xref: /openbsd-src/lib/libcrypto/x509/x509_ncons.c (revision 8b5faa7170599a10b7304ec693b84d6d6fd0697f)

/* $OpenBSD: x509_ncons.c,v 1.11 2024/07/13 15:08:58 tb Exp $ */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 */
/* ====================================================================
 * Copyright (c) 2003 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include <string.h>

#include <openssl/asn1t.h>
#include <openssl/conf.h>
#include <openssl/err.h>
#include <openssl/x509v3.h>

#include "x509_local.h"

static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
    X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval);
static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
    void *a, BIO *bp, int ind);
static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
    STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp, int ind, char *name);
static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip);

static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc);
static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen);
static int nc_dn(X509_NAME *sub, X509_NAME *nm);
static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns);
static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml);
static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base);

static const X509V3_EXT_METHOD x509v3_ext_name_constraints = {
	.ext_nid = NID_name_constraints,
	.ext_flags = 0,
	.it = &NAME_CONSTRAINTS_it,
	.ext_new = NULL,
	.ext_free = NULL,
	.d2i = NULL,
	.i2d = NULL,
	.i2s = NULL,
	.s2i = NULL,
	.i2v = NULL,
	.v2i = v2i_NAME_CONSTRAINTS,
	.i2r = i2r_NAME_CONSTRAINTS,
	.r2i = NULL,
	.usr_data = NULL,
};

const X509V3_EXT_METHOD *
x509v3_ext_method_name_constraints(void)
{
	return &x509v3_ext_name_constraints;
}

static const ASN1_TEMPLATE GENERAL_SUBTREE_seq_tt[] = {
	{
		.flags = 0,
		.tag = 0,
		.offset = offsetof(GENERAL_SUBTREE, base),
		.field_name = "base",
		.item = &GENERAL_NAME_it,
	},
	{
		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_OPTIONAL,
		.tag = 0,
		.offset = offsetof(GENERAL_SUBTREE, minimum),
		.field_name = "minimum",
		.item = &ASN1_INTEGER_it,
	},
	{
		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_OPTIONAL,
		.tag = 1,
		.offset = offsetof(GENERAL_SUBTREE, maximum),
		.field_name = "maximum",
		.item = &ASN1_INTEGER_it,
	},
};

const ASN1_ITEM GENERAL_SUBTREE_it = {
	.itype = ASN1_ITYPE_SEQUENCE,
	.utype = V_ASN1_SEQUENCE,
	.templates = GENERAL_SUBTREE_seq_tt,
	.tcount = sizeof(GENERAL_SUBTREE_seq_tt) / sizeof(ASN1_TEMPLATE),
	.funcs = NULL,
	.size = sizeof(GENERAL_SUBTREE),
	.sname = "GENERAL_SUBTREE",
};
LCRYPTO_ALIAS(GENERAL_SUBTREE_it);

static const ASN1_TEMPLATE NAME_CONSTRAINTS_seq_tt[] = {
	{
		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_SEQUENCE_OF | ASN1_TFLG_OPTIONAL,
		.tag = 0,
		.offset = offsetof(NAME_CONSTRAINTS, permittedSubtrees),
		.field_name = "permittedSubtrees",
		.item = &GENERAL_SUBTREE_it,
	},
	{
		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_SEQUENCE_OF | ASN1_TFLG_OPTIONAL,
		.tag = 1,
		.offset = offsetof(NAME_CONSTRAINTS, excludedSubtrees),
		.field_name = "excludedSubtrees",
		.item = &GENERAL_SUBTREE_it,
	},
};

const ASN1_ITEM NAME_CONSTRAINTS_it = {
	.itype = ASN1_ITYPE_SEQUENCE,
	.utype = V_ASN1_SEQUENCE,
	.templates = NAME_CONSTRAINTS_seq_tt,
	.tcount = sizeof(NAME_CONSTRAINTS_seq_tt) / sizeof(ASN1_TEMPLATE),
	.funcs = NULL,
	.size = sizeof(NAME_CONSTRAINTS),
	.sname = "NAME_CONSTRAINTS",
};
LCRYPTO_ALIAS(NAME_CONSTRAINTS_it);


GENERAL_SUBTREE *
GENERAL_SUBTREE_new(void)
{
	return (GENERAL_SUBTREE*)ASN1_item_new(&GENERAL_SUBTREE_it);
}
LCRYPTO_ALIAS(GENERAL_SUBTREE_new);

void
GENERAL_SUBTREE_free(GENERAL_SUBTREE *a)
{
	ASN1_item_free((ASN1_VALUE *)a, &GENERAL_SUBTREE_it);
}
LCRYPTO_ALIAS(GENERAL_SUBTREE_free);

NAME_CONSTRAINTS *
NAME_CONSTRAINTS_new(void)
{
	return (NAME_CONSTRAINTS*)ASN1_item_new(&NAME_CONSTRAINTS_it);
}
LCRYPTO_ALIAS(NAME_CONSTRAINTS_new);

void
NAME_CONSTRAINTS_free(NAME_CONSTRAINTS *a)
{
	ASN1_item_free((ASN1_VALUE *)a, &NAME_CONSTRAINTS_it);
}
LCRYPTO_ALIAS(NAME_CONSTRAINTS_free);

static void *
v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, X509V3_CTX *ctx,
    STACK_OF(CONF_VALUE) *nval)
{
	int i;
	CONF_VALUE tval, *val;
	STACK_OF(GENERAL_SUBTREE) **ptree = NULL;
	NAME_CONSTRAINTS *ncons = NULL;
	GENERAL_SUBTREE *sub = NULL;

	ncons = NAME_CONSTRAINTS_new();
	if (!ncons)
		goto memerr;
	for (i = 0; i < sk_CONF_VALUE_num(nval); i++) {
		val = sk_CONF_VALUE_value(nval, i);
		if (!strncmp(val->name, "permitted", 9) && val->name[9]) {
			ptree = &ncons->permittedSubtrees;
			tval.name = val->name + 10;
		} else if (!strncmp(val->name, "excluded", 8) && val->name[8]) {
			ptree = &ncons->excludedSubtrees;
			tval.name = val->name + 9;
		} else {
			X509V3error(X509V3_R_INVALID_SYNTAX);
			goto err;
		}
		tval.value = val->value;
		sub = GENERAL_SUBTREE_new();
		if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1))
			goto err;
		if (!*ptree)
			*ptree = sk_GENERAL_SUBTREE_new_null();
		if (!*ptree || !sk_GENERAL_SUBTREE_push(*ptree, sub))
			goto memerr;
		sub = NULL;
	}

	return ncons;

memerr:
	X509V3error(ERR_R_MALLOC_FAILURE);
err:
	NAME_CONSTRAINTS_free(ncons);
	GENERAL_SUBTREE_free(sub);
	return NULL;
}

static int
i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a, BIO *bp, int ind)
{
	NAME_CONSTRAINTS *ncons = a;

	do_i2r_name_constraints(method, ncons->permittedSubtrees,
	    bp, ind, "Permitted");
	do_i2r_name_constraints(method, ncons->excludedSubtrees,
	    bp, ind, "Excluded");
	return 1;
}

static int
do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
    STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp, int ind, char *name)
{
	GENERAL_SUBTREE *tree;
	int i;

	if (sk_GENERAL_SUBTREE_num(trees) > 0)
		BIO_printf(bp, "%*s%s:\n", ind, "", name);
	for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) {
		tree = sk_GENERAL_SUBTREE_value(trees, i);
		BIO_printf(bp, "%*s", ind + 2, "");
		if (tree->base->type == GEN_IPADD)
			print_nc_ipadd(bp, tree->base->d.ip);
		else
			GENERAL_NAME_print(bp, tree->base);
		BIO_puts(bp, "\n");
	}
	return 1;
}

static int
print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip)
{
	int i, len;
	unsigned char *p;

	p = ip->data;
	len = ip->length;
	BIO_puts(bp, "IP:");
	if (len == 8) {
		BIO_printf(bp, "%d.%d.%d.%d/%d.%d.%d.%d",
		    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
	} else if (len == 32) {
		for (i = 0; i < 16; i++) {
			BIO_printf(bp, "%X", p[0] << 8 | p[1]);
			p += 2;
			if (i == 7)
				BIO_puts(bp, "/");
			else if (i != 15)
				BIO_puts(bp, ":");
		}
	} else
		BIO_printf(bp, "IP Address:<invalid>");
	return 1;
}

/* Check a certificate conforms to a specified set of constraints.
 * Return values:
 *  X509_V_OK: All constraints obeyed.
 *  X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation.
 *  X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation.
 *  X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type.
 *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE:  Unsupported constraint type.
 *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax.
 *  X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name
 */

int
NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc)
{
	int r, i;
	X509_NAME *nm;

	nm = X509_get_subject_name(x);

	if (X509_NAME_entry_count(nm) > 0) {
		GENERAL_NAME gntmp;
		gntmp.type = GEN_DIRNAME;
		gntmp.d.directoryName = nm;

		r = nc_match(&gntmp, nc);

		if (r != X509_V_OK)
			return r;

		gntmp.type = GEN_EMAIL;

		/* Process any email address attributes in subject name */

		for (i = -1;;) {
			X509_NAME_ENTRY *ne;
			i = X509_NAME_get_index_by_NID(nm,
			    NID_pkcs9_emailAddress, i);
			if (i == -1)
				break;
			ne = X509_NAME_get_entry(nm, i);
			gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne);
			if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING)
				return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

			r = nc_match(&gntmp, nc);

			if (r != X509_V_OK)
				return r;
		}

	}

	for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++) {
		GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i);
		r = nc_match(gen, nc);
		if (r != X509_V_OK)
			return r;
	}
	return X509_V_OK;
}
LCRYPTO_ALIAS(NAME_CONSTRAINTS_check);
static int
nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc)
{
	GENERAL_SUBTREE *sub;
	int i, r, match = 0;

	/* Permitted subtrees: if any subtrees exist of matching the type
	 * at least one subtree must match.
	 */

	for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) {
		sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);
		if (gen->type != sub->base->type)
			continue;
		if (sub->minimum || sub->maximum)
			return X509_V_ERR_SUBTREE_MINMAX;
		/* If we already have a match don't bother trying any more */
		if (match == 2)
			continue;
		if (match == 0)
			match = 1;
		r = nc_match_single(gen, sub->base);
		if (r == X509_V_OK)
			match = 2;
		else if (r != X509_V_ERR_PERMITTED_VIOLATION)
			return r;
	}

	if (match == 1)
		return X509_V_ERR_PERMITTED_VIOLATION;

	/* Excluded subtrees: must not match any of these */

	for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) {
		sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);
		if (gen->type != sub->base->type)
			continue;
		if (sub->minimum || sub->maximum)
			return X509_V_ERR_SUBTREE_MINMAX;

		r = nc_match_single(gen, sub->base);
		if (r == X509_V_OK)
			return X509_V_ERR_EXCLUDED_VIOLATION;
		else if (r != X509_V_ERR_PERMITTED_VIOLATION)
			return r;

	}

	return X509_V_OK;
}

static int
nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base)
{
	switch (base->type) {
	case GEN_DIRNAME:
		return nc_dn(gen->d.directoryName, base->d.directoryName);

	case GEN_DNS:
		return nc_dns(gen->d.dNSName, base->d.dNSName);

	case GEN_EMAIL:
		return nc_email(gen->d.rfc822Name, base->d.rfc822Name);

	case GEN_URI:
		return nc_uri(gen->d.uniformResourceIdentifier,
		    base->d.uniformResourceIdentifier);

	default:
		return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;
	}
}

/* directoryName name constraint matching.
 * The canonical encoding of X509_NAME makes this comparison easy. It is
 * matched if the subtree is a subset of the name.
 */

static int
nc_dn(X509_NAME *nm, X509_NAME *base)
{
	/* Ensure canonical encodings are up to date.  */
	if (nm->modified && i2d_X509_NAME(nm, NULL) < 0)
		return X509_V_ERR_OUT_OF_MEM;
	if (base->modified && i2d_X509_NAME(base, NULL) < 0)
		return X509_V_ERR_OUT_OF_MEM;
	if (base->canon_enclen > nm->canon_enclen)
		return X509_V_ERR_PERMITTED_VIOLATION;
	if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen))
		return X509_V_ERR_PERMITTED_VIOLATION;
	return X509_V_OK;
}

static int
nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
{
	char *baseptr = (char *)base->data;
	char *dnsptr = (char *)dns->data;

	/* Empty matches everything */
	if (!*baseptr)
		return X509_V_OK;
	/* Otherwise can add zero or more components on the left so
	 * compare RHS and if dns is longer and expect '.' as preceding
	 * character.
	 */
	if (dns->length > base->length) {
		dnsptr += dns->length - base->length;
		if (baseptr[0] != '.' && dnsptr[-1] != '.')
			return X509_V_ERR_PERMITTED_VIOLATION;
	}

	if (strcasecmp(baseptr, dnsptr))
		return X509_V_ERR_PERMITTED_VIOLATION;

	return X509_V_OK;
}

static int
nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
{
	const char *baseptr = (char *)base->data;
	const char *emlptr = (char *)eml->data;
	const char *baseat = strchr(baseptr, '@');
	const char *emlat = strchr(emlptr, '@');

	if (!emlat)
		return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
	/* Special case: initial '.' is RHS match */
	if (!baseat && (*baseptr == '.')) {
		if (eml->length > base->length) {
			emlptr += eml->length - base->length;
			if (!strcasecmp(baseptr, emlptr))
				return X509_V_OK;
		}
		return X509_V_ERR_PERMITTED_VIOLATION;
	}

	/* If we have anything before '@' match local part */

	if (baseat) {
		if (baseat != baseptr) {
			if ((baseat - baseptr) != (emlat - emlptr))
				return X509_V_ERR_PERMITTED_VIOLATION;
			/* Case sensitive match of local part */
			if (strncmp(baseptr, emlptr, emlat - emlptr))
				return X509_V_ERR_PERMITTED_VIOLATION;
		}
		/* Position base after '@' */
		baseptr = baseat + 1;
	}
	emlptr = emlat + 1;
	/* Just have hostname left to match: case insensitive */
	if (strcasecmp(baseptr, emlptr))
		return X509_V_ERR_PERMITTED_VIOLATION;

	return X509_V_OK;
}

static int
nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
{
	const char *baseptr = (char *)base->data;
	const char *hostptr = (char *)uri->data;
	const char *p = strchr(hostptr, ':');
	int hostlen;

	/* Check for foo:// and skip past it */
	if (!p || (p[1] != '/') || (p[2] != '/'))
		return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
	hostptr = p + 3;

	/* Determine length of hostname part of URI */

	/* Look for a port indicator as end of hostname first */

	p = strchr(hostptr, ':');
	/* Otherwise look for trailing slash */
	if (!p)
		p = strchr(hostptr, '/');

	if (!p)
		hostlen = strlen(hostptr);
	else
		hostlen = p - hostptr;

	if (hostlen == 0)
		return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

	/* Special case: initial '.' is RHS match */
	if (*baseptr == '.') {
		if (hostlen > base->length) {
			p = hostptr + hostlen - base->length;
			if (!strncasecmp(p, baseptr, base->length))
				return X509_V_OK;
		}
		return X509_V_ERR_PERMITTED_VIOLATION;
	}

	if ((base->length != (int)hostlen) ||
	    strncasecmp(hostptr, baseptr, hostlen))
		return X509_V_ERR_PERMITTED_VIOLATION;

	return X509_V_OK;
}