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                 if (loggers[pf][i] == NULL)
  35                         continue;
  36
  37                 log = nft_log_dereference(loggers[pf][i]);
  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 == NFPROTO_INET) {
 160                 ret = nf_logger_find_get(NFPROTO_IPV4, type);
 161                 if (ret < 0)
 162                         return ret;
 163
 164                 ret = nf_logger_find_get(NFPROTO_IPV6, type);
 165                 if (ret < 0) {
 166                         nf_logger_put(NFPROTO_IPV4, type);
 167                         return ret;
 168                 }
 169
 170                 return 0;
 171         }
 172
 173         rcu_read_lock();
 174         logger = rcu_dereference(loggers[pf][type]);
 175         if (logger == NULL)
 176                 goto out;
 177
 178         if (try_module_get(logger->me))
 179                 ret = 0;
 180 out:
 181         rcu_read_unlock();
 182         return ret;
 183 }
 184 EXPORT_SYMBOL_GPL(nf_logger_find_get);
 185
 186 void nf_logger_put(int pf, enum nf_log_type type)
 187 {
 188         struct nf_logger *logger;
 189
 190         if (pf == NFPROTO_INET) {
 191                 nf_logger_put(NFPROTO_IPV4, type);
 192                 nf_logger_put(NFPROTO_IPV6, type);
 193                 return;
 194         }
 195
 196         BUG_ON(loggers[pf][type] == NULL);
 197
 198         rcu_read_lock();
 199         logger = rcu_dereference(loggers[pf][type]);
 200         module_put(logger->me);
 201         rcu_read_unlock();
 202 }
 203 EXPORT_SYMBOL_GPL(nf_logger_put);
 204
 205 void nf_log_packet(struct net *net,
 206                    u_int8_t pf,
 207                    unsigned int hooknum,
 208                    const struct sk_buff *skb,
 209                    const struct net_device *in,
 210                    const struct net_device *out,
 211                    const struct nf_loginfo *loginfo,
 212                    const char *fmt, ...)
 213 {
 214         va_list args;
 215         char prefix[NF_LOG_PREFIXLEN];
 216         const struct nf_logger *logger;
 217
 218         rcu_read_lock();
 219         if (loginfo != NULL)
 220                 logger = rcu_dereference(loggers[pf][loginfo->type]);
 221         else
 222                 logger = rcu_dereference(net->nf.nf_loggers[pf]);
 223
 224         if (logger) {
 225                 va_start(args, fmt);
 226                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 227                 va_end(args);
 228                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 229         }
 230         rcu_read_unlock();
 231 }
 232 EXPORT_SYMBOL(nf_log_packet);
 233
 234 void nf_log_trace(struct net *net,
 235                   u_int8_t pf,
 236                   unsigned int hooknum,
 237                   const struct sk_buff *skb,
 238                   const struct net_device *in,
 239                   const struct net_device *out,
 240                   const struct nf_loginfo *loginfo, const char *fmt, ...)
 241 {
 242         va_list args;
 243         char prefix[NF_LOG_PREFIXLEN];
 244         const struct nf_logger *logger;
 245
 246         rcu_read_lock();
 247         logger = rcu_dereference(net->nf.nf_loggers[pf]);
 248         if (logger) {
 249                 va_start(args, fmt);
 250                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 251                 va_end(args);
 252                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 253         }
 254         rcu_read_unlock();
 255 }
 256 EXPORT_SYMBOL(nf_log_trace);
 257
 258 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
 259
 260 struct nf_log_buf {
 261         unsigned int    count;
 262         char            buf[S_SIZE + 1];
 263 };
 264 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
 265
 266 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
 267 {
 268         va_list args;
 269         int len;
 270
 271         if (likely(m->count < S_SIZE)) {
 272                 va_start(args, f);
 273                 len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
 274                 va_end(args);
 275                 if (likely(m->count + len < S_SIZE)) {
 276                         m->count += len;
 277                         return 0;
 278                 }
 279         }
 280         m->count = S_SIZE;
 281         printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
 282         return -1;
 283 }
 284 EXPORT_SYMBOL_GPL(nf_log_buf_add);
 285
 286 struct nf_log_buf *nf_log_buf_open(void)
 287 {
 288         struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
 289
 290         if (unlikely(!m)) {
 291                 local_bh_disable();
 292                 do {
 293                         m = xchg(&emergency_ptr, NULL);
 294                 } while (!m);
 295         }
 296         m->count = 0;
 297         return m;
 298 }
 299 EXPORT_SYMBOL_GPL(nf_log_buf_open);
 300
 301 void nf_log_buf_close(struct nf_log_buf *m)
 302 {
 303         m->buf[m->count] = 0;
 304         printk("%s\n", m->buf);
 305
 306         if (likely(m != &emergency))
 307                 kfree(m);
 308         else {
 309                 emergency_ptr = m;
 310                 local_bh_enable();
 311         }
 312 }
 313 EXPORT_SYMBOL_GPL(nf_log_buf_close);
 314
 315 #ifdef CONFIG_PROC_FS
 316 static void *seq_start(struct seq_file *seq, loff_t *pos)
 317 {
 318         struct net *net = seq_file_net(seq);
 319
 320         mutex_lock(&nf_log_mutex);
 321
 322         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 323                 return NULL;
 324
 325         return pos;
 326 }
 327
 328 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 329 {
 330         struct net *net = seq_file_net(s);
 331
 332         (*pos)++;
 333
 334         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 335                 return NULL;
 336
 337         return pos;
 338 }
 339
 340 static void seq_stop(struct seq_file *s, void *v)
 341 {
 342         mutex_unlock(&nf_log_mutex);
 343 }
 344
 345 static int seq_show(struct seq_file *s, void *v)
 346 {
 347         loff_t *pos = v;
 348         const struct nf_logger *logger;
 349         int i;
 350         struct net *net = seq_file_net(s);
 351
 352         logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
 353
 354         if (!logger)
 355                 seq_printf(s, "%2lld NONE (", *pos);
 356         else
 357                 seq_printf(s, "%2lld %s (", *pos, logger->name);
 358
 359         if (seq_has_overflowed(s))
 360                 return -ENOSPC;
 361
 362         for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
 363                 if (loggers[*pos][i] == NULL)
 364                         continue;
 365
 366                 logger = nft_log_dereference(loggers[*pos][i]);
 367                 seq_puts(s, logger->name);
 368                 if (i == 0 && loggers[*pos][i + 1] != NULL)
 369                         seq_puts(s, ",");
 370
 371                 if (seq_has_overflowed(s))
 372                         return -ENOSPC;
 373         }
 374
 375         seq_puts(s, ")\n");
 376
 377         if (seq_has_overflowed(s))
 378                 return -ENOSPC;
 379         return 0;
 380 }
 381
 382 static const struct seq_operations nflog_seq_ops = {
 383         .start  = seq_start,
 384         .next   = seq_next,
 385         .stop   = seq_stop,
 386         .show   = seq_show,
 387 };
 388 #endif /* PROC_FS */
 389
 390 #ifdef CONFIG_SYSCTL
 391 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 392 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 393 static struct ctl_table_header *nf_log_sysctl_fhdr;
 394
 395 static struct ctl_table nf_log_sysctl_ftable[] = {
 396         {
 397                 .procname       = "nf_log_all_netns",
 398                 .data           = &sysctl_nf_log_all_netns,
 399                 .maxlen         = sizeof(sysctl_nf_log_all_netns),
 400                 .mode           = 0644,
 401                 .proc_handler   = proc_dointvec,
 402         },
 403         { }
 404 };
 405
 406 static int nf_log_proc_dostring(struct ctl_table *table, int write,
 407                          void *buffer, size_t *lenp, loff_t *ppos)
 408 {
 409         const struct nf_logger *logger;
 410         char buf[NFLOGGER_NAME_LEN];
 411         int r = 0;
 412         int tindex = (unsigned long)table->extra1;
 413         struct net *net = table->extra2;
 414
 415         if (write) {
 416                 struct ctl_table tmp = *table;
 417
 418                 /* proc_dostring() can append to existing strings, so we need to
 419                  * initialize it as an empty string.
 420                  */
 421                 buf[0] = '\0';
 422                 tmp.data = buf;
 423                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 424                 if (r)
 425                         return r;
 426
 427                 if (!strcmp(buf, "NONE")) {
 428                         nf_log_unbind_pf(net, tindex);
 429                         return 0;
 430                 }
 431                 mutex_lock(&nf_log_mutex);
 432                 logger = __find_logger(tindex, buf);
 433                 if (logger == NULL) {
 434                         mutex_unlock(&nf_log_mutex);
 435                         return -ENOENT;
 436                 }
 437                 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
 438                 mutex_unlock(&nf_log_mutex);
 439         } else {
 440                 struct ctl_table tmp = *table;
 441
 442                 tmp.data = buf;
 443                 mutex_lock(&nf_log_mutex);
 444                 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
 445                 if (!logger)
 446                         strlcpy(buf, "NONE", sizeof(buf));
 447                 else
 448                         strlcpy(buf, logger->name, sizeof(buf));
 449                 mutex_unlock(&nf_log_mutex);
 450                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 451         }
 452
 453         return r;
 454 }
 455
 456 static int netfilter_log_sysctl_init(struct net *net)
 457 {
 458         int i;
 459         struct ctl_table *table;
 460
 461         table = nf_log_sysctl_table;
 462         if (!net_eq(net, &init_net)) {
 463                 table = kmemdup(nf_log_sysctl_table,
 464                                  sizeof(nf_log_sysctl_table),
 465                                  GFP_KERNEL);
 466                 if (!table)
 467                         goto err_alloc;
 468         } else {
 469                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 470                         snprintf(nf_log_sysctl_fnames[i],
 471                                  3, "%d", i);
 472                         nf_log_sysctl_table[i].procname =
 473                                 nf_log_sysctl_fnames[i];
 474                         nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
 475                         nf_log_sysctl_table[i].mode = 0644;
 476                         nf_log_sysctl_table[i].proc_handler =
 477                                 nf_log_proc_dostring;
 478                         nf_log_sysctl_table[i].extra1 =
 479                                 (void *)(unsigned long) i;
 480                 }
 481                 nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
 482                                                          nf_log_sysctl_ftable);
 483                 if (!nf_log_sysctl_fhdr)
 484                         goto err_freg;
 485         }
 486
 487         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 488                 table[i].extra2 = net;
 489
 490         net->nf.nf_log_dir_header = register_net_sysctl(net,
 491                                                 "net/netfilter/nf_log",
 492                                                 table);
 493         if (!net->nf.nf_log_dir_header)
 494                 goto err_reg;
 495
 496         return 0;
 497
 498 err_reg:
 499         if (!net_eq(net, &init_net))
 500                 kfree(table);
 501         else
 502                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 503 err_freg:
 504 err_alloc:
 505         return -ENOMEM;
 506 }
 507
 508 static void netfilter_log_sysctl_exit(struct net *net)
 509 {
 510         struct ctl_table *table;
 511
 512         table = net->nf.nf_log_dir_header->ctl_table_arg;
 513         unregister_net_sysctl_table(net->nf.nf_log_dir_header);
 514         if (!net_eq(net, &init_net))
 515                 kfree(table);
 516         else
 517                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 518 }
 519 #else
 520 static int netfilter_log_sysctl_init(struct net *net)
 521 {
 522         return 0;
 523 }
 524
 525 static void netfilter_log_sysctl_exit(struct net *net)
 526 {
 527 }
 528 #endif /* CONFIG_SYSCTL */
 529
 530 static int __net_init nf_log_net_init(struct net *net)
 531 {
 532         int ret = -ENOMEM;
 533
 534 #ifdef CONFIG_PROC_FS
 535         if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
 536                         &nflog_seq_ops, sizeof(struct seq_net_private)))
 537                 return ret;
 538 #endif
 539         ret = netfilter_log_sysctl_init(net);
 540         if (ret < 0)
 541                 goto out_sysctl;
 542
 543         return 0;
 544
 545 out_sysctl:
 546 #ifdef CONFIG_PROC_FS
 547         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 548 #endif
 549         return ret;
 550 }
 551
 552 static void __net_exit nf_log_net_exit(struct net *net)
 553 {
 554         netfilter_log_sysctl_exit(net);
 555 #ifdef CONFIG_PROC_FS
 556         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 557 #endif
 558 }
 559
 560 static struct pernet_operations nf_log_net_ops = {
 561         .init = nf_log_net_init,
 562         .exit = nf_log_net_exit,
 563 };
 564
 565 int __init netfilter_log_init(void)
 566 {
 567         return register_pernet_subsys(&nf_log_net_ops);
 568 }