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/*
* xfrm4_mode_tunnel.c - Tunnel mode encapsulation for IPv4.
*
* Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/stringify.h>
#include <net/dst.h>
#include <net/inet_ecn.h>
#include <net/ip.h>
#include <net/xfrm.h>
static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
{
struct iphdr *outer_iph = ip_hdr(skb);
struct iphdr *inner_iph = ipip_hdr(skb);
if (INET_ECN_is_ce(outer_iph->tos))
IP_ECN_set_ce(inner_iph);
}
static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
{
if (INET_ECN_is_ce(iph->tos))
IP6_ECN_set_ce(ipv6_hdr(skb));
}
/* Add encapsulation header.
*
* 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 int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
struct iphdr *iph, *top_iph;
int flags;
iph = ip_hdr(skb);
skb->transport_header = skb->network_header;
skb_push(skb, x->props.header_len);
skb_reset_network_header(skb);
top_iph = ip_hdr(skb);
top_iph->ihl = 5;
top_iph->version = 4;
flags = x->props.flags;
/* DS disclosed */
if (xdst->route->ops->family == AF_INET) {
top_iph->protocol = IPPROTO_IPIP;
top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
0 : (iph->frag_off & htons(IP_DF));
}
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
else {
struct ipv6hdr *ipv6h = (struct ipv6hdr*)iph;
top_iph->protocol = IPPROTO_IPV6;
top_iph->tos = INET_ECN_encapsulate(iph->tos, ipv6_get_dsfield(ipv6h));
top_iph->frag_off = 0;
}
#endif
if (flags & XFRM_STATE_NOECN)
IP_ECN_clear(top_iph);
if (!top_iph->frag_off)
__ip_select_ident(top_iph, dst->child, 0);
top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
top_iph->saddr = x->props.saddr.a4;
top_iph->daddr = x->id.daddr.a4;
skb->protocol = htons(ETH_P_IP);
memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
return 0;
}
static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
{
struct iphdr *iph = ip_hdr(skb);
const unsigned char *old_mac;
int err = -EINVAL;
switch (iph->protocol){
case IPPROTO_IPIP:
break;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
case IPPROTO_IPV6:
break;
#endif
default:
goto out;
}
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
goto out;
if (skb_cloned(skb) &&
(err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
goto out;
iph = ip_hdr(skb);
if (iph->protocol == IPPROTO_IPIP) {
if (x->props.flags & XFRM_STATE_DECAP_DSCP)
ipv4_copy_dscp(iph, ipip_hdr(skb));
if (!(x->props.flags & XFRM_STATE_NOECN))
ipip_ecn_decapsulate(skb);
}
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
else {
if (!(x->props.flags & XFRM_STATE_NOECN))
ipip6_ecn_decapsulate(iph, skb);
skb->protocol = htons(ETH_P_IPV6);
}
#endif
old_mac = skb_mac_header(skb);
skb_set_mac_header(skb, -skb->mac_len);
memmove(skb_mac_header(skb), old_mac, skb->mac_len);
skb_reset_network_header(skb);
err = 0;
out:
return err;
}
static struct xfrm_mode xfrm4_tunnel_mode = {
.input = xfrm4_tunnel_input,
.output = xfrm4_tunnel_output,
.owner = THIS_MODULE,
.encap = XFRM_MODE_TUNNEL,
};
static int __init xfrm4_tunnel_init(void)
{
return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
}
static void __exit xfrm4_tunnel_exit(void)
{
int err;
err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
BUG_ON(err);
}
module_init(xfrm4_tunnel_init);
module_exit(xfrm4_tunnel_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);
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