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/config.h>
51 #include <linux/spinlock.h>
52 #include <linux/socket.h>
53 #include <linux/skbuff.h>
54 #include <linux/kernel.h>
55 #include <linux/timer.h>
56 #include <linux/netlink.h>
57 #include <linux/netdevice.h>
59 #include <linux/moduleparam.h>
60 #include <linux/netfilter.h>
61 #include <linux/netfilter_ipv4/ip_tables.h>
62 #include <linux/netfilter_ipv4/ipt_ULOG.h>
64 #include <linux/bitops.h>
66 MODULE_LICENSE("GPL");
67 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
68 MODULE_DESCRIPTION("iptables userspace logging module");
69 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
71 #define ULOG_NL_EVENT 111 /* Harald's favorite number */
72 #define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
75 #define DEBUGP(format, args...) printk("%s:%s:" format, \
76 __FILE__, __FUNCTION__ , ## args)
78 #define DEBUGP(format, args...)
81 #define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
83 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
84 module_param(nlbufsiz, uint, 0400);
85 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
87 static unsigned int flushtimeout = 10;
88 module_param(flushtimeout, uint, 0600);
89 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
92 module_param(nflog, bool, 0400);
93 MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
95 /* global data structures */
98 unsigned int qlen; /* number of nlmsgs' in the skb */
99 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
100 struct sk_buff *skb; /* the pre-allocated skb */
101 struct timer_list timer; /* the timer function */
104 static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */
106 static struct sock *nflognl; /* our socket */
107 static DEFINE_SPINLOCK(ulog_lock); /* spinlock */
109 /* send one ulog_buff_t to userspace */
110 static void ulog_send(unsigned int nlgroupnum)
112 ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
114 if (timer_pending(&ub->timer)) {
115 DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
116 del_timer(&ub->timer);
120 DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
124 /* last nlmsg needs NLMSG_DONE */
126 ub->lastnlh->nlmsg_type = NLMSG_DONE;
129 DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
133 NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1;
134 DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
135 ub->qlen, nlgroupnum + 1);
136 netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, GFP_ATOMIC);
145 /* timer function to flush queue in flushtimeout time */
146 static void ulog_timer(unsigned long data)
148 DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
150 /* lock to protect against somebody modifying our structure
151 * from ipt_ulog_target at the same time */
152 spin_lock_bh(&ulog_lock);
154 spin_unlock_bh(&ulog_lock);
157 static struct sk_buff *ulog_alloc_skb(unsigned int size)
162 /* alloc skb which should be big enough for a whole
163 * multipart message. WARNING: has to be <= 131000
164 * due to slab allocator restrictions */
166 n = max(size, nlbufsiz);
167 skb = alloc_skb(n, GFP_ATOMIC);
169 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n);
172 /* try to allocate only as much as we need for
175 skb = alloc_skb(size, GFP_ATOMIC);
177 PRINTR("ipt_ULOG: can't even allocate %ub\n",
185 static void ipt_ulog_packet(unsigned int hooknum,
186 const struct sk_buff *skb,
187 const struct net_device *in,
188 const struct net_device *out,
189 const struct ipt_ulog_info *loginfo,
193 ulog_packet_msg_t *pm;
194 size_t size, copy_len;
195 struct nlmsghdr *nlh;
197 /* ffs == find first bit set, necessary because userspace
198 * is already shifting groupnumber, but we need unshifted.
199 * ffs() returns [1..32], we need [0..31] */
200 unsigned int groupnum = ffs(loginfo->nl_group) - 1;
202 /* calculate the size of the skb needed */
203 if ((loginfo->copy_range == 0) ||
204 (loginfo->copy_range > skb->len)) {
207 copy_len = loginfo->copy_range;
210 size = NLMSG_SPACE(sizeof(*pm) + copy_len);
212 ub = &ulog_buffers[groupnum];
214 spin_lock_bh(&ulog_lock);
217 if (!(ub->skb = ulog_alloc_skb(size)))
219 } else if (ub->qlen >= loginfo->qthreshold ||
220 size > skb_tailroom(ub->skb)) {
221 /* either the queue len is too high or we don't have
222 * enough room in nlskb left. send it to userspace. */
226 if (!(ub->skb = ulog_alloc_skb(size)))
230 DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen,
231 loginfo->qthreshold);
233 /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
234 nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
235 sizeof(*pm)+copy_len);
238 pm = NLMSG_DATA(nlh);
240 /* We might not have a timestamp, get one */
241 if (skb->tstamp.off_sec == 0)
242 __net_timestamp((struct sk_buff *)skb);
244 /* copy hook, prefix, timestamp, payload, etc. */
245 pm->data_len = copy_len;
246 pm->timestamp_sec = skb->tstamp.off_sec;
247 pm->timestamp_usec = skb->tstamp.off_usec;
248 pm->mark = skb->nfmark;
251 strncpy(pm->prefix, prefix, sizeof(pm->prefix));
252 else if (loginfo->prefix[0] != '\0')
253 strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
255 *(pm->prefix) = '\0';
257 if (in && in->hard_header_len > 0
258 && skb->mac.raw != (void *) skb->nh.iph
259 && in->hard_header_len <= ULOG_MAC_LEN) {
260 memcpy(pm->mac, skb->mac.raw, in->hard_header_len);
261 pm->mac_len = in->hard_header_len;
266 strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
268 pm->indev_name[0] = '\0';
271 strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
273 pm->outdev_name[0] = '\0';
275 /* copy_len <= skb->len, so can't fail. */
276 if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
279 /* check if we are building multi-part messages */
281 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
286 /* if timer isn't already running, start it */
287 if (!timer_pending(&ub->timer)) {
288 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
289 add_timer(&ub->timer);
292 /* if threshold is reached, send message to userspace */
293 if (ub->qlen >= loginfo->qthreshold) {
294 if (loginfo->qthreshold > 1)
295 nlh->nlmsg_type = NLMSG_DONE;
299 spin_unlock_bh(&ulog_lock);
304 PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
307 PRINTR("ipt_ULOG: Error building netlink message\n");
309 spin_unlock_bh(&ulog_lock);
312 static unsigned int ipt_ulog_target(struct sk_buff **pskb,
313 const struct net_device *in,
314 const struct net_device *out,
315 unsigned int hooknum,
316 const void *targinfo, void *userinfo)
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,
353 unsigned int targinfosize,
354 unsigned int hookmask)
356 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
358 if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ulog_info))) {
359 DEBUGP("ipt_ULOG: targinfosize %u != 0\n", targinfosize);
363 if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
364 DEBUGP("ipt_ULOG: prefix term %i\n",
365 loginfo->prefix[sizeof(loginfo->prefix) - 1]);
369 if (loginfo->qthreshold > ULOG_MAX_QLEN) {
370 DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
371 loginfo->qthreshold);
378 static struct ipt_target ipt_ulog_reg = {
380 .target = ipt_ulog_target,
381 .checkentry = ipt_ulog_checkentry,
385 static struct nf_logger ipt_ulog_logger = {
391 static int __init init(void)
395 DEBUGP("ipt_ULOG: init module\n");
397 if (nlbufsiz > 128*1024) {
398 printk("Netlink buffer has to be <= 128kB\n");
402 /* initialize ulog_buffers */
403 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
404 init_timer(&ulog_buffers[i].timer);
405 ulog_buffers[i].timer.function = ulog_timer;
406 ulog_buffers[i].timer.data = i;
409 nflognl = netlink_kernel_create(NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL,
414 if (ipt_register_target(&ipt_ulog_reg) != 0) {
415 sock_release(nflognl->sk_socket);
419 nf_log_register(PF_INET, &ipt_ulog_logger);
424 static void __exit fini(void)
429 DEBUGP("ipt_ULOG: cleanup_module\n");
432 nf_log_unregister_logger(&ipt_ulog_logger);
433 ipt_unregister_target(&ipt_ulog_reg);
434 sock_release(nflognl->sk_socket);
436 /* remove pending timers and free allocated skb's */
437 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
438 ub = &ulog_buffers[i];
439 if (timer_pending(&ub->timer)) {
440 DEBUGP("timer was pending, deleting\n");
441 del_timer(&ub->timer);