net/netfilter/nf_queue.c

   1 #include <linux/kernel.h>
   2 #include <linux/init.h>
   3 #include <linux/module.h>
   4 #include <linux/proc_fs.h>
   5 #include <linux/skbuff.h>
   6 #include <linux/netfilter.h>
   7 #include <linux/seq_file.h>
   8 #include <linux/rcupdate.h>
   9 #include <net/protocol.h>
  10
  11 #include "nf_internals.h"
  12
  13 /*
  14  * A queue handler may be registered for each protocol.  Each is protected by
  15  * long term mutex.  The handler must provide an an outfn() to accept packets
  16  * for queueing and must reinject all packets it receives, no matter what.
  17  */
  18 static struct nf_queue_handler *queue_handler[NPROTO];
  19
  20 static DEFINE_MUTEX(queue_handler_mutex);
  21
  22 /* return EBUSY when somebody else is registered, return EEXIST if the
  23  * same handler is registered, return 0 in case of success. */
  24 int nf_register_queue_handler(int pf, struct nf_queue_handler *qh)
  25 {
  26         int ret;
  27
  28         if (pf >= NPROTO)
  29                 return -EINVAL;
  30
  31         mutex_lock(&queue_handler_mutex);
  32         if (queue_handler[pf] == qh)
  33                 ret = -EEXIST;
  34         else if (queue_handler[pf])
  35                 ret = -EBUSY;
  36         else {
  37                 rcu_assign_pointer(queue_handler[pf], qh);
  38                 ret = 0;
  39         }
  40         mutex_unlock(&queue_handler_mutex);
  41
  42         return ret;
  43 }
  44 EXPORT_SYMBOL(nf_register_queue_handler);
  45
  46 /* The caller must flush their queue before this */
  47 int nf_unregister_queue_handler(int pf, struct nf_queue_handler *qh)
  48 {
  49         if (pf >= NPROTO)
  50                 return -EINVAL;
  51
  52         mutex_lock(&queue_handler_mutex);
  53         if (queue_handler[pf] != qh) {
  54                 mutex_unlock(&queue_handler_mutex);
  55                 return -EINVAL;
  56         }
  57
  58         rcu_assign_pointer(queue_handler[pf], NULL);
  59         mutex_unlock(&queue_handler_mutex);
  60
  61         synchronize_rcu();
  62
  63         return 0;
  64 }
  65 EXPORT_SYMBOL(nf_unregister_queue_handler);
  66
  67 void nf_unregister_queue_handlers(struct nf_queue_handler *qh)
  68 {
  69         int pf;
  70
  71         mutex_lock(&queue_handler_mutex);
  72         for (pf = 0; pf < NPROTO; pf++)  {
  73                 if (queue_handler[pf] == qh)
  74                         rcu_assign_pointer(queue_handler[pf], NULL);
  75         }
  76         mutex_unlock(&queue_handler_mutex);
  77
  78         synchronize_rcu();
  79 }
  80 EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);
  81
  82 /*
  83  * Any packet that leaves via this function must come back
  84  * through nf_reinject().
  85  */
  86 static int __nf_queue(struct sk_buff *skb,
  87                       struct list_head *elem,
  88                       int pf, unsigned int hook,
  89                       struct net_device *indev,
  90                       struct net_device *outdev,
  91                       int (*okfn)(struct sk_buff *),
  92                       unsigned int queuenum)
  93 {
  94         int status;
  95         struct nf_info *info;
  96 #ifdef CONFIG_BRIDGE_NETFILTER
  97         struct net_device *physindev = NULL;
  98         struct net_device *physoutdev = NULL;
  99 #endif
 100         struct nf_afinfo *afinfo;
 101         struct nf_queue_handler *qh;
 102
 103         /* QUEUE == DROP if noone is waiting, to be safe. */
 104         rcu_read_lock();
 105
 106         qh = rcu_dereference(queue_handler[pf]);
 107         if (!qh) {
 108                 rcu_read_unlock();
 109                 kfree_skb(skb);
 110                 return 1;
 111         }
 112
 113         afinfo = nf_get_afinfo(pf);
 114         if (!afinfo) {
 115                 rcu_read_unlock();
 116                 kfree_skb(skb);
 117                 return 1;
 118         }
 119
 120         info = kmalloc(sizeof(*info) + afinfo->route_key_size, GFP_ATOMIC);
 121         if (!info) {
 122                 if (net_ratelimit())
 123                         printk(KERN_ERR "OOM queueing packet %p\n",
 124                                skb);
 125                 rcu_read_unlock();
 126                 kfree_skb(skb);
 127                 return 1;
 128         }
 129
 130         *info = (struct nf_info) {
 131                 (struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };
 132
 133         /* If it's going away, ignore hook. */
 134         if (!try_module_get(info->elem->owner)) {
 135                 rcu_read_unlock();
 136                 kfree(info);
 137                 return 0;
 138         }
 139
 140         /* Bump dev refs so they don't vanish while packet is out */
 141         if (indev) dev_hold(indev);
 142         if (outdev) dev_hold(outdev);
 143
 144 #ifdef CONFIG_BRIDGE_NETFILTER
 145         if (skb->nf_bridge) {
 146                 physindev = skb->nf_bridge->physindev;
 147                 if (physindev) dev_hold(physindev);
 148                 physoutdev = skb->nf_bridge->physoutdev;
 149                 if (physoutdev) dev_hold(physoutdev);
 150         }
 151 #endif
 152         afinfo->saveroute(skb, info);
 153         status = qh->outfn(skb, info, queuenum, qh->data);
 154
 155         rcu_read_unlock();
 156
 157         if (status < 0) {
 158                 /* James M doesn't say fuck enough. */
 159                 if (indev) dev_put(indev);
 160                 if (outdev) dev_put(outdev);
 161 #ifdef CONFIG_BRIDGE_NETFILTER
 162                 if (physindev) dev_put(physindev);
 163                 if (physoutdev) dev_put(physoutdev);
 164 #endif
 165                 module_put(info->elem->owner);
 166                 kfree(info);
 167                 kfree_skb(skb);
 168
 169                 return 1;
 170         }
 171
 172         return 1;
 173 }
 174
 175 int nf_queue(struct sk_buff *skb,
 176              struct list_head *elem,
 177              int pf, unsigned int hook,
 178              struct net_device *indev,
 179              struct net_device *outdev,
 180              int (*okfn)(struct sk_buff *),
 181              unsigned int queuenum)
 182 {
 183         struct sk_buff *segs;
 184
 185         if (!skb_is_gso(skb))
 186                 return __nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
 187                                   queuenum);
 188
 189         switch (pf) {
 190         case AF_INET:
 191                 skb->protocol = htons(ETH_P_IP);
 192                 break;
 193         case AF_INET6:
 194                 skb->protocol = htons(ETH_P_IPV6);
 195                 break;
 196         }
 197
 198         segs = skb_gso_segment(skb, 0);
 199         kfree_skb(skb);
 200         if (unlikely(IS_ERR(segs)))
 201                 return 1;
 202
 203         do {
 204                 struct sk_buff *nskb = segs->next;
 205
 206                 segs->next = NULL;
 207                 if (!__nf_queue(segs, elem, pf, hook, indev, outdev, okfn,
 208                                 queuenum))
 209                         kfree_skb(segs);
 210                 segs = nskb;
 211         } while (segs);
 212         return 1;
 213 }
 214
 215 void nf_reinject(struct sk_buff *skb, struct nf_info *info,
 216                  unsigned int verdict)
 217 {
 218         struct list_head *elem = &info->elem->list;
 219         struct list_head *i;
 220         struct nf_afinfo *afinfo;
 221
 222         rcu_read_lock();
 223
 224         /* Release those devices we held, or Alexey will kill me. */
 225         if (info->indev) dev_put(info->indev);
 226         if (info->outdev) dev_put(info->outdev);
 227 #ifdef CONFIG_BRIDGE_NETFILTER
 228         if (skb->nf_bridge) {
 229                 if (skb->nf_bridge->physindev)
 230                         dev_put(skb->nf_bridge->physindev);
 231                 if (skb->nf_bridge->physoutdev)
 232                         dev_put(skb->nf_bridge->physoutdev);
 233         }
 234 #endif
 235
 236         /* Drop reference to owner of hook which queued us. */
 237         module_put(info->elem->owner);
 238
 239         list_for_each_rcu(i, &nf_hooks[info->pf][info->hook]) {
 240                 if (i == elem)
 241                         break;
 242         }
 243
 244         if (i == &nf_hooks[info->pf][info->hook]) {
 245                 /* The module which sent it to userspace is gone. */
 246                 NFDEBUG("%s: module disappeared, dropping packet.\n",
 247                         __FUNCTION__);
 248                 verdict = NF_DROP;
 249         }
 250
 251         /* Continue traversal iff userspace said ok... */
 252         if (verdict == NF_REPEAT) {
 253                 elem = elem->prev;
 254                 verdict = NF_ACCEPT;
 255         }
 256
 257         if (verdict == NF_ACCEPT) {
 258                 afinfo = nf_get_afinfo(info->pf);
 259                 if (!afinfo || afinfo->reroute(&skb, info) < 0)
 260                         verdict = NF_DROP;
 261         }
 262
 263         if (verdict == NF_ACCEPT) {
 264         next_hook:
 265                 verdict = nf_iterate(&nf_hooks[info->pf][info->hook],
 266                                      &skb, info->hook,
 267                                      info->indev, info->outdev, &elem,
 268                                      info->okfn, INT_MIN);
 269         }
 270
 271         switch (verdict & NF_VERDICT_MASK) {
 272         case NF_ACCEPT:
 273         case NF_STOP:
 274                 info->okfn(skb);
 275         case NF_STOLEN:
 276                 break;
 277         case NF_QUEUE:
 278                 if (!__nf_queue(skb, elem, info->pf, info->hook,
 279                                 info->indev, info->outdev, info->okfn,
 280                                 verdict >> NF_VERDICT_BITS))
 281                         goto next_hook;
 282                 break;
 283         default:
 284                 kfree_skb(skb);
 285         }
 286         rcu_read_unlock();
 287         kfree(info);
 288         return;
 289 }
 290 EXPORT_SYMBOL(nf_reinject);
 291
 292 #ifdef CONFIG_PROC_FS
 293 static void *seq_start(struct seq_file *seq, loff_t *pos)
 294 {
 295         if (*pos >= NPROTO)
 296                 return NULL;
 297
 298         return pos;
 299 }
 300
 301 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 302 {
 303         (*pos)++;
 304
 305         if (*pos >= NPROTO)
 306                 return NULL;
 307
 308         return pos;
 309 }
 310
 311 static void seq_stop(struct seq_file *s, void *v)
 312 {
 313
 314 }
 315
 316 static int seq_show(struct seq_file *s, void *v)
 317 {
 318         int ret;
 319         loff_t *pos = v;
 320         struct nf_queue_handler *qh;
 321
 322         rcu_read_lock();
 323         qh = rcu_dereference(queue_handler[*pos]);
 324         if (!qh)
 325                 ret = seq_printf(s, "%2lld NONE\n", *pos);
 326         else
 327                 ret = seq_printf(s, "%2lld %s\n", *pos, qh->name);
 328         rcu_read_unlock();
 329
 330         return ret;
 331 }
 332
 333 static const struct seq_operations nfqueue_seq_ops = {
 334         .start  = seq_start,
 335         .next   = seq_next,
 336         .stop   = seq_stop,
 337         .show   = seq_show,
 338 };
 339
 340 static int nfqueue_open(struct inode *inode, struct file *file)
 341 {
 342         return seq_open(file, &nfqueue_seq_ops);
 343 }
 344
 345 static const struct file_operations nfqueue_file_ops = {
 346         .owner   = THIS_MODULE,
 347         .open    = nfqueue_open,
 348         .read    = seq_read,
 349         .llseek  = seq_lseek,
 350         .release = seq_release,
 351 };
 352 #endif /* PROC_FS */
 353
 354
 355 int __init netfilter_queue_init(void)
 356 {
 357 #ifdef CONFIG_PROC_FS
 358         struct proc_dir_entry *pde;
 359
 360         pde = create_proc_entry("nf_queue", S_IRUGO, proc_net_netfilter);
 361         if (!pde)
 362                 return -1;
 363         pde->proc_fops = &nfqueue_file_ops;
 364 #endif
 365         return 0;
 366 }
 367