Line data Source code
1 : /*
2 : Unix SMB/CIFS implementation.
3 : SMB Signing Code
4 : Copyright (C) Jeremy Allison 2002.
5 : Copyright (C) Andrew Bartlett <abartlet@samba.org> 2002-2003
6 : Copyright (C) James J Myers <myersjj@samba.org> 2003
7 :
8 : This program is free software; you can redistribute it and/or modify
9 : it under the terms of the GNU General Public License as published by
10 : the Free Software Foundation; either version 3 of the License, or
11 : (at your option) any later version.
12 :
13 : This program is distributed in the hope that it will be useful,
14 : but WITHOUT ANY WARRANTY; without even the implied warranty of
15 : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 : GNU General Public License for more details.
17 :
18 : You should have received a copy of the GNU General Public License
19 : along with this program. If not, see <http://www.gnu.org/licenses/>.
20 : */
21 :
22 : #include "includes.h"
23 : #include "libcli/raw/libcliraw.h"
24 : #include "libcli/raw/raw_proto.h"
25 : #include "../lib/crypto/crypto.h"
26 :
27 : #include <gnutls/gnutls.h>
28 : #include <gnutls/crypto.h>
29 :
30 : /***********************************************************
31 : SMB signing - Common code before we set a new signing implementation
32 : ************************************************************/
33 962 : bool set_smb_signing_common(struct smb_signing_context *sign_info)
34 : {
35 962 : if (sign_info->doing_signing) {
36 30 : DEBUG(5, ("SMB Signing already in progress, so we don't start it again\n"));
37 30 : return false;
38 : }
39 :
40 932 : if (!sign_info->allow_smb_signing) {
41 2 : DEBUG(5, ("SMB Signing has been locally disabled\n"));
42 2 : return false;
43 : }
44 :
45 930 : return true;
46 : }
47 :
48 419841 : void mark_packet_signed(struct smb_request_buffer *out)
49 : {
50 0 : uint16_t flags2;
51 419841 : flags2 = SVAL(out->hdr, HDR_FLG2);
52 419841 : flags2 |= FLAGS2_SMB_SECURITY_SIGNATURES;
53 419841 : SSVAL(out->hdr, HDR_FLG2, flags2);
54 419841 : }
55 :
56 419618 : bool signing_good(struct smb_signing_context *sign_info,
57 : unsigned int seq, bool good)
58 : {
59 419618 : if (good) {
60 419522 : if (!sign_info->doing_signing) {
61 834 : DEBUG(5, ("Seen valid packet, so turning signing on\n"));
62 834 : sign_info->doing_signing = true;
63 : }
64 419522 : if (!sign_info->seen_valid) {
65 834 : DEBUG(5, ("Seen valid packet, so marking signing as 'seen valid'\n"));
66 834 : sign_info->seen_valid = true;
67 : }
68 : } else {
69 96 : if (!sign_info->seen_valid) {
70 : /* If we have never seen a good packet, just turn it off */
71 96 : DEBUG(5, ("signing_good: signing negotiated but not required and peer\n"
72 : "isn't sending correct signatures. Turning off.\n"));
73 96 : smbcli_set_signing_off(sign_info);
74 96 : return true;
75 : } else {
76 : /* bad packet after signing started - fail and disconnect. */
77 0 : DEBUG(0, ("signing_good: BAD SIG: seq %u\n", seq));
78 0 : return false;
79 : }
80 : }
81 419522 : return true;
82 : }
83 :
84 419841 : void sign_outgoing_message(struct smb_request_buffer *out, DATA_BLOB *mac_key, unsigned int seq_num)
85 : {
86 0 : uint8_t calc_md5_mac[16];
87 419841 : gnutls_hash_hd_t hash_hnd = NULL;
88 0 : int rc;
89 :
90 : /*
91 : * Firstly put the sequence number into the first 4 bytes.
92 : * and zero out the next 4 bytes.
93 : */
94 419841 : SIVAL(out->hdr, HDR_SS_FIELD, seq_num);
95 419841 : SIVAL(out->hdr, HDR_SS_FIELD + 4, 0);
96 :
97 : /* mark the packet as signed - BEFORE we sign it...*/
98 419841 : mark_packet_signed(out);
99 :
100 : /* Calculate the 16 byte MAC and place first 8 bytes into the field. */
101 419841 : rc = gnutls_hash_init(&hash_hnd, GNUTLS_DIG_MD5);
102 419841 : if (rc < 0) {
103 0 : return;
104 : }
105 :
106 419841 : rc = gnutls_hash(hash_hnd, mac_key->data, mac_key->length);
107 419841 : if (rc < 0) {
108 0 : gnutls_hash_deinit(hash_hnd, NULL);
109 0 : return;
110 : }
111 419841 : rc = gnutls_hash(hash_hnd,
112 419841 : out->buffer + NBT_HDR_SIZE,
113 419841 : out->size - NBT_HDR_SIZE);
114 419841 : if (rc < 0) {
115 0 : gnutls_hash_deinit(hash_hnd, NULL);
116 0 : return;
117 : }
118 419841 : gnutls_hash_deinit(hash_hnd, calc_md5_mac);
119 :
120 419841 : memcpy(&out->hdr[HDR_SS_FIELD], calc_md5_mac, 8);
121 :
122 419841 : DEBUG(5, ("sign_outgoing_message: SENT SIG (seq: %d): sent SMB signature of\n",
123 : seq_num));
124 419841 : dump_data(5, calc_md5_mac, 8);
125 419841 : ZERO_ARRAY(calc_md5_mac);
126 : /* req->out.hdr[HDR_SS_FIELD+2]=0;
127 : Uncomment this to test if the remote server actually verifies signitures...*/
128 : }
129 :
130 419618 : bool check_signed_incoming_message(struct smb_request_buffer *in, DATA_BLOB *mac_key, unsigned int seq_num)
131 : {
132 419618 : bool ok = false;
133 0 : uint8_t calc_md5_mac[16];
134 0 : uint8_t *server_sent_mac;
135 0 : uint8_t sequence_buf[8];
136 0 : gnutls_hash_hd_t hash_hnd;
137 419618 : const size_t offset_end_of_sig = (HDR_SS_FIELD + 8);
138 0 : int rc;
139 0 : int i;
140 419618 : const int sign_range = 0;
141 :
142 : /* room enough for the signature? */
143 419618 : if (in->size < NBT_HDR_SIZE + HDR_SS_FIELD + 8) {
144 0 : return false;
145 : }
146 :
147 419618 : if (!mac_key->length) {
148 : /* NO key yet */
149 0 : return false;
150 : }
151 :
152 : /* its quite bogus to be guessing sequence numbers, but very useful
153 : when debugging signing implementations */
154 419714 : for (i = 0-sign_range; i <= 0+sign_range; i++) {
155 : /*
156 : * Firstly put the sequence number into the first 4 bytes.
157 : * and zero out the next 4 bytes.
158 : */
159 419618 : SIVAL(sequence_buf, 0, seq_num + i);
160 419618 : SIVAL(sequence_buf, 4, 0);
161 :
162 : /* get a copy of the server-sent mac */
163 419618 : server_sent_mac = &in->hdr[HDR_SS_FIELD];
164 :
165 : /* Calculate the 16 byte MAC and place first 8 bytes into the field. */
166 419618 : rc = gnutls_hash_init(&hash_hnd, GNUTLS_DIG_MD5);
167 419618 : if (rc < 0) {
168 0 : ok = false;
169 0 : goto out;
170 : }
171 :
172 419618 : rc = gnutls_hash(hash_hnd, mac_key->data, mac_key->length);
173 419618 : if (rc < 0) {
174 0 : gnutls_hash_deinit(hash_hnd, NULL);
175 0 : ok = false;
176 0 : goto out;
177 : }
178 419618 : rc = gnutls_hash(hash_hnd, in->hdr, HDR_SS_FIELD);
179 419618 : if (rc < 0) {
180 0 : gnutls_hash_deinit(hash_hnd, NULL);
181 0 : ok = false;
182 0 : goto out;
183 : }
184 419618 : rc = gnutls_hash(hash_hnd, sequence_buf, sizeof(sequence_buf));
185 419618 : if (rc < 0) {
186 0 : gnutls_hash_deinit(hash_hnd, NULL);
187 0 : ok = false;
188 0 : goto out;
189 : }
190 419618 : rc = gnutls_hash(hash_hnd,
191 419618 : in->hdr + offset_end_of_sig,
192 419618 : in->size - NBT_HDR_SIZE - (offset_end_of_sig));
193 419618 : if (rc < 0) {
194 0 : gnutls_hash_deinit(hash_hnd, NULL);
195 0 : ok = false;
196 0 : goto out;
197 : }
198 :
199 419618 : gnutls_hash_deinit(hash_hnd, calc_md5_mac);
200 :
201 419618 : ok = mem_equal_const_time(server_sent_mac, calc_md5_mac, 8);
202 :
203 419618 : if (i == 0) {
204 419618 : if (!ok) {
205 96 : DEBUG(5, ("check_signed_incoming_message: BAD SIG (seq: %d): wanted SMB signature of\n", seq_num + i));
206 96 : dump_data(5, calc_md5_mac, 8);
207 :
208 96 : DEBUG(5, ("check_signed_incoming_message: BAD SIG (seq: %d): got SMB signature of\n", seq_num + i));
209 96 : dump_data(5, server_sent_mac, 8);
210 : } else {
211 419522 : DEBUG(15, ("check_signed_incoming_message: GOOD SIG (seq: %d): got SMB signature of\n", seq_num + i));
212 419522 : dump_data(5, server_sent_mac, 8);
213 : }
214 : }
215 419618 : ZERO_ARRAY(calc_md5_mac);
216 :
217 419618 : if (ok) break;
218 : }
219 :
220 419618 : if (ok && i != 0) {
221 0 : DEBUG(0,("SIGNING OFFSET %d (should be %d)\n", i, seq_num));
222 : }
223 :
224 419618 : out:
225 419618 : return ok;
226 : }
227 :
228 : /**
229 : SMB signing - NULL implementation
230 :
231 : @note Used as an initialisation only - it will not correctly
232 : shut down a real signing mechanism
233 : */
234 2261 : bool smbcli_set_signing_off(struct smb_signing_context *sign_info)
235 : {
236 2261 : DEBUG(5, ("Shutdown SMB signing\n"));
237 2261 : sign_info->doing_signing = false;
238 2261 : data_blob_free(&sign_info->mac_key);
239 2261 : sign_info->signing_state = SMB_SIGNING_ENGINE_OFF;
240 2261 : return true;
241 : }
242 :
243 : /***********************************************************
244 : SMB signing - Simple implementation - setup the MAC key.
245 : ************************************************************/
246 930 : bool smbcli_simple_set_signing(TALLOC_CTX *mem_ctx,
247 : struct smb_signing_context *sign_info,
248 : const DATA_BLOB *user_session_key,
249 : const DATA_BLOB *response)
250 : {
251 930 : if (sign_info->mandatory_signing) {
252 838 : DEBUG(5, ("Mandatory SMB signing enabled!\n"));
253 : }
254 :
255 930 : DEBUG(5, ("SMB signing enabled!\n"));
256 :
257 930 : if (response && response->length) {
258 7 : sign_info->mac_key = data_blob_talloc(mem_ctx, NULL, response->length + user_session_key->length);
259 : } else {
260 923 : sign_info->mac_key = data_blob_talloc(mem_ctx, NULL, user_session_key->length);
261 : }
262 :
263 930 : memcpy(&sign_info->mac_key.data[0], user_session_key->data, user_session_key->length);
264 :
265 930 : if (response && response->length) {
266 7 : memcpy(&sign_info->mac_key.data[user_session_key->length],response->data, response->length);
267 : }
268 :
269 930 : dump_data_pw("Started Signing with key:\n", sign_info->mac_key.data, sign_info->mac_key.length);
270 :
271 930 : sign_info->signing_state = SMB_SIGNING_ENGINE_ON;
272 930 : sign_info->next_seq_num = 2;
273 :
274 930 : return true;
275 : }
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