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/spinlock.h>
  16 #include <linux/netfilter_ipv4.h>
  17 #include <net/ip.h>
  18 #include <net/xfrm.h>
  19 #include <net/icmp.h>
  20
  21 extern int skb_checksum_setup(struct sk_buff *skb);
  22
  23 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
  24 {
  25         int mtu, ret = 0;
  26         struct dst_entry *dst;
  27         struct iphdr *iph = skb->nh.iph;
  28
  29         if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
  30                 goto out;
  31
  32         IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
  33
  34         if (!(iph->frag_off & htons(IP_DF)) || skb->local_df)
  35                 goto out;
  36
  37         dst = skb->dst;
  38         mtu = dst_mtu(dst);
  39         if (skb->len > mtu) {
  40                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
  41                 ret = -EMSGSIZE;
  42         }
  43 out:
  44         return ret;
  45 }
  46
  47 static int xfrm4_output_one(struct sk_buff *skb)
  48 {
  49         struct dst_entry *dst = skb->dst;
  50         struct xfrm_state *x = dst->xfrm;
  51         int err;
  52
  53         err = skb_checksum_setup(skb);
  54         if (err)
  55                 goto error_nolock;
  56
  57         if (skb->ip_summed == CHECKSUM_HW) {
  58                 err = skb_checksum_help(skb, 0);
  59                 if (err)
  60                         goto error_nolock;
  61         }
  62
  63         if (x->props.mode) {
  64                 err = xfrm4_tunnel_check_size(skb);
  65                 if (err)
  66                         goto error_nolock;
  67         }
  68
  69         do {
  70                 spin_lock_bh(&x->lock);
  71                 err = xfrm_state_check(x, skb);
  72                 if (err)
  73                         goto error;
  74
  75                 err = x->mode->output(skb);
  76                 if (err)
  77                         goto error;
  78
  79                 err = x->type->output(x, skb);
  80                 if (err)
  81                         goto error;
  82
  83                 x->curlft.bytes += skb->len;
  84                 x->curlft.packets++;
  85
  86                 spin_unlock_bh(&x->lock);
  87
  88                 if (!(skb->dst = dst_pop(dst))) {
  89                         err = -EHOSTUNREACH;
  90                         goto error_nolock;
  91                 }
  92                 dst = skb->dst;
  93                 x = dst->xfrm;
  94         } while (x && !x->props.mode);
  95
  96         IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
  97         err = 0;
  98
  99 out_exit:
 100         return err;
 101 error:
 102         spin_unlock_bh(&x->lock);
 103 error_nolock:
 104         kfree_skb(skb);
 105         goto out_exit;
 106 }
 107
 108 static int xfrm4_output_finish2(struct sk_buff *skb)
 109 {
 110         int err;
 111
 112         while (likely((err = xfrm4_output_one(skb)) == 0)) {
 113                 nf_reset(skb);
 114
 115                 err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL,
 116                               skb->dst->dev, dst_output);
 117                 if (unlikely(err != 1))
 118                         break;
 119
 120                 if (!skb->dst->xfrm)
 121                         return dst_output(skb);
 122
 123                 err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL,
 124                               skb->dst->dev, xfrm4_output_finish2);
 125                 if (unlikely(err != 1))
 126                         break;
 127         }
 128
 129         return err;
 130 }
 131
 132 static int xfrm4_output_finish(struct sk_buff *skb)
 133 {
 134         struct sk_buff *segs;
 135
 136 #ifdef CONFIG_NETFILTER
 137         if (!skb->dst->xfrm) {
 138                 IPCB(skb)->flags |= IPSKB_REROUTED;
 139                 return dst_output(skb);
 140         }
 141 #endif
 142
 143         if (!skb_is_gso(skb))
 144                 return xfrm4_output_finish2(skb);
 145
 146         skb->protocol = htons(ETH_P_IP);
 147         segs = skb_gso_segment(skb, 0);
 148         kfree_skb(skb);
 149         if (unlikely(IS_ERR(segs)))
 150                 return PTR_ERR(segs);
 151
 152         do {
 153                 struct sk_buff *nskb = segs->next;
 154                 int err;
 155
 156                 segs->next = NULL;
 157                 err = xfrm4_output_finish2(segs);
 158
 159                 if (unlikely(err)) {
 160                         while ((segs = nskb)) {
 161                                 nskb = segs->next;
 162                                 segs->next = NULL;
 163                                 kfree_skb(segs);
 164                         }
 165                         return err;
 166                 }
 167
 168                 segs = nskb;
 169         } while (segs);
 170
 171         return 0;
 172 }
 173
 174 int xfrm4_output(struct sk_buff *skb)
 175 {
 176         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
 177                             xfrm4_output_finish,
 178                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 179 }