source4/dns_server/dns_query.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    DNS server handler for queries
   5
   6    Copyright (C) 2010 Kai Blin  <kai@samba.org>
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "smbd/service_task.h"
  24 #include "libcli/util/werror.h"
  25 #include "librpc/ndr/libndr.h"
  26 #include "librpc/gen_ndr/ndr_dns.h"
  27 #include "librpc/gen_ndr/ndr_dnsp.h"
  28 #include <ldb.h>
  29 #include "param/param.h"
  30 #include "dsdb/samdb/samdb.h"
  31 #include "dsdb/common/util.h"
  32 #include "dns_server/dns_server.h"
  33 #include "libcli/dns/libdns.h"
  34 #include "lib/util/dlinklist.h"
  35 #include "lib/util/util_net.h"
  36 #include "lib/util/tevent_werror.h"
  37 #include "auth/auth.h"
  38 #include "auth/credentials/credentials.h"
  39 #include "auth/gensec/gensec.h"
  40
  41 #undef DBGC_CLASS
  42 #define DBGC_CLASS DBGC_DNS
  43
  44 struct forwarder_string {
  45         const char *forwarder;
  46         struct forwarder_string *prev, *next;
  47 };
  48
  49 static WERROR add_response_rr(const char *name,
  50                               const struct dnsp_DnssrvRpcRecord *rec,
  51                               struct dns_res_rec **answers)
  52 {
  53         struct dns_res_rec *ans = *answers;
  54         uint16_t ai = talloc_array_length(ans);
  55         enum ndr_err_code ndr_err;
  56
  57         if (ai == UINT16_MAX) {
  58                 return WERR_BUFFER_OVERFLOW;
  59         }
  60
  61         /*
  62          * "ans" is always non-NULL and thus its own talloc context
  63          */
  64         ans = talloc_realloc(ans, ans, struct dns_res_rec, ai+1);
  65         if (ans == NULL) {
  66                 return WERR_NOT_ENOUGH_MEMORY;
  67         }
  68
  69         ZERO_STRUCT(ans[ai]);
  70
  71         switch (rec->wType) {
  72         case DNS_QTYPE_CNAME:
  73                 ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
  74                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.cname_record);
  75                 break;
  76         case DNS_QTYPE_A:
  77                 ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
  78                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv4_record);
  79                 break;
  80         case DNS_QTYPE_AAAA:
  81                 ans[ai].rdata.ipv6_record = talloc_strdup(ans, rec->data.ipv6);
  82                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv6_record);
  83                 break;
  84         case DNS_TYPE_NS:
  85                 ans[ai].rdata.ns_record = talloc_strdup(ans, rec->data.ns);
  86                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ns_record);
  87                 break;
  88         case DNS_QTYPE_SRV:
  89                 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
  90                 ans[ai].rdata.srv_record.weight   = rec->data.srv.wWeight;
  91                 ans[ai].rdata.srv_record.port     = rec->data.srv.wPort;
  92                 ans[ai].rdata.srv_record.target   = talloc_strdup(
  93                         ans, rec->data.srv.nameTarget);
  94                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.srv_record.target);
  95                 break;
  96         case DNS_QTYPE_SOA:
  97                 ans[ai].rdata.soa_record.mname   = talloc_strdup(
  98                         ans, rec->data.soa.mname);
  99                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.mname);
 100                 ans[ai].rdata.soa_record.rname   = talloc_strdup(
 101                         ans, rec->data.soa.rname);
 102                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.rname);
 103                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
 104                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
 105                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
 106                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
 107                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
 108                 break;
 109         case DNS_QTYPE_PTR:
 110                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
 111                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ptr_record);
 112                 break;
 113         case DNS_QTYPE_MX:
 114                 ans[ai].rdata.mx_record.preference = rec->data.mx.wPriority;
 115                 ans[ai].rdata.mx_record.exchange = talloc_strdup(
 116                         ans, rec->data.mx.nameTarget);
 117                 if (ans[ai].rdata.mx_record.exchange == NULL) {
 118                         return WERR_NOT_ENOUGH_MEMORY;
 119                 }
 120                 break;
 121         case DNS_QTYPE_TXT:
 122                 ndr_err = ndr_dnsp_string_list_copy(ans,
 123                                                     &rec->data.txt,
 124                                                     &ans[ai].rdata.txt_record.txt);
 125                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 126                         return WERR_NOT_ENOUGH_MEMORY;
 127                 }
 128                 break;
 129         default:
 130                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
 131                 return DNS_ERR(NOT_IMPLEMENTED);
 132         }
 133
 134         ans[ai].name = talloc_strdup(ans, name);
 135         W_ERROR_HAVE_NO_MEMORY(ans[ai].name);
 136         ans[ai].rr_type = rec->wType;
 137         ans[ai].rr_class = DNS_QCLASS_IN;
 138         ans[ai].ttl = rec->dwTtlSeconds;
 139         ans[ai].length = UINT16_MAX;
 140
 141         *answers = ans;
 142
 143         return WERR_OK;
 144 }
 145
 146 static WERROR add_dns_res_rec(struct dns_res_rec **pdst,
 147                               const struct dns_res_rec *src)
 148 {
 149         struct dns_res_rec *dst = *pdst;
 150         uint16_t di = talloc_array_length(dst);
 151         enum ndr_err_code ndr_err;
 152
 153         if (di == UINT16_MAX) {
 154                 return WERR_BUFFER_OVERFLOW;
 155         }
 156
 157         dst = talloc_realloc(dst, dst, struct dns_res_rec, di+1);
 158         if (dst == NULL) {
 159                 return WERR_NOT_ENOUGH_MEMORY;
 160         }
 161
 162         ZERO_STRUCT(dst[di]);
 163
 164         dst[di] = (struct dns_res_rec) {
 165                 .name = talloc_strdup(dst, src->name),
 166                 .rr_type = src->rr_type,
 167                 .rr_class = src->rr_class,
 168                 .ttl = src->ttl,
 169                 .length = src->length
 170         };
 171
 172         if (dst[di].name == NULL) {
 173                 return WERR_NOT_ENOUGH_MEMORY;
 174         }
 175
 176         switch (src->rr_type) {
 177         case DNS_QTYPE_CNAME:
 178                 dst[di].rdata.cname_record = talloc_strdup(
 179                         dst, src->rdata.cname_record);
 180                 if (dst[di].rdata.cname_record == NULL) {
 181                         return WERR_NOT_ENOUGH_MEMORY;
 182                 }
 183                 break;
 184         case DNS_QTYPE_A:
 185                 dst[di].rdata.ipv4_record = talloc_strdup(
 186                         dst, src->rdata.ipv4_record);
 187                 if (dst[di].rdata.ipv4_record == NULL) {
 188                         return WERR_NOT_ENOUGH_MEMORY;
 189                 }
 190                 break;
 191         case DNS_QTYPE_AAAA:
 192                 dst[di].rdata.ipv6_record = talloc_strdup(
 193                         dst, src->rdata.ipv6_record);
 194                 if (dst[di].rdata.ipv6_record == NULL) {
 195                         return WERR_NOT_ENOUGH_MEMORY;
 196                 }
 197                 break;
 198         case DNS_TYPE_NS:
 199                 dst[di].rdata.ns_record = talloc_strdup(
 200                         dst, src->rdata.ns_record);
 201                 if (dst[di].rdata.ns_record == NULL) {
 202                         return WERR_NOT_ENOUGH_MEMORY;
 203                 }
 204                 break;
 205         case DNS_QTYPE_SRV:
 206                 dst[di].rdata.srv_record = (struct dns_srv_record) {
 207                         .priority = src->rdata.srv_record.priority,
 208                         .weight   = src->rdata.srv_record.weight,
 209                         .port     = src->rdata.srv_record.port,
 210                         .target   = talloc_strdup(
 211                                 dst, src->rdata.srv_record.target)
 212                 };
 213                 if (dst[di].rdata.srv_record.target == NULL) {
 214                         return WERR_NOT_ENOUGH_MEMORY;
 215                 }
 216                 break;
 217         case DNS_QTYPE_SOA:
 218                 dst[di].rdata.soa_record = (struct dns_soa_record) {
 219                         .mname   = talloc_strdup(
 220                                 dst, src->rdata.soa_record.mname),
 221                         .rname   = talloc_strdup(
 222                                 dst, src->rdata.soa_record.rname),
 223                         .serial  = src->rdata.soa_record.serial,
 224                         .refresh = src->rdata.soa_record.refresh,
 225                         .retry   = src->rdata.soa_record.retry,
 226                         .expire  = src->rdata.soa_record.expire,
 227                         .minimum = src->rdata.soa_record.minimum
 228                 };
 229
 230                 if ((dst[di].rdata.soa_record.mname == NULL) ||
 231                     (dst[di].rdata.soa_record.rname == NULL)) {
 232                         return WERR_NOT_ENOUGH_MEMORY;
 233                 }
 234
 235                 break;
 236         case DNS_QTYPE_PTR:
 237                 dst[di].rdata.ptr_record = talloc_strdup(
 238                         dst, src->rdata.ptr_record);
 239                 if (dst[di].rdata.ptr_record == NULL) {
 240                         return WERR_NOT_ENOUGH_MEMORY;
 241                 }
 242                 break;
 243         case DNS_QTYPE_MX:
 244                 dst[di].rdata.mx_record = (struct dns_mx_record) {
 245                         .preference = src->rdata.mx_record.preference,
 246                         .exchange   = talloc_strdup(
 247                                 src, src->rdata.mx_record.exchange)
 248                 };
 249
 250                 if (dst[di].rdata.mx_record.exchange == NULL) {
 251                         return WERR_NOT_ENOUGH_MEMORY;
 252                 }
 253                 break;
 254         case DNS_QTYPE_TXT:
 255                 ndr_err = ndr_dnsp_string_list_copy(dst,
 256                                                     &src->rdata.txt_record.txt,
 257                                                     &dst[di].rdata.txt_record.txt);
 258                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 259                         return WERR_NOT_ENOUGH_MEMORY;
 260                 }
 261                 break;
 262         default:
 263                 DBG_WARNING("Got unhandled type %u query.\n", src->rr_type);
 264                 return DNS_ERR(NOT_IMPLEMENTED);
 265         }
 266
 267         *pdst = dst;
 268
 269         return WERR_OK;
 270 }
 271
 272 struct ask_forwarder_state {
 273         struct tevent_context *ev;
 274         uint16_t id;
 275         struct dns_name_packet in_packet;
 276 };
 277
 278 static void ask_forwarder_done(struct tevent_req *subreq);
 279
 280 static struct tevent_req *ask_forwarder_send(
 281         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 282         struct dns_server *dns,
 283         const char *forwarder, struct dns_name_question *question)
 284 {
 285         struct tevent_req *req, *subreq;
 286         struct ask_forwarder_state *state;
 287         struct dns_res_rec *options;
 288         struct dns_name_packet out_packet = { 0, };
 289         DATA_BLOB out_blob;
 290         enum ndr_err_code ndr_err;
 291         WERROR werr;
 292
 293         req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state);
 294         if (req == NULL) {
 295                 return NULL;
 296         }
 297         state->ev = ev;
 298         generate_random_buffer((uint8_t *)&state->id, sizeof(state->id));
 299
 300         if (!is_ipaddress(forwarder)) {
 301                 DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
 302                           "an IP address\n", forwarder));
 303                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 304                 return tevent_req_post(req, ev);
 305         }
 306
 307         out_packet.id = state->id;
 308         out_packet.operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 309         out_packet.qdcount = 1;
 310         out_packet.questions = question;
 311
 312         werr = dns_generate_options(dns, state, &options);
 313         if (!W_ERROR_IS_OK(werr)) {
 314                 tevent_req_werror(req, werr);
 315                 return tevent_req_post(req, ev);
 316         }
 317
 318         out_packet.arcount = 1;
 319         out_packet.additional = options;
 320
 321         ndr_err = ndr_push_struct_blob(
 322                 &out_blob, state, &out_packet,
 323                 (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 324         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 325                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 326                 return tevent_req_post(req, ev);
 327         }
 328         subreq = dns_udp_request_send(state, ev, forwarder, out_blob.data,
 329                                       out_blob.length);
 330         if (tevent_req_nomem(subreq, req)) {
 331                 return tevent_req_post(req, ev);
 332         }
 333         tevent_req_set_callback(subreq, ask_forwarder_done, req);
 334         return req;
 335 }
 336
 337 static void ask_forwarder_done(struct tevent_req *subreq)
 338 {
 339         struct tevent_req *req = tevent_req_callback_data(
 340                 subreq, struct tevent_req);
 341         struct ask_forwarder_state *state = tevent_req_data(
 342                 req, struct ask_forwarder_state);
 343         DATA_BLOB in_blob;
 344         enum ndr_err_code ndr_err;
 345         int ret;
 346
 347         ret = dns_udp_request_recv(subreq, state,
 348                                    &in_blob.data, &in_blob.length);
 349         TALLOC_FREE(subreq);
 350
 351         if (ret != 0) {
 352                 tevent_req_werror(req, unix_to_werror(ret));
 353                 return;
 354         }
 355
 356         ndr_err = ndr_pull_struct_blob(
 357                 &in_blob, state, &state->in_packet,
 358                 (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 359         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 360                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 361                 return;
 362         }
 363         if (state->in_packet.id != state->id) {
 364                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 365                 return;
 366         }
 367         tevent_req_done(req);
 368 }
 369
 370 static WERROR ask_forwarder_recv(
 371         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 372         struct dns_res_rec **answers, uint16_t *ancount,
 373         struct dns_res_rec **nsrecs, uint16_t *nscount,
 374         struct dns_res_rec **additional, uint16_t *arcount)
 375 {
 376         struct ask_forwarder_state *state = tevent_req_data(
 377                 req, struct ask_forwarder_state);
 378         struct dns_name_packet *in_packet = &state->in_packet;
 379         WERROR err;
 380
 381         if (tevent_req_is_werror(req, &err)) {
 382                 return err;
 383         }
 384
 385         *ancount = in_packet->ancount;
 386         *answers = talloc_move(mem_ctx, &in_packet->answers);
 387
 388         *nscount = in_packet->nscount;
 389         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 390
 391         *arcount = in_packet->arcount;
 392         *additional = talloc_move(mem_ctx, &in_packet->additional);
 393
 394         return WERR_OK;
 395 }
 396
 397 static WERROR add_zone_authority_record(struct dns_server *dns,
 398                                         TALLOC_CTX *mem_ctx,
 399                                         const struct dns_name_question *question,
 400                                         struct dns_res_rec **nsrecs)
 401 {
 402         const char *zone = NULL;
 403         struct dnsp_DnssrvRpcRecord *recs;
 404         struct dns_res_rec *ns = *nsrecs;
 405         uint16_t rec_count;
 406         struct ldb_dn *dn = NULL;
 407         unsigned int ri;
 408         WERROR werror;
 409
 410         zone = dns_get_authoritative_zone(dns, question->name);
 411         DEBUG(10, ("Creating zone authority record for '%s'\n", zone));
 412
 413         werror = dns_name2dn(dns, mem_ctx, zone, &dn);
 414         if (!W_ERROR_IS_OK(werror)) {
 415                 return werror;
 416         }
 417
 418         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 419         if (!W_ERROR_IS_OK(werror)) {
 420                 return werror;
 421         }
 422
 423         for (ri = 0; ri < rec_count; ri++) {
 424                 if (recs[ri].wType == DNS_TYPE_SOA) {
 425                         werror = add_response_rr(zone, &recs[ri], &ns);
 426                         if (!W_ERROR_IS_OK(werror)) {
 427                                 return werror;
 428                         }
 429                 }
 430         }
 431
 432         *nsrecs = ns;
 433
 434         return WERR_OK;
 435 }
 436
 437 static struct tevent_req *handle_authoritative_send(
 438         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 439         struct dns_server *dns, const char *forwarder,
 440         struct dns_name_question *question,
 441         struct dns_res_rec **answers, struct dns_res_rec **nsrecs);
 442 static WERROR handle_authoritative_recv(struct tevent_req *req);
 443
 444 struct handle_dnsrpcrec_state {
 445         struct dns_res_rec **answers;
 446         struct dns_res_rec **nsrecs;
 447 };
 448
 449 static void handle_dnsrpcrec_gotauth(struct tevent_req *subreq);
 450 static void handle_dnsrpcrec_gotforwarded(struct tevent_req *subreq);
 451
 452 static struct tevent_req *handle_dnsrpcrec_send(
 453         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 454         struct dns_server *dns, const char *forwarder,
 455         const struct dns_name_question *question,
 456         struct dnsp_DnssrvRpcRecord *rec,
 457         struct dns_res_rec **answers, struct dns_res_rec **nsrecs)
 458 {
 459         struct tevent_req *req, *subreq;
 460         struct handle_dnsrpcrec_state *state;
 461         struct dns_name_question *new_q;
 462         bool resolve_cname;
 463         WERROR werr;
 464
 465         req = tevent_req_create(mem_ctx, &state,
 466                                 struct handle_dnsrpcrec_state);
 467         if (req == NULL) {
 468                 return NULL;
 469         }
 470         state->answers = answers;
 471         state->nsrecs = nsrecs;
 472
 473         resolve_cname = ((rec->wType == DNS_TYPE_CNAME) &&
 474                          ((question->question_type == DNS_QTYPE_A) ||
 475                           (question->question_type == DNS_QTYPE_AAAA)));
 476
 477         if (!resolve_cname) {
 478                 if ((question->question_type != DNS_QTYPE_ALL) &&
 479                     (rec->wType !=
 480                      (enum dns_record_type) question->question_type)) {
 481                         tevent_req_done(req);
 482                         return tevent_req_post(req, ev);
 483                 }
 484
 485                 werr = add_response_rr(question->name, rec, state->answers);
 486                 if (tevent_req_werror(req, werr)) {
 487                         return tevent_req_post(req, ev);
 488                 }
 489
 490                 tevent_req_done(req);
 491                 return tevent_req_post(req, ev);
 492         }
 493
 494         werr = add_response_rr(question->name, rec, state->answers);
 495         if (tevent_req_werror(req, werr)) {
 496                 return tevent_req_post(req, ev);
 497         }
 498
 499         new_q = talloc(state, struct dns_name_question);
 500         if (tevent_req_nomem(new_q, req)) {
 501                 return tevent_req_post(req, ev);
 502         }
 503
 504         *new_q = (struct dns_name_question) {
 505                 .question_type = question->question_type,
 506                 .question_class = question->question_class,
 507                 .name = rec->data.cname
 508         };
 509
 510         if (dns_authoritative_for_zone(dns, new_q->name)) {
 511                 subreq = handle_authoritative_send(
 512                         state, ev, dns, forwarder, new_q,
 513                         state->answers, state->nsrecs);
 514                 if (tevent_req_nomem(subreq, req)) {
 515                         return tevent_req_post(req, ev);
 516                 }
 517                 tevent_req_set_callback(subreq, handle_dnsrpcrec_gotauth, req);
 518                 return req;
 519         }
 520
 521         subreq = ask_forwarder_send(state, ev, dns, forwarder, new_q);
 522         if (tevent_req_nomem(subreq, req)) {
 523                 return tevent_req_post(req, ev);
 524         }
 525         tevent_req_set_callback(subreq, handle_dnsrpcrec_gotforwarded, req);
 526
 527         return req;
 528 }
 529
 530 static void handle_dnsrpcrec_gotauth(struct tevent_req *subreq)
 531 {
 532         struct tevent_req *req = tevent_req_callback_data(
 533                 subreq, struct tevent_req);
 534         WERROR werr;
 535
 536         werr = handle_authoritative_recv(subreq);
 537         TALLOC_FREE(subreq);
 538         if (tevent_req_werror(req, werr)) {
 539                 return;
 540         }
 541         tevent_req_done(req);
 542 }
 543
 544 static void handle_dnsrpcrec_gotforwarded(struct tevent_req *subreq)
 545 {
 546         struct tevent_req *req = tevent_req_callback_data(
 547                 subreq, struct tevent_req);
 548         struct handle_dnsrpcrec_state *state = tevent_req_data(
 549                 req, struct handle_dnsrpcrec_state);
 550         struct dns_res_rec *answers, *nsrecs, *additional;
 551         uint16_t ancount = 0;
 552         uint16_t nscount = 0;
 553         uint16_t arcount = 0;
 554         uint16_t i;
 555         WERROR werr;
 556
 557         werr = ask_forwarder_recv(subreq, state, &answers, &ancount,
 558                                   &nsrecs, &nscount, &additional, &arcount);
 559         if (tevent_req_werror(req, werr)) {
 560                 return;
 561         }
 562
 563         for (i=0; i<ancount; i++) {
 564                 werr = add_dns_res_rec(state->answers, &answers[i]);
 565                 if (tevent_req_werror(req, werr)) {
 566                         return;
 567                 }
 568         }
 569
 570         for (i=0; i<nscount; i++) {
 571                 werr = add_dns_res_rec(state->nsrecs, &nsrecs[i]);
 572                 if (tevent_req_werror(req, werr)) {
 573                         return;
 574                 }
 575         }
 576
 577         tevent_req_done(req);
 578 }
 579
 580 static WERROR handle_dnsrpcrec_recv(struct tevent_req *req)
 581 {
 582         return tevent_req_simple_recv_werror(req);
 583 }
 584
 585 struct handle_authoritative_state {
 586         struct tevent_context *ev;
 587         struct dns_server *dns;
 588         struct dns_name_question *question;
 589         const char *forwarder;
 590
 591         struct dnsp_DnssrvRpcRecord *recs;
 592         uint16_t rec_count;
 593         uint16_t recs_done;
 594
 595         struct dns_res_rec **answers;
 596         struct dns_res_rec **nsrecs;
 597 };
 598
 599 static void handle_authoritative_done(struct tevent_req *subreq);
 600
 601 static struct tevent_req *handle_authoritative_send(
 602         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 603         struct dns_server *dns, const char *forwarder,
 604         struct dns_name_question *question,
 605         struct dns_res_rec **answers, struct dns_res_rec **nsrecs)
 606 {
 607         struct tevent_req *req, *subreq;
 608         struct handle_authoritative_state *state;
 609         struct ldb_dn *dn = NULL;
 610         WERROR werr;
 611
 612         req = tevent_req_create(mem_ctx, &state,
 613                                 struct handle_authoritative_state);
 614         if (req == NULL) {
 615                 return NULL;
 616         }
 617         state->ev = ev;
 618         state->dns = dns;
 619         state->question = question;
 620         state->forwarder = forwarder;
 621         state->answers = answers;
 622         state->nsrecs = nsrecs;
 623
 624         werr = dns_name2dn(dns, state, question->name, &dn);
 625         if (tevent_req_werror(req, werr)) {
 626                 return tevent_req_post(req, ev);
 627         }
 628
 629         werr = dns_lookup_records(dns, state, dn, &state->recs,
 630                                   &state->rec_count);
 631         TALLOC_FREE(dn);
 632         if (tevent_req_werror(req, werr)) {
 633                 return tevent_req_post(req, ev);
 634         }
 635
 636         if (state->rec_count == 0) {
 637                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 638                 return tevent_req_post(req, ev);
 639         }
 640
 641         subreq = handle_dnsrpcrec_send(
 642                 state, state->ev, state->dns, state->forwarder,
 643                 state->question, &state->recs[state->recs_done],
 644                 state->answers, state->nsrecs);
 645         if (tevent_req_nomem(subreq, req)) {
 646                 return tevent_req_post(req, ev);
 647         }
 648         tevent_req_set_callback(subreq, handle_authoritative_done, req);
 649         return req;
 650 }
 651
 652 static void handle_authoritative_done(struct tevent_req *subreq)
 653 {
 654         struct tevent_req *req = tevent_req_callback_data(
 655                 subreq, struct tevent_req);
 656         struct handle_authoritative_state *state = tevent_req_data(
 657                 req, struct handle_authoritative_state);
 658         WERROR werr;
 659
 660         werr = handle_dnsrpcrec_recv(subreq);
 661         TALLOC_FREE(subreq);
 662         if (tevent_req_werror(req, werr)) {
 663                 return;
 664         }
 665
 666         state->recs_done += 1;
 667
 668         if (state->recs_done == state->rec_count) {
 669                 tevent_req_done(req);
 670                 return;
 671         }
 672
 673         subreq = handle_dnsrpcrec_send(
 674                 state, state->ev, state->dns, state->forwarder,
 675                 state->question, &state->recs[state->recs_done],
 676                 state->answers, state->nsrecs);
 677         if (tevent_req_nomem(subreq, req)) {
 678                 return;
 679         }
 680         tevent_req_set_callback(subreq, handle_authoritative_done, req);
 681 }
 682
 683 static WERROR handle_authoritative_recv(struct tevent_req *req)
 684 {
 685         struct handle_authoritative_state *state = tevent_req_data(
 686                 req, struct handle_authoritative_state);
 687         WERROR werr;
 688
 689         if (tevent_req_is_werror(req, &werr)) {
 690                 return werr;
 691         }
 692
 693         werr = add_zone_authority_record(state->dns, state, state->question,
 694                                          state->nsrecs);
 695         if (!W_ERROR_IS_OK(werr)) {
 696                 return werr;
 697         }
 698
 699         return WERR_OK;
 700 }
 701
 702 static NTSTATUS create_tkey(struct dns_server *dns,
 703                             const char* name,
 704                             const char* algorithm,
 705                             const struct tsocket_address *remote_address,
 706                             const struct tsocket_address *local_address,
 707                             struct dns_server_tkey **tkey)
 708 {
 709         NTSTATUS status;
 710         struct dns_server_tkey_store *store = dns->tkeys;
 711         struct dns_server_tkey *k = talloc_zero(store, struct dns_server_tkey);
 712
 713         if (k == NULL) {
 714                 return NT_STATUS_NO_MEMORY;
 715         }
 716
 717         k->name = talloc_strdup(k, name);
 718
 719         if (k->name  == NULL) {
 720                 return NT_STATUS_NO_MEMORY;
 721         }
 722
 723         k->algorithm = talloc_strdup(k, algorithm);
 724         if (k->algorithm == NULL) {
 725                 return NT_STATUS_NO_MEMORY;
 726         }
 727
 728         /*
 729          * We only allow SPNEGO/KRB5 currently
 730          * and rely on the backend to be RPC/IPC free.
 731          *
 732          * It allows gensec_update() not to block.
 733          */
 734         status = samba_server_gensec_krb5_start(k,
 735                                                 dns->task->event_ctx,
 736                                                 dns->task->msg_ctx,
 737                                                 dns->task->lp_ctx,
 738                                                 dns->server_credentials,
 739                                                 "dns",
 740                                                 &k->gensec);
 741         if (!NT_STATUS_IS_OK(status)) {
 742                 DEBUG(1, ("Failed to start GENSEC server code: %s\n", nt_errstr(status)));
 743                 *tkey = NULL;
 744                 return status;
 745         }
 746
 747         gensec_want_feature(k->gensec, GENSEC_FEATURE_SIGN);
 748
 749         status = gensec_set_remote_address(k->gensec,
 750                                            remote_address);
 751         if (!NT_STATUS_IS_OK(status)) {
 752                 DEBUG(1, ("Failed to set remote address into GENSEC: %s\n",
 753                           nt_errstr(status)));
 754                 *tkey = NULL;
 755                 return status;
 756         }
 757
 758         status = gensec_set_local_address(k->gensec,
 759                                           local_address);
 760         if (!NT_STATUS_IS_OK(status)) {
 761                 DEBUG(1, ("Failed to set local address into GENSEC: %s\n",
 762                           nt_errstr(status)));
 763                 *tkey = NULL;
 764                 return status;
 765         }
 766
 767         status = gensec_start_mech_by_oid(k->gensec, GENSEC_OID_SPNEGO);
 768
 769         if (!NT_STATUS_IS_OK(status)) {
 770                 DEBUG(1, ("Failed to start GENSEC server code: %s\n",
 771                           nt_errstr(status)));
 772                 *tkey = NULL;
 773                 return status;
 774         }
 775
 776         if (store->tkeys[store->next_idx] != NULL) {
 777                 TALLOC_FREE(store->tkeys[store->next_idx]);
 778         }
 779
 780         store->tkeys[store->next_idx] = k;
 781         (store->next_idx)++;
 782         store->next_idx %= store->size;
 783
 784         *tkey = k;
 785         return NT_STATUS_OK;
 786 }
 787
 788 static NTSTATUS accept_gss_ticket(TALLOC_CTX *mem_ctx,
 789                                   struct dns_server *dns,
 790                                   struct dns_server_tkey *tkey,
 791                                   const DATA_BLOB *key,
 792                                   DATA_BLOB *reply,
 793                                   uint16_t *dns_auth_error)
 794 {
 795         NTSTATUS status;
 796
 797         /*
 798          * We use samba_server_gensec_krb5_start(),
 799          * which only allows SPNEGO/KRB5 currently
 800          * and makes sure the backend to be RPC/IPC free.
 801          *
 802          * See gensec_gssapi_update_internal() as
 803          * GENSEC_SERVER.
 804          *
 805          * It allows gensec_update() not to block.
 806          *
 807          * If that changes in future we need to use
 808          * gensec_update_send/recv here!
 809          */
 810         status = gensec_update(tkey->gensec, mem_ctx,
 811                                *key, reply);
 812
 813         if (NT_STATUS_EQUAL(NT_STATUS_MORE_PROCESSING_REQUIRED, status)) {
 814                 *dns_auth_error = DNS_RCODE_OK;
 815                 return status;
 816         }
 817
 818         if (NT_STATUS_IS_OK(status)) {
 819
 820                 status = gensec_session_info(tkey->gensec, tkey, &tkey->session_info);
 821                 if (!NT_STATUS_IS_OK(status)) {
 822                         *dns_auth_error = DNS_RCODE_BADKEY;
 823                         return status;
 824                 }
 825                 *dns_auth_error = DNS_RCODE_OK;
 826         }
 827
 828         return status;
 829 }
 830
 831 static WERROR handle_tkey(struct dns_server *dns,
 832                           TALLOC_CTX *mem_ctx,
 833                           const struct dns_name_packet *in,
 834                           struct dns_request_state *state,
 835                           struct dns_res_rec **answers,
 836                           uint16_t *ancount)
 837 {
 838         struct dns_res_rec *in_tkey = NULL;
 839         struct dns_res_rec *ret_tkey;
 840         uint16_t i;
 841
 842         for (i = 0; i < in->arcount; i++) {
 843                 if (in->additional[i].rr_type == DNS_QTYPE_TKEY) {
 844                         in_tkey = &in->additional[i];
 845                         break;
 846                 }
 847         }
 848
 849         /* If this is a TKEY query, it should have a TKEY RR.
 850          * Behaviour is not really specified in RFC 2930 or RFC 3645, but
 851          * FORMAT_ERROR seems to be what BIND uses .*/
 852         if (in_tkey == NULL) {
 853                 return DNS_ERR(FORMAT_ERROR);
 854         }
 855
 856         ret_tkey = talloc_zero(mem_ctx, struct dns_res_rec);
 857         if (ret_tkey == NULL) {
 858                 return WERR_NOT_ENOUGH_MEMORY;
 859         }
 860
 861         ret_tkey->name = talloc_strdup(ret_tkey, in_tkey->name);
 862         if (ret_tkey->name == NULL) {
 863                 return WERR_NOT_ENOUGH_MEMORY;
 864         }
 865
 866         ret_tkey->rr_type = DNS_QTYPE_TKEY;
 867         ret_tkey->rr_class = DNS_QCLASS_ANY;
 868         ret_tkey->length = UINT16_MAX;
 869
 870         ret_tkey->rdata.tkey_record.algorithm = talloc_strdup(ret_tkey,
 871                         in_tkey->rdata.tkey_record.algorithm);
 872         if (ret_tkey->rdata.tkey_record.algorithm  == NULL) {
 873                 return WERR_NOT_ENOUGH_MEMORY;
 874         }
 875
 876         ret_tkey->rdata.tkey_record.inception = in_tkey->rdata.tkey_record.inception;
 877         ret_tkey->rdata.tkey_record.expiration = in_tkey->rdata.tkey_record.expiration;
 878         ret_tkey->rdata.tkey_record.mode = in_tkey->rdata.tkey_record.mode;
 879
 880         switch (in_tkey->rdata.tkey_record.mode) {
 881         case DNS_TKEY_MODE_DH:
 882                 /* FIXME: According to RFC 2930, we MUST support this, but we don't.
 883                  * Still, claim it's a bad key instead of a bad mode */
 884                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 885                 break;
 886         case DNS_TKEY_MODE_GSSAPI: {
 887                 NTSTATUS status;
 888                 struct dns_server_tkey *tkey;
 889                 DATA_BLOB key;
 890                 DATA_BLOB reply;
 891
 892                 tkey = dns_find_tkey(dns->tkeys, in->questions[0].name);
 893                 if (tkey != NULL && tkey->complete) {
 894                         /* TODO: check if the key is still valid */
 895                         DEBUG(1, ("Rejecting tkey negotiation for already established key\n"));
 896                         ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADNAME;
 897                         break;
 898                 }
 899
 900                 if (tkey == NULL) {
 901                         status  = create_tkey(dns, in->questions[0].name,
 902                                               in_tkey->rdata.tkey_record.algorithm,
 903                                               state->remote_address,
 904                                               state->local_address,
 905                                               &tkey);
 906                         if (!NT_STATUS_IS_OK(status)) {
 907                                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 908                                 return ntstatus_to_werror(status);
 909                         }
 910                 }
 911
 912                 key.data = in_tkey->rdata.tkey_record.key_data;
 913                 key.length = in_tkey->rdata.tkey_record.key_size;
 914
 915                 status = accept_gss_ticket(ret_tkey, dns, tkey, &key, &reply,
 916                                            &ret_tkey->rdata.tkey_record.error);
 917                 if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 918                         DEBUG(1, ("More processing required\n"));
 919                         ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 920                 } else if (NT_STATUS_IS_OK(status)) {
 921                         DEBUG(1, ("Tkey handshake completed\n"));
 922                         ret_tkey->rdata.tkey_record.key_size = reply.length;
 923                         ret_tkey->rdata.tkey_record.key_data = talloc_memdup(ret_tkey,
 924                                                                 reply.data,
 925                                                                 reply.length);
 926                         state->sign = true;
 927                         state->key_name = talloc_strdup(state->mem_ctx, tkey->name);
 928                         if (state->key_name == NULL) {
 929                                 return WERR_NOT_ENOUGH_MEMORY;
 930                         }
 931                 } else {
 932                         DEBUG(1, ("GSS key negotiation returned %s\n", nt_errstr(status)));
 933                         ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 934                 }
 935
 936                 break;
 937                 }
 938         case DNS_TKEY_MODE_DELETE:
 939                 /* TODO: implement me */
 940                 DEBUG(1, ("Should delete tkey here\n"));
 941                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_OK;
 942                 break;
 943         case DNS_TKEY_MODE_NULL:
 944         case DNS_TKEY_MODE_SERVER:
 945         case DNS_TKEY_MODE_CLIENT:
 946         case DNS_TKEY_MODE_LAST:
 947                 /* We don't have to implement these, return a mode error */
 948                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADMODE;
 949                 break;
 950         default:
 951                 DEBUG(1, ("Unsupported TKEY mode %d\n",
 952                       in_tkey->rdata.tkey_record.mode));
 953         }
 954
 955         *answers = ret_tkey;
 956         *ancount = 1;
 957
 958         return WERR_OK;
 959 }
 960
 961 struct dns_server_process_query_state {
 962         struct tevent_context *ev;
 963         struct dns_server *dns;
 964         struct dns_name_question *question;
 965
 966         struct dns_res_rec *answers;
 967         uint16_t ancount;
 968         struct dns_res_rec *nsrecs;
 969         uint16_t nscount;
 970         struct dns_res_rec *additional;
 971         uint16_t arcount;
 972         struct forwarder_string *forwarders;
 973 };
 974
 975 static void dns_server_process_query_got_auth(struct tevent_req *subreq);
 976 static void dns_server_process_query_got_response(struct tevent_req *subreq);
 977
 978 struct tevent_req *dns_server_process_query_send(
 979         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 980         struct dns_server *dns, struct dns_request_state *req_state,
 981         const struct dns_name_packet *in)
 982 {
 983         struct tevent_req *req, *subreq;
 984         struct dns_server_process_query_state *state;
 985         const char **forwarders = NULL;
 986         unsigned int i;
 987
 988         req = tevent_req_create(mem_ctx, &state,
 989                                 struct dns_server_process_query_state);
 990         if (req == NULL) {
 991                 return NULL;
 992         }
 993         if (in->qdcount != 1) {
 994                 tevent_req_werror(req, DNS_ERR(FORMAT_ERROR));
 995                 return tevent_req_post(req, ev);
 996         }
 997
 998         /* Windows returns NOT_IMPLEMENTED on this as well */
 999         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
1000                 tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED));
1001                 return tevent_req_post(req, ev);
1002         }
1003
1004         if (in->questions[0].question_type == DNS_QTYPE_TKEY) {
1005                 WERROR err;
1006
1007                 err = handle_tkey(dns, state, in, req_state,
1008                                   &state->answers, &state->ancount);
1009                 if (tevent_req_werror(req, err)) {
1010                         return tevent_req_post(req, ev);
1011                 }
1012                 tevent_req_done(req);
1013                 return tevent_req_post(req, ev);
1014         }
1015
1016         state->dns = dns;
1017         state->ev = ev;
1018         state->question = &in->questions[0];
1019
1020         forwarders = lpcfg_dns_forwarder(dns->task->lp_ctx);
1021         for (i = 0; forwarders != NULL && forwarders[i] != NULL; i++) {
1022                 struct forwarder_string *f = talloc_zero(state,
1023                                                          struct forwarder_string);
1024                 f->forwarder = forwarders[i];
1025                 DLIST_ADD_END(state->forwarders, f);
1026         }
1027
1028         if (dns_authoritative_for_zone(dns, in->questions[0].name)) {
1029
1030                 req_state->flags |= DNS_FLAG_AUTHORITATIVE;
1031
1032                 /*
1033                  * Initialize the response arrays, so that we can use
1034                  * them as their own talloc contexts when doing the
1035                  * realloc
1036                  */
1037                 state->answers = talloc_array(state, struct dns_res_rec, 0);
1038                 if (tevent_req_nomem(state->answers, req)) {
1039                         return tevent_req_post(req, ev);
1040                 }
1041                 state->nsrecs = talloc_array(state, struct dns_res_rec, 0);
1042                 if (tevent_req_nomem(state->nsrecs, req)) {
1043                         return tevent_req_post(req, ev);
1044                 }
1045
1046                 subreq = handle_authoritative_send(
1047                         state, ev, dns, (forwarders == NULL ? NULL : forwarders[0]),
1048                         &in->questions[0], &state->answers, &state->nsrecs);
1049                 if (tevent_req_nomem(subreq, req)) {
1050                         return tevent_req_post(req, ev);
1051                 }
1052                 tevent_req_set_callback(
1053                         subreq, dns_server_process_query_got_auth, req);
1054                 return req;
1055         }
1056
1057         if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) &&
1058             (req_state->flags & DNS_FLAG_RECURSION_AVAIL)) {
1059                 DEBUG(5, ("Not authoritative for '%s', forwarding\n",
1060                           in->questions[0].name));
1061
1062                 subreq = ask_forwarder_send(state, ev, dns,
1063                                             (forwarders == NULL ? NULL : forwarders[0]),
1064                                             &in->questions[0]);
1065                 if (tevent_req_nomem(subreq, req)) {
1066                         return tevent_req_post(req, ev);
1067                 }
1068                 tevent_req_set_callback(
1069                         subreq, dns_server_process_query_got_response, req);
1070                 return req;
1071         }
1072
1073         tevent_req_werror(req, DNS_ERR(NAME_ERROR));
1074         return tevent_req_post(req, ev);
1075 }
1076
1077 static void dns_server_process_query_got_response(struct tevent_req *subreq)
1078 {
1079         struct tevent_req *req = tevent_req_callback_data(
1080                 subreq, struct tevent_req);
1081         struct dns_server_process_query_state *state = tevent_req_data(
1082                 req, struct dns_server_process_query_state);
1083         WERROR werr;
1084
1085         werr = ask_forwarder_recv(subreq, state,
1086                                   &state->answers, &state->ancount,
1087                                   &state->nsrecs, &state->nscount,
1088                                   &state->additional, &state->arcount);
1089         TALLOC_FREE(subreq);
1090
1091         /* If you get an error, attempt a different forwarder */
1092         if (!W_ERROR_IS_OK(werr)) {
1093                 if (state->forwarders != NULL) {
1094                         DLIST_REMOVE(state->forwarders, state->forwarders);
1095                 }
1096
1097                 /* If you have run out of forwarders, simply finish */
1098                 if (state->forwarders == NULL) {
1099                         tevent_req_werror(req, werr);
1100                         return;
1101                 }
1102
1103                 DEBUG(5, ("DNS query returned %s, trying another forwarder.\n",
1104                           win_errstr(werr)));
1105                 subreq = ask_forwarder_send(state, state->ev, state->dns,
1106                                             state->forwarders->forwarder,
1107                                             state->question);
1108
1109                 if (tevent_req_nomem(subreq, req)) {
1110                         return;
1111                 }
1112
1113                 tevent_req_set_callback(subreq,
1114                                         dns_server_process_query_got_response,
1115                                         req);
1116                 return;
1117         }
1118
1119         tevent_req_done(req);
1120 }
1121
1122 static void dns_server_process_query_got_auth(struct tevent_req *subreq)
1123 {
1124         struct tevent_req *req = tevent_req_callback_data(
1125                 subreq, struct tevent_req);
1126         struct dns_server_process_query_state *state = tevent_req_data(
1127                 req, struct dns_server_process_query_state);
1128         WERROR werr;
1129
1130         werr = handle_authoritative_recv(subreq);
1131         TALLOC_FREE(subreq);
1132
1133         /* If you get an error, attempt a different forwarder */
1134         if (!W_ERROR_IS_OK(werr)) {
1135                 if (state->forwarders != NULL) {
1136                         DLIST_REMOVE(state->forwarders, state->forwarders);
1137                 }
1138
1139                 /* If you have run out of forwarders, simply finish */
1140                 if (state->forwarders == NULL) {
1141                         tevent_req_werror(req, werr);
1142                         return;
1143                 }
1144
1145                 DEBUG(5, ("Error: %s, trying a different forwarder.\n",
1146                           win_errstr(werr)));
1147                 subreq = handle_authoritative_send(state, state->ev, state->dns,
1148                                                    state->forwarders->forwarder,
1149                                                    state->question, &state->answers,
1150                                                    &state->nsrecs);
1151
1152                 if (tevent_req_nomem(subreq, req)) {
1153                         return;
1154                 }
1155
1156                 tevent_req_set_callback(subreq,
1157                                         dns_server_process_query_got_auth,
1158                                         req);
1159                 return;
1160         }
1161
1162         state->ancount = talloc_array_length(state->answers);
1163         state->nscount = talloc_array_length(state->nsrecs);
1164         state->arcount = talloc_array_length(state->additional);
1165
1166         tevent_req_done(req);
1167 }
1168
1169 WERROR dns_server_process_query_recv(
1170         struct tevent_req *req, TALLOC_CTX *mem_ctx,
1171         struct dns_res_rec **answers,    uint16_t *ancount,
1172         struct dns_res_rec **nsrecs,     uint16_t *nscount,
1173         struct dns_res_rec **additional, uint16_t *arcount)
1174 {
1175         struct dns_server_process_query_state *state = tevent_req_data(
1176                 req, struct dns_server_process_query_state);
1177         WERROR err = WERR_OK;
1178
1179         if (tevent_req_is_werror(req, &err)) {
1180
1181                 if ((!W_ERROR_EQUAL(err, DNS_ERR(NAME_ERROR))) &&
1182                     (!W_ERROR_EQUAL(err, WERR_DNS_ERROR_NAME_DOES_NOT_EXIST))) {
1183                         return err;
1184                 }
1185         }
1186         *answers = talloc_move(mem_ctx, &state->answers);
1187         *ancount = state->ancount;
1188         *nsrecs = talloc_move(mem_ctx, &state->nsrecs);
1189         *nscount = state->nscount;
1190         *additional = talloc_move(mem_ctx, &state->additional);
1191         *arcount = state->arcount;
1192         return err;
1193 }