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.
32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
33 #include <linux/module.h>
34 #include <linux/spinlock.h>
35 #include <linux/socket.h>
36 #include <linux/slab.h>
37 #include <linux/skbuff.h>
38 #include <linux/kernel.h>
39 #include <linux/timer.h>
40 #include <linux/netlink.h>
41 #include <linux/netdevice.h>
43 #include <linux/moduleparam.h>
44 #include <linux/netfilter.h>
45 #include <linux/netfilter/x_tables.h>
46 #include <linux/netfilter_ipv4/ipt_ULOG.h>
47 #include <net/netfilter/nf_log.h>
49 #include <linux/bitops.h>
50 #include <asm/unaligned.h>
52 MODULE_LICENSE("GPL");
53 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
54 MODULE_DESCRIPTION("Xtables: packet logging to netlink using ULOG");
55 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
57 #define ULOG_NL_EVENT 111 /* Harald's favorite number */
58 #define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
60 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
61 module_param(nlbufsiz, uint, 0400);
62 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
64 static unsigned int flushtimeout = 10;
65 module_param(flushtimeout, uint, 0600);
66 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
68 static bool nflog = true;
69 module_param(nflog, bool, 0400);
70 MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
72 /* global data structures */
75 unsigned int qlen; /* number of nlmsgs' in the skb */
76 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
77 struct sk_buff *skb; /* the pre-allocated skb */
78 struct timer_list timer; /* the timer function */
81 static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */
83 static struct sock *nflognl; /* our socket */
84 static DEFINE_SPINLOCK(ulog_lock); /* spinlock */
86 /* send one ulog_buff_t to userspace */
87 static void ulog_send(unsigned int nlgroupnum)
89 ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
91 if (timer_pending(&ub->timer)) {
92 pr_debug("ulog_send: timer was pending, deleting\n");
93 del_timer(&ub->timer);
97 pr_debug("ulog_send: nothing to send\n");
101 /* last nlmsg needs NLMSG_DONE */
103 ub->lastnlh->nlmsg_type = NLMSG_DONE;
105 NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1;
106 pr_debug("throwing %d packets to netlink group %u\n",
107 ub->qlen, nlgroupnum + 1);
108 netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, GFP_ATOMIC);
116 /* timer function to flush queue in flushtimeout time */
117 static void ulog_timer(unsigned long data)
119 pr_debug("timer function called, calling ulog_send\n");
121 /* lock to protect against somebody modifying our structure
122 * from ipt_ulog_target at the same time */
123 spin_lock_bh(&ulog_lock);
125 spin_unlock_bh(&ulog_lock);
128 static struct sk_buff *ulog_alloc_skb(unsigned int size)
133 /* alloc skb which should be big enough for a whole
134 * multipart message. WARNING: has to be <= 131000
135 * due to slab allocator restrictions */
137 n = max(size, nlbufsiz);
138 skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN);
141 /* try to allocate only as much as we need for
144 skb = alloc_skb(size, GFP_ATOMIC);
146 pr_debug("cannot even allocate %ub\n", size);
153 static void ipt_ulog_packet(unsigned int hooknum,
154 const struct sk_buff *skb,
155 const struct net_device *in,
156 const struct net_device *out,
157 const struct ipt_ulog_info *loginfo,
161 ulog_packet_msg_t *pm;
162 size_t size, copy_len;
163 struct nlmsghdr *nlh;
166 /* ffs == find first bit set, necessary because userspace
167 * is already shifting groupnumber, but we need unshifted.
168 * ffs() returns [1..32], we need [0..31] */
169 unsigned int groupnum = ffs(loginfo->nl_group) - 1;
171 /* calculate the size of the skb needed */
172 if (loginfo->copy_range == 0 || loginfo->copy_range > skb->len)
175 copy_len = loginfo->copy_range;
177 size = NLMSG_SPACE(sizeof(*pm) + copy_len);
179 ub = &ulog_buffers[groupnum];
181 spin_lock_bh(&ulog_lock);
184 if (!(ub->skb = ulog_alloc_skb(size)))
186 } else if (ub->qlen >= loginfo->qthreshold ||
187 size > skb_tailroom(ub->skb)) {
188 /* either the queue len is too high or we don't have
189 * enough room in nlskb left. send it to userspace. */
193 if (!(ub->skb = ulog_alloc_skb(size)))
197 pr_debug("qlen %d, qthreshold %Zu\n", ub->qlen, loginfo->qthreshold);
199 nlh = nlmsg_put(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
200 sizeof(*pm)+copy_len, 0);
202 pr_debug("error during nlmsg_put\n");
207 pm = nlmsg_data(nlh);
209 /* We might not have a timestamp, get one */
210 if (skb->tstamp.tv64 == 0)
211 __net_timestamp((struct sk_buff *)skb);
213 /* copy hook, prefix, timestamp, payload, etc. */
214 pm->data_len = copy_len;
215 tv = ktime_to_timeval(skb->tstamp);
216 put_unaligned(tv.tv_sec, &pm->timestamp_sec);
217 put_unaligned(tv.tv_usec, &pm->timestamp_usec);
218 put_unaligned(skb->mark, &pm->mark);
221 strncpy(pm->prefix, prefix, sizeof(pm->prefix));
222 else if (loginfo->prefix[0] != '\0')
223 strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
225 *(pm->prefix) = '\0';
227 if (in && in->hard_header_len > 0 &&
228 skb->mac_header != skb->network_header &&
229 in->hard_header_len <= ULOG_MAC_LEN) {
230 memcpy(pm->mac, skb_mac_header(skb), in->hard_header_len);
231 pm->mac_len = in->hard_header_len;
236 strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
238 pm->indev_name[0] = '\0';
241 strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
243 pm->outdev_name[0] = '\0';
245 /* copy_len <= skb->len, so can't fail. */
246 if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
249 /* check if we are building multi-part messages */
251 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
255 /* if timer isn't already running, start it */
256 if (!timer_pending(&ub->timer)) {
257 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
258 add_timer(&ub->timer);
261 /* if threshold is reached, send message to userspace */
262 if (ub->qlen >= loginfo->qthreshold) {
263 if (loginfo->qthreshold > 1)
264 nlh->nlmsg_type = NLMSG_DONE;
268 spin_unlock_bh(&ulog_lock);
273 pr_debug("Error building netlink message\n");
274 spin_unlock_bh(&ulog_lock);
278 ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
280 ipt_ulog_packet(par->hooknum, skb, par->in, par->out,
281 par->targinfo, NULL);
285 static void ipt_logfn(u_int8_t pf,
286 unsigned int hooknum,
287 const struct sk_buff *skb,
288 const struct net_device *in,
289 const struct net_device *out,
290 const struct nf_loginfo *li,
293 struct ipt_ulog_info loginfo;
295 if (!li || li->type != NF_LOG_TYPE_ULOG) {
296 loginfo.nl_group = ULOG_DEFAULT_NLGROUP;
297 loginfo.copy_range = 0;
298 loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD;
299 loginfo.prefix[0] = '\0';
301 loginfo.nl_group = li->u.ulog.group;
302 loginfo.copy_range = li->u.ulog.copy_len;
303 loginfo.qthreshold = li->u.ulog.qthreshold;
304 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
307 ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
310 static int ulog_tg_check(const struct xt_tgchk_param *par)
312 const struct ipt_ulog_info *loginfo = par->targinfo;
314 if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
315 pr_debug("prefix not null-terminated\n");
318 if (loginfo->qthreshold > ULOG_MAX_QLEN) {
319 pr_debug("queue threshold %Zu > MAX_QLEN\n",
320 loginfo->qthreshold);
327 struct compat_ipt_ulog_info {
328 compat_uint_t nl_group;
329 compat_size_t copy_range;
330 compat_size_t qthreshold;
331 char prefix[ULOG_PREFIX_LEN];
334 static void ulog_tg_compat_from_user(void *dst, const void *src)
336 const struct compat_ipt_ulog_info *cl = src;
337 struct ipt_ulog_info l = {
338 .nl_group = cl->nl_group,
339 .copy_range = cl->copy_range,
340 .qthreshold = cl->qthreshold,
343 memcpy(l.prefix, cl->prefix, sizeof(l.prefix));
344 memcpy(dst, &l, sizeof(l));
347 static int ulog_tg_compat_to_user(void __user *dst, const void *src)
349 const struct ipt_ulog_info *l = src;
350 struct compat_ipt_ulog_info cl = {
351 .nl_group = l->nl_group,
352 .copy_range = l->copy_range,
353 .qthreshold = l->qthreshold,
356 memcpy(cl.prefix, l->prefix, sizeof(cl.prefix));
357 return copy_to_user(dst, &cl, sizeof(cl)) ? -EFAULT : 0;
359 #endif /* CONFIG_COMPAT */
361 static struct xt_target ulog_tg_reg __read_mostly = {
363 .family = NFPROTO_IPV4,
365 .targetsize = sizeof(struct ipt_ulog_info),
366 .checkentry = ulog_tg_check,
368 .compatsize = sizeof(struct compat_ipt_ulog_info),
369 .compat_from_user = ulog_tg_compat_from_user,
370 .compat_to_user = ulog_tg_compat_to_user,
375 static struct nf_logger ipt_ulog_logger __read_mostly = {
381 static int __init ulog_tg_init(void)
384 struct netlink_kernel_cfg cfg = {
385 .groups = ULOG_MAXNLGROUPS,
388 pr_debug("init module\n");
390 if (nlbufsiz > 128*1024) {
391 pr_warning("Netlink buffer has to be <= 128kB\n");
395 /* initialize ulog_buffers */
396 for (i = 0; i < ULOG_MAXNLGROUPS; i++)
397 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
399 nflognl = netlink_kernel_create(&init_net, NETLINK_NFLOG, &cfg);
403 ret = xt_register_target(&ulog_tg_reg);
405 netlink_kernel_release(nflognl);
409 nf_log_register(NFPROTO_IPV4, &ipt_ulog_logger);
414 static void __exit ulog_tg_exit(void)
419 pr_debug("cleanup_module\n");
422 nf_log_unregister(&ipt_ulog_logger);
423 xt_unregister_target(&ulog_tg_reg);
424 netlink_kernel_release(nflognl);
426 /* remove pending timers and free allocated skb's */
427 for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
428 ub = &ulog_buffers[i];
429 if (timer_pending(&ub->timer)) {
430 pr_debug("timer was pending, deleting\n");
431 del_timer(&ub->timer);
441 module_init(ulog_tg_init);
442 module_exit(ulog_tg_exit);