1/*
2 * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
3 * Copyright (C) 2002 USAGI/WIDE Project
4 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/if_ether.h>
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/skbuff.h>
16#include <linux/icmpv6.h>
17#include <linux/netfilter_ipv6.h>
18#include <net/dst.h>
19#include <net/ipv6.h>
20#include <net/ip6_route.h>
21#include <net/xfrm.h>
22
23int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
24			  u8 **prevhdr)
25{
26	return ip6_find_1stfragopt(skb, prevhdr);
27}
28EXPORT_SYMBOL(xfrm6_find_1stfragopt);
29
30static int xfrm6_local_dontfrag(struct sk_buff *skb)
31{
32	int proto;
33	struct sock *sk = skb->sk;
34
35	if (sk) {
36		if (sk->sk_family != AF_INET6)
37			return 0;
38
39		proto = sk->sk_protocol;
40		if (proto == IPPROTO_UDP || proto == IPPROTO_RAW)
41			return inet6_sk(sk)->dontfrag;
42	}
43
44	return 0;
45}
46
47static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
48{
49	struct flowi6 fl6;
50	struct sock *sk = skb->sk;
51
52	fl6.flowi6_oif = sk->sk_bound_dev_if;
53	fl6.daddr = ipv6_hdr(skb)->daddr;
54
55	ipv6_local_rxpmtu(sk, &fl6, mtu);
56}
57
58void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
59{
60	struct flowi6 fl6;
61	const struct ipv6hdr *hdr;
62	struct sock *sk = skb->sk;
63
64	hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb);
65	fl6.fl6_dport = inet_sk(sk)->inet_dport;
66	fl6.daddr = hdr->daddr;
67
68	ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
69}
70
71static int xfrm6_tunnel_check_size(struct sk_buff *skb)
72{
73	int mtu, ret = 0;
74	struct dst_entry *dst = skb_dst(skb);
75
76	mtu = dst_mtu(dst);
77	if (mtu < IPV6_MIN_MTU)
78		mtu = IPV6_MIN_MTU;
79
80	if (!skb->ignore_df && skb->len > mtu) {
81		skb->dev = dst->dev;
82
83		if (xfrm6_local_dontfrag(skb))
84			xfrm6_local_rxpmtu(skb, mtu);
85		else if (skb->sk)
86			xfrm_local_error(skb, mtu);
87		else
88			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
89		ret = -EMSGSIZE;
90	}
91
92	return ret;
93}
94
95int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
96{
97	int err;
98
99	err = xfrm6_tunnel_check_size(skb);
100	if (err)
101		return err;
102
103	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
104
105	return xfrm6_extract_header(skb);
106}
107
108int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
109{
110	int err;
111
112	err = xfrm_inner_extract_output(x, skb);
113	if (err)
114		return err;
115
116	skb->ignore_df = 1;
117
118	return x->outer_mode->output2(x, skb);
119}
120EXPORT_SYMBOL(xfrm6_prepare_output);
121
122int xfrm6_output_finish(struct sk_buff *skb)
123{
124	memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
125	skb->protocol = htons(ETH_P_IPV6);
126
127#ifdef CONFIG_NETFILTER
128	IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
129#endif
130
131	return xfrm_output(skb);
132}
133
134static int __xfrm6_output(struct sk_buff *skb)
135{
136	struct dst_entry *dst = skb_dst(skb);
137	struct xfrm_state *x = dst->xfrm;
138	int mtu;
139
140#ifdef CONFIG_NETFILTER
141	if (!x) {
142		IP6CB(skb)->flags |= IP6SKB_REROUTED;
143		return dst_output(skb);
144	}
145#endif
146
147	if (skb->protocol == htons(ETH_P_IPV6))
148		mtu = ip6_skb_dst_mtu(skb);
149	else
150		mtu = dst_mtu(skb_dst(skb));
151
152	if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {
153		xfrm6_local_rxpmtu(skb, mtu);
154		return -EMSGSIZE;
155	} else if (!skb->ignore_df && skb->len > mtu && skb->sk) {
156		xfrm_local_error(skb, mtu);
157		return -EMSGSIZE;
158	}
159
160	if (x->props.mode == XFRM_MODE_TUNNEL &&
161	    ((skb->len > mtu && !skb_is_gso(skb)) ||
162		dst_allfrag(skb_dst(skb)))) {
163			return ip6_fragment(skb, x->outer_mode->afinfo->output_finish);
164	}
165	return x->outer_mode->afinfo->output_finish(skb);
166}
167
168int xfrm6_output(struct sock *sk, struct sk_buff *skb)
169{
170	return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb,
171			    NULL, skb_dst(skb)->dev, __xfrm6_output,
172			    !(IP6CB(skb)->flags & IP6SKB_REROUTED));
173}
174