netfilter: nfnetlink_queue: do not free skb on error
[linux-2.6.git] / net / netfilter / nf_queue.c
1 #include <linux/kernel.h>
2 #include <linux/slab.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 #include <net/netfilter/nf_queue.h>
12 #include <net/dst.h>
13
14 #include "nf_internals.h"
15
16 /*
17  * A queue handler may be registered for each protocol.  Each is protected by
18  * long term mutex.  The handler must provide an an outfn() to accept packets
19  * for queueing and must reinject all packets it receives, no matter what.
20  */
21 static const struct nf_queue_handler __rcu *queue_handler[NFPROTO_NUMPROTO] __read_mostly;
22
23 static DEFINE_MUTEX(queue_handler_mutex);
24
25 /* return EBUSY when somebody else is registered, return EEXIST if the
26  * same handler is registered, return 0 in case of success. */
27 int nf_register_queue_handler(u_int8_t pf, const struct nf_queue_handler *qh)
28 {
29         int ret;
30         const struct nf_queue_handler *old;
31
32         if (pf >= ARRAY_SIZE(queue_handler))
33                 return -EINVAL;
34
35         mutex_lock(&queue_handler_mutex);
36         old = rcu_dereference_protected(queue_handler[pf],
37                                         lockdep_is_held(&queue_handler_mutex));
38         if (old == qh)
39                 ret = -EEXIST;
40         else if (old)
41                 ret = -EBUSY;
42         else {
43                 rcu_assign_pointer(queue_handler[pf], qh);
44                 ret = 0;
45         }
46         mutex_unlock(&queue_handler_mutex);
47
48         return ret;
49 }
50 EXPORT_SYMBOL(nf_register_queue_handler);
51
52 /* The caller must flush their queue before this */
53 int nf_unregister_queue_handler(u_int8_t pf, const struct nf_queue_handler *qh)
54 {
55         const struct nf_queue_handler *old;
56
57         if (pf >= ARRAY_SIZE(queue_handler))
58                 return -EINVAL;
59
60         mutex_lock(&queue_handler_mutex);
61         old = rcu_dereference_protected(queue_handler[pf],
62                                         lockdep_is_held(&queue_handler_mutex));
63         if (old && old != qh) {
64                 mutex_unlock(&queue_handler_mutex);
65                 return -EINVAL;
66         }
67
68         rcu_assign_pointer(queue_handler[pf], NULL);
69         mutex_unlock(&queue_handler_mutex);
70
71         synchronize_rcu();
72
73         return 0;
74 }
75 EXPORT_SYMBOL(nf_unregister_queue_handler);
76
77 void nf_unregister_queue_handlers(const struct nf_queue_handler *qh)
78 {
79         u_int8_t pf;
80
81         mutex_lock(&queue_handler_mutex);
82         for (pf = 0; pf < ARRAY_SIZE(queue_handler); pf++)  {
83                 if (rcu_dereference_protected(
84                                 queue_handler[pf],
85                                 lockdep_is_held(&queue_handler_mutex)
86                                 ) == qh)
87                         rcu_assign_pointer(queue_handler[pf], NULL);
88         }
89         mutex_unlock(&queue_handler_mutex);
90
91         synchronize_rcu();
92 }
93 EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);
94
95 static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
96 {
97         /* Release those devices we held, or Alexey will kill me. */
98         if (entry->indev)
99                 dev_put(entry->indev);
100         if (entry->outdev)
101                 dev_put(entry->outdev);
102 #ifdef CONFIG_BRIDGE_NETFILTER
103         if (entry->skb->nf_bridge) {
104                 struct nf_bridge_info *nf_bridge = entry->skb->nf_bridge;
105
106                 if (nf_bridge->physindev)
107                         dev_put(nf_bridge->physindev);
108                 if (nf_bridge->physoutdev)
109                         dev_put(nf_bridge->physoutdev);
110         }
111 #endif
112         /* Drop reference to owner of hook which queued us. */
113         module_put(entry->elem->owner);
114 }
115
116 /*
117  * Any packet that leaves via this function must come back
118  * through nf_reinject().
119  */
120 static int __nf_queue(struct sk_buff *skb,
121                       struct list_head *elem,
122                       u_int8_t pf, unsigned int hook,
123                       struct net_device *indev,
124                       struct net_device *outdev,
125                       int (*okfn)(struct sk_buff *),
126                       unsigned int queuenum)
127 {
128         int status = -ENOENT;
129         struct nf_queue_entry *entry = NULL;
130 #ifdef CONFIG_BRIDGE_NETFILTER
131         struct net_device *physindev;
132         struct net_device *physoutdev;
133 #endif
134         const struct nf_afinfo *afinfo;
135         const struct nf_queue_handler *qh;
136
137         /* QUEUE == DROP if noone is waiting, to be safe. */
138         rcu_read_lock();
139
140         qh = rcu_dereference(queue_handler[pf]);
141         if (!qh)
142                 goto err_unlock;
143
144         afinfo = nf_get_afinfo(pf);
145         if (!afinfo)
146                 goto err_unlock;
147
148         entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC);
149         if (!entry) {
150                 status = -ENOMEM;
151                 goto err_unlock;
152         }
153
154         *entry = (struct nf_queue_entry) {
155                 .skb    = skb,
156                 .elem   = list_entry(elem, struct nf_hook_ops, list),
157                 .pf     = pf,
158                 .hook   = hook,
159                 .indev  = indev,
160                 .outdev = outdev,
161                 .okfn   = okfn,
162         };
163
164         /* If it's going away, ignore hook. */
165         if (!try_module_get(entry->elem->owner)) {
166                 status = -ECANCELED;
167                 goto err_unlock;
168         }
169         /* Bump dev refs so they don't vanish while packet is out */
170         if (indev)
171                 dev_hold(indev);
172         if (outdev)
173                 dev_hold(outdev);
174 #ifdef CONFIG_BRIDGE_NETFILTER
175         if (skb->nf_bridge) {
176                 physindev = skb->nf_bridge->physindev;
177                 if (physindev)
178                         dev_hold(physindev);
179                 physoutdev = skb->nf_bridge->physoutdev;
180                 if (physoutdev)
181                         dev_hold(physoutdev);
182         }
183 #endif
184         skb_dst_force(skb);
185         afinfo->saveroute(skb, entry);
186         status = qh->outfn(entry, queuenum);
187
188         rcu_read_unlock();
189
190         if (status < 0) {
191                 nf_queue_entry_release_refs(entry);
192                 goto err;
193         }
194
195         return 0;
196
197 err_unlock:
198         rcu_read_unlock();
199 err:
200         kfree(entry);
201         return status;
202 }
203
204 int nf_queue(struct sk_buff *skb,
205              struct list_head *elem,
206              u_int8_t pf, unsigned int hook,
207              struct net_device *indev,
208              struct net_device *outdev,
209              int (*okfn)(struct sk_buff *),
210              unsigned int queuenum)
211 {
212         struct sk_buff *segs;
213         int err;
214         unsigned int queued;
215
216         if (!skb_is_gso(skb))
217                 return __nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
218                                   queuenum);
219
220         switch (pf) {
221         case NFPROTO_IPV4:
222                 skb->protocol = htons(ETH_P_IP);
223                 break;
224         case NFPROTO_IPV6:
225                 skb->protocol = htons(ETH_P_IPV6);
226                 break;
227         }
228
229         segs = skb_gso_segment(skb, 0);
230         /* Does not use PTR_ERR to limit the number of error codes that can be
231          * returned by nf_queue.  For instance, callers rely on -ECANCELED to mean
232          * 'ignore this hook'.
233          */
234         if (IS_ERR(segs))
235                 return -EINVAL;
236
237         queued = 0;
238         err = 0;
239         do {
240                 struct sk_buff *nskb = segs->next;
241
242                 segs->next = NULL;
243                 if (err == 0)
244                         err = __nf_queue(segs, elem, pf, hook, indev,
245                                            outdev, okfn, queuenum);
246                 if (err == 0)
247                         queued++;
248                 else
249                         kfree_skb(segs);
250                 segs = nskb;
251         } while (segs);
252
253         /* also free orig skb if only some segments were queued */
254         if (unlikely(err && queued))
255                 err = 0;
256         if (err == 0)
257                 kfree_skb(skb);
258         return err;
259 }
260
261 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
262 {
263         struct sk_buff *skb = entry->skb;
264         struct list_head *elem = &entry->elem->list;
265         const struct nf_afinfo *afinfo;
266         int err;
267
268         rcu_read_lock();
269
270         nf_queue_entry_release_refs(entry);
271
272         /* Continue traversal iff userspace said ok... */
273         if (verdict == NF_REPEAT) {
274                 elem = elem->prev;
275                 verdict = NF_ACCEPT;
276         }
277
278         if (verdict == NF_ACCEPT) {
279                 afinfo = nf_get_afinfo(entry->pf);
280                 if (!afinfo || afinfo->reroute(skb, entry) < 0)
281                         verdict = NF_DROP;
282         }
283
284         if (verdict == NF_ACCEPT) {
285         next_hook:
286                 verdict = nf_iterate(&nf_hooks[entry->pf][entry->hook],
287                                      skb, entry->hook,
288                                      entry->indev, entry->outdev, &elem,
289                                      entry->okfn, INT_MIN);
290         }
291
292         switch (verdict & NF_VERDICT_MASK) {
293         case NF_ACCEPT:
294         case NF_STOP:
295                 local_bh_disable();
296                 entry->okfn(skb);
297                 local_bh_enable();
298                 break;
299         case NF_QUEUE:
300                 err = __nf_queue(skb, elem, entry->pf, entry->hook,
301                                  entry->indev, entry->outdev, entry->okfn,
302                                  verdict >> NF_VERDICT_BITS);
303                 if (err < 0) {
304                         if (err == -ECANCELED)
305                                 goto next_hook;
306                         kfree_skb(skb);
307                 }
308                 break;
309         case NF_STOLEN:
310         default:
311                 kfree_skb(skb);
312         }
313         rcu_read_unlock();
314         kfree(entry);
315 }
316 EXPORT_SYMBOL(nf_reinject);
317
318 #ifdef CONFIG_PROC_FS
319 static void *seq_start(struct seq_file *seq, loff_t *pos)
320 {
321         if (*pos >= ARRAY_SIZE(queue_handler))
322                 return NULL;
323
324         return pos;
325 }
326
327 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
328 {
329         (*pos)++;
330
331         if (*pos >= ARRAY_SIZE(queue_handler))
332                 return NULL;
333
334         return pos;
335 }
336
337 static void seq_stop(struct seq_file *s, void *v)
338 {
339
340 }
341
342 static int seq_show(struct seq_file *s, void *v)
343 {
344         int ret;
345         loff_t *pos = v;
346         const struct nf_queue_handler *qh;
347
348         rcu_read_lock();
349         qh = rcu_dereference(queue_handler[*pos]);
350         if (!qh)
351                 ret = seq_printf(s, "%2lld NONE\n", *pos);
352         else
353                 ret = seq_printf(s, "%2lld %s\n", *pos, qh->name);
354         rcu_read_unlock();
355
356         return ret;
357 }
358
359 static const struct seq_operations nfqueue_seq_ops = {
360         .start  = seq_start,
361         .next   = seq_next,
362         .stop   = seq_stop,
363         .show   = seq_show,
364 };
365
366 static int nfqueue_open(struct inode *inode, struct file *file)
367 {
368         return seq_open(file, &nfqueue_seq_ops);
369 }
370
371 static const struct file_operations nfqueue_file_ops = {
372         .owner   = THIS_MODULE,
373         .open    = nfqueue_open,
374         .read    = seq_read,
375         .llseek  = seq_lseek,
376         .release = seq_release,
377 };
378 #endif /* PROC_FS */
379
380
381 int __init netfilter_queue_init(void)
382 {
383 #ifdef CONFIG_PROC_FS
384         if (!proc_create("nf_queue", S_IRUGO,
385                          proc_net_netfilter, &nfqueue_file_ops))
386                 return -1;
387 #endif
388         return 0;
389 }
390