/*
 * Copyright (C) 2013 Red Hat
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS 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 License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */
#include "gnutls_int.h"
#include <gnutls/gnutls.h>
#include <gnutls/crypto.h>
#include <unistd.h>
#include "errors.h"
#include <fips.h>
#include <gnutls/self-test.h>
#include <stdio.h>
#include <extras/hex.h>
#include <random.h>

#include "gthreads.h"

unsigned int _gnutls_lib_state = LIB_STATE_POWERON;
#ifdef ENABLE_FIPS140

#include <dlfcn.h>

#define FIPS_KERNEL_FILE "/proc/sys/crypto/fips_enabled"
#define FIPS_SYSTEM_FILE "/etc/system-fips"

/* We provide a per-thread FIPS-mode so that an application
 * can use gnutls_fips140_set_mode() to override a specific
 * operation on a thread */
static gnutls_fips_mode_t _global_fips_mode = -1;
static _Thread_local gnutls_fips_mode_t _tfips_mode = -1;

static int _skip_integrity_checks = 0;

/* Returns:
 * a gnutls_fips_mode_t value
 */
unsigned _gnutls_fips_mode_enabled(void)
{
	unsigned f1p = 0, f2p;
	FILE* fd;
	const char *p;
	unsigned ret;

	/* We initialize this threads' mode, and
	 * the global mode if not already initialized.
	 * When the global mode is initialized, then
	 * the thread mode is copied from it. As this
	 * is called on library initialization, the
	 * _global_fips_mode is always set during app run.
	 */
	if (_tfips_mode != (gnutls_fips_mode_t)-1)
		return _tfips_mode;

	if (_global_fips_mode != (gnutls_fips_mode_t)-1) {
		return _global_fips_mode;
	}

	p = secure_getenv("GNUTLS_SKIP_FIPS_INTEGRITY_CHECKS");
	if (p && p[0] == '1') {
		_skip_integrity_checks = 1;
	}

	p = secure_getenv("GNUTLS_FORCE_FIPS_MODE");
	if (p) {
		if (p[0] == '1')
			ret = 1;
		else if (p[0] == '2')
			ret = GNUTLS_FIPS140_SELFTESTS;
		else if (p[0] == '3')
			ret = GNUTLS_FIPS140_LAX;
		else if (p[0] == '4')
			ret = GNUTLS_FIPS140_LOG;
		else
			ret = GNUTLS_FIPS140_DISABLED;

		goto exit;
	}

	fd = fopen(FIPS_KERNEL_FILE, "r");
	if (fd != NULL) {
		f1p = fgetc(fd);
		fclose(fd);
		
		if (f1p == '1') f1p = 1;
		else f1p = 0;
	}

	f2p = !access(FIPS_SYSTEM_FILE, F_OK);

	if (f1p != 0 && f2p != 0) {
		_gnutls_debug_log("FIPS140-2 mode enabled\n");
		ret = GNUTLS_FIPS140_STRICT;
		goto exit;
	}

	if (f2p != 0) {
		/* a funny state where self tests are performed
		 * and ignored */
		_gnutls_debug_log("FIPS140-2 ZOMBIE mode enabled\n");
		ret = GNUTLS_FIPS140_SELFTESTS;
		goto exit;
	}

	ret = GNUTLS_FIPS140_DISABLED;
	goto exit;

 exit:
	_global_fips_mode = ret;
	return ret;
}

/* This _fips_mode == 2 is a strange mode where checks are being
 * performed, but its output is ignored. */
void _gnutls_fips_mode_reset_zombie(void)
{
	if (_global_fips_mode == GNUTLS_FIPS140_SELFTESTS) {
		_global_fips_mode = GNUTLS_FIPS140_DISABLED;
	}
}

#define GNUTLS_LIBRARY_NAME "libgnutls.so.28"
#define NETTLE_LIBRARY_NAME "libnettle.so.4"
#define HOGWEED_LIBRARY_NAME "libhogweed.so.2"
#define GMP_LIBRARY_NAME "libgmp.so.10"

#define HMAC_SUFFIX ".hmac"
#define HMAC_SIZE 32
#define HMAC_ALGO GNUTLS_MAC_SHA256

static int get_library_path(const char* lib, const char* symbol, char* path, size_t path_size)
{
Dl_info info;
int ret;
void *dl, *sym;

	dl = dlopen(lib, RTLD_LAZY);
	if (dl == NULL)
		return gnutls_assert_val(GNUTLS_E_FILE_ERROR);

	sym = dlsym(dl, symbol);
	if (sym == NULL) {
		ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR);
		goto cleanup;
	}
	
	ret = dladdr(sym, &info);
	if (ret == 0) {
		ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR);
		goto cleanup;
	}
	
	snprintf(path, path_size, "%s", info.dli_fname);

	ret = 0;
cleanup:
	dlclose(dl);
	return ret;
}

static void get_hmac_file(char *mac_file, size_t mac_file_size, const char* orig)
{
char* p;

	p = strrchr(orig, '/');
	if (p==NULL) {
		snprintf(mac_file, mac_file_size, ".%s"HMAC_SUFFIX, orig);
		return;
	}
	snprintf(mac_file, mac_file_size, "%.*s/.%s"HMAC_SUFFIX, (int)(p-orig), orig, p+1);
}

static void get_hmac_file2(char *mac_file, size_t mac_file_size, const char* orig)
{
char* p;

	p = strrchr(orig, '/');
	if (p==NULL) {
		snprintf(mac_file, mac_file_size, "fipscheck/%s"HMAC_SUFFIX, orig);
		return;
	}
	snprintf(mac_file, mac_file_size, "%.*s/fipscheck/%s"HMAC_SUFFIX, (int)(p-orig), orig, p+1);
}

/* Run an HMAC using the key above on the library binary data. 
 * Returns true on success and false on error.
 */
static unsigned check_binary_integrity(const char* libname, const char* symbol)
{
	int ret;
	unsigned prev;
	char mac_file[GNUTLS_PATH_MAX];
	char file[GNUTLS_PATH_MAX];
	uint8_t hmac[HMAC_SIZE];
	uint8_t new_hmac[HMAC_SIZE];
	size_t hmac_size;
	gnutls_datum_t data;

	ret = get_library_path(libname, symbol, file, sizeof(file));
	if (ret < 0) {
		_gnutls_debug_log("Could not get path for library %s\n", libname);
		return 0;
	}

	_gnutls_debug_log("Loading: %s\n", file);
	ret = gnutls_load_file(file, &data);
	if (ret < 0) {
		_gnutls_debug_log("Could not load: %s\n", file);
		return gnutls_assert_val(0);
	}

	prev = _gnutls_get_lib_state();
	_gnutls_switch_lib_state(LIB_STATE_OPERATIONAL);
	ret = gnutls_hmac_fast(HMAC_ALGO, FIPS_KEY, sizeof(FIPS_KEY)-1,
		data.data, data.size, new_hmac);
	_gnutls_switch_lib_state(prev);
	
	gnutls_free(data.data);

	if (ret < 0)
		return gnutls_assert_val(0);

	/* now open the .hmac file and compare */
	get_hmac_file(mac_file, sizeof(mac_file), file);

	ret = gnutls_load_file(mac_file, &data);
	if (ret < 0) {
		get_hmac_file2(mac_file, sizeof(mac_file), file);
		ret = gnutls_load_file(mac_file, &data);
		if (ret < 0) {
			_gnutls_debug_log("Could not open %s for MAC testing: %s\n", mac_file, gnutls_strerror(ret));
			return gnutls_assert_val(0);
		}
	}

	hmac_size = hex_data_size(data.size);
	ret = gnutls_hex_decode(&data, hmac, &hmac_size);
	gnutls_free(data.data);

	if (ret < 0) {
		_gnutls_debug_log("Could not convert hex data to binary for MAC testing for %s.\n", libname);
		return gnutls_assert_val(0);
	}

	if (hmac_size != sizeof(hmac) ||
			memcmp(hmac, new_hmac, sizeof(hmac)) != 0) {
		_gnutls_debug_log("Calculated MAC for %s does not match\n", libname);
		return gnutls_assert_val(0);
	}
	_gnutls_debug_log("Successfully verified MAC for %s (%s)\n", mac_file, libname);
	
	return 1;
}

int _gnutls_fips_perform_self_checks1(void)
{
	int ret;

	_gnutls_switch_lib_state(LIB_STATE_SELFTEST);

	/* Tests the FIPS algorithms used by nettle internally.
	 * In our case we test AES-CBC since nettle's AES is used by
	 * the DRBG-AES.
	 */

	/* ciphers - one test per cipher */
	ret = gnutls_cipher_self_test(0, GNUTLS_CIPHER_AES_128_CBC);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	return 0;

error:
	_gnutls_switch_lib_state(LIB_STATE_ERROR);
	_gnutls_audit_log(NULL, "FIPS140-2 self testing part1 failed\n");

	return GNUTLS_E_SELF_TEST_ERROR;
}

int _gnutls_fips_perform_self_checks2(void)
{
	int ret;

	_gnutls_switch_lib_state(LIB_STATE_SELFTEST);

	/* Tests the FIPS algorithms */

	/* ciphers - one test per cipher */
	ret = gnutls_cipher_self_test(0, GNUTLS_CIPHER_3DES_CBC);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_cipher_self_test(0, GNUTLS_CIPHER_AES_256_GCM);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	/* MAC (includes message digest test) */
	ret = gnutls_mac_self_test(0, GNUTLS_MAC_SHA1);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_mac_self_test(0, GNUTLS_MAC_SHA224);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_mac_self_test(0, GNUTLS_MAC_SHA256);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_mac_self_test(0, GNUTLS_MAC_SHA384);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_mac_self_test(0, GNUTLS_MAC_SHA512);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	/* PK */
	ret = gnutls_pk_self_test(0, GNUTLS_PK_RSA);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_pk_self_test(0, GNUTLS_PK_DSA);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_pk_self_test(0, GNUTLS_PK_EC);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	ret = gnutls_pk_self_test(0, GNUTLS_PK_DH);
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	if (_gnutls_rnd_ops.self_test == NULL) {
		gnutls_assert();
		goto error;
	}

	/* this does not require rng initialization */
	ret = _gnutls_rnd_ops.self_test();
	if (ret < 0) {
		gnutls_assert();
		goto error;
	}

	if (_skip_integrity_checks == 0) {
		ret = check_binary_integrity(GNUTLS_LIBRARY_NAME, "gnutls_global_init");
		if (ret == 0) {
			gnutls_assert();
			goto error;
		}

		ret = check_binary_integrity(NETTLE_LIBRARY_NAME, "nettle_aes_set_encrypt_key");
		if (ret == 0) {
			gnutls_assert();
			goto error;
		}

		ret = check_binary_integrity(HOGWEED_LIBRARY_NAME, "nettle_mpz_sizeinbase_256_u");
		if (ret == 0) {
			gnutls_assert();
			goto error;
		}

		ret = check_binary_integrity(GMP_LIBRARY_NAME, "__gmpz_init");
		if (ret == 0) {
			gnutls_assert();
			goto error;
		}
	}
	
	return 0;

error:
	_gnutls_switch_lib_state(LIB_STATE_ERROR);
	_gnutls_audit_log(NULL, "FIPS140-2 self testing part 2 failed\n");

	return GNUTLS_E_SELF_TEST_ERROR;
}
#endif

/**
 * gnutls_fips140_mode_enabled:
 *
 * Checks whether this library is in FIPS140 mode. The returned
 * value corresponds to the library mode as set with
 * gnutls_fips140_set_mode().
 *
 * If gnutls_fips140_set_mode() was called with %GNUTLS_FIPS140_SET_MODE_THREAD
 * then this function will return the current thread's FIPS140 mode, otherwise
 * the global value is returned.
 *
 * Returns: return non-zero if true or zero if false.
 *
 * Since: 3.3.0
 **/
unsigned gnutls_fips140_mode_enabled(void)
{
#ifdef ENABLE_FIPS140
	unsigned ret = _gnutls_fips_mode_enabled();

	if (ret > GNUTLS_FIPS140_DISABLED)
		return ret;
#endif
	return 0;
}

/**
 * gnutls_fips140_set_mode:
 * @mode: the FIPS140-2 mode to switch to
 * @flags: should be zero or %GNUTLS_FIPS140_SET_MODE_THREAD
 *
 * That function is not thread-safe when changing the mode with no flags
 * (globally), and should be called prior to creating any threads. Its
 * behavior with no flags after threads are created is undefined.
 *
 * When the flag %GNUTLS_FIPS140_SET_MODE_THREAD is specified
 * then this call will change the FIPS140-2 mode for this particular
 * thread and not for the whole process. That way an application
 * can utilize this function to set and reset mode for specific
 * operations.
 *
 * This function never fails but will be a no-op if used when
 * the library is not in FIPS140-2 mode. When asked to switch to unknown
 * values for @mode or to %GNUTLS_FIPS140_SELFTESTS mode, the library
 * switches to %GNUTLS_FIPS140_STRICT mode.
 *
 * Since: 3.6.2
 **/
void gnutls_fips140_set_mode(gnutls_fips_mode_t mode, unsigned flags)
{
#ifdef ENABLE_FIPS140
	gnutls_fips_mode_t prev = _gnutls_fips_mode_enabled();
	if (prev == GNUTLS_FIPS140_DISABLED || prev == GNUTLS_FIPS140_SELFTESTS) {
		/* we need to run self-tests first to be in FIPS140-2 mode */
		_gnutls_audit_log(NULL, "The library should be initialized in FIPS140-2 mode to do that operation\n");
		return;
	}

	switch (mode) {
		case GNUTLS_FIPS140_STRICT:
		case GNUTLS_FIPS140_LAX:
		case GNUTLS_FIPS140_LOG:
		case GNUTLS_FIPS140_DISABLED:
			break;
		case GNUTLS_FIPS140_SELFTESTS:
			_gnutls_audit_log(NULL, "Cannot switch library to FIPS140-2 self-tests mode; defaulting to strict\n");
			mode = GNUTLS_FIPS140_STRICT;
			break;
		default:
			_gnutls_audit_log(NULL, "Cannot switch library to mode %u; defaulting to strict\n", (unsigned)mode);
			mode = GNUTLS_FIPS140_STRICT;
			break;
	}

	if (flags & GNUTLS_FIPS140_SET_MODE_THREAD)
		_tfips_mode = mode;
	else {
		_global_fips_mode = mode;
		_tfips_mode = -1;
	}
#endif
}

void _gnutls_lib_simulate_error(void)
{
	_gnutls_switch_lib_state(LIB_STATE_ERROR);
}

void _gnutls_lib_force_operational(void)
{
	_gnutls_switch_lib_state(LIB_STATE_OPERATIONAL);
}