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                 err = xfrm_state_check_expire(x);
  65                 if (err) {
  66                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  67                         goto error;
  68                 }
  69
  70                 err = x->repl->overflow(x, skb);
  71                 if (err) {
  72                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  73                         goto error;
  74                 }
  75
  76                 x->curlft.bytes += skb->len;
  77                 x->curlft.packets++;
  78
  79                 spin_unlock_bh(&x->lock);
  80
  81                 skb_dst_force(skb);
  82
  83                 err = x->type->output(x, skb);
  84                 if (err == -EINPROGRESS)
  85                         goto out_exit;
  86
  87 resume:
  88                 if (err) {
  89                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  90                         goto error_nolock;
  91                 }
  92
  93                 dst = skb_dst_pop(skb);
  94                 if (!dst) {
  95                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  96                         err = -EHOSTUNREACH;
  97                         goto error_nolock;
  98                 }
  99                 skb_dst_set(skb, dst);
 100                 x = dst->xfrm;
 101         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 102
 103         err = 0;
 104
 105 out_exit:
 106         return err;
 107 error:
 108         spin_unlock_bh(&x->lock);
 109 error_nolock:
 110         kfree_skb(skb);
 111         goto out_exit;
 112 }
 113
 114 int xfrm_output_resume(struct sk_buff *skb, int err)
 115 {
 116         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 117                 nf_reset(skb);
 118
 119                 err = skb_dst(skb)->ops->local_out(skb);
 120                 if (unlikely(err != 1))
 121                         goto out;
 122
 123                 if (!skb_dst(skb)->xfrm)
 124                         return dst_output(skb);
 125
 126                 err = nf_hook(skb_dst(skb)->ops->family,
 127                               NF_INET_POST_ROUTING, skb,
 128                               NULL, skb_dst(skb)->dev, xfrm_output2);
 129                 if (unlikely(err != 1))
 130                         goto out;
 131         }
 132
 133         if (err == -EINPROGRESS)
 134                 err = 0;
 135
 136 out:
 137         return err;
 138 }
 139 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 140
 141 static int xfrm_output2(struct sk_buff *skb)
 142 {
 143         return xfrm_output_resume(skb, 1);
 144 }
 145
 146 static int xfrm_output_gso(struct sk_buff *skb)
 147 {
 148         struct sk_buff *segs;
 149
 150         segs = skb_gso_segment(skb, 0);
 151         kfree_skb(skb);
 152         if (IS_ERR(segs))
 153                 return PTR_ERR(segs);
 154
 155         do {
 156                 struct sk_buff *nskb = segs->next;
 157                 int err;
 158
 159                 segs->next = NULL;
 160                 err = xfrm_output2(segs);
 161
 162                 if (unlikely(err)) {
 163                         while ((segs = nskb)) {
 164                                 nskb = segs->next;
 165                                 segs->next = NULL;
 166                                 kfree_skb(segs);
 167                         }
 168                         return err;
 169                 }
 170
 171                 segs = nskb;
 172         } while (segs);
 173
 174         return 0;
 175 }
 176
 177 int xfrm_output(struct sk_buff *skb)
 178 {
 179         struct net *net = dev_net(skb_dst(skb)->dev);
 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(net, LINUX_MIB_XFRMOUTERROR);
 189                         kfree_skb(skb);
 190                         return err;
 191                 }
 192         }
 193
 194         return xfrm_output2(skb);
 195 }
 196
 197 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 198 {
 199         struct xfrm_mode *inner_mode;
 200         if (x->sel.family == AF_UNSPEC)
 201                 inner_mode = xfrm_ip2inner_mode(x,
 202                                 xfrm_af2proto(skb_dst(skb)->ops->family));
 203         else
 204                 inner_mode = x->inner_mode;
 205
 206         if (inner_mode == NULL)
 207                 return -EAFNOSUPPORT;
 208         return inner_mode->afinfo->extract_output(x, skb);
 209 }
 210
 211 EXPORT_SYMBOL_GPL(xfrm_output);
 212 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);