[NETFILTER]: nf_queue: remove unnecessary hook existance check
[linux-2.6.git] / 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)
142                 dev_hold(indev);
143         if (outdev)
144                 dev_hold(outdev);
145 #ifdef CONFIG_BRIDGE_NETFILTER
146         if (skb->nf_bridge) {
147                 physindev = skb->nf_bridge->physindev;
148                 if (physindev)
149                         dev_hold(physindev);
150                 physoutdev = skb->nf_bridge->physoutdev;
151                 if (physoutdev)
152                         dev_hold(physoutdev);
153         }
154 #endif
155         afinfo->saveroute(skb, info);
156         status = qh->outfn(skb, info, queuenum, qh->data);
157
158         rcu_read_unlock();
159
160         if (status < 0) {
161                 /* James M doesn't say fuck enough. */
162                 if (indev)
163                         dev_put(indev);
164                 if (outdev)
165                         dev_put(outdev);
166 #ifdef CONFIG_BRIDGE_NETFILTER
167                 if (physindev)
168                         dev_put(physindev);
169                 if (physoutdev)
170                         dev_put(physoutdev);
171 #endif
172                 module_put(info->elem->owner);
173                 kfree(info);
174                 kfree_skb(skb);
175
176                 return 1;
177         }
178
179         return 1;
180 }
181
182 int nf_queue(struct sk_buff *skb,
183              struct list_head *elem,
184              int pf, unsigned int hook,
185              struct net_device *indev,
186              struct net_device *outdev,
187              int (*okfn)(struct sk_buff *),
188              unsigned int queuenum)
189 {
190         struct sk_buff *segs;
191
192         if (!skb_is_gso(skb))
193                 return __nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
194                                   queuenum);
195
196         switch (pf) {
197         case AF_INET:
198                 skb->protocol = htons(ETH_P_IP);
199                 break;
200         case AF_INET6:
201                 skb->protocol = htons(ETH_P_IPV6);
202                 break;
203         }
204
205         segs = skb_gso_segment(skb, 0);
206         kfree_skb(skb);
207         if (unlikely(IS_ERR(segs)))
208                 return 1;
209
210         do {
211                 struct sk_buff *nskb = segs->next;
212
213                 segs->next = NULL;
214                 if (!__nf_queue(segs, elem, pf, hook, indev, outdev, okfn,
215                                 queuenum))
216                         kfree_skb(segs);
217                 segs = nskb;
218         } while (segs);
219         return 1;
220 }
221
222 void nf_reinject(struct sk_buff *skb, struct nf_info *info,
223                  unsigned int verdict)
224 {
225         struct list_head *elem = &info->elem->list;
226         struct nf_afinfo *afinfo;
227
228         rcu_read_lock();
229
230         /* Release those devices we held, or Alexey will kill me. */
231         if (info->indev)
232                 dev_put(info->indev);
233         if (info->outdev)
234                 dev_put(info->outdev);
235 #ifdef CONFIG_BRIDGE_NETFILTER
236         if (skb->nf_bridge) {
237                 if (skb->nf_bridge->physindev)
238                         dev_put(skb->nf_bridge->physindev);
239                 if (skb->nf_bridge->physoutdev)
240                         dev_put(skb->nf_bridge->physoutdev);
241         }
242 #endif
243
244         /* Drop reference to owner of hook which queued us. */
245         module_put(info->elem->owner);
246
247         /* Continue traversal iff userspace said ok... */
248         if (verdict == NF_REPEAT) {
249                 elem = elem->prev;
250                 verdict = NF_ACCEPT;
251         }
252
253         if (verdict == NF_ACCEPT) {
254                 afinfo = nf_get_afinfo(info->pf);
255                 if (!afinfo || afinfo->reroute(skb, info) < 0)
256                         verdict = NF_DROP;
257         }
258
259         if (verdict == NF_ACCEPT) {
260         next_hook:
261                 verdict = nf_iterate(&nf_hooks[info->pf][info->hook],
262                                      skb, info->hook,
263                                      info->indev, info->outdev, &elem,
264                                      info->okfn, INT_MIN);
265         }
266
267         switch (verdict & NF_VERDICT_MASK) {
268         case NF_ACCEPT:
269         case NF_STOP:
270                 info->okfn(skb);
271         case NF_STOLEN:
272                 break;
273         case NF_QUEUE:
274                 if (!__nf_queue(skb, elem, info->pf, info->hook,
275                                 info->indev, info->outdev, info->okfn,
276                                 verdict >> NF_VERDICT_BITS))
277                         goto next_hook;
278                 break;
279         default:
280                 kfree_skb(skb);
281         }
282         rcu_read_unlock();
283         kfree(info);
284         return;
285 }
286 EXPORT_SYMBOL(nf_reinject);
287
288 #ifdef CONFIG_PROC_FS
289 static void *seq_start(struct seq_file *seq, loff_t *pos)
290 {
291         if (*pos >= NPROTO)
292                 return NULL;
293
294         return pos;
295 }
296
297 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
298 {
299         (*pos)++;
300
301         if (*pos >= NPROTO)
302                 return NULL;
303
304         return pos;
305 }
306
307 static void seq_stop(struct seq_file *s, void *v)
308 {
309
310 }
311
312 static int seq_show(struct seq_file *s, void *v)
313 {
314         int ret;
315         loff_t *pos = v;
316         struct nf_queue_handler *qh;
317
318         rcu_read_lock();
319         qh = rcu_dereference(queue_handler[*pos]);
320         if (!qh)
321                 ret = seq_printf(s, "%2lld NONE\n", *pos);
322         else
323                 ret = seq_printf(s, "%2lld %s\n", *pos, qh->name);
324         rcu_read_unlock();
325
326         return ret;
327 }
328
329 static const struct seq_operations nfqueue_seq_ops = {
330         .start  = seq_start,
331         .next   = seq_next,
332         .stop   = seq_stop,
333         .show   = seq_show,
334 };
335
336 static int nfqueue_open(struct inode *inode, struct file *file)
337 {
338         return seq_open(file, &nfqueue_seq_ops);
339 }
340
341 static const struct file_operations nfqueue_file_ops = {
342         .owner   = THIS_MODULE,
343         .open    = nfqueue_open,
344         .read    = seq_read,
345         .llseek  = seq_lseek,
346         .release = seq_release,
347 };
348 #endif /* PROC_FS */
349
350
351 int __init netfilter_queue_init(void)
352 {
353 #ifdef CONFIG_PROC_FS
354         struct proc_dir_entry *pde;
355
356         pde = create_proc_entry("nf_queue", S_IRUGO, proc_net_netfilter);
357         if (!pde)
358                 return -1;
359         pde->proc_fops = &nfqueue_file_ops;
360 #endif
361         return 0;
362 }
363