2 * netfilter module for userspace packet logging daemons
4 * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
6 * 2000/09/22 ulog-cprange feature added
7 * 2001/01/04 in-kernel queue as proposed by Sebastian Zander
8 * <zander@fokus.gmd.de>
9 * 2001/01/30 per-rule nlgroup conflicts with global queue.
10 * nlgroup now global (sysctl)
11 * 2001/04/19 ulog-queue reworked, now fixed buffer size specified at
13 * 2002/07/07 remove broken nflog_rcv() function -HW
14 * 2002/08/29 fix shifted/unshifted nlgroup bug -HW
15 * 2002/10/30 fix uninitialized mac_len field - <Anders K. Pedersen>
16 * 2004/10/25 fix erroneous calculation of 'len' parameter to NLMSG_PUT
17 * resulting in bogus 'error during NLMSG_PUT' messages.
19 * (C) 1999-2001 Paul `Rusty' Russell
20 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
22 * This program is free software; you can redistribute it and/or modify
23 * it under the terms of the GNU General Public License version 2 as
24 * published by the Free Software Foundation.
26 * This module accepts two parameters:
29 * The parameter specifies how big the buffer for each netlink multicast
30 * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
31 * get accumulated in the kernel until they are sent to userspace. It is
32 * NOT possible to allocate more than 128kB, and it is strongly discouraged,
33 * because atomically allocating 128kB inside the network rx softirq is not
34 * reliable. Please also keep in mind that this buffer size is allocated for
35 * each nlgroup you are using, so the total kernel memory usage increases
38 * Actually you should use nlbufsiz a bit smaller than PAGE_SIZE, since
39 * nlbufsiz is used with alloc_skb, which adds another
40 * sizeof(struct skb_shared_info). Use NLMSG_GOODSIZE instead.
43 * Specify, after how many hundredths of a second the queue should be
44 * flushed even if it is not full yet.
46 * ipt_ULOG.c,v 1.22 2002/10/30 09:07:31 laforge Exp
49 #include <linux/module.h>
50 #include <linux/spinlock.h>
51 #include <linux/socket.h>
52 #include <linux/skbuff.h>
53 #include <linux/kernel.h>
54 #include <linux/timer.h>
55 #include <linux/netlink.h>
56 #include <linux/netdevice.h>
58 #include <linux/moduleparam.h>
59 #include <linux/netfilter.h>
60 #include <linux/netfilter_ipv4/ip_tables.h>
61 #include <linux/netfilter_ipv4/ipt_ULOG.h>
63 #include <linux/bitops.h>
65 MODULE_LICENSE("GPL");
66 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
67 MODULE_DESCRIPTION("iptables userspace logging module");
68 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
70 #define ULOG_NL_EVENT 111 /* Harald's favorite number */
71 #define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
74 #define DEBUGP(format, args...) printk("%s:%s:" format, \
75 __FILE__, __FUNCTION__ , ## args)
77 #define DEBUGP(format, args...)
80 #define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
82 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
83 module_param(nlbufsiz, uint, 0400);
84 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
86 static unsigned int flushtimeout = 10;
87 module_param(flushtimeout, uint, 0600);
88 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
91 module_param(nflog, bool, 0400);
92 MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
94 /* global data structures */
97 unsigned int qlen; /* number of nlmsgs' in the skb */
98 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
99 struct sk_buff *skb; /* the pre-allocated skb */
100 struct timer_list timer; /* the timer function */
103 static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */
105 static struct sock *nflognl; /* our socket */
106 static DEFINE_SPINLOCK(ulog_lock); /* spinlock */
108 /* send one ulog_buff_t to userspace */
109 static void ulog_send(unsigned int nlgroupnum)
111 ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
113 if (timer_pending(&ub->timer)) {
114 DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
115 del_timer(&ub->timer);
119 DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
123 /* last nlmsg needs NLMSG_DONE */
125 ub->lastnlh->nlmsg_type = NLMSG_DONE;
128 DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
132 NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1;
133 DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
134 ub->qlen, nlgroupnum + 1);
135 netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, GFP_ATOMIC);
144 /* timer function to flush queue in flushtimeout time */
145 static void ulog_timer(unsigned long data)
147 DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
149 /* lock to protect against somebody modifying our structure
150 * from ipt_ulog_target at the same time */
151 spin_lock_bh(&ulog_lock);
153 spin_unlock_bh(&ulog_lock);
156 static struct sk_buff *ulog_alloc_skb(unsigned int size)
161 /* alloc skb which should be big enough for a whole
162 * multipart message. WARNING: has to be <= 131000
163 * due to slab allocator restrictions */
165 n = max(size, nlbufsiz);
166 skb = alloc_skb(n, GFP_ATOMIC);
168 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n);
171 /* try to allocate only as much as we need for
174 skb = alloc_skb(size, GFP_ATOMIC);
176 PRINTR("ipt_ULOG: can't even allocate %ub\n",
184 static void ipt_ulog_packet(unsigned int hooknum,
185 const struct sk_buff *skb,
186 const struct net_device *in,
187 const struct net_device *out,
188 const struct ipt_ulog_info *loginfo,
192 ulog_packet_msg_t *pm;
193 size_t size, copy_len;
194 struct nlmsghdr *nlh;
196 /* ffs == find first bit set, necessary because userspace
197 * is already shifting groupnumber, but we need unshifted.
198 * ffs() returns [1..32], we need [0..31] */
199 unsigned int groupnum = ffs(loginfo->nl_group) - 1;
201 /* calculate the size of the skb needed */
202 if ((loginfo->copy_range == 0) ||
203 (loginfo->copy_range > skb->len)) {
206 copy_len = loginfo->copy_range;
209 size = NLMSG_SPACE(sizeof(*pm) + copy_len);
211 ub = &ulog_buffers[groupnum];
213 spin_lock_bh(&ulog_lock);
216 if (!(ub->skb = ulog_alloc_skb(size)))
218 } else if (ub->qlen >= loginfo->qthreshold ||
219 size > skb_tailroom(ub->skb)) {
220 /* either the queue len is too high or we don't have
221 * enough room in nlskb left. send it to userspace. */
225 if (!(ub->skb = ulog_alloc_skb(size)))
229 DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen,
230 loginfo->qthreshold);
232 /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
233 nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
234 sizeof(*pm)+copy_len);
237 pm = NLMSG_DATA(nlh);
239 /* We might not have a timestamp, get one */
240 if (skb->tstamp.off_sec == 0)
241 __net_timestamp((struct sk_buff *)skb);
243 /* copy hook, prefix, timestamp, payload, etc. */
244 pm->data_len = copy_len;
245 pm->timestamp_sec = skb->tstamp.off_sec;
246 pm->timestamp_usec = skb->tstamp.off_usec;
247 pm->mark = skb->mark;
250 strncpy(pm->prefix, prefix, sizeof(pm->prefix));
251 else if (loginfo->prefix[0] != '\0')
252 strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
254 *(pm->prefix) = '\0';
256 if (in && in->hard_header_len > 0
257 && skb->mac.raw != (void *) skb->nh.iph
258 && in->hard_header_len <= ULOG_MAC_LEN) {
259 memcpy(pm->mac, skb->mac.raw, in->hard_header_len);
260 pm->mac_len = in->hard_header_len;
265 strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
267 pm->indev_name[0] = '\0';
270 strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
272 pm->outdev_name[0] = '\0';
274 /* copy_len <= skb->len, so can't fail. */
275 if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
278 /* check if we are building multi-part messages */
280 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
285 /* if timer isn't already running, start it */
286 if (!timer_pending(&ub->timer)) {
287 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
288 add_timer(&ub->timer);
291 /* if threshold is reached, send message to userspace */
292 if (ub->qlen >= loginfo->qthreshold) {
293 if (loginfo->qthreshold > 1)
294 nlh->nlmsg_type = NLMSG_DONE;
298 spin_unlock_bh(&ulog_lock);
303 PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
306 PRINTR("ipt_ULOG: Error building netlink message\n");
308 spin_unlock_bh(&ulog_lock);
311 static unsigned int ipt_ulog_target(struct sk_buff **pskb,
312 const struct net_device *in,
313 const struct net_device *out,
314 unsigned int hooknum,
315 const struct xt_target *target,
316 const void *targinfo)
318 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
320 ipt_ulog_packet(hooknum, *pskb, in, out, loginfo, NULL);
325 static void ipt_logfn(unsigned int pf,
326 unsigned int hooknum,
327 const struct sk_buff *skb,
328 const struct net_device *in,
329 const struct net_device *out,
330 const struct nf_loginfo *li,
333 struct ipt_ulog_info loginfo;
335 if (!li || li->type != NF_LOG_TYPE_ULOG) {
336 loginfo.nl_group = ULOG_DEFAULT_NLGROUP;
337 loginfo.copy_range = 0;
338 loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD;
339 loginfo.prefix[0] = '\0';
341 loginfo.nl_group = li->u.ulog.group;
342 loginfo.copy_range = li->u.ulog.copy_len;
343 loginfo.qthreshold = li->u.ulog.qthreshold;
344 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
347 ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
350 static int ipt_ulog_checkentry(const char *tablename,
352 const struct xt_target *target,
354 unsigned int hookmask)
356 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
358 if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
359 DEBUGP("ipt_ULOG: prefix term %i\n",
360 loginfo->prefix[sizeof(loginfo->prefix) - 1]);
363 if (loginfo->qthreshold > ULOG_MAX_QLEN) {
364 DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
365 loginfo->qthreshold);
371 static struct ipt_target ipt_ulog_reg = {
373 .target = ipt_ulog_target,
374 .targetsize = sizeof(struct ipt_ulog_info),
375 .checkentry = ipt_ulog_checkentry,
379 static struct nf_logger ipt_ulog_logger = {
385 static int __init ipt_ulog_init(void)
389 DEBUGP("ipt_ULOG: init module\n");
391 if (nlbufsiz > 128*1024) {
392 printk("Netlink buffer has to be <= 128kB\n");
396 /* initialize ulog_buffers */
397 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
398 init_timer(&ulog_buffers[i].timer);
399 ulog_buffers[i].timer.function = ulog_timer;
400 ulog_buffers[i].timer.data = i;
403 nflognl = netlink_kernel_create(NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL,
408 if (ipt_register_target(&ipt_ulog_reg) != 0) {
409 sock_release(nflognl->sk_socket);
413 nf_log_register(PF_INET, &ipt_ulog_logger);
418 static void __exit ipt_ulog_fini(void)
423 DEBUGP("ipt_ULOG: cleanup_module\n");
426 nf_log_unregister_logger(&ipt_ulog_logger);
427 ipt_unregister_target(&ipt_ulog_reg);
428 sock_release(nflognl->sk_socket);
430 /* remove pending timers and free allocated skb's */
431 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
432 ub = &ulog_buffers[i];
433 if (timer_pending(&ub->timer)) {
434 DEBUGP("timer was pending, deleting\n");
435 del_timer(&ub->timer);
446 module_init(ipt_ulog_init);
447 module_exit(ipt_ulog_fini);