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