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