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/netfilter.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/spinlock.h>
  18 #include <net/dst.h>
  19 #include <net/xfrm.h>
  20
  21 static int xfrm_output2(struct sk_buff *skb);
  22
  23 static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
  24 {
  25         struct dst_entry *dst = skb->dst;
  26         int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
  27                 - skb_headroom(skb);
  28
  29         if (nhead > 0)
  30                 return pskb_expand_head(skb, nhead, 0, GFP_ATOMIC);
  31
  32         /* Check tail too... */
  33         return 0;
  34 }
  35
  36 static int xfrm_output_one(struct sk_buff *skb, int err)
  37 {
  38         struct dst_entry *dst = skb->dst;
  39         struct xfrm_state *x = dst->xfrm;
  40
  41         if (err <= 0)
  42                 goto resume;
  43
  44         do {
  45                 err = xfrm_state_check_space(x, skb);
  46                 if (err)
  47                         goto error_nolock;
  48
  49                 err = x->outer_mode->output(x, skb);
  50                 if (err)
  51                         goto error_nolock;
  52
  53                 spin_lock_bh(&x->lock);
  54                 err = xfrm_state_check_expire(x);
  55                 if (err)
  56                         goto error;
  57
  58                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
  59                         XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;
  60                         if (xfrm_aevent_is_on())
  61                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  62                 }
  63
  64                 x->curlft.bytes += skb->len;
  65                 x->curlft.packets++;
  66
  67                 spin_unlock_bh(&x->lock);
  68
  69                 err = x->type->output(x, skb);
  70
  71 resume:
  72                 if (err)
  73                         goto error_nolock;
  74
  75                 if (!(skb->dst = dst_pop(dst))) {
  76                         err = -EHOSTUNREACH;
  77                         goto error_nolock;
  78                 }
  79                 dst = skb->dst;
  80                 x = dst->xfrm;
  81         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
  82
  83         err = 0;
  84
  85 out_exit:
  86         return err;
  87 error:
  88         spin_unlock_bh(&x->lock);
  89 error_nolock:
  90         kfree_skb(skb);
  91         goto out_exit;
  92 }
  93
  94 int xfrm_output_resume(struct sk_buff *skb, int err)
  95 {
  96         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
  97                 struct xfrm_state *x;
  98
  99                 nf_reset(skb);
 100
 101                 err = skb->dst->ops->local_out(skb);
 102                 if (unlikely(err != 1))
 103                         goto out;
 104
 105                 x = skb->dst->xfrm;
 106                 if (!x)
 107                         return dst_output(skb);
 108
 109                 err = nf_hook(x->inner_mode->afinfo->family,
 110                               NF_INET_POST_ROUTING, skb,
 111                               NULL, skb->dst->dev, xfrm_output2);
 112                 if (unlikely(err != 1))
 113                         goto out;
 114         }
 115
 116         if (err == -EINPROGRESS)
 117                 err = 0;
 118
 119 out:
 120         return err;
 121 }
 122 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 123
 124 static int xfrm_output2(struct sk_buff *skb)
 125 {
 126         return xfrm_output_resume(skb, 1);
 127 }
 128
 129 static int xfrm_output_gso(struct sk_buff *skb)
 130 {
 131         struct sk_buff *segs;
 132
 133         segs = skb_gso_segment(skb, 0);
 134         kfree_skb(skb);
 135         if (unlikely(IS_ERR(segs)))
 136                 return PTR_ERR(segs);
 137
 138         do {
 139                 struct sk_buff *nskb = segs->next;
 140                 int err;
 141
 142                 segs->next = NULL;
 143                 err = xfrm_output2(segs);
 144
 145                 if (unlikely(err)) {
 146                         while ((segs = nskb)) {
 147                                 nskb = segs->next;
 148                                 segs->next = NULL;
 149                                 kfree_skb(segs);
 150                         }
 151                         return err;
 152                 }
 153
 154                 segs = nskb;
 155         } while (segs);
 156
 157         return 0;
 158 }
 159
 160 int xfrm_output(struct sk_buff *skb)
 161 {
 162         int err;
 163
 164         if (skb_is_gso(skb))
 165                 return xfrm_output_gso(skb);
 166
 167         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 168                 err = skb_checksum_help(skb);
 169                 if (err) {
 170                         kfree_skb(skb);
 171                         return err;
 172                 }
 173         }
 174
 175         return xfrm_output2(skb);
 176 }
 177 EXPORT_SYMBOL_GPL(xfrm_output);