1/*
  2 * xfrm6_mode_beet.c - BEET mode encapsulation for IPv6.
  3 *
  4 * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com>
  5 *                    Miika Komu     <miika@iki.fi>
  6 *                    Herbert Xu     <herbert@gondor.apana.org.au>
  7 *                    Abhinav Pathak <abhinav.pathak@hiit.fi>
  8 *                    Jeff Ahrenholz <ahrenholz@gmail.com>
  9 */
 10
 11#include <linux/init.h>
 12#include <linux/kernel.h>
 13#include <linux/module.h>
 14#include <linux/skbuff.h>
 15#include <linux/stringify.h>
 16#include <net/dsfield.h>
 17#include <net/dst.h>
 18#include <net/inet_ecn.h>
 19#include <net/ipv6.h>
 20#include <net/xfrm.h>
 21
 22static void xfrm6_beet_make_header(struct sk_buff *skb)
 23{
 24	struct ipv6hdr *iph = ipv6_hdr(skb);
 25
 26	iph->version = 6;
 27
 28	memcpy(iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
 29	       sizeof(iph->flow_lbl));
 30	iph->nexthdr = XFRM_MODE_SKB_CB(skb)->protocol;
 31
 32	ipv6_change_dsfield(iph, 0, XFRM_MODE_SKB_CB(skb)->tos);
 33	iph->hop_limit = XFRM_MODE_SKB_CB(skb)->ttl;
 34}
 35
 36/* Add encapsulation header.
 37 *
 38 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
 39 */
 40static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
 41{
 42	struct ipv6hdr *top_iph;
 43	struct ip_beet_phdr *ph;
 44	int optlen, hdr_len;
 45
 46	hdr_len = 0;
 47	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
 48	if (unlikely(optlen))
 49		hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
 50
 51	skb_set_network_header(skb, -x->props.header_len - hdr_len);
 52	if (x->sel.family != AF_INET6)
 53		skb->network_header += IPV4_BEET_PHMAXLEN;
 54	skb->mac_header = skb->network_header +
 55			  offsetof(struct ipv6hdr, nexthdr);
 56	skb->transport_header = skb->network_header + sizeof(*top_iph);
 57	ph = (struct ip_beet_phdr *)__skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl-hdr_len);
 58
 59	xfrm6_beet_make_header(skb);
 60
 61	top_iph = ipv6_hdr(skb);
 62	if (unlikely(optlen)) {
 63
 64		BUG_ON(optlen < 0);
 65
 66		ph->padlen = 4 - (optlen & 4);
 67		ph->hdrlen = optlen / 8;
 68		ph->nexthdr = top_iph->nexthdr;
 69		if (ph->padlen)
 70			memset(ph + 1, IPOPT_NOP, ph->padlen);
 71
 72		top_iph->nexthdr = IPPROTO_BEETPH;
 73	}
 74
 75	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
 76	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
 77	return 0;
 78}
 79
 80static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
 81{
 82	struct ipv6hdr *ip6h;
 83	int size = sizeof(struct ipv6hdr);
 84	int err;
 85
 86	err = skb_cow_head(skb, size + skb->mac_len);
 87	if (err)
 88		goto out;
 89
 90	__skb_push(skb, size);
 91	skb_reset_network_header(skb);
 92	skb_mac_header_rebuild(skb);
 93
 94	xfrm6_beet_make_header(skb);
 95
 96	ip6h = ipv6_hdr(skb);
 97	ip6h->payload_len = htons(skb->len - size);
 98	ip6h->daddr = x->sel.daddr.in6;
 99	ip6h->saddr = x->sel.saddr.in6;
100	err = 0;
101out:
102	return err;
103}
104
105static struct xfrm_mode xfrm6_beet_mode = {
106	.input2 = xfrm6_beet_input,
107	.input = xfrm_prepare_input,
108	.output2 = xfrm6_beet_output,
109	.output = xfrm6_prepare_output,
110	.owner = THIS_MODULE,
111	.encap = XFRM_MODE_BEET,
112	.flags = XFRM_MODE_FLAG_TUNNEL,
113};
114
115static int __init xfrm6_beet_init(void)
116{
117	return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
118}
119
120static void __exit xfrm6_beet_exit(void)
121{
122	int err;
123
124	err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
125	BUG_ON(err);
126}
127
128module_init(xfrm6_beet_init);
129module_exit(xfrm6_beet_exit);
130MODULE_LICENSE("GPL");
131MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);