From b95bf2d3d5a48b095bffe2a0cd8c40453cf59557 Mon Sep 17 00:00:00 2001 From: Milan Broz Date: Thu, 10 Dec 2009 23:51:56 +0000 Subject: [PATCH] dm crypt: separate essiv allocation from initialisation This patch separates the construction of IV from its initialisation. (For ESSIV it is a hash calculation based on volume key.) Constructor code now preallocates hash tfm and salt array and saves it in a private IV structure. The next patch requires this to reinitialise the wiped IV without reallocating memory when resuming a suspended device. Cc: stable@kernel.org Signed-off-by: Milan Broz Signed-off-by: Alasdair G Kergon --- drivers/md/dm-crypt.c | 69 ++++++++++++++++++++++++++++++++------------------- 1 file changed, 43 insertions(+), 26 deletions(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 2301d22..446153a 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -71,11 +71,14 @@ struct crypt_iv_operations { int (*ctr)(struct crypt_config *cc, struct dm_target *ti, const char *opts); void (*dtr)(struct crypt_config *cc); + int (*init)(struct crypt_config *cc); int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector); }; struct iv_essiv_private { struct crypto_cipher *tfm; + struct crypto_hash *hash_tfm; + u8 *salt; }; struct iv_benbi_private { @@ -176,12 +179,38 @@ static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector) return 0; } +/* Initialise ESSIV - compute salt but no local memory allocations */ +static int crypt_iv_essiv_init(struct crypt_config *cc) +{ + struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv; + struct hash_desc desc; + struct scatterlist sg; + int err; + + sg_init_one(&sg, cc->key, cc->key_size); + desc.tfm = essiv->hash_tfm; + desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + + err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt); + if (err) + return err; + + return crypto_cipher_setkey(essiv->tfm, essiv->salt, + crypto_hash_digestsize(essiv->hash_tfm)); +} + static void crypt_iv_essiv_dtr(struct crypt_config *cc) { struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv; crypto_free_cipher(essiv->tfm); essiv->tfm = NULL; + + crypto_free_hash(essiv->hash_tfm); + essiv->hash_tfm = NULL; + + kzfree(essiv->salt); + essiv->salt = NULL; } static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, @@ -189,9 +218,6 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, { struct crypto_cipher *essiv_tfm = NULL; struct crypto_hash *hash_tfm = NULL; - struct hash_desc desc; - struct scatterlist sg; - unsigned int saltsize; u8 *salt = NULL; int err; @@ -200,7 +226,7 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, return -EINVAL; } - /* Hash the cipher key with the given hash algorithm */ + /* Allocate hash algorithm */ hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC); if (IS_ERR(hash_tfm)) { ti->error = "Error initializing ESSIV hash"; @@ -208,27 +234,14 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, goto bad; } - saltsize = crypto_hash_digestsize(hash_tfm); - salt = kzalloc(saltsize, GFP_KERNEL); + salt = kzalloc(crypto_hash_digestsize(hash_tfm), GFP_KERNEL); if (!salt) { ti->error = "Error kmallocing salt storage in ESSIV"; err = -ENOMEM; goto bad; } - sg_init_one(&sg, cc->key, cc->key_size); - desc.tfm = hash_tfm; - desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; - err = crypto_hash_digest(&desc, &sg, cc->key_size, salt); - crypto_free_hash(hash_tfm); - hash_tfm = NULL; - - if (err) { - ti->error = "Error calculating hash in ESSIV"; - goto bad; - } - - /* Setup the essiv_tfm with the given salt */ + /* Allocate essiv_tfm */ essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC); if (IS_ERR(essiv_tfm)) { ti->error = "Error allocating crypto tfm for ESSIV"; @@ -242,14 +255,11 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, err = -EINVAL; goto bad; } - err = crypto_cipher_setkey(essiv_tfm, salt, saltsize); - if (err) { - ti->error = "Failed to set key for ESSIV cipher"; - goto bad; - } - kzfree(salt); + cc->iv_gen_private.essiv.salt = salt; cc->iv_gen_private.essiv.tfm = essiv_tfm; + cc->iv_gen_private.essiv.hash_tfm = hash_tfm; + return 0; bad: @@ -257,7 +267,7 @@ bad: crypto_free_cipher(essiv_tfm); if (hash_tfm && !IS_ERR(hash_tfm)) crypto_free_hash(hash_tfm); - kzfree(salt); + kfree(salt); return err; } @@ -323,6 +333,7 @@ static struct crypt_iv_operations crypt_iv_plain_ops = { static struct crypt_iv_operations crypt_iv_essiv_ops = { .ctr = crypt_iv_essiv_ctr, .dtr = crypt_iv_essiv_dtr, + .init = crypt_iv_essiv_init, .generator = crypt_iv_essiv_gen }; @@ -1054,6 +1065,12 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) goto bad_ivmode; + if (cc->iv_gen_ops && cc->iv_gen_ops->init && + cc->iv_gen_ops->init(cc) < 0) { + ti->error = "Error initialising IV"; + goto bad_slab_pool; + } + cc->iv_size = crypto_ablkcipher_ivsize(tfm); if (cc->iv_size) /* at least a 64 bit sector number should fit in our buffer */ -- 2.7.4