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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* X.509 certificate parser
3 *
4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
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"
18
19struct 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;
39};
40
41/*
42 * Free an X.509 certificate
43 */
44void x509_free_certificate(struct x509_certificate *cert)
45{
46 if (cert) {
47 public_key_free(cert->pub);
48 public_key_signature_free(cert->sig);
49 kfree(cert->issuer);
50 kfree(cert->subject);
51 kfree(cert->id);
52 kfree(cert->skid);
53 kfree(cert);
54 }
55}
56EXPORT_SYMBOL_GPL(x509_free_certificate);
57
58/*
59 * Parse an X.509 certificate
60 */
61struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
62{
63 struct x509_certificate *cert;
64 struct x509_parse_context *ctx;
65 struct asymmetric_key_id *kid;
66 long ret;
67
68 ret = -ENOMEM;
69 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
70 if (!cert)
71 goto error_no_cert;
72 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
73 if (!cert->pub)
74 goto error_no_ctx;
75 cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
76 if (!cert->sig)
77 goto error_no_ctx;
78 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
79 if (!ctx)
80 goto error_no_ctx;
81
82 ctx->cert = cert;
83 ctx->data = (unsigned long)data;
84
85 /* Attempt to decode the certificate */
86 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
87 if (ret < 0)
88 goto error_decode;
89
90 /* Decode the AuthorityKeyIdentifier */
91 if (ctx->raw_akid) {
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);
96 if (ret < 0) {
97 pr_warn("Couldn't decode AuthKeyIdentifier\n");
98 goto error_decode;
99 }
100 }
101
102 ret = -ENOMEM;
103 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
104 if (!cert->pub->key)
105 goto error_decode;
106
107 cert->pub->keylen = ctx->key_size;
108
109 cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
110 if (!cert->pub->params)
111 goto error_decode;
112
113 cert->pub->paramlen = ctx->params_size;
114 cert->pub->algo = ctx->key_algo;
115
116 /* Grab the signature bits */
117 ret = x509_get_sig_params(cert);
118 if (ret < 0)
119 goto error_decode;
120
121 /* Generate cert issuer + serial number key ID */
122 kid = asymmetric_key_generate_id(cert->raw_serial,
123 cert->raw_serial_size,
124 cert->raw_issuer,
125 cert->raw_issuer_size);
126 if (IS_ERR(kid)) {
127 ret = PTR_ERR(kid);
128 goto error_decode;
129 }
130 cert->id = kid;
131
132 /* Detect self-signed certificates */
133 ret = x509_check_for_self_signed(cert);
134 if (ret < 0)
135 goto error_decode;
136
137 kfree(ctx);
138 return cert;
139
140error_decode:
141 kfree(ctx);
142error_no_ctx:
143 x509_free_certificate(cert);
144error_no_cert:
145 return ERR_PTR(ret);
146}
147EXPORT_SYMBOL_GPL(x509_cert_parse);
148
149/*
150 * Note an OID when we find one for later processing when we know how
151 * to interpret it.
152 */
153int x509_note_OID(void *context, size_t hdrlen,
154 unsigned char tag,
155 const void *value, size_t vlen)
156{
157 struct x509_parse_context *ctx = context;
158
159 ctx->last_oid = look_up_OID(value, vlen);
160 if (ctx->last_oid == OID__NR) {
161 char buffer[50];
162 sprint_oid(value, vlen, buffer, sizeof(buffer));
163 pr_debug("Unknown OID: [%lu] %s\n",
164 (unsigned long)value - ctx->data, buffer);
165 }
166 return 0;
167}
168
169/*
170 * Save the position of the TBS data so that we can check the signature over it
171 * later.
172 */
173int x509_note_tbs_certificate(void *context, size_t hdrlen,
174 unsigned char tag,
175 const void *value, size_t vlen)
176{
177 struct x509_parse_context *ctx = context;
178
179 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
180 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
181
182 ctx->cert->tbs = value - hdrlen;
183 ctx->cert->tbs_size = vlen + hdrlen;
184 return 0;
185}
186
187/*
188 * Record the algorithm that was used to sign this certificate.
189 */
190int x509_note_sig_algo(void *context, size_t hdrlen, unsigned char tag,
191 const void *value, size_t vlen)
192{
193 struct x509_parse_context *ctx = context;
194
195 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
196
197 switch (ctx->last_oid) {
198 case OID_md2WithRSAEncryption:
199 case OID_md3WithRSAEncryption:
200 default:
201 return -ENOPKG; /* Unsupported combination */
202
203 case OID_md4WithRSAEncryption:
204 ctx->cert->sig->hash_algo = "md4";
205 goto rsa_pkcs1;
206
207 case OID_sha1WithRSAEncryption:
208 ctx->cert->sig->hash_algo = "sha1";
209 goto rsa_pkcs1;
210
211 case OID_sha256WithRSAEncryption:
212 ctx->cert->sig->hash_algo = "sha256";
213 goto rsa_pkcs1;
214
215 case OID_sha384WithRSAEncryption:
216 ctx->cert->sig->hash_algo = "sha384";
217 goto rsa_pkcs1;
218
219 case OID_sha512WithRSAEncryption:
220 ctx->cert->sig->hash_algo = "sha512";
221 goto rsa_pkcs1;
222
223 case OID_sha224WithRSAEncryption:
224 ctx->cert->sig->hash_algo = "sha224";
225 goto rsa_pkcs1;
226
227 case OID_id_ecdsa_with_sha1:
228 ctx->cert->sig->hash_algo = "sha1";
229 goto ecdsa;
230
231 case OID_id_ecdsa_with_sha224:
232 ctx->cert->sig->hash_algo = "sha224";
233 goto ecdsa;
234
235 case OID_id_ecdsa_with_sha256:
236 ctx->cert->sig->hash_algo = "sha256";
237 goto ecdsa;
238
239 case OID_id_ecdsa_with_sha384:
240 ctx->cert->sig->hash_algo = "sha384";
241 goto ecdsa;
242
243 case OID_id_ecdsa_with_sha512:
244 ctx->cert->sig->hash_algo = "sha512";
245 goto ecdsa;
246
247 case OID_gost2012Signature256:
248 ctx->cert->sig->hash_algo = "streebog256";
249 goto ecrdsa;
250
251 case OID_gost2012Signature512:
252 ctx->cert->sig->hash_algo = "streebog512";
253 goto ecrdsa;
254
255 case OID_SM2_with_SM3:
256 ctx->cert->sig->hash_algo = "sm3";
257 goto sm2;
258 }
259
260rsa_pkcs1:
261 ctx->cert->sig->pkey_algo = "rsa";
262 ctx->cert->sig->encoding = "pkcs1";
263 ctx->sig_algo = ctx->last_oid;
264 return 0;
265ecrdsa:
266 ctx->cert->sig->pkey_algo = "ecrdsa";
267 ctx->cert->sig->encoding = "raw";
268 ctx->sig_algo = ctx->last_oid;
269 return 0;
270sm2:
271 ctx->cert->sig->pkey_algo = "sm2";
272 ctx->cert->sig->encoding = "raw";
273 ctx->sig_algo = ctx->last_oid;
274 return 0;
275ecdsa:
276 ctx->cert->sig->pkey_algo = "ecdsa";
277 ctx->cert->sig->encoding = "x962";
278 ctx->sig_algo = ctx->last_oid;
279 return 0;
280}
281
282/*
283 * Note the whereabouts and type of the signature.
284 */
285int x509_note_signature(void *context, size_t hdrlen,
286 unsigned char tag,
287 const void *value, size_t vlen)
288{
289 struct x509_parse_context *ctx = context;
290
291 pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
292
293 /*
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.
297 */
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);
301 return -EINVAL;
302 }
303
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)
310 return -EBADMSG;
311
312 value++;
313 vlen--;
314 }
315
316 ctx->cert->raw_sig = value;
317 ctx->cert->raw_sig_size = vlen;
318 return 0;
319}
320
321/*
322 * Note the certificate serial number
323 */
324int x509_note_serial(void *context, size_t hdrlen,
325 unsigned char tag,
326 const void *value, size_t vlen)
327{
328 struct x509_parse_context *ctx = context;
329 ctx->cert->raw_serial = value;
330 ctx->cert->raw_serial_size = vlen;
331 return 0;
332}
333
334/*
335 * Note some of the name segments from which we'll fabricate a name.
336 */
337int x509_extract_name_segment(void *context, size_t hdrlen,
338 unsigned char tag,
339 const void *value, size_t vlen)
340{
341 struct x509_parse_context *ctx = context;
342
343 switch (ctx->last_oid) {
344 case OID_commonName:
345 ctx->cn_size = vlen;
346 ctx->cn_offset = (unsigned long)value - ctx->data;
347 break;
348 case OID_organizationName:
349 ctx->o_size = vlen;
350 ctx->o_offset = (unsigned long)value - ctx->data;
351 break;
352 case OID_email_address:
353 ctx->email_size = vlen;
354 ctx->email_offset = (unsigned long)value - ctx->data;
355 break;
356 default:
357 break;
358 }
359
360 return 0;
361}
362
363/*
364 * Fabricate and save the issuer and subject names
365 */
366static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
367 unsigned char tag,
368 char **_name, size_t vlen)
369{
370 const void *name, *data = (const void *)ctx->data;
371 size_t namesize;
372 char *buffer;
373
374 if (*_name)
375 return -EINVAL;
376
377 /* Empty name string if no material */
378 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
379 buffer = kmalloc(1, GFP_KERNEL);
380 if (!buffer)
381 return -ENOMEM;
382 buffer[0] = 0;
383 goto done;
384 }
385
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.
389 */
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,
394 ctx->o_size) == 0)
395 goto single_component;
396 if (ctx->cn_size >= 7 &&
397 ctx->o_size >= 7 &&
398 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
399 goto single_component;
400
401 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
402 GFP_KERNEL);
403 if (!buffer)
404 return -ENOMEM;
405
406 memcpy(buffer,
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;
413 goto done;
414
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;
421 } else {
422 namesize = ctx->email_size;
423 name = data + ctx->email_offset;
424 }
425
426single_component:
427 buffer = kmalloc(namesize + 1, GFP_KERNEL);
428 if (!buffer)
429 return -ENOMEM;
430 memcpy(buffer, name, namesize);
431 buffer[namesize] = 0;
432
433done:
434 *_name = buffer;
435 ctx->cn_size = 0;
436 ctx->o_size = 0;
437 ctx->email_size = 0;
438 return 0;
439}
440
441int x509_note_issuer(void *context, size_t hdrlen,
442 unsigned char tag,
443 const void *value, size_t vlen)
444{
445 struct x509_parse_context *ctx = context;
446 struct asymmetric_key_id *kid;
447
448 ctx->cert->raw_issuer = value;
449 ctx->cert->raw_issuer_size = vlen;
450
451 if (!ctx->cert->sig->auth_ids[2]) {
452 kid = asymmetric_key_generate_id(value, vlen, "", 0);
453 if (IS_ERR(kid))
454 return PTR_ERR(kid);
455 ctx->cert->sig->auth_ids[2] = kid;
456 }
457
458 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
459}
460
461int x509_note_subject(void *context, size_t hdrlen,
462 unsigned char tag,
463 const void *value, size_t vlen)
464{
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);
469}
470
471/*
472 * Extract the parameters for the public key
473 */
474int x509_note_params(void *context, size_t hdrlen,
475 unsigned char tag,
476 const void *value, size_t vlen)
477{
478 struct x509_parse_context *ctx = context;
479
480 /*
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.
484 */
485 if (!ctx->cert->raw_subject || ctx->key)
486 return 0;
487 ctx->params = value - hdrlen;
488 ctx->params_size = vlen + hdrlen;
489 return 0;
490}
491
492/*
493 * Extract the data for the public key algorithm
494 */
495int x509_extract_key_data(void *context, size_t hdrlen,
496 unsigned char tag,
497 const void *value, size_t vlen)
498{
499 struct x509_parse_context *ctx = context;
500 enum OID oid;
501
502 ctx->key_algo = ctx->last_oid;
503 switch (ctx->last_oid) {
504 case OID_rsaEncryption:
505 ctx->cert->pub->pkey_algo = "rsa";
506 break;
507 case OID_gost2012PKey256:
508 case OID_gost2012PKey512:
509 ctx->cert->pub->pkey_algo = "ecrdsa";
510 break;
511 case OID_sm2:
512 ctx->cert->pub->pkey_algo = "sm2";
513 break;
514 case OID_id_ecPublicKey:
515 if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
516 return -EBADMSG;
517
518 switch (oid) {
519 case OID_sm2:
520 ctx->cert->pub->pkey_algo = "sm2";
521 break;
522 case OID_id_prime192v1:
523 ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
524 break;
525 case OID_id_prime256v1:
526 ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
527 break;
528 case OID_id_ansip384r1:
529 ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
530 break;
531 default:
532 return -ENOPKG;
533 }
534 break;
535 default:
536 return -ENOPKG;
537 }
538
539 /* Discard the BIT STRING metadata */
540 if (vlen < 1 || *(const u8 *)value != 0)
541 return -EBADMSG;
542 ctx->key = value + 1;
543 ctx->key_size = vlen - 1;
544 return 0;
545}
546
547/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
548#define SEQ_TAG_KEYID (ASN1_CONT << 6)
549
550/*
551 * Process certificate extensions that are used to qualify the certificate.
552 */
553int x509_process_extension(void *context, size_t hdrlen,
554 unsigned char tag,
555 const void *value, size_t vlen)
556{
557 struct x509_parse_context *ctx = context;
558 struct asymmetric_key_id *kid;
559 const unsigned char *v = value;
560
561 pr_debug("Extension: %u\n", ctx->last_oid);
562
563 if (ctx->last_oid == OID_subjectKeyIdentifier) {
564 /* Get hold of the key fingerprint */
565 if (ctx->cert->skid || vlen < 3)
566 return -EBADMSG;
567 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
568 return -EBADMSG;
569 v += 2;
570 vlen -= 2;
571
572 ctx->cert->raw_skid_size = vlen;
573 ctx->cert->raw_skid = v;
574 kid = asymmetric_key_generate_id(v, vlen, "", 0);
575 if (IS_ERR(kid))
576 return PTR_ERR(kid);
577 ctx->cert->skid = kid;
578 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
579 return 0;
580 }
581
582 if (ctx->last_oid == OID_authorityKeyIdentifier) {
583 /* Get hold of the CA key fingerprint */
584 ctx->raw_akid = v;
585 ctx->raw_akid_size = vlen;
586 return 0;
587 }
588
589 return 0;
590}
591
592/**
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
599 *
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:
602 *
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.
609 */
610int x509_decode_time(time64_t *_t, size_t hdrlen,
611 unsigned char tag,
612 const unsigned char *value, size_t vlen)
613{
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;
618
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; })
621
622 if (tag == ASN1_UNITIM) {
623 /* UTCTime: YYMMDDHHMMSSZ */
624 if (vlen != 13)
625 goto unsupported_time;
626 year = DD2bin(p);
627 if (year >= 50)
628 year += 1900;
629 else
630 year += 2000;
631 } else if (tag == ASN1_GENTIM) {
632 /* GenTime: YYYYMMDDHHMMSSZ */
633 if (vlen != 15)
634 goto unsupported_time;
635 year = DD2bin(p) * 100 + DD2bin(p);
636 if (year >= 1950 && year <= 2049)
637 goto invalid_time;
638 } else {
639 goto unsupported_time;
640 }
641
642 mon = DD2bin(p);
643 day = DD2bin(p);
644 hour = DD2bin(p);
645 min = DD2bin(p);
646 sec = DD2bin(p);
647
648 if (*p != 'Z')
649 goto unsupported_time;
650
651 if (year < 1970 ||
652 mon < 1 || mon > 12)
653 goto invalid_time;
654
655 mon_len = month_lengths[mon - 1];
656 if (mon == 2) {
657 if (year % 4 == 0) {
658 mon_len = 29;
659 if (year % 100 == 0) {
660 mon_len = 28;
661 if (year % 400 == 0)
662 mon_len = 29;
663 }
664 }
665 }
666
667 if (day < 1 || day > mon_len ||
668 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
669 min > 59 ||
670 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
671 goto invalid_time;
672
673 *_t = mktime64(year, mon, day, hour, min, sec);
674 return 0;
675
676unsupported_time:
677 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
678 tag, (int)vlen, value);
679 return -EBADMSG;
680invalid_time:
681 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
682 tag, (int)vlen, value);
683 return -EBADMSG;
684}
685EXPORT_SYMBOL_GPL(x509_decode_time);
686
687int x509_note_not_before(void *context, size_t hdrlen,
688 unsigned char tag,
689 const void *value, size_t vlen)
690{
691 struct x509_parse_context *ctx = context;
692 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
693}
694
695int x509_note_not_after(void *context, size_t hdrlen,
696 unsigned char tag,
697 const void *value, size_t vlen)
698{
699 struct x509_parse_context *ctx = context;
700 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
701}
702
703/*
704 * Note a key identifier-based AuthorityKeyIdentifier
705 */
706int x509_akid_note_kid(void *context, size_t hdrlen,
707 unsigned char tag,
708 const void *value, size_t vlen)
709{
710 struct x509_parse_context *ctx = context;
711 struct asymmetric_key_id *kid;
712
713 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
714
715 if (ctx->cert->sig->auth_ids[1])
716 return 0;
717
718 kid = asymmetric_key_generate_id(value, vlen, "", 0);
719 if (IS_ERR(kid))
720 return PTR_ERR(kid);
721 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
722 ctx->cert->sig->auth_ids[1] = kid;
723 return 0;
724}
725
726/*
727 * Note a directoryName in an AuthorityKeyIdentifier
728 */
729int x509_akid_note_name(void *context, size_t hdrlen,
730 unsigned char tag,
731 const void *value, size_t vlen)
732{
733 struct x509_parse_context *ctx = context;
734
735 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
736
737 ctx->akid_raw_issuer = value;
738 ctx->akid_raw_issuer_size = vlen;
739 return 0;
740}
741
742/*
743 * Note a serial number in an AuthorityKeyIdentifier
744 */
745int x509_akid_note_serial(void *context, size_t hdrlen,
746 unsigned char tag,
747 const void *value, size_t vlen)
748{
749 struct x509_parse_context *ctx = context;
750 struct asymmetric_key_id *kid;
751
752 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
753
754 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
755 return 0;
756
757 kid = asymmetric_key_generate_id(value,
758 vlen,
759 ctx->akid_raw_issuer,
760 ctx->akid_raw_issuer_size);
761 if (IS_ERR(kid))
762 return PTR_ERR(kid);
763
764 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
765 ctx->cert->sig->auth_ids[0] = kid;
766 return 0;
767}
1/* X.509 certificate parser
2 *
3 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#define pr_fmt(fmt) "X.509: "fmt
13#include <linux/kernel.h>
14#include <linux/export.h>
15#include <linux/slab.h>
16#include <linux/err.h>
17#include <linux/oid_registry.h>
18#include <crypto/public_key.h>
19#include "x509_parser.h"
20#include "x509-asn1.h"
21#include "x509_akid-asn1.h"
22
23struct x509_parse_context {
24 struct x509_certificate *cert; /* Certificate being constructed */
25 unsigned long data; /* Start of data */
26 const void *cert_start; /* Start of cert content */
27 const void *key; /* Key data */
28 size_t key_size; /* Size of key data */
29 enum OID last_oid; /* Last OID encountered */
30 enum OID algo_oid; /* Algorithm OID */
31 unsigned char nr_mpi; /* Number of MPIs stored */
32 u8 o_size; /* Size of organizationName (O) */
33 u8 cn_size; /* Size of commonName (CN) */
34 u8 email_size; /* Size of emailAddress */
35 u16 o_offset; /* Offset of organizationName (O) */
36 u16 cn_offset; /* Offset of commonName (CN) */
37 u16 email_offset; /* Offset of emailAddress */
38 unsigned raw_akid_size;
39 const void *raw_akid; /* Raw authorityKeyId in ASN.1 */
40 const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */
41 unsigned akid_raw_issuer_size;
42};
43
44/*
45 * Free an X.509 certificate
46 */
47void x509_free_certificate(struct x509_certificate *cert)
48{
49 if (cert) {
50 public_key_destroy(cert->pub);
51 kfree(cert->issuer);
52 kfree(cert->subject);
53 kfree(cert->id);
54 kfree(cert->skid);
55 kfree(cert->akid_id);
56 kfree(cert->akid_skid);
57 kfree(cert->sig.digest);
58 kfree(cert->sig.s);
59 kfree(cert);
60 }
61}
62EXPORT_SYMBOL_GPL(x509_free_certificate);
63
64/*
65 * Parse an X.509 certificate
66 */
67struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
68{
69 struct x509_certificate *cert;
70 struct x509_parse_context *ctx;
71 struct asymmetric_key_id *kid;
72 long ret;
73
74 ret = -ENOMEM;
75 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
76 if (!cert)
77 goto error_no_cert;
78 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
79 if (!cert->pub)
80 goto error_no_ctx;
81 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
82 if (!ctx)
83 goto error_no_ctx;
84
85 ctx->cert = cert;
86 ctx->data = (unsigned long)data;
87
88 /* Attempt to decode the certificate */
89 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
90 if (ret < 0)
91 goto error_decode;
92
93 /* Decode the AuthorityKeyIdentifier */
94 if (ctx->raw_akid) {
95 pr_devel("AKID: %u %*phN\n",
96 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
97 ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
98 ctx->raw_akid, ctx->raw_akid_size);
99 if (ret < 0) {
100 pr_warn("Couldn't decode AuthKeyIdentifier\n");
101 goto error_decode;
102 }
103 }
104
105 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
106 if (!cert->pub->key)
107 goto error_decode;
108
109 cert->pub->keylen = ctx->key_size;
110
111 /* Generate cert issuer + serial number key ID */
112 kid = asymmetric_key_generate_id(cert->raw_serial,
113 cert->raw_serial_size,
114 cert->raw_issuer,
115 cert->raw_issuer_size);
116 if (IS_ERR(kid)) {
117 ret = PTR_ERR(kid);
118 goto error_decode;
119 }
120 cert->id = kid;
121
122 kfree(ctx);
123 return cert;
124
125error_decode:
126 kfree(cert->pub->key);
127 kfree(ctx);
128error_no_ctx:
129 x509_free_certificate(cert);
130error_no_cert:
131 return ERR_PTR(ret);
132}
133EXPORT_SYMBOL_GPL(x509_cert_parse);
134
135/*
136 * Note an OID when we find one for later processing when we know how
137 * to interpret it.
138 */
139int x509_note_OID(void *context, size_t hdrlen,
140 unsigned char tag,
141 const void *value, size_t vlen)
142{
143 struct x509_parse_context *ctx = context;
144
145 ctx->last_oid = look_up_OID(value, vlen);
146 if (ctx->last_oid == OID__NR) {
147 char buffer[50];
148 sprint_oid(value, vlen, buffer, sizeof(buffer));
149 pr_debug("Unknown OID: [%lu] %s\n",
150 (unsigned long)value - ctx->data, buffer);
151 }
152 return 0;
153}
154
155/*
156 * Save the position of the TBS data so that we can check the signature over it
157 * later.
158 */
159int x509_note_tbs_certificate(void *context, size_t hdrlen,
160 unsigned char tag,
161 const void *value, size_t vlen)
162{
163 struct x509_parse_context *ctx = context;
164
165 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
166 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
167
168 ctx->cert->tbs = value - hdrlen;
169 ctx->cert->tbs_size = vlen + hdrlen;
170 return 0;
171}
172
173/*
174 * Record the public key algorithm
175 */
176int x509_note_pkey_algo(void *context, size_t hdrlen,
177 unsigned char tag,
178 const void *value, size_t vlen)
179{
180 struct x509_parse_context *ctx = context;
181
182 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
183
184 switch (ctx->last_oid) {
185 case OID_md2WithRSAEncryption:
186 case OID_md3WithRSAEncryption:
187 default:
188 return -ENOPKG; /* Unsupported combination */
189
190 case OID_md4WithRSAEncryption:
191 ctx->cert->sig.hash_algo = "md4";
192 ctx->cert->sig.pkey_algo = "rsa";
193 break;
194
195 case OID_sha1WithRSAEncryption:
196 ctx->cert->sig.hash_algo = "sha1";
197 ctx->cert->sig.pkey_algo = "rsa";
198 break;
199
200 case OID_sha256WithRSAEncryption:
201 ctx->cert->sig.hash_algo = "sha256";
202 ctx->cert->sig.pkey_algo = "rsa";
203 break;
204
205 case OID_sha384WithRSAEncryption:
206 ctx->cert->sig.hash_algo = "sha384";
207 ctx->cert->sig.pkey_algo = "rsa";
208 break;
209
210 case OID_sha512WithRSAEncryption:
211 ctx->cert->sig.hash_algo = "sha512";
212 ctx->cert->sig.pkey_algo = "rsa";
213 break;
214
215 case OID_sha224WithRSAEncryption:
216 ctx->cert->sig.hash_algo = "sha224";
217 ctx->cert->sig.pkey_algo = "rsa";
218 break;
219 }
220
221 ctx->algo_oid = ctx->last_oid;
222 return 0;
223}
224
225/*
226 * Note the whereabouts and type of the signature.
227 */
228int x509_note_signature(void *context, size_t hdrlen,
229 unsigned char tag,
230 const void *value, size_t vlen)
231{
232 struct x509_parse_context *ctx = context;
233
234 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
235
236 if (ctx->last_oid != ctx->algo_oid) {
237 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
238 ctx->algo_oid, ctx->last_oid);
239 return -EINVAL;
240 }
241
242 ctx->cert->raw_sig = value;
243 ctx->cert->raw_sig_size = vlen;
244 return 0;
245}
246
247/*
248 * Note the certificate serial number
249 */
250int x509_note_serial(void *context, size_t hdrlen,
251 unsigned char tag,
252 const void *value, size_t vlen)
253{
254 struct x509_parse_context *ctx = context;
255 ctx->cert->raw_serial = value;
256 ctx->cert->raw_serial_size = vlen;
257 return 0;
258}
259
260/*
261 * Note some of the name segments from which we'll fabricate a name.
262 */
263int x509_extract_name_segment(void *context, size_t hdrlen,
264 unsigned char tag,
265 const void *value, size_t vlen)
266{
267 struct x509_parse_context *ctx = context;
268
269 switch (ctx->last_oid) {
270 case OID_commonName:
271 ctx->cn_size = vlen;
272 ctx->cn_offset = (unsigned long)value - ctx->data;
273 break;
274 case OID_organizationName:
275 ctx->o_size = vlen;
276 ctx->o_offset = (unsigned long)value - ctx->data;
277 break;
278 case OID_email_address:
279 ctx->email_size = vlen;
280 ctx->email_offset = (unsigned long)value - ctx->data;
281 break;
282 default:
283 break;
284 }
285
286 return 0;
287}
288
289/*
290 * Fabricate and save the issuer and subject names
291 */
292static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
293 unsigned char tag,
294 char **_name, size_t vlen)
295{
296 const void *name, *data = (const void *)ctx->data;
297 size_t namesize;
298 char *buffer;
299
300 if (*_name)
301 return -EINVAL;
302
303 /* Empty name string if no material */
304 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
305 buffer = kmalloc(1, GFP_KERNEL);
306 if (!buffer)
307 return -ENOMEM;
308 buffer[0] = 0;
309 goto done;
310 }
311
312 if (ctx->cn_size && ctx->o_size) {
313 /* Consider combining O and CN, but use only the CN if it is
314 * prefixed by the O, or a significant portion thereof.
315 */
316 namesize = ctx->cn_size;
317 name = data + ctx->cn_offset;
318 if (ctx->cn_size >= ctx->o_size &&
319 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
320 ctx->o_size) == 0)
321 goto single_component;
322 if (ctx->cn_size >= 7 &&
323 ctx->o_size >= 7 &&
324 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
325 goto single_component;
326
327 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
328 GFP_KERNEL);
329 if (!buffer)
330 return -ENOMEM;
331
332 memcpy(buffer,
333 data + ctx->o_offset, ctx->o_size);
334 buffer[ctx->o_size + 0] = ':';
335 buffer[ctx->o_size + 1] = ' ';
336 memcpy(buffer + ctx->o_size + 2,
337 data + ctx->cn_offset, ctx->cn_size);
338 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
339 goto done;
340
341 } else if (ctx->cn_size) {
342 namesize = ctx->cn_size;
343 name = data + ctx->cn_offset;
344 } else if (ctx->o_size) {
345 namesize = ctx->o_size;
346 name = data + ctx->o_offset;
347 } else {
348 namesize = ctx->email_size;
349 name = data + ctx->email_offset;
350 }
351
352single_component:
353 buffer = kmalloc(namesize + 1, GFP_KERNEL);
354 if (!buffer)
355 return -ENOMEM;
356 memcpy(buffer, name, namesize);
357 buffer[namesize] = 0;
358
359done:
360 *_name = buffer;
361 ctx->cn_size = 0;
362 ctx->o_size = 0;
363 ctx->email_size = 0;
364 return 0;
365}
366
367int x509_note_issuer(void *context, size_t hdrlen,
368 unsigned char tag,
369 const void *value, size_t vlen)
370{
371 struct x509_parse_context *ctx = context;
372 ctx->cert->raw_issuer = value;
373 ctx->cert->raw_issuer_size = vlen;
374 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
375}
376
377int x509_note_subject(void *context, size_t hdrlen,
378 unsigned char tag,
379 const void *value, size_t vlen)
380{
381 struct x509_parse_context *ctx = context;
382 ctx->cert->raw_subject = value;
383 ctx->cert->raw_subject_size = vlen;
384 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
385}
386
387/*
388 * Extract the data for the public key algorithm
389 */
390int x509_extract_key_data(void *context, size_t hdrlen,
391 unsigned char tag,
392 const void *value, size_t vlen)
393{
394 struct x509_parse_context *ctx = context;
395
396 if (ctx->last_oid != OID_rsaEncryption)
397 return -ENOPKG;
398
399 ctx->cert->pub->pkey_algo = "rsa";
400
401 /* Discard the BIT STRING metadata */
402 ctx->key = value + 1;
403 ctx->key_size = vlen - 1;
404 return 0;
405}
406
407/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
408#define SEQ_TAG_KEYID (ASN1_CONT << 6)
409
410/*
411 * Process certificate extensions that are used to qualify the certificate.
412 */
413int x509_process_extension(void *context, size_t hdrlen,
414 unsigned char tag,
415 const void *value, size_t vlen)
416{
417 struct x509_parse_context *ctx = context;
418 struct asymmetric_key_id *kid;
419 const unsigned char *v = value;
420
421 pr_debug("Extension: %u\n", ctx->last_oid);
422
423 if (ctx->last_oid == OID_subjectKeyIdentifier) {
424 /* Get hold of the key fingerprint */
425 if (ctx->cert->skid || vlen < 3)
426 return -EBADMSG;
427 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
428 return -EBADMSG;
429 v += 2;
430 vlen -= 2;
431
432 ctx->cert->raw_skid_size = vlen;
433 ctx->cert->raw_skid = v;
434 kid = asymmetric_key_generate_id(v, vlen, "", 0);
435 if (IS_ERR(kid))
436 return PTR_ERR(kid);
437 ctx->cert->skid = kid;
438 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
439 return 0;
440 }
441
442 if (ctx->last_oid == OID_authorityKeyIdentifier) {
443 /* Get hold of the CA key fingerprint */
444 ctx->raw_akid = v;
445 ctx->raw_akid_size = vlen;
446 return 0;
447 }
448
449 return 0;
450}
451
452/**
453 * x509_decode_time - Decode an X.509 time ASN.1 object
454 * @_t: The time to fill in
455 * @hdrlen: The length of the object header
456 * @tag: The object tag
457 * @value: The object value
458 * @vlen: The size of the object value
459 *
460 * Decode an ASN.1 universal time or generalised time field into a struct the
461 * kernel can handle and check it for validity. The time is decoded thus:
462 *
463 * [RFC5280 ยง4.1.2.5]
464 * CAs conforming to this profile MUST always encode certificate validity
465 * dates through the year 2049 as UTCTime; certificate validity dates in
466 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
467 * applications MUST be able to process validity dates that are encoded in
468 * either UTCTime or GeneralizedTime.
469 */
470int x509_decode_time(time64_t *_t, size_t hdrlen,
471 unsigned char tag,
472 const unsigned char *value, size_t vlen)
473{
474 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
475 31, 31, 30, 31, 30, 31 };
476 const unsigned char *p = value;
477 unsigned year, mon, day, hour, min, sec, mon_len;
478
479#define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
480#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
481
482 if (tag == ASN1_UNITIM) {
483 /* UTCTime: YYMMDDHHMMSSZ */
484 if (vlen != 13)
485 goto unsupported_time;
486 year = DD2bin(p);
487 if (year >= 50)
488 year += 1900;
489 else
490 year += 2000;
491 } else if (tag == ASN1_GENTIM) {
492 /* GenTime: YYYYMMDDHHMMSSZ */
493 if (vlen != 15)
494 goto unsupported_time;
495 year = DD2bin(p) * 100 + DD2bin(p);
496 if (year >= 1950 && year <= 2049)
497 goto invalid_time;
498 } else {
499 goto unsupported_time;
500 }
501
502 mon = DD2bin(p);
503 day = DD2bin(p);
504 hour = DD2bin(p);
505 min = DD2bin(p);
506 sec = DD2bin(p);
507
508 if (*p != 'Z')
509 goto unsupported_time;
510
511 if (year < 1970 ||
512 mon < 1 || mon > 12)
513 goto invalid_time;
514
515 mon_len = month_lengths[mon - 1];
516 if (mon == 2) {
517 if (year % 4 == 0) {
518 mon_len = 29;
519 if (year % 100 == 0) {
520 mon_len = 28;
521 if (year % 400 == 0)
522 mon_len = 29;
523 }
524 }
525 }
526
527 if (day < 1 || day > mon_len ||
528 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
529 min > 59 ||
530 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
531 goto invalid_time;
532
533 *_t = mktime64(year, mon, day, hour, min, sec);
534 return 0;
535
536unsupported_time:
537 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
538 tag, (int)vlen, value);
539 return -EBADMSG;
540invalid_time:
541 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
542 tag, (int)vlen, value);
543 return -EBADMSG;
544}
545EXPORT_SYMBOL_GPL(x509_decode_time);
546
547int x509_note_not_before(void *context, size_t hdrlen,
548 unsigned char tag,
549 const void *value, size_t vlen)
550{
551 struct x509_parse_context *ctx = context;
552 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
553}
554
555int x509_note_not_after(void *context, size_t hdrlen,
556 unsigned char tag,
557 const void *value, size_t vlen)
558{
559 struct x509_parse_context *ctx = context;
560 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
561}
562
563/*
564 * Note a key identifier-based AuthorityKeyIdentifier
565 */
566int x509_akid_note_kid(void *context, size_t hdrlen,
567 unsigned char tag,
568 const void *value, size_t vlen)
569{
570 struct x509_parse_context *ctx = context;
571 struct asymmetric_key_id *kid;
572
573 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
574
575 if (ctx->cert->akid_skid)
576 return 0;
577
578 kid = asymmetric_key_generate_id(value, vlen, "", 0);
579 if (IS_ERR(kid))
580 return PTR_ERR(kid);
581 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
582 ctx->cert->akid_skid = kid;
583 return 0;
584}
585
586/*
587 * Note a directoryName in an AuthorityKeyIdentifier
588 */
589int x509_akid_note_name(void *context, size_t hdrlen,
590 unsigned char tag,
591 const void *value, size_t vlen)
592{
593 struct x509_parse_context *ctx = context;
594
595 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
596
597 ctx->akid_raw_issuer = value;
598 ctx->akid_raw_issuer_size = vlen;
599 return 0;
600}
601
602/*
603 * Note a serial number in an AuthorityKeyIdentifier
604 */
605int x509_akid_note_serial(void *context, size_t hdrlen,
606 unsigned char tag,
607 const void *value, size_t vlen)
608{
609 struct x509_parse_context *ctx = context;
610 struct asymmetric_key_id *kid;
611
612 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
613
614 if (!ctx->akid_raw_issuer || ctx->cert->akid_id)
615 return 0;
616
617 kid = asymmetric_key_generate_id(value,
618 vlen,
619 ctx->akid_raw_issuer,
620 ctx->akid_raw_issuer_size);
621 if (IS_ERR(kid))
622 return PTR_ERR(kid);
623
624 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
625 ctx->cert->akid_id = kid;
626 return 0;
627}