[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>

1 files changed, 3 insertions, 60 deletions

diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c
index 80242172a5df..16e84254a252 100644
--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -14,68 +14,9 @@
 #include <linux/spinlock.h>
 #include <linux/icmpv6.h>
 #include <linux/netfilter_ipv6.h>
-#include <net/dsfield.h>
-#include <net/inet_ecn.h>
 #include <net/ipv6.h>
 #include <net/xfrm.h>
 
-/* Add encapsulation header.
- *
- * In transport mode, the IP header and mutable extension headers will be moved
- * forward to make space for the encapsulation header.
- *
- * In tunnel mode, the top IP header will be constructed per RFC 2401.
- * The following fields in it shall be filled in by x->type->output:
- *      payload_len
- *
- * On exit, skb->h will be set to the start of the encapsulation header to be
- * filled in by x->type->output and skb->nh will be set to the nextheader field
- * of the extension header directly preceding the encapsulation header, or in
- * its absence, that of the top IP header.  The value of skb->data will always
- * point to the top IP header.
- */
-static void xfrm6_encap(struct sk_buff *skb)
-{
-        struct dst_entry *dst = skb->dst;
-        struct xfrm_state *x = dst->xfrm;
-        struct ipv6hdr *iph, *top_iph;
-        int dsfield;
-
-        skb_push(skb, x->props.header_len);
-        iph = skb->nh.ipv6h;
-
-        if (!x->props.mode) {
-                u8 *prevhdr;
-                int hdr_len;
-
-                hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
-                skb->nh.raw = prevhdr - x->props.header_len;
-                skb->h.raw = skb->data + hdr_len;
-                memmove(skb->data, iph, hdr_len);
-                return;
-        }
-
-        skb->nh.raw = skb->data;
-        top_iph = skb->nh.ipv6h;
-        skb->nh.raw = &top_iph->nexthdr;
-        skb->h.ipv6h = top_iph + 1;
-
-        top_iph->version = 6;
-        top_iph->priority = iph->priority;
-        top_iph->flow_lbl[0] = iph->flow_lbl[0];
-        top_iph->flow_lbl[1] = iph->flow_lbl[1];
-        top_iph->flow_lbl[2] = iph->flow_lbl[2];
-        dsfield = ipv6_get_dsfield(top_iph);
-        dsfield = INET_ECN_encapsulate(dsfield, dsfield);
-        if (x->props.flags & XFRM_STATE_NOECN)
-                dsfield &= ~INET_ECN_MASK;
-        ipv6_change_dsfield(top_iph, 0, dsfield);
-        top_iph->nexthdr = IPPROTO_IPV6; 
-        top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
-        ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
-        ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
-}
-
 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
 {
         int mtu, ret = 0;
@@ -118,7 +59,9 @@ static int xfrm6_output_one(struct sk_buff *skb)
                 if (err)
                         goto error;
 
-                xfrm6_encap(skb);
+                err = x->mode->output(skb);
+                if (err)
+                        goto error;
 
                 err = x->type->output(x, skb);
                 if (err)