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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 <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Milan Broz 2009-12-10 23:51:56 +00:00 committed by Alasdair G Kergon
parent 5861f1be00
commit b95bf2d3d5
1 changed files with 43 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

69
drivers/md/dm-crypt.c
View File

@ -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 */