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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;
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
25 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
26 goto out;
27
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070028 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
Linus Torvalds1da177e2005-04-16 15:20:36 -070029 goto out;
30
Hannes Frederic Sowa5a25cf12013-08-26 12:31:19 +020031 mtu = dst_mtu(skb_dst(skb));
Linus Torvalds1da177e2005-04-16 15:20:36 -070032 if (skb->len > mtu) {
Steffen Klassertb00897b2011-06-29 23:20:41 +000033 if (skb->sk)
Hannes Frederic Sowa628e3412013-08-14 13:05:23 +020034 xfrm_local_error(skb, mtu);
Steffen Klassertb00897b2011-06-29 23:20:41 +000035 else
36 icmp_send(skb, ICMP_DEST_UNREACH,
37 ICMP_FRAG_NEEDED, htonl(mtu));
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 ret = -EMSGSIZE;
39 }
40out:
41 return ret;
42}
43
Herbert Xu36cf9ac2007-11-13 21:40:52 -080044int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -070045{
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 int err;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090047
Herbert Xu36cf9ac2007-11-13 21:40:52 -080048 err = xfrm4_tunnel_check_size(skb);
49 if (err)
50 return err;
51
Herbert Xu60d5fcf2007-11-19 18:47:58 -080052 XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
53
Herbert Xu36cf9ac2007-11-13 21:40:52 -080054 return xfrm4_extract_header(skb);
55}
56
57int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
58{
59 int err;
60
Kazunori MIYAZAWAdf9dcb42008-03-24 14:51:51 -070061 err = xfrm_inner_extract_output(x, skb);
Herbert Xu36cf9ac2007-11-13 21:40:52 -080062 if (err)
63 return err;
64
65 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
Herbert Xu862b82c2007-11-13 21:43:11 -080066 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;
Herbert Xu36cf9ac2007-11-13 21:40:52 -080067
68 skb->protocol = htons(ETH_P_IP);
69
70 return x->outer_mode->output2(x, skb);
71}
72EXPORT_SYMBOL(xfrm4_prepare_output);
73
Steffen Klassert43a4dea2011-05-09 19:36:38 +000074int xfrm4_output_finish(struct sk_buff *skb)
Herbert Xu09b8f7a2006-06-22 03:08:03 -070075{
Herbert Xu09b8f7a2006-06-22 03:08:03 -070076#ifdef CONFIG_NETFILTER
Eric Dumazetadf30902009-06-02 05:19:30 +000077 if (!skb_dst(skb)->xfrm) {
Herbert Xu09b8f7a2006-06-22 03:08:03 -070078 IPCB(skb)->flags |= IPSKB_REROUTED;
79 return dst_output(skb);
80 }
Herbert Xu862b82c2007-11-13 21:43:11 -080081
82 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
Herbert Xu09b8f7a2006-06-22 03:08:03 -070083#endif
84
Herbert Xu09b8f7a2006-06-22 03:08:03 -070085 skb->protocol = htons(ETH_P_IP);
Herbert Xu862b82c2007-11-13 21:43:11 -080086 return xfrm_output(skb);
Herbert Xu09b8f7a2006-06-22 03:08:03 -070087}
88
Patrick McHardy16a66772006-01-06 23:01:48 -080089int xfrm4_output(struct sk_buff *skb)
90{
Steffen Klassert43a4dea2011-05-09 19:36:38 +000091 struct dst_entry *dst = skb_dst(skb);
92 struct xfrm_state *x = dst->xfrm;
93
Jan Engelhardt9bbc7682010-03-23 04:07:29 +010094 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb,
Steffen Klassert43a4dea2011-05-09 19:36:38 +000095 NULL, dst->dev,
96 x->outer_mode->afinfo->output_finish,
Patrick McHardy48d5cad2006-02-15 15:10:22 -080097 !(IPCB(skb)->flags & IPSKB_REROUTED));
Patrick McHardy16a66772006-01-06 23:01:48 -080098}
Hannes Frederic Sowa628e3412013-08-14 13:05:23 +020099
100void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
101{
102 struct iphdr *hdr;
103
104 hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
105 ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
106 inet_sk(skb->sk)->inet_dport, mtu);
107}