[IPSEC]: Separate inner/outer mode processing on input

With inter-family transforms the inner mode differs from the outer
mode.  Attempting to handle both sides from the same function means
that it needs to handle both IPv4 and IPv6 which creates duplication
and confusion.

This patch separates the two parts on the input path so that each
function deals with one family only.

In particular, the functions xfrm4_extract_inut/xfrm6_extract_inut
moves the pertinent fields from the IPv4/IPv6 IP headers into a
neutral format stored in skb->cb.  This is then used by the inner mode
input functions to modify the inner IP header.  In this way the input
function no longer has to know about the outer address family.

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

1 files changed, 27 insertions, 0 deletions

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 138c1868be1d..a9dbe091ae58 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -258,6 +258,7 @@ extern int __xfrm_state_delete(struct xfrm_state *x);
 struct xfrm_state_afinfo {
         unsigned int            family;
         unsigned int            proto;
+        unsigned int            eth_proto;
         struct module           *owner;
         struct xfrm_type        *type_map[IPPROTO_MAX];
         struct xfrm_mode        *mode_map[XFRM_MODE_MAX];
@@ -268,6 +269,8 @@ struct xfrm_state_afinfo {
         int                     (*tmpl_sort)(struct xfrm_tmpl **dst, struct xfrm_tmpl **src, int n);
         int                     (*state_sort)(struct xfrm_state **dst, struct xfrm_state **src, int n);
         int                     (*output)(struct sk_buff *skb);
+        int                     (*extract_input)(struct xfrm_state *x,
+                                                 struct sk_buff *skb);
         int                     (*extract_output)(struct xfrm_state *x,
                                                   struct sk_buff *skb);
 };
@@ -302,6 +305,27 @@ extern int xfrm_register_type(struct xfrm_type *type, unsigned short family);
 extern int xfrm_unregister_type(struct xfrm_type *type, unsigned short family);
 
 struct xfrm_mode {
+        /*
+         * Remove encapsulation header.
+         *
+         * The IP header will be moved over the top of the encapsulation
+         * header.
+         *
+         * On entry, the transport header shall point to where the IP header
+         * should be and the network header shall be set to where the IP
+         * header currently is.  skb->data shall point to the start of the
+         * payload.
+         */
+        int (*input2)(struct xfrm_state *x, struct sk_buff *skb);
+
+        /*
+         * This is the actual input entry point.
+         *
+         * For transport mode and equivalent this would be identical to
+         * input2 (which does not need to be set).  While tunnel mode
+         * and equivalent would set this to the tunnel encapsulation function
+         * xfrm4_prepare_input that would in turn call input2.
+         */
         int (*input)(struct xfrm_state *x, struct sk_buff *skb);
 
         /*
@@ -1093,8 +1117,10 @@ extern void xfrm_replay_advance(struct xfrm_state *x, __be32 seq);
 extern void xfrm_replay_notify(struct xfrm_state *x, int event);
 extern int xfrm_state_mtu(struct xfrm_state *x, int mtu);
 extern int xfrm_init_state(struct xfrm_state *x);
+extern int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb);
 extern int xfrm_output(struct sk_buff *skb);
 extern int xfrm4_extract_header(struct sk_buff *skb);
+extern int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb);
 extern int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
                            int encap_type);
 extern int xfrm4_rcv(struct sk_buff *skb);
@@ -1110,6 +1136,7 @@ extern int xfrm4_output(struct sk_buff *skb);
 extern int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family);
 extern int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family);
 extern int xfrm6_extract_header(struct sk_buff *skb);
+extern int xfrm6_extract_input(struct xfrm_state *x, struct sk_buff *skb);
 extern int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi);
 extern int xfrm6_rcv(struct sk_buff *skb);
 extern int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,