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qemu/vnc-tls.c

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/*
* QEMU VNC display driver: TLS helpers
*
* Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
* Copyright (C) 2006 Fabrice Bellard
* Copyright (C) 2009 Red Hat, Inc
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "vnc.h"
#include "qemu_socket.h"
#if defined(_VNC_DEBUG) && _VNC_DEBUG >= 2
/* Very verbose, so only enabled for _VNC_DEBUG >= 2 */
static void vnc_debug_gnutls_log(int level, const char* str) {
VNC_DEBUG("%d %s", level, str);
}
#endif /* defined(_VNC_DEBUG) && _VNC_DEBUG >= 2 */
#define DH_BITS 1024
static gnutls_dh_params_t dh_params;
static int vnc_tls_initialize(void)
{
static int tlsinitialized = 0;
if (tlsinitialized)
return 1;
if (gnutls_global_init () < 0)
return 0;
/* XXX ought to re-generate diffie-hellmen params periodically */
if (gnutls_dh_params_init (&dh_params) < 0)
return 0;
if (gnutls_dh_params_generate2 (dh_params, DH_BITS) < 0)
return 0;
#if defined(_VNC_DEBUG) && _VNC_DEBUG >= 2
gnutls_global_set_log_level(10);
gnutls_global_set_log_function(vnc_debug_gnutls_log);
#endif
tlsinitialized = 1;
return 1;
}
static ssize_t vnc_tls_push(gnutls_transport_ptr_t transport,
const void *data,
size_t len) {
struct VncState *vs = (struct VncState *)transport;
int ret;
retry:
ret = send(vs->csock, data, len, 0);
if (ret < 0) {
if (errno == EINTR)
goto retry;
return -1;
}
return ret;
}
static ssize_t vnc_tls_pull(gnutls_transport_ptr_t transport,
void *data,
size_t len) {
struct VncState *vs = (struct VncState *)transport;
int ret;
retry:
ret = recv(vs->csock, data, len, 0);
if (ret < 0) {
if (errno == EINTR)
goto retry;
return -1;
}
return ret;
}
static gnutls_anon_server_credentials vnc_tls_initialize_anon_cred(void)
{
gnutls_anon_server_credentials anon_cred;
int ret;
if ((ret = gnutls_anon_allocate_server_credentials(&anon_cred)) < 0) {
VNC_DEBUG("Cannot allocate credentials %s\n", gnutls_strerror(ret));
return NULL;
}
gnutls_anon_set_server_dh_params(anon_cred, dh_params);
return anon_cred;
}
static gnutls_certificate_credentials_t vnc_tls_initialize_x509_cred(VncDisplay *vd)
{
gnutls_certificate_credentials_t x509_cred;
int ret;
if (!vd->tls.x509cacert) {
VNC_DEBUG("No CA x509 certificate specified\n");
return NULL;
}
if (!vd->tls.x509cert) {
VNC_DEBUG("No server x509 certificate specified\n");
return NULL;
}
if (!vd->tls.x509key) {
VNC_DEBUG("No server private key specified\n");
return NULL;
}
if ((ret = gnutls_certificate_allocate_credentials(&x509_cred)) < 0) {
VNC_DEBUG("Cannot allocate credentials %s\n", gnutls_strerror(ret));
return NULL;
}
if ((ret = gnutls_certificate_set_x509_trust_file(x509_cred,
vd->tls.x509cacert,
GNUTLS_X509_FMT_PEM)) < 0) {
VNC_DEBUG("Cannot load CA certificate %s\n", gnutls_strerror(ret));
gnutls_certificate_free_credentials(x509_cred);
return NULL;
}
if ((ret = gnutls_certificate_set_x509_key_file (x509_cred,
vd->tls.x509cert,
vd->tls.x509key,
GNUTLS_X509_FMT_PEM)) < 0) {
VNC_DEBUG("Cannot load certificate & key %s\n", gnutls_strerror(ret));
gnutls_certificate_free_credentials(x509_cred);
return NULL;
}
if (vd->tls.x509cacrl) {
if ((ret = gnutls_certificate_set_x509_crl_file(x509_cred,
vd->tls.x509cacrl,
GNUTLS_X509_FMT_PEM)) < 0) {
VNC_DEBUG("Cannot load CRL %s\n", gnutls_strerror(ret));
gnutls_certificate_free_credentials(x509_cred);
return NULL;
}
}
gnutls_certificate_set_dh_params (x509_cred, dh_params);
return x509_cred;
}
int vnc_tls_validate_certificate(struct VncState *vs)
{
int ret;
unsigned int status;
const gnutls_datum_t *certs;
unsigned int nCerts, i;
time_t now;
VNC_DEBUG("Validating client certificate\n");
if ((ret = gnutls_certificate_verify_peers2 (vs->tls.session, &status)) < 0) {
VNC_DEBUG("Verify failed %s\n", gnutls_strerror(ret));
return -1;
}
if ((now = time(NULL)) == ((time_t)-1)) {
return -1;
}
if (status != 0) {
if (status & GNUTLS_CERT_INVALID)
VNC_DEBUG("The certificate is not trusted.\n");
if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
VNC_DEBUG("The certificate hasn't got a known issuer.\n");
if (status & GNUTLS_CERT_REVOKED)
VNC_DEBUG("The certificate has been revoked.\n");
if (status & GNUTLS_CERT_INSECURE_ALGORITHM)
VNC_DEBUG("The certificate uses an insecure algorithm\n");
return -1;
} else {
VNC_DEBUG("Certificate is valid!\n");
}
/* Only support x509 for now */
if (gnutls_certificate_type_get(vs->tls.session) != GNUTLS_CRT_X509)
return -1;
if (!(certs = gnutls_certificate_get_peers(vs->tls.session, &nCerts)))
return -1;
for (i = 0 ; i < nCerts ; i++) {
gnutls_x509_crt_t cert;
VNC_DEBUG ("Checking certificate chain %d\n", i);
if (gnutls_x509_crt_init (&cert) < 0)
return -1;
if (gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER) < 0) {
gnutls_x509_crt_deinit (cert);
return -1;
}
if (gnutls_x509_crt_get_expiration_time (cert) < now) {
VNC_DEBUG("The certificate has expired\n");
gnutls_x509_crt_deinit (cert);
return -1;
}
if (gnutls_x509_crt_get_activation_time (cert) > now) {
VNC_DEBUG("The certificate is not yet activated\n");
gnutls_x509_crt_deinit (cert);
return -1;
}
if (gnutls_x509_crt_get_activation_time (cert) > now) {
VNC_DEBUG("The certificate is not yet activated\n");
gnutls_x509_crt_deinit (cert);
return -1;
}
if (i == 0) {
size_t dnameSize = 1024;
vs->tls.dname = qemu_malloc(dnameSize);
requery:
if ((ret = gnutls_x509_crt_get_dn (cert, vs->tls.dname, &dnameSize)) != 0) {
if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
vs->tls.dname = qemu_realloc(vs->tls.dname, dnameSize);
goto requery;
}
gnutls_x509_crt_deinit (cert);
VNC_DEBUG("Cannot get client distinguished name: %s",
gnutls_strerror (ret));
return -1;
}
if (vs->vd->tls.x509verify) {
int allow;
if (!vs->vd->tls.acl) {
VNC_DEBUG("no ACL activated, allowing access");
gnutls_x509_crt_deinit (cert);
continue;
}
allow = qemu_acl_party_is_allowed(vs->vd->tls.acl,
vs->tls.dname);
VNC_DEBUG("TLS x509 ACL check for %s is %s\n",
vs->tls.dname, allow ? "allowed" : "denied");
if (!allow) {
gnutls_x509_crt_deinit (cert);
return -1;
}
}
}
gnutls_x509_crt_deinit (cert);
}
return 0;
}
int vnc_tls_client_setup(struct VncState *vs,
int needX509Creds) {
static const int cert_type_priority[] = { GNUTLS_CRT_X509, 0 };
static const int protocol_priority[]= { GNUTLS_TLS1_1, GNUTLS_TLS1_0, GNUTLS_SSL3, 0 };
static const int kx_anon[] = {GNUTLS_KX_ANON_DH, 0};
static const int kx_x509[] = {GNUTLS_KX_DHE_DSS, GNUTLS_KX_RSA, GNUTLS_KX_DHE_RSA, GNUTLS_KX_SRP, 0};
VNC_DEBUG("Do TLS setup\n");
if (vnc_tls_initialize() < 0) {
VNC_DEBUG("Failed to init TLS\n");
vnc_client_error(vs);
return -1;
}
if (vs->tls.session == NULL) {
if (gnutls_init(&vs->tls.session, GNUTLS_SERVER) < 0) {
vnc_client_error(vs);
return -1;
}
if (gnutls_set_default_priority(vs->tls.session) < 0) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
vnc_client_error(vs);
return -1;
}
if (gnutls_kx_set_priority(vs->tls.session, needX509Creds ? kx_x509 : kx_anon) < 0) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
vnc_client_error(vs);
return -1;
}
if (gnutls_certificate_type_set_priority(vs->tls.session, cert_type_priority) < 0) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
vnc_client_error(vs);
return -1;
}
if (gnutls_protocol_set_priority(vs->tls.session, protocol_priority) < 0) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
vnc_client_error(vs);
return -1;
}
if (needX509Creds) {
gnutls_certificate_server_credentials x509_cred = vnc_tls_initialize_x509_cred(vs->vd);
if (!x509_cred) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
vnc_client_error(vs);
return -1;
}
if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_CERTIFICATE, x509_cred) < 0) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
gnutls_certificate_free_credentials(x509_cred);
vnc_client_error(vs);
return -1;
}
if (vs->vd->tls.x509verify) {
VNC_DEBUG("Requesting a client certificate\n");
gnutls_certificate_server_set_request (vs->tls.session, GNUTLS_CERT_REQUEST);
}
} else {
gnutls_anon_server_credentials anon_cred = vnc_tls_initialize_anon_cred();
if (!anon_cred) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
vnc_client_error(vs);
return -1;
}
if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_ANON, anon_cred) < 0) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
gnutls_anon_free_server_credentials(anon_cred);
vnc_client_error(vs);
return -1;
}
}
gnutls_transport_set_ptr(vs->tls.session, (gnutls_transport_ptr_t)vs);
gnutls_transport_set_push_function(vs->tls.session, vnc_tls_push);
gnutls_transport_set_pull_function(vs->tls.session, vnc_tls_pull);
}
return 0;
}
void vnc_tls_client_cleanup(struct VncState *vs)
{
if (vs->tls.session) {
gnutls_deinit(vs->tls.session);
vs->tls.session = NULL;
}
vs->tls.wiremode = VNC_WIREMODE_CLEAR;
free(vs->tls.dname);
}
static int vnc_set_x509_credential(VncDisplay *vd,
const char *certdir,
const char *filename,
char **cred,
int ignoreMissing)
{
struct stat sb;
if (*cred) {
qemu_free(*cred);
*cred = NULL;
}
*cred = qemu_malloc(strlen(certdir) + strlen(filename) + 2);
strcpy(*cred, certdir);
strcat(*cred, "/");
strcat(*cred, filename);
VNC_DEBUG("Check %s\n", *cred);
if (stat(*cred, &sb) < 0) {
qemu_free(*cred);
*cred = NULL;
if (ignoreMissing && errno == ENOENT)
return 0;
return -1;
}
return 0;
}
#define X509_CA_CERT_FILE "ca-cert.pem"
#define X509_CA_CRL_FILE "ca-crl.pem"
#define X509_SERVER_KEY_FILE "server-key.pem"
#define X509_SERVER_CERT_FILE "server-cert.pem"
int vnc_tls_set_x509_creds_dir(VncDisplay *vd,
const char *certdir)
{
if (vnc_set_x509_credential(vd, certdir, X509_CA_CERT_FILE, &vd->tls.x509cacert, 0) < 0)
goto cleanup;
if (vnc_set_x509_credential(vd, certdir, X509_CA_CRL_FILE, &vd->tls.x509cacrl, 1) < 0)
goto cleanup;
if (vnc_set_x509_credential(vd, certdir, X509_SERVER_CERT_FILE, &vd->tls.x509cert, 0) < 0)
goto cleanup;
if (vnc_set_x509_credential(vd, certdir, X509_SERVER_KEY_FILE, &vd->tls.x509key, 0) < 0)
goto cleanup;
return 0;
cleanup:
qemu_free(vd->tls.x509cacert);
qemu_free(vd->tls.x509cacrl);
qemu_free(vd->tls.x509cert);
qemu_free(vd->tls.x509key);
vd->tls.x509cacert = vd->tls.x509cacrl = vd->tls.x509cert = vd->tls.x509key = NULL;
return -1;
}
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