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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 §4.1.2.5]
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/slab.h>
15#include <linux/err.h>
16#include <linux/oid_registry.h>
17#include "public_key.h"
18#include "x509_parser.h"
19#include "x509-asn1.h"
20#include "x509_rsakey-asn1.h"
21
22struct x509_parse_context {
23 struct x509_certificate *cert; /* Certificate being constructed */
24 unsigned long data; /* Start of data */
25 const void *cert_start; /* Start of cert content */
26 const void *key; /* Key data */
27 size_t key_size; /* Size of key data */
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};
38
39/*
40 * Free an X.509 certificate
41 */
42void x509_free_certificate(struct x509_certificate *cert)
43{
44 if (cert) {
45 public_key_destroy(cert->pub);
46 kfree(cert->issuer);
47 kfree(cert->subject);
48 kfree(cert->fingerprint);
49 kfree(cert->authority);
50 kfree(cert->sig.digest);
51 mpi_free(cert->sig.rsa.s);
52 kfree(cert);
53 }
54}
55
56/*
57 * Parse an X.509 certificate
58 */
59struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
60{
61 struct x509_certificate *cert;
62 struct x509_parse_context *ctx;
63 long ret;
64
65 ret = -ENOMEM;
66 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
67 if (!cert)
68 goto error_no_cert;
69 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
70 if (!cert->pub)
71 goto error_no_ctx;
72 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
73 if (!ctx)
74 goto error_no_ctx;
75
76 ctx->cert = cert;
77 ctx->data = (unsigned long)data;
78
79 /* Attempt to decode the certificate */
80 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
81 if (ret < 0)
82 goto error_decode;
83
84 /* Decode the public key */
85 ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
86 ctx->key, ctx->key_size);
87 if (ret < 0)
88 goto error_decode;
89
90 kfree(ctx);
91 return cert;
92
93error_decode:
94 kfree(ctx);
95error_no_ctx:
96 x509_free_certificate(cert);
97error_no_cert:
98 return ERR_PTR(ret);
99}
100
101/*
102 * Note an OID when we find one for later processing when we know how
103 * to interpret it.
104 */
105int x509_note_OID(void *context, size_t hdrlen,
106 unsigned char tag,
107 const void *value, size_t vlen)
108{
109 struct x509_parse_context *ctx = context;
110
111 ctx->last_oid = look_up_OID(value, vlen);
112 if (ctx->last_oid == OID__NR) {
113 char buffer[50];
114 sprint_oid(value, vlen, buffer, sizeof(buffer));
115 pr_debug("Unknown OID: [%lu] %s\n",
116 (unsigned long)value - ctx->data, buffer);
117 }
118 return 0;
119}
120
121/*
122 * Save the position of the TBS data so that we can check the signature over it
123 * later.
124 */
125int x509_note_tbs_certificate(void *context, size_t hdrlen,
126 unsigned char tag,
127 const void *value, size_t vlen)
128{
129 struct x509_parse_context *ctx = context;
130
131 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
132 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
133
134 ctx->cert->tbs = value - hdrlen;
135 ctx->cert->tbs_size = vlen + hdrlen;
136 return 0;
137}
138
139/*
140 * Record the public key algorithm
141 */
142int x509_note_pkey_algo(void *context, size_t hdrlen,
143 unsigned char tag,
144 const void *value, size_t vlen)
145{
146 struct x509_parse_context *ctx = context;
147
148 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
149
150 switch (ctx->last_oid) {
151 case OID_md2WithRSAEncryption:
152 case OID_md3WithRSAEncryption:
153 default:
154 return -ENOPKG; /* Unsupported combination */
155
156 case OID_md4WithRSAEncryption:
157 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_MD5;
158 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
159 break;
160
161 case OID_sha1WithRSAEncryption:
162 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA1;
163 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
164 break;
165
166 case OID_sha256WithRSAEncryption:
167 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA256;
168 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
169 break;
170
171 case OID_sha384WithRSAEncryption:
172 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA384;
173 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
174 break;
175
176 case OID_sha512WithRSAEncryption:
177 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA512;
178 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
179 break;
180
181 case OID_sha224WithRSAEncryption:
182 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA224;
183 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
184 break;
185 }
186
187 ctx->algo_oid = ctx->last_oid;
188 return 0;
189}
190
191/*
192 * Note the whereabouts and type of the signature.
193 */
194int x509_note_signature(void *context, size_t hdrlen,
195 unsigned char tag,
196 const void *value, size_t vlen)
197{
198 struct x509_parse_context *ctx = context;
199
200 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
201
202 if (ctx->last_oid != ctx->algo_oid) {
203 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
204 ctx->algo_oid, ctx->last_oid);
205 return -EINVAL;
206 }
207
208 ctx->cert->raw_sig = value;
209 ctx->cert->raw_sig_size = vlen;
210 return 0;
211}
212
213/*
214 * Note some of the name segments from which we'll fabricate a name.
215 */
216int x509_extract_name_segment(void *context, size_t hdrlen,
217 unsigned char tag,
218 const void *value, size_t vlen)
219{
220 struct x509_parse_context *ctx = context;
221
222 switch (ctx->last_oid) {
223 case OID_commonName:
224 ctx->cn_size = vlen;
225 ctx->cn_offset = (unsigned long)value - ctx->data;
226 break;
227 case OID_organizationName:
228 ctx->o_size = vlen;
229 ctx->o_offset = (unsigned long)value - ctx->data;
230 break;
231 case OID_email_address:
232 ctx->email_size = vlen;
233 ctx->email_offset = (unsigned long)value - ctx->data;
234 break;
235 default:
236 break;
237 }
238
239 return 0;
240}
241
242/*
243 * Fabricate and save the issuer and subject names
244 */
245static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
246 unsigned char tag,
247 char **_name, size_t vlen)
248{
249 const void *name, *data = (const void *)ctx->data;
250 size_t namesize;
251 char *buffer;
252
253 if (*_name)
254 return -EINVAL;
255
256 /* Empty name string if no material */
257 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
258 buffer = kmalloc(1, GFP_KERNEL);
259 if (!buffer)
260 return -ENOMEM;
261 buffer[0] = 0;
262 goto done;
263 }
264
265 if (ctx->cn_size && ctx->o_size) {
266 /* Consider combining O and CN, but use only the CN if it is
267 * prefixed by the O, or a significant portion thereof.
268 */
269 namesize = ctx->cn_size;
270 name = data + ctx->cn_offset;
271 if (ctx->cn_size >= ctx->o_size &&
272 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
273 ctx->o_size) == 0)
274 goto single_component;
275 if (ctx->cn_size >= 7 &&
276 ctx->o_size >= 7 &&
277 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
278 goto single_component;
279
280 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
281 GFP_KERNEL);
282 if (!buffer)
283 return -ENOMEM;
284
285 memcpy(buffer,
286 data + ctx->o_offset, ctx->o_size);
287 buffer[ctx->o_size + 0] = ':';
288 buffer[ctx->o_size + 1] = ' ';
289 memcpy(buffer + ctx->o_size + 2,
290 data + ctx->cn_offset, ctx->cn_size);
291 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
292 goto done;
293
294 } else if (ctx->cn_size) {
295 namesize = ctx->cn_size;
296 name = data + ctx->cn_offset;
297 } else if (ctx->o_size) {
298 namesize = ctx->o_size;
299 name = data + ctx->o_offset;
300 } else {
301 namesize = ctx->email_size;
302 name = data + ctx->email_offset;
303 }
304
305single_component:
306 buffer = kmalloc(namesize + 1, GFP_KERNEL);
307 if (!buffer)
308 return -ENOMEM;
309 memcpy(buffer, name, namesize);
310 buffer[namesize] = 0;
311
312done:
313 *_name = buffer;
314 ctx->cn_size = 0;
315 ctx->o_size = 0;
316 ctx->email_size = 0;
317 return 0;
318}
319
320int x509_note_issuer(void *context, size_t hdrlen,
321 unsigned char tag,
322 const void *value, size_t vlen)
323{
324 struct x509_parse_context *ctx = context;
325 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
326}
327
328int x509_note_subject(void *context, size_t hdrlen,
329 unsigned char tag,
330 const void *value, size_t vlen)
331{
332 struct x509_parse_context *ctx = context;
333 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
334}
335
336/*
337 * Extract the data for the public key algorithm
338 */
339int x509_extract_key_data(void *context, size_t hdrlen,
340 unsigned char tag,
341 const void *value, size_t vlen)
342{
343 struct x509_parse_context *ctx = context;
344
345 if (ctx->last_oid != OID_rsaEncryption)
346 return -ENOPKG;
347
348 ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA;
349
350 /* Discard the BIT STRING metadata */
351 ctx->key = value + 1;
352 ctx->key_size = vlen - 1;
353 return 0;
354}
355
356/*
357 * Extract a RSA public key value
358 */
359int rsa_extract_mpi(void *context, size_t hdrlen,
360 unsigned char tag,
361 const void *value, size_t vlen)
362{
363 struct x509_parse_context *ctx = context;
364 MPI mpi;
365
366 if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
367 pr_err("Too many public key MPIs in certificate\n");
368 return -EBADMSG;
369 }
370
371 mpi = mpi_read_raw_data(value, vlen);
372 if (!mpi)
373 return -ENOMEM;
374
375 ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
376 return 0;
377}
378
379/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
380#define SEQ_TAG_KEYID (ASN1_CONT << 6)
381
382/*
383 * Process certificate extensions that are used to qualify the certificate.
384 */
385int x509_process_extension(void *context, size_t hdrlen,
386 unsigned char tag,
387 const void *value, size_t vlen)
388{
389 struct x509_parse_context *ctx = context;
390 const unsigned char *v = value;
391 char *f;
392 int i;
393
394 pr_debug("Extension: %u\n", ctx->last_oid);
395
396 if (ctx->last_oid == OID_subjectKeyIdentifier) {
397 /* Get hold of the key fingerprint */
398 if (vlen < 3)
399 return -EBADMSG;
400 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
401 return -EBADMSG;
402 v += 2;
403 vlen -= 2;
404
405 f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
406 if (!f)
407 return -ENOMEM;
408 for (i = 0; i < vlen; i++)
409 sprintf(f + i * 2, "%02x", v[i]);
410 pr_debug("fingerprint %s\n", f);
411 ctx->cert->fingerprint = f;
412 return 0;
413 }
414
415 if (ctx->last_oid == OID_authorityKeyIdentifier) {
416 size_t key_len;
417
418 /* Get hold of the CA key fingerprint */
419 if (vlen < 5)
420 return -EBADMSG;
421
422 /* Authority Key Identifier must be a Constructed SEQUENCE */
423 if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)))
424 return -EBADMSG;
425
426 /* Authority Key Identifier is not indefinite length */
427 if (unlikely(vlen == ASN1_INDEFINITE_LENGTH))
428 return -EBADMSG;
429
430 if (vlen < ASN1_INDEFINITE_LENGTH) {
431 /* Short Form length */
432 if (v[1] != vlen - 2 ||
433 v[2] != SEQ_TAG_KEYID ||
434 v[3] > vlen - 4)
435 return -EBADMSG;
436
437 key_len = v[3];
438 v += 4;
439 } else {
440 /* Long Form length */
441 size_t seq_len = 0;
442 size_t sub = v[1] - ASN1_INDEFINITE_LENGTH;
443
444 if (sub > 2)
445 return -EBADMSG;
446
447 /* calculate the length from subsequent octets */
448 v += 2;
449 for (i = 0; i < sub; i++) {
450 seq_len <<= 8;
451 seq_len |= v[i];
452 }
453
454 if (seq_len != vlen - 2 - sub ||
455 v[sub] != SEQ_TAG_KEYID ||
456 v[sub + 1] > vlen - 4 - sub)
457 return -EBADMSG;
458
459 key_len = v[sub + 1];
460 v += (sub + 2);
461 }
462
463 f = kmalloc(key_len * 2 + 1, GFP_KERNEL);
464 if (!f)
465 return -ENOMEM;
466 for (i = 0; i < key_len; i++)
467 sprintf(f + i * 2, "%02x", v[i]);
468 pr_debug("authority %s\n", f);
469 ctx->cert->authority = f;
470 return 0;
471 }
472
473 return 0;
474}
475
476/*
477 * Record a certificate time.
478 */
479static int x509_note_time(struct tm *tm, size_t hdrlen,
480 unsigned char tag,
481 const unsigned char *value, size_t vlen)
482{
483 const unsigned char *p = value;
484
485#define dec2bin(X) ((X) - '0')
486#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
487
488 if (tag == ASN1_UNITIM) {
489 /* UTCTime: YYMMDDHHMMSSZ */
490 if (vlen != 13)
491 goto unsupported_time;
492 tm->tm_year = DD2bin(p);
493 if (tm->tm_year >= 50)
494 tm->tm_year += 1900;
495 else
496 tm->tm_year += 2000;
497 } else if (tag == ASN1_GENTIM) {
498 /* GenTime: YYYYMMDDHHMMSSZ */
499 if (vlen != 15)
500 goto unsupported_time;
501 tm->tm_year = DD2bin(p) * 100 + DD2bin(p);
502 } else {
503 goto unsupported_time;
504 }
505
506 tm->tm_year -= 1900;
507 tm->tm_mon = DD2bin(p) - 1;
508 tm->tm_mday = DD2bin(p);
509 tm->tm_hour = DD2bin(p);
510 tm->tm_min = DD2bin(p);
511 tm->tm_sec = DD2bin(p);
512
513 if (*p != 'Z')
514 goto unsupported_time;
515
516 return 0;
517
518unsupported_time:
519 pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n",
520 tag, (int)vlen, (int)vlen, value);
521 return -EBADMSG;
522}
523
524int x509_note_not_before(void *context, size_t hdrlen,
525 unsigned char tag,
526 const void *value, size_t vlen)
527{
528 struct x509_parse_context *ctx = context;
529 return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
530}
531
532int x509_note_not_after(void *context, size_t hdrlen,
533 unsigned char tag,
534 const void *value, size_t vlen)
535{
536 struct x509_parse_context *ctx = context;
537 return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
538}