fs/cifs/cifsencrypt.c

   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 <linux/slab.h>
  24 #include "cifspdu.h"
  25 #include "cifsglob.h"
  26 #include "cifs_debug.h"
  27 #include "md5.h"
  28 #include "cifs_unicode.h"
  29 #include "cifsproto.h"
  30 #include "ntlmssp.h"
  31 #include <linux/ctype.h>
  32 #include <linux/random.h>
  33
  34 /* Calculate and return the CIFS signature based on the mac key and SMB PDU */
  35 /* the 16 byte signature must be allocated by the caller  */
  36 /* Note we only use the 1st eight bytes */
  37 /* Note that the smb header signature field on input contains the
  38         sequence number before this function is called */
  39
  40 extern void mdfour(unsigned char *out, unsigned char *in, int n);
  41 extern void E_md4hash(const unsigned char *passwd, unsigned char *p16);
  42 extern void SMBencrypt(unsigned char *passwd, const unsigned char *c8,
  43                        unsigned char *p24);
  44
  45 static int cifs_calculate_signature(const struct smb_hdr *cifs_pdu,
  46                                 const struct session_key *key, char *signature)
  47 {
  48         struct  MD5Context context;
  49
  50         if ((cifs_pdu == NULL) || (signature == NULL) || (key == NULL))
  51                 return -EINVAL;
  52
  53         cifs_MD5_init(&context);
  54         cifs_MD5_update(&context, (char *)&key->data, key->len);
  55         cifs_MD5_update(&context, cifs_pdu->Protocol, cifs_pdu->smb_buf_length);
  56
  57         cifs_MD5_final(signature, &context);
  58         return 0;
  59 }
  60
  61 int cifs_sign_smb(struct smb_hdr *cifs_pdu, struct TCP_Server_Info *server,
  62                   __u32 *pexpected_response_sequence_number)
  63 {
  64         int rc = 0;
  65         char smb_signature[20];
  66
  67         if ((cifs_pdu == NULL) || (server == NULL))
  68                 return -EINVAL;
  69
  70         if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
  71                 return rc;
  72
  73         spin_lock(&GlobalMid_Lock);
  74         cifs_pdu->Signature.Sequence.SequenceNumber =
  75                         cpu_to_le32(server->sequence_number);
  76         cifs_pdu->Signature.Sequence.Reserved = 0;
  77
  78         *pexpected_response_sequence_number = server->sequence_number++;
  79         server->sequence_number++;
  80         spin_unlock(&GlobalMid_Lock);
  81
  82         rc = cifs_calculate_signature(cifs_pdu, &server->session_key,
  83                                       smb_signature);
  84         if (rc)
  85                 memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
  86         else
  87                 memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);
  88
  89         return rc;
  90 }
  91
  92 static int cifs_calc_signature2(const struct kvec *iov, int n_vec,
  93                                 const struct session_key *key, char *signature)
  94 {
  95         struct  MD5Context context;
  96         int i;
  97
  98         if ((iov == NULL) || (signature == NULL) || (key == NULL))
  99                 return -EINVAL;
 100
 101         cifs_MD5_init(&context);
 102         cifs_MD5_update(&context, (char *)&key->data, key->len);
 103         for (i = 0; i < n_vec; i++) {
 104                 if (iov[i].iov_len == 0)
 105                         continue;
 106                 if (iov[i].iov_base == NULL) {
 107                         cERROR(1, "null iovec entry");
 108                         return -EIO;
 109                 }
 110                 /* The first entry includes a length field (which does not get
 111                    signed that occupies the first 4 bytes before the header */
 112                 if (i == 0) {
 113                         if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
 114                                 break; /* nothing to sign or corrupt header */
 115                         cifs_MD5_update(&context, iov[0].iov_base+4,
 116                                   iov[0].iov_len-4);
 117                 } else
 118                         cifs_MD5_update(&context, iov[i].iov_base, iov[i].iov_len);
 119         }
 120
 121         cifs_MD5_final(signature, &context);
 122
 123         return 0;
 124 }
 125
 126
 127 int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
 128                    __u32 *pexpected_response_sequence_number)
 129 {
 130         int rc = 0;
 131         char smb_signature[20];
 132         struct smb_hdr *cifs_pdu = iov[0].iov_base;
 133
 134         if ((cifs_pdu == NULL) || (server == NULL))
 135                 return -EINVAL;
 136
 137         if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
 138                 return rc;
 139
 140         spin_lock(&GlobalMid_Lock);
 141         cifs_pdu->Signature.Sequence.SequenceNumber =
 142                                 cpu_to_le32(server->sequence_number);
 143         cifs_pdu->Signature.Sequence.Reserved = 0;
 144
 145         *pexpected_response_sequence_number = server->sequence_number++;
 146         server->sequence_number++;
 147         spin_unlock(&GlobalMid_Lock);
 148
 149         rc = cifs_calc_signature2(iov, n_vec, &server->session_key,
 150                                       smb_signature);
 151         if (rc)
 152                 memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
 153         else
 154                 memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);
 155
 156         return rc;
 157 }
 158
 159 int cifs_verify_signature(struct smb_hdr *cifs_pdu,
 160                           const struct session_key *session_key,
 161                           __u32 expected_sequence_number)
 162 {
 163         unsigned int rc;
 164         char server_response_sig[8];
 165         char what_we_think_sig_should_be[20];
 166
 167         if (cifs_pdu == NULL || session_key == NULL)
 168                 return -EINVAL;
 169
 170         if (cifs_pdu->Command == SMB_COM_NEGOTIATE)
 171                 return 0;
 172
 173         if (cifs_pdu->Command == SMB_COM_LOCKING_ANDX) {
 174                 struct smb_com_lock_req *pSMB =
 175                         (struct smb_com_lock_req *)cifs_pdu;
 176             if (pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE)
 177                         return 0;
 178         }
 179
 180         /* BB what if signatures are supposed to be on for session but
 181            server does not send one? BB */
 182
 183         /* Do not need to verify session setups with signature "BSRSPYL "  */
 184         if (memcmp(cifs_pdu->Signature.SecuritySignature, "BSRSPYL ", 8) == 0)
 185                 cFYI(1, "dummy signature received for smb command 0x%x",
 186                         cifs_pdu->Command);
 187
 188         /* save off the origiginal signature so we can modify the smb and check
 189                 its signature against what the server sent */
 190         memcpy(server_response_sig, cifs_pdu->Signature.SecuritySignature, 8);
 191
 192         cifs_pdu->Signature.Sequence.SequenceNumber =
 193                                         cpu_to_le32(expected_sequence_number);
 194         cifs_pdu->Signature.Sequence.Reserved = 0;
 195
 196         rc = cifs_calculate_signature(cifs_pdu, session_key,
 197                 what_we_think_sig_should_be);
 198
 199         if (rc)
 200                 return rc;
 201
 202 /*      cifs_dump_mem("what we think it should be: ",
 203                       what_we_think_sig_should_be, 16); */
 204
 205         if (memcmp(server_response_sig, what_we_think_sig_should_be, 8))
 206                 return -EACCES;
 207         else
 208                 return 0;
 209
 210 }
 211
 212 /* We fill in key by putting in 40 byte array which was allocated by caller */
 213 int cifs_calculate_session_key(struct session_key *key, const char *rn,
 214                            const char *password)
 215 {
 216         char temp_key[16];
 217         if ((key == NULL) || (rn == NULL))
 218                 return -EINVAL;
 219
 220         E_md4hash(password, temp_key);
 221         mdfour(key->data.ntlm, temp_key, 16);
 222         memcpy(key->data.ntlm+16, rn, CIFS_SESS_KEY_SIZE);
 223         key->len = 40;
 224         return 0;
 225 }
 226
 227 #ifdef CONFIG_CIFS_WEAK_PW_HASH
 228 void calc_lanman_hash(const char *password, const char *cryptkey, bool encrypt,
 229                         char *lnm_session_key)
 230 {
 231         int i;
 232         char password_with_pad[CIFS_ENCPWD_SIZE];
 233
 234         memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
 235         if (password)
 236                 strncpy(password_with_pad, password, CIFS_ENCPWD_SIZE);
 237
 238         if (!encrypt && global_secflags & CIFSSEC_MAY_PLNTXT) {
 239                 memset(lnm_session_key, 0, CIFS_SESS_KEY_SIZE);
 240                 memcpy(lnm_session_key, password_with_pad,
 241                         CIFS_ENCPWD_SIZE);
 242                 return;
 243         }
 244
 245         /* calculate old style session key */
 246         /* calling toupper is less broken than repeatedly
 247         calling nls_toupper would be since that will never
 248         work for UTF8, but neither handles multibyte code pages
 249         but the only alternative would be converting to UCS-16 (Unicode)
 250         (using a routine something like UniStrupr) then
 251         uppercasing and then converting back from Unicode - which
 252         would only worth doing it if we knew it were utf8. Basically
 253         utf8 and other multibyte codepages each need their own strupper
 254         function since a byte at a time will ont work. */
 255
 256         for (i = 0; i < CIFS_ENCPWD_SIZE; i++)
 257                 password_with_pad[i] = toupper(password_with_pad[i]);
 258
 259         SMBencrypt(password_with_pad, cryptkey, lnm_session_key);
 260
 261         /* clear password before we return/free memory */
 262         memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
 263 }
 264 #endif /* CIFS_WEAK_PW_HASH */
 265
 266 /* This is just a filler for ntlmv2 type of security mechanisms.
 267  * Older servers are not very particular about the contents of av pairs
 268  * in the blob and for sec mechs like ntlmv2, there is no negotiation
 269  * as in ntlmssp, so unless domain and server  netbios and dns names
 270  * are specified, there is no way to obtain name.  In case of ntlmssp,
 271  * server provides that info in type 2 challenge packet
 272  */
 273 static int
 274 build_avpair_blob(struct cifsSesInfo *ses)
 275 {
 276         struct ntlmssp2_name *attrptr;
 277
 278         ses->tilen = 2 * sizeof(struct ntlmssp2_name);
 279         ses->tiblob = kzalloc(ses->tilen, GFP_KERNEL);
 280         if (!ses->tiblob) {
 281                 ses->tilen = 0;
 282                 cERROR(1, "Challenge target info allocation failure");
 283                 return -ENOMEM;
 284         }
 285         attrptr = (struct ntlmssp2_name *) ses->tiblob;
 286         attrptr->type = cpu_to_le16(NTLMSSP_DOMAIN_TYPE);
 287
 288         return 0;
 289 }
 290
 291 /* Server has provided av pairs/target info in the type 2 challenge
 292  * packet and we have plucked it and stored within smb session.
 293  * We parse that blob here to find netbios domain name to be used
 294  * as part of ntlmv2 authentication (in Target String), if not already
 295  * specified on the command line.
 296  * If this function returns without any error but without fetching
 297  * domain name, authentication may fail against some server but
 298  * may not fail against other (those who are not very particular
 299  * about target string i.e. for some, just user name might suffice.
 300  */
 301 static int
 302 find_domain_name(struct cifsSesInfo *ses)
 303 {
 304         unsigned int attrsize;
 305         unsigned int type;
 306         unsigned int onesize = sizeof(struct ntlmssp2_name);
 307         unsigned char *blobptr;
 308         unsigned char *blobend;
 309         struct ntlmssp2_name *attrptr;
 310
 311         if (!ses->tilen || !ses->tiblob)
 312                 return 0;
 313
 314         blobptr = ses->tiblob;
 315         blobend = ses->tiblob + ses->tilen;
 316
 317         while (blobptr + onesize < blobend) {
 318                 attrptr = (struct ntlmssp2_name *) blobptr;
 319                 type = le16_to_cpu(attrptr->type);
 320                 if (type == NTLMSSP_AV_EOL)
 321                         break;
 322                 blobptr += 2; /* advance attr type */
 323                 attrsize = le16_to_cpu(attrptr->length);
 324                 blobptr += 2; /* advance attr size */
 325                 if (blobptr + attrsize > blobend)
 326                         break;
 327                 if (type == NTLMSSP_AV_NB_DOMAIN_NAME) {
 328                         if (!attrsize)
 329                                 break;
 330                         if (!ses->domainName) {
 331                                 ses->domainName =
 332                                         kmalloc(attrsize + 1, GFP_KERNEL);
 333                                 if (!ses->domainName)
 334                                                 return -ENOMEM;
 335                                 cifs_from_ucs2(ses->domainName,
 336                                         (__le16 *)blobptr, attrsize, attrsize,
 337                                         load_nls_default(), false);
 338                                 break;
 339                         }
 340                 }
 341                 blobptr += attrsize; /* advance attr  value */
 342         }
 343
 344         return 0;
 345 }
 346
 347 static int calc_ntlmv2_hash(struct cifsSesInfo *ses,
 348                             const struct nls_table *nls_cp)
 349 {
 350         int rc = 0;
 351         int len;
 352         char nt_hash[16];
 353         struct HMACMD5Context *pctxt;
 354         wchar_t *user;
 355         wchar_t *domain;
 356
 357         pctxt = kmalloc(sizeof(struct HMACMD5Context), GFP_KERNEL);
 358
 359         if (pctxt == NULL)
 360                 return -ENOMEM;
 361
 362         /* calculate md4 hash of password */
 363         E_md4hash(ses->password, nt_hash);
 364
 365         /* convert Domainname to unicode and uppercase */
 366         hmac_md5_init_limK_to_64(nt_hash, 16, pctxt);
 367
 368         /* convert ses->userName to unicode and uppercase */
 369         len = strlen(ses->userName);
 370         user = kmalloc(2 + (len * 2), GFP_KERNEL);
 371         if (user == NULL)
 372                 goto calc_exit_2;
 373         len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
 374         UniStrupr(user);
 375         hmac_md5_update((char *)user, 2*len, pctxt);
 376
 377         /* convert ses->domainName to unicode and uppercase */
 378         if (ses->domainName) {
 379                 len = strlen(ses->domainName);
 380
 381                 domain = kmalloc(2 + (len * 2), GFP_KERNEL);
 382                 if (domain == NULL)
 383                         goto calc_exit_1;
 384                 len = cifs_strtoUCS((__le16 *)domain, ses->domainName, len,
 385                                         nls_cp);
 386                 /* the following line was removed since it didn't work well
 387                    with lower cased domain name that passed as an option.
 388                    Maybe converting the domain name earlier makes sense */
 389                 /* UniStrupr(domain); */
 390
 391                 hmac_md5_update((char *)domain, 2*len, pctxt);
 392
 393                 kfree(domain);
 394         }
 395 calc_exit_1:
 396         kfree(user);
 397 calc_exit_2:
 398         /* BB FIXME what about bytes 24 through 40 of the signing key?
 399            compare with the NTLM example */
 400         hmac_md5_final(ses->server->ntlmv2_hash, pctxt);
 401
 402         kfree(pctxt);
 403         return rc;
 404 }
 405
 406 int
 407 setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
 408                       const struct nls_table *nls_cp)
 409 {
 410         int rc;
 411         struct ntlmv2_resp *buf = (struct ntlmv2_resp *)resp_buf;
 412         struct HMACMD5Context context;
 413
 414         buf->blob_signature = cpu_to_le32(0x00000101);
 415         buf->reserved = 0;
 416         buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
 417         get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
 418         buf->reserved2 = 0;
 419
 420         if (ses->server->secType == RawNTLMSSP) {
 421                 if (!ses->domainName) {
 422                         rc = find_domain_name(ses);
 423                         if (rc) {
 424                                 cERROR(1, "error %d finding domain name", rc);
 425                                 goto setup_ntlmv2_rsp_ret;
 426                         }
 427                 }
 428         } else {
 429                 rc = build_avpair_blob(ses);
 430                 if (rc) {
 431                         cERROR(1, "error %d building av pair blob", rc);
 432                         return rc;
 433                 }
 434         }
 435
 436         /* calculate buf->ntlmv2_hash */
 437         rc = calc_ntlmv2_hash(ses, nls_cp);
 438         if (rc) {
 439                 cERROR(1, "could not get v2 hash rc %d", rc);
 440                 goto setup_ntlmv2_rsp_ret;
 441         }
 442         CalcNTLMv2_response(ses, resp_buf);
 443
 444         /* now calculate the MAC key for NTLMv2 */
 445         hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);
 446         hmac_md5_update(resp_buf, 16, &context);
 447         hmac_md5_final(ses->server->session_key.data.ntlmv2.key, &context);
 448
 449         memcpy(&ses->server->session_key.data.ntlmv2.resp, resp_buf,
 450                sizeof(struct ntlmv2_resp));
 451         ses->server->session_key.len = 16 + sizeof(struct ntlmv2_resp);
 452
 453         return 0;
 454
 455 setup_ntlmv2_rsp_ret:
 456         kfree(ses->tiblob);
 457         ses->tiblob = NULL;
 458         ses->tilen = 0;
 459
 460         return rc;
 461 }
 462
 463 void CalcNTLMv2_response(const struct cifsSesInfo *ses,
 464                          char *v2_session_response)
 465 {
 466         struct HMACMD5Context context;
 467         /* rest of v2 struct already generated */
 468         memcpy(v2_session_response + 8, ses->server->cryptKey, 8);
 469         hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);
 470
 471         hmac_md5_update(v2_session_response+8,
 472                         sizeof(struct ntlmv2_resp) - 8, &context);
 473
 474         if (ses->tilen)
 475                 hmac_md5_update(ses->tiblob, ses->tilen, &context);
 476
 477         hmac_md5_final(v2_session_response, &context);
 478 /*      cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); */
 479 }