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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
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
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
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
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
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 if (skb->ignore_df)
77 goto out;
78
79 mtu = dst_mtu(dst);
80 if (mtu < IPV6_MIN_MTU)
81 mtu = IPV6_MIN_MTU;
82
83 if ((!skb_is_gso(skb) && skb->len > mtu) ||
84 (skb_is_gso(skb) &&
85 !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
86 skb->dev = dst->dev;
87 skb->protocol = htons(ETH_P_IPV6);
88
89 if (xfrm6_local_dontfrag(skb))
90 xfrm6_local_rxpmtu(skb, mtu);
91 else if (skb->sk)
92 xfrm_local_error(skb, mtu);
93 else
94 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
95 ret = -EMSGSIZE;
96 }
97 out:
98 return ret;
99 }
100
101 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
102 {
103 int err;
104
105 err = xfrm6_tunnel_check_size(skb);
106 if (err)
107 return err;
108
109 XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
110
111 return xfrm6_extract_header(skb);
112 }
113
114 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
115 {
116 int err;
117
118 err = xfrm_inner_extract_output(x, skb);
119 if (err)
120 return err;
121
122 skb->ignore_df = 1;
123 skb->protocol = htons(ETH_P_IPV6);
124
125 return x->outer_mode->output2(x, skb);
126 }
127 EXPORT_SYMBOL(xfrm6_prepare_output);
128
129 int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb)
130 {
131 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
132
133 #ifdef CONFIG_NETFILTER
134 IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
135 #endif
136
137 return xfrm_output(sk, skb);
138 }
139
140 static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
141 {
142 struct xfrm_state *x = skb_dst(skb)->xfrm;
143
144 return x->outer_mode->afinfo->output_finish(sk, skb);
145 }
146
147 static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
148 {
149 struct dst_entry *dst = skb_dst(skb);
150 struct xfrm_state *x = dst->xfrm;
151 int mtu;
152 bool toobig;
153
154 #ifdef CONFIG_NETFILTER
155 if (!x) {
156 IP6CB(skb)->flags |= IP6SKB_REROUTED;
157 return dst_output(net, sk, skb);
158 }
159 #endif
160
161 if (x->props.mode != XFRM_MODE_TUNNEL)
162 goto skip_frag;
163
164 if (skb->protocol == htons(ETH_P_IPV6))
165 mtu = ip6_skb_dst_mtu(skb);
166 else
167 mtu = dst_mtu(skb_dst(skb));
168
169 toobig = skb->len > mtu && !skb_is_gso(skb);
170
171 if (toobig && xfrm6_local_dontfrag(skb)) {
172 xfrm6_local_rxpmtu(skb, mtu);
173 return -EMSGSIZE;
174 } else if (!skb->ignore_df && toobig && skb->sk) {
175 xfrm_local_error(skb, mtu);
176 return -EMSGSIZE;
177 }
178
179 if (toobig || dst_allfrag(skb_dst(skb)))
180 return ip6_fragment(net, sk, skb,
181 __xfrm6_output_finish);
182
183 skip_frag:
184 return x->outer_mode->afinfo->output_finish(sk, skb);
185 }
186
187 int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
188 {
189 return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
190 net, sk, skb, NULL, skb_dst(skb)->dev,
191 __xfrm6_output,
192 !(IP6CB(skb)->flags & IP6SKB_REROUTED));
193 }