_data(bio, ti->per_io_data_size); + io->v = v; + io->orig_bi_end_io = bio->bi_end_io; + io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); + io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; + io->had_mismatch = false; + + bio->bi_end_io = verity_end_io; + bio->bi_private = io; + io->iter = bio->bi_iter; + + verity_fec_init_io(io); + + verity_submit_prefetch(v, io, bio->bi_ioprio); + + submit_bio_noacct(bio); + + return DM_MAPIO_SUBMITTED; +} + +static void verity_postsuspend(struct dm_target *ti) +{ + struct dm_verity *v = ti->private; + flush_workqueue(v->verify_wq); + dm_bufio_client_reset(v->bufio); +} + +/* + * Status: V (valid) or C (corruption found) + */ +static void verity_status(struct dm_target *ti, status_type_t type, + unsigned int status_flags, char *result, unsigned int maxlen) +{ + struct dm_verity *v = ti->private; + unsigned int args = 0; + unsigned int sz = 0; + unsigned int x; + + switch (type) { + case STATUSTYPE_INFO: + DMEMIT("%c", v->hash_failed ? 'C' : 'V'); + break; + case STATUSTYPE_TABLE: + DMEMIT("%u %s %s %u %u %llu %llu %s ", + v->version, + v->data_dev->name, + v->hash_dev->name, + 1 << v->data_dev_block_bits, + 1 << v->hash_dev_block_bits, + (unsigned long long)v->data_blocks, + (unsigned long long)v->hash_start, + v->alg_name + ); + for (x = 0; x < v->digest_size; x++) + DMEMIT("%02x", v->root_digest[x]); + DMEMIT(" "); + if (!v->salt_size) + DMEMIT("-"); + else + for (x = 0; x < v->salt_size; x++) + DMEMIT("%02x", v->salt[x]); + if (v->mode != DM_VERITY_MODE_EIO) + args++; + if (v->error_mode != DM_VERITY_MODE_EIO) + args++; + if (verity_fec_is_enabled(v)) + args += DM_VERITY_OPTS_FEC; + if (v->zero_digest) + args++; + if (v->validated_blocks) + args++; + if (v->use_bh_wq) + args++; + if (v->signature_key_desc) + args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; + if (!args) + return; + DMEMIT(" %u", args); + if (v->mode != DM_VERITY_MODE_EIO) { + DMEMIT(" "); + switch (v->mode) { + case DM_VERITY_MODE_LOGGING: + DMEMIT(DM_VERITY_OPT_LOGGING); + break; + case DM_VERITY_MODE_RESTART: + DMEMIT(DM_VERITY_OPT_RESTART); + break; + case DM_VERITY_MODE_PANIC: + DMEMIT(DM_VERITY_OPT_PANIC); + break; + default: + BUG(); + } + } + if (v->error_mode != DM_VERITY_MODE_EIO) { + DMEMIT(" "); + switch (v->error_mode) { + case DM_VERITY_MODE_RESTART: + DMEMIT(DM_VERITY_OPT_ERROR_RESTART); + break; + case DM_VERITY_MODE_PANIC: + DMEMIT(DM_VERITY_OPT_ERROR_PANIC); + break; + default: + BUG(); + } + } + if (v->zero_digest) + DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); + if (v->validated_blocks) + DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); + if (v->use_bh_wq) + DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); + sz = verity_fec_status_table(v, sz, result, maxlen); + if (v->signature_key_desc) + DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY + " %s", v->signature_key_desc); + break; + + case STATUSTYPE_IMA: + DMEMIT_TARGET_NAME_VERSION(ti->type); + DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); + DMEMIT(",verity_version=%u", v->version); + DMEMIT(",data_device_name=%s", v->data_dev->name); + DMEMIT(",hash_device_name=%s", v->hash_dev->name); + DMEMIT(",verity_algorithm=%s", v->alg_name); + + DMEMIT(",root_digest="); + for (x = 0; x < v->digest_size; x++) + DMEMIT("%02x", v->root_digest[x]); + + DMEMIT(",salt="); + if (!v->salt_size) + DMEMIT("-"); + else + for (x = 0; x < v->salt_size; x++) + DMEMIT("%02x", v->salt[x]); + + DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); + DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); + if (v->signature_key_desc) + DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); + + if (v->mode != DM_VERITY_MODE_EIO) { + DMEMIT(",verity_mode="); + switch (v->mode) { + case DM_VERITY_MODE_LOGGING: + DMEMIT(DM_VERITY_OPT_LOGGING); + break; + case DM_VERITY_MODE_RESTART: + DMEMIT(DM_VERITY_OPT_RESTART); + break; + case DM_VERITY_MODE_PANIC: + DMEMIT(DM_VERITY_OPT_PANIC); + break; + default: + DMEMIT("invalid"); + } + } + if (v->error_mode != DM_VERITY_MODE_EIO) { + DMEMIT(",verity_error_mode="); + switch (v->error_mode) { + case DM_VERITY_MODE_RESTART: + DMEMIT(DM_VERITY_OPT_ERROR_RESTART); + break; + case DM_VERITY_MODE_PANIC: + DMEMIT(DM_VERITY_OPT_ERROR_PANIC); + break; + default: + DMEMIT("invalid"); + } + } + DMEMIT(";"); + break; + } +} + +static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev, + unsigned int cmd, unsigned long arg, + bool *forward) +{ + struct dm_verity *v = ti->private; + + *bdev = v->data_dev->bdev; + + if (ti->len != bdev_nr_sectors(v->data_dev->bdev)) + return 1; + return 0; +} + +static int verity_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, void *data) +{ + struct dm_verity *v = ti->private; + + return fn(ti, v->data_dev, 0, ti->len, data); +} + +static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) +{ + struct dm_verity *v = ti->private; + + if (limits->logical_block_size < 1 << v->data_dev_block_bits) + limits->logical_block_size = 1 << v->data_dev_block_bits; + + if (limits->physical_block_size < 1 << v->data_dev_block_bits) + limits->physical_block_size = 1 << v->data_dev_block_bits; + + limits->io_min = limits->logical_block_size; + + /* + * Similar to what dm-crypt does, opt dm-verity out of support for + * direct I/O that is aligned to less than the traditional direct I/O + * alignment requirement of logical_block_size. This prevents dm-verity + * data blocks from crossing pages, eliminating various edge cases. + */ + limits->dma_alignment = limits->logical_block_size - 1; +} + +#ifdef CONFIG_SECURITY + +static int verity_init_sig(struct dm_verity *v, const void *sig, + size_t sig_size) +{ + v->sig_size = sig_size; + + if (sig) { + v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL); + if (!v->root_digest_sig) + return -ENOMEM; + } + + return 0; +} + +static void verity_free_sig(struct dm_verity *v) +{ + kfree(v->root_digest_sig); +} + +#else + +static inline int verity_init_sig(struct dm_verity *v, const void *sig, + size_t sig_size) +{ + return 0; +} + +static inline void verity_free_sig(struct dm_verity *v) +{ +} + +#endif /* CONFIG_SECURITY */ + +static void verity_dtr(struct dm_target *ti) +{ + struct dm_verity *v = ti->private; + + if (v->verify_wq) + destroy_workqueue(v->verify_wq); + + mempool_exit(&v->recheck_pool); + if (v->io) + dm_io_client_destroy(v->io); + + if (v->bufio) + dm_bufio_client_destroy(v->bufio); + + kvfree(v->validated_blocks); + kfree(v->salt); + kfree(v->initial_hashstate); + kfree(v->root_digest); + kfree(v->zero_digest); + verity_free_sig(v); + + crypto_free_shash(v->shash_tfm); + + kfree(v->alg_name); + + if (v->hash_dev) + dm_put_device(ti, v->hash_dev); + + if (v->data_dev) + dm_put_device(ti, v->data_dev); + + verity_fec_dtr(v); + + kfree(v->signature_key_desc); + + if (v->use_bh_wq) + static_branch_dec(&use_bh_wq_enabled); + + kfree(v); + + dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); +} + +static int verity_alloc_most_once(struct dm_verity *v) +{ + struct dm_target *ti = v->ti; + + if (v->validated_blocks) + return 0; + + /* 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 dm_verity_io *io; + u8 *zero_data; + + if (v->zero_digest) + return 0; + + v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); + + if (!v->zero_digest) + return r; + + io = kmalloc(sizeof(*io) + crypto_shash_descsize(v->shash_tfm), + GFP_KERNEL); + + if (!io) + 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, io, zero_data, 1 << v->data_dev_block_bits, + v->zero_digest); + +out: + kfree(io); + kfree(zero_data); + + return r; +} + +static inline bool verity_is_verity_mode(const char *arg_name) +{ + return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || + !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || + !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); +} + +static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) +{ + if (v->mode) + return -EINVAL; + + if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) + v->mode = DM_VERITY_MODE_LOGGING; + else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) + v->mode = DM_VERITY_MODE_RESTART; + else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) + v->mode = DM_VERITY_MODE_PANIC; + + return 0; +} + +static inline bool verity_is_verity_error_mode(const char *arg_name) +{ + return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) || + !strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC)); +} + +static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name) +{ + if (v->error_mode) + return -EINVAL; + + if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART)) + v->error_mode = DM_VERITY_MODE_RESTART; + else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC)) + v->error_mode = DM_VERITY_MODE_PANIC; + + return 0; +} + +static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, + struct dm_verity_sig_opts *verify_args, + bool only_modifier_opts) +{ + int r = 0; + unsigned int argc; + struct dm_target *ti = v->ti; + const char *arg_name; + + static const struct dm_arg _args[] = { + {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, + }; + + r = dm_read_arg_group(_args, as, &argc, &ti->error); + if (r) + return -EINVAL; + + if (!argc) + return 0; + + do { + arg_name = dm_shift_arg(as); + argc--; + + if (verity_is_verity_mode(arg_name)) { + if (only_modifier_opts) + continue; + r = verity_parse_verity_mode(v, arg_name); + if (r) { + ti->error = "Conflicting error handling parameters"; + return r; + } + continue; + + } else if (verity_is_verity_error_mode(arg_name)) { + if (only_modifier_opts) + continue; + r = verity_parse_verity_error_mode(v, arg_name); + if (r) { + ti->error = "Conflicting error handling parameters"; + return r; + } + continue; + + } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { + if (only_modifier_opts) + continue; + r = verity_alloc_zero_digest(v); + if (r) { + ti->error = "Cannot allocate zero digest"; + return r; + } + continue; + + } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { + if (only_modifier_opts) + continue; + r = verity_alloc_most_once(v); + if (r) + return r; + continue; + + } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { + v->use_bh_wq = true; + static_branch_inc(&use_bh_wq_enabled); + continue; + + } else if (verity_is_fec_opt_arg(arg_name)) { + if (only_modifier_opts) + continue; + r = verity_fec_parse_opt_args(as, v, &argc, arg_name); + if (r) + return r; + continue; + + } else if (verity_verify_is_sig_opt_arg(arg_name)) { + if (only_modifier_opts) + continue; + r = verity_verify_sig_parse_opt_args(as, v, + verify_args, + &argc, arg_name); + if (r) + return r; + continue; + + } else if (only_modifier_opts) { + /* + * Ignore unrecognized opt, could easily be an extra + * argument to an option whose parsing was skipped. + * Normal parsing (@only_modifier_opts=false) will + * properly parse all options (and their extra args). + */ + continue; + } + + DMERR("Unrecognized verity feature request: %s", arg_name); + ti->error = "Unrecognized verity feature request"; + return -EINVAL; + } while (argc && !r); + + return r; +} + +static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name) +{ + struct dm_target *ti = v->ti; + struct crypto_shash *shash; + + v->alg_name = kstrdup(alg_name, GFP_KERNEL); + if (!v->alg_name) { + ti->error = "Cannot allocate algorithm name"; + return -ENOMEM; + } + + shash = crypto_alloc_shash(alg_name, 0, 0); + if (IS_ERR(shash)) { + ti->error = "Cannot initialize hash function"; + return PTR_ERR(shash); + } + v->shash_tfm = shash; + v->digest_size = crypto_shash_digestsize(shash); + DMINFO("%s using \"%s\"", alg_name, crypto_shash_driver_name(shash)); + if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { + ti->error = "Digest size too big"; + return -EINVAL; + } + return 0; +} + +static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg) +{ + struct dm_target *ti = v->ti; + + if (strcmp(arg, "-") != 0) { + v->salt_size = strlen(arg) / 2; + v->salt = kmalloc(v->salt_size, GFP_KERNEL); + if (!v->salt) { + ti->error = "Cannot allocate salt"; + return -ENOMEM; + } + if (strlen(arg) != v->salt_size * 2 || + hex2bin(v->salt, arg, v->salt_size)) { + ti->error = "Invalid salt"; + return -EINVAL; + } + } + if (v->version) { /* Version 1: salt at beginning */ + SHASH_DESC_ON_STACK(desc, v->shash_tfm); + int r; + + /* + * Compute the pre-salted hash state that can be passed to + * crypto_shash_import() for each block later. + */ + v->initial_hashstate = kmalloc( + crypto_shash_statesize(v->shash_tfm), GFP_KERNEL); + if (!v->initial_hashstate) { + ti->error = "Cannot allocate initial hash state"; + return -ENOMEM; + } + desc->tfm = v->shash_tfm; + r = crypto_shash_init(desc) ?: + crypto_shash_update(desc, v->salt, v->salt_size) ?: + crypto_shash_export(desc, v->initial_hashstate); + if (r) { + ti->error = "Cannot set up initial hash state"; + return r; + } + } + return 0; +} + +/* + * Target parameters: + * <version> The current format is version 1. + * Vsn 0 is compatible with original Chromium OS releases. + * <data device> + * <hash device> + * <data block size> + * <hash block size> + * <the number of data blocks> + * <hash start block> + * <algorithm> + * <digest> + * <salt> Hex string or "-" if no salt. + */ +static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) +{ + struct dm_verity *v; + struct dm_verity_sig_opts verify_args = {0}; + struct dm_arg_set as; + unsigned int num; + unsigned long long num_ll; + int r; + int i; + sector_t hash_position; + char dummy; + char *root_hash_digest_to_validate; + + v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); + if (!v) { + ti->error = "Cannot allocate verity structure"; + return -ENOMEM; + } + ti->private = v; + v->ti = ti; + + r = verity_fec_ctr_alloc(v); + if (r) + goto bad; + + if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { + ti->error = "Device must be readonly"; + r = -EINVAL; + goto bad; + } + + if (argc < 10) { + ti->error = "Not enough arguments"; + r = -EINVAL; + goto bad; + } + + /* Parse optional parameters that modify primary args */ + if (argc > 10) { + as.argc = argc - 10; + as.argv = argv + 10; + r = verity_parse_opt_args(&as, v, &verify_args, true); + if (r < 0) + goto bad; + } + + if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || + num > 1) { + ti->error = "Invalid version"; + r = -EINVAL; + goto bad; + } + v->version = num; + + r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); + if (r) { + ti->error = "Data device lookup failed"; + goto bad; + } + + r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); + if (r) { + ti->error = "Hash device lookup failed"; + goto bad; + } + + if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || + !num || (num & (num - 1)) || + num < bdev_logical_block_size(v->data_dev->bdev) || + num > PAGE_SIZE) { + ti->error = "Invalid data device block size"; + r = -EINVAL; + goto bad; + } + v->data_dev_block_bits = __ffs(num); + + if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || + !num || (num & (num - 1)) || + num < bdev_logical_block_size(v->hash_dev->bdev) || + num > INT_MAX) { + ti->error = "Invalid hash device block size"; + r = -EINVAL; + goto bad; + } + v->hash_dev_block_bits = __ffs(num); + + if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || + (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) + >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { + ti->error = "Invalid data blocks"; + r = -EINVAL; + goto bad; + } + v->data_blocks = num_ll; + + if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { + ti->error = "Data device is too small"; + r = -EINVAL; + goto bad; + } + + if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || + (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) + >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { + ti->error = "Invalid hash start"; + r = -EINVAL; + goto bad; + } + v->hash_start = num_ll; + + r = verity_setup_hash_alg(v, argv[7]); + if (r) + goto bad; + + 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]; + + r = verity_setup_salt_and_hashstate(v, argv[9]); + if (r) + goto bad; + + argv += 10; + argc -= 10; + + /* Optional parameters */ + if (argc) { + as.argc = argc; + as.argv = argv; + r = verity_parse_opt_args(&as, v, &verify_args, false); + if (r < 0) + goto bad; + } + + /* Root hash signature is an 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; + } + + r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); + if (r < 0) { + ti->error = "Cannot allocate root digest signature"; + 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; + + r = mempool_init_page_pool(&v->recheck_pool, 1, 0); + if (unlikely(r)) { + ti->error = "Cannot allocate mempool"; + goto bad; + } + + v->io = dm_io_client_create(); + if (IS_ERR(v->io)) { + r = PTR_ERR(v->io); + v->io = NULL; + ti->error = "Cannot allocate dm io"; + goto bad; + } + + v->bufio = dm_bufio_client_create(v->hash_dev->bdev, + 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), + dm_bufio_alloc_callback, NULL, + v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0); + if (IS_ERR(v->bufio)) { + ti->error = "Cannot initialize dm-bufio"; + r = PTR_ERR(v->bufio); + v->bufio = NULL; + goto bad; + } + + if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { + ti->error = "Hash device is too small"; + r = -E2BIG; + goto bad; + } + + /* + * Using WQ_HIGHPRI improves throughput and completion latency by + * reducing wait times when reading from a dm-verity device. + * + * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI + * allows verify_wq to preempt softirq since verification in BH workqueue + * will fall-back to using it for error handling (or if the bufio cache + * doesn't have required hashes). + */ + v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); + if (!v->verify_wq) { + ti->error = "Cannot allocate workqueue"; + r = -ENOMEM; + goto bad; + } + + ti->per_io_data_size = sizeof(struct dm_verity_io) + + crypto_shash_descsize(v->shash_tfm); + + r = verity_fec_ctr(v); + if (r) + goto bad; + + ti->per_io_data_size = roundup(ti->per_io_data_size, + __alignof__(struct dm_verity_io)); + + verity_verify_sig_opts_cleanup(&verify_args); + + dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); + + return 0; + +bad: + + verity_verify_sig_opts_cleanup(&verify_args); + dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); + verity_dtr(ti); + + return r; +} + +/* + * Get the verity mode (error behavior) of a verity target. + * + * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity + * target. + */ +int dm_verity_get_mode(struct dm_target *ti) +{ + struct dm_verity *v = ti->private; + + if (!dm_is_verity_target(ti)) + return -EINVAL; + + return v->mode; +} + +/* + * Get the root digest of a verity target. + * + * Returns a copy of the root digest, the caller is responsible for + * freeing the memory of the digest. + */ +int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) +{ + struct dm_verity *v = ti->private; + + if (!dm_is_verity_target(ti)) + return -EINVAL; + + *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); + if (*root_digest == NULL) + return -ENOMEM; + + *digest_size = v->digest_size; + + return 0; +} + +#ifdef CONFIG_SECURITY + +#ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG + +static int verity_security_set_signature(struct block_device *bdev, + struct dm_verity *v) +{ + /* + * if the dm-verity target is unsigned, v->root_digest_sig will + * be NULL, and the hook call is still required to let LSMs mark + * the device as unsigned. This information is crucial for LSMs to + * block operations such as execution on unsigned files + */ + return security_bdev_setintegrity(bdev, + LSM_INT_DMVERITY_SIG_VALID, + v->root_digest_sig, + v->sig_size); +} + +#else + +static inline int verity_security_set_signature(struct block_device *bdev, + struct dm_verity *v) +{ + return 0; +} + +#endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */ + +/* + * Expose verity target's root hash and signature data to LSMs before resume. + * + * Returns 0 on success, or -ENOMEM if the system is out of memory. + */ +static int verity_preresume(struct dm_target *ti) +{ + struct block_device *bdev; + struct dm_verity_digest root_digest; + struct dm_verity *v; + int r; + + v = ti->private; + bdev = dm_disk(dm_table_get_md(ti->table))->part0; + root_digest.digest = v->root_digest; + root_digest.digest_len = v->digest_size; + root_digest.alg = crypto_shash_alg_name(v->shash_tfm); + + r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest, + sizeof(root_digest)); + if (r) + return r; + + r = verity_security_set_signature(bdev, v); + if (r) + goto bad; + + return 0; + +bad: + + security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0); + + return r; +} + +#endif /* CONFIG_SECURITY */ + +static struct target_type verity_target = { + .name = "verity", +/* Note: the LSMs depend on the singleton and immutable features */ + .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, + .version = {1, 12, 0}, + .module = THIS_MODULE, + .ctr = verity_ctr, + .dtr = verity_dtr, + .map = verity_map, + .postsuspend = verity_postsuspend, + .status = verity_status, + .prepare_ioctl = verity_prepare_ioctl, + .iterate_devices = verity_iterate_devices, + .io_hints = verity_io_hints, +#ifdef CONFIG_SECURITY + .preresume = verity_preresume, +#endif /* CONFIG_SECURITY */ +}; +module_dm(verity); + +/* + * Check whether a DM target is a verity target. + */ +bool dm_is_verity_target(struct dm_target *ti) +{ + return ti->type == &verity_target; +} + +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"); |