root/net/ipv6/xfrm6_mode_tunnel.c

DEFINITIONS

1. ipip6_ecn_decapsulate
2. xfrm6_mode_tunnel_output
3. xfrm6_mode_tunnel_input
4. xfrm6_mode_tunnel_init
5. xfrm6_mode_tunnel_exit

/*
 * 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);
}

/* Add encapsulation header.
 *
 * The top IP header will be constructed per RFC 2401.
 */
static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
{
        struct dst_entry *dst = skb->dst;
        struct ipv6hdr *top_iph;
        int dsfield;

        skb_set_network_header(skb, -x->props.header_len);
        skb->mac_header = skb->network_header +
                          offsetof(struct ipv6hdr, nexthdr);
        skb->transport_header = skb->network_header + sizeof(*top_iph);
        top_iph = ipv6_hdr(skb);

        top_iph->version = 6;

        memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
               sizeof(top_iph->flow_lbl));
        top_iph->nexthdr = xfrm_af2proto(skb->dst->ops->family);

        dsfield = XFRM_MODE_SKB_CB(skb)->tos;
        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);
        return 0;
}

static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
{
        int err = -EINVAL;
        const unsigned char *old_mac;

        if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
                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;

        if (x->props.flags & XFRM_STATE_DECAP_DSCP)
                ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
                               ipipv6_hdr(skb));
        if (!(x->props.flags & XFRM_STATE_NOECN))
                ipip6_ecn_decapsulate(skb);

        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 = {
        .input2 = xfrm6_mode_tunnel_input,
        .input = xfrm_prepare_input,
        .output2 = xfrm6_mode_tunnel_output,
        .output = xfrm6_prepare_output,
        .owner = THIS_MODULE,
        .encap = XFRM_MODE_TUNNEL,
        .flags = XFRM_MODE_FLAG_TUNNEL,
};

static int __init xfrm6_mode_tunnel_init(void)
{
        return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
}

static void __exit xfrm6_mode_tunnel_exit(void)
{
        int err;

        err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
        BUG_ON(err);
}

module_init(xfrm6_mode_tunnel_init);
module_exit(xfrm6_mode_tunnel_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);