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Linux/net/netfilter/nf_log.c

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  1 #include <linux/kernel.h>
  2 #include <linux/init.h>
  3 #include <linux/module.h>
  4 #include <linux/proc_fs.h>
  5 #include <linux/skbuff.h>
  6 #include <linux/netfilter.h>
  7 #include <linux/seq_file.h>
  8 #include <net/protocol.h>
  9 #include <net/netfilter/nf_log.h>
 10 
 11 #include "nf_internals.h"
 12 
 13 /* Internal logging interface, which relies on the real
 14    LOG target modules */
 15 
 16 #define NFLOGGER_NAME_LEN               64
 17 
 18 int sysctl_nf_log_all_netns __read_mostly;
 19 EXPORT_SYMBOL(sysctl_nf_log_all_netns);
 20 
 21 static struct nf_logger __rcu *loggers[NFPROTO_NUMPROTO][NF_LOG_TYPE_MAX] __read_mostly;
 22 static DEFINE_MUTEX(nf_log_mutex);
 23 
 24 #define nft_log_dereference(logger) \
 25         rcu_dereference_protected(logger, lockdep_is_held(&nf_log_mutex))
 26 
 27 static struct nf_logger *__find_logger(int pf, const char *str_logger)
 28 {
 29         struct nf_logger *log;
 30         int i;
 31 
 32         for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
 33                 if (loggers[pf][i] == NULL)
 34                         continue;
 35 
 36                 log = nft_log_dereference(loggers[pf][i]);
 37                 if (!strncasecmp(str_logger, log->name, strlen(log->name)))
 38                         return log;
 39         }
 40 
 41         return NULL;
 42 }
 43 
 44 int nf_log_set(struct net *net, u_int8_t pf, const struct nf_logger *logger)
 45 {
 46         const struct nf_logger *log;
 47 
 48         if (pf == NFPROTO_UNSPEC || pf >= ARRAY_SIZE(net->nf.nf_loggers))
 49                 return -EOPNOTSUPP;
 50 
 51         mutex_lock(&nf_log_mutex);
 52         log = nft_log_dereference(net->nf.nf_loggers[pf]);
 53         if (log == NULL)
 54                 rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
 55 
 56         mutex_unlock(&nf_log_mutex);
 57 
 58         return 0;
 59 }
 60 EXPORT_SYMBOL(nf_log_set);
 61 
 62 void nf_log_unset(struct net *net, const struct nf_logger *logger)
 63 {
 64         int i;
 65         const struct nf_logger *log;
 66 
 67         mutex_lock(&nf_log_mutex);
 68         for (i = 0; i < NFPROTO_NUMPROTO; i++) {
 69                 log = nft_log_dereference(net->nf.nf_loggers[i]);
 70                 if (log == logger)
 71                         RCU_INIT_POINTER(net->nf.nf_loggers[i], NULL);
 72         }
 73         mutex_unlock(&nf_log_mutex);
 74 }
 75 EXPORT_SYMBOL(nf_log_unset);
 76 
 77 /* return EEXIST if the same logger is registered, 0 on success. */
 78 int nf_log_register(u_int8_t pf, struct nf_logger *logger)
 79 {
 80         int i;
 81         int ret = 0;
 82 
 83         if (pf >= ARRAY_SIZE(init_net.nf.nf_loggers))
 84                 return -EINVAL;
 85 
 86         mutex_lock(&nf_log_mutex);
 87 
 88         if (pf == NFPROTO_UNSPEC) {
 89                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 90                         if (rcu_access_pointer(loggers[i][logger->type])) {
 91                                 ret = -EEXIST;
 92                                 goto unlock;
 93                         }
 94                 }
 95                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 96                         rcu_assign_pointer(loggers[i][logger->type], logger);
 97         } else {
 98                 if (rcu_access_pointer(loggers[pf][logger->type])) {
 99                         ret = -EEXIST;
100                         goto unlock;
101                 }
102                 rcu_assign_pointer(loggers[pf][logger->type], logger);
103         }
104 
105 unlock:
106         mutex_unlock(&nf_log_mutex);
107         return ret;
108 }
109 EXPORT_SYMBOL(nf_log_register);
110 
111 void nf_log_unregister(struct nf_logger *logger)
112 {
113         const struct nf_logger *log;
114         int i;
115 
116         mutex_lock(&nf_log_mutex);
117         for (i = 0; i < NFPROTO_NUMPROTO; i++) {
118                 log = nft_log_dereference(loggers[i][logger->type]);
119                 if (log == logger)
120                         RCU_INIT_POINTER(loggers[i][logger->type], NULL);
121         }
122         mutex_unlock(&nf_log_mutex);
123         synchronize_rcu();
124 }
125 EXPORT_SYMBOL(nf_log_unregister);
126 
127 int nf_log_bind_pf(struct net *net, u_int8_t pf,
128                    const struct nf_logger *logger)
129 {
130         if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
131                 return -EINVAL;
132         mutex_lock(&nf_log_mutex);
133         if (__find_logger(pf, logger->name) == NULL) {
134                 mutex_unlock(&nf_log_mutex);
135                 return -ENOENT;
136         }
137         rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
138         mutex_unlock(&nf_log_mutex);
139         return 0;
140 }
141 EXPORT_SYMBOL(nf_log_bind_pf);
142 
143 void nf_log_unbind_pf(struct net *net, u_int8_t pf)
144 {
145         if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
146                 return;
147         mutex_lock(&nf_log_mutex);
148         RCU_INIT_POINTER(net->nf.nf_loggers[pf], NULL);
149         mutex_unlock(&nf_log_mutex);
150 }
151 EXPORT_SYMBOL(nf_log_unbind_pf);
152 
153 void nf_logger_request_module(int pf, enum nf_log_type type)
154 {
155         if (loggers[pf][type] == NULL)
156                 request_module("nf-logger-%u-%u", pf, type);
157 }
158 EXPORT_SYMBOL_GPL(nf_logger_request_module);
159 
160 int nf_logger_find_get(int pf, enum nf_log_type type)
161 {
162         struct nf_logger *logger;
163         int ret = -ENOENT;
164 
165         if (pf == NFPROTO_INET) {
166                 ret = nf_logger_find_get(NFPROTO_IPV4, type);
167                 if (ret < 0)
168                         return ret;
169 
170                 ret = nf_logger_find_get(NFPROTO_IPV6, type);
171                 if (ret < 0) {
172                         nf_logger_put(NFPROTO_IPV4, type);
173                         return ret;
174                 }
175 
176                 return 0;
177         }
178 
179         if (rcu_access_pointer(loggers[pf][type]) == NULL)
180                 request_module("nf-logger-%u-%u", pf, type);
181 
182         rcu_read_lock();
183         logger = rcu_dereference(loggers[pf][type]);
184         if (logger == NULL)
185                 goto out;
186 
187         if (try_module_get(logger->me))
188                 ret = 0;
189 out:
190         rcu_read_unlock();
191         return ret;
192 }
193 EXPORT_SYMBOL_GPL(nf_logger_find_get);
194 
195 void nf_logger_put(int pf, enum nf_log_type type)
196 {
197         struct nf_logger *logger;
198 
199         if (pf == NFPROTO_INET) {
200                 nf_logger_put(NFPROTO_IPV4, type);
201                 nf_logger_put(NFPROTO_IPV6, type);
202                 return;
203         }
204 
205         BUG_ON(loggers[pf][type] == NULL);
206 
207         rcu_read_lock();
208         logger = rcu_dereference(loggers[pf][type]);
209         module_put(logger->me);
210         rcu_read_unlock();
211 }
212 EXPORT_SYMBOL_GPL(nf_logger_put);
213 
214 void nf_log_packet(struct net *net,
215                    u_int8_t pf,
216                    unsigned int hooknum,
217                    const struct sk_buff *skb,
218                    const struct net_device *in,
219                    const struct net_device *out,
220                    const struct nf_loginfo *loginfo,
221                    const char *fmt, ...)
222 {
223         va_list args;
224         char prefix[NF_LOG_PREFIXLEN];
225         const struct nf_logger *logger;
226 
227         rcu_read_lock();
228         if (loginfo != NULL)
229                 logger = rcu_dereference(loggers[pf][loginfo->type]);
230         else
231                 logger = rcu_dereference(net->nf.nf_loggers[pf]);
232 
233         if (logger) {
234                 va_start(args, fmt);
235                 vsnprintf(prefix, sizeof(prefix), fmt, args);
236                 va_end(args);
237                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
238         }
239         rcu_read_unlock();
240 }
241 EXPORT_SYMBOL(nf_log_packet);
242 
243 void nf_log_trace(struct net *net,
244                   u_int8_t pf,
245                   unsigned int hooknum,
246                   const struct sk_buff *skb,
247                   const struct net_device *in,
248                   const struct net_device *out,
249                   const struct nf_loginfo *loginfo, const char *fmt, ...)
250 {
251         va_list args;
252         char prefix[NF_LOG_PREFIXLEN];
253         const struct nf_logger *logger;
254 
255         rcu_read_lock();
256         logger = rcu_dereference(net->nf.nf_loggers[pf]);
257         if (logger) {
258                 va_start(args, fmt);
259                 vsnprintf(prefix, sizeof(prefix), fmt, args);
260                 va_end(args);
261                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
262         }
263         rcu_read_unlock();
264 }
265 EXPORT_SYMBOL(nf_log_trace);
266 
267 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
268 
269 struct nf_log_buf {
270         unsigned int    count;
271         char            buf[S_SIZE + 1];
272 };
273 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
274 
275 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
276 {
277         va_list args;
278         int len;
279 
280         if (likely(m->count < S_SIZE)) {
281                 va_start(args, f);
282                 len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
283                 va_end(args);
284                 if (likely(m->count + len < S_SIZE)) {
285                         m->count += len;
286                         return 0;
287                 }
288         }
289         m->count = S_SIZE;
290         printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
291         return -1;
292 }
293 EXPORT_SYMBOL_GPL(nf_log_buf_add);
294 
295 struct nf_log_buf *nf_log_buf_open(void)
296 {
297         struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
298 
299         if (unlikely(!m)) {
300                 local_bh_disable();
301                 do {
302                         m = xchg(&emergency_ptr, NULL);
303                 } while (!m);
304         }
305         m->count = 0;
306         return m;
307 }
308 EXPORT_SYMBOL_GPL(nf_log_buf_open);
309 
310 void nf_log_buf_close(struct nf_log_buf *m)
311 {
312         m->buf[m->count] = 0;
313         printk("%s\n", m->buf);
314 
315         if (likely(m != &emergency))
316                 kfree(m);
317         else {
318                 emergency_ptr = m;
319                 local_bh_enable();
320         }
321 }
322 EXPORT_SYMBOL_GPL(nf_log_buf_close);
323 
324 #ifdef CONFIG_PROC_FS
325 static void *seq_start(struct seq_file *seq, loff_t *pos)
326 {
327         struct net *net = seq_file_net(seq);
328 
329         mutex_lock(&nf_log_mutex);
330 
331         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
332                 return NULL;
333 
334         return pos;
335 }
336 
337 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
338 {
339         struct net *net = seq_file_net(s);
340 
341         (*pos)++;
342 
343         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
344                 return NULL;
345 
346         return pos;
347 }
348 
349 static void seq_stop(struct seq_file *s, void *v)
350 {
351         mutex_unlock(&nf_log_mutex);
352 }
353 
354 static int seq_show(struct seq_file *s, void *v)
355 {
356         loff_t *pos = v;
357         const struct nf_logger *logger;
358         int i;
359         struct net *net = seq_file_net(s);
360 
361         logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
362 
363         if (!logger)
364                 seq_printf(s, "%2lld NONE (", *pos);
365         else
366                 seq_printf(s, "%2lld %s (", *pos, logger->name);
367 
368         if (seq_has_overflowed(s))
369                 return -ENOSPC;
370 
371         for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
372                 if (loggers[*pos][i] == NULL)
373                         continue;
374 
375                 logger = nft_log_dereference(loggers[*pos][i]);
376                 seq_printf(s, "%s", logger->name);
377                 if (i == 0 && loggers[*pos][i + 1] != NULL)
378                         seq_puts(s, ",");
379 
380                 if (seq_has_overflowed(s))
381                         return -ENOSPC;
382         }
383 
384         seq_puts(s, ")\n");
385 
386         if (seq_has_overflowed(s))
387                 return -ENOSPC;
388         return 0;
389 }
390 
391 static const struct seq_operations nflog_seq_ops = {
392         .start  = seq_start,
393         .next   = seq_next,
394         .stop   = seq_stop,
395         .show   = seq_show,
396 };
397 
398 static int nflog_open(struct inode *inode, struct file *file)
399 {
400         return seq_open_net(inode, file, &nflog_seq_ops,
401                             sizeof(struct seq_net_private));
402 }
403 
404 static const struct file_operations nflog_file_ops = {
405         .owner   = THIS_MODULE,
406         .open    = nflog_open,
407         .read    = seq_read,
408         .llseek  = seq_lseek,
409         .release = seq_release_net,
410 };
411 
412 
413 #endif /* PROC_FS */
414 
415 #ifdef CONFIG_SYSCTL
416 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
417 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
418 static struct ctl_table_header *nf_log_sysctl_fhdr;
419 
420 static struct ctl_table nf_log_sysctl_ftable[] = {
421         {
422                 .procname       = "nf_log_all_netns",
423                 .data           = &sysctl_nf_log_all_netns,
424                 .maxlen         = sizeof(sysctl_nf_log_all_netns),
425                 .mode           = 0644,
426                 .proc_handler   = proc_dointvec,
427         },
428         { }
429 };
430 
431 static int nf_log_proc_dostring(struct ctl_table *table, int write,
432                          void __user *buffer, size_t *lenp, loff_t *ppos)
433 {
434         const struct nf_logger *logger;
435         char buf[NFLOGGER_NAME_LEN];
436         int r = 0;
437         int tindex = (unsigned long)table->extra1;
438         struct net *net = table->extra2;
439 
440         if (write) {
441                 struct ctl_table tmp = *table;
442 
443                 tmp.data = buf;
444                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
445                 if (r)
446                         return r;
447 
448                 if (!strcmp(buf, "NONE")) {
449                         nf_log_unbind_pf(net, tindex);
450                         return 0;
451                 }
452                 mutex_lock(&nf_log_mutex);
453                 logger = __find_logger(tindex, buf);
454                 if (logger == NULL) {
455                         mutex_unlock(&nf_log_mutex);
456                         return -ENOENT;
457                 }
458                 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
459                 mutex_unlock(&nf_log_mutex);
460         } else {
461                 mutex_lock(&nf_log_mutex);
462                 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
463                 if (!logger)
464                         table->data = "NONE";
465                 else
466                         table->data = logger->name;
467                 r = proc_dostring(table, write, buffer, lenp, ppos);
468                 mutex_unlock(&nf_log_mutex);
469         }
470 
471         return r;
472 }
473 
474 static int netfilter_log_sysctl_init(struct net *net)
475 {
476         int i;
477         struct ctl_table *table;
478 
479         table = nf_log_sysctl_table;
480         if (!net_eq(net, &init_net)) {
481                 table = kmemdup(nf_log_sysctl_table,
482                                  sizeof(nf_log_sysctl_table),
483                                  GFP_KERNEL);
484                 if (!table)
485                         goto err_alloc;
486         } else {
487                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
488                         snprintf(nf_log_sysctl_fnames[i],
489                                  3, "%d", i);
490                         nf_log_sysctl_table[i].procname =
491                                 nf_log_sysctl_fnames[i];
492                         nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
493                         nf_log_sysctl_table[i].mode = 0644;
494                         nf_log_sysctl_table[i].proc_handler =
495                                 nf_log_proc_dostring;
496                         nf_log_sysctl_table[i].extra1 =
497                                 (void *)(unsigned long) i;
498                 }
499                 nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
500                                                          nf_log_sysctl_ftable);
501                 if (!nf_log_sysctl_fhdr)
502                         goto err_freg;
503         }
504 
505         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
506                 table[i].extra2 = net;
507 
508         net->nf.nf_log_dir_header = register_net_sysctl(net,
509                                                 "net/netfilter/nf_log",
510                                                 table);
511         if (!net->nf.nf_log_dir_header)
512                 goto err_reg;
513 
514         return 0;
515 
516 err_reg:
517         if (!net_eq(net, &init_net))
518                 kfree(table);
519         else
520                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
521 err_freg:
522 err_alloc:
523         return -ENOMEM;
524 }
525 
526 static void netfilter_log_sysctl_exit(struct net *net)
527 {
528         struct ctl_table *table;
529 
530         table = net->nf.nf_log_dir_header->ctl_table_arg;
531         unregister_net_sysctl_table(net->nf.nf_log_dir_header);
532         if (!net_eq(net, &init_net))
533                 kfree(table);
534         else
535                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
536 }
537 #else
538 static int netfilter_log_sysctl_init(struct net *net)
539 {
540         return 0;
541 }
542 
543 static void netfilter_log_sysctl_exit(struct net *net)
544 {
545 }
546 #endif /* CONFIG_SYSCTL */
547 
548 static int __net_init nf_log_net_init(struct net *net)
549 {
550         int ret = -ENOMEM;
551 
552 #ifdef CONFIG_PROC_FS
553         if (!proc_create("nf_log", S_IRUGO,
554                          net->nf.proc_netfilter, &nflog_file_ops))
555                 return ret;
556 #endif
557         ret = netfilter_log_sysctl_init(net);
558         if (ret < 0)
559                 goto out_sysctl;
560 
561         return 0;
562 
563 out_sysctl:
564 #ifdef CONFIG_PROC_FS
565         remove_proc_entry("nf_log", net->nf.proc_netfilter);
566 #endif
567         return ret;
568 }
569 
570 static void __net_exit nf_log_net_exit(struct net *net)
571 {
572         netfilter_log_sysctl_exit(net);
573 #ifdef CONFIG_PROC_FS
574         remove_proc_entry("nf_log", net->nf.proc_netfilter);
575 #endif
576 }
577 
578 static struct pernet_operations nf_log_net_ops = {
579         .init = nf_log_net_init,
580         .exit = nf_log_net_exit,
581 };
582 
583 int __init netfilter_log_init(void)
584 {
585         return register_pernet_subsys(&nf_log_net_ops);
586 }
587 

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