Free Electrons

Embedded Linux Experts

  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
/*
 * netfilter module for userspace packet logging daemons
 *
 * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
 *
 * 2000/09/22 ulog-cprange feature added
 * 2001/01/04 in-kernel queue as proposed by Sebastian Zander 
 * 						<zander@fokus.gmd.de>
 * 2001/01/30 per-rule nlgroup conflicts with global queue. 
 *            nlgroup now global (sysctl)
 * 2001/04/19 ulog-queue reworked, now fixed buffer size specified at
 * 	      module loadtime -HW
 * 2002/07/07 remove broken nflog_rcv() function -HW
 * 2002/08/29 fix shifted/unshifted nlgroup bug -HW
 * 2002/10/30 fix uninitialized mac_len field - <Anders K. Pedersen>
 * 2004/10/25 fix erroneous calculation of 'len' parameter to NLMSG_PUT
 *	      resulting in bogus 'error during NLMSG_PUT' messages.
 *
 * (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 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.
 *
 * This module accepts two parameters: 
 * 
 * nlbufsiz:
 *   The parameter specifies how big the buffer for each netlink multicast
 * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
 * get accumulated in the kernel until they are sent to userspace. It is
 * NOT possible to allocate more than 128kB, and it is strongly discouraged,
 * because atomically allocating 128kB inside the network rx softirq is not
 * reliable. Please also keep in mind that this buffer size is allocated for
 * each nlgroup you are using, so the total kernel memory usage increases
 * by that factor.
 *
 * flushtimeout:
 *   Specify, after how many hundredths of a second the queue should be
 *   flushed even if it is not full yet.
 *
 * ipt_ULOG.c,v 1.22 2002/10/30 09:07:31 laforge Exp
 */

#include <linux/module.h>
#include <linux/config.h>
#include <linux/spinlock.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/netlink.h>
#include <linux/netdevice.h>
#include <linux/mm.h>
#include <linux/moduleparam.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_ULOG.h>
#include <linux/netfilter_ipv4/lockhelp.h>
#include <net/sock.h>
#include <linux/bitops.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("iptables userspace logging module");

#define ULOG_NL_EVENT		111		/* Harald's favorite number */
#define ULOG_MAXNLGROUPS	32		/* numer of nlgroups */

#if 0
#define DEBUGP(format, args...) printk("%s:%s:" format, \
                                       __FILE__, __FUNCTION__ , ## args)
#else
#define DEBUGP(format, args...)
#endif

#define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)

static unsigned int nlbufsiz = 4096;
module_param(nlbufsiz, uint, 0600); /* FIXME: Check size < 128k --RR */
MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");

static unsigned int flushtimeout = 10;
module_param(flushtimeout, int, 0600);
MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");

static unsigned int nflog = 1;
module_param(nflog, int, 0400);
MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");

/* global data structures */

typedef struct {
	unsigned int qlen;		/* number of nlmsgs' in the skb */
	struct nlmsghdr *lastnlh;	/* netlink header of last msg in skb */
	struct sk_buff *skb;		/* the pre-allocated skb */
	struct timer_list timer;	/* the timer function */
} ulog_buff_t;

static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS];	/* array of buffers */

static struct sock *nflognl;	/* our socket */
static DECLARE_LOCK(ulog_lock);	/* spinlock */

/* send one ulog_buff_t to userspace */
static void ulog_send(unsigned int nlgroupnum)
{
	ulog_buff_t *ub = &ulog_buffers[nlgroupnum];

	if (timer_pending(&ub->timer)) {
		DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
		del_timer(&ub->timer);
	}

	/* last nlmsg needs NLMSG_DONE */
	if (ub->qlen > 1)
		ub->lastnlh->nlmsg_type = NLMSG_DONE;

	NETLINK_CB(ub->skb).dst_groups = (1 << nlgroupnum);
	DEBUGP("ipt_ULOG: throwing %d packets to netlink mask %u\n",
		ub->qlen, nlgroupnum);
	netlink_broadcast(nflognl, ub->skb, 0, (1 << nlgroupnum), GFP_ATOMIC);

	ub->qlen = 0;
	ub->skb = NULL;
	ub->lastnlh = NULL;

}


/* timer function to flush queue in flushtimeout time */
static void ulog_timer(unsigned long data)
{
	DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");

	/* lock to protect against somebody modifying our structure
	 * from ipt_ulog_target at the same time */
	LOCK_BH(&ulog_lock);
	ulog_send(data);
	UNLOCK_BH(&ulog_lock);
}

static struct sk_buff *ulog_alloc_skb(unsigned int size)
{
	struct sk_buff *skb;

	/* alloc skb which should be big enough for a whole
	 * multipart message. WARNING: has to be <= 131000
	 * due to slab allocator restrictions */

	skb = alloc_skb(nlbufsiz, GFP_ATOMIC);
	if (!skb) {
		PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n",
			nlbufsiz);

		/* try to allocate only as much as we need for 
		 * current packet */

		skb = alloc_skb(size, GFP_ATOMIC);
		if (!skb)
			PRINTR("ipt_ULOG: can't even allocate %ub\n", size);
	}

	return skb;
}

static void ipt_ulog_packet(unsigned int hooknum,
			    const struct sk_buff *skb,
			    const struct net_device *in,
			    const struct net_device *out,
			    const struct ipt_ulog_info *loginfo,
			    const char *prefix)
{
	ulog_buff_t *ub;
	ulog_packet_msg_t *pm;
	size_t size, copy_len;
	struct nlmsghdr *nlh;

	/* ffs == find first bit set, necessary because userspace
	 * is already shifting groupnumber, but we need unshifted.
	 * ffs() returns [1..32], we need [0..31] */
	unsigned int groupnum = ffs(loginfo->nl_group) - 1;

	/* calculate the size of the skb needed */
	if ((loginfo->copy_range == 0) ||
	    (loginfo->copy_range > skb->len)) {
		copy_len = skb->len;
	} else {
		copy_len = loginfo->copy_range;
	}

	size = NLMSG_SPACE(sizeof(*pm) + copy_len);

	ub = &ulog_buffers[groupnum];
	
	LOCK_BH(&ulog_lock);

	if (!ub->skb) {
		if (!(ub->skb = ulog_alloc_skb(size)))
			goto alloc_failure;
	} else if (ub->qlen >= loginfo->qthreshold ||
		   size > skb_tailroom(ub->skb)) {
		/* either the queue len is too high or we don't have 
		 * enough room in nlskb left. send it to userspace. */

		ulog_send(groupnum);

		if (!(ub->skb = ulog_alloc_skb(size)))
			goto alloc_failure;
	}

	DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen, 
		loginfo->qthreshold);

	/* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
	nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT, 
			sizeof(*pm)+copy_len);
	ub->qlen++;

	pm = NLMSG_DATA(nlh);

	/* We might not have a timestamp, get one */
	if (skb->stamp.tv_sec == 0)
		do_gettimeofday((struct timeval *)&skb->stamp);

	/* copy hook, prefix, timestamp, payload, etc. */
	pm->data_len = copy_len;
	pm->timestamp_sec = skb->stamp.tv_sec;
	pm->timestamp_usec = skb->stamp.tv_usec;
	pm->mark = skb->nfmark;
	pm->hook = hooknum;
	if (prefix != NULL)
		strncpy(pm->prefix, prefix, sizeof(pm->prefix));
	else if (loginfo->prefix[0] != '\0')
		strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
	else
		*(pm->prefix) = '\0';

	if (in && in->hard_header_len > 0
	    && skb->mac.raw != (void *) skb->nh.iph
	    && in->hard_header_len <= ULOG_MAC_LEN) {
		memcpy(pm->mac, skb->mac.raw, in->hard_header_len);
		pm->mac_len = in->hard_header_len;
	} else
		pm->mac_len = 0;

	if (in)
		strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
	else
		pm->indev_name[0] = '\0';

	if (out)
		strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
	else
		pm->outdev_name[0] = '\0';

	/* copy_len <= skb->len, so can't fail. */
	if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
		BUG();
	
	/* check if we are building multi-part messages */
	if (ub->qlen > 1) {
		ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
	}

	ub->lastnlh = nlh;

	/* if timer isn't already running, start it */
	if (!timer_pending(&ub->timer)) {
		ub->timer.expires = jiffies + flushtimeout * HZ / 100;
		add_timer(&ub->timer);
	}

	/* if threshold is reached, send message to userspace */
	if (ub->qlen >= loginfo->qthreshold) {
		if (loginfo->qthreshold > 1)
			nlh->nlmsg_type = NLMSG_DONE;
		ulog_send(groupnum);
	}

	UNLOCK_BH(&ulog_lock);

	return;

nlmsg_failure:
	PRINTR("ipt_ULOG: error during NLMSG_PUT\n");

alloc_failure:
	PRINTR("ipt_ULOG: Error building netlink message\n");

	UNLOCK_BH(&ulog_lock);
}

static unsigned int ipt_ulog_target(struct sk_buff **pskb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const void *targinfo, void *userinfo)
{
	struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;

	ipt_ulog_packet(hooknum, *pskb, in, out, loginfo, NULL);
 
 	return IPT_CONTINUE;
}
 
static void ipt_logfn(unsigned int hooknum,
		      const struct sk_buff *skb,
		      const struct net_device *in,
		      const struct net_device *out,
		      const char *prefix)
{
	struct ipt_ulog_info loginfo = { 
		.nl_group = ULOG_DEFAULT_NLGROUP,
		.copy_range = 0,
		.qthreshold = ULOG_DEFAULT_QTHRESHOLD,
		.prefix = ""
	};

	ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
}

static int ipt_ulog_checkentry(const char *tablename,
			       const struct ipt_entry *e,
			       void *targinfo,
			       unsigned int targinfosize,
			       unsigned int hookmask)
{
	struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;

	if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ulog_info))) {
		DEBUGP("ipt_ULOG: targinfosize %u != 0\n", targinfosize);
		return 0;
	}

	if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
		DEBUGP("ipt_ULOG: prefix term %i\n",
		       loginfo->prefix[sizeof(loginfo->prefix) - 1]);
		return 0;
	}

	if (loginfo->qthreshold > ULOG_MAX_QLEN) {
		DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
			loginfo->qthreshold);
		return 0;
	}

	return 1;
}

static struct ipt_target ipt_ulog_reg = {
	.name		= "ULOG",
	.target		= ipt_ulog_target,
	.checkentry	= ipt_ulog_checkentry,
	.me		= THIS_MODULE,
};

static int __init init(void)
{
	int i;

	DEBUGP("ipt_ULOG: init module\n");

	if (nlbufsiz >= 128*1024) {
		printk("Netlink buffer has to be <= 128kB\n");
		return -EINVAL;
	}

	/* initialize ulog_buffers */
	for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
		init_timer(&ulog_buffers[i].timer);
		ulog_buffers[i].timer.function = ulog_timer;
		ulog_buffers[i].timer.data = i;
	}

	nflognl = netlink_kernel_create(NETLINK_NFLOG, NULL);
	if (!nflognl)
		return -ENOMEM;

	if (ipt_register_target(&ipt_ulog_reg) != 0) {
		sock_release(nflognl->sk_socket);
		return -EINVAL;
	}
	if (nflog)
		nf_log_register(PF_INET, &ipt_logfn);
	
	return 0;
}

static void __exit fini(void)
{
	ulog_buff_t *ub;
	int i;

	DEBUGP("ipt_ULOG: cleanup_module\n");

	if (nflog)
		nf_log_unregister(PF_INET, &ipt_logfn);
	ipt_unregister_target(&ipt_ulog_reg);
	sock_release(nflognl->sk_socket);

	/* remove pending timers and free allocated skb's */
	for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
		ub = &ulog_buffers[i];
		if (timer_pending(&ub->timer)) {
			DEBUGP("timer was pending, deleting\n");
			del_timer(&ub->timer);
		}

		if (ub->skb) {
			kfree_skb(ub->skb);
			ub->skb = NULL;
		}
	}

}

module_init(init);
module_exit(fini);