xref: /linux/net/netfilter/nf_log.c (revision 52338415) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/kernel.h>
3 #include <linux/init.h>
4 #include <linux/module.h>
5 #include <linux/proc_fs.h>
6 #include <linux/skbuff.h>
7 #include <linux/netfilter.h>
8 #include <linux/seq_file.h>
9 #include <net/protocol.h>
10 #include <net/netfilter/nf_log.h>
11 
12 #include "nf_internals.h"
13 
14 /* Internal logging interface, which relies on the real
15    LOG target modules */
16 
17 #define NFLOGGER_NAME_LEN		64
18 
19 int sysctl_nf_log_all_netns __read_mostly;
20 EXPORT_SYMBOL(sysctl_nf_log_all_netns);
21 
22 static struct nf_logger __rcu *loggers[NFPROTO_NUMPROTO][NF_LOG_TYPE_MAX] __read_mostly;
23 static DEFINE_MUTEX(nf_log_mutex);
24 
25 #define nft_log_dereference(logger) \
26 	rcu_dereference_protected(logger, lockdep_is_held(&nf_log_mutex))
27 
28 static struct nf_logger *__find_logger(int pf, const char *str_logger)
29 {
30 	struct nf_logger *log;
31 	int i;
32 
33 	for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
34 		if (loggers[pf][i] == NULL)
35 			continue;
36 
37 		log = nft_log_dereference(loggers[pf][i]);
38 		if (!strncasecmp(str_logger, log->name, strlen(log->name)))
39 			return log;
40 	}
41 
42 	return NULL;
43 }
44 
45 int nf_log_set(struct net *net, u_int8_t pf, const struct nf_logger *logger)
46 {
47 	const struct nf_logger *log;
48 
49 	if (pf == NFPROTO_UNSPEC || pf >= ARRAY_SIZE(net->nf.nf_loggers))
50 		return -EOPNOTSUPP;
51 
52 	mutex_lock(&nf_log_mutex);
53 	log = nft_log_dereference(net->nf.nf_loggers[pf]);
54 	if (log == NULL)
55 		rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
56 
57 	mutex_unlock(&nf_log_mutex);
58 
59 	return 0;
60 }
61 EXPORT_SYMBOL(nf_log_set);
62 
63 void nf_log_unset(struct net *net, const struct nf_logger *logger)
64 {
65 	int i;
66 	const struct nf_logger *log;
67 
68 	mutex_lock(&nf_log_mutex);
69 	for (i = 0; i < NFPROTO_NUMPROTO; i++) {
70 		log = nft_log_dereference(net->nf.nf_loggers[i]);
71 		if (log == logger)
72 			RCU_INIT_POINTER(net->nf.nf_loggers[i], NULL);
73 	}
74 	mutex_unlock(&nf_log_mutex);
75 }
76 EXPORT_SYMBOL(nf_log_unset);
77 
78 /* return EEXIST if the same logger is registered, 0 on success. */
79 int nf_log_register(u_int8_t pf, struct nf_logger *logger)
80 {
81 	int i;
82 	int ret = 0;
83 
84 	if (pf >= ARRAY_SIZE(init_net.nf.nf_loggers))
85 		return -EINVAL;
86 
87 	mutex_lock(&nf_log_mutex);
88 
89 	if (pf == NFPROTO_UNSPEC) {
90 		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
91 			if (rcu_access_pointer(loggers[i][logger->type])) {
92 				ret = -EEXIST;
93 				goto unlock;
94 			}
95 		}
96 		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
97 			rcu_assign_pointer(loggers[i][logger->type], logger);
98 	} else {
99 		if (rcu_access_pointer(loggers[pf][logger->type])) {
100 			ret = -EEXIST;
101 			goto unlock;
102 		}
103 		rcu_assign_pointer(loggers[pf][logger->type], logger);
104 	}
105 
106 unlock:
107 	mutex_unlock(&nf_log_mutex);
108 	return ret;
109 }
110 EXPORT_SYMBOL(nf_log_register);
111 
112 void nf_log_unregister(struct nf_logger *logger)
113 {
114 	const struct nf_logger *log;
115 	int i;
116 
117 	mutex_lock(&nf_log_mutex);
118 	for (i = 0; i < NFPROTO_NUMPROTO; i++) {
119 		log = nft_log_dereference(loggers[i][logger->type]);
120 		if (log == logger)
121 			RCU_INIT_POINTER(loggers[i][logger->type], NULL);
122 	}
123 	mutex_unlock(&nf_log_mutex);
124 	synchronize_rcu();
125 }
126 EXPORT_SYMBOL(nf_log_unregister);
127 
128 int nf_log_bind_pf(struct net *net, u_int8_t pf,
129 		   const struct nf_logger *logger)
130 {
131 	if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
132 		return -EINVAL;
133 	mutex_lock(&nf_log_mutex);
134 	if (__find_logger(pf, logger->name) == NULL) {
135 		mutex_unlock(&nf_log_mutex);
136 		return -ENOENT;
137 	}
138 	rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
139 	mutex_unlock(&nf_log_mutex);
140 	return 0;
141 }
142 EXPORT_SYMBOL(nf_log_bind_pf);
143 
144 void nf_log_unbind_pf(struct net *net, u_int8_t pf)
145 {
146 	if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
147 		return;
148 	mutex_lock(&nf_log_mutex);
149 	RCU_INIT_POINTER(net->nf.nf_loggers[pf], NULL);
150 	mutex_unlock(&nf_log_mutex);
151 }
152 EXPORT_SYMBOL(nf_log_unbind_pf);
153 
154 void nf_logger_request_module(int pf, enum nf_log_type type)
155 {
156 	if (loggers[pf][type] == NULL)
157 		request_module("nf-logger-%u-%u", pf, type);
158 }
159 EXPORT_SYMBOL_GPL(nf_logger_request_module);
160 
161 int nf_logger_find_get(int pf, enum nf_log_type type)
162 {
163 	struct nf_logger *logger;
164 	int ret = -ENOENT;
165 
166 	if (pf == NFPROTO_INET) {
167 		ret = nf_logger_find_get(NFPROTO_IPV4, type);
168 		if (ret < 0)
169 			return ret;
170 
171 		ret = nf_logger_find_get(NFPROTO_IPV6, type);
172 		if (ret < 0) {
173 			nf_logger_put(NFPROTO_IPV4, type);
174 			return ret;
175 		}
176 
177 		return 0;
178 	}
179 
180 	if (rcu_access_pointer(loggers[pf][type]) == NULL)
181 		request_module("nf-logger-%u-%u", pf, type);
182 
183 	rcu_read_lock();
184 	logger = rcu_dereference(loggers[pf][type]);
185 	if (logger == NULL)
186 		goto out;
187 
188 	if (try_module_get(logger->me))
189 		ret = 0;
190 out:
191 	rcu_read_unlock();
192 	return ret;
193 }
194 EXPORT_SYMBOL_GPL(nf_logger_find_get);
195 
196 void nf_logger_put(int pf, enum nf_log_type type)
197 {
198 	struct nf_logger *logger;
199 
200 	if (pf == NFPROTO_INET) {
201 		nf_logger_put(NFPROTO_IPV4, type);
202 		nf_logger_put(NFPROTO_IPV6, type);
203 		return;
204 	}
205 
206 	BUG_ON(loggers[pf][type] == NULL);
207 
208 	rcu_read_lock();
209 	logger = rcu_dereference(loggers[pf][type]);
210 	module_put(logger->me);
211 	rcu_read_unlock();
212 }
213 EXPORT_SYMBOL_GPL(nf_logger_put);
214 
215 void nf_log_packet(struct net *net,
216 		   u_int8_t pf,
217 		   unsigned int hooknum,
218 		   const struct sk_buff *skb,
219 		   const struct net_device *in,
220 		   const struct net_device *out,
221 		   const struct nf_loginfo *loginfo,
222 		   const char *fmt, ...)
223 {
224 	va_list args;
225 	char prefix[NF_LOG_PREFIXLEN];
226 	const struct nf_logger *logger;
227 
228 	rcu_read_lock();
229 	if (loginfo != NULL)
230 		logger = rcu_dereference(loggers[pf][loginfo->type]);
231 	else
232 		logger = rcu_dereference(net->nf.nf_loggers[pf]);
233 
234 	if (logger) {
235 		va_start(args, fmt);
236 		vsnprintf(prefix, sizeof(prefix), fmt, args);
237 		va_end(args);
238 		logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
239 	}
240 	rcu_read_unlock();
241 }
242 EXPORT_SYMBOL(nf_log_packet);
243 
244 void nf_log_trace(struct net *net,
245 		  u_int8_t pf,
246 		  unsigned int hooknum,
247 		  const struct sk_buff *skb,
248 		  const struct net_device *in,
249 		  const struct net_device *out,
250 		  const struct nf_loginfo *loginfo, const char *fmt, ...)
251 {
252 	va_list args;
253 	char prefix[NF_LOG_PREFIXLEN];
254 	const struct nf_logger *logger;
255 
256 	rcu_read_lock();
257 	logger = rcu_dereference(net->nf.nf_loggers[pf]);
258 	if (logger) {
259 		va_start(args, fmt);
260 		vsnprintf(prefix, sizeof(prefix), fmt, args);
261 		va_end(args);
262 		logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
263 	}
264 	rcu_read_unlock();
265 }
266 EXPORT_SYMBOL(nf_log_trace);
267 
268 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
269 
270 struct nf_log_buf {
271 	unsigned int	count;
272 	char		buf[S_SIZE + 1];
273 };
274 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
275 
276 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
277 {
278 	va_list args;
279 	int len;
280 
281 	if (likely(m->count < S_SIZE)) {
282 		va_start(args, f);
283 		len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
284 		va_end(args);
285 		if (likely(m->count + len < S_SIZE)) {
286 			m->count += len;
287 			return 0;
288 		}
289 	}
290 	m->count = S_SIZE;
291 	printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
292 	return -1;
293 }
294 EXPORT_SYMBOL_GPL(nf_log_buf_add);
295 
296 struct nf_log_buf *nf_log_buf_open(void)
297 {
298 	struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
299 
300 	if (unlikely(!m)) {
301 		local_bh_disable();
302 		do {
303 			m = xchg(&emergency_ptr, NULL);
304 		} while (!m);
305 	}
306 	m->count = 0;
307 	return m;
308 }
309 EXPORT_SYMBOL_GPL(nf_log_buf_open);
310 
311 void nf_log_buf_close(struct nf_log_buf *m)
312 {
313 	m->buf[m->count] = 0;
314 	printk("%s\n", m->buf);
315 
316 	if (likely(m != &emergency))
317 		kfree(m);
318 	else {
319 		emergency_ptr = m;
320 		local_bh_enable();
321 	}
322 }
323 EXPORT_SYMBOL_GPL(nf_log_buf_close);
324 
325 #ifdef CONFIG_PROC_FS
326 static void *seq_start(struct seq_file *seq, loff_t *pos)
327 {
328 	struct net *net = seq_file_net(seq);
329 
330 	mutex_lock(&nf_log_mutex);
331 
332 	if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
333 		return NULL;
334 
335 	return pos;
336 }
337 
338 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
339 {
340 	struct net *net = seq_file_net(s);
341 
342 	(*pos)++;
343 
344 	if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
345 		return NULL;
346 
347 	return pos;
348 }
349 
350 static void seq_stop(struct seq_file *s, void *v)
351 {
352 	mutex_unlock(&nf_log_mutex);
353 }
354 
355 static int seq_show(struct seq_file *s, void *v)
356 {
357 	loff_t *pos = v;
358 	const struct nf_logger *logger;
359 	int i;
360 	struct net *net = seq_file_net(s);
361 
362 	logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
363 
364 	if (!logger)
365 		seq_printf(s, "%2lld NONE (", *pos);
366 	else
367 		seq_printf(s, "%2lld %s (", *pos, logger->name);
368 
369 	if (seq_has_overflowed(s))
370 		return -ENOSPC;
371 
372 	for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
373 		if (loggers[*pos][i] == NULL)
374 			continue;
375 
376 		logger = nft_log_dereference(loggers[*pos][i]);
377 		seq_puts(s, logger->name);
378 		if (i == 0 && loggers[*pos][i + 1] != NULL)
379 			seq_puts(s, ",");
380 
381 		if (seq_has_overflowed(s))
382 			return -ENOSPC;
383 	}
384 
385 	seq_puts(s, ")\n");
386 
387 	if (seq_has_overflowed(s))
388 		return -ENOSPC;
389 	return 0;
390 }
391 
392 static const struct seq_operations nflog_seq_ops = {
393 	.start	= seq_start,
394 	.next	= seq_next,
395 	.stop	= seq_stop,
396 	.show	= seq_show,
397 };
398 #endif /* PROC_FS */
399 
400 #ifdef CONFIG_SYSCTL
401 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
402 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
403 static struct ctl_table_header *nf_log_sysctl_fhdr;
404 
405 static struct ctl_table nf_log_sysctl_ftable[] = {
406 	{
407 		.procname	= "nf_log_all_netns",
408 		.data		= &sysctl_nf_log_all_netns,
409 		.maxlen		= sizeof(sysctl_nf_log_all_netns),
410 		.mode		= 0644,
411 		.proc_handler	= proc_dointvec,
412 	},
413 	{ }
414 };
415 
416 static int nf_log_proc_dostring(struct ctl_table *table, int write,
417 			 void __user *buffer, size_t *lenp, loff_t *ppos)
418 {
419 	const struct nf_logger *logger;
420 	char buf[NFLOGGER_NAME_LEN];
421 	int r = 0;
422 	int tindex = (unsigned long)table->extra1;
423 	struct net *net = table->extra2;
424 
425 	if (write) {
426 		struct ctl_table tmp = *table;
427 
428 		/* proc_dostring() can append to existing strings, so we need to
429 		 * initialize it as an empty string.
430 		 */
431 		buf[0] = '\0';
432 		tmp.data = buf;
433 		r = proc_dostring(&tmp, write, buffer, lenp, ppos);
434 		if (r)
435 			return r;
436 
437 		if (!strcmp(buf, "NONE")) {
438 			nf_log_unbind_pf(net, tindex);
439 			return 0;
440 		}
441 		mutex_lock(&nf_log_mutex);
442 		logger = __find_logger(tindex, buf);
443 		if (logger == NULL) {
444 			mutex_unlock(&nf_log_mutex);
445 			return -ENOENT;
446 		}
447 		rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
448 		mutex_unlock(&nf_log_mutex);
449 	} else {
450 		struct ctl_table tmp = *table;
451 
452 		tmp.data = buf;
453 		mutex_lock(&nf_log_mutex);
454 		logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
455 		if (!logger)
456 			strlcpy(buf, "NONE", sizeof(buf));
457 		else
458 			strlcpy(buf, logger->name, sizeof(buf));
459 		mutex_unlock(&nf_log_mutex);
460 		r = proc_dostring(&tmp, write, buffer, lenp, ppos);
461 	}
462 
463 	return r;
464 }
465 
466 static int netfilter_log_sysctl_init(struct net *net)
467 {
468 	int i;
469 	struct ctl_table *table;
470 
471 	table = nf_log_sysctl_table;
472 	if (!net_eq(net, &init_net)) {
473 		table = kmemdup(nf_log_sysctl_table,
474 				 sizeof(nf_log_sysctl_table),
475 				 GFP_KERNEL);
476 		if (!table)
477 			goto err_alloc;
478 	} else {
479 		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
480 			snprintf(nf_log_sysctl_fnames[i],
481 				 3, "%d", i);
482 			nf_log_sysctl_table[i].procname	=
483 				nf_log_sysctl_fnames[i];
484 			nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
485 			nf_log_sysctl_table[i].mode = 0644;
486 			nf_log_sysctl_table[i].proc_handler =
487 				nf_log_proc_dostring;
488 			nf_log_sysctl_table[i].extra1 =
489 				(void *)(unsigned long) i;
490 		}
491 		nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
492 							 nf_log_sysctl_ftable);
493 		if (!nf_log_sysctl_fhdr)
494 			goto err_freg;
495 	}
496 
497 	for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
498 		table[i].extra2 = net;
499 
500 	net->nf.nf_log_dir_header = register_net_sysctl(net,
501 						"net/netfilter/nf_log",
502 						table);
503 	if (!net->nf.nf_log_dir_header)
504 		goto err_reg;
505 
506 	return 0;
507 
508 err_reg:
509 	if (!net_eq(net, &init_net))
510 		kfree(table);
511 	else
512 		unregister_net_sysctl_table(nf_log_sysctl_fhdr);
513 err_freg:
514 err_alloc:
515 	return -ENOMEM;
516 }
517 
518 static void netfilter_log_sysctl_exit(struct net *net)
519 {
520 	struct ctl_table *table;
521 
522 	table = net->nf.nf_log_dir_header->ctl_table_arg;
523 	unregister_net_sysctl_table(net->nf.nf_log_dir_header);
524 	if (!net_eq(net, &init_net))
525 		kfree(table);
526 	else
527 		unregister_net_sysctl_table(nf_log_sysctl_fhdr);
528 }
529 #else
530 static int netfilter_log_sysctl_init(struct net *net)
531 {
532 	return 0;
533 }
534 
535 static void netfilter_log_sysctl_exit(struct net *net)
536 {
537 }
538 #endif /* CONFIG_SYSCTL */
539 
540 static int __net_init nf_log_net_init(struct net *net)
541 {
542 	int ret = -ENOMEM;
543 
544 #ifdef CONFIG_PROC_FS
545 	if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
546 			&nflog_seq_ops, sizeof(struct seq_net_private)))
547 		return ret;
548 #endif
549 	ret = netfilter_log_sysctl_init(net);
550 	if (ret < 0)
551 		goto out_sysctl;
552 
553 	return 0;
554 
555 out_sysctl:
556 #ifdef CONFIG_PROC_FS
557 	remove_proc_entry("nf_log", net->nf.proc_netfilter);
558 #endif
559 	return ret;
560 }
561 
562 static void __net_exit nf_log_net_exit(struct net *net)
563 {
564 	netfilter_log_sysctl_exit(net);
565 #ifdef CONFIG_PROC_FS
566 	remove_proc_entry("nf_log", net->nf.proc_netfilter);
567 #endif
568 }
569 
570 static struct pernet_operations nf_log_net_ops = {
571 	.init = nf_log_net_init,
572 	.exit = nf_log_net_exit,
573 };
574 
575 int __init netfilter_log_init(void)
576 {
577 	return register_pernet_subsys(&nf_log_net_ops);
578 }
579