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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
3 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09004 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 */
10
Herbert Xu09b8f7a2006-06-22 03:08:03 -070011#include <linux/if_ether.h>
12#include <linux/kernel.h>
Herbert Xu36cf9ac2007-11-13 21:40:52 -080013#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/skbuff.h>
Patrick McHardy16a66772006-01-06 23:01:48 -080015#include <linux/netfilter_ipv4.h>
Herbert Xu36cf9ac2007-11-13 21:40:52 -080016#include <net/dst.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <net/ip.h>
18#include <net/xfrm.h>
19#include <net/icmp.h>
20
Linus Torvalds1da177e2005-04-16 15:20:36 -070021static int xfrm4_tunnel_check_size(struct sk_buff *skb)
22{
23 int mtu, ret = 0;
24 struct dst_entry *dst;
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
26 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
27 goto out;
28
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070029 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 goto out;
31
32 dst = skb->dst;
33 mtu = dst_mtu(dst);
34 if (skb->len > mtu) {
35 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
36 ret = -EMSGSIZE;
37 }
38out:
39 return ret;
40}
41
Herbert Xu36cf9ac2007-11-13 21:40:52 -080042int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -070043{
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 int err;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090045
Herbert Xu36cf9ac2007-11-13 21:40:52 -080046 err = xfrm4_tunnel_check_size(skb);
47 if (err)
48 return err;
49
Herbert Xu60d5fcf2007-11-19 18:47:58 -080050 XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
51
Herbert Xu36cf9ac2007-11-13 21:40:52 -080052 return xfrm4_extract_header(skb);
53}
54
55int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
56{
57 int err;
58
Kazunori MIYAZAWAdf9dcb42008-03-24 14:51:51 -070059 err = xfrm_inner_extract_output(x, skb);
Herbert Xu36cf9ac2007-11-13 21:40:52 -080060 if (err)
61 return err;
62
63 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
Herbert Xu862b82c2007-11-13 21:43:11 -080064 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;
Herbert Xu36cf9ac2007-11-13 21:40:52 -080065
66 skb->protocol = htons(ETH_P_IP);
67
68 return x->outer_mode->output2(x, skb);
69}
70EXPORT_SYMBOL(xfrm4_prepare_output);
71
Herbert Xu09b8f7a2006-06-22 03:08:03 -070072static int xfrm4_output_finish(struct sk_buff *skb)
73{
Herbert Xu09b8f7a2006-06-22 03:08:03 -070074#ifdef CONFIG_NETFILTER
75 if (!skb->dst->xfrm) {
76 IPCB(skb)->flags |= IPSKB_REROUTED;
77 return dst_output(skb);
78 }
Herbert Xu862b82c2007-11-13 21:43:11 -080079
80 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
Herbert Xu09b8f7a2006-06-22 03:08:03 -070081#endif
82
Herbert Xu09b8f7a2006-06-22 03:08:03 -070083 skb->protocol = htons(ETH_P_IP);
Herbert Xu862b82c2007-11-13 21:43:11 -080084 return xfrm_output(skb);
Herbert Xu09b8f7a2006-06-22 03:08:03 -070085}
86
Patrick McHardy16a66772006-01-06 23:01:48 -080087int xfrm4_output(struct sk_buff *skb)
88{
Patrick McHardy6e23ae22007-11-19 18:53:30 -080089 return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb,
90 NULL, skb->dst->dev, xfrm4_output_finish,
Patrick McHardy48d5cad2006-02-15 15:10:22 -080091 !(IPCB(skb)->flags & IPSKB_REROUTED));
Patrick McHardy16a66772006-01-06 23:01:48 -080092}