summaryrefslogtreecommitdiff
path: root/net/ipv4/netfilter/ip_queue.c
blob: e2787048aa0a4f9008cb8389e89baaaa45717fce (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
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
/*
 * This is a module which is used for queueing IPv4 packets and
 * communicating with userspace via netlink.
 *
 * (C) 2000-2002 James Morris <jmorris@intercode.com.au>
 * (C) 2003-2005 Netfilter Core Team <coreteam@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4/ip_queue.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netlink.h>
#include <linux/spinlock.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/security.h>
#include <linux/net.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <net/route.h>
#include <net/netfilter/nf_queue.h>
#include <net/ip.h>

#define IPQ_QMAX_DEFAULT 1024
#define IPQ_PROC_FS_NAME "ip_queue"
#define NET_IPQ_QMAX 2088
#define NET_IPQ_QMAX_NAME "ip_queue_maxlen"

typedef int (*ipq_cmpfn)(struct nf_queue_entry *, unsigned long);

static unsigned char copy_mode __read_mostly = IPQ_COPY_NONE;
static unsigned int queue_maxlen __read_mostly = IPQ_QMAX_DEFAULT;
static DEFINE_RWLOCK(queue_lock);
static int peer_pid __read_mostly;
static unsigned int copy_range __read_mostly;
static unsigned int queue_total;
static unsigned int queue_dropped = 0;
static unsigned int queue_user_dropped = 0;
static struct sock *ipqnl __read_mostly;
static LIST_HEAD(queue_list);
static DEFINE_MUTEX(ipqnl_mutex);

static inline void
__ipq_enqueue_entry(struct nf_queue_entry *entry)
{
       list_add_tail(&entry->list, &queue_list);
       queue_total++;
}

static inline int
__ipq_set_mode(unsigned char mode, unsigned int range)
{
	int status = 0;

	switch(mode) {
	case IPQ_COPY_NONE:
	case IPQ_COPY_META:
		copy_mode = mode;
		copy_range = 0;
		break;

	case IPQ_COPY_PACKET:
		copy_mode = mode;
		copy_range = range;
		if (copy_range > 0xFFFF)
			copy_range = 0xFFFF;
		break;

	default:
		status = -EINVAL;

	}
	return status;
}

static void __ipq_flush(ipq_cmpfn cmpfn, unsigned long data);

static inline void
__ipq_reset(void)
{
	peer_pid = 0;
	net_disable_timestamp();
	__ipq_set_mode(IPQ_COPY_NONE, 0);
	__ipq_flush(NULL, 0);
}

static struct nf_queue_entry *
ipq_find_dequeue_entry(unsigned long id)
{
	struct nf_queue_entry *entry = NULL, *i;

	write_lock_bh(&queue_lock);

	list_for_each_entry(i, &queue_list, list) {
		if ((unsigned long)i == id) {
			entry = i;
			break;
		}
	}

	if (entry) {
		list_del(&entry->list);
		queue_total--;
	}

	write_unlock_bh(&queue_lock);
	return entry;
}

static void
__ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
{
	struct nf_queue_entry *entry, *next;

	list_for_each_entry_safe(entry, next, &queue_list, list) {
		if (!cmpfn || cmpfn(entry, data)) {
			list_del(&entry->list);
			queue_total--;
			nf_reinject(entry, NF_DROP);
		}
	}
}

static void
ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
{
	write_lock_bh(&queue_lock);
	__ipq_flush(cmpfn, data);
	write_unlock_bh(&queue_lock);
}

static struct sk_buff *
ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
{
	sk_buff_data_t old_tail;
	size_t size = 0;
	size_t data_len = 0;
	struct sk_buff *skb;
	struct ipq_packet_msg *pmsg;
	struct nlmsghdr *nlh;
	struct timeval tv;

	read_lock_bh(&queue_lock);

	switch (copy_mode) {
	case IPQ_COPY_META:
	case IPQ_COPY_NONE:
		size = NLMSG_SPACE(sizeof(*pmsg));
		break;

	case IPQ_COPY_PACKET:
		if ((entry->skb->ip_summed == CHECKSUM_PARTIAL ||
		     entry->skb->ip_summed == CHECKSUM_COMPLETE) &&
		    (*errp = skb_checksum_help(entry->skb))) {
			read_unlock_bh(&queue_lock);
			return NULL;
		}
		if (copy_range == 0 || copy_range > entry->skb->len)
			data_len = entry->skb->len;
		else
			data_len = copy_range;

		size = NLMSG_SPACE(sizeof(*pmsg) + data_len);
		break;

	default:
		*errp = -EINVAL;
		read_unlock_bh(&queue_lock);
		return NULL;
	}

	read_unlock_bh(&queue_lock);

	skb = alloc_skb(size, GFP_ATOMIC);
	if (!skb)
		goto nlmsg_failure;

	old_tail = skb->tail;
	nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));
	pmsg = NLMSG_DATA(nlh);
	memset(pmsg, 0, sizeof(*pmsg));

	pmsg->packet_id       = (unsigned long )entry;
	pmsg->data_len        = data_len;
	tv = ktime_to_timeval(entry->skb->tstamp);
	pmsg->timestamp_sec   = tv.tv_sec;
	pmsg->timestamp_usec  = tv.tv_usec;
	pmsg->mark            = entry->skb->mark;
	pmsg->hook            = entry->hook;
	pmsg->hw_protocol     = entry->skb->protocol;

	if (entry->indev)
		strcpy(pmsg->indev_name, entry->indev->name);
	else
		pmsg->indev_name[0] = '\0';

	if (entry->outdev)
		strcpy(pmsg->outdev_name, entry->outdev->name);
	else
		pmsg->outdev_name[0] = '\0';

	if (entry->indev && entry->skb->dev) {
		pmsg->hw_type = entry->skb->dev->type;
		pmsg->hw_addrlen = dev_parse_header(entry->skb,
						    pmsg->hw_addr);
	}

	if (data_len)
		if (skb_copy_bits(entry->skb, 0, pmsg->payload, data_len))
			BUG();

	nlh->nlmsg_len = skb->tail - old_tail;
	return skb;

nlmsg_failure:
	*errp = -EINVAL;
	printk(KERN_ERR "ip_queue: error creating packet message\n");
	return NULL;
}

static int
ipq_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
{
	int status = -EINVAL;
	struct sk_buff *nskb;

	if (copy_mode == IPQ_COPY_NONE)
		return -EAGAIN;

	nskb = ipq_build_packet_message(entry, &status);
	if (nskb == NULL)
		return status;

	write_lock_bh(&queue_lock);

	if (!peer_pid)
		goto err_out_free_nskb;

	if (queue_total >= queue_maxlen) {
		queue_dropped++;
		status = -ENOSPC;
		if (net_ratelimit())
			  printk (KERN_WARNING "ip_queue: full at %d entries, "
				  "dropping packets(s). Dropped: %d\n", queue_total,
				  queue_dropped);
		goto err_out_free_nskb;
	}

	/* netlink_unicast will either free the nskb or attach it to a socket */
	status = netlink_unicast(ipqnl, nskb, peer_pid, MSG_DONTWAIT);
	if (status < 0) {
		queue_user_dropped++;
		goto err_out_unlock;
	}

	__ipq_enqueue_entry(entry);

	write_unlock_bh(&queue_lock);
	return status;

err_out_free_nskb:
	kfree_skb(nskb);

err_out_unlock:
	write_unlock_bh(&queue_lock);
	return status;
}

static int
ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct nf_queue_entry *e)
{
	int diff;
	struct iphdr *user_iph = (struct iphdr *)v->payload;
	struct sk_buff *nskb;

	if (v->data_len < sizeof(*user_iph))
		return 0;
	diff = v->data_len - e->skb->len;
	if (diff < 0) {
		if (pskb_trim(e->skb, v->data_len))
			return -ENOMEM;
	} else if (diff > 0) {
		if (v->data_len > 0xFFFF)
			return -EINVAL;
		if (diff > skb_tailroom(e->skb)) {
			nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
					       diff, GFP_ATOMIC);
			if (!nskb) {
				printk(KERN_WARNING "ip_queue: error "
				      "in mangle, dropping packet\n");
				return -ENOMEM;
			}
			kfree_skb(e->skb);
			e->skb = nskb;
		}
		skb_put(e->skb, diff);
	}
	if (!skb_make_writable(e->skb, v->data_len))
		return -ENOMEM;
	skb_copy_to_linear_data(e->skb, v->payload, v->data_len);
	e->skb->ip_summed = CHECKSUM_NONE;

	return 0;
}

static int
ipq_set_verdict(struct ipq_verdict_msg *vmsg, unsigned int len)
{
	struct nf_queue_entry *entry;

	if (vmsg->value > NF_MAX_VERDICT)
		return -EINVAL;

	entry = ipq_find_dequeue_entry(vmsg->id);
	if (entry == NULL)
		return -ENOENT;
	else {
		int verdict = vmsg->value;

		if (vmsg->data_len && vmsg->data_len == len)
			if (ipq_mangle_ipv4(vmsg, entry) < 0)
				verdict = NF_DROP;

		nf_reinject(entry, verdict);
		return 0;
	}
}

static int
ipq_set_mode(unsigned char mode, unsigned int range)
{
	int status;

	write_lock_bh(&queue_lock);
	status = __ipq_set_mode(mode, range);
	write_unlock_bh(&queue_lock);
	return status;
}

static int
ipq_receive_peer(struct ipq_peer_msg *pmsg,
		 unsigned char type, unsigned int len)
{
	int status = 0;

	if (len < sizeof(*pmsg))
		return -EINVAL;

	switch (type) {
	case IPQM_MODE:
		status = ipq_set_mode(pmsg->msg.mode.value,
				      pmsg->msg.mode.range);
		break;

	case IPQM_VERDICT:
		if (pmsg->msg.verdict.value > NF_MAX_VERDICT)
			status = -EINVAL;
		else
			status = ipq_set_verdict(&pmsg->msg.verdict,
						 len - sizeof(*pmsg));
			break;
	default:
		status = -EINVAL;
	}
	return status;
}

static int
dev_cmp(struct nf_queue_entry *entry, unsigned long ifindex)
{
	if (entry->indev)
		if (entry->indev->ifindex == ifindex)
			return 1;
	if (entry->outdev)
		if (entry->outdev->ifindex == ifindex)
			return 1;
#ifdef CONFIG_BRIDGE_NETFILTER
	if (entry->skb->nf_bridge) {
		if (entry->skb->nf_bridge->physindev &&
		    entry->skb->nf_bridge->physindev->ifindex == ifindex)
			return 1;
		if (entry->skb->nf_bridge->physoutdev &&
		    entry->skb->nf_bridge->physoutdev->ifindex == ifindex)
			return 1;
	}
#endif
	return 0;
}

static void
ipq_dev_drop(int ifindex)
{
	ipq_flush(dev_cmp, ifindex);
}

#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)

static inline void
__ipq_rcv_skb(struct sk_buff *skb)
{
	int status, type, pid, flags, nlmsglen, skblen;
	struct nlmsghdr *nlh;

	skblen = skb->len;
	if (skblen < sizeof(*nlh))
		return;

	nlh = nlmsg_hdr(skb);
	nlmsglen = nlh->nlmsg_len;
	if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
		return;

	pid = nlh->nlmsg_pid;
	flags = nlh->nlmsg_flags;

	if(pid <= 0 || !(flags & NLM_F_REQUEST) || flags & NLM_F_MULTI)
		RCV_SKB_FAIL(-EINVAL);

	if (flags & MSG_TRUNC)
		RCV_SKB_FAIL(-ECOMM);

	type = nlh->nlmsg_type;
	if (type < NLMSG_NOOP || type >= IPQM_MAX)
		RCV_SKB_FAIL(-EINVAL);

	if (type <= IPQM_BASE)
		return;

	if (security_netlink_recv(skb, CAP_NET_ADMIN))
		RCV_SKB_FAIL(-EPERM);

	write_lock_bh(&queue_lock);

	if (peer_pid) {
		if (peer_pid != pid) {
			write_unlock_bh(&queue_lock);
			RCV_SKB_FAIL(-EBUSY);
		}
	} else {
		net_enable_timestamp();
		peer_pid = pid;
	}

	write_unlock_bh(&queue_lock);

	status = ipq_receive_peer(NLMSG_DATA(nlh), type,
				  nlmsglen - NLMSG_LENGTH(0));
	if (status < 0)
		RCV_SKB_FAIL(status);

	if (flags & NLM_F_ACK)
		netlink_ack(skb, nlh, 0);
	return;
}

static void
ipq_rcv_skb(struct sk_buff *skb)
{
	mutex_lock(&ipqnl_mutex);
	__ipq_rcv_skb(skb);
	mutex_unlock(&ipqnl_mutex);
}

static int
ipq_rcv_dev_event(struct notifier_block *this,
		  unsigned long event, void *ptr)
{
	struct net_device *dev = ptr;

	if (!net_eq(dev_net(dev), &init_net))
		return NOTIFY_DONE;

	/* Drop any packets associated with the downed device */
	if (event == NETDEV_DOWN)
		ipq_dev_drop(dev->ifindex);
	return NOTIFY_DONE;
}

static struct notifier_block ipq_dev_notifier = {
	.notifier_call	= ipq_rcv_dev_event,
};

static int
ipq_rcv_nl_event(struct notifier_block *this,
		 unsigned long event, void *ptr)
{
	struct netlink_notify *n = ptr;

	if (event == NETLINK_URELEASE && n->protocol == NETLINK_FIREWALL) {
		write_lock_bh(&queue_lock);
		if ((net_eq(n->net, &init_net)) && (n->pid == peer_pid))
			__ipq_reset();
		write_unlock_bh(&queue_lock);
	}
	return NOTIFY_DONE;
}

static struct notifier_block ipq_nl_notifier = {
	.notifier_call	= ipq_rcv_nl_event,
};

#ifdef CONFIG_SYSCTL
static struct ctl_table_header *ipq_sysctl_header;

static ctl_table ipq_table[] = {
	{
		.procname	= NET_IPQ_QMAX_NAME,
		.data		= &queue_maxlen,
		.maxlen		= sizeof(queue_maxlen),
		.mode		= 0644,
		.proc_handler	= proc_dointvec
	},
	{ }
};
#endif

#ifdef CONFIG_PROC_FS
static int ip_queue_show(struct seq_file *m, void *v)
{
	read_lock_bh(&queue_lock);

	seq_printf(m,
		      "Peer PID          : %d\n"
		      "Copy mode         : %hu\n"
		      "Copy range        : %u\n"
		      "Queue length      : %u\n"
		      "Queue max. length : %u\n"
		      "Queue dropped     : %u\n"
		      "Netlink dropped   : %u\n",
		      peer_pid,
		      copy_mode,
		      copy_range,
		      queue_total,
		      queue_maxlen,
		      queue_dropped,
		      queue_user_dropped);

	read_unlock_bh(&queue_lock);
	return 0;
}

static int ip_queue_open(struct inode *inode, struct file *file)
{
	return single_open(file, ip_queue_show, NULL);
}

static const struct file_operations ip_queue_proc_fops = {
	.open		= ip_queue_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
	.owner		= THIS_MODULE,
};
#endif

static const struct nf_queue_handler nfqh = {
	.name	= "ip_queue",
	.outfn	= &ipq_enqueue_packet,
};

static int __init ip_queue_init(void)
{
	int status = -ENOMEM;
	struct proc_dir_entry *proc __maybe_unused;

	netlink_register_notifier(&ipq_nl_notifier);
	ipqnl = netlink_kernel_create(&init_net, NETLINK_FIREWALL, 0,
				      ipq_rcv_skb, NULL, THIS_MODULE);
	if (ipqnl == NULL) {
		printk(KERN_ERR "ip_queue: failed to create netlink socket\n");
		goto cleanup_netlink_notifier;
	}

#ifdef CONFIG_PROC_FS
	proc = proc_create(IPQ_PROC_FS_NAME, 0, init_net.proc_net,
			   &ip_queue_proc_fops);
	if (!proc) {
		printk(KERN_ERR "ip_queue: failed to create proc entry\n");
		goto cleanup_ipqnl;
	}
#endif
	register_netdevice_notifier(&ipq_dev_notifier);
#ifdef CONFIG_SYSCTL
	ipq_sysctl_header = register_sysctl_paths(net_ipv4_ctl_path, ipq_table);
#endif
	status = nf_register_queue_handler(NFPROTO_IPV4, &nfqh);
	if (status < 0) {
		printk(KERN_ERR "ip_queue: failed to register queue handler\n");
		goto cleanup_sysctl;
	}
	return status;

cleanup_sysctl:
#ifdef CONFIG_SYSCTL
	unregister_sysctl_table(ipq_sysctl_header);
#endif
	unregister_netdevice_notifier(&ipq_dev_notifier);
	proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
cleanup_ipqnl: __maybe_unused
	netlink_kernel_release(ipqnl);
	mutex_lock(&ipqnl_mutex);
	mutex_unlock(&ipqnl_mutex);

cleanup_netlink_notifier:
	netlink_unregister_notifier(&ipq_nl_notifier);
	return status;
}

static void __exit ip_queue_fini(void)
{
	nf_unregister_queue_handlers(&nfqh);

	ipq_flush(NULL, 0);

#ifdef CONFIG_SYSCTL
	unregister_sysctl_table(ipq_sysctl_header);
#endif
	unregister_netdevice_notifier(&ipq_dev_notifier);
	proc_net_remove(&init_net, IPQ_PROC_FS_NAME);

	netlink_kernel_release(ipqnl);
	mutex_lock(&ipqnl_mutex);
	mutex_unlock(&ipqnl_mutex);

	netlink_unregister_notifier(&ipq_nl_notifier);
}

MODULE_DESCRIPTION("IPv4 packet queue handler");
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_FIREWALL);

module_init(ip_queue_init);
module_exit(ip_queue_fini);