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);
132