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