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/compiler.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/icmpv6.h>
  16 #include <linux/netfilter_ipv6.h>
  17 #include <net/ipv6.h>
  18 #include <net/xfrm.h>
  19
  20 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  21 {
  22         int mtu, ret = 0;
  23         struct dst_entry *dst = skb->dst;
  24
  25         mtu = dst_mtu(dst);
  26         if (mtu < IPV6_MIN_MTU)
  27                 mtu = IPV6_MIN_MTU;
  28
  29         if (skb->len > mtu) {
  30                 skb->dev = dst->dev;
  31                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
  32                 ret = -EMSGSIZE;
  33         }
  34
  35         return ret;
  36 }
  37
  38 static int xfrm6_output_one(struct sk_buff *skb)
  39 {
  40         struct dst_entry *dst = skb->dst;
  41         struct xfrm_state *x = dst->xfrm;
  42         int err;
  43
  44         if (skb->ip_summed == CHECKSUM_HW) {
  45                 err = skb_checksum_help(skb, 0);
  46                 if (err)
  47                         goto error_nolock;
  48         }
  49
  50         if (x->props.mode) {
  51                 err = xfrm6_tunnel_check_size(skb);
  52                 if (err)
  53                         goto error_nolock;
  54         }
  55
  56         do {
  57                 spin_lock_bh(&x->lock);
  58                 err = xfrm_state_check(x, skb);
  59                 if (err)
  60                         goto error;
  61
  62                 err = x->mode->output(skb);
  63                 if (err)
  64                         goto error;
  65
  66                 err = x->type->output(x, skb);
  67                 if (err)
  68                         goto error;
  69
  70                 x->curlft.bytes += skb->len;
  71                 x->curlft.packets++;
  72
  73                 spin_unlock_bh(&x->lock);
  74
  75                 skb->nh.raw = skb->data;
  76
  77                 if (!(skb->dst = dst_pop(dst))) {
  78                         err = -EHOSTUNREACH;
  79                         goto error_nolock;
  80                 }
  81                 dst = skb->dst;
  82                 x = dst->xfrm;
  83         } while (x && !x->props.mode);
  84
  85         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
  86         err = 0;
  87
  88 out_exit:
  89         return err;
  90 error:
  91         spin_unlock_bh(&x->lock);
  92 error_nolock:
  93         kfree_skb(skb);
  94         goto out_exit;
  95 }
  96
  97 static int xfrm6_output_finish(struct sk_buff *skb)
  98 {
  99         int err;
 100
 101         while (likely((err = xfrm6_output_one(skb)) == 0)) {
 102                 nf_reset(skb);
 103
 104                 err = nf_hook(PF_INET6, NF_IP6_LOCAL_OUT, &skb, NULL,
 105                               skb->dst->dev, dst_output);
 106                 if (unlikely(err != 1))
 107                         break;
 108
 109                 if (!skb->dst->xfrm)
 110                         return dst_output(skb);
 111
 112                 err = nf_hook(PF_INET6, NF_IP6_POST_ROUTING, &skb, NULL,
 113                               skb->dst->dev, xfrm6_output_finish);
 114                 if (unlikely(err != 1))
 115                         break;
 116         }
 117
 118         return err;
 119 }
 120
 121 int xfrm6_output(struct sk_buff *skb)
 122 {
 123         return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL, skb->dst->dev,
 124                        xfrm6_output_finish);
 125 }