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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 *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;
41};
42
43/*
44 * Free an X.509 certificate
45 */
46void x509_free_certificate(struct x509_certificate *cert)
47{
48 if (cert) {
49 public_key_free(cert->pub);
50 public_key_signature_free(cert->sig);
51 kfree(cert->issuer);
52 kfree(cert->subject);
53 kfree(cert->id);
54 kfree(cert->skid);
55 kfree(cert);
56 }
57}
58EXPORT_SYMBOL_GPL(x509_free_certificate);
59
60/*
61 * Parse an X.509 certificate
62 */
63struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
64{
65 struct x509_certificate *cert;
66 struct x509_parse_context *ctx;
67 struct asymmetric_key_id *kid;
68 long ret;
69
70 ret = -ENOMEM;
71 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
72 if (!cert)
73 goto error_no_cert;
74 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
75 if (!cert->pub)
76 goto error_no_ctx;
77 cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
78 if (!cert->sig)
79 goto error_no_ctx;
80 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
81 if (!ctx)
82 goto error_no_ctx;
83
84 ctx->cert = cert;
85 ctx->data = (unsigned long)data;
86
87 /* Attempt to decode the certificate */
88 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
89 if (ret < 0)
90 goto error_decode;
91
92 /* Decode the AuthorityKeyIdentifier */
93 if (ctx->raw_akid) {
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);
98 if (ret < 0) {
99 pr_warn("Couldn't decode AuthKeyIdentifier\n");
100 goto error_decode;
101 }
102 }
103
104 ret = -ENOMEM;
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 cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
112 if (!cert->pub->params)
113 goto error_decode;
114
115 cert->pub->paramlen = ctx->params_size;
116 cert->pub->algo = ctx->key_algo;
117
118 /* Grab the signature bits */
119 ret = x509_get_sig_params(cert);
120 if (ret < 0)
121 goto error_decode;
122
123 /* Generate cert issuer + serial number key ID */
124 kid = asymmetric_key_generate_id(cert->raw_serial,
125 cert->raw_serial_size,
126 cert->raw_issuer,
127 cert->raw_issuer_size);
128 if (IS_ERR(kid)) {
129 ret = PTR_ERR(kid);
130 goto error_decode;
131 }
132 cert->id = kid;
133
134 /* Detect self-signed certificates */
135 ret = x509_check_for_self_signed(cert);
136 if (ret < 0)
137 goto error_decode;
138
139 kfree(ctx);
140 return cert;
141
142error_decode:
143 kfree(ctx);
144error_no_ctx:
145 x509_free_certificate(cert);
146error_no_cert:
147 return ERR_PTR(ret);
148}
149EXPORT_SYMBOL_GPL(x509_cert_parse);
150
151/*
152 * Note an OID when we find one for later processing when we know how
153 * to interpret it.
154 */
155int x509_note_OID(void *context, size_t hdrlen,
156 unsigned char tag,
157 const void *value, size_t vlen)
158{
159 struct x509_parse_context *ctx = context;
160
161 ctx->last_oid = look_up_OID(value, vlen);
162 if (ctx->last_oid == OID__NR) {
163 char buffer[50];
164 sprint_oid(value, vlen, buffer, sizeof(buffer));
165 pr_debug("Unknown OID: [%lu] %s\n",
166 (unsigned long)value - ctx->data, buffer);
167 }
168 return 0;
169}
170
171/*
172 * Save the position of the TBS data so that we can check the signature over it
173 * later.
174 */
175int x509_note_tbs_certificate(void *context, size_t hdrlen,
176 unsigned char tag,
177 const void *value, size_t vlen)
178{
179 struct x509_parse_context *ctx = context;
180
181 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
182 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
183
184 ctx->cert->tbs = value - hdrlen;
185 ctx->cert->tbs_size = vlen + hdrlen;
186 return 0;
187}
188
189/*
190 * Record the public key algorithm
191 */
192int x509_note_pkey_algo(void *context, size_t hdrlen,
193 unsigned char tag,
194 const void *value, size_t vlen)
195{
196 struct x509_parse_context *ctx = context;
197
198 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
199
200 switch (ctx->last_oid) {
201 case OID_md2WithRSAEncryption:
202 case OID_md3WithRSAEncryption:
203 default:
204 return -ENOPKG; /* Unsupported combination */
205
206 case OID_md4WithRSAEncryption:
207 ctx->cert->sig->hash_algo = "md4";
208 goto rsa_pkcs1;
209
210 case OID_sha1WithRSAEncryption:
211 ctx->cert->sig->hash_algo = "sha1";
212 goto rsa_pkcs1;
213
214 case OID_sha256WithRSAEncryption:
215 ctx->cert->sig->hash_algo = "sha256";
216 goto rsa_pkcs1;
217
218 case OID_sha384WithRSAEncryption:
219 ctx->cert->sig->hash_algo = "sha384";
220 goto rsa_pkcs1;
221
222 case OID_sha512WithRSAEncryption:
223 ctx->cert->sig->hash_algo = "sha512";
224 goto rsa_pkcs1;
225
226 case OID_sha224WithRSAEncryption:
227 ctx->cert->sig->hash_algo = "sha224";
228 goto rsa_pkcs1;
229
230 case OID_gost2012Signature256:
231 ctx->cert->sig->hash_algo = "streebog256";
232 goto ecrdsa;
233
234 case OID_gost2012Signature512:
235 ctx->cert->sig->hash_algo = "streebog512";
236 goto ecrdsa;
237 }
238
239rsa_pkcs1:
240 ctx->cert->sig->pkey_algo = "rsa";
241 ctx->cert->sig->encoding = "pkcs1";
242 ctx->algo_oid = ctx->last_oid;
243 return 0;
244ecrdsa:
245 ctx->cert->sig->pkey_algo = "ecrdsa";
246 ctx->cert->sig->encoding = "raw";
247 ctx->algo_oid = ctx->last_oid;
248 return 0;
249}
250
251/*
252 * Note the whereabouts and type of the signature.
253 */
254int x509_note_signature(void *context, size_t hdrlen,
255 unsigned char tag,
256 const void *value, size_t vlen)
257{
258 struct x509_parse_context *ctx = context;
259
260 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
261
262 if (ctx->last_oid != ctx->algo_oid) {
263 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
264 ctx->algo_oid, ctx->last_oid);
265 return -EINVAL;
266 }
267
268 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
269 strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0) {
270 /* Discard the BIT STRING metadata */
271 if (vlen < 1 || *(const u8 *)value != 0)
272 return -EBADMSG;
273
274 value++;
275 vlen--;
276 }
277
278 ctx->cert->raw_sig = value;
279 ctx->cert->raw_sig_size = vlen;
280 return 0;
281}
282
283/*
284 * Note the certificate serial number
285 */
286int x509_note_serial(void *context, size_t hdrlen,
287 unsigned char tag,
288 const void *value, size_t vlen)
289{
290 struct x509_parse_context *ctx = context;
291 ctx->cert->raw_serial = value;
292 ctx->cert->raw_serial_size = vlen;
293 return 0;
294}
295
296/*
297 * Note some of the name segments from which we'll fabricate a name.
298 */
299int x509_extract_name_segment(void *context, size_t hdrlen,
300 unsigned char tag,
301 const void *value, size_t vlen)
302{
303 struct x509_parse_context *ctx = context;
304
305 switch (ctx->last_oid) {
306 case OID_commonName:
307 ctx->cn_size = vlen;
308 ctx->cn_offset = (unsigned long)value - ctx->data;
309 break;
310 case OID_organizationName:
311 ctx->o_size = vlen;
312 ctx->o_offset = (unsigned long)value - ctx->data;
313 break;
314 case OID_email_address:
315 ctx->email_size = vlen;
316 ctx->email_offset = (unsigned long)value - ctx->data;
317 break;
318 default:
319 break;
320 }
321
322 return 0;
323}
324
325/*
326 * Fabricate and save the issuer and subject names
327 */
328static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
329 unsigned char tag,
330 char **_name, size_t vlen)
331{
332 const void *name, *data = (const void *)ctx->data;
333 size_t namesize;
334 char *buffer;
335
336 if (*_name)
337 return -EINVAL;
338
339 /* Empty name string if no material */
340 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
341 buffer = kmalloc(1, GFP_KERNEL);
342 if (!buffer)
343 return -ENOMEM;
344 buffer[0] = 0;
345 goto done;
346 }
347
348 if (ctx->cn_size && ctx->o_size) {
349 /* Consider combining O and CN, but use only the CN if it is
350 * prefixed by the O, or a significant portion thereof.
351 */
352 namesize = ctx->cn_size;
353 name = data + ctx->cn_offset;
354 if (ctx->cn_size >= ctx->o_size &&
355 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
356 ctx->o_size) == 0)
357 goto single_component;
358 if (ctx->cn_size >= 7 &&
359 ctx->o_size >= 7 &&
360 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
361 goto single_component;
362
363 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
364 GFP_KERNEL);
365 if (!buffer)
366 return -ENOMEM;
367
368 memcpy(buffer,
369 data + ctx->o_offset, ctx->o_size);
370 buffer[ctx->o_size + 0] = ':';
371 buffer[ctx->o_size + 1] = ' ';
372 memcpy(buffer + ctx->o_size + 2,
373 data + ctx->cn_offset, ctx->cn_size);
374 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
375 goto done;
376
377 } else if (ctx->cn_size) {
378 namesize = ctx->cn_size;
379 name = data + ctx->cn_offset;
380 } else if (ctx->o_size) {
381 namesize = ctx->o_size;
382 name = data + ctx->o_offset;
383 } else {
384 namesize = ctx->email_size;
385 name = data + ctx->email_offset;
386 }
387
388single_component:
389 buffer = kmalloc(namesize + 1, GFP_KERNEL);
390 if (!buffer)
391 return -ENOMEM;
392 memcpy(buffer, name, namesize);
393 buffer[namesize] = 0;
394
395done:
396 *_name = buffer;
397 ctx->cn_size = 0;
398 ctx->o_size = 0;
399 ctx->email_size = 0;
400 return 0;
401}
402
403int x509_note_issuer(void *context, size_t hdrlen,
404 unsigned char tag,
405 const void *value, size_t vlen)
406{
407 struct x509_parse_context *ctx = context;
408 ctx->cert->raw_issuer = value;
409 ctx->cert->raw_issuer_size = vlen;
410 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
411}
412
413int x509_note_subject(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 ctx->cert->raw_subject = value;
419 ctx->cert->raw_subject_size = vlen;
420 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
421}
422
423/*
424 * Extract the parameters for the public key
425 */
426int x509_note_params(void *context, size_t hdrlen,
427 unsigned char tag,
428 const void *value, size_t vlen)
429{
430 struct x509_parse_context *ctx = context;
431
432 /*
433 * AlgorithmIdentifier is used three times in the x509, we should skip
434 * first and ignore third, using second one which is after subject and
435 * before subjectPublicKey.
436 */
437 if (!ctx->cert->raw_subject || ctx->key)
438 return 0;
439 ctx->params = value - hdrlen;
440 ctx->params_size = vlen + hdrlen;
441 return 0;
442}
443
444/*
445 * Extract the data for the public key algorithm
446 */
447int x509_extract_key_data(void *context, size_t hdrlen,
448 unsigned char tag,
449 const void *value, size_t vlen)
450{
451 struct x509_parse_context *ctx = context;
452
453 ctx->key_algo = ctx->last_oid;
454 if (ctx->last_oid == OID_rsaEncryption)
455 ctx->cert->pub->pkey_algo = "rsa";
456 else if (ctx->last_oid == OID_gost2012PKey256 ||
457 ctx->last_oid == OID_gost2012PKey512)
458 ctx->cert->pub->pkey_algo = "ecrdsa";
459 else
460 return -ENOPKG;
461
462 /* Discard the BIT STRING metadata */
463 if (vlen < 1 || *(const u8 *)value != 0)
464 return -EBADMSG;
465 ctx->key = value + 1;
466 ctx->key_size = vlen - 1;
467 return 0;
468}
469
470/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
471#define SEQ_TAG_KEYID (ASN1_CONT << 6)
472
473/*
474 * Process certificate extensions that are used to qualify the certificate.
475 */
476int x509_process_extension(void *context, size_t hdrlen,
477 unsigned char tag,
478 const void *value, size_t vlen)
479{
480 struct x509_parse_context *ctx = context;
481 struct asymmetric_key_id *kid;
482 const unsigned char *v = value;
483
484 pr_debug("Extension: %u\n", ctx->last_oid);
485
486 if (ctx->last_oid == OID_subjectKeyIdentifier) {
487 /* Get hold of the key fingerprint */
488 if (ctx->cert->skid || vlen < 3)
489 return -EBADMSG;
490 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
491 return -EBADMSG;
492 v += 2;
493 vlen -= 2;
494
495 ctx->cert->raw_skid_size = vlen;
496 ctx->cert->raw_skid = v;
497 kid = asymmetric_key_generate_id(v, vlen, "", 0);
498 if (IS_ERR(kid))
499 return PTR_ERR(kid);
500 ctx->cert->skid = kid;
501 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
502 return 0;
503 }
504
505 if (ctx->last_oid == OID_authorityKeyIdentifier) {
506 /* Get hold of the CA key fingerprint */
507 ctx->raw_akid = v;
508 ctx->raw_akid_size = vlen;
509 return 0;
510 }
511
512 return 0;
513}
514
515/**
516 * x509_decode_time - Decode an X.509 time ASN.1 object
517 * @_t: The time to fill in
518 * @hdrlen: The length of the object header
519 * @tag: The object tag
520 * @value: The object value
521 * @vlen: The size of the object value
522 *
523 * Decode an ASN.1 universal time or generalised time field into a struct the
524 * kernel can handle and check it for validity. The time is decoded thus:
525 *
526 * [RFC5280 §4.1.2.5]
527 * CAs conforming to this profile MUST always encode certificate validity
528 * dates through the year 2049 as UTCTime; certificate validity dates in
529 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
530 * applications MUST be able to process validity dates that are encoded in
531 * either UTCTime or GeneralizedTime.
532 */
533int x509_decode_time(time64_t *_t, size_t hdrlen,
534 unsigned char tag,
535 const unsigned char *value, size_t vlen)
536{
537 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
538 31, 31, 30, 31, 30, 31 };
539 const unsigned char *p = value;
540 unsigned year, mon, day, hour, min, sec, mon_len;
541
542#define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
543#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
544
545 if (tag == ASN1_UNITIM) {
546 /* UTCTime: YYMMDDHHMMSSZ */
547 if (vlen != 13)
548 goto unsupported_time;
549 year = DD2bin(p);
550 if (year >= 50)
551 year += 1900;
552 else
553 year += 2000;
554 } else if (tag == ASN1_GENTIM) {
555 /* GenTime: YYYYMMDDHHMMSSZ */
556 if (vlen != 15)
557 goto unsupported_time;
558 year = DD2bin(p) * 100 + DD2bin(p);
559 if (year >= 1950 && year <= 2049)
560 goto invalid_time;
561 } else {
562 goto unsupported_time;
563 }
564
565 mon = DD2bin(p);
566 day = DD2bin(p);
567 hour = DD2bin(p);
568 min = DD2bin(p);
569 sec = DD2bin(p);
570
571 if (*p != 'Z')
572 goto unsupported_time;
573
574 if (year < 1970 ||
575 mon < 1 || mon > 12)
576 goto invalid_time;
577
578 mon_len = month_lengths[mon - 1];
579 if (mon == 2) {
580 if (year % 4 == 0) {
581 mon_len = 29;
582 if (year % 100 == 0) {
583 mon_len = 28;
584 if (year % 400 == 0)
585 mon_len = 29;
586 }
587 }
588 }
589
590 if (day < 1 || day > mon_len ||
591 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
592 min > 59 ||
593 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
594 goto invalid_time;
595
596 *_t = mktime64(year, mon, day, hour, min, sec);
597 return 0;
598
599unsupported_time:
600 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
601 tag, (int)vlen, value);
602 return -EBADMSG;
603invalid_time:
604 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
605 tag, (int)vlen, value);
606 return -EBADMSG;
607}
608EXPORT_SYMBOL_GPL(x509_decode_time);
609
610int x509_note_not_before(void *context, size_t hdrlen,
611 unsigned char tag,
612 const void *value, size_t vlen)
613{
614 struct x509_parse_context *ctx = context;
615 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
616}
617
618int x509_note_not_after(void *context, size_t hdrlen,
619 unsigned char tag,
620 const void *value, size_t vlen)
621{
622 struct x509_parse_context *ctx = context;
623 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
624}
625
626/*
627 * Note a key identifier-based AuthorityKeyIdentifier
628 */
629int x509_akid_note_kid(void *context, size_t hdrlen,
630 unsigned char tag,
631 const void *value, size_t vlen)
632{
633 struct x509_parse_context *ctx = context;
634 struct asymmetric_key_id *kid;
635
636 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
637
638 if (ctx->cert->sig->auth_ids[1])
639 return 0;
640
641 kid = asymmetric_key_generate_id(value, vlen, "", 0);
642 if (IS_ERR(kid))
643 return PTR_ERR(kid);
644 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
645 ctx->cert->sig->auth_ids[1] = kid;
646 return 0;
647}
648
649/*
650 * Note a directoryName in an AuthorityKeyIdentifier
651 */
652int x509_akid_note_name(void *context, size_t hdrlen,
653 unsigned char tag,
654 const void *value, size_t vlen)
655{
656 struct x509_parse_context *ctx = context;
657
658 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
659
660 ctx->akid_raw_issuer = value;
661 ctx->akid_raw_issuer_size = vlen;
662 return 0;
663}
664
665/*
666 * Note a serial number in an AuthorityKeyIdentifier
667 */
668int x509_akid_note_serial(void *context, size_t hdrlen,
669 unsigned char tag,
670 const void *value, size_t vlen)
671{
672 struct x509_parse_context *ctx = context;
673 struct asymmetric_key_id *kid;
674
675 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
676
677 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
678 return 0;
679
680 kid = asymmetric_key_generate_id(value,
681 vlen,
682 ctx->akid_raw_issuer,
683 ctx->akid_raw_issuer_size);
684 if (IS_ERR(kid))
685 return PTR_ERR(kid);
686
687 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
688 ctx->cert->sig->auth_ids[0] = kid;
689 return 0;
690}
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}