[PATCH 1/8] crypto: AF_ALG: add user space interface for AEAD

[Stephan Mueller <smueller@chronox.de>]

AEAD requires the following data in addition to normal symmetric
ciphers:

	* Associated authentication data of arbitrary length

	* Authentication tag for decryption

	* Length of authentication tag for encryption

The authentication tag data is communicated as part of the actual
ciphertext as mandated by the kernel crypto API. Therefore we only need
to provide a user space interface for the associated authentication data
as well as for the authentication tag length.

This patch adds both as a setsockopt interface that is identical to the
AF_ALG interface for setting an IV and for selecting the cipher
operation type (encrypt or decrypt).

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 crypto/af_alg.c             | 17 +++++++++++++++++
 include/crypto/if_alg.h     |  2 ++
 include/uapi/linux/if_alg.h |  7 +++++++
 3 files changed, 26 insertions(+)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 6a3ad80..635140b 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -421,6 +421,23 @@ int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con)
 			con->op = *(u32 *)CMSG_DATA(cmsg);
 			break;
 
+
+		case ALG_SET_AEAD_AUTHSIZE:
+			if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
+				return -EINVAL;
+			con->aead_authsize = *(u32 *)CMSG_DATA(cmsg);
+			break;
+
+		case ALG_SET_AEAD_ASSOC:
+			if (cmsg->cmsg_len < CMSG_LEN(sizeof(*con->aead_assoc)))
+				return -EINVAL;
+			con->aead_assoc = (void *)CMSG_DATA(cmsg);
+			if (cmsg->cmsg_len <
+				CMSG_LEN(con->aead_assoc->aead_assoclen +
+					 sizeof(*con->aead_assoc)))
+				return -EINVAL;
+			break;
+
 		default:
 			return -EINVAL;
 		}
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index d61c111..c741483 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -41,7 +41,9 @@ struct af_alg_completion {
 
 struct af_alg_control {
 	struct af_alg_iv *iv;
+	struct af_alg_aead_assoc *aead_assoc;
 	int op;
+	unsigned int aead_authsize;
 };
 
 struct af_alg_type {
diff --git a/include/uapi/linux/if_alg.h b/include/uapi/linux/if_alg.h
index 0f9acce..64e7008 100644
--- a/include/uapi/linux/if_alg.h
+++ b/include/uapi/linux/if_alg.h
@@ -28,10 +28,17 @@ struct af_alg_iv {
 	__u8	iv[0];
 };
 
+struct af_alg_aead_assoc {
+	__u32	aead_assoclen;
+	__u8	aead_assoc[0];
+};
+
 /* Socket options */
 #define ALG_SET_KEY			1
 #define ALG_SET_IV			2
 #define ALG_SET_OP			3
+#define ALG_SET_AEAD_ASSOC		4
+#define ALG_SET_AEAD_AUTHSIZE		5
 
 /* Operations */
 #define ALG_OP_DECRYPT			0
-- 
2.1.0