git.oblomov.eu Git - linux-2.6/blob - net/ipv4/xfrm4_output.c

   1 /*
   2  * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
   3  * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version
   8  * 2 of the License, or (at your option) any later version.
   9  */
  10
  11 #include <linux/compiler.h>
  12 #include <linux/if_ether.h>
  13 #include <linux/kernel.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/netfilter_ipv4.h>
  16 #include <net/ip.h>
  17 #include <net/xfrm.h>
  18 #include <net/icmp.h>
  19
  20 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
  21 {
  22         int mtu, ret = 0;
  23         struct dst_entry *dst;
  24
  25         if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
  26                 goto out;
  27
  28         IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
  29
  30         if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
  31                 goto out;
  32
  33         dst = skb->dst;
  34         mtu = dst_mtu(dst);
  35         if (skb->len > mtu) {
  36                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
  37                 ret = -EMSGSIZE;
  38         }
  39 out:
  40         return ret;
  41 }
  42
  43 static inline int xfrm4_output_one(struct sk_buff *skb)
  44 {
  45         struct dst_entry *dst = skb->dst;
  46         struct xfrm_state *x = dst->xfrm;
  47         int err;
  48
  49         if (x->props.mode == XFRM_MODE_TUNNEL) {
  50                 err = xfrm4_tunnel_check_size(skb);
  51                 if (err)
  52                         goto error_nolock;
  53         }
  54
  55         err = xfrm_output(skb);
  56         if (err)
  57                 goto error_nolock;
  58
  59         IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
  60         err = 0;
  61
  62 out_exit:
  63         return err;
  64 error_nolock:
  65         kfree_skb(skb);
  66         goto out_exit;
  67 }
  68
  69 static int xfrm4_output_finish2(struct sk_buff *skb)
  70 {
  71         int err;
  72
  73         while (likely((err = xfrm4_output_one(skb)) == 0)) {
  74                 nf_reset(skb);
  75
  76                 err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL,
  77                               skb->dst->dev, dst_output);
  78                 if (unlikely(err != 1))
  79                         break;
  80
  81                 if (!skb->dst->xfrm)
  82                         return dst_output(skb);
  83
  84                 err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL,
  85                               skb->dst->dev, xfrm4_output_finish2);
  86                 if (unlikely(err != 1))
  87                         break;
  88         }
  89
  90         return err;
  91 }
  92
  93 static int xfrm4_output_finish(struct sk_buff *skb)
  94 {
  95         struct sk_buff *segs;
  96
  97 #ifdef CONFIG_NETFILTER
  98         if (!skb->dst->xfrm) {
  99                 IPCB(skb)->flags |= IPSKB_REROUTED;
 100                 return dst_output(skb);
 101         }
 102 #endif
 103
 104         if (!skb_is_gso(skb))
 105                 return xfrm4_output_finish2(skb);
 106
 107         skb->protocol = htons(ETH_P_IP);
 108         segs = skb_gso_segment(skb, 0);
 109         kfree_skb(skb);
 110         if (unlikely(IS_ERR(segs)))
 111                 return PTR_ERR(segs);
 112
 113         do {
 114                 struct sk_buff *nskb = segs->next;
 115                 int err;
 116
 117                 segs->next = NULL;
 118                 err = xfrm4_output_finish2(segs);
 119
 120                 if (unlikely(err)) {
 121                         while ((segs = nskb)) {
 122                                 nskb = segs->next;
 123                                 segs->next = NULL;
 124                                 kfree_skb(segs);
 125                         }
 126                         return err;
 127                 }
 128
 129                 segs = nskb;
 130         } while (segs);
 131
 132         return 0;
 133 }
 134
 135 int xfrm4_output(struct sk_buff *skb)
 136 {
 137         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
 138                             xfrm4_output_finish,
 139                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 140 }