static void start_auth_vencrypt_subauth(VncState *vs)
{
switch (vs->subauth) {
case VNC_AUTH_VENCRYPT_TLSNONE:
case VNC_AUTH_VENCRYPT_X509NONE:
vnc_write_u32(vs, 0); /* Accept auth completion */
start_client_init(vs);
break;
case VNC_AUTH_VENCRYPT_TLSVNC:
case VNC_AUTH_VENCRYPT_X509VNC:
start_auth_vnc(vs);
break;
#ifdef CONFIG_VNC_SASL
case VNC_AUTH_VENCRYPT_TLSSASL:
case VNC_AUTH_VENCRYPT_X509SASL:
start_auth_sasl(vs);
break;
#endif /* CONFIG_VNC_SASL */
default: /* Should not be possible, but just in case */
trace_vnc_auth_fail(vs, vs->auth, "Unhandled VeNCrypt subauth", "");
vnc_write_u8(vs, 1);
if (vs->minor >= 8) {
static const char err[] = "Unsupported authentication type";
vnc_write_u32(vs, sizeof(err));
vnc_write(vs, err, sizeof(err));
}
vnc_client_error(vs);
}
}
static void start_auth_vencrypt_subauth(VncState *vs)
{
switch (vs->subauth) {
case VNC_AUTH_VENCRYPT_TLSNONE:
case VNC_AUTH_VENCRYPT_X509NONE:
VNC_DEBUG("Accept TLS auth none\n");
vnc_write_u32(vs, 0); /* Accept auth completion */
start_client_init(vs);
break;
case VNC_AUTH_VENCRYPT_TLSVNC:
case VNC_AUTH_VENCRYPT_X509VNC:
VNC_DEBUG("Start TLS auth VNC\n");
start_auth_vnc(vs);
break;
#ifdef CONFIG_VNC_SASL
case VNC_AUTH_VENCRYPT_TLSSASL:
case VNC_AUTH_VENCRYPT_X509SASL:
VNC_DEBUG("Start TLS auth SASL\n");
start_auth_sasl(vs);
break;
#endif /* CONFIG_VNC_SASL */
default: /* Should not be possible, but just in case */
VNC_DEBUG("Reject subauth %d server bug\n", vs->auth);
vnc_write_u8(vs, 1);
if (vs->minor >= 8) {
static const char err[] = "Unsupported authentication type";
vnc_write_u32(vs, sizeof(err));
vnc_write(vs, err, sizeof(err));
}
vnc_client_error(vs);
}
}
static int protocol_client_vencrypt_init(VncState *vs, uint8_t *data, size_t len)
{
trace_vnc_auth_vencrypt_version(vs, (int)data[0], (int)data[1]);
if (data[0] != 0 ||
data[1] != 2) {
trace_vnc_auth_fail(vs, vs->auth, "Unsupported version", "");
vnc_write_u8(vs, 1); /* Reject version */
vnc_flush(vs);
vnc_client_error(vs);
} else {
vnc_write_u8(vs, 0); /* Accept version */
vnc_write_u8(vs, 1); /* Number of sub-auths */
vnc_write_u32(vs, vs->subauth); /* The supported auth */
vnc_flush(vs);
vnc_read_when(vs, protocol_client_vencrypt_auth, 4);
}
return 0;
}
static int protocol_client_vencrypt_init(VncState *vs, uint8_t *data, size_t len)
{
if (data[0] != 0 ||
data[1] != 2) {
VNC_DEBUG("Unsupported VeNCrypt protocol %d.%d\n", (int)data[0], (int)data[1]);
vnc_write_u8(vs, 1); /* Reject version */
vnc_flush(vs);
vnc_client_error(vs);
} else {
VNC_DEBUG("Sending allowed auth %d\n", vs->subauth);
vnc_write_u8(vs, 0); /* Accept version */
vnc_write_u8(vs, 1); /* Number of sub-auths */
vnc_write_u32(vs, vs->subauth); /* The supported auth */
vnc_flush(vs);
vnc_read_when(vs, protocol_client_vencrypt_auth, 4);
}
return 0;
}
void start_auth_sasl(VncState *vs)
{
const char *mechlist = NULL;
sasl_security_properties_t secprops;
int err;
char *localAddr, *remoteAddr;
int mechlistlen;
VNC_DEBUG("Initialize SASL auth %p\n", vs->ioc);
/* Get local & remote client addresses in form IPADDR;PORT */
localAddr = vnc_socket_ip_addr_string(vs->sioc, true, NULL);
if (!localAddr) {
goto authabort;
}
remoteAddr = vnc_socket_ip_addr_string(vs->sioc, false, NULL);
if (!remoteAddr) {
g_free(localAddr);
goto authabort;
}
err = sasl_server_new("vnc",
NULL, /* FQDN - just delegates to gethostname */
NULL, /* User realm */
localAddr,
remoteAddr,
NULL, /* Callbacks, not needed */
SASL_SUCCESS_DATA,
&vs->sasl.conn);
g_free(localAddr);
g_free(remoteAddr);
localAddr = remoteAddr = NULL;
if (err != SASL_OK) {
VNC_DEBUG("sasl context setup failed %d (%s)",
err, sasl_errstring(err, NULL, NULL));
vs->sasl.conn = NULL;
goto authabort;
}
/* Inform SASL that we've got an external SSF layer from TLS/x509 */
if (vs->auth == VNC_AUTH_VENCRYPT &&
vs->subauth == VNC_AUTH_VENCRYPT_X509SASL) {
Error *local_err = NULL;
int keysize;
sasl_ssf_t ssf;
keysize = qcrypto_tls_session_get_key_size(vs->tls,
&local_err);
if (keysize < 0) {
VNC_DEBUG("cannot TLS get cipher size: %s\n",
error_get_pretty(local_err));
error_free(local_err);
sasl_dispose(&vs->sasl.conn);
vs->sasl.conn = NULL;
goto authabort;
}
ssf = keysize * CHAR_BIT; /* tls key size is bytes, sasl wants bits */
err = sasl_setprop(vs->sasl.conn, SASL_SSF_EXTERNAL, &ssf);
if (err != SASL_OK) {
VNC_DEBUG("cannot set SASL external SSF %d (%s)\n",
err, sasl_errstring(err, NULL, NULL));
sasl_dispose(&vs->sasl.conn);
vs->sasl.conn = NULL;
goto authabort;
}
} else {
vs->sasl.wantSSF = 1;
}
memset (&secprops, 0, sizeof secprops);
/* Inform SASL that we've got an external SSF layer from TLS.
*
* Disable SSF, if using TLS+x509+SASL only. TLS without x509
* is not sufficiently strong
*/
if (vs->vd->is_unix ||
(vs->auth == VNC_AUTH_VENCRYPT &&
vs->subauth == VNC_AUTH_VENCRYPT_X509SASL)) {
/* If we've got TLS or UNIX domain sock, we don't care about SSF */
secprops.min_ssf = 0;
secprops.max_ssf = 0;
secprops.maxbufsize = 8192;
secprops.security_flags = 0;
} else {
/* Plain TCP, better get an SSF layer */
secprops.min_ssf = 56; /* Good enough to require kerberos */
secprops.max_ssf = 100000; /* Arbitrary big number */
secprops.maxbufsize = 8192;
/* Forbid any anonymous or trivially crackable auth */
secprops.security_flags =
SASL_SEC_NOANONYMOUS | SASL_SEC_NOPLAINTEXT;
}
err = sasl_setprop(vs->sasl.conn, SASL_SEC_PROPS, &secprops);
if (err != SASL_OK) {
VNC_DEBUG("cannot set SASL security props %d (%s)\n",
err, sasl_errstring(err, NULL, NULL));
sasl_dispose(&vs->sasl.conn);
vs->sasl.conn = NULL;
goto authabort;
}
err = sasl_listmech(vs->sasl.conn,
NULL, /* Don't need to set user */
"", /* Prefix */
",", /* Separator */
"", /* Suffix */
&mechlist,
NULL,
NULL);
if (err != SASL_OK) {
VNC_DEBUG("cannot list SASL mechanisms %d (%s)\n",
err, sasl_errdetail(vs->sasl.conn));
sasl_dispose(&vs->sasl.conn);
vs->sasl.conn = NULL;
goto authabort;
}
VNC_DEBUG("Available mechanisms for client: '%s'\n", mechlist);
vs->sasl.mechlist = g_strdup(mechlist);
mechlistlen = strlen(mechlist);
vnc_write_u32(vs, mechlistlen);
vnc_write(vs, mechlist, mechlistlen);
vnc_flush(vs);
VNC_DEBUG("Wait for client mechname length\n");
vnc_read_when(vs, protocol_client_auth_sasl_mechname_len, 4);
return;
authabort:
vnc_client_error(vs);
}
static int protocol_client_auth_sasl_start(VncState *vs, uint8_t *data, size_t len)
{
uint32_t datalen = len;
const char *serverout;
unsigned int serveroutlen;
int err;
char *clientdata = NULL;
/* NB, distinction of NULL vs "" is *critical* in SASL */
if (datalen) {
clientdata = (char*)data;
clientdata[datalen-1] = '\0'; /* Should be on wire, but make sure */
datalen--; /* Don't count NULL byte when passing to _start() */
}
VNC_DEBUG("Start SASL auth with mechanism %s. Data %p (%d bytes)\n",
vs->sasl.mechlist, clientdata, datalen);
err = sasl_server_start(vs->sasl.conn,
vs->sasl.mechlist,
clientdata,
datalen,
&serverout,
&serveroutlen);
if (err != SASL_OK &&
err != SASL_CONTINUE) {
VNC_DEBUG("sasl start failed %d (%s)\n",
err, sasl_errdetail(vs->sasl.conn));
sasl_dispose(&vs->sasl.conn);
vs->sasl.conn = NULL;
goto authabort;
}
if (serveroutlen > SASL_DATA_MAX_LEN) {
VNC_DEBUG("sasl start reply data too long %d\n",
serveroutlen);
sasl_dispose(&vs->sasl.conn);
vs->sasl.conn = NULL;
goto authabort;
}
VNC_DEBUG("SASL return data %d bytes, nil; %d\n",
serveroutlen, serverout ? 0 : 1);
if (serveroutlen) {
vnc_write_u32(vs, serveroutlen + 1);
vnc_write(vs, serverout, serveroutlen + 1);
} else {
vnc_write_u32(vs, 0);
}
/* Whether auth is complete */
vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);
if (err == SASL_CONTINUE) {
VNC_DEBUG("%s", "Authentication must continue\n");
/* Wait for step length */
vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
} else {
if (!vnc_auth_sasl_check_ssf(vs)) {
VNC_DEBUG("Authentication rejected for weak SSF %p\n", vs->ioc);
goto authreject;
}
/* Check username whitelist ACL */
if (vnc_auth_sasl_check_access(vs) < 0) {
VNC_DEBUG("Authentication rejected for ACL %p\n", vs->ioc);
goto authreject;
}
VNC_DEBUG("Authentication successful %p\n", vs->ioc);
vnc_write_u32(vs, 0); /* Accept auth */
start_client_init(vs);
}
return 0;
authreject:
vnc_write_u32(vs, 1); /* Reject auth */
vnc_write_u32(vs, sizeof("Authentication failed"));
vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
vnc_flush(vs);
vnc_client_error(vs);
return -1;
authabort:
vnc_client_error(vs);
return -1;
}