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 <linux/rcupdate.h>
  10 #include <net/protocol.h>
  11
  12 #include "nf_internals.h"
  13
  14 /*
  15  * A queue handler may be registered for each protocol.  Each is protected by
  16  * long term mutex.  The handler must provide an an outfn() to accept packets
  17  * for queueing and must reinject all packets it receives, no matter what.
  18  */
  19 static struct nf_queue_handler *queue_handler[NPROTO];
  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 void nf_unregister_queue_handlers(struct nf_queue_handler *qh)
  62 {
  63         int pf;
  64
  65         write_lock_bh(&queue_handler_lock);
  66         for (pf = 0; pf < NPROTO; pf++)  {
  67                 if (queue_handler[pf] == qh)
  68                         queue_handler[pf] = NULL;
  69         }
  70         write_unlock_bh(&queue_handler_lock);
  71 }
  72 EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);
  73
  74 /*
  75  * Any packet that leaves via this function must come back
  76  * through nf_reinject().
  77  */
  78 int nf_queue(struct sk_buff **skb,
  79              struct list_head *elem,
  80              int pf, unsigned int hook,
  81              struct net_device *indev,
  82              struct net_device *outdev,
  83              int (*okfn)(struct sk_buff *),
  84              unsigned int queuenum)
  85 {
  86         int status;
  87         struct nf_info *info;
  88 #ifdef CONFIG_BRIDGE_NETFILTER
  89         struct net_device *physindev = NULL;
  90         struct net_device *physoutdev = NULL;
  91 #endif
  92         struct nf_afinfo *afinfo;
  93
  94         /* QUEUE == DROP if noone is waiting, to be safe. */
  95         read_lock(&queue_handler_lock);
  96         if (!queue_handler[pf]) {
  97                 read_unlock(&queue_handler_lock);
  98                 kfree_skb(*skb);
  99                 return 1;
 100         }
 101
 102         afinfo = nf_get_afinfo(pf);
 103         if (!afinfo) {
 104                 read_unlock(&queue_handler_lock);
 105                 kfree_skb(*skb);
 106                 return 1;
 107         }
 108
 109         info = kmalloc(sizeof(*info) + afinfo->route_key_size, GFP_ATOMIC);
 110         if (!info) {
 111                 if (net_ratelimit())
 112                         printk(KERN_ERR "OOM queueing packet %p\n",
 113                                *skb);
 114                 read_unlock(&queue_handler_lock);
 115                 kfree_skb(*skb);
 116                 return 1;
 117         }
 118
 119         *info = (struct nf_info) {
 120                 (struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };
 121
 122         /* If it's going away, ignore hook. */
 123         if (!try_module_get(info->elem->owner)) {
 124                 read_unlock(&queue_handler_lock);
 125                 kfree(info);
 126                 return 0;
 127         }
 128
 129         /* Bump dev refs so they don't vanish while packet is out */
 130         if (indev) dev_hold(indev);
 131         if (outdev) dev_hold(outdev);
 132
 133 #ifdef CONFIG_BRIDGE_NETFILTER
 134         if ((*skb)->nf_bridge) {
 135                 physindev = (*skb)->nf_bridge->physindev;
 136                 if (physindev) dev_hold(physindev);
 137                 physoutdev = (*skb)->nf_bridge->physoutdev;
 138                 if (physoutdev) dev_hold(physoutdev);
 139         }
 140 #endif
 141         afinfo->saveroute(*skb, info);
 142         status = queue_handler[pf]->outfn(*skb, info, queuenum,
 143                                           queue_handler[pf]->data);
 144
 145         read_unlock(&queue_handler_lock);
 146
 147         if (status < 0) {
 148                 /* James M doesn't say fuck enough. */
 149                 if (indev) dev_put(indev);
 150                 if (outdev) dev_put(outdev);
 151 #ifdef CONFIG_BRIDGE_NETFILTER
 152                 if (physindev) dev_put(physindev);
 153                 if (physoutdev) dev_put(physoutdev);
 154 #endif
 155                 module_put(info->elem->owner);
 156                 kfree(info);
 157                 kfree_skb(*skb);
 158
 159                 return 1;
 160         }
 161
 162         return 1;
 163 }
 164
 165 void nf_reinject(struct sk_buff *skb, struct nf_info *info,
 166                  unsigned int verdict)
 167 {
 168         struct list_head *elem = &info->elem->list;
 169         struct list_head *i;
 170         struct nf_afinfo *afinfo;
 171
 172         rcu_read_lock();
 173
 174         /* Release those devices we held, or Alexey will kill me. */
 175         if (info->indev) dev_put(info->indev);
 176         if (info->outdev) dev_put(info->outdev);
 177 #ifdef CONFIG_BRIDGE_NETFILTER
 178         if (skb->nf_bridge) {
 179                 if (skb->nf_bridge->physindev)
 180                         dev_put(skb->nf_bridge->physindev);
 181                 if (skb->nf_bridge->physoutdev)
 182                         dev_put(skb->nf_bridge->physoutdev);
 183         }
 184 #endif
 185
 186         /* Drop reference to owner of hook which queued us. */
 187         module_put(info->elem->owner);
 188
 189         list_for_each_rcu(i, &nf_hooks[info->pf][info->hook]) {
 190                 if (i == elem)
 191                         break;
 192         }
 193
 194         if (i == &nf_hooks[info->pf][info->hook]) {
 195                 /* The module which sent it to userspace is gone. */
 196                 NFDEBUG("%s: module disappeared, dropping packet.\n",
 197                         __FUNCTION__);
 198                 verdict = NF_DROP;
 199         }
 200
 201         /* Continue traversal iff userspace said ok... */
 202         if (verdict == NF_REPEAT) {
 203                 elem = elem->prev;
 204                 verdict = NF_ACCEPT;
 205         }
 206
 207         if (verdict == NF_ACCEPT) {
 208                 afinfo = nf_get_afinfo(info->pf);
 209                 if (!afinfo || afinfo->reroute(&skb, info) < 0)
 210                         verdict = NF_DROP;
 211         }
 212
 213         if (verdict == NF_ACCEPT) {
 214         next_hook:
 215                 verdict = nf_iterate(&nf_hooks[info->pf][info->hook],
 216                                      &skb, info->hook,
 217                                      info->indev, info->outdev, &elem,
 218                                      info->okfn, INT_MIN);
 219         }
 220
 221         switch (verdict & NF_VERDICT_MASK) {
 222         case NF_ACCEPT:
 223                 info->okfn(skb);
 224                 break;
 225
 226         case NF_QUEUE:
 227                 if (!nf_queue(&skb, elem, info->pf, info->hook,
 228                               info->indev, info->outdev, info->okfn,
 229                               verdict >> NF_VERDICT_BITS))
 230                         goto next_hook;
 231                 break;
 232         }
 233         rcu_read_unlock();
 234
 235         if (verdict == NF_DROP)
 236                 kfree_skb(skb);
 237
 238         kfree(info);
 239         return;
 240 }
 241 EXPORT_SYMBOL(nf_reinject);
 242
 243 #ifdef CONFIG_PROC_FS
 244 static void *seq_start(struct seq_file *seq, loff_t *pos)
 245 {
 246         if (*pos >= NPROTO)
 247                 return NULL;
 248
 249         return pos;
 250 }
 251
 252 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 253 {
 254         (*pos)++;
 255
 256         if (*pos >= NPROTO)
 257                 return NULL;
 258
 259         return pos;
 260 }
 261
 262 static void seq_stop(struct seq_file *s, void *v)
 263 {
 264
 265 }
 266
 267 static int seq_show(struct seq_file *s, void *v)
 268 {
 269         int ret;
 270         loff_t *pos = v;
 271         struct nf_queue_handler *qh;
 272
 273         read_lock_bh(&queue_handler_lock);
 274         qh = queue_handler[*pos];
 275         if (!qh)
 276                 ret = seq_printf(s, "%2lld NONE\n", *pos);
 277         else
 278                 ret = seq_printf(s, "%2lld %s\n", *pos, qh->name);
 279         read_unlock_bh(&queue_handler_lock);
 280
 281         return ret;
 282 }
 283
 284 static struct seq_operations nfqueue_seq_ops = {
 285         .start  = seq_start,
 286         .next   = seq_next,
 287         .stop   = seq_stop,
 288         .show   = seq_show,
 289 };
 290
 291 static int nfqueue_open(struct inode *inode, struct file *file)
 292 {
 293         return seq_open(file, &nfqueue_seq_ops);
 294 }
 295
 296 static struct file_operations nfqueue_file_ops = {
 297         .owner   = THIS_MODULE,
 298         .open    = nfqueue_open,
 299         .read    = seq_read,
 300         .llseek  = seq_lseek,
 301         .release = seq_release,
 302 };
 303 #endif /* PROC_FS */
 304
 305
 306 int __init netfilter_queue_init(void)
 307 {
 308 #ifdef CONFIG_PROC_FS
 309         struct proc_dir_entry *pde;
 310
 311         pde = create_proc_entry("nf_queue", S_IRUGO, proc_net_netfilter);
 312         if (!pde)
 313                 return -1;
 314         pde->proc_fops = &nfqueue_file_ops;
 315 #endif
 316         return 0;
 317 }
 318