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_sha1WithRSAEncryption:
202 ctx->cert->sig->hash_algo = "sha1";
205 case OID_sha256WithRSAEncryption:
206 ctx->cert->sig->hash_algo = "sha256";
209 case OID_sha384WithRSAEncryption:
210 ctx->cert->sig->hash_algo = "sha384";
213 case OID_sha512WithRSAEncryption:
214 ctx->cert->sig->hash_algo = "sha512";
217 case OID_sha224WithRSAEncryption:
218 ctx->cert->sig->hash_algo = "sha224";
221 case OID_id_ecdsa_with_sha1:
222 ctx->cert->sig->hash_algo = "sha1";
225 case OID_id_rsassa_pkcs1_v1_5_with_sha3_256:
226 ctx->cert->sig->hash_algo = "sha3-256";
229 case OID_id_rsassa_pkcs1_v1_5_with_sha3_384:
230 ctx->cert->sig->hash_algo = "sha3-384";
233 case OID_id_rsassa_pkcs1_v1_5_with_sha3_512:
234 ctx->cert->sig->hash_algo = "sha3-512";
237 case OID_id_ecdsa_with_sha224:
238 ctx->cert->sig->hash_algo = "sha224";
241 case OID_id_ecdsa_with_sha256:
242 ctx->cert->sig->hash_algo = "sha256";
245 case OID_id_ecdsa_with_sha384:
246 ctx->cert->sig->hash_algo = "sha384";
249 case OID_id_ecdsa_with_sha512:
250 ctx->cert->sig->hash_algo = "sha512";
253 case OID_id_ecdsa_with_sha3_256:
254 ctx->cert->sig->hash_algo = "sha3-256";
257 case OID_id_ecdsa_with_sha3_384:
258 ctx->cert->sig->hash_algo = "sha3-384";
261 case OID_id_ecdsa_with_sha3_512:
262 ctx->cert->sig->hash_algo = "sha3-512";
265 case OID_gost2012Signature256:
266 ctx->cert->sig->hash_algo = "streebog256";
269 case OID_gost2012Signature512:
270 ctx->cert->sig->hash_algo = "streebog512";
273 case OID_SM2_with_SM3:
274 ctx->cert->sig->hash_algo = "sm3";
279 ctx->cert->sig->pkey_algo = "rsa";
280 ctx->cert->sig->encoding = "pkcs1";
281 ctx->sig_algo = ctx->last_oid;
284 ctx->cert->sig->pkey_algo = "ecrdsa";
285 ctx->cert->sig->encoding = "raw";
286 ctx->sig_algo = ctx->last_oid;
289 ctx->cert->sig->pkey_algo = "sm2";
290 ctx->cert->sig->encoding = "raw";
291 ctx->sig_algo = ctx->last_oid;
294 ctx->cert->sig->pkey_algo = "ecdsa";
295 ctx->cert->sig->encoding = "x962";
296 ctx->sig_algo = ctx->last_oid;
301 * Note the whereabouts and type of the signature.
303 int x509_note_signature(void *context, size_t hdrlen,
305 const void *value, size_t vlen)
307 struct x509_parse_context *ctx = context;
309 pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
312 * In X.509 certificates, the signature's algorithm is stored in two
313 * places: inside the TBSCertificate (the data that is signed), and
314 * alongside the signature. These *must* match.
316 if (ctx->last_oid != ctx->sig_algo) {
317 pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n",
318 ctx->last_oid, ctx->sig_algo);
322 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
323 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
324 strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
325 strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
326 /* Discard the BIT STRING metadata */
327 if (vlen < 1 || *(const u8 *)value != 0)
334 ctx->cert->raw_sig = value;
335 ctx->cert->raw_sig_size = vlen;
340 * Note the certificate serial number
342 int x509_note_serial(void *context, size_t hdrlen,
344 const void *value, size_t vlen)
346 struct x509_parse_context *ctx = context;
347 ctx->cert->raw_serial = value;
348 ctx->cert->raw_serial_size = vlen;
353 * Note some of the name segments from which we'll fabricate a name.
355 int x509_extract_name_segment(void *context, size_t hdrlen,
357 const void *value, size_t vlen)
359 struct x509_parse_context *ctx = context;
361 switch (ctx->last_oid) {
364 ctx->cn_offset = (unsigned long)value - ctx->data;
366 case OID_organizationName:
368 ctx->o_offset = (unsigned long)value - ctx->data;
370 case OID_email_address:
371 ctx->email_size = vlen;
372 ctx->email_offset = (unsigned long)value - ctx->data;
382 * Fabricate and save the issuer and subject names
384 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
386 char **_name, size_t vlen)
388 const void *name, *data = (const void *)ctx->data;
395 /* Empty name string if no material */
396 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
397 buffer = kmalloc(1, GFP_KERNEL);
404 if (ctx->cn_size && ctx->o_size) {
405 /* Consider combining O and CN, but use only the CN if it is
406 * prefixed by the O, or a significant portion thereof.
408 namesize = ctx->cn_size;
409 name = data + ctx->cn_offset;
410 if (ctx->cn_size >= ctx->o_size &&
411 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
413 goto single_component;
414 if (ctx->cn_size >= 7 &&
416 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
417 goto single_component;
419 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
425 data + ctx->o_offset, ctx->o_size);
426 buffer[ctx->o_size + 0] = ':';
427 buffer[ctx->o_size + 1] = ' ';
428 memcpy(buffer + ctx->o_size + 2,
429 data + ctx->cn_offset, ctx->cn_size);
430 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
433 } else if (ctx->cn_size) {
434 namesize = ctx->cn_size;
435 name = data + ctx->cn_offset;
436 } else if (ctx->o_size) {
437 namesize = ctx->o_size;
438 name = data + ctx->o_offset;
440 namesize = ctx->email_size;
441 name = data + ctx->email_offset;
445 buffer = kmalloc(namesize + 1, GFP_KERNEL);
448 memcpy(buffer, name, namesize);
449 buffer[namesize] = 0;
459 int x509_note_issuer(void *context, size_t hdrlen,
461 const void *value, size_t vlen)
463 struct x509_parse_context *ctx = context;
464 struct asymmetric_key_id *kid;
466 ctx->cert->raw_issuer = value;
467 ctx->cert->raw_issuer_size = vlen;
469 if (!ctx->cert->sig->auth_ids[2]) {
470 kid = asymmetric_key_generate_id(value, vlen, "", 0);
473 ctx->cert->sig->auth_ids[2] = kid;
476 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
479 int x509_note_subject(void *context, size_t hdrlen,
481 const void *value, size_t vlen)
483 struct x509_parse_context *ctx = context;
484 ctx->cert->raw_subject = value;
485 ctx->cert->raw_subject_size = vlen;
486 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
490 * Extract the parameters for the public key
492 int x509_note_params(void *context, size_t hdrlen,
494 const void *value, size_t vlen)
496 struct x509_parse_context *ctx = context;
499 * AlgorithmIdentifier is used three times in the x509, we should skip
500 * first and ignore third, using second one which is after subject and
501 * before subjectPublicKey.
503 if (!ctx->cert->raw_subject || ctx->key)
505 ctx->params = value - hdrlen;
506 ctx->params_size = vlen + hdrlen;
511 * Extract the data for the public key algorithm
513 int x509_extract_key_data(void *context, size_t hdrlen,
515 const void *value, size_t vlen)
517 struct x509_parse_context *ctx = context;
520 ctx->key_algo = ctx->last_oid;
521 switch (ctx->last_oid) {
522 case OID_rsaEncryption:
523 ctx->cert->pub->pkey_algo = "rsa";
525 case OID_gost2012PKey256:
526 case OID_gost2012PKey512:
527 ctx->cert->pub->pkey_algo = "ecrdsa";
530 ctx->cert->pub->pkey_algo = "sm2";
532 case OID_id_ecPublicKey:
533 if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
538 ctx->cert->pub->pkey_algo = "sm2";
540 case OID_id_prime192v1:
541 ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
543 case OID_id_prime256v1:
544 ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
546 case OID_id_ansip384r1:
547 ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
557 /* Discard the BIT STRING metadata */
558 if (vlen < 1 || *(const u8 *)value != 0)
560 ctx->key = value + 1;
561 ctx->key_size = vlen - 1;
565 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
566 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
569 * Process certificate extensions that are used to qualify the certificate.
571 int x509_process_extension(void *context, size_t hdrlen,
573 const void *value, size_t vlen)
575 struct x509_parse_context *ctx = context;
576 struct asymmetric_key_id *kid;
577 const unsigned char *v = value;
579 pr_debug("Extension: %u\n", ctx->last_oid);
581 if (ctx->last_oid == OID_subjectKeyIdentifier) {
582 /* Get hold of the key fingerprint */
583 if (ctx->cert->skid || vlen < 3)
585 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
590 ctx->cert->raw_skid_size = vlen;
591 ctx->cert->raw_skid = v;
592 kid = asymmetric_key_generate_id(v, vlen, "", 0);
595 ctx->cert->skid = kid;
596 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
600 if (ctx->last_oid == OID_keyUsage) {
602 * Get hold of the keyUsage bit string
603 * v[1] is the encoding size
604 * (Expect either 0x02 or 0x03, making it 1 or 2 bytes)
605 * v[2] is the number of unused bits in the bit string
606 * (If >= 3 keyCertSign is missing when v[1] = 0x02)
607 * v[3] and possibly v[4] contain the bit string
609 * From RFC 5280 4.2.1.3:
610 * 0x04 is where keyCertSign lands in this bit string
611 * 0x80 is where digitalSignature lands in this bit string
613 if (v[0] != ASN1_BTS)
620 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG;
621 if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04))
622 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
623 else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04))
624 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
628 if (ctx->last_oid == OID_authorityKeyIdentifier) {
629 /* Get hold of the CA key fingerprint */
631 ctx->raw_akid_size = vlen;
635 if (ctx->last_oid == OID_basicConstraints) {
637 * Get hold of the basicConstraints
638 * v[1] is the encoding size
639 * (Expect 0x2 or greater, making it 1 or more bytes)
640 * v[2] is the encoding type
641 * (Expect an ASN1_BOOL for the CA)
642 * v[3] is the contents of the ASN1_BOOL
643 * (Expect 1 if the CA is TRUE)
644 * vlen should match the entire extension size
646 if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
650 if (v[1] != vlen - 2)
652 if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
653 ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA;
661 * x509_decode_time - Decode an X.509 time ASN.1 object
662 * @_t: The time to fill in
663 * @hdrlen: The length of the object header
664 * @tag: The object tag
665 * @value: The object value
666 * @vlen: The size of the object value
668 * Decode an ASN.1 universal time or generalised time field into a struct the
669 * kernel can handle and check it for validity. The time is decoded thus:
671 * [RFC5280 ยง4.1.2.5]
672 * CAs conforming to this profile MUST always encode certificate validity
673 * dates through the year 2049 as UTCTime; certificate validity dates in
674 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
675 * applications MUST be able to process validity dates that are encoded in
676 * either UTCTime or GeneralizedTime.
678 int x509_decode_time(time64_t *_t, size_t hdrlen,
680 const unsigned char *value, size_t vlen)
682 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
683 31, 31, 30, 31, 30, 31 };
684 const unsigned char *p = value;
685 unsigned year, mon, day, hour, min, sec, mon_len;
687 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
688 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
690 if (tag == ASN1_UNITIM) {
691 /* UTCTime: YYMMDDHHMMSSZ */
693 goto unsupported_time;
699 } else if (tag == ASN1_GENTIM) {
700 /* GenTime: YYYYMMDDHHMMSSZ */
702 goto unsupported_time;
703 year = DD2bin(p) * 100 + DD2bin(p);
704 if (year >= 1950 && year <= 2049)
707 goto unsupported_time;
717 goto unsupported_time;
723 mon_len = month_lengths[mon - 1];
727 if (year % 100 == 0) {
735 if (day < 1 || day > mon_len ||
736 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
738 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
741 *_t = mktime64(year, mon, day, hour, min, sec);
745 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
746 tag, (int)vlen, value);
749 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
750 tag, (int)vlen, value);
753 EXPORT_SYMBOL_GPL(x509_decode_time);
755 int x509_note_not_before(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_from, hdrlen, tag, value, vlen);
763 int x509_note_not_after(void *context, size_t hdrlen,
765 const void *value, size_t vlen)
767 struct x509_parse_context *ctx = context;
768 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
772 * Note a key identifier-based AuthorityKeyIdentifier
774 int x509_akid_note_kid(void *context, size_t hdrlen,
776 const void *value, size_t vlen)
778 struct x509_parse_context *ctx = context;
779 struct asymmetric_key_id *kid;
781 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
783 if (ctx->cert->sig->auth_ids[1])
786 kid = asymmetric_key_generate_id(value, vlen, "", 0);
789 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
790 ctx->cert->sig->auth_ids[1] = kid;
795 * Note a directoryName in an AuthorityKeyIdentifier
797 int x509_akid_note_name(void *context, size_t hdrlen,
799 const void *value, size_t vlen)
801 struct x509_parse_context *ctx = context;
803 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
805 ctx->akid_raw_issuer = value;
806 ctx->akid_raw_issuer_size = vlen;
811 * Note a serial number in an AuthorityKeyIdentifier
813 int x509_akid_note_serial(void *context, size_t hdrlen,
815 const void *value, size_t vlen)
817 struct x509_parse_context *ctx = context;
818 struct asymmetric_key_id *kid;
820 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
822 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
825 kid = asymmetric_key_generate_id(value,
827 ctx->akid_raw_issuer,
828 ctx->akid_raw_issuer_size);
832 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
833 ctx->cert->sig->auth_ids[0] = kid;