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 net *net, 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 /* Children define the path of the packet through the
  42  * Linux networking.  Thus, destinations are stackable.
  43  */
  44
  45 static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
  46 {
  47         struct dst_entry *child = dst_clone(xfrm_dst_child(skb_dst(skb)));
  48
  49         skb_dst_drop(skb);
  50         return child;
  51 }
  52
  53 static int xfrm_output_one(struct sk_buff *skb, int err)
  54 {
  55         struct dst_entry *dst = skb_dst(skb);
  56         struct xfrm_state *x = dst->xfrm;
  57         struct net *net = xs_net(x);
  58
  59         if (err <= 0)
  60                 goto resume;
  61
  62         do {
  63                 err = xfrm_skb_check_space(skb);
  64                 if (err) {
  65                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  66                         goto error_nolock;
  67                 }
  68
  69                 skb->mark = xfrm_smark_get(skb->mark, x);
  70
  71                 err = x->outer_mode->output(x, skb);
  72                 if (err) {
  73                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
  74                         goto error_nolock;
  75                 }
  76
  77                 spin_lock_bh(&x->lock);
  78
  79                 if (unlikely(x->km.state != XFRM_STATE_VALID)) {
  80                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
  81                         err = -EINVAL;
  82                         goto error;
  83                 }
  84
  85                 err = xfrm_state_check_expire(x);
  86                 if (err) {
  87                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  88                         goto error;
  89                 }
  90
  91                 err = x->repl->overflow(x, skb);
  92                 if (err) {
  93                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  94                         goto error;
  95                 }
  96
  97                 x->curlft.bytes += skb->len;
  98                 x->curlft.packets++;
  99
 100                 spin_unlock_bh(&x->lock);
 101
 102                 skb_dst_force(skb);
 103                 if (!skb_dst(skb)) {
 104                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 105                         err = -EHOSTUNREACH;
 106                         goto error_nolock;
 107                 }
 108
 109                 if (xfrm_offload(skb)) {
 110                         x->type_offload->encap(x, skb);
 111                 } else {
 112                         /* Inner headers are invalid now. */
 113                         skb->encapsulation = 0;
 114
 115                         err = x->type->output(x, skb);
 116                         if (err == -EINPROGRESS)
 117                                 goto out;
 118                 }
 119
 120 resume:
 121                 if (err) {
 122                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
 123                         goto error_nolock;
 124                 }
 125
 126                 dst = skb_dst_pop(skb);
 127                 if (!dst) {
 128                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 129                         err = -EHOSTUNREACH;
 130                         goto error_nolock;
 131                 }
 132                 skb_dst_set(skb, dst);
 133                 x = dst->xfrm;
 134         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 135
 136         return 0;
 137
 138 error:
 139         spin_unlock_bh(&x->lock);
 140 error_nolock:
 141         kfree_skb(skb);
 142 out:
 143         return err;
 144 }
 145
 146 int xfrm_output_resume(struct sk_buff *skb, int err)
 147 {
 148         struct net *net = xs_net(skb_dst(skb)->xfrm);
 149
 150         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 151                 nf_reset(skb);
 152
 153                 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
 154                 if (unlikely(err != 1))
 155                         goto out;
 156
 157                 if (!skb_dst(skb)->xfrm)
 158                         return dst_output(net, skb->sk, skb);
 159
 160                 err = nf_hook(skb_dst(skb)->ops->family,
 161                               NF_INET_POST_ROUTING, net, skb->sk, skb,
 162                               NULL, skb_dst(skb)->dev, xfrm_output2);
 163                 if (unlikely(err != 1))
 164                         goto out;
 165         }
 166
 167         if (err == -EINPROGRESS)
 168                 err = 0;
 169
 170 out:
 171         return err;
 172 }
 173 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 174
 175 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 176 {
 177         return xfrm_output_resume(skb, 1);
 178 }
 179
 180 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
 181 {
 182         struct sk_buff *segs;
 183
 184         BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 185         BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
 186         segs = skb_gso_segment(skb, 0);
 187         kfree_skb(skb);
 188         if (IS_ERR(segs))
 189                 return PTR_ERR(segs);
 190         if (segs == NULL)
 191                 return -EINVAL;
 192
 193         do {
 194                 struct sk_buff *nskb = segs->next;
 195                 int err;
 196
 197                 skb_mark_not_on_list(segs);
 198                 err = xfrm_output2(net, sk, segs);
 199
 200                 if (unlikely(err)) {
 201                         kfree_skb_list(nskb);
 202                         return err;
 203                 }
 204
 205                 segs = nskb;
 206         } while (segs);
 207
 208         return 0;
 209 }
 210
 211 int xfrm_output(struct sock *sk, struct sk_buff *skb)
 212 {
 213         struct net *net = dev_net(skb_dst(skb)->dev);
 214         struct xfrm_state *x = skb_dst(skb)->xfrm;
 215         int err;
 216
 217         secpath_reset(skb);
 218
 219         if (xfrm_dev_offload_ok(skb, x)) {
 220                 struct sec_path *sp;
 221
 222                 sp = secpath_set(skb);
 223                 if (!sp) {
 224                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 225                         kfree_skb(skb);
 226                         return -ENOMEM;
 227                 }
 228                 skb->encapsulation = 1;
 229
 230                 sp->olen++;
 231                 sp->xvec[sp->len++] = x;
 232                 xfrm_state_hold(x);
 233
 234                 if (skb_is_gso(skb)) {
 235                         skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
 236
 237                         return xfrm_output2(net, sk, skb);
 238                 }
 239
 240                 if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
 241                         goto out;
 242         }
 243
 244         if (skb_is_gso(skb))
 245                 return xfrm_output_gso(net, sk, skb);
 246
 247         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 248                 err = skb_checksum_help(skb);
 249                 if (err) {
 250                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 251                         kfree_skb(skb);
 252                         return err;
 253                 }
 254         }
 255
 256 out:
 257         return xfrm_output2(net, sk, skb);
 258 }
 259 EXPORT_SYMBOL_GPL(xfrm_output);
 260
 261 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 262 {
 263         struct xfrm_mode *inner_mode;
 264         if (x->sel.family == AF_UNSPEC)
 265                 inner_mode = xfrm_ip2inner_mode(x,
 266                                 xfrm_af2proto(skb_dst(skb)->ops->family));
 267         else
 268                 inner_mode = x->inner_mode;
 269
 270         if (inner_mode == NULL)
 271                 return -EAFNOSUPPORT;
 272         return inner_mode->afinfo->extract_output(x, skb);
 273 }
 274 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
 275
 276 void xfrm_local_error(struct sk_buff *skb, int mtu)
 277 {
 278         unsigned int proto;
 279         struct xfrm_state_afinfo *afinfo;
 280
 281         if (skb->protocol == htons(ETH_P_IP))
 282                 proto = AF_INET;
 283         else if (skb->protocol == htons(ETH_P_IPV6))
 284                 proto = AF_INET6;
 285         else
 286                 return;
 287
 288         afinfo = xfrm_state_get_afinfo(proto);
 289         if (afinfo) {
 290                 afinfo->local_error(skb, mtu);
 291                 rcu_read_unlock();
 292         }
 293 }
 294 EXPORT_SYMBOL_GPL(xfrm_local_error);