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