net/xfrm/xfrm_output.c

   1 /*
   2  * xfrm_output.c - Common IPsec encapsulation code.
   3  *
   4  * Copyright (c) 2007 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/errno.h>
  13 #include <linux/module.h>
  14 #include <linux/netdevice.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/spinlock.h>
  17 #include <net/dst.h>
  18 #include <net/xfrm.h>
  19
  20 static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
  21 {
  22         int nhead = x->props.header_len + LL_RESERVED_SPACE(skb->dst->dev)
  23                 - skb_headroom(skb);
  24
  25         if (nhead > 0)
  26                 return pskb_expand_head(skb, nhead, 0, GFP_ATOMIC);
  27
  28         /* Check tail too... */
  29         return 0;
  30 }
  31
  32 static int xfrm_state_check(struct xfrm_state *x, struct sk_buff *skb)
  33 {
  34         int err = xfrm_state_check_expire(x);
  35         if (err < 0)
  36                 goto err;
  37         err = xfrm_state_check_space(x, skb);
  38 err:
  39         return err;
  40 }
  41
  42 int xfrm_output(struct sk_buff *skb)
  43 {
  44         struct dst_entry *dst = skb->dst;
  45         struct xfrm_state *x = dst->xfrm;
  46         int err;
  47
  48         if (skb->ip_summed == CHECKSUM_PARTIAL) {
  49                 err = skb_checksum_help(skb);
  50                 if (err)
  51                         goto error_nolock;
  52         }
  53
  54         do {
  55                 spin_lock_bh(&x->lock);
  56                 err = xfrm_state_check(x, skb);
  57                 if (err)
  58                         goto error;
  59
  60                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
  61                         XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;
  62                         if (xfrm_aevent_is_on())
  63                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  64                 }
  65
  66                 err = x->outer_mode->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                 err = x->type->output(x, skb);
  76                 if (err)
  77                         goto error_nolock;
  78
  79                 if (!(skb->dst = dst_pop(dst))) {
  80                         err = -EHOSTUNREACH;
  81                         goto error_nolock;
  82                 }
  83                 dst = skb->dst;
  84                 x = dst->xfrm;
  85         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
  86
  87         err = 0;
  88
  89 error_nolock:
  90         return err;
  91 error:
  92         spin_unlock_bh(&x->lock);
  93         goto error_nolock;
  94 }
  95 EXPORT_SYMBOL_GPL(xfrm_output);