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 (unlikely(x->replay.oseq == 0)) {
  61                                 x->replay.oseq--;
  62                                 xfrm_audit_state_replay_overflow(x, skb);
  63                                 goto error;
  64                         }
  65                         if (xfrm_aevent_is_on())
  66                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  67                 }
  68
  69                 x->curlft.bytes += skb->len;
  70                 x->curlft.packets++;
  71
  72                 spin_unlock_bh(&x->lock);
  73
  74                 err = x->type->output(x, skb);
  75
  76 resume:
  77                 if (err) {
  78                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  79                         goto error_nolock;
  80                 }
  81
  82                 if (!(skb->dst = dst_pop(dst))) {
  83                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
  84                         err = -EHOSTUNREACH;
  85                         goto error_nolock;
  86                 }
  87                 dst = skb->dst;
  88                 x = dst->xfrm;
  89         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
  90
  91         err = 0;
  92
  93 out_exit:
  94         return err;
  95 error:
  96         spin_unlock_bh(&x->lock);
  97 error_nolock:
  98         kfree_skb(skb);
  99         goto out_exit;
 100 }
 101
 102 int xfrm_output_resume(struct sk_buff *skb, int err)
 103 {
 104         while (likely((err = xfrm_output_one(skb, err)) == 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                         goto out;
 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                               NF_INET_POST_ROUTING, skb,
 119                               NULL, skb->dst->dev, xfrm_output2);
 120                 if (unlikely(err != 1))
 121                         goto out;
 122         }
 123
 124         if (err == -EINPROGRESS)
 125                 err = 0;
 126
 127 out:
 128         return err;
 129 }
 130 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 131
 132 static int xfrm_output2(struct sk_buff *skb)
 133 {
 134         return xfrm_output_resume(skb, 1);
 135 }
 136
 137 static int xfrm_output_gso(struct sk_buff *skb)
 138 {
 139         struct sk_buff *segs;
 140
 141         segs = skb_gso_segment(skb, 0);
 142         kfree_skb(skb);
 143         if (unlikely(IS_ERR(segs)))
 144                 return PTR_ERR(segs);
 145
 146         do {
 147                 struct sk_buff *nskb = segs->next;
 148                 int err;
 149
 150                 segs->next = NULL;
 151                 err = xfrm_output2(segs);
 152
 153                 if (unlikely(err)) {
 154                         while ((segs = nskb)) {
 155                                 nskb = segs->next;
 156                                 segs->next = NULL;
 157                                 kfree_skb(segs);
 158                         }
 159                         return err;
 160                 }
 161
 162                 segs = nskb;
 163         } while (segs);
 164
 165         return 0;
 166 }
 167
 168 int xfrm_output(struct sk_buff *skb)
 169 {
 170         int err;
 171
 172         if (skb_is_gso(skb))
 173                 return xfrm_output_gso(skb);
 174
 175         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 176                 err = skb_checksum_help(skb);
 177                 if (err) {
 178                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
 179                         kfree_skb(skb);
 180                         return err;
 181                 }
 182         }
 183
 184         return xfrm_output2(skb);
 185 }
 186 EXPORT_SYMBOL_GPL(xfrm_output);