aboutsummaryrefslogblamecommitdiffstats
path: root/net/ipv4/xfrm4_output.c
blob: 571aa96a175c956fb81728030441309286b938c9 (plain) (tree)
1
2
3
4
5
6
7
8
9
10


                                                              
  





                                                                

                           
                         
                         
                                 
                    



                     



                                                       



                                                      
                                                                     

                         
                           








                                                                                







                                                                   

                                                                






                                                                   
                                                



                                                 
                                                                            






                                              

                                                   
                       
                                  


                                                   
 

                                                   

                                        
                                

 

                                     
                                                                    
                                                                         
                                                                  
 
/*
 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/if_ether.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4.h>
#include <net/dst.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/icmp.h>

static int xfrm4_tunnel_check_size(struct sk_buff *skb)
{
	int mtu, ret = 0;
	struct dst_entry *dst;

	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
		goto out;

	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
		goto out;

	dst = skb_dst(skb);
	mtu = dst_mtu(dst);
	if (skb->len > mtu) {
		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
		ret = -EMSGSIZE;
	}
out:
	return ret;
}

int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
{
	int err;

	err = xfrm4_tunnel_check_size(skb);
	if (err)
		return err;

	XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;

	return xfrm4_extract_header(skb);
}

int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
{
	int err;

	err = xfrm_inner_extract_output(x, skb);
	if (err)
		return err;

	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;

	skb->protocol = htons(ETH_P_IP);

	return x->outer_mode->output2(x, skb);
}
EXPORT_SYMBOL(xfrm4_prepare_output);

static int xfrm4_output_finish(struct sk_buff *skb)
{
#ifdef CONFIG_NETFILTER
	if (!skb_dst(skb)->xfrm) {
		IPCB(skb)->flags |= IPSKB_REROUTED;
		return dst_output(skb);
	}

	IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
#endif

	skb->protocol = htons(ETH_P_IP);
	return xfrm_output(skb);
}

int xfrm4_output(struct sk_buff *skb)
{
	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb,
			    NULL, skb_dst(skb)->dev, xfrm4_output_finish,
			    !(IPCB(skb)->flags & IPSKB_REROUTED));
}