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gnutls-dtls.c
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gnutls-dtls.c
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/*
* OpenConnect (SSL + DTLS) VPN client
*
* Copyright © 2008-2016 Intel Corporation.
*
* Author: David Woodhouse <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* version 2.1, as published by the Free Software Foundation.
*
* 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
* Lesser General Public License for more details.
*/
#include <config.h>
#include "gnutls.h"
#include <gnutls/dtls.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#ifndef _WIN32
#include <netinet/in.h>
#include <sys/socket.h>
#endif
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#if GNUTLS_VERSION_NUMBER < 0x030400
# define GNUTLS_CIPHER_CHACHA20_POLY1305 23
#endif
#if GNUTLS_VERSION_NUMBER >= 0x030801 && !defined(GNUTLS_NO_EXTENSIONS)
/* XX: GNUTLS_NO_EXTENSIONS was renamed in GnuTLS v3.8.1. A
* backwards-compatibility shim was added in a subsequent commit, but
* not yet released.
*/
# define GNUTLS_NO_EXTENSIONS GNUTLS_NO_DEFAULT_EXTENSIONS
#endif
/* sets the DTLS MTU and returns the actual tunnel MTU */
unsigned dtls_set_mtu(struct openconnect_info *vpninfo, unsigned mtu)
{
gnutls_dtls_set_mtu(vpninfo->dtls_ssl, mtu);
return gnutls_dtls_get_data_mtu(vpninfo->dtls_ssl);
}
struct {
const char *name;
gnutls_protocol_t version;
gnutls_cipher_algorithm_t cipher;
gnutls_kx_algorithm_t kx;
gnutls_mac_algorithm_t mac;
const char *prio;
const char *min_gnutls_version;
int cisco_dtls12;
} gnutls_dtls_ciphers[] = {
{ "DHE-RSA-AES128-SHA", GNUTLS_DTLS0_9, GNUTLS_CIPHER_AES_128_CBC, GNUTLS_KX_DHE_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS0.9:+COMP-NULL:+AES-128-CBC:+SHA1:+DHE-RSA:+SIGN-ALL:%COMPAT", "3.0.0" },
{ "DHE-RSA-AES256-SHA", GNUTLS_DTLS0_9, GNUTLS_CIPHER_AES_256_CBC, GNUTLS_KX_DHE_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS0.9:+COMP-NULL:+AES-256-CBC:+SHA1:+DHE-RSA:+SIGN-ALL:%COMPAT", "3.0.0" },
{ "AES128-SHA", GNUTLS_DTLS0_9, GNUTLS_CIPHER_AES_128_CBC, GNUTLS_KX_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS0.9:+COMP-NULL:+AES-128-CBC:+SHA1:+RSA:+SIGN-ALL:%COMPAT", "3.0.0" },
{ "AES256-SHA", GNUTLS_DTLS0_9, GNUTLS_CIPHER_AES_256_CBC, GNUTLS_KX_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS0.9:+COMP-NULL:+AES-256-CBC:+SHA1:+RSA:+SIGN-ALL:%COMPAT", "3.0.0" },
{ "DES-CBC3-SHA", GNUTLS_DTLS0_9, GNUTLS_CIPHER_3DES_CBC, GNUTLS_KX_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS0.9:+COMP-NULL:+3DES-CBC:+SHA1:+RSA:+SIGN-ALL:%COMPAT", "3.0.0" },
{ "OC-DTLS1_2-AES128-GCM", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_128_GCM, GNUTLS_KX_RSA, GNUTLS_MAC_AEAD,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-128-GCM:+AEAD:+RSA:%COMPAT:+SIGN-ALL", "3.2.7" },
{ "OC-DTLS1_2-AES256-GCM", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_256_GCM, GNUTLS_KX_RSA, GNUTLS_MAC_AEAD,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-256-GCM:+AEAD:+RSA:%COMPAT:+SIGN-ALL", "3.2.7" },
{ "OC2-DTLS1_2-CHACHA20-POLY1305", GNUTLS_DTLS1_2, GNUTLS_CIPHER_CHACHA20_POLY1305, GNUTLS_KX_PSK, GNUTLS_MAC_AEAD,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+CHACHA20-POLY1305:+AEAD:+PSK:%COMPAT:+SIGN-ALL", "3.4.8" },
/* Cisco X-DTLS12-CipherSuite: values */
{ "DHE-RSA-AES128-SHA", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_128_CBC, GNUTLS_KX_DHE_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-128-CBC:+SHA1:+DHE-RSA:+SIGN-ALL:%COMPAT", "3.0.0", 1 },
{ "DHE-RSA-AES256-SHA", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_256_CBC, GNUTLS_KX_DHE_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-256-CBC:+SHA1:+DHE-RSA:+SIGN-ALL:%COMPAT", "3.0.0", 1 },
{ "AES128-SHA", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_128_CBC, GNUTLS_KX_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-128-CBC:+SHA1:+RSA:+SIGN-ALL:%COMPAT", "3.0.0", 1 },
{ "AES256-SHA", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_256_CBC, GNUTLS_KX_RSA, GNUTLS_MAC_SHA1,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-256-CBC:+SHA1:+RSA:+SIGN-ALL:%COMPAT", "3.0.0", 1 },
{ "ECDHE-RSA-AES256-GCM-SHA384", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_256_GCM, GNUTLS_KX_ECDHE_RSA, GNUTLS_MAC_AEAD,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-256-GCM:+AEAD:+ECDHE-RSA:+SIGN-ALL:%COMPAT", "3.2.7", 1 },
{ "ECDHE-RSA-AES128-GCM-SHA256", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_128_GCM, GNUTLS_KX_ECDHE_RSA, GNUTLS_MAC_AEAD,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-128-GCM:+AEAD:+ECDHE-RSA:+SIGN-ALL:%COMPAT", "3.2.7", 1 },
{ "AES128-GCM-SHA256", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_128_GCM, GNUTLS_KX_RSA, GNUTLS_MAC_AEAD,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-128-GCM:+AEAD:+RSA:+SIGN-ALL:%COMPAT", "3.2.7", 1 },
{ "AES256-GCM-SHA384", GNUTLS_DTLS1_2, GNUTLS_CIPHER_AES_256_GCM, GNUTLS_KX_RSA, GNUTLS_MAC_AEAD,
"NONE:+VERS-DTLS1.2:+COMP-NULL:+AES-256-GCM:+AEAD:+RSA:+SIGN-ALL:%COMPAT", "3.2.7", 1 },
/* NB. We agreed that any new cipher suites probably shouldn't use
* Cisco's session resume hack (which ties us to a specific version
* of DTLS). Instead, we'll use GNUTLS_KX_PSK and let it negotiate
* the session properly. We might want to wait for
* draft-jay-tls-psk-identity-extension before we do that. */
};
#if GNUTLS_VERSION_NUMBER < 0x030009
void gather_dtls_ciphers(struct openconnect_info *vpninfo, struct oc_text_buf *buf,
struct oc_text_buf *buf12)
{
int i, first = 1;
for (i = 0; i < ARRAY_SIZE(gnutls_dtls_ciphers); i++) {
if (!gnutls_dtls_ciphers[i].cisco_dtls12 &&
gnutls_check_version(gnutls_dtls_ciphers[i].min_gnutls_version)) {
buf_append(buf, "%s%s", first ? "" : ":",
gnutls_dtls_ciphers[i].name);
first = 0;
}
}
}
#else
void gather_dtls_ciphers(struct openconnect_info *vpninfo, struct oc_text_buf *buf,
struct oc_text_buf *buf12)
{
/* only enable the ciphers that would have been negotiated in the TLS channel */
unsigned i, j;
int ret;
unsigned idx;
gnutls_cipher_algorithm_t cipher;
gnutls_mac_algorithm_t mac;
gnutls_priority_t cache;
uint32_t used = 0;
buf_append(buf, "PSK-NEGOTIATE");
ret = gnutls_priority_init(&cache, vpninfo->ciphersuite_config, NULL);
if (ret < 0) {
buf->error = -EIO;
return;
}
for (j=0; ; j++) {
ret = gnutls_priority_get_cipher_suite_index(cache, j, &idx);
if (ret == GNUTLS_E_UNKNOWN_CIPHER_SUITE)
continue;
else if (ret < 0)
break;
if (gnutls_cipher_suite_info(idx, NULL, NULL, &cipher, &mac, NULL) != NULL) {
for (i = 0; i < ARRAY_SIZE(gnutls_dtls_ciphers); i++) {
if (used & (1 << i))
continue;
if (gnutls_dtls_ciphers[i].mac == mac && gnutls_dtls_ciphers[i].cipher == cipher) {
/* This cipher can be supported. Decide whether which list it lives
* in. Cisco's DTLSv1.2 options need to go into a separate
* into a separate X-DTLS12-CipherSuite header for some reason... */
struct oc_text_buf *list;
if (gnutls_dtls_ciphers[i].cisco_dtls12)
list = buf12;
else
list = buf;
if (list && list->pos)
buf_append(list, ":%s", gnutls_dtls_ciphers[i].name);
else
buf_append(list, "%s", gnutls_dtls_ciphers[i].name);
used |= (1 << i);
break;
}
}
}
}
gnutls_priority_deinit(cache);
}
#endif
/* This enables a DTLS protocol negotiation. The new negotiation is as follows:
*
* If the client's X-DTLS-CipherSuite contains the "PSK-NEGOTIATE" keyword,
* the server will reply with "X-DTLS-CipherSuite: PSK-NEGOTIATE" and will
* enable DTLS-PSK negotiation on the DTLS channel. This allows the protocol
* to use new DTLS versions, as well as new DTLS ciphersuites, as long as
* they are also permitted by the system crypto policy in use.
*
* That change still requires to client to pretend it is resuming by setting
* in the TLS ClientHello the session ID provided by the X-DTLS-Session-ID
* header. That is, because there is no TLS extension we can use to set an
* identifier in the client hello (draft-jay-tls-psk-identity-extension
* could be used in the future). The session is not actually resumed.
*/
static int start_dtls_psk_handshake(struct openconnect_info *vpninfo, gnutls_session_t dtls_ssl)
{
gnutls_datum_t key;
struct oc_text_buf *prio;
int err;
if (!vpninfo->https_sess) {
vpn_progress(vpninfo, PRG_INFO,
_("Deferring DTLS resumption until CSTP generates a PSK\n"));
return -EAGAIN;
}
prio = buf_alloc();
buf_append(prio, "%s:-VERS-TLS-ALL:+VERS-DTLS-ALL:-KX-ALL:+PSK", vpninfo->ciphersuite_config);
if (buf_error(prio)) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to generate DTLS priority string\n"));
return buf_free(prio);
}
err = gnutls_priority_set_direct(dtls_ssl, prio->data, NULL);
if (err) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to set DTLS priority: '%s': %s\n"),
prio->data, gnutls_strerror(err));
goto fail;
}
/* set our session identifier match the application ID; we do that in addition
* to the extension which contains the same information in order to deprecate
* the latter. The reason is that the session ID field is a field not used
* with TLS1.3 (and DTLS1.3), and as such we can rely on it being available to
* us, while avoiding a custom extension which requires standardization.
*/
if (vpninfo->dtls_app_id_size > 0) {
gnutls_datum_t id = {vpninfo->dtls_app_id, vpninfo->dtls_app_id_size};
gnutls_session_set_id(dtls_ssl, &id);
}
/* set PSK credentials */
err = gnutls_psk_allocate_client_credentials(&vpninfo->psk_cred);
if (err < 0) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to allocate credentials: %s\n"),
gnutls_strerror(err));
goto fail;
}
/* generate key */
/* we should have used gnutls_prf_rfc5705() but since we don't use
* the RFC5705 context, the output is identical with gnutls_prf(). The
* latter is available in much earlier versions of gnutls. */
err = gnutls_prf(vpninfo->https_sess, PSK_LABEL_SIZE, PSK_LABEL,
0, 0, 0, PSK_KEY_SIZE, (char *)vpninfo->dtls_secret);
if (err < 0) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to generate DTLS key: %s\n"),
gnutls_strerror(err));
goto fail;
}
key.data = vpninfo->dtls_secret;
key.size = PSK_KEY_SIZE;
/* we set an arbitrary username here. We cannot take advantage of the
* username field to send our ID to the server, since the username in TLS-PSK
* is sent after the server-hello. */
err = gnutls_psk_set_client_credentials(vpninfo->psk_cred, "psk", &key, 0);
if (err < 0) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to set DTLS key: %s\n"),
gnutls_strerror(err));
goto fail;
}
err = gnutls_credentials_set(dtls_ssl, GNUTLS_CRD_PSK, vpninfo->psk_cred);
if (err) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to set DTLS PSK credentials: %s\n"),
gnutls_strerror(err));
goto fail;
}
buf_free(prio);
return 0;
fail:
buf_free(prio);
gnutls_psk_free_client_credentials(vpninfo->psk_cred);
vpninfo->psk_cred = NULL;
return -EINVAL;
}
static int start_dtls_resume_handshake(struct openconnect_info *vpninfo, gnutls_session_t dtls_ssl)
{
gnutls_datum_t master_secret, session_id;
int err;
int cipher;
for (cipher = 0; cipher < ARRAY_SIZE(gnutls_dtls_ciphers); cipher++) {
if (gnutls_dtls_ciphers[cipher].cisco_dtls12 != vpninfo->dtls12 ||
gnutls_check_version(gnutls_dtls_ciphers[cipher].min_gnutls_version) == NULL)
continue;
if (!strcmp(vpninfo->dtls_cipher, gnutls_dtls_ciphers[cipher].name))
goto found_cipher;
}
vpn_progress(vpninfo, PRG_ERR, _("Unknown DTLS parameters for requested CipherSuite '%s'\n"),
vpninfo->dtls_cipher);
return -EINVAL;
found_cipher:
err = gnutls_priority_set_direct(dtls_ssl,
gnutls_dtls_ciphers[cipher].prio,
NULL);
if (err) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to set DTLS priority: '%s': %s\n"),
gnutls_dtls_ciphers[cipher].prio, gnutls_strerror(err));
return -EINVAL;
}
gnutls_record_disable_padding(dtls_ssl);
master_secret.data = vpninfo->dtls_secret;
master_secret.size = sizeof(vpninfo->dtls_secret);
session_id.data = vpninfo->dtls_session_id;
session_id.size = sizeof(vpninfo->dtls_session_id);
err = gnutls_session_set_premaster(dtls_ssl, GNUTLS_CLIENT, gnutls_dtls_ciphers[cipher].version,
gnutls_dtls_ciphers[cipher].kx, gnutls_dtls_ciphers[cipher].cipher,
gnutls_dtls_ciphers[cipher].mac, GNUTLS_COMP_NULL,
&master_secret, &session_id);
if (err) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to set DTLS session parameters: %s\n"),
gnutls_strerror(err));
return -EINVAL;
}
return 0;
}
static int start_dtls_anon_handshake(struct openconnect_info *vpninfo, gnutls_session_t dtls_ssl)
{
char *prio = vpninfo->ciphersuite_config;
int ret;
/*
* Use the same cred store as for the HTTPS session. That has
* our own verify_peer() callback installed, and will validate
* just like we do for the HTTPS service.
*
* There is also perhaps a case to be made for *only* accepting
* precisely the same cert that we get from the HTTPS service,
* but we tried that for EAP-TTLS in the Pulse protocol and the
* theory was disproven, so we ended up doing this there too.
*/
gnutls_credentials_set(dtls_ssl, GNUTLS_CRD_CERTIFICATE, vpninfo->https_cred);
/* The F5 BIG-IP server before v16, will crap itself if we
* even *try* to do DTLSv1.2 */
if (!vpninfo->dtls12 &&
asprintf(&prio, "%s:-VERS-DTLS1.2:+VERS-DTLS1.0",
vpninfo->ciphersuite_config) < 0)
return -ENOMEM;
ret = gnutls_priority_set_direct(dtls_ssl, prio ? : vpninfo->ciphersuite_config,
NULL);
if (ret) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to set DTLS priority: '%s': %s\n"),
prio, gnutls_strerror(ret));
}
if (prio != vpninfo->ciphersuite_config)
free(prio);
return ret;
}
/*
* GnuTLS version between 3.6.3 and 3.6.12 send zero'ed ClientHello. Make sure
* we are not hitting that bug. Adapted from:
* https://gitlab.com/gnutls/gnutls/-/blob/3.6.13/tests/tls_hello_random_value.c
*/
static int check_client_hello_random(gnutls_session_t ttls_sess, unsigned int type,
unsigned hook, unsigned int incoming, const gnutls_datum_t *msg)
{
unsigned non_zero = 0, i;
struct openconnect_info *vpninfo = (struct openconnect_info *)gnutls_session_get_ptr(ttls_sess);
if (type == GNUTLS_HANDSHAKE_CLIENT_HELLO && hook == GNUTLS_HOOK_POST) {
gnutls_datum_t buf;
gnutls_session_get_random(ttls_sess, &buf, NULL);
if (buf.size != 32) {
vpn_progress(vpninfo, PRG_ERR,
_("GnuTLS used %d ClientHello random bytes; this should never happen\n"),
buf.size);
return GNUTLS_E_INVALID_REQUEST;
}
for (i = 0; i < buf.size; ++i) {
if (buf.data[i] != 0) {
non_zero++;
}
}
/* The GnuTLS bug was that *all* bytes were zero, but as part of the unit test
* they also slipped in a coincidental check on how well the random number
* generator is behaving. Eight or more zeroes is a bad thing whatever the
* reason for it. So we have the same check. */
if (non_zero <= 8) {
/* TODO: mention CVE number in log message once it's assigned */
vpn_progress(vpninfo, PRG_ERR,
_("GnuTLS sent insecure ClientHello random. Upgrade to 3.6.13 or newer.\n"));
return GNUTLS_E_INVALID_REQUEST;
}
}
return 0;
}
int start_dtls_handshake(struct openconnect_info *vpninfo, int dtls_fd)
{
gnutls_session_t dtls_ssl;
int err, ret;
err = gnutls_init(&dtls_ssl, GNUTLS_CLIENT|GNUTLS_DATAGRAM|GNUTLS_NONBLOCK|GNUTLS_NO_EXTENSIONS);
if (err) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to initialize DTLS: %s\n"),
gnutls_strerror(err));
return -EINVAL;
}
gnutls_session_set_ptr(dtls_ssl, (void *) vpninfo);
gnutls_transport_set_ptr(dtls_ssl,
(gnutls_transport_ptr_t)(intptr_t)dtls_fd);
if (!vpninfo->dtls_cipher) {
/* Anonymous DTLS (PPP protocols) */
ret = start_dtls_anon_handshake(vpninfo, dtls_ssl);
} else if (!strcmp(vpninfo->dtls_cipher, "PSK-NEGOTIATE")) {
/* For OpenConnect/ocserv protocol */
ret = start_dtls_psk_handshake(vpninfo, dtls_ssl);
} else {
/* Nonexistent session resume hack (Cisco AnyConnect) */
ret = start_dtls_resume_handshake(vpninfo, dtls_ssl);
}
if (ret) {
if (ret != -EAGAIN)
vpninfo->dtls_attempt_period = 0;
gnutls_deinit(dtls_ssl);
return ret;
}
if (gnutls_check_version_numeric(3,6,3) && !gnutls_check_version_numeric(3,6,13)) {
gnutls_handshake_set_hook_function(dtls_ssl, GNUTLS_HANDSHAKE_CLIENT_HELLO,
GNUTLS_HOOK_POST, check_client_hello_random);
}
vpninfo->dtls_ssl = dtls_ssl;
return 0;
}
int dtls_try_handshake(struct openconnect_info *vpninfo, int *timeout)
{
int err = gnutls_handshake(vpninfo->dtls_ssl);
char *str;
if (!err) {
if (!vpninfo->dtls_cipher) {
/* Anonymous DTLS (PPP protocols) will set vpninfo->ip_info.mtu
* in PPP negotiation.
*
* XX: Needs forthcoming overhaul to detect MTU correctly and offer
* reasonable MRU values during PPP negotiation.
*/
int data_mtu = vpninfo->cstp_basemtu = 1500;
if (vpninfo->peer_addr->sa_family == IPPROTO_IPV6)
data_mtu -= 40; /* IPv6 header */
else
data_mtu -= 20; /* Legacy IP header */
data_mtu -= 8; /* UDP header */
dtls_set_mtu(vpninfo, data_mtu);
} else if (!strcmp(vpninfo->dtls_cipher, "PSK-NEGOTIATE")) {
/* For PSK-NEGOTIATE (OpenConnect/ocserv protocol)
* we have to determine the tunnel MTU
* for ourselves based on the base MTU */
int data_mtu = vpninfo->cstp_basemtu;
if (vpninfo->peer_addr->sa_family == IPPROTO_IPV6)
data_mtu -= 40; /* IPv6 header */
else
data_mtu -= 20; /* Legacy IP header */
data_mtu -= 8; /* UDP header */
if (data_mtu < 0) {
vpn_progress(vpninfo, PRG_ERR,
_("Peer MTU %d too small to allow DTLS\n"),
vpninfo->cstp_basemtu);
goto nodtls;
}
/* Reduce it by one because that's the payload header *inside*
* the encryption */
data_mtu = dtls_set_mtu(vpninfo, data_mtu) - 1;
if (data_mtu < vpninfo->ip_info.mtu) {
vpn_progress(vpninfo, PRG_INFO,
_("DTLS MTU reduced to %d\n"),
data_mtu);
vpninfo->ip_info.mtu = data_mtu;
}
} else {
/* Nonexistent session resume hack (Cisco AnyConnect) */
if (!gnutls_session_is_resumed(vpninfo->dtls_ssl)) {
/* Someone attempting to hijack the DTLS session?
* A real server would never allow a full session
* establishment instead of the agreed resume. */
vpn_progress(vpninfo, PRG_ERR,
_("DTLS session resume failed; possible MITM attack. Disabling DTLS.\n"));
nodtls:
dtls_close(vpninfo);
vpninfo->dtls_attempt_period = 0;
vpninfo->dtls_state = DTLS_DISABLED;
return -EIO;
}
/* Make sure GnuTLS's idea of the MTU is sufficient to take
a full VPN MTU (with 1-byte header) in a data record. */
err = gnutls_dtls_set_data_mtu(vpninfo->dtls_ssl, vpninfo->ip_info.mtu + 1);
if (err) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to set DTLS MTU: %s\n"),
gnutls_strerror(err));
goto error;
}
}
vpninfo->dtls_state = DTLS_CONNECTED;
str = get_gnutls_cipher(vpninfo->dtls_ssl);
if (str) {
const char *c;
vpn_progress(vpninfo, PRG_INFO,
_("Established DTLS connection (using GnuTLS). Ciphersuite %s.\n"),
str);
gnutls_free(str);
c = openconnect_get_dtls_compression(vpninfo);
if (c) {
vpn_progress(vpninfo, PRG_INFO,
_("DTLS connection compression using %s.\n"), c);
}
}
vpninfo->dtls_times.last_rekey = vpninfo->dtls_times.last_rx =
vpninfo->dtls_times.last_tx = time(NULL);
dtls_detect_mtu(vpninfo);
/* XXX: For OpenSSL we explicitly prevent retransmits here. */
return 0;
}
if (err == GNUTLS_E_AGAIN || err == GNUTLS_E_INTERRUPTED) {
int quit_time = vpninfo->new_dtls_started + 12 - time(NULL);
if (quit_time > 0) {
if (timeout) {
unsigned next_resend = gnutls_dtls_get_timeout(vpninfo->dtls_ssl);
if (next_resend && *timeout > next_resend)
*timeout = next_resend;
if (*timeout > quit_time * 1000)
*timeout = quit_time * 1000;
}
return 0;
}
vpn_progress(vpninfo, PRG_DEBUG, _("DTLS handshake timed out\n"));
}
vpn_progress(vpninfo, PRG_ERR, _("DTLS handshake failed: %s\n"),
gnutls_strerror(err));
if (err == GNUTLS_E_PUSH_ERROR)
vpn_progress(vpninfo, PRG_ERR,
_("(Is a firewall preventing you from sending UDP packets?)\n"));
error:
dtls_close(vpninfo);
vpninfo->dtls_state = DTLS_SLEEPING;
time(&vpninfo->new_dtls_started);
if (timeout && *timeout > vpninfo->dtls_attempt_period * 1000)
*timeout = vpninfo->dtls_attempt_period * 1000;
return -EINVAL;
}
void dtls_shutdown(struct openconnect_info *vpninfo)
{
dtls_close(vpninfo);
}
void dtls_ssl_free(struct openconnect_info *vpninfo)
{
gnutls_deinit(vpninfo->dtls_ssl);
if (vpninfo->psk_cred) {
gnutls_psk_free_client_credentials(vpninfo->psk_cred);
vpninfo->psk_cred = NULL;
}
}