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samba-mirror/source4/dns_server/dns_crypto.c
Andreas Schneider 121af4c3fc s4:dns_crypto: Remove unused include of hmac_md5.h
Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
2019-02-22 21:48:11 +01:00

435 lines
12 KiB
C

/*
Unix SMB/CIFS implementation.
DNS server handler for signed packets
Copyright (C) 2012 Kai Blin <kai@samba.org>
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 <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "system/network.h"
#include "librpc/ndr/libndr.h"
#include "librpc/gen_ndr/ndr_dns.h"
#include "dns_server/dns_server.h"
#include "libcli/util/ntstatus.h"
#include "auth/auth.h"
#include "auth/gensec/gensec.h"
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_DNS
static WERROR dns_copy_tsig(TALLOC_CTX *mem_ctx,
struct dns_res_rec *old,
struct dns_res_rec *new_rec)
{
new_rec->name = talloc_strdup(mem_ctx, old->name);
W_ERROR_HAVE_NO_MEMORY(new_rec->name);
new_rec->rr_type = old->rr_type;
new_rec->rr_class = old->rr_class;
new_rec->ttl = old->ttl;
new_rec->length = old->length;
new_rec->rdata.tsig_record.algorithm_name = talloc_strdup(mem_ctx,
old->rdata.tsig_record.algorithm_name);
W_ERROR_HAVE_NO_MEMORY(new_rec->rdata.tsig_record.algorithm_name);
new_rec->rdata.tsig_record.time_prefix = old->rdata.tsig_record.time_prefix;
new_rec->rdata.tsig_record.time = old->rdata.tsig_record.time;
new_rec->rdata.tsig_record.fudge = old->rdata.tsig_record.fudge;
new_rec->rdata.tsig_record.mac_size = old->rdata.tsig_record.mac_size;
new_rec->rdata.tsig_record.mac = talloc_memdup(mem_ctx,
old->rdata.tsig_record.mac,
old->rdata.tsig_record.mac_size);
W_ERROR_HAVE_NO_MEMORY(new_rec->rdata.tsig_record.mac);
new_rec->rdata.tsig_record.original_id = old->rdata.tsig_record.original_id;
new_rec->rdata.tsig_record.error = old->rdata.tsig_record.error;
new_rec->rdata.tsig_record.other_size = old->rdata.tsig_record.other_size;
new_rec->rdata.tsig_record.other_data = talloc_memdup(mem_ctx,
old->rdata.tsig_record.other_data,
old->rdata.tsig_record.other_size);
W_ERROR_HAVE_NO_MEMORY(new_rec->rdata.tsig_record.other_data);
return WERR_OK;
}
struct dns_server_tkey *dns_find_tkey(struct dns_server_tkey_store *store,
const char *name)
{
struct dns_server_tkey *tkey = NULL;
uint16_t i = 0;
do {
struct dns_server_tkey *tmp_key = store->tkeys[i];
i++;
i %= TKEY_BUFFER_SIZE;
if (tmp_key == NULL) {
continue;
}
if (dns_name_equal(name, tmp_key->name)) {
tkey = tmp_key;
break;
}
} while (i != 0);
return tkey;
}
WERROR dns_verify_tsig(struct dns_server *dns,
TALLOC_CTX *mem_ctx,
struct dns_request_state *state,
struct dns_name_packet *packet,
DATA_BLOB *in)
{
WERROR werror;
NTSTATUS status;
enum ndr_err_code ndr_err;
uint16_t i, arcount = 0;
DATA_BLOB tsig_blob, fake_tsig_blob, sig;
uint8_t *buffer = NULL;
size_t buffer_len = 0, packet_len = 0;
struct dns_server_tkey *tkey = NULL;
struct dns_fake_tsig_rec *check_rec = talloc_zero(mem_ctx,
struct dns_fake_tsig_rec);
/* Find the first TSIG record in the additional records */
for (i=0; i < packet->arcount; i++) {
if (packet->additional[i].rr_type == DNS_QTYPE_TSIG) {
break;
}
}
if (i == packet->arcount) {
/* no TSIG around */
return WERR_OK;
}
/* The TSIG record needs to be the last additional record */
if (i + 1 != packet->arcount) {
DEBUG(1, ("TSIG record not the last additional record!\n"));
return DNS_ERR(FORMAT_ERROR);
}
/* We got a TSIG, so we need to sign our reply */
state->sign = true;
state->tsig = talloc_zero(state->mem_ctx, struct dns_res_rec);
if (state->tsig == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
werror = dns_copy_tsig(state->tsig, &packet->additional[i],
state->tsig);
if (!W_ERROR_IS_OK(werror)) {
return werror;
}
packet->arcount--;
tkey = dns_find_tkey(dns->tkeys, state->tsig->name);
if (tkey == NULL) {
/*
* We must save the name for use in the TSIG error
* response and have no choice here but to save the
* keyname from the TSIG request.
*/
state->key_name = talloc_strdup(state->mem_ctx,
state->tsig->name);
if (state->key_name == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
state->tsig_error = DNS_RCODE_BADKEY;
return DNS_ERR(NOTAUTH);
}
/*
* Remember the keyname that found an existing tkey, used
* later to fetch the key with dns_find_tkey() when signing
* and adding a TSIG record with MAC.
*/
state->key_name = talloc_strdup(state->mem_ctx, tkey->name);
if (state->key_name == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
/* FIXME: check TSIG here */
if (check_rec == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
/* first build and verify check packet */
check_rec->name = talloc_strdup(check_rec, tkey->name);
if (check_rec->name == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
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_NOT_ENOUGH_MEMORY;
}
check_rec->time_prefix = 0;
check_rec->time = state->tsig->rdata.tsig_record.time;
check_rec->fudge = state->tsig->rdata.tsig_record.fudge;
check_rec->error = 0;
check_rec->other_size = 0;
check_rec->other_data = NULL;
ndr_err = ndr_push_struct_blob(&tsig_blob, mem_ctx, state->tsig,
(ndr_push_flags_fn_t)ndr_push_dns_res_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);
}
ndr_err = ndr_push_struct_blob(&fake_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);
}
/* we need to work some magic here. we need to keep the input packet
* exactly like we got it, but we need to cut off the tsig record */
packet_len = in->length - tsig_blob.length;
buffer_len = packet_len + fake_tsig_blob.length;
buffer = talloc_zero_array(mem_ctx, uint8_t, buffer_len);
if (buffer == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
memcpy(buffer, in->data, packet_len);
memcpy(buffer + packet_len, fake_tsig_blob.data, fake_tsig_blob.length);
sig.length = state->tsig->rdata.tsig_record.mac_size;
sig.data = talloc_memdup(mem_ctx, state->tsig->rdata.tsig_record.mac, sig.length);
if (sig.data == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
/* Now we also need to count down the additional record counter */
arcount = RSVAL(buffer, 10);
RSSVAL(buffer, 10, arcount-1);
status = gensec_check_packet(tkey->gensec, buffer, buffer_len,
buffer, buffer_len, &sig);
if (NT_STATUS_EQUAL(NT_STATUS_ACCESS_DENIED, status)) {
state->tsig_error = DNS_RCODE_BADSIG;
return DNS_ERR(NOTAUTH);
}
if (!NT_STATUS_IS_OK(status)) {
DEBUG(1, ("Verifying tsig failed: %s\n", nt_errstr(status)));
return ntstatus_to_werror(status);
}
state->authenticated = true;
return WERR_OK;
}
static WERROR dns_tsig_compute_mac(TALLOC_CTX *mem_ctx,
struct dns_request_state *state,
struct dns_name_packet *packet,
struct dns_server_tkey *tkey,
time_t current_time,
DATA_BLOB *_psig)
{
NTSTATUS status;
enum ndr_err_code ndr_err;
DATA_BLOB packet_blob, tsig_blob, sig;
uint8_t *buffer = NULL;
uint8_t *p = NULL;
size_t buffer_len = 0;
struct dns_fake_tsig_rec *check_rec = talloc_zero(mem_ctx,
struct dns_fake_tsig_rec);
size_t mac_size = 0;
if (check_rec == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
/* first build and verify check packet */
check_rec->name = talloc_strdup(check_rec, tkey->name);
if (check_rec->name == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
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_NOT_ENOUGH_MEMORY;
}
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);
}
if (state->tsig != NULL) {
mac_size = state->tsig->rdata.tsig_record.mac_size;
}
buffer_len = mac_size;
buffer_len += packet_blob.length;
if (buffer_len < packet_blob.length) {
return WERR_INVALID_PARAMETER;
}
buffer_len += tsig_blob.length;
if (buffer_len < tsig_blob.length) {
return WERR_INVALID_PARAMETER;
}
buffer = talloc_zero_array(mem_ctx, uint8_t, buffer_len);
if (buffer == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
p = buffer;
/*
* RFC 2845 "4.2 TSIG on Answers", how to lay out the buffer
* that we're going to sign:
* 1. MAC of request (if present)
* 2. Outgoing packet
* 3. TSIG record
*/
if (mac_size > 0) {
memcpy(p, state->tsig->rdata.tsig_record.mac, mac_size);
p += mac_size;
}
memcpy(p, packet_blob.data, packet_blob.length);
p += packet_blob.length;
memcpy(p, 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);
}
*_psig = sig;
return WERR_OK;
}
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;
time_t current_time = time(NULL);
struct dns_res_rec *tsig = NULL;
DATA_BLOB sig = (DATA_BLOB) {
.data = NULL,
.length = 0
};
tsig = talloc_zero(mem_ctx, struct dns_res_rec);
if (tsig == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
if (state->tsig_error == DNS_RCODE_OK) {
struct dns_server_tkey *tkey = dns_find_tkey(
dns->tkeys, state->key_name);
if (tkey == NULL) {
return DNS_ERR(SERVER_FAILURE);
}
werror = dns_tsig_compute_mac(mem_ctx, state, packet,
tkey, current_time, &sig);
if (!W_ERROR_IS_OK(werror)) {
return werror;
}
}
tsig->name = talloc_strdup(tsig, state->key_name);
if (tsig->name == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
tsig->rr_class = DNS_QCLASS_ANY;
tsig->rr_type = DNS_QTYPE_TSIG;
tsig->ttl = 0;
tsig->length = UINT16_MAX;
tsig->rdata.tsig_record.algorithm_name = talloc_strdup(tsig, "gss-tsig");
if (tsig->rdata.tsig_record.algorithm_name == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
tsig->rdata.tsig_record.time_prefix = 0;
tsig->rdata.tsig_record.time = current_time;
tsig->rdata.tsig_record.fudge = 300;
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;
if (sig.length > 0) {
tsig->rdata.tsig_record.mac_size = sig.length;
tsig->rdata.tsig_record.mac = talloc_memdup(tsig, sig.data, sig.length);
if (tsig->rdata.tsig_record.mac == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
}
if (packet->arcount == 0) {
packet->additional = talloc_zero(mem_ctx, struct dns_res_rec);
if (packet->additional == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
}
packet->additional = talloc_realloc(mem_ctx, packet->additional,
struct dns_res_rec,
packet->arcount + 1);
if (packet->additional == NULL) {
return WERR_NOT_ENOUGH_MEMORY;
}
werror = dns_copy_tsig(mem_ctx, tsig,
&packet->additional[packet->arcount]);
if (!W_ERROR_IS_OK(werror)) {
return werror;
}
packet->arcount++;
return WERR_OK;
}