diff options
Diffstat (limited to 'source4/auth/gensec/schannel_sign.c')
| -rw-r--r-- | source4/auth/gensec/schannel_sign.c | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/source4/auth/gensec/schannel_sign.c b/source4/auth/gensec/schannel_sign.c new file mode 100644 index 0000000000..493b26f6c0 --- /dev/null +++ b/source4/auth/gensec/schannel_sign.c @@ -0,0 +1,283 @@ +/* + 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 2 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, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +*/ + +#include "includes.h" +#include "lib/crypto/crypto.h" +#include "auth/auth.h" +#include "auth/gensec/schannel.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 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 = gensec_security->private_data; + + 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 gensec_security *gensec_security, + TALLOC_CTX *mem_ctx, + const uint8_t *data, size_t length, + const uint8_t *whole_pdu, size_t pdu_length, + const DATA_BLOB *sig) +{ + struct schannel_state *state = gensec_security->private_data; + + 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 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 = gensec_security->private_data; + + 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 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 = gensec_security->private_data; + + 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; +} |