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 <stdio.h>
  11 #include <string.h>
  12 #include <stdlib.h>
  13 #include <getopt.h>
  14 #include <netdb.h>
  15 #include <ctype.h>
  16
  17 #include <netinet/in.h>
  18 #include <xtables.h>
  19
  20 #include <linux/netfilter/xt_sctp.h>
  21
  22 #if 0
  23 #define DEBUGP(format, first...) printf(format, ##first)
  24 #define static
  25 #else
  26 #define DEBUGP(format, fist...)
  27 #endif
  28
  29 static void
  30 print_chunk(u_int32_t chunknum, int numeric);
  31
  32 static void sctp_init(struct xt_entry_match *m)
  33 {
  34         int i;
  35         struct xt_sctp_info *einfo = (struct xt_sctp_info *)m->data;
  36
  37         memset(einfo, 0, sizeof(struct xt_sctp_info));
  38
  39         for (i = 0; i < XT_NUM_SCTP_FLAGS; i++) {
  40                 einfo->flag_info[i].chunktype = -1;
  41         }
  42 }
  43
  44 static void sctp_help(void)
  45 {
  46         printf(
  47 "sctp match options\n"
  48 "[!] --source-port port[:port]                          match source port(s)\n"
  49 " --sport ...\n"
  50 "[!] --destination-port port[:port]                     match destination port(s)\n"
  51 " --dport ...\n"
  52 "[!] --chunk-types (all|any|none) (chunktype[:flags])+  match if all, any or none of\n"
  53 "                                                       chunktypes are present\n"
  54 "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");
  55 }
  56
  57 static const struct option sctp_opts[] = {
  58         { .name = "source-port", .has_arg = 1, .val = '1' },
  59         { .name = "sport", .has_arg = 1, .val = '1' },
  60         { .name = "destination-port", .has_arg = 1, .val = '2' },
  61         { .name = "dport", .has_arg = 1, .val = '2' },
  62         { .name = "chunk-types", .has_arg = 1, .val = '3' },
  63         { .name = NULL }
  64 };
  65
  66 static void
  67 parse_sctp_ports(const char *portstring,
  68                  u_int16_t *ports)
  69 {
  70         char *buffer;
  71         char *cp;
  72
  73         buffer = strdup(portstring);
  74         DEBUGP("%s\n", portstring);
  75         if ((cp = strchr(buffer, ':')) == NULL) {
  76                 ports[0] = ports[1] = xtables_parse_port(buffer, "sctp");
  77         }
  78         else {
  79                 *cp = '\0';
  80                 cp++;
  81
  82                 ports[0] = buffer[0] ? xtables_parse_port(buffer, "sctp") : 0;
  83                 ports[1] = cp[0] ? xtables_parse_port(cp, "sctp") : 0xFFFF;
  84
  85                 if (ports[0] > ports[1])
  86                         xtables_error(PARAMETER_PROBLEM,
  87                                    "invalid portrange (min > max)");
  88         }
  89         free(buffer);
  90 }
  91
  92 struct sctp_chunk_names {
  93         const char *name;
  94         unsigned int chunk_type;
  95         const char *valid_flags;
  96 };
  97
  98 /*'ALL' and 'NONE' will be treated specially. */
  99 static const struct sctp_chunk_names sctp_chunk_names[]
 100 = { { .name = "DATA",           .chunk_type = 0,   .valid_flags = "----IUBE"},
 101     { .name = "INIT",           .chunk_type = 1,   .valid_flags = "--------"},
 102     { .name = "INIT_ACK",       .chunk_type = 2,   .valid_flags = "--------"},
 103     { .name = "SACK",           .chunk_type = 3,   .valid_flags = "--------"},
 104     { .name = "HEARTBEAT",      .chunk_type = 4,   .valid_flags = "--------"},
 105     { .name = "HEARTBEAT_ACK",  .chunk_type = 5,   .valid_flags = "--------"},
 106     { .name = "ABORT",          .chunk_type = 6,   .valid_flags = "-------T"},
 107     { .name = "SHUTDOWN",       .chunk_type = 7,   .valid_flags = "--------"},
 108     { .name = "SHUTDOWN_ACK",   .chunk_type = 8,   .valid_flags = "--------"},
 109     { .name = "ERROR",          .chunk_type = 9,   .valid_flags = "--------"},
 110     { .name = "COOKIE_ECHO",    .chunk_type = 10,  .valid_flags = "--------"},
 111     { .name = "COOKIE_ACK",     .chunk_type = 11,  .valid_flags = "--------"},
 112     { .name = "ECN_ECNE",       .chunk_type = 12,  .valid_flags = "--------"},
 113     { .name = "ECN_CWR",        .chunk_type = 13,  .valid_flags = "--------"},
 114     { .name = "SHUTDOWN_COMPLETE", .chunk_type = 14,  .valid_flags = "-------T"},
 115     { .name = "ASCONF",         .chunk_type = 193,  .valid_flags = "--------"},
 116     { .name = "ASCONF_ACK",     .chunk_type = 128,  .valid_flags = "--------"},
 117     { .name = "FORWARD_TSN",    .chunk_type = 192,  .valid_flags = "--------"},
 118 };
 119
 120 static void
 121 save_chunk_flag_info(struct xt_sctp_flag_info *flag_info,
 122                      int *flag_count,
 123                      int chunktype,
 124                      int bit,
 125                      int set)
 126 {
 127         int i;
 128
 129         for (i = 0; i < *flag_count; i++) {
 130                 if (flag_info[i].chunktype == chunktype) {
 131                         DEBUGP("Previous match found\n");
 132                         flag_info[i].chunktype = chunktype;
 133                         flag_info[i].flag_mask |= (1 << bit);
 134                         if (set) {
 135                                 flag_info[i].flag |= (1 << bit);
 136                         }
 137
 138                         return;
 139                 }
 140         }
 141
 142         if (*flag_count == XT_NUM_SCTP_FLAGS) {
 143                 xtables_error (PARAMETER_PROBLEM,
 144                         "Number of chunk types with flags exceeds currently allowed limit."
 145                         "Increasing this limit involves changing IPT_NUM_SCTP_FLAGS and"
 146                         "recompiling both the kernel space and user space modules\n");
 147         }
 148
 149         flag_info[*flag_count].chunktype = chunktype;
 150         flag_info[*flag_count].flag_mask |= (1 << bit);
 151         if (set) {
 152                 flag_info[*flag_count].flag |= (1 << bit);
 153         }
 154         (*flag_count)++;
 155 }
 156
 157 static void
 158 parse_sctp_chunk(struct xt_sctp_info *einfo,
 159                  const char *chunks)
 160 {
 161         char *ptr;
 162         char *buffer;
 163         unsigned int i, j;
 164         int found = 0;
 165         char *chunk_flags;
 166
 167         buffer = strdup(chunks);
 168         DEBUGP("Buffer: %s\n", buffer);
 169
 170         SCTP_CHUNKMAP_RESET(einfo->chunkmap);
 171
 172         if (!strcasecmp(buffer, "ALL")) {
 173                 SCTP_CHUNKMAP_SET_ALL(einfo->chunkmap);
 174                 goto out;
 175         }
 176
 177         if (!strcasecmp(buffer, "NONE")) {
 178                 SCTP_CHUNKMAP_RESET(einfo->chunkmap);
 179                 goto out;
 180         }
 181
 182         for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ",")) {
 183                 found = 0;
 184                 DEBUGP("Next Chunk type %s\n", ptr);
 185
 186                 if ((chunk_flags = strchr(ptr, ':')) != NULL) {
 187                         *chunk_flags++ = 0;
 188                 }
 189
 190                 for (i = 0; i < ARRAY_SIZE(sctp_chunk_names); ++i)
 191                         if (strcasecmp(sctp_chunk_names[i].name, ptr) == 0) {
 192                                 DEBUGP("Chunk num %d\n", sctp_chunk_names[i].chunk_type);
 193                                 SCTP_CHUNKMAP_SET(einfo->chunkmap,
 194                                         sctp_chunk_names[i].chunk_type);
 195                                 found = 1;
 196                                 break;
 197                         }
 198                 if (!found)
 199                         xtables_error(PARAMETER_PROBLEM,
 200                                    "Unknown sctp chunk `%s'", ptr);
 201
 202                 if (chunk_flags) {
 203                         DEBUGP("Chunk flags %s\n", chunk_flags);
 204                         for (j = 0; j < strlen(chunk_flags); j++) {
 205                                 char *p;
 206                                 int bit;
 207
 208                                 if ((p = strchr(sctp_chunk_names[i].valid_flags,
 209                                                 toupper(chunk_flags[j]))) != NULL) {
 210                                         bit = p - sctp_chunk_names[i].valid_flags;
 211                                         bit = 7 - bit;
 212
 213                                         save_chunk_flag_info(einfo->flag_info,
 214                                                 &(einfo->flag_count), i, bit,
 215                                                 isupper(chunk_flags[j]));
 216                                 } else {
 217                                         xtables_error(PARAMETER_PROBLEM,
 218                                                 "Invalid flags for chunk type %d\n", i);
 219                                 }
 220                         }
 221                 }
 222         }
 223 out:
 224         free(buffer);
 225 }
 226
 227 static void
 228 parse_sctp_chunks(struct xt_sctp_info *einfo,
 229                   const char *match_type,
 230                   const char *chunks)
 231 {
 232         DEBUGP("Match type: %s Chunks: %s\n", match_type, chunks);
 233         if (!strcasecmp(match_type, "ANY")) {
 234                 einfo->chunk_match_type = SCTP_CHUNK_MATCH_ANY;
 235         } else  if (!strcasecmp(match_type, "ALL")) {
 236                 einfo->chunk_match_type = SCTP_CHUNK_MATCH_ALL;
 237         } else  if (!strcasecmp(match_type, "ONLY")) {
 238                 einfo->chunk_match_type = SCTP_CHUNK_MATCH_ONLY;
 239         } else {
 240                 xtables_error (PARAMETER_PROBLEM,
 241                         "Match type has to be one of \"ALL\", \"ANY\" or \"ONLY\"");
 242         }
 243
 244         SCTP_CHUNKMAP_RESET(einfo->chunkmap);
 245         parse_sctp_chunk(einfo, chunks);
 246 }
 247
 248 static int
 249 sctp_parse(int c, char **argv, int invert, unsigned int *flags,
 250            const void *entry, struct xt_entry_match **match)
 251 {
 252         struct xt_sctp_info *einfo
 253                 = (struct xt_sctp_info *)(*match)->data;
 254
 255         switch (c) {
 256         case '1':
 257                 if (*flags & XT_SCTP_SRC_PORTS)
 258                         xtables_error(PARAMETER_PROBLEM,
 259                                    "Only one `--source-port' allowed");
 260                 einfo->flags |= XT_SCTP_SRC_PORTS;
 261                 xtables_check_inverse(optarg, &invert, &optind, 0, argv);
 262                 parse_sctp_ports(optarg, einfo->spts);
 263                 if (invert)
 264                         einfo->invflags |= XT_SCTP_SRC_PORTS;
 265                 *flags |= XT_SCTP_SRC_PORTS;
 266                 break;
 267
 268         case '2':
 269                 if (*flags & XT_SCTP_DEST_PORTS)
 270                         xtables_error(PARAMETER_PROBLEM,
 271                                    "Only one `--destination-port' allowed");
 272                 einfo->flags |= XT_SCTP_DEST_PORTS;
 273                 xtables_check_inverse(optarg, &invert, &optind, 0, argv);
 274                 parse_sctp_ports(optarg, einfo->dpts);
 275                 if (invert)
 276                         einfo->invflags |= XT_SCTP_DEST_PORTS;
 277                 *flags |= XT_SCTP_DEST_PORTS;
 278                 break;
 279
 280         case '3':
 281                 if (*flags & XT_SCTP_CHUNK_TYPES)
 282                         xtables_error(PARAMETER_PROBLEM,
 283                                    "Only one `--chunk-types' allowed");
 284                 xtables_check_inverse(optarg, &invert, &optind, 0, argv);
 285
 286                 if (!argv[optind]
 287                     || argv[optind][0] == '-' || argv[optind][0] == '!')
 288                         xtables_error(PARAMETER_PROBLEM,
 289                                    "--chunk-types requires two args");
 290
 291                 einfo->flags |= XT_SCTP_CHUNK_TYPES;
 292                 parse_sctp_chunks(einfo, optarg, argv[optind]);
 293                 if (invert)
 294                         einfo->invflags |= XT_SCTP_CHUNK_TYPES;
 295                 optind++;
 296                 *flags |= XT_SCTP_CHUNK_TYPES;
 297                 break;
 298
 299         default:
 300                 return 0;
 301         }
 302         return 1;
 303 }
 304
 305 static char *
 306 port_to_service(int port)
 307 {
 308         struct servent *service;
 309
 310         if ((service = getservbyport(htons(port), "sctp")))
 311                 return service->s_name;
 312
 313         return NULL;
 314 }
 315
 316 static void
 317 print_port(u_int16_t port, int numeric)
 318 {
 319         char *service;
 320
 321         if (numeric || (service = port_to_service(port)) == NULL)
 322                 printf("%u", port);
 323         else
 324                 printf("%s", service);
 325 }
 326
 327 static void
 328 print_ports(const char *name, u_int16_t min, u_int16_t max,
 329             int invert, int numeric)
 330 {
 331         const char *inv = invert ? "!" : "";
 332
 333         if (min != 0 || max != 0xFFFF || invert) {
 334                 printf("%s", name);
 335                 if (min == max) {
 336                         printf(":%s", inv);
 337                         print_port(min, numeric);
 338                 } else {
 339                         printf("s:%s", inv);
 340                         print_port(min, numeric);
 341                         printf(":");
 342                         print_port(max, numeric);
 343                 }
 344                 printf(" ");
 345         }
 346 }
 347
 348 static void
 349 print_chunk_flags(u_int32_t chunknum, u_int8_t chunk_flags, u_int8_t chunk_flags_mask)
 350 {
 351         int i;
 352
 353         DEBUGP("type: %d\tflags: %x\tflag mask: %x\n", chunknum, chunk_flags,
 354                         chunk_flags_mask);
 355
 356         if (chunk_flags_mask) {
 357                 printf(":");
 358         }
 359
 360         for (i = 7; i >= 0; i--) {
 361                 if (chunk_flags_mask & (1 << i)) {
 362                         if (chunk_flags & (1 << i)) {
 363                                 printf("%c", sctp_chunk_names[chunknum].valid_flags[7-i]);
 364                         } else {
 365                                 printf("%c", tolower(sctp_chunk_names[chunknum].valid_flags[7-i]));
 366                         }
 367                 }
 368         }
 369 }
 370
 371 static void
 372 print_chunk(u_int32_t chunknum, int numeric)
 373 {
 374         if (numeric) {
 375                 printf("0x%04X", chunknum);
 376         }
 377         else {
 378                 int i;
 379
 380                 for (i = 0; i < ARRAY_SIZE(sctp_chunk_names); ++i)
 381                         if (sctp_chunk_names[i].chunk_type == chunknum)
 382                                 printf("%s", sctp_chunk_names[chunknum].name);
 383         }
 384 }
 385
 386 static void
 387 print_chunks(const struct xt_sctp_info *einfo, int numeric)
 388 {
 389         u_int32_t chunk_match_type = einfo->chunk_match_type;
 390         const struct xt_sctp_flag_info *flag_info = einfo->flag_info;
 391         int flag_count = einfo->flag_count;
 392         int i, j;
 393         int flag;
 394
 395         switch (chunk_match_type) {
 396                 case SCTP_CHUNK_MATCH_ANY:      printf("any "); break;
 397                 case SCTP_CHUNK_MATCH_ALL:      printf("all "); break;
 398                 case SCTP_CHUNK_MATCH_ONLY:     printf("only "); break;
 399                 default:        printf("Never reach herer\n"); break;
 400         }
 401
 402         if (SCTP_CHUNKMAP_IS_CLEAR(einfo->chunkmap)) {
 403                 printf("NONE ");
 404                 goto out;
 405         }
 406
 407         if (SCTP_CHUNKMAP_IS_ALL_SET(einfo->chunkmap)) {
 408                 printf("ALL ");
 409                 goto out;
 410         }
 411
 412         flag = 0;
 413         for (i = 0; i < 256; i++) {
 414                 if (SCTP_CHUNKMAP_IS_SET(einfo->chunkmap, i)) {
 415                         if (flag)
 416                                 printf(",");
 417                         flag = 1;
 418                         print_chunk(i, numeric);
 419                         for (j = 0; j < flag_count; j++) {
 420                                 if (flag_info[j].chunktype == i) {
 421                                         print_chunk_flags(i, flag_info[j].flag,
 422                                                 flag_info[j].flag_mask);
 423                                 }
 424                         }
 425                 }
 426         }
 427
 428         if (flag)
 429                 printf(" ");
 430 out:
 431         return;
 432 }
 433
 434 static void
 435 sctp_print(const void *ip, const struct xt_entry_match *match, int numeric)
 436 {
 437         const struct xt_sctp_info *einfo =
 438                 (const struct xt_sctp_info *)match->data;
 439
 440         printf("sctp ");
 441
 442         if (einfo->flags & XT_SCTP_SRC_PORTS) {
 443                 print_ports("spt", einfo->spts[0], einfo->spts[1],
 444                         einfo->invflags & XT_SCTP_SRC_PORTS,
 445                         numeric);
 446         }
 447
 448         if (einfo->flags & XT_SCTP_DEST_PORTS) {
 449                 print_ports("dpt", einfo->dpts[0], einfo->dpts[1],
 450                         einfo->invflags & XT_SCTP_DEST_PORTS,
 451                         numeric);
 452         }
 453
 454         if (einfo->flags & XT_SCTP_CHUNK_TYPES) {
 455                 /* FIXME: print_chunks() is used in save() where the printing of '!'
 456                 s taken care of, so we need to do that here as well */
 457                 if (einfo->invflags & XT_SCTP_CHUNK_TYPES) {
 458                         printf("! ");
 459                 }
 460                 print_chunks(einfo, numeric);
 461         }
 462 }
 463
 464 static void sctp_save(const void *ip, const struct xt_entry_match *match)
 465 {
 466         const struct xt_sctp_info *einfo =
 467                 (const struct xt_sctp_info *)match->data;
 468
 469         if (einfo->flags & XT_SCTP_SRC_PORTS) {
 470                 if (einfo->invflags & XT_SCTP_SRC_PORTS)
 471                         printf("! ");
 472                 if (einfo->spts[0] != einfo->spts[1])
 473                         printf("--sport %u:%u ",
 474                                einfo->spts[0], einfo->spts[1]);
 475                 else
 476                         printf("--sport %u ", einfo->spts[0]);
 477         }
 478
 479         if (einfo->flags & XT_SCTP_DEST_PORTS) {
 480                 if (einfo->invflags & XT_SCTP_DEST_PORTS)
 481                         printf("! ");
 482                 if (einfo->dpts[0] != einfo->dpts[1])
 483                         printf("--dport %u:%u ",
 484                                einfo->dpts[0], einfo->dpts[1]);
 485                 else
 486                         printf("--dport %u ", einfo->dpts[0]);
 487         }
 488
 489         if (einfo->flags & XT_SCTP_CHUNK_TYPES) {
 490                 if (einfo->invflags & XT_SCTP_CHUNK_TYPES)
 491                         printf("! ");
 492                 printf("--chunk-types ");
 493
 494                 print_chunks(einfo, 0);
 495         }
 496 }
 497
 498 static struct xtables_match sctp_match = {
 499         .name           = "sctp",
 500         .family         = NFPROTO_UNSPEC,
 501         .version        = XTABLES_VERSION,
 502         .size           = XT_ALIGN(sizeof(struct xt_sctp_info)),
 503         .userspacesize  = XT_ALIGN(sizeof(struct xt_sctp_info)),
 504         .help           = sctp_help,
 505         .init           = sctp_init,
 506         .parse          = sctp_parse,
 507         .print          = sctp_print,
 508         .save           = sctp_save,
 509         .extra_opts     = sctp_opts,
 510 };
 511
 512 void _init(void)
 513 {
 514         xtables_register_match(&sctp_match);
 515 }