1 /* PKCS#7 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) "PKCS7: "fmt
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/export.h>
16 #include <linux/slab.h>
17 #include <linux/err.h>
18 #include <linux/oid_registry.h>
19 #include <crypto/public_key.h>
20 #include "pkcs7_parser.h"
21 #include "pkcs7.asn1.h"
22 
23 MODULE_DESCRIPTION("PKCS#7 parser");
24 MODULE_AUTHOR("Red Hat, Inc.");
25 MODULE_LICENSE("GPL");
26 
27 struct pkcs7_parse_context {
28 	struct pkcs7_message	*msg;		/* Message being constructed */
29 	struct pkcs7_signed_info *sinfo;	/* SignedInfo being constructed */
30 	struct pkcs7_signed_info **ppsinfo;
31 	struct x509_certificate *certs;		/* Certificate cache */
32 	struct x509_certificate **ppcerts;
33 	unsigned long	data;			/* Start of data */
34 	enum OID	last_oid;		/* Last OID encountered */
35 	unsigned	x509_index;
36 	unsigned	sinfo_index;
37 	const void	*raw_serial;
38 	unsigned	raw_serial_size;
39 	unsigned	raw_issuer_size;
40 	const void	*raw_issuer;
41 	const void	*raw_skid;
42 	unsigned	raw_skid_size;
43 	bool		expect_skid;
44 };
45 
46 /*
47  * Free a signed information block.
48  */
49 static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
50 {
51 	if (sinfo) {
52 		public_key_signature_free(sinfo->sig);
53 		kfree(sinfo);
54 	}
55 }
56 
57 /**
58  * pkcs7_free_message - Free a PKCS#7 message
59  * @pkcs7: The PKCS#7 message to free
60  */
61 void pkcs7_free_message(struct pkcs7_message *pkcs7)
62 {
63 	struct x509_certificate *cert;
64 	struct pkcs7_signed_info *sinfo;
65 
66 	if (pkcs7) {
67 		while (pkcs7->certs) {
68 			cert = pkcs7->certs;
69 			pkcs7->certs = cert->next;
70 			x509_free_certificate(cert);
71 		}
72 		while (pkcs7->crl) {
73 			cert = pkcs7->crl;
74 			pkcs7->crl = cert->next;
75 			x509_free_certificate(cert);
76 		}
77 		while (pkcs7->signed_infos) {
78 			sinfo = pkcs7->signed_infos;
79 			pkcs7->signed_infos = sinfo->next;
80 			pkcs7_free_signed_info(sinfo);
81 		}
82 		kfree(pkcs7);
83 	}
84 }
85 EXPORT_SYMBOL_GPL(pkcs7_free_message);
86 
87 /*
88  * Check authenticatedAttributes are provided or not provided consistently.
89  */
90 static int pkcs7_check_authattrs(struct pkcs7_message *msg)
91 {
92 	struct pkcs7_signed_info *sinfo;
93 	bool want = false;
94 
95 	sinfo = msg->signed_infos;
96 	if (!sinfo)
97 		goto inconsistent;
98 
99 	if (sinfo->authattrs) {
100 		want = true;
101 		msg->have_authattrs = true;
102 	}
103 
104 	for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next)
105 		if (!!sinfo->authattrs != want)
106 			goto inconsistent;
107 	return 0;
108 
109 inconsistent:
110 	pr_warn("Inconsistently supplied authAttrs\n");
111 	return -EINVAL;
112 }
113 
114 /**
115  * pkcs7_parse_message - Parse a PKCS#7 message
116  * @data: The raw binary ASN.1 encoded message to be parsed
117  * @datalen: The size of the encoded message
118  */
119 struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
120 {
121 	struct pkcs7_parse_context *ctx;
122 	struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
123 	int ret;
124 
125 	ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
126 	if (!ctx)
127 		goto out_no_ctx;
128 	ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
129 	if (!ctx->msg)
130 		goto out_no_msg;
131 	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
132 	if (!ctx->sinfo)
133 		goto out_no_sinfo;
134 	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
135 				  GFP_KERNEL);
136 	if (!ctx->sinfo->sig)
137 		goto out_no_sig;
138 
139 	ctx->data = (unsigned long)data;
140 	ctx->ppcerts = &ctx->certs;
141 	ctx->ppsinfo = &ctx->msg->signed_infos;
142 
143 	/* Attempt to decode the signature */
144 	ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
145 	if (ret < 0) {
146 		msg = ERR_PTR(ret);
147 		goto out;
148 	}
149 
150 	ret = pkcs7_check_authattrs(ctx->msg);
151 	if (ret < 0) {
152 		msg = ERR_PTR(ret);
153 		goto out;
154 	}
155 
156 	msg = ctx->msg;
157 	ctx->msg = NULL;
158 
159 out:
160 	while (ctx->certs) {
161 		struct x509_certificate *cert = ctx->certs;
162 		ctx->certs = cert->next;
163 		x509_free_certificate(cert);
164 	}
165 out_no_sig:
166 	pkcs7_free_signed_info(ctx->sinfo);
167 out_no_sinfo:
168 	pkcs7_free_message(ctx->msg);
169 out_no_msg:
170 	kfree(ctx);
171 out_no_ctx:
172 	return msg;
173 }
174 EXPORT_SYMBOL_GPL(pkcs7_parse_message);
175 
176 /**
177  * pkcs7_get_content_data - Get access to the PKCS#7 content
178  * @pkcs7: The preparsed PKCS#7 message to access
179  * @_data: Place to return a pointer to the data
180  * @_data_len: Place to return the data length
181  * @_headerlen: Size of ASN.1 header not included in _data
182  *
183  * Get access to the data content of the PKCS#7 message.  The size of the
184  * header of the ASN.1 object that contains it is also provided and can be used
185  * to adjust *_data and *_data_len to get the entire object.
186  *
187  * Returns -ENODATA if the data object was missing from the message.
188  */
189 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
190 			   const void **_data, size_t *_data_len,
191 			   size_t *_headerlen)
192 {
193 	if (!pkcs7->data)
194 		return -ENODATA;
195 
196 	*_data = pkcs7->data;
197 	*_data_len = pkcs7->data_len;
198 	if (_headerlen)
199 		*_headerlen = pkcs7->data_hdrlen;
200 	return 0;
201 }
202 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
203 
204 /*
205  * Note an OID when we find one for later processing when we know how
206  * to interpret it.
207  */
208 int pkcs7_note_OID(void *context, size_t hdrlen,
209 		   unsigned char tag,
210 		   const void *value, size_t vlen)
211 {
212 	struct pkcs7_parse_context *ctx = context;
213 
214 	ctx->last_oid = look_up_OID(value, vlen);
215 	if (ctx->last_oid == OID__NR) {
216 		char buffer[50];
217 		sprint_oid(value, vlen, buffer, sizeof(buffer));
218 		printk("PKCS7: Unknown OID: [%lu] %s\n",
219 		       (unsigned long)value - ctx->data, buffer);
220 	}
221 	return 0;
222 }
223 
224 /*
225  * Note the digest algorithm for the signature.
226  */
227 int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
228 			       unsigned char tag,
229 			       const void *value, size_t vlen)
230 {
231 	struct pkcs7_parse_context *ctx = context;
232 
233 	switch (ctx->last_oid) {
234 	case OID_md4:
235 		ctx->sinfo->sig->hash_algo = "md4";
236 		break;
237 	case OID_md5:
238 		ctx->sinfo->sig->hash_algo = "md5";
239 		break;
240 	case OID_sha1:
241 		ctx->sinfo->sig->hash_algo = "sha1";
242 		break;
243 	case OID_sha256:
244 		ctx->sinfo->sig->hash_algo = "sha256";
245 		break;
246 	case OID_sha384:
247 		ctx->sinfo->sig->hash_algo = "sha384";
248 		break;
249 	case OID_sha512:
250 		ctx->sinfo->sig->hash_algo = "sha512";
251 		break;
252 	case OID_sha224:
253 		ctx->sinfo->sig->hash_algo = "sha224";
254 		break;
255 	default:
256 		printk("Unsupported digest algo: %u\n", ctx->last_oid);
257 		return -ENOPKG;
258 	}
259 	return 0;
260 }
261 
262 /*
263  * Note the public key algorithm for the signature.
264  */
265 int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
266 			     unsigned char tag,
267 			     const void *value, size_t vlen)
268 {
269 	struct pkcs7_parse_context *ctx = context;
270 
271 	switch (ctx->last_oid) {
272 	case OID_rsaEncryption:
273 		ctx->sinfo->sig->pkey_algo = "rsa";
274 		ctx->sinfo->sig->encoding = "pkcs1";
275 		break;
276 	default:
277 		printk("Unsupported pkey algo: %u\n", ctx->last_oid);
278 		return -ENOPKG;
279 	}
280 	return 0;
281 }
282 
283 /*
284  * We only support signed data [RFC2315 sec 9].
285  */
286 int pkcs7_check_content_type(void *context, size_t hdrlen,
287 			     unsigned char tag,
288 			     const void *value, size_t vlen)
289 {
290 	struct pkcs7_parse_context *ctx = context;
291 
292 	if (ctx->last_oid != OID_signed_data) {
293 		pr_warn("Only support pkcs7_signedData type\n");
294 		return -EINVAL;
295 	}
296 
297 	return 0;
298 }
299 
300 /*
301  * Note the SignedData version
302  */
303 int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
304 				  unsigned char tag,
305 				  const void *value, size_t vlen)
306 {
307 	struct pkcs7_parse_context *ctx = context;
308 	unsigned version;
309 
310 	if (vlen != 1)
311 		goto unsupported;
312 
313 	ctx->msg->version = version = *(const u8 *)value;
314 	switch (version) {
315 	case 1:
316 		/* PKCS#7 SignedData [RFC2315 sec 9.1]
317 		 * CMS ver 1 SignedData [RFC5652 sec 5.1]
318 		 */
319 		break;
320 	case 3:
321 		/* CMS ver 3 SignedData [RFC2315 sec 5.1] */
322 		break;
323 	default:
324 		goto unsupported;
325 	}
326 
327 	return 0;
328 
329 unsupported:
330 	pr_warn("Unsupported SignedData version\n");
331 	return -EINVAL;
332 }
333 
334 /*
335  * Note the SignerInfo version
336  */
337 int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
338 				  unsigned char tag,
339 				  const void *value, size_t vlen)
340 {
341 	struct pkcs7_parse_context *ctx = context;
342 	unsigned version;
343 
344 	if (vlen != 1)
345 		goto unsupported;
346 
347 	version = *(const u8 *)value;
348 	switch (version) {
349 	case 1:
350 		/* PKCS#7 SignerInfo [RFC2315 sec 9.2]
351 		 * CMS ver 1 SignerInfo [RFC5652 sec 5.3]
352 		 */
353 		if (ctx->msg->version != 1)
354 			goto version_mismatch;
355 		ctx->expect_skid = false;
356 		break;
357 	case 3:
358 		/* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */
359 		if (ctx->msg->version == 1)
360 			goto version_mismatch;
361 		ctx->expect_skid = true;
362 		break;
363 	default:
364 		goto unsupported;
365 	}
366 
367 	return 0;
368 
369 unsupported:
370 	pr_warn("Unsupported SignerInfo version\n");
371 	return -EINVAL;
372 version_mismatch:
373 	pr_warn("SignedData-SignerInfo version mismatch\n");
374 	return -EBADMSG;
375 }
376 
377 /*
378  * Extract a certificate and store it in the context.
379  */
380 int pkcs7_extract_cert(void *context, size_t hdrlen,
381 		       unsigned char tag,
382 		       const void *value, size_t vlen)
383 {
384 	struct pkcs7_parse_context *ctx = context;
385 	struct x509_certificate *x509;
386 
387 	if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
388 		pr_debug("Cert began with tag %02x at %lu\n",
389 			 tag, (unsigned long)ctx - ctx->data);
390 		return -EBADMSG;
391 	}
392 
393 	/* We have to correct for the header so that the X.509 parser can start
394 	 * from the beginning.  Note that since X.509 stipulates DER, there
395 	 * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
396 	 * stipulates BER).
397 	 */
398 	value -= hdrlen;
399 	vlen += hdrlen;
400 
401 	if (((u8*)value)[1] == 0x80)
402 		vlen += 2; /* Indefinite length - there should be an EOC */
403 
404 	x509 = x509_cert_parse(value, vlen);
405 	if (IS_ERR(x509))
406 		return PTR_ERR(x509);
407 
408 	x509->index = ++ctx->x509_index;
409 	pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
410 	pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
411 
412 	*ctx->ppcerts = x509;
413 	ctx->ppcerts = &x509->next;
414 	return 0;
415 }
416 
417 /*
418  * Save the certificate list
419  */
420 int pkcs7_note_certificate_list(void *context, size_t hdrlen,
421 				unsigned char tag,
422 				const void *value, size_t vlen)
423 {
424 	struct pkcs7_parse_context *ctx = context;
425 
426 	pr_devel("Got cert list (%02x)\n", tag);
427 
428 	*ctx->ppcerts = ctx->msg->certs;
429 	ctx->msg->certs = ctx->certs;
430 	ctx->certs = NULL;
431 	ctx->ppcerts = &ctx->certs;
432 	return 0;
433 }
434 
435 /*
436  * Note the content type.
437  */
438 int pkcs7_note_content(void *context, size_t hdrlen,
439 		       unsigned char tag,
440 		       const void *value, size_t vlen)
441 {
442 	struct pkcs7_parse_context *ctx = context;
443 
444 	if (ctx->last_oid != OID_data &&
445 	    ctx->last_oid != OID_msIndirectData) {
446 		pr_warn("Unsupported data type %d\n", ctx->last_oid);
447 		return -EINVAL;
448 	}
449 
450 	ctx->msg->data_type = ctx->last_oid;
451 	return 0;
452 }
453 
454 /*
455  * Extract the data from the message and store that and its content type OID in
456  * the context.
457  */
458 int pkcs7_note_data(void *context, size_t hdrlen,
459 		    unsigned char tag,
460 		    const void *value, size_t vlen)
461 {
462 	struct pkcs7_parse_context *ctx = context;
463 
464 	pr_debug("Got data\n");
465 
466 	ctx->msg->data = value;
467 	ctx->msg->data_len = vlen;
468 	ctx->msg->data_hdrlen = hdrlen;
469 	return 0;
470 }
471 
472 /*
473  * Parse authenticated attributes.
474  */
475 int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
476 				      unsigned char tag,
477 				      const void *value, size_t vlen)
478 {
479 	struct pkcs7_parse_context *ctx = context;
480 	struct pkcs7_signed_info *sinfo = ctx->sinfo;
481 	enum OID content_type;
482 
483 	pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
484 
485 	switch (ctx->last_oid) {
486 	case OID_contentType:
487 		if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
488 			goto repeated;
489 		content_type = look_up_OID(value, vlen);
490 		if (content_type != ctx->msg->data_type) {
491 			pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n",
492 				ctx->msg->data_type, sinfo->index,
493 				content_type);
494 			return -EBADMSG;
495 		}
496 		return 0;
497 
498 	case OID_signingTime:
499 		if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
500 			goto repeated;
501 		/* Should we check that the signing time is consistent
502 		 * with the signer's X.509 cert?
503 		 */
504 		return x509_decode_time(&sinfo->signing_time,
505 					hdrlen, tag, value, vlen);
506 
507 	case OID_messageDigest:
508 		if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
509 			goto repeated;
510 		if (tag != ASN1_OTS)
511 			return -EBADMSG;
512 		sinfo->msgdigest = value;
513 		sinfo->msgdigest_len = vlen;
514 		return 0;
515 
516 	case OID_smimeCapabilites:
517 		if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
518 			goto repeated;
519 		if (ctx->msg->data_type != OID_msIndirectData) {
520 			pr_warn("S/MIME Caps only allowed with Authenticode\n");
521 			return -EKEYREJECTED;
522 		}
523 		return 0;
524 
525 		/* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE
526 		 * char URLs and cont[1] 8-bit char URLs.
527 		 *
528 		 * Microsoft StatementType seems to contain a list of OIDs that
529 		 * are also used as extendedKeyUsage types in X.509 certs.
530 		 */
531 	case OID_msSpOpusInfo:
532 		if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
533 			goto repeated;
534 		goto authenticode_check;
535 	case OID_msStatementType:
536 		if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
537 			goto repeated;
538 	authenticode_check:
539 		if (ctx->msg->data_type != OID_msIndirectData) {
540 			pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n");
541 			return -EKEYREJECTED;
542 		}
543 		/* I'm not sure how to validate these */
544 		return 0;
545 	default:
546 		return 0;
547 	}
548 
549 repeated:
550 	/* We permit max one item per AuthenticatedAttribute and no repeats */
551 	pr_warn("Repeated/multivalue AuthAttrs not permitted\n");
552 	return -EKEYREJECTED;
553 }
554 
555 /*
556  * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3]
557  */
558 int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
559 				    unsigned char tag,
560 				    const void *value, size_t vlen)
561 {
562 	struct pkcs7_parse_context *ctx = context;
563 	struct pkcs7_signed_info *sinfo = ctx->sinfo;
564 
565 	if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) ||
566 	    !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) {
567 		pr_warn("Missing required AuthAttr\n");
568 		return -EBADMSG;
569 	}
570 
571 	if (ctx->msg->data_type != OID_msIndirectData &&
572 	    test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
573 		pr_warn("Unexpected Authenticode AuthAttr\n");
574 		return -EBADMSG;
575 	}
576 
577 	/* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
578 	sinfo->authattrs = value - (hdrlen - 1);
579 	sinfo->authattrs_len = vlen + (hdrlen - 1);
580 	return 0;
581 }
582 
583 /*
584  * Note the issuing certificate serial number
585  */
586 int pkcs7_sig_note_serial(void *context, size_t hdrlen,
587 			  unsigned char tag,
588 			  const void *value, size_t vlen)
589 {
590 	struct pkcs7_parse_context *ctx = context;
591 	ctx->raw_serial = value;
592 	ctx->raw_serial_size = vlen;
593 	return 0;
594 }
595 
596 /*
597  * Note the issuer's name
598  */
599 int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
600 			  unsigned char tag,
601 			  const void *value, size_t vlen)
602 {
603 	struct pkcs7_parse_context *ctx = context;
604 	ctx->raw_issuer = value;
605 	ctx->raw_issuer_size = vlen;
606 	return 0;
607 }
608 
609 /*
610  * Note the issuing cert's subjectKeyIdentifier
611  */
612 int pkcs7_sig_note_skid(void *context, size_t hdrlen,
613 			unsigned char tag,
614 			const void *value, size_t vlen)
615 {
616 	struct pkcs7_parse_context *ctx = context;
617 
618 	pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
619 
620 	ctx->raw_skid = value;
621 	ctx->raw_skid_size = vlen;
622 	return 0;
623 }
624 
625 /*
626  * Note the signature data
627  */
628 int pkcs7_sig_note_signature(void *context, size_t hdrlen,
629 			     unsigned char tag,
630 			     const void *value, size_t vlen)
631 {
632 	struct pkcs7_parse_context *ctx = context;
633 
634 	ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL);
635 	if (!ctx->sinfo->sig->s)
636 		return -ENOMEM;
637 
638 	ctx->sinfo->sig->s_size = vlen;
639 	return 0;
640 }
641 
642 /*
643  * Note a signature information block
644  */
645 int pkcs7_note_signed_info(void *context, size_t hdrlen,
646 			   unsigned char tag,
647 			   const void *value, size_t vlen)
648 {
649 	struct pkcs7_parse_context *ctx = context;
650 	struct pkcs7_signed_info *sinfo = ctx->sinfo;
651 	struct asymmetric_key_id *kid;
652 
653 	if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) {
654 		pr_warn("Authenticode requires AuthAttrs\n");
655 		return -EBADMSG;
656 	}
657 
658 	/* Generate cert issuer + serial number key ID */
659 	if (!ctx->expect_skid) {
660 		kid = asymmetric_key_generate_id(ctx->raw_serial,
661 						 ctx->raw_serial_size,
662 						 ctx->raw_issuer,
663 						 ctx->raw_issuer_size);
664 	} else {
665 		kid = asymmetric_key_generate_id(ctx->raw_skid,
666 						 ctx->raw_skid_size,
667 						 "", 0);
668 	}
669 	if (IS_ERR(kid))
670 		return PTR_ERR(kid);
671 
672 	pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data);
673 
674 	sinfo->sig->auth_ids[0] = kid;
675 	sinfo->index = ++ctx->sinfo_index;
676 	*ctx->ppsinfo = sinfo;
677 	ctx->ppsinfo = &sinfo->next;
678 	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
679 	if (!ctx->sinfo)
680 		return -ENOMEM;
681 	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
682 				  GFP_KERNEL);
683 	if (!ctx->sinfo->sig)
684 		return -ENOMEM;
685 	return 0;
686 }
687