net/netfilter/nf_log.c

   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 #endif /* PROC_FS */
 398
 399 #ifdef CONFIG_SYSCTL
 400 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 401 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 402 static struct ctl_table_header *nf_log_sysctl_fhdr;
 403
 404 static struct ctl_table nf_log_sysctl_ftable[] = {
 405         {
 406                 .procname       = "nf_log_all_netns",
 407                 .data           = &sysctl_nf_log_all_netns,
 408                 .maxlen         = sizeof(sysctl_nf_log_all_netns),
 409                 .mode           = 0644,
 410                 .proc_handler   = proc_dointvec,
 411         },
 412         { }
 413 };
 414
 415 static int nf_log_proc_dostring(struct ctl_table *table, int write,
 416                          void __user *buffer, size_t *lenp, loff_t *ppos)
 417 {
 418         const struct nf_logger *logger;
 419         char buf[NFLOGGER_NAME_LEN];
 420         int r = 0;
 421         int tindex = (unsigned long)table->extra1;
 422         struct net *net = table->extra2;
 423
 424         if (write) {
 425                 struct ctl_table tmp = *table;
 426
 427                 /* proc_dostring() can append to existing strings, so we need to
 428                  * initialize it as an empty string.
 429                  */
 430                 buf[0] = '\0';
 431                 tmp.data = buf;
 432                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 433                 if (r)
 434                         return r;
 435
 436                 if (!strcmp(buf, "NONE")) {
 437                         nf_log_unbind_pf(net, tindex);
 438                         return 0;
 439                 }
 440                 mutex_lock(&nf_log_mutex);
 441                 logger = __find_logger(tindex, buf);
 442                 if (logger == NULL) {
 443                         mutex_unlock(&nf_log_mutex);
 444                         return -ENOENT;
 445                 }
 446                 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
 447                 mutex_unlock(&nf_log_mutex);
 448         } else {
 449                 struct ctl_table tmp = *table;
 450
 451                 tmp.data = buf;
 452                 mutex_lock(&nf_log_mutex);
 453                 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
 454                 if (!logger)
 455                         strlcpy(buf, "NONE", sizeof(buf));
 456                 else
 457                         strlcpy(buf, logger->name, sizeof(buf));
 458                 mutex_unlock(&nf_log_mutex);
 459                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 460         }
 461
 462         return r;
 463 }
 464
 465 static int netfilter_log_sysctl_init(struct net *net)
 466 {
 467         int i;
 468         struct ctl_table *table;
 469
 470         table = nf_log_sysctl_table;
 471         if (!net_eq(net, &init_net)) {
 472                 table = kmemdup(nf_log_sysctl_table,
 473                                  sizeof(nf_log_sysctl_table),
 474                                  GFP_KERNEL);
 475                 if (!table)
 476                         goto err_alloc;
 477         } else {
 478                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 479                         snprintf(nf_log_sysctl_fnames[i],
 480                                  3, "%d", i);
 481                         nf_log_sysctl_table[i].procname =
 482                                 nf_log_sysctl_fnames[i];
 483                         nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
 484                         nf_log_sysctl_table[i].mode = 0644;
 485                         nf_log_sysctl_table[i].proc_handler =
 486                                 nf_log_proc_dostring;
 487                         nf_log_sysctl_table[i].extra1 =
 488                                 (void *)(unsigned long) i;
 489                 }
 490                 nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
 491                                                          nf_log_sysctl_ftable);
 492                 if (!nf_log_sysctl_fhdr)
 493                         goto err_freg;
 494         }
 495
 496         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 497                 table[i].extra2 = net;
 498
 499         net->nf.nf_log_dir_header = register_net_sysctl(net,
 500                                                 "net/netfilter/nf_log",
 501                                                 table);
 502         if (!net->nf.nf_log_dir_header)
 503                 goto err_reg;
 504
 505         return 0;
 506
 507 err_reg:
 508         if (!net_eq(net, &init_net))
 509                 kfree(table);
 510         else
 511                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 512 err_freg:
 513 err_alloc:
 514         return -ENOMEM;
 515 }
 516
 517 static void netfilter_log_sysctl_exit(struct net *net)
 518 {
 519         struct ctl_table *table;
 520
 521         table = net->nf.nf_log_dir_header->ctl_table_arg;
 522         unregister_net_sysctl_table(net->nf.nf_log_dir_header);
 523         if (!net_eq(net, &init_net))
 524                 kfree(table);
 525         else
 526                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 527 }
 528 #else
 529 static int netfilter_log_sysctl_init(struct net *net)
 530 {
 531         return 0;
 532 }
 533
 534 static void netfilter_log_sysctl_exit(struct net *net)
 535 {
 536 }
 537 #endif /* CONFIG_SYSCTL */
 538
 539 static int __net_init nf_log_net_init(struct net *net)
 540 {
 541         int ret = -ENOMEM;
 542
 543 #ifdef CONFIG_PROC_FS
 544         if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
 545                         &nflog_seq_ops, sizeof(struct seq_net_private)))
 546                 return ret;
 547 #endif
 548         ret = netfilter_log_sysctl_init(net);
 549         if (ret < 0)
 550                 goto out_sysctl;
 551
 552         return 0;
 553
 554 out_sysctl:
 555 #ifdef CONFIG_PROC_FS
 556         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 557 #endif
 558         return ret;
 559 }
 560
 561 static void __net_exit nf_log_net_exit(struct net *net)
 562 {
 563         netfilter_log_sysctl_exit(net);
 564 #ifdef CONFIG_PROC_FS
 565         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 566 #endif
 567 }
 568
 569 static struct pernet_operations nf_log_net_ops = {
 570         .init = nf_log_net_init,
 571         .exit = nf_log_net_exit,
 572 };
 573
 574 int __init netfilter_log_init(void)
 575 {
 576         return register_pernet_subsys(&nf_log_net_ops);
 577 }