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