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 (rcu_access_pointer(loggers[pf][type]) == NULL)
 163                 request_module("nf-logger-%u-%u", pf, type);
 164
 165         rcu_read_lock();
 166         logger = rcu_dereference(loggers[pf][type]);
 167         if (logger == NULL)
 168                 goto out;
 169
 170         if (logger && try_module_get(logger->me))
 171                 ret = 0;
 172 out:
 173         rcu_read_unlock();
 174         return ret;
 175 }
 176 EXPORT_SYMBOL_GPL(nf_logger_find_get);
 177
 178 void nf_logger_put(int pf, enum nf_log_type type)
 179 {
 180         struct nf_logger *logger;
 181
 182         BUG_ON(loggers[pf][type] == NULL);
 183
 184         rcu_read_lock();
 185         logger = rcu_dereference(loggers[pf][type]);
 186         module_put(logger->me);
 187         rcu_read_unlock();
 188 }
 189 EXPORT_SYMBOL_GPL(nf_logger_put);
 190
 191 void nf_log_packet(struct net *net,
 192                    u_int8_t pf,
 193                    unsigned int hooknum,
 194                    const struct sk_buff *skb,
 195                    const struct net_device *in,
 196                    const struct net_device *out,
 197                    const struct nf_loginfo *loginfo,
 198                    const char *fmt, ...)
 199 {
 200         va_list args;
 201         char prefix[NF_LOG_PREFIXLEN];
 202         const struct nf_logger *logger;
 203
 204         rcu_read_lock();
 205         if (loginfo != NULL)
 206                 logger = rcu_dereference(loggers[pf][loginfo->type]);
 207         else
 208                 logger = rcu_dereference(net->nf.nf_loggers[pf]);
 209
 210         if (logger) {
 211                 va_start(args, fmt);
 212                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 213                 va_end(args);
 214                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 215         }
 216         rcu_read_unlock();
 217 }
 218 EXPORT_SYMBOL(nf_log_packet);
 219
 220 void nf_log_trace(struct net *net,
 221                   u_int8_t pf,
 222                   unsigned int hooknum,
 223                   const struct sk_buff *skb,
 224                   const struct net_device *in,
 225                   const struct net_device *out,
 226                   const struct nf_loginfo *loginfo, const char *fmt, ...)
 227 {
 228         va_list args;
 229         char prefix[NF_LOG_PREFIXLEN];
 230         const struct nf_logger *logger;
 231
 232         rcu_read_lock();
 233         logger = rcu_dereference(net->nf.nf_loggers[pf]);
 234         if (logger) {
 235                 va_start(args, fmt);
 236                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 237                 va_end(args);
 238                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 239         }
 240         rcu_read_unlock();
 241 }
 242 EXPORT_SYMBOL(nf_log_trace);
 243
 244 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
 245
 246 struct nf_log_buf {
 247         unsigned int    count;
 248         char            buf[S_SIZE + 1];
 249 };
 250 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
 251
 252 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
 253 {
 254         va_list args;
 255         int len;
 256
 257         if (likely(m->count < S_SIZE)) {
 258                 va_start(args, f);
 259                 len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
 260                 va_end(args);
 261                 if (likely(m->count + len < S_SIZE)) {
 262                         m->count += len;
 263                         return 0;
 264                 }
 265         }
 266         m->count = S_SIZE;
 267         printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
 268         return -1;
 269 }
 270 EXPORT_SYMBOL_GPL(nf_log_buf_add);
 271
 272 struct nf_log_buf *nf_log_buf_open(void)
 273 {
 274         struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
 275
 276         if (unlikely(!m)) {
 277                 local_bh_disable();
 278                 do {
 279                         m = xchg(&emergency_ptr, NULL);
 280                 } while (!m);
 281         }
 282         m->count = 0;
 283         return m;
 284 }
 285 EXPORT_SYMBOL_GPL(nf_log_buf_open);
 286
 287 void nf_log_buf_close(struct nf_log_buf *m)
 288 {
 289         m->buf[m->count] = 0;
 290         printk("%s\n", m->buf);
 291
 292         if (likely(m != &emergency))
 293                 kfree(m);
 294         else {
 295                 emergency_ptr = m;
 296                 local_bh_enable();
 297         }
 298 }
 299 EXPORT_SYMBOL_GPL(nf_log_buf_close);
 300
 301 #ifdef CONFIG_PROC_FS
 302 static void *seq_start(struct seq_file *seq, loff_t *pos)
 303 {
 304         struct net *net = seq_file_net(seq);
 305
 306         mutex_lock(&nf_log_mutex);
 307
 308         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 309                 return NULL;
 310
 311         return pos;
 312 }
 313
 314 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 315 {
 316         struct net *net = seq_file_net(s);
 317
 318         (*pos)++;
 319
 320         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 321                 return NULL;
 322
 323         return pos;
 324 }
 325
 326 static void seq_stop(struct seq_file *s, void *v)
 327 {
 328         mutex_unlock(&nf_log_mutex);
 329 }
 330
 331 static int seq_show(struct seq_file *s, void *v)
 332 {
 333         loff_t *pos = v;
 334         const struct nf_logger *logger;
 335         int i;
 336         struct net *net = seq_file_net(s);
 337
 338         logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
 339
 340         if (!logger)
 341                 seq_printf(s, "%2lld NONE (", *pos);
 342         else
 343                 seq_printf(s, "%2lld %s (", *pos, logger->name);
 344
 345         if (seq_has_overflowed(s))
 346                 return -ENOSPC;
 347
 348         for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
 349                 if (loggers[*pos][i] == NULL)
 350                         continue;
 351
 352                 logger = nft_log_dereference(loggers[*pos][i]);
 353                 seq_printf(s, "%s", logger->name);
 354                 if (i == 0 && loggers[*pos][i + 1] != NULL)
 355                         seq_printf(s, ",");
 356
 357                 if (seq_has_overflowed(s))
 358                         return -ENOSPC;
 359         }
 360
 361         seq_printf(s, ")\n");
 362
 363         if (seq_has_overflowed(s))
 364                 return -ENOSPC;
 365         return 0;
 366 }
 367
 368 static const struct seq_operations nflog_seq_ops = {
 369         .start  = seq_start,
 370         .next   = seq_next,
 371         .stop   = seq_stop,
 372         .show   = seq_show,
 373 };
 374
 375 static int nflog_open(struct inode *inode, struct file *file)
 376 {
 377         return seq_open_net(inode, file, &nflog_seq_ops,
 378                             sizeof(struct seq_net_private));
 379 }
 380
 381 static const struct file_operations nflog_file_ops = {
 382         .owner   = THIS_MODULE,
 383         .open    = nflog_open,
 384         .read    = seq_read,
 385         .llseek  = seq_lseek,
 386         .release = seq_release_net,
 387 };
 388
 389
 390 #endif /* PROC_FS */
 391
 392 #ifdef CONFIG_SYSCTL
 393 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 394 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 395
 396 static int nf_log_proc_dostring(struct ctl_table *table, int write,
 397                          void __user *buffer, size_t *lenp, loff_t *ppos)
 398 {
 399         const struct nf_logger *logger;
 400         char buf[NFLOGGER_NAME_LEN];
 401         size_t size = *lenp;
 402         int r = 0;
 403         int tindex = (unsigned long)table->extra1;
 404         struct net *net = table->extra2;
 405
 406         if (write) {
 407                 if (size > sizeof(buf))
 408                         size = sizeof(buf);
 409                 if (copy_from_user(buf, buffer, size))
 410                         return -EFAULT;
 411
 412                 if (!strcmp(buf, "NONE")) {
 413                         nf_log_unbind_pf(net, tindex);
 414                         return 0;
 415                 }
 416                 mutex_lock(&nf_log_mutex);
 417                 logger = __find_logger(tindex, buf);
 418                 if (logger == NULL) {
 419                         mutex_unlock(&nf_log_mutex);
 420                         return -ENOENT;
 421                 }
 422                 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
 423                 mutex_unlock(&nf_log_mutex);
 424         } else {
 425                 mutex_lock(&nf_log_mutex);
 426                 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
 427                 if (!logger)
 428                         table->data = "NONE";
 429                 else
 430                         table->data = logger->name;
 431                 r = proc_dostring(table, write, buffer, lenp, ppos);
 432                 mutex_unlock(&nf_log_mutex);
 433         }
 434
 435         return r;
 436 }
 437
 438 static int netfilter_log_sysctl_init(struct net *net)
 439 {
 440         int i;
 441         struct ctl_table *table;
 442
 443         table = nf_log_sysctl_table;
 444         if (!net_eq(net, &init_net)) {
 445                 table = kmemdup(nf_log_sysctl_table,
 446                                  sizeof(nf_log_sysctl_table),
 447                                  GFP_KERNEL);
 448                 if (!table)
 449                         goto err_alloc;
 450         } else {
 451                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 452                         snprintf(nf_log_sysctl_fnames[i],
 453                                  3, "%d", i);
 454                         nf_log_sysctl_table[i].procname =
 455                                 nf_log_sysctl_fnames[i];
 456                         nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
 457                         nf_log_sysctl_table[i].mode = 0644;
 458                         nf_log_sysctl_table[i].proc_handler =
 459                                 nf_log_proc_dostring;
 460                         nf_log_sysctl_table[i].extra1 =
 461                                 (void *)(unsigned long) i;
 462                 }
 463         }
 464
 465         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 466                 table[i].extra2 = net;
 467
 468         net->nf.nf_log_dir_header = register_net_sysctl(net,
 469                                                 "net/netfilter/nf_log",
 470                                                 table);
 471         if (!net->nf.nf_log_dir_header)
 472                 goto err_reg;
 473
 474         return 0;
 475
 476 err_reg:
 477         if (!net_eq(net, &init_net))
 478                 kfree(table);
 479 err_alloc:
 480         return -ENOMEM;
 481 }
 482
 483 static void netfilter_log_sysctl_exit(struct net *net)
 484 {
 485         struct ctl_table *table;
 486
 487         table = net->nf.nf_log_dir_header->ctl_table_arg;
 488         unregister_net_sysctl_table(net->nf.nf_log_dir_header);
 489         if (!net_eq(net, &init_net))
 490                 kfree(table);
 491 }
 492 #else
 493 static int netfilter_log_sysctl_init(struct net *net)
 494 {
 495         return 0;
 496 }
 497
 498 static void netfilter_log_sysctl_exit(struct net *net)
 499 {
 500 }
 501 #endif /* CONFIG_SYSCTL */
 502
 503 static int __net_init nf_log_net_init(struct net *net)
 504 {
 505         int ret = -ENOMEM;
 506
 507 #ifdef CONFIG_PROC_FS
 508         if (!proc_create("nf_log", S_IRUGO,
 509                          net->nf.proc_netfilter, &nflog_file_ops))
 510                 return ret;
 511 #endif
 512         ret = netfilter_log_sysctl_init(net);
 513         if (ret < 0)
 514                 goto out_sysctl;
 515
 516         return 0;
 517
 518 out_sysctl:
 519 #ifdef CONFIG_PROC_FS
 520         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 521 #endif
 522         return ret;
 523 }
 524
 525 static void __net_exit nf_log_net_exit(struct net *net)
 526 {
 527         netfilter_log_sysctl_exit(net);
 528 #ifdef CONFIG_PROC_FS
 529         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 530 #endif
 531 }
 532
 533 static struct pernet_operations nf_log_net_ops = {
 534         .init = nf_log_net_init,
 535         .exit = nf_log_net_exit,
 536 };
 537
 538 int __init netfilter_log_init(void)
 539 {
 540         return register_pernet_subsys(&nf_log_net_ops);
 541 }