summaryrefslogtreecommitdiffstats
path: root/fs/cifs/cifsencrypt.c
blob: 35042d8f733865c77b31ee8d10dd097d4f0a16d8 (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
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
/*
 *   fs/cifs/cifsencrypt.c
 *
 *   Copyright (C) International Business Machines  Corp., 2005,2006
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifs_debug.h"
#include "md5.h"
#include "cifs_unicode.h"
#include "cifsproto.h"
#include <linux/ctype.h>
#include <linux/random.h>

/* Calculate and return the CIFS signature based on the mac key and SMB PDU */
/* the 16 byte signature must be allocated by the caller  */
/* Note we only use the 1st eight bytes */
/* Note that the smb header signature field on input contains the
	sequence number before this function is called */

extern void mdfour(unsigned char *out, unsigned char *in, int n);
extern void E_md4hash(const unsigned char *passwd, unsigned char *p16);
extern void SMBencrypt(unsigned char *passwd, const unsigned char *c8,
		       unsigned char *p24);

static int cifs_calculate_signature(const struct smb_hdr *cifs_pdu,
				    const struct mac_key *key, char *signature)
{
	struct	MD5Context context;

	if ((cifs_pdu == NULL) || (signature == NULL) || (key == NULL))
		return -EINVAL;

	cifs_MD5_init(&context);
	cifs_MD5_update(&context, (char *)&key->data, key->len);
	cifs_MD5_update(&context, cifs_pdu->Protocol, cifs_pdu->smb_buf_length);

	cifs_MD5_final(signature, &context);
	return 0;
}

int cifs_sign_smb(struct smb_hdr *cifs_pdu, struct TCP_Server_Info *server,
		  __u32 *pexpected_response_sequence_number)
{
	int rc = 0;
	char smb_signature[20];

	if ((cifs_pdu == NULL) || (server == NULL))
		return -EINVAL;

	if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
		return rc;

	spin_lock(&GlobalMid_Lock);
	cifs_pdu->Signature.Sequence.SequenceNumber =
			cpu_to_le32(server->sequence_number);
	cifs_pdu->Signature.Sequence.Reserved = 0;

	*pexpected_response_sequence_number = server->sequence_number++;
	server->sequence_number++;
	spin_unlock(&GlobalMid_Lock);

	rc = cifs_calculate_signature(cifs_pdu, &server->mac_signing_key,
				      smb_signature);
	if (rc)
		memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
	else
		memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);

	return rc;
}

static int cifs_calc_signature2(const struct kvec *iov, int n_vec,
				const struct mac_key *key, char *signature)
{
	struct  MD5Context context;
	int i;

	if ((iov == NULL) || (signature == NULL) || (key == NULL))
		return -EINVAL;

	cifs_MD5_init(&context);
	cifs_MD5_update(&context, (char *)&key->data, key->len);
	for (i = 0; i < n_vec; i++) {
		if (iov[i].iov_len == 0)
			continue;
		if (iov[i].iov_base == NULL) {
			cERROR(1, "null iovec entry");
			return -EIO;
		}
		/* The first entry includes a length field (which does not get
		   signed that occupies the first 4 bytes before the header */
		if (i == 0) {
			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
				break; /* nothing to sign or corrupt header */
			cifs_MD5_update(&context, iov[0].iov_base+4,
				  iov[0].iov_len-4);
		} else
			cifs_MD5_update(&context, iov[i].iov_base, iov[i].iov_len);
	}

	cifs_MD5_final(signature, &context);

	return 0;
}


int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
		   __u32 *pexpected_response_sequence_number)
{
	int rc = 0;
	char smb_signature[20];
	struct smb_hdr *cifs_pdu = iov[0].iov_base;

	if ((cifs_pdu == NULL) || (server == NULL))
		return -EINVAL;

	if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
		return rc;

	spin_lock(&GlobalMid_Lock);
	cifs_pdu->Signature.Sequence.SequenceNumber =
				cpu_to_le32(server->sequence_number);
	cifs_pdu->Signature.Sequence.Reserved = 0;

	*pexpected_response_sequence_number = server->sequence_number++;
	server->sequence_number++;
	spin_unlock(&GlobalMid_Lock);

	rc = cifs_calc_signature2(iov, n_vec, &server->mac_signing_key,
				      smb_signature);
	if (rc)
		memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
	else
		memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);

	return rc;
}

int cifs_verify_signature(struct smb_hdr *cifs_pdu,
			  const struct mac_key *mac_key,
			  __u32 expected_sequence_number)
{
	unsigned int rc;
	char server_response_sig[8];
	char what_we_think_sig_should_be[20];

	if ((cifs_pdu == NULL) || (mac_key == NULL))
		return -EINVAL;

	if (cifs_pdu->Command == SMB_COM_NEGOTIATE)
		return 0;

	if (cifs_pdu->Command == SMB_COM_LOCKING_ANDX) {
		struct smb_com_lock_req *pSMB =
			(struct smb_com_lock_req *)cifs_pdu;
	    if (pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE)
			return 0;
	}

	/* BB what if signatures are supposed to be on for session but
	   server does not send one? BB */

	/* Do not need to verify session setups with signature "BSRSPYL "  */
	if (memcmp(cifs_pdu->Signature.SecuritySignature, "BSRSPYL ", 8) == 0)
		cFYI(1, "dummy signature received for smb command 0x%x",
			cifs_pdu->Command);

	/* save off the origiginal signature so we can modify the smb and check
		its signature against what the server sent */
	memcpy(server_response_sig, cifs_pdu->Signature.SecuritySignature, 8);

	cifs_pdu->Signature.Sequence.SequenceNumber =
					cpu_to_le32(expected_sequence_number);
	cifs_pdu->Signature.Sequence.Reserved = 0;

	rc = cifs_calculate_signature(cifs_pdu, mac_key,
		what_we_think_sig_should_be);

	if (rc)
		return rc;

/*	cifs_dump_mem("what we think it should be: ",
		      what_we_think_sig_should_be, 16); */

	if (memcmp(server_response_sig, what_we_think_sig_should_be, 8))
		return -EACCES;
	else
		return 0;

}

/* We fill in key by putting in 40 byte array which was allocated by caller */
int cifs_calculate_mac_key(struct mac_key *key, const char *rn,
			   const char *password)
{
	char temp_key[16];
	if ((key == NULL) || (rn == NULL))
		return -EINVAL;

	E_md4hash(password, temp_key);
	mdfour(key->data.ntlm, temp_key, 16);
	memcpy(key->data.ntlm+16, rn, CIFS_SESS_KEY_SIZE);
	key->len = 40;
	return 0;
}

#ifdef CONFIG_CIFS_WEAK_PW_HASH
void calc_lanman_hash(const char *password, const char *cryptkey, bool encrypt,
			char *lnm_session_key)
{
	int i;
	char password_with_pad[CIFS_ENCPWD_SIZE];

	memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
	if (password)
		strncpy(password_with_pad, password, CIFS_ENCPWD_SIZE);

	if (!encrypt && global_secflags & CIFSSEC_MAY_PLNTXT) {
		memset(lnm_session_key, 0, CIFS_SESS_KEY_SIZE);
		memcpy(lnm_session_key, password_with_pad,
			CIFS_ENCPWD_SIZE);
		return;
	}

	/* calculate old style session key */
	/* calling toupper is less broken than repeatedly
	calling nls_toupper would be since that will never
	work for UTF8, but neither handles multibyte code pages
	but the only alternative would be converting to UCS-16 (Unicode)
	(using a routine something like UniStrupr) then
	uppercasing and then converting back from Unicode - which
	would only worth doing it if we knew it were utf8. Basically
	utf8 and other multibyte codepages each need their own strupper
	function since a byte at a time will ont work. */

	for (i = 0; i < CIFS_ENCPWD_SIZE; i++)
		password_with_pad[i] = toupper(password_with_pad[i]);

	SMBencrypt(password_with_pad, cryptkey, lnm_session_key);

	/* clear password before we return/free memory */
	memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
}
#endif /* CIFS_WEAK_PW_HASH */

static int calc_ntlmv2_hash(struct cifsSesInfo *ses,
			    const struct nls_table *nls_cp)
{
	int rc = 0;
	int len;
	char nt_hash[16];
	struct HMACMD5Context *pctxt;
	wchar_t *user;
	wchar_t *domain;

	pctxt = kmalloc(sizeof(struct HMACMD5Context), GFP_KERNEL);

	if (pctxt == NULL)
		return -ENOMEM;

	/* calculate md4 hash of password */
	E_md4hash(ses->password, nt_hash);

	/* convert Domainname to unicode and uppercase */
	hmac_md5_init_limK_to_64(nt_hash, 16, pctxt);

	/* convert ses->userName to unicode and uppercase */
	len = strlen(ses->userName);
	user = kmalloc(2 + (len * 2), GFP_KERNEL);
	if (user == NULL)
		goto calc_exit_2;
	len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
	UniStrupr(user);
	hmac_md5_update((char *)user, 2*len, pctxt);

	/* convert ses->domainName to unicode and uppercase */
	if (ses->domainName) {
		len = strlen(ses->domainName);

		domain = kmalloc(2 + (len * 2), GFP_KERNEL);
		if (domain == NULL)
			goto calc_exit_1;
		len = cifs_strtoUCS((__le16 *)domain, ses->domainName, len,
					nls_cp);
		/* the following line was removed since it didn't work well
		   with lower cased domain name that passed as an option.
		   Maybe converting the domain name earlier makes sense */
		/* UniStrupr(domain); */

		hmac_md5_update((char *)domain, 2*len, pctxt);

		kfree(domain);
	}
calc_exit_1:
	kfree(user);
calc_exit_2:
	/* BB FIXME what about bytes 24 through 40 of the signing key?
	   compare with the NTLM example */
	hmac_md5_final(ses->server->ntlmv2_hash, pctxt);

	kfree(pctxt);
	return rc;
}

void setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
		      const struct nls_table *nls_cp)
{
	int rc;
	struct ntlmv2_resp *buf = (struct ntlmv2_resp *)resp_buf;
	struct HMACMD5Context context;

	buf->blob_signature = cpu_to_le32(0x00000101);
	buf->reserved = 0;
	buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
	get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
	buf->reserved2 = 0;
	buf->names[0].type = cpu_to_le16(NTLMSSP_DOMAIN_TYPE);
	buf->names[0].length = 0;
	buf->names[1].type = 0;
	buf->names[1].length = 0;

	/* calculate buf->ntlmv2_hash */
	rc = calc_ntlmv2_hash(ses, nls_cp);
	if (rc)
		cERROR(1, "could not get v2 hash rc %d", rc);
	CalcNTLMv2_response(ses, resp_buf);

	/* now calculate the MAC key for NTLMv2 */
	hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);
	hmac_md5_update(resp_buf, 16, &context);
	hmac_md5_final(ses->server->mac_signing_key.data.ntlmv2.key, &context);

	memcpy(&ses->server->mac_signing_key.data.ntlmv2.resp, resp_buf,
	       sizeof(struct ntlmv2_resp));
	ses->server->mac_signing_key.len = 16 + sizeof(struct ntlmv2_resp);
}

void CalcNTLMv2_response(const struct cifsSesInfo *ses,
			 char *v2_session_response)
{
	struct HMACMD5Context context;
	/* rest of v2 struct already generated */
	memcpy(v2_session_response + 8, ses->server->cryptKey, 8);
	hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);

	hmac_md5_update(v2_session_response+8,
			sizeof(struct ntlmv2_resp) - 8, &context);

	hmac_md5_final(v2_session_response, &context);
/*	cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); */
}