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Linux/net/netfilter/nf_log.c

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

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