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