mft.c revision 1.96 
1/*	$OpenBSD: mft.c,v 1.96 2023/06/29 10:28:25 tb Exp $ */
2/*
3 * Copyright (c) 2022 Theo Buehler <tb@openbsd.org>
4 * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#include <assert.h>
20#include <err.h>
21#include <limits.h>
22#include <stdint.h>
23#include <stdlib.h>
24#include <string.h>
25#include <unistd.h>
26
27#include <openssl/bn.h>
28#include <openssl/asn1.h>
29#include <openssl/asn1t.h>
30#include <openssl/safestack.h>
31#include <openssl/sha.h>
32#include <openssl/stack.h>
33#include <openssl/x509.h>
34
35#include "extern.h"
36
37/*
38 * Parse results and data of the manifest file.
39 */
40struct	parse {
41	const char	*fn; /* manifest file name */
42	struct mft	*res; /* result object */
43	int		 found_crl;
44};
45
46extern ASN1_OBJECT	*mft_oid;
47
48/*
49 * Types and templates for the Manifest eContent, RFC 6486, section 4.2.
50 */
51
52typedef struct {
53	ASN1_IA5STRING	*file;
54	ASN1_BIT_STRING	*hash;
55} FileAndHash;
56
57DECLARE_STACK_OF(FileAndHash);
58
59#ifndef DEFINE_STACK_OF
60#define sk_FileAndHash_num(sk)		SKM_sk_num(FileAndHash, (sk))
61#define sk_FileAndHash_value(sk, i)	SKM_sk_value(FileAndHash, (sk), (i))
62#endif
63
64typedef struct {
65	ASN1_INTEGER		*version;
66	ASN1_INTEGER		*manifestNumber;
67	ASN1_GENERALIZEDTIME	*thisUpdate;
68	ASN1_GENERALIZEDTIME	*nextUpdate;
69	ASN1_OBJECT		*fileHashAlg;
70	STACK_OF(FileAndHash)	*fileList;
71} Manifest;
72
73ASN1_SEQUENCE(FileAndHash) = {
74	ASN1_SIMPLE(FileAndHash, file, ASN1_IA5STRING),
75	ASN1_SIMPLE(FileAndHash, hash, ASN1_BIT_STRING),
76} ASN1_SEQUENCE_END(FileAndHash);
77
78ASN1_SEQUENCE(Manifest) = {
79	ASN1_EXP_OPT(Manifest, version, ASN1_INTEGER, 0),
80	ASN1_SIMPLE(Manifest, manifestNumber, ASN1_INTEGER),
81	ASN1_SIMPLE(Manifest, thisUpdate, ASN1_GENERALIZEDTIME),
82	ASN1_SIMPLE(Manifest, nextUpdate, ASN1_GENERALIZEDTIME),
83	ASN1_SIMPLE(Manifest, fileHashAlg, ASN1_OBJECT),
84	ASN1_SEQUENCE_OF(Manifest, fileList, FileAndHash),
85} ASN1_SEQUENCE_END(Manifest);
86
87DECLARE_ASN1_FUNCTIONS(Manifest);
88IMPLEMENT_ASN1_FUNCTIONS(Manifest);
89
90#define GENTIME_LENGTH 15
91
92/*
93 * Convert an ASN1_GENERALIZEDTIME to a struct tm.
94 * Returns 1 on success, 0 on failure.
95 */
96static int
97generalizedtime_to_tm(const ASN1_GENERALIZEDTIME *gtime, struct tm *tm)
98{
99	/*
100	 * ASN1_GENERALIZEDTIME is another name for ASN1_STRING. Check type and
101	 * length, so we don't accidentally accept a UTCTime. Punt on checking
102	 * Zulu time for OpenSSL: we don't want to mess about with silly flags.
103	 */
104	if (ASN1_STRING_type(gtime) != V_ASN1_GENERALIZEDTIME)
105		return 0;
106	if (ASN1_STRING_length(gtime) != GENTIME_LENGTH)
107		return 0;
108
109	memset(tm, 0, sizeof(*tm));
110	return ASN1_TIME_to_tm(gtime, tm);
111}
112
113/*
114 * Validate and verify the time validity of the mft.
115 * Returns 1 if all is good and for any other case 0.
116 */
117static int
118mft_parse_time(const ASN1_GENERALIZEDTIME *from,
119    const ASN1_GENERALIZEDTIME *until, struct parse *p)
120{
121	struct tm tm_from, tm_until;
122
123	if (!generalizedtime_to_tm(from, &tm_from)) {
124		warnx("%s: embedded from time format invalid", p->fn);
125		return 0;
126	}
127	if (!generalizedtime_to_tm(until, &tm_until)) {
128		warnx("%s: embedded until time format invalid", p->fn);
129		return 0;
130	}
131
132	if ((p->res->thisupdate = timegm(&tm_from)) == -1 ||
133	    (p->res->nextupdate = timegm(&tm_until)) == -1)
134		errx(1, "%s: timegm failed", p->fn);
135
136	if (p->res->thisupdate > p->res->nextupdate) {
137		warnx("%s: bad update interval", p->fn);
138		return 0;
139	}
140
141	return 1;
142}
143
144/*
145 * Determine rtype corresponding to file extension. Returns RTYPE_INVALID
146 * on error or unkown extension.
147 */
148enum rtype
149rtype_from_file_extension(const char *fn)
150{
151	size_t	 sz;
152
153	sz = strlen(fn);
154	if (sz < 5)
155		return RTYPE_INVALID;
156
157	if (strcasecmp(fn + sz - 4, ".tal") == 0)
158		return RTYPE_TAL;
159	if (strcasecmp(fn + sz - 4, ".cer") == 0)
160		return RTYPE_CER;
161	if (strcasecmp(fn + sz - 4, ".crl") == 0)
162		return RTYPE_CRL;
163	if (strcasecmp(fn + sz - 4, ".mft") == 0)
164		return RTYPE_MFT;
165	if (strcasecmp(fn + sz - 4, ".roa") == 0)
166		return RTYPE_ROA;
167	if (strcasecmp(fn + sz - 4, ".gbr") == 0)
168		return RTYPE_GBR;
169	if (strcasecmp(fn + sz - 4, ".sig") == 0)
170		return RTYPE_RSC;
171	if (strcasecmp(fn + sz - 4, ".asa") == 0)
172		return RTYPE_ASPA;
173	if (strcasecmp(fn + sz - 4, ".tak") == 0)
174		return RTYPE_TAK;
175	if (strcasecmp(fn + sz - 4, ".csv") == 0)
176		return RTYPE_GEOFEED;
177
178	return RTYPE_INVALID;
179}
180
181/*
182 * Validate that a filename listed on a Manifest only contains characters
183 * permitted in draft-ietf-sidrops-6486bis section 4.2.2
184 * Also ensure that there is exactly one '.'.
185 */
186static int
187valid_mft_filename(const char *fn, size_t len)
188{
189	const unsigned char *c;
190
191	if (!valid_filename(fn, len))
192		return 0;
193
194	c = memchr(fn, '.', len);
195	if (c == NULL || c != memrchr(fn, '.', len))
196		return 0;
197
198	return 1;
199}
200
201/*
202 * Check that the file is allowed to be part of a manifest and the parser
203 * for this type is implemented in rpki-client.
204 * Returns corresponding rtype or RTYPE_INVALID to mark the file as unknown.
205 */
206static enum rtype
207rtype_from_mftfile(const char *fn)
208{
209	enum rtype		 type;
210
211	type = rtype_from_file_extension(fn);
212	switch (type) {
213	case RTYPE_CER:
214	case RTYPE_CRL:
215	case RTYPE_GBR:
216	case RTYPE_ROA:
217	case RTYPE_ASPA:
218	case RTYPE_TAK:
219		return type;
220	default:
221		return RTYPE_INVALID;
222	}
223}
224
225/*
226 * Parse an individual "FileAndHash", RFC 6486, sec. 4.2.
227 * Return zero on failure, non-zero on success.
228 */
229static int
230mft_parse_filehash(struct parse *p, const FileAndHash *fh)
231{
232	char			*fn = NULL;
233	int			 rc = 0;
234	struct mftfile		*fent;
235	enum rtype		 type;
236
237	if (!valid_mft_filename(fh->file->data, fh->file->length)) {
238		warnx("%s: RFC 6486 section 4.2.2: bad filename", p->fn);
239		goto out;
240	}
241	fn = strndup(fh->file->data, fh->file->length);
242	if (fn == NULL)
243		err(1, NULL);
244
245	if (fh->hash->length != SHA256_DIGEST_LENGTH) {
246		warnx("%s: RFC 6486 section 4.2.1: hash: "
247		    "invalid SHA256 length, have %d",
248		    p->fn, fh->hash->length);
249		goto out;
250	}
251
252	type = rtype_from_mftfile(fn);
253	/* remember the filehash for the CRL in struct mft */
254	if (type == RTYPE_CRL && strcmp(fn, p->res->crl) == 0) {
255		memcpy(p->res->crlhash, fh->hash->data, SHA256_DIGEST_LENGTH);
256		p->found_crl = 1;
257	}
258
259	/* Insert the filename and hash value. */
260	fent = &p->res->files[p->res->filesz++];
261	fent->type = type;
262	fent->file = fn;
263	fn = NULL;
264	memcpy(fent->hash, fh->hash->data, SHA256_DIGEST_LENGTH);
265
266	rc = 1;
267 out:
268	free(fn);
269	return rc;
270}
271
272/*
273 * Handle the eContent of the manifest object, RFC 6486 sec. 4.2.
274 * Returns 0 on failure and 1 on success.
275 */
276static int
277mft_parse_econtent(const unsigned char *d, size_t dsz, struct parse *p)
278{
279	Manifest		*mft;
280	FileAndHash		*fh;
281	int			 i, rc = 0;
282
283	if ((mft = d2i_Manifest(NULL, &d, dsz)) == NULL) {
284		warnx("%s: RFC 6486 section 4: failed to parse Manifest",
285		    p->fn);
286		goto out;
287	}
288
289	if (!valid_econtent_version(p->fn, mft->version, 0))
290		goto out;
291
292	p->res->seqnum = x509_convert_seqnum(p->fn, mft->manifestNumber);
293	if (p->res->seqnum == NULL)
294		goto out;
295
296	/*
297	 * Timestamps: this and next update time.
298	 * Validate that the current date falls into this interval.
299	 * This is required by section 4.4, (3).
300	 * If we're after the given date, then the MFT is stale.
301	 * This is made super complicated because it uses OpenSSL's
302	 * ASN1_GENERALIZEDTIME instead of ASN1_TIME, which we could
303	 * compare against the current time trivially.
304	 */
305
306	if (!mft_parse_time(mft->thisUpdate, mft->nextUpdate, p))
307		goto out;
308
309	if (OBJ_obj2nid(mft->fileHashAlg) != NID_sha256) {
310		warnx("%s: RFC 6486 section 4.2.1: fileHashAlg: "
311		    "want SHA256 object, have %s (NID %d)", p->fn,
312		    ASN1_tag2str(OBJ_obj2nid(mft->fileHashAlg)),
313		    OBJ_obj2nid(mft->fileHashAlg));
314		goto out;
315	}
316
317	if (sk_FileAndHash_num(mft->fileList) >= MAX_MANIFEST_ENTRIES) {
318		warnx("%s: %d exceeds manifest entry limit (%d)", p->fn,
319		    sk_FileAndHash_num(mft->fileList), MAX_MANIFEST_ENTRIES);
320		goto out;
321	}
322
323	p->res->files = calloc(sk_FileAndHash_num(mft->fileList),
324	    sizeof(struct mftfile));
325	if (p->res->files == NULL)
326		err(1, NULL);
327
328	for (i = 0; i < sk_FileAndHash_num(mft->fileList); i++) {
329		fh = sk_FileAndHash_value(mft->fileList, i);
330		if (!mft_parse_filehash(p, fh))
331			goto out;
332	}
333
334	if (!p->found_crl) {
335		warnx("%s: CRL not part of MFT fileList", p->fn);
336		goto out;
337	}
338
339	rc = 1;
340 out:
341	Manifest_free(mft);
342	return rc;
343}
344
345/*
346 * Parse the objects that have been published in the manifest.
347 * This conforms to RFC 6486.
348 * Note that if the MFT is stale, all referenced objects are stripped
349 * from the parsed content.
350 * The MFT content is otherwise returned.
351 */
352struct mft *
353mft_parse(X509 **x509, const char *fn, const unsigned char *der, size_t len)
354{
355	struct parse	 p;
356	struct cert	*cert = NULL;
357	int		 rc = 0;
358	size_t		 cmsz;
359	unsigned char	*cms;
360	char		*crldp = NULL, *crlfile;
361	time_t		 signtime = 0;
362
363	memset(&p, 0, sizeof(struct parse));
364	p.fn = fn;
365
366	cms = cms_parse_validate(x509, fn, der, len, mft_oid, &cmsz, &signtime);
367	if (cms == NULL)
368		return NULL;
369	assert(*x509 != NULL);
370
371	if ((p.res = calloc(1, sizeof(struct mft))) == NULL)
372		err(1, NULL);
373	p.res->signtime = signtime;
374
375	if (!x509_get_aia(*x509, fn, &p.res->aia))
376		goto out;
377	if (!x509_get_aki(*x509, fn, &p.res->aki))
378		goto out;
379	if (!x509_get_sia(*x509, fn, &p.res->sia))
380		goto out;
381	if (!x509_get_ski(*x509, fn, &p.res->ski))
382		goto out;
383	if (p.res->aia == NULL || p.res->aki == NULL || p.res->sia == NULL ||
384	    p.res->ski == NULL) {
385		warnx("%s: RFC 6487 section 4.8: "
386		    "missing AIA, AKI, SIA, or SKI X509 extension", fn);
387		goto out;
388	}
389
390	if (!x509_inherits(*x509)) {
391		warnx("%s: RFC 3779 extension not set to inherit", fn);
392		goto out;
393	}
394
395	/* get CRL info for later */
396	if (!x509_get_crl(*x509, fn, &crldp))
397		goto out;
398	if (crldp == NULL) {
399		warnx("%s: RFC 6487 section 4.8.6: CRL: "
400		    "missing CRL distribution point extension", fn);
401		goto out;
402	}
403	crlfile = strrchr(crldp, '/');
404	if (crlfile == NULL) {
405		warnx("%s: RFC 6487 section 4.8.6: "
406		    "invalid CRL distribution point", fn);
407		goto out;
408	}
409	crlfile++;
410	if (!valid_mft_filename(crlfile, strlen(crlfile)) ||
411	    rtype_from_file_extension(crlfile) != RTYPE_CRL) {
412		warnx("%s: RFC 6487 section 4.8.6: CRL: "
413		    "bad CRL distribution point extension", fn);
414		goto out;
415	}
416	if ((p.res->crl = strdup(crlfile)) == NULL)
417		err(1, NULL);
418
419	if (mft_parse_econtent(cms, cmsz, &p) == 0)
420		goto out;
421
422	if ((cert = cert_parse_ee_cert(fn, *x509)) == NULL)
423		goto out;
424
425	if (p.res->signtime > p.res->nextupdate) {
426		warnx("%s: dating issue: CMS signing-time after MFT nextUpdate",
427		    fn);
428		goto out;
429	}
430
431	rc = 1;
432out:
433	if (rc == 0) {
434		mft_free(p.res);
435		p.res = NULL;
436		X509_free(*x509);
437		*x509 = NULL;
438	}
439	free(crldp);
440	cert_free(cert);
441	free(cms);
442	return p.res;
443}
444
445/*
446 * Free an MFT pointer.
447 * Safe to call with NULL.
448 */
449void
450mft_free(struct mft *p)
451{
452	size_t	 i;
453
454	if (p == NULL)
455		return;
456
457	if (p->files != NULL)
458		for (i = 0; i < p->filesz; i++)
459			free(p->files[i].file);
460
461	free(p->aia);
462	free(p->aki);
463	free(p->sia);
464	free(p->ski);
465	free(p->path);
466	free(p->files);
467	free(p->seqnum);
468	free(p);
469}
470
471/*
472 * Serialise MFT parsed content into the given buffer.
473 * See mft_read() for the other side of the pipe.
474 */
475void
476mft_buffer(struct ibuf *b, const struct mft *p)
477{
478	size_t		 i;
479
480	io_simple_buffer(b, &p->stale, sizeof(p->stale));
481	io_simple_buffer(b, &p->repoid, sizeof(p->repoid));
482	io_simple_buffer(b, &p->talid, sizeof(p->talid));
483	io_str_buffer(b, p->path);
484
485	io_str_buffer(b, p->aia);
486	io_str_buffer(b, p->aki);
487	io_str_buffer(b, p->ski);
488
489	io_simple_buffer(b, &p->filesz, sizeof(size_t));
490	for (i = 0; i < p->filesz; i++) {
491		io_str_buffer(b, p->files[i].file);
492		io_simple_buffer(b, &p->files[i].type,
493		    sizeof(p->files[i].type));
494		io_simple_buffer(b, &p->files[i].location,
495		    sizeof(p->files[i].location));
496		io_simple_buffer(b, p->files[i].hash, SHA256_DIGEST_LENGTH);
497	}
498}
499
500/*
501 * Read an MFT structure from the file descriptor.
502 * Result must be passed to mft_free().
503 */
504struct mft *
505mft_read(struct ibuf *b)
506{
507	struct mft	*p = NULL;
508	size_t		 i;
509
510	if ((p = calloc(1, sizeof(struct mft))) == NULL)
511		err(1, NULL);
512
513	io_read_buf(b, &p->stale, sizeof(p->stale));
514	io_read_buf(b, &p->repoid, sizeof(p->repoid));
515	io_read_buf(b, &p->talid, sizeof(p->talid));
516	io_read_str(b, &p->path);
517
518	io_read_str(b, &p->aia);
519	io_read_str(b, &p->aki);
520	io_read_str(b, &p->ski);
521	assert(p->aia && p->aki && p->ski);
522
523	io_read_buf(b, &p->filesz, sizeof(size_t));
524	if ((p->files = calloc(p->filesz, sizeof(struct mftfile))) == NULL)
525		err(1, NULL);
526
527	for (i = 0; i < p->filesz; i++) {
528		io_read_str(b, &p->files[i].file);
529		io_read_buf(b, &p->files[i].type, sizeof(p->files[i].type));
530		io_read_buf(b, &p->files[i].location,
531		    sizeof(p->files[i].location));
532		io_read_buf(b, p->files[i].hash, SHA256_DIGEST_LENGTH);
533	}
534
535	return p;
536}
537
538/*
539 * Compare two MFT files, returns 1 if first MFT is preferred and 0 if second
540 * MFT should be used.
541 */
542int
543mft_compare(const struct mft *a, const struct mft *b)
544{
545	int r;
546
547	if (b == NULL)
548		return 1;
549	if (a == NULL)
550		return 0;
551
552	r = strlen(a->seqnum) - strlen(b->seqnum);
553	if (r > 0)	/* seqnum in a is longer -> higher */
554		return 1;
555	if (r < 0)	/* seqnum in a is shorter -> smaller */
556		return 0;
557
558	r = strcmp(a->seqnum, b->seqnum);
559	if (r > 0)	/* a is greater, prefer a */
560		return 1;
561	return 0;
562}
563