/* Unix SMB/CIFS implementation. DNS server handler for queries Copyright (C) 2010 Kai Blin This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ #include "includes.h" #include "smbd/service_task.h" #include "libcli/util/werror.h" #include "librpc/ndr/libndr.h" #include "librpc/gen_ndr/ndr_dns.h" #include "librpc/gen_ndr/ndr_dnsp.h" #include #include "param/param.h" #include "dsdb/samdb/samdb.h" #include "dsdb/common/util.h" #include "dns_server/dns_server.h" #include "libcli/dns/libdns.h" #include "lib/util/util_net.h" #include "lib/util/tevent_werror.h" #include "auth/auth.h" #include "auth/credentials/credentials.h" #include "auth/gensec/gensec.h" #undef DBGC_CLASS #define DBGC_CLASS DBGC_DNS static WERROR create_response_rr(const struct dns_name_question *question, const struct dnsp_DnssrvRpcRecord *rec, struct dns_res_rec **answers, uint16_t *ancount) { struct dns_res_rec *ans = *answers; uint16_t ai = *ancount; char *tmp; uint32_t i; ZERO_STRUCT(ans[ai]); switch (rec->wType) { case DNS_QTYPE_CNAME: ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname); W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.cname_record); break; case DNS_QTYPE_A: ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4); W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv4_record); break; case DNS_QTYPE_AAAA: ans[ai].rdata.ipv6_record = talloc_strdup(ans, rec->data.ipv6); W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv6_record); break; case DNS_TYPE_NS: ans[ai].rdata.ns_record = talloc_strdup(ans, rec->data.ns); W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ns_record); break; case DNS_QTYPE_SRV: ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority; ans[ai].rdata.srv_record.weight = rec->data.srv.wWeight; ans[ai].rdata.srv_record.port = rec->data.srv.wPort; ans[ai].rdata.srv_record.target = talloc_strdup( ans, rec->data.srv.nameTarget); W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.srv_record.target); break; case DNS_QTYPE_SOA: ans[ai].rdata.soa_record.mname = talloc_strdup( ans, rec->data.soa.mname); W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.mname); ans[ai].rdata.soa_record.rname = talloc_strdup( ans, rec->data.soa.rname); W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.rname); ans[ai].rdata.soa_record.serial = rec->data.soa.serial; ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh; ans[ai].rdata.soa_record.retry = rec->data.soa.retry; ans[ai].rdata.soa_record.expire = rec->data.soa.expire; ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum; break; case DNS_QTYPE_PTR: ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr); break; case DNS_QTYPE_MX: ans[ai].rdata.mx_record.preference = rec->data.mx.wPriority; ans[ai].rdata.mx_record.exchange = talloc_strdup( ans, rec->data.mx.nameTarget); if (ans[ai].rdata.mx_record.exchange == NULL) { return WERR_NOMEM; } break; case DNS_QTYPE_TXT: tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]); W_ERROR_HAVE_NO_MEMORY(tmp); for (i=1; idata.txt.count; i++) { tmp = talloc_asprintf_append_buffer( tmp, " \"%s\"", rec->data.txt.str[i]); W_ERROR_HAVE_NO_MEMORY(tmp); } ans[ai].rdata.txt_record.txt = tmp; break; default: DEBUG(0, ("Got unhandled type %u query.\n", rec->wType)); return DNS_ERR(NOT_IMPLEMENTED); } ans[ai].name = talloc_strdup(ans, question->name); W_ERROR_HAVE_NO_MEMORY(ans[ai].name); ans[ai].rr_type = rec->wType; ans[ai].rr_class = DNS_QCLASS_IN; ans[ai].ttl = rec->dwTtlSeconds; ans[ai].length = UINT16_MAX; ai++; *answers = ans; *ancount = ai; return WERR_OK; } struct ask_forwarder_state { struct tevent_context *ev; uint16_t id; struct dns_name_packet in_packet; }; static void ask_forwarder_done(struct tevent_req *subreq); static struct tevent_req *ask_forwarder_send( struct dns_server *dns, TALLOC_CTX *mem_ctx, struct tevent_context *ev, const char *forwarder, struct dns_name_question *question) { struct tevent_req *req, *subreq; struct ask_forwarder_state *state; struct dns_res_rec *options; struct dns_name_packet out_packet = { 0, }; DATA_BLOB out_blob; enum ndr_err_code ndr_err; WERROR werr; req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state); if (req == NULL) { return NULL; } state->ev = ev; generate_random_buffer((uint8_t *)&state->id, sizeof(state->id)); if (!is_ipaddress(forwarder)) { DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be " "an IP address\n", forwarder)); tevent_req_werror(req, DNS_ERR(NAME_ERROR)); return tevent_req_post(req, ev); } out_packet.id = state->id; out_packet.operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED; out_packet.qdcount = 1; out_packet.questions = question; werr = dns_generate_options(dns, state, &options); if (!W_ERROR_IS_OK(werr)) { tevent_req_werror(req, werr); return tevent_req_post(req, ev); } out_packet.arcount = 1; out_packet.additional = options; ndr_err = ndr_push_struct_blob( &out_blob, state, &out_packet, (ndr_push_flags_fn_t)ndr_push_dns_name_packet); if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) { tevent_req_werror(req, DNS_ERR(SERVER_FAILURE)); return tevent_req_post(req, ev); } subreq = dns_udp_request_send(state, ev, forwarder, out_blob.data, out_blob.length); if (tevent_req_nomem(subreq, req)) { return tevent_req_post(req, ev); } tevent_req_set_callback(subreq, ask_forwarder_done, req); return req; } static void ask_forwarder_done(struct tevent_req *subreq) { struct tevent_req *req = tevent_req_callback_data( subreq, struct tevent_req); struct ask_forwarder_state *state = tevent_req_data( req, struct ask_forwarder_state); DATA_BLOB in_blob; enum ndr_err_code ndr_err; WERROR ret; ret = dns_udp_request_recv(subreq, state, &in_blob.data, &in_blob.length); TALLOC_FREE(subreq); if (tevent_req_werror(req, ret)) { return; } ndr_err = ndr_pull_struct_blob( &in_blob, state, &state->in_packet, (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet); if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) { tevent_req_werror(req, DNS_ERR(SERVER_FAILURE)); return; } if (state->in_packet.id != state->id) { tevent_req_werror(req, DNS_ERR(NAME_ERROR)); return; } tevent_req_done(req); } static WERROR ask_forwarder_recv( struct tevent_req *req, TALLOC_CTX *mem_ctx, struct dns_res_rec **answers, uint16_t *ancount, struct dns_res_rec **nsrecs, uint16_t *nscount, struct dns_res_rec **additional, uint16_t *arcount) { struct ask_forwarder_state *state = tevent_req_data( req, struct ask_forwarder_state); struct dns_name_packet *in_packet = &state->in_packet; WERROR err; if (tevent_req_is_werror(req, &err)) { return err; } *ancount = in_packet->ancount; *answers = talloc_move(mem_ctx, &in_packet->answers); *nscount = in_packet->nscount; *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs); *arcount = in_packet->arcount; *additional = talloc_move(mem_ctx, &in_packet->additional); return WERR_OK; } static WERROR handle_question(struct dns_server *dns, TALLOC_CTX *mem_ctx, const struct dns_name_question *question, struct dns_res_rec **answers, uint16_t *ancount) { struct dns_res_rec *ans = *answers; WERROR werror; unsigned int ri; struct dnsp_DnssrvRpcRecord *recs; uint16_t rec_count, ai = *ancount; struct ldb_dn *dn = NULL; werror = dns_name2dn(dns, mem_ctx, question->name, &dn); W_ERROR_NOT_OK_RETURN(werror); werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count); W_ERROR_NOT_OK_RETURN(werror); ans = talloc_realloc(mem_ctx, ans, struct dns_res_rec, rec_count + ai); if (ans == NULL) { return WERR_NOMEM; } for (ri = 0; ri < rec_count; ri++) { if ((recs[ri].wType == DNS_TYPE_CNAME) && ((question->question_type == DNS_QTYPE_A) || (question->question_type == DNS_QTYPE_AAAA))) { struct dns_name_question *new_q = talloc(mem_ctx, struct dns_name_question); if (new_q == NULL) { return WERR_NOMEM; } /* We reply with one more record, so grow the array */ ans = talloc_realloc(mem_ctx, ans, struct dns_res_rec, rec_count + 1); if (ans == NULL) { TALLOC_FREE(new_q); return WERR_NOMEM; } /* First put in the CNAME record */ werror = create_response_rr(question, &recs[ri], &ans, &ai); if (!W_ERROR_IS_OK(werror)) { return werror; } /* And then look up the name it points at.. */ /* First build up the new question */ new_q->question_type = question->question_type; new_q->question_class = question->question_class; if (new_q->question_type == DNS_QTYPE_A) { new_q->name = talloc_strdup(new_q, recs[ri].data.ipv4); } else if (new_q->question_type == DNS_QTYPE_AAAA) { new_q->name = talloc_strdup(new_q, recs[ri].data.ipv6); } if (new_q->name == NULL) { TALLOC_FREE(new_q); return WERR_NOMEM; } /* and then call the lookup again */ werror = handle_question(dns, mem_ctx, new_q, &ans, &ai); if (!W_ERROR_IS_OK(werror)) { return werror; } continue; } if ((question->question_type != DNS_QTYPE_ALL) && (recs[ri].wType != question->question_type)) { continue; } werror = create_response_rr(question, &recs[ri], &ans, &ai); if (!W_ERROR_IS_OK(werror)) { return werror; } } if (ai == 0) { return DNS_ERR(NAME_ERROR); } *ancount = ai; *answers = ans; return WERR_OK; } static NTSTATUS create_tkey(struct dns_server *dns, const char* name, const char* algorithm, struct dns_server_tkey **tkey) { NTSTATUS status; struct dns_server_tkey_store *store = dns->tkeys; struct dns_server_tkey *k = talloc_zero(store, struct dns_server_tkey); if (k == NULL) { return NT_STATUS_NO_MEMORY; } k->name = talloc_strdup(k, name); if (k->name == NULL) { return NT_STATUS_NO_MEMORY; } k->algorithm = talloc_strdup(k, algorithm); if (k->algorithm == NULL) { return NT_STATUS_NO_MEMORY; } status = samba_server_gensec_start(k, dns->task->event_ctx, dns->task->msg_ctx, dns->task->lp_ctx, dns->server_credentials, "dns", &k->gensec); if (!NT_STATUS_IS_OK(status)) { DEBUG(1, ("Failed to start GENSEC server code: %s\n", nt_errstr(status))); *tkey = NULL; return status; } gensec_want_feature(k->gensec, GENSEC_FEATURE_SIGN); status = gensec_start_mech_by_oid(k->gensec, GENSEC_OID_SPNEGO); if (!NT_STATUS_IS_OK(status)) { DEBUG(1, ("Failed to start GENSEC server code: %s\n", nt_errstr(status))); *tkey = NULL; return status; } if (store->tkeys[store->next_idx] != NULL) { TALLOC_FREE(store->tkeys[store->next_idx]); } store->tkeys[store->next_idx] = k; (store->next_idx)++; store->next_idx %= store->size; *tkey = k; return NT_STATUS_OK; } static NTSTATUS accept_gss_ticket(TALLOC_CTX *mem_ctx, struct dns_server *dns, struct dns_server_tkey *tkey, const DATA_BLOB *key, DATA_BLOB *reply, uint16_t *dns_auth_error) { NTSTATUS status; status = gensec_update(tkey->gensec, mem_ctx, dns->task->event_ctx, *key, reply); if (NT_STATUS_EQUAL(NT_STATUS_MORE_PROCESSING_REQUIRED, status)) { *dns_auth_error = DNS_RCODE_OK; return status; } if (NT_STATUS_IS_OK(status)) { status = gensec_session_info(tkey->gensec, tkey, &tkey->session_info); if (!NT_STATUS_IS_OK(status)) { *dns_auth_error = DNS_RCODE_BADKEY; return status; } *dns_auth_error = DNS_RCODE_OK; } return status; } static WERROR handle_tkey(struct dns_server *dns, TALLOC_CTX *mem_ctx, const struct dns_name_packet *in, struct dns_request_state *state, struct dns_res_rec **answers, uint16_t *ancount) { struct dns_res_rec *in_tkey = NULL; struct dns_res_rec *ret_tkey; uint16_t i; for (i = 0; i < in->arcount; i++) { if (in->additional[i].rr_type == DNS_QTYPE_TKEY) { in_tkey = &in->additional[i]; break; } } /* If this is a TKEY query, it should have a TKEY RR. * Behaviour is not really specified in RFC 2930 or RFC 3645, but * FORMAT_ERROR seems to be what BIND uses .*/ if (in_tkey == NULL) { return DNS_ERR(FORMAT_ERROR); } ret_tkey = talloc_zero(mem_ctx, struct dns_res_rec); if (ret_tkey == NULL) { return WERR_NOMEM; } ret_tkey->name = talloc_strdup(ret_tkey, in_tkey->name); if (ret_tkey->name == NULL) { return WERR_NOMEM; } ret_tkey->rr_type = DNS_QTYPE_TKEY; ret_tkey->rr_class = DNS_QCLASS_ANY; ret_tkey->length = UINT16_MAX; ret_tkey->rdata.tkey_record.algorithm = talloc_strdup(ret_tkey, in_tkey->rdata.tkey_record.algorithm); if (ret_tkey->rdata.tkey_record.algorithm == NULL) { return WERR_NOMEM; } ret_tkey->rdata.tkey_record.inception = in_tkey->rdata.tkey_record.inception; ret_tkey->rdata.tkey_record.expiration = in_tkey->rdata.tkey_record.expiration; ret_tkey->rdata.tkey_record.mode = in_tkey->rdata.tkey_record.mode; switch (in_tkey->rdata.tkey_record.mode) { case DNS_TKEY_MODE_DH: /* FIXME: According to RFC 2930, we MUST support this, but we don't. * Still, claim it's a bad key instead of a bad mode */ ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY; break; case DNS_TKEY_MODE_GSSAPI: { NTSTATUS status; struct dns_server_tkey *tkey; DATA_BLOB key; DATA_BLOB reply; tkey = dns_find_tkey(dns->tkeys, in->questions[0].name); if (tkey != NULL && tkey->complete) { /* TODO: check if the key is still valid */ DEBUG(1, ("Rejecting tkey negotiation for already established key\n")); ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADNAME; break; } if (tkey == NULL) { status = create_tkey(dns, in->questions[0].name, in_tkey->rdata.tkey_record.algorithm, &tkey); if (!NT_STATUS_IS_OK(status)) { ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY; return ntstatus_to_werror(status); } } key.data = in_tkey->rdata.tkey_record.key_data; key.length = in_tkey->rdata.tkey_record.key_size; status = accept_gss_ticket(ret_tkey, dns, tkey, &key, &reply, &ret_tkey->rdata.tkey_record.error); if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) { DEBUG(1, ("More processing required\n")); ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY; } else if (NT_STATUS_IS_OK(status)) { DEBUG(1, ("Tkey handshake completed\n")); ret_tkey->rdata.tkey_record.key_size = reply.length; ret_tkey->rdata.tkey_record.key_data = talloc_memdup(ret_tkey, reply.data, reply.length); state->sign = true; state->key_name = talloc_strdup(mem_ctx, tkey->name); if (state->key_name == NULL) { return WERR_NOMEM; } } else { DEBUG(1, ("GSS key negotiation returned %s\n", nt_errstr(status))); ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY; } break; } case DNS_TKEY_MODE_DELETE: /* TODO: implement me */ DEBUG(1, ("Should delete tkey here\n")); ret_tkey->rdata.tkey_record.error = DNS_RCODE_OK; break; case DNS_TKEY_MODE_NULL: case DNS_TKEY_MODE_SERVER: case DNS_TKEY_MODE_CLIENT: case DNS_TKEY_MODE_LAST: /* We don't have to implement these, return a mode error */ ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADMODE; break; default: DEBUG(1, ("Unsupported TKEY mode %d\n", in_tkey->rdata.tkey_record.mode)); } *answers = ret_tkey; *ancount = 1; return WERR_OK; } struct dns_server_process_query_state { struct dns_res_rec *answers; uint16_t ancount; struct dns_res_rec *nsrecs; uint16_t nscount; struct dns_res_rec *additional; uint16_t arcount; }; static void dns_server_process_query_got_response(struct tevent_req *subreq); struct tevent_req *dns_server_process_query_send( TALLOC_CTX *mem_ctx, struct tevent_context *ev, struct dns_server *dns, struct dns_request_state *req_state, const struct dns_name_packet *in) { struct tevent_req *req, *subreq; struct dns_server_process_query_state *state; req = tevent_req_create(mem_ctx, &state, struct dns_server_process_query_state); if (req == NULL) { return NULL; } if (in->qdcount != 1) { tevent_req_werror(req, DNS_ERR(FORMAT_ERROR)); return tevent_req_post(req, ev); } /* Windows returns NOT_IMPLEMENTED on this as well */ if (in->questions[0].question_class == DNS_QCLASS_NONE) { tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED)); return tevent_req_post(req, ev); } if (in->questions[0].question_type == DNS_QTYPE_TKEY) { WERROR err; err = handle_tkey(dns, state, in, req_state, &state->answers, &state->ancount); if (tevent_req_werror(req, err)) { return tevent_req_post(req, ev); } tevent_req_done(req); return tevent_req_post(req, ev); } if (dns_authorative_for_zone(dns, in->questions[0].name)) { WERROR err; req_state->flags |= DNS_FLAG_AUTHORITATIVE; err = handle_question(dns, state, &in->questions[0], &state->answers, &state->ancount); if (tevent_req_werror(req, err)) { return tevent_req_post(req, ev); } tevent_req_done(req); return tevent_req_post(req, ev); } if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) && (req_state->flags & DNS_FLAG_RECURSION_AVAIL)) { DEBUG(2, ("Not authoritative for '%s', forwarding\n", in->questions[0].name)); subreq = ask_forwarder_send( dns, state, ev, lpcfg_dns_forwarder(dns->task->lp_ctx), &in->questions[0]); if (tevent_req_nomem(subreq, req)) { return tevent_req_post(req, ev); } tevent_req_set_callback( subreq, dns_server_process_query_got_response, req); return req; } tevent_req_werror(req, DNS_ERR(NAME_ERROR)); return tevent_req_post(req, ev); } static void dns_server_process_query_got_response(struct tevent_req *subreq) { struct tevent_req *req = tevent_req_callback_data( subreq, struct tevent_req); struct dns_server_process_query_state *state = tevent_req_data( req, struct dns_server_process_query_state); WERROR err; err = ask_forwarder_recv(subreq, state, &state->answers, &state->ancount, &state->nsrecs, &state->nscount, &state->additional, &state->arcount); TALLOC_FREE(subreq); if (tevent_req_werror(req, err)) { return; } tevent_req_done(req); } WERROR dns_server_process_query_recv( struct tevent_req *req, TALLOC_CTX *mem_ctx, struct dns_res_rec **answers, uint16_t *ancount, struct dns_res_rec **nsrecs, uint16_t *nscount, struct dns_res_rec **additional, uint16_t *arcount) { struct dns_server_process_query_state *state = tevent_req_data( req, struct dns_server_process_query_state); WERROR err; if (tevent_req_is_werror(req, &err)) { return err; } *answers = talloc_move(mem_ctx, &state->answers); *ancount = state->ancount; *nsrecs = talloc_move(mem_ctx, &state->nsrecs); *nscount = state->nscount; *additional = talloc_move(mem_ctx, &state->additional); *arcount = state->arcount; return WERR_OK; }