summaryrefslogtreecommitdiffstats
path: root/crypto/asymmetric_keys/pkcs7_parser.c
blob: 8357016131250b254085c7d2c0f7717948ad6cb6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
/* PKCS#7 parser
 *
 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#define pr_fmt(fmt) "PKCS7: "fmt
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/oid_registry.h>
#include <crypto/public_key.h>
#include "pkcs7_parser.h"
#include "pkcs7-asn1.h"

struct pkcs7_parse_context {
	struct pkcs7_message	*msg;		/* Message being constructed */
	struct pkcs7_signed_info *sinfo;	/* SignedInfo being constructed */
	struct pkcs7_signed_info **ppsinfo;
	struct x509_certificate *certs;		/* Certificate cache */
	struct x509_certificate **ppcerts;
	unsigned long	data;			/* Start of data */
	enum OID	last_oid;		/* Last OID encountered */
	unsigned	x509_index;
	unsigned	sinfo_index;
	const void	*raw_serial;
	unsigned	raw_serial_size;
	unsigned	raw_issuer_size;
	const void	*raw_issuer;
	const void	*raw_skid;
	unsigned	raw_skid_size;
	bool		expect_skid;
};

/*
 * Free a signed information block.
 */
static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
{
	if (sinfo) {
		public_key_signature_free(sinfo->sig);
		kfree(sinfo);
	}
}

/**
 * pkcs7_free_message - Free a PKCS#7 message
 * @pkcs7: The PKCS#7 message to free
 */
void pkcs7_free_message(struct pkcs7_message *pkcs7)
{
	struct x509_certificate *cert;
	struct pkcs7_signed_info *sinfo;

	if (pkcs7) {
		while (pkcs7->certs) {
			cert = pkcs7->certs;
			pkcs7->certs = cert->next;
			x509_free_certificate(cert);
		}
		while (pkcs7->crl) {
			cert = pkcs7->crl;
			pkcs7->crl = cert->next;
			x509_free_certificate(cert);
		}
		while (pkcs7->signed_infos) {
			sinfo = pkcs7->signed_infos;
			pkcs7->signed_infos = sinfo->next;
			pkcs7_free_signed_info(sinfo);
		}
		kfree(pkcs7);
	}
}
EXPORT_SYMBOL_GPL(pkcs7_free_message);

/*
 * Check authenticatedAttributes are provided or not provided consistently.
 */
static int pkcs7_check_authattrs(struct pkcs7_message *msg)
{
	struct pkcs7_signed_info *sinfo;
	bool want = false;

	sinfo = msg->signed_infos;
	if (sinfo->authattrs) {
		want = true;
		msg->have_authattrs = true;
	}

	for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next)
		if (!!sinfo->authattrs != want)
			goto inconsistent;
	return 0;

inconsistent:
	pr_warn("Inconsistently supplied authAttrs\n");
	return -EINVAL;
}

/**
 * pkcs7_parse_message - Parse a PKCS#7 message
 * @data: The raw binary ASN.1 encoded message to be parsed
 * @datalen: The size of the encoded message
 */
struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
{
	struct pkcs7_parse_context *ctx;
	struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
	int ret;

	ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
	if (!ctx)
		goto out_no_ctx;
	ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
	if (!ctx->msg)
		goto out_no_msg;
	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
	if (!ctx->sinfo)
		goto out_no_sinfo;
	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
				  GFP_KERNEL);
	if (!ctx->sinfo->sig)
		goto out_no_sig;

	ctx->data = (unsigned long)data;
	ctx->ppcerts = &ctx->certs;
	ctx->ppsinfo = &ctx->msg->signed_infos;

	/* Attempt to decode the signature */
	ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
	if (ret < 0) {
		msg = ERR_PTR(ret);
		goto out;
	}

	ret = pkcs7_check_authattrs(ctx->msg);
	if (ret < 0)
		goto out;

	msg = ctx->msg;
	ctx->msg = NULL;

out:
	while (ctx->certs) {
		struct x509_certificate *cert = ctx->certs;
		ctx->certs = cert->next;
		x509_free_certificate(cert);
	}
out_no_sig:
	pkcs7_free_signed_info(ctx->sinfo);
out_no_sinfo:
	pkcs7_free_message(ctx->msg);
out_no_msg:
	kfree(ctx);
out_no_ctx:
	return msg;
}
EXPORT_SYMBOL_GPL(pkcs7_parse_message);

/**
 * pkcs7_get_content_data - Get access to the PKCS#7 content
 * @pkcs7: The preparsed PKCS#7 message to access
 * @_data: Place to return a pointer to the data
 * @_data_len: Place to return the data length
 * @want_wrapper: True if the ASN.1 object header should be included in the data
 *
 * Get access to the data content of the PKCS#7 message, including, optionally,
 * the header of the ASN.1 object that contains it.  Returns -ENODATA if the
 * data object was missing from the message.
 */
int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
			   const void **_data, size_t *_data_len,
			   bool want_wrapper)
{
	size_t wrapper;

	if (!pkcs7->data)
		return -ENODATA;

	wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
	*_data = pkcs7->data - wrapper;
	*_data_len = pkcs7->data_len + wrapper;
	return 0;
}
EXPORT_SYMBOL_GPL(pkcs7_get_content_data);

/*
 * Note an OID when we find one for later processing when we know how
 * to interpret it.
 */
int pkcs7_note_OID(void *context, size_t hdrlen,
		   unsigned char tag,
		   const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	ctx->last_oid = look_up_OID(value, vlen);
	if (ctx->last_oid == OID__NR) {
		char buffer[50];
		sprint_oid(value, vlen, buffer, sizeof(buffer));
		printk("PKCS7: Unknown OID: [%lu] %s\n",
		       (unsigned long)value - ctx->data, buffer);
	}
	return 0;
}

/*
 * Note the digest algorithm for the signature.
 */
int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
			       unsigned char tag,
			       const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	switch (ctx->last_oid) {
	case OID_md4:
		ctx->sinfo->sig->hash_algo = "md4";
		break;
	case OID_md5:
		ctx->sinfo->sig->hash_algo = "md5";
		break;
	case OID_sha1:
		ctx->sinfo->sig->hash_algo = "sha1";
		break;
	case OID_sha256:
		ctx->sinfo->sig->hash_algo = "sha256";
		break;
	case OID_sha384:
		ctx->sinfo->sig->hash_algo = "sha384";
		break;
	case OID_sha512:
		ctx->sinfo->sig->hash_algo = "sha512";
		break;
	case OID_sha224:
		ctx->sinfo->sig->hash_algo = "sha224";
		break;
	default:
		printk("Unsupported digest algo: %u\n", ctx->last_oid);
		return -ENOPKG;
	}
	return 0;
}

/*
 * Note the public key algorithm for the signature.
 */
int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
			     unsigned char tag,
			     const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	switch (ctx->last_oid) {
	case OID_rsaEncryption:
		ctx->sinfo->sig->pkey_algo = "rsa";
		break;
	default:
		printk("Unsupported pkey algo: %u\n", ctx->last_oid);
		return -ENOPKG;
	}
	return 0;
}

/*
 * We only support signed data [RFC2315 sec 9].
 */
int pkcs7_check_content_type(void *context, size_t hdrlen,
			     unsigned char tag,
			     const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	if (ctx->last_oid != OID_signed_data) {
		pr_warn("Only support pkcs7_signedData type\n");
		return -EINVAL;
	}

	return 0;
}

/*
 * Note the SignedData version
 */
int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
				  unsigned char tag,
				  const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	unsigned version;

	if (vlen != 1)
		goto unsupported;

	ctx->msg->version = version = *(const u8 *)value;
	switch (version) {
	case 1:
		/* PKCS#7 SignedData [RFC2315 sec 9.1]
		 * CMS ver 1 SignedData [RFC5652 sec 5.1]
		 */
		break;
	case 3:
		/* CMS ver 3 SignedData [RFC2315 sec 5.1] */
		break;
	default:
		goto unsupported;
	}

	return 0;

unsupported:
	pr_warn("Unsupported SignedData version\n");
	return -EINVAL;
}

/*
 * Note the SignerInfo version
 */
int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
				  unsigned char tag,
				  const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	unsigned version;

	if (vlen != 1)
		goto unsupported;

	version = *(const u8 *)value;
	switch (version) {
	case 1:
		/* PKCS#7 SignerInfo [RFC2315 sec 9.2]
		 * CMS ver 1 SignerInfo [RFC5652 sec 5.3]
		 */
		if (ctx->msg->version != 1)
			goto version_mismatch;
		ctx->expect_skid = false;
		break;
	case 3:
		/* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */
		if (ctx->msg->version == 1)
			goto version_mismatch;
		ctx->expect_skid = true;
		break;
	default:
		goto unsupported;
	}

	return 0;

unsupported:
	pr_warn("Unsupported SignerInfo version\n");
	return -EINVAL;
version_mismatch:
	pr_warn("SignedData-SignerInfo version mismatch\n");
	return -EBADMSG;
}

/*
 * Extract a certificate and store it in the context.
 */
int pkcs7_extract_cert(void *context, size_t hdrlen,
		       unsigned char tag,
		       const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	struct x509_certificate *x509;

	if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
		pr_debug("Cert began with tag %02x at %lu\n",
			 tag, (unsigned long)ctx - ctx->data);
		return -EBADMSG;
	}

	/* We have to correct for the header so that the X.509 parser can start
	 * from the beginning.  Note that since X.509 stipulates DER, there
	 * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
	 * stipulates BER).
	 */
	value -= hdrlen;
	vlen += hdrlen;

	if (((u8*)value)[1] == 0x80)
		vlen += 2; /* Indefinite length - there should be an EOC */

	x509 = x509_cert_parse(value, vlen);
	if (IS_ERR(x509))
		return PTR_ERR(x509);

	x509->index = ++ctx->x509_index;
	pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
	pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);

	*ctx->ppcerts = x509;
	ctx->ppcerts = &x509->next;
	return 0;
}

/*
 * Save the certificate list
 */
int pkcs7_note_certificate_list(void *context, size_t hdrlen,
				unsigned char tag,
				const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	pr_devel("Got cert list (%02x)\n", tag);

	*ctx->ppcerts = ctx->msg->certs;
	ctx->msg->certs = ctx->certs;
	ctx->certs = NULL;
	ctx->ppcerts = &ctx->certs;
	return 0;
}

/*
 * Note the content type.
 */
int pkcs7_note_content(void *context, size_t hdrlen,
		       unsigned char tag,
		       const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	if (ctx->last_oid != OID_data &&
	    ctx->last_oid != OID_msIndirectData) {
		pr_warn("Unsupported data type %d\n", ctx->last_oid);
		return -EINVAL;
	}

	ctx->msg->data_type = ctx->last_oid;
	return 0;
}

/*
 * Extract the data from the message and store that and its content type OID in
 * the context.
 */
int pkcs7_note_data(void *context, size_t hdrlen,
		    unsigned char tag,
		    const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	pr_debug("Got data\n");

	ctx->msg->data = value;
	ctx->msg->data_len = vlen;
	ctx->msg->data_hdrlen = hdrlen;
	return 0;
}

/*
 * Parse authenticated attributes.
 */
int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
				      unsigned char tag,
				      const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	struct pkcs7_signed_info *sinfo = ctx->sinfo;
	enum OID content_type;

	pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);

	switch (ctx->last_oid) {
	case OID_contentType:
		if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
			goto repeated;
		content_type = look_up_OID(value, vlen);
		if (content_type != ctx->msg->data_type) {
			pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n",
				ctx->msg->data_type, sinfo->index,
				content_type);
			return -EBADMSG;
		}
		return 0;

	case OID_signingTime:
		if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
			goto repeated;
		/* Should we check that the signing time is consistent
		 * with the signer's X.509 cert?
		 */
		return x509_decode_time(&sinfo->signing_time,
					hdrlen, tag, value, vlen);

	case OID_messageDigest:
		if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
			goto repeated;
		if (tag != ASN1_OTS)
			return -EBADMSG;
		sinfo->msgdigest = value;
		sinfo->msgdigest_len = vlen;
		return 0;

	case OID_smimeCapabilites:
		if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
			goto repeated;
		if (ctx->msg->data_type != OID_msIndirectData) {
			pr_warn("S/MIME Caps only allowed with Authenticode\n");
			return -EKEYREJECTED;
		}
		return 0;

		/* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE
		 * char URLs and cont[1] 8-bit char URLs.
		 *
		 * Microsoft StatementType seems to contain a list of OIDs that
		 * are also used as extendedKeyUsage types in X.509 certs.
		 */
	case OID_msSpOpusInfo:
		if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
			goto repeated;
		goto authenticode_check;
	case OID_msStatementType:
		if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
			goto repeated;
	authenticode_check:
		if (ctx->msg->data_type != OID_msIndirectData) {
			pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n");
			return -EKEYREJECTED;
		}
		/* I'm not sure how to validate these */
		return 0;
	default:
		return 0;
	}

repeated:
	/* We permit max one item per AuthenticatedAttribute and no repeats */
	pr_warn("Repeated/multivalue AuthAttrs not permitted\n");
	return -EKEYREJECTED;
}

/*
 * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3]
 */
int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
				    unsigned char tag,
				    const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	struct pkcs7_signed_info *sinfo = ctx->sinfo;

	if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) ||
	    !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) {
		pr_warn("Missing required AuthAttr\n");
		return -EBADMSG;
	}

	if (ctx->msg->data_type != OID_msIndirectData &&
	    test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
		pr_warn("Unexpected Authenticode AuthAttr\n");
		return -EBADMSG;
	}

	/* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
	sinfo->authattrs = value - (hdrlen - 1);
	sinfo->authattrs_len = vlen + (hdrlen - 1);
	return 0;
}

/*
 * Note the issuing certificate serial number
 */
int pkcs7_sig_note_serial(void *context, size_t hdrlen,
			  unsigned char tag,
			  const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	ctx->raw_serial = value;
	ctx->raw_serial_size = vlen;
	return 0;
}

/*
 * Note the issuer's name
 */
int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
			  unsigned char tag,
			  const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	ctx->raw_issuer = value;
	ctx->raw_issuer_size = vlen;
	return 0;
}

/*
 * Note the issuing cert's subjectKeyIdentifier
 */
int pkcs7_sig_note_skid(void *context, size_t hdrlen,
			unsigned char tag,
			const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);

	ctx->raw_skid = value;
	ctx->raw_skid_size = vlen;
	return 0;
}

/*
 * Note the signature data
 */
int pkcs7_sig_note_signature(void *context, size_t hdrlen,
			     unsigned char tag,
			     const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;

	ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL);
	if (!ctx->sinfo->sig->s)
		return -ENOMEM;

	ctx->sinfo->sig->s_size = vlen;
	return 0;
}

/*
 * Note a signature information block
 */
int pkcs7_note_signed_info(void *context, size_t hdrlen,
			   unsigned char tag,
			   const void *value, size_t vlen)
{
	struct pkcs7_parse_context *ctx = context;
	struct pkcs7_signed_info *sinfo = ctx->sinfo;
	struct asymmetric_key_id *kid;

	if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) {
		pr_warn("Authenticode requires AuthAttrs\n");
		return -EBADMSG;
	}

	/* Generate cert issuer + serial number key ID */
	if (!ctx->expect_skid) {
		kid = asymmetric_key_generate_id(ctx->raw_serial,
						 ctx->raw_serial_size,
						 ctx->raw_issuer,
						 ctx->raw_issuer_size);
	} else {
		kid = asymmetric_key_generate_id(ctx->raw_skid,
						 ctx->raw_skid_size,
						 "", 0);
	}
	if (IS_ERR(kid))
		return PTR_ERR(kid);

	pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data);

	sinfo->sig->auth_ids[0] = kid;
	sinfo->index = ++ctx->sinfo_index;
	*ctx->ppsinfo = sinfo;
	ctx->ppsinfo = &sinfo->next;
	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
	if (!ctx->sinfo)
		return -ENOMEM;
	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
				  GFP_KERNEL);
	if (!ctx->sinfo->sig)
		return -ENOMEM;
	return 0;
}