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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         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;
  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                 if (!(skb->dst = dst_pop(dst))) {
  98                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  99                         err = -EHOSTUNREACH;
 100                         goto error_nolock;
 101                 }
 102                 dst = skb->dst;
 103                 x = dst->xfrm;
 104         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 105
 106         err = 0;
 107
 108 out_exit:
 109         return err;
 110 error:
 111         spin_unlock_bh(&x->lock);
 112 error_nolock:
 113         kfree_skb(skb);
 114         goto out_exit;
 115 }
 116
 117 int xfrm_output_resume(struct sk_buff *skb, int err)
 118 {
 119         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 120                 nf_reset(skb);
 121
 122                 err = skb->dst->ops->local_out(skb);
 123                 if (unlikely(err != 1))
 124                         goto out;
 125
 126                 if (!skb->dst->xfrm)
 127                         return dst_output(skb);
 128
 129                 err = nf_hook(skb->dst->ops->family,
 130                               NF_INET_POST_ROUTING, skb,
 131                               NULL, skb->dst->dev, xfrm_output2);
 132                 if (unlikely(err != 1))
 133                         goto out;
 134         }
 135
 136         if (err == -EINPROGRESS)
 137                 err = 0;
 138
 139 out:
 140         return err;
 141 }
 142 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 143
 144 static int xfrm_output2(struct sk_buff *skb)
 145 {
 146         return xfrm_output_resume(skb, 1);
 147 }
 148
 149 static int xfrm_output_gso(struct sk_buff *skb)
 150 {
 151         struct sk_buff *segs;
 152
 153         segs = skb_gso_segment(skb, 0);
 154         kfree_skb(skb);
 155         if (IS_ERR(segs))
 156                 return PTR_ERR(segs);
 157
 158         do {
 159                 struct sk_buff *nskb = segs->next;
 160                 int err;
 161
 162                 segs->next = NULL;
 163                 err = xfrm_output2(segs);
 164
 165                 if (unlikely(err)) {
 166                         while ((segs = nskb)) {
 167                                 nskb = segs->next;
 168                                 segs->next = NULL;
 169                                 kfree_skb(segs);
 170                         }
 171                         return err;
 172                 }
 173
 174                 segs = nskb;
 175         } while (segs);
 176
 177         return 0;
 178 }
 179
 180 int xfrm_output(struct sk_buff *skb)
 181 {
 182         struct net *net = dev_net(skb->dst->dev);
 183         int err;
 184
 185         if (skb_is_gso(skb))
 186                 return xfrm_output_gso(skb);
 187
 188         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 189                 err = skb_checksum_help(skb);
 190                 if (err) {
 191                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 192                         kfree_skb(skb);
 193                         return err;
 194                 }
 195         }
 196
 197         return xfrm_output2(skb);
 198 }
 199
 200 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 201 {
 202         struct xfrm_mode *inner_mode;
 203         if (x->sel.family == AF_UNSPEC)
 204                 inner_mode = xfrm_ip2inner_mode(x,
 205                                 xfrm_af2proto(skb->dst->ops->family));
 206         else
 207                 inner_mode = x->inner_mode;
 208
 209         if (inner_mode == NULL)
 210                 return -EAFNOSUPPORT;
 211         return inner_mode->afinfo->extract_output(x, skb);
 212 }
 213
 214 EXPORT_SYMBOL_GPL(xfrm_output);
 215 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);