aboutsummaryrefslogtreecommitdiffstats
path: root/source3/smbd/signing.c
blob: f4a8d2a2fdaf62fe97ebe5a89a4638b5b39f6cf5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
/*
   Unix SMB/CIFS implementation.
   SMB Signing Code
   Copyright (C) Jeremy Allison 2003.
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2002-2003
   Copyright (C) Stefan Metzmacher 2009

   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 "smbd/smbd.h"
#include "smbd/globals.h"
#include "../libcli/smb/smb_signing.h"

/***********************************************************
 Called to validate an incoming packet from the client.
************************************************************/

bool srv_check_sign_mac(struct smbd_server_connection *conn,
			const char *inbuf, uint32_t *seqnum,
			bool trusted_channel)
{
	/* Check if it's a non-session message. */
	if(CVAL(inbuf,0)) {
		return true;
	}

	if (trusted_channel) {
		NTSTATUS status;

		if (smb_len(inbuf) < (smb_ss_field + 8 - 4)) {
			DEBUG(1,("smb_signing_check_pdu: Can't check signature "
				 "on short packet! smb_len = %u\n",
				 smb_len(inbuf)));
			return false;
		}

		status = NT_STATUS(IVAL(inbuf, smb_ss_field + 4));
		if (!NT_STATUS_IS_OK(status)) {
			DEBUG(1,("smb_signing_check_pdu: trusted channel passed %s\n",
				 nt_errstr(status)));
			return false;
		}

		*seqnum = IVAL(inbuf, smb_ss_field);
		return true;
	}

	*seqnum = smb_signing_next_seqnum(conn->smb1.signing_state, false);
	return smb_signing_check_pdu(conn->smb1.signing_state,
				     (const uint8_t *)inbuf,
				     *seqnum);
}

/***********************************************************
 Called to sign an outgoing packet to the client.
************************************************************/

void srv_calculate_sign_mac(struct smbd_server_connection *conn,
			    char *outbuf, uint32_t seqnum)
{
	/* Check if it's a non-session message. */
	if(CVAL(outbuf,0)) {
		return;
	}

	smb_signing_sign_pdu(conn->smb1.signing_state, (uint8_t *)outbuf, seqnum);
}


/***********************************************************
 Called to indicate a oneway request
************************************************************/
void srv_cancel_sign_response(struct smbd_server_connection *conn)
{
	smb_signing_cancel_reply(conn->smb1.signing_state, true);
}

struct smbd_shm_signing {
	size_t shm_size;
	uint8_t *shm_pointer;

	/* we know the signing engine will only allocate 2 chunks */
	uint8_t *ptr1;
	size_t len1;
	uint8_t *ptr2;
	size_t len2;
};

static int smbd_shm_signing_destructor(struct smbd_shm_signing *s)
{
	anonymous_shared_free(s->shm_pointer);
	return 0;
}

static void *smbd_shm_signing_alloc(TALLOC_CTX *mem_ctx, size_t len)
{
	struct smbd_shm_signing *s = talloc_get_type_abort(mem_ctx,
				     struct smbd_shm_signing);

	if (s->ptr1 == NULL) {
		s->len1 = len;
		if (len % 8) {
			s->len1 += (8 - (len % 8));
		}
		if (s->len1 > s->shm_size) {
			s->len1 = 0;
			errno = ENOMEM;
			return NULL;
		}
		s->ptr1 = s->shm_pointer;
		return s->ptr1;
	}

	if (s->ptr2 == NULL) {
		s->len2 = len;
		if (s->len2 > (s->shm_size - s->len1)) {
			s->len2 = 0;
			errno = ENOMEM;
			return NULL;
		}
		s->ptr2 = s->shm_pointer + s->len1;
		return s->ptr2;
	}

	errno = ENOMEM;
	return NULL;
}

static void smbd_shm_signing_free(TALLOC_CTX *mem_ctx, void *ptr)
{
	struct smbd_shm_signing *s = talloc_get_type_abort(mem_ctx,
				     struct smbd_shm_signing);

	if (s->ptr2 == ptr) {
		s->ptr2 = NULL;
		s->len2 = 0;
	}
}

/***********************************************************
 Called by server negprot when signing has been negotiated.
************************************************************/

bool srv_init_signing(struct smbd_server_connection *conn)
{
	bool allowed = true;
	bool desired;
	bool mandatory = false;

	switch (lp_server_signing()) {
	case SMB_SIGNING_REQUIRED:
		mandatory = true;
		break;
	case SMB_SIGNING_IF_REQUIRED:
		break;
	case SMB_SIGNING_DEFAULT:
	case SMB_SIGNING_OFF:
		allowed = false;
		break;
	}

	/*
	 * if the client and server allow signing,
	 * we desire to use it.
	 *
	 * This matches Windows behavior and is needed
	 * because not every client that requires signing
	 * sends FLAGS2_SMB_SECURITY_SIGNATURES_REQUIRED.
	 */
	desired = allowed;

	if (lp_async_smb_echo_handler()) {
		struct smbd_shm_signing *s;

		/* setup the signing state in shared memory */
		s = talloc_zero(conn, struct smbd_shm_signing);
		if (s == NULL) {
			return false;
		}
		s->shm_size = 4096;
		s->shm_pointer =
			(uint8_t *)anonymous_shared_allocate(s->shm_size);
		if (s->shm_pointer == NULL) {
			talloc_free(s);
			return false;
		}
		talloc_set_destructor(s, smbd_shm_signing_destructor);
		conn->smb1.signing_state = smb_signing_init_ex(s,
							allowed, desired, mandatory,
							smbd_shm_signing_alloc,
							smbd_shm_signing_free);
		if (!conn->smb1.signing_state) {
			return false;
		}
		return true;
	}

	conn->smb1.signing_state = smb_signing_init(conn,
						    allowed, desired, mandatory);
	if (!conn->smb1.signing_state) {
		return false;
	}

	return true;
}

void srv_set_signing_negotiated(struct smbd_server_connection *conn,
				bool allowed, bool mandatory)
{
	smb_signing_set_negotiated(conn->smb1.signing_state,
				   allowed, mandatory);
}

/***********************************************************
 Returns whether signing is active. We can't use sendfile or raw
 reads/writes if it is.
************************************************************/

bool srv_is_signing_active(struct smbd_server_connection *conn)
{
	return smb_signing_is_active(conn->smb1.signing_state);
}


/***********************************************************
 Returns whether signing is negotiated. We can't use it unless it was
 in the negprot.
************************************************************/

bool srv_is_signing_negotiated(struct smbd_server_connection *conn)
{
	return smb_signing_is_negotiated(conn->smb1.signing_state);
}

/***********************************************************
 Turn on signing from this packet onwards.
************************************************************/

void srv_set_signing(struct smbd_server_connection *conn,
		     const DATA_BLOB user_session_key,
		     const DATA_BLOB response)
{
	bool negotiated;
	bool mandatory;

	if (!user_session_key.length)
		return;

	negotiated = smb_signing_is_negotiated(conn->smb1.signing_state);
	mandatory = smb_signing_is_mandatory(conn->smb1.signing_state);

	if (!negotiated && !mandatory) {
		DEBUG(5,("srv_set_signing: signing negotiated = %u, "
			 "mandatory_signing = %u. Not allowing smb signing.\n",
			 negotiated, mandatory));
		return;
	}

	if (!smb_signing_activate(conn->smb1.signing_state,
				  user_session_key, response)) {
		return;
	}

	DEBUG(3,("srv_set_signing: turning on SMB signing: "
		 "signing negotiated = %u, mandatory_signing = %u.\n",
		 negotiated, mandatory));
}