libcli/smb/smb2_signing.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    SMB2 signing
   4
   5    Copyright (C) Stefan Metzmacher 2009
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program 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 the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22 #include "system/filesys.h"
  23 #include "../libcli/smb/smb_common.h"
  24 #include "../lib/crypto/crypto.h"
  25
  26 NTSTATUS smb2_signing_sign_pdu(DATA_BLOB signing_key,
  27                                enum protocol_types protocol,
  28                                struct iovec *vector,
  29                                int count)
  30 {
  31         uint8_t *hdr;
  32         uint64_t session_id;
  33         uint8_t res[16];
  34         int i;
  35
  36         if (count < 2) {
  37                 return NT_STATUS_INVALID_PARAMETER;
  38         }
  39
  40         if (vector[0].iov_len != SMB2_HDR_BODY) {
  41                 return NT_STATUS_INVALID_PARAMETER;
  42         }
  43
  44         hdr = (uint8_t *)vector[0].iov_base;
  45
  46         session_id = BVAL(hdr, SMB2_HDR_SESSION_ID);
  47         if (session_id == 0) {
  48                 /*
  49                  * do not sign messages with a zero session_id.
  50                  * See MS-SMB2 3.2.4.1.1
  51                  */
  52                 return NT_STATUS_OK;
  53         }
  54
  55         if (signing_key.length == 0) {
  56                 DEBUG(2,("Wrong session key length %u for SMB2 signing\n",
  57                          (unsigned)signing_key.length));
  58                 return NT_STATUS_ACCESS_DENIED;
  59         }
  60
  61         memset(hdr + SMB2_HDR_SIGNATURE, 0, 16);
  62
  63         SIVAL(hdr, SMB2_HDR_FLAGS, IVAL(hdr, SMB2_HDR_FLAGS) | SMB2_HDR_FLAG_SIGNED);
  64
  65         if (protocol >= PROTOCOL_SMB2_24) {
  66                 struct aes_cmac_128_context ctx;
  67                 uint8_t key[AES_BLOCK_SIZE];
  68
  69                 ZERO_STRUCT(key);
  70                 memcpy(key, signing_key.data, MIN(signing_key.length, 16));
  71
  72                 aes_cmac_128_init(&ctx, key);
  73                 for (i=0; i < count; i++) {
  74                         aes_cmac_128_update(&ctx,
  75                                         (const uint8_t *)vector[i].iov_base,
  76                                         vector[i].iov_len);
  77                 }
  78                 aes_cmac_128_final(&ctx, res);
  79         } else {
  80                 struct HMACSHA256Context m;
  81                 uint8_t digest[SHA256_DIGEST_LENGTH];
  82
  83                 ZERO_STRUCT(m);
  84                 hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
  85                 for (i=0; i < count; i++) {
  86                         hmac_sha256_update((const uint8_t *)vector[i].iov_base,
  87                                            vector[i].iov_len, &m);
  88                 }
  89                 hmac_sha256_final(digest, &m);
  90                 memcpy(res, digest, 16);
  91         }
  92         DEBUG(5,("signed SMB2 message\n"));
  93
  94         memcpy(hdr + SMB2_HDR_SIGNATURE, res, 16);
  95
  96         return NT_STATUS_OK;
  97 }
  98
  99 NTSTATUS smb2_signing_check_pdu(DATA_BLOB signing_key,
 100                                 enum protocol_types protocol,
 101                                 const struct iovec *vector,
 102                                 int count)
 103 {
 104         const uint8_t *hdr;
 105         const uint8_t *sig;
 106         uint64_t session_id;
 107         uint8_t res[16];
 108         static const uint8_t zero_sig[16] = { 0, };
 109         int i;
 110
 111         if (count < 2) {
 112                 return NT_STATUS_INVALID_PARAMETER;
 113         }
 114
 115         if (vector[0].iov_len != SMB2_HDR_BODY) {
 116                 return NT_STATUS_INVALID_PARAMETER;
 117         }
 118
 119         hdr = (const uint8_t *)vector[0].iov_base;
 120
 121         session_id = BVAL(hdr, SMB2_HDR_SESSION_ID);
 122         if (session_id == 0) {
 123                 /*
 124                  * do not sign messages with a zero session_id.
 125                  * See MS-SMB2 3.2.4.1.1
 126                  */
 127                 return NT_STATUS_OK;
 128         }
 129
 130         if (signing_key.length == 0) {
 131                 /* we don't have the session key yet */
 132                 return NT_STATUS_OK;
 133         }
 134
 135         sig = hdr+SMB2_HDR_SIGNATURE;
 136
 137         if (protocol >= PROTOCOL_SMB2_24) {
 138                 struct aes_cmac_128_context ctx;
 139                 uint8_t key[AES_BLOCK_SIZE];
 140
 141                 ZERO_STRUCT(key);
 142                 memcpy(key, signing_key.data, MIN(signing_key.length, 16));
 143
 144                 aes_cmac_128_init(&ctx, key);
 145                 aes_cmac_128_update(&ctx, hdr, SMB2_HDR_SIGNATURE);
 146                 aes_cmac_128_update(&ctx, zero_sig, 16);
 147                 for (i=1; i < count; i++) {
 148                         aes_cmac_128_update(&ctx,
 149                                         (const uint8_t *)vector[i].iov_base,
 150                                         vector[i].iov_len);
 151                 }
 152                 aes_cmac_128_final(&ctx, res);
 153         } else {
 154                 struct HMACSHA256Context m;
 155                 uint8_t digest[SHA256_DIGEST_LENGTH];
 156
 157                 ZERO_STRUCT(m);
 158                 hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
 159                 hmac_sha256_update(hdr, SMB2_HDR_SIGNATURE, &m);
 160                 hmac_sha256_update(zero_sig, 16, &m);
 161                 for (i=1; i < count; i++) {
 162                         hmac_sha256_update((const uint8_t *)vector[i].iov_base,
 163                                            vector[i].iov_len, &m);
 164                 }
 165                 hmac_sha256_final(digest, &m);
 166                 memcpy(res, digest, 16);
 167         }
 168
 169         if (memcmp(res, sig, 16) != 0) {
 170                 DEBUG(0,("Bad SMB2 signature for message\n"));
 171                 dump_data(0, sig, 16);
 172                 dump_data(0, res, 16);
 173                 return NT_STATUS_ACCESS_DENIED;
 174         }
 175
 176         return NT_STATUS_OK;
 177 }
 178
 179 void smb2_key_derivation(const uint8_t *KI, size_t KI_len,
 180                          const uint8_t *Label, size_t Label_len,
 181                          const uint8_t *Context, size_t Context_len,
 182                          uint8_t KO[16])
 183 {
 184         struct HMACSHA256Context ctx;
 185         uint8_t buf[4];
 186         static const uint8_t zero = 0;
 187         uint8_t digest[SHA256_DIGEST_LENGTH];
 188         uint32_t i = 1;
 189         uint32_t L = 128;
 190
 191         /*
 192          * a simplified version of
 193          * "NIST Special Publication 800-108" section 5.1
 194          * using hmac-sha256.
 195          */
 196         hmac_sha256_init(KI, KI_len, &ctx);
 197
 198         RSIVAL(buf, 0, i);
 199         hmac_sha256_update(buf, sizeof(buf), &ctx);
 200         hmac_sha256_update(Label, Label_len, &ctx);
 201         hmac_sha256_update(&zero, 1, &ctx);
 202         hmac_sha256_update(Context, Context_len, &ctx);
 203         RSIVAL(buf, 0, L);
 204         hmac_sha256_update(buf, sizeof(buf), &ctx);
 205
 206         hmac_sha256_final(digest, &ctx);
 207
 208         memcpy(KO, digest, 16);
 209 }
 210
 211 NTSTATUS smb2_signing_encrypt_pdu(DATA_BLOB encryption_key,
 212                                   uint16_t cipher_id,
 213                                   struct iovec *vector,
 214                                   int count)
 215 {
 216         uint8_t *tf;
 217         uint8_t sig[16];
 218         int i;
 219         size_t a_total;
 220         size_t m_total = 0;
 221         union {
 222                 struct aes_ccm_128_context ccm;
 223                 struct aes_gcm_128_context gcm;
 224         } c;
 225         uint8_t key[AES_BLOCK_SIZE];
 226
 227         if (count < 1) {
 228                 return NT_STATUS_INVALID_PARAMETER;
 229         }
 230
 231         if (vector[0].iov_len != SMB2_TF_HDR_SIZE) {
 232                 return NT_STATUS_INVALID_PARAMETER;
 233         }
 234
 235         tf = (uint8_t *)vector[0].iov_base;
 236
 237         if (encryption_key.length == 0) {
 238                 DEBUG(2,("Wrong encryption key length %u for SMB2 signing\n",
 239                          (unsigned)encryption_key.length));
 240                 return NT_STATUS_ACCESS_DENIED;
 241         }
 242
 243         a_total = SMB2_TF_HDR_SIZE - SMB2_TF_NONCE;
 244         for (i=1; i < count; i++) {
 245                 m_total += vector[i].iov_len;
 246         }
 247
 248         SSVAL(tf, SMB2_TF_FLAGS, SMB2_TF_FLAGS_ENCRYPTED);
 249         SIVAL(tf, SMB2_TF_MSG_SIZE, m_total);
 250
 251         ZERO_STRUCT(key);
 252         memcpy(key, encryption_key.data,
 253                MIN(encryption_key.length, AES_BLOCK_SIZE));
 254
 255         switch (cipher_id) {
 256         case SMB2_ENCRYPTION_AES128_CCM:
 257                 aes_ccm_128_init(&c.ccm, key,
 258                                  tf + SMB2_TF_NONCE,
 259                                  a_total, m_total);
 260                 memset(tf + SMB2_TF_NONCE + AES_CCM_128_NONCE_SIZE, 0,
 261                        16 - AES_CCM_128_NONCE_SIZE);
 262                 aes_ccm_128_update(&c.ccm, tf + SMB2_TF_NONCE, a_total);
 263                 for (i=1; i < count; i++) {
 264                         aes_ccm_128_update(&c.ccm,
 265                                         (const uint8_t *)vector[i].iov_base,
 266                                         vector[i].iov_len);
 267                         aes_ccm_128_crypt(&c.ccm,
 268                                         (uint8_t *)vector[i].iov_base,
 269                                         vector[i].iov_len);
 270                 }
 271                 aes_ccm_128_digest(&c.ccm, sig);
 272                 break;
 273
 274         case SMB2_ENCRYPTION_AES128_GCM:
 275                 aes_gcm_128_init(&c.gcm, key, tf + SMB2_TF_NONCE);
 276                 memset(tf + SMB2_TF_NONCE + AES_GCM_128_IV_SIZE, 0,
 277                        16 - AES_GCM_128_IV_SIZE);
 278                 aes_gcm_128_updateA(&c.gcm, tf + SMB2_TF_NONCE, a_total);
 279                 for (i=1; i < count; i++) {
 280                         aes_gcm_128_crypt(&c.gcm,
 281                                         (uint8_t *)vector[i].iov_base,
 282                                         vector[i].iov_len);
 283                         aes_gcm_128_updateC(&c.gcm,
 284                                         (const uint8_t *)vector[i].iov_base,
 285                                         vector[i].iov_len);
 286                 }
 287                 aes_gcm_128_digest(&c.gcm, sig);
 288                 break;
 289
 290         default:
 291                 ZERO_STRUCT(key);
 292                 return NT_STATUS_INVALID_PARAMETER;
 293         }
 294         ZERO_STRUCT(key);
 295
 296         memcpy(tf + SMB2_TF_SIGNATURE, sig, 16);
 297
 298         DEBUG(5,("encrypt SMB2 message\n"));
 299
 300         return NT_STATUS_OK;
 301 }
 302
 303 NTSTATUS smb2_signing_decrypt_pdu(DATA_BLOB decryption_key,
 304                                   uint16_t cipher_id,
 305                                   struct iovec *vector,
 306                                   int count)
 307 {
 308         uint8_t *tf;
 309         uint16_t flags;
 310         uint8_t *sig_ptr = NULL;
 311         uint8_t sig[16];
 312         int i;
 313         size_t a_total;
 314         size_t m_total = 0;
 315         uint32_t msg_size = 0;
 316         union {
 317                 struct aes_ccm_128_context ccm;
 318                 struct aes_gcm_128_context gcm;
 319         } c;
 320         uint8_t key[AES_BLOCK_SIZE];
 321
 322         if (count < 1) {
 323                 return NT_STATUS_INVALID_PARAMETER;
 324         }
 325
 326         if (vector[0].iov_len != SMB2_TF_HDR_SIZE) {
 327                 return NT_STATUS_INVALID_PARAMETER;
 328         }
 329
 330         tf = (uint8_t *)vector[0].iov_base;
 331
 332         if (decryption_key.length == 0) {
 333                 DEBUG(2,("Wrong decryption key length %u for SMB2 signing\n",
 334                          (unsigned)decryption_key.length));
 335                 return NT_STATUS_ACCESS_DENIED;
 336         }
 337
 338         a_total = SMB2_TF_HDR_SIZE - SMB2_TF_NONCE;
 339         for (i=1; i < count; i++) {
 340                 m_total += vector[i].iov_len;
 341         }
 342
 343         flags = SVAL(tf, SMB2_TF_FLAGS);
 344         msg_size = IVAL(tf, SMB2_TF_MSG_SIZE);
 345
 346         if (flags != SMB2_TF_FLAGS_ENCRYPTED) {
 347                 return NT_STATUS_ACCESS_DENIED;
 348         }
 349
 350         if (msg_size != m_total) {
 351                 return NT_STATUS_INTERNAL_ERROR;
 352         }
 353
 354         ZERO_STRUCT(key);
 355         memcpy(key, decryption_key.data,
 356                MIN(decryption_key.length, AES_BLOCK_SIZE));
 357
 358         switch (cipher_id) {
 359         case SMB2_ENCRYPTION_AES128_CCM:
 360                 aes_ccm_128_init(&c.ccm, key,
 361                                  tf + SMB2_TF_NONCE,
 362                                  a_total, m_total);
 363                 aes_ccm_128_update(&c.ccm, tf + SMB2_TF_NONCE, a_total);
 364                 for (i=1; i < count; i++) {
 365                         aes_ccm_128_crypt(&c.ccm,
 366                                         (uint8_t *)vector[i].iov_base,
 367                                         vector[i].iov_len);
 368                         aes_ccm_128_update(&c.ccm,
 369                                         ( uint8_t *)vector[i].iov_base,
 370                                         vector[i].iov_len);
 371                 }
 372                 aes_ccm_128_digest(&c.ccm, sig);
 373                 break;
 374
 375         case SMB2_ENCRYPTION_AES128_GCM:
 376                 aes_gcm_128_init(&c.gcm, key, tf + SMB2_TF_NONCE);
 377                 aes_gcm_128_updateA(&c.gcm, tf + SMB2_TF_NONCE, a_total);
 378                 for (i=1; i < count; i++) {
 379                         aes_gcm_128_updateC(&c.gcm,
 380                                         (const uint8_t *)vector[i].iov_base,
 381                                         vector[i].iov_len);
 382                         aes_gcm_128_crypt(&c.gcm,
 383                                         (uint8_t *)vector[i].iov_base,
 384                                         vector[i].iov_len);
 385                 }
 386                 aes_gcm_128_digest(&c.gcm, sig);
 387                 break;
 388
 389         default:
 390                 ZERO_STRUCT(key);
 391                 return NT_STATUS_INVALID_PARAMETER;
 392         }
 393         ZERO_STRUCT(key);
 394
 395         sig_ptr = tf + SMB2_TF_SIGNATURE;
 396         if (memcmp(sig_ptr, sig, 16) != 0) {
 397                 return NT_STATUS_ACCESS_DENIED;
 398         }
 399
 400         DEBUG(5,("decrypt SMB2 message\n"));
 401
 402         return NT_STATUS_OK;
 403 }