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_local_dontfrag(struct sk_buff *skb)
  32 {
  33         int proto;
  34         struct sock *sk = skb->sk;
  35
  36         if (sk) {
  37                 if (sk->sk_family != AF_INET6)
  38                         return 0;
  39
  40                 proto = sk->sk_protocol;
  41                 if (proto == IPPROTO_UDP || proto == IPPROTO_RAW)
  42                         return inet6_sk(sk)->dontfrag;
  43         }
  44
  45         return 0;
  46 }
  47
  48 static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
  49 {
  50         struct flowi6 fl6;
  51         struct sock *sk = skb->sk;
  52
  53         fl6.flowi6_oif = sk->sk_bound_dev_if;
  54         fl6.daddr = ipv6_hdr(skb)->daddr;
  55
  56         ipv6_local_rxpmtu(sk, &fl6, mtu);
  57 }
  58
  59 void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
  60 {
  61         struct flowi6 fl6;
  62         struct sock *sk = skb->sk;
  63
  64         fl6.fl6_dport = inet_sk(sk)->inet_dport;
  65         fl6.daddr = ipv6_hdr(skb)->daddr;
  66
  67         ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
  68 }
  69
  70 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  71 {
  72         int mtu, ret = 0;
  73         struct dst_entry *dst = skb_dst(skb);
  74
  75         mtu = dst_mtu(dst);
  76         if (mtu < IPV6_MIN_MTU)
  77                 mtu = IPV6_MIN_MTU;
  78
  79         if (!skb->local_df && skb->len > mtu) {
  80                 skb->dev = dst->dev;
  81
  82                 if (xfrm6_local_dontfrag(skb))
  83                         xfrm6_local_rxpmtu(skb, mtu);
  84                 else if (skb->sk)
  85                         xfrm_local_error(skb, mtu);
  86                 else
  87                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  88                 ret = -EMSGSIZE;
  89         }
  90
  91         return ret;
  92 }
  93
  94 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  95 {
  96         int err;
  97
  98         err = xfrm6_tunnel_check_size(skb);
  99         if (err)
 100                 return err;
 101
 102         XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
 103
 104         return xfrm6_extract_header(skb);
 105 }
 106
 107 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
 108 {
 109         int err;
 110
 111         err = xfrm_inner_extract_output(x, skb);
 112         if (err)
 113                 return err;
 114
 115         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 116 #ifdef CONFIG_NETFILTER
 117         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 118 #endif
 119
 120         skb->protocol = htons(ETH_P_IPV6);
 121         skb->local_df = 1;
 122
 123         return x->outer_mode->output2(x, skb);
 124 }
 125 EXPORT_SYMBOL(xfrm6_prepare_output);
 126
 127 int xfrm6_output_finish(struct sk_buff *skb)
 128 {
 129 #ifdef CONFIG_NETFILTER
 130         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 131 #endif
 132
 133         skb->protocol = htons(ETH_P_IPV6);
 134         return xfrm_output(skb);
 135 }
 136
 137 static int __xfrm6_output(struct sk_buff *skb)
 138 {
 139         struct dst_entry *dst = skb_dst(skb);
 140         struct xfrm_state *x = dst->xfrm;
 141         int mtu = xfrm_skb_dst_mtu(skb);
 142
 143         if (mtu < IPV6_MIN_MTU)
 144                 mtu = IPV6_MIN_MTU;
 145
 146         if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {
 147                 xfrm6_local_rxpmtu(skb, mtu);
 148                 return -EMSGSIZE;
 149         } else if (!skb->local_df && skb->len > mtu && skb->sk) {
 150                 xfrm_local_error(skb, mtu);
 151                 return -EMSGSIZE;
 152         }
 153
 154         if (x->props.mode == XFRM_MODE_TUNNEL &&
 155             ((skb->len > mtu && !skb_is_gso(skb)) ||
 156                 dst_allfrag(skb_dst(skb)))) {
 157                         return ip6_fragment(skb, x->outer_mode->afinfo->output_finish);
 158         }
 159         return x->outer_mode->afinfo->output_finish(skb);
 160 }
 161
 162 int xfrm6_output(struct sk_buff *skb)
 163 {
 164         return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
 165                        skb_dst(skb)->dev, __xfrm6_output);
 166 }