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 *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;
44 * Free an X.509 certificate
46 void x509_free_certificate(struct x509_certificate *cert)
49 public_key_free(cert->pub);
50 public_key_signature_free(cert->sig);
58 EXPORT_SYMBOL_GPL(x509_free_certificate);
61 * Parse an X.509 certificate
63 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
65 struct x509_certificate *cert;
66 struct x509_parse_context *ctx;
67 struct asymmetric_key_id *kid;
71 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
74 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
77 cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
80 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
85 ctx->data = (unsigned long)data;
87 /* Attempt to decode the certificate */
88 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
92 /* Decode the AuthorityKeyIdentifier */
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);
99 pr_warn("Couldn't decode AuthKeyIdentifier\n");
105 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
109 cert->pub->keylen = ctx->key_size;
111 cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
112 if (!cert->pub->params)
115 cert->pub->paramlen = ctx->params_size;
116 cert->pub->algo = ctx->key_algo;
118 /* Grab the signature bits */
119 ret = x509_get_sig_params(cert);
123 /* Generate cert issuer + serial number key ID */
124 kid = asymmetric_key_generate_id(cert->raw_serial,
125 cert->raw_serial_size,
127 cert->raw_issuer_size);
134 /* Detect self-signed certificates */
135 ret = x509_check_for_self_signed(cert);
145 x509_free_certificate(cert);
149 EXPORT_SYMBOL_GPL(x509_cert_parse);
152 * Note an OID when we find one for later processing when we know how
155 int x509_note_OID(void *context, size_t hdrlen,
157 const void *value, size_t vlen)
159 struct x509_parse_context *ctx = context;
161 ctx->last_oid = look_up_OID(value, vlen);
162 if (ctx->last_oid == OID__NR) {
164 sprint_oid(value, vlen, buffer, sizeof(buffer));
165 pr_debug("Unknown OID: [%lu] %s\n",
166 (unsigned long)value - ctx->data, buffer);
172 * Save the position of the TBS data so that we can check the signature over it
175 int x509_note_tbs_certificate(void *context, size_t hdrlen,
177 const void *value, size_t vlen)
179 struct x509_parse_context *ctx = context;
181 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
182 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
184 ctx->cert->tbs = value - hdrlen;
185 ctx->cert->tbs_size = vlen + hdrlen;
190 * Record the public key algorithm
192 int x509_note_pkey_algo(void *context, size_t hdrlen,
194 const void *value, size_t vlen)
196 struct x509_parse_context *ctx = context;
198 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
200 switch (ctx->last_oid) {
201 case OID_md2WithRSAEncryption:
202 case OID_md3WithRSAEncryption:
204 return -ENOPKG; /* Unsupported combination */
206 case OID_md4WithRSAEncryption:
207 ctx->cert->sig->hash_algo = "md4";
210 case OID_sha1WithRSAEncryption:
211 ctx->cert->sig->hash_algo = "sha1";
214 case OID_sha256WithRSAEncryption:
215 ctx->cert->sig->hash_algo = "sha256";
218 case OID_sha384WithRSAEncryption:
219 ctx->cert->sig->hash_algo = "sha384";
222 case OID_sha512WithRSAEncryption:
223 ctx->cert->sig->hash_algo = "sha512";
226 case OID_sha224WithRSAEncryption:
227 ctx->cert->sig->hash_algo = "sha224";
230 case OID_id_ecdsa_with_sha1:
231 ctx->cert->sig->hash_algo = "sha1";
234 case OID_id_ecdsa_with_sha224:
235 ctx->cert->sig->hash_algo = "sha224";
238 case OID_id_ecdsa_with_sha256:
239 ctx->cert->sig->hash_algo = "sha256";
242 case OID_id_ecdsa_with_sha384:
243 ctx->cert->sig->hash_algo = "sha384";
246 case OID_id_ecdsa_with_sha512:
247 ctx->cert->sig->hash_algo = "sha512";
250 case OID_gost2012Signature256:
251 ctx->cert->sig->hash_algo = "streebog256";
254 case OID_gost2012Signature512:
255 ctx->cert->sig->hash_algo = "streebog512";
258 case OID_SM2_with_SM3:
259 ctx->cert->sig->hash_algo = "sm3";
264 ctx->cert->sig->pkey_algo = "rsa";
265 ctx->cert->sig->encoding = "pkcs1";
266 ctx->algo_oid = ctx->last_oid;
269 ctx->cert->sig->pkey_algo = "ecrdsa";
270 ctx->cert->sig->encoding = "raw";
271 ctx->algo_oid = ctx->last_oid;
274 ctx->cert->sig->pkey_algo = "sm2";
275 ctx->cert->sig->encoding = "raw";
276 ctx->algo_oid = ctx->last_oid;
279 ctx->cert->sig->pkey_algo = "ecdsa";
280 ctx->cert->sig->encoding = "x962";
281 ctx->algo_oid = ctx->last_oid;
286 * Note the whereabouts and type of the signature.
288 int x509_note_signature(void *context, size_t hdrlen,
290 const void *value, size_t vlen)
292 struct x509_parse_context *ctx = context;
294 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
296 if (ctx->last_oid != ctx->algo_oid) {
297 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
298 ctx->algo_oid, ctx->last_oid);
302 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
303 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
304 strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
305 strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
306 /* Discard the BIT STRING metadata */
307 if (vlen < 1 || *(const u8 *)value != 0)
314 ctx->cert->raw_sig = value;
315 ctx->cert->raw_sig_size = vlen;
320 * Note the certificate serial number
322 int x509_note_serial(void *context, size_t hdrlen,
324 const void *value, size_t vlen)
326 struct x509_parse_context *ctx = context;
327 ctx->cert->raw_serial = value;
328 ctx->cert->raw_serial_size = vlen;
333 * Note some of the name segments from which we'll fabricate a name.
335 int x509_extract_name_segment(void *context, size_t hdrlen,
337 const void *value, size_t vlen)
339 struct x509_parse_context *ctx = context;
341 switch (ctx->last_oid) {
344 ctx->cn_offset = (unsigned long)value - ctx->data;
346 case OID_organizationName:
348 ctx->o_offset = (unsigned long)value - ctx->data;
350 case OID_email_address:
351 ctx->email_size = vlen;
352 ctx->email_offset = (unsigned long)value - ctx->data;
362 * Fabricate and save the issuer and subject names
364 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
366 char **_name, size_t vlen)
368 const void *name, *data = (const void *)ctx->data;
375 /* Empty name string if no material */
376 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
377 buffer = kmalloc(1, GFP_KERNEL);
384 if (ctx->cn_size && ctx->o_size) {
385 /* Consider combining O and CN, but use only the CN if it is
386 * prefixed by the O, or a significant portion thereof.
388 namesize = ctx->cn_size;
389 name = data + ctx->cn_offset;
390 if (ctx->cn_size >= ctx->o_size &&
391 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
393 goto single_component;
394 if (ctx->cn_size >= 7 &&
396 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
397 goto single_component;
399 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
405 data + ctx->o_offset, ctx->o_size);
406 buffer[ctx->o_size + 0] = ':';
407 buffer[ctx->o_size + 1] = ' ';
408 memcpy(buffer + ctx->o_size + 2,
409 data + ctx->cn_offset, ctx->cn_size);
410 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
413 } else if (ctx->cn_size) {
414 namesize = ctx->cn_size;
415 name = data + ctx->cn_offset;
416 } else if (ctx->o_size) {
417 namesize = ctx->o_size;
418 name = data + ctx->o_offset;
420 namesize = ctx->email_size;
421 name = data + ctx->email_offset;
425 buffer = kmalloc(namesize + 1, GFP_KERNEL);
428 memcpy(buffer, name, namesize);
429 buffer[namesize] = 0;
439 int x509_note_issuer(void *context, size_t hdrlen,
441 const void *value, size_t vlen)
443 struct x509_parse_context *ctx = context;
444 struct asymmetric_key_id *kid;
446 ctx->cert->raw_issuer = value;
447 ctx->cert->raw_issuer_size = vlen;
449 if (!ctx->cert->sig->auth_ids[2]) {
450 kid = asymmetric_key_generate_id(value, vlen, "", 0);
453 ctx->cert->sig->auth_ids[2] = kid;
456 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
459 int x509_note_subject(void *context, size_t hdrlen,
461 const void *value, size_t vlen)
463 struct x509_parse_context *ctx = context;
464 ctx->cert->raw_subject = value;
465 ctx->cert->raw_subject_size = vlen;
466 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
470 * Extract the parameters for the public key
472 int x509_note_params(void *context, size_t hdrlen,
474 const void *value, size_t vlen)
476 struct x509_parse_context *ctx = context;
479 * AlgorithmIdentifier is used three times in the x509, we should skip
480 * first and ignore third, using second one which is after subject and
481 * before subjectPublicKey.
483 if (!ctx->cert->raw_subject || ctx->key)
485 ctx->params = value - hdrlen;
486 ctx->params_size = vlen + hdrlen;
491 * Extract the data for the public key algorithm
493 int x509_extract_key_data(void *context, size_t hdrlen,
495 const void *value, size_t vlen)
497 struct x509_parse_context *ctx = context;
500 ctx->key_algo = ctx->last_oid;
501 switch (ctx->last_oid) {
502 case OID_rsaEncryption:
503 ctx->cert->pub->pkey_algo = "rsa";
505 case OID_gost2012PKey256:
506 case OID_gost2012PKey512:
507 ctx->cert->pub->pkey_algo = "ecrdsa";
509 case OID_id_ecPublicKey:
510 if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
515 ctx->cert->pub->pkey_algo = "sm2";
517 case OID_id_prime192v1:
518 ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
520 case OID_id_prime256v1:
521 ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
523 case OID_id_ansip384r1:
524 ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
534 /* Discard the BIT STRING metadata */
535 if (vlen < 1 || *(const u8 *)value != 0)
537 ctx->key = value + 1;
538 ctx->key_size = vlen - 1;
542 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
543 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
546 * Process certificate extensions that are used to qualify the certificate.
548 int x509_process_extension(void *context, size_t hdrlen,
550 const void *value, size_t vlen)
552 struct x509_parse_context *ctx = context;
553 struct asymmetric_key_id *kid;
554 const unsigned char *v = value;
556 pr_debug("Extension: %u\n", ctx->last_oid);
558 if (ctx->last_oid == OID_subjectKeyIdentifier) {
559 /* Get hold of the key fingerprint */
560 if (ctx->cert->skid || vlen < 3)
562 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
567 ctx->cert->raw_skid_size = vlen;
568 ctx->cert->raw_skid = v;
569 kid = asymmetric_key_generate_id(v, vlen, "", 0);
572 ctx->cert->skid = kid;
573 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
577 if (ctx->last_oid == OID_authorityKeyIdentifier) {
578 /* Get hold of the CA key fingerprint */
580 ctx->raw_akid_size = vlen;
588 * x509_decode_time - Decode an X.509 time ASN.1 object
589 * @_t: The time to fill in
590 * @hdrlen: The length of the object header
591 * @tag: The object tag
592 * @value: The object value
593 * @vlen: The size of the object value
595 * Decode an ASN.1 universal time or generalised time field into a struct the
596 * kernel can handle and check it for validity. The time is decoded thus:
598 * [RFC5280 ยง4.1.2.5]
599 * CAs conforming to this profile MUST always encode certificate validity
600 * dates through the year 2049 as UTCTime; certificate validity dates in
601 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
602 * applications MUST be able to process validity dates that are encoded in
603 * either UTCTime or GeneralizedTime.
605 int x509_decode_time(time64_t *_t, size_t hdrlen,
607 const unsigned char *value, size_t vlen)
609 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
610 31, 31, 30, 31, 30, 31 };
611 const unsigned char *p = value;
612 unsigned year, mon, day, hour, min, sec, mon_len;
614 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
615 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
617 if (tag == ASN1_UNITIM) {
618 /* UTCTime: YYMMDDHHMMSSZ */
620 goto unsupported_time;
626 } else if (tag == ASN1_GENTIM) {
627 /* GenTime: YYYYMMDDHHMMSSZ */
629 goto unsupported_time;
630 year = DD2bin(p) * 100 + DD2bin(p);
631 if (year >= 1950 && year <= 2049)
634 goto unsupported_time;
644 goto unsupported_time;
650 mon_len = month_lengths[mon - 1];
654 if (year % 100 == 0) {
662 if (day < 1 || day > mon_len ||
663 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
665 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
668 *_t = mktime64(year, mon, day, hour, min, sec);
672 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
673 tag, (int)vlen, value);
676 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
677 tag, (int)vlen, value);
680 EXPORT_SYMBOL_GPL(x509_decode_time);
682 int x509_note_not_before(void *context, size_t hdrlen,
684 const void *value, size_t vlen)
686 struct x509_parse_context *ctx = context;
687 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
690 int x509_note_not_after(void *context, size_t hdrlen,
692 const void *value, size_t vlen)
694 struct x509_parse_context *ctx = context;
695 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
699 * Note a key identifier-based AuthorityKeyIdentifier
701 int x509_akid_note_kid(void *context, size_t hdrlen,
703 const void *value, size_t vlen)
705 struct x509_parse_context *ctx = context;
706 struct asymmetric_key_id *kid;
708 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
710 if (ctx->cert->sig->auth_ids[1])
713 kid = asymmetric_key_generate_id(value, vlen, "", 0);
716 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
717 ctx->cert->sig->auth_ids[1] = kid;
722 * Note a directoryName in an AuthorityKeyIdentifier
724 int x509_akid_note_name(void *context, size_t hdrlen,
726 const void *value, size_t vlen)
728 struct x509_parse_context *ctx = context;
730 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
732 ctx->akid_raw_issuer = value;
733 ctx->akid_raw_issuer_size = vlen;
738 * Note a serial number in an AuthorityKeyIdentifier
740 int x509_akid_note_serial(void *context, size_t hdrlen,
742 const void *value, size_t vlen)
744 struct x509_parse_context *ctx = context;
745 struct asymmetric_key_id *kid;
747 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
749 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
752 kid = asymmetric_key_generate_id(value,
754 ctx->akid_raw_issuer,
755 ctx->akid_raw_issuer_size);
759 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
760 ctx->cert->sig->auth_ids[0] = kid;