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/slab.h>
  18 #include <linux/spinlock.h>
  19 #include <net/dst.h>
  20 #include <net/xfrm.h>
  21
  22 static int xfrm_output2(struct sk_buff *skb);
  23
  24 static int xfrm_skb_check_space(struct sk_buff *skb)
  25 {
  26         struct dst_entry *dst = skb_dst(skb);
  27         int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
  28                 - skb_headroom(skb);
  29         int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
  30
  31         if (nhead <= 0) {
  32                 if (ntail <= 0)
  33                         return 0;
  34                 nhead = 0;
  35         } else if (ntail < 0)
  36                 ntail = 0;
  37
  38         return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
  39 }
  40
  41 static int xfrm_output_one(struct sk_buff *skb, int err)
  42 {
  43         struct dst_entry *dst = skb_dst(skb);
  44         struct xfrm_state *x = dst->xfrm;
  45         struct net *net = xs_net(x);
  46
  47         if (err <= 0)
  48                 goto resume;
  49
  50         do {
  51                 err = xfrm_skb_check_space(skb);
  52                 if (err) {
  53                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  54                         goto error_nolock;
  55                 }
  56
  57                 err = x->outer_mode->output(x, skb);
  58                 if (err) {
  59                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
  60                         goto error_nolock;
  61                 }
  62
  63                 spin_lock_bh(&x->lock);
  64
  65                 if (unlikely(x->km.state != XFRM_STATE_VALID)) {
  66                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
  67                         err = -EINVAL;
  68                         goto error;
  69                 }
  70
  71                 err = xfrm_state_check_expire(x);
  72                 if (err) {
  73                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  74                         goto error;
  75                 }
  76
  77                 err = x->repl->overflow(x, skb);
  78                 if (err) {
  79                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  80                         goto error;
  81                 }
  82
  83                 x->curlft.bytes += skb->len;
  84                 x->curlft.packets++;
  85
  86                 spin_unlock_bh(&x->lock);
  87
  88                 skb_dst_force(skb);
  89
  90                 err = x->type->output(x, skb);
  91                 if (err == -EINPROGRESS)
  92                         goto out_exit;
  93
  94 resume:
  95                 if (err) {
  96                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  97                         goto error_nolock;
  98                 }
  99
 100                 dst = skb_dst_pop(skb);
 101                 if (!dst) {
 102                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 103                         err = -EHOSTUNREACH;
 104                         goto error_nolock;
 105                 }
 106                 skb_dst_set(skb, dst);
 107                 x = dst->xfrm;
 108         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 109
 110         err = 0;
 111
 112 out_exit:
 113         return err;
 114 error:
 115         spin_unlock_bh(&x->lock);
 116 error_nolock:
 117         kfree_skb(skb);
 118         goto out_exit;
 119 }
 120
 121 int xfrm_output_resume(struct sk_buff *skb, int err)
 122 {
 123         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 124                 nf_reset(skb);
 125
 126                 err = skb_dst(skb)->ops->local_out(skb);
 127                 if (unlikely(err != 1))
 128                         goto out;
 129
 130                 if (!skb_dst(skb)->xfrm)
 131                         return dst_output(skb);
 132
 133                 err = nf_hook(skb_dst(skb)->ops->family,
 134                               NF_INET_POST_ROUTING, skb,
 135                               NULL, skb_dst(skb)->dev, xfrm_output2);
 136                 if (unlikely(err != 1))
 137                         goto out;
 138         }
 139
 140         if (err == -EINPROGRESS)
 141                 err = 0;
 142
 143 out:
 144         return err;
 145 }
 146 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 147
 148 static int xfrm_output2(struct sk_buff *skb)
 149 {
 150         return xfrm_output_resume(skb, 1);
 151 }
 152
 153 static int xfrm_output_gso(struct sk_buff *skb)
 154 {
 155         struct sk_buff *segs;
 156
 157         segs = skb_gso_segment(skb, 0);
 158         kfree_skb(skb);
 159         if (IS_ERR(segs))
 160                 return PTR_ERR(segs);
 161
 162         do {
 163                 struct sk_buff *nskb = segs->next;
 164                 int err;
 165
 166                 segs->next = NULL;
 167                 err = xfrm_output2(segs);
 168
 169                 if (unlikely(err)) {
 170                         while ((segs = nskb)) {
 171                                 nskb = segs->next;
 172                                 segs->next = NULL;
 173                                 kfree_skb(segs);
 174                         }
 175                         return err;
 176                 }
 177
 178                 segs = nskb;
 179         } while (segs);
 180
 181         return 0;
 182 }
 183
 184 int xfrm_output(struct sk_buff *skb)
 185 {
 186         struct net *net = dev_net(skb_dst(skb)->dev);
 187         int err;
 188
 189         if (skb_is_gso(skb))
 190                 return xfrm_output_gso(skb);
 191
 192         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 193                 err = skb_checksum_help(skb);
 194                 if (err) {
 195                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 196                         kfree_skb(skb);
 197                         return err;
 198                 }
 199         }
 200
 201         return xfrm_output2(skb);
 202 }
 203
 204 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 205 {
 206         struct xfrm_mode *inner_mode;
 207         if (x->sel.family == AF_UNSPEC)
 208                 inner_mode = xfrm_ip2inner_mode(x,
 209                                 xfrm_af2proto(skb_dst(skb)->ops->family));
 210         else
 211                 inner_mode = x->inner_mode;
 212
 213         if (inner_mode == NULL)
 214                 return -EAFNOSUPPORT;
 215         return inner_mode->afinfo->extract_output(x, skb);
 216 }
 217
 218 EXPORT_SYMBOL_GPL(xfrm_output);
 219 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);