The custom action uses cmd.exe to run VSS Service installation
and removal which causes an interactive command shell to spawn.
This shell can be used to execute any commands as a SYSTEM user.
Even if call qemu-ga.exe directly the interactive command shell
will be spawned as qemu-ga.exe is a console application and used
by users from the console as well as a service.
As VSS Service runs from DLL which contains the installer and
uninstaller code, it can be run directly by rundll32.exe without
any interactive command shell.
Add specific entry points for rundll which is just a wrapper
for COMRegister/COMUnregister functions with proper arguments.
resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2167423
fixes: CVE-2023-0664 (part 2 of 2)
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com>
Reported-by: Brian Wiltse <brian.wiltse@live.com>
Adds VSS provider and requester as a qga-vss.dll, which is loaded by
Windows VSS service as well as by qemu-ga.
"provider.cpp" implements a basic stub of a software VSS provider.
Currently, this module only relays a frozen event from VSS service to the
agent, and thaw event from the agent to VSS service, to block VSS process
to keep the system frozen while snapshots are taken at the host.
To register the provider to the guest system as COM+ application, the type
library (.tlb) for qga-vss.dll is required. To build it from COM IDL (.idl),
VisualC++, MIDL and stdole2.tlb in Windows SDK are required. This patch also
adds pre-compiled .tlb file in the repository in order to enable
cross-compile qemu-ga.exe for Windows with VSS support.
"requester.cpp" provides the VSS requester to kick the VSS snapshot process.
Qemu-ga.exe works without the DLL, although fsfreeze features are disabled.
These functions are only supported in Windows 2003 or later. In older
systems, fsfreeze features are disabled.
In several versions of Windows which don't support attribute
VSS_VOLSNAP_ATTR_NO_AUTORECOVERY, DoSnapshotSet fails with error
VSS_E_OBJECT_NOT_FOUND. In this patch, we just ignore this error.
To solve this fundamentally, we need a framework to handle mount writable
snapshot on guests, which is required by VSS auto-recovery feature
(cleanup phase after a snapshot is taken).
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
