epan/dissectors/asn1/pkcs12/packet-pkcs12-template.c

   1 /* packet-pkcs12.c
   2  * Routines for PKCS#12: Personal Information Exchange packet dissection
   3  * Graeme Lunt 2006
   4  *
   5  * See "PKCS #12 v1.1: Personal Information Exchange Syntax":
   6  *
   7  *    http://www.emc.com/emc-plus/rsa-labs/pkcs/files/h11301-wp-pkcs-12v1-1-personal-information-exchange-syntax.pdf
   8  *
   9  * Wireshark - Network traffic analyzer
  10  * By Gerald Combs <gerald@wireshark.org>
  11  * Copyright 1998 Gerald Combs
  12  *
  13  * SPDX-License-Identifier: GPL-2.0-or-later
  14  */
  15
  16 #include "config.h"
  17
  18 #include <epan/packet.h>
  19 #include <epan/expert.h>
  20 #include <epan/oids.h>
  21 #include <epan/asn1.h>
  22 #include <epan/prefs.h>
  23 #include <wsutil/array.h>
  24
  25 #include "packet-ber.h"
  26 #include "packet-pkcs12.h"
  27 #include "packet-x509af.h"
  28 #include "packet-x509if.h"
  29 #include "packet-cms.h"
  30
  31 #include <wsutil/wsgcrypt.h>
  32
  33 #define PNAME  "PKCS#12: Personal Information Exchange"
  34 #define PSNAME "PKCS12"
  35 #define PFNAME "pkcs12"
  36
  37 #define PKCS12_PBE_ARCFOUR_SHA1_OID     "1.2.840.113549.1.12.1.1"
  38 #define PKCS12_PBE_3DES_SHA1_OID        "1.2.840.113549.1.12.1.3"
  39 #define PKCS12_PBE_RC2_40_SHA1_OID      "1.2.840.113549.1.12.1.6"
  40
  41 void proto_register_pkcs12(void);
  42 void proto_reg_handoff_pkcs12(void);
  43
  44 /* Initialize the protocol and registered fields */
  45 static int proto_pkcs12;
  46
  47 static int hf_pkcs12_X509Certificate_PDU;
  48 static int hf_pkcs12_AuthenticatedSafe_PDU;  /* AuthenticatedSafe */
  49 static int ett_decrypted_pbe;
  50
  51 static expert_field ei_pkcs12_octet_string_expected;
  52
  53
  54 static const char *object_identifier_id;
  55 static int iteration_count;
  56 static tvbuff_t *salt;
  57 static const char *password;
  58 static bool try_null_password;
  59
  60 static int dissect_AuthenticatedSafe_OCTETSTRING_PDU(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data);
  61 static int dissect_SafeContents_OCTETSTRING_PDU(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data);
  62 static int dissect_PrivateKeyInfo_PDU(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data);
  63
  64 #include "packet-pkcs12-hf.c"
  65
  66 /* Initialize the subtree pointers */
  67 #include "packet-pkcs12-ett.c"
  68
  69 static void append_oid(wmem_allocator_t *pool, proto_tree *tree, const char *oid)
  70 {
  71         const char *name = NULL;
  72
  73         name = oid_resolved_from_string(pool, oid);
  74         proto_item_append_text(tree, " (%s)", name ? name : oid);
  75 }
  76
  77 static int
  78 generate_key_or_iv(packet_info *pinfo, unsigned int id, tvbuff_t *salt_tvb, unsigned int iter,
  79                        const char *pw, unsigned int req_keylen, char * keybuf)
  80 {
  81   int rc;
  82   unsigned int i, j;
  83   gcry_md_hd_t md;
  84   gcry_mpi_t num_b1 = NULL;
  85   size_t pwlen;
  86   char hash[20], buf_b[64], buf_i[128], *p;
  87   char *salt_p;
  88   int salt_size;
  89   size_t cur_keylen;
  90   size_t n;
  91   gcry_error_t  err;
  92
  93   cur_keylen = 0;
  94
  95   salt_size = tvb_captured_length(salt_tvb);
  96   salt_p = (char *)tvb_memdup(pinfo->pool, salt_tvb, 0, salt_size);
  97
  98   if (pw == NULL)
  99     pwlen = 0;
 100   else
 101     pwlen = strlen(pw);
 102
 103   if (pwlen > 63 / 2) {
 104     return false;
 105   }
 106
 107   /* Store salt and password in BUF_I */
 108   p = buf_i;
 109   for (i = 0; i < 64; i++)
 110     *p++ = salt_p[i % salt_size];
 111
 112   if (pw) {
 113     for (i = j = 0; i < 64; i += 2) {
 114       *p++ = 0;
 115       *p++ = pw[j];
 116       if (++j > pwlen)  /* Note, that we include the trailing zero */
 117         j = 0;
 118     }
 119   }
 120   else
 121     memset (p, 0, 64);
 122
 123   for (;;) {
 124       err = gcry_md_open(&md, GCRY_MD_SHA1, 0);
 125       if (gcry_err_code(err)) {
 126         return false;
 127       }
 128       for (i = 0; i < 64; i++) {
 129         unsigned char lid = id & 0xFF;
 130         gcry_md_write (md, &lid, 1);
 131       }
 132
 133       gcry_md_write(md, buf_i, pw ? 128 : 64);
 134
 135       gcry_md_final (md);
 136       memcpy (hash, gcry_md_read (md, 0), 20);
 137
 138       gcry_md_close (md);
 139
 140       for (i = 1; i < iter; i++)
 141         gcry_md_hash_buffer (GCRY_MD_SHA1, hash, hash, 20);
 142
 143       for (i = 0; i < 20 && cur_keylen < req_keylen; i++)
 144         keybuf[cur_keylen++] = hash[i];
 145
 146       if (cur_keylen == req_keylen) {
 147         gcry_mpi_release (num_b1);
 148         return true;            /* ready */
 149       }
 150
 151       /* need more bytes. */
 152       for (i = 0; i < 64; i++)
 153         buf_b[i] = hash[i % 20];
 154
 155       n = 64;
 156
 157       rc = gcry_mpi_scan (&num_b1, GCRYMPI_FMT_USG, buf_b, n, &n);
 158
 159       if (rc != 0) {
 160         return false;
 161       }
 162
 163       gcry_mpi_add_ui (num_b1, num_b1, 1);
 164
 165       for (i = 0; i < 128; i += 64) {
 166         gcry_mpi_t num_ij;
 167
 168         n = 64;
 169         rc = gcry_mpi_scan (&num_ij, GCRYMPI_FMT_USG, buf_i + i, n, &n);
 170
 171         if (rc != 0) {
 172           return false;
 173         }
 174
 175         gcry_mpi_add (num_ij, num_ij, num_b1);
 176         gcry_mpi_clear_highbit (num_ij, 64 * 8);
 177
 178         n = 64;
 179
 180         rc = gcry_mpi_print (GCRYMPI_FMT_USG, buf_i + i, n, &n, num_ij);
 181         if (rc != 0) {
 182           return false;
 183         }
 184
 185         gcry_mpi_release (num_ij);
 186       }
 187   }
 188 }
 189
 190 void PBE_reset_parameters(void)
 191 {
 192         iteration_count = 0;
 193         salt = NULL;
 194 }
 195
 196 int PBE_decrypt_data(const char *object_identifier_id_param _U_, tvbuff_t *encrypted_tvb _U_, packet_info *pinfo _U_, asn1_ctx_t *actx _U_, proto_item *item _U_)
 197 {
 198         const char      *encryption_algorithm;
 199         gcry_cipher_hd_t cipher;
 200         gcry_error_t    err;
 201         int             algo;
 202         int             mode;
 203         int             ivlen = 0;
 204         int             keylen = 0;
 205         int             datalen = 0;
 206         char            *key = NULL;
 207         char            *iv = NULL;
 208         char            *clear_data = NULL;
 209         tvbuff_t        *clear_tvb = NULL;
 210         const char      *oidname;
 211         GString         *name;
 212         proto_tree      *tree;
 213         char            byte;
 214         bool    decrypt_ok = true;
 215
 216         if(((password == NULL) || (*password == '\0')) && (try_null_password == false)) {
 217                 /* we are not configured to decrypt */
 218                 return false;
 219         }
 220
 221         encryption_algorithm = x509af_get_last_algorithm_id();
 222
 223         /* these are the only encryption schemes we understand for now */
 224         if(!strcmp(encryption_algorithm, PKCS12_PBE_3DES_SHA1_OID)) {
 225                 ivlen = 8;
 226                 keylen = 24;
 227                 algo = GCRY_CIPHER_3DES;
 228                 mode = GCRY_CIPHER_MODE_CBC;
 229         } else if(!strcmp(encryption_algorithm, PKCS12_PBE_ARCFOUR_SHA1_OID)) {
 230                 ivlen = 0;
 231                 keylen = 16;
 232                 algo = GCRY_CIPHER_ARCFOUR;
 233                 mode = GCRY_CIPHER_MODE_NONE;
 234         } else if(!strcmp(encryption_algorithm, PKCS12_PBE_RC2_40_SHA1_OID)) {
 235                 ivlen = 8;
 236                 keylen = 5;
 237                 algo = GCRY_CIPHER_RFC2268_40;
 238                 mode = GCRY_CIPHER_MODE_CBC;
 239         } else {
 240                 /* we don't know how to decrypt this */
 241
 242                 proto_item_append_text(item, " [Unsupported encryption algorithm]");
 243                 return false;
 244         }
 245
 246         if((iteration_count == 0) || (salt == NULL)) {
 247                 proto_item_append_text(item, " [Insufficient parameters]");
 248                 return false;
 249         }
 250
 251         /* allocate buffers */
 252         key = (char *)wmem_alloc(pinfo->pool, keylen);
 253
 254         if(!generate_key_or_iv(pinfo, 1 /*LEY */, salt, iteration_count, password, keylen, key))
 255                 return false;
 256
 257         if(ivlen) {
 258
 259                 iv = (char *)wmem_alloc(pinfo->pool, ivlen);
 260
 261                 if(!generate_key_or_iv(pinfo, 2 /* IV */, salt, iteration_count, password, ivlen, iv))
 262                         return false;
 263         }
 264
 265         /* now try an internal function */
 266         err = gcry_cipher_open(&cipher, algo, mode, 0);
 267         if (gcry_err_code (err))
 268                         return false;
 269
 270         err = gcry_cipher_setkey (cipher, key, keylen);
 271         if (gcry_err_code (err)) {
 272                         gcry_cipher_close (cipher);
 273                         return false;
 274         }
 275
 276         if(ivlen) {
 277                   err = gcry_cipher_setiv (cipher, iv, ivlen);
 278                   if (gcry_err_code (err)) {
 279                           gcry_cipher_close (cipher);
 280                           return false;
 281                   }
 282         }
 283
 284         datalen = tvb_captured_length(encrypted_tvb);
 285         clear_data = (char *)wmem_alloc(pinfo->pool, datalen);
 286
 287         err = gcry_cipher_decrypt (cipher, clear_data, datalen, (char *)tvb_memdup(pinfo->pool, encrypted_tvb, 0, datalen), datalen);
 288         if (gcry_err_code (err)) {
 289
 290                 proto_item_append_text(item, " [Failed to decrypt with password preference]");
 291
 292                 gcry_cipher_close (cipher);
 293                 return false;
 294         }
 295
 296         gcry_cipher_close (cipher);
 297
 298         /* We don't know if we have successfully decrypted the data or not so we:
 299                 a) check the trailing bytes
 300                 b) see if we start with a sequence or a set (is this too constraining?
 301                 */
 302
 303         /* first the trailing bytes */
 304         byte = clear_data[datalen-1];
 305         if(byte <= 0x08) {
 306                 int i;
 307
 308                 for(i = (int)byte; i > 0 ; i--) {
 309                         if(clear_data[datalen - i] != byte) {
 310                                 decrypt_ok = false;
 311                                 break;
 312                         }
 313                 }
 314         } else {
 315                 /* XXX: is this a failure? */
 316         }
 317
 318         /* we assume the result is ASN.1 - check it is a SET or SEQUENCE */
 319         byte = clear_data[0];
 320         if((byte != 0x30) && (byte != 0x31)) { /* do we need more here? OCTET STRING? */
 321                 decrypt_ok = false;
 322         }
 323
 324         if(!decrypt_ok) {
 325                 proto_item_append_text(item, " [Failed to decrypt with supplied password]");
 326
 327                 return false;
 328         }
 329
 330         proto_item_append_text(item, " [Decrypted successfully]");
 331
 332         tree = proto_item_add_subtree(item, ett_decrypted_pbe);
 333
 334         /* OK - so now clear_data contains the decrypted data */
 335
 336         clear_tvb = tvb_new_child_real_data(encrypted_tvb,(const uint8_t *)clear_data, datalen, datalen);
 337
 338         name = g_string_new("");
 339         oidname = oid_resolved_from_string(pinfo->pool, object_identifier_id_param);
 340         g_string_printf(name, "Decrypted %s", oidname ? oidname : object_identifier_id_param);
 341
 342         /* add it as a new source */
 343         add_new_data_source(actx->pinfo, clear_tvb, name->str);
 344
 345         g_string_free(name, TRUE);
 346
 347         /* now try and decode it */
 348         call_ber_oid_callback(object_identifier_id_param, clear_tvb, 0, actx->pinfo, tree, NULL);
 349
 350         return true;
 351 }
 352
 353 #include "packet-pkcs12-fn.c"
 354
 355 static int strip_octet_string(tvbuff_t *tvb)
 356 {
 357   int8_t ber_class;
 358   bool pc, ind;
 359   int32_t tag;
 360   uint32_t len;
 361   int offset = 0;
 362
 363   /* PKCS#7 encodes the content as OCTET STRING, whereas CMS is just any ANY */
 364   /* if we use CMS (rather than PKCS#7) - which we are - we need to strip the OCTET STRING tag */
 365   /* before proceeding */
 366
 367   offset = get_ber_identifier(tvb, 0, &ber_class, &pc, &tag);
 368   offset = get_ber_length(tvb, offset, &len, &ind);
 369
 370   if((ber_class == BER_CLASS_UNI) && (tag == BER_UNI_TAG_OCTETSTRING))
 371     return offset;
 372
 373   return 0;
 374
 375 }
 376
 377 static int dissect_AuthenticatedSafe_OCTETSTRING_PDU(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) {
 378   int offset = 0;
 379   asn1_ctx_t asn1_ctx;
 380   asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, true, pinfo);
 381
 382   if((offset = strip_octet_string(tvb)) > 0)
 383     dissect_pkcs12_AuthenticatedSafe(false, tvb, offset, &asn1_ctx, tree, hf_pkcs12_AuthenticatedSafe_PDU);
 384   else
 385     proto_tree_add_expert(tree, pinfo, &ei_pkcs12_octet_string_expected, tvb, 0, 1);
 386   return tvb_captured_length(tvb);
 387 }
 388
 389 static int dissect_SafeContents_OCTETSTRING_PDU(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
 390 {
 391   int offset = 0;
 392   asn1_ctx_t asn1_ctx;
 393   asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, true, pinfo);
 394
 395   offset = strip_octet_string(tvb);
 396
 397   dissect_pkcs12_SafeContents(false, tvb, offset, &asn1_ctx, tree, hf_pkcs12_SafeContents_PDU);
 398   return tvb_captured_length(tvb);
 399 }
 400
 401 static int dissect_X509Certificate_OCTETSTRING_PDU(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
 402 {
 403   int offset = 0;
 404   asn1_ctx_t asn1_ctx;
 405   asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, true, pinfo);
 406
 407   if((offset = strip_octet_string(tvb)) > 0)
 408         dissect_x509af_Certificate(false, tvb, offset, &asn1_ctx, tree, hf_pkcs12_X509Certificate_PDU);
 409   else
 410         proto_tree_add_expert(tree, pinfo, &ei_pkcs12_octet_string_expected, tvb, 0, 1);
 411
 412   return tvb_captured_length(tvb);
 413 }
 414
 415 /*--- proto_register_pkcs12 ----------------------------------------------*/
 416 void proto_register_pkcs12(void) {
 417
 418   /* List of fields */
 419   static hf_register_info hf[] = {
 420     { &hf_pkcs12_X509Certificate_PDU,
 421       { "X509Certificate", "pkcs12.X509Certificate",
 422         FT_NONE, BASE_NONE, NULL, 0,
 423         "pkcs12.X509Certificate", HFILL }},
 424     { &hf_pkcs12_AuthenticatedSafe_PDU,
 425       { "AuthenticatedSafe", "pkcs12.AuthenticatedSafe",
 426         FT_UINT32, BASE_DEC, NULL, 0,
 427         NULL, HFILL }},
 428
 429 #include "packet-pkcs12-hfarr.c"
 430   };
 431
 432   /* List of subtrees */
 433   static int *ett[] = {
 434           &ett_decrypted_pbe,
 435 #include "packet-pkcs12-ettarr.c"
 436   };
 437   static ei_register_info ei[] = {
 438       { &ei_pkcs12_octet_string_expected, { "pkcs12.octet_string_expected", PI_PROTOCOL, PI_WARN, "BER Error: OCTET STRING expected", EXPFILL }},
 439   };
 440
 441   module_t *pkcs12_module;
 442   expert_module_t* expert_pkcs12;
 443
 444   /* Register protocol */
 445   proto_pkcs12 = proto_register_protocol(PNAME, PSNAME, PFNAME);
 446
 447   /* Register fields and subtrees */
 448   proto_register_field_array(proto_pkcs12, hf, array_length(hf));
 449   proto_register_subtree_array(ett, array_length(ett));
 450   expert_pkcs12 = expert_register_protocol(proto_pkcs12);
 451   expert_register_field_array(expert_pkcs12, ei, array_length(ei));
 452
 453   /* Register preferences */
 454   pkcs12_module = prefs_register_protocol(proto_pkcs12, NULL);
 455
 456   prefs_register_string_preference(pkcs12_module, "password",
 457         "Password to decrypt the file with",
 458         "The password to used to decrypt the encrypted elements within"
 459         " the PKCS#12 file", &password);
 460
 461   prefs_register_bool_preference(pkcs12_module, "try_null_password",
 462         "Try to decrypt with a empty password",
 463         "Whether to try and decrypt the encrypted data within the"
 464         " PKCS#12 with a NULL password", &try_null_password);
 465
 466   register_ber_syntax_dissector("PKCS#12", proto_pkcs12, dissect_PFX_PDU);
 467   register_ber_oid_syntax(".p12", NULL, "PKCS#12");
 468   register_ber_oid_syntax(".pfx", NULL, "PKCS#12");
 469 }
 470
 471
 472 /*--- proto_reg_handoff_pkcs12 -------------------------------------------*/
 473 void proto_reg_handoff_pkcs12(void) {
 474 #include "packet-pkcs12-dis-tab.c"
 475
 476         register_ber_oid_dissector("1.2.840.113549.1.9.22.1", dissect_X509Certificate_OCTETSTRING_PDU, proto_pkcs12, "x509Certificate");
 477
 478 }
 479