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/ip6_route.h>
  21 #include <net/xfrm.h>
  22
  23 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
  24                           u8 **prevhdr)
  25 {
  26         return ip6_find_1stfragopt(skb, prevhdr);
  27 }
  28
  29 EXPORT_SYMBOL(xfrm6_find_1stfragopt);
  30
  31 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  32 {
  33         int mtu, ret = 0;
  34         struct dst_entry *dst = skb_dst(skb);
  35
  36         mtu = dst_mtu(dst);
  37         if (mtu < IPV6_MIN_MTU)
  38                 mtu = IPV6_MIN_MTU;
  39
  40         if (!skb->local_df && skb->len > mtu) {
  41                 skb->dev = dst->dev;
  42                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  43                 ret = -EMSGSIZE;
  44         }
  45
  46         return ret;
  47 }
  48
  49 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  50 {
  51         int err;
  52
  53         err = xfrm6_tunnel_check_size(skb);
  54         if (err)
  55                 return err;
  56
  57         XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
  58
  59         return xfrm6_extract_header(skb);
  60 }
  61
  62 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
  63 {
  64         int err;
  65
  66         err = xfrm_inner_extract_output(x, skb);
  67         if (err)
  68                 return err;
  69
  70         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
  71 #ifdef CONFIG_NETFILTER
  72         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
  73 #endif
  74
  75         skb->protocol = htons(ETH_P_IPV6);
  76         skb->local_df = 1;
  77
  78         return x->outer_mode->output2(x, skb);
  79 }
  80 EXPORT_SYMBOL(xfrm6_prepare_output);
  81
  82 static int xfrm6_output_finish(struct sk_buff *skb)
  83 {
  84 #ifdef CONFIG_NETFILTER
  85         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
  86 #endif
  87
  88         skb->protocol = htons(ETH_P_IPV6);
  89         return xfrm_output(skb);
  90 }
  91
  92 static int __xfrm6_output(struct sk_buff *skb)
  93 {
  94         struct dst_entry *dst = skb_dst(skb);
  95         struct xfrm_state *x = dst->xfrm;
  96
  97         if ((x && x->props.mode == XFRM_MODE_TUNNEL) &&
  98             ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) ||
  99                 dst_allfrag(skb_dst(skb)))) {
 100                         return ip6_fragment(skb, xfrm6_output_finish);
 101         }
 102         return xfrm6_output_finish(skb);
 103 }
 104
 105 int xfrm6_output(struct sk_buff *skb)
 106 {
 107         return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
 108                        skb_dst(skb)->dev, __xfrm6_output);
 109 }