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bdf253d580
The support for asynchronous hashes in dm-verity has outlived its usefulness. It adds significant code complexity and opportunity for bugs. I don't know of anyone using it in practice. (The original submitter of the code possibly was, but that was 8 years ago.) Data I recently collected for en/decryption shows that using off-CPU crypto "accelerators" is consistently much slower than the CPU (https://lore.kernel.org/r/20250704070322.20692-1-ebiggers@kernel.org/), even on CPUs that lack dedicated cryptographic instructions. Similar results are likely to be seen for hashing. I already removed support for asynchronous hashes from fsverity two years ago, and no one ever complained. Moreover, neither dm-verity, fsverity, nor fscrypt has ever actually used the asynchronous crypto algorithms in a truly asynchronous manner. The lack of interest in such optimizations provides further evidence that it's only the CPU-based crypto that actually matters. Historically, it's also been common for people to forget to enable the optimized SHA-256 code, which could contribute to an off-CPU crypto engine being perceived as more useful than it really is. In 6.16 I fixed that: the optimized SHA-256 code is now enabled by default. Therefore, let's drop the support for asynchronous hashes in dm-verity. Tested with verity-compat-test. Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
132 lines
3.8 KiB
C
132 lines
3.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2012 Red Hat, Inc.
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* Copyright (C) 2015 Google, Inc.
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*
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* Author: Mikulas Patocka <mpatocka@redhat.com>
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*
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* Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
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*/
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#ifndef DM_VERITY_H
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#define DM_VERITY_H
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#include <linux/dm-io.h>
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#include <linux/dm-bufio.h>
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#include <linux/device-mapper.h>
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#include <linux/interrupt.h>
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#include <crypto/hash.h>
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#define DM_VERITY_MAX_LEVELS 63
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enum verity_mode {
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DM_VERITY_MODE_EIO,
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DM_VERITY_MODE_LOGGING,
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DM_VERITY_MODE_RESTART,
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DM_VERITY_MODE_PANIC
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};
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enum verity_block_type {
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DM_VERITY_BLOCK_TYPE_DATA,
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DM_VERITY_BLOCK_TYPE_METADATA
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};
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struct dm_verity_fec;
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struct dm_verity {
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struct dm_dev *data_dev;
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struct dm_dev *hash_dev;
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struct dm_target *ti;
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struct dm_bufio_client *bufio;
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char *alg_name;
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struct crypto_shash *shash_tfm;
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u8 *root_digest; /* digest of the root block */
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u8 *salt; /* salt: its size is salt_size */
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u8 *initial_hashstate; /* salted initial state, if version >= 1 */
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u8 *zero_digest; /* digest for a zero block */
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#ifdef CONFIG_SECURITY
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u8 *root_digest_sig; /* signature of the root digest */
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unsigned int sig_size; /* root digest signature size */
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#endif /* CONFIG_SECURITY */
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unsigned int salt_size;
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sector_t hash_start; /* hash start in blocks */
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sector_t data_blocks; /* the number of data blocks */
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sector_t hash_blocks; /* the number of hash blocks */
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unsigned char data_dev_block_bits; /* log2(data blocksize) */
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unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
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unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
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unsigned char levels; /* the number of tree levels */
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unsigned char version;
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bool hash_failed:1; /* set if hash of any block failed */
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bool use_bh_wq:1; /* try to verify in BH wq before normal work-queue */
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unsigned int digest_size; /* digest size for the current hash algorithm */
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enum verity_mode mode; /* mode for handling verification errors */
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enum verity_mode error_mode;/* mode for handling I/O errors */
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unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
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struct workqueue_struct *verify_wq;
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/* starting blocks for each tree level. 0 is the lowest level. */
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sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
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struct dm_verity_fec *fec; /* forward error correction */
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unsigned long *validated_blocks; /* bitset blocks validated */
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char *signature_key_desc; /* signature keyring reference */
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struct dm_io_client *io;
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mempool_t recheck_pool;
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};
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struct dm_verity_io {
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struct dm_verity *v;
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/* original value of bio->bi_end_io */
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bio_end_io_t *orig_bi_end_io;
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struct bvec_iter iter;
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sector_t block;
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unsigned int n_blocks;
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bool in_bh;
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bool had_mismatch;
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struct work_struct work;
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struct work_struct bh_work;
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u8 real_digest[HASH_MAX_DIGESTSIZE];
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u8 want_digest[HASH_MAX_DIGESTSIZE];
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/*
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* Temporary space for hashing. This is variable-length and must be at
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* the end of the struct. struct shash_desc is just the fixed part;
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* it's followed by a context of size crypto_shash_descsize(shash_tfm).
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*/
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struct shash_desc hash_desc;
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};
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static inline u8 *verity_io_real_digest(struct dm_verity *v,
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struct dm_verity_io *io)
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{
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return io->real_digest;
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}
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static inline u8 *verity_io_want_digest(struct dm_verity *v,
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struct dm_verity_io *io)
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{
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return io->want_digest;
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}
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extern int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
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const u8 *data, size_t len, u8 *digest);
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extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
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sector_t block, u8 *digest, bool *is_zero);
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extern bool dm_is_verity_target(struct dm_target *ti);
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extern int dm_verity_get_mode(struct dm_target *ti);
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extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest,
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unsigned int *digest_size);
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#endif /* DM_VERITY_H */
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