Commit ce671a6d authored by Nikos Mavrogiannopoulos's avatar Nikos Mavrogiannopoulos Committed by Nikos Mavrogiannopoulos

priorities: introduced %FORCE_ETM

This introduces a priority string option to force encrypt-then-mac
during negotiation, to prevent negotiating the legacy CBC ciphersuites.

Resolves #472Signed-off-by: Nikos Mavrogiannopoulos's avatarNikos Mavrogiannopoulos <nmav@gnutls.org>
parent 62248b6a
Pipeline #23684733 passed with stage
in 127 minutes and 11 seconds
......@@ -1350,6 +1350,10 @@ in certificates.
will disable the encrypt-then-mac TLS extension (RFC7366). This is
implied by the %COMPAT keyword.
@item %FORCE_ETM @tab
negotiate CBC ciphersuites only when both sides of the connection support
encrypt-then-mac TLS extension (RFC7366).
@item %DISABLE_SAFE_RENEGOTIATION @tab
will completely disable safe renegotiation
completely. Do not use unless you know what you are doing.
......
......@@ -1405,6 +1405,14 @@ const char *gnutls_cipher_suite_info(size_t idx,
continue; \
}
#define CIPHER_CHECK(algo) \
if (session->internals.priorities->force_etm && !have_etm) { \
const cipher_entry_st *_cipher; \
_cipher = cipher_to_entry(algo); \
if (_cipher == NULL || _gnutls_cipher_type(_cipher) == CIPHER_BLOCK) \
continue; \
}
#define KX_SRP_CHECKS(kx, action) \
if (kx == GNUTLS_KX_SRP_RSA || kx == GNUTLS_KX_SRP_DSS) { \
if (!_gnutls_get_cred(session, GNUTLS_CRD_SRP)) { \
......@@ -1450,11 +1458,20 @@ _gnutls_figure_common_ciphersuite(gnutls_session_t session,
gnutls_credentials_type_t cred_type = GNUTLS_CRD_CERTIFICATE; /* default for TLS1.3 */
unsigned int no_cert_found = 0;
const gnutls_group_entry_st *sgroup = NULL;
gnutls_ext_priv_data_t epriv;
unsigned have_etm = 0;
if (version == NULL) {
return gnutls_assert_val(GNUTLS_E_NO_CIPHER_SUITES);
}
/* we figure whether etm is negotiated by checking the raw extension data
* because we only set (security_params) EtM to true only after the ciphersuite is
* negotiated. */
ret = _gnutls_hello_ext_get_priv(session, GNUTLS_EXTENSION_ETM, &epriv);
if (ret >= 0 && ((intptr_t)epriv) != 0)
have_etm = 1;
/* If we didn't receive the supported_groups extension, then
* we should assume that SECP256R1 is supported; that is required
* by RFC4492, probably to allow SSLv2 hellos negotiate elliptic curve
......@@ -1474,6 +1491,8 @@ _gnutls_figure_common_ciphersuite(gnutls_session_t session,
kx = peer_clist->entry[i]->kx_algorithm;
CIPHER_CHECK(peer_clist->entry[i]->block_algorithm);
if (!version->tls13_sem)
cred_type = _gnutls_map_kx_get_cred(kx, 1);
......@@ -1510,6 +1529,8 @@ _gnutls_figure_common_ciphersuite(gnutls_session_t session,
for (j = 0; j < session->internals.priorities->cs.size; j++) {
VERSION_CHECK(session->internals.priorities->cs.entry[j]);
CIPHER_CHECK(session->internals.priorities->cs.entry[j]->block_algorithm);
for (i = 0; i < peer_clist->size; i++) {
_gnutls_debug_log("checking %.2x.%.2x (%s) for compatibility\n",
(unsigned)peer_clist->entry[i]->id[0],
......
......@@ -900,6 +900,7 @@ struct gnutls_priority_st {
bool no_tickets;
bool have_cbc;
bool have_psk;
bool force_etm;
unsigned int additional_verify_flags;
/* TLS_FALLBACK_SCSV */
......
......@@ -1825,7 +1825,6 @@ read_server_hello(gnutls_session_t session,
*/
if (!vers->tls13_sem &&
client_check_if_resuming(session, session_id, session_id_len) == 0) {
ret =
_gnutls_parse_hello_extensions(session, GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO,
GNUTLS_EXT_MANDATORY,
......@@ -1878,6 +1877,14 @@ read_server_hello(gnutls_session_t session,
if (ret < 0)
return gnutls_assert_val(ret);
/* check if EtM is required */
if (!vers->tls13_sem && session->internals.priorities->force_etm && !session->security_parameters.etm) {
const cipher_entry_st *cipher = cipher_to_entry(session->security_parameters.cs->block_algorithm);
if (_gnutls_cipher_type(cipher) == CIPHER_BLOCK)
return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);
}
ret =
_gnutls_parse_hello_extensions(session,
ext_parse_flag,
......
......@@ -809,6 +809,10 @@ static void enable_no_etm(gnutls_priority_t c)
{
c->_no_etm = 1;
}
static void enable_force_etm(gnutls_priority_t c)
{
c->force_etm = 1;
}
static void enable_no_tickets(gnutls_priority_t c)
{
c->no_tickets = 1;
......
......@@ -10,6 +10,7 @@ DUMBFW, enable_dumbfw
NO_EXTENSIONS, enable_no_extensions
NO_TICKETS, enable_no_tickets
NO_ETM, enable_no_etm
FORCE_ETM, enable_force_etm
NO_SESSION_HASH, enable_no_ext_master_secret
STATELESS_COMPRESSION, dummy_func
VERIFY_ALLOW_BROKEN, enable_verify_allow_broken
......
......@@ -153,7 +153,7 @@ ctests += mini-record-2 simple gnutls_hmac_fast set_pkcs12_cred cert certuniquei
pubkey-import-export sign-is-secure spki spki-abstract rsa-rsa-pss \
mini-dtls-fork mini-dtls-pthread mini-key-material x509cert-invalid \
tls-ext-register tls-supplemental mini-dtls0-9 duplicate-extensions \
record-retvals mini-server-name tls-etm x509-cert-callback alerts \
record-retvals mini-server-name tls-etm tls-force-etm x509-cert-callback alerts \
client-sign-md5-rep tls12-invalid-key-exchanges session-rdn-read \
tls13-cert-key-exchange x509-cert-callback-ocsp gnutls_ocsp_resp_list_import2 \
server-sign-md5-rep privkey-keygen mini-tls-nonblock no-signal pkcs7-gen dtls-etm \
......
/*
* Copyright (C) 2015-2018 Red Hat, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* GnuTLS 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.
*
* GnuTLS 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 Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#if defined(_WIN32)
int main()
{
exit(77);
}
#else
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#include <gnutls/dtls.h>
#include <signal.h>
#include <assert.h>
#include "utils.h"
#include "cert-common.h"
/* This program tests whether forced EtM is negotiated as expected.
*/
static void server_log_func(int level, const char *str)
{
fprintf(stderr, "server|<%d>| %s", level, str);
}
static void client_log_func(int level, const char *str)
{
fprintf(stderr, "client|<%d>| %s", level, str);
}
#define MAX_BUF 1024
static void client(int fd, const char *prio, unsigned etm, int eret)
{
int ret;
char buffer[MAX_BUF + 1];
gnutls_anon_client_credentials_t anoncred;
gnutls_certificate_credentials_t x509_cred;
gnutls_session_t session;
/* Need to enable anonymous KX specifically. */
global_init();
if (debug) {
gnutls_global_set_log_function(client_log_func);
gnutls_global_set_log_level(7);
}
gnutls_anon_allocate_client_credentials(&anoncred);
gnutls_certificate_allocate_credentials(&x509_cred);
assert(gnutls_init(&session, GNUTLS_CLIENT)>=0);
gnutls_handshake_set_timeout(session, 20 * 1000);
/* Use default priorities */
assert(gnutls_priority_set_direct(session, prio, NULL)>=0);
/* put the anonymous credentials to the current session
*/
gnutls_credentials_set(session, GNUTLS_CRD_ANON, anoncred);
gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
gnutls_transport_set_int(session, fd);
/* Perform the TLS handshake
*/
do {
ret = gnutls_handshake(session);
}
while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
if (eret < 0) {
if (eret != ret) {
fail("client: Handshake failed with unexpected error: %s\n", gnutls_strerror(ret));
}
goto end;
}
if (ret < 0) {
fail("client: Handshake failed: %s\n", gnutls_strerror(ret));
} else {
if (debug)
success("client: Handshake was completed\n");
}
if (debug)
success("client: TLS version is: %s\n",
gnutls_protocol_get_name
(gnutls_protocol_get_version(session)));
if (etm != 0 && gnutls_session_etm_status(session) == 0) {
fail("client: EtM was not negotiated with %s!\n", prio);
exit(1);
} else if (etm == 0 && gnutls_session_etm_status(session) != 0) {
fail("client: EtM was negotiated with %s!\n", prio);
exit(1);
}
if (etm != 0 && ((gnutls_session_get_flags(session) & GNUTLS_SFLAGS_ETM) == 0)) {
fail("client: EtM was not negotiated with %s!\n", prio);
exit(1);
} else if (etm == 0 && ((gnutls_session_get_flags(session) & GNUTLS_SFLAGS_ETM) != 0)) {
fail("client: EtM was negotiated with %s!\n", prio);
exit(1);
}
do {
do {
ret = gnutls_record_recv(session, buffer, MAX_BUF);
} while (ret == GNUTLS_E_AGAIN
|| ret == GNUTLS_E_INTERRUPTED);
} while (ret > 0);
if (ret == 0) {
if (debug)
success
("client: Peer has closed the TLS connection\n");
goto end;
} else if (ret < 0) {
if (ret != 0) {
fail("client: Error: %s\n", gnutls_strerror(ret));
exit(1);
}
}
gnutls_bye(session, GNUTLS_SHUT_WR);
end:
close(fd);
gnutls_deinit(session);
gnutls_anon_free_client_credentials(anoncred);
gnutls_certificate_free_credentials(x509_cred);
gnutls_global_deinit();
}
static void server(int fd, const char *prio, unsigned etm, int eret)
{
int ret;
char buffer[MAX_BUF + 1];
gnutls_session_t session;
gnutls_anon_server_credentials_t anoncred;
gnutls_certificate_credentials_t x509_cred;
unsigned to_send = sizeof(buffer)/4;
/* this must be called once in the program
*/
global_init();
memset(buffer, 0, sizeof(buffer));
if (debug) {
gnutls_global_set_log_function(server_log_func);
gnutls_global_set_log_level(4711);
}
gnutls_certificate_allocate_credentials(&x509_cred);
gnutls_certificate_set_x509_key_mem(x509_cred, &server_cert,
&server_key,
GNUTLS_X509_FMT_PEM);
gnutls_anon_allocate_server_credentials(&anoncred);
assert(gnutls_init(&session, GNUTLS_SERVER)>=0);
gnutls_handshake_set_timeout(session, 20 * 1000);
/* avoid calling all the priority functions, since the defaults
* are adequate.
*/
assert(gnutls_priority_set_direct(session, prio, NULL) >= 0);
gnutls_credentials_set(session, GNUTLS_CRD_ANON, anoncred);
gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
gnutls_transport_set_int(session, fd);
do {
ret = gnutls_handshake(session);
} while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
if (eret < 0) {
if (eret != -1 && eret != ret) {
fail("server: Handshake failed with unexpected error: %s\n", gnutls_strerror(ret));
}
goto end;
}
if (ret < 0) {
close(fd);
gnutls_deinit(session);
fail("server: Handshake has failed (%s)\n\n",
gnutls_strerror(ret));
}
if (etm != 0 && gnutls_session_etm_status(session) == 0) {
fail("server: EtM was not negotiated with %s!\n", prio);
exit(1);
} else if (etm == 0 && gnutls_session_etm_status(session) != 0) {
fail("server: EtM was negotiated with %s!\n", prio);
exit(1);
}
if (etm != 0 && ((gnutls_session_get_flags(session) & GNUTLS_SFLAGS_ETM) == 0)) {
fail("server: EtM was not negotiated with %s!\n", prio);
exit(1);
} else if (etm == 0 && ((gnutls_session_get_flags(session) & GNUTLS_SFLAGS_ETM) != 0)) {
fail("server: EtM was negotiated with %s!\n", prio);
exit(1);
}
if (debug)
success("server: Handshake was completed\n");
if (debug)
success("server: TLS version is: %s\n",
gnutls_protocol_get_name
(gnutls_protocol_get_version(session)));
do {
do {
ret =
gnutls_record_send(session, buffer,
sizeof(buffer));
} while (ret == GNUTLS_E_AGAIN
|| ret == GNUTLS_E_INTERRUPTED);
if (ret < 0) {
fail("Error sending %d byte packet: %s\n", to_send,
gnutls_strerror(ret));
}
to_send++;
}
while (to_send < 64);
to_send = -1;
/* do not wait for the peer to close the connection.
*/
gnutls_bye(session, GNUTLS_SHUT_WR);
end:
close(fd);
gnutls_deinit(session);
gnutls_anon_free_server_credentials(anoncred);
gnutls_certificate_free_credentials(x509_cred);
gnutls_global_deinit();
if (debug)
success("server: finished\n");
}
struct test_st {
const char *name;
const char *server_prio;
const char *client_prio;
unsigned etm;
int client_err;
int server_err;
};
static void start(struct test_st *test)
{
int fd[2];
int ret, status;
pid_t child;
success("trying: %s\n", test->name);
ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fd);
if (ret < 0) {
perror("socketpair");
exit(1);
}
child = fork();
if (child < 0) {
perror("fork");
fail("fork");
exit(1);
}
if (child) {
/* parent */
close(fd[1]);
server(fd[0], test->server_prio, test->etm, test->server_err);
wait(&status);
check_wait_status(status);
} else {
close(fd[0]);
client(fd[1], test->client_prio, test->etm, test->client_err);
exit(0);
}
}
#define AES_CBC "NONE:+VERS-TLS1.0:-CIPHER-ALL:+AES-128-CBC:+SHA1:+SIGN-ALL:+COMP-ALL:+ANON-ECDH:+CURVE-ALL"
#define AES_CBC_SHA256 "NONE:+VERS-TLS1.2:-CIPHER-ALL:+RSA:+AES-128-CBC:+AES-256-CBC:+SHA256:+SIGN-ALL:+COMP-ALL:+ANON-ECDH:+CURVE-ALL"
#define AES_GCM "NONE:+VERS-TLS1.2:-CIPHER-ALL:+RSA:+AES-128-GCM:+MAC-ALL:+SIGN-ALL:+COMP-ALL:+ANON-ECDH:+CURVE-ALL"
#define AES_CBC_TLS12 "NONE:+VERS-TLS1.2:-CIPHER-ALL:+RSA:+AES-128-CBC:+MAC-ALL:+SIGN-ALL:+COMP-ALL:+ANON-ECDH:+CURVE-ALL"
static void ch_handler(int sig)
{
return;
}
static struct test_st tests[] = {
{
.name = "aes-cbc-hmac-sha1 with force etm",
.server_prio = AES_CBC":%FORCE_ETM",
.client_prio = AES_CBC":%FORCE_ETM",
.etm = 1
},
{
.name = "aes-cbc-hmac-sha256 with force etm",
.server_prio = AES_CBC_SHA256":%FORCE_ETM",
.client_prio = AES_CBC_SHA256":%FORCE_ETM",
.etm = 1
},
{
.name = "server aes-cbc-hmac-sha1 with force etm, gcm fallback",
.server_prio = AES_CBC_TLS12":+AES-128-GCM:%FORCE_ETM",
.client_prio = AES_CBC_TLS12":+AES-128-GCM:%NO_ETM",
.etm = 0
},
{
.name = "aes-gcm with force etm",
.server_prio = AES_GCM":%FORCE_ETM",
.client_prio = AES_GCM":%FORCE_ETM",
.etm = 0
},
{
.name = "server aes-cbc-hmac-sha1 with force etm failure",
.server_prio = AES_CBC":%FORCE_ETM",
.client_prio = AES_CBC":%NO_ETM",
.etm = 0,
.client_err = GNUTLS_E_PREMATURE_TERMINATION,
.server_err = GNUTLS_E_NO_CIPHER_SUITES
},
{
.name = "client aes-cbc-hmac-sha1 with force etm failure",
.server_prio = AES_CBC":%NO_ETM",
.client_prio = AES_CBC":%FORCE_ETM",
.etm = 0,
.client_err = GNUTLS_E_UNWANTED_ALGORITHM,
.server_err = -1
}
};
void doit(void)
{
unsigned i;
signal(SIGCHLD, ch_handler);
for (i=0;i<sizeof(tests)/sizeof(tests[0]);i++) {
start(&tests[i]);
}
}
#endif /* _WIN32 */
......@@ -16,9 +16,8 @@
* 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 GnuTLS; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
* 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/>
*/
#ifndef UTILS_H
......
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