1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* X.509 certificate 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) "X.509: "fmt 9 #include <linux/kernel.h> 10 #include <linux/export.h> 11 #include <linux/slab.h> 12 #include <linux/err.h> 13 #include <linux/oid_registry.h> 14 #include <crypto/public_key.h> 15 #include "x509_parser.h" 16 #include "x509.asn1.h" 17 #include "x509_akid.asn1.h" 18 19 struct x509_parse_context { 20 struct x509_certificate *cert; /* Certificate being constructed */ 21 unsigned long data; /* Start of data */ 22 const void *cert_start; /* Start of cert content */ 23 const void *key; /* Key data */ 24 size_t key_size; /* Size of key data */ 25 const void *params; /* Key parameters */ 26 size_t params_size; /* Size of key parameters */ 27 enum OID key_algo; /* Public key algorithm */ 28 enum OID last_oid; /* Last OID encountered */ 29 enum OID algo_oid; /* Algorithm OID */ 30 unsigned char nr_mpi; /* Number of MPIs stored */ 31 u8 o_size; /* Size of organizationName (O) */ 32 u8 cn_size; /* Size of commonName (CN) */ 33 u8 email_size; /* Size of emailAddress */ 34 u16 o_offset; /* Offset of organizationName (O) */ 35 u16 cn_offset; /* Offset of commonName (CN) */ 36 u16 email_offset; /* Offset of emailAddress */ 37 unsigned raw_akid_size; 38 const void *raw_akid; /* Raw authorityKeyId in ASN.1 */ 39 const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */ 40 unsigned akid_raw_issuer_size; 41 }; 42 43 /* 44 * Free an X.509 certificate 45 */ 46 void x509_free_certificate(struct x509_certificate *cert) 47 { 48 if (cert) { 49 public_key_free(cert->pub); 50 public_key_signature_free(cert->sig); 51 kfree(cert->issuer); 52 kfree(cert->subject); 53 kfree(cert->id); 54 kfree(cert->skid); 55 kfree(cert); 56 } 57 } 58 EXPORT_SYMBOL_GPL(x509_free_certificate); 59 60 /* 61 * Parse an X.509 certificate 62 */ 63 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) 64 { 65 struct x509_certificate *cert; 66 struct x509_parse_context *ctx; 67 struct asymmetric_key_id *kid; 68 long ret; 69 70 ret = -ENOMEM; 71 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL); 72 if (!cert) 73 goto error_no_cert; 74 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL); 75 if (!cert->pub) 76 goto error_no_ctx; 77 cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL); 78 if (!cert->sig) 79 goto error_no_ctx; 80 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL); 81 if (!ctx) 82 goto error_no_ctx; 83 84 ctx->cert = cert; 85 ctx->data = (unsigned long)data; 86 87 /* Attempt to decode the certificate */ 88 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen); 89 if (ret < 0) 90 goto error_decode; 91 92 /* Decode the AuthorityKeyIdentifier */ 93 if (ctx->raw_akid) { 94 pr_devel("AKID: %u %*phN\n", 95 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid); 96 ret = asn1_ber_decoder(&x509_akid_decoder, ctx, 97 ctx->raw_akid, ctx->raw_akid_size); 98 if (ret < 0) { 99 pr_warn("Couldn't decode AuthKeyIdentifier\n"); 100 goto error_decode; 101 } 102 } 103 104 ret = -ENOMEM; 105 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL); 106 if (!cert->pub->key) 107 goto error_decode; 108 109 cert->pub->keylen = ctx->key_size; 110 111 cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL); 112 if (!cert->pub->params) 113 goto error_decode; 114 115 cert->pub->paramlen = ctx->params_size; 116 cert->pub->algo = ctx->key_algo; 117 118 /* Grab the signature bits */ 119 ret = x509_get_sig_params(cert); 120 if (ret < 0) 121 goto error_decode; 122 123 /* Generate cert issuer + serial number key ID */ 124 kid = asymmetric_key_generate_id(cert->raw_serial, 125 cert->raw_serial_size, 126 cert->raw_issuer, 127 cert->raw_issuer_size); 128 if (IS_ERR(kid)) { 129 ret = PTR_ERR(kid); 130 goto error_decode; 131 } 132 cert->id = kid; 133 134 /* Detect self-signed certificates */ 135 ret = x509_check_for_self_signed(cert); 136 if (ret < 0) 137 goto error_decode; 138 139 kfree(ctx); 140 return cert; 141 142 error_decode: 143 kfree(ctx); 144 error_no_ctx: 145 x509_free_certificate(cert); 146 error_no_cert: 147 return ERR_PTR(ret); 148 } 149 EXPORT_SYMBOL_GPL(x509_cert_parse); 150 151 /* 152 * Note an OID when we find one for later processing when we know how 153 * to interpret it. 154 */ 155 int x509_note_OID(void *context, size_t hdrlen, 156 unsigned char tag, 157 const void *value, size_t vlen) 158 { 159 struct x509_parse_context *ctx = context; 160 161 ctx->last_oid = look_up_OID(value, vlen); 162 if (ctx->last_oid == OID__NR) { 163 char buffer[50]; 164 sprint_oid(value, vlen, buffer, sizeof(buffer)); 165 pr_debug("Unknown OID: [%lu] %s\n", 166 (unsigned long)value - ctx->data, buffer); 167 } 168 return 0; 169 } 170 171 /* 172 * Save the position of the TBS data so that we can check the signature over it 173 * later. 174 */ 175 int x509_note_tbs_certificate(void *context, size_t hdrlen, 176 unsigned char tag, 177 const void *value, size_t vlen) 178 { 179 struct x509_parse_context *ctx = context; 180 181 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n", 182 hdrlen, tag, (unsigned long)value - ctx->data, vlen); 183 184 ctx->cert->tbs = value - hdrlen; 185 ctx->cert->tbs_size = vlen + hdrlen; 186 return 0; 187 } 188 189 /* 190 * Record the public key algorithm 191 */ 192 int x509_note_pkey_algo(void *context, size_t hdrlen, 193 unsigned char tag, 194 const void *value, size_t vlen) 195 { 196 struct x509_parse_context *ctx = context; 197 198 pr_debug("PubKey Algo: %u\n", ctx->last_oid); 199 200 switch (ctx->last_oid) { 201 case OID_md2WithRSAEncryption: 202 case OID_md3WithRSAEncryption: 203 default: 204 return -ENOPKG; /* Unsupported combination */ 205 206 case OID_md4WithRSAEncryption: 207 ctx->cert->sig->hash_algo = "md4"; 208 goto rsa_pkcs1; 209 210 case OID_sha1WithRSAEncryption: 211 ctx->cert->sig->hash_algo = "sha1"; 212 goto rsa_pkcs1; 213 214 case OID_sha256WithRSAEncryption: 215 ctx->cert->sig->hash_algo = "sha256"; 216 goto rsa_pkcs1; 217 218 case OID_sha384WithRSAEncryption: 219 ctx->cert->sig->hash_algo = "sha384"; 220 goto rsa_pkcs1; 221 222 case OID_sha512WithRSAEncryption: 223 ctx->cert->sig->hash_algo = "sha512"; 224 goto rsa_pkcs1; 225 226 case OID_sha224WithRSAEncryption: 227 ctx->cert->sig->hash_algo = "sha224"; 228 goto rsa_pkcs1; 229 230 case OID_gost2012Signature256: 231 ctx->cert->sig->hash_algo = "streebog256"; 232 goto ecrdsa; 233 234 case OID_gost2012Signature512: 235 ctx->cert->sig->hash_algo = "streebog512"; 236 goto ecrdsa; 237 238 case OID_SM2_with_SM3: 239 ctx->cert->sig->hash_algo = "sm3"; 240 goto sm2; 241 } 242 243 rsa_pkcs1: 244 ctx->cert->sig->pkey_algo = "rsa"; 245 ctx->cert->sig->encoding = "pkcs1"; 246 ctx->algo_oid = ctx->last_oid; 247 return 0; 248 ecrdsa: 249 ctx->cert->sig->pkey_algo = "ecrdsa"; 250 ctx->cert->sig->encoding = "raw"; 251 ctx->algo_oid = ctx->last_oid; 252 return 0; 253 sm2: 254 ctx->cert->sig->pkey_algo = "sm2"; 255 ctx->cert->sig->encoding = "raw"; 256 ctx->algo_oid = ctx->last_oid; 257 return 0; 258 } 259 260 /* 261 * Note the whereabouts and type of the signature. 262 */ 263 int x509_note_signature(void *context, size_t hdrlen, 264 unsigned char tag, 265 const void *value, size_t vlen) 266 { 267 struct x509_parse_context *ctx = context; 268 269 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen); 270 271 if (ctx->last_oid != ctx->algo_oid) { 272 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n", 273 ctx->algo_oid, ctx->last_oid); 274 return -EINVAL; 275 } 276 277 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 || 278 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 || 279 strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0) { 280 /* Discard the BIT STRING metadata */ 281 if (vlen < 1 || *(const u8 *)value != 0) 282 return -EBADMSG; 283 284 value++; 285 vlen--; 286 } 287 288 ctx->cert->raw_sig = value; 289 ctx->cert->raw_sig_size = vlen; 290 return 0; 291 } 292 293 /* 294 * Note the certificate serial number 295 */ 296 int x509_note_serial(void *context, size_t hdrlen, 297 unsigned char tag, 298 const void *value, size_t vlen) 299 { 300 struct x509_parse_context *ctx = context; 301 ctx->cert->raw_serial = value; 302 ctx->cert->raw_serial_size = vlen; 303 return 0; 304 } 305 306 /* 307 * Note some of the name segments from which we'll fabricate a name. 308 */ 309 int x509_extract_name_segment(void *context, size_t hdrlen, 310 unsigned char tag, 311 const void *value, size_t vlen) 312 { 313 struct x509_parse_context *ctx = context; 314 315 switch (ctx->last_oid) { 316 case OID_commonName: 317 ctx->cn_size = vlen; 318 ctx->cn_offset = (unsigned long)value - ctx->data; 319 break; 320 case OID_organizationName: 321 ctx->o_size = vlen; 322 ctx->o_offset = (unsigned long)value - ctx->data; 323 break; 324 case OID_email_address: 325 ctx->email_size = vlen; 326 ctx->email_offset = (unsigned long)value - ctx->data; 327 break; 328 default: 329 break; 330 } 331 332 return 0; 333 } 334 335 /* 336 * Fabricate and save the issuer and subject names 337 */ 338 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen, 339 unsigned char tag, 340 char **_name, size_t vlen) 341 { 342 const void *name, *data = (const void *)ctx->data; 343 size_t namesize; 344 char *buffer; 345 346 if (*_name) 347 return -EINVAL; 348 349 /* Empty name string if no material */ 350 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) { 351 buffer = kmalloc(1, GFP_KERNEL); 352 if (!buffer) 353 return -ENOMEM; 354 buffer[0] = 0; 355 goto done; 356 } 357 358 if (ctx->cn_size && ctx->o_size) { 359 /* Consider combining O and CN, but use only the CN if it is 360 * prefixed by the O, or a significant portion thereof. 361 */ 362 namesize = ctx->cn_size; 363 name = data + ctx->cn_offset; 364 if (ctx->cn_size >= ctx->o_size && 365 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 366 ctx->o_size) == 0) 367 goto single_component; 368 if (ctx->cn_size >= 7 && 369 ctx->o_size >= 7 && 370 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0) 371 goto single_component; 372 373 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1, 374 GFP_KERNEL); 375 if (!buffer) 376 return -ENOMEM; 377 378 memcpy(buffer, 379 data + ctx->o_offset, ctx->o_size); 380 buffer[ctx->o_size + 0] = ':'; 381 buffer[ctx->o_size + 1] = ' '; 382 memcpy(buffer + ctx->o_size + 2, 383 data + ctx->cn_offset, ctx->cn_size); 384 buffer[ctx->o_size + 2 + ctx->cn_size] = 0; 385 goto done; 386 387 } else if (ctx->cn_size) { 388 namesize = ctx->cn_size; 389 name = data + ctx->cn_offset; 390 } else if (ctx->o_size) { 391 namesize = ctx->o_size; 392 name = data + ctx->o_offset; 393 } else { 394 namesize = ctx->email_size; 395 name = data + ctx->email_offset; 396 } 397 398 single_component: 399 buffer = kmalloc(namesize + 1, GFP_KERNEL); 400 if (!buffer) 401 return -ENOMEM; 402 memcpy(buffer, name, namesize); 403 buffer[namesize] = 0; 404 405 done: 406 *_name = buffer; 407 ctx->cn_size = 0; 408 ctx->o_size = 0; 409 ctx->email_size = 0; 410 return 0; 411 } 412 413 int x509_note_issuer(void *context, size_t hdrlen, 414 unsigned char tag, 415 const void *value, size_t vlen) 416 { 417 struct x509_parse_context *ctx = context; 418 ctx->cert->raw_issuer = value; 419 ctx->cert->raw_issuer_size = vlen; 420 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen); 421 } 422 423 int x509_note_subject(void *context, size_t hdrlen, 424 unsigned char tag, 425 const void *value, size_t vlen) 426 { 427 struct x509_parse_context *ctx = context; 428 ctx->cert->raw_subject = value; 429 ctx->cert->raw_subject_size = vlen; 430 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen); 431 } 432 433 /* 434 * Extract the parameters for the public key 435 */ 436 int x509_note_params(void *context, size_t hdrlen, 437 unsigned char tag, 438 const void *value, size_t vlen) 439 { 440 struct x509_parse_context *ctx = context; 441 442 /* 443 * AlgorithmIdentifier is used three times in the x509, we should skip 444 * first and ignore third, using second one which is after subject and 445 * before subjectPublicKey. 446 */ 447 if (!ctx->cert->raw_subject || ctx->key) 448 return 0; 449 ctx->params = value - hdrlen; 450 ctx->params_size = vlen + hdrlen; 451 return 0; 452 } 453 454 /* 455 * Extract the data for the public key algorithm 456 */ 457 int x509_extract_key_data(void *context, size_t hdrlen, 458 unsigned char tag, 459 const void *value, size_t vlen) 460 { 461 struct x509_parse_context *ctx = context; 462 463 ctx->key_algo = ctx->last_oid; 464 switch (ctx->last_oid) { 465 case OID_rsaEncryption: 466 ctx->cert->pub->pkey_algo = "rsa"; 467 break; 468 case OID_gost2012PKey256: 469 case OID_gost2012PKey512: 470 ctx->cert->pub->pkey_algo = "ecrdsa"; 471 break; 472 case OID_id_ecPublicKey: 473 ctx->cert->pub->pkey_algo = "sm2"; 474 break; 475 default: 476 return -ENOPKG; 477 } 478 479 /* Discard the BIT STRING metadata */ 480 if (vlen < 1 || *(const u8 *)value != 0) 481 return -EBADMSG; 482 ctx->key = value + 1; 483 ctx->key_size = vlen - 1; 484 return 0; 485 } 486 487 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */ 488 #define SEQ_TAG_KEYID (ASN1_CONT << 6) 489 490 /* 491 * Process certificate extensions that are used to qualify the certificate. 492 */ 493 int x509_process_extension(void *context, size_t hdrlen, 494 unsigned char tag, 495 const void *value, size_t vlen) 496 { 497 struct x509_parse_context *ctx = context; 498 struct asymmetric_key_id *kid; 499 const unsigned char *v = value; 500 501 pr_debug("Extension: %u\n", ctx->last_oid); 502 503 if (ctx->last_oid == OID_subjectKeyIdentifier) { 504 /* Get hold of the key fingerprint */ 505 if (ctx->cert->skid || vlen < 3) 506 return -EBADMSG; 507 if (v[0] != ASN1_OTS || v[1] != vlen - 2) 508 return -EBADMSG; 509 v += 2; 510 vlen -= 2; 511 512 ctx->cert->raw_skid_size = vlen; 513 ctx->cert->raw_skid = v; 514 kid = asymmetric_key_generate_id(v, vlen, "", 0); 515 if (IS_ERR(kid)) 516 return PTR_ERR(kid); 517 ctx->cert->skid = kid; 518 pr_debug("subjkeyid %*phN\n", kid->len, kid->data); 519 return 0; 520 } 521 522 if (ctx->last_oid == OID_authorityKeyIdentifier) { 523 /* Get hold of the CA key fingerprint */ 524 ctx->raw_akid = v; 525 ctx->raw_akid_size = vlen; 526 return 0; 527 } 528 529 return 0; 530 } 531 532 /** 533 * x509_decode_time - Decode an X.509 time ASN.1 object 534 * @_t: The time to fill in 535 * @hdrlen: The length of the object header 536 * @tag: The object tag 537 * @value: The object value 538 * @vlen: The size of the object value 539 * 540 * Decode an ASN.1 universal time or generalised time field into a struct the 541 * kernel can handle and check it for validity. The time is decoded thus: 542 * 543 * [RFC5280 §4.1.2.5] 544 * CAs conforming to this profile MUST always encode certificate validity 545 * dates through the year 2049 as UTCTime; certificate validity dates in 546 * 2050 or later MUST be encoded as GeneralizedTime. Conforming 547 * applications MUST be able to process validity dates that are encoded in 548 * either UTCTime or GeneralizedTime. 549 */ 550 int x509_decode_time(time64_t *_t, size_t hdrlen, 551 unsigned char tag, 552 const unsigned char *value, size_t vlen) 553 { 554 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30, 555 31, 31, 30, 31, 30, 31 }; 556 const unsigned char *p = value; 557 unsigned year, mon, day, hour, min, sec, mon_len; 558 559 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; }) 560 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; }) 561 562 if (tag == ASN1_UNITIM) { 563 /* UTCTime: YYMMDDHHMMSSZ */ 564 if (vlen != 13) 565 goto unsupported_time; 566 year = DD2bin(p); 567 if (year >= 50) 568 year += 1900; 569 else 570 year += 2000; 571 } else if (tag == ASN1_GENTIM) { 572 /* GenTime: YYYYMMDDHHMMSSZ */ 573 if (vlen != 15) 574 goto unsupported_time; 575 year = DD2bin(p) * 100 + DD2bin(p); 576 if (year >= 1950 && year <= 2049) 577 goto invalid_time; 578 } else { 579 goto unsupported_time; 580 } 581 582 mon = DD2bin(p); 583 day = DD2bin(p); 584 hour = DD2bin(p); 585 min = DD2bin(p); 586 sec = DD2bin(p); 587 588 if (*p != 'Z') 589 goto unsupported_time; 590 591 if (year < 1970 || 592 mon < 1 || mon > 12) 593 goto invalid_time; 594 595 mon_len = month_lengths[mon - 1]; 596 if (mon == 2) { 597 if (year % 4 == 0) { 598 mon_len = 29; 599 if (year % 100 == 0) { 600 mon_len = 28; 601 if (year % 400 == 0) 602 mon_len = 29; 603 } 604 } 605 } 606 607 if (day < 1 || day > mon_len || 608 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */ 609 min > 59 || 610 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */ 611 goto invalid_time; 612 613 *_t = mktime64(year, mon, day, hour, min, sec); 614 return 0; 615 616 unsupported_time: 617 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n", 618 tag, (int)vlen, value); 619 return -EBADMSG; 620 invalid_time: 621 pr_debug("Got invalid time [tag %02x]: '%*phN'\n", 622 tag, (int)vlen, value); 623 return -EBADMSG; 624 } 625 EXPORT_SYMBOL_GPL(x509_decode_time); 626 627 int x509_note_not_before(void *context, size_t hdrlen, 628 unsigned char tag, 629 const void *value, size_t vlen) 630 { 631 struct x509_parse_context *ctx = context; 632 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen); 633 } 634 635 int x509_note_not_after(void *context, size_t hdrlen, 636 unsigned char tag, 637 const void *value, size_t vlen) 638 { 639 struct x509_parse_context *ctx = context; 640 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen); 641 } 642 643 /* 644 * Note a key identifier-based AuthorityKeyIdentifier 645 */ 646 int x509_akid_note_kid(void *context, size_t hdrlen, 647 unsigned char tag, 648 const void *value, size_t vlen) 649 { 650 struct x509_parse_context *ctx = context; 651 struct asymmetric_key_id *kid; 652 653 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value); 654 655 if (ctx->cert->sig->auth_ids[1]) 656 return 0; 657 658 kid = asymmetric_key_generate_id(value, vlen, "", 0); 659 if (IS_ERR(kid)) 660 return PTR_ERR(kid); 661 pr_debug("authkeyid %*phN\n", kid->len, kid->data); 662 ctx->cert->sig->auth_ids[1] = kid; 663 return 0; 664 } 665 666 /* 667 * Note a directoryName in an AuthorityKeyIdentifier 668 */ 669 int x509_akid_note_name(void *context, size_t hdrlen, 670 unsigned char tag, 671 const void *value, size_t vlen) 672 { 673 struct x509_parse_context *ctx = context; 674 675 pr_debug("AKID: name: %*phN\n", (int)vlen, value); 676 677 ctx->akid_raw_issuer = value; 678 ctx->akid_raw_issuer_size = vlen; 679 return 0; 680 } 681 682 /* 683 * Note a serial number in an AuthorityKeyIdentifier 684 */ 685 int x509_akid_note_serial(void *context, size_t hdrlen, 686 unsigned char tag, 687 const void *value, size_t vlen) 688 { 689 struct x509_parse_context *ctx = context; 690 struct asymmetric_key_id *kid; 691 692 pr_debug("AKID: serial: %*phN\n", (int)vlen, value); 693 694 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0]) 695 return 0; 696 697 kid = asymmetric_key_generate_id(value, 698 vlen, 699 ctx->akid_raw_issuer, 700 ctx->akid_raw_issuer_size); 701 if (IS_ERR(kid)) 702 return PTR_ERR(kid); 703 704 pr_debug("authkeyid %*phN\n", kid->len, kid->data); 705 ctx->cert->sig->auth_ids[0] = kid; 706 return 0; 707 } 708