xfrm6_mode_beet.c

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/*
 * xfrm6_mode_beet.c - BEET mode encapsulation for IPv6.
 *
 * Copyright (c) 2006 Diego Beltrami <[email protected]>
 *                    Miika Komu     <[email protected]>
 *                    Herbert Xu     <[email protected]>
 *                    Abhinav Pathak <[email protected]>
 *                    Jeff Ahrenholz <[email protected]>
 */

#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 void xfrm6_beet_make_header(struct sk_buff *skb)
{
    struct ipv6hdr *iph = ipv6_hdr(skb);

    iph->version = 6;

    memcpy(iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
           sizeof(iph->flow_lbl));
    iph->nexthdr = XFRM_MODE_SKB_CB(skb)->protocol;

    ipv6_change_dsfield(iph, 0, XFRM_MODE_SKB_CB(skb)->tos);
    iph->hop_limit = XFRM_MODE_SKB_CB(skb)->ttl;
}

/* Add encapsulation header.
 *
 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
 */
static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
{
    struct ipv6hdr *top_iph;
    struct ip_beet_phdr *ph;
    int optlen, hdr_len;

    hdr_len = 0;
    optlen = XFRM_MODE_SKB_CB(skb)->optlen;
    if (unlikely(optlen))
        hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);

    skb_set_network_header(skb, -x->props.header_len - hdr_len);
    if (x->sel.family != AF_INET6)
        skb->network_header += IPV4_BEET_PHMAXLEN;
    skb->mac_header = skb->network_header +
              offsetof(struct ipv6hdr, nexthdr);
    skb->transport_header = skb->network_header + sizeof(*top_iph);
    ph = (struct ip_beet_phdr *)__skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl-hdr_len);

    xfrm6_beet_make_header(skb);

    top_iph = ipv6_hdr(skb);
    if (unlikely(optlen)) {

        BUG_ON(optlen < 0);

        ph->padlen = 4 - (optlen & 4);
        ph->hdrlen = optlen / 8;
        ph->nexthdr = top_iph->nexthdr;
        if (ph->padlen)
            memset(ph + 1, IPOPT_NOP, ph->padlen);

        top_iph->nexthdr = IPPROTO_BEETPH;
    }

    top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
    top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
    return 0;
}

static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
{
    struct ipv6hdr *ip6h;
    int size = sizeof(struct ipv6hdr);
    int err;

    err = skb_cow_head(skb, size + skb->mac_len);
    if (err)
        goto out;

    __skb_push(skb, size);
    skb_reset_network_header(skb);
    skb_mac_header_rebuild(skb);

    xfrm6_beet_make_header(skb);

    ip6h = ipv6_hdr(skb);
    ip6h->payload_len = htons(skb->len - size);
    ip6h->daddr = *(struct in6_addr *)&x->sel.daddr.a6;
    ip6h->saddr = *(struct in6_addr *)&x->sel.saddr.a6;
    err = 0;
out:
    return err;
}

static struct xfrm_mode xfrm6_beet_mode = {
    .input2 = xfrm6_beet_input,
    .input = xfrm_prepare_input,
    .output2 = xfrm6_beet_output,
    .output = xfrm6_prepare_output,
    .owner = THIS_MODULE,
    .encap = XFRM_MODE_BEET,
    .flags = XFRM_MODE_FLAG_TUNNEL,
};

static int __init xfrm6_beet_init(void)
{
    return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
}

static void __exit xfrm6_beet_exit(void)
{
    int err;

    err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
    BUG_ON(err);
}

module_init(xfrm6_beet_init);
module_exit(xfrm6_beet_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);