net/netfilter/nf_queue.c

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