net/ipv6/xfrm6_output.c

   1 /*
   2  * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
   3  * Copyright (C) 2002 USAGI/WIDE Project
   4  * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/if_ether.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/icmpv6.h>
  17 #include <linux/netfilter_ipv6.h>
  18 #include <net/dst.h>
  19 #include <net/ipv6.h>
  20 #include <net/xfrm.h>
  21
  22 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
  23                           u8 **prevhdr)
  24 {
  25         return ip6_find_1stfragopt(skb, prevhdr);
  26 }
  27
  28 EXPORT_SYMBOL(xfrm6_find_1stfragopt);
  29
  30 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  31 {
  32         int mtu, ret = 0;
  33         struct dst_entry *dst = skb_dst(skb);
  34
  35         mtu = dst_mtu(dst);
  36         if (mtu < IPV6_MIN_MTU)
  37                 mtu = IPV6_MIN_MTU;
  38
  39         if (!skb->local_df && skb->len > mtu) {
  40                 skb->dev = dst->dev;
  41                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  42                 ret = -EMSGSIZE;
  43         }
  44
  45         return ret;
  46 }
  47
  48 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  49 {
  50         int err;
  51
  52         err = xfrm6_tunnel_check_size(skb);
  53         if (err)
  54                 return err;
  55
  56         XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
  57
  58         return xfrm6_extract_header(skb);
  59 }
  60
  61 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
  62 {
  63         int err;
  64
  65         err = xfrm_inner_extract_output(x, skb);
  66         if (err)
  67                 return err;
  68
  69         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
  70 #ifdef CONFIG_NETFILTER
  71         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
  72 #endif
  73
  74         skb->protocol = htons(ETH_P_IPV6);
  75         skb->local_df = 1;
  76
  77         return x->outer_mode->output2(x, skb);
  78 }
  79 EXPORT_SYMBOL(xfrm6_prepare_output);
  80
  81 static int xfrm6_output_finish(struct sk_buff *skb)
  82 {
  83 #ifdef CONFIG_NETFILTER
  84         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
  85 #endif
  86
  87         skb->protocol = htons(ETH_P_IPV6);
  88         return xfrm_output(skb);
  89 }
  90
  91 int xfrm6_output(struct sk_buff *skb)
  92 {
  93         return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
  94                        skb_dst(skb)->dev, xfrm6_output_finish);
  95 }