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
);
119 /* last nlmsg needs NLMSG_DONE */
121 ub
->lastnlh
->nlmsg_type
= NLMSG_DONE
;
123 NETLINK_CB(ub
->skb
).dst_group
= nlgroupnum
+ 1;
124 DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
125 ub
->qlen
, nlgroupnum
+ 1);
126 netlink_broadcast(nflognl
, ub
->skb
, 0, nlgroupnum
+ 1, GFP_ATOMIC
);
135 /* timer function to flush queue in flushtimeout time */
136 static void ulog_timer(unsigned long data
)
138 DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
140 /* lock to protect against somebody modifying our structure
141 * from ipt_ulog_target at the same time */
142 spin_lock_bh(&ulog_lock
);
144 spin_unlock_bh(&ulog_lock
);
147 static struct sk_buff
*ulog_alloc_skb(unsigned int size
)
152 /* alloc skb which should be big enough for a whole
153 * multipart message. WARNING: has to be <= 131000
154 * due to slab allocator restrictions */
156 n
= max(size
, nlbufsiz
);
157 skb
= alloc_skb(n
, GFP_ATOMIC
);
159 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n
);
162 /* try to allocate only as much as we need for
165 skb
= alloc_skb(size
, GFP_ATOMIC
);
167 PRINTR("ipt_ULOG: can't even allocate %ub\n",
175 static void ipt_ulog_packet(unsigned int hooknum
,
176 const struct sk_buff
*skb
,
177 const struct net_device
*in
,
178 const struct net_device
*out
,
179 const struct ipt_ulog_info
*loginfo
,
183 ulog_packet_msg_t
*pm
;
184 size_t size
, copy_len
;
185 struct nlmsghdr
*nlh
;
187 /* ffs == find first bit set, necessary because userspace
188 * is already shifting groupnumber, but we need unshifted.
189 * ffs() returns [1..32], we need [0..31] */
190 unsigned int groupnum
= ffs(loginfo
->nl_group
) - 1;
192 /* calculate the size of the skb needed */
193 if ((loginfo
->copy_range
== 0) ||
194 (loginfo
->copy_range
> skb
->len
)) {
197 copy_len
= loginfo
->copy_range
;
200 size
= NLMSG_SPACE(sizeof(*pm
) + copy_len
);
202 ub
= &ulog_buffers
[groupnum
];
204 spin_lock_bh(&ulog_lock
);
207 if (!(ub
->skb
= ulog_alloc_skb(size
)))
209 } else if (ub
->qlen
>= loginfo
->qthreshold
||
210 size
> skb_tailroom(ub
->skb
)) {
211 /* either the queue len is too high or we don't have
212 * enough room in nlskb left. send it to userspace. */
216 if (!(ub
->skb
= ulog_alloc_skb(size
)))
220 DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub
->qlen
,
221 loginfo
->qthreshold
);
223 /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
224 nlh
= NLMSG_PUT(ub
->skb
, 0, ub
->qlen
, ULOG_NL_EVENT
,
225 sizeof(*pm
)+copy_len
);
228 pm
= NLMSG_DATA(nlh
);
230 /* We might not have a timestamp, get one */
231 if (skb
->tstamp
.off_sec
== 0)
232 __net_timestamp((struct sk_buff
*)skb
);
234 /* copy hook, prefix, timestamp, payload, etc. */
235 pm
->data_len
= copy_len
;
236 pm
->timestamp_sec
= skb
->tstamp
.off_sec
;
237 pm
->timestamp_usec
= skb
->tstamp
.off_usec
;
238 pm
->mark
= skb
->nfmark
;
241 strncpy(pm
->prefix
, prefix
, sizeof(pm
->prefix
));
242 else if (loginfo
->prefix
[0] != '\0')
243 strncpy(pm
->prefix
, loginfo
->prefix
, sizeof(pm
->prefix
));
245 *(pm
->prefix
) = '\0';
247 if (in
&& in
->hard_header_len
> 0
248 && skb
->mac
.raw
!= (void *) skb
->nh
.iph
249 && in
->hard_header_len
<= ULOG_MAC_LEN
) {
250 memcpy(pm
->mac
, skb
->mac
.raw
, in
->hard_header_len
);
251 pm
->mac_len
= in
->hard_header_len
;
256 strncpy(pm
->indev_name
, in
->name
, sizeof(pm
->indev_name
));
258 pm
->indev_name
[0] = '\0';
261 strncpy(pm
->outdev_name
, out
->name
, sizeof(pm
->outdev_name
));
263 pm
->outdev_name
[0] = '\0';
265 /* copy_len <= skb->len, so can't fail. */
266 if (skb_copy_bits(skb
, 0, pm
->payload
, copy_len
) < 0)
269 /* check if we are building multi-part messages */
271 ub
->lastnlh
->nlmsg_flags
|= NLM_F_MULTI
;
276 /* if timer isn't already running, start it */
277 if (!timer_pending(&ub
->timer
)) {
278 ub
->timer
.expires
= jiffies
+ flushtimeout
* HZ
/ 100;
279 add_timer(&ub
->timer
);
282 /* if threshold is reached, send message to userspace */
283 if (ub
->qlen
>= loginfo
->qthreshold
) {
284 if (loginfo
->qthreshold
> 1)
285 nlh
->nlmsg_type
= NLMSG_DONE
;
289 spin_unlock_bh(&ulog_lock
);
294 PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
297 PRINTR("ipt_ULOG: Error building netlink message\n");
299 spin_unlock_bh(&ulog_lock
);
302 static unsigned int ipt_ulog_target(struct sk_buff
**pskb
,
303 const struct net_device
*in
,
304 const struct net_device
*out
,
305 unsigned int hooknum
,
306 const void *targinfo
, void *userinfo
)
308 struct ipt_ulog_info
*loginfo
= (struct ipt_ulog_info
*) targinfo
;
310 ipt_ulog_packet(hooknum
, *pskb
, in
, out
, loginfo
, NULL
);
315 static void ipt_logfn(unsigned int pf
,
316 unsigned int hooknum
,
317 const struct sk_buff
*skb
,
318 const struct net_device
*in
,
319 const struct net_device
*out
,
320 const struct nf_loginfo
*li
,
323 struct ipt_ulog_info loginfo
;
325 if (!li
|| li
->type
!= NF_LOG_TYPE_ULOG
) {
326 loginfo
.nl_group
= ULOG_DEFAULT_NLGROUP
;
327 loginfo
.copy_range
= 0;
328 loginfo
.qthreshold
= ULOG_DEFAULT_QTHRESHOLD
;
329 loginfo
.prefix
[0] = '\0';
331 loginfo
.nl_group
= li
->u
.ulog
.group
;
332 loginfo
.copy_range
= li
->u
.ulog
.copy_len
;
333 loginfo
.qthreshold
= li
->u
.ulog
.qthreshold
;
334 strlcpy(loginfo
.prefix
, prefix
, sizeof(loginfo
.prefix
));
337 ipt_ulog_packet(hooknum
, skb
, in
, out
, &loginfo
, prefix
);
340 static int ipt_ulog_checkentry(const char *tablename
,
343 unsigned int targinfosize
,
344 unsigned int hookmask
)
346 struct ipt_ulog_info
*loginfo
= (struct ipt_ulog_info
*) targinfo
;
348 if (targinfosize
!= IPT_ALIGN(sizeof(struct ipt_ulog_info
))) {
349 DEBUGP("ipt_ULOG: targinfosize %u != 0\n", targinfosize
);
353 if (loginfo
->prefix
[sizeof(loginfo
->prefix
) - 1] != '\0') {
354 DEBUGP("ipt_ULOG: prefix term %i\n",
355 loginfo
->prefix
[sizeof(loginfo
->prefix
) - 1]);
359 if (loginfo
->qthreshold
> ULOG_MAX_QLEN
) {
360 DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
361 loginfo
->qthreshold
);
368 static struct ipt_target ipt_ulog_reg
= {
370 .target
= ipt_ulog_target
,
371 .checkentry
= ipt_ulog_checkentry
,
375 static struct nf_logger ipt_ulog_logger
= {
381 static int __init
init(void)
385 DEBUGP("ipt_ULOG: init module\n");
387 if (nlbufsiz
> 128*1024) {
388 printk("Netlink buffer has to be <= 128kB\n");
392 /* initialize ulog_buffers */
393 for (i
= 0; i
< ULOG_MAXNLGROUPS
; i
++) {
394 init_timer(&ulog_buffers
[i
].timer
);
395 ulog_buffers
[i
].timer
.function
= ulog_timer
;
396 ulog_buffers
[i
].timer
.data
= i
;
399 nflognl
= netlink_kernel_create(NETLINK_NFLOG
, ULOG_MAXNLGROUPS
, NULL
,
404 if (ipt_register_target(&ipt_ulog_reg
) != 0) {
405 sock_release(nflognl
->sk_socket
);
409 nf_log_register(PF_INET
, &ipt_ulog_logger
);
414 static void __exit
fini(void)
419 DEBUGP("ipt_ULOG: cleanup_module\n");
422 nf_log_unregister_logger(&ipt_ulog_logger
);
423 ipt_unregister_target(&ipt_ulog_reg
);
424 sock_release(nflognl
->sk_socket
);
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 DEBUGP("timer was pending, deleting\n");
431 del_timer(&ub
->timer
);