linux/net/ipv6/xfrm6_mode_beet.c
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   1/*
   2 * xfrm6_mode_beet.c - BEET mode encapsulation for IPv6.
   3 *
   4 * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com>
   5 *                    Miika Komu     <miika@iki.fi>
   6 *                    Herbert Xu     <herbert@gondor.apana.org.au>
   7 *                    Abhinav Pathak <abhinav.pathak@hiit.fi>
   8 *                    Jeff Ahrenholz <ahrenholz@gmail.com>
   9 */
  10
  11#include <linux/init.h>
  12#include <linux/kernel.h>
  13#include <linux/module.h>
  14#include <linux/skbuff.h>
  15#include <linux/stringify.h>
  16#include <net/dsfield.h>
  17#include <net/dst.h>
  18#include <net/inet_ecn.h>
  19#include <net/ipv6.h>
  20#include <net/xfrm.h>
  21
  22static void xfrm6_beet_make_header(struct sk_buff *skb)
  23{
  24        struct ipv6hdr *iph = ipv6_hdr(skb);
  25
  26        iph->version = 6;
  27
  28        memcpy(iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
  29               sizeof(iph->flow_lbl));
  30        iph->nexthdr = XFRM_MODE_SKB_CB(skb)->protocol;
  31
  32        ipv6_change_dsfield(iph, 0, XFRM_MODE_SKB_CB(skb)->tos);
  33        iph->hop_limit = XFRM_MODE_SKB_CB(skb)->ttl;
  34}
  35
  36/* Add encapsulation header.
  37 *
  38 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
  39 */
  40static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
  41{
  42        struct ipv6hdr *top_iph;
  43        struct ip_beet_phdr *ph;
  44        int optlen, hdr_len;
  45
  46        hdr_len = 0;
  47        optlen = XFRM_MODE_SKB_CB(skb)->optlen;
  48        if (unlikely(optlen))
  49                hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
  50
  51        skb_set_network_header(skb, -x->props.header_len - hdr_len);
  52        if (x->sel.family != AF_INET6)
  53                skb->network_header += IPV4_BEET_PHMAXLEN;
  54        skb->mac_header = skb->network_header +
  55                          offsetof(struct ipv6hdr, nexthdr);
  56        skb->transport_header = skb->network_header + sizeof(*top_iph);
  57        ph = (struct ip_beet_phdr *)__skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl-hdr_len);
  58
  59        xfrm6_beet_make_header(skb);
  60
  61        top_iph = ipv6_hdr(skb);
  62        if (unlikely(optlen)) {
  63
  64                BUG_ON(optlen < 0);
  65
  66                ph->padlen = 4 - (optlen & 4);
  67                ph->hdrlen = optlen / 8;
  68                ph->nexthdr = top_iph->nexthdr;
  69                if (ph->padlen)
  70                        memset(ph + 1, IPOPT_NOP, ph->padlen);
  71
  72                top_iph->nexthdr = IPPROTO_BEETPH;
  73        }
  74
  75        top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
  76        top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
  77        return 0;
  78}
  79
  80static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
  81{
  82        struct ipv6hdr *ip6h;
  83        int size = sizeof(struct ipv6hdr);
  84        int err;
  85
  86        err = skb_cow_head(skb, size + skb->mac_len);
  87        if (err)
  88                goto out;
  89
  90        __skb_push(skb, size);
  91        skb_reset_network_header(skb);
  92        skb_mac_header_rebuild(skb);
  93
  94        xfrm6_beet_make_header(skb);
  95
  96        ip6h = ipv6_hdr(skb);
  97        ip6h->payload_len = htons(skb->len - size);
  98        ip6h->daddr = *(struct in6_addr *)&x->sel.daddr.a6;
  99        ip6h->saddr = *(struct in6_addr *)&x->sel.saddr.a6;
 100        err = 0;
 101out:
 102        return err;
 103}
 104
 105static struct xfrm_mode xfrm6_beet_mode = {
 106        .input2 = xfrm6_beet_input,
 107        .input = xfrm_prepare_input,
 108        .output2 = xfrm6_beet_output,
 109        .output = xfrm6_prepare_output,
 110        .owner = THIS_MODULE,
 111        .encap = XFRM_MODE_BEET,
 112        .flags = XFRM_MODE_FLAG_TUNNEL,
 113};
 114
 115static int __init xfrm6_beet_init(void)
 116{
 117        return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
 118}
 119
 120static void __exit xfrm6_beet_exit(void)
 121{
 122        int err;
 123
 124        err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
 125        BUG_ON(err);
 126}
 127
 128module_init(xfrm6_beet_init);
 129module_exit(xfrm6_beet_exit);
 130MODULE_LICENSE("GPL");
 131MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);
 132
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