In preparing to remove all stack VLA usage from the kernel[1], this removes the discouraged use of AHASH_REQUEST_ON_STACK in favor of the smaller SHASH_DESC_ON_STACK by converting from ahash-wrapped-shash to direct shash. By removing a layer of indirection this both improves performance and reduces stack usage. The stack allocation will be made a fixed size in a later patch to the crypto subsystem. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@xxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- drivers/md/dm-crypt.c | 31 ++++++++++++++----------------- 1 file changed, 14 insertions(+), 17 deletions(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index b61b069c33af..c4c922990090 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -99,7 +99,7 @@ struct crypt_iv_operations { }; struct iv_essiv_private { - struct crypto_ahash *hash_tfm; + struct crypto_shash *hash_tfm; u8 *salt; }; @@ -327,25 +327,22 @@ static int crypt_iv_plain64be_gen(struct crypt_config *cc, u8 *iv, static int crypt_iv_essiv_init(struct crypt_config *cc) { struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv; - AHASH_REQUEST_ON_STACK(req, essiv->hash_tfm); - struct scatterlist sg; + SHASH_DESC_ON_STACK(desc, essiv->hash_tfm); struct crypto_cipher *essiv_tfm; int err; - sg_init_one(&sg, cc->key, cc->key_size); - ahash_request_set_tfm(req, essiv->hash_tfm); - ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL); - ahash_request_set_crypt(req, &sg, essiv->salt, cc->key_size); + desc->tfm = essiv->hash_tfm; + desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; - err = crypto_ahash_digest(req); - ahash_request_zero(req); + err = crypto_shash_digest(desc, cc->key, cc->key_size, essiv->salt); + shash_desc_zero(desc); if (err) return err; essiv_tfm = cc->iv_private; err = crypto_cipher_setkey(essiv_tfm, essiv->salt, - crypto_ahash_digestsize(essiv->hash_tfm)); + crypto_shash_digestsize(essiv->hash_tfm)); if (err) return err; @@ -356,7 +353,7 @@ static int crypt_iv_essiv_init(struct crypt_config *cc) static int crypt_iv_essiv_wipe(struct crypt_config *cc) { struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv; - unsigned salt_size = crypto_ahash_digestsize(essiv->hash_tfm); + unsigned salt_size = crypto_shash_digestsize(essiv->hash_tfm); struct crypto_cipher *essiv_tfm; int r, err = 0; @@ -408,7 +405,7 @@ static void crypt_iv_essiv_dtr(struct crypt_config *cc) struct crypto_cipher *essiv_tfm; struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv; - crypto_free_ahash(essiv->hash_tfm); + crypto_free_shash(essiv->hash_tfm); essiv->hash_tfm = NULL; kzfree(essiv->salt); @@ -426,7 +423,7 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, const char *opts) { struct crypto_cipher *essiv_tfm = NULL; - struct crypto_ahash *hash_tfm = NULL; + struct crypto_shash *hash_tfm = NULL; u8 *salt = NULL; int err; @@ -436,14 +433,14 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, } /* Allocate hash algorithm */ - hash_tfm = crypto_alloc_ahash(opts, 0, CRYPTO_ALG_ASYNC); + hash_tfm = crypto_alloc_shash(opts, 0, 0); if (IS_ERR(hash_tfm)) { ti->error = "Error initializing ESSIV hash"; err = PTR_ERR(hash_tfm); goto bad; } - salt = kzalloc(crypto_ahash_digestsize(hash_tfm), GFP_KERNEL); + salt = kzalloc(crypto_shash_digestsize(hash_tfm), GFP_KERNEL); if (!salt) { ti->error = "Error kmallocing salt storage in ESSIV"; err = -ENOMEM; @@ -454,7 +451,7 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, cc->iv_gen_private.essiv.hash_tfm = hash_tfm; essiv_tfm = alloc_essiv_cipher(cc, ti, salt, - crypto_ahash_digestsize(hash_tfm)); + crypto_shash_digestsize(hash_tfm)); if (IS_ERR(essiv_tfm)) { crypt_iv_essiv_dtr(cc); return PTR_ERR(essiv_tfm); @@ -465,7 +462,7 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, bad: if (hash_tfm && !IS_ERR(hash_tfm)) - crypto_free_ahash(hash_tfm); + crypto_free_shash(hash_tfm); kfree(salt); return err; } -- 2.17.1
