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authorMilan Broz <gmazyland@gmail.com>2013-10-28 23:21:03 +0100
committerMike Snitzer <snitzer@redhat.com>2013-11-09 18:20:20 -0500
commitda31a0787a2ac92dd219ce0d33322160b66d6a01 (patch)
tree01f47fbf8855b25ea85a7504dbb32569f712f293 /drivers/md/dm-crypt.c
parent2c2263c93f70c6abdce90ad96a854760532aa52f (diff)
dm crypt: properly handle extra key string in initialization
Some encryption modes use extra keys (e.g. loopAES has IV seed) which are not used in block cipher initialization but are part of key string in table constructor. This patch adds an additional field which describes the length of the extra key(s) and substracts it before real key encryption setting. The key_size always includes the size, in bytes, of the key provided in mapping table. The key_parts describes how many parts (usually keys) are contained in the whole key buffer. And key_extra_size contains size in bytes of additional keys part (this number of bytes must be subtracted because it is processed by the IV generator). | K1 | K2 | .... | K64 | Kiv | |----------- key_size ----------------- | | |-key_extra_size-| | [64 keys] | [1 key] | => key_parts = 65 Example where key string contains main key K, whitening key Kw and IV seed Kiv: | K | Kiv | Kw | |--------------- key_size --------------| | |-----key_extra_size------| | [1 key] | [1 key] | [1 key] | => key_parts = 3 Because key_extra_size is calculated during IV mode setting, key initialization is moved after this step. For now, this change has no effect to supported modes (thanks to ilog2 rounding) but it is required by the following patch. Also, fix a sparse warning in crypt_iv_lmk_one(). Signed-off-by: Milan Broz <gmazyland@gmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-crypt.c')
-rw-r--r--drivers/md/dm-crypt.c29
1 files changed, 18 insertions, 11 deletions
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 0fce0bc1a957..e0c61a326550 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -171,7 +171,8 @@ struct crypt_config {
unsigned long flags;
unsigned int key_size;
- unsigned int key_parts;
+ unsigned int key_parts; /* independent parts in key buffer */
+ unsigned int key_extra_size; /* additional keys length */
u8 key[0];
};
@@ -530,7 +531,7 @@ static int crypt_iv_lmk_one(struct crypt_config *cc, u8 *iv,
char ctx[crypto_shash_descsize(lmk->hash_tfm)];
} sdesc;
struct md5_state md5state;
- u32 buf[4];
+ __le32 buf[4];
int i, r;
sdesc.desc.tfm = lmk->hash_tfm;
@@ -1274,9 +1275,12 @@ static int crypt_alloc_tfms(struct crypt_config *cc, char *ciphermode)
static int crypt_setkey_allcpus(struct crypt_config *cc)
{
- unsigned subkey_size = cc->key_size >> ilog2(cc->tfms_count);
+ unsigned subkey_size;
int err = 0, i, r;
+ /* Ignore extra keys (which are used for IV etc) */
+ subkey_size = (cc->key_size - cc->key_extra_size) >> ilog2(cc->tfms_count);
+
for (i = 0; i < cc->tfms_count; i++) {
r = crypto_ablkcipher_setkey(cc->tfms[i],
cc->key + (i * subkey_size),
@@ -1409,6 +1413,7 @@ static int crypt_ctr_cipher(struct dm_target *ti,
return -EINVAL;
}
cc->key_parts = cc->tfms_count;
+ cc->key_extra_size = 0;
cc->cipher = kstrdup(cipher, GFP_KERNEL);
if (!cc->cipher)
@@ -1460,13 +1465,6 @@ static int crypt_ctr_cipher(struct dm_target *ti,
goto bad;
}
- /* Initialize and set key */
- ret = crypt_set_key(cc, key);
- if (ret < 0) {
- ti->error = "Error decoding and setting key";
- goto bad;
- }
-
/* Initialize IV */
cc->iv_size = crypto_ablkcipher_ivsize(any_tfm(cc));
if (cc->iv_size)
@@ -1497,14 +1495,23 @@ static int crypt_ctr_cipher(struct dm_target *ti,
* to length of provided multi-key string.
* If present (version 3), last key is used as IV seed.
*/
- if (cc->key_size % cc->key_parts)
+ if (cc->key_size % cc->key_parts) {
cc->key_parts++;
+ cc->key_extra_size = cc->key_size / cc->key_parts;
+ }
} else {
ret = -EINVAL;
ti->error = "Invalid IV mode";
goto bad;
}
+ /* Initialize and set key */
+ ret = crypt_set_key(cc, key);
+ if (ret < 0) {
+ ti->error = "Error decoding and setting key";
+ goto bad;
+ }
+
/* Allocate IV */
if (cc->iv_gen_ops && cc->iv_gen_ops->ctr) {
ret = cc->iv_gen_ops->ctr(cc, ti, ivopts);