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 
__find_logger(int pf,const char * str_logger)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 
nf_log_set(struct net * net,u_int8_t pf,const struct nf_logger * logger)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 
nf_log_unset(struct net * net,const struct nf_logger * logger)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. */
nf_log_register(u_int8_t pf,struct nf_logger * logger)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 
nf_log_unregister(struct nf_logger * logger)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 
nf_log_bind_pf(struct net * net,u_int8_t pf,const struct nf_logger * logger)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 
nf_log_unbind_pf(struct net * net,u_int8_t pf)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 
nf_logger_find_get(int pf,enum nf_log_type type)154 int nf_logger_find_get(int pf, enum nf_log_type type)
155 {
156 	struct nf_logger *logger;
157 	int ret = -ENOENT;
158 
159 	if (pf == NFPROTO_INET) {
160 		ret = nf_logger_find_get(NFPROTO_IPV4, type);
161 		if (ret < 0)
162 			return ret;
163 
164 		ret = nf_logger_find_get(NFPROTO_IPV6, type);
165 		if (ret < 0) {
166 			nf_logger_put(NFPROTO_IPV4, type);
167 			return ret;
168 		}
169 
170 		return 0;
171 	}
172 
173 	rcu_read_lock();
174 	logger = rcu_dereference(loggers[pf][type]);
175 	if (logger == NULL)
176 		goto out;
177 
178 	if (try_module_get(logger->me))
179 		ret = 0;
180 out:
181 	rcu_read_unlock();
182 	return ret;
183 }
184 EXPORT_SYMBOL_GPL(nf_logger_find_get);
185 
nf_logger_put(int pf,enum nf_log_type type)186 void nf_logger_put(int pf, enum nf_log_type type)
187 {
188 	struct nf_logger *logger;
189 
190 	if (pf == NFPROTO_INET) {
191 		nf_logger_put(NFPROTO_IPV4, type);
192 		nf_logger_put(NFPROTO_IPV6, type);
193 		return;
194 	}
195 
196 	BUG_ON(loggers[pf][type] == NULL);
197 
198 	rcu_read_lock();
199 	logger = rcu_dereference(loggers[pf][type]);
200 	module_put(logger->me);
201 	rcu_read_unlock();
202 }
203 EXPORT_SYMBOL_GPL(nf_logger_put);
204 
nf_log_packet(struct net * net,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 * loginfo,const char * fmt,...)205 void nf_log_packet(struct net *net,
206 		   u_int8_t pf,
207 		   unsigned int hooknum,
208 		   const struct sk_buff *skb,
209 		   const struct net_device *in,
210 		   const struct net_device *out,
211 		   const struct nf_loginfo *loginfo,
212 		   const char *fmt, ...)
213 {
214 	va_list args;
215 	char prefix[NF_LOG_PREFIXLEN];
216 	const struct nf_logger *logger;
217 
218 	rcu_read_lock();
219 	if (loginfo != NULL)
220 		logger = rcu_dereference(loggers[pf][loginfo->type]);
221 	else
222 		logger = rcu_dereference(net->nf.nf_loggers[pf]);
223 
224 	if (logger) {
225 		va_start(args, fmt);
226 		vsnprintf(prefix, sizeof(prefix), fmt, args);
227 		va_end(args);
228 		logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
229 	}
230 	rcu_read_unlock();
231 }
232 EXPORT_SYMBOL(nf_log_packet);
233 
nf_log_trace(struct net * net,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 * loginfo,const char * fmt,...)234 void nf_log_trace(struct net *net,
235 		  u_int8_t pf,
236 		  unsigned int hooknum,
237 		  const struct sk_buff *skb,
238 		  const struct net_device *in,
239 		  const struct net_device *out,
240 		  const struct nf_loginfo *loginfo, const char *fmt, ...)
241 {
242 	va_list args;
243 	char prefix[NF_LOG_PREFIXLEN];
244 	const struct nf_logger *logger;
245 
246 	rcu_read_lock();
247 	logger = rcu_dereference(net->nf.nf_loggers[pf]);
248 	if (logger) {
249 		va_start(args, fmt);
250 		vsnprintf(prefix, sizeof(prefix), fmt, args);
251 		va_end(args);
252 		logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
253 	}
254 	rcu_read_unlock();
255 }
256 EXPORT_SYMBOL(nf_log_trace);
257 
258 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
259 
260 struct nf_log_buf {
261 	unsigned int	count;
262 	char		buf[S_SIZE + 1];
263 };
264 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
265 
nf_log_buf_add(struct nf_log_buf * m,const char * f,...)266 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
267 {
268 	va_list args;
269 	int len;
270 
271 	if (likely(m->count < S_SIZE)) {
272 		va_start(args, f);
273 		len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
274 		va_end(args);
275 		if (likely(m->count + len < S_SIZE)) {
276 			m->count += len;
277 			return 0;
278 		}
279 	}
280 	m->count = S_SIZE;
281 	printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
282 	return -1;
283 }
284 EXPORT_SYMBOL_GPL(nf_log_buf_add);
285 
nf_log_buf_open(void)286 struct nf_log_buf *nf_log_buf_open(void)
287 {
288 	struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
289 
290 	if (unlikely(!m)) {
291 		local_bh_disable();
292 		do {
293 			m = xchg(&emergency_ptr, NULL);
294 		} while (!m);
295 	}
296 	m->count = 0;
297 	return m;
298 }
299 EXPORT_SYMBOL_GPL(nf_log_buf_open);
300 
nf_log_buf_close(struct nf_log_buf * m)301 void nf_log_buf_close(struct nf_log_buf *m)
302 {
303 	m->buf[m->count] = 0;
304 	printk("%s\n", m->buf);
305 
306 	if (likely(m != &emergency))
307 		kfree(m);
308 	else {
309 		emergency_ptr = m;
310 		local_bh_enable();
311 	}
312 }
313 EXPORT_SYMBOL_GPL(nf_log_buf_close);
314 
315 #ifdef CONFIG_PROC_FS
seq_start(struct seq_file * seq,loff_t * pos)316 static void *seq_start(struct seq_file *seq, loff_t *pos)
317 {
318 	struct net *net = seq_file_net(seq);
319 
320 	mutex_lock(&nf_log_mutex);
321 
322 	if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
323 		return NULL;
324 
325 	return pos;
326 }
327 
seq_next(struct seq_file * s,void * v,loff_t * pos)328 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
329 {
330 	struct net *net = seq_file_net(s);
331 
332 	(*pos)++;
333 
334 	if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
335 		return NULL;
336 
337 	return pos;
338 }
339 
seq_stop(struct seq_file * s,void * v)340 static void seq_stop(struct seq_file *s, void *v)
341 {
342 	mutex_unlock(&nf_log_mutex);
343 }
344 
seq_show(struct seq_file * s,void * v)345 static int seq_show(struct seq_file *s, void *v)
346 {
347 	loff_t *pos = v;
348 	const struct nf_logger *logger;
349 	int i;
350 	struct net *net = seq_file_net(s);
351 
352 	logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
353 
354 	if (!logger)
355 		seq_printf(s, "%2lld NONE (", *pos);
356 	else
357 		seq_printf(s, "%2lld %s (", *pos, logger->name);
358 
359 	if (seq_has_overflowed(s))
360 		return -ENOSPC;
361 
362 	for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
363 		if (loggers[*pos][i] == NULL)
364 			continue;
365 
366 		logger = nft_log_dereference(loggers[*pos][i]);
367 		seq_puts(s, logger->name);
368 		if (i == 0 && loggers[*pos][i + 1] != NULL)
369 			seq_puts(s, ",");
370 
371 		if (seq_has_overflowed(s))
372 			return -ENOSPC;
373 	}
374 
375 	seq_puts(s, ")\n");
376 
377 	if (seq_has_overflowed(s))
378 		return -ENOSPC;
379 	return 0;
380 }
381 
382 static const struct seq_operations nflog_seq_ops = {
383 	.start	= seq_start,
384 	.next	= seq_next,
385 	.stop	= seq_stop,
386 	.show	= seq_show,
387 };
388 #endif /* PROC_FS */
389 
390 #ifdef CONFIG_SYSCTL
391 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
392 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
393 static struct ctl_table_header *nf_log_sysctl_fhdr;
394 
395 static struct ctl_table nf_log_sysctl_ftable[] = {
396 	{
397 		.procname	= "nf_log_all_netns",
398 		.data		= &sysctl_nf_log_all_netns,
399 		.maxlen		= sizeof(sysctl_nf_log_all_netns),
400 		.mode		= 0644,
401 		.proc_handler	= proc_dointvec,
402 	},
403 	{ }
404 };
405 
nf_log_proc_dostring(struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)406 static int nf_log_proc_dostring(struct ctl_table *table, int write,
407 			 void *buffer, size_t *lenp, loff_t *ppos)
408 {
409 	const struct nf_logger *logger;
410 	char buf[NFLOGGER_NAME_LEN];
411 	int r = 0;
412 	int tindex = (unsigned long)table->extra1;
413 	struct net *net = table->extra2;
414 
415 	if (write) {
416 		struct ctl_table tmp = *table;
417 
418 		/* proc_dostring() can append to existing strings, so we need to
419 		 * initialize it as an empty string.
420 		 */
421 		buf[0] = '\0';
422 		tmp.data = buf;
423 		r = proc_dostring(&tmp, write, buffer, lenp, ppos);
424 		if (r)
425 			return r;
426 
427 		if (!strcmp(buf, "NONE")) {
428 			nf_log_unbind_pf(net, tindex);
429 			return 0;
430 		}
431 		mutex_lock(&nf_log_mutex);
432 		logger = __find_logger(tindex, buf);
433 		if (logger == NULL) {
434 			mutex_unlock(&nf_log_mutex);
435 			return -ENOENT;
436 		}
437 		rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
438 		mutex_unlock(&nf_log_mutex);
439 	} else {
440 		struct ctl_table tmp = *table;
441 
442 		tmp.data = buf;
443 		mutex_lock(&nf_log_mutex);
444 		logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
445 		if (!logger)
446 			strscpy(buf, "NONE", sizeof(buf));
447 		else
448 			strscpy(buf, logger->name, sizeof(buf));
449 		mutex_unlock(&nf_log_mutex);
450 		r = proc_dostring(&tmp, write, buffer, lenp, ppos);
451 	}
452 
453 	return r;
454 }
455 
netfilter_log_sysctl_init(struct net * net)456 static int netfilter_log_sysctl_init(struct net *net)
457 {
458 	int i;
459 	struct ctl_table *table;
460 
461 	table = nf_log_sysctl_table;
462 	if (!net_eq(net, &init_net)) {
463 		table = kmemdup(nf_log_sysctl_table,
464 				 sizeof(nf_log_sysctl_table),
465 				 GFP_KERNEL);
466 		if (!table)
467 			goto err_alloc;
468 	} else {
469 		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
470 			snprintf(nf_log_sysctl_fnames[i],
471 				 3, "%d", i);
472 			nf_log_sysctl_table[i].procname	=
473 				nf_log_sysctl_fnames[i];
474 			nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
475 			nf_log_sysctl_table[i].mode = 0644;
476 			nf_log_sysctl_table[i].proc_handler =
477 				nf_log_proc_dostring;
478 			nf_log_sysctl_table[i].extra1 =
479 				(void *)(unsigned long) i;
480 		}
481 		nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
482 							 nf_log_sysctl_ftable);
483 		if (!nf_log_sysctl_fhdr)
484 			goto err_freg;
485 	}
486 
487 	for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
488 		table[i].extra2 = net;
489 
490 	net->nf.nf_log_dir_header = register_net_sysctl(net,
491 						"net/netfilter/nf_log",
492 						table);
493 	if (!net->nf.nf_log_dir_header)
494 		goto err_reg;
495 
496 	return 0;
497 
498 err_reg:
499 	if (!net_eq(net, &init_net))
500 		kfree(table);
501 	else
502 		unregister_net_sysctl_table(nf_log_sysctl_fhdr);
503 err_freg:
504 err_alloc:
505 	return -ENOMEM;
506 }
507 
netfilter_log_sysctl_exit(struct net * net)508 static void netfilter_log_sysctl_exit(struct net *net)
509 {
510 	struct ctl_table *table;
511 
512 	table = net->nf.nf_log_dir_header->ctl_table_arg;
513 	unregister_net_sysctl_table(net->nf.nf_log_dir_header);
514 	if (!net_eq(net, &init_net))
515 		kfree(table);
516 	else
517 		unregister_net_sysctl_table(nf_log_sysctl_fhdr);
518 }
519 #else
netfilter_log_sysctl_init(struct net * net)520 static int netfilter_log_sysctl_init(struct net *net)
521 {
522 	return 0;
523 }
524 
netfilter_log_sysctl_exit(struct net * net)525 static void netfilter_log_sysctl_exit(struct net *net)
526 {
527 }
528 #endif /* CONFIG_SYSCTL */
529 
nf_log_net_init(struct net * net)530 static int __net_init nf_log_net_init(struct net *net)
531 {
532 	int ret = -ENOMEM;
533 
534 #ifdef CONFIG_PROC_FS
535 	if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
536 			&nflog_seq_ops, sizeof(struct seq_net_private)))
537 		return ret;
538 #endif
539 	ret = netfilter_log_sysctl_init(net);
540 	if (ret < 0)
541 		goto out_sysctl;
542 
543 	return 0;
544 
545 out_sysctl:
546 #ifdef CONFIG_PROC_FS
547 	remove_proc_entry("nf_log", net->nf.proc_netfilter);
548 #endif
549 	return ret;
550 }
551 
nf_log_net_exit(struct net * net)552 static void __net_exit nf_log_net_exit(struct net *net)
553 {
554 	netfilter_log_sysctl_exit(net);
555 #ifdef CONFIG_PROC_FS
556 	remove_proc_entry("nf_log", net->nf.proc_netfilter);
557 #endif
558 }
559 
560 static struct pernet_operations nf_log_net_ops = {
561 	.init = nf_log_net_init,
562 	.exit = nf_log_net_exit,
563 };
564 
netfilter_log_init(void)565 int __init netfilter_log_init(void)
566 {
567 	return register_pernet_subsys(&nf_log_net_ops);
568 }
569