crypto: af_alg - add setsockopt for auth tag size

Use setsockopt on the tfm FD to provide the authentication tag size for
an AEAD cipher. This is achieved by adding a callback function which is
intended to be used by the AEAD AF_ALG implementation.

The optlen argument of the setsockopt specifies the authentication tag
size to be used with the AEAD tfm.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

2 files changed, 8 insertions, 0 deletions

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 8ffc174a0154..a8ff3c44e13c 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -215,6 +215,13 @@ static int alg_setsockopt(struct socket *sock, int level, int optname,
                         goto unlock;
 
                 err = alg_setkey(sk, optval, optlen);
+                break;
+        case ALG_SET_AEAD_AUTHSIZE:
+                if (sock->state == SS_CONNECTED)
+                        goto unlock;
+                if (!type->setauthsize)
+                        goto unlock;
+                err = type->setauthsize(ask->private, optlen);
         }
 
 unlock:
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index cd62bf4289e9..5c7b6c53e96f 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -50,6 +50,7 @@ struct af_alg_type {
         void (*release)(void *private);
         int (*setkey)(void *private, const u8 *key, unsigned int keylen);
         int (*accept)(void *private, struct sock *sk);
+        int (*setauthsize)(void *private, unsigned int authsize);
 
         struct proto_ops *ops;
         struct module *owner;