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         if (skb->ignore_df)
  77                 goto out;
  78
  79         mtu = dst_mtu(dst);
  80         if (mtu < IPV6_MIN_MTU)
  81                 mtu = IPV6_MIN_MTU;
  82
  83         if ((!skb_is_gso(skb) && skb->len > mtu) ||
  84             (skb_is_gso(skb) &&
  85              skb_gso_network_seglen(skb) > ip6_skb_dst_mtu(skb))) {
  86                 skb->dev = dst->dev;
  87                 skb->protocol = htons(ETH_P_IPV6);
  88
  89                 if (xfrm6_local_dontfrag(skb))
  90                         xfrm6_local_rxpmtu(skb, mtu);
  91                 else if (skb->sk)
  92                         xfrm_local_error(skb, mtu);
  93                 else
  94                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  95                 ret = -EMSGSIZE;
  96         }
  97 out:
  98         return ret;
  99 }
 100
 101 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 102 {
 103         int err;
 104
 105         err = xfrm6_tunnel_check_size(skb);
 106         if (err)
 107                 return err;
 108
 109         XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
 110
 111         return xfrm6_extract_header(skb);
 112 }
 113
 114 int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
 115 {
 116         int err;
 117
 118         err = xfrm_inner_extract_output(x, skb);
 119         if (err)
 120                 return err;
 121
 122         skb->ignore_df = 1;
 123         skb->protocol = htons(ETH_P_IPV6);
 124
 125         return x->outer_mode->output2(x, skb);
 126 }
 127 EXPORT_SYMBOL(xfrm6_prepare_output);
 128
 129 int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb)
 130 {
 131         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 132
 133 #ifdef CONFIG_NETFILTER
 134         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 135 #endif
 136
 137         return xfrm_output(sk, skb);
 138 }
 139
 140 static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 141 {
 142         struct xfrm_state *x = skb_dst(skb)->xfrm;
 143
 144         return x->outer_mode->afinfo->output_finish(sk, skb);
 145 }
 146
 147 static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 148 {
 149         struct dst_entry *dst = skb_dst(skb);
 150         struct xfrm_state *x = dst->xfrm;
 151         int mtu;
 152         bool toobig;
 153
 154 #ifdef CONFIG_NETFILTER
 155         if (!x) {
 156                 IP6CB(skb)->flags |= IP6SKB_REROUTED;
 157                 return dst_output(net, sk, skb);
 158         }
 159 #endif
 160
 161         if (x->props.mode != XFRM_MODE_TUNNEL)
 162                 goto skip_frag;
 163
 164         if (skb->protocol == htons(ETH_P_IPV6))
 165                 mtu = ip6_skb_dst_mtu(skb);
 166         else
 167                 mtu = dst_mtu(skb_dst(skb));
 168
 169         toobig = skb->len > mtu && !skb_is_gso(skb);
 170
 171         if (toobig && xfrm6_local_dontfrag(skb)) {
 172                 xfrm6_local_rxpmtu(skb, mtu);
 173                 return -EMSGSIZE;
 174         } else if (!skb->ignore_df && toobig && skb->sk) {
 175                 xfrm_local_error(skb, mtu);
 176                 return -EMSGSIZE;
 177         }
 178
 179         if (toobig || dst_allfrag(skb_dst(skb)))
 180                 return ip6_fragment(net, sk, skb,
 181                                     __xfrm6_output_finish);
 182
 183 skip_frag:
 184         return x->outer_mode->afinfo->output_finish(sk, skb);
 185 }
 186
 187 int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 188 {
 189         return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
 190                             net, sk, skb,  NULL, skb_dst(skb)->dev,
 191                             __xfrm6_output,
 192                             !(IP6CB(skb)->flags & IP6SKB_REROUTED));
 193 }