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