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
xfrm6_find_1stfragopt(struct xfrm_state * x,struct sk_buff * skb,u8 ** prevhdr)23 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
24 u8 **prevhdr)
25 {
26 return ip6_find_1stfragopt(skb, prevhdr);
27 }
28 EXPORT_SYMBOL(xfrm6_find_1stfragopt);
29
xfrm6_local_dontfrag(struct sk_buff * skb)30 static 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
xfrm6_local_rxpmtu(struct sk_buff * skb,u32 mtu)47 static 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
xfrm6_local_error(struct sk_buff * skb,u32 mtu)58 void 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
xfrm6_tunnel_check_size(struct sk_buff * skb)71 static 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
xfrm6_extract_output(struct xfrm_state * x,struct sk_buff * skb)95 int 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
xfrm6_prepare_output(struct xfrm_state * x,struct sk_buff * skb)108 int 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 }
120 EXPORT_SYMBOL(xfrm6_prepare_output);
121
xfrm6_output_finish(struct sk_buff * skb)122 int 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
__xfrm6_output(struct sk_buff * skb)134 static 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
xfrm6_output(struct sock * sk,struct sk_buff * skb)168 int 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