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