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 #include "lib/util/iov_buf.h"
  26
  27 NTSTATUS smb2_signing_sign_pdu(DATA_BLOB signing_key,
  28                                enum protocol_types protocol,
  29                                struct iovec *vector,
  30                                int count)
  31 {
  32         uint8_t *hdr;
  33         uint64_t session_id;
  34         uint8_t res[16];
  35         int i;
  36
  37         if (count < 2) {
  38                 return NT_STATUS_INVALID_PARAMETER;
  39         }
  40
  41         if (vector[0].iov_len != SMB2_HDR_BODY) {
  42                 return NT_STATUS_INVALID_PARAMETER;
  43         }
  44
  45         hdr = (uint8_t *)vector[0].iov_base;
  46
  47         session_id = BVAL(hdr, SMB2_HDR_SESSION_ID);
  48         if (session_id == 0) {
  49                 /*
  50                  * do not sign messages with a zero session_id.
  51                  * See MS-SMB2 3.2.4.1.1
  52                  */
  53                 return NT_STATUS_OK;
  54         }
  55
  56         if (signing_key.length == 0) {
  57                 DEBUG(2,("Wrong session key length %u for SMB2 signing\n",
  58                          (unsigned)signing_key.length));
  59                 return NT_STATUS_ACCESS_DENIED;
  60         }
  61
  62         memset(hdr + SMB2_HDR_SIGNATURE, 0, 16);
  63
  64         SIVAL(hdr, SMB2_HDR_FLAGS, IVAL(hdr, SMB2_HDR_FLAGS) | SMB2_HDR_FLAG_SIGNED);
  65
  66         if (protocol >= PROTOCOL_SMB2_24) {
  67                 struct aes_cmac_128_context ctx;
  68                 uint8_t key[AES_BLOCK_SIZE] = {0};
  69
  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
  80                 ZERO_ARRAY(key);
  81         } else {
  82                 struct HMACSHA256Context m;
  83                 uint8_t digest[SHA256_DIGEST_LENGTH];
  84
  85                 ZERO_STRUCT(m);
  86                 hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
  87                 for (i=0; i < count; i++) {
  88                         hmac_sha256_update((const uint8_t *)vector[i].iov_base,
  89                                            vector[i].iov_len, &m);
  90                 }
  91                 hmac_sha256_final(digest, &m);
  92                 memcpy(res, digest, 16);
  93         }
  94         DEBUG(5,("signed SMB2 message\n"));
  95
  96         memcpy(hdr + SMB2_HDR_SIGNATURE, res, 16);
  97
  98         return NT_STATUS_OK;
  99 }
 100
 101 NTSTATUS smb2_signing_check_pdu(DATA_BLOB signing_key,
 102                                 enum protocol_types protocol,
 103                                 const struct iovec *vector,
 104                                 int count)
 105 {
 106         const uint8_t *hdr;
 107         const uint8_t *sig;
 108         uint64_t session_id;
 109         uint8_t res[16];
 110         static const uint8_t zero_sig[16] = { 0, };
 111         int i;
 112
 113         if (count < 2) {
 114                 return NT_STATUS_INVALID_PARAMETER;
 115         }
 116
 117         if (vector[0].iov_len != SMB2_HDR_BODY) {
 118                 return NT_STATUS_INVALID_PARAMETER;
 119         }
 120
 121         hdr = (const uint8_t *)vector[0].iov_base;
 122
 123         session_id = BVAL(hdr, SMB2_HDR_SESSION_ID);
 124         if (session_id == 0) {
 125                 /*
 126                  * do not sign messages with a zero session_id.
 127                  * See MS-SMB2 3.2.4.1.1
 128                  */
 129                 return NT_STATUS_OK;
 130         }
 131
 132         if (signing_key.length == 0) {
 133                 /* we don't have the session key yet */
 134                 return NT_STATUS_OK;
 135         }
 136
 137         sig = hdr+SMB2_HDR_SIGNATURE;
 138
 139         if (protocol >= PROTOCOL_SMB2_24) {
 140                 struct aes_cmac_128_context ctx;
 141                 uint8_t key[AES_BLOCK_SIZE] = {0};
 142
 143                 memcpy(key, signing_key.data, MIN(signing_key.length, 16));
 144
 145                 aes_cmac_128_init(&ctx, key);
 146                 aes_cmac_128_update(&ctx, hdr, SMB2_HDR_SIGNATURE);
 147                 aes_cmac_128_update(&ctx, zero_sig, 16);
 148                 for (i=1; i < count; i++) {
 149                         aes_cmac_128_update(&ctx,
 150                                         (const uint8_t *)vector[i].iov_base,
 151                                         vector[i].iov_len);
 152                 }
 153                 aes_cmac_128_final(&ctx, res);
 154
 155                 ZERO_ARRAY(key);
 156         } else {
 157                 struct HMACSHA256Context m;
 158                 uint8_t digest[SHA256_DIGEST_LENGTH];
 159
 160                 ZERO_STRUCT(m);
 161                 hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
 162                 hmac_sha256_update(hdr, SMB2_HDR_SIGNATURE, &m);
 163                 hmac_sha256_update(zero_sig, 16, &m);
 164                 for (i=1; i < count; i++) {
 165                         hmac_sha256_update((const uint8_t *)vector[i].iov_base,
 166                                            vector[i].iov_len, &m);
 167                 }
 168                 hmac_sha256_final(digest, &m);
 169                 memcpy(res, digest, 16);
 170         }
 171
 172         if (memcmp_const_time(res, sig, 16) != 0) {
 173                 DEBUG(0,("Bad SMB2 signature for message\n"));
 174                 dump_data(0, sig, 16);
 175                 dump_data(0, res, 16);
 176                 return NT_STATUS_ACCESS_DENIED;
 177         }
 178
 179         return NT_STATUS_OK;
 180 }
 181
 182 void smb2_key_derivation(const uint8_t *KI, size_t KI_len,
 183                          const uint8_t *Label, size_t Label_len,
 184                          const uint8_t *Context, size_t Context_len,
 185                          uint8_t KO[16])
 186 {
 187         struct HMACSHA256Context ctx;
 188         uint8_t buf[4];
 189         static const uint8_t zero = 0;
 190         uint8_t digest[SHA256_DIGEST_LENGTH];
 191         uint32_t i = 1;
 192         uint32_t L = 128;
 193
 194         /*
 195          * a simplified version of
 196          * "NIST Special Publication 800-108" section 5.1
 197          * using hmac-sha256.
 198          */
 199         hmac_sha256_init(KI, KI_len, &ctx);
 200
 201         RSIVAL(buf, 0, i);
 202         hmac_sha256_update(buf, sizeof(buf), &ctx);
 203         hmac_sha256_update(Label, Label_len, &ctx);
 204         hmac_sha256_update(&zero, 1, &ctx);
 205         hmac_sha256_update(Context, Context_len, &ctx);
 206         RSIVAL(buf, 0, L);
 207         hmac_sha256_update(buf, sizeof(buf), &ctx);
 208
 209         hmac_sha256_final(digest, &ctx);
 210
 211         memcpy(KO, digest, 16);
 212 }
 213
 214 NTSTATUS smb2_signing_encrypt_pdu(DATA_BLOB encryption_key,
 215                                   uint16_t cipher_id,
 216                                   struct iovec *vector,
 217                                   int count)
 218 {
 219         uint8_t *tf;
 220         uint8_t sig[16];
 221         int i;
 222         size_t a_total;
 223         ssize_t m_total;
 224         union {
 225                 struct aes_ccm_128_context ccm;
 226                 struct aes_gcm_128_context gcm;
 227         } c;
 228         uint8_t key[AES_BLOCK_SIZE];
 229
 230         if (count < 1) {
 231                 return NT_STATUS_INVALID_PARAMETER;
 232         }
 233
 234         if (vector[0].iov_len != SMB2_TF_HDR_SIZE) {
 235                 return NT_STATUS_INVALID_PARAMETER;
 236         }
 237
 238         tf = (uint8_t *)vector[0].iov_base;
 239
 240         if (encryption_key.length == 0) {
 241                 DEBUG(2,("Wrong encryption key length %u for SMB2 signing\n",
 242                          (unsigned)encryption_key.length));
 243                 return NT_STATUS_ACCESS_DENIED;
 244         }
 245
 246         a_total = SMB2_TF_HDR_SIZE - SMB2_TF_NONCE;
 247
 248         m_total = iov_buflen(&vector[1], count-1);
 249         if (m_total == -1) {
 250                 return NT_STATUS_BUFFER_TOO_SMALL;
 251         }
 252
 253         SSVAL(tf, SMB2_TF_FLAGS, SMB2_TF_FLAGS_ENCRYPTED);
 254         SIVAL(tf, SMB2_TF_MSG_SIZE, m_total);
 255
 256         ZERO_STRUCT(key);
 257         memcpy(key, encryption_key.data,
 258                MIN(encryption_key.length, AES_BLOCK_SIZE));
 259
 260         switch (cipher_id) {
 261         case SMB2_ENCRYPTION_AES128_CCM:
 262                 aes_ccm_128_init(&c.ccm, key,
 263                                  tf + SMB2_TF_NONCE,
 264                                  a_total, m_total);
 265                 memset(tf + SMB2_TF_NONCE + AES_CCM_128_NONCE_SIZE, 0,
 266                        16 - AES_CCM_128_NONCE_SIZE);
 267                 aes_ccm_128_update(&c.ccm, tf + SMB2_TF_NONCE, a_total);
 268                 for (i=1; i < count; i++) {
 269                         aes_ccm_128_update(&c.ccm,
 270                                         (const uint8_t *)vector[i].iov_base,
 271                                         vector[i].iov_len);
 272                         aes_ccm_128_crypt(&c.ccm,
 273                                         (uint8_t *)vector[i].iov_base,
 274                                         vector[i].iov_len);
 275                 }
 276                 aes_ccm_128_digest(&c.ccm, sig);
 277                 break;
 278
 279         case SMB2_ENCRYPTION_AES128_GCM:
 280                 aes_gcm_128_init(&c.gcm, key, tf + SMB2_TF_NONCE);
 281                 memset(tf + SMB2_TF_NONCE + AES_GCM_128_IV_SIZE, 0,
 282                        16 - AES_GCM_128_IV_SIZE);
 283                 aes_gcm_128_updateA(&c.gcm, tf + SMB2_TF_NONCE, a_total);
 284                 for (i=1; i < count; i++) {
 285                         aes_gcm_128_crypt(&c.gcm,
 286                                         (uint8_t *)vector[i].iov_base,
 287                                         vector[i].iov_len);
 288                         aes_gcm_128_updateC(&c.gcm,
 289                                         (const uint8_t *)vector[i].iov_base,
 290                                         vector[i].iov_len);
 291                 }
 292                 aes_gcm_128_digest(&c.gcm, sig);
 293                 break;
 294
 295         default:
 296                 ZERO_STRUCT(key);
 297                 return NT_STATUS_INVALID_PARAMETER;
 298         }
 299         ZERO_STRUCT(key);
 300
 301         memcpy(tf + SMB2_TF_SIGNATURE, sig, 16);
 302
 303         DEBUG(5,("encrypt SMB2 message\n"));
 304
 305         return NT_STATUS_OK;
 306 }
 307
 308 NTSTATUS smb2_signing_decrypt_pdu(DATA_BLOB decryption_key,
 309                                   uint16_t cipher_id,
 310                                   struct iovec *vector,
 311                                   int count)
 312 {
 313         uint8_t *tf;
 314         uint16_t flags;
 315         uint8_t *sig_ptr = NULL;
 316         uint8_t sig[16];
 317         int i;
 318         size_t a_total;
 319         ssize_t m_total;
 320         uint32_t msg_size = 0;
 321         union {
 322                 struct aes_ccm_128_context ccm;
 323                 struct aes_gcm_128_context gcm;
 324         } c;
 325         uint8_t key[AES_BLOCK_SIZE];
 326
 327         if (count < 1) {
 328                 return NT_STATUS_INVALID_PARAMETER;
 329         }
 330
 331         if (vector[0].iov_len != SMB2_TF_HDR_SIZE) {
 332                 return NT_STATUS_INVALID_PARAMETER;
 333         }
 334
 335         tf = (uint8_t *)vector[0].iov_base;
 336
 337         if (decryption_key.length == 0) {
 338                 DEBUG(2,("Wrong decryption key length %u for SMB2 signing\n",
 339                          (unsigned)decryption_key.length));
 340                 return NT_STATUS_ACCESS_DENIED;
 341         }
 342
 343         a_total = SMB2_TF_HDR_SIZE - SMB2_TF_NONCE;
 344
 345         m_total = iov_buflen(&vector[1], count-1);
 346         if (m_total == -1) {
 347                 return NT_STATUS_BUFFER_TOO_SMALL;
 348         }
 349
 350         flags = SVAL(tf, SMB2_TF_FLAGS);
 351         msg_size = IVAL(tf, SMB2_TF_MSG_SIZE);
 352
 353         if (flags != SMB2_TF_FLAGS_ENCRYPTED) {
 354                 return NT_STATUS_ACCESS_DENIED;
 355         }
 356
 357         if (msg_size != m_total) {
 358                 return NT_STATUS_INTERNAL_ERROR;
 359         }
 360
 361         ZERO_STRUCT(key);
 362         memcpy(key, decryption_key.data,
 363                MIN(decryption_key.length, AES_BLOCK_SIZE));
 364
 365         switch (cipher_id) {
 366         case SMB2_ENCRYPTION_AES128_CCM:
 367                 aes_ccm_128_init(&c.ccm, key,
 368                                  tf + SMB2_TF_NONCE,
 369                                  a_total, m_total);
 370                 aes_ccm_128_update(&c.ccm, tf + SMB2_TF_NONCE, a_total);
 371                 for (i=1; i < count; i++) {
 372                         aes_ccm_128_crypt(&c.ccm,
 373                                         (uint8_t *)vector[i].iov_base,
 374                                         vector[i].iov_len);
 375                         aes_ccm_128_update(&c.ccm,
 376                                         ( uint8_t *)vector[i].iov_base,
 377                                         vector[i].iov_len);
 378                 }
 379                 aes_ccm_128_digest(&c.ccm, sig);
 380                 break;
 381
 382         case SMB2_ENCRYPTION_AES128_GCM:
 383                 aes_gcm_128_init(&c.gcm, key, tf + SMB2_TF_NONCE);
 384                 aes_gcm_128_updateA(&c.gcm, tf + SMB2_TF_NONCE, a_total);
 385                 for (i=1; i < count; i++) {
 386                         aes_gcm_128_updateC(&c.gcm,
 387                                         (const uint8_t *)vector[i].iov_base,
 388                                         vector[i].iov_len);
 389                         aes_gcm_128_crypt(&c.gcm,
 390                                         (uint8_t *)vector[i].iov_base,
 391                                         vector[i].iov_len);
 392                 }
 393                 aes_gcm_128_digest(&c.gcm, sig);
 394                 break;
 395
 396         default:
 397                 ZERO_STRUCT(key);
 398                 return NT_STATUS_INVALID_PARAMETER;
 399         }
 400         ZERO_STRUCT(key);
 401
 402         sig_ptr = tf + SMB2_TF_SIGNATURE;
 403         if (memcmp(sig_ptr, sig, 16) != 0) {
 404                 return NT_STATUS_ACCESS_DENIED;
 405         }
 406
 407         DEBUG(5,("decrypt SMB2 message\n"));
 408
 409         return NT_STATUS_OK;
 410 }