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 = -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(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
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, str_logger: logger->name) == NULL) {
135 mutex_unlock(lock: &nf_log_mutex);
136 return -ENOENT;
137 }
138 rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
139 mutex_unlock(lock: &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(lock: &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(pf: NFPROTO_IPV4, type);
166 if (ret < 0)
167 return ret;
168
169 ret = nf_logger_find_get(pf: NFPROTO_IPV6, type);
170 if (ret < 0) {
171 nf_logger_put(pf: 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(module: 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(pf: NFPROTO_IPV4, type);
197 nf_logger_put(pf: 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(module: 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(buf: prefix, size: 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(buf: prefix, size: 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(buf: m->buf + m->count, S_SIZE - m->count, fmt: 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(size: 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(objp: 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(seq: 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(lock: &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(seq: s);
357
358 logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
359
360 if (!logger)
361 seq_printf(m: s, fmt: "%2lld NONE (", *pos);
362 else
363 seq_printf(m: s, fmt: "%2lld %s (", *pos, logger->name);
364
365 if (seq_has_overflowed(m: 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(m: s, s: logger->name);
374 if (i == 0 && loggers[*pos][i + 1] != NULL)
375 seq_puts(m: s, s: ",");
376
377 if (seq_has_overflowed(m: s))
378 return -ENOSPC;
379 }
380
381 seq_puts(m: s, s: ")\n");
382
383 if (seq_has_overflowed(m: 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(pf: tindex, str_logger: buf);
439 if (logger == NULL) {
440 mutex_unlock(lock: &nf_log_mutex);
441 return -ENOENT;
442 }
443 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
444 mutex_unlock(lock: &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(lock: &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(net1: net, net2: &init_net)) {
469 table = kmemdup(p: nf_log_sysctl_table,
470 size: 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(buf: nf_log_sysctl_fnames[i],
477 size: 3, fmt: "%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 path: "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(net1: net, net2: &init_net))
507 kfree(objp: table);
508 else
509 unregister_net_sysctl_table(header: 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(header: net->nf.nf_log_dir_header);
521 if (!net_eq(net1: net, net2: &init_net))
522 kfree(objp: table);
523 else
524 unregister_net_sysctl_table(header: 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

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