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/*
* 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/compiler.h>
#include <linux/if_ether.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4.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;
IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
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;
}
static inline int xfrm4_output_one(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct xfrm_state *x = dst->xfrm;
struct iphdr *iph;
int err;
if (x->props.mode == XFRM_MODE_TUNNEL) {
err = xfrm4_tunnel_check_size(skb);
if (err)
goto error_nolock;
}
err = xfrm_output(skb);
if (err)
goto error_nolock;
iph = ip_hdr(skb);
iph->tot_len = htons(skb->len);
ip_send_check(iph);
IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
err = 0;
out_exit:
return err;
error_nolock:
kfree_skb(skb);
goto out_exit;
}
static int xfrm4_output_finish2(struct sk_buff *skb)
{
int err;
while (likely((err = xfrm4_output_one(skb)) == 0)) {
nf_reset(skb);
err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL,
skb->dst->dev, dst_output);
if (unlikely(err != 1))
break;
if (!skb->dst->xfrm)
return dst_output(skb);
err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL,
skb->dst->dev, xfrm4_output_finish2);
if (unlikely(err != 1))
break;
}
return err;
}
static int xfrm4_output_finish(struct sk_buff *skb)
{
struct sk_buff *segs;
#ifdef CONFIG_NETFILTER
if (!skb->dst->xfrm) {
IPCB(skb)->flags |= IPSKB_REROUTED;
return dst_output(skb);
}
#endif
if (!skb_is_gso(skb))
return xfrm4_output_finish2(skb);
skb->protocol = htons(ETH_P_IP);
segs = skb_gso_segment(skb, 0);
kfree_skb(skb);
if (unlikely(IS_ERR(segs)))
return PTR_ERR(segs);
do {
struct sk_buff *nskb = segs->next;
int err;
segs->next = NULL;
err = xfrm4_output_finish2(segs);
if (unlikely(err)) {
while ((segs = nskb)) {
nskb = segs->next;
segs->next = NULL;
kfree_skb(segs);
}
return err;
}
segs = nskb;
} while (segs);
return 0;
}
int xfrm4_output(struct sk_buff *skb)
{
return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
xfrm4_output_finish,
!(IPCB(skb)->flags & IPSKB_REROUTED));
}
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