[105/151] dm crypt: separate essiv allocation from initialisation

Greg KH
2009-12-17T04:22:43Z

From: Milan Broz <mbroz@redhat.com>

commit b95bf2d3d5a48b095bffe2a0cd8c40453cf59557 upstream.

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.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/dm-crypt.c | 69 +++++++++++++++++++++++++++++++-------------------
1 file changed, 43 insertions(+), 26 deletions(-)

--- 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 cry
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 cry
{
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 cry
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 cry
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 cry
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_
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 *t
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 */