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1 /*
2  *   fs/cifs/cifsencrypt.c
3  *
4  *   Copyright (C) International Business Machines  Corp., 2005,2006
5  *   Author(s): Steve French (sfrench@us.ibm.com)
6  *
7  *   This library is free software; you can redistribute it and/or modify
8  *   it under the terms of the GNU Lesser General Public License as published
9  *   by the Free Software Foundation; either version 2.1 of the License, or
10  *   (at your option) any later version.
11  *
12  *   This library is distributed in the hope that it will be useful,
13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
15  *   the GNU Lesser General Public License for more details.
16  *
17  *   You should have received a copy of the GNU Lesser General Public License
18  *   along with this library; if not, write to the Free Software
19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  */
21 
22 #include <linux/fs.h>
23 #include "cifspdu.h"
24 #include "cifsglob.h"
25 #include "cifs_debug.h"
26 #include "md5.h"
27 #include "cifs_unicode.h"
28 #include "cifsproto.h"
29 #include <linux/ctype.h>
30 #include <linux/random.h>
31 
32 /* Calculate and return the CIFS signature based on the mac key and SMB PDU */
33 /* the 16 byte signature must be allocated by the caller  */
34 /* Note we only use the 1st eight bytes */
35 /* Note that the smb header signature field on input contains the
36 	sequence number before this function is called */
37 
38 extern void mdfour(unsigned char *out, unsigned char *in, int n);
39 extern void E_md4hash(const unsigned char *passwd, unsigned char *p16);
40 extern void SMBencrypt(unsigned char *passwd, const unsigned char *c8,
41 		       unsigned char *p24);
42 
cifs_calculate_signature(const struct smb_hdr * cifs_pdu,const struct mac_key * key,char * signature)43 static int cifs_calculate_signature(const struct smb_hdr *cifs_pdu,
44 				    const struct mac_key *key, char *signature)
45 {
46 	struct	MD5Context context;
47 
48 	if ((cifs_pdu == NULL) || (signature == NULL) || (key == NULL))
49 		return -EINVAL;
50 
51 	cifs_MD5_init(&context);
52 	cifs_MD5_update(&context, (char *)&key->data, key->len);
53 	cifs_MD5_update(&context, cifs_pdu->Protocol, cifs_pdu->smb_buf_length);
54 
55 	cifs_MD5_final(signature, &context);
56 	return 0;
57 }
58 
cifs_sign_smb(struct smb_hdr * cifs_pdu,struct TCP_Server_Info * server,__u32 * pexpected_response_sequence_number)59 int cifs_sign_smb(struct smb_hdr *cifs_pdu, struct TCP_Server_Info *server,
60 		  __u32 *pexpected_response_sequence_number)
61 {
62 	int rc = 0;
63 	char smb_signature[20];
64 
65 	if ((cifs_pdu == NULL) || (server == NULL))
66 		return -EINVAL;
67 
68 	if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
69 		return rc;
70 
71 	spin_lock(&GlobalMid_Lock);
72 	cifs_pdu->Signature.Sequence.SequenceNumber =
73 			cpu_to_le32(server->sequence_number);
74 	cifs_pdu->Signature.Sequence.Reserved = 0;
75 
76 	*pexpected_response_sequence_number = server->sequence_number++;
77 	server->sequence_number++;
78 	spin_unlock(&GlobalMid_Lock);
79 
80 	rc = cifs_calculate_signature(cifs_pdu, &server->mac_signing_key,
81 				      smb_signature);
82 	if (rc)
83 		memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
84 	else
85 		memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);
86 
87 	return rc;
88 }
89 
cifs_calc_signature2(const struct kvec * iov,int n_vec,const struct mac_key * key,char * signature)90 static int cifs_calc_signature2(const struct kvec *iov, int n_vec,
91 				const struct mac_key *key, char *signature)
92 {
93 	struct  MD5Context context;
94 	int i;
95 
96 	if ((iov == NULL) || (signature == NULL) || (key == NULL))
97 		return -EINVAL;
98 
99 	cifs_MD5_init(&context);
100 	cifs_MD5_update(&context, (char *)&key->data, key->len);
101 	for (i = 0; i < n_vec; i++) {
102 		if (iov[i].iov_len == 0)
103 			continue;
104 		if (iov[i].iov_base == NULL) {
105 			cERROR(1, ("null iovec entry"));
106 			return -EIO;
107 		}
108 		/* The first entry includes a length field (which does not get
109 		   signed that occupies the first 4 bytes before the header */
110 		if (i == 0) {
111 			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
112 				break; /* nothing to sign or corrupt header */
113 			cifs_MD5_update(&context, iov[0].iov_base+4,
114 				  iov[0].iov_len-4);
115 		} else
116 			cifs_MD5_update(&context, iov[i].iov_base, iov[i].iov_len);
117 	}
118 
119 	cifs_MD5_final(signature, &context);
120 
121 	return 0;
122 }
123 
124 
cifs_sign_smb2(struct kvec * iov,int n_vec,struct TCP_Server_Info * server,__u32 * pexpected_response_sequence_number)125 int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
126 		   __u32 *pexpected_response_sequence_number)
127 {
128 	int rc = 0;
129 	char smb_signature[20];
130 	struct smb_hdr *cifs_pdu = iov[0].iov_base;
131 
132 	if ((cifs_pdu == NULL) || (server == NULL))
133 		return -EINVAL;
134 
135 	if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
136 		return rc;
137 
138 	spin_lock(&GlobalMid_Lock);
139 	cifs_pdu->Signature.Sequence.SequenceNumber =
140 				cpu_to_le32(server->sequence_number);
141 	cifs_pdu->Signature.Sequence.Reserved = 0;
142 
143 	*pexpected_response_sequence_number = server->sequence_number++;
144 	server->sequence_number++;
145 	spin_unlock(&GlobalMid_Lock);
146 
147 	rc = cifs_calc_signature2(iov, n_vec, &server->mac_signing_key,
148 				      smb_signature);
149 	if (rc)
150 		memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
151 	else
152 		memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);
153 
154 	return rc;
155 }
156 
cifs_verify_signature(struct smb_hdr * cifs_pdu,const struct mac_key * mac_key,__u32 expected_sequence_number)157 int cifs_verify_signature(struct smb_hdr *cifs_pdu,
158 			  const struct mac_key *mac_key,
159 			  __u32 expected_sequence_number)
160 {
161 	unsigned int rc;
162 	char server_response_sig[8];
163 	char what_we_think_sig_should_be[20];
164 
165 	if ((cifs_pdu == NULL) || (mac_key == NULL))
166 		return -EINVAL;
167 
168 	if (cifs_pdu->Command == SMB_COM_NEGOTIATE)
169 		return 0;
170 
171 	if (cifs_pdu->Command == SMB_COM_LOCKING_ANDX) {
172 		struct smb_com_lock_req *pSMB =
173 			(struct smb_com_lock_req *)cifs_pdu;
174 	    if (pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE)
175 			return 0;
176 	}
177 
178 	/* BB what if signatures are supposed to be on for session but
179 	   server does not send one? BB */
180 
181 	/* Do not need to verify session setups with signature "BSRSPYL "  */
182 	if (memcmp(cifs_pdu->Signature.SecuritySignature, "BSRSPYL ", 8) == 0)
183 		cFYI(1, ("dummy signature received for smb command 0x%x",
184 			cifs_pdu->Command));
185 
186 	/* save off the origiginal signature so we can modify the smb and check
187 		its signature against what the server sent */
188 	memcpy(server_response_sig, cifs_pdu->Signature.SecuritySignature, 8);
189 
190 	cifs_pdu->Signature.Sequence.SequenceNumber =
191 					cpu_to_le32(expected_sequence_number);
192 	cifs_pdu->Signature.Sequence.Reserved = 0;
193 
194 	rc = cifs_calculate_signature(cifs_pdu, mac_key,
195 		what_we_think_sig_should_be);
196 
197 	if (rc)
198 		return rc;
199 
200 /*	cifs_dump_mem("what we think it should be: ",
201 		      what_we_think_sig_should_be, 16); */
202 
203 	if (memcmp(server_response_sig, what_we_think_sig_should_be, 8))
204 		return -EACCES;
205 	else
206 		return 0;
207 
208 }
209 
210 /* We fill in key by putting in 40 byte array which was allocated by caller */
cifs_calculate_mac_key(struct mac_key * key,const char * rn,const char * password)211 int cifs_calculate_mac_key(struct mac_key *key, const char *rn,
212 			   const char *password)
213 {
214 	char temp_key[16];
215 	if ((key == NULL) || (rn == NULL))
216 		return -EINVAL;
217 
218 	E_md4hash(password, temp_key);
219 	mdfour(key->data.ntlm, temp_key, 16);
220 	memcpy(key->data.ntlm+16, rn, CIFS_SESS_KEY_SIZE);
221 	key->len = 40;
222 	return 0;
223 }
224 
CalcNTLMv2_partial_mac_key(struct cifsSesInfo * ses,const struct nls_table * nls_info)225 int CalcNTLMv2_partial_mac_key(struct cifsSesInfo *ses,
226 			       const struct nls_table *nls_info)
227 {
228 	char temp_hash[16];
229 	struct HMACMD5Context ctx;
230 	char *ucase_buf;
231 	__le16 *unicode_buf;
232 	unsigned int i, user_name_len, dom_name_len;
233 
234 	if (ses == NULL)
235 		return -EINVAL;
236 
237 	E_md4hash(ses->password, temp_hash);
238 
239 	hmac_md5_init_limK_to_64(temp_hash, 16, &ctx);
240 	user_name_len = strlen(ses->userName);
241 	if (user_name_len > MAX_USERNAME_SIZE)
242 		return -EINVAL;
243 	if (ses->domainName == NULL)
244 		return -EINVAL; /* BB should we use CIFS_LINUX_DOM */
245 	dom_name_len = strlen(ses->domainName);
246 	if (dom_name_len > MAX_USERNAME_SIZE)
247 		return -EINVAL;
248 
249 	ucase_buf = kmalloc((MAX_USERNAME_SIZE+1), GFP_KERNEL);
250 	if (ucase_buf == NULL)
251 		return -ENOMEM;
252 	unicode_buf = kmalloc((MAX_USERNAME_SIZE+1)*4, GFP_KERNEL);
253 	if (unicode_buf == NULL) {
254 		kfree(ucase_buf);
255 		return -ENOMEM;
256 	}
257 
258 	for (i = 0; i < user_name_len; i++)
259 		ucase_buf[i] = nls_info->charset2upper[(int)ses->userName[i]];
260 	ucase_buf[i] = 0;
261 	user_name_len = cifs_strtoUCS(unicode_buf, ucase_buf,
262 				      MAX_USERNAME_SIZE*2, nls_info);
263 	unicode_buf[user_name_len] = 0;
264 	user_name_len++;
265 
266 	for (i = 0; i < dom_name_len; i++)
267 		ucase_buf[i] = nls_info->charset2upper[(int)ses->domainName[i]];
268 	ucase_buf[i] = 0;
269 	dom_name_len = cifs_strtoUCS(unicode_buf+user_name_len, ucase_buf,
270 				     MAX_USERNAME_SIZE*2, nls_info);
271 
272 	unicode_buf[user_name_len + dom_name_len] = 0;
273 	hmac_md5_update((const unsigned char *) unicode_buf,
274 		(user_name_len+dom_name_len)*2, &ctx);
275 
276 	hmac_md5_final(ses->server->ntlmv2_hash, &ctx);
277 	kfree(ucase_buf);
278 	kfree(unicode_buf);
279 	return 0;
280 }
281 
282 #ifdef CONFIG_CIFS_WEAK_PW_HASH
calc_lanman_hash(const char * password,const char * cryptkey,bool encrypt,char * lnm_session_key)283 void calc_lanman_hash(const char *password, const char *cryptkey, bool encrypt,
284 			char *lnm_session_key)
285 {
286 	int i;
287 	char password_with_pad[CIFS_ENCPWD_SIZE];
288 
289 	memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
290 	if (password)
291 		strncpy(password_with_pad, password, CIFS_ENCPWD_SIZE);
292 
293 	if (!encrypt && extended_security & CIFSSEC_MAY_PLNTXT) {
294 		memset(lnm_session_key, 0, CIFS_SESS_KEY_SIZE);
295 		memcpy(lnm_session_key, password_with_pad,
296 			CIFS_ENCPWD_SIZE);
297 		return;
298 	}
299 
300 	/* calculate old style session key */
301 	/* calling toupper is less broken than repeatedly
302 	calling nls_toupper would be since that will never
303 	work for UTF8, but neither handles multibyte code pages
304 	but the only alternative would be converting to UCS-16 (Unicode)
305 	(using a routine something like UniStrupr) then
306 	uppercasing and then converting back from Unicode - which
307 	would only worth doing it if we knew it were utf8. Basically
308 	utf8 and other multibyte codepages each need their own strupper
309 	function since a byte at a time will ont work. */
310 
311 	for (i = 0; i < CIFS_ENCPWD_SIZE; i++)
312 		password_with_pad[i] = toupper(password_with_pad[i]);
313 
314 	SMBencrypt(password_with_pad, cryptkey, lnm_session_key);
315 
316 	/* clear password before we return/free memory */
317 	memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
318 }
319 #endif /* CIFS_WEAK_PW_HASH */
320 
calc_ntlmv2_hash(struct cifsSesInfo * ses,const struct nls_table * nls_cp)321 static int calc_ntlmv2_hash(struct cifsSesInfo *ses,
322 			    const struct nls_table *nls_cp)
323 {
324 	int rc = 0;
325 	int len;
326 	char nt_hash[16];
327 	struct HMACMD5Context *pctxt;
328 	wchar_t *user;
329 	wchar_t *domain;
330 
331 	pctxt = kmalloc(sizeof(struct HMACMD5Context), GFP_KERNEL);
332 
333 	if (pctxt == NULL)
334 		return -ENOMEM;
335 
336 	/* calculate md4 hash of password */
337 	E_md4hash(ses->password, nt_hash);
338 
339 	/* convert Domainname to unicode and uppercase */
340 	hmac_md5_init_limK_to_64(nt_hash, 16, pctxt);
341 
342 	/* convert ses->userName to unicode and uppercase */
343 	len = strlen(ses->userName);
344 	user = kmalloc(2 + (len * 2), GFP_KERNEL);
345 	if (user == NULL)
346 		goto calc_exit_2;
347 	len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
348 	UniStrupr(user);
349 	hmac_md5_update((char *)user, 2*len, pctxt);
350 
351 	/* convert ses->domainName to unicode and uppercase */
352 	if (ses->domainName) {
353 		len = strlen(ses->domainName);
354 
355 		domain = kmalloc(2 + (len * 2), GFP_KERNEL);
356 		if (domain == NULL)
357 			goto calc_exit_1;
358 		len = cifs_strtoUCS((__le16 *)domain, ses->domainName, len,
359 					nls_cp);
360 		/* the following line was removed since it didn't work well
361 		   with lower cased domain name that passed as an option.
362 		   Maybe converting the domain name earlier makes sense */
363 		/* UniStrupr(domain); */
364 
365 		hmac_md5_update((char *)domain, 2*len, pctxt);
366 
367 		kfree(domain);
368 	}
369 calc_exit_1:
370 	kfree(user);
371 calc_exit_2:
372 	/* BB FIXME what about bytes 24 through 40 of the signing key?
373 	   compare with the NTLM example */
374 	hmac_md5_final(ses->server->ntlmv2_hash, pctxt);
375 
376 	return rc;
377 }
378 
setup_ntlmv2_rsp(struct cifsSesInfo * ses,char * resp_buf,const struct nls_table * nls_cp)379 void setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
380 		      const struct nls_table *nls_cp)
381 {
382 	int rc;
383 	struct ntlmv2_resp *buf = (struct ntlmv2_resp *)resp_buf;
384 	struct HMACMD5Context context;
385 
386 	buf->blob_signature = cpu_to_le32(0x00000101);
387 	buf->reserved = 0;
388 	buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
389 	get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
390 	buf->reserved2 = 0;
391 	buf->names[0].type = cpu_to_le16(NTLMSSP_DOMAIN_TYPE);
392 	buf->names[0].length = 0;
393 	buf->names[1].type = 0;
394 	buf->names[1].length = 0;
395 
396 	/* calculate buf->ntlmv2_hash */
397 	rc = calc_ntlmv2_hash(ses, nls_cp);
398 	if (rc)
399 		cERROR(1, ("could not get v2 hash rc %d", rc));
400 	CalcNTLMv2_response(ses, resp_buf);
401 
402 	/* now calculate the MAC key for NTLMv2 */
403 	hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);
404 	hmac_md5_update(resp_buf, 16, &context);
405 	hmac_md5_final(ses->server->mac_signing_key.data.ntlmv2.key, &context);
406 
407 	memcpy(&ses->server->mac_signing_key.data.ntlmv2.resp, resp_buf,
408 	       sizeof(struct ntlmv2_resp));
409 	ses->server->mac_signing_key.len = 16 + sizeof(struct ntlmv2_resp);
410 }
411 
CalcNTLMv2_response(const struct cifsSesInfo * ses,char * v2_session_response)412 void CalcNTLMv2_response(const struct cifsSesInfo *ses,
413 			 char *v2_session_response)
414 {
415 	struct HMACMD5Context context;
416 	/* rest of v2 struct already generated */
417 	memcpy(v2_session_response + 8, ses->server->cryptKey, 8);
418 	hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);
419 
420 	hmac_md5_update(v2_session_response+8,
421 			sizeof(struct ntlmv2_resp) - 8, &context);
422 
423 	hmac_md5_final(v2_session_response, &context);
424 /*	cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); */
425 }
426