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         const struct ipv6hdr *hdr;
  63         struct sock *sk = skb->sk;
  64
  65         hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb);
  66         fl6.fl6_dport = inet_sk(sk)->inet_dport;
  67         fl6.daddr = hdr->daddr;
  68
  69         ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
  70 }
  71
  72 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  73 {
  74         int mtu, ret = 0;
  75         struct dst_entry *dst = skb_dst(skb);
  76
  77         mtu = dst_mtu(dst);
  78         if (mtu < IPV6_MIN_MTU)
  79                 mtu = IPV6_MIN_MTU;
  80
  81         if (!skb->ignore_df && skb->len > mtu) {
  82                 skb->dev = dst->dev;
  83
  84                 if (xfrm6_local_dontfrag(skb))
  85                         xfrm6_local_rxpmtu(skb, mtu);
  86                 else if (skb->sk)
  87                         xfrm_local_error(skb, mtu);
  88                 else
  89                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  90                 ret = -EMSGSIZE;
  91         }
  92
  93         return ret;
  94 }
  95
  96 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  97 {
  98         int err;
  99
 100         err = xfrm6_tunnel_check_size(skb);
 101         if (err)
 102                 return err;
 103
 104         XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
 105
 106         return xfrm6_extract_header(skb);
 107 }
 108
 109 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
 110 {
 111         int err;
 112
 113         err = xfrm_inner_extract_output(x, skb);
 114         if (err)
 115                 return err;
 116
 117         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 118 #ifdef CONFIG_NETFILTER
 119         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 120 #endif
 121
 122         skb->protocol = htons(ETH_P_IPV6);
 123         skb->ignore_df = 1;
 124
 125         return x->outer_mode->output2(x, skb);
 126 }
 127 EXPORT_SYMBOL(xfrm6_prepare_output);
 128
 129 int xfrm6_output_finish(struct sk_buff *skb)
 130 {
 131 #ifdef CONFIG_NETFILTER
 132         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 133 #endif
 134
 135         skb->protocol = htons(ETH_P_IPV6);
 136         return xfrm_output(skb);
 137 }
 138
 139 static int __xfrm6_output(struct sk_buff *skb)
 140 {
 141         struct dst_entry *dst = skb_dst(skb);
 142         struct xfrm_state *x = dst->xfrm;
 143         int mtu;
 144
 145         if (skb->protocol == htons(ETH_P_IPV6))
 146                 mtu = ip6_skb_dst_mtu(skb);
 147         else
 148                 mtu = dst_mtu(skb_dst(skb));
 149
 150         if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {
 151                 xfrm6_local_rxpmtu(skb, mtu);
 152                 return -EMSGSIZE;
 153         } else if (!skb->ignore_df && skb->len > mtu && skb->sk) {
 154                 xfrm_local_error(skb, mtu);
 155                 return -EMSGSIZE;
 156         }
 157
 158         if (x->props.mode == XFRM_MODE_TUNNEL &&
 159             ((skb->len > mtu && !skb_is_gso(skb)) ||
 160                 dst_allfrag(skb_dst(skb)))) {
 161                         return ip6_fragment(skb, x->outer_mode->afinfo->output_finish);
 162         }
 163         return x->outer_mode->afinfo->output_finish(skb);
 164 }
 165
 166 int xfrm6_output(struct sock *sk, struct sk_buff *skb)
 167 {
 168         return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
 169                        skb_dst(skb)->dev, __xfrm6_output);
 170 }