2 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
3 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
5 * 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.
11 #include <linux/if_ether.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/netfilter_ipv4.h>
21 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
24 struct dst_entry *dst;
26 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
29 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
36 xfrm_local_error(skb, mtu);
38 icmp_send(skb, ICMP_DEST_UNREACH,
39 ICMP_FRAG_NEEDED, htonl(mtu));
46 int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
50 err = xfrm4_tunnel_check_size(skb);
54 XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
56 return xfrm4_extract_header(skb);
59 int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
63 err = xfrm_inner_extract_output(x, skb);
67 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
68 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;
70 skb->protocol = htons(ETH_P_IP);
72 return x->outer_mode->output2(x, skb);
74 EXPORT_SYMBOL(xfrm4_prepare_output);
76 int xfrm4_output_finish(struct sk_buff *skb)
78 #ifdef CONFIG_NETFILTER
79 if (!skb_dst(skb)->xfrm) {
80 IPCB(skb)->flags |= IPSKB_REROUTED;
81 return dst_output(skb);
84 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
87 skb->protocol = htons(ETH_P_IP);
88 return xfrm_output(skb);
91 int xfrm4_output(struct sk_buff *skb)
93 struct dst_entry *dst = skb_dst(skb);
94 struct xfrm_state *x = dst->xfrm;
96 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb,
98 x->outer_mode->afinfo->output_finish,
99 !(IPCB(skb)->flags & IPSKB_REROUTED));
102 void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
106 hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
107 ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
108 inet_sk(skb->sk)->inet_dport, mtu);