[XFRM]: BEET mode

This patch introduces the BEET mode (Bound End-to-End Tunnel) with as
specified by the ietf draft at the following link:

http://www.ietf.org/internet-drafts/draft-nikander-esp-beet-mode-06.txt

The patch provides only single family support (i.e. inner family =
outer family).

Signed-off-by: Diego Beltrami <diego.beltrami@gmail.com>
Signed-off-by: Miika Komu     <miika@iki.fi>
Signed-off-by: Herbert Xu     <herbert@gondor.apana.org.au>
Signed-off-by: Abhinav Pathak <abhinav.pathak@hiit.fi>
Signed-off-by: Jeff Ahrenholz <ahrenholz@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 107 insertions, 0 deletions

diff --git a/net/ipv6/xfrm6_mode_beet.c b/net/ipv6/xfrm6_mode_beet.c
new file mode 100644
index 0000000..edcfffa
--- /dev/null
+++ b/net/ipv6/xfrm6_mode_beet.c
@@ -0,0 +1,107 @@
+/*
+ * xfrm6_mode_beet.c - BEET mode encapsulation for IPv6.
+ *
+ * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com>
+ *                    Miika Komu     <miika@iki.fi>
+ *                    Herbert Xu     <herbert@gondor.apana.org.au>
+ *                    Abhinav Pathak <abhinav.pathak@hiit.fi>
+ *                    Jeff Ahrenholz <ahrenholz@gmail.com>
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/stringify.h>
+#include <net/dsfield.h>
+#include <net/dst.h>
+#include <net/inet_ecn.h>
+#include <net/ipv6.h>
+#include <net/xfrm.h>
+
+/* Add encapsulation header.
+ *
+ * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
+ * 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 int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct ipv6hdr *iph, *top_iph;
+	u8 *prevhdr;
+	int hdr_len;
+
+	skb_push(skb, x->props.header_len);
+	iph = skb->nh.ipv6h;
+
+	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);
+
+	skb->nh.raw = skb->data;
+	top_iph = skb->nh.ipv6h;
+	skb->nh.raw = &top_iph->nexthdr;
+	skb->h.ipv6h = top_iph + 1;
+
+	ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
+	ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
+
+	return 0;
+}
+
+static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct ipv6hdr *ip6h;
+	int size = sizeof(struct ipv6hdr);
+	int err = -EINVAL;
+
+	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
+		goto out;
+
+	skb_push(skb, size);
+	memmove(skb->data, skb->nh.raw, size);
+	skb->nh.raw = skb->data;
+
+	skb->mac.raw = memmove(skb->data - skb->mac_len,
+			       skb->mac.raw, skb->mac_len);
+
+	ip6h = skb->nh.ipv6h;
+	ip6h->payload_len = htons(skb->len - size);
+	ipv6_addr_copy(&ip6h->daddr, (struct in6_addr *) &x->sel.daddr.a6);
+	ipv6_addr_copy(&ip6h->saddr, (struct in6_addr *) &x->sel.saddr.a6);
+	err = 0;
+out:
+	return err;
+}
+
+static struct xfrm_mode xfrm6_beet_mode = {
+	.input = xfrm6_beet_input,
+	.output = xfrm6_beet_output,
+	.owner = THIS_MODULE,
+	.encap = XFRM_MODE_BEET,
+};
+
+static int __init xfrm6_beet_init(void)
+{
+	return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
+}
+
+static void __exit xfrm6_beet_exit(void)
+{
+	int err;
+
+	err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
+	BUG_ON(err);
+}
+
+module_init(xfrm6_beet_init);
+module_exit(xfrm6_beet_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);