1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* X.509 certificate parser
4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
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"
19 struct x509_parse_context {
20 struct x509_certificate *cert; /* Certificate being constructed */
21 unsigned long data; /* Start of data */
22 const void *key; /* Key data */
23 size_t key_size; /* Size of key data */
24 const void *params; /* Key parameters */
25 size_t params_size; /* Size of key parameters */
26 enum OID key_algo; /* Algorithm used by the cert's key */
27 enum OID last_oid; /* Last OID encountered */
28 enum OID sig_algo; /* Algorithm used to sign the cert */
29 u8 o_size; /* Size of organizationName (O) */
30 u8 cn_size; /* Size of commonName (CN) */
31 u8 email_size; /* Size of emailAddress */
32 u16 o_offset; /* Offset of organizationName (O) */
33 u16 cn_offset; /* Offset of commonName (CN) */
34 u16 email_offset; /* Offset of emailAddress */
35 unsigned raw_akid_size;
36 const void *raw_akid; /* Raw authorityKeyId in ASN.1 */
37 const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */
38 unsigned akid_raw_issuer_size;
42 * Free an X.509 certificate
44 void x509_free_certificate(struct x509_certificate *cert)
47 public_key_free(cert->pub);
48 public_key_signature_free(cert->sig);
56 EXPORT_SYMBOL_GPL(x509_free_certificate);
59 * Parse an X.509 certificate
61 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
63 struct x509_certificate *cert;
64 struct x509_parse_context *ctx;
65 struct asymmetric_key_id *kid;
69 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
72 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
75 cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
78 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
83 ctx->data = (unsigned long)data;
85 /* Attempt to decode the certificate */
86 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
90 /* Decode the AuthorityKeyIdentifier */
92 pr_devel("AKID: %u %*phN\n",
93 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
94 ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
95 ctx->raw_akid, ctx->raw_akid_size);
97 pr_warn("Couldn't decode AuthKeyIdentifier\n");
103 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
107 cert->pub->keylen = ctx->key_size;
109 cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
110 if (!cert->pub->params)
113 cert->pub->paramlen = ctx->params_size;
114 cert->pub->algo = ctx->key_algo;
116 /* Grab the signature bits */
117 ret = x509_get_sig_params(cert);
121 /* Generate cert issuer + serial number key ID */
122 kid = asymmetric_key_generate_id(cert->raw_serial,
123 cert->raw_serial_size,
125 cert->raw_issuer_size);
132 /* Detect self-signed certificates */
133 ret = x509_check_for_self_signed(cert);
143 x509_free_certificate(cert);
147 EXPORT_SYMBOL_GPL(x509_cert_parse);
150 * Note an OID when we find one for later processing when we know how
153 int x509_note_OID(void *context, size_t hdrlen,
155 const void *value, size_t vlen)
157 struct x509_parse_context *ctx = context;
159 ctx->last_oid = look_up_OID(value, vlen);
160 if (ctx->last_oid == OID__NR) {
162 sprint_oid(value, vlen, buffer, sizeof(buffer));
163 pr_debug("Unknown OID: [%lu] %s\n",
164 (unsigned long)value - ctx->data, buffer);
170 * Save the position of the TBS data so that we can check the signature over it
173 int x509_note_tbs_certificate(void *context, size_t hdrlen,
175 const void *value, size_t vlen)
177 struct x509_parse_context *ctx = context;
179 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
180 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
182 ctx->cert->tbs = value - hdrlen;
183 ctx->cert->tbs_size = vlen + hdrlen;
188 * Record the algorithm that was used to sign this certificate.
190 int x509_note_sig_algo(void *context, size_t hdrlen, unsigned char tag,
191 const void *value, size_t vlen)
193 struct x509_parse_context *ctx = context;
195 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
197 switch (ctx->last_oid) {
199 return -ENOPKG; /* Unsupported combination */
201 case OID_sha256WithRSAEncryption:
202 ctx->cert->sig->hash_algo = "sha256";
205 case OID_sha384WithRSAEncryption:
206 ctx->cert->sig->hash_algo = "sha384";
209 case OID_sha512WithRSAEncryption:
210 ctx->cert->sig->hash_algo = "sha512";
213 case OID_sha224WithRSAEncryption:
214 ctx->cert->sig->hash_algo = "sha224";
217 case OID_id_rsassa_pkcs1_v1_5_with_sha3_256:
218 ctx->cert->sig->hash_algo = "sha3-256";
221 case OID_id_rsassa_pkcs1_v1_5_with_sha3_384:
222 ctx->cert->sig->hash_algo = "sha3-384";
225 case OID_id_rsassa_pkcs1_v1_5_with_sha3_512:
226 ctx->cert->sig->hash_algo = "sha3-512";
229 case OID_id_ecdsa_with_sha224:
230 ctx->cert->sig->hash_algo = "sha224";
233 case OID_id_ecdsa_with_sha256:
234 ctx->cert->sig->hash_algo = "sha256";
237 case OID_id_ecdsa_with_sha384:
238 ctx->cert->sig->hash_algo = "sha384";
241 case OID_id_ecdsa_with_sha512:
242 ctx->cert->sig->hash_algo = "sha512";
245 case OID_id_ecdsa_with_sha3_256:
246 ctx->cert->sig->hash_algo = "sha3-256";
249 case OID_id_ecdsa_with_sha3_384:
250 ctx->cert->sig->hash_algo = "sha3-384";
253 case OID_id_ecdsa_with_sha3_512:
254 ctx->cert->sig->hash_algo = "sha3-512";
257 case OID_gost2012Signature256:
258 ctx->cert->sig->hash_algo = "streebog256";
261 case OID_gost2012Signature512:
262 ctx->cert->sig->hash_algo = "streebog512";
265 case OID_SM2_with_SM3:
266 ctx->cert->sig->hash_algo = "sm3";
271 ctx->cert->sig->pkey_algo = "rsa";
272 ctx->cert->sig->encoding = "pkcs1";
273 ctx->sig_algo = ctx->last_oid;
276 ctx->cert->sig->pkey_algo = "ecrdsa";
277 ctx->cert->sig->encoding = "raw";
278 ctx->sig_algo = ctx->last_oid;
281 ctx->cert->sig->pkey_algo = "sm2";
282 ctx->cert->sig->encoding = "raw";
283 ctx->sig_algo = ctx->last_oid;
286 ctx->cert->sig->pkey_algo = "ecdsa";
287 ctx->cert->sig->encoding = "x962";
288 ctx->sig_algo = ctx->last_oid;
293 * Note the whereabouts and type of the signature.
295 int x509_note_signature(void *context, size_t hdrlen,
297 const void *value, size_t vlen)
299 struct x509_parse_context *ctx = context;
301 pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
304 * In X.509 certificates, the signature's algorithm is stored in two
305 * places: inside the TBSCertificate (the data that is signed), and
306 * alongside the signature. These *must* match.
308 if (ctx->last_oid != ctx->sig_algo) {
309 pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n",
310 ctx->last_oid, ctx->sig_algo);
314 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
315 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
316 strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
317 strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
318 /* Discard the BIT STRING metadata */
319 if (vlen < 1 || *(const u8 *)value != 0)
326 ctx->cert->raw_sig = value;
327 ctx->cert->raw_sig_size = vlen;
332 * Note the certificate serial number
334 int x509_note_serial(void *context, size_t hdrlen,
336 const void *value, size_t vlen)
338 struct x509_parse_context *ctx = context;
339 ctx->cert->raw_serial = value;
340 ctx->cert->raw_serial_size = vlen;
345 * Note some of the name segments from which we'll fabricate a name.
347 int x509_extract_name_segment(void *context, size_t hdrlen,
349 const void *value, size_t vlen)
351 struct x509_parse_context *ctx = context;
353 switch (ctx->last_oid) {
356 ctx->cn_offset = (unsigned long)value - ctx->data;
358 case OID_organizationName:
360 ctx->o_offset = (unsigned long)value - ctx->data;
362 case OID_email_address:
363 ctx->email_size = vlen;
364 ctx->email_offset = (unsigned long)value - ctx->data;
374 * Fabricate and save the issuer and subject names
376 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
378 char **_name, size_t vlen)
380 const void *name, *data = (const void *)ctx->data;
387 /* Empty name string if no material */
388 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
389 buffer = kmalloc(1, GFP_KERNEL);
396 if (ctx->cn_size && ctx->o_size) {
397 /* Consider combining O and CN, but use only the CN if it is
398 * prefixed by the O, or a significant portion thereof.
400 namesize = ctx->cn_size;
401 name = data + ctx->cn_offset;
402 if (ctx->cn_size >= ctx->o_size &&
403 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
405 goto single_component;
406 if (ctx->cn_size >= 7 &&
408 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
409 goto single_component;
411 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
417 data + ctx->o_offset, ctx->o_size);
418 buffer[ctx->o_size + 0] = ':';
419 buffer[ctx->o_size + 1] = ' ';
420 memcpy(buffer + ctx->o_size + 2,
421 data + ctx->cn_offset, ctx->cn_size);
422 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
425 } else if (ctx->cn_size) {
426 namesize = ctx->cn_size;
427 name = data + ctx->cn_offset;
428 } else if (ctx->o_size) {
429 namesize = ctx->o_size;
430 name = data + ctx->o_offset;
432 namesize = ctx->email_size;
433 name = data + ctx->email_offset;
437 buffer = kmalloc(namesize + 1, GFP_KERNEL);
440 memcpy(buffer, name, namesize);
441 buffer[namesize] = 0;
451 int x509_note_issuer(void *context, size_t hdrlen,
453 const void *value, size_t vlen)
455 struct x509_parse_context *ctx = context;
456 struct asymmetric_key_id *kid;
458 ctx->cert->raw_issuer = value;
459 ctx->cert->raw_issuer_size = vlen;
461 if (!ctx->cert->sig->auth_ids[2]) {
462 kid = asymmetric_key_generate_id(value, vlen, "", 0);
465 ctx->cert->sig->auth_ids[2] = kid;
468 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
471 int x509_note_subject(void *context, size_t hdrlen,
473 const void *value, size_t vlen)
475 struct x509_parse_context *ctx = context;
476 ctx->cert->raw_subject = value;
477 ctx->cert->raw_subject_size = vlen;
478 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
482 * Extract the parameters for the public key
484 int x509_note_params(void *context, size_t hdrlen,
486 const void *value, size_t vlen)
488 struct x509_parse_context *ctx = context;
491 * AlgorithmIdentifier is used three times in the x509, we should skip
492 * first and ignore third, using second one which is after subject and
493 * before subjectPublicKey.
495 if (!ctx->cert->raw_subject || ctx->key)
497 ctx->params = value - hdrlen;
498 ctx->params_size = vlen + hdrlen;
503 * Extract the data for the public key algorithm
505 int x509_extract_key_data(void *context, size_t hdrlen,
507 const void *value, size_t vlen)
509 struct x509_parse_context *ctx = context;
512 ctx->key_algo = ctx->last_oid;
513 switch (ctx->last_oid) {
514 case OID_rsaEncryption:
515 ctx->cert->pub->pkey_algo = "rsa";
517 case OID_gost2012PKey256:
518 case OID_gost2012PKey512:
519 ctx->cert->pub->pkey_algo = "ecrdsa";
522 ctx->cert->pub->pkey_algo = "sm2";
524 case OID_id_ecPublicKey:
525 if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
530 ctx->cert->pub->pkey_algo = "sm2";
532 case OID_id_prime192v1:
533 ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
535 case OID_id_prime256v1:
536 ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
538 case OID_id_ansip384r1:
539 ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
549 /* Discard the BIT STRING metadata */
550 if (vlen < 1 || *(const u8 *)value != 0)
552 ctx->key = value + 1;
553 ctx->key_size = vlen - 1;
557 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
558 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
561 * Process certificate extensions that are used to qualify the certificate.
563 int x509_process_extension(void *context, size_t hdrlen,
565 const void *value, size_t vlen)
567 struct x509_parse_context *ctx = context;
568 struct asymmetric_key_id *kid;
569 const unsigned char *v = value;
571 pr_debug("Extension: %u\n", ctx->last_oid);
573 if (ctx->last_oid == OID_subjectKeyIdentifier) {
574 /* Get hold of the key fingerprint */
575 if (ctx->cert->skid || vlen < 3)
577 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
582 ctx->cert->raw_skid_size = vlen;
583 ctx->cert->raw_skid = v;
584 kid = asymmetric_key_generate_id(v, vlen, "", 0);
587 ctx->cert->skid = kid;
588 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
592 if (ctx->last_oid == OID_keyUsage) {
594 * Get hold of the keyUsage bit string
595 * v[1] is the encoding size
596 * (Expect either 0x02 or 0x03, making it 1 or 2 bytes)
597 * v[2] is the number of unused bits in the bit string
598 * (If >= 3 keyCertSign is missing when v[1] = 0x02)
599 * v[3] and possibly v[4] contain the bit string
601 * From RFC 5280 4.2.1.3:
602 * 0x04 is where keyCertSign lands in this bit string
603 * 0x80 is where digitalSignature lands in this bit string
605 if (v[0] != ASN1_BTS)
612 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG;
613 if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04))
614 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
615 else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04))
616 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
620 if (ctx->last_oid == OID_authorityKeyIdentifier) {
621 /* Get hold of the CA key fingerprint */
623 ctx->raw_akid_size = vlen;
627 if (ctx->last_oid == OID_basicConstraints) {
629 * Get hold of the basicConstraints
630 * v[1] is the encoding size
631 * (Expect 0x2 or greater, making it 1 or more bytes)
632 * v[2] is the encoding type
633 * (Expect an ASN1_BOOL for the CA)
634 * v[3] is the contents of the ASN1_BOOL
635 * (Expect 1 if the CA is TRUE)
636 * vlen should match the entire extension size
638 if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
642 if (v[1] != vlen - 2)
644 if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
645 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA;
653 * x509_decode_time - Decode an X.509 time ASN.1 object
654 * @_t: The time to fill in
655 * @hdrlen: The length of the object header
656 * @tag: The object tag
657 * @value: The object value
658 * @vlen: The size of the object value
660 * Decode an ASN.1 universal time or generalised time field into a struct the
661 * kernel can handle and check it for validity. The time is decoded thus:
663 * [RFC5280 ยง4.1.2.5]
664 * CAs conforming to this profile MUST always encode certificate validity
665 * dates through the year 2049 as UTCTime; certificate validity dates in
666 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
667 * applications MUST be able to process validity dates that are encoded in
668 * either UTCTime or GeneralizedTime.
670 int x509_decode_time(time64_t *_t, size_t hdrlen,
672 const unsigned char *value, size_t vlen)
674 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
675 31, 31, 30, 31, 30, 31 };
676 const unsigned char *p = value;
677 unsigned year, mon, day, hour, min, sec, mon_len;
679 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
680 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
682 if (tag == ASN1_UNITIM) {
683 /* UTCTime: YYMMDDHHMMSSZ */
685 goto unsupported_time;
691 } else if (tag == ASN1_GENTIM) {
692 /* GenTime: YYYYMMDDHHMMSSZ */
694 goto unsupported_time;
695 year = DD2bin(p) * 100 + DD2bin(p);
696 if (year >= 1950 && year <= 2049)
699 goto unsupported_time;
709 goto unsupported_time;
715 mon_len = month_lengths[mon - 1];
719 if (year % 100 == 0) {
727 if (day < 1 || day > mon_len ||
728 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
730 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
733 *_t = mktime64(year, mon, day, hour, min, sec);
737 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
738 tag, (int)vlen, value);
741 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
742 tag, (int)vlen, value);
745 EXPORT_SYMBOL_GPL(x509_decode_time);
747 int x509_note_not_before(void *context, size_t hdrlen,
749 const void *value, size_t vlen)
751 struct x509_parse_context *ctx = context;
752 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
755 int x509_note_not_after(void *context, size_t hdrlen,
757 const void *value, size_t vlen)
759 struct x509_parse_context *ctx = context;
760 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
764 * Note a key identifier-based AuthorityKeyIdentifier
766 int x509_akid_note_kid(void *context, size_t hdrlen,
768 const void *value, size_t vlen)
770 struct x509_parse_context *ctx = context;
771 struct asymmetric_key_id *kid;
773 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
775 if (ctx->cert->sig->auth_ids[1])
778 kid = asymmetric_key_generate_id(value, vlen, "", 0);
781 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
782 ctx->cert->sig->auth_ids[1] = kid;
787 * Note a directoryName in an AuthorityKeyIdentifier
789 int x509_akid_note_name(void *context, size_t hdrlen,
791 const void *value, size_t vlen)
793 struct x509_parse_context *ctx = context;
795 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
797 ctx->akid_raw_issuer = value;
798 ctx->akid_raw_issuer_size = vlen;
803 * Note a serial number in an AuthorityKeyIdentifier
805 int x509_akid_note_serial(void *context, size_t hdrlen,
807 const void *value, size_t vlen)
809 struct x509_parse_context *ctx = context;
810 struct asymmetric_key_id *kid;
812 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
814 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
817 kid = asymmetric_key_generate_id(value,
819 ctx->akid_raw_issuer,
820 ctx->akid_raw_issuer_size);
824 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
825 ctx->cert->sig->auth_ids[0] = kid;