1 /*
2 * netfilter module for userspace bridged Ethernet frames logging daemons
3 *
4 * Authors:
5 * Bart De Schuymer <bdschuym@pandora.be>
6 * Harald Welte <laforge@netfilter.org>
7 *
8 * November, 2004
9 *
10 * Based on ipt_ULOG.c, which is
11 * (C) 2000-2002 by Harald Welte <laforge@netfilter.org>
12 *
13 * This module accepts two parameters:
14 *
15 * nlbufsiz:
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
23 * by that factor.
24 *
25 * flushtimeout:
26 * Specify, after how many hundredths of a second the queue should be
27 * flushed even if it is not full yet.
28 *
29 */
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>
44 #include <net/sock.h>
45 #include "../br_private.h"
46
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)");
51
52 static unsigned int flushtimeout = 10;
53 module_param(flushtimeout, uint, 0600);
54 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
55 "(defaults to 10)");
56
57 typedef struct {
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 */
63 } ebt_ulog_buff_t;
64
65 static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
66 static struct sock *ebtulognl;
67
68 /* send one ulog_buff_t to userspace */
ulog_send(unsigned int nlgroup)69 static void ulog_send(unsigned int nlgroup)
70 {
71 ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup];
72
73 if (timer_pending(&ub->timer))
74 del_timer(&ub->timer);
75
76 if (!ub->skb)
77 return;
78
79 /* last nlmsg needs NLMSG_DONE */
80 if (ub->qlen > 1)
81 ub->lastnlh->nlmsg_type = NLMSG_DONE;
82
83 NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
84 netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
85
86 ub->qlen = 0;
87 ub->skb = NULL;
88 }
89
90 /* timer function to flush queue in flushtimeout time */
ulog_timer(unsigned long data)91 static void ulog_timer(unsigned long data)
92 {
93 spin_lock_bh(&ulog_buffers[data].lock);
94 if (ulog_buffers[data].skb)
95 ulog_send(data);
96 spin_unlock_bh(&ulog_buffers[data].lock);
97 }
98
ulog_alloc_skb(unsigned int size)99 static struct sk_buff *ulog_alloc_skb(unsigned int size)
100 {
101 struct sk_buff *skb;
102 unsigned int n;
103
104 n = max(size, nlbufsiz);
105 skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN);
106 if (!skb) {
107 if (n > size) {
108 /* try to allocate only as much as we need for
109 * current packet */
110 skb = alloc_skb(size, GFP_ATOMIC);
111 if (!skb)
112 pr_debug("cannot even allocate buffer of size %ub\n",
113 size);
114 }
115 }
116
117 return skb;
118 }
119
ebt_ulog_packet(unsigned int hooknr,const struct sk_buff * skb,const struct net_device * in,const struct net_device * out,const struct ebt_ulog_info * uloginfo,const char * prefix)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)
123 {
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;
130 ktime_t kt;
131
132 if ((uloginfo->cprange == 0) ||
133 (uloginfo->cprange > skb->len + ETH_HLEN))
134 copy_len = skb->len + ETH_HLEN;
135 else
136 copy_len = uloginfo->cprange;
137
138 size = NLMSG_SPACE(sizeof(*pm) + copy_len);
139 if (size > nlbufsiz) {
140 pr_debug("Size %Zd needed, but nlbufsiz=%d\n", size, nlbufsiz);
141 return;
142 }
143
144 spin_lock_bh(lock);
145
146 if (!ub->skb) {
147 if (!(ub->skb = ulog_alloc_skb(size)))
148 goto alloc_failure;
149 } else if (size > skb_tailroom(ub->skb)) {
150 ulog_send(group);
151
152 if (!(ub->skb = ulog_alloc_skb(size)))
153 goto alloc_failure;
154 }
155
156 nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0,
157 size - NLMSG_ALIGN(sizeof(*nlh)));
158 ub->qlen++;
159
160 pm = NLMSG_DATA(nlh);
161
162 /* Fill in the ulog data */
163 pm->version = EBT_ULOG_VERSION;
164 kt = ktime_get_real();
165 pm->stamp = ktime_to_timeval(kt);
166 if (ub->qlen == 1)
167 ub->skb->tstamp = kt;
168 pm->data_len = copy_len;
169 pm->mark = skb->mark;
170 pm->hook = hooknr;
171 if (uloginfo->prefix != NULL)
172 strcpy(pm->prefix, uloginfo->prefix);
173 else
174 *(pm->prefix) = '\0';
175
176 if (in) {
177 strcpy(pm->physindev, in->name);
178 /* If in isn't a bridge, then physindev==indev */
179 if (br_port_exists(in))
180 /* rcu_read_lock()ed by nf_hook_slow */
181 strcpy(pm->indev, br_port_get_rcu(in)->br->dev->name);
182 else
183 strcpy(pm->indev, in->name);
184 } else
185 pm->indev[0] = pm->physindev[0] = '\0';
186
187 if (out) {
188 /* If out exists, then out is a bridge port */
189 strcpy(pm->physoutdev, out->name);
190 /* rcu_read_lock()ed by nf_hook_slow */
191 strcpy(pm->outdev, br_port_get_rcu(out)->br->dev->name);
192 } else
193 pm->outdev[0] = pm->physoutdev[0] = '\0';
194
195 if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
196 BUG();
197
198 if (ub->qlen > 1)
199 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
200
201 ub->lastnlh = nlh;
202
203 if (ub->qlen >= uloginfo->qthreshold)
204 ulog_send(group);
205 else if (!timer_pending(&ub->timer)) {
206 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
207 add_timer(&ub->timer);
208 }
209
210 unlock:
211 spin_unlock_bh(lock);
212
213 return;
214
215 nlmsg_failure:
216 pr_debug("error during NLMSG_PUT. This should "
217 "not happen, please report to author.\n");
218 alloc_failure:
219 goto unlock;
220 }
221
222 /* this function is registered with the netfilter core */
ebt_log_packet(u_int8_t pf,unsigned int hooknum,const struct sk_buff * skb,const struct net_device * in,const struct net_device * out,const struct nf_loginfo * li,const char * prefix)223 static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
224 const struct sk_buff *skb, const struct net_device *in,
225 const struct net_device *out, const struct nf_loginfo *li,
226 const char *prefix)
227 {
228 struct ebt_ulog_info loginfo;
229
230 if (!li || li->type != NF_LOG_TYPE_ULOG) {
231 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
232 loginfo.cprange = 0;
233 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
234 loginfo.prefix[0] = '\0';
235 } else {
236 loginfo.nlgroup = li->u.ulog.group;
237 loginfo.cprange = li->u.ulog.copy_len;
238 loginfo.qthreshold = li->u.ulog.qthreshold;
239 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
240 }
241
242 ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
243 }
244
245 static unsigned int
ebt_ulog_tg(struct sk_buff * skb,const struct xt_action_param * par)246 ebt_ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
247 {
248 ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
249 par->targinfo, NULL);
250 return EBT_CONTINUE;
251 }
252
ebt_ulog_tg_check(const struct xt_tgchk_param * par)253 static int ebt_ulog_tg_check(const struct xt_tgchk_param *par)
254 {
255 struct ebt_ulog_info *uloginfo = par->targinfo;
256
257 if (uloginfo->nlgroup > 31)
258 return -EINVAL;
259
260 uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
261
262 if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
263 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
264
265 return 0;
266 }
267
268 static struct xt_target ebt_ulog_tg_reg __read_mostly = {
269 .name = "ulog",
270 .revision = 0,
271 .family = NFPROTO_BRIDGE,
272 .target = ebt_ulog_tg,
273 .checkentry = ebt_ulog_tg_check,
274 .targetsize = sizeof(struct ebt_ulog_info),
275 .me = THIS_MODULE,
276 };
277
278 static struct nf_logger ebt_ulog_logger __read_mostly = {
279 .name = "ebt_ulog",
280 .logfn = &ebt_log_packet,
281 .me = THIS_MODULE,
282 };
283
ebt_ulog_init(void)284 static int __init ebt_ulog_init(void)
285 {
286 int ret;
287 int i;
288
289 if (nlbufsiz >= 128*1024) {
290 pr_warning("Netlink buffer has to be <= 128kB,"
291 " please try a smaller nlbufsiz parameter.\n");
292 return -EINVAL;
293 }
294
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);
299 }
300
301 ebtulognl = netlink_kernel_create(&init_net, NETLINK_NFLOG,
302 EBT_ULOG_MAXNLGROUPS, NULL, NULL,
303 THIS_MODULE);
304 if (!ebtulognl)
305 ret = -ENOMEM;
306 else if ((ret = xt_register_target(&ebt_ulog_tg_reg)) != 0)
307 netlink_kernel_release(ebtulognl);
308
309 if (ret == 0)
310 nf_log_register(NFPROTO_BRIDGE, &ebt_ulog_logger);
311
312 return ret;
313 }
314
ebt_ulog_fini(void)315 static void __exit ebt_ulog_fini(void)
316 {
317 ebt_ulog_buff_t *ub;
318 int i;
319
320 nf_log_unregister(&ebt_ulog_logger);
321 xt_unregister_target(&ebt_ulog_tg_reg);
322 for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
323 ub = &ulog_buffers[i];
324 if (timer_pending(&ub->timer))
325 del_timer(&ub->timer);
326 spin_lock_bh(&ub->lock);
327 if (ub->skb) {
328 kfree_skb(ub->skb);
329 ub->skb = NULL;
330 }
331 spin_unlock_bh(&ub->lock);
332 }
333 netlink_kernel_release(ebtulognl);
334 }
335
336 module_init(ebt_ulog_init);
337 module_exit(ebt_ulog_fini);
338 MODULE_LICENSE("GPL");
339 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
340 MODULE_DESCRIPTION("Ebtables: Packet logging to netlink using ULOG");
341