[Spice-devel] [vdagent-win v2] VDService to notify VDAgent about session status
Victor Toso
lists at victortoso.com
Wed Dec 14 22:35:42 UTC 2016
Hi,
On Wed, Dec 14, 2016 at 05:07:17PM -0500, Frediano Ziglio wrote:
> >
> > Commit 5907b6cbb5c724f9729da59a644271b4258d122e started to handle
> > Lock/Unlock events from Session at VDAgent. That seemed to work fine
> > but as pointed by Andrei at [0], it does not cover the following
> > situation:
> >
> > > It fails for next test-case:
> > >
> > > * Connect with RV to VM
> > > * Lock VM (ctrl-alt-del)
> > > * Close RV
> > > * Connect with RV to the VM again
> > > * Do not unlock session. DnD files from client to locked VM.
> > >
> > > Result : Files are copied to VM.
> >
> > [0] https://bugzilla.redhat.com/show_bug.cgi?id=1323628#c6
> >
> > There is also race between receiving sessions events (like
> > WTS_SESSION_LOCK/UNLOCK) and the CONTROL_DESKTOP_SWITCH control
> > action, which eventually calls WTSUnRegisterSessionNotification().
> >
> > To solve this situation, we need VDService to inform VDAgent if
> > Session is Locked or not, always.
> >
> > - We have two new events to trigger both lock/unlock events between
> > VDService and VDAgent.
> > - VDAgent is always initialized with session_is_locked = true
> >
> > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1323628
> > Signed-off-by: Victor Toso <victortoso at redhat.com>
> > Reported-by: Andrei Stepanov <astepano at redhat.com>
> > ---
> > common/vdcommon.h | 2 ++
> > vdagent/vdagent.cpp | 34 ++++++++++++++++++++++++++++------
> > vdservice/vdservice.cpp | 20 ++++++++++++++++++++
> > 3 files changed, 50 insertions(+), 6 deletions(-)
> >
> > diff --git a/common/vdcommon.h b/common/vdcommon.h
> > index c1920e9..6b2b5f1 100644
> > --- a/common/vdcommon.h
> > +++ b/common/vdcommon.h
> > @@ -66,6 +66,8 @@ typedef Mutex mutex_t;
> >
> > #define VD_AGENT_REGISTRY_KEY "SOFTWARE\\Red Hat\\Spice\\vdagent\\"
> > #define VD_AGENT_STOP_EVENT TEXT("Global\\vdagent_stop_event")
> > +#define VD_AGENT_SESSION_LOCKED_EVENT
> > TEXT("Global\\vdagent_session_locked_event")
> > +#define VD_AGENT_SESSION_UNLOCKED_EVENT
> > TEXT("Global\\vdagent_session_unlocked_event")
> >
> > #if defined __GNUC__
> > #define ALIGN_GCC __attribute__ ((packed))
> > diff --git a/vdagent/vdagent.cpp b/vdagent/vdagent.cpp
> > index e3ba14b..95f7eef 100644
> > --- a/vdagent/vdagent.cpp
> > +++ b/vdagent/vdagent.cpp
> > @@ -148,6 +148,8 @@ private:
> > DWORD _input_time;
> > HANDLE _control_event;
> > HANDLE _stop_event;
> > + HANDLE _session_locked_event;
> > + HANDLE _session_unlocked_event;
> > VDAgentMessage* _in_msg;
> > uint32_t _in_msg_pos;
> > bool _pending_input;
> > @@ -207,11 +209,13 @@ VDAgent::VDAgent()
> > , _input_time (0)
> > , _control_event (NULL)
> > , _stop_event (NULL)
> > + , _session_locked_event (NULL)
> > + , _session_unlocked_event (NULL)
> > , _in_msg (NULL)
> > , _in_msg_pos (0)
> > , _pending_input (false)
> > , _running (false)
> > - , _session_is_locked (false)
> > + , _session_is_locked (true)
> > , _desktop_switch (false)
> > , _desktop_layout (NULL)
> > , _display_setting (VD_AGENT_REGISTRY_KEY)
> > @@ -309,6 +313,8 @@ bool VDAgent::run()
> > return false;
> > }
> > _stop_event = OpenEvent(SYNCHRONIZE, FALSE, VD_AGENT_STOP_EVENT);
> > + _session_locked_event = OpenEvent(SYNCHRONIZE, FALSE,
> > VD_AGENT_SESSION_LOCKED_EVENT);
> > + _session_unlocked_event = OpenEvent(SYNCHRONIZE, FALSE,
> > VD_AGENT_SESSION_UNLOCKED_EVENT);
> > memset(&wcls, 0, sizeof(wcls));
> > wcls.lpfnWndProc = &VDAgent::wnd_proc;
> > wcls.lpszClassName = VD_AGENT_WINCLASS_NAME;
> > @@ -479,13 +485,15 @@ void VDAgent::input_desktop_message_loop()
> >
> > void VDAgent::event_dispatcher(DWORD timeout, DWORD wake_mask)
> > {
> > - HANDLE events[2];
> > + HANDLE events[4];
> > DWORD event_count = 1;
> > DWORD wait_ret;
> > MSG msg;
> > enum {
> > CONTROL_ACTION,
> > STOP_ACTION,
> > + SESSION_LOCKED_ACTION,
> > + SESSION_UNLOCKED_ACTION,
> > } actions[SPICE_N_ELEMENTS(events)], action;
> >
> > events[0] = _control_event;
> > @@ -496,6 +504,16 @@ void VDAgent::event_dispatcher(DWORD timeout, DWORD
> > wake_mask)
> > event_count++;
> > }
> >
> > + if (_session_unlocked_event && _session_locked_event) {
> > + events[event_count] = _session_locked_event;
> > + actions[event_count] = SESSION_LOCKED_ACTION;
> > + event_count++;
> > +
> > + events[event_count] = _session_unlocked_event;
> > + actions[event_count] = SESSION_UNLOCKED_ACTION;
> > + event_count++;
> > + }
> > +
> > wait_ret = MsgWaitForMultipleObjectsEx(event_count, events, timeout,
> > wake_mask, MWMO_ALERTABLE);
> > if (wait_ret == WAIT_OBJECT_0 + event_count) {
> > while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
> > @@ -520,6 +538,14 @@ void VDAgent::event_dispatcher(DWORD timeout, DWORD
> > wake_mask)
> > vd_printf("%s: received stop event", __func__);
> > _running = false;
> > break;
> > + case SESSION_LOCKED_ACTION:
> > + vd_printf("%s: received session locked event", __func__);
> > + _session_is_locked = true;
> > + break;
> > + case SESSION_UNLOCKED_ACTION:
> > + vd_printf("%s: received session unlocked event", __func__);
> > + _session_is_locked = false;
> > + break;
> > default:
> > vd_printf("%s: action not handled (%d)", __func__, action);
> > _running = false;
> > @@ -1516,10 +1542,6 @@ LRESULT CALLBACK VDAgent::wnd_proc(HWND hwnd, UINT
> > message, WPARAM wparam, LPARA
> > case WM_WTSSESSION_CHANGE:
> > if (wparam == WTS_SESSION_LOGON) {
> > a->set_control_event(CONTROL_LOGON);
> > - } else if (wparam == WTS_SESSION_LOCK) {
> > - a->_session_is_locked = true;
> > - } else if (wparam == WTS_SESSION_UNLOCK) {
> > - a->_session_is_locked = false;
> > }
> > break;
> > default:
> > diff --git a/vdservice/vdservice.cpp b/vdservice/vdservice.cpp
> > index 1892b72..9a11d87 100644
> > --- a/vdservice/vdservice.cpp
> > +++ b/vdservice/vdservice.cpp
> > @@ -91,6 +91,8 @@ private:
> > PROCESS_INFORMATION _agent_proc_info;
> > HANDLE _control_event;
> > HANDLE _agent_stop_event;
> > + HANDLE _session_locked_event;
> > + HANDLE _session_unlocked_event;
> > HANDLE* _events;
> > TCHAR _agent_path[MAX_PATH];
> > VDControlQueue _control_queue;
> > @@ -103,6 +105,7 @@ private:
> > int _system_version;
> > bool _agent_alive;
> > bool _running;
> > + bool _session_is_locked;
> > VDLog* _log;
> > unsigned _events_count;
> > };
> > @@ -116,6 +119,7 @@ VDService::VDService()
> > , _agent_restarts (0)
> > , _agent_alive (false)
> > , _running (false)
> > + , _session_is_locked (false)
> > , _log (NULL)
> > , _events_count(0)
> > {
> > @@ -123,11 +127,15 @@ VDService::VDService()
> > _system_version = supported_system_version();
> > _control_event = CreateEvent(NULL, FALSE, FALSE, NULL);
> > _agent_stop_event = CreateEvent(NULL, FALSE, FALSE,
> > VD_AGENT_STOP_EVENT);
> > + _session_locked_event = CreateEvent(NULL, FALSE, FALSE,
> > VD_AGENT_SESSION_LOCKED_EVENT);
> > + _session_unlocked_event = CreateEvent(NULL, FALSE, FALSE,
> > VD_AGENT_SESSION_UNLOCKED_EVENT);
> > _agent_path[0] = wchar_t('\0');
> > }
> >
> > VDService::~VDService()
> > {
> > + CloseHandle(_session_unlocked_event);
> > + CloseHandle(_session_locked_event);
> > CloseHandle(_agent_stop_event);
> > CloseHandle(_control_event);
> > delete[] _events;
> > @@ -290,6 +298,12 @@ DWORD WINAPI VDService::control_handler(DWORD control,
> > DWORD event_type, LPVOID
> > if (event_type == WTS_CONSOLE_CONNECT) {
> > s->_session_id = session_id;
> > s->set_control_event(VD_CONTROL_RESTART_AGENT);
> > + } else if (event_type == WTS_SESSION_LOCK) {
> > + s->_session_is_locked = true;
> > + SetEvent(s->_session_locked_event);
> > + } else if (event_type == WTS_SESSION_UNLOCK) {
> > + s->_session_is_locked = false;
> > + SetEvent(s->_session_unlocked_event);
> > }
> > break;
> > }
> > @@ -728,6 +742,12 @@ bool VDService::launch_agent()
> > return false;
> > }
> > _agent_alive = true;
> > +
> > + if (!_session_is_locked) {
> > + /* For security reasons, VDAgent always starts thinking its session
> > is
> > + * locked. We should notify that's not true */
> > + SetEvent(_session_unlocked_event);
> > + }
> > return true;
> > }
> >
>
> Not against this patch but the more I dig into the Windows agent the
> less I understand the separation design.
> I though was to separate process users but in both Windows 7 and
> Windows 10 agent and service are run as SYSTEM.
> I though in the past was to have multiple agents but there can
> be only one running.
> System services can interact with desktop so in theory you can do
> everything with a single process if security separation is not
> required. Maybe the developer that start all this ignored the
> SERVICE_INTERACTIVE_PROCESS flag registering the service?
> Or maybe all this weird code is to support some really old version
> of Windows? Maybe Windows 2000 terminal server? However the actual
> code seems to support from Windows XP onward.
>
> Frediano
I'm all in for a new design. I did not try to understand why things are
like they are, I was only trying to provide a solution to
not-really-big-problem :)
I think we should make some room to discuss improvements in vdagent for
both, linux and windows guests.
Unless it is proven to be bad, I wish we could come up with something
like spice-gtk for the agents. A codebase that is used for
windows/linux.
While we are not there... Anything you could think of that might be a
problem in this patch? :)
Cheers,
toso
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