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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(skb);
  26         int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
  27                 - skb_headroom(skb);
  28         int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
  29
  30         if (nhead <= 0) {
  31                 if (ntail <= 0)
  32                         return 0;
  33                 nhead = 0;
  34         } else if (ntail < 0)
  35                 ntail = 0;
  36
  37         return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
  38 }
  39
  40 static int xfrm_output_one(struct sk_buff *skb, int err)
  41 {
  42         struct dst_entry *dst = skb_dst(skb);
  43         struct xfrm_state *x = dst->xfrm;
  44         struct net *net = xs_net(x);
  45
  46         if (err <= 0)
  47                 goto resume;
  48
  49         do {
  50                 err = xfrm_state_check_space(x, skb);
  51                 if (err) {
  52                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  53                         goto error_nolock;
  54                 }
  55
  56                 err = x->outer_mode->output(x, skb);
  57                 if (err) {
  58                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
  59                         goto error_nolock;
  60                 }
  61
  62                 spin_lock_bh(&x->lock);
  63                 err = xfrm_state_check_expire(x);
  64                 if (err) {
  65                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  66                         goto error;
  67                 }
  68
  69                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
  70                         XFRM_SKB_CB(skb)->seq.output = ++x->replay.oseq;
  71                         if (unlikely(x->replay.oseq == 0)) {
  72                                 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  73                                 x->replay.oseq--;
  74                                 xfrm_audit_state_replay_overflow(x, skb);
  75                                 err = -EOVERFLOW;
  76                                 goto error;
  77                         }
  78                         if (xfrm_aevent_is_on(net))
  79                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  80                 }
  81
  82                 x->curlft.bytes += skb->len;
  83                 x->curlft.packets++;
  84
  85                 spin_unlock_bh(&x->lock);
  86
  87                 err = x->type->output(x, skb);
  88                 if (err == -EINPROGRESS)
  89                         goto out_exit;
  90
  91 resume:
  92                 if (err) {
  93                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  94                         goto error_nolock;
  95                 }
  96
  97                 dst = dst_pop(dst);
  98                 if (!dst) {
  99                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 100                         err = -EHOSTUNREACH;
 101                         goto error_nolock;
 102                 }
 103                 skb_dst_set(skb, dst);
 104                 x = dst->xfrm;
 105         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 106
 107         err = 0;
 108
 109 out_exit:
 110         return err;
 111 error:
 112         spin_unlock_bh(&x->lock);
 113 error_nolock:
 114         kfree_skb(skb);
 115         goto out_exit;
 116 }
 117
 118 int xfrm_output_resume(struct sk_buff *skb, int err)
 119 {
 120         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 121                 nf_reset(skb);
 122
 123                 err = skb_dst(skb)->ops->local_out(skb);
 124                 if (unlikely(err != 1))
 125                         goto out;
 126
 127                 if (!skb_dst(skb)->xfrm)
 128                         return dst_output(skb);
 129
 130                 err = nf_hook(skb_dst(skb)->ops->family,
 131                               NF_INET_POST_ROUTING, skb,
 132                               NULL, skb_dst(skb)->dev, xfrm_output2);
 133                 if (unlikely(err != 1))
 134                         goto out;
 135         }
 136
 137         if (err == -EINPROGRESS)
 138                 err = 0;
 139
 140 out:
 141         return err;
 142 }
 143 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 144
 145 static int xfrm_output2(struct sk_buff *skb)
 146 {
 147         return xfrm_output_resume(skb, 1);
 148 }
 149
 150 static int xfrm_output_gso(struct sk_buff *skb)
 151 {
 152         struct sk_buff *segs;
 153
 154         segs = skb_gso_segment(skb, 0);
 155         kfree_skb(skb);
 156         if (IS_ERR(segs))
 157                 return PTR_ERR(segs);
 158
 159         do {
 160                 struct sk_buff *nskb = segs->next;
 161                 int err;
 162
 163                 segs->next = NULL;
 164                 err = xfrm_output2(segs);
 165
 166                 if (unlikely(err)) {
 167                         while ((segs = nskb)) {
 168                                 nskb = segs->next;
 169                                 segs->next = NULL;
 170                                 kfree_skb(segs);
 171                         }
 172                         return err;
 173                 }
 174
 175                 segs = nskb;
 176         } while (segs);
 177
 178         return 0;
 179 }
 180
 181 int xfrm_output(struct sk_buff *skb)
 182 {
 183         struct net *net = dev_net(skb_dst(skb)->dev);
 184         int err;
 185
 186         if (skb_is_gso(skb))
 187                 return xfrm_output_gso(skb);
 188
 189         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 190                 err = skb_checksum_help(skb);
 191                 if (err) {
 192                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 193                         kfree_skb(skb);
 194                         return err;
 195                 }
 196         }
 197
 198         return xfrm_output2(skb);
 199 }
 200
 201 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 202 {
 203         struct xfrm_mode *inner_mode;
 204         if (x->sel.family == AF_UNSPEC)
 205                 inner_mode = xfrm_ip2inner_mode(x,
 206                                 xfrm_af2proto(skb_dst(skb)->ops->family));
 207         else
 208                 inner_mode = x->inner_mode;
 209
 210         if (inner_mode == NULL)
 211                 return -EAFNOSUPPORT;
 212         return inner_mode->afinfo->extract_output(x, skb);
 213 }
 214
 215 EXPORT_SYMBOL_GPL(xfrm_output);
 216 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);