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/*
* 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>
/* Add encapsulation header.
*
* The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
* 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_beet_output(struct xfrm_state *x, struct sk_buff *skb)
{
struct iphdr *iph, *top_iph = NULL;
int hdrlen, optlen;
iph = skb->nh.iph;
skb->h.ipiph = iph;
hdrlen = 0;
optlen = iph->ihl * 4 - sizeof(*iph);
if (unlikely(optlen))
hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
skb->nh.raw = skb_push(skb, x->props.header_len + hdrlen);
top_iph = skb->nh.iph;
skb->h.raw += sizeof(*iph) - hdrlen;
memmove(top_iph, iph, sizeof(*iph));
if (unlikely(optlen)) {
struct ip_beet_phdr *ph;
BUG_ON(optlen < 0);
ph = (struct ip_beet_phdr *)skb->h.raw;
ph->padlen = 4 - (optlen & 4);
ph->hdrlen = (optlen + ph->padlen + sizeof(*ph)) / 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 = skb->nh.iph;
int phlen = 0;
int optlen = 0;
__u8 ph_nexthdr = 0, protocol = 0;
int err = -EINVAL;
protocol = iph->protocol;
if (unlikely(iph->protocol == IPPROTO_BEETPH)) {
struct ip_beet_phdr *ph;
if (!pskb_may_pull(skb, sizeof(*ph)))
goto out;
ph = (struct ip_beet_phdr *)(skb->h.ipiph + 1);
phlen = sizeof(*ph) + ph->padlen;
optlen = ph->hdrlen * 8 - phlen;
if (optlen < 0 || optlen & 3 || optlen > 250)
goto out;
if (!pskb_may_pull(skb, phlen + optlen))
goto out;
skb->len -= phlen + optlen;
ph_nexthdr = ph->nexthdr;
}
skb->nh.raw = skb->data + (phlen - sizeof(*iph));
memmove(skb->nh.raw, iph, sizeof(*iph));
skb->h.raw = skb->data + (phlen + optlen);
skb->data = skb->h.raw;
iph = skb->nh.iph;
iph->ihl = (sizeof(*iph) + optlen) / 4;
iph->tot_len = htons(skb->len + iph->ihl * 4);
iph->daddr = x->sel.daddr.a4;
iph->saddr = x->sel.saddr.a4;
if (ph_nexthdr)
iph->protocol = ph_nexthdr;
else
iph->protocol = protocol;
iph->check = 0;
iph->check = ip_fast_csum(skb->nh.raw, iph->ihl);
err = 0;
out:
return err;
}
static struct xfrm_mode xfrm4_beet_mode = {
.input = xfrm4_beet_input,
.output = xfrm4_beet_output,
.owner = THIS_MODULE,
.encap = XFRM_MODE_BEET,
};
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);
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