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_request_module(int pf,enum nf_log_type type)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
nf_logger_find_get(int pf,enum nf_log_type type)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
nf_logger_put(int pf,enum nf_log_type type)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 rcu_read_lock();
207 logger = rcu_dereference(loggers[pf][type]);
208 if (!logger)
209 WARN_ON_ONCE(1);
210 else
211 module_put(logger->me);
212 rcu_read_unlock();
213 }
214 EXPORT_SYMBOL_GPL(nf_logger_put);
215
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,...)216 void nf_log_packet(struct net *net,
217 u_int8_t pf,
218 unsigned int hooknum,
219 const struct sk_buff *skb,
220 const struct net_device *in,
221 const struct net_device *out,
222 const struct nf_loginfo *loginfo,
223 const char *fmt, ...)
224 {
225 va_list args;
226 char prefix[NF_LOG_PREFIXLEN];
227 const struct nf_logger *logger;
228
229 rcu_read_lock();
230 if (loginfo != NULL)
231 logger = rcu_dereference(loggers[pf][loginfo->type]);
232 else
233 logger = rcu_dereference(net->nf.nf_loggers[pf]);
234
235 if (logger) {
236 va_start(args, fmt);
237 vsnprintf(prefix, sizeof(prefix), fmt, args);
238 va_end(args);
239 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
240 }
241 rcu_read_unlock();
242 }
243 EXPORT_SYMBOL(nf_log_packet);
244
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,...)245 void nf_log_trace(struct net *net,
246 u_int8_t pf,
247 unsigned int hooknum,
248 const struct sk_buff *skb,
249 const struct net_device *in,
250 const struct net_device *out,
251 const struct nf_loginfo *loginfo, const char *fmt, ...)
252 {
253 va_list args;
254 char prefix[NF_LOG_PREFIXLEN];
255 const struct nf_logger *logger;
256
257 rcu_read_lock();
258 logger = rcu_dereference(net->nf.nf_loggers[pf]);
259 if (logger) {
260 va_start(args, fmt);
261 vsnprintf(prefix, sizeof(prefix), fmt, args);
262 va_end(args);
263 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
264 }
265 rcu_read_unlock();
266 }
267 EXPORT_SYMBOL(nf_log_trace);
268
269 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
270
271 struct nf_log_buf {
272 unsigned int count;
273 char buf[S_SIZE + 1];
274 };
275 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
276
nf_log_buf_add(struct nf_log_buf * m,const char * f,...)277 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
278 {
279 va_list args;
280 int len;
281
282 if (likely(m->count < S_SIZE)) {
283 va_start(args, f);
284 len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
285 va_end(args);
286 if (likely(m->count + len < S_SIZE)) {
287 m->count += len;
288 return 0;
289 }
290 }
291 m->count = S_SIZE;
292 printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
293 return -1;
294 }
295 EXPORT_SYMBOL_GPL(nf_log_buf_add);
296
nf_log_buf_open(void)297 struct nf_log_buf *nf_log_buf_open(void)
298 {
299 struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
300
301 if (unlikely(!m)) {
302 local_bh_disable();
303 do {
304 m = xchg(&emergency_ptr, NULL);
305 } while (!m);
306 }
307 m->count = 0;
308 return m;
309 }
310 EXPORT_SYMBOL_GPL(nf_log_buf_open);
311
nf_log_buf_close(struct nf_log_buf * m)312 void nf_log_buf_close(struct nf_log_buf *m)
313 {
314 m->buf[m->count] = 0;
315 printk("%s\n", m->buf);
316
317 if (likely(m != &emergency))
318 kfree(m);
319 else {
320 emergency_ptr = m;
321 local_bh_enable();
322 }
323 }
324 EXPORT_SYMBOL_GPL(nf_log_buf_close);
325
326 #ifdef CONFIG_PROC_FS
seq_start(struct seq_file * seq,loff_t * pos)327 static void *seq_start(struct seq_file *seq, loff_t *pos)
328 {
329 struct net *net = seq_file_net(seq);
330
331 mutex_lock(&nf_log_mutex);
332
333 if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
334 return NULL;
335
336 return pos;
337 }
338
seq_next(struct seq_file * s,void * v,loff_t * pos)339 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
340 {
341 struct net *net = seq_file_net(s);
342
343 (*pos)++;
344
345 if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
346 return NULL;
347
348 return pos;
349 }
350
seq_stop(struct seq_file * s,void * v)351 static void seq_stop(struct seq_file *s, void *v)
352 {
353 mutex_unlock(&nf_log_mutex);
354 }
355
seq_show(struct seq_file * s,void * v)356 static int seq_show(struct seq_file *s, void *v)
357 {
358 loff_t *pos = v;
359 const struct nf_logger *logger;
360 int i;
361 struct net *net = seq_file_net(s);
362
363 logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
364
365 if (!logger)
366 seq_printf(s, "%2lld NONE (", *pos);
367 else
368 seq_printf(s, "%2lld %s (", *pos, logger->name);
369
370 if (seq_has_overflowed(s))
371 return -ENOSPC;
372
373 for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
374 if (loggers[*pos][i] == NULL)
375 continue;
376
377 logger = nft_log_dereference(loggers[*pos][i]);
378 seq_puts(s, logger->name);
379 if (i == 0 && loggers[*pos][i + 1] != NULL)
380 seq_puts(s, ",");
381
382 if (seq_has_overflowed(s))
383 return -ENOSPC;
384 }
385
386 seq_puts(s, ")\n");
387
388 if (seq_has_overflowed(s))
389 return -ENOSPC;
390 return 0;
391 }
392
393 static const struct seq_operations nflog_seq_ops = {
394 .start = seq_start,
395 .next = seq_next,
396 .stop = seq_stop,
397 .show = seq_show,
398 };
399 #endif /* PROC_FS */
400
401 #ifdef CONFIG_SYSCTL
402 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
403 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
404 static struct ctl_table_header *nf_log_sysctl_fhdr;
405
406 static struct ctl_table nf_log_sysctl_ftable[] = {
407 {
408 .procname = "nf_log_all_netns",
409 .data = &sysctl_nf_log_all_netns,
410 .maxlen = sizeof(sysctl_nf_log_all_netns),
411 .mode = 0644,
412 .proc_handler = proc_dointvec,
413 },
414 { }
415 };
416
nf_log_proc_dostring(struct ctl_table * table,int write,void __user * buffer,size_t * lenp,loff_t * ppos)417 static int nf_log_proc_dostring(struct ctl_table *table, int write,
418 void __user *buffer, size_t *lenp, loff_t *ppos)
419 {
420 const struct nf_logger *logger;
421 char buf[NFLOGGER_NAME_LEN];
422 int r = 0;
423 int tindex = (unsigned long)table->extra1;
424 struct net *net = table->extra2;
425
426 if (write) {
427 struct ctl_table tmp = *table;
428
429 /* proc_dostring() can append to existing strings, so we need to
430 * initialize it as an empty string.
431 */
432 buf[0] = '\0';
433 tmp.data = buf;
434 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
435 if (r)
436 return r;
437
438 if (!strcmp(buf, "NONE")) {
439 nf_log_unbind_pf(net, tindex);
440 return 0;
441 }
442 mutex_lock(&nf_log_mutex);
443 logger = __find_logger(tindex, buf);
444 if (logger == NULL) {
445 mutex_unlock(&nf_log_mutex);
446 return -ENOENT;
447 }
448 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
449 mutex_unlock(&nf_log_mutex);
450 } else {
451 struct ctl_table tmp = *table;
452
453 tmp.data = buf;
454 mutex_lock(&nf_log_mutex);
455 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
456 if (!logger)
457 strlcpy(buf, "NONE", sizeof(buf));
458 else
459 strlcpy(buf, logger->name, sizeof(buf));
460 mutex_unlock(&nf_log_mutex);
461 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
462 }
463
464 return r;
465 }
466
netfilter_log_sysctl_init(struct net * net)467 static int netfilter_log_sysctl_init(struct net *net)
468 {
469 int i;
470 struct ctl_table *table;
471
472 table = nf_log_sysctl_table;
473 if (!net_eq(net, &init_net)) {
474 table = kmemdup(nf_log_sysctl_table,
475 sizeof(nf_log_sysctl_table),
476 GFP_KERNEL);
477 if (!table)
478 goto err_alloc;
479 } else {
480 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
481 snprintf(nf_log_sysctl_fnames[i],
482 3, "%d", i);
483 nf_log_sysctl_table[i].procname =
484 nf_log_sysctl_fnames[i];
485 nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
486 nf_log_sysctl_table[i].mode = 0644;
487 nf_log_sysctl_table[i].proc_handler =
488 nf_log_proc_dostring;
489 nf_log_sysctl_table[i].extra1 =
490 (void *)(unsigned long) i;
491 }
492 nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
493 nf_log_sysctl_ftable);
494 if (!nf_log_sysctl_fhdr)
495 goto err_freg;
496 }
497
498 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
499 table[i].extra2 = net;
500
501 net->nf.nf_log_dir_header = register_net_sysctl(net,
502 "net/netfilter/nf_log",
503 table);
504 if (!net->nf.nf_log_dir_header)
505 goto err_reg;
506
507 return 0;
508
509 err_reg:
510 if (!net_eq(net, &init_net))
511 kfree(table);
512 else
513 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
514 err_freg:
515 err_alloc:
516 return -ENOMEM;
517 }
518
netfilter_log_sysctl_exit(struct net * net)519 static void netfilter_log_sysctl_exit(struct net *net)
520 {
521 struct ctl_table *table;
522
523 table = net->nf.nf_log_dir_header->ctl_table_arg;
524 unregister_net_sysctl_table(net->nf.nf_log_dir_header);
525 if (!net_eq(net, &init_net))
526 kfree(table);
527 else
528 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
529 }
530 #else
netfilter_log_sysctl_init(struct net * net)531 static int netfilter_log_sysctl_init(struct net *net)
532 {
533 return 0;
534 }
535
netfilter_log_sysctl_exit(struct net * net)536 static void netfilter_log_sysctl_exit(struct net *net)
537 {
538 }
539 #endif /* CONFIG_SYSCTL */
540
nf_log_net_init(struct net * net)541 static int __net_init nf_log_net_init(struct net *net)
542 {
543 int ret = -ENOMEM;
544
545 #ifdef CONFIG_PROC_FS
546 if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
547 &nflog_seq_ops, sizeof(struct seq_net_private)))
548 return ret;
549 #endif
550 ret = netfilter_log_sysctl_init(net);
551 if (ret < 0)
552 goto out_sysctl;
553
554 return 0;
555
556 out_sysctl:
557 #ifdef CONFIG_PROC_FS
558 remove_proc_entry("nf_log", net->nf.proc_netfilter);
559 #endif
560 return ret;
561 }
562
nf_log_net_exit(struct net * net)563 static void __net_exit nf_log_net_exit(struct net *net)
564 {
565 netfilter_log_sysctl_exit(net);
566 #ifdef CONFIG_PROC_FS
567 remove_proc_entry("nf_log", net->nf.proc_netfilter);
568 #endif
569 }
570
571 static struct pernet_operations nf_log_net_ops = {
572 .init = nf_log_net_init,
573 .exit = nf_log_net_exit,
574 };
575
netfilter_log_init(void)576 int __init netfilter_log_init(void)
577 {
578 return register_pernet_subsys(&nf_log_net_ops);
579 }
580