extensions/libxt_sctp.c

   1 /* Shared library add-on to iptables for SCTP matching
   2  *
   3  * (C) 2003 by Harald Welte <laforge@gnumonks.org>
   4  *
   5  * This program is distributed under the terms of GNU GPL v2, 1991
   6  *
   7  * libipt_ecn.c borrowed heavily from libipt_dscp.c
   8  *
   9  */
  10 #include <stdbool.h>
  11 #include <stdio.h>
  12 #include <string.h>
  13 #include <stdlib.h>
  14 #include <getopt.h>
  15 #include <netdb.h>
  16 #include <ctype.h>
  17
  18 #include <netinet/in.h>
  19 #include <xtables.h>
  20
  21 #include <linux/netfilter/xt_sctp.h>
  22
  23 #if 0
  24 #define DEBUGP(format, first...) printf(format, ##first)
  25 #define static
  26 #else
  27 #define DEBUGP(format, fist...)
  28 #endif
  29
  30 static void
  31 print_chunk(uint32_t chunknum, int numeric);
  32
  33 static void sctp_init(struct xt_entry_match *m)
  34 {
  35         int i;
  36         struct xt_sctp_info *einfo = (struct xt_sctp_info *)m->data;
  37
  38         for (i = 0; i < XT_NUM_SCTP_FLAGS; i++) {
  39                 einfo->flag_info[i].chunktype = -1;
  40         }
  41 }
  42
  43 static void sctp_help(void)
  44 {
  45         printf(
  46 "sctp match options\n"
  47 "[!] --source-port port[:port]                          match source port(s)\n"
  48 " --sport ...\n"
  49 "[!] --destination-port port[:port]                     match destination port(s)\n"
  50 " --dport ...\n"
  51 "[!] --chunk-types (all|any|none) (chunktype[:flags])+  match if all, any or none of\n"
  52 "                                                       chunktypes are present\n"
  53 "chunktypes - DATA INIT INIT_ACK SACK HEARTBEAT HEARTBEAT_ACK ABORT SHUTDOWN SHUTDOWN_ACK ERROR COOKIE_ECHO COOKIE_ACK ECN_ECNE ECN_CWR SHUTDOWN_COMPLETE ASCONF ASCONF_ACK FORWARD_TSN ALL NONE\n");
  54 }
  55
  56 static const struct option sctp_opts[] = {
  57         {.name = "source-port",      .has_arg = true, .val = '1'},
  58         {.name = "sport",            .has_arg = true, .val = '1'},
  59         {.name = "destination-port", .has_arg = true, .val = '2'},
  60         {.name = "dport",            .has_arg = true, .val = '2'},
  61         {.name = "chunk-types",      .has_arg = true, .val = '3'},
  62         XT_GETOPT_TABLEEND,
  63 };
  64
  65 static void
  66 parse_sctp_ports(const char *portstring,
  67                  uint16_t *ports)
  68 {
  69         char *buffer;
  70         char *cp;
  71
  72         buffer = strdup(portstring);
  73         DEBUGP("%s\n", portstring);
  74         if ((cp = strchr(buffer, ':')) == NULL) {
  75                 ports[0] = ports[1] = xtables_parse_port(buffer, "sctp");
  76         }
  77         else {
  78                 *cp = '\0';
  79                 cp++;
  80
  81                 ports[0] = buffer[0] ? xtables_parse_port(buffer, "sctp") : 0;
  82                 ports[1] = cp[0] ? xtables_parse_port(cp, "sctp") : 0xFFFF;
  83
  84                 if (ports[0] > ports[1])
  85                         xtables_error(PARAMETER_PROBLEM,
  86                                    "invalid portrange (min > max)");
  87         }
  88         free(buffer);
  89 }
  90
  91 struct sctp_chunk_names {
  92         const char *name;
  93         unsigned int chunk_type;
  94         const char *valid_flags;
  95 };
  96
  97 /*'ALL' and 'NONE' will be treated specially. */
  98 static const struct sctp_chunk_names sctp_chunk_names[]
  99 = { { .name = "DATA",           .chunk_type = 0,   .valid_flags = "----IUBE"},
 100     { .name = "INIT",           .chunk_type = 1,   .valid_flags = "--------"},
 101     { .name = "INIT_ACK",       .chunk_type = 2,   .valid_flags = "--------"},
 102     { .name = "SACK",           .chunk_type = 3,   .valid_flags = "--------"},
 103     { .name = "HEARTBEAT",      .chunk_type = 4,   .valid_flags = "--------"},
 104     { .name = "HEARTBEAT_ACK",  .chunk_type = 5,   .valid_flags = "--------"},
 105     { .name = "ABORT",          .chunk_type = 6,   .valid_flags = "-------T"},
 106     { .name = "SHUTDOWN",       .chunk_type = 7,   .valid_flags = "--------"},
 107     { .name = "SHUTDOWN_ACK",   .chunk_type = 8,   .valid_flags = "--------"},
 108     { .name = "ERROR",          .chunk_type = 9,   .valid_flags = "--------"},
 109     { .name = "COOKIE_ECHO",    .chunk_type = 10,  .valid_flags = "--------"},
 110     { .name = "COOKIE_ACK",     .chunk_type = 11,  .valid_flags = "--------"},
 111     { .name = "ECN_ECNE",       .chunk_type = 12,  .valid_flags = "--------"},
 112     { .name = "ECN_CWR",        .chunk_type = 13,  .valid_flags = "--------"},
 113     { .name = "SHUTDOWN_COMPLETE", .chunk_type = 14,  .valid_flags = "-------T"},
 114     { .name = "ASCONF",         .chunk_type = 193,  .valid_flags = "--------"},
 115     { .name = "ASCONF_ACK",     .chunk_type = 128,  .valid_flags = "--------"},
 116     { .name = "FORWARD_TSN",    .chunk_type = 192,  .valid_flags = "--------"},
 117 };
 118
 119 static void
 120 save_chunk_flag_info(struct xt_sctp_flag_info *flag_info,
 121                      int *flag_count,
 122                      int chunktype,
 123                      int bit,
 124                      int set)
 125 {
 126         int i;
 127
 128         for (i = 0; i < *flag_count; i++) {
 129                 if (flag_info[i].chunktype == chunktype) {
 130                         DEBUGP("Previous match found\n");
 131                         flag_info[i].chunktype = chunktype;
 132                         flag_info[i].flag_mask |= (1 << bit);
 133                         if (set) {
 134                                 flag_info[i].flag |= (1 << bit);
 135                         }
 136
 137                         return;
 138                 }
 139         }
 140
 141         if (*flag_count == XT_NUM_SCTP_FLAGS) {
 142                 xtables_error (PARAMETER_PROBLEM,
 143                         "Number of chunk types with flags exceeds currently allowed limit."
 144                         "Increasing this limit involves changing IPT_NUM_SCTP_FLAGS and"
 145                         "recompiling both the kernel space and user space modules\n");
 146         }
 147
 148         flag_info[*flag_count].chunktype = chunktype;
 149         flag_info[*flag_count].flag_mask |= (1 << bit);
 150         if (set) {
 151                 flag_info[*flag_count].flag |= (1 << bit);
 152         }
 153         (*flag_count)++;
 154 }
 155
 156 static void
 157 parse_sctp_chunk(struct xt_sctp_info *einfo,
 158                  const char *chunks)
 159 {
 160         char *ptr;
 161         char *buffer;
 162         unsigned int i, j;
 163         int found = 0;
 164         char *chunk_flags;
 165
 166         buffer = strdup(chunks);
 167         DEBUGP("Buffer: %s\n", buffer);
 168
 169         SCTP_CHUNKMAP_RESET(einfo->chunkmap);
 170
 171         if (!strcasecmp(buffer, "ALL")) {
 172                 SCTP_CHUNKMAP_SET_ALL(einfo->chunkmap);
 173                 goto out;
 174         }
 175
 176         if (!strcasecmp(buffer, "NONE")) {
 177                 SCTP_CHUNKMAP_RESET(einfo->chunkmap);
 178                 goto out;
 179         }
 180
 181         for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ",")) {
 182                 found = 0;
 183                 DEBUGP("Next Chunk type %s\n", ptr);
 184
 185                 if ((chunk_flags = strchr(ptr, ':')) != NULL) {
 186                         *chunk_flags++ = 0;
 187                 }
 188
 189                 for (i = 0; i < ARRAY_SIZE(sctp_chunk_names); ++i)
 190                         if (strcasecmp(sctp_chunk_names[i].name, ptr) == 0) {
 191                                 DEBUGP("Chunk num %d\n", sctp_chunk_names[i].chunk_type);
 192                                 SCTP_CHUNKMAP_SET(einfo->chunkmap,
 193                                         sctp_chunk_names[i].chunk_type);
 194                                 found = 1;
 195                                 break;
 196                         }
 197                 if (!found)
 198                         xtables_error(PARAMETER_PROBLEM,
 199                                    "Unknown sctp chunk `%s'", ptr);
 200
 201                 if (chunk_flags) {
 202                         DEBUGP("Chunk flags %s\n", chunk_flags);
 203                         for (j = 0; j < strlen(chunk_flags); j++) {
 204                                 char *p;
 205                                 int bit;
 206
 207                                 if ((p = strchr(sctp_chunk_names[i].valid_flags,
 208                                                 toupper(chunk_flags[j]))) != NULL) {
 209                                         bit = p - sctp_chunk_names[i].valid_flags;
 210                                         bit = 7 - bit;
 211
 212                                         save_chunk_flag_info(einfo->flag_info,
 213                                                 &(einfo->flag_count), i, bit,
 214                                                 isupper(chunk_flags[j]));
 215                                 } else {
 216                                         xtables_error(PARAMETER_PROBLEM,
 217                                                 "Invalid flags for chunk type %d\n", i);
 218                                 }
 219                         }
 220                 }
 221         }
 222 out:
 223         free(buffer);
 224 }
 225
 226 static void
 227 parse_sctp_chunks(struct xt_sctp_info *einfo,
 228                   const char *match_type,
 229                   const char *chunks)
 230 {
 231         DEBUGP("Match type: %s Chunks: %s\n", match_type, chunks);
 232         if (!strcasecmp(match_type, "ANY")) {
 233                 einfo->chunk_match_type = SCTP_CHUNK_MATCH_ANY;
 234         } else  if (!strcasecmp(match_type, "ALL")) {
 235                 einfo->chunk_match_type = SCTP_CHUNK_MATCH_ALL;
 236         } else  if (!strcasecmp(match_type, "ONLY")) {
 237                 einfo->chunk_match_type = SCTP_CHUNK_MATCH_ONLY;
 238         } else {
 239                 xtables_error (PARAMETER_PROBLEM,
 240                         "Match type has to be one of \"ALL\", \"ANY\" or \"ONLY\"");
 241         }
 242
 243         SCTP_CHUNKMAP_RESET(einfo->chunkmap);
 244         parse_sctp_chunk(einfo, chunks);
 245 }
 246
 247 static int
 248 sctp_parse(int c, char **argv, int invert, unsigned int *flags,
 249            const void *entry, struct xt_entry_match **match)
 250 {
 251         struct xt_sctp_info *einfo
 252                 = (struct xt_sctp_info *)(*match)->data;
 253
 254         switch (c) {
 255         case '1':
 256                 if (*flags & XT_SCTP_SRC_PORTS)
 257                         xtables_error(PARAMETER_PROBLEM,
 258                                    "Only one `--source-port' allowed");
 259                 einfo->flags |= XT_SCTP_SRC_PORTS;
 260                 parse_sctp_ports(optarg, einfo->spts);
 261                 if (invert)
 262                         einfo->invflags |= XT_SCTP_SRC_PORTS;
 263                 *flags |= XT_SCTP_SRC_PORTS;
 264                 break;
 265
 266         case '2':
 267                 if (*flags & XT_SCTP_DEST_PORTS)
 268                         xtables_error(PARAMETER_PROBLEM,
 269                                    "Only one `--destination-port' allowed");
 270                 einfo->flags |= XT_SCTP_DEST_PORTS;
 271                 parse_sctp_ports(optarg, einfo->dpts);
 272                 if (invert)
 273                         einfo->invflags |= XT_SCTP_DEST_PORTS;
 274                 *flags |= XT_SCTP_DEST_PORTS;
 275                 break;
 276
 277         case '3':
 278                 if (*flags & XT_SCTP_CHUNK_TYPES)
 279                         xtables_error(PARAMETER_PROBLEM,
 280                                    "Only one `--chunk-types' allowed");
 281                 if (!argv[optind]
 282                     || argv[optind][0] == '-' || argv[optind][0] == '!')
 283                         xtables_error(PARAMETER_PROBLEM,
 284                                    "--chunk-types requires two args");
 285
 286                 einfo->flags |= XT_SCTP_CHUNK_TYPES;
 287                 parse_sctp_chunks(einfo, optarg, argv[optind]);
 288                 if (invert)
 289                         einfo->invflags |= XT_SCTP_CHUNK_TYPES;
 290                 optind++;
 291                 *flags |= XT_SCTP_CHUNK_TYPES;
 292                 break;
 293         }
 294         return 1;
 295 }
 296
 297 static const char *
 298 port_to_service(int port)
 299 {
 300         const struct servent *service;
 301
 302         if ((service = getservbyport(htons(port), "sctp")))
 303                 return service->s_name;
 304
 305         return NULL;
 306 }
 307
 308 static void
 309 print_port(uint16_t port, int numeric)
 310 {
 311         const char *service;
 312
 313         if (numeric || (service = port_to_service(port)) == NULL)
 314                 printf("%u", port);
 315         else
 316                 printf("%s", service);
 317 }
 318
 319 static void
 320 print_ports(const char *name, uint16_t min, uint16_t max,
 321             int invert, int numeric)
 322 {
 323         const char *inv = invert ? "!" : "";
 324
 325         if (min != 0 || max != 0xFFFF || invert) {
 326                 printf(" %s", name);
 327                 if (min == max) {
 328                         printf(":%s", inv);
 329                         print_port(min, numeric);
 330                 } else {
 331                         printf("s:%s", inv);
 332                         print_port(min, numeric);
 333                         printf(":");
 334                         print_port(max, numeric);
 335                 }
 336         }
 337 }
 338
 339 static void
 340 print_chunk_flags(uint32_t chunknum, uint8_t chunk_flags, uint8_t chunk_flags_mask)
 341 {
 342         int i;
 343
 344         DEBUGP("type: %d\tflags: %x\tflag mask: %x\n", chunknum, chunk_flags,
 345                         chunk_flags_mask);
 346
 347         if (chunk_flags_mask) {
 348                 printf(":");
 349         }
 350
 351         for (i = 7; i >= 0; i--) {
 352                 if (chunk_flags_mask & (1 << i)) {
 353                         if (chunk_flags & (1 << i)) {
 354                                 printf("%c", sctp_chunk_names[chunknum].valid_flags[7-i]);
 355                         } else {
 356                                 printf("%c", tolower(sctp_chunk_names[chunknum].valid_flags[7-i]));
 357                         }
 358                 }
 359         }
 360 }
 361
 362 static void
 363 print_chunk(uint32_t chunknum, int numeric)
 364 {
 365         if (numeric) {
 366                 printf("0x%04X", chunknum);
 367         }
 368         else {
 369                 int i;
 370
 371                 for (i = 0; i < ARRAY_SIZE(sctp_chunk_names); ++i)
 372                         if (sctp_chunk_names[i].chunk_type == chunknum)
 373                                 printf("%s", sctp_chunk_names[chunknum].name);
 374         }
 375 }
 376
 377 static void
 378 print_chunks(const struct xt_sctp_info *einfo, int numeric)
 379 {
 380         uint32_t chunk_match_type = einfo->chunk_match_type;
 381         const struct xt_sctp_flag_info *flag_info = einfo->flag_info;
 382         int flag_count = einfo->flag_count;
 383         int i, j;
 384         int flag;
 385
 386         switch (chunk_match_type) {
 387                 case SCTP_CHUNK_MATCH_ANY:      printf(" any"); break;
 388                 case SCTP_CHUNK_MATCH_ALL:      printf(" all"); break;
 389                 case SCTP_CHUNK_MATCH_ONLY:     printf(" only"); break;
 390                 default:        printf("Never reach here\n"); break;
 391         }
 392
 393         if (SCTP_CHUNKMAP_IS_CLEAR(einfo->chunkmap)) {
 394                 printf(" NONE");
 395                 goto out;
 396         }
 397
 398         if (SCTP_CHUNKMAP_IS_ALL_SET(einfo->chunkmap)) {
 399                 printf(" ALL");
 400                 goto out;
 401         }
 402
 403         flag = 0;
 404         for (i = 0; i < 256; i++) {
 405                 if (SCTP_CHUNKMAP_IS_SET(einfo->chunkmap, i)) {
 406                         if (flag)
 407                                 printf(",");
 408                         else
 409                                 putchar(' ');
 410                         flag = 1;
 411                         print_chunk(i, numeric);
 412                         for (j = 0; j < flag_count; j++) {
 413                                 if (flag_info[j].chunktype == i) {
 414                                         print_chunk_flags(i, flag_info[j].flag,
 415                                                 flag_info[j].flag_mask);
 416                                 }
 417                         }
 418                 }
 419         }
 420 out:
 421         return;
 422 }
 423
 424 static void
 425 sctp_print(const void *ip, const struct xt_entry_match *match, int numeric)
 426 {
 427         const struct xt_sctp_info *einfo =
 428                 (const struct xt_sctp_info *)match->data;
 429
 430         printf(" sctp");
 431
 432         if (einfo->flags & XT_SCTP_SRC_PORTS) {
 433                 print_ports("spt", einfo->spts[0], einfo->spts[1],
 434                         einfo->invflags & XT_SCTP_SRC_PORTS,
 435                         numeric);
 436         }
 437
 438         if (einfo->flags & XT_SCTP_DEST_PORTS) {
 439                 print_ports("dpt", einfo->dpts[0], einfo->dpts[1],
 440                         einfo->invflags & XT_SCTP_DEST_PORTS,
 441                         numeric);
 442         }
 443
 444         if (einfo->flags & XT_SCTP_CHUNK_TYPES) {
 445                 /* FIXME: print_chunks() is used in save() where the printing of '!'
 446                 s taken care of, so we need to do that here as well */
 447                 if (einfo->invflags & XT_SCTP_CHUNK_TYPES) {
 448                         printf(" !");
 449                 }
 450                 print_chunks(einfo, numeric);
 451         }
 452 }
 453
 454 static void sctp_save(const void *ip, const struct xt_entry_match *match)
 455 {
 456         const struct xt_sctp_info *einfo =
 457                 (const struct xt_sctp_info *)match->data;
 458
 459         if (einfo->flags & XT_SCTP_SRC_PORTS) {
 460                 if (einfo->invflags & XT_SCTP_SRC_PORTS)
 461                         printf(" !");
 462                 if (einfo->spts[0] != einfo->spts[1])
 463                         printf(" --sport %u:%u",
 464                                einfo->spts[0], einfo->spts[1]);
 465                 else
 466                         printf(" --sport %u", einfo->spts[0]);
 467         }
 468
 469         if (einfo->flags & XT_SCTP_DEST_PORTS) {
 470                 if (einfo->invflags & XT_SCTP_DEST_PORTS)
 471                         printf(" !");
 472                 if (einfo->dpts[0] != einfo->dpts[1])
 473                         printf(" --dport %u:%u",
 474                                einfo->dpts[0], einfo->dpts[1]);
 475                 else
 476                         printf(" --dport %u", einfo->dpts[0]);
 477         }
 478
 479         if (einfo->flags & XT_SCTP_CHUNK_TYPES) {
 480                 if (einfo->invflags & XT_SCTP_CHUNK_TYPES)
 481                         printf(" !");
 482                 printf(" --chunk-types");
 483
 484                 print_chunks(einfo, 0);
 485         }
 486 }
 487
 488 static struct xtables_match sctp_match = {
 489         .name           = "sctp",
 490         .family         = NFPROTO_UNSPEC,
 491         .version        = XTABLES_VERSION,
 492         .size           = XT_ALIGN(sizeof(struct xt_sctp_info)),
 493         .userspacesize  = XT_ALIGN(sizeof(struct xt_sctp_info)),
 494         .help           = sctp_help,
 495         .init           = sctp_init,
 496         .parse          = sctp_parse,
 497         .print          = sctp_print,
 498         .save           = sctp_save,
 499         .extra_opts     = sctp_opts,
 500 };
 501
 502 void _init(void)
 503 {
 504         xtables_register_match(&sctp_match);
 505 }