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qemu/io/channel-tls.c
Daniel P. Berrangé 10be627d2b io: remove io watch if TLS channel is closed during handshake 
The TLS handshake make take some time to complete, during which time an
I/O watch might be registered with the main loop. If the owner of the
I/O channel invokes qio_channel_close() while the handshake is waiting
to continue the I/O watch must be removed. Failing to remove it will
later trigger the completion callback which the owner is not expecting
to receive. In the case of the VNC server, this results in a SEGV as
vnc_disconnect_start() tries to shutdown a client connection that is
already gone / NULL.

CVE-2023-3354
Reported-by: jiangyegen <jiangyegen@huawei.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2023-08-01 18:45:27 +01:00

511 lines
14 KiB
C
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/*
* QEMU I/O channels TLS driver
*
* Copyright (c) 2015 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/module.h"
#include "io/channel-tls.h"
#include "trace.h"
#include "qemu/atomic.h"
static ssize_t qio_channel_tls_write_handler(const char *buf,
size_t len,
void *opaque)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(opaque);
ssize_t ret;
ret = qio_channel_write(tioc->master, buf, len, NULL);
if (ret == QIO_CHANNEL_ERR_BLOCK) {
errno = EAGAIN;
return -1;
} else if (ret < 0) {
errno = EIO;
return -1;
}
return ret;
}
static ssize_t qio_channel_tls_read_handler(char *buf,
size_t len,
void *opaque)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(opaque);
ssize_t ret;
ret = qio_channel_read(tioc->master, buf, len, NULL);
if (ret == QIO_CHANNEL_ERR_BLOCK) {
errno = EAGAIN;
return -1;
} else if (ret < 0) {
errno = EIO;
return -1;
}
return ret;
}
QIOChannelTLS *
qio_channel_tls_new_server(QIOChannel *master,
QCryptoTLSCreds *creds,
const char *aclname,
Error **errp)
{
QIOChannelTLS *ioc;
ioc = QIO_CHANNEL_TLS(object_new(TYPE_QIO_CHANNEL_TLS));
ioc->master = master;
if (qio_channel_has_feature(master, QIO_CHANNEL_FEATURE_SHUTDOWN)) {
qio_channel_set_feature(QIO_CHANNEL(ioc), QIO_CHANNEL_FEATURE_SHUTDOWN);
}
object_ref(OBJECT(master));
ioc->session = qcrypto_tls_session_new(
creds,
NULL,
aclname,
QCRYPTO_TLS_CREDS_ENDPOINT_SERVER,
errp);
if (!ioc->session) {
goto error;
}
qcrypto_tls_session_set_callbacks(
ioc->session,
qio_channel_tls_write_handler,
qio_channel_tls_read_handler,
ioc);
trace_qio_channel_tls_new_server(ioc, master, creds, aclname);
return ioc;
error:
object_unref(OBJECT(ioc));
return NULL;
}
QIOChannelTLS *
qio_channel_tls_new_client(QIOChannel *master,
QCryptoTLSCreds *creds,
const char *hostname,
Error **errp)
{
QIOChannelTLS *tioc;
QIOChannel *ioc;
tioc = QIO_CHANNEL_TLS(object_new(TYPE_QIO_CHANNEL_TLS));
ioc = QIO_CHANNEL(tioc);
tioc->master = master;
if (qio_channel_has_feature(master, QIO_CHANNEL_FEATURE_SHUTDOWN)) {
qio_channel_set_feature(ioc, QIO_CHANNEL_FEATURE_SHUTDOWN);
}
object_ref(OBJECT(master));
tioc->session = qcrypto_tls_session_new(
creds,
hostname,
NULL,
QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT,
errp);
if (!tioc->session) {
goto error;
}
qcrypto_tls_session_set_callbacks(
tioc->session,
qio_channel_tls_write_handler,
qio_channel_tls_read_handler,
tioc);
trace_qio_channel_tls_new_client(tioc, master, creds, hostname);
return tioc;
error:
object_unref(OBJECT(tioc));
return NULL;
}
struct QIOChannelTLSData {
QIOTask *task;
GMainContext *context;
};
typedef struct QIOChannelTLSData QIOChannelTLSData;
static gboolean qio_channel_tls_handshake_io(QIOChannel *ioc,
GIOCondition condition,
gpointer user_data);
static void qio_channel_tls_handshake_task(QIOChannelTLS *ioc,
QIOTask *task,
GMainContext *context)
{
Error *err = NULL;
QCryptoTLSSessionHandshakeStatus status;
if (qcrypto_tls_session_handshake(ioc->session, &err) < 0) {
trace_qio_channel_tls_handshake_fail(ioc);
qio_task_set_error(task, err);
qio_task_complete(task);
return;
}
status = qcrypto_tls_session_get_handshake_status(ioc->session);
if (status == QCRYPTO_TLS_HANDSHAKE_COMPLETE) {
trace_qio_channel_tls_handshake_complete(ioc);
if (qcrypto_tls_session_check_credentials(ioc->session,
&err) < 0) {
trace_qio_channel_tls_credentials_deny(ioc);
qio_task_set_error(task, err);
} else {
trace_qio_channel_tls_credentials_allow(ioc);
}
qio_task_complete(task);
} else {
GIOCondition condition;
QIOChannelTLSData *data = g_new0(typeof(*data), 1);
data->task = task;
data->context = context;
if (context) {
g_main_context_ref(context);
}
if (status == QCRYPTO_TLS_HANDSHAKE_SENDING) {
condition = G_IO_OUT;
} else {
condition = G_IO_IN;
}
trace_qio_channel_tls_handshake_pending(ioc, status);
ioc->hs_ioc_tag =
qio_channel_add_watch_full(ioc->master,
condition,
qio_channel_tls_handshake_io,
data,
NULL,
context);
}
}
static gboolean qio_channel_tls_handshake_io(QIOChannel *ioc,
GIOCondition condition,
gpointer user_data)
{
QIOChannelTLSData *data = user_data;
QIOTask *task = data->task;
GMainContext *context = data->context;
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(
qio_task_get_source(task));
tioc->hs_ioc_tag = 0;
g_free(data);
qio_channel_tls_handshake_task(tioc, task, context);
if (context) {
g_main_context_unref(context);
}
return FALSE;
}
void qio_channel_tls_handshake(QIOChannelTLS *ioc,
QIOTaskFunc func,
gpointer opaque,
GDestroyNotify destroy,
GMainContext *context)
{
QIOTask *task;
task = qio_task_new(OBJECT(ioc),
func, opaque, destroy);
trace_qio_channel_tls_handshake_start(ioc);
qio_channel_tls_handshake_task(ioc, task, context);
}
static void qio_channel_tls_init(Object *obj G_GNUC_UNUSED)
{
}
static void qio_channel_tls_finalize(Object *obj)
{
QIOChannelTLS *ioc = QIO_CHANNEL_TLS(obj);
object_unref(OBJECT(ioc->master));
qcrypto_tls_session_free(ioc->session);
}
static ssize_t qio_channel_tls_readv(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int **fds,
size_t *nfds,
int flags,
Error **errp)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
size_t i;
ssize_t got = 0;
for (i = 0 ; i < niov ; i++) {
ssize_t ret = qcrypto_tls_session_read(tioc->session,
iov[i].iov_base,
iov[i].iov_len);
if (ret < 0) {
if (errno == EAGAIN) {
if (got) {
return got;
} else {
return QIO_CHANNEL_ERR_BLOCK;
}
} else if (errno == ECONNABORTED &&
(qatomic_load_acquire(&tioc->shutdown) &
QIO_CHANNEL_SHUTDOWN_READ)) {
return 0;
}
error_setg_errno(errp, errno,
"Cannot read from TLS channel");
return -1;
}
got += ret;
if (ret < iov[i].iov_len) {
break;
}
}
return got;
}
static ssize_t qio_channel_tls_writev(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int *fds,
size_t nfds,
int flags,
Error **errp)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
size_t i;
ssize_t done = 0;
for (i = 0 ; i < niov ; i++) {
ssize_t ret = qcrypto_tls_session_write(tioc->session,
iov[i].iov_base,
iov[i].iov_len);
if (ret <= 0) {
if (errno == EAGAIN) {
if (done) {
return done;
} else {
return QIO_CHANNEL_ERR_BLOCK;
}
}
error_setg_errno(errp, errno,
"Cannot write to TLS channel");
return -1;
}
done += ret;
if (ret < iov[i].iov_len) {
break;
}
}
return done;
}
static int qio_channel_tls_set_blocking(QIOChannel *ioc,
bool enabled,
Error **errp)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
return qio_channel_set_blocking(tioc->master, enabled, errp);
}
static void qio_channel_tls_set_delay(QIOChannel *ioc,
bool enabled)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
qio_channel_set_delay(tioc->master, enabled);
}
static void qio_channel_tls_set_cork(QIOChannel *ioc,
bool enabled)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
qio_channel_set_cork(tioc->master, enabled);
}
static int qio_channel_tls_shutdown(QIOChannel *ioc,
QIOChannelShutdown how,
Error **errp)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
qatomic_or(&tioc->shutdown, how);
return qio_channel_shutdown(tioc->master, how, errp);
}
static int qio_channel_tls_close(QIOChannel *ioc,
Error **errp)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
if (tioc->hs_ioc_tag) {
g_clear_handle_id(&tioc->hs_ioc_tag, g_source_remove);
}
return qio_channel_close(tioc->master, errp);
}
static void qio_channel_tls_set_aio_fd_handler(QIOChannel *ioc,
AioContext *ctx,
IOHandler *io_read,
IOHandler *io_write,
void *opaque)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
qio_channel_set_aio_fd_handler(tioc->master, ctx, io_read, io_write, opaque);
}
typedef struct QIOChannelTLSSource QIOChannelTLSSource;
struct QIOChannelTLSSource {
GSource parent;
QIOChannelTLS *tioc;
};
static gboolean
qio_channel_tls_source_check(GSource *source)
{
QIOChannelTLSSource *tsource = (QIOChannelTLSSource *)source;
return qcrypto_tls_session_check_pending(tsource->tioc->session) > 0;
}
static gboolean
qio_channel_tls_source_prepare(GSource *source, gint *timeout)
{
*timeout = -1;
return qio_channel_tls_source_check(source);
}
static gboolean
qio_channel_tls_source_dispatch(GSource *source, GSourceFunc callback,
gpointer user_data)
{
return G_SOURCE_CONTINUE;
}
static void
qio_channel_tls_source_finalize(GSource *source)
{
QIOChannelTLSSource *tsource = (QIOChannelTLSSource *)source;
object_unref(OBJECT(tsource->tioc));
}
static GSourceFuncs qio_channel_tls_source_funcs = {
qio_channel_tls_source_prepare,
qio_channel_tls_source_check,
qio_channel_tls_source_dispatch,
qio_channel_tls_source_finalize
};
static void
qio_channel_tls_read_watch(QIOChannelTLS *tioc, GSource *source)
{
GSource *child;
QIOChannelTLSSource *tlssource;
child = g_source_new(&qio_channel_tls_source_funcs,
sizeof(QIOChannelTLSSource));
tlssource = (QIOChannelTLSSource *)child;
tlssource->tioc = tioc;
object_ref(OBJECT(tioc));
g_source_add_child_source(source, child);
g_source_unref(child);
}
static GSource *qio_channel_tls_create_watch(QIOChannel *ioc,
GIOCondition condition)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
GSource *source = qio_channel_create_watch(tioc->master, condition);
if (condition & G_IO_IN) {
qio_channel_tls_read_watch(tioc, source);
}
return source;
}
QCryptoTLSSession *
qio_channel_tls_get_session(QIOChannelTLS *ioc)
{
return ioc->session;
}
static void qio_channel_tls_class_init(ObjectClass *klass,
void *class_data G_GNUC_UNUSED)
{
QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
ioc_klass->io_writev = qio_channel_tls_writev;
ioc_klass->io_readv = qio_channel_tls_readv;
ioc_klass->io_set_blocking = qio_channel_tls_set_blocking;
ioc_klass->io_set_delay = qio_channel_tls_set_delay;
ioc_klass->io_set_cork = qio_channel_tls_set_cork;
ioc_klass->io_close = qio_channel_tls_close;
ioc_klass->io_shutdown = qio_channel_tls_shutdown;
ioc_klass->io_create_watch = qio_channel_tls_create_watch;
ioc_klass->io_set_aio_fd_handler = qio_channel_tls_set_aio_fd_handler;
}
static const TypeInfo qio_channel_tls_info = {
.parent = TYPE_QIO_CHANNEL,
.name = TYPE_QIO_CHANNEL_TLS,
.instance_size = sizeof(QIOChannelTLS),
.instance_init = qio_channel_tls_init,
.instance_finalize = qio_channel_tls_finalize,
.class_init = qio_channel_tls_class_init,
};
static void qio_channel_tls_register_types(void)
{
type_register_static(&qio_channel_tls_info);
}
type_init(qio_channel_tls_register_types);
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