[IPSEC]: Add support for combined mode algorithms

This patch adds support for combined mode algorithms with GCM being
the first algorithm supported.

Combined mode algorithms can be added through the xfrm_user interface
using the new algorithm payload type XFRMA_ALG_AEAD.  Each algorithms
is identified by its name and the ICV length.

For the purposes of matching algorithms in xfrm_tmpl structures,
combined mode algorithms occupy the same name space as encryption
algorithms.  This is in line with how they are negotiated using IKE.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 5ebb9ba479b1..34d373775a0e 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -159,6 +159,7 @@ struct xfrm_state
         struct xfrm_algo        *aalg;
         struct xfrm_algo        *ealg;
         struct xfrm_algo        *calg;
+        struct xfrm_algo_aead   *aead;
 
         /* Data for encapsulator */
         struct xfrm_encap_tmpl  *encap;
@@ -1108,6 +1109,10 @@ static inline int xfrm_id_proto_match(u8 proto, u8 userproto)
 /*
  * xfrm algorithm information
  */
+struct xfrm_algo_aead_info {
+        u16 icv_truncbits;
+};
+
 struct xfrm_algo_auth_info {
         u16 icv_truncbits;
         u16 icv_fullbits;
@@ -1127,6 +1132,7 @@ struct xfrm_algo_desc {
         char *compat;
         u8 available:1;
         union {
+                struct xfrm_algo_aead_info aead;
                 struct xfrm_algo_auth_info auth;
                 struct xfrm_algo_encr_info encr;
                 struct xfrm_algo_comp_info comp;
@@ -1343,6 +1349,8 @@ extern struct xfrm_algo_desc *xfrm_calg_get_byid(int alg_id);
 extern struct xfrm_algo_desc *xfrm_aalg_get_byname(char *name, int probe);
 extern struct xfrm_algo_desc *xfrm_ealg_get_byname(char *name, int probe);
 extern struct xfrm_algo_desc *xfrm_calg_get_byname(char *name, int probe);
+extern struct xfrm_algo_desc *xfrm_aead_get_byname(char *name, int icv_len,
+                                                   int probe);
 
 struct hash_desc;
 struct scatterlist;