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 && strncasecmp(name, "hmac-sha256.", 11) == 0) {
 138 #ifdef HAVE_EVP_SHA256
 139                 return EVP_sha256();
 140 #else
 141                 return NULL;
 142 #endif
 143         } else if (strlen(name) == 10 && strncasecmp(name, "hmac-sha1.", 9) == 0)
 144                 return EVP_sha1();
 145         else if (strlen(name) == 25 && strncasecmp(name,
 146                      "hmac-md5.sig-alg.reg.int.", 25) == 0)
 147                 return EVP_md5();
 148         else
 149                 return NULL;
 150 }
 151 #endif
 152
 153 #ifdef HAVE_SSL
 154 static ldns_status
 155 ldns_tsig_mac_new(ldns_rdf **tsig_mac, uint8_t *pkt_wire, size_t pkt_wire_size,
 156                 const char *key_data, ldns_rdf *key_name_rdf, ldns_rdf *fudge_rdf,
 157                 ldns_rdf *algorithm_rdf, ldns_rdf *time_signed_rdf, ldns_rdf *error_rdf,
 158                 ldns_rdf *other_data_rdf, ldns_rdf *orig_mac_rdf, int tsig_timers_only)
 159 {
 160         char *wireformat;
 161         int wiresize;
 162         unsigned char *mac_bytes;
 163         unsigned char *key_bytes;
 164         int key_size;
 165         const EVP_MD *digester;
 166         char *algorithm_name;
 167         unsigned int md_len = EVP_MAX_MD_SIZE;
 168         ldns_rdf *result = NULL;
 169         ldns_buffer *data_buffer = NULL;
 170
 171         /*
 172          * prepare the digestable information
 173          */
 174         data_buffer = ldns_buffer_new(LDNS_MAX_PACKETLEN);
 175         if(!data_buffer) {
 176                 return LDNS_STATUS_MEM_ERR;
 177         }
 178         /* if orig_mac is not NULL, add it too */
 179         if (orig_mac_rdf) {
 180                 (void) ldns_rdf2buffer_wire(data_buffer, orig_mac_rdf);
 181         }
 182         ldns_buffer_write(data_buffer, pkt_wire, pkt_wire_size);
 183         if (!tsig_timers_only) {
 184                 (void)ldns_rdf2buffer_wire(data_buffer, key_name_rdf);
 185                 ldns_buffer_write_u16(data_buffer, LDNS_RR_CLASS_ANY);
 186                 ldns_buffer_write_u32(data_buffer, 0);
 187                 (void)ldns_rdf2buffer_wire(data_buffer, algorithm_rdf);
 188         }
 189         (void)ldns_rdf2buffer_wire(data_buffer, time_signed_rdf);
 190         (void)ldns_rdf2buffer_wire(data_buffer, fudge_rdf);
 191         if (!tsig_timers_only) {
 192                 (void)ldns_rdf2buffer_wire(data_buffer, error_rdf);
 193                 (void)ldns_rdf2buffer_wire(data_buffer, other_data_rdf);
 194         }
 195
 196         wireformat = (char *) data_buffer->_data;
 197         wiresize = (int) ldns_buffer_position(data_buffer);
 198
 199         algorithm_name = ldns_rdf2str(algorithm_rdf);
 200         if(!algorithm_name) {
 201                 ldns_buffer_free(data_buffer);
 202                 return LDNS_STATUS_MEM_ERR;
 203         }
 204
 205         /* prepare the key */
 206         key_bytes = LDNS_XMALLOC(unsigned char,
 207                         ldns_b64_pton_calculate_size(strlen(key_data)));
 208         if(!key_bytes) {
 209                 LDNS_FREE(algorithm_name);
 210                 ldns_buffer_free(data_buffer);
 211                 return LDNS_STATUS_MEM_ERR;
 212         }
 213         key_size = ldns_b64_pton(key_data, key_bytes,
 214                 ldns_b64_pton_calculate_size(strlen(key_data)));
 215         if (key_size < 0) {
 216                 LDNS_FREE(algorithm_name);
 217                 LDNS_FREE(key_bytes);
 218                 ldns_buffer_free(data_buffer);
 219                 /* LDNS_STATUS_INVALID_B64 */
 220                 return LDNS_STATUS_INVALID_B64;
 221         }
 222         /* hmac it */
 223         /* 2 spare bytes for the length */
 224         mac_bytes = LDNS_XMALLOC(unsigned char, md_len+2);
 225         if(!mac_bytes) {
 226                 LDNS_FREE(algorithm_name);
 227                 LDNS_FREE(key_bytes);
 228                 ldns_buffer_free(data_buffer);
 229                 return LDNS_STATUS_MEM_ERR;
 230         }
 231         memset(mac_bytes, 0, md_len+2);
 232
 233         digester = ldns_digest_function(algorithm_name);
 234
 235         if (digester) {
 236                 (void) HMAC(digester, key_bytes, key_size, (void *)wireformat,
 237                             (size_t) wiresize, mac_bytes + 2, &md_len);
 238
 239                 ldns_write_uint16(mac_bytes, md_len);
 240                 result = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_INT16_DATA, md_len + 2,
 241                                 mac_bytes);
 242         } else {
 243                 LDNS_FREE(algorithm_name);
 244                 LDNS_FREE(mac_bytes);
 245                 LDNS_FREE(key_bytes);
 246                 ldns_buffer_free(data_buffer);
 247                 return LDNS_STATUS_CRYPTO_UNKNOWN_ALGO;
 248         }
 249
 250         LDNS_FREE(algorithm_name);
 251         LDNS_FREE(mac_bytes);
 252         LDNS_FREE(key_bytes);
 253         ldns_buffer_free(data_buffer);
 254
 255         *tsig_mac = result;
 256
 257         return LDNS_STATUS_OK;
 258 }
 259 #endif /*  HAVE_SSL */
 260
 261
 262 #ifdef HAVE_SSL
 263 bool
 264 ldns_pkt_tsig_verify(ldns_pkt *pkt, uint8_t *wire, size_t wirelen, const char *key_name,
 265         const char *key_data, ldns_rdf *orig_mac_rdf)
 266 {
 267         return ldns_pkt_tsig_verify_next(pkt, wire, wirelen, key_name, key_data, orig_mac_rdf, 0);
 268 }
 269
 270 bool
 271 ldns_pkt_tsig_verify_next(ldns_pkt *pkt, uint8_t *wire, size_t wirelen, const char* key_name,
 272         const char *key_data, ldns_rdf *orig_mac_rdf, int tsig_timers_only)
 273 {
 274         ldns_rdf *fudge_rdf;
 275         ldns_rdf *algorithm_rdf;
 276         ldns_rdf *time_signed_rdf;
 277         ldns_rdf *orig_id_rdf;
 278         ldns_rdf *error_rdf;
 279         ldns_rdf *other_data_rdf;
 280         ldns_rdf *pkt_mac_rdf;
 281         ldns_rdf *my_mac_rdf;
 282         ldns_rdf *key_name_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, key_name);
 283         uint16_t pkt_id, orig_pkt_id;
 284         ldns_status status;
 285
 286         uint8_t *prepared_wire = NULL;
 287         size_t prepared_wire_size = 0;
 288
 289         ldns_rr *orig_tsig = ldns_pkt_tsig(pkt);
 290
 291         if (!orig_tsig) {
 292                 ldns_rdf_deep_free(key_name_rdf);
 293                 return false;
 294         }
 295         algorithm_rdf = ldns_rr_rdf(orig_tsig, 0);
 296         time_signed_rdf = ldns_rr_rdf(orig_tsig, 1);
 297         fudge_rdf = ldns_rr_rdf(orig_tsig, 2);
 298         pkt_mac_rdf = ldns_rr_rdf(orig_tsig, 3);
 299         orig_id_rdf = ldns_rr_rdf(orig_tsig, 4);
 300         error_rdf = ldns_rr_rdf(orig_tsig, 5);
 301         other_data_rdf = ldns_rr_rdf(orig_tsig, 6);
 302
 303         /* remove temporarily */
 304         ldns_pkt_set_tsig(pkt, NULL);
 305         /* temporarily change the id to the original id */
 306         pkt_id = ldns_pkt_id(pkt);
 307         orig_pkt_id = ldns_rdf2native_int16(orig_id_rdf);
 308         ldns_pkt_set_id(pkt, orig_pkt_id);
 309
 310         prepared_wire = ldns_tsig_prepare_pkt_wire(wire, wirelen, &prepared_wire_size);
 311
 312         status = ldns_tsig_mac_new(&my_mac_rdf, prepared_wire, prepared_wire_size,
 313                         key_data, key_name_rdf, fudge_rdf, algorithm_rdf,
 314                         time_signed_rdf, error_rdf, other_data_rdf, orig_mac_rdf, tsig_timers_only);
 315
 316         LDNS_FREE(prepared_wire);
 317
 318         if (status != LDNS_STATUS_OK) {
 319                 ldns_rdf_deep_free(key_name_rdf);
 320                 return false;
 321         }
 322         /* Put back the values */
 323         ldns_pkt_set_tsig(pkt, orig_tsig);
 324         ldns_pkt_set_id(pkt, pkt_id);
 325
 326         ldns_rdf_deep_free(key_name_rdf);
 327
 328         if (ldns_rdf_compare(pkt_mac_rdf, my_mac_rdf) == 0) {
 329                 ldns_rdf_deep_free(my_mac_rdf);
 330                 return true;
 331         } else {
 332                 ldns_rdf_deep_free(my_mac_rdf);
 333                 return false;
 334         }
 335 }
 336 #endif /* HAVE_SSL */
 337
 338 #ifdef HAVE_SSL
 339 ldns_status
 340 ldns_pkt_tsig_sign(ldns_pkt *pkt, const char *key_name, const char *key_data,
 341         uint16_t fudge, const char *algorithm_name, ldns_rdf *query_mac)
 342 {
 343         return ldns_pkt_tsig_sign_next(pkt, key_name, key_data, fudge, algorithm_name, query_mac, 0);
 344 }
 345
 346 ldns_status
 347 ldns_pkt_tsig_sign_next(ldns_pkt *pkt, const char *key_name, const char *key_data,
 348         uint16_t fudge, const char *algorithm_name, ldns_rdf *query_mac, int tsig_timers_only)
 349 {
 350         ldns_rr *tsig_rr;
 351         ldns_rdf *key_name_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, key_name);
 352         ldns_rdf *fudge_rdf = NULL;
 353         ldns_rdf *orig_id_rdf = NULL;
 354         ldns_rdf *algorithm_rdf;
 355         ldns_rdf *error_rdf = NULL;
 356         ldns_rdf *mac_rdf = NULL;
 357         ldns_rdf *other_data_rdf = NULL;
 358
 359         ldns_status status = LDNS_STATUS_OK;
 360
 361         uint8_t *pkt_wire = NULL;
 362         size_t pkt_wire_len;
 363
 364         struct timeval tv_time_signed;
 365         uint8_t *time_signed = NULL;
 366         ldns_rdf *time_signed_rdf = NULL;
 367
 368         algorithm_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, algorithm_name);
 369         if(!key_name_rdf || !algorithm_rdf) {
 370                 status = LDNS_STATUS_MEM_ERR;
 371                 goto clean;
 372         }
 373
 374         /* eww don't have create tsigtime rdf yet :( */
 375         /* bleh :p */
 376         if (gettimeofday(&tv_time_signed, NULL) == 0) {
 377                 time_signed = LDNS_XMALLOC(uint8_t, 6);
 378                 if(!time_signed) {
 379                         status = LDNS_STATUS_MEM_ERR;
 380                         goto clean;
 381                 }
 382                 ldns_write_uint64_as_uint48(time_signed,
 383                                 (uint64_t)tv_time_signed.tv_sec);
 384         } else {
 385                 status = LDNS_STATUS_INTERNAL_ERR;
 386                 goto clean;
 387         }
 388
 389         time_signed_rdf = ldns_rdf_new(LDNS_RDF_TYPE_TSIGTIME, 6, time_signed);
 390         if(!time_signed_rdf) {
 391                 LDNS_FREE(time_signed);
 392                 status = LDNS_STATUS_MEM_ERR;
 393                 goto clean;
 394         }
 395
 396         fudge_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, fudge);
 397
 398         orig_id_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, ldns_pkt_id(pkt));
 399
 400         error_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, 0);
 401
 402         other_data_rdf = ldns_native2rdf_int16_data(0, NULL);
 403
 404         if(!fudge_rdf || !orig_id_rdf || !error_rdf || !other_data_rdf) {
 405                 status = LDNS_STATUS_MEM_ERR;
 406                 goto clean;
 407         }
 408
 409         if (ldns_pkt2wire(&pkt_wire, pkt, &pkt_wire_len) != LDNS_STATUS_OK) {
 410                 status = LDNS_STATUS_ERR;
 411                 goto clean;
 412         }
 413
 414         status = ldns_tsig_mac_new(&mac_rdf, pkt_wire, pkt_wire_len,
 415                         key_data, key_name_rdf, fudge_rdf, algorithm_rdf,
 416                         time_signed_rdf, error_rdf, other_data_rdf, query_mac, tsig_timers_only);
 417
 418         if (!mac_rdf) {
 419                 goto clean;
 420         }
 421
 422         LDNS_FREE(pkt_wire);
 423
 424         /* Create the TSIG RR */
 425         tsig_rr = ldns_rr_new();
 426         if(!tsig_rr) {
 427                 status = LDNS_STATUS_MEM_ERR;
 428                 goto clean;
 429         }
 430         ldns_rr_set_owner(tsig_rr, key_name_rdf);
 431         ldns_rr_set_class(tsig_rr, LDNS_RR_CLASS_ANY);
 432         ldns_rr_set_type(tsig_rr, LDNS_RR_TYPE_TSIG);
 433         ldns_rr_set_ttl(tsig_rr, 0);
 434
 435         ldns_rr_push_rdf(tsig_rr, algorithm_rdf);
 436         ldns_rr_push_rdf(tsig_rr, time_signed_rdf);
 437         ldns_rr_push_rdf(tsig_rr, fudge_rdf);
 438         ldns_rr_push_rdf(tsig_rr, mac_rdf);
 439         ldns_rr_push_rdf(tsig_rr, orig_id_rdf);
 440         ldns_rr_push_rdf(tsig_rr, error_rdf);
 441         ldns_rr_push_rdf(tsig_rr, other_data_rdf);
 442
 443         ldns_pkt_set_tsig(pkt, tsig_rr);
 444
 445         return status;
 446
 447   clean:
 448         LDNS_FREE(pkt_wire);
 449         ldns_rdf_free(key_name_rdf);
 450         ldns_rdf_free(algorithm_rdf);
 451         ldns_rdf_free(time_signed_rdf);
 452         ldns_rdf_free(fudge_rdf);
 453         ldns_rdf_free(orig_id_rdf);
 454         ldns_rdf_free(error_rdf);
 455         ldns_rdf_free(other_data_rdf);
 456         return status;
 457 }
 458 #endif /* HAVE_SSL */