1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* PKCS#7 parser 3 * 4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #define pr_fmt(fmt) "PKCS7: "fmt 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/export.h> 12 #include <linux/slab.h> 13 #include <linux/err.h> 14 #include <linux/oid_registry.h> 15 #include <crypto/public_key.h> 16 #include "pkcs7_parser.h" 17 #include "pkcs7.asn1.h" 18 19 MODULE_DESCRIPTION("PKCS#7 parser"); 20 MODULE_AUTHOR("Red Hat, Inc."); 21 MODULE_LICENSE("GPL"); 22 23 struct pkcs7_parse_context { 24 struct pkcs7_message *msg; /* Message being constructed */ 25 struct pkcs7_signed_info *sinfo; /* SignedInfo being constructed */ 26 struct pkcs7_signed_info **ppsinfo; 27 struct x509_certificate *certs; /* Certificate cache */ 28 struct x509_certificate **ppcerts; 29 unsigned long data; /* Start of data */ 30 enum OID last_oid; /* Last OID encountered */ 31 unsigned x509_index; 32 unsigned sinfo_index; 33 const void *raw_serial; 34 unsigned raw_serial_size; 35 unsigned raw_issuer_size; 36 const void *raw_issuer; 37 const void *raw_skid; 38 unsigned raw_skid_size; 39 bool expect_skid; 40 }; 41 42 /* 43 * Free a signed information block. 44 */ 45 static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo) 46 { 47 if (sinfo) { 48 public_key_signature_free(sinfo->sig); 49 kfree(sinfo); 50 } 51 } 52 53 /** 54 * pkcs7_free_message - Free a PKCS#7 message 55 * @pkcs7: The PKCS#7 message to free 56 */ 57 void pkcs7_free_message(struct pkcs7_message *pkcs7) 58 { 59 struct x509_certificate *cert; 60 struct pkcs7_signed_info *sinfo; 61 62 if (pkcs7) { 63 while (pkcs7->certs) { 64 cert = pkcs7->certs; 65 pkcs7->certs = cert->next; 66 x509_free_certificate(cert); 67 } 68 while (pkcs7->crl) { 69 cert = pkcs7->crl; 70 pkcs7->crl = cert->next; 71 x509_free_certificate(cert); 72 } 73 while (pkcs7->signed_infos) { 74 sinfo = pkcs7->signed_infos; 75 pkcs7->signed_infos = sinfo->next; 76 pkcs7_free_signed_info(sinfo); 77 } 78 kfree(pkcs7); 79 } 80 } 81 EXPORT_SYMBOL_GPL(pkcs7_free_message); 82 83 /* 84 * Check authenticatedAttributes are provided or not provided consistently. 85 */ 86 static int pkcs7_check_authattrs(struct pkcs7_message *msg) 87 { 88 struct pkcs7_signed_info *sinfo; 89 bool want = false; 90 91 sinfo = msg->signed_infos; 92 if (!sinfo) 93 goto inconsistent; 94 95 if (sinfo->authattrs) { 96 want = true; 97 msg->have_authattrs = true; 98 } 99 100 for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next) 101 if (!!sinfo->authattrs != want) 102 goto inconsistent; 103 return 0; 104 105 inconsistent: 106 pr_warn("Inconsistently supplied authAttrs\n"); 107 return -EINVAL; 108 } 109 110 /** 111 * pkcs7_parse_message - Parse a PKCS#7 message 112 * @data: The raw binary ASN.1 encoded message to be parsed 113 * @datalen: The size of the encoded message 114 */ 115 struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen) 116 { 117 struct pkcs7_parse_context *ctx; 118 struct pkcs7_message *msg = ERR_PTR(-ENOMEM); 119 int ret; 120 121 ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL); 122 if (!ctx) 123 goto out_no_ctx; 124 ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL); 125 if (!ctx->msg) 126 goto out_no_msg; 127 ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL); 128 if (!ctx->sinfo) 129 goto out_no_sinfo; 130 ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature), 131 GFP_KERNEL); 132 if (!ctx->sinfo->sig) 133 goto out_no_sig; 134 135 ctx->data = (unsigned long)data; 136 ctx->ppcerts = &ctx->certs; 137 ctx->ppsinfo = &ctx->msg->signed_infos; 138 139 /* Attempt to decode the signature */ 140 ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen); 141 if (ret < 0) { 142 msg = ERR_PTR(ret); 143 goto out; 144 } 145 146 ret = pkcs7_check_authattrs(ctx->msg); 147 if (ret < 0) { 148 msg = ERR_PTR(ret); 149 goto out; 150 } 151 152 msg = ctx->msg; 153 ctx->msg = NULL; 154 155 out: 156 while (ctx->certs) { 157 struct x509_certificate *cert = ctx->certs; 158 ctx->certs = cert->next; 159 x509_free_certificate(cert); 160 } 161 out_no_sig: 162 pkcs7_free_signed_info(ctx->sinfo); 163 out_no_sinfo: 164 pkcs7_free_message(ctx->msg); 165 out_no_msg: 166 kfree(ctx); 167 out_no_ctx: 168 return msg; 169 } 170 EXPORT_SYMBOL_GPL(pkcs7_parse_message); 171 172 /** 173 * pkcs7_get_content_data - Get access to the PKCS#7 content 174 * @pkcs7: The preparsed PKCS#7 message to access 175 * @_data: Place to return a pointer to the data 176 * @_data_len: Place to return the data length 177 * @_headerlen: Size of ASN.1 header not included in _data 178 * 179 * Get access to the data content of the PKCS#7 message. The size of the 180 * header of the ASN.1 object that contains it is also provided and can be used 181 * to adjust *_data and *_data_len to get the entire object. 182 * 183 * Returns -ENODATA if the data object was missing from the message. 184 */ 185 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7, 186 const void **_data, size_t *_data_len, 187 size_t *_headerlen) 188 { 189 if (!pkcs7->data) 190 return -ENODATA; 191 192 *_data = pkcs7->data; 193 *_data_len = pkcs7->data_len; 194 if (_headerlen) 195 *_headerlen = pkcs7->data_hdrlen; 196 return 0; 197 } 198 EXPORT_SYMBOL_GPL(pkcs7_get_content_data); 199 200 /* 201 * Note an OID when we find one for later processing when we know how 202 * to interpret it. 203 */ 204 int pkcs7_note_OID(void *context, size_t hdrlen, 205 unsigned char tag, 206 const void *value, size_t vlen) 207 { 208 struct pkcs7_parse_context *ctx = context; 209 210 ctx->last_oid = look_up_OID(value, vlen); 211 if (ctx->last_oid == OID__NR) { 212 char buffer[50]; 213 sprint_oid(value, vlen, buffer, sizeof(buffer)); 214 printk("PKCS7: Unknown OID: [%lu] %s\n", 215 (unsigned long)value - ctx->data, buffer); 216 } 217 return 0; 218 } 219 220 /* 221 * Note the digest algorithm for the signature. 222 */ 223 int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen, 224 unsigned char tag, 225 const void *value, size_t vlen) 226 { 227 struct pkcs7_parse_context *ctx = context; 228 229 switch (ctx->last_oid) { 230 case OID_md4: 231 ctx->sinfo->sig->hash_algo = "md4"; 232 break; 233 case OID_md5: 234 ctx->sinfo->sig->hash_algo = "md5"; 235 break; 236 case OID_sha1: 237 ctx->sinfo->sig->hash_algo = "sha1"; 238 break; 239 case OID_sha256: 240 ctx->sinfo->sig->hash_algo = "sha256"; 241 break; 242 case OID_sha384: 243 ctx->sinfo->sig->hash_algo = "sha384"; 244 break; 245 case OID_sha512: 246 ctx->sinfo->sig->hash_algo = "sha512"; 247 break; 248 case OID_sha224: 249 ctx->sinfo->sig->hash_algo = "sha224"; 250 break; 251 default: 252 printk("Unsupported digest algo: %u\n", ctx->last_oid); 253 return -ENOPKG; 254 } 255 return 0; 256 } 257 258 /* 259 * Note the public key algorithm for the signature. 260 */ 261 int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen, 262 unsigned char tag, 263 const void *value, size_t vlen) 264 { 265 struct pkcs7_parse_context *ctx = context; 266 267 switch (ctx->last_oid) { 268 case OID_rsaEncryption: 269 ctx->sinfo->sig->pkey_algo = "rsa"; 270 ctx->sinfo->sig->encoding = "pkcs1"; 271 break; 272 case OID_id_ecdsa_with_sha1: 273 case OID_id_ecdsa_with_sha224: 274 case OID_id_ecdsa_with_sha256: 275 case OID_id_ecdsa_with_sha384: 276 case OID_id_ecdsa_with_sha512: 277 ctx->sinfo->sig->pkey_algo = "ecdsa"; 278 ctx->sinfo->sig->encoding = "x962"; 279 break; 280 default: 281 printk("Unsupported pkey algo: %u\n", ctx->last_oid); 282 return -ENOPKG; 283 } 284 return 0; 285 } 286 287 /* 288 * We only support signed data [RFC2315 sec 9]. 289 */ 290 int pkcs7_check_content_type(void *context, size_t hdrlen, 291 unsigned char tag, 292 const void *value, size_t vlen) 293 { 294 struct pkcs7_parse_context *ctx = context; 295 296 if (ctx->last_oid != OID_signed_data) { 297 pr_warn("Only support pkcs7_signedData type\n"); 298 return -EINVAL; 299 } 300 301 return 0; 302 } 303 304 /* 305 * Note the SignedData version 306 */ 307 int pkcs7_note_signeddata_version(void *context, size_t hdrlen, 308 unsigned char tag, 309 const void *value, size_t vlen) 310 { 311 struct pkcs7_parse_context *ctx = context; 312 unsigned version; 313 314 if (vlen != 1) 315 goto unsupported; 316 317 ctx->msg->version = version = *(const u8 *)value; 318 switch (version) { 319 case 1: 320 /* PKCS#7 SignedData [RFC2315 sec 9.1] 321 * CMS ver 1 SignedData [RFC5652 sec 5.1] 322 */ 323 break; 324 case 3: 325 /* CMS ver 3 SignedData [RFC2315 sec 5.1] */ 326 break; 327 default: 328 goto unsupported; 329 } 330 331 return 0; 332 333 unsupported: 334 pr_warn("Unsupported SignedData version\n"); 335 return -EINVAL; 336 } 337 338 /* 339 * Note the SignerInfo version 340 */ 341 int pkcs7_note_signerinfo_version(void *context, size_t hdrlen, 342 unsigned char tag, 343 const void *value, size_t vlen) 344 { 345 struct pkcs7_parse_context *ctx = context; 346 unsigned version; 347 348 if (vlen != 1) 349 goto unsupported; 350 351 version = *(const u8 *)value; 352 switch (version) { 353 case 1: 354 /* PKCS#7 SignerInfo [RFC2315 sec 9.2] 355 * CMS ver 1 SignerInfo [RFC5652 sec 5.3] 356 */ 357 if (ctx->msg->version != 1) 358 goto version_mismatch; 359 ctx->expect_skid = false; 360 break; 361 case 3: 362 /* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */ 363 if (ctx->msg->version == 1) 364 goto version_mismatch; 365 ctx->expect_skid = true; 366 break; 367 default: 368 goto unsupported; 369 } 370 371 return 0; 372 373 unsupported: 374 pr_warn("Unsupported SignerInfo version\n"); 375 return -EINVAL; 376 version_mismatch: 377 pr_warn("SignedData-SignerInfo version mismatch\n"); 378 return -EBADMSG; 379 } 380 381 /* 382 * Extract a certificate and store it in the context. 383 */ 384 int pkcs7_extract_cert(void *context, size_t hdrlen, 385 unsigned char tag, 386 const void *value, size_t vlen) 387 { 388 struct pkcs7_parse_context *ctx = context; 389 struct x509_certificate *x509; 390 391 if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) { 392 pr_debug("Cert began with tag %02x at %lu\n", 393 tag, (unsigned long)ctx - ctx->data); 394 return -EBADMSG; 395 } 396 397 /* We have to correct for the header so that the X.509 parser can start 398 * from the beginning. Note that since X.509 stipulates DER, there 399 * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which 400 * stipulates BER). 401 */ 402 value -= hdrlen; 403 vlen += hdrlen; 404 405 if (((u8*)value)[1] == 0x80) 406 vlen += 2; /* Indefinite length - there should be an EOC */ 407 408 x509 = x509_cert_parse(value, vlen); 409 if (IS_ERR(x509)) 410 return PTR_ERR(x509); 411 412 x509->index = ++ctx->x509_index; 413 pr_debug("Got cert %u for %s\n", x509->index, x509->subject); 414 pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data); 415 416 *ctx->ppcerts = x509; 417 ctx->ppcerts = &x509->next; 418 return 0; 419 } 420 421 /* 422 * Save the certificate list 423 */ 424 int pkcs7_note_certificate_list(void *context, size_t hdrlen, 425 unsigned char tag, 426 const void *value, size_t vlen) 427 { 428 struct pkcs7_parse_context *ctx = context; 429 430 pr_devel("Got cert list (%02x)\n", tag); 431 432 *ctx->ppcerts = ctx->msg->certs; 433 ctx->msg->certs = ctx->certs; 434 ctx->certs = NULL; 435 ctx->ppcerts = &ctx->certs; 436 return 0; 437 } 438 439 /* 440 * Note the content type. 441 */ 442 int pkcs7_note_content(void *context, size_t hdrlen, 443 unsigned char tag, 444 const void *value, size_t vlen) 445 { 446 struct pkcs7_parse_context *ctx = context; 447 448 if (ctx->last_oid != OID_data && 449 ctx->last_oid != OID_msIndirectData) { 450 pr_warn("Unsupported data type %d\n", ctx->last_oid); 451 return -EINVAL; 452 } 453 454 ctx->msg->data_type = ctx->last_oid; 455 return 0; 456 } 457 458 /* 459 * Extract the data from the message and store that and its content type OID in 460 * the context. 461 */ 462 int pkcs7_note_data(void *context, size_t hdrlen, 463 unsigned char tag, 464 const void *value, size_t vlen) 465 { 466 struct pkcs7_parse_context *ctx = context; 467 468 pr_debug("Got data\n"); 469 470 ctx->msg->data = value; 471 ctx->msg->data_len = vlen; 472 ctx->msg->data_hdrlen = hdrlen; 473 return 0; 474 } 475 476 /* 477 * Parse authenticated attributes. 478 */ 479 int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen, 480 unsigned char tag, 481 const void *value, size_t vlen) 482 { 483 struct pkcs7_parse_context *ctx = context; 484 struct pkcs7_signed_info *sinfo = ctx->sinfo; 485 enum OID content_type; 486 487 pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value); 488 489 switch (ctx->last_oid) { 490 case OID_contentType: 491 if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set)) 492 goto repeated; 493 content_type = look_up_OID(value, vlen); 494 if (content_type != ctx->msg->data_type) { 495 pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n", 496 ctx->msg->data_type, sinfo->index, 497 content_type); 498 return -EBADMSG; 499 } 500 return 0; 501 502 case OID_signingTime: 503 if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set)) 504 goto repeated; 505 /* Should we check that the signing time is consistent 506 * with the signer's X.509 cert? 507 */ 508 return x509_decode_time(&sinfo->signing_time, 509 hdrlen, tag, value, vlen); 510 511 case OID_messageDigest: 512 if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set)) 513 goto repeated; 514 if (tag != ASN1_OTS) 515 return -EBADMSG; 516 sinfo->msgdigest = value; 517 sinfo->msgdigest_len = vlen; 518 return 0; 519 520 case OID_smimeCapabilites: 521 if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set)) 522 goto repeated; 523 if (ctx->msg->data_type != OID_msIndirectData) { 524 pr_warn("S/MIME Caps only allowed with Authenticode\n"); 525 return -EKEYREJECTED; 526 } 527 return 0; 528 529 /* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE 530 * char URLs and cont[1] 8-bit char URLs. 531 * 532 * Microsoft StatementType seems to contain a list of OIDs that 533 * are also used as extendedKeyUsage types in X.509 certs. 534 */ 535 case OID_msSpOpusInfo: 536 if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) 537 goto repeated; 538 goto authenticode_check; 539 case OID_msStatementType: 540 if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set)) 541 goto repeated; 542 authenticode_check: 543 if (ctx->msg->data_type != OID_msIndirectData) { 544 pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n"); 545 return -EKEYREJECTED; 546 } 547 /* I'm not sure how to validate these */ 548 return 0; 549 default: 550 return 0; 551 } 552 553 repeated: 554 /* We permit max one item per AuthenticatedAttribute and no repeats */ 555 pr_warn("Repeated/multivalue AuthAttrs not permitted\n"); 556 return -EKEYREJECTED; 557 } 558 559 /* 560 * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3] 561 */ 562 int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen, 563 unsigned char tag, 564 const void *value, size_t vlen) 565 { 566 struct pkcs7_parse_context *ctx = context; 567 struct pkcs7_signed_info *sinfo = ctx->sinfo; 568 569 if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) || 570 !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) { 571 pr_warn("Missing required AuthAttr\n"); 572 return -EBADMSG; 573 } 574 575 if (ctx->msg->data_type != OID_msIndirectData && 576 test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) { 577 pr_warn("Unexpected Authenticode AuthAttr\n"); 578 return -EBADMSG; 579 } 580 581 /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */ 582 sinfo->authattrs = value - (hdrlen - 1); 583 sinfo->authattrs_len = vlen + (hdrlen - 1); 584 return 0; 585 } 586 587 /* 588 * Note the issuing certificate serial number 589 */ 590 int pkcs7_sig_note_serial(void *context, size_t hdrlen, 591 unsigned char tag, 592 const void *value, size_t vlen) 593 { 594 struct pkcs7_parse_context *ctx = context; 595 ctx->raw_serial = value; 596 ctx->raw_serial_size = vlen; 597 return 0; 598 } 599 600 /* 601 * Note the issuer's name 602 */ 603 int pkcs7_sig_note_issuer(void *context, size_t hdrlen, 604 unsigned char tag, 605 const void *value, size_t vlen) 606 { 607 struct pkcs7_parse_context *ctx = context; 608 ctx->raw_issuer = value; 609 ctx->raw_issuer_size = vlen; 610 return 0; 611 } 612 613 /* 614 * Note the issuing cert's subjectKeyIdentifier 615 */ 616 int pkcs7_sig_note_skid(void *context, size_t hdrlen, 617 unsigned char tag, 618 const void *value, size_t vlen) 619 { 620 struct pkcs7_parse_context *ctx = context; 621 622 pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value); 623 624 ctx->raw_skid = value; 625 ctx->raw_skid_size = vlen; 626 return 0; 627 } 628 629 /* 630 * Note the signature data 631 */ 632 int pkcs7_sig_note_signature(void *context, size_t hdrlen, 633 unsigned char tag, 634 const void *value, size_t vlen) 635 { 636 struct pkcs7_parse_context *ctx = context; 637 638 ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL); 639 if (!ctx->sinfo->sig->s) 640 return -ENOMEM; 641 642 ctx->sinfo->sig->s_size = vlen; 643 return 0; 644 } 645 646 /* 647 * Note a signature information block 648 */ 649 int pkcs7_note_signed_info(void *context, size_t hdrlen, 650 unsigned char tag, 651 const void *value, size_t vlen) 652 { 653 struct pkcs7_parse_context *ctx = context; 654 struct pkcs7_signed_info *sinfo = ctx->sinfo; 655 struct asymmetric_key_id *kid; 656 657 if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) { 658 pr_warn("Authenticode requires AuthAttrs\n"); 659 return -EBADMSG; 660 } 661 662 /* Generate cert issuer + serial number key ID */ 663 if (!ctx->expect_skid) { 664 kid = asymmetric_key_generate_id(ctx->raw_serial, 665 ctx->raw_serial_size, 666 ctx->raw_issuer, 667 ctx->raw_issuer_size); 668 } else { 669 kid = asymmetric_key_generate_id(ctx->raw_skid, 670 ctx->raw_skid_size, 671 "", 0); 672 } 673 if (IS_ERR(kid)) 674 return PTR_ERR(kid); 675 676 pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data); 677 678 sinfo->sig->auth_ids[0] = kid; 679 sinfo->index = ++ctx->sinfo_index; 680 *ctx->ppsinfo = sinfo; 681 ctx->ppsinfo = &sinfo->next; 682 ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL); 683 if (!ctx->sinfo) 684 return -ENOMEM; 685 ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature), 686 GFP_KERNEL); 687 if (!ctx->sinfo->sig) 688 return -ENOMEM; 689 return 0; 690 } 691