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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
WANG Cong60ff7462014-05-04 16:39:18 -070028 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_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
Steffen Klassert55967322014-04-07 08:08:52 +020065 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
Steffen Klassert044a8322015-01-12 13:38:49 +010066 skb->protocol = htons(ETH_P_IP);
Herbert Xu36cf9ac2007-11-13 21:40:52 -080067
68 return x->outer_mode->output2(x, skb);
69}
70EXPORT_SYMBOL(xfrm4_prepare_output);
71
David Miller7026b1d2015-04-05 22:19:04 -040072int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb)
Herbert Xu09b8f7a2006-06-22 03:08:03 -070073{
Steffen Klassert55967322014-04-07 08:08:52 +020074 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
Herbert Xu862b82c2007-11-13 21:43:11 -080075
Steffen Klassert55967322014-04-07 08:08:52 +020076#ifdef CONFIG_NETFILTER
Herbert Xu862b82c2007-11-13 21:43:11 -080077 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
Herbert Xu09b8f7a2006-06-22 03:08:03 -070078#endif
79
David Miller7026b1d2015-04-05 22:19:04 -040080 return xfrm_output(sk, skb);
Herbert Xu09b8f7a2006-06-22 03:08:03 -070081}
82
David Miller7026b1d2015-04-05 22:19:04 -040083static int __xfrm4_output(struct sock *sk, struct sk_buff *skb)
Steffen Klassert55967322014-04-07 08:08:52 +020084{
85 struct xfrm_state *x = skb_dst(skb)->xfrm;
86
87#ifdef CONFIG_NETFILTER
88 if (!x) {
89 IPCB(skb)->flags |= IPSKB_REROUTED;
David Miller7026b1d2015-04-05 22:19:04 -040090 return dst_output_sk(sk, skb);
Steffen Klassert55967322014-04-07 08:08:52 +020091 }
92#endif
93
David Miller7026b1d2015-04-05 22:19:04 -040094 return x->outer_mode->afinfo->output_finish(sk, skb);
Steffen Klassert55967322014-04-07 08:08:52 +020095}
96
Eric Dumazetaad88722014-04-15 13:47:15 -040097int xfrm4_output(struct sock *sk, struct sk_buff *skb)
Patrick McHardy16a66772006-01-06 23:01:48 -080098{
David Miller7026b1d2015-04-05 22:19:04 -040099 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb,
Steffen Klassert55967322014-04-07 08:08:52 +0200100 NULL, skb_dst(skb)->dev, __xfrm4_output,
Patrick McHardy48d5cad2006-02-15 15:10:22 -0800101 !(IPCB(skb)->flags & IPSKB_REROUTED));
Patrick McHardy16a66772006-01-06 23:01:48 -0800102}
Hannes Frederic Sowa628e3412013-08-14 13:05:23 +0200103
104void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
105{
106 struct iphdr *hdr;
107
108 hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
109 ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
110 inet_sk(skb->sk)->inet_dport, mtu);
111}