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/spinlock.h>
51 #include <linux/socket.h>
52 #include <linux/skbuff.h>
53 #include <linux/kernel.h>
54 #include <linux/timer.h>
55 #include <linux/netlink.h>
56 #include <linux/netdevice.h>
58 #include <linux/moduleparam.h>
59 #include <linux/netfilter.h>
60 #include <linux/netfilter_ipv4/ip_tables.h>
61 #include <linux/netfilter_ipv4/ipt_ULOG.h>
63 #include <linux/bitops.h>
65 MODULE_LICENSE("GPL");
66 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
67 MODULE_DESCRIPTION("iptables userspace logging module");
68 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK
, NETLINK_NFLOG
);
70 #define ULOG_NL_EVENT 111 /* Harald's favorite number */
71 #define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
74 #define DEBUGP(format, args...) printk("%s:%s:" format, \
75 __FILE__, __FUNCTION__ , ## args)
77 #define DEBUGP(format, args...)
80 #define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
82 static unsigned int nlbufsiz
= NLMSG_GOODSIZE
;
83 module_param(nlbufsiz
, uint
, 0400);
84 MODULE_PARM_DESC(nlbufsiz
, "netlink buffer size");
86 static unsigned int flushtimeout
= 10;
87 module_param(flushtimeout
, uint
, 0600);
88 MODULE_PARM_DESC(flushtimeout
, "buffer flush timeout (hundredths of a second)");
91 module_param(nflog
, bool, 0400);
92 MODULE_PARM_DESC(nflog
, "register as internal netfilter logging module");
94 /* global data structures */
97 unsigned int qlen
; /* number of nlmsgs' in the skb */
98 struct nlmsghdr
*lastnlh
; /* netlink header of last msg in skb */
99 struct sk_buff
*skb
; /* the pre-allocated skb */
100 struct timer_list timer
; /* the timer function */
103 static ulog_buff_t ulog_buffers
[ULOG_MAXNLGROUPS
]; /* array of buffers */
105 static struct sock
*nflognl
; /* our socket */
106 static DEFINE_SPINLOCK(ulog_lock
); /* spinlock */
108 /* send one ulog_buff_t to userspace */
109 static void ulog_send(unsigned int nlgroupnum
)
111 ulog_buff_t
*ub
= &ulog_buffers
[nlgroupnum
];
113 if (timer_pending(&ub
->timer
)) {
114 DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
115 del_timer(&ub
->timer
);
119 DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
123 /* last nlmsg needs NLMSG_DONE */
125 ub
->lastnlh
->nlmsg_type
= NLMSG_DONE
;
127 NETLINK_CB(ub
->skb
).dst_group
= nlgroupnum
+ 1;
128 DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
129 ub
->qlen
, nlgroupnum
+ 1);
130 netlink_broadcast(nflognl
, ub
->skb
, 0, nlgroupnum
+ 1, GFP_ATOMIC
);
139 /* timer function to flush queue in flushtimeout time */
140 static void ulog_timer(unsigned long data
)
142 DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
144 /* lock to protect against somebody modifying our structure
145 * from ipt_ulog_target at the same time */
146 spin_lock_bh(&ulog_lock
);
148 spin_unlock_bh(&ulog_lock
);
151 static struct sk_buff
*ulog_alloc_skb(unsigned int size
)
156 /* alloc skb which should be big enough for a whole
157 * multipart message. WARNING: has to be <= 131000
158 * due to slab allocator restrictions */
160 n
= max(size
, nlbufsiz
);
161 skb
= alloc_skb(n
, GFP_ATOMIC
);
163 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n
);
166 /* try to allocate only as much as we need for
169 skb
= alloc_skb(size
, GFP_ATOMIC
);
171 PRINTR("ipt_ULOG: can't even allocate %ub\n",
179 static void ipt_ulog_packet(unsigned int hooknum
,
180 const struct sk_buff
*skb
,
181 const struct net_device
*in
,
182 const struct net_device
*out
,
183 const struct ipt_ulog_info
*loginfo
,
187 ulog_packet_msg_t
*pm
;
188 size_t size
, copy_len
;
189 struct nlmsghdr
*nlh
;
191 /* ffs == find first bit set, necessary because userspace
192 * is already shifting groupnumber, but we need unshifted.
193 * ffs() returns [1..32], we need [0..31] */
194 unsigned int groupnum
= ffs(loginfo
->nl_group
) - 1;
196 /* calculate the size of the skb needed */
197 if ((loginfo
->copy_range
== 0) ||
198 (loginfo
->copy_range
> skb
->len
)) {
201 copy_len
= loginfo
->copy_range
;
204 size
= NLMSG_SPACE(sizeof(*pm
) + copy_len
);
206 ub
= &ulog_buffers
[groupnum
];
208 spin_lock_bh(&ulog_lock
);
211 if (!(ub
->skb
= ulog_alloc_skb(size
)))
213 } else if (ub
->qlen
>= loginfo
->qthreshold
||
214 size
> skb_tailroom(ub
->skb
)) {
215 /* either the queue len is too high or we don't have
216 * enough room in nlskb left. send it to userspace. */
220 if (!(ub
->skb
= ulog_alloc_skb(size
)))
224 DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub
->qlen
,
225 loginfo
->qthreshold
);
227 /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
228 nlh
= NLMSG_PUT(ub
->skb
, 0, ub
->qlen
, ULOG_NL_EVENT
,
229 sizeof(*pm
)+copy_len
);
232 pm
= NLMSG_DATA(nlh
);
234 /* We might not have a timestamp, get one */
235 if (skb
->tstamp
.off_sec
== 0)
236 __net_timestamp((struct sk_buff
*)skb
);
238 /* copy hook, prefix, timestamp, payload, etc. */
239 pm
->data_len
= copy_len
;
240 pm
->timestamp_sec
= skb
->tstamp
.off_sec
;
241 pm
->timestamp_usec
= skb
->tstamp
.off_usec
;
242 pm
->mark
= skb
->mark
;
245 strncpy(pm
->prefix
, prefix
, sizeof(pm
->prefix
));
246 else if (loginfo
->prefix
[0] != '\0')
247 strncpy(pm
->prefix
, loginfo
->prefix
, sizeof(pm
->prefix
));
249 *(pm
->prefix
) = '\0';
251 if (in
&& in
->hard_header_len
> 0
252 && skb
->mac
.raw
!= (void *) skb
->nh
.iph
253 && in
->hard_header_len
<= ULOG_MAC_LEN
) {
254 memcpy(pm
->mac
, skb
->mac
.raw
, in
->hard_header_len
);
255 pm
->mac_len
= in
->hard_header_len
;
260 strncpy(pm
->indev_name
, in
->name
, sizeof(pm
->indev_name
));
262 pm
->indev_name
[0] = '\0';
265 strncpy(pm
->outdev_name
, out
->name
, sizeof(pm
->outdev_name
));
267 pm
->outdev_name
[0] = '\0';
269 /* copy_len <= skb->len, so can't fail. */
270 if (skb_copy_bits(skb
, 0, pm
->payload
, copy_len
) < 0)
273 /* check if we are building multi-part messages */
275 ub
->lastnlh
->nlmsg_flags
|= NLM_F_MULTI
;
280 /* if timer isn't already running, start it */
281 if (!timer_pending(&ub
->timer
)) {
282 ub
->timer
.expires
= jiffies
+ flushtimeout
* HZ
/ 100;
283 add_timer(&ub
->timer
);
286 /* if threshold is reached, send message to userspace */
287 if (ub
->qlen
>= loginfo
->qthreshold
) {
288 if (loginfo
->qthreshold
> 1)
289 nlh
->nlmsg_type
= NLMSG_DONE
;
293 spin_unlock_bh(&ulog_lock
);
298 PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
301 PRINTR("ipt_ULOG: Error building netlink message\n");
303 spin_unlock_bh(&ulog_lock
);
306 static unsigned int ipt_ulog_target(struct sk_buff
**pskb
,
307 const struct net_device
*in
,
308 const struct net_device
*out
,
309 unsigned int hooknum
,
310 const struct xt_target
*target
,
311 const void *targinfo
)
313 struct ipt_ulog_info
*loginfo
= (struct ipt_ulog_info
*) targinfo
;
315 ipt_ulog_packet(hooknum
, *pskb
, in
, out
, loginfo
, NULL
);
320 static void ipt_logfn(unsigned int pf
,
321 unsigned int hooknum
,
322 const struct sk_buff
*skb
,
323 const struct net_device
*in
,
324 const struct net_device
*out
,
325 const struct nf_loginfo
*li
,
328 struct ipt_ulog_info loginfo
;
330 if (!li
|| li
->type
!= NF_LOG_TYPE_ULOG
) {
331 loginfo
.nl_group
= ULOG_DEFAULT_NLGROUP
;
332 loginfo
.copy_range
= 0;
333 loginfo
.qthreshold
= ULOG_DEFAULT_QTHRESHOLD
;
334 loginfo
.prefix
[0] = '\0';
336 loginfo
.nl_group
= li
->u
.ulog
.group
;
337 loginfo
.copy_range
= li
->u
.ulog
.copy_len
;
338 loginfo
.qthreshold
= li
->u
.ulog
.qthreshold
;
339 strlcpy(loginfo
.prefix
, prefix
, sizeof(loginfo
.prefix
));
342 ipt_ulog_packet(hooknum
, skb
, in
, out
, &loginfo
, prefix
);
345 static int ipt_ulog_checkentry(const char *tablename
,
347 const struct xt_target
*target
,
349 unsigned int hookmask
)
351 struct ipt_ulog_info
*loginfo
= (struct ipt_ulog_info
*) targinfo
;
353 if (loginfo
->prefix
[sizeof(loginfo
->prefix
) - 1] != '\0') {
354 DEBUGP("ipt_ULOG: prefix term %i\n",
355 loginfo
->prefix
[sizeof(loginfo
->prefix
) - 1]);
358 if (loginfo
->qthreshold
> ULOG_MAX_QLEN
) {
359 DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
360 loginfo
->qthreshold
);
366 static struct ipt_target ipt_ulog_reg
= {
368 .target
= ipt_ulog_target
,
369 .targetsize
= sizeof(struct ipt_ulog_info
),
370 .checkentry
= ipt_ulog_checkentry
,
374 static struct nf_logger ipt_ulog_logger
= {
380 static int __init
ipt_ulog_init(void)
384 DEBUGP("ipt_ULOG: init module\n");
386 if (nlbufsiz
> 128*1024) {
387 printk("Netlink buffer has to be <= 128kB\n");
391 /* initialize ulog_buffers */
392 for (i
= 0; i
< ULOG_MAXNLGROUPS
; i
++) {
393 init_timer(&ulog_buffers
[i
].timer
);
394 ulog_buffers
[i
].timer
.function
= ulog_timer
;
395 ulog_buffers
[i
].timer
.data
= i
;
398 nflognl
= netlink_kernel_create(NETLINK_NFLOG
, ULOG_MAXNLGROUPS
, NULL
,
403 if (ipt_register_target(&ipt_ulog_reg
) != 0) {
404 sock_release(nflognl
->sk_socket
);
408 nf_log_register(PF_INET
, &ipt_ulog_logger
);
413 static void __exit
ipt_ulog_fini(void)
418 DEBUGP("ipt_ULOG: cleanup_module\n");
421 nf_log_unregister_logger(&ipt_ulog_logger
);
422 ipt_unregister_target(&ipt_ulog_reg
);
423 sock_release(nflognl
->sk_socket
);
425 /* remove pending timers and free allocated skb's */
426 for (i
= 0; i
< ULOG_MAXNLGROUPS
; i
++) {
427 ub
= &ulog_buffers
[i
];
428 if (timer_pending(&ub
->timer
)) {
429 DEBUGP("timer was pending, deleting\n");
430 del_timer(&ub
->timer
);
441 module_init(ipt_ulog_init
);
442 module_exit(ipt_ulog_fini
);