net/ipv4/xfrm4_mode_beet.c

   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
  20 /* Add encapsulation header.
  21  *
  22  * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
  23  */
  24 static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
  25 {
  26         struct ip_beet_phdr *ph;
  27         struct iphdr *iph, *top_iph;
  28         int hdrlen, optlen;
  29
  30         iph = ip_hdr(skb);
  31
  32         hdrlen = 0;
  33         optlen = iph->ihl * 4 - sizeof(*iph);
  34         if (unlikely(optlen))
  35                 hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
  36
  37         skb_set_network_header(skb, IPV4_BEET_PHMAXLEN - x->props.header_len -
  38                                     hdrlen);
  39         skb->mac_header = skb->network_header +
  40                           offsetof(struct iphdr, protocol);
  41         skb->transport_header = skb->network_header + sizeof(*iph);
  42
  43         ph = (struct ip_beet_phdr *)__skb_pull(skb, sizeof(*iph) - hdrlen);
  44
  45         top_iph = ip_hdr(skb);
  46         memmove(top_iph, iph, sizeof(*iph));
  47         if (unlikely(optlen)) {
  48                 BUG_ON(optlen < 0);
  49
  50                 ph->padlen = 4 - (optlen & 4);
  51                 ph->hdrlen = optlen / 8;
  52                 ph->nexthdr = top_iph->protocol;
  53                 if (ph->padlen)
  54                         memset(ph + 1, IPOPT_NOP, ph->padlen);
  55
  56                 top_iph->protocol = IPPROTO_BEETPH;
  57                 top_iph->ihl = sizeof(struct iphdr) / 4;
  58         }
  59
  60         top_iph->saddr = x->props.saddr.a4;
  61         top_iph->daddr = x->id.daddr.a4;
  62
  63         return 0;
  64 }
  65
  66 static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
  67 {
  68         struct iphdr *iph = ip_hdr(skb);
  69         int phlen = 0;
  70         int optlen = 0;
  71         u8 ph_nexthdr = 0;
  72         int err = -EINVAL;
  73
  74         if (unlikely(iph->protocol == IPPROTO_BEETPH)) {
  75                 struct ip_beet_phdr *ph;
  76
  77                 if (!pskb_may_pull(skb, sizeof(*ph)))
  78                         goto out;
  79                 ph = (struct ip_beet_phdr *)(ipip_hdr(skb) + 1);
  80
  81                 phlen = sizeof(*ph) + ph->padlen;
  82                 optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
  83                 if (optlen < 0 || optlen & 3 || optlen > 250)
  84                         goto out;
  85
  86                 if (!pskb_may_pull(skb, phlen + optlen))
  87                         goto out;
  88                 skb->len -= phlen + optlen;
  89
  90                 ph_nexthdr = ph->nexthdr;
  91         }
  92
  93         skb_set_network_header(skb, phlen - sizeof(*iph));
  94         memmove(skb_network_header(skb), iph, sizeof(*iph));
  95         skb_set_transport_header(skb, phlen + optlen);
  96         skb->data = skb_transport_header(skb);
  97
  98         iph = ip_hdr(skb);
  99         iph->ihl = (sizeof(*iph) + optlen) / 4;
 100         iph->tot_len = htons(skb->len + iph->ihl * 4);
 101         iph->daddr = x->sel.daddr.a4;
 102         iph->saddr = x->sel.saddr.a4;
 103         if (ph_nexthdr)
 104                 iph->protocol = ph_nexthdr;
 105         iph->check = 0;
 106         iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
 107         err = 0;
 108 out:
 109         return err;
 110 }
 111
 112 static struct xfrm_mode xfrm4_beet_mode = {
 113         .input = xfrm4_beet_input,
 114         .output = xfrm4_beet_output,
 115         .owner = THIS_MODULE,
 116         .encap = XFRM_MODE_BEET,
 117 };
 118
 119 static int __init xfrm4_beet_init(void)
 120 {
 121         return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
 122 }
 123
 124 static void __exit xfrm4_beet_exit(void)
 125 {
 126         int err;
 127
 128         err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
 129         BUG_ON(err);
 130 }
 131
 132 module_init(xfrm4_beet_init);
 133 module_exit(xfrm4_beet_exit);
 134 MODULE_LICENSE("GPL");
 135 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);