diff mbox series

[v6,3/7] md: dm-crypt: infer ESSIV block cipher from cipher string directly

Message ID 20190628152112.914-4-ard.biesheuvel@linaro.org
State New
Headers show
Series crypto: switch to crypto API for ESSIV generation | expand

Commit Message

Ard Biesheuvel June 28, 2019, 3:21 p.m. UTC 
Instead of allocating a crypto skcipher tfm 'foo' and attempting to
infer the encapsulated block cipher from the driver's 'name' field,
directly parse the string that we used to allocated the tfm. These
are always identical (unless the allocation failed, in which case
we bail anyway), but using the string allows us to use it in the
allocation, which is something we will need when switching to the
'essiv' crypto API template.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 drivers/md/dm-crypt.c | 35 +++++++++-----------
 1 file changed, 15 insertions(+), 20 deletions(-)

-- 
2.20.1

Comments

Milan Broz July 1, 2019, 8:58 a.m. UTC | #1 
On 28/06/2019 17:21, Ard Biesheuvel wrote:
> Instead of allocating a crypto skcipher tfm 'foo' and attempting to

> infer the encapsulated block cipher from the driver's 'name' field,

> directly parse the string that we used to allocated the tfm. These

> are always identical (unless the allocation failed, in which case

> we bail anyway), but using the string allows us to use it in the

> allocation, which is something we will need when switching to the

> 'essiv' crypto API template.

> 

> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>


>  drivers/md/dm-crypt.c | 35 +++++++++-----------


> @@ -2445,21 +2451,10 @@ static int crypt_ctr_cipher_new(struct dm_target *ti, char *cipher_in, char *key

>  

>  	/* Alloc AEAD, can be used only in new format. */


^^ This comment is now obsolete, please move it with the code or remove it.

>  	if (crypt_integrity_aead(cc)) {

> -		ret = crypt_ctr_auth_cipher(cc, cipher_api);

> -		if (ret < 0) {

> -			ti->error = "Invalid AEAD cipher spec";

> -			return -ENOMEM;

> -		}

>  		cc->iv_size = crypto_aead_ivsize(any_tfm_aead(cc));

>  	} else

>  		cc->iv_size = crypto_skcipher_ivsize(any_tfm(cc));


Otherwise

Reviewed-by: Milan Broz <gmazyland@gmail.com>


Thanks,
Milan
diff mbox series

Patch

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 1b16d34bb785..f001f1104cb5 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2321,25 +2321,17 @@  static int crypt_ctr_ivmode(struct dm_target *ti, const char *ivmode)
  * The cc->cipher is currently used only in ESSIV.
  * This should be probably done by crypto-api calls (once available...)
  */
-static int crypt_ctr_blkdev_cipher(struct crypt_config *cc)
+static int crypt_ctr_blkdev_cipher(struct crypt_config *cc, char *alg_name)
 {
-	const char *alg_name = NULL;
 	char *start, *end;
 
 	if (crypt_integrity_aead(cc)) {
-		alg_name = crypto_tfm_alg_name(crypto_aead_tfm(any_tfm_aead(cc)));
-		if (!alg_name)
-			return -EINVAL;
 		if (crypt_integrity_hmac(cc)) {
 			alg_name = strchr(alg_name, ',');
 			if (!alg_name)
 				return -EINVAL;
 		}
 		alg_name++;
-	} else {
-		alg_name = crypto_tfm_alg_name(crypto_skcipher_tfm(any_tfm(cc)));
-		if (!alg_name)
-			return -EINVAL;
 	}
 
 	start = strchr(alg_name, '(');
@@ -2434,6 +2426,20 @@  static int crypt_ctr_cipher_new(struct dm_target *ti, char *cipher_in, char *key
 	if (*ivmode && !strcmp(*ivmode, "lmk"))
 		cc->tfms_count = 64;
 
+	if (crypt_integrity_aead(cc)) {
+		ret = crypt_ctr_auth_cipher(cc, cipher_api);
+		if (ret < 0) {
+			ti->error = "Invalid AEAD cipher spec";
+			return -ENOMEM;
+	       }
+	}
+
+	ret = crypt_ctr_blkdev_cipher(cc, cipher_api);
+	if (ret < 0) {
+		ti->error = "Cannot allocate cipher string";
+		return -ENOMEM;
+	}
+
 	cc->key_parts = cc->tfms_count;
 
 	/* Allocate cipher */
@@ -2445,21 +2451,10 @@  static int crypt_ctr_cipher_new(struct dm_target *ti, char *cipher_in, char *key
 
 	/* Alloc AEAD, can be used only in new format. */
 	if (crypt_integrity_aead(cc)) {
-		ret = crypt_ctr_auth_cipher(cc, cipher_api);
-		if (ret < 0) {
-			ti->error = "Invalid AEAD cipher spec";
-			return -ENOMEM;
-		}
 		cc->iv_size = crypto_aead_ivsize(any_tfm_aead(cc));
 	} else
 		cc->iv_size = crypto_skcipher_ivsize(any_tfm(cc));
 
-	ret = crypt_ctr_blkdev_cipher(cc);
-	if (ret < 0) {
-		ti->error = "Cannot allocate cipher string";
-		return -ENOMEM;
-	}
-
 	return 0;
 }