root/net/ipv4/xfrm4_mode_beet.c

DEFINITIONS

1. xfrm4_beet_make_header
2. xfrm4_beet_output
3. xfrm4_beet_input
4. xfrm4_beet_init
5. xfrm4_beet_exit

/*
 * xfrm4_mode_beet.c - BEET mode encapsulation for IPv4.
 *
 * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com>
 *                    Miika Komu     <miika@iki.fi>
 *                    Herbert Xu     <herbert@gondor.apana.org.au>
 *                    Abhinav Pathak <abhinav.pathak@hiit.fi>
 *                    Jeff Ahrenholz <ahrenholz@gmail.com>
 */

#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/ip.h>
#include <net/xfrm.h>

static void xfrm4_beet_make_header(struct sk_buff *skb)
{
        struct iphdr *iph = ip_hdr(skb);

        iph->ihl = 5;
        iph->version = 4;

        iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
        iph->tos = XFRM_MODE_SKB_CB(skb)->tos;

        iph->id = XFRM_MODE_SKB_CB(skb)->id;
        iph->frag_off = XFRM_MODE_SKB_CB(skb)->frag_off;
        iph->ttl = 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 xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
{
        struct ip_beet_phdr *ph;
        struct iphdr *top_iph;
        int hdrlen, optlen;

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

        skb_set_network_header(skb, -x->props.header_len -
                                    hdrlen + (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
        if (x->sel.family != AF_INET6)
                skb->network_header += IPV4_BEET_PHMAXLEN;
        skb->mac_header = skb->network_header +
                          offsetof(struct iphdr, protocol);
        skb->transport_header = skb->network_header + sizeof(*top_iph);

        xfrm4_beet_make_header(skb);

        ph = (struct ip_beet_phdr *)
                __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);

        top_iph = ip_hdr(skb);

        if (unlikely(optlen)) {
                BUG_ON(optlen < 0);

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

                top_iph->protocol = IPPROTO_BEETPH;
                top_iph->ihl = sizeof(struct iphdr) / 4;
        }

        top_iph->saddr = x->props.saddr.a4;
        top_iph->daddr = x->id.daddr.a4;

        return 0;
}

static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
{
        struct iphdr *iph;
        int optlen = 0;
        int err = -EINVAL;

        if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
                struct ip_beet_phdr *ph;
                int phlen;

                if (!pskb_may_pull(skb, sizeof(*ph)))
                        goto out;

                ph = (struct ip_beet_phdr *)skb->data;

                phlen = sizeof(*ph) + ph->padlen;
                optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
                if (optlen < 0 || optlen & 3 || optlen > 250)
                        goto out;

                XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr;

                if (!pskb_may_pull(skb, phlen))
                        goto out;
                __skb_pull(skb, phlen);
        }

        skb_push(skb, sizeof(*iph));
        skb_reset_network_header(skb);

        memmove(skb->data - skb->mac_len, skb_mac_header(skb),
                skb->mac_len);
        skb_set_mac_header(skb, -skb->mac_len);

        xfrm4_beet_make_header(skb);

        iph = ip_hdr(skb);

        iph->ihl += optlen / 4;
        iph->tot_len = htons(skb->len);
        iph->daddr = x->sel.daddr.a4;
        iph->saddr = x->sel.saddr.a4;
        iph->check = 0;
        iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
        err = 0;
out:
        return err;
}

static struct xfrm_mode xfrm4_beet_mode = {
        .input2 = xfrm4_beet_input,
        .input = xfrm_prepare_input,
        .output2 = xfrm4_beet_output,
        .output = xfrm4_prepare_output,
        .owner = THIS_MODULE,
        .encap = XFRM_MODE_BEET,
        .flags = XFRM_MODE_FLAG_TUNNEL,
};

static int __init xfrm4_beet_init(void)
{
        return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
}

static void __exit xfrm4_beet_exit(void)
{
        int err;

        err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
        BUG_ON(err);
}

module_init(xfrm4_beet_init);
module_exit(xfrm4_beet_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);