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