crypto: af_alg - add user space interface for AEAD

AEAD requires the caller to specify the following information separate
from the data stream. This information allows the AEAD interface handler
to identify the AAD, ciphertext/plaintext and the authentication tag:

        * Associated authentication data of arbitrary length and
          length

        * Length of authentication tag for encryption
Signed-off-by: NStephan Mueller <smueller@chronox.de>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

crypto/af_alg.c

@@ -421,6 +421,12 @@ int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con)
 			con->op = *(u32 *)CMSG_DATA(cmsg);
 			break;
 
+		case ALG_SET_AEAD_ASSOCLEN:
+			if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
+				return -EINVAL;
+			con->aead_assoclen = *(u32 *)CMSG_DATA(cmsg);
+			break;
+
 		default:
 			return -EINVAL;
 		}

include/crypto/if_alg.h

@@ -42,6 +42,7 @@ struct af_alg_completion {
 struct af_alg_control {
 	struct af_alg_iv *iv;
 	int op;
+	unsigned int aead_assoclen;
 };
 
 struct af_alg_type {

include/uapi/linux/if_alg.h

@@ -32,6 +32,8 @@ struct af_alg_iv {
 #define ALG_SET_KEY			1
 #define ALG_SET_IV			2
 #define ALG_SET_OP			3
+#define ALG_SET_AEAD_ASSOCLEN		4
+#define ALG_SET_AEAD_AUTHSIZE		5
 
 /* Operations */
 #define ALG_OP_DECRYPT			0