/* Extract X.509 certificate in DER form from PKCS#11 or PEM.
 *
 * Copyright © 2014-2015 Red Hat, Inc. All Rights Reserved.
 * Copyright © 2015      Intel Corporation.
 *
 * Authors: David Howells <dhowells@redhat.com>
 *          David Woodhouse <dwmw2@infradead.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the licence, or (at your option) any later version.
 */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <err.h>
#include <openssl/bio.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#if OPENSSL_VERSION_MAJOR >= 3
# define USE_PKCS11_PROVIDER
# include <openssl/provider.h>
# include <openssl/store.h>
#else
# if !defined(OPENSSL_NO_ENGINE) && !defined(OPENSSL_NO_DEPRECATED_3_0)
#  define USE_PKCS11_ENGINE
#  include <openssl/engine.h>
# endif
#endif
#include "ssl-common.h"

#define PKEY_ID_PKCS7 2

static __attribute__((noreturn))
void format(void)
{
        fprintf(stderr,
                "Usage: extract-cert <source> <dest>\n");
        exit(2);
}

static const char *key_pass;
static BIO *wb;
static char *cert_dst;
static bool verbose;

static void write_cert(X509 *x509)
{
        char buf[200];

        if (!wb) {
                wb = BIO_new_file(cert_dst, "wb");
                ERR(!wb, "%s", cert_dst);
        }
        X509_NAME_oneline(X509_get_subject_name(x509), buf, sizeof(buf));
        ERR(!i2d_X509_bio(wb, x509), "%s", cert_dst);
        if (verbose)
                fprintf(stderr, "Extracted cert: %s\n", buf);
}

static X509 *load_cert_pkcs11(const char *cert_src)
{
        X509 *cert = NULL;
#ifdef USE_PKCS11_PROVIDER
        OSSL_STORE_CTX *store;

        if (!OSSL_PROVIDER_try_load(NULL, "pkcs11", true))
                ERR(1, "OSSL_PROVIDER_try_load(pkcs11)");
        if (!OSSL_PROVIDER_try_load(NULL, "default", true))
                ERR(1, "OSSL_PROVIDER_try_load(default)");

        store = OSSL_STORE_open(cert_src, NULL, NULL, NULL, NULL);
        ERR(!store, "OSSL_STORE_open");

        while (!OSSL_STORE_eof(store)) {
                OSSL_STORE_INFO *info = OSSL_STORE_load(store);

                if (!info) {
                        drain_openssl_errors(__LINE__, 0);
                        continue;
                }
                if (OSSL_STORE_INFO_get_type(info) == OSSL_STORE_INFO_CERT) {
                        cert = OSSL_STORE_INFO_get1_CERT(info);
                        ERR(!cert, "OSSL_STORE_INFO_get1_CERT");
                }
                OSSL_STORE_INFO_free(info);
                if (cert)
                        break;
        }
        OSSL_STORE_close(store);
#elif defined(USE_PKCS11_ENGINE)
                ENGINE *e;
                struct {
                        const char *cert_id;
                        X509 *cert;
                } parms;

                parms.cert_id = cert_src;
                parms.cert = NULL;

                ENGINE_load_builtin_engines();
                drain_openssl_errors(__LINE__, 1);
                e = ENGINE_by_id("pkcs11");
                ERR(!e, "Load PKCS#11 ENGINE");
                if (ENGINE_init(e))
                        drain_openssl_errors(__LINE__, 1);
                else
                        ERR(1, "ENGINE_init");
                if (key_pass)
                        ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
                ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1);
                ERR(!parms.cert, "Get X.509 from PKCS#11");
                cert = parms.cert;
#else
                fprintf(stderr, "no pkcs11 engine/provider available\n");
                exit(1);
#endif
        return cert;
}

int main(int argc, char **argv)
{
        char *cert_src;
        char *verbose_env;

        OpenSSL_add_all_algorithms();
        ERR_load_crypto_strings();
        ERR_clear_error();

        verbose_env = getenv("KBUILD_VERBOSE");
        if (verbose_env && strchr(verbose_env, '1'))
                verbose = true;

        key_pass = getenv("KBUILD_SIGN_PIN");

        if (argc != 3)
                format();

        cert_src = argv[1];
        cert_dst = argv[2];

        if (!cert_src[0]) {
                /* Invoked with no input; create empty file */
                FILE *f = fopen(cert_dst, "wb");
                ERR(!f, "%s", cert_dst);
                fclose(f);
                exit(0);
        } else if (!strncmp(cert_src, "pkcs11:", 7)) {
                X509 *cert = load_cert_pkcs11(cert_src);

                ERR(!cert, "load_cert_pkcs11 failed");
                write_cert(cert);
        } else {
                BIO *b;
                X509 *x509;

                b = BIO_new_file(cert_src, "rb");
                ERR(!b, "%s", cert_src);

                while (1) {
                        x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
                        if (wb && !x509) {
                                unsigned long err = ERR_peek_last_error();
                                if (ERR_GET_LIB(err) == ERR_LIB_PEM &&
                                    ERR_GET_REASON(err) == PEM_R_NO_START_LINE) {
                                        ERR_clear_error();
                                        break;
                                }
                        }
                        ERR(!x509, "%s", cert_src);
                        write_cert(x509);
                }
        }

        BIO_free(wb);

        return 0;
}