[PATCH v5 07/15] dm-verity: move hash algorithm setup into its own function

Eric Biggers
2024-06-11T03:49:13Z

Move the code that sets up the hash transformation into its own
function. No change in behavior.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
drivers/md/dm-verity-target.c | 70 +++++++++++++++++++----------------
1 file changed, 39 insertions(+), 31 deletions(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index bb5da66da4c1..88d2a49dca43 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -1224,10 +1224,47 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
} 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_ahash *ahash;
+
+ v->alg_name = kstrdup(alg_name, GFP_KERNEL);
+ if (!v->alg_name) {
+ ti->error = "Cannot allocate algorithm name";
+ return -ENOMEM;
+ }
+
+ ahash = crypto_alloc_ahash(alg_name, 0,
+ v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
+ if (IS_ERR(ahash)) {
+ ti->error = "Cannot initialize hash function";
+ return PTR_ERR(ahash);
+ }
+ v->tfm = ahash;
+
+ /*
+ * 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\"", alg_name,
+ crypto_hash_alg_common(ahash)->base.cra_driver_name);
+
+ v->digest_size = crypto_ahash_digestsize(ahash);
+ if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
+ ti->error = "Digest size too big";
+ return -EINVAL;
+ }
+ v->ahash_reqsize = sizeof(struct ahash_request) +
+ crypto_ahash_reqsize(ahash);
+ return 0;
+}
+
/*
* Target parameters:
* <version> The current format is version 1.
* Vsn 0 is compatible with original Chromium OS releases.
*
@@ -1348,42 +1385,13 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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,
- v->use_bh_wq ? CRYPTO_ALG_ASYNC : 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;
+ r = verity_setup_hash_alg(v, argv[7]);
+ if (r)
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;
--
2.45.1