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   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_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
  22 {
  23         struct dst_entry *dst = skb->dst;
  24         int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
  25                 - skb_headroom(skb);
  26
  27         if (nhead > 0)
  28                 return pskb_expand_head(skb, nhead, 0, GFP_ATOMIC);
  29
  30         /* Check tail too... */
  31         return 0;
  32 }
  33
  34 static int xfrm_state_check(struct xfrm_state *x, struct sk_buff *skb)
  35 {
  36         int err = xfrm_state_check_expire(x);
  37         if (err < 0)
  38                 goto err;
  39         err = xfrm_state_check_space(x, skb);
  40 err:
  41         return err;
  42 }
  43
  44 static int xfrm_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         do {
  57                 err = x->outer_mode->output(x, skb);
  58                 if (err)
  59                         goto error;
  60
  61                 spin_lock_bh(&x->lock);
  62                 err = xfrm_state_check(x, skb);
  63                 if (err)
  64                         goto error;
  65
  66                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
  67                         XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;
  68                         if (xfrm_aevent_is_on())
  69                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  70                 }
  71
  72                 x->curlft.bytes += skb->len;
  73                 x->curlft.packets++;
  74
  75                 spin_unlock_bh(&x->lock);
  76
  77                 err = x->type->output(x, skb);
  78                 if (err)
  79                         goto error_nolock;
  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->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
  88
  89         err = 0;
  90
  91 out_exit:
  92         return err;
  93 error:
  94         spin_unlock_bh(&x->lock);
  95 error_nolock:
  96         kfree_skb(skb);
  97         goto out_exit;
  98 }
  99
 100 static int xfrm_output2(struct sk_buff *skb)
 101 {
 102         int err;
 103
 104         while (likely((err = xfrm_output_one(skb)) == 0)) {
 105                 struct xfrm_state *x;
 106
 107                 nf_reset(skb);
 108
 109                 err = skb->dst->ops->local_out(skb);
 110                 if (unlikely(err != 1))
 111                         break;
 112
 113                 x = skb->dst->xfrm;
 114                 if (!x)
 115                         return dst_output(skb);
 116
 117                 err = nf_hook(x->inner_mode->afinfo->family,
 118                               x->inner_mode->afinfo->nf_post_routing, skb,
 119                               NULL, skb->dst->dev, xfrm_output2);
 120                 if (unlikely(err != 1))
 121                         break;
 122         }
 123
 124         return err;
 125 }
 126
 127 int xfrm_output(struct sk_buff *skb)
 128 {
 129         struct sk_buff *segs;
 130
 131         if (!skb_is_gso(skb))
 132                 return xfrm_output2(skb);
 133
 134         segs = skb_gso_segment(skb, 0);
 135         kfree_skb(skb);
 136         if (unlikely(IS_ERR(segs)))
 137                 return PTR_ERR(segs);
 138
 139         do {
 140                 struct sk_buff *nskb = segs->next;
 141                 int err;
 142
 143                 segs->next = NULL;
 144                 err = xfrm_output2(segs);
 145
 146                 if (unlikely(err)) {
 147                         while ((segs = nskb)) {
 148                                 nskb = segs->next;
 149                                 segs->next = NULL;
 150                                 kfree_skb(segs);
 151                         }
 152                         return err;
 153                 }
 154
 155                 segs = nskb;
 156         } while (segs);
 157
 158         return 0;
 159 }
 160 EXPORT_SYMBOL_GPL(xfrm_output);