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		skb->protocol = htons(ETH_P_IPV6);
83
84		if (xfrm6_local_dontfrag(skb))
85			xfrm6_local_rxpmtu(skb, mtu);
86		else if (skb->sk)
87			xfrm_local_error(skb, mtu);
88		else
89			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
90		ret = -EMSGSIZE;
91	}
92
93	return ret;
94}
95
96int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
97{
98	int err;
99
100	err = xfrm6_tunnel_check_size(skb);
101	if (err)
102		return err;
103
104	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
105
106	return xfrm6_extract_header(skb);
107}
108
109int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
110{
111	int err;
112
113	err = xfrm_inner_extract_output(x, skb);
114	if (err)
115		return err;
116
117	skb->ignore_df = 1;
118	skb->protocol = htons(ETH_P_IPV6);
119
120	return x->outer_mode->output2(x, skb);
121}
122EXPORT_SYMBOL(xfrm6_prepare_output);
123
124int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb)
125{
126	memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
127
128#ifdef CONFIG_NETFILTER
129	IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
130#endif
131
132	return xfrm_output(sk, skb);
133}
134
135static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
136{
137	struct xfrm_state *x = skb_dst(skb)->xfrm;
138
139	return x->outer_mode->afinfo->output_finish(sk, skb);
140}
141
142static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
143{
144	struct dst_entry *dst = skb_dst(skb);
145	struct xfrm_state *x = dst->xfrm;
146	int mtu;
147	bool toobig;
148
149#ifdef CONFIG_NETFILTER
150	if (!x) {
151		IP6CB(skb)->flags |= IP6SKB_REROUTED;
152		return dst_output(net, sk, skb);
153	}
154#endif
155
156	if (x->props.mode != XFRM_MODE_TUNNEL)
157		goto skip_frag;
158
159	if (skb->protocol == htons(ETH_P_IPV6))
160		mtu = ip6_skb_dst_mtu(skb);
161	else
162		mtu = dst_mtu(skb_dst(skb));
163
164	toobig = skb->len > mtu && !skb_is_gso(skb);
165
166	if (toobig && xfrm6_local_dontfrag(skb)) {
167		xfrm6_local_rxpmtu(skb, mtu);
168		return -EMSGSIZE;
169	} else if (!skb->ignore_df && toobig && skb->sk) {
170		xfrm_local_error(skb, mtu);
171		return -EMSGSIZE;
172	}
173
174	if (toobig || dst_allfrag(skb_dst(skb)))
175		return ip6_fragment(net, sk, skb,
176				    __xfrm6_output_finish);
177
178skip_frag:
179	return x->outer_mode->afinfo->output_finish(sk, skb);
180}
181
182int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
183{
184	return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
185			    net, sk, skb,  NULL, skb_dst(skb)->dev,
186			    __xfrm6_output,
187			    !(IP6CB(skb)->flags & IP6SKB_REROUTED));
188}
189