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[PATCH 2/4] dm-crypt: multi tfm mode | |
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Introduces a mode for dm-crypt which uses multiple
encryption keys (and thus tfms) alternating based on
the sector number and the number of keys.
This change is needed to support loop-AES compatible
block chaining modes, which use "multi:64".
Signed-off-by: Max Vozeler <max@xxxxxxxxxxxxx>
Cc: Milan Broz <mbroz@xxxxxxxxxx>
Cc: Jari Ruusu <jariruusu@xxxxxxxxxxxxxxxxxxxxx>
---
Documentation/device-mapper/dm-crypt.txt | 3 +-
drivers/md/dm-crypt.c | 138 +++++++++++++++++++++++++----
2 files changed, 121 insertions(+), 20 deletions(-)
diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 6680cab..0d57442 100644
--- a/Documentation/device-mapper/dm-crypt.txt
+++ b/Documentation/device-mapper/dm-crypt.txt
@@ -8,11 +8,12 @@ Parameters: <cipher> <key> <iv_offset> <device path> <offset>
<cipher>
Encryption cipher and an optional IV generation mode.
- (In format cipher-chainmode-ivopts:ivmode).
+ (In format cipher-chainmode-ivopts:ivmode-multi:nkeys).
Examples:
des
aes-cbc-essiv:sha256
twofish-ecb
+ aes-lmk3-plain64-multi:64
/proc/crypto contains supported crypto modes
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index e783f93..a7c7c22 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -22,6 +22,7 @@
#include <linux/scatterlist.h>
#include <asm/page.h>
#include <asm/unaligned.h>
+#include <asm/div64.h>
#include <linux/device-mapper.h>
@@ -120,6 +121,12 @@ struct crypt_config {
unsigned int iv_size;
/*
+ * crypto context selection
+ */
+ struct crypto_ablkcipher **tfms;
+ unsigned long numtfms;
+
+ /*
* Layout of each crypto request:
*
* struct ablkcipher_request
@@ -137,7 +144,6 @@ struct crypt_config {
char cipher[CRYPTO_MAX_ALG_NAME];
char chainmode[CRYPTO_MAX_ALG_NAME];
- struct crypto_ablkcipher *tfm;
unsigned long flags;
unsigned int key_size;
u8 key[0];
@@ -273,7 +279,7 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
goto bad;
}
if (crypto_cipher_blocksize(essiv_tfm) !=
- crypto_ablkcipher_ivsize(cc->tfm)) {
+ crypto_ablkcipher_ivsize(cc->tfms[0])) {
ti->error = "Block size of ESSIV cipher does "
"not match IV size of block cipher";
err = -EINVAL;
@@ -306,7 +312,7 @@ static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
const char *opts)
{
- unsigned bs = crypto_ablkcipher_blocksize(cc->tfm);
+ unsigned bs = crypto_ablkcipher_blocksize(cc->tfms[0]);
int log = ilog2(bs);
/* we need to calculate how far we must shift the sector count
@@ -376,6 +382,56 @@ static struct crypt_iv_operations crypt_iv_null_ops = {
.generator = crypt_iv_null_gen
};
+static void crypt_free_tfms(struct crypt_config *cc)
+{
+ int i;
+
+ for (i=0; i < cc->numtfms; i++)
+ if (cc->tfms[i])
+ crypto_free_ablkcipher(cc->tfms[i]);
+
+ kfree(cc->tfms);
+}
+
+static int crypt_alloc_tfms(struct crypt_config *cc, struct dm_target *ti, char *ciphermode)
+{
+ struct crypto_ablkcipher **tfms;
+ int i;
+
+ tfms = kcalloc(cc->numtfms, sizeof(*tfms), GFP_KERNEL);
+ if (!tfms)
+ return -ENOMEM;
+
+ for (i=0; i < cc->numtfms; i++) {
+ struct crypto_ablkcipher *tfm;
+
+ tfm = crypto_alloc_ablkcipher(ciphermode, 0, 0);
+ if (IS_ERR(tfm)) {
+ crypt_free_tfms(cc);
+
+ ti->error = "Error allocating crypto tfm";
+ return PTR_ERR(tfm);
+ }
+
+ tfms[i] = tfm;
+ }
+
+ cc->tfms = tfms;
+
+ return 0;
+}
+
+static struct crypto_ablkcipher *crypt_select_tfm(struct crypt_config *cc,
+ struct convert_context *ctx)
+{
+ if (cc->numtfms == 1)
+ return cc->tfms[0];
+ else {
+ sector_t tmp = ctx->sector;
+ return cc->tfms[do_div(tmp, cc->numtfms)];
+ }
+}
+
static void crypt_convert_init(struct crypt_config *cc,
struct convert_context *ctx,
struct bio *bio_out, struct bio *bio_in,
@@ -415,7 +471,7 @@ static int crypt_convert_block(struct crypt_config *cc,
dmreq = dmreq_of_req(cc, req);
iv = (u8 *)ALIGN((unsigned long)(dmreq + 1),
- crypto_ablkcipher_alignmask(cc->tfm) + 1);
+ crypto_ablkcipher_alignmask(cc->tfms[0]) + 1);
dmreq->ctx = ctx;
sg_init_table(&dmreq->sg_in, 1);
@@ -460,9 +516,15 @@ static void kcryptd_async_done(struct crypto_async_request *async_req,
static void crypt_alloc_req(struct crypt_config *cc,
struct convert_context *ctx)
{
+ struct crypto_ablkcipher *tfm;
+
if (!cc->req)
cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
- ablkcipher_request_set_tfm(cc->req, cc->tfm);
+
+ tfm = crypt_select_tfm(cc, ctx);
+
+ ablkcipher_request_set_tfm(cc->req, tfm);
+
ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG |
CRYPTO_TFM_REQ_MAY_SLEEP,
kcryptd_async_done,
@@ -974,6 +1036,21 @@ static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
}
}
+static int crypt_set_subkeys(struct crypt_config *cc, const u8 *key)
+{
+ int i, err = 0;
+ unsigned subkey_size = cc->key_size / cc->numtfms;
+
+ for (i=0; i < cc->numtfms; i++) {
+ err = crypto_ablkcipher_setkey(cc->tfms[i],
+ cc->key + (i * subkey_size), subkey_size);
+ if (err)
+ break;
+ }
+
+ return err;
+}
+
static int crypt_set_key(struct crypt_config *cc, char *key)
{
unsigned key_size = strlen(key) >> 1;
@@ -989,14 +1066,15 @@ static int crypt_set_key(struct crypt_config *cc, char *key)
set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
- return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
+ return crypt_set_subkeys(cc, cc->key);
}
static int crypt_wipe_key(struct crypt_config *cc)
{
clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
memset(&cc->key, 0, cc->key_size * sizeof(u8));
- return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
+
+ return crypt_set_subkeys(cc, cc->key);
}
/*
@@ -1006,12 +1084,13 @@ static int crypt_wipe_key(struct crypt_config *cc)
static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct crypt_config *cc;
- struct crypto_ablkcipher *tfm;
char *tmp;
char *cipher;
char *chainmode;
char *ivmode;
char *ivopts;
+ char *tfmmode;
+ char *tfmopts;
unsigned int key_size;
unsigned long long tmpll;
char ciphermode[CRYPTO_MAX_ALG_NAME];
@@ -1026,6 +1105,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
chainmode = strsep(&tmp, "-");
ivopts = strsep(&tmp, "-");
ivmode = strsep(&ivopts, ":");
+ tfmopts = strsep(&tmp, "-");
+ tfmmode = strsep(&tfmopts, ":");
if (tmp)
DMWARN("Unexpected additional cipher options");
@@ -1056,15 +1137,32 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad_cipher;
}
- tfm = crypto_alloc_ablkcipher(ciphermode, 0, 0);
- if (IS_ERR(tfm)) {
- ti->error = "Error allocating crypto tfm";
+ strcpy(cc->cipher, cipher);
+ strcpy(cc->chainmode, chainmode);
+
+ /*
+ * Choose multi key mode. Valid modes: "single", "multi:<n>"
+ */
+
+ if (tfmmode == NULL || strcmp(tfmmode, "single") == 0)
+ cc->numtfms = 1;
+ else if (strcmp(tfmmode, "multi") == 0) {
+ if (tfmopts == NULL) {
+ ti->error = "Number of keys missing for multi-tfm mode";
+ return -EINVAL;
+ }
+
+ if (strict_strtoul(tfmopts, 10, &cc->numtfms) < 0) {
+ ti->error = "Number of keys badly formatted";
+ return -EINVAL;
+ }
+ } else {
+ ti->error = "Invalid tfm mode";
goto bad_cipher;
}
- strcpy(cc->cipher, cipher);
- strcpy(cc->chainmode, chainmode);
- cc->tfm = tfm;
+ if (crypt_alloc_tfms(cc, ti, ciphermode) < 0)
+ goto bad_cipher;
if (crypt_set_key(cc, argv[1]) < 0) {
ti->error = "Error decoding and setting key";
@@ -1103,7 +1201,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad_slab_pool;
}
- cc->iv_size = crypto_ablkcipher_ivsize(tfm);
+ cc->iv_size = crypto_ablkcipher_ivsize(cc->tfms[0]);
if (cc->iv_size)
/* at least a 64 bit sector number should fit in our buffer */
cc->iv_size = max(cc->iv_size,
@@ -1124,9 +1222,9 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
}
cc->dmreq_start = sizeof(struct ablkcipher_request);
- cc->dmreq_start += crypto_ablkcipher_reqsize(tfm);
+ cc->dmreq_start += crypto_ablkcipher_reqsize(cc->tfms[0]);
cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
- cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) &
+ cc->dmreq_start += crypto_ablkcipher_alignmask(cc->tfms[0]) &
~(crypto_tfm_ctx_alignment() - 1);
cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
@@ -1213,7 +1311,7 @@ bad_slab_pool:
if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
cc->iv_gen_ops->dtr(cc);
bad_ivmode:
- crypto_free_ablkcipher(tfm);
+ crypt_free_tfms(cc);
bad_cipher:
/* Must zero key material before freeing */
kzfree(cc);
@@ -1238,7 +1336,9 @@ static void crypt_dtr(struct dm_target *ti)
kfree(cc->iv_mode);
if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
cc->iv_gen_ops->dtr(cc);
- crypto_free_ablkcipher(cc->tfm);
+
+ crypt_free_tfms(cc);
+
dm_put_device(ti, cc->dev);
/* Must zero key material before freeing */
--
1.6.5.4
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