s4 dns: Handle GSS-TSIG signature creation

3 files changed, 144 insertions, 0 deletions

diff --git a/source4/dns_server/dns_crypto.c b/source4/dns_server/dns_crypto.c
index 4be61f6aac..87d82b86a6 100644
--- a/source4/dns_server/dns_crypto.c
+++ b/source4/dns_server/dns_crypto.c
@@ -52,3 +52,130 @@ struct dns_server_tkey *dns_find_tkey(struct dns_server_tkey_store *store,
 
 	return tkey;
 }
+
+WERROR dns_sign_tsig(struct dns_server *dns,
+		     TALLOC_CTX *mem_ctx,
+		     struct dns_request_state *state,
+		     struct dns_name_packet *packet,
+		     uint16_t error)
+{
+	WERROR werror;
+	NTSTATUS status;
+	enum ndr_err_code ndr_err;
+	time_t current_time = time(NULL);
+	DATA_BLOB packet_blob, tsig_blob, sig;
+	uint8_t *buffer = NULL;
+	size_t buffer_len = 0;
+	struct dns_server_tkey * tkey = NULL;
+	struct dns_res_rec *tsig = talloc_zero(mem_ctx, struct dns_res_rec);
+
+	struct dns_fake_tsig_rec *check_rec = talloc_zero(mem_ctx,
+			struct dns_fake_tsig_rec);
+
+	if (tsig == NULL) {
+		return WERR_NOMEM;
+	}
+
+	if (check_rec == NULL) {
+		return WERR_NOMEM;
+	}
+
+	tkey = dns_find_tkey(dns->tkeys, state->key_name);
+	if (tkey == NULL) {
+		/* FIXME: read up on what to do when we can't find a key */
+		return WERR_OK;
+	}
+
+	/* first build and verify check packet */
+	check_rec->name = talloc_strdup(check_rec, tkey->name);
+	if (check_rec->name == NULL) {
+		return WERR_NOMEM;
+	}
+	check_rec->rr_class = DNS_QCLASS_ANY;
+	check_rec->ttl = 0;
+	check_rec->algorithm_name = talloc_strdup(check_rec, tkey->algorithm);
+	if (check_rec->algorithm_name == NULL) {
+		return WERR_NOMEM;
+	}
+	check_rec->time_prefix = 0;
+	check_rec->time = current_time;
+	check_rec->fudge = 300;
+	check_rec->error = state->tsig_error;
+	check_rec->other_size = 0;
+	check_rec->other_data = NULL;
+
+	ndr_err = ndr_push_struct_blob(&packet_blob, mem_ctx, packet,
+		(ndr_push_flags_fn_t)ndr_push_dns_name_packet);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		DEBUG(1, ("Failed to push packet: %s!\n",
+			  ndr_errstr(ndr_err)));
+		return DNS_ERR(SERVER_FAILURE);
+	}
+
+	ndr_err = ndr_push_struct_blob(&tsig_blob, mem_ctx, check_rec,
+		(ndr_push_flags_fn_t)ndr_push_dns_fake_tsig_rec);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		DEBUG(1, ("Failed to push packet: %s!\n",
+			  ndr_errstr(ndr_err)));
+		return DNS_ERR(SERVER_FAILURE);
+	}
+
+	buffer_len = packet_blob.length + tsig_blob.length;
+	buffer = talloc_zero_array(mem_ctx, uint8_t, buffer_len);
+	if (buffer == NULL) {
+		return WERR_NOMEM;
+	}
+
+	memcpy(buffer, packet_blob.data, packet_blob.length);
+	memcpy(buffer+packet_blob.length, tsig_blob.data, tsig_blob.length);
+
+
+	status = gensec_sign_packet(tkey->gensec, mem_ctx, buffer, buffer_len,
+				    buffer, buffer_len, &sig);
+	if (!NT_STATUS_IS_OK(status)) {
+		return ntstatus_to_werror(status);
+	}
+
+	tsig->name = talloc_strdup(tsig, check_rec->name);
+	if (tsig->name == NULL) {
+		return WERR_NOMEM;
+	}
+	tsig->rr_class = check_rec->rr_class;
+	tsig->rr_type = DNS_QTYPE_TSIG;
+	tsig->ttl = 0;
+	tsig->length = UINT16_MAX;
+	tsig->rdata.tsig_record.algorithm_name = talloc_strdup(tsig,
+			check_rec->algorithm_name);
+	tsig->rdata.tsig_record.time_prefix = check_rec->time_prefix;
+	tsig->rdata.tsig_record.time = check_rec->time;
+	tsig->rdata.tsig_record.fudge = check_rec->fudge;
+	tsig->rdata.tsig_record.error = state->tsig_error;
+	tsig->rdata.tsig_record.original_id = packet->id;
+	tsig->rdata.tsig_record.other_size = 0;
+	tsig->rdata.tsig_record.other_data = NULL;
+	tsig->rdata.tsig_record.mac_size = sig.length;
+	tsig->rdata.tsig_record.mac = talloc_memdup(tsig, sig.data, sig.length);
+
+
+	if (packet->arcount == 0) {
+		packet->additional = talloc_zero(mem_ctx, struct dns_res_rec);
+		if (packet->additional == NULL) {
+			return WERR_NOMEM;
+		}
+	}
+	packet->additional = talloc_realloc(mem_ctx, packet->additional,
+					    struct dns_res_rec,
+					    packet->arcount + 1);
+	if (packet->additional == NULL) {
+		return WERR_NOMEM;
+	}
+
+	werror = dns_copy_tsig(mem_ctx, tsig,
+			       &packet->additional[packet->arcount]);
+	if (!W_ERROR_IS_OK(werror)) {
+		return werror;
+	}
+	packet->arcount++;
+
+	return WERR_OK;
+}
diff --git a/source4/dns_server/dns_server.c b/source4/dns_server/dns_server.c
index 887fc8ee1d..795b7198aa 100644
--- a/source4/dns_server/dns_server.c
+++ b/source4/dns_server/dns_server.c
@@ -98,6 +98,7 @@ static void dns_tcp_send(struct stream_connection *conn, uint16_t flags)
 
 struct dns_process_state {
 	DATA_BLOB *in;
+	struct dns_server *dns;
 	struct dns_name_packet in_packet;
 	struct dns_request_state state;
 	uint16_t dns_err;
@@ -123,6 +124,8 @@ static struct tevent_req *dns_process_send(TALLOC_CTX *mem_ctx,
 	}
 	state->in = in;
 
+	state->dns = dns;
+
 	if (in->length < 12) {
 		tevent_req_werror(req, WERR_INVALID_PARAM);
 		return tevent_req_post(req, ev);
@@ -215,6 +218,15 @@ static WERROR dns_process_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
 	}
 	state->out_packet.operation |= state->state.flags;
 
+	if (state->state.sign) {
+		ret = dns_sign_tsig(state->dns, mem_ctx, &state->state,
+				    &state->out_packet, 0);
+		if (!W_ERROR_IS_OK(ret)) {
+			state->dns_err = DNS_RCODE_SERVFAIL;
+			goto drop;
+		}
+	}
+
 	ndr_err = ndr_push_struct_blob(
 		out, mem_ctx, &state->out_packet,
 		(ndr_push_flags_fn_t)ndr_push_dns_name_packet);
diff --git a/source4/dns_server/dns_server.h b/source4/dns_server/dns_server.h
index 8007bcbc08..0093879451 100644
--- a/source4/dns_server/dns_server.h
+++ b/source4/dns_server/dns_server.h
@@ -109,6 +109,11 @@ WERROR dns_name2dn(struct dns_server *dns,
 		   struct ldb_dn **_dn);
 struct dns_server_tkey *dns_find_tkey(struct dns_server_tkey_store *store,
 				      const char *name);
+WERROR dns_sign_tsig(struct dns_server *dns,
+		     TALLOC_CTX *mem_ctx,
+		     struct dns_request_state *state,
+		     struct dns_name_packet *packet,
+		     uint16_t error);
 
 #define DNS_ERR(err_str) WERR_DNS_ERROR_RCODE_##err_str
 #endif /* __DNS_SERVER_H__ */