schannel: move schannel_sign to main directory.

Guenther

1 files changed, 271 insertions, 0 deletions

diff --git a/libcli/auth/schannel_sign.c b/libcli/auth/schannel_sign.c
new file mode 100644
index 0000000000..45f3989e11
--- /dev/null
+++ b/libcli/auth/schannel_sign.c
@@ -0,0 +1,271 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   schannel library code
+
+   Copyright (C) Andrew Tridgell 2004
+   Copyright (C) Andrew Bartlett <abartlet@samba.org> 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 "../libcli/auth/schannel.h"
+#include "../lib/crypto/crypto.h"
+#include "auth/gensec/gensec.h"
+#include "auth/gensec/gensec_proto.h"
+
+#define NETSEC_SIGN_SIGNATURE { 0x77, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00 }
+#define NETSEC_SEAL_SIGNATURE { 0x77, 0x00, 0x7a, 0x00, 0xff, 0xff, 0x00, 0x00 }
+
+/*******************************************************************
+ Encode or Decode the sequence number (which is symmetric)
+ ********************************************************************/
+static void netsec_deal_with_seq_num(struct schannel_state *state,
+				     const uint8_t packet_digest[8],
+				     uint8_t seq_num[8])
+{
+	static const uint8_t zeros[4];
+	uint8_t sequence_key[16];
+	uint8_t digest1[16];
+
+	hmac_md5(state->creds->session_key, zeros, sizeof(zeros), digest1);
+	hmac_md5(digest1, packet_digest, 8, sequence_key);
+	arcfour_crypt(seq_num, sequence_key, 8);
+
+	state->seq_num++;
+}
+
+
+/*******************************************************************
+ Calculate the key with which to encode the data payload
+ ********************************************************************/
+static void netsec_get_sealing_key(const uint8_t session_key[16],
+				   const uint8_t seq_num[8],
+				   uint8_t sealing_key[16])
+{
+	static const uint8_t zeros[4];
+	uint8_t digest2[16];
+	uint8_t sess_kf0[16];
+	int i;
+
+	for (i = 0; i < 16; i++) {
+		sess_kf0[i] = session_key[i] ^ 0xf0;
+	}
+
+	hmac_md5(sess_kf0, zeros, 4, digest2);
+	hmac_md5(digest2, seq_num, 8, sealing_key);
+}
+
+
+/*******************************************************************
+ Create a digest over the entire packet (including the data), and
+ MD5 it with the session key.
+ ********************************************************************/
+static void schannel_digest(const uint8_t sess_key[16],
+			    const uint8_t netsec_sig[8],
+			    const uint8_t *confounder,
+			    const uint8_t *data, size_t data_len,
+			    uint8_t digest_final[16])
+{
+	uint8_t packet_digest[16];
+	static const uint8_t zeros[4];
+	struct MD5Context ctx;
+
+	MD5Init(&ctx);
+	MD5Update(&ctx, zeros, 4);
+	MD5Update(&ctx, netsec_sig, 8);
+	if (confounder) {
+		MD5Update(&ctx, confounder, 8);
+	}
+	MD5Update(&ctx, data, data_len);
+	MD5Final(packet_digest, &ctx);
+
+	hmac_md5(sess_key, packet_digest, sizeof(packet_digest), digest_final);
+}
+
+
+/*
+  unseal a packet
+*/
+NTSTATUS schannel_unseal_packet(struct schannel_state *state,
+				TALLOC_CTX *mem_ctx,
+				uint8_t *data, size_t length,
+				const DATA_BLOB *sig)
+{
+	uint8_t digest_final[16];
+	uint8_t confounder[8];
+	uint8_t seq_num[8];
+	uint8_t sealing_key[16];
+	static const uint8_t netsec_sig[8] = NETSEC_SEAL_SIGNATURE;
+
+	if (sig->length != 32) {
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	memcpy(confounder, sig->data+24, 8);
+
+	RSIVAL(seq_num, 0, state->seq_num);
+	SIVAL(seq_num, 4, state->initiator?0:0x80);
+
+	netsec_get_sealing_key(state->creds->session_key, seq_num, sealing_key);
+	arcfour_crypt(confounder, sealing_key, 8);
+	arcfour_crypt(data, sealing_key, length);
+
+	schannel_digest(state->creds->session_key,
+			netsec_sig, confounder,
+			data, length, digest_final);
+
+	if (memcmp(digest_final, sig->data+16, 8) != 0) {
+		dump_data_pw("calc digest:", digest_final, 8);
+		dump_data_pw("wire digest:", sig->data+16, 8);
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	netsec_deal_with_seq_num(state, digest_final, seq_num);
+
+	if (memcmp(seq_num, sig->data+8, 8) != 0) {
+		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;
+}
+
+/*
+  check the signature on a packet
+*/
+NTSTATUS schannel_check_packet(struct schannel_state *state,
+			       TALLOC_CTX *mem_ctx,
+			       const uint8_t *data, size_t length,
+			       const DATA_BLOB *sig)
+{
+	uint8_t digest_final[16];
+	uint8_t seq_num[8];
+	static const uint8_t netsec_sig[8] = NETSEC_SIGN_SIGNATURE;
+
+	/* w2k sends just 24 bytes and skip the confounder */
+	if (sig->length != 32 && sig->length != 24) {
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	RSIVAL(seq_num, 0, state->seq_num);
+	SIVAL(seq_num, 4, state->initiator?0:0x80);
+
+	dump_data_pw("seq_num:\n", seq_num, 8);
+	dump_data_pw("sess_key:\n", state->creds->session_key, 16);
+
+	schannel_digest(state->creds->session_key,
+			netsec_sig, NULL,
+			data, length, digest_final);
+
+	netsec_deal_with_seq_num(state, digest_final, seq_num);
+
+	if (memcmp(seq_num, sig->data+8, 8) != 0) {
+		dump_data_pw("calc seq num:", seq_num, 8);
+		dump_data_pw("wire seq num:", sig->data+8, 8);
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	if (memcmp(digest_final, sig->data+16, 8) != 0) {
+		dump_data_pw("calc digest:", digest_final, 8);
+		dump_data_pw("wire digest:", sig->data+16, 8);
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	return NT_STATUS_OK;
+}
+
+
+/*
+  seal a packet
+*/
+NTSTATUS schannel_seal_packet(struct schannel_state *state,
+			      TALLOC_CTX *mem_ctx,
+			      uint8_t *data, size_t length,
+			      DATA_BLOB *sig)
+{
+	uint8_t digest_final[16];
+	uint8_t confounder[8];
+	uint8_t seq_num[8];
+	uint8_t sealing_key[16];
+	static const uint8_t netsec_sig[8] = NETSEC_SEAL_SIGNATURE;
+
+	generate_random_buffer(confounder, 8);
+
+	RSIVAL(seq_num, 0, state->seq_num);
+	SIVAL(seq_num, 4, state->initiator?0x80:0);
+
+	schannel_digest(state->creds->session_key,
+			netsec_sig, confounder,
+			data, length, digest_final);
+
+	netsec_get_sealing_key(state->creds->session_key, seq_num, sealing_key);
+	arcfour_crypt(confounder, sealing_key, 8);
+	arcfour_crypt(data, sealing_key, length);
+
+	netsec_deal_with_seq_num(state, digest_final, seq_num);
+
+	(*sig) = data_blob_talloc(mem_ctx, NULL, 32);
+
+	memcpy(sig->data, netsec_sig, 8);
+	memcpy(sig->data+8, seq_num, 8);
+	memcpy(sig->data+16, digest_final, 8);
+	memcpy(sig->data+24, 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, 8);
+	dump_data_pw("confound :", sig->data+24, 8);
+
+	return NT_STATUS_OK;
+}
+
+
+/*
+  sign a packet
+*/
+NTSTATUS schannel_sign_packet(struct schannel_state *state,
+			      TALLOC_CTX *mem_ctx,
+			      const uint8_t *data, size_t length,
+			      DATA_BLOB *sig)
+{
+	uint8_t digest_final[16];
+	uint8_t seq_num[8];
+	static const uint8_t netsec_sig[8] = NETSEC_SIGN_SIGNATURE;
+
+	RSIVAL(seq_num, 0, state->seq_num);
+	SIVAL(seq_num, 4, state->initiator?0x80:0);
+
+	schannel_digest(state->creds->session_key,
+			netsec_sig, NULL,
+			data, length, digest_final);
+
+	netsec_deal_with_seq_num(state, digest_final, seq_num);
+
+	(*sig) = data_blob_talloc(mem_ctx, NULL, 32);
+
+	memcpy(sig->data, netsec_sig, 8);
+	memcpy(sig->data+8, seq_num, 8);
+	memcpy(sig->data+16, digest_final, 8);
+	memset(sig->data+24, 0, 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, 8);
+	dump_data_pw("confound :", sig->data+24, 8);
+
+	return NT_STATUS_OK;
+}