Adding upstream version 2:4.20.0+dfsg.upstream/2%4.20.0+dfsg

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1181 insertions, 0 deletions

diff --git a/auth/gensec/schannel.c b/auth/gensec/schannel.c
new file mode 100644
index 0000000..86527fe
--- /dev/null
+++ b/auth/gensec/schannel.c
@@ -0,0 +1,1181 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   dcerpc schannel operations
+
+   Copyright (C) Andrew Tridgell 2004
+   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
+
+   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 <tevent.h>
+#include "lib/util/tevent_ntstatus.h"
+#include "librpc/gen_ndr/ndr_schannel.h"
+#include "auth/auth.h"
+#include "auth/credentials/credentials.h"
+#include "auth/gensec/gensec.h"
+#include "auth/gensec/gensec_internal.h"
+#include "auth/gensec/gensec_proto.h"
+#include "../libcli/auth/schannel.h"
+#include "librpc/gen_ndr/dcerpc.h"
+#include "param/param.h"
+#include "auth/gensec/gensec_toplevel_proto.h"
+#include "libds/common/roles.h"
+
+#include "lib/crypto/gnutls_helpers.h"
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+
+#undef DBGC_CLASS
+#define DBGC_CLASS DBGC_AUTH
+
+struct schannel_state {
+	struct gensec_security *gensec;
+	uint64_t seq_num;
+	bool initiator;
+	struct netlogon_creds_CredentialState *creds;
+	struct auth_user_info_dc *user_info_dc;
+};
+
+#define SETUP_SEQNUM(state, buf, initiator) do { \
+	uint8_t *_buf = buf; \
+	uint32_t _seq_num_low = (state)->seq_num & UINT32_MAX; \
+	uint32_t _seq_num_high = (state)->seq_num >> 32; \
+	if (initiator) { \
+		_seq_num_high |= 0x80000000; \
+	} \
+	RSIVAL(_buf, 0, _seq_num_low); \
+	RSIVAL(_buf, 4, _seq_num_high); \
+} while(0)
+
+static struct schannel_state *netsec_create_state(
+				struct gensec_security *gensec,
+				struct netlogon_creds_CredentialState *creds,
+				bool initiator)
+{
+	struct schannel_state *state;
+
+	state = talloc_zero(gensec, struct schannel_state);
+	if (state == NULL) {
+		return NULL;
+	}
+
+	state->gensec = gensec;
+	state->initiator = initiator;
+	state->creds = netlogon_creds_copy(state, creds);
+	if (state->creds == NULL) {
+		talloc_free(state);
+		return NULL;
+	}
+
+	gensec->private_data = state;
+
+	return state;
+}
+
+static void netsec_offset_and_sizes(struct schannel_state *state,
+				    bool do_seal,
+				    uint32_t *_min_sig_size,
+				    uint32_t *_used_sig_size,
+				    uint32_t *_checksum_length,
+				    uint32_t *_confounder_ofs)
+{
+	uint32_t min_sig_size;
+	uint32_t used_sig_size;
+	uint32_t checksum_length;
+	uint32_t confounder_ofs;
+
+	if (state->creds->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
+		min_sig_size = 48;
+		used_sig_size = 56;
+		/*
+		 * Note: windows has a bug here and uses the old values...
+		 *
+		 * checksum_length = 32;
+		 * confounder_ofs = 48;
+		 */
+		checksum_length = 8;
+		confounder_ofs = 24;
+	} else {
+		min_sig_size = 24;
+		used_sig_size = 32;
+		checksum_length = 8;
+		confounder_ofs = 24;
+	}
+
+	if (do_seal) {
+		min_sig_size += 8;
+	}
+
+	if (_min_sig_size) {
+		*_min_sig_size = min_sig_size;
+	}
+
+	if (_used_sig_size) {
+		*_used_sig_size = used_sig_size;
+	}
+
+	if (_checksum_length) {
+		*_checksum_length = checksum_length;
+	}
+
+	if (_confounder_ofs) {
+		*_confounder_ofs = confounder_ofs;
+	}
+}
+
+/*******************************************************************
+ Encode or Decode the sequence number (which is symmetric)
+ ********************************************************************/
+static NTSTATUS netsec_do_seq_num(struct schannel_state *state,
+				  const uint8_t *checksum,
+				  uint32_t checksum_length,
+				  uint8_t seq_num[8])
+{
+	if (state->creds->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
+		gnutls_cipher_hd_t cipher_hnd = NULL;
+		gnutls_datum_t key = {
+			.data = state->creds->session_key,
+			.size = sizeof(state->creds->session_key),
+		};
+		uint32_t iv_size =
+			gnutls_cipher_get_iv_size(GNUTLS_CIPHER_AES_128_CFB8);
+		uint8_t _iv[iv_size];
+		gnutls_datum_t iv = {
+			.data = _iv,
+			.size = iv_size,
+		};
+		int rc;
+
+		ZERO_ARRAY(_iv);
+
+		memcpy(iv.data + 0, checksum, 8);
+		memcpy(iv.data + 8, checksum, 8);
+
+		rc = gnutls_cipher_init(&cipher_hnd,
+					GNUTLS_CIPHER_AES_128_CFB8,
+					&key,
+					&iv);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc,
+							NT_STATUS_CRYPTO_SYSTEM_INVALID);
+		}
+
+		rc = gnutls_cipher_encrypt(cipher_hnd, seq_num, 8);
+		gnutls_cipher_deinit(cipher_hnd);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc,
+							NT_STATUS_CRYPTO_SYSTEM_INVALID);
+		}
+
+	} else {
+		static const uint8_t zeros[4];
+		uint8_t _sequence_key[16];
+		gnutls_cipher_hd_t cipher_hnd;
+		gnutls_datum_t sequence_key = {
+			.data = _sequence_key,
+			.size = sizeof(_sequence_key),
+		};
+		uint8_t digest1[16];
+		int rc;
+
+		rc = gnutls_hmac_fast(GNUTLS_MAC_MD5,
+				      state->creds->session_key,
+				      sizeof(state->creds->session_key),
+				      zeros,
+				      sizeof(zeros),
+				      digest1);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+
+		rc = gnutls_hmac_fast(GNUTLS_MAC_MD5,
+				      digest1,
+				      sizeof(digest1),
+				      checksum,
+				      checksum_length,
+				      _sequence_key);
+		ZERO_ARRAY(digest1);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+
+		rc = gnutls_cipher_init(&cipher_hnd,
+					GNUTLS_CIPHER_ARCFOUR_128,
+					&sequence_key,
+					NULL);
+		if (rc < 0) {
+			ZERO_ARRAY(_sequence_key);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+
+		rc = gnutls_cipher_encrypt(cipher_hnd,
+					   seq_num,
+					   8);
+		gnutls_cipher_deinit(cipher_hnd);
+		ZERO_ARRAY(_sequence_key);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+	}
+
+	state->seq_num++;
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS netsec_do_seal(struct schannel_state *state,
+			       const uint8_t seq_num[8],
+			       uint8_t confounder[8],
+			       uint8_t *data, uint32_t length,
+			       bool forward)
+{
+	if (state->creds->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
+		gnutls_cipher_hd_t cipher_hnd = NULL;
+		uint8_t sess_kf0[16] = {0};
+		gnutls_datum_t key = {
+			.data = sess_kf0,
+			.size = sizeof(sess_kf0),
+		};
+		uint32_t iv_size =
+			gnutls_cipher_get_iv_size(GNUTLS_CIPHER_AES_128_CFB8);
+		uint8_t _iv[iv_size];
+		gnutls_datum_t iv = {
+			.data = _iv,
+			.size = iv_size,
+		};
+		uint32_t i;
+		int rc;
+
+		for (i = 0; i < key.size; i++) {
+			key.data[i] = state->creds->session_key[i] ^ 0xf0;
+		}
+
+		ZERO_ARRAY(_iv);
+
+		memcpy(iv.data + 0, seq_num, 8);
+		memcpy(iv.data + 8, seq_num, 8);
+
+		rc = gnutls_cipher_init(&cipher_hnd,
+					GNUTLS_CIPHER_AES_128_CFB8,
+					&key,
+					&iv);
+		if (rc < 0) {
+			DBG_ERR("ERROR: gnutls_cipher_init: %s\n",
+				gnutls_strerror(rc));
+			return NT_STATUS_NO_MEMORY;
+		}
+
+		if (forward) {
+			rc = gnutls_cipher_encrypt(cipher_hnd,
+						   confounder,
+						   8);
+			if (rc < 0) {
+				gnutls_cipher_deinit(cipher_hnd);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+			}
+
+			rc = gnutls_cipher_encrypt(cipher_hnd,
+						   data,
+						   length);
+			if (rc < 0) {
+				gnutls_cipher_deinit(cipher_hnd);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+			}
+		} else {
+
+			/*
+			 * Workaround bug present in gnutls 3.6.8:
+			 *
+			 * gnutls_cipher_decrypt() uses an optimization
+			 * internally that breaks decryption when processing
+			 * buffers with their length not being a multiple
+			 * of the blocksize.
+			 */
+
+			uint8_t tmp[16] = { 0, };
+			uint32_t tmp_dlength = MIN(length, sizeof(tmp) - 8);
+
+			memcpy(tmp, confounder, 8);
+			memcpy(tmp + 8, data, tmp_dlength);
+
+			rc = gnutls_cipher_decrypt(cipher_hnd,
+						   tmp,
+						   8 + tmp_dlength);
+			if (rc < 0) {
+				ZERO_STRUCT(tmp);
+				gnutls_cipher_deinit(cipher_hnd);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+			}
+
+			memcpy(confounder, tmp, 8);
+			memcpy(data, tmp + 8, tmp_dlength);
+			ZERO_STRUCT(tmp);
+
+			if (length > tmp_dlength) {
+				rc = gnutls_cipher_decrypt(cipher_hnd,
+							   data + tmp_dlength,
+							   length - tmp_dlength);
+				if (rc < 0) {
+					gnutls_cipher_deinit(cipher_hnd);
+					return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+				}
+			}
+		}
+		gnutls_cipher_deinit(cipher_hnd);
+	} else {
+		gnutls_cipher_hd_t cipher_hnd;
+		uint8_t _sealing_key[16];
+		gnutls_datum_t sealing_key = {
+			.data = _sealing_key,
+			.size = sizeof(_sealing_key),
+		};
+		static const uint8_t zeros[4];
+		uint8_t digest2[16];
+		uint8_t sess_kf0[16];
+		int rc;
+		int i;
+
+		for (i = 0; i < 16; i++) {
+			sess_kf0[i] = state->creds->session_key[i] ^ 0xf0;
+		}
+
+		rc = gnutls_hmac_fast(GNUTLS_MAC_MD5,
+				      sess_kf0,
+				      sizeof(sess_kf0),
+				      zeros,
+				      4,
+				      digest2);
+		if (rc < 0) {
+			ZERO_ARRAY(digest2);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+
+		rc = gnutls_hmac_fast(GNUTLS_MAC_MD5,
+				      digest2,
+				      sizeof(digest2),
+				      seq_num,
+				      8,
+				      _sealing_key);
+
+		ZERO_ARRAY(digest2);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+
+		rc = gnutls_cipher_init(&cipher_hnd,
+					GNUTLS_CIPHER_ARCFOUR_128,
+					&sealing_key,
+					NULL);
+		if (rc < 0) {
+			ZERO_ARRAY(_sealing_key);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+		}
+		rc = gnutls_cipher_encrypt(cipher_hnd,
+					   confounder,
+					   8);
+		if (rc < 0) {
+			ZERO_ARRAY(_sealing_key);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+		}
+		gnutls_cipher_deinit(cipher_hnd);
+		rc = gnutls_cipher_init(&cipher_hnd,
+					GNUTLS_CIPHER_ARCFOUR_128,
+					&sealing_key,
+					NULL);
+		if (rc < 0) {
+			ZERO_ARRAY(_sealing_key);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+		}
+		rc = gnutls_cipher_encrypt(cipher_hnd,
+					   data,
+					   length);
+		gnutls_cipher_deinit(cipher_hnd);
+		ZERO_ARRAY(_sealing_key);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_CRYPTO_SYSTEM_INVALID);
+		}
+	}
+
+	return NT_STATUS_OK;
+}
+
+/*******************************************************************
+ Create a digest over the entire packet (including the data), and
+ MD5 it with the session key.
+ ********************************************************************/
+static NTSTATUS netsec_do_sign(struct schannel_state *state,
+			       const uint8_t *confounder,
+			       const uint8_t *data, size_t length,
+			       uint8_t header[8],
+			       uint8_t *checksum)
+{
+	if (state->creds->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
+		gnutls_hmac_hd_t hmac_hnd = NULL;
+		int rc;
+
+		rc = gnutls_hmac_init(&hmac_hnd,
+				      GNUTLS_MAC_SHA256,
+				      state->creds->session_key,
+				      sizeof(state->creds->session_key));
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+
+		if (confounder) {
+			SSVAL(header, 0, NL_SIGN_HMAC_SHA256);
+			SSVAL(header, 2, NL_SEAL_AES128);
+			SSVAL(header, 4, 0xFFFF);
+			SSVAL(header, 6, 0x0000);
+
+			rc = gnutls_hmac(hmac_hnd, header, 8);
+			if (rc < 0) {
+				gnutls_hmac_deinit(hmac_hnd, NULL);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+			}
+			rc = gnutls_hmac(hmac_hnd, confounder, 8);
+			if (rc < 0) {
+				gnutls_hmac_deinit(hmac_hnd, NULL);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+			}
+		} else {
+			SSVAL(header, 0, NL_SIGN_HMAC_SHA256);
+			SSVAL(header, 2, NL_SEAL_NONE);
+			SSVAL(header, 4, 0xFFFF);
+			SSVAL(header, 6, 0x0000);
+
+			rc = gnutls_hmac(hmac_hnd, header, 8);
+			if (rc < 0) {
+				gnutls_hmac_deinit(hmac_hnd, NULL);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+			}
+		}
+
+		rc = gnutls_hmac(hmac_hnd, data, length);
+		if (rc < 0) {
+			gnutls_hmac_deinit(hmac_hnd, NULL);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+
+		gnutls_hmac_deinit(hmac_hnd, checksum);
+	} else {
+		uint8_t packet_digest[16];
+		static const uint8_t zeros[4];
+		gnutls_hash_hd_t hash_hnd = NULL;
+		int rc;
+
+		rc = gnutls_hash_init(&hash_hnd, GNUTLS_DIG_MD5);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HASH_NOT_SUPPORTED);
+		}
+
+		rc = gnutls_hash(hash_hnd, zeros, sizeof(zeros));
+		if (rc < 0) {
+			gnutls_hash_deinit(hash_hnd, NULL);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HASH_NOT_SUPPORTED);
+		}
+		if (confounder) {
+			SSVAL(header, 0, NL_SIGN_HMAC_MD5);
+			SSVAL(header, 2, NL_SEAL_RC4);
+			SSVAL(header, 4, 0xFFFF);
+			SSVAL(header, 6, 0x0000);
+
+			rc = gnutls_hash(hash_hnd, header, 8);
+			if (rc < 0) {
+				gnutls_hash_deinit(hash_hnd, NULL);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_HASH_NOT_SUPPORTED);
+			}
+			rc = gnutls_hash(hash_hnd, confounder, 8);
+			if (rc < 0) {
+				gnutls_hash_deinit(hash_hnd, NULL);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_HASH_NOT_SUPPORTED);
+			}
+		} else {
+			SSVAL(header, 0, NL_SIGN_HMAC_MD5);
+			SSVAL(header, 2, NL_SEAL_NONE);
+			SSVAL(header, 4, 0xFFFF);
+			SSVAL(header, 6, 0x0000);
+
+			rc = gnutls_hash(hash_hnd, header, 8);
+			if (rc < 0) {
+				gnutls_hash_deinit(hash_hnd, NULL);
+				return gnutls_error_to_ntstatus(rc, NT_STATUS_HASH_NOT_SUPPORTED);
+			}
+		}
+		rc = gnutls_hash(hash_hnd, data, length);
+		if (rc < 0) {
+			gnutls_hash_deinit(hash_hnd, NULL);
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HASH_NOT_SUPPORTED);
+		}
+		gnutls_hash_deinit(hash_hnd, packet_digest);
+
+		rc = gnutls_hmac_fast(GNUTLS_MAC_MD5,
+				      state->creds->session_key,
+				      sizeof(state->creds->session_key),
+				      packet_digest,
+				      sizeof(packet_digest),
+				      checksum);
+		ZERO_ARRAY(packet_digest);
+		if (rc < 0) {
+			return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED);
+		}
+	}
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS netsec_incoming_packet(struct schannel_state *state,
+				bool do_unseal,
+				uint8_t *data, size_t length,
+				const uint8_t *whole_pdu, size_t pdu_length,
+				const DATA_BLOB *sig)
+{
+	uint32_t min_sig_size = 0;
+	uint8_t header[8];
+	uint8_t checksum[32];
+	uint32_t checksum_length = sizeof(checksum_length);
+	uint8_t _confounder[8];
+	uint8_t *confounder = NULL;
+	uint32_t confounder_ofs = 0;
+	uint8_t seq_num[8];
+	bool ret;
+	const uint8_t *sign_data = NULL;
+	size_t sign_length = 0;
+	NTSTATUS status;
+
+	netsec_offset_and_sizes(state,
+				do_unseal,
+				&min_sig_size,
+				NULL,
+				&checksum_length,
+				&confounder_ofs);
+
+	if (sig->length < min_sig_size) {
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	if (do_unseal) {
+		confounder = _confounder;
+		memcpy(confounder, sig->data+confounder_ofs, 8);
+	} else {
+		confounder = NULL;
+	}
+
+	SETUP_SEQNUM(state, seq_num, !state->initiator);
+
+	if (do_unseal) {
+		status = netsec_do_seal(state,
+					seq_num,
+					confounder,
+					data,
+					length,
+					false);
+		if (!NT_STATUS_IS_OK(status)) {
+			DBG_WARNING("netsec_do_seal failed: %s\n", nt_errstr(status));
+			return NT_STATUS_ACCESS_DENIED;
+		}
+	}
+
+	if (state->gensec->want_features & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		sign_data = whole_pdu;
+		sign_length = pdu_length;
+	} else {
+		sign_data = data;
+		sign_length = length;
+	}
+
+	status = netsec_do_sign(state,
+				confounder,
+				sign_data,
+				sign_length,
+				header,
+				checksum);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_WARNING("netsec_do_sign failed: %s\n", nt_errstr(status));
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	ret = mem_equal_const_time(checksum, sig->data+16, checksum_length);
+	if (!ret) {
+		dump_data_pw("calc digest:", checksum, checksum_length);
+		dump_data_pw("wire digest:", sig->data+16, checksum_length);
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	status = netsec_do_seq_num(state, checksum, checksum_length, seq_num);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_WARNING("netsec_do_seq_num failed: %s\n",
+			    nt_errstr(status));
+		return status;
+	}
+
+	ZERO_ARRAY(checksum);
+
+	ret = mem_equal_const_time(seq_num, sig->data+8, 8);
+	if (!ret) {
+		dump_data_pw("calc seq num:", seq_num, 8);
+		dump_data_pw("wire seq num:", sig->data+8, 8);
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	return NT_STATUS_OK;
+}
+
+static uint32_t netsec_outgoing_sig_size(struct schannel_state *state)
+{
+	uint32_t sig_size = 0;
+
+	netsec_offset_and_sizes(state,
+				true,
+				NULL,
+				&sig_size,
+				NULL,
+				NULL);
+
+	return sig_size;
+}
+
+static NTSTATUS netsec_outgoing_packet(struct schannel_state *state,
+				TALLOC_CTX *mem_ctx,
+				bool do_seal,
+				uint8_t *data, size_t length,
+				const uint8_t *whole_pdu, size_t pdu_length,
+				DATA_BLOB *sig)
+{
+	uint32_t min_sig_size = 0;
+	uint32_t used_sig_size = 0;
+	uint8_t header[8];
+	uint8_t checksum[32];
+	uint32_t checksum_length = sizeof(checksum_length);
+	uint8_t _confounder[8];
+	uint8_t *confounder = NULL;
+	uint32_t confounder_ofs = 0;
+	uint8_t seq_num[8];
+	const uint8_t *sign_data = NULL;
+	size_t sign_length = 0;
+	NTSTATUS status;
+
+	netsec_offset_and_sizes(state,
+				do_seal,
+				&min_sig_size,
+				&used_sig_size,
+				&checksum_length,
+				&confounder_ofs);
+
+	SETUP_SEQNUM(state, seq_num, state->initiator);
+
+	if (do_seal) {
+		confounder = _confounder;
+		generate_random_buffer(confounder, 8);
+	} else {
+		confounder = NULL;
+	}
+
+	if (state->gensec->want_features & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		sign_data = whole_pdu;
+		sign_length = pdu_length;
+	} else {
+		sign_data = data;
+		sign_length = length;
+	}
+
+	status = netsec_do_sign(state,
+				confounder,
+				sign_data,
+				sign_length,
+				header,
+				checksum);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_WARNING("netsec_do_sign failed: %s\n", nt_errstr(status));
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	if (do_seal) {
+		status = netsec_do_seal(state,
+					seq_num,
+					confounder,
+					data,
+					length,
+					true);
+		if (!NT_STATUS_IS_OK(status)) {
+			DBG_WARNING("netsec_do_seal failed: %s\n",
+				    nt_errstr(status));
+			return status;
+		}
+	}
+
+	status = netsec_do_seq_num(state, checksum, checksum_length, seq_num);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_WARNING("netsec_do_seq_num failed: %s\n",
+			    nt_errstr(status));
+		return status;
+	}
+
+	(*sig) = data_blob_talloc_zero(mem_ctx, used_sig_size);
+
+	memcpy(sig->data, header, 8);
+	memcpy(sig->data+8, seq_num, 8);
+	memcpy(sig->data+16, checksum, checksum_length);
+
+	if (confounder) {
+		memcpy(sig->data+confounder_ofs, confounder, 8);
+	}
+
+	dump_data_pw("signature:", sig->data+ 0, 8);
+	dump_data_pw("seq_num  :", sig->data+ 8, 8);
+	dump_data_pw("digest   :", sig->data+16, checksum_length);
+	dump_data_pw("confound :", sig->data+confounder_ofs, 8);
+
+	return NT_STATUS_OK;
+}
+
+_PUBLIC_ NTSTATUS gensec_schannel_init(TALLOC_CTX *ctx);
+
+static size_t schannel_sig_size(struct gensec_security *gensec_security, size_t data_size)
+{
+	struct schannel_state *state =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct schannel_state);
+
+	return netsec_outgoing_sig_size(state);
+}
+
+struct schannel_update_state {
+	NTSTATUS status;
+	DATA_BLOB out;
+};
+
+static NTSTATUS schannel_update_internal(struct gensec_security *gensec_security,
+					 TALLOC_CTX *out_mem_ctx,
+					 const DATA_BLOB in, DATA_BLOB *out);
+
+static struct tevent_req *schannel_update_send(TALLOC_CTX *mem_ctx,
+					       struct tevent_context *ev,
+					       struct gensec_security *gensec_security,
+					       const DATA_BLOB in)
+{
+	struct tevent_req *req;
+	struct schannel_update_state *state = NULL;
+	NTSTATUS status;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct schannel_update_state);
+	if (req == NULL) {
+		return NULL;
+	}
+
+	status = schannel_update_internal(gensec_security,
+					  state, in,
+					  &state->out);
+	state->status = status;
+	if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
+		status = NT_STATUS_OK;
+	}
+	if (tevent_req_nterror(req, status)) {
+		return tevent_req_post(req, ev);
+	}
+
+	tevent_req_done(req);
+	return tevent_req_post(req, ev);
+}
+
+static NTSTATUS schannel_update_internal(struct gensec_security *gensec_security,
+					 TALLOC_CTX *out_mem_ctx,
+					 const DATA_BLOB in, DATA_BLOB *out)
+{
+	struct schannel_state *state =
+		talloc_get_type(gensec_security->private_data,
+		struct schannel_state);
+	NTSTATUS status;
+	enum ndr_err_code ndr_err;
+	struct NL_AUTH_MESSAGE bind_schannel = {
+		.Flags = 0,
+	};
+	struct NL_AUTH_MESSAGE bind_schannel_ack;
+	struct netlogon_creds_CredentialState *creds;
+	const char *workstation;
+	const char *domain;
+
+	*out = data_blob(NULL, 0);
+
+	if (gensec_security->dcerpc_auth_level < DCERPC_AUTH_LEVEL_INTEGRITY) {
+		switch (gensec_security->gensec_role) {
+		case GENSEC_CLIENT:
+			return NT_STATUS_INVALID_PARAMETER_MIX;
+		case GENSEC_SERVER:
+			return NT_STATUS_INVALID_PARAMETER;
+		}
+		return NT_STATUS_INTERNAL_ERROR;
+	}
+
+	switch (gensec_security->gensec_role) {
+	case GENSEC_CLIENT:
+		if (state != NULL) {
+			/* we could parse the bind ack, but we don't know what it is yet */
+			return NT_STATUS_OK;
+		}
+
+		creds = cli_credentials_get_netlogon_creds(gensec_security->credentials);
+		if (creds == NULL) {
+			return NT_STATUS_INVALID_PARAMETER_MIX;
+		}
+
+		state = netsec_create_state(gensec_security,
+					    creds, true /* initiator */);
+		if (state == NULL) {
+			return NT_STATUS_NO_MEMORY;
+		}
+
+		bind_schannel.MessageType = NL_NEGOTIATE_REQUEST;
+
+		bind_schannel.Flags = NL_FLAG_OEM_NETBIOS_DOMAIN_NAME |
+				      NL_FLAG_OEM_NETBIOS_COMPUTER_NAME;
+		bind_schannel.oem_netbios_domain.a = cli_credentials_get_domain(gensec_security->credentials);
+		bind_schannel.oem_netbios_computer.a = creds->computer_name;
+
+		if (creds->secure_channel_type == SEC_CHAN_DNS_DOMAIN) {
+			bind_schannel.Flags |= NL_FLAG_UTF8_DNS_DOMAIN_NAME;
+			bind_schannel.utf8_dns_domain.u = cli_credentials_get_realm(gensec_security->credentials);
+
+			bind_schannel.Flags |= NL_FLAG_UTF8_NETBIOS_COMPUTER_NAME;
+			bind_schannel.utf8_netbios_computer.u = creds->computer_name;
+		}
+
+		ndr_err = ndr_push_struct_blob(out, out_mem_ctx, &bind_schannel,
+					       (ndr_push_flags_fn_t)ndr_push_NL_AUTH_MESSAGE);
+		if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+			status = ndr_map_error2ntstatus(ndr_err);
+			DEBUG(3, ("Could not create schannel bind: %s\n",
+				  nt_errstr(status)));
+			return status;
+		}
+
+		return NT_STATUS_MORE_PROCESSING_REQUIRED;
+	case GENSEC_SERVER:
+
+		if (state != NULL) {
+			/* no third leg on this protocol */
+			return NT_STATUS_INVALID_PARAMETER;
+		}
+
+		/* parse the schannel startup blob */
+		ndr_err = ndr_pull_struct_blob(&in, out_mem_ctx, &bind_schannel,
+			(ndr_pull_flags_fn_t)ndr_pull_NL_AUTH_MESSAGE);
+		if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+			status = ndr_map_error2ntstatus(ndr_err);
+			DEBUG(3, ("Could not parse incoming schannel bind: %s\n",
+				  nt_errstr(status)));
+			return status;
+		}
+
+		if (bind_schannel.Flags & NL_FLAG_OEM_NETBIOS_DOMAIN_NAME) {
+			domain = bind_schannel.oem_netbios_domain.a;
+			if (strcasecmp_m(domain, lpcfg_workgroup(gensec_security->settings->lp_ctx)) != 0) {
+				DEBUG(3, ("Request for schannel to incorrect domain: %s != our domain %s\n",
+					  domain, lpcfg_workgroup(gensec_security->settings->lp_ctx)));
+				return NT_STATUS_LOGON_FAILURE;
+			}
+		} else if (bind_schannel.Flags & NL_FLAG_UTF8_DNS_DOMAIN_NAME) {
+			domain = bind_schannel.utf8_dns_domain.u;
+			if (strcasecmp_m(domain, lpcfg_dnsdomain(gensec_security->settings->lp_ctx)) != 0) {
+				DEBUG(3, ("Request for schannel to incorrect domain: %s != our domain %s\n",
+					  domain, lpcfg_dnsdomain(gensec_security->settings->lp_ctx)));
+				return NT_STATUS_LOGON_FAILURE;
+			}
+		} else {
+			DEBUG(3, ("Request for schannel to without domain\n"));
+			return NT_STATUS_LOGON_FAILURE;
+		}
+
+		if (bind_schannel.Flags & NL_FLAG_OEM_NETBIOS_COMPUTER_NAME) {
+			workstation = bind_schannel.oem_netbios_computer.a;
+		} else if (bind_schannel.Flags & NL_FLAG_UTF8_NETBIOS_COMPUTER_NAME) {
+			workstation = bind_schannel.utf8_netbios_computer.u;
+		} else {
+			DEBUG(3, ("Request for schannel to without netbios workstation\n"));
+			return NT_STATUS_LOGON_FAILURE;
+		}
+
+		status = schannel_get_creds_state(out_mem_ctx,
+						  gensec_security->settings->lp_ctx,
+						  workstation, &creds);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(3, ("Could not find session key for attempted schannel connection from %s: %s\n",
+				  workstation, nt_errstr(status)));
+			if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
+				return NT_STATUS_LOGON_FAILURE;
+			}
+			return status;
+		}
+
+		state = netsec_create_state(gensec_security,
+					    creds, false /* not initiator */);
+		if (state == NULL) {
+			return NT_STATUS_NO_MEMORY;
+		}
+
+		status = auth_anonymous_user_info_dc(state,
+				lpcfg_netbios_name(gensec_security->settings->lp_ctx),
+				&state->user_info_dc);
+		if (!NT_STATUS_IS_OK(status)) {
+			return status;
+		}
+
+		bind_schannel_ack.MessageType = NL_NEGOTIATE_RESPONSE;
+		bind_schannel_ack.Flags = 0;
+		bind_schannel_ack.Buffer.dummy = 0x6c0000; /* actually I think
+							    * this does not have
+							    * any meaning here
+							    * - gd */
+
+		ndr_err = ndr_push_struct_blob(out, out_mem_ctx, &bind_schannel_ack,
+					       (ndr_push_flags_fn_t)ndr_push_NL_AUTH_MESSAGE);
+		if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+			status = ndr_map_error2ntstatus(ndr_err);
+			DEBUG(3, ("Could not return schannel bind ack for client %s: %s\n",
+				  workstation, nt_errstr(status)));
+			return status;
+		}
+
+		return NT_STATUS_OK;
+	}
+	return NT_STATUS_INVALID_PARAMETER;
+}
+
+static NTSTATUS schannel_update_recv(struct tevent_req *req,
+				     TALLOC_CTX *out_mem_ctx,
+				     DATA_BLOB *out)
+{
+	struct schannel_update_state *state =
+		tevent_req_data(req,
+		struct schannel_update_state);
+	NTSTATUS status;
+
+	*out = data_blob_null;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		tevent_req_received(req);
+		return status;
+	}
+
+	status = state->status;
+	talloc_steal(out_mem_ctx, state->out.data);
+	*out = state->out;
+	tevent_req_received(req);
+	return status;
+}
+
+/**
+ * Returns anonymous credentials for schannel, matching Win2k3.
+ *
+ */
+
+static NTSTATUS schannel_session_info(struct gensec_security *gensec_security,
+				      TALLOC_CTX *mem_ctx,
+				      struct auth_session_info **_session_info)
+{
+	struct schannel_state *state =
+		talloc_get_type(gensec_security->private_data,
+		struct schannel_state);
+	struct auth4_context *auth_ctx = gensec_security->auth_context;
+	struct auth_session_info *session_info = NULL;
+	uint32_t session_info_flags = 0;
+	NTSTATUS status;
+
+	if (auth_ctx == NULL) {
+		DEBUG(0, ("Cannot generate a session_info without the auth_context\n"));
+		return NT_STATUS_INTERNAL_ERROR;
+	}
+
+	if (auth_ctx->generate_session_info == NULL) {
+		DEBUG(0, ("Cannot generate a session_info without the generate_session_info hook\n"));
+		return NT_STATUS_INTERNAL_ERROR;
+	}
+
+	if (gensec_security->want_features & GENSEC_FEATURE_UNIX_TOKEN) {
+		session_info_flags |= AUTH_SESSION_INFO_UNIX_TOKEN;
+	}
+
+	session_info_flags |= AUTH_SESSION_INFO_SIMPLE_PRIVILEGES;
+
+	status = auth_ctx->generate_session_info(
+				auth_ctx,
+				mem_ctx,
+				state->user_info_dc,
+				state->user_info_dc->info->account_name,
+				session_info_flags,
+				&session_info);
+	if (!NT_STATUS_IS_OK(status)) {
+		return status;
+	}
+
+	*_session_info = session_info;
+	return NT_STATUS_OK;
+}
+
+/*
+ * Reduce the attack surface by ensuring schannel is not available when
+ * we are not a DC
+ */
+static NTSTATUS schannel_server_start(struct gensec_security *gensec_security)
+{
+	enum server_role server_role
+		= lpcfg_server_role(gensec_security->settings->lp_ctx);
+
+	switch (server_role) {
+	case ROLE_DOMAIN_BDC:
+	case ROLE_DOMAIN_PDC:
+	case ROLE_ACTIVE_DIRECTORY_DC:
+	case ROLE_IPA_DC:
+		return NT_STATUS_OK;
+	default:
+		return NT_STATUS_NOT_IMPLEMENTED;
+	}
+}
+
+static NTSTATUS schannel_client_start(struct gensec_security *gensec_security)
+{
+	return NT_STATUS_OK;
+}
+
+static bool schannel_have_feature(struct gensec_security *gensec_security,
+					 uint32_t feature)
+{
+	if (gensec_security->dcerpc_auth_level >= DCERPC_AUTH_LEVEL_INTEGRITY) {
+		if (feature & GENSEC_FEATURE_SIGN) {
+			return true;
+		}
+	}
+	if (gensec_security->dcerpc_auth_level == DCERPC_AUTH_LEVEL_PRIVACY) {
+		if (feature & GENSEC_FEATURE_SEAL) {
+			return true;
+		}
+	}
+	if (feature & GENSEC_FEATURE_DCE_STYLE) {
+		return true;
+	}
+	if (feature & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		return true;
+	}
+	return false;
+}
+
+/*
+  unseal a packet
+*/
+static NTSTATUS schannel_unseal_packet(struct gensec_security *gensec_security,
+				       uint8_t *data, size_t length,
+				       const uint8_t *whole_pdu, size_t pdu_length,
+				       const DATA_BLOB *sig)
+{
+	struct schannel_state *state =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct schannel_state);
+
+	return netsec_incoming_packet(state, true,
+				      discard_const_p(uint8_t, data),
+				      length,
+				      whole_pdu, pdu_length,
+				      sig);
+}
+
+/*
+  check the signature on a packet
+*/
+static NTSTATUS schannel_check_packet(struct gensec_security *gensec_security,
+				      const uint8_t *data, size_t length,
+				      const uint8_t *whole_pdu, size_t pdu_length,
+				      const DATA_BLOB *sig)
+{
+	struct schannel_state *state =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct schannel_state);
+
+	return netsec_incoming_packet(state, false,
+				      discard_const_p(uint8_t, data),
+				      length,
+				      whole_pdu, pdu_length,
+				      sig);
+}
+/*
+  seal a packet
+*/
+static NTSTATUS schannel_seal_packet(struct gensec_security *gensec_security,
+				     TALLOC_CTX *mem_ctx,
+				     uint8_t *data, size_t length,
+				     const uint8_t *whole_pdu, size_t pdu_length,
+				     DATA_BLOB *sig)
+{
+	struct schannel_state *state =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct schannel_state);
+
+	return netsec_outgoing_packet(state, mem_ctx, true,
+				      data, length,
+				      whole_pdu, pdu_length,
+				      sig);
+}
+
+/*
+  sign a packet
+*/
+static NTSTATUS schannel_sign_packet(struct gensec_security *gensec_security,
+				     TALLOC_CTX *mem_ctx,
+				     const uint8_t *data, size_t length,
+				     const uint8_t *whole_pdu, size_t pdu_length,
+				     DATA_BLOB *sig)
+{
+	struct schannel_state *state =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct schannel_state);
+
+	return netsec_outgoing_packet(state, mem_ctx, false,
+				      discard_const_p(uint8_t, data),
+				      length,
+				      whole_pdu, pdu_length,
+				      sig);
+}
+
+static const struct gensec_security_ops gensec_schannel_security_ops = {
+	.name		= "schannel",
+	.auth_type	= DCERPC_AUTH_TYPE_SCHANNEL,
+	.client_start   = schannel_client_start,
+	.server_start   = schannel_server_start,
+	.update_send	= schannel_update_send,
+	.update_recv	= schannel_update_recv,
+	.seal_packet 	= schannel_seal_packet,
+	.sign_packet   	= schannel_sign_packet,
+	.check_packet	= schannel_check_packet,
+	.unseal_packet 	= schannel_unseal_packet,
+	.session_info	= schannel_session_info,
+	.sig_size	= schannel_sig_size,
+	.have_feature   = schannel_have_feature,
+	.enabled        = true,
+	.priority       = GENSEC_SCHANNEL
+};
+
+_PUBLIC_ NTSTATUS gensec_schannel_init(TALLOC_CTX *ctx)
+{
+	NTSTATUS ret;
+	ret = gensec_register(ctx, &gensec_schannel_security_ops);
+	if (!NT_STATUS_IS_OK(ret)) {
+		DEBUG(0,("Failed to register '%s' gensec backend!\n",
+			gensec_schannel_security_ops.name));
+		return ret;
+	}
+
+	return ret;
+}