[PATCH v3 1/7] crypto: AF_ALG: add user space interface for AEAD

[Stephan Mueller]

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

        * Associated authentication data of arbitrary length and
	  length

        * Authentication tag for decryption and length

        * Length of authentication tag for encryption

The memory structure for the data received by the kernel via sendmsg
must follow this structure:

	* Symmetric encryption input:  plaintext
	* Symmetric encryption output: ciphertext
	* AEAD encryption input:  assoc data || plaintext
	* AEAD encryption output: cipherntext || auth tag
	* Symmetric decryption input:  ciphertext
	* Symmetric decryption output: plaintext
	* AEAD decryption input:  assoc data || ciphertext || authtag
	* AEAD decryption output: plaintext

Therefore, in addition to submitting the data, AEAD requires that
the associated data length and the tag length must be communicated.
The plaintext/ciphertext length can be derived from the other two size
fields. Therefore,  This patch adds setting the associated data length
and tag length as part of the sendmsg communication.

Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
---
 crypto/af_alg.c             | 12 ++++++++++++
 include/crypto/if_alg.h     |  2 ++
 include/uapi/linux/if_alg.h |  2 ++
 3 files changed, 16 insertions(+)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 6a3ad80..75eb88c 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -421,6 +421,18 @@ 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_ASSOCLEN:
+			if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
+				return -EINVAL;
+			con->aead_assoclen = *(u32 *)CMSG_DATA(cmsg);
+			break;
+
 		default:
 			return -EINVAL;
 		}
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index d61c111..60ed1b7 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -42,6 +42,8 @@ struct af_alg_completion {
 struct af_alg_control {
 	struct af_alg_iv *iv;
 	int op;
+	unsigned int aead_authsize;
+	unsigned int aead_assoclen;
 };
 
 struct af_alg_type {
diff --git a/include/uapi/linux/if_alg.h b/include/uapi/linux/if_alg.h
index 0f9acce..f2acd2f 100644
--- a/include/uapi/linux/if_alg.h
+++ b/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
-- 
2.1.0


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