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