claws-mail/src/common/ssl.c

/*
 * Claws Mail -- a GTK+ based, lightweight, and fast e-mail client
 * Copyright (C) 1999-2021 the Claws Mail team and Hiroyuki Yamamoto
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 * 
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#include "claws-features.h"
#endif

#ifdef USE_GNUTLS
#include "defs.h"

#include <stdlib.h>
#include <glib.h>
#include <glib/gi18n.h>
#include <errno.h>
#include <pthread.h>

#include "claws.h"
#include "utils.h"
#include "ssl.h"
#include "ssl_certificate.h"
#include "hooks.h"

#if GNUTLS_VERSION_NUMBER <= 0x020b00
#include <gcrypt.h>
GCRY_THREAD_OPTION_PTHREAD_IMPL;
#endif

#ifdef HAVE_LIBETPAN
#include <libetpan/mailstream_ssl.h>
#endif

#ifdef USE_PTHREAD
#include <pthread.h>
#endif

#ifdef USE_PTHREAD
typedef struct _thread_data {
	gnutls_session_t ssl;
	gboolean done;
} thread_data;
#endif

#if GNUTLS_VERSION_NUMBER < 0x030400
#define DEFAULT_GNUTLS_PRIORITY "NORMAL:-VERS-SSL3.0"
#else
#define DEFAULT_GNUTLS_PRIORITY "NORMAL"
#endif

#if GNUTLS_VERSION_NUMBER < 0x030000
/* GnuTLS 3.0 introduced new API for certificate callback,
 * gnutls_certificate_set_retrieve_function2() */

#if GNUTLS_VERSION_NUMBER <= 0x020c00
static int gnutls_client_cert_cb(gnutls_session_t session,
                               const gnutls_datum_t *req_ca_rdn, int nreqs,
                               const gnutls_pk_algorithm_t *sign_algos,
                               int sign_algos_length, gnutls_retr_st *st)
#else
static int gnutls_cert_cb(gnutls_session_t session,
                               const gnutls_datum_t *req_ca_rdn, int nreqs,
                               const gnutls_pk_algorithm_t *sign_algos,
                               int sign_algos_length, gnutls_retr2_st *st)
#endif /* GNUTLS_VERSION_NUMBER <= 0x020c00 */
{
	SSLClientCertHookData hookdata;
	SockInfo *sockinfo = (SockInfo *)gnutls_session_get_ptr(session);
	gnutls_certificate_type_t type = gnutls_certificate_type_get(session);
	gnutls_x509_crt_t crt;
	gnutls_x509_privkey_t key;

	st->ncerts = 0;

	hookdata.account = sockinfo->account;
	hookdata.cert_path = NULL;
	hookdata.password = NULL;
	hookdata.is_smtp = sockinfo->is_smtp;
	hooks_invoke(SSLCERT_GET_CLIENT_CERT_HOOKLIST, &hookdata);	

	if (hookdata.cert_path == NULL) {
		g_free(hookdata.password);
		return 0;
	}

	sockinfo->client_crt = ssl_certificate_get_x509_from_pem_file(hookdata.cert_path);
	sockinfo->client_key = ssl_certificate_get_pkey_from_pem_file(hookdata.cert_path);
	if (!(sockinfo->client_crt && sockinfo->client_key)) {
		/* try pkcs12 format */
		ssl_certificate_get_x509_and_pkey_from_p12_file(hookdata.cert_path, hookdata.password, 
			&crt, &key);
		sockinfo->client_crt = crt;
		sockinfo->client_key = key;
	}

	if (type == GNUTLS_CRT_X509 && sockinfo->client_crt && sockinfo->client_key) {
		st->ncerts = 1;
#if GNUTLS_VERSION_NUMBER <= 0x020c00
		st->type = type;
#else
		st->key_type = type;
#endif
		st->cert.x509 = &(sockinfo->client_crt);
		st->key.x509 = sockinfo->client_key;
		st->deinit_all = 0;
		g_free(hookdata.password);
		return 0;
	}
	g_free(hookdata.password);
	return 0;
}

#else /* GNUTLS_VERSION_NUMBER < 0x030000 */

static int gnutls_cert_cb(gnutls_session_t session,
		const gnutls_datum_t *req_ca_rdn,
		int nreqs,
		const gnutls_pk_algorithm_t *pk_algos,
		int pk_algos_length,
		gnutls_pcert_st **pcert,
		unsigned int *pcert_length,
		gnutls_privkey_t *privkey)
{
	SSLClientCertHookData hookdata;
	SockInfo *sockinfo = (SockInfo *)gnutls_session_get_ptr(session);
	gnutls_datum_t tmp;
	int r;

	hookdata.account = sockinfo->account;
	hookdata.cert_path = NULL;
	hookdata.password = NULL;
	hookdata.is_smtp = sockinfo->is_smtp;
	hooks_invoke(SSLCERT_GET_CLIENT_CERT_HOOKLIST, &hookdata);

	if (hookdata.cert_path == NULL) {
		g_free(hookdata.password);
		return 0;
	}

	if ((r = gnutls_load_file(hookdata.cert_path, &tmp)) != 0) {
		debug_print("couldn't load file '%s': %d\n",
				hookdata.cert_path, r);
		g_free(hookdata.password);
		return 0;
	}
	debug_print("trying to load client cert+key from file '%s'\n",
			hookdata.cert_path);

	if ((r = gnutls_pcert_import_x509_raw(&sockinfo->client_crt, &tmp,
				GNUTLS_X509_FMT_PEM, 0)) != 0) {
		debug_print("couldn't import x509 cert from PEM file '%s': %d\n",
				hookdata.cert_path, r);
		g_free(hookdata.password);
		return 0;
	}
	debug_print("loaded client certificate...\n");

	gnutls_privkey_init(&sockinfo->client_key);
	if ((r = gnutls_privkey_import_x509_raw(sockinfo->client_key, &tmp,
				GNUTLS_X509_FMT_PEM, hookdata.password, 0)) != 0) {
		debug_print("couldn't import x509 pkey from PEM file '%s': %d\n",
				hookdata.cert_path, r);
		g_free(hookdata.password);
		gnutls_privkey_deinit(sockinfo->client_key);
		return 0;
	}
	debug_print("loaded client private key...\n");

	gnutls_free(tmp.data);

	*pcert_length = 1;
	*pcert = &sockinfo->client_crt;
	*privkey = sockinfo->client_key;

	return 0;
}
#endif /* GNUTLS_VERSION_NUMBER < 0x030000 */

const gchar *claws_ssl_get_cert_file(void)
{
#ifndef G_OS_WIN32
	const char *cert_files[]={
		"/etc/ssl/cert.pem",
		"/etc/pki/tls/certs/ca-bundle.crt",
		"/etc/certs/ca-bundle.crt",
		"/etc/ssl/ca-bundle.pem",
		"/usr/share/ssl/certs/ca-bundle.crt",
		"/etc/ssl/certs/ca-certificates.crt",
		"/usr/local/ssl/certs/ca-bundle.crt",
		"/etc/apache/ssl.crt/ca-bundle.crt",
		"/usr/share/curl/curl-ca-bundle.crt",
		"/usr/share/curl/curl-ca-bundle.crt",
		"/usr/lib/ssl/cert.pem",
		NULL};
	int i;
#endif

	/* We honor this environment variable on all platforms. */
	if (g_getenv("SSL_CERT_FILE"))
		return g_getenv("SSL_CERT_FILE");

#ifndef G_OS_WIN32
	for (i = 0; cert_files[i]; i++) {
		if (is_file_exist(cert_files[i]))
			return cert_files[i];
	}
	return NULL;
#else
	return w32_get_cert_file();
#endif
}

const gchar *claws_ssl_get_cert_dir(void)
{
	if (g_getenv("SSL_CERT_DIR"))
		return g_getenv("SSL_CERT_DIR");
#ifndef G_OS_WIN32
	const char *cert_dirs[]={
		"/etc/pki/tls/certs",
		"/etc/certs",
		"/usr/share/ssl/certs",
		"/etc/ssl/certs",
		"/usr/local/ssl/certs",
		"/etc/apache/ssl.crt",
		"/usr/share/curl",
		"/usr/lib/ssl/certs",
		NULL};
	int i;
    	
	for (i = 0; cert_dirs[i]; i++) {
		if (is_dir_exist(cert_dirs[i]))
			return cert_dirs[i];
	}
	return NULL;
#else
	return NULL;
#endif
}

void ssl_init(void)
{
#if GNUTLS_VERSION_NUMBER <= 0x020b00
	gcry_control (GCRYCTL_SET_THREAD_CBS, &gcry_threads_pthread);
#endif
#ifdef HAVE_LIBETPAN
	mailstream_gnutls_init_not_required();
#endif	
	gnutls_global_init();
}

void ssl_done(void)
{
	gnutls_global_deinit();
}

#ifdef USE_PTHREAD
static void *SSL_connect_thread(void *data)
{
	thread_data *td = (thread_data *)data;
	int result = -1;

	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
	pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);

	do {
		result = gnutls_handshake(td->ssl);
	} while (result == GNUTLS_E_AGAIN || result == GNUTLS_E_INTERRUPTED);

	td->done = TRUE; /* let the caller thread join() */
	return GINT_TO_POINTER(result);
}
#endif

static gint SSL_connect_nb(gnutls_session_t ssl)
{
	int result;
#ifdef USE_PTHREAD
	thread_data *td = g_new0(thread_data, 1);
	pthread_t pt;
	void *res = NULL;
	time_t start_time = time(NULL);
	gboolean killed = FALSE;
	
	td->ssl  = ssl;
	td->done = FALSE;
	
	/* try to create a thread to initialize the SSL connection,
	 * fallback to blocking method in case of problem 
	 */
	if (pthread_create(&pt, NULL, SSL_connect_thread, td) != 0) {
		do {
			result = gnutls_handshake(td->ssl);
		} while (result == GNUTLS_E_AGAIN || result == GNUTLS_E_INTERRUPTED);
		return result;
	}
	debug_print("waiting for SSL_connect thread...\n");
	while(!td->done) {
		/* don't let the interface freeze while waiting */
		claws_do_idle();
		if (time(NULL) - start_time > 30) {
			pthread_cancel(pt);
			td->done = TRUE;
			killed = TRUE;
		}
	}

	/* get the thread's return value and clean its resources */
	pthread_join(pt, &res);
	g_free(td);
	
	if (killed) {
		res = GINT_TO_POINTER(-1);
	}
	debug_print("SSL_connect thread returned %d\n", 
			GPOINTER_TO_INT(res));
	
	return GPOINTER_TO_INT(res);
#else /* USE_PTHREAD */
	do {
		result = gnutls_handshake(ssl);
	} while (result == GNUTLS_E_AGAIN || result == GNUTLS_E_INTERRUPTED);
#endif
}

gnutls_x509_crt_t *ssl_get_certificate_chain(gnutls_session_t session, gint *list_len)
{
	const gnutls_datum_t *raw_cert_list;
	gnutls_x509_crt_t *certs = NULL;
	gboolean result = TRUE;

	*list_len = -1;
	if (!session)
		return NULL;

	raw_cert_list = gnutls_certificate_get_peers(session, list_len);

	if (raw_cert_list && gnutls_certificate_type_get(session) == GNUTLS_CRT_X509) {
		int i = 0;

		if (*list_len > 128)
			*list_len = 128;

		certs = g_malloc(sizeof(gnutls_x509_crt_t) * (*list_len));

		for(i = 0 ; i < (*list_len) ; i++) {
			int r;

			gnutls_x509_crt_init(&certs[i]);
			r = gnutls_x509_crt_import(certs[i], &raw_cert_list[i], GNUTLS_X509_FMT_DER);
			if (r < 0) {
				g_warning("cert get failure: %d %s", r, gnutls_strerror(r));

				result = FALSE;
				i--;
				break;
			}
		}
		if (!result) {
			for (; i >= 0; i--)
				gnutls_x509_crt_deinit(certs[i]);

			g_free(certs);
			*list_len = -1;

			return NULL;
		}
	}

	return certs;
}

gboolean ssl_init_socket(SockInfo *sockinfo)
{
	gnutls_session_t session;
	int r, i;
	unsigned int cert_list_length;
	gnutls_x509_crt_t *certs = NULL;
	gnutls_certificate_credentials_t xcred;

	if (gnutls_certificate_allocate_credentials (&xcred) != 0)
		return FALSE;

	r = gnutls_init(&session, GNUTLS_CLIENT);
	if (session == NULL || r != 0)
		return FALSE;

	if (sockinfo->gnutls_priority && strlen(sockinfo->gnutls_priority)) {
		r = gnutls_priority_set_direct(session, sockinfo->gnutls_priority, NULL);
		debug_print("Setting GnuTLS priority to %s, status = %d\n",
			    sockinfo->gnutls_priority, r);
	}
	else {
		gnutls_priority_set_direct(session, DEFAULT_GNUTLS_PRIORITY, NULL);
	}

	gnutls_record_disable_padding(session);

	/* If we have a host name, rather than a numerical IP address, tell
	 * gnutls to send it in the server name identification extension field,
	 * to give the server a chance to select the correct certificate in the
	 * virtual hosting case where multiple domain names are hosted on the
	 * same IP address. */
	if (sockinfo->use_tls_sni &&
			sockinfo->hostname != NULL &&
			!is_numeric_host_address(sockinfo->hostname)) {
		r = gnutls_server_name_set(session, GNUTLS_NAME_DNS,
				sockinfo->hostname, strlen(sockinfo->hostname));
		debug_print("Set GnuTLS session server name indication to %s, status = %d\n",
			    sockinfo->hostname, r);
	}

	gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, xcred);

	if (claws_ssl_get_cert_file()) {
		r = gnutls_certificate_set_x509_trust_file(xcred, claws_ssl_get_cert_file(),  GNUTLS_X509_FMT_PEM);
		if (r < 0)
			g_warning("Can't read SSL_CERT_FILE '%s': %s",
				claws_ssl_get_cert_file(), 
				gnutls_strerror(r));
	} else {
		debug_print("Can't find SSL ca-certificates file\n");
	}
	gnutls_certificate_set_verify_flags (xcred, GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT);

	gnutls_transport_set_ptr(session, (gnutls_transport_ptr_t) GINT_TO_POINTER(sockinfo->sock));

	gnutls_session_set_ptr(session, sockinfo);

#if GNUTLS_VERSION_NUMBER < 0x030000
#  if GNUTLS_VERSION_NUMBER <= 0x020c00
	gnutls_certificate_client_set_retrieve_function(xcred, gnutls_client_cert_cb);
#  else
	gnutls_certificate_set_retrieve_function(xcred, gnutls_cert_cb);
#  endif
#else
	debug_print("setting certificate callback function\n");
	gnutls_certificate_set_retrieve_function2(xcred, gnutls_cert_cb);
#endif

#if GNUTLS_VERSION_NUMBER < 0x030107
	/* Starting from GnuTLS 3.1.7, minimal size of the DH prime is
	 * set by the priority string. By default ("NORMAL"), it is 1008
	 * as of GnuTLS 3.3.0. */
	gnutls_dh_set_prime_bits(session, 1008);
#endif

	if ((r = SSL_connect_nb(session)) < 0) {
		g_warning("TLS connection failed (%s)", gnutls_strerror(r));
		gnutls_certificate_free_credentials(xcred);
		gnutls_deinit(session);
		return FALSE;
	}

	/* Get server's certificate (note: beware of dynamic allocation) */
	certs = ssl_get_certificate_chain(session, &cert_list_length);

	if (!certs) {
		gnutls_certificate_free_credentials(xcred);
		gnutls_deinit(session);
		return FALSE;
	}

	if (!ssl_certificate_check_chain(certs, cert_list_length, sockinfo->hostname, sockinfo->port,
					 sockinfo->ssl_cert_auto_accept)) {
		for (i = 0; i < cert_list_length; i++)
			gnutls_x509_crt_deinit(certs[i]);
		g_free(certs);
		gnutls_certificate_free_credentials(xcred);
		gnutls_deinit(session);
		return FALSE;
	}

	for (i = 0; i < cert_list_length; i++)
		gnutls_x509_crt_deinit(certs[i]);
	g_free(certs);

	sockinfo->ssl = session;
	sockinfo->xcred = xcred;
	return TRUE;
}

void ssl_done_socket(SockInfo *sockinfo)
{
	if (sockinfo && sockinfo->ssl) {
		if (sockinfo->xcred)
			gnutls_certificate_free_credentials(sockinfo->xcred);
		gnutls_deinit(sockinfo->ssl);
#if GNUTLS_VERSION_NUMBER < 0x030000
		if (sockinfo->client_crt)
			gnutls_x509_crt_deinit(sockinfo->client_crt);
		if (sockinfo->client_key)
			gnutls_x509_privkey_deinit(sockinfo->client_key);
		sockinfo->client_key = NULL;
		sockinfo->client_crt = NULL;
#else
		gnutls_pcert_deinit(&sockinfo->client_crt);
		gnutls_privkey_deinit(sockinfo->client_key);
#endif
		sockinfo->client_key = NULL;
		sockinfo->xcred = NULL;
		sockinfo->ssl = NULL;
	}
}

#endif /* USE_GNUTLS */