linux/net/ipv4/xfrm4_mode_beet.c
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   1/*
   2 * xfrm4_mode_beet.c - BEET mode encapsulation for IPv4.
   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/dst.h>
  17#include <net/ip.h>
  18#include <net/xfrm.h>
  19
  20static void xfrm4_beet_make_header(struct sk_buff *skb)
  21{
  22        struct iphdr *iph = ip_hdr(skb);
  23
  24        iph->ihl = 5;
  25        iph->version = 4;
  26
  27        iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
  28        iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
  29
  30        iph->id = XFRM_MODE_SKB_CB(skb)->id;
  31        iph->frag_off = XFRM_MODE_SKB_CB(skb)->frag_off;
  32        iph->ttl = XFRM_MODE_SKB_CB(skb)->ttl;
  33}
  34
  35/* Add encapsulation header.
  36 *
  37 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
  38 */
  39static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
  40{
  41        struct ip_beet_phdr *ph;
  42        struct iphdr *top_iph;
  43        int hdrlen, optlen;
  44
  45        hdrlen = 0;
  46        optlen = XFRM_MODE_SKB_CB(skb)->optlen;
  47        if (unlikely(optlen))
  48                hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
  49
  50        skb_set_network_header(skb, -x->props.header_len -
  51                                    hdrlen + (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
  52        if (x->sel.family != AF_INET6)
  53                skb->network_header += IPV4_BEET_PHMAXLEN;
  54        skb->mac_header = skb->network_header +
  55                          offsetof(struct iphdr, protocol);
  56        skb->transport_header = skb->network_header + sizeof(*top_iph);
  57
  58        xfrm4_beet_make_header(skb);
  59
  60        ph = (struct ip_beet_phdr *)
  61                __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
  62
  63        top_iph = ip_hdr(skb);
  64
  65        if (unlikely(optlen)) {
  66                BUG_ON(optlen < 0);
  67
  68                ph->padlen = 4 - (optlen & 4);
  69                ph->hdrlen = optlen / 8;
  70                ph->nexthdr = top_iph->protocol;
  71                if (ph->padlen)
  72                        memset(ph + 1, IPOPT_NOP, ph->padlen);
  73
  74                top_iph->protocol = IPPROTO_BEETPH;
  75                top_iph->ihl = sizeof(struct iphdr) / 4;
  76        }
  77
  78        top_iph->saddr = x->props.saddr.a4;
  79        top_iph->daddr = x->id.daddr.a4;
  80
  81        return 0;
  82}
  83
  84static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
  85{
  86        struct iphdr *iph;
  87        int optlen = 0;
  88        int err = -EINVAL;
  89
  90        if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
  91                struct ip_beet_phdr *ph;
  92                int phlen;
  93
  94                if (!pskb_may_pull(skb, sizeof(*ph)))
  95                        goto out;
  96
  97                ph = (struct ip_beet_phdr *)skb->data;
  98
  99                phlen = sizeof(*ph) + ph->padlen;
 100                optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
 101                if (optlen < 0 || optlen & 3 || optlen > 250)
 102                        goto out;
 103
 104                XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr;
 105
 106                if (!pskb_may_pull(skb, phlen))
 107                        goto out;
 108                __skb_pull(skb, phlen);
 109        }
 110
 111        skb_push(skb, sizeof(*iph));
 112        skb_reset_network_header(skb);
 113        skb_mac_header_rebuild(skb);
 114
 115        xfrm4_beet_make_header(skb);
 116
 117        iph = ip_hdr(skb);
 118
 119        iph->ihl += optlen / 4;
 120        iph->tot_len = htons(skb->len);
 121        iph->daddr = x->sel.daddr.a4;
 122        iph->saddr = x->sel.saddr.a4;
 123        iph->check = 0;
 124        iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
 125        err = 0;
 126out:
 127        return err;
 128}
 129
 130static struct xfrm_mode xfrm4_beet_mode = {
 131        .input2 = xfrm4_beet_input,
 132        .input = xfrm_prepare_input,
 133        .output2 = xfrm4_beet_output,
 134        .output = xfrm4_prepare_output,
 135        .owner = THIS_MODULE,
 136        .encap = XFRM_MODE_BEET,
 137        .flags = XFRM_MODE_FLAG_TUNNEL,
 138};
 139
 140static int __init xfrm4_beet_init(void)
 141{
 142        return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
 143}
 144
 145static void __exit xfrm4_beet_exit(void)
 146{
 147        int err;
 148
 149        err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
 150        BUG_ON(err);
 151}
 152
 153module_init(xfrm4_beet_init);
 154module_exit(xfrm4_beet_exit);
 155MODULE_LICENSE("GPL");
 156MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);
 157
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