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_gost2012Signature256:
231 ctx->cert->sig->hash_algo = "streebog256";
234 case OID_gost2012Signature512:
235 ctx->cert->sig->hash_algo = "streebog512";
238 case OID_SM2_with_SM3:
239 ctx->cert->sig->hash_algo = "sm3";
244 ctx->cert->sig->pkey_algo = "rsa";
245 ctx->cert->sig->encoding = "pkcs1";
246 ctx->algo_oid = ctx->last_oid;
249 ctx->cert->sig->pkey_algo = "ecrdsa";
250 ctx->cert->sig->encoding = "raw";
251 ctx->algo_oid = ctx->last_oid;
254 ctx->cert->sig->pkey_algo = "sm2";
255 ctx->cert->sig->encoding = "raw";
256 ctx->algo_oid = ctx->last_oid;
261 * Note the whereabouts and type of the signature.
263 int x509_note_signature(void *context, size_t hdrlen,
265 const void *value, size_t vlen)
267 struct x509_parse_context *ctx = context;
269 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
271 if (ctx->last_oid != ctx->algo_oid) {
272 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
273 ctx->algo_oid, ctx->last_oid);
277 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
278 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
279 strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0) {
280 /* Discard the BIT STRING metadata */
281 if (vlen < 1 || *(const u8 *)value != 0)
288 ctx->cert->raw_sig = value;
289 ctx->cert->raw_sig_size = vlen;
294 * Note the certificate serial number
296 int x509_note_serial(void *context, size_t hdrlen,
298 const void *value, size_t vlen)
300 struct x509_parse_context *ctx = context;
301 ctx->cert->raw_serial = value;
302 ctx->cert->raw_serial_size = vlen;
307 * Note some of the name segments from which we'll fabricate a name.
309 int x509_extract_name_segment(void *context, size_t hdrlen,
311 const void *value, size_t vlen)
313 struct x509_parse_context *ctx = context;
315 switch (ctx->last_oid) {
318 ctx->cn_offset = (unsigned long)value - ctx->data;
320 case OID_organizationName:
322 ctx->o_offset = (unsigned long)value - ctx->data;
324 case OID_email_address:
325 ctx->email_size = vlen;
326 ctx->email_offset = (unsigned long)value - ctx->data;
336 * Fabricate and save the issuer and subject names
338 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
340 char **_name, size_t vlen)
342 const void *name, *data = (const void *)ctx->data;
349 /* Empty name string if no material */
350 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
351 buffer = kmalloc(1, GFP_KERNEL);
358 if (ctx->cn_size && ctx->o_size) {
359 /* Consider combining O and CN, but use only the CN if it is
360 * prefixed by the O, or a significant portion thereof.
362 namesize = ctx->cn_size;
363 name = data + ctx->cn_offset;
364 if (ctx->cn_size >= ctx->o_size &&
365 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
367 goto single_component;
368 if (ctx->cn_size >= 7 &&
370 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
371 goto single_component;
373 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
379 data + ctx->o_offset, ctx->o_size);
380 buffer[ctx->o_size + 0] = ':';
381 buffer[ctx->o_size + 1] = ' ';
382 memcpy(buffer + ctx->o_size + 2,
383 data + ctx->cn_offset, ctx->cn_size);
384 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
387 } else if (ctx->cn_size) {
388 namesize = ctx->cn_size;
389 name = data + ctx->cn_offset;
390 } else if (ctx->o_size) {
391 namesize = ctx->o_size;
392 name = data + ctx->o_offset;
394 namesize = ctx->email_size;
395 name = data + ctx->email_offset;
399 buffer = kmalloc(namesize + 1, GFP_KERNEL);
402 memcpy(buffer, name, namesize);
403 buffer[namesize] = 0;
413 int x509_note_issuer(void *context, size_t hdrlen,
415 const void *value, size_t vlen)
417 struct x509_parse_context *ctx = context;
418 ctx->cert->raw_issuer = value;
419 ctx->cert->raw_issuer_size = vlen;
420 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
423 int x509_note_subject(void *context, size_t hdrlen,
425 const void *value, size_t vlen)
427 struct x509_parse_context *ctx = context;
428 ctx->cert->raw_subject = value;
429 ctx->cert->raw_subject_size = vlen;
430 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
434 * Extract the parameters for the public key
436 int x509_note_params(void *context, size_t hdrlen,
438 const void *value, size_t vlen)
440 struct x509_parse_context *ctx = context;
443 * AlgorithmIdentifier is used three times in the x509, we should skip
444 * first and ignore third, using second one which is after subject and
445 * before subjectPublicKey.
447 if (!ctx->cert->raw_subject || ctx->key)
449 ctx->params = value - hdrlen;
450 ctx->params_size = vlen + hdrlen;
455 * Extract the data for the public key algorithm
457 int x509_extract_key_data(void *context, size_t hdrlen,
459 const void *value, size_t vlen)
461 struct x509_parse_context *ctx = context;
463 ctx->key_algo = ctx->last_oid;
464 switch (ctx->last_oid) {
465 case OID_rsaEncryption:
466 ctx->cert->pub->pkey_algo = "rsa";
468 case OID_gost2012PKey256:
469 case OID_gost2012PKey512:
470 ctx->cert->pub->pkey_algo = "ecrdsa";
472 case OID_id_ecPublicKey:
473 ctx->cert->pub->pkey_algo = "sm2";
479 /* Discard the BIT STRING metadata */
480 if (vlen < 1 || *(const u8 *)value != 0)
482 ctx->key = value + 1;
483 ctx->key_size = vlen - 1;
487 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
488 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
491 * Process certificate extensions that are used to qualify the certificate.
493 int x509_process_extension(void *context, size_t hdrlen,
495 const void *value, size_t vlen)
497 struct x509_parse_context *ctx = context;
498 struct asymmetric_key_id *kid;
499 const unsigned char *v = value;
501 pr_debug("Extension: %u\n", ctx->last_oid);
503 if (ctx->last_oid == OID_subjectKeyIdentifier) {
504 /* Get hold of the key fingerprint */
505 if (ctx->cert->skid || vlen < 3)
507 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
512 ctx->cert->raw_skid_size = vlen;
513 ctx->cert->raw_skid = v;
514 kid = asymmetric_key_generate_id(v, vlen, "", 0);
517 ctx->cert->skid = kid;
518 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
522 if (ctx->last_oid == OID_authorityKeyIdentifier) {
523 /* Get hold of the CA key fingerprint */
525 ctx->raw_akid_size = vlen;
533 * x509_decode_time - Decode an X.509 time ASN.1 object
534 * @_t: The time to fill in
535 * @hdrlen: The length of the object header
536 * @tag: The object tag
537 * @value: The object value
538 * @vlen: The size of the object value
540 * Decode an ASN.1 universal time or generalised time field into a struct the
541 * kernel can handle and check it for validity. The time is decoded thus:
543 * [RFC5280 ยง4.1.2.5]
544 * CAs conforming to this profile MUST always encode certificate validity
545 * dates through the year 2049 as UTCTime; certificate validity dates in
546 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
547 * applications MUST be able to process validity dates that are encoded in
548 * either UTCTime or GeneralizedTime.
550 int x509_decode_time(time64_t *_t, size_t hdrlen,
552 const unsigned char *value, size_t vlen)
554 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
555 31, 31, 30, 31, 30, 31 };
556 const unsigned char *p = value;
557 unsigned year, mon, day, hour, min, sec, mon_len;
559 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
560 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
562 if (tag == ASN1_UNITIM) {
563 /* UTCTime: YYMMDDHHMMSSZ */
565 goto unsupported_time;
571 } else if (tag == ASN1_GENTIM) {
572 /* GenTime: YYYYMMDDHHMMSSZ */
574 goto unsupported_time;
575 year = DD2bin(p) * 100 + DD2bin(p);
576 if (year >= 1950 && year <= 2049)
579 goto unsupported_time;
589 goto unsupported_time;
595 mon_len = month_lengths[mon - 1];
599 if (year % 100 == 0) {
607 if (day < 1 || day > mon_len ||
608 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
610 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
613 *_t = mktime64(year, mon, day, hour, min, sec);
617 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
618 tag, (int)vlen, value);
621 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
622 tag, (int)vlen, value);
625 EXPORT_SYMBOL_GPL(x509_decode_time);
627 int x509_note_not_before(void *context, size_t hdrlen,
629 const void *value, size_t vlen)
631 struct x509_parse_context *ctx = context;
632 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
635 int x509_note_not_after(void *context, size_t hdrlen,
637 const void *value, size_t vlen)
639 struct x509_parse_context *ctx = context;
640 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
644 * Note a key identifier-based AuthorityKeyIdentifier
646 int x509_akid_note_kid(void *context, size_t hdrlen,
648 const void *value, size_t vlen)
650 struct x509_parse_context *ctx = context;
651 struct asymmetric_key_id *kid;
653 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
655 if (ctx->cert->sig->auth_ids[1])
658 kid = asymmetric_key_generate_id(value, vlen, "", 0);
661 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
662 ctx->cert->sig->auth_ids[1] = kid;
667 * Note a directoryName in an AuthorityKeyIdentifier
669 int x509_akid_note_name(void *context, size_t hdrlen,
671 const void *value, size_t vlen)
673 struct x509_parse_context *ctx = context;
675 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
677 ctx->akid_raw_issuer = value;
678 ctx->akid_raw_issuer_size = vlen;
683 * Note a serial number in an AuthorityKeyIdentifier
685 int x509_akid_note_serial(void *context, size_t hdrlen,
687 const void *value, size_t vlen)
689 struct x509_parse_context *ctx = context;
690 struct asymmetric_key_id *kid;
692 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
694 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
697 kid = asymmetric_key_generate_id(value,
699 ctx->akid_raw_issuer,
700 ctx->akid_raw_issuer_size);
704 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
705 ctx->cert->sig->auth_ids[0] = kid;