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