contrib/ldns/tsig.c

   1 /*
   2  * tsig.c
   3  *
   4  * contains the functions needed for TSIG [RFC2845]
   5  *
   6  * (c) 2005-2006 NLnet Labs
   7  * See the file LICENSE for the license
   8  */
   9
  10 #include <ldns/config.h>
  11
  12 #include <ldns/ldns.h>
  13
  14 #include <strings.h>
  15
  16 #ifdef HAVE_SSL
  17 #include <openssl/hmac.h>
  18 #include <openssl/md5.h>
  19 #endif /* HAVE_SSL */
  20
  21 char *
  22 ldns_tsig_algorithm(ldns_tsig_credentials *tc)
  23 {
  24         return tc->algorithm;
  25 }
  26
  27 char *
  28 ldns_tsig_keyname(ldns_tsig_credentials *tc)
  29 {
  30         return tc->keyname;
  31 }
  32
  33 char *
  34 ldns_tsig_keydata(ldns_tsig_credentials *tc)
  35 {
  36         return tc->keydata;
  37 }
  38
  39 char *
  40 ldns_tsig_keyname_clone(ldns_tsig_credentials *tc)
  41 {
  42         return strdup(tc->keyname);
  43 }
  44
  45 char *
  46 ldns_tsig_keydata_clone(ldns_tsig_credentials *tc)
  47 {
  48         return strdup(tc->keydata);
  49 }
  50
  51 /*
  52  *  Makes an exact copy of the wire, but with the tsig rr removed
  53  */
  54 uint8_t *
  55 ldns_tsig_prepare_pkt_wire(uint8_t *wire, size_t wire_len, size_t *result_len)
  56 {
  57         uint8_t *wire2 = NULL;
  58         uint16_t qd_count;
  59         uint16_t an_count;
  60         uint16_t ns_count;
  61         uint16_t ar_count;
  62         ldns_rr *rr;
  63
  64         size_t pos;
  65         uint16_t i;
  66
  67         ldns_status status;
  68
  69         if(wire_len < LDNS_HEADER_SIZE) {
  70                 return NULL;
  71         }
  72         /* fake parse the wire */
  73         qd_count = LDNS_QDCOUNT(wire);
  74         an_count = LDNS_ANCOUNT(wire);
  75         ns_count = LDNS_NSCOUNT(wire);
  76         ar_count = LDNS_ARCOUNT(wire);
  77
  78         if (ar_count > 0) {
  79                 ar_count--;
  80         } else {
  81                 return NULL;
  82         }
  83
  84         pos = LDNS_HEADER_SIZE;
  85
  86         for (i = 0; i < qd_count; i++) {
  87                 status = ldns_wire2rr(&rr, wire, wire_len, &pos, LDNS_SECTION_QUESTION);
  88                 if (status != LDNS_STATUS_OK) {
  89                         return NULL;
  90                 }
  91                 ldns_rr_free(rr);
  92         }
  93
  94         for (i = 0; i < an_count; i++) {
  95                 status = ldns_wire2rr(&rr, wire, wire_len, &pos, LDNS_SECTION_ANSWER);
  96                 if (status != LDNS_STATUS_OK) {
  97                         return NULL;
  98                 }
  99                 ldns_rr_free(rr);
 100         }
 101
 102         for (i = 0; i < ns_count; i++) {
 103                 status = ldns_wire2rr(&rr, wire, wire_len, &pos, LDNS_SECTION_AUTHORITY);
 104                 if (status != LDNS_STATUS_OK) {
 105                         return NULL;
 106                 }
 107                 ldns_rr_free(rr);
 108         }
 109
 110         for (i = 0; i < ar_count; i++) {
 111                 status = ldns_wire2rr(&rr, wire, wire_len, &pos,
 112                                 LDNS_SECTION_ADDITIONAL);
 113                 if (status != LDNS_STATUS_OK) {
 114                         return NULL;
 115                 }
 116                 ldns_rr_free(rr);
 117         }
 118
 119         *result_len = pos;
 120         wire2 = LDNS_XMALLOC(uint8_t, *result_len);
 121         if(!wire2) {
 122                 return NULL;
 123         }
 124         memcpy(wire2, wire, *result_len);
 125
 126         ldns_write_uint16(wire2 + LDNS_ARCOUNT_OFF, ar_count);
 127
 128         return wire2;
 129 }
 130
 131 #ifdef HAVE_SSL
 132 static const EVP_MD *
 133 ldns_digest_function(char *name)
 134 {
 135         /* these are the mandatory algorithms from RFC4635 */
 136         /* The optional algorithms are not yet implemented */
 137         if (strlen(name) == 12
 138                         && strncasecmp(name, "hmac-sha256.", 11) == 0) {
 139 #ifdef HAVE_EVP_SHA256
 140                 return EVP_sha256();
 141 #else
 142                 return NULL;
 143 #endif
 144         } else if (strlen(name) == 10
 145                         && strncasecmp(name, "hmac-sha1.", 9) == 0) {
 146                 return EVP_sha1();
 147         } else if (strlen(name) == 25
 148                         && strncasecmp(name, "hmac-md5.sig-alg.reg.int.", 25)
 149                         == 0) {
 150                 return EVP_md5();
 151         } else {
 152                 return NULL;
 153         }
 154 }
 155 #endif
 156
 157 #ifdef HAVE_SSL
 158 static ldns_status
 159 ldns_tsig_mac_new(ldns_rdf **tsig_mac, uint8_t *pkt_wire, size_t pkt_wire_size,
 160                 const char *key_data, ldns_rdf *key_name_rdf, ldns_rdf *fudge_rdf,
 161                 ldns_rdf *algorithm_rdf, ldns_rdf *time_signed_rdf, ldns_rdf *error_rdf,
 162                 ldns_rdf *other_data_rdf, ldns_rdf *orig_mac_rdf, int tsig_timers_only)
 163 {
 164         ldns_status status;
 165         char *wireformat;
 166         int wiresize;
 167         unsigned char *mac_bytes = NULL;
 168         unsigned char *key_bytes = NULL;
 169         int key_size;
 170         const EVP_MD *digester;
 171         char *algorithm_name = NULL;
 172         unsigned int md_len = EVP_MAX_MD_SIZE;
 173         ldns_rdf *result = NULL;
 174         ldns_buffer *data_buffer = NULL;
 175         ldns_rdf *canonical_key_name_rdf = NULL;
 176         ldns_rdf *canonical_algorithm_rdf = NULL;
 177
 178         if (key_name_rdf == NULL || algorithm_rdf == NULL) {
 179                 return LDNS_STATUS_NULL;
 180         }
 181         canonical_key_name_rdf  = ldns_rdf_clone(key_name_rdf);
 182         if (canonical_key_name_rdf == NULL) {
 183                 return LDNS_STATUS_MEM_ERR;
 184         }
 185         canonical_algorithm_rdf = ldns_rdf_clone(algorithm_rdf);
 186         if (canonical_algorithm_rdf == NULL) {
 187                 ldns_rdf_deep_free(canonical_key_name_rdf);
 188                 return LDNS_STATUS_MEM_ERR;
 189         }
 190         /*
 191          * prepare the digestable information
 192          */
 193         data_buffer = ldns_buffer_new(LDNS_MAX_PACKETLEN);
 194         if (!data_buffer) {
 195                 status = LDNS_STATUS_MEM_ERR;
 196                 goto clean;
 197         }
 198         /* if orig_mac is not NULL, add it too */
 199         if (orig_mac_rdf) {
 200                 (void) ldns_rdf2buffer_wire(data_buffer, orig_mac_rdf);
 201         }
 202         ldns_buffer_write(data_buffer, pkt_wire, pkt_wire_size);
 203         if (!tsig_timers_only) {
 204                 ldns_dname2canonical(canonical_key_name_rdf);
 205                 (void)ldns_rdf2buffer_wire(data_buffer,
 206                                 canonical_key_name_rdf);
 207                 ldns_buffer_write_u16(data_buffer, LDNS_RR_CLASS_ANY);
 208                 ldns_buffer_write_u32(data_buffer, 0);
 209                 ldns_dname2canonical(canonical_algorithm_rdf);
 210                 (void)ldns_rdf2buffer_wire(data_buffer,
 211                                 canonical_algorithm_rdf);
 212         }
 213         (void)ldns_rdf2buffer_wire(data_buffer, time_signed_rdf);
 214         (void)ldns_rdf2buffer_wire(data_buffer, fudge_rdf);
 215         if (!tsig_timers_only) {
 216                 (void)ldns_rdf2buffer_wire(data_buffer, error_rdf);
 217                 (void)ldns_rdf2buffer_wire(data_buffer, other_data_rdf);
 218         }
 219
 220         wireformat = (char *) data_buffer->_data;
 221         wiresize = (int) ldns_buffer_position(data_buffer);
 222
 223         algorithm_name = ldns_rdf2str(algorithm_rdf);
 224         if(!algorithm_name) {
 225                 status = LDNS_STATUS_MEM_ERR;
 226                 goto clean;
 227         }
 228
 229         /* prepare the key */
 230         key_bytes = LDNS_XMALLOC(unsigned char,
 231                         ldns_b64_pton_calculate_size(strlen(key_data)));
 232         if(!key_bytes) {
 233                 status = LDNS_STATUS_MEM_ERR;
 234                 goto clean;
 235         }
 236         key_size = ldns_b64_pton(key_data, key_bytes,
 237         ldns_b64_pton_calculate_size(strlen(key_data)));
 238         if (key_size < 0) {
 239                 status = LDNS_STATUS_INVALID_B64;
 240                 goto clean;
 241         }
 242         /* hmac it */
 243         /* 2 spare bytes for the length */
 244         mac_bytes = LDNS_XMALLOC(unsigned char, md_len+2);
 245         if(!mac_bytes) {
 246                 status = LDNS_STATUS_MEM_ERR;
 247                 goto clean;
 248         }
 249         memset(mac_bytes, 0, md_len+2);
 250
 251         digester = ldns_digest_function(algorithm_name);
 252
 253         if (digester) {
 254                 (void) HMAC(digester, key_bytes, key_size, (void *)wireformat,
 255                             (size_t) wiresize, mac_bytes + 2, &md_len);
 256
 257                 ldns_write_uint16(mac_bytes, md_len);
 258                 result = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_INT16_DATA, md_len + 2,
 259                                 mac_bytes);
 260         } else {
 261                 status = LDNS_STATUS_CRYPTO_UNKNOWN_ALGO;
 262                 goto clean;
 263         }
 264         *tsig_mac = result;
 265         status = LDNS_STATUS_OK;
 266   clean:
 267         LDNS_FREE(mac_bytes);
 268         LDNS_FREE(key_bytes);
 269         LDNS_FREE(algorithm_name);
 270         ldns_buffer_free(data_buffer);
 271         ldns_rdf_deep_free(canonical_algorithm_rdf);
 272         ldns_rdf_deep_free(canonical_key_name_rdf);
 273         return status;
 274 }
 275 #endif /*  HAVE_SSL */
 276
 277
 278 #ifdef HAVE_SSL
 279 bool
 280 ldns_pkt_tsig_verify(ldns_pkt *pkt, uint8_t *wire, size_t wirelen, const char *key_name,
 281         const char *key_data, ldns_rdf *orig_mac_rdf)
 282 {
 283         return ldns_pkt_tsig_verify_next(pkt, wire, wirelen, key_name, key_data, orig_mac_rdf, 0);
 284 }
 285
 286 bool
 287 ldns_pkt_tsig_verify_next(ldns_pkt *pkt, uint8_t *wire, size_t wirelen, const char* key_name,
 288         const char *key_data, ldns_rdf *orig_mac_rdf, int tsig_timers_only)
 289 {
 290         ldns_rdf *fudge_rdf;
 291         ldns_rdf *algorithm_rdf;
 292         ldns_rdf *time_signed_rdf;
 293         ldns_rdf *orig_id_rdf;
 294         ldns_rdf *error_rdf;
 295         ldns_rdf *other_data_rdf;
 296         ldns_rdf *pkt_mac_rdf;
 297         ldns_rdf *my_mac_rdf;
 298         ldns_rdf *key_name_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, key_name);
 299         uint16_t pkt_id, orig_pkt_id;
 300         ldns_status status;
 301
 302         uint8_t *prepared_wire = NULL;
 303         size_t prepared_wire_size = 0;
 304
 305         ldns_rr *orig_tsig = ldns_pkt_tsig(pkt);
 306
 307         if (!orig_tsig || ldns_rr_rd_count(orig_tsig) <= 6) {
 308                 ldns_rdf_deep_free(key_name_rdf);
 309                 return false;
 310         }
 311         algorithm_rdf = ldns_rr_rdf(orig_tsig, 0);
 312         time_signed_rdf = ldns_rr_rdf(orig_tsig, 1);
 313         fudge_rdf = ldns_rr_rdf(orig_tsig, 2);
 314         pkt_mac_rdf = ldns_rr_rdf(orig_tsig, 3);
 315         orig_id_rdf = ldns_rr_rdf(orig_tsig, 4);
 316         error_rdf = ldns_rr_rdf(orig_tsig, 5);
 317         other_data_rdf = ldns_rr_rdf(orig_tsig, 6);
 318
 319         /* remove temporarily */
 320         ldns_pkt_set_tsig(pkt, NULL);
 321         /* temporarily change the id to the original id */
 322         pkt_id = ldns_pkt_id(pkt);
 323         orig_pkt_id = ldns_rdf2native_int16(orig_id_rdf);
 324         ldns_pkt_set_id(pkt, orig_pkt_id);
 325
 326         prepared_wire = ldns_tsig_prepare_pkt_wire(wire, wirelen, &prepared_wire_size);
 327
 328         status = ldns_tsig_mac_new(&my_mac_rdf, prepared_wire, prepared_wire_size,
 329                         key_data, key_name_rdf, fudge_rdf, algorithm_rdf,
 330                         time_signed_rdf, error_rdf, other_data_rdf, orig_mac_rdf, tsig_timers_only);
 331
 332         LDNS_FREE(prepared_wire);
 333
 334         if (status != LDNS_STATUS_OK) {
 335                 ldns_rdf_deep_free(key_name_rdf);
 336                 return false;
 337         }
 338         /* Put back the values */
 339         ldns_pkt_set_tsig(pkt, orig_tsig);
 340         ldns_pkt_set_id(pkt, pkt_id);
 341
 342         ldns_rdf_deep_free(key_name_rdf);
 343
 344         if (ldns_rdf_compare(pkt_mac_rdf, my_mac_rdf) == 0) {
 345                 ldns_rdf_deep_free(my_mac_rdf);
 346                 return true;
 347         } else {
 348                 ldns_rdf_deep_free(my_mac_rdf);
 349                 return false;
 350         }
 351 }
 352 #endif /* HAVE_SSL */
 353
 354 #ifdef HAVE_SSL
 355 ldns_status
 356 ldns_pkt_tsig_sign(ldns_pkt *pkt, const char *key_name, const char *key_data,
 357         uint16_t fudge, const char *algorithm_name, ldns_rdf *query_mac)
 358 {
 359         return ldns_pkt_tsig_sign_next(pkt, key_name, key_data, fudge, algorithm_name, query_mac, 0);
 360 }
 361
 362 ldns_status
 363 ldns_pkt_tsig_sign_next(ldns_pkt *pkt, const char *key_name, const char *key_data,
 364         uint16_t fudge, const char *algorithm_name, ldns_rdf *query_mac, int tsig_timers_only)
 365 {
 366         ldns_rr *tsig_rr;
 367         ldns_rdf *key_name_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, key_name);
 368         ldns_rdf *fudge_rdf = NULL;
 369         ldns_rdf *orig_id_rdf = NULL;
 370         ldns_rdf *algorithm_rdf;
 371         ldns_rdf *error_rdf = NULL;
 372         ldns_rdf *mac_rdf = NULL;
 373         ldns_rdf *other_data_rdf = NULL;
 374
 375         ldns_status status = LDNS_STATUS_OK;
 376
 377         uint8_t *pkt_wire = NULL;
 378         size_t pkt_wire_len;
 379
 380         struct timeval tv_time_signed;
 381         uint8_t *time_signed = NULL;
 382         ldns_rdf *time_signed_rdf = NULL;
 383
 384         algorithm_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, algorithm_name);
 385         if(!key_name_rdf || !algorithm_rdf) {
 386                 status = LDNS_STATUS_MEM_ERR;
 387                 goto clean;
 388         }
 389
 390         /* eww don't have create tsigtime rdf yet :( */
 391         /* bleh :p */
 392         if (gettimeofday(&tv_time_signed, NULL) == 0) {
 393                 time_signed = LDNS_XMALLOC(uint8_t, 6);
 394                 if(!time_signed) {
 395                         status = LDNS_STATUS_MEM_ERR;
 396                         goto clean;
 397                 }
 398                 ldns_write_uint64_as_uint48(time_signed,
 399                                 (uint64_t)tv_time_signed.tv_sec);
 400         } else {
 401                 status = LDNS_STATUS_INTERNAL_ERR;
 402                 goto clean;
 403         }
 404
 405         time_signed_rdf = ldns_rdf_new(LDNS_RDF_TYPE_TSIGTIME, 6, time_signed);
 406         if(!time_signed_rdf) {
 407                 LDNS_FREE(time_signed);
 408                 status = LDNS_STATUS_MEM_ERR;
 409                 goto clean;
 410         }
 411
 412         fudge_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, fudge);
 413
 414         orig_id_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, ldns_pkt_id(pkt));
 415
 416         error_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, 0);
 417
 418         other_data_rdf = ldns_native2rdf_int16_data(0, NULL);
 419
 420         if(!fudge_rdf || !orig_id_rdf || !error_rdf || !other_data_rdf) {
 421                 status = LDNS_STATUS_MEM_ERR;
 422                 goto clean;
 423         }
 424
 425         if (ldns_pkt2wire(&pkt_wire, pkt, &pkt_wire_len) != LDNS_STATUS_OK) {
 426                 status = LDNS_STATUS_ERR;
 427                 goto clean;
 428         }
 429
 430         status = ldns_tsig_mac_new(&mac_rdf, pkt_wire, pkt_wire_len,
 431                         key_data, key_name_rdf, fudge_rdf, algorithm_rdf,
 432                         time_signed_rdf, error_rdf, other_data_rdf, query_mac, tsig_timers_only);
 433
 434         if (!mac_rdf) {
 435                 goto clean;
 436         }
 437
 438         LDNS_FREE(pkt_wire);
 439
 440         /* Create the TSIG RR */
 441         tsig_rr = ldns_rr_new();
 442         if(!tsig_rr) {
 443                 status = LDNS_STATUS_MEM_ERR;
 444                 goto clean;
 445         }
 446         ldns_rr_set_owner(tsig_rr, key_name_rdf);
 447         ldns_rr_set_class(tsig_rr, LDNS_RR_CLASS_ANY);
 448         ldns_rr_set_type(tsig_rr, LDNS_RR_TYPE_TSIG);
 449         ldns_rr_set_ttl(tsig_rr, 0);
 450
 451         ldns_rr_push_rdf(tsig_rr, algorithm_rdf);
 452         ldns_rr_push_rdf(tsig_rr, time_signed_rdf);
 453         ldns_rr_push_rdf(tsig_rr, fudge_rdf);
 454         ldns_rr_push_rdf(tsig_rr, mac_rdf);
 455         ldns_rr_push_rdf(tsig_rr, orig_id_rdf);
 456         ldns_rr_push_rdf(tsig_rr, error_rdf);
 457         ldns_rr_push_rdf(tsig_rr, other_data_rdf);
 458
 459         ldns_pkt_set_tsig(pkt, tsig_rr);
 460
 461         return status;
 462
 463   clean:
 464         LDNS_FREE(pkt_wire);
 465         ldns_rdf_free(key_name_rdf);
 466         ldns_rdf_free(algorithm_rdf);
 467         ldns_rdf_free(time_signed_rdf);
 468         ldns_rdf_free(fudge_rdf);
 469         ldns_rdf_free(orig_id_rdf);
 470         ldns_rdf_free(error_rdf);
 471         ldns_rdf_free(other_data_rdf);
 472         return status;
 473 }
 474 #endif /* HAVE_SSL */