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 } 238 239 rsa_pkcs1: 240 ctx->cert->sig->pkey_algo = "rsa"; 241 ctx->cert->sig->encoding = "pkcs1"; 242 ctx->algo_oid = ctx->last_oid; 243 return 0; 244 ecrdsa: 245 ctx->cert->sig->pkey_algo = "ecrdsa"; 246 ctx->cert->sig->encoding = "raw"; 247 ctx->algo_oid = ctx->last_oid; 248 return 0; 249 } 250 251 /* 252 * Note the whereabouts and type of the signature. 253 */ 254 int x509_note_signature(void *context, size_t hdrlen, 255 unsigned char tag, 256 const void *value, size_t vlen) 257 { 258 struct x509_parse_context *ctx = context; 259 260 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen); 261 262 if (ctx->last_oid != ctx->algo_oid) { 263 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n", 264 ctx->algo_oid, ctx->last_oid); 265 return -EINVAL; 266 } 267 268 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 || 269 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0) { 270 /* Discard the BIT STRING metadata */ 271 if (vlen < 1 || *(const u8 *)value != 0) 272 return -EBADMSG; 273 274 value++; 275 vlen--; 276 } 277 278 ctx->cert->raw_sig = value; 279 ctx->cert->raw_sig_size = vlen; 280 return 0; 281 } 282 283 /* 284 * Note the certificate serial number 285 */ 286 int x509_note_serial(void *context, size_t hdrlen, 287 unsigned char tag, 288 const void *value, size_t vlen) 289 { 290 struct x509_parse_context *ctx = context; 291 ctx->cert->raw_serial = value; 292 ctx->cert->raw_serial_size = vlen; 293 return 0; 294 } 295 296 /* 297 * Note some of the name segments from which we'll fabricate a name. 298 */ 299 int x509_extract_name_segment(void *context, size_t hdrlen, 300 unsigned char tag, 301 const void *value, size_t vlen) 302 { 303 struct x509_parse_context *ctx = context; 304 305 switch (ctx->last_oid) { 306 case OID_commonName: 307 ctx->cn_size = vlen; 308 ctx->cn_offset = (unsigned long)value - ctx->data; 309 break; 310 case OID_organizationName: 311 ctx->o_size = vlen; 312 ctx->o_offset = (unsigned long)value - ctx->data; 313 break; 314 case OID_email_address: 315 ctx->email_size = vlen; 316 ctx->email_offset = (unsigned long)value - ctx->data; 317 break; 318 default: 319 break; 320 } 321 322 return 0; 323 } 324 325 /* 326 * Fabricate and save the issuer and subject names 327 */ 328 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen, 329 unsigned char tag, 330 char **_name, size_t vlen) 331 { 332 const void *name, *data = (const void *)ctx->data; 333 size_t namesize; 334 char *buffer; 335 336 if (*_name) 337 return -EINVAL; 338 339 /* Empty name string if no material */ 340 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) { 341 buffer = kmalloc(1, GFP_KERNEL); 342 if (!buffer) 343 return -ENOMEM; 344 buffer[0] = 0; 345 goto done; 346 } 347 348 if (ctx->cn_size && ctx->o_size) { 349 /* Consider combining O and CN, but use only the CN if it is 350 * prefixed by the O, or a significant portion thereof. 351 */ 352 namesize = ctx->cn_size; 353 name = data + ctx->cn_offset; 354 if (ctx->cn_size >= ctx->o_size && 355 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 356 ctx->o_size) == 0) 357 goto single_component; 358 if (ctx->cn_size >= 7 && 359 ctx->o_size >= 7 && 360 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0) 361 goto single_component; 362 363 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1, 364 GFP_KERNEL); 365 if (!buffer) 366 return -ENOMEM; 367 368 memcpy(buffer, 369 data + ctx->o_offset, ctx->o_size); 370 buffer[ctx->o_size + 0] = ':'; 371 buffer[ctx->o_size + 1] = ' '; 372 memcpy(buffer + ctx->o_size + 2, 373 data + ctx->cn_offset, ctx->cn_size); 374 buffer[ctx->o_size + 2 + ctx->cn_size] = 0; 375 goto done; 376 377 } else if (ctx->cn_size) { 378 namesize = ctx->cn_size; 379 name = data + ctx->cn_offset; 380 } else if (ctx->o_size) { 381 namesize = ctx->o_size; 382 name = data + ctx->o_offset; 383 } else { 384 namesize = ctx->email_size; 385 name = data + ctx->email_offset; 386 } 387 388 single_component: 389 buffer = kmalloc(namesize + 1, GFP_KERNEL); 390 if (!buffer) 391 return -ENOMEM; 392 memcpy(buffer, name, namesize); 393 buffer[namesize] = 0; 394 395 done: 396 *_name = buffer; 397 ctx->cn_size = 0; 398 ctx->o_size = 0; 399 ctx->email_size = 0; 400 return 0; 401 } 402 403 int x509_note_issuer(void *context, size_t hdrlen, 404 unsigned char tag, 405 const void *value, size_t vlen) 406 { 407 struct x509_parse_context *ctx = context; 408 ctx->cert->raw_issuer = value; 409 ctx->cert->raw_issuer_size = vlen; 410 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen); 411 } 412 413 int x509_note_subject(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_subject = value; 419 ctx->cert->raw_subject_size = vlen; 420 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen); 421 } 422 423 /* 424 * Extract the parameters for the public key 425 */ 426 int x509_note_params(void *context, size_t hdrlen, 427 unsigned char tag, 428 const void *value, size_t vlen) 429 { 430 struct x509_parse_context *ctx = context; 431 432 /* 433 * AlgorithmIdentifier is used three times in the x509, we should skip 434 * first and ignore third, using second one which is after subject and 435 * before subjectPublicKey. 436 */ 437 if (!ctx->cert->raw_subject || ctx->key) 438 return 0; 439 ctx->params = value - hdrlen; 440 ctx->params_size = vlen + hdrlen; 441 return 0; 442 } 443 444 /* 445 * Extract the data for the public key algorithm 446 */ 447 int x509_extract_key_data(void *context, size_t hdrlen, 448 unsigned char tag, 449 const void *value, size_t vlen) 450 { 451 struct x509_parse_context *ctx = context; 452 453 ctx->key_algo = ctx->last_oid; 454 if (ctx->last_oid == OID_rsaEncryption) 455 ctx->cert->pub->pkey_algo = "rsa"; 456 else if (ctx->last_oid == OID_gost2012PKey256 || 457 ctx->last_oid == OID_gost2012PKey512) 458 ctx->cert->pub->pkey_algo = "ecrdsa"; 459 else 460 return -ENOPKG; 461 462 /* Discard the BIT STRING metadata */ 463 if (vlen < 1 || *(const u8 *)value != 0) 464 return -EBADMSG; 465 ctx->key = value + 1; 466 ctx->key_size = vlen - 1; 467 return 0; 468 } 469 470 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */ 471 #define SEQ_TAG_KEYID (ASN1_CONT << 6) 472 473 /* 474 * Process certificate extensions that are used to qualify the certificate. 475 */ 476 int x509_process_extension(void *context, size_t hdrlen, 477 unsigned char tag, 478 const void *value, size_t vlen) 479 { 480 struct x509_parse_context *ctx = context; 481 struct asymmetric_key_id *kid; 482 const unsigned char *v = value; 483 484 pr_debug("Extension: %u\n", ctx->last_oid); 485 486 if (ctx->last_oid == OID_subjectKeyIdentifier) { 487 /* Get hold of the key fingerprint */ 488 if (ctx->cert->skid || vlen < 3) 489 return -EBADMSG; 490 if (v[0] != ASN1_OTS || v[1] != vlen - 2) 491 return -EBADMSG; 492 v += 2; 493 vlen -= 2; 494 495 ctx->cert->raw_skid_size = vlen; 496 ctx->cert->raw_skid = v; 497 kid = asymmetric_key_generate_id(v, vlen, "", 0); 498 if (IS_ERR(kid)) 499 return PTR_ERR(kid); 500 ctx->cert->skid = kid; 501 pr_debug("subjkeyid %*phN\n", kid->len, kid->data); 502 return 0; 503 } 504 505 if (ctx->last_oid == OID_authorityKeyIdentifier) { 506 /* Get hold of the CA key fingerprint */ 507 ctx->raw_akid = v; 508 ctx->raw_akid_size = vlen; 509 return 0; 510 } 511 512 return 0; 513 } 514 515 /** 516 * x509_decode_time - Decode an X.509 time ASN.1 object 517 * @_t: The time to fill in 518 * @hdrlen: The length of the object header 519 * @tag: The object tag 520 * @value: The object value 521 * @vlen: The size of the object value 522 * 523 * Decode an ASN.1 universal time or generalised time field into a struct the 524 * kernel can handle and check it for validity. The time is decoded thus: 525 * 526 * [RFC5280 §4.1.2.5] 527 * CAs conforming to this profile MUST always encode certificate validity 528 * dates through the year 2049 as UTCTime; certificate validity dates in 529 * 2050 or later MUST be encoded as GeneralizedTime. Conforming 530 * applications MUST be able to process validity dates that are encoded in 531 * either UTCTime or GeneralizedTime. 532 */ 533 int x509_decode_time(time64_t *_t, size_t hdrlen, 534 unsigned char tag, 535 const unsigned char *value, size_t vlen) 536 { 537 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30, 538 31, 31, 30, 31, 30, 31 }; 539 const unsigned char *p = value; 540 unsigned year, mon, day, hour, min, sec, mon_len; 541 542 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; }) 543 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; }) 544 545 if (tag == ASN1_UNITIM) { 546 /* UTCTime: YYMMDDHHMMSSZ */ 547 if (vlen != 13) 548 goto unsupported_time; 549 year = DD2bin(p); 550 if (year >= 50) 551 year += 1900; 552 else 553 year += 2000; 554 } else if (tag == ASN1_GENTIM) { 555 /* GenTime: YYYYMMDDHHMMSSZ */ 556 if (vlen != 15) 557 goto unsupported_time; 558 year = DD2bin(p) * 100 + DD2bin(p); 559 if (year >= 1950 && year <= 2049) 560 goto invalid_time; 561 } else { 562 goto unsupported_time; 563 } 564 565 mon = DD2bin(p); 566 day = DD2bin(p); 567 hour = DD2bin(p); 568 min = DD2bin(p); 569 sec = DD2bin(p); 570 571 if (*p != 'Z') 572 goto unsupported_time; 573 574 if (year < 1970 || 575 mon < 1 || mon > 12) 576 goto invalid_time; 577 578 mon_len = month_lengths[mon - 1]; 579 if (mon == 2) { 580 if (year % 4 == 0) { 581 mon_len = 29; 582 if (year % 100 == 0) { 583 mon_len = 28; 584 if (year % 400 == 0) 585 mon_len = 29; 586 } 587 } 588 } 589 590 if (day < 1 || day > mon_len || 591 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */ 592 min > 59 || 593 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */ 594 goto invalid_time; 595 596 *_t = mktime64(year, mon, day, hour, min, sec); 597 return 0; 598 599 unsupported_time: 600 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n", 601 tag, (int)vlen, value); 602 return -EBADMSG; 603 invalid_time: 604 pr_debug("Got invalid time [tag %02x]: '%*phN'\n", 605 tag, (int)vlen, value); 606 return -EBADMSG; 607 } 608 EXPORT_SYMBOL_GPL(x509_decode_time); 609 610 int x509_note_not_before(void *context, size_t hdrlen, 611 unsigned char tag, 612 const void *value, size_t vlen) 613 { 614 struct x509_parse_context *ctx = context; 615 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen); 616 } 617 618 int x509_note_not_after(void *context, size_t hdrlen, 619 unsigned char tag, 620 const void *value, size_t vlen) 621 { 622 struct x509_parse_context *ctx = context; 623 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen); 624 } 625 626 /* 627 * Note a key identifier-based AuthorityKeyIdentifier 628 */ 629 int x509_akid_note_kid(void *context, size_t hdrlen, 630 unsigned char tag, 631 const void *value, size_t vlen) 632 { 633 struct x509_parse_context *ctx = context; 634 struct asymmetric_key_id *kid; 635 636 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value); 637 638 if (ctx->cert->sig->auth_ids[1]) 639 return 0; 640 641 kid = asymmetric_key_generate_id(value, vlen, "", 0); 642 if (IS_ERR(kid)) 643 return PTR_ERR(kid); 644 pr_debug("authkeyid %*phN\n", kid->len, kid->data); 645 ctx->cert->sig->auth_ids[1] = kid; 646 return 0; 647 } 648 649 /* 650 * Note a directoryName in an AuthorityKeyIdentifier 651 */ 652 int x509_akid_note_name(void *context, size_t hdrlen, 653 unsigned char tag, 654 const void *value, size_t vlen) 655 { 656 struct x509_parse_context *ctx = context; 657 658 pr_debug("AKID: name: %*phN\n", (int)vlen, value); 659 660 ctx->akid_raw_issuer = value; 661 ctx->akid_raw_issuer_size = vlen; 662 return 0; 663 } 664 665 /* 666 * Note a serial number in an AuthorityKeyIdentifier 667 */ 668 int x509_akid_note_serial(void *context, size_t hdrlen, 669 unsigned char tag, 670 const void *value, size_t vlen) 671 { 672 struct x509_parse_context *ctx = context; 673 struct asymmetric_key_id *kid; 674 675 pr_debug("AKID: serial: %*phN\n", (int)vlen, value); 676 677 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0]) 678 return 0; 679 680 kid = asymmetric_key_generate_id(value, 681 vlen, 682 ctx->akid_raw_issuer, 683 ctx->akid_raw_issuer_size); 684 if (IS_ERR(kid)) 685 return PTR_ERR(kid); 686 687 pr_debug("authkeyid %*phN\n", kid->len, kid->data); 688 ctx->cert->sig->auth_ids[0] = kid; 689 return 0; 690 } 691