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 EXPORT_SYMBOL(xfrm6_find_1stfragopt);
  29
  30 static int xfrm6_local_dontfrag(struct sk_buff *skb)
  31 {
  32         int proto;
  33         struct sock *sk = skb->sk;
  34
  35         if (sk) {
  36                 if (sk->sk_family != AF_INET6)
  37                         return 0;
  38
  39                 proto = sk->sk_protocol;
  40                 if (proto == IPPROTO_UDP || proto == IPPROTO_RAW)
  41                         return inet6_sk(sk)->dontfrag;
  42         }
  43
  44         return 0;
  45 }
  46
  47 static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
  48 {
  49         struct flowi6 fl6;
  50         struct sock *sk = skb->sk;
  51
  52         fl6.flowi6_oif = sk->sk_bound_dev_if;
  53         fl6.daddr = ipv6_hdr(skb)->daddr;
  54
  55         ipv6_local_rxpmtu(sk, &fl6, mtu);
  56 }
  57
  58 void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
  59 {
  60         struct flowi6 fl6;
  61         const struct ipv6hdr *hdr;
  62         struct sock *sk = skb->sk;
  63
  64         hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb);
  65         fl6.fl6_dport = inet_sk(sk)->inet_dport;
  66         fl6.daddr = hdr->daddr;
  67
  68         ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
  69 }
  70
  71 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  72 {
  73         int mtu, ret = 0;
  74         struct dst_entry *dst = skb_dst(skb);
  75
  76         mtu = dst_mtu(dst);
  77         if (mtu < IPV6_MIN_MTU)
  78                 mtu = IPV6_MIN_MTU;
  79
  80         if (!skb->ignore_df && skb->len > mtu) {
  81                 skb->dev = dst->dev;
  82
  83                 if (xfrm6_local_dontfrag(skb))
  84                         xfrm6_local_rxpmtu(skb, mtu);
  85                 else if (skb->sk)
  86                         xfrm_local_error(skb, mtu);
  87                 else
  88                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  89                 ret = -EMSGSIZE;
  90         }
  91
  92         return ret;
  93 }
  94
  95 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  96 {
  97         int err;
  98
  99         err = xfrm6_tunnel_check_size(skb);
 100         if (err)
 101                 return err;
 102
 103         XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
 104
 105         return xfrm6_extract_header(skb);
 106 }
 107
 108 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
 109 {
 110         int err;
 111
 112         err = xfrm_inner_extract_output(x, skb);
 113         if (err)
 114                 return err;
 115
 116         skb->ignore_df = 1;
 117         skb->protocol = htons(ETH_P_IPV6);
 118
 119         return x->outer_mode->output2(x, skb);
 120 }
 121 EXPORT_SYMBOL(xfrm6_prepare_output);
 122
 123 int xfrm6_output_finish(struct sk_buff *skb)
 124 {
 125         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 126
 127 #ifdef CONFIG_NETFILTER
 128         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 129 #endif
 130
 131         return xfrm_output(skb);
 132 }
 133
 134 static int __xfrm6_output(struct sk_buff *skb)
 135 {
 136         struct dst_entry *dst = skb_dst(skb);
 137         struct xfrm_state *x = dst->xfrm;
 138         int mtu;
 139
 140 #ifdef CONFIG_NETFILTER
 141         if (!x) {
 142                 IP6CB(skb)->flags |= IP6SKB_REROUTED;
 143                 return dst_output(skb);
 144         }
 145 #endif
 146
 147         if (skb->protocol == htons(ETH_P_IPV6))
 148                 mtu = ip6_skb_dst_mtu(skb);
 149         else
 150                 mtu = dst_mtu(skb_dst(skb));
 151
 152         if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {
 153                 xfrm6_local_rxpmtu(skb, mtu);
 154                 return -EMSGSIZE;
 155         } else if (!skb->ignore_df && skb->len > mtu && skb->sk) {
 156                 xfrm_local_error(skb, mtu);
 157                 return -EMSGSIZE;
 158         }
 159
 160         if (x->props.mode == XFRM_MODE_TUNNEL &&
 161             ((skb->len > mtu && !skb_is_gso(skb)) ||
 162                 dst_allfrag(skb_dst(skb)))) {
 163                         return ip6_fragment(skb, x->outer_mode->afinfo->output_finish);
 164         }
 165         return x->outer_mode->afinfo->output_finish(skb);
 166 }
 167
 168 int xfrm6_output(struct sock *sk, struct sk_buff *skb)
 169 {
 170         return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb,
 171                             NULL, skb_dst(skb)->dev, __xfrm6_output,
 172                             !(IP6CB(skb)->flags & IP6SKB_REROUTED));
 173 }