xref: /linux/crypto/asymmetric_keys/pkcs7_parser.c (revision 6fdcba32711044c35c0e1b094cbd8f3f0b4472c9) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* PKCS#7 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) "PKCS7: "fmt
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/export.h>
12 #include <linux/slab.h>
13 #include <linux/err.h>
14 #include <linux/oid_registry.h>
15 #include <crypto/public_key.h>
16 #include "pkcs7_parser.h"
17 #include "pkcs7.asn1.h"
18 
19 MODULE_DESCRIPTION("PKCS#7 parser");
20 MODULE_AUTHOR("Red Hat, Inc.");
21 MODULE_LICENSE("GPL");
22 
23 struct pkcs7_parse_context {
24 	struct pkcs7_message	*msg;		/* Message being constructed */
25 	struct pkcs7_signed_info *sinfo;	/* SignedInfo being constructed */
26 	struct pkcs7_signed_info **ppsinfo;
27 	struct x509_certificate *certs;		/* Certificate cache */
28 	struct x509_certificate **ppcerts;
29 	unsigned long	data;			/* Start of data */
30 	enum OID	last_oid;		/* Last OID encountered */
31 	unsigned	x509_index;
32 	unsigned	sinfo_index;
33 	const void	*raw_serial;
34 	unsigned	raw_serial_size;
35 	unsigned	raw_issuer_size;
36 	const void	*raw_issuer;
37 	const void	*raw_skid;
38 	unsigned	raw_skid_size;
39 	bool		expect_skid;
40 };
41 
42 /*
43  * Free a signed information block.
44  */
45 static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
46 {
47 	if (sinfo) {
48 		public_key_signature_free(sinfo->sig);
49 		kfree(sinfo);
50 	}
51 }
52 
53 /**
54  * pkcs7_free_message - Free a PKCS#7 message
55  * @pkcs7: The PKCS#7 message to free
56  */
57 void pkcs7_free_message(struct pkcs7_message *pkcs7)
58 {
59 	struct x509_certificate *cert;
60 	struct pkcs7_signed_info *sinfo;
61 
62 	if (pkcs7) {
63 		while (pkcs7->certs) {
64 			cert = pkcs7->certs;
65 			pkcs7->certs = cert->next;
66 			x509_free_certificate(cert);
67 		}
68 		while (pkcs7->crl) {
69 			cert = pkcs7->crl;
70 			pkcs7->crl = cert->next;
71 			x509_free_certificate(cert);
72 		}
73 		while (pkcs7->signed_infos) {
74 			sinfo = pkcs7->signed_infos;
75 			pkcs7->signed_infos = sinfo->next;
76 			pkcs7_free_signed_info(sinfo);
77 		}
78 		kfree(pkcs7);
79 	}
80 }
81 EXPORT_SYMBOL_GPL(pkcs7_free_message);
82 
83 /*
84  * Check authenticatedAttributes are provided or not provided consistently.
85  */
86 static int pkcs7_check_authattrs(struct pkcs7_message *msg)
87 {
88 	struct pkcs7_signed_info *sinfo;
89 	bool want = false;
90 
91 	sinfo = msg->signed_infos;
92 	if (!sinfo)
93 		goto inconsistent;
94 
95 	if (sinfo->authattrs) {
96 		want = true;
97 		msg->have_authattrs = true;
98 	}
99 
100 	for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next)
101 		if (!!sinfo->authattrs != want)
102 			goto inconsistent;
103 	return 0;
104 
105 inconsistent:
106 	pr_warn("Inconsistently supplied authAttrs\n");
107 	return -EINVAL;
108 }
109 
110 /**
111  * pkcs7_parse_message - Parse a PKCS#7 message
112  * @data: The raw binary ASN.1 encoded message to be parsed
113  * @datalen: The size of the encoded message
114  */
115 struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
116 {
117 	struct pkcs7_parse_context *ctx;
118 	struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
119 	int ret;
120 
121 	ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
122 	if (!ctx)
123 		goto out_no_ctx;
124 	ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
125 	if (!ctx->msg)
126 		goto out_no_msg;
127 	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
128 	if (!ctx->sinfo)
129 		goto out_no_sinfo;
130 	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
131 				  GFP_KERNEL);
132 	if (!ctx->sinfo->sig)
133 		goto out_no_sig;
134 
135 	ctx->data = (unsigned long)data;
136 	ctx->ppcerts = &ctx->certs;
137 	ctx->ppsinfo = &ctx->msg->signed_infos;
138 
139 	/* Attempt to decode the signature */
140 	ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
141 	if (ret < 0) {
142 		msg = ERR_PTR(ret);
143 		goto out;
144 	}
145 
146 	ret = pkcs7_check_authattrs(ctx->msg);
147 	if (ret < 0) {
148 		msg = ERR_PTR(ret);
149 		goto out;
150 	}
151 
152 	msg = ctx->msg;
153 	ctx->msg = NULL;
154 
155 out:
156 	while (ctx->certs) {
157 		struct x509_certificate *cert = ctx->certs;
158 		ctx->certs = cert->next;
159 		x509_free_certificate(cert);
160 	}
161 out_no_sig:
162 	pkcs7_free_signed_info(ctx->sinfo);
163 out_no_sinfo:
164 	pkcs7_free_message(ctx->msg);
165 out_no_msg:
166 	kfree(ctx);
167 out_no_ctx:
168 	return msg;
169 }
170 EXPORT_SYMBOL_GPL(pkcs7_parse_message);
171 
172 /**
173  * pkcs7_get_content_data - Get access to the PKCS#7 content
174  * @pkcs7: The preparsed PKCS#7 message to access
175  * @_data: Place to return a pointer to the data
176  * @_data_len: Place to return the data length
177  * @_headerlen: Size of ASN.1 header not included in _data
178  *
179  * Get access to the data content of the PKCS#7 message.  The size of the
180  * header of the ASN.1 object that contains it is also provided and can be used
181  * to adjust *_data and *_data_len to get the entire object.
182  *
183  * Returns -ENODATA if the data object was missing from the message.
184  */
185 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
186 			   const void **_data, size_t *_data_len,
187 			   size_t *_headerlen)
188 {
189 	if (!pkcs7->data)
190 		return -ENODATA;
191 
192 	*_data = pkcs7->data;
193 	*_data_len = pkcs7->data_len;
194 	if (_headerlen)
195 		*_headerlen = pkcs7->data_hdrlen;
196 	return 0;
197 }
198 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
199 
200 /*
201  * Note an OID when we find one for later processing when we know how
202  * to interpret it.
203  */
204 int pkcs7_note_OID(void *context, size_t hdrlen,
205 		   unsigned char tag,
206 		   const void *value, size_t vlen)
207 {
208 	struct pkcs7_parse_context *ctx = context;
209 
210 	ctx->last_oid = look_up_OID(value, vlen);
211 	if (ctx->last_oid == OID__NR) {
212 		char buffer[50];
213 		sprint_oid(value, vlen, buffer, sizeof(buffer));
214 		printk("PKCS7: Unknown OID: [%lu] %s\n",
215 		       (unsigned long)value - ctx->data, buffer);
216 	}
217 	return 0;
218 }
219 
220 /*
221  * Note the digest algorithm for the signature.
222  */
223 int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
224 			       unsigned char tag,
225 			       const void *value, size_t vlen)
226 {
227 	struct pkcs7_parse_context *ctx = context;
228 
229 	switch (ctx->last_oid) {
230 	case OID_md4:
231 		ctx->sinfo->sig->hash_algo = "md4";
232 		break;
233 	case OID_md5:
234 		ctx->sinfo->sig->hash_algo = "md5";
235 		break;
236 	case OID_sha1:
237 		ctx->sinfo->sig->hash_algo = "sha1";
238 		break;
239 	case OID_sha256:
240 		ctx->sinfo->sig->hash_algo = "sha256";
241 		break;
242 	case OID_sha384:
243 		ctx->sinfo->sig->hash_algo = "sha384";
244 		break;
245 	case OID_sha512:
246 		ctx->sinfo->sig->hash_algo = "sha512";
247 		break;
248 	case OID_sha224:
249 		ctx->sinfo->sig->hash_algo = "sha224";
250 		break;
251 	default:
252 		printk("Unsupported digest algo: %u\n", ctx->last_oid);
253 		return -ENOPKG;
254 	}
255 	return 0;
256 }
257 
258 /*
259  * Note the public key algorithm for the signature.
260  */
261 int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
262 			     unsigned char tag,
263 			     const void *value, size_t vlen)
264 {
265 	struct pkcs7_parse_context *ctx = context;
266 
267 	switch (ctx->last_oid) {
268 	case OID_rsaEncryption:
269 		ctx->sinfo->sig->pkey_algo = "rsa";
270 		ctx->sinfo->sig->encoding = "pkcs1";
271 		break;
272 	default:
273 		printk("Unsupported pkey algo: %u\n", ctx->last_oid);
274 		return -ENOPKG;
275 	}
276 	return 0;
277 }
278 
279 /*
280  * We only support signed data [RFC2315 sec 9].
281  */
282 int pkcs7_check_content_type(void *context, size_t hdrlen,
283 			     unsigned char tag,
284 			     const void *value, size_t vlen)
285 {
286 	struct pkcs7_parse_context *ctx = context;
287 
288 	if (ctx->last_oid != OID_signed_data) {
289 		pr_warn("Only support pkcs7_signedData type\n");
290 		return -EINVAL;
291 	}
292 
293 	return 0;
294 }
295 
296 /*
297  * Note the SignedData version
298  */
299 int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
300 				  unsigned char tag,
301 				  const void *value, size_t vlen)
302 {
303 	struct pkcs7_parse_context *ctx = context;
304 	unsigned version;
305 
306 	if (vlen != 1)
307 		goto unsupported;
308 
309 	ctx->msg->version = version = *(const u8 *)value;
310 	switch (version) {
311 	case 1:
312 		/* PKCS#7 SignedData [RFC2315 sec 9.1]
313 		 * CMS ver 1 SignedData [RFC5652 sec 5.1]
314 		 */
315 		break;
316 	case 3:
317 		/* CMS ver 3 SignedData [RFC2315 sec 5.1] */
318 		break;
319 	default:
320 		goto unsupported;
321 	}
322 
323 	return 0;
324 
325 unsupported:
326 	pr_warn("Unsupported SignedData version\n");
327 	return -EINVAL;
328 }
329 
330 /*
331  * Note the SignerInfo version
332  */
333 int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
334 				  unsigned char tag,
335 				  const void *value, size_t vlen)
336 {
337 	struct pkcs7_parse_context *ctx = context;
338 	unsigned version;
339 
340 	if (vlen != 1)
341 		goto unsupported;
342 
343 	version = *(const u8 *)value;
344 	switch (version) {
345 	case 1:
346 		/* PKCS#7 SignerInfo [RFC2315 sec 9.2]
347 		 * CMS ver 1 SignerInfo [RFC5652 sec 5.3]
348 		 */
349 		if (ctx->msg->version != 1)
350 			goto version_mismatch;
351 		ctx->expect_skid = false;
352 		break;
353 	case 3:
354 		/* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */
355 		if (ctx->msg->version == 1)
356 			goto version_mismatch;
357 		ctx->expect_skid = true;
358 		break;
359 	default:
360 		goto unsupported;
361 	}
362 
363 	return 0;
364 
365 unsupported:
366 	pr_warn("Unsupported SignerInfo version\n");
367 	return -EINVAL;
368 version_mismatch:
369 	pr_warn("SignedData-SignerInfo version mismatch\n");
370 	return -EBADMSG;
371 }
372 
373 /*
374  * Extract a certificate and store it in the context.
375  */
376 int pkcs7_extract_cert(void *context, size_t hdrlen,
377 		       unsigned char tag,
378 		       const void *value, size_t vlen)
379 {
380 	struct pkcs7_parse_context *ctx = context;
381 	struct x509_certificate *x509;
382 
383 	if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
384 		pr_debug("Cert began with tag %02x at %lu\n",
385 			 tag, (unsigned long)ctx - ctx->data);
386 		return -EBADMSG;
387 	}
388 
389 	/* We have to correct for the header so that the X.509 parser can start
390 	 * from the beginning.  Note that since X.509 stipulates DER, there
391 	 * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
392 	 * stipulates BER).
393 	 */
394 	value -= hdrlen;
395 	vlen += hdrlen;
396 
397 	if (((u8*)value)[1] == 0x80)
398 		vlen += 2; /* Indefinite length - there should be an EOC */
399 
400 	x509 = x509_cert_parse(value, vlen);
401 	if (IS_ERR(x509))
402 		return PTR_ERR(x509);
403 
404 	x509->index = ++ctx->x509_index;
405 	pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
406 	pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
407 
408 	*ctx->ppcerts = x509;
409 	ctx->ppcerts = &x509->next;
410 	return 0;
411 }
412 
413 /*
414  * Save the certificate list
415  */
416 int pkcs7_note_certificate_list(void *context, size_t hdrlen,
417 				unsigned char tag,
418 				const void *value, size_t vlen)
419 {
420 	struct pkcs7_parse_context *ctx = context;
421 
422 	pr_devel("Got cert list (%02x)\n", tag);
423 
424 	*ctx->ppcerts = ctx->msg->certs;
425 	ctx->msg->certs = ctx->certs;
426 	ctx->certs = NULL;
427 	ctx->ppcerts = &ctx->certs;
428 	return 0;
429 }
430 
431 /*
432  * Note the content type.
433  */
434 int pkcs7_note_content(void *context, size_t hdrlen,
435 		       unsigned char tag,
436 		       const void *value, size_t vlen)
437 {
438 	struct pkcs7_parse_context *ctx = context;
439 
440 	if (ctx->last_oid != OID_data &&
441 	    ctx->last_oid != OID_msIndirectData) {
442 		pr_warn("Unsupported data type %d\n", ctx->last_oid);
443 		return -EINVAL;
444 	}
445 
446 	ctx->msg->data_type = ctx->last_oid;
447 	return 0;
448 }
449 
450 /*
451  * Extract the data from the message and store that and its content type OID in
452  * the context.
453  */
454 int pkcs7_note_data(void *context, size_t hdrlen,
455 		    unsigned char tag,
456 		    const void *value, size_t vlen)
457 {
458 	struct pkcs7_parse_context *ctx = context;
459 
460 	pr_debug("Got data\n");
461 
462 	ctx->msg->data = value;
463 	ctx->msg->data_len = vlen;
464 	ctx->msg->data_hdrlen = hdrlen;
465 	return 0;
466 }
467 
468 /*
469  * Parse authenticated attributes.
470  */
471 int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
472 				      unsigned char tag,
473 				      const void *value, size_t vlen)
474 {
475 	struct pkcs7_parse_context *ctx = context;
476 	struct pkcs7_signed_info *sinfo = ctx->sinfo;
477 	enum OID content_type;
478 
479 	pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
480 
481 	switch (ctx->last_oid) {
482 	case OID_contentType:
483 		if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
484 			goto repeated;
485 		content_type = look_up_OID(value, vlen);
486 		if (content_type != ctx->msg->data_type) {
487 			pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n",
488 				ctx->msg->data_type, sinfo->index,
489 				content_type);
490 			return -EBADMSG;
491 		}
492 		return 0;
493 
494 	case OID_signingTime:
495 		if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
496 			goto repeated;
497 		/* Should we check that the signing time is consistent
498 		 * with the signer's X.509 cert?
499 		 */
500 		return x509_decode_time(&sinfo->signing_time,
501 					hdrlen, tag, value, vlen);
502 
503 	case OID_messageDigest:
504 		if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
505 			goto repeated;
506 		if (tag != ASN1_OTS)
507 			return -EBADMSG;
508 		sinfo->msgdigest = value;
509 		sinfo->msgdigest_len = vlen;
510 		return 0;
511 
512 	case OID_smimeCapabilites:
513 		if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
514 			goto repeated;
515 		if (ctx->msg->data_type != OID_msIndirectData) {
516 			pr_warn("S/MIME Caps only allowed with Authenticode\n");
517 			return -EKEYREJECTED;
518 		}
519 		return 0;
520 
521 		/* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE
522 		 * char URLs and cont[1] 8-bit char URLs.
523 		 *
524 		 * Microsoft StatementType seems to contain a list of OIDs that
525 		 * are also used as extendedKeyUsage types in X.509 certs.
526 		 */
527 	case OID_msSpOpusInfo:
528 		if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
529 			goto repeated;
530 		goto authenticode_check;
531 	case OID_msStatementType:
532 		if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
533 			goto repeated;
534 	authenticode_check:
535 		if (ctx->msg->data_type != OID_msIndirectData) {
536 			pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n");
537 			return -EKEYREJECTED;
538 		}
539 		/* I'm not sure how to validate these */
540 		return 0;
541 	default:
542 		return 0;
543 	}
544 
545 repeated:
546 	/* We permit max one item per AuthenticatedAttribute and no repeats */
547 	pr_warn("Repeated/multivalue AuthAttrs not permitted\n");
548 	return -EKEYREJECTED;
549 }
550 
551 /*
552  * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3]
553  */
554 int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
555 				    unsigned char tag,
556 				    const void *value, size_t vlen)
557 {
558 	struct pkcs7_parse_context *ctx = context;
559 	struct pkcs7_signed_info *sinfo = ctx->sinfo;
560 
561 	if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) ||
562 	    !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) {
563 		pr_warn("Missing required AuthAttr\n");
564 		return -EBADMSG;
565 	}
566 
567 	if (ctx->msg->data_type != OID_msIndirectData &&
568 	    test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
569 		pr_warn("Unexpected Authenticode AuthAttr\n");
570 		return -EBADMSG;
571 	}
572 
573 	/* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
574 	sinfo->authattrs = value - (hdrlen - 1);
575 	sinfo->authattrs_len = vlen + (hdrlen - 1);
576 	return 0;
577 }
578 
579 /*
580  * Note the issuing certificate serial number
581  */
582 int pkcs7_sig_note_serial(void *context, size_t hdrlen,
583 			  unsigned char tag,
584 			  const void *value, size_t vlen)
585 {
586 	struct pkcs7_parse_context *ctx = context;
587 	ctx->raw_serial = value;
588 	ctx->raw_serial_size = vlen;
589 	return 0;
590 }
591 
592 /*
593  * Note the issuer's name
594  */
595 int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
596 			  unsigned char tag,
597 			  const void *value, size_t vlen)
598 {
599 	struct pkcs7_parse_context *ctx = context;
600 	ctx->raw_issuer = value;
601 	ctx->raw_issuer_size = vlen;
602 	return 0;
603 }
604 
605 /*
606  * Note the issuing cert's subjectKeyIdentifier
607  */
608 int pkcs7_sig_note_skid(void *context, size_t hdrlen,
609 			unsigned char tag,
610 			const void *value, size_t vlen)
611 {
612 	struct pkcs7_parse_context *ctx = context;
613 
614 	pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
615 
616 	ctx->raw_skid = value;
617 	ctx->raw_skid_size = vlen;
618 	return 0;
619 }
620 
621 /*
622  * Note the signature data
623  */
624 int pkcs7_sig_note_signature(void *context, size_t hdrlen,
625 			     unsigned char tag,
626 			     const void *value, size_t vlen)
627 {
628 	struct pkcs7_parse_context *ctx = context;
629 
630 	ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL);
631 	if (!ctx->sinfo->sig->s)
632 		return -ENOMEM;
633 
634 	ctx->sinfo->sig->s_size = vlen;
635 	return 0;
636 }
637 
638 /*
639  * Note a signature information block
640  */
641 int pkcs7_note_signed_info(void *context, size_t hdrlen,
642 			   unsigned char tag,
643 			   const void *value, size_t vlen)
644 {
645 	struct pkcs7_parse_context *ctx = context;
646 	struct pkcs7_signed_info *sinfo = ctx->sinfo;
647 	struct asymmetric_key_id *kid;
648 
649 	if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) {
650 		pr_warn("Authenticode requires AuthAttrs\n");
651 		return -EBADMSG;
652 	}
653 
654 	/* Generate cert issuer + serial number key ID */
655 	if (!ctx->expect_skid) {
656 		kid = asymmetric_key_generate_id(ctx->raw_serial,
657 						 ctx->raw_serial_size,
658 						 ctx->raw_issuer,
659 						 ctx->raw_issuer_size);
660 	} else {
661 		kid = asymmetric_key_generate_id(ctx->raw_skid,
662 						 ctx->raw_skid_size,
663 						 "", 0);
664 	}
665 	if (IS_ERR(kid))
666 		return PTR_ERR(kid);
667 
668 	pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data);
669 
670 	sinfo->sig->auth_ids[0] = kid;
671 	sinfo->index = ++ctx->sinfo_index;
672 	*ctx->ppsinfo = sinfo;
673 	ctx->ppsinfo = &sinfo->next;
674 	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
675 	if (!ctx->sinfo)
676 		return -ENOMEM;
677 	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
678 				  GFP_KERNEL);
679 	if (!ctx->sinfo->sig)
680 		return -ENOMEM;
681 	return 0;
682 }
683