LXR linux/net/ipv6/xfrm6

   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
  23int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
  24                          u8 **prevhdr)
  25{
  26        return ip6_find_1stfragopt(skb, prevhdr);
  27}
  28EXPORT_SYMBOL(xfrm6_find_1stfragopt);
  29
  30static 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
  47static 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
  58void 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
  71static 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
  95int 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
 108int 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}
 121EXPORT_SYMBOL(xfrm6_prepare_output);
 122
 123int xfrm6_output_finish(struct sock *sk, 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(sk, skb);
 132}
 133
 134static int __xfrm6_output(struct sock *sk, 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_sk(sk, 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(sk, skb,
 164                                    x->outer_mode->afinfo->output_finish);
 165        }
 166        return x->outer_mode->afinfo->output_finish(sk, skb);
 167}
 168
 169int xfrm6_output(struct sock *sk, struct sk_buff *skb)
 170{
 171        return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, sk, skb,
 172                            NULL, skb_dst(skb)->dev, __xfrm6_output,
 173                            !(IP6CB(skb)->flags & IP6SKB_REROUTED));
 174}
 175