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

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