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 sock *sk, 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;
  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         return 0;
 111
 112 error:
 113         spin_unlock_bh(&x->lock);
 114 error_nolock:
 115         kfree_skb(skb);
 116 out:
 117         return err;
 118 }
 119
 120 int xfrm_output_resume(struct sk_buff *skb, int err)
 121 {
 122         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 123                 nf_reset(skb);
 124
 125                 err = skb_dst(skb)->ops->local_out(skb);
 126                 if (unlikely(err != 1))
 127                         goto out;
 128
 129                 if (!skb_dst(skb)->xfrm)
 130                         return dst_output(skb);
 131
 132                 err = nf_hook(skb_dst(skb)->ops->family,
 133                               NF_INET_POST_ROUTING, skb->sk, skb,
 134                               NULL, skb_dst(skb)->dev, xfrm_output2);
 135                 if (unlikely(err != 1))
 136                         goto out;
 137         }
 138
 139         if (err == -EINPROGRESS)
 140                 err = 0;
 141
 142 out:
 143         return err;
 144 }
 145 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 146
 147 static int xfrm_output2(struct sock *sk, struct sk_buff *skb)
 148 {
 149         return xfrm_output_resume(skb, 1);
 150 }
 151
 152 static int xfrm_output_gso(struct sock *sk, struct sk_buff *skb)
 153 {
 154         struct sk_buff *segs;
 155
 156         segs = skb_gso_segment(skb, 0);
 157         kfree_skb(skb);
 158         if (IS_ERR(segs))
 159                 return PTR_ERR(segs);
 160         if (segs == NULL)
 161                 return -EINVAL;
 162
 163         do {
 164                 struct sk_buff *nskb = segs->next;
 165                 int err;
 166
 167                 segs->next = NULL;
 168                 err = xfrm_output2(sk, segs);
 169
 170                 if (unlikely(err)) {
 171                         kfree_skb_list(nskb);
 172                         return err;
 173                 }
 174
 175                 segs = nskb;
 176         } while (segs);
 177
 178         return 0;
 179 }
 180
 181 int xfrm_output(struct sock *sk, struct sk_buff *skb)
 182 {
 183         struct net *net = dev_net(skb_dst(skb)->dev);
 184         int err;
 185
 186         if (skb_is_gso(skb))
 187                 return xfrm_output_gso(sk, skb);
 188
 189         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 190                 err = skb_checksum_help(skb);
 191                 if (err) {
 192                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 193                         kfree_skb(skb);
 194                         return err;
 195                 }
 196         }
 197
 198         return xfrm_output2(sk, skb);
 199 }
 200 EXPORT_SYMBOL_GPL(xfrm_output);
 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 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
 216
 217 void xfrm_local_error(struct sk_buff *skb, int mtu)
 218 {
 219         unsigned int proto;
 220         struct xfrm_state_afinfo *afinfo;
 221
 222         if (skb->protocol == htons(ETH_P_IP))
 223                 proto = AF_INET;
 224         else if (skb->protocol == htons(ETH_P_IPV6))
 225                 proto = AF_INET6;
 226         else
 227                 return;
 228
 229         afinfo = xfrm_state_get_afinfo(proto);
 230         if (!afinfo)
 231                 return;
 232
 233         afinfo->local_error(skb, mtu);
 234         xfrm_state_put_afinfo(afinfo);
 235 }
 236 EXPORT_SYMBOL_GPL(xfrm_local_error);