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(s1: str_logger, s2: 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(lock: &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(lock: &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 = -EBUSY;
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 = -EBUSY;
101 goto unlock;
102 }
103 rcu_assign_pointer(loggers[pf][logger->type], logger);
104 }
105
106unlock:
107 mutex_unlock(lock: &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(lock: &nf_log_mutex);
124 synchronize_rcu();
125}
126EXPORT_SYMBOL(nf_log_unregister);
127
128/**
129 * nf_log_is_registered - Check if any logger is registered for a given
130 * protocol family.
131 *
132 * @pf: Protocol family
133 *
134 * Returns: true if at least one logger is active for @pf, false otherwise.
135 */
136bool nf_log_is_registered(u_int8_t pf)
137{
138 int i;
139
140 if (pf >= NFPROTO_NUMPROTO) {
141 WARN_ON_ONCE(1);
142 return false;
143 }
144
145 for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
146 if (rcu_access_pointer(loggers[pf][i]))
147 return true;
148 }
149
150 return false;
151}
152EXPORT_SYMBOL(nf_log_is_registered);
153
154int nf_log_bind_pf(struct net *net, u_int8_t pf,
155 const struct nf_logger *logger)
156{
157 if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
158 return -EINVAL;
159 mutex_lock(&nf_log_mutex);
160 if (__find_logger(pf, str_logger: logger->name) == NULL) {
161 mutex_unlock(lock: &nf_log_mutex);
162 return -ENOENT;
163 }
164 rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
165 mutex_unlock(lock: &nf_log_mutex);
166 return 0;
167}
168EXPORT_SYMBOL(nf_log_bind_pf);
169
170void nf_log_unbind_pf(struct net *net, u_int8_t pf)
171{
172 if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
173 return;
174 mutex_lock(&nf_log_mutex);
175 RCU_INIT_POINTER(net->nf.nf_loggers[pf], NULL);
176 mutex_unlock(lock: &nf_log_mutex);
177}
178EXPORT_SYMBOL(nf_log_unbind_pf);
179
180int nf_logger_find_get(int pf, enum nf_log_type type)
181{
182 struct nf_logger *logger;
183 int ret = -ENOENT;
184
185 if (pf >= ARRAY_SIZE(loggers))
186 return -EINVAL;
187 if (type >= NF_LOG_TYPE_MAX)
188 return -EINVAL;
189
190 if (pf == NFPROTO_INET) {
191 ret = nf_logger_find_get(pf: NFPROTO_IPV4, type);
192 if (ret < 0)
193 return ret;
194
195 ret = nf_logger_find_get(pf: NFPROTO_IPV6, type);
196 if (ret < 0) {
197 nf_logger_put(pf: NFPROTO_IPV4, type);
198 return ret;
199 }
200
201 return 0;
202 }
203
204 rcu_read_lock();
205 logger = rcu_dereference(loggers[pf][type]);
206 if (logger == NULL)
207 goto out;
208
209 if (try_module_get(module: logger->me))
210 ret = 0;
211out:
212 rcu_read_unlock();
213 return ret;
214}
215EXPORT_SYMBOL_GPL(nf_logger_find_get);
216
217void nf_logger_put(int pf, enum nf_log_type type)
218{
219 struct nf_logger *logger;
220
221 if (pf == NFPROTO_INET) {
222 nf_logger_put(pf: NFPROTO_IPV4, type);
223 nf_logger_put(pf: NFPROTO_IPV6, type);
224 return;
225 }
226
227 rcu_read_lock();
228 logger = rcu_dereference(loggers[pf][type]);
229 if (!logger)
230 WARN_ON_ONCE(1);
231 else
232 module_put(module: logger->me);
233 rcu_read_unlock();
234}
235EXPORT_SYMBOL_GPL(nf_logger_put);
236
237void nf_log_packet(struct net *net,
238 u_int8_t pf,
239 unsigned int hooknum,
240 const struct sk_buff *skb,
241 const struct net_device *in,
242 const struct net_device *out,
243 const struct nf_loginfo *loginfo,
244 const char *fmt, ...)
245{
246 va_list args;
247 char prefix[NF_LOG_PREFIXLEN];
248 const struct nf_logger *logger;
249
250 rcu_read_lock();
251 if (loginfo != NULL)
252 logger = rcu_dereference(loggers[pf][loginfo->type]);
253 else
254 logger = rcu_dereference(net->nf.nf_loggers[pf]);
255
256 if (logger) {
257 va_start(args, fmt);
258 vsnprintf(buf: prefix, size: sizeof(prefix), fmt, args);
259 va_end(args);
260 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
261 }
262 rcu_read_unlock();
263}
264EXPORT_SYMBOL(nf_log_packet);
265
266void nf_log_trace(struct net *net,
267 u_int8_t pf,
268 unsigned int hooknum,
269 const struct sk_buff *skb,
270 const struct net_device *in,
271 const struct net_device *out,
272 const struct nf_loginfo *loginfo, const char *fmt, ...)
273{
274 va_list args;
275 char prefix[NF_LOG_PREFIXLEN];
276 const struct nf_logger *logger;
277
278 rcu_read_lock();
279 logger = rcu_dereference(net->nf.nf_loggers[pf]);
280 if (logger) {
281 va_start(args, fmt);
282 vsnprintf(buf: prefix, size: sizeof(prefix), fmt, args);
283 va_end(args);
284 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
285 }
286 rcu_read_unlock();
287}
288EXPORT_SYMBOL(nf_log_trace);
289
290#define S_SIZE (1024 - (sizeof(unsigned int) + 1))
291
292struct nf_log_buf {
293 unsigned int count;
294 char buf[S_SIZE + 1];
295};
296static struct nf_log_buf emergency, *emergency_ptr = &emergency;
297
298__printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
299{
300 va_list args;
301 int len;
302
303 if (likely(m->count < S_SIZE)) {
304 va_start(args, f);
305 len = vsnprintf(buf: m->buf + m->count, S_SIZE - m->count, fmt: f, args);
306 va_end(args);
307 if (likely(m->count + len < S_SIZE)) {
308 m->count += len;
309 return 0;
310 }
311 }
312 m->count = S_SIZE;
313 printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
314 return -1;
315}
316EXPORT_SYMBOL_GPL(nf_log_buf_add);
317
318struct nf_log_buf *nf_log_buf_open(void)
319{
320 struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
321
322 if (unlikely(!m)) {
323 local_bh_disable();
324 do {
325 m = xchg(&emergency_ptr, NULL);
326 } while (!m);
327 }
328 m->count = 0;
329 return m;
330}
331EXPORT_SYMBOL_GPL(nf_log_buf_open);
332
333void nf_log_buf_close(struct nf_log_buf *m)
334{
335 m->buf[m->count] = 0;
336 printk("%s\n", m->buf);
337
338 if (likely(m != &emergency))
339 kfree(objp: m);
340 else {
341 emergency_ptr = m;
342 local_bh_enable();
343 }
344}
345EXPORT_SYMBOL_GPL(nf_log_buf_close);
346
347#ifdef CONFIG_PROC_FS
348static void *seq_start(struct seq_file *seq, loff_t *pos)
349{
350 struct net *net = seq_file_net(seq);
351
352 mutex_lock(&nf_log_mutex);
353
354 if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
355 return NULL;
356
357 return pos;
358}
359
360static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
361{
362 struct net *net = seq_file_net(seq: s);
363
364 (*pos)++;
365
366 if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
367 return NULL;
368
369 return pos;
370}
371
372static void seq_stop(struct seq_file *s, void *v)
373{
374 mutex_unlock(lock: &nf_log_mutex);
375}
376
377static int seq_show(struct seq_file *s, void *v)
378{
379 loff_t *pos = v;
380 const struct nf_logger *logger;
381 int i;
382 struct net *net = seq_file_net(seq: s);
383
384 logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
385
386 if (!logger)
387 seq_printf(m: s, fmt: "%2lld NONE (", *pos);
388 else
389 seq_printf(m: s, fmt: "%2lld %s (", *pos, logger->name);
390
391 if (seq_has_overflowed(m: s))
392 return -ENOSPC;
393
394 for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
395 if (loggers[*pos][i] == NULL)
396 continue;
397
398 logger = nft_log_dereference(loggers[*pos][i]);
399 seq_puts(m: s, s: logger->name);
400 if (i == 0 && loggers[*pos][i + 1] != NULL)
401 seq_puts(m: s, s: ",");
402
403 if (seq_has_overflowed(m: s))
404 return -ENOSPC;
405 }
406
407 seq_puts(m: s, s: ")\n");
408
409 if (seq_has_overflowed(m: s))
410 return -ENOSPC;
411 return 0;
412}
413
414static const struct seq_operations nflog_seq_ops = {
415 .start = seq_start,
416 .next = seq_next,
417 .stop = seq_stop,
418 .show = seq_show,
419};
420#endif /* PROC_FS */
421
422#ifdef CONFIG_SYSCTL
423static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
424static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO];
425static struct ctl_table_header *nf_log_sysctl_fhdr;
426
427static struct ctl_table nf_log_sysctl_ftable[] = {
428 {
429 .procname = "nf_log_all_netns",
430 .data = &sysctl_nf_log_all_netns,
431 .maxlen = sizeof(sysctl_nf_log_all_netns),
432 .mode = 0644,
433 .proc_handler = proc_dointvec,
434 },
435};
436
437static int nf_log_proc_dostring(const struct ctl_table *table, int write,
438 void *buffer, size_t *lenp, loff_t *ppos)
439{
440 const struct nf_logger *logger;
441 char buf[NFLOGGER_NAME_LEN];
442 int r = 0;
443 int tindex = (unsigned long)table->extra1;
444 struct net *net = table->extra2;
445
446 if (write) {
447 struct ctl_table tmp = *table;
448
449 /* proc_dostring() can append to existing strings, so we need to
450 * initialize it as an empty string.
451 */
452 buf[0] = '\0';
453 tmp.data = buf;
454 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
455 if (r)
456 return r;
457
458 if (!strcmp(buf, "NONE")) {
459 nf_log_unbind_pf(net, tindex);
460 return 0;
461 }
462 mutex_lock(&nf_log_mutex);
463 logger = __find_logger(pf: tindex, str_logger: buf);
464 if (logger == NULL) {
465 mutex_unlock(lock: &nf_log_mutex);
466 return -ENOENT;
467 }
468 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
469 mutex_unlock(lock: &nf_log_mutex);
470 } else {
471 struct ctl_table tmp = *table;
472
473 tmp.data = buf;
474 mutex_lock(&nf_log_mutex);
475 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
476 if (!logger)
477 strscpy(buf, "NONE", sizeof(buf));
478 else
479 strscpy(buf, logger->name, sizeof(buf));
480 mutex_unlock(lock: &nf_log_mutex);
481 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
482 }
483
484 return r;
485}
486
487static int netfilter_log_sysctl_init(struct net *net)
488{
489 int i;
490 struct ctl_table *table;
491
492 table = nf_log_sysctl_table;
493 if (!net_eq(net1: net, net2: &init_net)) {
494 table = kmemdup(nf_log_sysctl_table,
495 sizeof(nf_log_sysctl_table),
496 GFP_KERNEL);
497 if (!table)
498 goto err_alloc;
499 } else {
500 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
501 snprintf(buf: nf_log_sysctl_fnames[i],
502 size: 3, fmt: "%d", i);
503 nf_log_sysctl_table[i].procname =
504 nf_log_sysctl_fnames[i];
505 nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
506 nf_log_sysctl_table[i].mode = 0644;
507 nf_log_sysctl_table[i].proc_handler =
508 nf_log_proc_dostring;
509 nf_log_sysctl_table[i].extra1 =
510 (void *)(unsigned long) i;
511 }
512 nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
513 nf_log_sysctl_ftable);
514 if (!nf_log_sysctl_fhdr)
515 goto err_freg;
516 }
517
518 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
519 table[i].extra2 = net;
520
521 net->nf.nf_log_dir_header = register_net_sysctl_sz(net,
522 path: "net/netfilter/nf_log",
523 table,
524 ARRAY_SIZE(nf_log_sysctl_table));
525 if (!net->nf.nf_log_dir_header)
526 goto err_reg;
527
528 return 0;
529
530err_reg:
531 if (!net_eq(net1: net, net2: &init_net))
532 kfree(objp: table);
533 else
534 unregister_net_sysctl_table(header: nf_log_sysctl_fhdr);
535err_freg:
536err_alloc:
537 return -ENOMEM;
538}
539
540static void netfilter_log_sysctl_exit(struct net *net)
541{
542 const struct ctl_table *table;
543
544 table = net->nf.nf_log_dir_header->ctl_table_arg;
545 unregister_net_sysctl_table(header: net->nf.nf_log_dir_header);
546 if (!net_eq(net1: net, net2: &init_net))
547 kfree(objp: table);
548 else
549 unregister_net_sysctl_table(header: nf_log_sysctl_fhdr);
550}
551#else
552static int netfilter_log_sysctl_init(struct net *net)
553{
554 return 0;
555}
556
557static void netfilter_log_sysctl_exit(struct net *net)
558{
559}
560#endif /* CONFIG_SYSCTL */
561
562static int __net_init nf_log_net_init(struct net *net)
563{
564 int ret = -ENOMEM;
565
566#ifdef CONFIG_PROC_FS
567 if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
568 &nflog_seq_ops, sizeof(struct seq_net_private)))
569 return ret;
570#endif
571 ret = netfilter_log_sysctl_init(net);
572 if (ret < 0)
573 goto out_sysctl;
574
575 return 0;
576
577out_sysctl:
578#ifdef CONFIG_PROC_FS
579 remove_proc_entry("nf_log", net->nf.proc_netfilter);
580#endif
581 return ret;
582}
583
584static void __net_exit nf_log_net_exit(struct net *net)
585{
586 netfilter_log_sysctl_exit(net);
587#ifdef CONFIG_PROC_FS
588 remove_proc_entry("nf_log", net->nf.proc_netfilter);
589#endif
590}
591
592static struct pernet_operations nf_log_net_ops = {
593 .init = nf_log_net_init,
594 .exit = nf_log_net_exit,
595};
596
597int __init netfilter_log_init(void)
598{
599 return register_pernet_subsys(&nf_log_net_ops);
600}
601

source code of linux/net/netfilter/nf_log.c