xref: /linux/net/ipv6/xfrm6_output.c (revision d39d0ed196aa1685bb24771e92f78633c66ac9cb)
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/xfrm.h>
21 
22 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
23 			  u8 **prevhdr)
24 {
25 	return ip6_find_1stfragopt(skb, prevhdr);
26 }
27 
28 EXPORT_SYMBOL(xfrm6_find_1stfragopt);
29 
30 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
31 {
32 	int mtu, ret = 0;
33 	struct dst_entry *dst = skb_dst(skb);
34 
35 	mtu = dst_mtu(dst);
36 	if (mtu < IPV6_MIN_MTU)
37 		mtu = IPV6_MIN_MTU;
38 
39 	if (!skb->local_df && skb->len > mtu) {
40 		skb->dev = dst->dev;
41 		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
42 		ret = -EMSGSIZE;
43 	}
44 
45 	return ret;
46 }
47 
48 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
49 {
50 	int err;
51 
52 	err = xfrm6_tunnel_check_size(skb);
53 	if (err)
54 		return err;
55 
56 	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
57 
58 	return xfrm6_extract_header(skb);
59 }
60 
61 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
62 {
63 	int err;
64 
65 	err = xfrm_inner_extract_output(x, skb);
66 	if (err)
67 		return err;
68 
69 	memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
70 #ifdef CONFIG_NETFILTER
71 	IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
72 #endif
73 
74 	skb->protocol = htons(ETH_P_IPV6);
75 	skb->local_df = 1;
76 
77 	return x->outer_mode->output2(x, skb);
78 }
79 EXPORT_SYMBOL(xfrm6_prepare_output);
80 
81 static int xfrm6_output_finish(struct sk_buff *skb)
82 {
83 #ifdef CONFIG_NETFILTER
84 	IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
85 #endif
86 
87 	skb->protocol = htons(ETH_P_IPV6);
88 	return xfrm_output(skb);
89 }
90 
91 int xfrm6_output(struct sk_buff *skb)
92 {
93 	return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
94 		       skb_dst(skb)->dev, xfrm6_output_finish);
95 }
96