--- /dev/null
+/*
+ Unix SMB/CIFS implementation.
+ Group Managed Service Account functions
+
+ Copyright (C) Catalyst.Net Ltd 2024
+
+ 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 <https://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include <gnutls/gnutls.h>
+#include "lib/crypto/gnutls_helpers.h"
+#include "lib/crypto/gkdi.h"
+#include "lib/crypto/gmsa.h"
+#include "librpc/gen_ndr/ndr_security.h"
+
+static const uint8_t gmsa_security_descriptor[] = {
+ /* O:SYD:(A;;FRFW;;;S-1-5-9) */
+ 0x01, 0x00, 0x04, 0x80, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x14, 0x00, 0x00, 0x00, 0x02, 0x00, 0x1c, 0x00,
+ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x14, 0x00, 0x9f, 0x01, 0x12, 0x00,
+ 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05, 0x09, 0x00, 0x00, 0x00,
+ 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05, 0x12, 0x00, 0x00, 0x00};
+
+static const uint8_t gmsa_password_label[] = {
+ /* GMSA PASSWORD as a NULL‐terminated UTF‐16LE string. */
+ 'G', 0, 'M', 0, 'S', 0, 'A', 0, ' ', 0, 'P', 0, 'A', 0,
+ 'S', 0, 'S', 0, 'W', 0, 'O', 0, 'R', 0, 'D', 0, 0, 0,
+};
+
+static NTSTATUS generate_gmsa_password(
+ const uint8_t key[static const GKDI_KEY_LEN],
+ const struct dom_sid *const account_sid,
+ const struct KdfAlgorithm kdf_algorithm,
+ uint8_t password[static const GMSA_PASSWORD_LEN])
+{
+ NTSTATUS status = NT_STATUS_OK;
+ gnutls_mac_algorithm_t algorithm;
+
+ algorithm = get_sp800_108_mac_algorithm(kdf_algorithm);
+ if (algorithm == GNUTLS_MAC_UNKNOWN) {
+ status = NT_STATUS_NOT_SUPPORTED;
+ goto out;
+ }
+
+ if (account_sid == NULL) {
+ status = NT_STATUS_INVALID_PARAMETER;
+ goto out;
+ }
+
+ {
+ uint8_t encoded_sid[ndr_size_dom_sid(account_sid, 0)];
+ {
+ struct ndr_push ndr = {
+ .data = encoded_sid,
+ .alloc_size = sizeof encoded_sid,
+ .fixed_buf_size = true,
+ };
+ enum ndr_err_code ndr_err;
+
+ ndr_err = ndr_push_dom_sid(&ndr,
+ NDR_SCALARS | NDR_BUFFERS,
+ account_sid);
+ if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+ status = ndr_map_error2ntstatus(ndr_err);
+ goto out;
+ }
+ }
+
+ status = samba_gnutls_sp800_108_derive_key(
+ key,
+ GKDI_KEY_LEN,
+ NULL,
+ 0,
+ gmsa_password_label,
+ sizeof gmsa_password_label,
+ encoded_sid,
+ sizeof encoded_sid,
+ algorithm,
+ password,
+ GMSA_PASSWORD_LEN);
+ if (!NT_STATUS_IS_OK(status)) {
+ goto out;
+ }
+ }
+
+out:
+ return status;
+}
+
+static void gmsa_post_process_password_buffer(
+ uint8_t password[static const GMSA_PASSWORD_NULL_TERMINATED_LEN])
+{
+ size_t n;
+
+ for (n = 0; n < GMSA_PASSWORD_LEN; n += 2) {
+ const uint8_t a = password[n];
+ const uint8_t b = password[n + 1];
+ if (!a && !b) {
+ /*
+ * There is a 0.2% chance that the generated password
+ * will contain an embedded null terminator, which will
+ * need to be converted into U+0001.
+ */
+ password[n] = 1;
+ }
+ }
+
+ /* Null‐terminate the password. */
+ password[GMSA_PASSWORD_LEN] = 0;
+ password[GMSA_PASSWORD_LEN + 1] = 0;
+}
+
+NTSTATUS gmsa_password_based_on_key_id(
+ TALLOC_CTX *mem_ctx,
+ const struct Gkid gkid,
+ const NTTIME current_time,
+ const struct ProvRootKey *const root_key,
+ const struct dom_sid *const account_sid,
+ uint8_t password[static const GMSA_PASSWORD_NULL_TERMINATED_LEN])
+{
+ NTSTATUS status = NT_STATUS_OK;
+
+ /* Ensure that a specific seed key is being requested. */
+
+ if (!gkid_is_valid(gkid)) {
+ status = NT_STATUS_INVALID_PARAMETER;
+ goto out;
+ }
+
+ if (gkid_key_type(gkid) != GKID_L2_SEED_KEY) {
+ status = NT_STATUS_INVALID_PARAMETER;
+ goto out;
+ }
+
+ /* Require the root key ID for the moment. */
+ if (root_key == NULL) {
+ status = NT_STATUS_INVALID_PARAMETER;
+ goto out;
+ }
+
+ /* Assert that the root key may be used at this time. */
+ if (current_time < root_key->use_start_time) {
+ status = NT_STATUS_INVALID_PARAMETER;
+ goto out;
+ }
+
+ {
+ /*
+ * The key being requested must not be from the future. That
+ * said, we allow for a little bit of clock skew so that samdb
+ * can compute the next managed password prior to the expiration
+ * of the current one.
+ */
+ const struct Gkid current_gkid = gkdi_get_interval_id(
+ current_time + gkdi_max_clock_skew);
+ if (!gkid_less_than_or_equal_to(gkid, current_gkid)) {
+ status = NT_STATUS_INVALID_PARAMETER;
+ goto out;
+ }
+ }
+
+ /*
+ * Windows’ GetKey() might return not the specified L2 seed key, but an
+ * earlier L2 seed key, or an L1 seed key, leaving the client to perform
+ * the rest of the derivation. We are able to simplify things by always
+ * deriving the specified L2 seed key, but if we implement a
+ * client‐accessible GetKey(), we must take care that it match the
+ * Windows implementation.
+ */
+
+ /*
+ * Depending on the GKID that was requested, Windows’ GetKey() might
+ * return a different L1 or L2 seed key, leaving the client with some
+ * further derivation to do. Our simpler implementation will return
+ * either the exact key the caller requested, or an error code if the
+ * client is not suitably authorized.
+ */
+
+ {
+ uint8_t key[GKDI_KEY_LEN];
+
+ status = compute_seed_key(
+ mem_ctx,
+ data_blob_const(gmsa_security_descriptor,
+ sizeof gmsa_security_descriptor),
+ root_key,
+ gkid,
+ key);
+ if (!NT_STATUS_IS_OK(status)) {
+ goto out;
+ }
+
+ status = generate_gmsa_password(key,
+ account_sid,
+ root_key->kdf_algorithm,
+ password);
+ ZERO_ARRAY(key);
+ if (!NT_STATUS_IS_OK(status)) {
+ goto out;
+ }
+ }
+
+ gmsa_post_process_password_buffer(password);
+
+out:
+ return status;
+}
+
+NTSTATUS gmsa_talloc_password_based_on_key_id(
+ TALLOC_CTX *mem_ctx,
+ const struct Gkid gkid,
+ const NTTIME current_time,
+ const struct ProvRootKey *const root_key,
+ const struct dom_sid *const account_sid,
+ struct gmsa_null_terminated_password **password_out)
+{
+ struct gmsa_null_terminated_password *password = NULL;
+ NTSTATUS status = NT_STATUS_OK;
+
+ if (password_out == NULL) {
+ return NT_STATUS_INVALID_PARAMETER;
+ }
+
+ password = talloc(mem_ctx, struct gmsa_null_terminated_password);
+ if (password == NULL) {
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ status = gmsa_password_based_on_key_id(
+ mem_ctx, gkid, current_time, root_key, account_sid, password->buf);
+ if (!NT_STATUS_IS_OK(status)) {
+ talloc_free(password);
+ return status;
+ }
+
+ *password_out = password;
+ return status;
+}
+
+bool gmsa_current_time(NTTIME *current_time_out)
+{
+ struct timespec current_timespec;
+ int ret;
+
+ ret = clock_gettime(CLOCK_REALTIME, ¤t_timespec);
+ if (ret) {
+ return false;
+ }
+
+ *current_time_out = full_timespec_to_nt_time(¤t_timespec);
+ return true;
+}
git.samba.org / gd / samba-autobuild / .git / blobdiff