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
  29         if (nhead > 0)
  30                 return pskb_expand_head(skb, nhead, 0, GFP_ATOMIC);
  31
  32         /* Check tail too... */
  33         return 0;
  34 }
  35
  36 static int xfrm_output_one(struct sk_buff *skb, int err)
  37 {
  38         struct dst_entry *dst = skb->dst;
  39         struct xfrm_state *x = dst->xfrm;
  40
  41         if (err <= 0)
  42                 goto resume;
  43
  44         do {
  45                 err = xfrm_state_check_space(x, skb);
  46                 if (err) {
  47                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
  48                         goto error_nolock;
  49                 }
  50
  51                 err = x->outer_mode->output(x, skb);
  52                 if (err) {
  53                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEMODEERROR);
  54                         goto error_nolock;
  55                 }
  56
  57                 spin_lock_bh(&x->lock);
  58                 err = xfrm_state_check_expire(x);
  59                 if (err) {
  60                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEEXPIRED);
  61                         goto error;
  62                 }
  63
  64                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
  65                         XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;
  66                         if (unlikely(x->replay.oseq == 0)) {
  67                                 x->replay.oseq--;
  68                                 xfrm_audit_state_replay_overflow(x, skb);
  69                                 err = -EOVERFLOW;
  70                                 goto error;
  71                         }
  72                         if (xfrm_aevent_is_on())
  73                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  74                 }
  75
  76                 x->curlft.bytes += skb->len;
  77                 x->curlft.packets++;
  78
  79                 spin_unlock_bh(&x->lock);
  80
  81                 err = x->type->output(x, skb);
  82                 if (err == -EINPROGRESS)
  83                         goto out_exit;
  84
  85 resume:
  86                 if (err) {
  87                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  88                         goto error_nolock;
  89                 }
  90
  91                 if (!(skb->dst = dst_pop(dst))) {
  92                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
  93                         err = -EHOSTUNREACH;
  94                         goto error_nolock;
  95                 }
  96                 dst = skb->dst;
  97                 x = dst->xfrm;
  98         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
  99
 100         err = 0;
 101
 102 out_exit:
 103         return err;
 104 error:
 105         spin_unlock_bh(&x->lock);
 106 error_nolock:
 107         kfree_skb(skb);
 108         goto out_exit;
 109 }
 110
 111 int xfrm_output_resume(struct sk_buff *skb, int err)
 112 {
 113         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 114                 struct xfrm_state *x;
 115
 116                 nf_reset(skb);
 117
 118                 err = skb->dst->ops->local_out(skb);
 119                 if (unlikely(err != 1))
 120                         goto out;
 121
 122                 x = skb->dst->xfrm;
 123                 if (!x)
 124                         return dst_output(skb);
 125
 126                 err = nf_hook(x->inner_mode->afinfo->family,
 127                               NF_INET_POST_ROUTING, skb,
 128                               NULL, skb->dst->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 (unlikely(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         int err;
 180
 181         if (skb_is_gso(skb))
 182                 return xfrm_output_gso(skb);
 183
 184         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 185                 err = skb_checksum_help(skb);
 186                 if (err) {
 187                         XFRM_INC_STATS(LINUX_MIB_XFRMOUTERROR);
 188                         kfree_skb(skb);
 189                         return err;
 190                 }
 191         }
 192
 193         return xfrm_output2(skb);
 194 }
 195 EXPORT_SYMBOL_GPL(xfrm_output);