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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_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                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
  48                         goto error_nolock;
  49                 }
  50
  51                 err = x->outer_mode->output(x, skb);
  52                 if (err) {
  53                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEMODEERROR);
  54                         goto error_nolock;
  55                 }
  56
  57                 spin_lock_bh(&x->lock);
  58                 err = xfrm_state_check_expire(x);
  59                 if (err) {
  60                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEEXPIRED);
  61                         goto error;
  62                 }
  63
  64                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
  65                         XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;
  66                         if (unlikely(x->replay.oseq == 0)) {
  67                                 XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATESEQERROR);
  68                                 x->replay.oseq--;
  69                                 xfrm_audit_state_replay_overflow(x, skb);
  70                                 err = -EOVERFLOW;
  71                                 goto error;
  72                         }
  73                         if (xfrm_aevent_is_on())
  74                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  75                 }
  76
  77                 x->curlft.bytes += skb->len;
  78                 x->curlft.packets++;
  79
  80                 spin_unlock_bh(&x->lock);
  81
  82                 err = x->type->output(x, skb);
  83                 if (err == -EINPROGRESS)
  84                         goto out_exit;
  85
  86 resume:
  87                 if (err) {
  88                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  89                         goto error_nolock;
  90                 }
  91
  92                 if (!(skb->dst = dst_pop(dst))) {
  93                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
  94                         err = -EHOSTUNREACH;
  95                         goto error_nolock;
  96                 }
  97                 dst = skb->dst;
  98                 x = dst->xfrm;
  99         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 100
 101         err = 0;
 102
 103 out_exit:
 104         return err;
 105 error:
 106         spin_unlock_bh(&x->lock);
 107 error_nolock:
 108         kfree_skb(skb);
 109         goto out_exit;
 110 }
 111
 112 int xfrm_output_resume(struct sk_buff *skb, int err)
 113 {
 114         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 115                 struct xfrm_state *x;
 116
 117                 nf_reset(skb);
 118
 119                 err = skb->dst->ops->local_out(skb);
 120                 if (unlikely(err != 1))
 121                         goto out;
 122
 123                 x = skb->dst->xfrm;
 124                 if (!x)
 125                         return dst_output(skb);
 126
 127                 err = nf_hook(x->inner_mode->afinfo->family,
 128                               NF_INET_POST_ROUTING, skb,
 129                               NULL, skb->dst->dev, xfrm_output2);
 130                 if (unlikely(err != 1))
 131                         goto out;
 132         }
 133
 134         if (err == -EINPROGRESS)
 135                 err = 0;
 136
 137 out:
 138         return err;
 139 }
 140 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 141
 142 static int xfrm_output2(struct sk_buff *skb)
 143 {
 144         return xfrm_output_resume(skb, 1);
 145 }
 146
 147 static int xfrm_output_gso(struct sk_buff *skb)
 148 {
 149         struct sk_buff *segs;
 150
 151         segs = skb_gso_segment(skb, 0);
 152         kfree_skb(skb);
 153         if (unlikely(IS_ERR(segs)))
 154                 return PTR_ERR(segs);
 155
 156         do {
 157                 struct sk_buff *nskb = segs->next;
 158                 int err;
 159
 160                 segs->next = NULL;
 161                 err = xfrm_output2(segs);
 162
 163                 if (unlikely(err)) {
 164                         while ((segs = nskb)) {
 165                                 nskb = segs->next;
 166                                 segs->next = NULL;
 167                                 kfree_skb(segs);
 168                         }
 169                         return err;
 170                 }
 171
 172                 segs = nskb;
 173         } while (segs);
 174
 175         return 0;
 176 }
 177
 178 int xfrm_output(struct sk_buff *skb)
 179 {
 180         int err;
 181
 182         if (skb_is_gso(skb))
 183                 return xfrm_output_gso(skb);
 184
 185         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 186                 err = skb_checksum_help(skb);
 187                 if (err) {
 188                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
 189                         kfree_skb(skb);
 190                         return err;
 191                 }
 192         }
 193
 194         return xfrm_output2(skb);
 195 }
 196 EXPORT_SYMBOL_GPL(xfrm_output);