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
,
404 ret
= xt_register_target(&ulog_tg_reg
);
406 netlink_kernel_release(nflognl
);
410 nf_log_register(NFPROTO_IPV4
, &ipt_ulog_logger
);
415 static void __exit
ulog_tg_exit(void)
420 pr_debug("cleanup_module\n");
423 nf_log_unregister(&ipt_ulog_logger
);
424 xt_unregister_target(&ulog_tg_reg
);
425 netlink_kernel_release(nflognl
);
427 /* remove pending timers and free allocated skb's */
428 for (i
= 0; i
< ULOG_MAXNLGROUPS
; i
++) {
429 ub
= &ulog_buffers
[i
];
430 if (timer_pending(&ub
->timer
)) {
431 pr_debug("timer was pending, deleting\n");
432 del_timer(&ub
->timer
);
442 module_init(ulog_tg_init
);
443 module_exit(ulog_tg_exit
);