source: vendor/3.6.0/libcli/auth/schannel_sign.c

Last change on this file was 740, checked in by Silvan Scherrer, 13 years ago

Samba Server: update vendor to 3.6.0
File size: 7.1 KB
Line 
1/*
2 Unix SMB/CIFS implementation.
3
4 schannel library code
5
6 Copyright (C) Andrew Tridgell 2004
7 Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
8
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>.
21*/
22
23#include "includes.h"
24#include "../libcli/auth/schannel.h"
25#include "../lib/crypto/crypto.h"
26
27static void netsec_offset_and_sizes(struct schannel_state *state,
28 bool do_seal,
29 uint32_t *_min_sig_size,
30 uint32_t *_used_sig_size,
31 uint32_t *_checksum_length,
32 uint32_t *_confounder_ofs)
33{
34 uint32_t min_sig_size = 24;
35 uint32_t used_sig_size = 32;
36 uint32_t checksum_length = 8;
37 uint32_t confounder_ofs = 24;
38
39 if (do_seal) {
40 min_sig_size += 8;
41 }
42
43 if (_min_sig_size) {
44 *_min_sig_size = min_sig_size;
45 }
46
47 if (_used_sig_size) {
48 *_used_sig_size = used_sig_size;
49 }
50
51 if (_checksum_length) {
52 *_checksum_length = checksum_length;
53 }
54
55 if (_confounder_ofs) {
56 *_confounder_ofs = confounder_ofs;
57 }
58}
59
60/*******************************************************************
61 Encode or Decode the sequence number (which is symmetric)
62 ********************************************************************/
63static void netsec_do_seq_num(struct schannel_state *state,
64 const uint8_t *checksum,
65 uint32_t checksum_length,
66 uint8_t seq_num[8])
67{
68 static const uint8_t zeros[4];
69 uint8_t sequence_key[16];
70 uint8_t digest1[16];
71
72 hmac_md5(state->creds->session_key, zeros, sizeof(zeros), digest1);
73 hmac_md5(digest1, checksum, checksum_length, sequence_key);
74 arcfour_crypt(seq_num, sequence_key, 8);
75
76 state->seq_num++;
77}
78
79static void netsec_do_seal(struct schannel_state *state,
80 const uint8_t seq_num[8],
81 uint8_t confounder[8],
82 uint8_t *data, uint32_t length)
83{
84 uint8_t sealing_key[16];
85 static const uint8_t zeros[4];
86 uint8_t digest2[16];
87 uint8_t sess_kf0[16];
88 int i;
89
90 for (i = 0; i < 16; i++) {
91 sess_kf0[i] = state->creds->session_key[i] ^ 0xf0;
92 }
93
94 hmac_md5(sess_kf0, zeros, 4, digest2);
95 hmac_md5(digest2, seq_num, 8, sealing_key);
96
97 arcfour_crypt(confounder, sealing_key, 8);
98 arcfour_crypt(data, sealing_key, length);
99}
100
101/*******************************************************************
102 Create a digest over the entire packet (including the data), and
103 MD5 it with the session key.
104 ********************************************************************/
105static void netsec_do_sign(struct schannel_state *state,
106 const uint8_t *confounder,
107 const uint8_t *data, size_t data_len,
108 uint8_t header[8],
109 uint8_t *checksum)
110{
111 uint8_t packet_digest[16];
112 static const uint8_t zeros[4];
113 struct MD5Context ctx;
114
115 MD5Init(&ctx);
116 MD5Update(&ctx, zeros, 4);
117 if (confounder) {
118 SSVAL(header, 0, NL_SIGN_HMAC_MD5);
119 SSVAL(header, 2, NL_SEAL_RC4);
120 SSVAL(header, 4, 0xFFFF);
121 SSVAL(header, 6, 0x0000);
122
123 MD5Update(&ctx, header, 8);
124 MD5Update(&ctx, confounder, 8);
125 } else {
126 SSVAL(header, 0, NL_SIGN_HMAC_MD5);
127 SSVAL(header, 2, NL_SEAL_NONE);
128 SSVAL(header, 4, 0xFFFF);
129 SSVAL(header, 6, 0x0000);
130
131 MD5Update(&ctx, header, 8);
132 }
133 MD5Update(&ctx, data, data_len);
134 MD5Final(packet_digest, &ctx);
135
136 hmac_md5(state->creds->session_key,
137 packet_digest, sizeof(packet_digest),
138 checksum);
139}
140
141NTSTATUS netsec_incoming_packet(struct schannel_state *state,
142 TALLOC_CTX *mem_ctx,
143 bool do_unseal,
144 uint8_t *data, size_t length,
145 const DATA_BLOB *sig)
146{
147 uint32_t min_sig_size = 0;
148 uint8_t header[8];
149 uint8_t checksum[32];
150 uint32_t checksum_length = sizeof(checksum_length);
151 uint8_t _confounder[8];
152 uint8_t *confounder = NULL;
153 uint32_t confounder_ofs = 0;
154 uint8_t seq_num[8];
155 int ret;
156
157 netsec_offset_and_sizes(state,
158 do_unseal,
159 &min_sig_size,
160 NULL,
161 &checksum_length,
162 &confounder_ofs);
163
164 if (sig->length < min_sig_size) {
165 return NT_STATUS_ACCESS_DENIED;
166 }
167
168 if (do_unseal) {
169 confounder = _confounder;
170 memcpy(confounder, sig->data+confounder_ofs, 8);
171 } else {
172 confounder = NULL;
173 }
174
175 RSIVAL(seq_num, 0, state->seq_num);
176 SIVAL(seq_num, 4, state->initiator?0:0x80);
177
178 if (do_unseal) {
179 netsec_do_seal(state, seq_num,
180 confounder,
181 data, length);
182 }
183
184 netsec_do_sign(state, confounder,
185 data, length,
186 header, checksum);
187
188 ret = memcmp(checksum, sig->data+16, checksum_length);
189 if (ret != 0) {
190 dump_data_pw("calc digest:", checksum, checksum_length);
191 dump_data_pw("wire digest:", sig->data+16, checksum_length);
192 return NT_STATUS_ACCESS_DENIED;
193 }
194
195 netsec_do_seq_num(state, checksum, checksum_length, seq_num);
196
197 ret = memcmp(seq_num, sig->data+8, 8);
198 if (ret != 0) {
199 dump_data_pw("calc seq num:", seq_num, 8);
200 dump_data_pw("wire seq num:", sig->data+8, 8);
201 return NT_STATUS_ACCESS_DENIED;
202 }
203
204 return NT_STATUS_OK;
205}
206
207uint32_t netsec_outgoing_sig_size(struct schannel_state *state)
208{
209 uint32_t sig_size = 0;
210
211 netsec_offset_and_sizes(state,
212 true,
213 NULL,
214 &sig_size,
215 NULL,
216 NULL);
217
218 return sig_size;
219}
220
221NTSTATUS netsec_outgoing_packet(struct schannel_state *state,
222 TALLOC_CTX *mem_ctx,
223 bool do_seal,
224 uint8_t *data, size_t length,
225 DATA_BLOB *sig)
226{
227 uint32_t min_sig_size = 0;
228 uint32_t used_sig_size = 0;
229 uint8_t header[8];
230 uint8_t checksum[32];
231 uint32_t checksum_length = sizeof(checksum_length);
232 uint8_t _confounder[8];
233 uint8_t *confounder = NULL;
234 uint32_t confounder_ofs = 0;
235 uint8_t seq_num[8];
236
237 netsec_offset_and_sizes(state,
238 do_seal,
239 &min_sig_size,
240 &used_sig_size,
241 &checksum_length,
242 &confounder_ofs);
243
244 RSIVAL(seq_num, 0, state->seq_num);
245 SIVAL(seq_num, 4, state->initiator?0x80:0);
246
247 if (do_seal) {
248 confounder = _confounder;
249 generate_random_buffer(confounder, 8);
250 } else {
251 confounder = NULL;
252 }
253
254 netsec_do_sign(state, confounder,
255 data, length,
256 header, checksum);
257
258 if (do_seal) {
259 netsec_do_seal(state, seq_num,
260 confounder,
261 data, length);
262 }
263
264 netsec_do_seq_num(state, checksum, checksum_length, seq_num);
265
266 (*sig) = data_blob_talloc_zero(mem_ctx, used_sig_size);
267
268 memcpy(sig->data, header, 8);
269 memcpy(sig->data+8, seq_num, 8);
270 memcpy(sig->data+16, checksum, checksum_length);
271
272 if (confounder) {
273 memcpy(sig->data+confounder_ofs, confounder, 8);
274 }
275
276 dump_data_pw("signature:", sig->data+ 0, 8);
277 dump_data_pw("seq_num :", sig->data+ 8, 8);
278 dump_data_pw("digest :", sig->data+16, checksum_length);
279 dump_data_pw("confound :", sig->data+confounder_ofs, 8);
280
281 return NT_STATUS_OK;
282}
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