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
39 * Specify, after how many hundredths of a second the queue should be
40 * flushed even if it is not full yet.
42 * ipt_ULOG.c,v 1.22 2002/10/30 09:07:31 laforge Exp
45 #include <linux/module.h>
46 #include <linux/config.h>
47 #include <linux/spinlock.h>
48 #include <linux/socket.h>
49 #include <linux/skbuff.h>
50 #include <linux/kernel.h>
51 #include <linux/timer.h>
52 #include <linux/netlink.h>
53 #include <linux/netdevice.h>
55 #include <linux/moduleparam.h>
56 #include <linux/netfilter.h>
57 #include <linux/netfilter_ipv4/ip_tables.h>
58 #include <linux/netfilter_ipv4/ipt_ULOG.h>
60 #include <linux/bitops.h>
62 MODULE_LICENSE("GPL");
63 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
64 MODULE_DESCRIPTION("iptables userspace logging module");
66 #define ULOG_NL_EVENT 111 /* Harald's favorite number */
67 #define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
70 #define DEBUGP(format, args...) printk("%s:%s:" format, \
71 __FILE__, __FUNCTION__ , ## args)
73 #define DEBUGP(format, args...)
76 #define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
78 static unsigned int nlbufsiz = 4096;
79 module_param(nlbufsiz, uint, 0600); /* FIXME: Check size < 128k --RR */
80 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
82 static unsigned int flushtimeout = 10;
83 module_param(flushtimeout, int, 0600);
84 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
86 static unsigned int nflog = 1;
87 module_param(nflog, int, 0400);
88 MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
90 /* global data structures */
93 unsigned int qlen; /* number of nlmsgs' in the skb */
94 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
95 struct sk_buff *skb; /* the pre-allocated skb */
96 struct timer_list timer; /* the timer function */
99 static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */
101 static struct sock *nflognl; /* our socket */
102 static DEFINE_SPINLOCK(ulog_lock); /* spinlock */
104 /* send one ulog_buff_t to userspace */
105 static void ulog_send(unsigned int nlgroupnum)
107 ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
109 if (timer_pending(&ub->timer)) {
110 DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
111 del_timer(&ub->timer);
114 /* last nlmsg needs NLMSG_DONE */
116 ub->lastnlh->nlmsg_type = NLMSG_DONE;
118 NETLINK_CB(ub->skb).dst_groups = (1 << nlgroupnum);
119 DEBUGP("ipt_ULOG: throwing %d packets to netlink mask %u\n",
120 ub->qlen, nlgroupnum);
121 netlink_broadcast(nflognl, ub->skb, 0, (1 << nlgroupnum), GFP_ATOMIC);
130 /* timer function to flush queue in flushtimeout time */
131 static void ulog_timer(unsigned long data)
133 DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
135 /* lock to protect against somebody modifying our structure
136 * from ipt_ulog_target at the same time */
137 spin_lock_bh(&ulog_lock);
139 spin_unlock_bh(&ulog_lock);
142 static struct sk_buff *ulog_alloc_skb(unsigned int size)
146 /* alloc skb which should be big enough for a whole
147 * multipart message. WARNING: has to be <= 131000
148 * due to slab allocator restrictions */
150 skb = alloc_skb(nlbufsiz, GFP_ATOMIC);
152 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n",
155 /* try to allocate only as much as we need for
158 skb = alloc_skb(size, GFP_ATOMIC);
160 PRINTR("ipt_ULOG: can't even allocate %ub\n", size);
166 static void ipt_ulog_packet(unsigned int hooknum,
167 const struct sk_buff *skb,
168 const struct net_device *in,
169 const struct net_device *out,
170 const struct ipt_ulog_info *loginfo,
174 ulog_packet_msg_t *pm;
175 size_t size, copy_len;
176 struct nlmsghdr *nlh;
178 /* ffs == find first bit set, necessary because userspace
179 * is already shifting groupnumber, but we need unshifted.
180 * ffs() returns [1..32], we need [0..31] */
181 unsigned int groupnum = ffs(loginfo->nl_group) - 1;
183 /* calculate the size of the skb needed */
184 if ((loginfo->copy_range == 0) ||
185 (loginfo->copy_range > skb->len)) {
188 copy_len = loginfo->copy_range;
191 size = NLMSG_SPACE(sizeof(*pm) + copy_len);
193 ub = &ulog_buffers[groupnum];
195 spin_lock_bh(&ulog_lock);
198 if (!(ub->skb = ulog_alloc_skb(size)))
200 } else if (ub->qlen >= loginfo->qthreshold ||
201 size > skb_tailroom(ub->skb)) {
202 /* either the queue len is too high or we don't have
203 * enough room in nlskb left. send it to userspace. */
207 if (!(ub->skb = ulog_alloc_skb(size)))
211 DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen,
212 loginfo->qthreshold);
214 /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
215 nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
216 sizeof(*pm)+copy_len);
219 pm = NLMSG_DATA(nlh);
221 /* We might not have a timestamp, get one */
222 if (skb->stamp.tv_sec == 0)
223 do_gettimeofday((struct timeval *)&skb->stamp);
225 /* copy hook, prefix, timestamp, payload, etc. */
226 pm->data_len = copy_len;
227 pm->timestamp_sec = skb->stamp.tv_sec;
228 pm->timestamp_usec = skb->stamp.tv_usec;
229 pm->mark = skb->nfmark;
232 strncpy(pm->prefix, prefix, sizeof(pm->prefix));
233 else if (loginfo->prefix[0] != '\0')
234 strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
236 *(pm->prefix) = '\0';
238 if (in && in->hard_header_len > 0
239 && skb->mac.raw != (void *) skb->nh.iph
240 && in->hard_header_len <= ULOG_MAC_LEN) {
241 memcpy(pm->mac, skb->mac.raw, in->hard_header_len);
242 pm->mac_len = in->hard_header_len;
247 strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
249 pm->indev_name[0] = '\0';
252 strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
254 pm->outdev_name[0] = '\0';
256 /* copy_len <= skb->len, so can't fail. */
257 if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
260 /* check if we are building multi-part messages */
262 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
267 /* if timer isn't already running, start it */
268 if (!timer_pending(&ub->timer)) {
269 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
270 add_timer(&ub->timer);
273 /* if threshold is reached, send message to userspace */
274 if (ub->qlen >= loginfo->qthreshold) {
275 if (loginfo->qthreshold > 1)
276 nlh->nlmsg_type = NLMSG_DONE;
280 spin_unlock_bh(&ulog_lock);
285 PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
288 PRINTR("ipt_ULOG: Error building netlink message\n");
290 spin_unlock_bh(&ulog_lock);
293 static unsigned int ipt_ulog_target(struct sk_buff **pskb,
294 const struct net_device *in,
295 const struct net_device *out,
296 unsigned int hooknum,
297 const void *targinfo, void *userinfo)
299 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
301 ipt_ulog_packet(hooknum, *pskb, in, out, loginfo, NULL);
306 static void ipt_logfn(unsigned int hooknum,
307 const struct sk_buff *skb,
308 const struct net_device *in,
309 const struct net_device *out,
312 struct ipt_ulog_info loginfo = {
313 .nl_group = ULOG_DEFAULT_NLGROUP,
315 .qthreshold = ULOG_DEFAULT_QTHRESHOLD,
319 ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
322 static int ipt_ulog_checkentry(const char *tablename,
323 const struct ipt_entry *e,
325 unsigned int targinfosize,
326 unsigned int hookmask)
328 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
330 if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ulog_info))) {
331 DEBUGP("ipt_ULOG: targinfosize %u != 0\n", targinfosize);
335 if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
336 DEBUGP("ipt_ULOG: prefix term %i\n",
337 loginfo->prefix[sizeof(loginfo->prefix) - 1]);
341 if (loginfo->qthreshold > ULOG_MAX_QLEN) {
342 DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
343 loginfo->qthreshold);
350 static struct ipt_target ipt_ulog_reg = {
352 .target = ipt_ulog_target,
353 .checkentry = ipt_ulog_checkentry,
357 static int __init init(void)
361 DEBUGP("ipt_ULOG: init module\n");
363 if (nlbufsiz >= 128*1024) {
364 printk("Netlink buffer has to be <= 128kB\n");
368 /* initialize ulog_buffers */
369 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
370 init_timer(&ulog_buffers[i].timer);
371 ulog_buffers[i].timer.function = ulog_timer;
372 ulog_buffers[i].timer.data = i;
375 nflognl = netlink_kernel_create(NETLINK_NFLOG, NULL);
379 if (ipt_register_target(&ipt_ulog_reg) != 0) {
380 sock_release(nflognl->sk_socket);
384 nf_log_register(PF_INET, &ipt_logfn);
389 static void __exit fini(void)
394 DEBUGP("ipt_ULOG: cleanup_module\n");
397 nf_log_unregister(PF_INET, &ipt_logfn);
398 ipt_unregister_target(&ipt_ulog_reg);
399 sock_release(nflognl->sk_socket);
401 /* remove pending timers and free allocated skb's */
402 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
403 ub = &ulog_buffers[i];
404 if (timer_pending(&ub->timer)) {
405 DEBUGP("timer was pending, deleting\n");
406 del_timer(&ub->timer);