2 * netfilter module for userspace bridged Ethernet frames logging daemons
5 * Bart De Schuymer <bdschuym@pandora.be>
6 * Harald Welte <laforge@netfilter.org>
10 * Based on ipt_ULOG.c, which is
11 * (C) 2000-2002 by Harald Welte <laforge@netfilter.org>
13 * This module accepts two parameters:
16 * The parameter specifies how big the buffer for each netlink multicast
17 * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
18 * get accumulated in the kernel until they are sent to userspace. It is
19 * NOT possible to allocate more than 128kB, and it is strongly discouraged,
20 * because atomically allocating 128kB inside the network rx softirq is not
21 * reliable. Please also keep in mind that this buffer size is allocated for
22 * each nlgroup you are using, so the total kernel memory usage increases
26 * Specify, after how many hundredths of a second the queue should be
27 * flushed even if it is not full yet.
30 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31 #include <linux/module.h>
32 #include <linux/slab.h>
33 #include <linux/spinlock.h>
34 #include <linux/socket.h>
35 #include <linux/skbuff.h>
36 #include <linux/kernel.h>
37 #include <linux/timer.h>
38 #include <net/netlink.h>
39 #include <linux/netdevice.h>
40 #include <linux/netfilter/x_tables.h>
41 #include <linux/netfilter_bridge/ebtables.h>
42 #include <linux/netfilter_bridge/ebt_ulog.h>
43 #include <net/netfilter/nf_log.h>
44 #include <net/netns/generic.h>
46 #include "../br_private.h"
48 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
49 module_param(nlbufsiz, uint, 0600);
50 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
51 "(defaults to 4096)");
53 static unsigned int flushtimeout = 10;
54 module_param(flushtimeout, uint, 0600);
55 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
59 unsigned int qlen; /* number of nlmsgs' in the skb */
60 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
61 struct sk_buff *skb; /* the pre-allocated skb */
62 struct timer_list timer; /* the timer function */
63 spinlock_t lock; /* the per-queue lock */
66 static int ebt_ulog_net_id __read_mostly;
68 unsigned int nlgroup[EBT_ULOG_MAXNLGROUPS];
69 ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
70 struct sock *ebtulognl;
73 static struct ebt_ulog_net *ebt_ulog_pernet(struct net *net)
75 return net_generic(net, ebt_ulog_net_id);
78 /* send one ulog_buff_t to userspace */
79 static void ulog_send(struct ebt_ulog_net *ebt, unsigned int nlgroup)
81 ebt_ulog_buff_t *ub = &ebt->ulog_buffers[nlgroup];
83 del_timer(&ub->timer);
88 /* last nlmsg needs NLMSG_DONE */
90 ub->lastnlh->nlmsg_type = NLMSG_DONE;
92 NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
93 netlink_broadcast(ebt->ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
99 /* timer function to flush queue in flushtimeout time */
100 static void ulog_timer(unsigned long data)
102 struct ebt_ulog_net *ebt = container_of((void *)data,
104 nlgroup[*(unsigned int *)data]);
106 ebt_ulog_buff_t *ub = &ebt->ulog_buffers[*(unsigned int *)data];
107 spin_lock_bh(&ub->lock);
109 ulog_send(ebt, *(unsigned int *)data);
110 spin_unlock_bh(&ub->lock);
113 static struct sk_buff *ulog_alloc_skb(unsigned int size)
118 n = max(size, nlbufsiz);
119 skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN);
122 /* try to allocate only as much as we need for
124 skb = alloc_skb(size, GFP_ATOMIC);
126 pr_debug("cannot even allocate buffer of size %ub\n",
134 static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
135 const struct net_device *in, const struct net_device *out,
136 const struct ebt_ulog_info *uloginfo, const char *prefix)
138 ebt_ulog_packet_msg_t *pm;
139 size_t size, copy_len;
140 struct nlmsghdr *nlh;
141 struct net *net = dev_net(in ? in : out);
142 struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
143 unsigned int group = uloginfo->nlgroup;
144 ebt_ulog_buff_t *ub = &ebt->ulog_buffers[group];
145 spinlock_t *lock = &ub->lock;
148 if ((uloginfo->cprange == 0) ||
149 (uloginfo->cprange > skb->len + ETH_HLEN))
150 copy_len = skb->len + ETH_HLEN;
152 copy_len = uloginfo->cprange;
154 size = nlmsg_total_size(sizeof(*pm) + copy_len);
155 if (size > nlbufsiz) {
156 pr_debug("Size %Zd needed, but nlbufsiz=%d\n", size, nlbufsiz);
163 if (!(ub->skb = ulog_alloc_skb(size)))
165 } else if (size > skb_tailroom(ub->skb)) {
166 ulog_send(ebt, group);
168 if (!(ub->skb = ulog_alloc_skb(size)))
172 nlh = nlmsg_put(ub->skb, 0, ub->qlen, 0,
173 size - NLMSG_ALIGN(sizeof(*nlh)), 0);
181 pm = nlmsg_data(nlh);
183 /* Fill in the ulog data */
184 pm->version = EBT_ULOG_VERSION;
185 kt = ktime_get_real();
186 pm->stamp = ktime_to_timeval(kt);
188 ub->skb->tstamp = kt;
189 pm->data_len = copy_len;
190 pm->mark = skb->mark;
192 if (uloginfo->prefix != NULL)
193 strcpy(pm->prefix, uloginfo->prefix);
195 *(pm->prefix) = '\0';
198 strcpy(pm->physindev, in->name);
199 /* If in isn't a bridge, then physindev==indev */
200 if (br_port_exists(in))
201 /* rcu_read_lock()ed by nf_hook_slow */
202 strcpy(pm->indev, br_port_get_rcu(in)->br->dev->name);
204 strcpy(pm->indev, in->name);
206 pm->indev[0] = pm->physindev[0] = '\0';
209 /* If out exists, then out is a bridge port */
210 strcpy(pm->physoutdev, out->name);
211 /* rcu_read_lock()ed by nf_hook_slow */
212 strcpy(pm->outdev, br_port_get_rcu(out)->br->dev->name);
214 pm->outdev[0] = pm->physoutdev[0] = '\0';
216 if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
220 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
224 if (ub->qlen >= uloginfo->qthreshold)
225 ulog_send(ebt, group);
226 else if (!timer_pending(&ub->timer)) {
227 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
228 add_timer(&ub->timer);
232 spin_unlock_bh(lock);
235 /* this function is registered with the netfilter core */
236 static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
237 const struct sk_buff *skb, const struct net_device *in,
238 const struct net_device *out, const struct nf_loginfo *li,
241 struct ebt_ulog_info loginfo;
243 if (!li || li->type != NF_LOG_TYPE_ULOG) {
244 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
246 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
247 loginfo.prefix[0] = '\0';
249 loginfo.nlgroup = li->u.ulog.group;
250 loginfo.cprange = li->u.ulog.copy_len;
251 loginfo.qthreshold = li->u.ulog.qthreshold;
252 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
255 ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
259 ebt_ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
261 ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
262 par->targinfo, NULL);
266 static int ebt_ulog_tg_check(const struct xt_tgchk_param *par)
268 struct ebt_ulog_info *uloginfo = par->targinfo;
270 if (uloginfo->nlgroup > 31)
273 uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
275 if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
276 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
281 static struct xt_target ebt_ulog_tg_reg __read_mostly = {
284 .family = NFPROTO_BRIDGE,
285 .target = ebt_ulog_tg,
286 .checkentry = ebt_ulog_tg_check,
287 .targetsize = sizeof(struct ebt_ulog_info),
291 static struct nf_logger ebt_ulog_logger __read_mostly = {
293 .logfn = &ebt_log_packet,
297 static int __net_init ebt_ulog_net_init(struct net *net)
300 struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
302 struct netlink_kernel_cfg cfg = {
303 .groups = EBT_ULOG_MAXNLGROUPS,
306 /* initialize ulog_buffers */
307 for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
309 setup_timer(&ebt->ulog_buffers[i].timer, ulog_timer,
310 (unsigned long)&ebt->nlgroup[i]);
311 spin_lock_init(&ebt->ulog_buffers[i].lock);
314 ebt->ebtulognl = netlink_kernel_create(net, NETLINK_NFLOG, &cfg);
318 nf_log_set(net, NFPROTO_BRIDGE, &ebt_ulog_logger);
322 static void __net_exit ebt_ulog_net_fini(struct net *net)
325 struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
327 nf_log_unset(net, &ebt_ulog_logger);
328 for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
329 ebt_ulog_buff_t *ub = &ebt->ulog_buffers[i];
330 del_timer(&ub->timer);
337 netlink_kernel_release(ebt->ebtulognl);
340 static struct pernet_operations ebt_ulog_net_ops = {
341 .init = ebt_ulog_net_init,
342 .exit = ebt_ulog_net_fini,
343 .id = &ebt_ulog_net_id,
344 .size = sizeof(struct ebt_ulog_net),
347 static int __init ebt_ulog_init(void)
351 if (nlbufsiz >= 128*1024) {
352 pr_warn("Netlink buffer has to be <= 128kB,"
353 "please try a smaller nlbufsiz parameter.\n");
357 ret = register_pernet_subsys(&ebt_ulog_net_ops);
361 ret = xt_register_target(&ebt_ulog_tg_reg);
365 nf_log_register(NFPROTO_BRIDGE, &ebt_ulog_logger);
370 unregister_pernet_subsys(&ebt_ulog_net_ops);
375 static void __exit ebt_ulog_fini(void)
377 nf_log_unregister(&ebt_ulog_logger);
378 xt_unregister_target(&ebt_ulog_tg_reg);
379 unregister_pernet_subsys(&ebt_ulog_net_ops);
382 module_init(ebt_ulog_init);
383 module_exit(ebt_ulog_fini);
384 MODULE_LICENSE("GPL");
385 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
386 MODULE_DESCRIPTION("Ebtables: Packet logging to netlink using ULOG");