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                 proto = sk->sk_protocol;
  38
  39                 if (proto == IPPROTO_UDP || proto == IPPROTO_RAW)
  40                         return inet6_sk(sk)->dontfrag;
  41         }
  42
  43         return 0;
  44 }
  45
  46 static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
  47 {
  48         struct flowi6 fl6;
  49         struct sock *sk = skb->sk;
  50
  51         fl6.flowi6_oif = sk->sk_bound_dev_if;
  52         ipv6_addr_copy(&fl6.daddr, &ipv6_hdr(skb)->daddr);
  53
  54         ipv6_local_rxpmtu(sk, &fl6, mtu);
  55 }
  56
  57 static void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
  58 {
  59         struct flowi6 fl6;
  60         struct sock *sk = skb->sk;
  61
  62         fl6.fl6_dport = inet_sk(sk)->inet_dport;
  63         ipv6_addr_copy(&fl6.daddr, &ipv6_hdr(skb)->daddr);
  64
  65         ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
  66 }
  67
  68 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  69 {
  70         int mtu, ret = 0;
  71         struct dst_entry *dst = skb_dst(skb);
  72
  73         mtu = dst_mtu(dst);
  74         if (mtu < IPV6_MIN_MTU)
  75                 mtu = IPV6_MIN_MTU;
  76
  77         if (!skb->local_df && skb->len > mtu) {
  78                 skb->dev = dst->dev;
  79
  80                 if (xfrm6_local_dontfrag(skb))
  81                         xfrm6_local_rxpmtu(skb, mtu);
  82                 else if (skb->sk)
  83                         xfrm6_local_error(skb, mtu);
  84                 else
  85                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  86                 ret = -EMSGSIZE;
  87         }
  88
  89         return ret;
  90 }
  91
  92 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  93 {
  94         int err;
  95
  96         err = xfrm6_tunnel_check_size(skb);
  97         if (err)
  98                 return err;
  99
 100         XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
 101
 102         return xfrm6_extract_header(skb);
 103 }
 104
 105 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
 106 {
 107         int err;
 108
 109         err = xfrm_inner_extract_output(x, skb);
 110         if (err)
 111                 return err;
 112
 113         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 114 #ifdef CONFIG_NETFILTER
 115         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 116 #endif
 117
 118         skb->protocol = htons(ETH_P_IPV6);
 119         skb->local_df = 1;
 120
 121         return x->outer_mode->output2(x, skb);
 122 }
 123 EXPORT_SYMBOL(xfrm6_prepare_output);
 124
 125 int xfrm6_output_finish(struct sk_buff *skb)
 126 {
 127 #ifdef CONFIG_NETFILTER
 128         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 129 #endif
 130
 131         skb->protocol = htons(ETH_P_IPV6);
 132         return xfrm_output(skb);
 133 }
 134
 135 static int __xfrm6_output(struct sk_buff *skb)
 136 {
 137         struct dst_entry *dst = skb_dst(skb);
 138         struct xfrm_state *x = dst->xfrm;
 139         int mtu = ip6_skb_dst_mtu(skb);
 140
 141         if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {
 142                 xfrm6_local_rxpmtu(skb, mtu);
 143                 return -EMSGSIZE;
 144         } else if (!skb->local_df && skb->len > mtu && skb->sk) {
 145                 xfrm6_local_error(skb, mtu);
 146                 return -EMSGSIZE;
 147         }
 148
 149         if ((x && x->props.mode == XFRM_MODE_TUNNEL) &&
 150             ((skb->len > mtu && !skb_is_gso(skb)) ||
 151                 dst_allfrag(skb_dst(skb)))) {
 152                         return ip6_fragment(skb, x->outer_mode->afinfo->output_finish);
 153         }
 154         return x->outer_mode->afinfo->output_finish(skb);
 155 }
 156
 157 int xfrm6_output(struct sk_buff *skb)
 158 {
 159         return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
 160                        skb_dst(skb)->dev, __xfrm6_output);
 161 }