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/*
* xfrm6_mode_tunnel.c - Tunnel mode encapsulation for IPv6.
*
* Copyright (C) 2002 USAGI/WIDE Project
* 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/dsfield.h>
#include <net/dst.h>
#include <net/inet_ecn.h>
#include <net/ipv6.h>
#include <net/xfrm.h>
static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
{
struct ipv6hdr *outer_iph = ipv6_hdr(skb);
struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
IP6_ECN_set_ce(inner_iph);
}
static inline void ip6ip_ecn_decapsulate(struct sk_buff *skb)
{
if (INET_ECN_is_ce(ipv6_get_dsfield(ipv6_hdr(skb))))
IP_ECN_set_ce(ipip_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:
* payload_len
*
* On exit, skb->h will be set to the start of the encapsulation header to be
* filled in by x->type->output and the mac header will be set to the
* nextheader field of the extension header directly preceding the
* encapsulation header, or in its absence, that of the top IP header.
* The value of the network header will always point to the top IP header
* while skb->data will point to the payload.
*/
static int xfrm6_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 ipv6hdr *iph, *top_iph;
int dsfield;
iph = ipv6_hdr(skb);
skb_set_mac_header(skb, offsetof(struct ipv6hdr, nexthdr) -
x->props.header_len);
skb_set_network_header(skb, -x->props.header_len);
skb_set_transport_header(skb, sizeof(struct ipv6hdr) -
x->props.header_len);
top_iph = ipv6_hdr(skb);
top_iph->version = 6;
if (xdst->route->ops->family == AF_INET6) {
top_iph->priority = iph->priority;
top_iph->flow_lbl[0] = iph->flow_lbl[0];
top_iph->flow_lbl[1] = iph->flow_lbl[1];
top_iph->flow_lbl[2] = iph->flow_lbl[2];
top_iph->nexthdr = IPPROTO_IPV6;
} else {
top_iph->priority = 0;
top_iph->flow_lbl[0] = 0;
top_iph->flow_lbl[1] = 0;
top_iph->flow_lbl[2] = 0;
top_iph->nexthdr = IPPROTO_IPIP;
}
dsfield = ipv6_get_dsfield(top_iph);
dsfield = INET_ECN_encapsulate(dsfield, dsfield);
if (x->props.flags & XFRM_STATE_NOECN)
dsfield &= ~INET_ECN_MASK;
ipv6_change_dsfield(top_iph, 0, dsfield);
top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
skb->protocol = htons(ETH_P_IPV6);
return 0;
}
static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
{
int err = -EINVAL;
const unsigned char *old_mac;
const unsigned char *nh = skb_network_header(skb);
if (nh[IP6CB(skb)->nhoff] != IPPROTO_IPV6 &&
nh[IP6CB(skb)->nhoff] != IPPROTO_IPIP)
goto out;
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
goto out;
if (skb_cloned(skb) &&
(err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
goto out;
nh = skb_network_header(skb);
if (nh[IP6CB(skb)->nhoff] == IPPROTO_IPV6) {
if (x->props.flags & XFRM_STATE_DECAP_DSCP)
ipv6_copy_dscp(ipv6_hdr(skb), ipipv6_hdr(skb));
if (!(x->props.flags & XFRM_STATE_NOECN))
ipip6_ecn_decapsulate(skb);
} else {
if (!(x->props.flags & XFRM_STATE_NOECN))
ip6ip_ecn_decapsulate(skb);
skb->protocol = htons(ETH_P_IP);
}
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 xfrm6_tunnel_mode = {
.input = xfrm6_tunnel_input,
.output = xfrm6_tunnel_output,
.owner = THIS_MODULE,
.encap = XFRM_MODE_TUNNEL,
};
static int __init xfrm6_tunnel_init(void)
{
return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
}
static void __exit xfrm6_tunnel_exit(void)
{
int err;
err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
BUG_ON(err);
}
module_init(xfrm6_tunnel_init);
module_exit(xfrm6_tunnel_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);
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