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];
  69
  70                 ZERO_STRUCT(key);
  71                 memcpy(key, signing_key.data, MIN(signing_key.length, 16));
  72
  73                 aes_cmac_128_init(&ctx, key);
  74                 for (i=0; i < count; i++) {
  75                         aes_cmac_128_update(&ctx,
  76                                         (const uint8_t *)vector[i].iov_base,
  77                                         vector[i].iov_len);
  78                 }
  79                 aes_cmac_128_final(&ctx, res);
  80         } else {
  81                 struct HMACSHA256Context m;
  82                 uint8_t digest[SHA256_DIGEST_LENGTH];
  83
  84                 ZERO_STRUCT(m);
  85                 hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
  86                 for (i=0; i < count; i++) {
  87                         hmac_sha256_update((const uint8_t *)vector[i].iov_base,
  88                                            vector[i].iov_len, &m);
  89                 }
  90                 hmac_sha256_final(digest, &m);
  91                 memcpy(res, digest, 16);
  92         }
  93         DEBUG(5,("signed SMB2 message\n"));
  94
  95         memcpy(hdr + SMB2_HDR_SIGNATURE, res, 16);
  96
  97         return NT_STATUS_OK;
  98 }
  99
 100 NTSTATUS smb2_signing_check_pdu(DATA_BLOB signing_key,
 101                                 enum protocol_types protocol,
 102                                 const struct iovec *vector,
 103                                 int count)
 104 {
 105         const uint8_t *hdr;
 106         const uint8_t *sig;
 107         uint64_t session_id;
 108         uint8_t res[16];
 109         static const uint8_t zero_sig[16] = { 0, };
 110         int i;
 111
 112         if (count < 2) {
 113                 return NT_STATUS_INVALID_PARAMETER;
 114         }
 115
 116         if (vector[0].iov_len != SMB2_HDR_BODY) {
 117                 return NT_STATUS_INVALID_PARAMETER;
 118         }
 119
 120         hdr = (const uint8_t *)vector[0].iov_base;
 121
 122         session_id = BVAL(hdr, SMB2_HDR_SESSION_ID);
 123         if (session_id == 0) {
 124                 /*
 125                  * do not sign messages with a zero session_id.
 126                  * See MS-SMB2 3.2.4.1.1
 127                  */
 128                 return NT_STATUS_OK;
 129         }
 130
 131         if (signing_key.length == 0) {
 132                 /* we don't have the session key yet */
 133                 return NT_STATUS_OK;
 134         }
 135
 136         sig = hdr+SMB2_HDR_SIGNATURE;
 137
 138         if (protocol >= PROTOCOL_SMB2_24) {
 139                 struct aes_cmac_128_context ctx;
 140                 uint8_t key[AES_BLOCK_SIZE];
 141
 142                 ZERO_STRUCT(key);
 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         } else {
 155                 struct HMACSHA256Context m;
 156                 uint8_t digest[SHA256_DIGEST_LENGTH];
 157
 158                 ZERO_STRUCT(m);
 159                 hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
 160                 hmac_sha256_update(hdr, SMB2_HDR_SIGNATURE, &m);
 161                 hmac_sha256_update(zero_sig, 16, &m);
 162                 for (i=1; i < count; i++) {
 163                         hmac_sha256_update((const uint8_t *)vector[i].iov_base,
 164                                            vector[i].iov_len, &m);
 165                 }
 166                 hmac_sha256_final(digest, &m);
 167                 memcpy(res, digest, 16);
 168         }
 169
 170         if (memcmp(res, sig, 16) != 0) {
 171                 DEBUG(0,("Bad SMB2 signature for message\n"));
 172                 dump_data(0, sig, 16);
 173                 dump_data(0, res, 16);
 174                 return NT_STATUS_ACCESS_DENIED;
 175         }
 176
 177         return NT_STATUS_OK;
 178 }
 179
 180 void smb2_key_derivation(const uint8_t *KI, size_t KI_len,
 181                          const uint8_t *Label, size_t Label_len,
 182                          const uint8_t *Context, size_t Context_len,
 183                          uint8_t KO[16])
 184 {
 185         struct HMACSHA256Context ctx;
 186         uint8_t buf[4];
 187         static const uint8_t zero = 0;
 188         uint8_t digest[SHA256_DIGEST_LENGTH];
 189         uint32_t i = 1;
 190         uint32_t L = 128;
 191
 192         /*
 193          * a simplified version of
 194          * "NIST Special Publication 800-108" section 5.1
 195          * using hmac-sha256.
 196          */
 197         hmac_sha256_init(KI, KI_len, &ctx);
 198
 199         RSIVAL(buf, 0, i);
 200         hmac_sha256_update(buf, sizeof(buf), &ctx);
 201         hmac_sha256_update(Label, Label_len, &ctx);
 202         hmac_sha256_update(&zero, 1, &ctx);
 203         hmac_sha256_update(Context, Context_len, &ctx);
 204         RSIVAL(buf, 0, L);
 205         hmac_sha256_update(buf, sizeof(buf), &ctx);
 206
 207         hmac_sha256_final(digest, &ctx);
 208
 209         memcpy(KO, digest, 16);
 210 }
 211
 212 NTSTATUS smb2_signing_encrypt_pdu(DATA_BLOB encryption_key,
 213                                   uint16_t cipher_id,
 214                                   struct iovec *vector,
 215                                   int count)
 216 {
 217         uint8_t *tf;
 218         uint8_t sig[16];
 219         int i;
 220         size_t a_total;
 221         ssize_t m_total;
 222         union {
 223                 struct aes_ccm_128_context ccm;
 224                 struct aes_gcm_128_context gcm;
 225         } c;
 226         uint8_t key[AES_BLOCK_SIZE];
 227
 228         if (count < 1) {
 229                 return NT_STATUS_INVALID_PARAMETER;
 230         }
 231
 232         if (vector[0].iov_len != SMB2_TF_HDR_SIZE) {
 233                 return NT_STATUS_INVALID_PARAMETER;
 234         }
 235
 236         tf = (uint8_t *)vector[0].iov_base;
 237
 238         if (encryption_key.length == 0) {
 239                 DEBUG(2,("Wrong encryption key length %u for SMB2 signing\n",
 240                          (unsigned)encryption_key.length));
 241                 return NT_STATUS_ACCESS_DENIED;
 242         }
 243
 244         a_total = SMB2_TF_HDR_SIZE - SMB2_TF_NONCE;
 245
 246         m_total = iov_buflen(&vector[1], count-1);
 247         if (m_total == -1) {
 248                 return NT_STATUS_BUFFER_TOO_SMALL;
 249         }
 250
 251         SSVAL(tf, SMB2_TF_FLAGS, SMB2_TF_FLAGS_ENCRYPTED);
 252         SIVAL(tf, SMB2_TF_MSG_SIZE, m_total);
 253
 254         ZERO_STRUCT(key);
 255         memcpy(key, encryption_key.data,
 256                MIN(encryption_key.length, AES_BLOCK_SIZE));
 257
 258         switch (cipher_id) {
 259         case SMB2_ENCRYPTION_AES128_CCM:
 260                 aes_ccm_128_init(&c.ccm, key,
 261                                  tf + SMB2_TF_NONCE,
 262                                  a_total, m_total);
 263                 memset(tf + SMB2_TF_NONCE + AES_CCM_128_NONCE_SIZE, 0,
 264                        16 - AES_CCM_128_NONCE_SIZE);
 265                 aes_ccm_128_update(&c.ccm, tf + SMB2_TF_NONCE, a_total);
 266                 for (i=1; i < count; i++) {
 267                         aes_ccm_128_update(&c.ccm,
 268                                         (const uint8_t *)vector[i].iov_base,
 269                                         vector[i].iov_len);
 270                         aes_ccm_128_crypt(&c.ccm,
 271                                         (uint8_t *)vector[i].iov_base,
 272                                         vector[i].iov_len);
 273                 }
 274                 aes_ccm_128_digest(&c.ccm, sig);
 275                 break;
 276
 277         case SMB2_ENCRYPTION_AES128_GCM:
 278                 aes_gcm_128_init(&c.gcm, key, tf + SMB2_TF_NONCE);
 279                 memset(tf + SMB2_TF_NONCE + AES_GCM_128_IV_SIZE, 0,
 280                        16 - AES_GCM_128_IV_SIZE);
 281                 aes_gcm_128_updateA(&c.gcm, tf + SMB2_TF_NONCE, a_total);
 282                 for (i=1; i < count; i++) {
 283                         aes_gcm_128_crypt(&c.gcm,
 284                                         (uint8_t *)vector[i].iov_base,
 285                                         vector[i].iov_len);
 286                         aes_gcm_128_updateC(&c.gcm,
 287                                         (const uint8_t *)vector[i].iov_base,
 288                                         vector[i].iov_len);
 289                 }
 290                 aes_gcm_128_digest(&c.gcm, sig);
 291                 break;
 292
 293         default:
 294                 ZERO_STRUCT(key);
 295                 return NT_STATUS_INVALID_PARAMETER;
 296         }
 297         ZERO_STRUCT(key);
 298
 299         memcpy(tf + SMB2_TF_SIGNATURE, sig, 16);
 300
 301         DEBUG(5,("encrypt SMB2 message\n"));
 302
 303         return NT_STATUS_OK;
 304 }
 305
 306 NTSTATUS smb2_signing_decrypt_pdu(DATA_BLOB decryption_key,
 307                                   uint16_t cipher_id,
 308                                   struct iovec *vector,
 309                                   int count)
 310 {
 311         uint8_t *tf;
 312         uint16_t flags;
 313         uint8_t *sig_ptr = NULL;
 314         uint8_t sig[16];
 315         int i;
 316         size_t a_total;
 317         ssize_t m_total;
 318         uint32_t msg_size = 0;
 319         union {
 320                 struct aes_ccm_128_context ccm;
 321                 struct aes_gcm_128_context gcm;
 322         } c;
 323         uint8_t key[AES_BLOCK_SIZE];
 324
 325         if (count < 1) {
 326                 return NT_STATUS_INVALID_PARAMETER;
 327         }
 328
 329         if (vector[0].iov_len != SMB2_TF_HDR_SIZE) {
 330                 return NT_STATUS_INVALID_PARAMETER;
 331         }
 332
 333         tf = (uint8_t *)vector[0].iov_base;
 334
 335         if (decryption_key.length == 0) {
 336                 DEBUG(2,("Wrong decryption key length %u for SMB2 signing\n",
 337                          (unsigned)decryption_key.length));
 338                 return NT_STATUS_ACCESS_DENIED;
 339         }
 340
 341         a_total = SMB2_TF_HDR_SIZE - SMB2_TF_NONCE;
 342
 343         m_total = iov_buflen(&vector[1], count-1);
 344         if (m_total == -1) {
 345                 return NT_STATUS_BUFFER_TOO_SMALL;
 346         }
 347
 348         flags = SVAL(tf, SMB2_TF_FLAGS);
 349         msg_size = IVAL(tf, SMB2_TF_MSG_SIZE);
 350
 351         if (flags != SMB2_TF_FLAGS_ENCRYPTED) {
 352                 return NT_STATUS_ACCESS_DENIED;
 353         }
 354
 355         if (msg_size != m_total) {
 356                 return NT_STATUS_INTERNAL_ERROR;
 357         }
 358
 359         ZERO_STRUCT(key);
 360         memcpy(key, decryption_key.data,
 361                MIN(decryption_key.length, AES_BLOCK_SIZE));
 362
 363         switch (cipher_id) {
 364         case SMB2_ENCRYPTION_AES128_CCM:
 365                 aes_ccm_128_init(&c.ccm, key,
 366                                  tf + SMB2_TF_NONCE,
 367                                  a_total, m_total);
 368                 aes_ccm_128_update(&c.ccm, tf + SMB2_TF_NONCE, a_total);
 369                 for (i=1; i < count; i++) {
 370                         aes_ccm_128_crypt(&c.ccm,
 371                                         (uint8_t *)vector[i].iov_base,
 372                                         vector[i].iov_len);
 373                         aes_ccm_128_update(&c.ccm,
 374                                         ( uint8_t *)vector[i].iov_base,
 375                                         vector[i].iov_len);
 376                 }
 377                 aes_ccm_128_digest(&c.ccm, sig);
 378                 break;
 379
 380         case SMB2_ENCRYPTION_AES128_GCM:
 381                 aes_gcm_128_init(&c.gcm, key, tf + SMB2_TF_NONCE);
 382                 aes_gcm_128_updateA(&c.gcm, tf + SMB2_TF_NONCE, a_total);
 383                 for (i=1; i < count; i++) {
 384                         aes_gcm_128_updateC(&c.gcm,
 385                                         (const uint8_t *)vector[i].iov_base,
 386                                         vector[i].iov_len);
 387                         aes_gcm_128_crypt(&c.gcm,
 388                                         (uint8_t *)vector[i].iov_base,
 389                                         vector[i].iov_len);
 390                 }
 391                 aes_gcm_128_digest(&c.gcm, sig);
 392                 break;
 393
 394         default:
 395                 ZERO_STRUCT(key);
 396                 return NT_STATUS_INVALID_PARAMETER;
 397         }
 398         ZERO_STRUCT(key);
 399
 400         sig_ptr = tf + SMB2_TF_SIGNATURE;
 401         if (memcmp(sig_ptr, sig, 16) != 0) {
 402                 return NT_STATUS_ACCESS_DENIED;
 403         }
 404
 405         DEBUG(5,("decrypt SMB2 message\n"));
 406
 407         return NT_STATUS_OK;
 408 }