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