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