From: Sami Tolvanen Date: Thu, 5 Nov 2015 02:02:31 +0000 (+0000) Subject: dm verity: clean up duplicate hashing code X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6dbeda3469ced777bc3138ed5918f7ae79670b7b;p=linux-beck.git dm verity: clean up duplicate hashing code Handle dm-verity salting in one place to simplify the code. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Signed-off-by: Mike Snitzer --- diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c index 9e8891507c1c..24517055bd8e 100644 --- a/drivers/md/dm-verity.c +++ b/drivers/md/dm-verity.c @@ -172,6 +172,84 @@ static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, return block >> (level * v->hash_per_block_bits); } +/* + * Wrapper for crypto_shash_init, which handles verity salting. + */ +static int verity_hash_init(struct dm_verity *v, struct shash_desc *desc) +{ + int r; + + desc->tfm = v->tfm; + desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; + + r = crypto_shash_init(desc); + + if (unlikely(r < 0)) { + DMERR("crypto_shash_init failed: %d", r); + return r; + } + + if (likely(v->version >= 1)) { + r = crypto_shash_update(desc, v->salt, v->salt_size); + + if (unlikely(r < 0)) { + DMERR("crypto_shash_update failed: %d", r); + return r; + } + } + + return 0; +} + +static int verity_hash_update(struct dm_verity *v, struct shash_desc *desc, + const u8 *data, size_t len) +{ + int r = crypto_shash_update(desc, data, len); + + if (unlikely(r < 0)) + DMERR("crypto_shash_update failed: %d", r); + + return r; +} + +static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc, + u8 *digest) +{ + int r; + + if (unlikely(!v->version)) { + r = crypto_shash_update(desc, v->salt, v->salt_size); + + if (r < 0) { + DMERR("crypto_shash_update failed: %d", r); + return r; + } + } + + r = crypto_shash_final(desc, digest); + + if (unlikely(r < 0)) + DMERR("crypto_shash_final failed: %d", r); + + return r; +} + +static int verity_hash(struct dm_verity *v, struct shash_desc *desc, + const u8 *data, size_t len, u8 *digest) +{ + int r; + + r = verity_hash_init(v, desc); + if (unlikely(r < 0)) + return r; + + r = verity_hash_update(v, desc, data, len); + if (unlikely(r < 0)) + return r; + + return verity_hash_final(v, desc, digest); +} + static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, sector_t *hash_block, unsigned *offset) { @@ -252,10 +330,10 @@ out: * If "skip_unverified" is false, unverified buffer is hashed and verified * against current value of io_want_digest(v, io). */ -static int verity_verify_level(struct dm_verity_io *io, sector_t block, - int level, bool skip_unverified) +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_verity *v = io->v; struct dm_buffer *buf; struct buffer_aux *aux; u8 *data; @@ -272,74 +350,71 @@ static int verity_verify_level(struct dm_verity_io *io, sector_t block, aux = dm_bufio_get_aux_data(buf); if (!aux->hash_verified) { - struct shash_desc *desc; - u8 *result; - if (skip_unverified) { r = 1; goto release_ret_r; } - desc = io_hash_desc(v, io); - desc->tfm = v->tfm; - desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; - r = crypto_shash_init(desc); - if (r < 0) { - DMERR("crypto_shash_init failed: %d", r); + r = verity_hash(v, io_hash_desc(v, io), + data, 1 << v->hash_dev_block_bits, + io_real_digest(v, io)); + if (unlikely(r < 0)) goto release_ret_r; - } - - if (likely(v->version >= 1)) { - r = crypto_shash_update(desc, v->salt, v->salt_size); - if (r < 0) { - DMERR("crypto_shash_update failed: %d", r); - goto release_ret_r; - } - } - r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits); - if (r < 0) { - DMERR("crypto_shash_update failed: %d", r); - goto release_ret_r; - } - - if (!v->version) { - r = crypto_shash_update(desc, v->salt, v->salt_size); - if (r < 0) { - DMERR("crypto_shash_update failed: %d", r); - goto release_ret_r; - } - } - - result = io_real_digest(v, io); - r = crypto_shash_final(desc, result); - if (r < 0) { - DMERR("crypto_shash_final failed: %d", r); + if (likely(memcmp(io_real_digest(v, io), want_digest, + v->digest_size) == 0)) + aux->hash_verified = 1; + else if (verity_handle_err(v, + DM_VERITY_BLOCK_TYPE_METADATA, + hash_block)) { + r = -EIO; goto release_ret_r; } - if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { - if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_METADATA, - hash_block)) { - r = -EIO; - goto release_ret_r; - } - } else - aux->hash_verified = 1; } data += offset; - - memcpy(io_want_digest(v, io), data, v->digest_size); - - dm_bufio_release(buf); - return 0; + 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. + */ +static int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, + sector_t block, u8 *digest) +{ + int i; + int r; + + 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)) + return r; + } + + 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)) + return r; + } + + return 0; +} + /* * Verify one "dm_verity_io" structure. */ @@ -349,54 +424,21 @@ static int verity_verify_io(struct dm_verity_io *io) struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size); unsigned b; - int i; for (b = 0; b < io->n_blocks; b++) { - struct shash_desc *desc; - u8 *result; int r; unsigned todo; + struct shash_desc *desc = io_hash_desc(v, io); - 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 0 and we fall back to whole - * chain verification. - */ - int r = verity_verify_level(io, io->block + b, 0, true); - if (likely(!r)) - goto test_block_hash; - if (r < 0) - return r; - } - - memcpy(io_want_digest(v, io), v->root_digest, v->digest_size); - - for (i = v->levels - 1; i >= 0; i--) { - int r = verity_verify_level(io, io->block + b, i, false); - if (unlikely(r)) - return r; - } + r = verity_hash_for_block(v, io, io->block + b, + io_want_digest(v, io)); + if (unlikely(r < 0)) + return r; -test_block_hash: - desc = io_hash_desc(v, io); - desc->tfm = v->tfm; - desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; - r = crypto_shash_init(desc); - if (r < 0) { - DMERR("crypto_shash_init failed: %d", r); + r = verity_hash_init(v, desc); + if (unlikely(r < 0)) return r; - } - if (likely(v->version >= 1)) { - r = crypto_shash_update(desc, v->salt, v->salt_size); - if (r < 0) { - DMERR("crypto_shash_update failed: %d", r); - return r; - } - } todo = 1 << v->data_dev_block_bits; do { u8 *page; @@ -407,37 +449,27 @@ test_block_hash: len = bv.bv_len; if (likely(len >= todo)) len = todo; - r = crypto_shash_update(desc, page + bv.bv_offset, len); + r = verity_hash_update(v, desc, page + bv.bv_offset, + len); kunmap_atomic(page); - if (r < 0) { - DMERR("crypto_shash_update failed: %d", r); + if (unlikely(r < 0)) return r; - } bio_advance_iter(bio, &io->iter, len); todo -= len; } while (todo); - if (!v->version) { - r = crypto_shash_update(desc, v->salt, v->salt_size); - if (r < 0) { - DMERR("crypto_shash_update failed: %d", r); - return r; - } - } - - result = io_real_digest(v, io); - r = crypto_shash_final(desc, result); - if (r < 0) { - DMERR("crypto_shash_final failed: %d", r); + r = verity_hash_final(v, desc, io_real_digest(v, io)); + if (unlikely(r < 0)) return r; - } - if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { - if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, - io->block + b)) - return -EIO; - } + + if (likely(memcmp(io_real_digest(v, io), + io_want_digest(v, io), v->digest_size) == 0)) + continue; + else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, + io->block + b)) + return -EIO; } return 0;