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                 if (x->props.output_mark)
  70                         skb->mark = x->props.output_mark;
  71
  72                 err = x->outer_mode->output(x, skb);
  73                 if (err) {
  74                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
  75                         goto error_nolock;
  76                 }
  77
  78                 spin_lock_bh(&x->lock);
  79
  80                 if (unlikely(x->km.state != XFRM_STATE_VALID)) {
  81                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
  82                         err = -EINVAL;
  83                         goto error;
  84                 }
  85
  86                 err = xfrm_state_check_expire(x);
  87                 if (err) {
  88                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  89                         goto error;
  90                 }
  91
  92                 err = x->repl->overflow(x, skb);
  93                 if (err) {
  94                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  95                         goto error;
  96                 }
  97
  98                 x->curlft.bytes += skb->len;
  99                 x->curlft.packets++;
 100
 101                 spin_unlock_bh(&x->lock);
 102
 103                 skb_dst_force(skb);
 104                 if (!skb_dst(skb)) {
 105                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 106                         err = -EHOSTUNREACH;
 107                         goto error_nolock;
 108                 }
 109
 110                 if (xfrm_offload(skb)) {
 111                         x->type_offload->encap(x, skb);
 112                 } else {
 113                         /* Inner headers are invalid now. */
 114                         skb->encapsulation = 0;
 115
 116                         err = x->type->output(x, skb);
 117                         if (err == -EINPROGRESS)
 118                                 goto out;
 119                 }
 120
 121 resume:
 122                 if (err) {
 123                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
 124                         goto error_nolock;
 125                 }
 126
 127                 dst = skb_dst_pop(skb);
 128                 if (!dst) {
 129                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 130                         err = -EHOSTUNREACH;
 131                         goto error_nolock;
 132                 }
 133                 skb_dst_set(skb, dst);
 134                 x = dst->xfrm;
 135         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 136
 137         return 0;
 138
 139 error:
 140         spin_unlock_bh(&x->lock);
 141 error_nolock:
 142         kfree_skb(skb);
 143 out:
 144         return err;
 145 }
 146
 147 int xfrm_output_resume(struct sk_buff *skb, int err)
 148 {
 149         struct net *net = xs_net(skb_dst(skb)->xfrm);
 150
 151         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 152                 nf_reset(skb);
 153
 154                 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
 155                 if (unlikely(err != 1))
 156                         goto out;
 157
 158                 if (!skb_dst(skb)->xfrm)
 159                         return dst_output(net, skb->sk, skb);
 160
 161                 err = nf_hook(skb_dst(skb)->ops->family,
 162                               NF_INET_POST_ROUTING, net, skb->sk, skb,
 163                               NULL, skb_dst(skb)->dev, xfrm_output2);
 164                 if (unlikely(err != 1))
 165                         goto out;
 166         }
 167
 168         if (err == -EINPROGRESS)
 169                 err = 0;
 170
 171 out:
 172         return err;
 173 }
 174 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 175
 176 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 177 {
 178         return xfrm_output_resume(skb, 1);
 179 }
 180
 181 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
 182 {
 183         struct sk_buff *segs;
 184
 185         BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 186         BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
 187         segs = skb_gso_segment(skb, 0);
 188         kfree_skb(skb);
 189         if (IS_ERR(segs))
 190                 return PTR_ERR(segs);
 191         if (segs == NULL)
 192                 return -EINVAL;
 193
 194         do {
 195                 struct sk_buff *nskb = segs->next;
 196                 int err;
 197
 198                 segs->next = NULL;
 199                 err = xfrm_output2(net, sk, segs);
 200
 201                 if (unlikely(err)) {
 202                         kfree_skb_list(nskb);
 203                         return err;
 204                 }
 205
 206                 segs = nskb;
 207         } while (segs);
 208
 209         return 0;
 210 }
 211
 212 int xfrm_output(struct sock *sk, struct sk_buff *skb)
 213 {
 214         struct net *net = dev_net(skb_dst(skb)->dev);
 215         struct xfrm_state *x = skb_dst(skb)->xfrm;
 216         int err;
 217
 218         secpath_reset(skb);
 219
 220         if (xfrm_dev_offload_ok(skb, x)) {
 221                 struct sec_path *sp;
 222
 223                 sp = secpath_dup(skb->sp);
 224                 if (!sp) {
 225                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 226                         kfree_skb(skb);
 227                         return -ENOMEM;
 228                 }
 229                 if (skb->sp)
 230                         secpath_put(skb->sp);
 231                 skb->sp = sp;
 232                 skb->encapsulation = 1;
 233
 234                 sp->olen++;
 235                 sp->xvec[skb->sp->len++] = x;
 236                 xfrm_state_hold(x);
 237
 238                 if (skb_is_gso(skb)) {
 239                         skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
 240
 241                         return xfrm_output2(net, sk, skb);
 242                 }
 243
 244                 if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
 245                         goto out;
 246         }
 247
 248         if (skb_is_gso(skb))
 249                 return xfrm_output_gso(net, sk, skb);
 250
 251         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 252                 err = skb_checksum_help(skb);
 253                 if (err) {
 254                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 255                         kfree_skb(skb);
 256                         return err;
 257                 }
 258         }
 259
 260 out:
 261         return xfrm_output2(net, sk, skb);
 262 }
 263 EXPORT_SYMBOL_GPL(xfrm_output);
 264
 265 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 266 {
 267         struct xfrm_mode *inner_mode;
 268         if (x->sel.family == AF_UNSPEC)
 269                 inner_mode = xfrm_ip2inner_mode(x,
 270                                 xfrm_af2proto(skb_dst(skb)->ops->family));
 271         else
 272                 inner_mode = x->inner_mode;
 273
 274         if (inner_mode == NULL)
 275                 return -EAFNOSUPPORT;
 276         return inner_mode->afinfo->extract_output(x, skb);
 277 }
 278 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
 279
 280 void xfrm_local_error(struct sk_buff *skb, int mtu)
 281 {
 282         unsigned int proto;
 283         struct xfrm_state_afinfo *afinfo;
 284
 285         if (skb->protocol == htons(ETH_P_IP))
 286                 proto = AF_INET;
 287         else if (skb->protocol == htons(ETH_P_IPV6))
 288                 proto = AF_INET6;
 289         else
 290                 return;
 291
 292         afinfo = xfrm_state_get_afinfo(proto);
 293         if (afinfo) {
 294                 afinfo->local_error(skb, mtu);
 295                 rcu_read_unlock();
 296         }
 297 }
 298 EXPORT_SYMBOL_GPL(xfrm_local_error);