/*
 * Written by Matt Caswell for the OpenSSL project.
 */
/* ====================================================================
 * Copyright (c) 1998-2015 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
 *    openssl-core@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 <openssl/crypto.h>
#include <openssl/bio.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/err.h>

static STACK_OF(X509) *load_certs_from_file(const char *filename)
{
    STACK_OF(X509) *certs;
    BIO *bio;
    X509 *x;

    bio = BIO_new_file(filename, "r");

    if (bio == NULL) {
        return NULL;
    }

    certs = sk_X509_new_null();
    if (certs == NULL) {
        BIO_free(bio);
        return NULL;
    }

    ERR_set_mark();
    do {
        x = PEM_read_bio_X509(bio, NULL, 0, NULL);
        if (x != NULL && !sk_X509_push(certs, x)) {
            sk_X509_pop_free(certs, X509_free);
            BIO_free(bio);
            return NULL;
        } else if (x == NULL) {
            /*
             * We probably just ran out of certs, so ignore any errors
             * generated
             */
            ERR_pop_to_mark();
        }
    } while (x != NULL);

    BIO_free(bio);

    return certs;
}

/*
 * Test for CVE-2015-1793 (Alternate Chains Certificate Forgery)
 *
 * Chain is as follows:
 *
 * rootCA (self-signed)
 *   |
 * interCA
 *   |
 * subinterCA       subinterCA (self-signed)
 *   |                   |
 * leaf ------------------
 *   |
 * bad
 *
 * rootCA, interCA, subinterCA, subinterCA (ss) all have CA=TRUE
 * leaf and bad have CA=FALSE
 *
 * subinterCA and subinterCA (ss) have the same subject name and keys
 *
 * interCA (but not rootCA) and subinterCA (ss) are in the trusted store
 * (roots.pem)
 * leaf and subinterCA are in the untrusted list (untrusted.pem)
 * bad is the certificate being verified (bad.pem)
 *
 * Versions vulnerable to CVE-2015-1793 will fail to detect that leaf has
 * CA=FALSE, and will therefore incorrectly verify bad
 *
 */
static int test_alt_chains_cert_forgery(void)
{
    int ret = 0;
    int i;
    X509 *x = NULL;
    STACK_OF(X509) *untrusted = NULL;
    BIO *bio = NULL;
    X509_STORE_CTX *sctx = NULL;
    X509_STORE *store = NULL;
    X509_LOOKUP *lookup = NULL;

    store = X509_STORE_new();
    if (store == NULL)
        goto err;

    lookup = X509_STORE_add_lookup(store, X509_LOOKUP_file());
    if (lookup == NULL)
        goto err;
    if(!X509_LOOKUP_load_file(lookup, "certs/roots.pem", X509_FILETYPE_PEM))
        goto err;

    untrusted = load_certs_from_file("certs/untrusted.pem");

    if ((bio = BIO_new_file("certs/bad.pem", "r")) == NULL)
        goto err;

    if((x = PEM_read_bio_X509(bio, NULL, 0, NULL)) == NULL)
        goto err;

    sctx = X509_STORE_CTX_new();
    if (sctx == NULL)
        goto err;

    if (!X509_STORE_CTX_init(sctx, store, x, untrusted))
        goto err;

    i = X509_verify_cert(sctx);

    if(i == 0 && X509_STORE_CTX_get_error(sctx)
                 == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT) {
        /* This is the result we were expecting: Test passed */
        ret = 1;
    }
 err:
    X509_STORE_CTX_free(sctx);
    X509_free(x);
    BIO_free(bio);
    sk_X509_pop_free(untrusted, X509_free);
    X509_STORE_free(store);
    if (ret != 1)
        ERR_print_errors_fp(stderr);
    return ret;
}

int main(void)
{
    CRYPTO_malloc_debug_init();
    CRYPTO_set_mem_debug_options(V_CRYPTO_MDEBUG_ALL);
    CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ON);

    ERR_load_crypto_strings();
    OpenSSL_add_all_digests();

    if (!test_alt_chains_cert_forgery()) {
        fprintf(stderr, "Test alt chains cert forgery failed\n");
        return 1;
    }

    EVP_cleanup();
    CRYPTO_cleanup_all_ex_data();
    ERR_remove_thread_state(NULL);
    ERR_free_strings();
    CRYPTO_mem_leaks_fp(stderr);

    printf("PASS\n");
    return 0;
}