2 * netfilter module for userspace packet logging daemons
4 * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
5 * (C) 1999-2001 Paul `Rusty' Russell
6 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
12 * This module accepts two parameters:
15 * The parameter specifies how big the buffer for each netlink multicast
16 * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
17 * get accumulated in the kernel until they are sent to userspace. It is
18 * NOT possible to allocate more than 128kB, and it is strongly discouraged,
19 * because atomically allocating 128kB inside the network rx softirq is not
20 * reliable. Please also keep in mind that this buffer size is allocated for
21 * each nlgroup you are using, so the total kernel memory usage increases
24 * Actually you should use nlbufsiz a bit smaller than PAGE_SIZE, since
25 * nlbufsiz is used with alloc_skb, which adds another
26 * sizeof(struct skb_shared_info). Use NLMSG_GOODSIZE instead.
29 * Specify, after how many hundredths of a second the queue should be
30 * flushed even if it is not full yet.
33 #include <linux/module.h>
34 #include <linux/spinlock.h>
35 #include <linux/socket.h>
36 #include <linux/skbuff.h>
37 #include <linux/kernel.h>
38 #include <linux/timer.h>
39 #include <linux/netlink.h>
40 #include <linux/netdevice.h>
42 #include <linux/moduleparam.h>
43 #include <linux/netfilter.h>
44 #include <linux/netfilter/x_tables.h>
45 #include <linux/netfilter_ipv4/ipt_ULOG.h>
47 #include <linux/bitops.h>
48 #include <asm/unaligned.h>
50 MODULE_LICENSE("GPL");
51 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
52 MODULE_DESCRIPTION("iptables userspace logging module");
53 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
55 #define ULOG_NL_EVENT 111 /* Harald's favorite number */
56 #define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
59 #define DEBUGP(format, args...) printk("%s:%s:" format, \
60 __FILE__, __FUNCTION__ , ## args)
62 #define DEBUGP(format, args...)
65 #define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
67 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
68 module_param(nlbufsiz, uint, 0400);
69 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
71 static unsigned int flushtimeout = 10;
72 module_param(flushtimeout, uint, 0600);
73 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
76 module_param(nflog, bool, 0400);
77 MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
79 /* global data structures */
82 unsigned int qlen; /* number of nlmsgs' in the skb */
83 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
84 struct sk_buff *skb; /* the pre-allocated skb */
85 struct timer_list timer; /* the timer function */
88 static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */
90 static struct sock *nflognl; /* our socket */
91 static DEFINE_SPINLOCK(ulog_lock); /* spinlock */
93 /* send one ulog_buff_t to userspace */
94 static void ulog_send(unsigned int nlgroupnum)
96 ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
98 if (timer_pending(&ub->timer)) {
99 DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
100 del_timer(&ub->timer);
104 DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
108 /* last nlmsg needs NLMSG_DONE */
110 ub->lastnlh->nlmsg_type = NLMSG_DONE;
112 NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1;
113 DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
114 ub->qlen, nlgroupnum + 1);
115 netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, GFP_ATOMIC);
123 /* timer function to flush queue in flushtimeout time */
124 static void ulog_timer(unsigned long data)
126 DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
128 /* lock to protect against somebody modifying our structure
129 * from ipt_ulog_target at the same time */
130 spin_lock_bh(&ulog_lock);
132 spin_unlock_bh(&ulog_lock);
135 static struct sk_buff *ulog_alloc_skb(unsigned int size)
140 /* alloc skb which should be big enough for a whole
141 * multipart message. WARNING: has to be <= 131000
142 * due to slab allocator restrictions */
144 n = max(size, nlbufsiz);
145 skb = alloc_skb(n, GFP_ATOMIC);
147 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n);
150 /* try to allocate only as much as we need for
153 skb = alloc_skb(size, GFP_ATOMIC);
155 PRINTR("ipt_ULOG: can't even allocate %ub\n",
163 static void ipt_ulog_packet(unsigned int hooknum,
164 const struct sk_buff *skb,
165 const struct net_device *in,
166 const struct net_device *out,
167 const struct ipt_ulog_info *loginfo,
171 ulog_packet_msg_t *pm;
172 size_t size, copy_len;
173 struct nlmsghdr *nlh;
176 /* ffs == find first bit set, necessary because userspace
177 * is already shifting groupnumber, but we need unshifted.
178 * ffs() returns [1..32], we need [0..31] */
179 unsigned int groupnum = ffs(loginfo->nl_group) - 1;
181 /* calculate the size of the skb needed */
182 if (loginfo->copy_range == 0 || loginfo->copy_range > skb->len)
185 copy_len = loginfo->copy_range;
187 size = NLMSG_SPACE(sizeof(*pm) + copy_len);
189 ub = &ulog_buffers[groupnum];
191 spin_lock_bh(&ulog_lock);
194 if (!(ub->skb = ulog_alloc_skb(size)))
196 } else if (ub->qlen >= loginfo->qthreshold ||
197 size > skb_tailroom(ub->skb)) {
198 /* either the queue len is too high or we don't have
199 * enough room in nlskb left. send it to userspace. */
203 if (!(ub->skb = ulog_alloc_skb(size)))
207 DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen,
208 loginfo->qthreshold);
210 /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
211 nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
212 sizeof(*pm)+copy_len);
215 pm = NLMSG_DATA(nlh);
217 /* We might not have a timestamp, get one */
218 if (skb->tstamp.tv64 == 0)
219 __net_timestamp((struct sk_buff *)skb);
221 /* copy hook, prefix, timestamp, payload, etc. */
222 pm->data_len = copy_len;
223 tv = ktime_to_timeval(skb->tstamp);
224 put_unaligned(tv.tv_sec, &pm->timestamp_sec);
225 put_unaligned(tv.tv_usec, &pm->timestamp_usec);
226 put_unaligned(skb->mark, &pm->mark);
229 strncpy(pm->prefix, prefix, sizeof(pm->prefix));
230 else if (loginfo->prefix[0] != '\0')
231 strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
233 *(pm->prefix) = '\0';
235 if (in && in->hard_header_len > 0
236 && skb->mac_header != skb->network_header
237 && in->hard_header_len <= ULOG_MAC_LEN) {
238 memcpy(pm->mac, skb_mac_header(skb), in->hard_header_len);
239 pm->mac_len = in->hard_header_len;
244 strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
246 pm->indev_name[0] = '\0';
249 strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
251 pm->outdev_name[0] = '\0';
253 /* copy_len <= skb->len, so can't fail. */
254 if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
257 /* check if we are building multi-part messages */
259 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
263 /* if timer isn't already running, start it */
264 if (!timer_pending(&ub->timer)) {
265 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
266 add_timer(&ub->timer);
269 /* if threshold is reached, send message to userspace */
270 if (ub->qlen >= loginfo->qthreshold) {
271 if (loginfo->qthreshold > 1)
272 nlh->nlmsg_type = NLMSG_DONE;
276 spin_unlock_bh(&ulog_lock);
281 PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
284 PRINTR("ipt_ULOG: Error building netlink message\n");
286 spin_unlock_bh(&ulog_lock);
289 static unsigned int ipt_ulog_target(struct sk_buff **pskb,
290 const struct net_device *in,
291 const struct net_device *out,
292 unsigned int hooknum,
293 const struct xt_target *target,
294 const void *targinfo)
296 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
298 ipt_ulog_packet(hooknum, *pskb, in, out, loginfo, NULL);
303 static void ipt_logfn(unsigned int pf,
304 unsigned int hooknum,
305 const struct sk_buff *skb,
306 const struct net_device *in,
307 const struct net_device *out,
308 const struct nf_loginfo *li,
311 struct ipt_ulog_info loginfo;
313 if (!li || li->type != NF_LOG_TYPE_ULOG) {
314 loginfo.nl_group = ULOG_DEFAULT_NLGROUP;
315 loginfo.copy_range = 0;
316 loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD;
317 loginfo.prefix[0] = '\0';
319 loginfo.nl_group = li->u.ulog.group;
320 loginfo.copy_range = li->u.ulog.copy_len;
321 loginfo.qthreshold = li->u.ulog.qthreshold;
322 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
325 ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
328 static bool ipt_ulog_checkentry(const char *tablename,
330 const struct xt_target *target,
332 unsigned int hookmask)
334 const struct ipt_ulog_info *loginfo = targinfo;
336 if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
337 DEBUGP("ipt_ULOG: prefix term %i\n",
338 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 struct compat_ipt_ulog_info {
351 compat_uint_t nl_group;
352 compat_size_t copy_range;
353 compat_size_t qthreshold;
354 char prefix[ULOG_PREFIX_LEN];
357 static void compat_from_user(void *dst, void *src)
359 const struct compat_ipt_ulog_info *cl = src;
360 struct ipt_ulog_info l = {
361 .nl_group = cl->nl_group,
362 .copy_range = cl->copy_range,
363 .qthreshold = cl->qthreshold,
366 memcpy(l.prefix, cl->prefix, sizeof(l.prefix));
367 memcpy(dst, &l, sizeof(l));
370 static int compat_to_user(void __user *dst, void *src)
372 const struct ipt_ulog_info *l = src;
373 struct compat_ipt_ulog_info cl = {
374 .nl_group = l->nl_group,
375 .copy_range = l->copy_range,
376 .qthreshold = l->qthreshold,
379 memcpy(cl.prefix, l->prefix, sizeof(cl.prefix));
380 return copy_to_user(dst, &cl, sizeof(cl)) ? -EFAULT : 0;
382 #endif /* CONFIG_COMPAT */
384 static struct xt_target ipt_ulog_reg = {
387 .target = ipt_ulog_target,
388 .targetsize = sizeof(struct ipt_ulog_info),
389 .checkentry = ipt_ulog_checkentry,
391 .compatsize = sizeof(struct compat_ipt_ulog_info),
392 .compat_from_user = compat_from_user,
393 .compat_to_user = compat_to_user,
398 static struct nf_logger ipt_ulog_logger = {
404 static int __init ipt_ulog_init(void)
408 DEBUGP("ipt_ULOG: init module\n");
410 if (nlbufsiz > 128*1024) {
411 printk("Netlink buffer has to be <= 128kB\n");
415 /* initialize ulog_buffers */
416 for (i = 0; i < ULOG_MAXNLGROUPS; i++)
417 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
419 nflognl = netlink_kernel_create(NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL,
424 ret = xt_register_target(&ipt_ulog_reg);
426 sock_release(nflognl->sk_socket);
430 nf_log_register(PF_INET, &ipt_ulog_logger);
435 static void __exit ipt_ulog_fini(void)
440 DEBUGP("ipt_ULOG: cleanup_module\n");
443 nf_log_unregister(&ipt_ulog_logger);
444 xt_unregister_target(&ipt_ulog_reg);
445 sock_release(nflognl->sk_socket);
447 /* remove pending timers and free allocated skb's */
448 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
449 ub = &ulog_buffers[i];
450 if (timer_pending(&ub->timer)) {
451 DEBUGP("timer was pending, deleting\n");
452 del_timer(&ub->timer);
462 module_init(ipt_ulog_init);
463 module_exit(ipt_ulog_fini);