net/netfilter/nf_log.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/kernel.h>
   3 #include <linux/init.h>
   4 #include <linux/module.h>
   5 #include <linux/proc_fs.h>
   6 #include <linux/skbuff.h>
   7 #include <linux/netfilter.h>
   8 #include <linux/seq_file.h>
   9 #include <net/protocol.h>
  10 #include <net/netfilter/nf_log.h>
  11
  12 #include "nf_internals.h"
  13
  14 /* Internal logging interface, which relies on the real
  15    LOG target modules */
  16
  17 #define NFLOGGER_NAME_LEN               64
  18
  19 int sysctl_nf_log_all_netns __read_mostly;
  20 EXPORT_SYMBOL(sysctl_nf_log_all_netns);
  21
  22 static struct nf_logger __rcu *loggers[NFPROTO_NUMPROTO][NF_LOG_TYPE_MAX] __read_mostly;
  23 static DEFINE_MUTEX(nf_log_mutex);
  24
  25 #define nft_log_dereference(logger) \
  26         rcu_dereference_protected(logger, lockdep_is_held(&nf_log_mutex))
  27
  28 static struct nf_logger *__find_logger(int pf, const char *str_logger)
  29 {
  30         struct nf_logger *log;
  31         int i;
  32
  33         for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
  34                 log = nft_log_dereference(loggers[pf][i]);
  35                 if (!log)
  36                         continue;
  37
  38                 if (!strncasecmp(str_logger, log->name, strlen(log->name)))
  39                         return log;
  40         }
  41
  42         return NULL;
  43 }
  44
  45 int nf_log_set(struct net *net, u_int8_t pf, const struct nf_logger *logger)
  46 {
  47         const struct nf_logger *log;
  48
  49         if (pf == NFPROTO_UNSPEC || pf >= ARRAY_SIZE(net->nf.nf_loggers))
  50                 return -EOPNOTSUPP;
  51
  52         mutex_lock(&nf_log_mutex);
  53         log = nft_log_dereference(net->nf.nf_loggers[pf]);
  54         if (log == NULL)
  55                 rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
  56
  57         mutex_unlock(&nf_log_mutex);
  58
  59         return 0;
  60 }
  61 EXPORT_SYMBOL(nf_log_set);
  62
  63 void nf_log_unset(struct net *net, const struct nf_logger *logger)
  64 {
  65         int i;
  66         const struct nf_logger *log;
  67
  68         mutex_lock(&nf_log_mutex);
  69         for (i = 0; i < NFPROTO_NUMPROTO; i++) {
  70                 log = nft_log_dereference(net->nf.nf_loggers[i]);
  71                 if (log == logger)
  72                         RCU_INIT_POINTER(net->nf.nf_loggers[i], NULL);
  73         }
  74         mutex_unlock(&nf_log_mutex);
  75 }
  76 EXPORT_SYMBOL(nf_log_unset);
  77
  78 /* return EEXIST if the same logger is registered, 0 on success. */
  79 int nf_log_register(u_int8_t pf, struct nf_logger *logger)
  80 {
  81         int i;
  82         int ret = 0;
  83
  84         if (pf >= ARRAY_SIZE(init_net.nf.nf_loggers))
  85                 return -EINVAL;
  86
  87         mutex_lock(&nf_log_mutex);
  88
  89         if (pf == NFPROTO_UNSPEC) {
  90                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
  91                         if (rcu_access_pointer(loggers[i][logger->type])) {
  92                                 ret = -EEXIST;
  93                                 goto unlock;
  94                         }
  95                 }
  96                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
  97                         rcu_assign_pointer(loggers[i][logger->type], logger);
  98         } else {
  99                 if (rcu_access_pointer(loggers[pf][logger->type])) {
 100                         ret = -EEXIST;
 101                         goto unlock;
 102                 }
 103                 rcu_assign_pointer(loggers[pf][logger->type], logger);
 104         }
 105
 106 unlock:
 107         mutex_unlock(&nf_log_mutex);
 108         return ret;
 109 }
 110 EXPORT_SYMBOL(nf_log_register);
 111
 112 void nf_log_unregister(struct nf_logger *logger)
 113 {
 114         const struct nf_logger *log;
 115         int i;
 116
 117         mutex_lock(&nf_log_mutex);
 118         for (i = 0; i < NFPROTO_NUMPROTO; i++) {
 119                 log = nft_log_dereference(loggers[i][logger->type]);
 120                 if (log == logger)
 121                         RCU_INIT_POINTER(loggers[i][logger->type], NULL);
 122         }
 123         mutex_unlock(&nf_log_mutex);
 124         synchronize_rcu();
 125 }
 126 EXPORT_SYMBOL(nf_log_unregister);
 127
 128 int nf_log_bind_pf(struct net *net, u_int8_t pf,
 129                    const struct nf_logger *logger)
 130 {
 131         if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
 132                 return -EINVAL;
 133         mutex_lock(&nf_log_mutex);
 134         if (__find_logger(pf, logger->name) == NULL) {
 135                 mutex_unlock(&nf_log_mutex);
 136                 return -ENOENT;
 137         }
 138         rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
 139         mutex_unlock(&nf_log_mutex);
 140         return 0;
 141 }
 142 EXPORT_SYMBOL(nf_log_bind_pf);
 143
 144 void nf_log_unbind_pf(struct net *net, u_int8_t pf)
 145 {
 146         if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
 147                 return;
 148         mutex_lock(&nf_log_mutex);
 149         RCU_INIT_POINTER(net->nf.nf_loggers[pf], NULL);
 150         mutex_unlock(&nf_log_mutex);
 151 }
 152 EXPORT_SYMBOL(nf_log_unbind_pf);
 153
 154 int nf_logger_find_get(int pf, enum nf_log_type type)
 155 {
 156         struct nf_logger *logger;
 157         int ret = -ENOENT;
 158
 159         if (pf >= ARRAY_SIZE(loggers))
 160                 return -EINVAL;
 161         if (type >= NF_LOG_TYPE_MAX)
 162                 return -EINVAL;
 163
 164         if (pf == NFPROTO_INET) {
 165                 ret = nf_logger_find_get(NFPROTO_IPV4, type);
 166                 if (ret < 0)
 167                         return ret;
 168
 169                 ret = nf_logger_find_get(NFPROTO_IPV6, type);
 170                 if (ret < 0) {
 171                         nf_logger_put(NFPROTO_IPV4, type);
 172                         return ret;
 173                 }
 174
 175                 return 0;
 176         }
 177
 178         rcu_read_lock();
 179         logger = rcu_dereference(loggers[pf][type]);
 180         if (logger == NULL)
 181                 goto out;
 182
 183         if (try_module_get(logger->me))
 184                 ret = 0;
 185 out:
 186         rcu_read_unlock();
 187         return ret;
 188 }
 189 EXPORT_SYMBOL_GPL(nf_logger_find_get);
 190
 191 void nf_logger_put(int pf, enum nf_log_type type)
 192 {
 193         struct nf_logger *logger;
 194
 195         if (pf == NFPROTO_INET) {
 196                 nf_logger_put(NFPROTO_IPV4, type);
 197                 nf_logger_put(NFPROTO_IPV6, type);
 198                 return;
 199         }
 200
 201         rcu_read_lock();
 202         logger = rcu_dereference(loggers[pf][type]);
 203         if (!logger)
 204                 WARN_ON_ONCE(1);
 205         else
 206                 module_put(logger->me);
 207         rcu_read_unlock();
 208 }
 209 EXPORT_SYMBOL_GPL(nf_logger_put);
 210
 211 void nf_log_packet(struct net *net,
 212                    u_int8_t pf,
 213                    unsigned int hooknum,
 214                    const struct sk_buff *skb,
 215                    const struct net_device *in,
 216                    const struct net_device *out,
 217                    const struct nf_loginfo *loginfo,
 218                    const char *fmt, ...)
 219 {
 220         va_list args;
 221         char prefix[NF_LOG_PREFIXLEN];
 222         const struct nf_logger *logger;
 223
 224         rcu_read_lock();
 225         if (loginfo != NULL)
 226                 logger = rcu_dereference(loggers[pf][loginfo->type]);
 227         else
 228                 logger = rcu_dereference(net->nf.nf_loggers[pf]);
 229
 230         if (logger) {
 231                 va_start(args, fmt);
 232                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 233                 va_end(args);
 234                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 235         }
 236         rcu_read_unlock();
 237 }
 238 EXPORT_SYMBOL(nf_log_packet);
 239
 240 void nf_log_trace(struct net *net,
 241                   u_int8_t pf,
 242                   unsigned int hooknum,
 243                   const struct sk_buff *skb,
 244                   const struct net_device *in,
 245                   const struct net_device *out,
 246                   const struct nf_loginfo *loginfo, const char *fmt, ...)
 247 {
 248         va_list args;
 249         char prefix[NF_LOG_PREFIXLEN];
 250         const struct nf_logger *logger;
 251
 252         rcu_read_lock();
 253         logger = rcu_dereference(net->nf.nf_loggers[pf]);
 254         if (logger) {
 255                 va_start(args, fmt);
 256                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 257                 va_end(args);
 258                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 259         }
 260         rcu_read_unlock();
 261 }
 262 EXPORT_SYMBOL(nf_log_trace);
 263
 264 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
 265
 266 struct nf_log_buf {
 267         unsigned int    count;
 268         char            buf[S_SIZE + 1];
 269 };
 270 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
 271
 272 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
 273 {
 274         va_list args;
 275         int len;
 276
 277         if (likely(m->count < S_SIZE)) {
 278                 va_start(args, f);
 279                 len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
 280                 va_end(args);
 281                 if (likely(m->count + len < S_SIZE)) {
 282                         m->count += len;
 283                         return 0;
 284                 }
 285         }
 286         m->count = S_SIZE;
 287         printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
 288         return -1;
 289 }
 290 EXPORT_SYMBOL_GPL(nf_log_buf_add);
 291
 292 struct nf_log_buf *nf_log_buf_open(void)
 293 {
 294         struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
 295
 296         if (unlikely(!m)) {
 297                 local_bh_disable();
 298                 do {
 299                         m = xchg(&emergency_ptr, NULL);
 300                 } while (!m);
 301         }
 302         m->count = 0;
 303         return m;
 304 }
 305 EXPORT_SYMBOL_GPL(nf_log_buf_open);
 306
 307 void nf_log_buf_close(struct nf_log_buf *m)
 308 {
 309         m->buf[m->count] = 0;
 310         printk("%s\n", m->buf);
 311
 312         if (likely(m != &emergency))
 313                 kfree(m);
 314         else {
 315                 emergency_ptr = m;
 316                 local_bh_enable();
 317         }
 318 }
 319 EXPORT_SYMBOL_GPL(nf_log_buf_close);
 320
 321 #ifdef CONFIG_PROC_FS
 322 static void *seq_start(struct seq_file *seq, loff_t *pos)
 323 {
 324         struct net *net = seq_file_net(seq);
 325
 326         mutex_lock(&nf_log_mutex);
 327
 328         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 329                 return NULL;
 330
 331         return pos;
 332 }
 333
 334 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 335 {
 336         struct net *net = seq_file_net(s);
 337
 338         (*pos)++;
 339
 340         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 341                 return NULL;
 342
 343         return pos;
 344 }
 345
 346 static void seq_stop(struct seq_file *s, void *v)
 347 {
 348         mutex_unlock(&nf_log_mutex);
 349 }
 350
 351 static int seq_show(struct seq_file *s, void *v)
 352 {
 353         loff_t *pos = v;
 354         const struct nf_logger *logger;
 355         int i;
 356         struct net *net = seq_file_net(s);
 357
 358         logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
 359
 360         if (!logger)
 361                 seq_printf(s, "%2lld NONE (", *pos);
 362         else
 363                 seq_printf(s, "%2lld %s (", *pos, logger->name);
 364
 365         if (seq_has_overflowed(s))
 366                 return -ENOSPC;
 367
 368         for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
 369                 if (loggers[*pos][i] == NULL)
 370                         continue;
 371
 372                 logger = nft_log_dereference(loggers[*pos][i]);
 373                 seq_puts(s, logger->name);
 374                 if (i == 0 && loggers[*pos][i + 1] != NULL)
 375                         seq_puts(s, ",");
 376
 377                 if (seq_has_overflowed(s))
 378                         return -ENOSPC;
 379         }
 380
 381         seq_puts(s, ")\n");
 382
 383         if (seq_has_overflowed(s))
 384                 return -ENOSPC;
 385         return 0;
 386 }
 387
 388 static const struct seq_operations nflog_seq_ops = {
 389         .start  = seq_start,
 390         .next   = seq_next,
 391         .stop   = seq_stop,
 392         .show   = seq_show,
 393 };
 394 #endif /* PROC_FS */
 395
 396 #ifdef CONFIG_SYSCTL
 397 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 398 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 399 static struct ctl_table_header *nf_log_sysctl_fhdr;
 400
 401 static struct ctl_table nf_log_sysctl_ftable[] = {
 402         {
 403                 .procname       = "nf_log_all_netns",
 404                 .data           = &sysctl_nf_log_all_netns,
 405                 .maxlen         = sizeof(sysctl_nf_log_all_netns),
 406                 .mode           = 0644,
 407                 .proc_handler   = proc_dointvec,
 408         },
 409         { }
 410 };
 411
 412 static int nf_log_proc_dostring(struct ctl_table *table, int write,
 413                          void *buffer, size_t *lenp, loff_t *ppos)
 414 {
 415         const struct nf_logger *logger;
 416         char buf[NFLOGGER_NAME_LEN];
 417         int r = 0;
 418         int tindex = (unsigned long)table->extra1;
 419         struct net *net = table->extra2;
 420
 421         if (write) {
 422                 struct ctl_table tmp = *table;
 423
 424                 /* proc_dostring() can append to existing strings, so we need to
 425                  * initialize it as an empty string.
 426                  */
 427                 buf[0] = '\0';
 428                 tmp.data = buf;
 429                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 430                 if (r)
 431                         return r;
 432
 433                 if (!strcmp(buf, "NONE")) {
 434                         nf_log_unbind_pf(net, tindex);
 435                         return 0;
 436                 }
 437                 mutex_lock(&nf_log_mutex);
 438                 logger = __find_logger(tindex, buf);
 439                 if (logger == NULL) {
 440                         mutex_unlock(&nf_log_mutex);
 441                         return -ENOENT;
 442                 }
 443                 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
 444                 mutex_unlock(&nf_log_mutex);
 445         } else {
 446                 struct ctl_table tmp = *table;
 447
 448                 tmp.data = buf;
 449                 mutex_lock(&nf_log_mutex);
 450                 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
 451                 if (!logger)
 452                         strscpy(buf, "NONE", sizeof(buf));
 453                 else
 454                         strscpy(buf, logger->name, sizeof(buf));
 455                 mutex_unlock(&nf_log_mutex);
 456                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 457         }
 458
 459         return r;
 460 }
 461
 462 static int netfilter_log_sysctl_init(struct net *net)
 463 {
 464         int i;
 465         struct ctl_table *table;
 466
 467         table = nf_log_sysctl_table;
 468         if (!net_eq(net, &init_net)) {
 469                 table = kmemdup(nf_log_sysctl_table,
 470                                  sizeof(nf_log_sysctl_table),
 471                                  GFP_KERNEL);
 472                 if (!table)
 473                         goto err_alloc;
 474         } else {
 475                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 476                         snprintf(nf_log_sysctl_fnames[i],
 477                                  3, "%d", i);
 478                         nf_log_sysctl_table[i].procname =
 479                                 nf_log_sysctl_fnames[i];
 480                         nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
 481                         nf_log_sysctl_table[i].mode = 0644;
 482                         nf_log_sysctl_table[i].proc_handler =
 483                                 nf_log_proc_dostring;
 484                         nf_log_sysctl_table[i].extra1 =
 485                                 (void *)(unsigned long) i;
 486                 }
 487                 nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
 488                                                          nf_log_sysctl_ftable);
 489                 if (!nf_log_sysctl_fhdr)
 490                         goto err_freg;
 491         }
 492
 493         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 494                 table[i].extra2 = net;
 495
 496         net->nf.nf_log_dir_header = register_net_sysctl_sz(net,
 497                                                            "net/netfilter/nf_log",
 498                                                            table,
 499                                                            ARRAY_SIZE(nf_log_sysctl_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         else
 509                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 510 err_freg:
 511 err_alloc:
 512         return -ENOMEM;
 513 }
 514
 515 static void netfilter_log_sysctl_exit(struct net *net)
 516 {
 517         struct ctl_table *table;
 518
 519         table = net->nf.nf_log_dir_header->ctl_table_arg;
 520         unregister_net_sysctl_table(net->nf.nf_log_dir_header);
 521         if (!net_eq(net, &init_net))
 522                 kfree(table);
 523         else
 524                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 525 }
 526 #else
 527 static int netfilter_log_sysctl_init(struct net *net)
 528 {
 529         return 0;
 530 }
 531
 532 static void netfilter_log_sysctl_exit(struct net *net)
 533 {
 534 }
 535 #endif /* CONFIG_SYSCTL */
 536
 537 static int __net_init nf_log_net_init(struct net *net)
 538 {
 539         int ret = -ENOMEM;
 540
 541 #ifdef CONFIG_PROC_FS
 542         if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
 543                         &nflog_seq_ops, sizeof(struct seq_net_private)))
 544                 return ret;
 545 #endif
 546         ret = netfilter_log_sysctl_init(net);
 547         if (ret < 0)
 548                 goto out_sysctl;
 549
 550         return 0;
 551
 552 out_sysctl:
 553 #ifdef CONFIG_PROC_FS
 554         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 555 #endif
 556         return ret;
 557 }
 558
 559 static void __net_exit nf_log_net_exit(struct net *net)
 560 {
 561         netfilter_log_sysctl_exit(net);
 562 #ifdef CONFIG_PROC_FS
 563         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 564 #endif
 565 }
 566
 567 static struct pernet_operations nf_log_net_ops = {
 568         .init = nf_log_net_init,
 569         .exit = nf_log_net_exit,
 570 };
 571
 572 int __init netfilter_log_init(void)
 573 {
 574         return register_pernet_subsys(&nf_log_net_ops);
 575 }