2 * Copyright 2003-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 #include "internal/cryptlib.h"
11 #include "internal/numbers.h"
13 #include "crypto/asn1.h"
14 #include <openssl/asn1t.h>
15 #include <openssl/conf.h>
16 #include <openssl/x509v3.h>
17 #include <openssl/bn.h>
19 #include "crypto/x509.h"
22 static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
24 STACK_OF(CONF_VALUE) *nval);
25 static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,
27 static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
28 STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp,
29 int ind, const char *name);
30 static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip);
32 static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc);
33 static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen);
34 static int nc_dn(X509_NAME *sub, X509_NAME *nm);
35 static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns);
36 static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml);
37 static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base);
38 static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base);
40 const X509V3_EXT_METHOD v3_name_constraints = {
41 NID_name_constraints, 0,
42 ASN1_ITEM_ref(NAME_CONSTRAINTS),
45 0, v2i_NAME_CONSTRAINTS,
46 i2r_NAME_CONSTRAINTS, 0,
50 ASN1_SEQUENCE(GENERAL_SUBTREE) = {
51 ASN1_SIMPLE(GENERAL_SUBTREE, base, GENERAL_NAME),
52 ASN1_IMP_OPT(GENERAL_SUBTREE, minimum, ASN1_INTEGER, 0),
53 ASN1_IMP_OPT(GENERAL_SUBTREE, maximum, ASN1_INTEGER, 1)
54 } ASN1_SEQUENCE_END(GENERAL_SUBTREE)
56 ASN1_SEQUENCE(NAME_CONSTRAINTS) = {
57 ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, permittedSubtrees,
59 ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, excludedSubtrees,
61 } ASN1_SEQUENCE_END(NAME_CONSTRAINTS)
64 IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE)
65 IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS)
68 * We cannot use strncasecmp here because that applies locale specific rules.
69 * For example in Turkish 'I' is not the uppercase character for 'i'. We need to
70 * do a simple ASCII case comparison ignoring the locale (that is why we use
71 * numeric constants below).
73 static int ia5ncasecmp(const char *s1, const char *s2, size_t n)
75 for (; n > 0; n--, s1++, s2++) {
77 unsigned char c1 = (unsigned char)*s1, c2 = (unsigned char)*s2;
79 /* Convert to lower case */
80 if (c1 >= 0x41 /* A */ && c1 <= 0x5A /* Z */)
82 if (c2 >= 0x41 /* A */ && c2 <= 0x5A /* Z */)
93 } else if (*s1 == 0) {
94 /* If we get here we know that *s2 == 0 too */
102 static int ia5casecmp(const char *s1, const char *s2)
104 return ia5ncasecmp(s1, s2, SIZE_MAX);
107 static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
108 X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval)
111 CONF_VALUE tval, *val;
112 STACK_OF(GENERAL_SUBTREE) **ptree = NULL;
113 NAME_CONSTRAINTS *ncons = NULL;
114 GENERAL_SUBTREE *sub = NULL;
116 ncons = NAME_CONSTRAINTS_new();
119 for (i = 0; i < sk_CONF_VALUE_num(nval); i++) {
120 val = sk_CONF_VALUE_value(nval, i);
121 if (strncmp(val->name, "permitted", 9) == 0 && val->name[9]) {
122 ptree = &ncons->permittedSubtrees;
123 tval.name = val->name + 10;
124 } else if (strncmp(val->name, "excluded", 8) == 0 && val->name[8]) {
125 ptree = &ncons->excludedSubtrees;
126 tval.name = val->name + 9;
128 X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, X509V3_R_INVALID_SYNTAX);
131 tval.value = val->value;
132 sub = GENERAL_SUBTREE_new();
135 if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1))
138 *ptree = sk_GENERAL_SUBTREE_new_null();
139 if (*ptree == NULL || !sk_GENERAL_SUBTREE_push(*ptree, sub))
147 X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, ERR_R_MALLOC_FAILURE);
149 NAME_CONSTRAINTS_free(ncons);
150 GENERAL_SUBTREE_free(sub);
155 static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,
158 NAME_CONSTRAINTS *ncons = a;
159 do_i2r_name_constraints(method, ncons->permittedSubtrees,
160 bp, ind, "Permitted");
161 if (ncons->permittedSubtrees && ncons->excludedSubtrees)
163 do_i2r_name_constraints(method, ncons->excludedSubtrees,
164 bp, ind, "Excluded");
168 static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
169 STACK_OF(GENERAL_SUBTREE) *trees,
170 BIO *bp, int ind, const char *name)
172 GENERAL_SUBTREE *tree;
174 if (sk_GENERAL_SUBTREE_num(trees) > 0)
175 BIO_printf(bp, "%*s%s:\n", ind, "", name);
176 for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) {
179 tree = sk_GENERAL_SUBTREE_value(trees, i);
180 BIO_printf(bp, "%*s", ind + 2, "");
181 if (tree->base->type == GEN_IPADD)
182 print_nc_ipadd(bp, tree->base->d.ip);
184 GENERAL_NAME_print(bp, tree->base);
189 static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip)
197 BIO_printf(bp, "%d.%d.%d.%d/%d.%d.%d.%d",
198 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
199 } else if (len == 32) {
200 for (i = 0; i < 16; i++) {
201 BIO_printf(bp, "%X", p[0] << 8 | p[1]);
209 BIO_printf(bp, "IP Address:<invalid>");
213 #define NAME_CHECK_MAX (1 << 20)
215 static int add_lengths(int *out, int a, int b)
217 /* sk_FOO_num(NULL) returns -1 but is effectively 0 when iterating. */
230 * Check a certificate conforms to a specified set of constraints.
232 * X509_V_OK: All constraints obeyed.
233 * X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation.
234 * X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation.
235 * X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type.
236 * X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE: Unsupported constraint type.
237 * X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax.
238 * X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name
241 int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc)
243 int r, i, name_count, constraint_count;
246 nm = X509_get_subject_name(x);
249 * Guard against certificates with an excessive number of names or
250 * constraints causing a computationally expensive name constraints check.
252 if (!add_lengths(&name_count, X509_NAME_entry_count(nm),
253 sk_GENERAL_NAME_num(x->altname))
254 || !add_lengths(&constraint_count,
255 sk_GENERAL_SUBTREE_num(nc->permittedSubtrees),
256 sk_GENERAL_SUBTREE_num(nc->excludedSubtrees))
257 || (name_count > 0 && constraint_count > NAME_CHECK_MAX / name_count))
258 return X509_V_ERR_UNSPECIFIED;
260 if (X509_NAME_entry_count(nm) > 0) {
262 gntmp.type = GEN_DIRNAME;
263 gntmp.d.directoryName = nm;
265 r = nc_match(&gntmp, nc);
270 gntmp.type = GEN_EMAIL;
272 /* Process any email address attributes in subject name */
275 const X509_NAME_ENTRY *ne;
277 i = X509_NAME_get_index_by_NID(nm, NID_pkcs9_emailAddress, i);
280 ne = X509_NAME_get_entry(nm, i);
281 gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne);
282 if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING)
283 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
285 r = nc_match(&gntmp, nc);
293 for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++) {
294 GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i);
295 r = nc_match(gen, nc);
304 static int cn2dnsid(ASN1_STRING *cn, unsigned char **dnsid, size_t *idlen)
307 unsigned char *utf8_value;
311 /* Don't leave outputs uninitialized */
316 * Per RFC 6125, DNS-IDs representing internationalized domain names appear
317 * in certificates in A-label encoded form:
319 * https://tools.ietf.org/html/rfc6125#section-6.4.2
321 * The same applies to CNs which are intended to represent DNS names.
322 * However, while in the SAN DNS-IDs are IA5Strings, as CNs they may be
323 * needlessly encoded in 16-bit Unicode. We perform a conversion to UTF-8
324 * to ensure that we get an ASCII representation of any CNs that are
325 * representable as ASCII, but just not encoded as ASCII. The UTF-8 form
326 * may contain some non-ASCII octets, and that's fine, such CNs are not
327 * valid legacy DNS names.
329 * Note, 'int' is the return type of ASN1_STRING_to_UTF8() so that's what
330 * we must use for 'utf8_length'.
332 if ((utf8_length = ASN1_STRING_to_UTF8(&utf8_value, cn)) < 0)
333 return X509_V_ERR_OUT_OF_MEM;
336 * Some certificates have had names that include a *trailing* NUL byte.
337 * Remove these harmless NUL characters. They would otherwise yield false
338 * alarms with the following embedded NUL check.
340 while (utf8_length > 0 && utf8_value[utf8_length - 1] == '\0')
343 /* Reject *embedded* NULs */
344 if ((size_t)utf8_length != strlen((char *)utf8_value)) {
345 OPENSSL_free(utf8_value);
346 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
350 * XXX: Deviation from strict DNS name syntax, also check names with '_'
351 * Check DNS name syntax, any '-' or '.' must be internal,
352 * and on either side of each '.' we can't have a '-' or '.'.
354 * If the name has just one label, we don't consider it a DNS name. This
355 * means that "CN=sometld" cannot be precluded by DNS name constraints, but
356 * that is not a problem.
358 for (i = 0; i < utf8_length; ++i) {
359 unsigned char c = utf8_value[i];
361 if ((c >= 'a' && c <= 'z')
362 || (c >= 'A' && c <= 'Z')
363 || (c >= '0' && c <= '9')
367 /* Dot and hyphen cannot be first or last. */
368 if (i > 0 && i < utf8_length - 1) {
372 * Next to a dot the preceding and following characters must not be
373 * another dot or a hyphen. Otherwise, record that the name is
374 * plausible, since it has two or more labels.
377 && utf8_value[i + 1] != '.'
378 && utf8_value[i - 1] != '-'
379 && utf8_value[i + 1] != '-') {
390 *idlen = (size_t)utf8_length;
393 OPENSSL_free(utf8_value);
398 * Check CN against DNS-ID name constraints.
400 int NAME_CONSTRAINTS_check_CN(X509 *x, NAME_CONSTRAINTS *nc)
403 X509_NAME *nm = X509_get_subject_name(x);
408 stmp.type = V_ASN1_IA5STRING;
409 gntmp.type = GEN_DNS;
410 gntmp.d.dNSName = &stmp;
412 /* Process any commonName attributes in subject name */
417 unsigned char *idval;
420 i = X509_NAME_get_index_by_NID(nm, NID_commonName, i);
423 ne = X509_NAME_get_entry(nm, i);
424 cn = X509_NAME_ENTRY_get_data(ne);
426 /* Only process attributes that look like host names */
427 if ((r = cn2dnsid(cn, &idval, &idlen)) != X509_V_OK)
434 r = nc_match(&gntmp, nc);
443 * Return nonzero if the GeneralSubtree has valid 'minimum' field
444 * (must be absent or 0) and valid 'maximum' field (must be absent).
446 static int nc_minmax_valid(GENERAL_SUBTREE *sub) {
454 bn = ASN1_INTEGER_to_BN(sub->minimum, NULL);
455 if (bn == NULL || !BN_is_zero(bn))
463 static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc)
465 GENERAL_SUBTREE *sub;
469 * Permitted subtrees: if any subtrees exist of matching the type at
470 * least one subtree must match.
473 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) {
474 sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);
475 if (gen->type != sub->base->type)
477 if (!nc_minmax_valid(sub))
478 return X509_V_ERR_SUBTREE_MINMAX;
479 /* If we already have a match don't bother trying any more */
484 r = nc_match_single(gen, sub->base);
487 else if (r != X509_V_ERR_PERMITTED_VIOLATION)
492 return X509_V_ERR_PERMITTED_VIOLATION;
494 /* Excluded subtrees: must not match any of these */
496 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) {
497 sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);
498 if (gen->type != sub->base->type)
500 if (!nc_minmax_valid(sub))
501 return X509_V_ERR_SUBTREE_MINMAX;
503 r = nc_match_single(gen, sub->base);
505 return X509_V_ERR_EXCLUDED_VIOLATION;
506 else if (r != X509_V_ERR_PERMITTED_VIOLATION)
515 static int nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base)
517 switch (base->type) {
519 return nc_dn(gen->d.directoryName, base->d.directoryName);
522 return nc_dns(gen->d.dNSName, base->d.dNSName);
525 return nc_email(gen->d.rfc822Name, base->d.rfc822Name);
528 return nc_uri(gen->d.uniformResourceIdentifier,
529 base->d.uniformResourceIdentifier);
532 return nc_ip(gen->d.iPAddress, base->d.iPAddress);
535 return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;
541 * directoryName name constraint matching. The canonical encoding of
542 * X509_NAME makes this comparison easy. It is matched if the subtree is a
543 * subset of the name.
546 static int nc_dn(X509_NAME *nm, X509_NAME *base)
548 /* Ensure canonical encodings are up to date. */
549 if (nm->modified && i2d_X509_NAME(nm, NULL) < 0)
550 return X509_V_ERR_OUT_OF_MEM;
551 if (base->modified && i2d_X509_NAME(base, NULL) < 0)
552 return X509_V_ERR_OUT_OF_MEM;
553 if (base->canon_enclen > nm->canon_enclen)
554 return X509_V_ERR_PERMITTED_VIOLATION;
555 if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen))
556 return X509_V_ERR_PERMITTED_VIOLATION;
560 static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
562 char *baseptr = (char *)base->data;
563 char *dnsptr = (char *)dns->data;
564 /* Empty matches everything */
568 * Otherwise can add zero or more components on the left so compare RHS
569 * and if dns is longer and expect '.' as preceding character.
571 if (dns->length > base->length) {
572 dnsptr += dns->length - base->length;
573 if (*baseptr != '.' && dnsptr[-1] != '.')
574 return X509_V_ERR_PERMITTED_VIOLATION;
577 if (ia5casecmp(baseptr, dnsptr))
578 return X509_V_ERR_PERMITTED_VIOLATION;
584 static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
586 const char *baseptr = (char *)base->data;
587 const char *emlptr = (char *)eml->data;
589 const char *baseat = strchr(baseptr, '@');
590 const char *emlat = strchr(emlptr, '@');
592 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
593 /* Special case: initial '.' is RHS match */
594 if (!baseat && (*baseptr == '.')) {
595 if (eml->length > base->length) {
596 emlptr += eml->length - base->length;
597 if (ia5casecmp(baseptr, emlptr) == 0)
600 return X509_V_ERR_PERMITTED_VIOLATION;
603 /* If we have anything before '@' match local part */
606 if (baseat != baseptr) {
607 if ((baseat - baseptr) != (emlat - emlptr))
608 return X509_V_ERR_PERMITTED_VIOLATION;
609 /* Case sensitive match of local part */
610 if (strncmp(baseptr, emlptr, emlat - emlptr))
611 return X509_V_ERR_PERMITTED_VIOLATION;
613 /* Position base after '@' */
614 baseptr = baseat + 1;
617 /* Just have hostname left to match: case insensitive */
618 if (ia5casecmp(baseptr, emlptr))
619 return X509_V_ERR_PERMITTED_VIOLATION;
625 static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
627 const char *baseptr = (char *)base->data;
628 const char *hostptr = (char *)uri->data;
629 const char *p = strchr(hostptr, ':');
631 /* Check for foo:// and skip past it */
632 if (!p || (p[1] != '/') || (p[2] != '/'))
633 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
636 /* Determine length of hostname part of URI */
638 /* Look for a port indicator as end of hostname first */
640 p = strchr(hostptr, ':');
641 /* Otherwise look for trailing slash */
643 p = strchr(hostptr, '/');
646 hostlen = strlen(hostptr);
648 hostlen = p - hostptr;
651 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
653 /* Special case: initial '.' is RHS match */
654 if (*baseptr == '.') {
655 if (hostlen > base->length) {
656 p = hostptr + hostlen - base->length;
657 if (ia5ncasecmp(p, baseptr, base->length) == 0)
660 return X509_V_ERR_PERMITTED_VIOLATION;
663 if ((base->length != (int)hostlen)
664 || ia5ncasecmp(hostptr, baseptr, hostlen))
665 return X509_V_ERR_PERMITTED_VIOLATION;
671 static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base)
673 int hostlen, baselen, i;
674 unsigned char *hostptr, *baseptr, *maskptr;
676 hostlen = ip->length;
677 baseptr = base->data;
678 baselen = base->length;
680 /* Invalid if not IPv4 or IPv6 */
681 if (!((hostlen == 4) || (hostlen == 16)))
682 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
683 if (!((baselen == 8) || (baselen == 32)))
684 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
686 /* Do not match IPv4 with IPv6 */
687 if (hostlen * 2 != baselen)
688 return X509_V_ERR_PERMITTED_VIOLATION;
690 maskptr = base->data + hostlen;
692 /* Considering possible not aligned base ipAddress */
693 /* Not checking for wrong mask definition: i.e.: 255.0.255.0 */
694 for (i = 0; i < hostlen; i++)
695 if ((hostptr[i] & maskptr[i]) != (baseptr[i] & maskptr[i]))
696 return X509_V_ERR_PERMITTED_VIOLATION;