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 <linux/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>
45 #include "../br_private.h"
47 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
48 module_param(nlbufsiz, uint, 0600);
49 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
50 "(defaults to 4096)");
52 static unsigned int flushtimeout = 10;
53 module_param(flushtimeout, uint, 0600);
54 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
58 unsigned int qlen; /* number of nlmsgs' in the skb */
59 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
60 struct sk_buff *skb; /* the pre-allocated skb */
61 struct timer_list timer; /* the timer function */
62 spinlock_t lock; /* the per-queue lock */
65 static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
66 static struct sock *ebtulognl;
68 /* send one ulog_buff_t to userspace */
69 static void ulog_send(unsigned int nlgroup)
71 ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup];
73 if (timer_pending(&ub->timer))
74 del_timer(&ub->timer);
79 /* last nlmsg needs NLMSG_DONE */
81 ub->lastnlh->nlmsg_type = NLMSG_DONE;
83 NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
84 netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
90 /* timer function to flush queue in flushtimeout time */
91 static void ulog_timer(unsigned long data)
93 spin_lock_bh(&ulog_buffers[data].lock);
94 if (ulog_buffers[data].skb)
96 spin_unlock_bh(&ulog_buffers[data].lock);
99 static struct sk_buff *ulog_alloc_skb(unsigned int size)
104 n = max(size, nlbufsiz);
105 skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN);
108 /* try to allocate only as much as we need for
110 skb = alloc_skb(size, GFP_ATOMIC);
112 pr_debug("cannot even allocate buffer of size %ub\n",
120 static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
121 const struct net_device *in, const struct net_device *out,
122 const struct ebt_ulog_info *uloginfo, const char *prefix)
124 ebt_ulog_packet_msg_t *pm;
125 size_t size, copy_len;
126 struct nlmsghdr *nlh;
127 unsigned int group = uloginfo->nlgroup;
128 ebt_ulog_buff_t *ub = &ulog_buffers[group];
129 spinlock_t *lock = &ub->lock;
132 if ((uloginfo->cprange == 0) ||
133 (uloginfo->cprange > skb->len + ETH_HLEN))
134 copy_len = skb->len + ETH_HLEN;
136 copy_len = uloginfo->cprange;
138 size = NLMSG_SPACE(sizeof(*pm) + copy_len);
139 if (size > nlbufsiz) {
140 pr_debug("Size %Zd needed, but nlbufsiz=%d\n", size, nlbufsiz);
147 if (!(ub->skb = ulog_alloc_skb(size)))
149 } else if (size > skb_tailroom(ub->skb)) {
152 if (!(ub->skb = ulog_alloc_skb(size)))
156 nlh = nlmsg_put(ub->skb, 0, ub->qlen, 0,
157 size - NLMSG_ALIGN(sizeof(*nlh)), 0);
165 pm = nlmsg_data(nlh);
167 /* Fill in the ulog data */
168 pm->version = EBT_ULOG_VERSION;
169 kt = ktime_get_real();
170 pm->stamp = ktime_to_timeval(kt);
172 ub->skb->tstamp = kt;
173 pm->data_len = copy_len;
174 pm->mark = skb->mark;
176 if (uloginfo->prefix != NULL)
177 strcpy(pm->prefix, uloginfo->prefix);
179 *(pm->prefix) = '\0';
182 strcpy(pm->physindev, in->name);
183 /* If in isn't a bridge, then physindev==indev */
184 if (br_port_exists(in))
185 /* rcu_read_lock()ed by nf_hook_slow */
186 strcpy(pm->indev, br_port_get_rcu(in)->br->dev->name);
188 strcpy(pm->indev, in->name);
190 pm->indev[0] = pm->physindev[0] = '\0';
193 /* If out exists, then out is a bridge port */
194 strcpy(pm->physoutdev, out->name);
195 /* rcu_read_lock()ed by nf_hook_slow */
196 strcpy(pm->outdev, br_port_get_rcu(out)->br->dev->name);
198 pm->outdev[0] = pm->physoutdev[0] = '\0';
200 if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
204 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
208 if (ub->qlen >= uloginfo->qthreshold)
210 else if (!timer_pending(&ub->timer)) {
211 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
212 add_timer(&ub->timer);
216 spin_unlock_bh(lock);
219 /* this function is registered with the netfilter core */
220 static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
221 const struct sk_buff *skb, const struct net_device *in,
222 const struct net_device *out, const struct nf_loginfo *li,
225 struct ebt_ulog_info loginfo;
227 if (!li || li->type != NF_LOG_TYPE_ULOG) {
228 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
230 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
231 loginfo.prefix[0] = '\0';
233 loginfo.nlgroup = li->u.ulog.group;
234 loginfo.cprange = li->u.ulog.copy_len;
235 loginfo.qthreshold = li->u.ulog.qthreshold;
236 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
239 ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
243 ebt_ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
245 ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
246 par->targinfo, NULL);
250 static int ebt_ulog_tg_check(const struct xt_tgchk_param *par)
252 struct ebt_ulog_info *uloginfo = par->targinfo;
254 if (uloginfo->nlgroup > 31)
257 uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
259 if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
260 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
265 static struct xt_target ebt_ulog_tg_reg __read_mostly = {
268 .family = NFPROTO_BRIDGE,
269 .target = ebt_ulog_tg,
270 .checkentry = ebt_ulog_tg_check,
271 .targetsize = sizeof(struct ebt_ulog_info),
275 static struct nf_logger ebt_ulog_logger __read_mostly = {
277 .logfn = &ebt_log_packet,
281 static int __init ebt_ulog_init(void)
285 struct netlink_kernel_cfg cfg = {
286 .groups = EBT_ULOG_MAXNLGROUPS,
289 if (nlbufsiz >= 128*1024) {
290 pr_warning("Netlink buffer has to be <= 128kB,"
291 " please try a smaller nlbufsiz parameter.\n");
295 /* initialize ulog_buffers */
296 for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
297 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
298 spin_lock_init(&ulog_buffers[i].lock);
301 ebtulognl = netlink_kernel_create(&init_net, NETLINK_NFLOG, &cfg);
304 else if ((ret = xt_register_target(&ebt_ulog_tg_reg)) != 0)
305 netlink_kernel_release(ebtulognl);
308 nf_log_register(NFPROTO_BRIDGE, &ebt_ulog_logger);
313 static void __exit ebt_ulog_fini(void)
318 nf_log_unregister(&ebt_ulog_logger);
319 xt_unregister_target(&ebt_ulog_tg_reg);
320 for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
321 ub = &ulog_buffers[i];
322 if (timer_pending(&ub->timer))
323 del_timer(&ub->timer);
324 spin_lock_bh(&ub->lock);
329 spin_unlock_bh(&ub->lock);
331 netlink_kernel_release(ebtulognl);
334 module_init(ebt_ulog_init);
335 module_exit(ebt_ulog_fini);
336 MODULE_LICENSE("GPL");
337 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
338 MODULE_DESCRIPTION("Ebtables: Packet logging to netlink using ULOG");