/* $OpenBSD: x509_ncons.c,v 1.12 2025/05/10 05:54:39 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/x509v3.h>

#include "err_local.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;
}