summaryrefslogtreecommitdiff
path: root/net/netfilter/nf_queue.c
blob: d10d552d9c40e2911aaf8cf796125c4212bdabff (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <linux/seq_file.h>
#include <net/protocol.h>

#include "nf_internals.h"

/* 
 * A queue handler may be registered for each protocol.  Each is protected by
 * long term mutex.  The handler must provide an an outfn() to accept packets
 * for queueing and must reinject all packets it receives, no matter what.
 */
static struct nf_queue_handler *queue_handler[NPROTO];
static struct nf_queue_rerouter *queue_rerouter;

static DEFINE_RWLOCK(queue_handler_lock);

/* return EBUSY when somebody else is registered, return EEXIST if the
 * same handler is registered, return 0 in case of success. */
int nf_register_queue_handler(int pf, struct nf_queue_handler *qh)
{      
	int ret;

	if (pf >= NPROTO)
		return -EINVAL;

	write_lock_bh(&queue_handler_lock);
	if (queue_handler[pf] == qh)
		ret = -EEXIST;
	else if (queue_handler[pf])
		ret = -EBUSY;
	else {
		queue_handler[pf] = qh;
		ret = 0;
	}
	write_unlock_bh(&queue_handler_lock);

	return ret;
}
EXPORT_SYMBOL(nf_register_queue_handler);

/* The caller must flush their queue before this */
int nf_unregister_queue_handler(int pf)
{
	if (pf >= NPROTO)
		return -EINVAL;

	write_lock_bh(&queue_handler_lock);
	queue_handler[pf] = NULL;
	write_unlock_bh(&queue_handler_lock);
	
	return 0;
}
EXPORT_SYMBOL(nf_unregister_queue_handler);

int nf_register_queue_rerouter(int pf, struct nf_queue_rerouter *rer)
{
	if (pf >= NPROTO)
		return -EINVAL;

	write_lock_bh(&queue_handler_lock);
	memcpy(&queue_rerouter[pf], rer, sizeof(queue_rerouter[pf]));
	write_unlock_bh(&queue_handler_lock);

	return 0;
}
EXPORT_SYMBOL_GPL(nf_register_queue_rerouter);

int nf_unregister_queue_rerouter(int pf)
{
	if (pf >= NPROTO)
		return -EINVAL;

	write_lock_bh(&queue_handler_lock);
	memset(&queue_rerouter[pf], 0, sizeof(queue_rerouter[pf]));
	write_unlock_bh(&queue_handler_lock);
	return 0;
}
EXPORT_SYMBOL_GPL(nf_unregister_queue_rerouter);

void nf_unregister_queue_handlers(struct nf_queue_handler *qh)
{
	int pf;

	write_lock_bh(&queue_handler_lock);
	for (pf = 0; pf < NPROTO; pf++)  {
		if (queue_handler[pf] == qh)
			queue_handler[pf] = NULL;
	}
	write_unlock_bh(&queue_handler_lock);
}
EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);

/* 
 * Any packet that leaves via this function must come back 
 * through nf_reinject().
 */
int nf_queue(struct sk_buff **skb, 
	     struct list_head *elem, 
	     int pf, unsigned int hook,
	     struct net_device *indev,
	     struct net_device *outdev,
	     int (*okfn)(struct sk_buff *),
	     unsigned int queuenum)
{
	int status;
	struct nf_info *info;
#ifdef CONFIG_BRIDGE_NETFILTER
	struct net_device *physindev = NULL;
	struct net_device *physoutdev = NULL;
#endif

	/* QUEUE == DROP if noone is waiting, to be safe. */
	read_lock(&queue_handler_lock);
	if (!queue_handler[pf]->outfn) {
		read_unlock(&queue_handler_lock);
		kfree_skb(*skb);
		return 1;
	}

	info = kmalloc(sizeof(*info)+queue_rerouter[pf].rer_size, GFP_ATOMIC);
	if (!info) {
		if (net_ratelimit())
			printk(KERN_ERR "OOM queueing packet %p\n",
			       *skb);
		read_unlock(&queue_handler_lock);
		kfree_skb(*skb);
		return 1;
	}

	*info = (struct nf_info) { 
		(struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };

	/* If it's going away, ignore hook. */
	if (!try_module_get(info->elem->owner)) {
		read_unlock(&queue_handler_lock);
		kfree(info);
		return 0;
	}

	/* Bump dev refs so they don't vanish while packet is out */
	if (indev) dev_hold(indev);
	if (outdev) dev_hold(outdev);

#ifdef CONFIG_BRIDGE_NETFILTER
	if ((*skb)->nf_bridge) {
		physindev = (*skb)->nf_bridge->physindev;
		if (physindev) dev_hold(physindev);
		physoutdev = (*skb)->nf_bridge->physoutdev;
		if (physoutdev) dev_hold(physoutdev);
	}
#endif
	if (queue_rerouter[pf].save)
		queue_rerouter[pf].save(*skb, info);

	status = queue_handler[pf]->outfn(*skb, info, queuenum,
					  queue_handler[pf]->data);

	if (status >= 0 && queue_rerouter[pf].reroute)
		status = queue_rerouter[pf].reroute(skb, info);

	read_unlock(&queue_handler_lock);

	if (status < 0) {
		/* James M doesn't say fuck enough. */
		if (indev) dev_put(indev);
		if (outdev) dev_put(outdev);
#ifdef CONFIG_BRIDGE_NETFILTER
		if (physindev) dev_put(physindev);
		if (physoutdev) dev_put(physoutdev);
#endif
		module_put(info->elem->owner);
		kfree(info);
		kfree_skb(*skb);

		return 1;
	}

	return 1;
}

void nf_reinject(struct sk_buff *skb, struct nf_info *info,
		 unsigned int verdict)
{
	struct list_head *elem = &info->elem->list;
	struct list_head *i;

	rcu_read_lock();

	/* Release those devices we held, or Alexey will kill me. */
	if (info->indev) dev_put(info->indev);
	if (info->outdev) dev_put(info->outdev);
#ifdef CONFIG_BRIDGE_NETFILTER
	if (skb->nf_bridge) {
		if (skb->nf_bridge->physindev)
			dev_put(skb->nf_bridge->physindev);
		if (skb->nf_bridge->physoutdev)
			dev_put(skb->nf_bridge->physoutdev);
	}
#endif

	/* Drop reference to owner of hook which queued us. */
	module_put(info->elem->owner);

	list_for_each_rcu(i, &nf_hooks[info->pf][info->hook]) {
		if (i == elem) 
  			break;
  	}
  
	if (elem == &nf_hooks[info->pf][info->hook]) {
		/* The module which sent it to userspace is gone. */
		NFDEBUG("%s: module disappeared, dropping packet.\n",
			__FUNCTION__);
		verdict = NF_DROP;
	}

	/* Continue traversal iff userspace said ok... */
	if (verdict == NF_REPEAT) {
		elem = elem->prev;
		verdict = NF_ACCEPT;
	}

	if (verdict == NF_ACCEPT) {
	next_hook:
		verdict = nf_iterate(&nf_hooks[info->pf][info->hook],
				     &skb, info->hook, 
				     info->indev, info->outdev, &elem,
				     info->okfn, INT_MIN);
	}

	switch (verdict & NF_VERDICT_MASK) {
	case NF_ACCEPT:
		info->okfn(skb);
		break;

	case NF_QUEUE:
		if (!nf_queue(&skb, elem, info->pf, info->hook, 
			      info->indev, info->outdev, info->okfn,
			      verdict >> NF_VERDICT_BITS))
			goto next_hook;
		break;
	}
	rcu_read_unlock();

	if (verdict == NF_DROP)
		kfree_skb(skb);

	kfree(info);
	return;
}
EXPORT_SYMBOL(nf_reinject);

#ifdef CONFIG_PROC_FS
static void *seq_start(struct seq_file *seq, loff_t *pos)
{
	if (*pos >= NPROTO)
		return NULL;

	return pos;
}

static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
{
	(*pos)++;

	if (*pos >= NPROTO)
		return NULL;

	return pos;
}

static void seq_stop(struct seq_file *s, void *v)
{

}

static int seq_show(struct seq_file *s, void *v)
{
	int ret;
	loff_t *pos = v;
	struct nf_queue_handler *qh;

	read_lock_bh(&queue_handler_lock);
	qh = queue_handler[*pos];
	if (!qh)
		ret = seq_printf(s, "%2lld NONE\n", *pos);
	else
		ret = seq_printf(s, "%2lld %s\n", *pos, qh->name);
	read_unlock_bh(&queue_handler_lock);

	return ret;
}

static struct seq_operations nfqueue_seq_ops = {
	.start	= seq_start,
	.next	= seq_next,
	.stop	= seq_stop,
	.show	= seq_show,
};

static int nfqueue_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &nfqueue_seq_ops);
}

static struct file_operations nfqueue_file_ops = {
	.owner	 = THIS_MODULE,
	.open	 = nfqueue_open,
	.read	 = seq_read,
	.llseek	 = seq_lseek,
	.release = seq_release,
};
#endif /* PROC_FS */


int __init netfilter_queue_init(void)
{
#ifdef CONFIG_PROC_FS
	struct proc_dir_entry *pde;
#endif
	queue_rerouter = kmalloc(NPROTO * sizeof(struct nf_queue_rerouter),
				 GFP_KERNEL);
	if (!queue_rerouter)
		return -ENOMEM;

#ifdef CONFIG_PROC_FS
	pde = create_proc_entry("nf_queue", S_IRUGO, proc_net_netfilter);
	if (!pde) {
		kfree(queue_rerouter);
		return -1;
	}
	pde->proc_fops = &nfqueue_file_ops;
#endif
	memset(queue_rerouter, 0, NPROTO * sizeof(struct nf_queue_rerouter));

	return 0;
}