root/net/ipv4/xfrm4_output.c

DEFINITIONS

1. xfrm4_tunnel_check_size
2. xfrm4_extract_output
3. xfrm4_prepare_output
4. xfrm4_output_finish
5. xfrm4_output

/*
 * 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;
        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->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(PF_INET, NF_INET_POST_ROUTING, skb,
                            NULL, skb->dst->dev, xfrm4_output_finish,
                            !(IPCB(skb)->flags & IPSKB_REROUTED));
}