/*

 * Copyright 1999-2023 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include "internal/cryptlib.h"

#include <openssl/x509v3.h>

#include "crypto/x509.h"

static int tr_cmp(const X509_TRUST *const *a, const X509_TRUST *const *b);

static void trtable_free(X509_TRUST *p);

static int trust_1oidany(X509_TRUST *trust, X509 *x, int flags);

static int trust_1oid(X509_TRUST *trust, X509 *x, int flags);

static int trust_compat(X509_TRUST *trust, X509 *x, int flags);

static int obj_trust(int id, X509 *x, int flags);

static int (*default_trust) (int id, X509 *x, int flags) = obj_trust;

/*

 * WARNING: the following table should be kept in order of trust and without

 * any gaps so we can just subtract the minimum trust value to get an index

 * into the table

 */

static X509_TRUST trstandard[] = {

    {X509_TRUST_COMPAT, 0, trust_compat, "compatible", 0, NULL},

    {X509_TRUST_SSL_CLIENT, 0, trust_1oidany, "SSL Client", NID_client_auth,

     NULL},

    {X509_TRUST_SSL_SERVER, 0, trust_1oidany, "SSL Server", NID_server_auth,

     NULL},

    {X509_TRUST_EMAIL, 0, trust_1oidany, "S/MIME email", NID_email_protect,

     NULL},

    {X509_TRUST_OBJECT_SIGN, 0, trust_1oidany, "Object Signer", NID_code_sign,

     NULL},

    {X509_TRUST_OCSP_SIGN, 0, trust_1oid, "OCSP responder", NID_OCSP_sign,

     NULL},

    {X509_TRUST_OCSP_REQUEST, 0, trust_1oid, "OCSP request", NID_ad_OCSP,

     NULL},

    {X509_TRUST_TSA, 0, trust_1oidany, "TSA server", NID_time_stamp, NULL}

};

#define X509_TRUST_COUNT        OSSL_NELEM(trstandard)

static STACK_OF(X509_TRUST) *trtable = NULL;

static int tr_cmp(const X509_TRUST *const *a, const X509_TRUST *const *b)

{

    return (*a)->trust - (*b)->trust;

}

int (*X509_TRUST_set_default(int (*trust) (int, X509 *, int))) (int, X509 *,

                                                                int) {

    int (*oldtrust) (int, X509 *, int);

    oldtrust = default_trust;

    default_trust = trust;

    return oldtrust;

}

/* Returns X509_TRUST_TRUSTED, X509_TRUST_REJECTED, or X509_TRUST_UNTRUSTED */

int X509_check_trust(X509 *x, int id, int flags)

{

    X509_TRUST *pt;

    int idx;

    /* We get this as a default value */

    if (id == X509_TRUST_DEFAULT)

        return obj_trust(NID_anyExtendedKeyUsage, x,

                         flags | X509_TRUST_DO_SS_COMPAT);

    idx = X509_TRUST_get_by_id(id);

    if (idx < 0)

        return default_trust(id, x, flags);

    pt = X509_TRUST_get0(idx);

    return pt->check_trust(pt, x, flags);

}

int X509_TRUST_get_count(void)

{

    if (!trtable)

        return X509_TRUST_COUNT;

    return sk_X509_TRUST_num(trtable) + X509_TRUST_COUNT;

}

X509_TRUST *X509_TRUST_get0(int idx)

{

    if (idx < 0)

        return NULL;

    if (idx < (int)X509_TRUST_COUNT)

        return trstandard + idx;

    return sk_X509_TRUST_value(trtable, idx - X509_TRUST_COUNT);

}

int X509_TRUST_get_by_id(int id)

{

    X509_TRUST tmp;

    int idx;

    if ((id >= X509_TRUST_MIN) && (id <= X509_TRUST_MAX))

        return id - X509_TRUST_MIN;

    if (trtable == NULL)

        return -1;

    tmp.trust = id;

    /* Ideally, this would be done under lock */

    sk_X509_TRUST_sort(trtable);

    idx = sk_X509_TRUST_find(trtable, &tmp);

    if (idx < 0)

        return -1;

    return idx + X509_TRUST_COUNT;

}

int X509_TRUST_set(int *t, int trust)

{

    if (X509_TRUST_get_by_id(trust) < 0) {

        ERR_raise(ERR_LIB_X509, X509_R_INVALID_TRUST);

        return 0;

    }

    *t = trust;

    return 1;

}

int X509_TRUST_add(int id, int flags, int (*ck) (X509_TRUST *, X509 *, int),

                   const char *name, int arg1, void *arg2)

{

    int idx;

    X509_TRUST *trtmp;

    /*

     * This is set according to what we change: application can't set it

     */

    flags &= ~X509_TRUST_DYNAMIC;

    /* This will always be set for application modified trust entries */

    flags |= X509_TRUST_DYNAMIC_NAME;

    /* Get existing entry if any */

    idx = X509_TRUST_get_by_id(id);

    /* Need a new entry */

    if (idx < 0) {

        if ((trtmp = OPENSSL_malloc(sizeof(*trtmp))) == NULL)

            return 0;

        trtmp->flags = X509_TRUST_DYNAMIC;

    } else

        trtmp = X509_TRUST_get0(idx);

    /* OPENSSL_free existing name if dynamic */

    if (trtmp->flags & X509_TRUST_DYNAMIC_NAME)

        OPENSSL_free(trtmp->name);

    /* dup supplied name */

    if ((trtmp->name = OPENSSL_strdup(name)) == NULL)

        goto err;

    /* Keep the dynamic flag of existing entry */

    trtmp->flags &= X509_TRUST_DYNAMIC;

    /* Set all other flags */

    trtmp->flags |= flags;

    trtmp->trust = id;

    trtmp->check_trust = ck;

    trtmp->arg1 = arg1;

    trtmp->arg2 = arg2;

    /* If its a new entry manage the dynamic table */

    if (idx < 0) {

        if (trtable == NULL

            && (trtable = sk_X509_TRUST_new(tr_cmp)) == NULL) {

            ERR_raise(ERR_LIB_X509, ERR_R_CRYPTO_LIB);

            goto err;

        }

        if (!sk_X509_TRUST_push(trtable, trtmp)) {

            ERR_raise(ERR_LIB_X509, ERR_R_CRYPTO_LIB);

            goto err;

        }

    }

    return 1;

 err:

    if (idx < 0) {

        OPENSSL_free(trtmp->name);

        OPENSSL_free(trtmp);

    }

    return 0;

}

static void trtable_free(X509_TRUST *p)

{

    if (p == NULL)

        return;

    if (p->flags & X509_TRUST_DYNAMIC) {

        if (p->flags & X509_TRUST_DYNAMIC_NAME)

            OPENSSL_free(p->name);

        OPENSSL_free(p);

    }

}

void X509_TRUST_cleanup(void)

{

    sk_X509_TRUST_pop_free(trtable, trtable_free);

    trtable = NULL;

}

int X509_TRUST_get_flags(const X509_TRUST *xp)

{

    return xp->flags;

}

char *X509_TRUST_get0_name(const X509_TRUST *xp)

{

    return xp->name;

}

int X509_TRUST_get_trust(const X509_TRUST *xp)

{

    return xp->trust;

}

static int trust_1oidany(X509_TRUST *trust, X509 *x, int flags)

{

    /*

     * Declare the chain verified if the desired trust OID is not rejected in

     * any auxiliary trust info for this certificate, and the OID is either

     * expressly trusted, or else either "anyEKU" is trusted, or the

     * certificate is self-signed and X509_TRUST_NO_SS_COMPAT is not set.

     */

    flags |= X509_TRUST_DO_SS_COMPAT | X509_TRUST_OK_ANY_EKU;

    return obj_trust(trust->arg1, x, flags);

}

static int trust_1oid(X509_TRUST *trust, X509 *x, int flags)

{

    /*

     * Declare the chain verified only if the desired trust OID is not

     * rejected and is expressly trusted.  Neither "anyEKU" nor "compat"

     * trust in self-signed certificates apply.

     */

    flags &= ~(X509_TRUST_DO_SS_COMPAT | X509_TRUST_OK_ANY_EKU);

    return obj_trust(trust->arg1, x, flags);

}

static int trust_compat(X509_TRUST *trust, X509 *x, int flags)

{

    /* Call for side-effect of setting EXFLAG_SS for self-signed-certs */

    if (X509_check_purpose(x, -1, 0) != 1)

        return X509_TRUST_UNTRUSTED;

    if ((flags & X509_TRUST_NO_SS_COMPAT) == 0 && (x->ex_flags & EXFLAG_SS))

        return X509_TRUST_TRUSTED;

    else

        return X509_TRUST_UNTRUSTED;

}

/*

 * |id| is the NID of the extended key usage (EKU) to check for certificate |x|.

 * Return X509_TRUST_REJECTED if negative trust attributes of |x| prevents it.

 * Return X509_TRUST_TRUSTED if positive trust attributes of |x| accepts it.

 * If |flags| includes X509_TRUST_OK_ANY_EKU then anyEKU serves as wildcard.

 * Return X509_TRUST_UNTRUSTED if no clear decision has been reached here.

 */

static int obj_trust(int id, X509 *x, int flags)

{

    X509_CERT_AUX *ax = x->aux;

    int i;

    if (ax != NULL && ax->reject != NULL) {

        for (i = 0; i < sk_ASN1_OBJECT_num(ax->reject); i++) {

            ASN1_OBJECT *obj = sk_ASN1_OBJECT_value(ax->reject, i);

            int nid = OBJ_obj2nid(obj);

            if (nid == id || (nid == NID_anyExtendedKeyUsage &&

                (flags & X509_TRUST_OK_ANY_EKU)))

                return X509_TRUST_REJECTED;

        }

    }

    if (ax != NULL && ax->trust != NULL) {

        for (i = 0; i < sk_ASN1_OBJECT_num(ax->trust); i++) {

            ASN1_OBJECT *obj = sk_ASN1_OBJECT_value(ax->trust, i);

            int nid = OBJ_obj2nid(obj);

            if (nid == id || (nid == NID_anyExtendedKeyUsage &&

                (flags & X509_TRUST_OK_ANY_EKU)))

                return X509_TRUST_TRUSTED;

        }

        /*

         * Reject when explicit trust EKU are set and none match.

         *

         * Returning untrusted is enough for full chains that end in

         * self-signed roots, because when explicit trust is specified it

         * suppresses the default blanket trust of self-signed objects.

         *

         * But for partial chains, this is not enough, because absent a similar

         * trust-self-signed policy, non matching EKUs are indistinguishable

         * from lack of EKU constraints.

         *

         * Therefore, failure to match any trusted purpose must trigger an

         * explicit reject.

         */

        return X509_TRUST_REJECTED;

    }

    if ((flags & X509_TRUST_DO_SS_COMPAT) == 0)

        return X509_TRUST_UNTRUSTED;

    /*

     * Not rejected, and there is no list of accepted uses, try compat.

     */

    return trust_compat(NULL, x, flags);

}