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 == 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         rcu_read_lock();
 197         logger = rcu_dereference(loggers[pf][type]);
 198         if (!logger)
 199                 WARN_ON_ONCE(1);
 200         else
 201                 module_put(logger->me);
 202         rcu_read_unlock();
 203 }
 204 EXPORT_SYMBOL_GPL(nf_logger_put);
 205
 206 void nf_log_packet(struct net *net,
 207                    u_int8_t pf,
 208                    unsigned int hooknum,
 209                    const struct sk_buff *skb,
 210                    const struct net_device *in,
 211                    const struct net_device *out,
 212                    const struct nf_loginfo *loginfo,
 213                    const char *fmt, ...)
 214 {
 215         va_list args;
 216         char prefix[NF_LOG_PREFIXLEN];
 217         const struct nf_logger *logger;
 218
 219         rcu_read_lock();
 220         if (loginfo != NULL)
 221                 logger = rcu_dereference(loggers[pf][loginfo->type]);
 222         else
 223                 logger = rcu_dereference(net->nf.nf_loggers[pf]);
 224
 225         if (logger) {
 226                 va_start(args, fmt);
 227                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 228                 va_end(args);
 229                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 230         }
 231         rcu_read_unlock();
 232 }
 233 EXPORT_SYMBOL(nf_log_packet);
 234
 235 void nf_log_trace(struct net *net,
 236                   u_int8_t pf,
 237                   unsigned int hooknum,
 238                   const struct sk_buff *skb,
 239                   const struct net_device *in,
 240                   const struct net_device *out,
 241                   const struct nf_loginfo *loginfo, const char *fmt, ...)
 242 {
 243         va_list args;
 244         char prefix[NF_LOG_PREFIXLEN];
 245         const struct nf_logger *logger;
 246
 247         rcu_read_lock();
 248         logger = rcu_dereference(net->nf.nf_loggers[pf]);
 249         if (logger) {
 250                 va_start(args, fmt);
 251                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 252                 va_end(args);
 253                 logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
 254         }
 255         rcu_read_unlock();
 256 }
 257 EXPORT_SYMBOL(nf_log_trace);
 258
 259 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
 260
 261 struct nf_log_buf {
 262         unsigned int    count;
 263         char            buf[S_SIZE + 1];
 264 };
 265 static struct nf_log_buf emergency, *emergency_ptr = &emergency;
 266
 267 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
 268 {
 269         va_list args;
 270         int len;
 271
 272         if (likely(m->count < S_SIZE)) {
 273                 va_start(args, f);
 274                 len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
 275                 va_end(args);
 276                 if (likely(m->count + len < S_SIZE)) {
 277                         m->count += len;
 278                         return 0;
 279                 }
 280         }
 281         m->count = S_SIZE;
 282         printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
 283         return -1;
 284 }
 285 EXPORT_SYMBOL_GPL(nf_log_buf_add);
 286
 287 struct nf_log_buf *nf_log_buf_open(void)
 288 {
 289         struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
 290
 291         if (unlikely(!m)) {
 292                 local_bh_disable();
 293                 do {
 294                         m = xchg(&emergency_ptr, NULL);
 295                 } while (!m);
 296         }
 297         m->count = 0;
 298         return m;
 299 }
 300 EXPORT_SYMBOL_GPL(nf_log_buf_open);
 301
 302 void nf_log_buf_close(struct nf_log_buf *m)
 303 {
 304         m->buf[m->count] = 0;
 305         printk("%s\n", m->buf);
 306
 307         if (likely(m != &emergency))
 308                 kfree(m);
 309         else {
 310                 emergency_ptr = m;
 311                 local_bh_enable();
 312         }
 313 }
 314 EXPORT_SYMBOL_GPL(nf_log_buf_close);
 315
 316 #ifdef CONFIG_PROC_FS
 317 static void *seq_start(struct seq_file *seq, loff_t *pos)
 318 {
 319         struct net *net = seq_file_net(seq);
 320
 321         mutex_lock(&nf_log_mutex);
 322
 323         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 324                 return NULL;
 325
 326         return pos;
 327 }
 328
 329 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 330 {
 331         struct net *net = seq_file_net(s);
 332
 333         (*pos)++;
 334
 335         if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
 336                 return NULL;
 337
 338         return pos;
 339 }
 340
 341 static void seq_stop(struct seq_file *s, void *v)
 342 {
 343         mutex_unlock(&nf_log_mutex);
 344 }
 345
 346 static int seq_show(struct seq_file *s, void *v)
 347 {
 348         loff_t *pos = v;
 349         const struct nf_logger *logger;
 350         int i;
 351         struct net *net = seq_file_net(s);
 352
 353         logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
 354
 355         if (!logger)
 356                 seq_printf(s, "%2lld NONE (", *pos);
 357         else
 358                 seq_printf(s, "%2lld %s (", *pos, logger->name);
 359
 360         if (seq_has_overflowed(s))
 361                 return -ENOSPC;
 362
 363         for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
 364                 if (loggers[*pos][i] == NULL)
 365                         continue;
 366
 367                 logger = nft_log_dereference(loggers[*pos][i]);
 368                 seq_puts(s, logger->name);
 369                 if (i == 0 && loggers[*pos][i + 1] != NULL)
 370                         seq_puts(s, ",");
 371
 372                 if (seq_has_overflowed(s))
 373                         return -ENOSPC;
 374         }
 375
 376         seq_puts(s, ")\n");
 377
 378         if (seq_has_overflowed(s))
 379                 return -ENOSPC;
 380         return 0;
 381 }
 382
 383 static const struct seq_operations nflog_seq_ops = {
 384         .start  = seq_start,
 385         .next   = seq_next,
 386         .stop   = seq_stop,
 387         .show   = seq_show,
 388 };
 389 #endif /* PROC_FS */
 390
 391 #ifdef CONFIG_SYSCTL
 392 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 393 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 394 static struct ctl_table_header *nf_log_sysctl_fhdr;
 395
 396 static struct ctl_table nf_log_sysctl_ftable[] = {
 397         {
 398                 .procname       = "nf_log_all_netns",
 399                 .data           = &sysctl_nf_log_all_netns,
 400                 .maxlen         = sizeof(sysctl_nf_log_all_netns),
 401                 .mode           = 0644,
 402                 .proc_handler   = proc_dointvec,
 403         },
 404         { }
 405 };
 406
 407 static int nf_log_proc_dostring(struct ctl_table *table, int write,
 408                          void *buffer, size_t *lenp, loff_t *ppos)
 409 {
 410         const struct nf_logger *logger;
 411         char buf[NFLOGGER_NAME_LEN];
 412         int r = 0;
 413         int tindex = (unsigned long)table->extra1;
 414         struct net *net = table->extra2;
 415
 416         if (write) {
 417                 struct ctl_table tmp = *table;
 418
 419                 /* proc_dostring() can append to existing strings, so we need to
 420                  * initialize it as an empty string.
 421                  */
 422                 buf[0] = '\0';
 423                 tmp.data = buf;
 424                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 425                 if (r)
 426                         return r;
 427
 428                 if (!strcmp(buf, "NONE")) {
 429                         nf_log_unbind_pf(net, tindex);
 430                         return 0;
 431                 }
 432                 mutex_lock(&nf_log_mutex);
 433                 logger = __find_logger(tindex, buf);
 434                 if (logger == NULL) {
 435                         mutex_unlock(&nf_log_mutex);
 436                         return -ENOENT;
 437                 }
 438                 rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
 439                 mutex_unlock(&nf_log_mutex);
 440         } else {
 441                 struct ctl_table tmp = *table;
 442
 443                 tmp.data = buf;
 444                 mutex_lock(&nf_log_mutex);
 445                 logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
 446                 if (!logger)
 447                         strscpy(buf, "NONE", sizeof(buf));
 448                 else
 449                         strscpy(buf, logger->name, sizeof(buf));
 450                 mutex_unlock(&nf_log_mutex);
 451                 r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 452         }
 453
 454         return r;
 455 }
 456
 457 static int netfilter_log_sysctl_init(struct net *net)
 458 {
 459         int i;
 460         struct ctl_table *table;
 461
 462         table = nf_log_sysctl_table;
 463         if (!net_eq(net, &init_net)) {
 464                 table = kmemdup(nf_log_sysctl_table,
 465                                  sizeof(nf_log_sysctl_table),
 466                                  GFP_KERNEL);
 467                 if (!table)
 468                         goto err_alloc;
 469         } else {
 470                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 471                         snprintf(nf_log_sysctl_fnames[i],
 472                                  3, "%d", i);
 473                         nf_log_sysctl_table[i].procname =
 474                                 nf_log_sysctl_fnames[i];
 475                         nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
 476                         nf_log_sysctl_table[i].mode = 0644;
 477                         nf_log_sysctl_table[i].proc_handler =
 478                                 nf_log_proc_dostring;
 479                         nf_log_sysctl_table[i].extra1 =
 480                                 (void *)(unsigned long) i;
 481                 }
 482                 nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
 483                                                          nf_log_sysctl_ftable);
 484                 if (!nf_log_sysctl_fhdr)
 485                         goto err_freg;
 486         }
 487
 488         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 489                 table[i].extra2 = net;
 490
 491         net->nf.nf_log_dir_header = register_net_sysctl_sz(net,
 492                                                            "net/netfilter/nf_log",
 493                                                            table,
 494                                                            ARRAY_SIZE(nf_log_sysctl_table));
 495         if (!net->nf.nf_log_dir_header)
 496                 goto err_reg;
 497
 498         return 0;
 499
 500 err_reg:
 501         if (!net_eq(net, &init_net))
 502                 kfree(table);
 503         else
 504                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 505 err_freg:
 506 err_alloc:
 507         return -ENOMEM;
 508 }
 509
 510 static void netfilter_log_sysctl_exit(struct net *net)
 511 {
 512         struct ctl_table *table;
 513
 514         table = net->nf.nf_log_dir_header->ctl_table_arg;
 515         unregister_net_sysctl_table(net->nf.nf_log_dir_header);
 516         if (!net_eq(net, &init_net))
 517                 kfree(table);
 518         else
 519                 unregister_net_sysctl_table(nf_log_sysctl_fhdr);
 520 }
 521 #else
 522 static int netfilter_log_sysctl_init(struct net *net)
 523 {
 524         return 0;
 525 }
 526
 527 static void netfilter_log_sysctl_exit(struct net *net)
 528 {
 529 }
 530 #endif /* CONFIG_SYSCTL */
 531
 532 static int __net_init nf_log_net_init(struct net *net)
 533 {
 534         int ret = -ENOMEM;
 535
 536 #ifdef CONFIG_PROC_FS
 537         if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
 538                         &nflog_seq_ops, sizeof(struct seq_net_private)))
 539                 return ret;
 540 #endif
 541         ret = netfilter_log_sysctl_init(net);
 542         if (ret < 0)
 543                 goto out_sysctl;
 544
 545         return 0;
 546
 547 out_sysctl:
 548 #ifdef CONFIG_PROC_FS
 549         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 550 #endif
 551         return ret;
 552 }
 553
 554 static void __net_exit nf_log_net_exit(struct net *net)
 555 {
 556         netfilter_log_sysctl_exit(net);
 557 #ifdef CONFIG_PROC_FS
 558         remove_proc_entry("nf_log", net->nf.proc_netfilter);
 559 #endif
 560 }
 561
 562 static struct pernet_operations nf_log_net_ops = {
 563         .init = nf_log_net_init,
 564         .exit = nf_log_net_exit,
 565 };
 566
 567 int __init netfilter_log_init(void)
 568 {
 569         return register_pernet_subsys(&nf_log_net_ops);
 570 }