linux/net/ipv6/xfrm6_output.c
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   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}
  28
  29EXPORT_SYMBOL(xfrm6_find_1stfragopt);
  30
  31static 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
  46static 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        fl6.daddr = ipv6_hdr(skb)->daddr;
  53
  54        ipv6_local_rxpmtu(sk, &fl6, mtu);
  55}
  56
  57static 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        fl6.daddr = ipv6_hdr(skb)->daddr;
  64
  65        ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
  66}
  67
  68static 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
  92int 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
 105int 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}
 123EXPORT_SYMBOL(xfrm6_prepare_output);
 124
 125int 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
 135static 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->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
 157int 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}
 162
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