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_state_check_space(struct xfrm_state *x, 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_state_check_space(x, 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                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
  71                         XFRM_SKB_CB(skb)->seq.output = ++x->replay.oseq;
  72                         if (unlikely(x->replay.oseq == 0)) {
  73                                 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  74                                 x->replay.oseq--;
  75                                 xfrm_audit_state_replay_overflow(x, skb);
  76                                 err = -EOVERFLOW;
  77                                 goto error;
  78                         }
  79                         if (xfrm_aevent_is_on(net))
  80                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
  81                 }
  82
  83                 x->curlft.bytes += skb->len;
  84                 x->curlft.packets++;
  85
  86                 spin_unlock_bh(&x->lock);
  87
  88                 err = x->type->output(x, skb);
  89                 if (err == -EINPROGRESS)
  90                         goto out_exit;
  91
  92 resume:
  93                 if (err) {
  94                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  95                         goto error_nolock;
  96                 }
  97
  98                 dst = skb_dst_pop(skb);
  99                 if (!dst) {
 100                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 101                         err = -EHOSTUNREACH;
 102                         goto error_nolock;
 103                 }
 104                 skb_dst_set_noref(skb, dst);
 105                 x = dst->xfrm;
 106         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 107
 108         err = 0;
 109
 110 out_exit:
 111         return err;
 112 error:
 113         spin_unlock_bh(&x->lock);
 114 error_nolock:
 115         kfree_skb(skb);
 116         goto out_exit;
 117 }
 118
 119 int xfrm_output_resume(struct sk_buff *skb, int err)
 120 {
 121         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 122                 nf_reset(skb);
 123
 124                 err = skb_dst(skb)->ops->local_out(skb);
 125                 if (unlikely(err != 1))
 126                         goto out;
 127
 128                 if (!skb_dst(skb)->xfrm)
 129                         return dst_output(skb);
 130
 131                 err = nf_hook(skb_dst(skb)->ops->family,
 132                               NF_INET_POST_ROUTING, skb,
 133                               NULL, skb_dst(skb)->dev, xfrm_output2);
 134                 if (unlikely(err != 1))
 135                         goto out;
 136         }
 137
 138         if (err == -EINPROGRESS)
 139                 err = 0;
 140
 141 out:
 142         return err;
 143 }
 144 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 145
 146 static int xfrm_output2(struct sk_buff *skb)
 147 {
 148         return xfrm_output_resume(skb, 1);
 149 }
 150
 151 static int xfrm_output_gso(struct sk_buff *skb)
 152 {
 153         struct sk_buff *segs;
 154
 155         segs = skb_gso_segment(skb, 0);
 156         kfree_skb(skb);
 157         if (IS_ERR(segs))
 158                 return PTR_ERR(segs);
 159
 160         do {
 161                 struct sk_buff *nskb = segs->next;
 162                 int err;
 163
 164                 segs->next = NULL;
 165                 err = xfrm_output2(segs);
 166
 167                 if (unlikely(err)) {
 168                         while ((segs = nskb)) {
 169                                 nskb = segs->next;
 170                                 segs->next = NULL;
 171                                 kfree_skb(segs);
 172                         }
 173                         return err;
 174                 }
 175
 176                 segs = nskb;
 177         } while (segs);
 178
 179         return 0;
 180 }
 181
 182 int xfrm_output(struct sk_buff *skb)
 183 {
 184         struct net *net = dev_net(skb_dst(skb)->dev);
 185         int err;
 186
 187         if (skb_is_gso(skb))
 188                 return xfrm_output_gso(skb);
 189
 190         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 191                 err = skb_checksum_help(skb);
 192                 if (err) {
 193                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 194                         kfree_skb(skb);
 195                         return err;
 196                 }
 197         }
 198
 199         return xfrm_output2(skb);
 200 }
 201
 202 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 203 {
 204         struct xfrm_mode *inner_mode;
 205         if (x->sel.family == AF_UNSPEC)
 206                 inner_mode = xfrm_ip2inner_mode(x,
 207                                 xfrm_af2proto(skb_dst(skb)->ops->family));
 208         else
 209                 inner_mode = x->inner_mode;
 210
 211         if (inner_mode == NULL)
 212                 return -EAFNOSUPPORT;
 213         return inner_mode->afinfo->extract_output(x, skb);
 214 }
 215
 216 EXPORT_SYMBOL_GPL(xfrm_output);
 217 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);