[IPSEC] xfrm: Abstract out encapsulation modes

This patch adds the structure xfrm_mode.  It is meant to represent
the operations carried out by transport/tunnel modes.

By doing this we allow additional encapsulation modes to be added
without clogging up the xfrm_input/xfrm_output paths.

Candidate modes include 4-to-6 tunnel mode, 6-to-4 tunnel mode, and
BEET modes.

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

2 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index 6b42cc474c01..46a15c7a1a13 100644
--- a/include/linux/xfrm.h
+++ b/include/linux/xfrm.h
@@ -118,6 +118,10 @@ enum
         XFRM_SHARE_UNIQUE       /* Use once */
 };
 
+#define XFRM_MODE_TRANSPORT 0
+#define XFRM_MODE_TUNNEL 1
+#define XFRM_MODE_MAX 2
+
 /* Netlink configuration messages.  */
 enum {
         XFRM_MSG_BASE = 0x10,
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index ed7c9747059d..ed5bb34f817f 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -20,6 +20,8 @@
 #include <net/ip6_fib.h>
 
 #define XFRM_ALIGN8(len)        (((len) + 7) & ~7)
+#define MODULE_ALIAS_XFRM_MODE(family, encap) \
+        MODULE_ALIAS("xfrm-mode-" __stringify(family) "-" __stringify(encap))
 
 extern struct sock *xfrm_nl;
 extern u32 sysctl_xfrm_aevent_etime;
@@ -164,6 +166,7 @@ struct xfrm_state
         /* Reference to data common to all the instances of this
          * transformer. */
         struct xfrm_type        *type;
+        struct xfrm_mode        *mode;
 
         /* Security context */
         struct xfrm_sec_ctx     *security;
@@ -205,6 +208,7 @@ struct xfrm_dst;
 struct xfrm_policy_afinfo {
         unsigned short          family;
         struct xfrm_type        *type_map[256];
+        struct xfrm_mode        *mode_map[XFRM_MODE_MAX];
         struct dst_ops          *dst_ops;
         void                    (*garbage_collect)(void);
         int                     (*dst_lookup)(struct xfrm_dst **dst, struct flowi *fl);
@@ -267,6 +271,19 @@ extern int xfrm_unregister_type(struct xfrm_type *type, unsigned short family);
 extern struct xfrm_type *xfrm_get_type(u8 proto, unsigned short family);
 extern void xfrm_put_type(struct xfrm_type *type);
 
+struct xfrm_mode {
+        int (*input)(struct xfrm_state *x, struct sk_buff *skb);
+        int (*output)(struct sk_buff *skb);
+
+        struct module *owner;
+        unsigned int encap;
+};
+
+extern int xfrm_register_mode(struct xfrm_mode *mode, int family);
+extern int xfrm_unregister_mode(struct xfrm_mode *mode, int family);
+extern struct xfrm_mode *xfrm_get_mode(unsigned int encap, int family);
+extern void xfrm_put_mode(struct xfrm_mode *mode);
+
 struct xfrm_tmpl
 {
 /* id in template is interpreted as: