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 /* Build a proper attribute value/target info pairs blob.
 267  * Fill in netbios and dns domain name and workstation name
 268  * and client time (total five av pairs and + one end of fields indicator.
 269  * Allocate domain name which gets freed when session struct is deallocated.
 270  */
 271 static int
 272 build_avpair_blob(struct cifsSesInfo *ses, const struct nls_table *nls_cp)
 273 {
 274         unsigned int dlen;
 275         unsigned int wlen;
 276         unsigned int size = 6 * sizeof(struct ntlmssp2_name);
 277         __le64  curtime;
 278         char *defdmname = "WORKGROUP";
 279         unsigned char *blobptr;
 280         struct ntlmssp2_name *attrptr;
 281
 282         if (!ses->domainName) {
 283                 ses->domainName = kstrdup(defdmname, GFP_KERNEL);
 284                 if (!ses->domainName)
 285                         return -ENOMEM;
 286         }
 287
 288         dlen = strlen(ses->domainName);
 289         wlen = strlen(ses->server->hostname);
 290
 291         /* The length of this blob is a size which is
 292          * six times the size of a structure which holds name/size +
 293          * two times the unicode length of a domain name +
 294          * two times the unicode length of a server name +
 295          * size of a timestamp (which is 8 bytes).
 296          */
 297         ses->tilen = size + 2 * (2 * dlen) + 2 * (2 * wlen) + 8;
 298         ses->tiblob = kzalloc(ses->tilen, GFP_KERNEL);
 299         if (!ses->tiblob) {
 300                 ses->tilen = 0;
 301                 cERROR(1, "Challenge target info allocation failure");
 302                 return -ENOMEM;
 303         }
 304
 305         blobptr = ses->tiblob;
 306         attrptr = (struct ntlmssp2_name *) blobptr;
 307
 308         attrptr->type = cpu_to_le16(NTLMSSP_AV_NB_DOMAIN_NAME);
 309         attrptr->length = cpu_to_le16(2 * dlen);
 310         blobptr = (unsigned char *)attrptr + sizeof(struct ntlmssp2_name);
 311         cifs_strtoUCS((__le16 *)blobptr, ses->domainName, dlen, nls_cp);
 312
 313         blobptr += 2 * dlen;
 314         attrptr = (struct ntlmssp2_name *) blobptr;
 315
 316         attrptr->type = cpu_to_le16(NTLMSSP_AV_NB_COMPUTER_NAME);
 317         attrptr->length = cpu_to_le16(2 * wlen);
 318         blobptr = (unsigned char *)attrptr + sizeof(struct ntlmssp2_name);
 319         cifs_strtoUCS((__le16 *)blobptr, ses->server->hostname, wlen, nls_cp);
 320
 321         blobptr += 2 * wlen;
 322         attrptr = (struct ntlmssp2_name *) blobptr;
 323
 324         attrptr->type = cpu_to_le16(NTLMSSP_AV_DNS_DOMAIN_NAME);
 325         attrptr->length = cpu_to_le16(2 * dlen);
 326         blobptr = (unsigned char *)attrptr + sizeof(struct ntlmssp2_name);
 327         cifs_strtoUCS((__le16 *)blobptr, ses->domainName, dlen, nls_cp);
 328
 329         blobptr += 2 * dlen;
 330         attrptr = (struct ntlmssp2_name *) blobptr;
 331
 332         attrptr->type = cpu_to_le16(NTLMSSP_AV_DNS_COMPUTER_NAME);
 333         attrptr->length = cpu_to_le16(2 * wlen);
 334         blobptr = (unsigned char *)attrptr + sizeof(struct ntlmssp2_name);
 335         cifs_strtoUCS((__le16 *)blobptr, ses->server->hostname, wlen, nls_cp);
 336
 337         blobptr += 2 * wlen;
 338         attrptr = (struct ntlmssp2_name *) blobptr;
 339
 340         attrptr->type = cpu_to_le16(NTLMSSP_AV_TIMESTAMP);
 341         attrptr->length = cpu_to_le16(sizeof(__le64));
 342         blobptr = (unsigned char *)attrptr + sizeof(struct ntlmssp2_name);
 343         curtime = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
 344         memcpy(blobptr, &curtime, sizeof(__le64));
 345
 346         return 0;
 347 }
 348
 349 /* Server has provided av pairs/target info in the type 2 challenge
 350  * packet and we have plucked it and stored within smb session.
 351  * We parse that blob here to find netbios domain name to be used
 352  * as part of ntlmv2 authentication (in Target String), if not already
 353  * specified on the command line.
 354  * If this function returns without any error but without fetching
 355  * domain name, authentication may fail against some server but
 356  * may not fail against other (those who are not very particular
 357  * about target string i.e. for some, just user name might suffice.
 358  */
 359 static int
 360 find_domain_name(struct cifsSesInfo *ses)
 361 {
 362         unsigned int attrsize;
 363         unsigned int type;
 364         unsigned int onesize = sizeof(struct ntlmssp2_name);
 365         unsigned char *blobptr;
 366         unsigned char *blobend;
 367         struct ntlmssp2_name *attrptr;
 368
 369         if (!ses->tilen || !ses->tiblob)
 370                 return 0;
 371
 372         blobptr = ses->tiblob;
 373         blobend = ses->tiblob + ses->tilen;
 374
 375         while (blobptr + onesize < blobend) {
 376                 attrptr = (struct ntlmssp2_name *) blobptr;
 377                 type = le16_to_cpu(attrptr->type);
 378                 if (type == NTLMSSP_AV_EOL)
 379                         break;
 380                 blobptr += 2; /* advance attr type */
 381                 attrsize = le16_to_cpu(attrptr->length);
 382                 blobptr += 2; /* advance attr size */
 383                 if (blobptr + attrsize > blobend)
 384                         break;
 385                 if (type == NTLMSSP_AV_NB_DOMAIN_NAME) {
 386                         if (!attrsize)
 387                                 break;
 388                         if (!ses->domainName) {
 389                                 struct nls_table *default_nls;
 390                                 ses->domainName =
 391                                         kmalloc(attrsize + 1, GFP_KERNEL);
 392                                 if (!ses->domainName)
 393                                                 return -ENOMEM;
 394                                 default_nls = load_nls_default();
 395                                 cifs_from_ucs2(ses->domainName,
 396                                         (__le16 *)blobptr, attrsize, attrsize,
 397                                         default_nls, false);
 398                                 unload_nls(default_nls);
 399                                 break;
 400                         }
 401                 }
 402                 blobptr += attrsize; /* advance attr  value */
 403         }
 404
 405         return 0;
 406 }
 407
 408 static int calc_ntlmv2_hash(struct cifsSesInfo *ses,
 409                             const struct nls_table *nls_cp)
 410 {
 411         int rc = 0;
 412         int len;
 413         char nt_hash[16];
 414         struct HMACMD5Context *pctxt;
 415         wchar_t *user;
 416         wchar_t *domain;
 417
 418         pctxt = kmalloc(sizeof(struct HMACMD5Context), GFP_KERNEL);
 419
 420         if (pctxt == NULL)
 421                 return -ENOMEM;
 422
 423         /* calculate md4 hash of password */
 424         E_md4hash(ses->password, nt_hash);
 425
 426         /* convert Domainname to unicode and uppercase */
 427         hmac_md5_init_limK_to_64(nt_hash, 16, pctxt);
 428
 429         /* convert ses->userName to unicode and uppercase */
 430         len = strlen(ses->userName);
 431         user = kmalloc(2 + (len * 2), GFP_KERNEL);
 432         if (user == NULL)
 433                 goto calc_exit_2;
 434         len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
 435         UniStrupr(user);
 436         hmac_md5_update((char *)user, 2*len, pctxt);
 437
 438         /* convert ses->domainName to unicode and uppercase */
 439         if (ses->domainName) {
 440                 len = strlen(ses->domainName);
 441
 442                 domain = kmalloc(2 + (len * 2), GFP_KERNEL);
 443                 if (domain == NULL)
 444                         goto calc_exit_1;
 445                 len = cifs_strtoUCS((__le16 *)domain, ses->domainName, len,
 446                                         nls_cp);
 447                 /* the following line was removed since it didn't work well
 448                    with lower cased domain name that passed as an option.
 449                    Maybe converting the domain name earlier makes sense */
 450                 /* UniStrupr(domain); */
 451
 452                 hmac_md5_update((char *)domain, 2*len, pctxt);
 453
 454                 kfree(domain);
 455         }
 456 calc_exit_1:
 457         kfree(user);
 458 calc_exit_2:
 459         /* BB FIXME what about bytes 24 through 40 of the signing key?
 460            compare with the NTLM example */
 461         hmac_md5_final(ses->ntlmv2_hash, pctxt);
 462
 463         kfree(pctxt);
 464         return rc;
 465 }
 466
 467 int
 468 setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
 469                       const struct nls_table *nls_cp)
 470 {
 471         int rc;
 472         struct ntlmv2_resp *buf = (struct ntlmv2_resp *)resp_buf;
 473         struct HMACMD5Context context;
 474
 475         buf->blob_signature = cpu_to_le32(0x00000101);
 476         buf->reserved = 0;
 477         buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
 478         get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
 479         buf->reserved2 = 0;
 480
 481         if (ses->server->secType == RawNTLMSSP) {
 482                 if (!ses->domainName) {
 483                         rc = find_domain_name(ses);
 484                         if (rc) {
 485                                 cERROR(1, "error %d finding domain name", rc);
 486                                 goto setup_ntlmv2_rsp_ret;
 487                         }
 488                 }
 489         } else {
 490                 rc = build_avpair_blob(ses, nls_cp);
 491                 if (rc) {
 492                         cERROR(1, "error %d building av pair blob", rc);
 493                         return rc;
 494                 }
 495         }
 496
 497         /* calculate buf->ntlmv2_hash */
 498         rc = calc_ntlmv2_hash(ses, nls_cp);
 499         if (rc) {
 500                 cERROR(1, "could not get v2 hash rc %d", rc);
 501                 goto setup_ntlmv2_rsp_ret;
 502         }
 503         CalcNTLMv2_response(ses, resp_buf);
 504
 505         /* now calculate the session key for NTLMv2 */
 506         hmac_md5_init_limK_to_64(ses->ntlmv2_hash, 16, &context);
 507         hmac_md5_update(resp_buf, 16, &context);
 508         hmac_md5_final(ses->auth_key.data.ntlmv2.key, &context);
 509
 510         memcpy(&ses->auth_key.data.ntlmv2.resp, resp_buf,
 511                sizeof(struct ntlmv2_resp));
 512         ses->auth_key.len = 16 + sizeof(struct ntlmv2_resp);
 513
 514         return 0;
 515
 516 setup_ntlmv2_rsp_ret:
 517         kfree(ses->tiblob);
 518         ses->tiblob = NULL;
 519         ses->tilen = 0;
 520
 521         return rc;
 522 }
 523
 524 void CalcNTLMv2_response(const struct cifsSesInfo *ses,
 525                          char *v2_session_response)
 526 {
 527         struct HMACMD5Context context;
 528         /* rest of v2 struct already generated */
 529         memcpy(v2_session_response + 8, ses->cryptKey, 8);
 530         hmac_md5_init_limK_to_64(ses->ntlmv2_hash, 16, &context);
 531
 532         hmac_md5_update(v2_session_response+8,
 533                         sizeof(struct ntlmv2_resp) - 8, &context);
 534
 535         if (ses->tilen)
 536                 hmac_md5_update(ses->tiblob, ses->tilen, &context);
 537
 538         hmac_md5_final(v2_session_response, &context);
 539 /*      cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); */
 540 }