146 lines
3.1 KiB
C
146 lines
3.1 KiB
C
/*
|
|
* 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/skbuff.h>
|
|
#include <linux/spinlock.h>
|
|
#include <net/inet_ecn.h>
|
|
#include <net/ip.h>
|
|
#include <net/xfrm.h>
|
|
#include <net/icmp.h>
|
|
|
|
/* Add encapsulation header.
|
|
*
|
|
* In transport mode, the IP header will be moved forward to make space
|
|
* for the encapsulation header.
|
|
*
|
|
* In tunnel mode, the top IP header will be constructed per RFC 2401.
|
|
* The following fields in it shall be filled in by x->type->output:
|
|
* tot_len
|
|
* check
|
|
*
|
|
* On exit, skb->h will be set to the start of the payload to be processed
|
|
* by x->type->output and skb->nh will be set to the top IP header.
|
|
*/
|
|
static void xfrm4_encap(struct sk_buff *skb)
|
|
{
|
|
struct dst_entry *dst = skb->dst;
|
|
struct xfrm_state *x = dst->xfrm;
|
|
struct iphdr *iph, *top_iph;
|
|
int flags;
|
|
|
|
iph = skb->nh.iph;
|
|
skb->h.ipiph = iph;
|
|
|
|
skb->nh.raw = skb_push(skb, x->props.header_len);
|
|
top_iph = skb->nh.iph;
|
|
|
|
if (!x->props.mode) {
|
|
skb->h.raw += iph->ihl*4;
|
|
memmove(top_iph, iph, iph->ihl*4);
|
|
return;
|
|
}
|
|
|
|
top_iph->ihl = 5;
|
|
top_iph->version = 4;
|
|
|
|
/* DS disclosed */
|
|
top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
|
|
|
|
flags = x->props.flags;
|
|
if (flags & XFRM_STATE_NOECN)
|
|
IP_ECN_clear(top_iph);
|
|
|
|
top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
|
|
0 : (iph->frag_off & htons(IP_DF));
|
|
if (!top_iph->frag_off)
|
|
__ip_select_ident(top_iph, dst, 0);
|
|
|
|
top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
|
|
|
|
top_iph->saddr = x->props.saddr.a4;
|
|
top_iph->daddr = x->id.daddr.a4;
|
|
top_iph->protocol = IPPROTO_IPIP;
|
|
|
|
memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
|
|
}
|
|
|
|
static int xfrm4_tunnel_check_size(struct sk_buff *skb)
|
|
{
|
|
int mtu, ret = 0;
|
|
struct dst_entry *dst;
|
|
struct iphdr *iph = skb->nh.iph;
|
|
|
|
if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
|
|
goto out;
|
|
|
|
IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
|
|
|
|
if (!(iph->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_output(struct sk_buff *skb)
|
|
{
|
|
struct dst_entry *dst = skb->dst;
|
|
struct xfrm_state *x = dst->xfrm;
|
|
int err;
|
|
|
|
if (skb->ip_summed == CHECKSUM_HW) {
|
|
err = skb_checksum_help(skb, 0);
|
|
if (err)
|
|
goto error_nolock;
|
|
}
|
|
|
|
if (x->props.mode) {
|
|
err = xfrm4_tunnel_check_size(skb);
|
|
if (err)
|
|
goto error_nolock;
|
|
}
|
|
|
|
spin_lock_bh(&x->lock);
|
|
err = xfrm_state_check(x, skb);
|
|
if (err)
|
|
goto error;
|
|
|
|
xfrm4_encap(skb);
|
|
|
|
err = x->type->output(x, skb);
|
|
if (err)
|
|
goto error;
|
|
|
|
x->curlft.bytes += skb->len;
|
|
x->curlft.packets++;
|
|
|
|
spin_unlock_bh(&x->lock);
|
|
|
|
if (!(skb->dst = dst_pop(dst))) {
|
|
err = -EHOSTUNREACH;
|
|
goto error_nolock;
|
|
}
|
|
err = NET_XMIT_BYPASS;
|
|
|
|
out_exit:
|
|
return err;
|
|
error:
|
|
spin_unlock_bh(&x->lock);
|
|
error_nolock:
|
|
kfree_skb(skb);
|
|
goto out_exit;
|
|
}
|