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) {
198 case OID_md2WithRSAEncryption:
199 case OID_md3WithRSAEncryption:
201 return -ENOPKG; /* Unsupported combination */
203 case OID_md4WithRSAEncryption:
204 ctx->cert->sig->hash_algo = "md4";
207 case OID_sha1WithRSAEncryption:
208 ctx->cert->sig->hash_algo = "sha1";
211 case OID_sha256WithRSAEncryption:
212 ctx->cert->sig->hash_algo = "sha256";
215 case OID_sha384WithRSAEncryption:
216 ctx->cert->sig->hash_algo = "sha384";
219 case OID_sha512WithRSAEncryption:
220 ctx->cert->sig->hash_algo = "sha512";
223 case OID_sha224WithRSAEncryption:
224 ctx->cert->sig->hash_algo = "sha224";
227 case OID_id_ecdsa_with_sha1:
228 ctx->cert->sig->hash_algo = "sha1";
231 case OID_id_ecdsa_with_sha224:
232 ctx->cert->sig->hash_algo = "sha224";
235 case OID_id_ecdsa_with_sha256:
236 ctx->cert->sig->hash_algo = "sha256";
239 case OID_id_ecdsa_with_sha384:
240 ctx->cert->sig->hash_algo = "sha384";
243 case OID_id_ecdsa_with_sha512:
244 ctx->cert->sig->hash_algo = "sha512";
247 case OID_gost2012Signature256:
248 ctx->cert->sig->hash_algo = "streebog256";
251 case OID_gost2012Signature512:
252 ctx->cert->sig->hash_algo = "streebog512";
255 case OID_SM2_with_SM3:
256 ctx->cert->sig->hash_algo = "sm3";
261 ctx->cert->sig->pkey_algo = "rsa";
262 ctx->cert->sig->encoding = "pkcs1";
263 ctx->sig_algo = ctx->last_oid;
266 ctx->cert->sig->pkey_algo = "ecrdsa";
267 ctx->cert->sig->encoding = "raw";
268 ctx->sig_algo = ctx->last_oid;
271 ctx->cert->sig->pkey_algo = "sm2";
272 ctx->cert->sig->encoding = "raw";
273 ctx->sig_algo = ctx->last_oid;
276 ctx->cert->sig->pkey_algo = "ecdsa";
277 ctx->cert->sig->encoding = "x962";
278 ctx->sig_algo = ctx->last_oid;
283 * Note the whereabouts and type of the signature.
285 int x509_note_signature(void *context, size_t hdrlen,
287 const void *value, size_t vlen)
289 struct x509_parse_context *ctx = context;
291 pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
294 * In X.509 certificates, the signature's algorithm is stored in two
295 * places: inside the TBSCertificate (the data that is signed), and
296 * alongside the signature. These *must* match.
298 if (ctx->last_oid != ctx->sig_algo) {
299 pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n",
300 ctx->last_oid, ctx->sig_algo);
304 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
305 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
306 strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
307 strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
308 /* Discard the BIT STRING metadata */
309 if (vlen < 1 || *(const u8 *)value != 0)
316 ctx->cert->raw_sig = value;
317 ctx->cert->raw_sig_size = vlen;
322 * Note the certificate serial number
324 int x509_note_serial(void *context, size_t hdrlen,
326 const void *value, size_t vlen)
328 struct x509_parse_context *ctx = context;
329 ctx->cert->raw_serial = value;
330 ctx->cert->raw_serial_size = vlen;
335 * Note some of the name segments from which we'll fabricate a name.
337 int x509_extract_name_segment(void *context, size_t hdrlen,
339 const void *value, size_t vlen)
341 struct x509_parse_context *ctx = context;
343 switch (ctx->last_oid) {
346 ctx->cn_offset = (unsigned long)value - ctx->data;
348 case OID_organizationName:
350 ctx->o_offset = (unsigned long)value - ctx->data;
352 case OID_email_address:
353 ctx->email_size = vlen;
354 ctx->email_offset = (unsigned long)value - ctx->data;
364 * Fabricate and save the issuer and subject names
366 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
368 char **_name, size_t vlen)
370 const void *name, *data = (const void *)ctx->data;
377 /* Empty name string if no material */
378 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
379 buffer = kmalloc(1, GFP_KERNEL);
386 if (ctx->cn_size && ctx->o_size) {
387 /* Consider combining O and CN, but use only the CN if it is
388 * prefixed by the O, or a significant portion thereof.
390 namesize = ctx->cn_size;
391 name = data + ctx->cn_offset;
392 if (ctx->cn_size >= ctx->o_size &&
393 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
395 goto single_component;
396 if (ctx->cn_size >= 7 &&
398 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
399 goto single_component;
401 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
407 data + ctx->o_offset, ctx->o_size);
408 buffer[ctx->o_size + 0] = ':';
409 buffer[ctx->o_size + 1] = ' ';
410 memcpy(buffer + ctx->o_size + 2,
411 data + ctx->cn_offset, ctx->cn_size);
412 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
415 } else if (ctx->cn_size) {
416 namesize = ctx->cn_size;
417 name = data + ctx->cn_offset;
418 } else if (ctx->o_size) {
419 namesize = ctx->o_size;
420 name = data + ctx->o_offset;
422 namesize = ctx->email_size;
423 name = data + ctx->email_offset;
427 buffer = kmalloc(namesize + 1, GFP_KERNEL);
430 memcpy(buffer, name, namesize);
431 buffer[namesize] = 0;
441 int x509_note_issuer(void *context, size_t hdrlen,
443 const void *value, size_t vlen)
445 struct x509_parse_context *ctx = context;
446 struct asymmetric_key_id *kid;
448 ctx->cert->raw_issuer = value;
449 ctx->cert->raw_issuer_size = vlen;
451 if (!ctx->cert->sig->auth_ids[2]) {
452 kid = asymmetric_key_generate_id(value, vlen, "", 0);
455 ctx->cert->sig->auth_ids[2] = kid;
458 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
461 int x509_note_subject(void *context, size_t hdrlen,
463 const void *value, size_t vlen)
465 struct x509_parse_context *ctx = context;
466 ctx->cert->raw_subject = value;
467 ctx->cert->raw_subject_size = vlen;
468 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
472 * Extract the parameters for the public key
474 int x509_note_params(void *context, size_t hdrlen,
476 const void *value, size_t vlen)
478 struct x509_parse_context *ctx = context;
481 * AlgorithmIdentifier is used three times in the x509, we should skip
482 * first and ignore third, using second one which is after subject and
483 * before subjectPublicKey.
485 if (!ctx->cert->raw_subject || ctx->key)
487 ctx->params = value - hdrlen;
488 ctx->params_size = vlen + hdrlen;
493 * Extract the data for the public key algorithm
495 int x509_extract_key_data(void *context, size_t hdrlen,
497 const void *value, size_t vlen)
499 struct x509_parse_context *ctx = context;
502 ctx->key_algo = ctx->last_oid;
503 switch (ctx->last_oid) {
504 case OID_rsaEncryption:
505 ctx->cert->pub->pkey_algo = "rsa";
507 case OID_gost2012PKey256:
508 case OID_gost2012PKey512:
509 ctx->cert->pub->pkey_algo = "ecrdsa";
512 ctx->cert->pub->pkey_algo = "sm2";
514 case OID_id_ecPublicKey:
515 if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
520 ctx->cert->pub->pkey_algo = "sm2";
522 case OID_id_prime192v1:
523 ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
525 case OID_id_prime256v1:
526 ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
528 case OID_id_ansip384r1:
529 ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
539 /* Discard the BIT STRING metadata */
540 if (vlen < 1 || *(const u8 *)value != 0)
542 ctx->key = value + 1;
543 ctx->key_size = vlen - 1;
547 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
548 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
551 * Process certificate extensions that are used to qualify the certificate.
553 int x509_process_extension(void *context, size_t hdrlen,
555 const void *value, size_t vlen)
557 struct x509_parse_context *ctx = context;
558 struct asymmetric_key_id *kid;
559 const unsigned char *v = value;
561 pr_debug("Extension: %u\n", ctx->last_oid);
563 if (ctx->last_oid == OID_subjectKeyIdentifier) {
564 /* Get hold of the key fingerprint */
565 if (ctx->cert->skid || vlen < 3)
567 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
572 ctx->cert->raw_skid_size = vlen;
573 ctx->cert->raw_skid = v;
574 kid = asymmetric_key_generate_id(v, vlen, "", 0);
577 ctx->cert->skid = kid;
578 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
582 if (ctx->last_oid == OID_authorityKeyIdentifier) {
583 /* Get hold of the CA key fingerprint */
585 ctx->raw_akid_size = vlen;
593 * x509_decode_time - Decode an X.509 time ASN.1 object
594 * @_t: The time to fill in
595 * @hdrlen: The length of the object header
596 * @tag: The object tag
597 * @value: The object value
598 * @vlen: The size of the object value
600 * Decode an ASN.1 universal time or generalised time field into a struct the
601 * kernel can handle and check it for validity. The time is decoded thus:
603 * [RFC5280 ยง4.1.2.5]
604 * CAs conforming to this profile MUST always encode certificate validity
605 * dates through the year 2049 as UTCTime; certificate validity dates in
606 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
607 * applications MUST be able to process validity dates that are encoded in
608 * either UTCTime or GeneralizedTime.
610 int x509_decode_time(time64_t *_t, size_t hdrlen,
612 const unsigned char *value, size_t vlen)
614 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
615 31, 31, 30, 31, 30, 31 };
616 const unsigned char *p = value;
617 unsigned year, mon, day, hour, min, sec, mon_len;
619 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
620 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
622 if (tag == ASN1_UNITIM) {
623 /* UTCTime: YYMMDDHHMMSSZ */
625 goto unsupported_time;
631 } else if (tag == ASN1_GENTIM) {
632 /* GenTime: YYYYMMDDHHMMSSZ */
634 goto unsupported_time;
635 year = DD2bin(p) * 100 + DD2bin(p);
636 if (year >= 1950 && year <= 2049)
639 goto unsupported_time;
649 goto unsupported_time;
655 mon_len = month_lengths[mon - 1];
659 if (year % 100 == 0) {
667 if (day < 1 || day > mon_len ||
668 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
670 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
673 *_t = mktime64(year, mon, day, hour, min, sec);
677 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
678 tag, (int)vlen, value);
681 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
682 tag, (int)vlen, value);
685 EXPORT_SYMBOL_GPL(x509_decode_time);
687 int x509_note_not_before(void *context, size_t hdrlen,
689 const void *value, size_t vlen)
691 struct x509_parse_context *ctx = context;
692 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
695 int x509_note_not_after(void *context, size_t hdrlen,
697 const void *value, size_t vlen)
699 struct x509_parse_context *ctx = context;
700 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
704 * Note a key identifier-based AuthorityKeyIdentifier
706 int x509_akid_note_kid(void *context, size_t hdrlen,
708 const void *value, size_t vlen)
710 struct x509_parse_context *ctx = context;
711 struct asymmetric_key_id *kid;
713 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
715 if (ctx->cert->sig->auth_ids[1])
718 kid = asymmetric_key_generate_id(value, vlen, "", 0);
721 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
722 ctx->cert->sig->auth_ids[1] = kid;
727 * Note a directoryName in an AuthorityKeyIdentifier
729 int x509_akid_note_name(void *context, size_t hdrlen,
731 const void *value, size_t vlen)
733 struct x509_parse_context *ctx = context;
735 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
737 ctx->akid_raw_issuer = value;
738 ctx->akid_raw_issuer_size = vlen;
743 * Note a serial number in an AuthorityKeyIdentifier
745 int x509_akid_note_serial(void *context, size_t hdrlen,
747 const void *value, size_t vlen)
749 struct x509_parse_context *ctx = context;
750 struct asymmetric_key_id *kid;
752 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
754 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
757 kid = asymmetric_key_generate_id(value,
759 ctx->akid_raw_issuer,
760 ctx->akid_raw_issuer_size);
764 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
765 ctx->cert->sig->auth_ids[0] = kid;