Re: qemu-ga guest-exec & SELinux

On Mon, Jun 20, 2022 at 01:44:05PM +0400, Marc-André Lureau wrote:
> Hi!
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=2093355 ("AVCs when trying to
> execute a command through qemu-ga ("guest-exec" command)") describes an
> issue with fedora/rhel SELinux rules, where some program executions are
> denied.
> 
> qemu-ga has "virt_qemu_ga_t" context, and is not allowed to execute
> binaries that are not "bin_t", iiuc. The suggestion from Renaud Métrich is
> for qemu-ga exec command to launch the user program through an helper
> program that would have the virt_qemu_ga_unconfined_exec_t context, and
> appropriate rules in selinux (similar to fsfreeze-hook rules), so any
> program can be executed. qemu-ga would thus ship and use that helper, in
> all OS, to avoid varying code paths.
> 
> Does that sound reasonable or should we try to find a solution with SELinux
> rules instead?

I thought was did not allow qemu-ga to execute binaries at all, regardless
of whether they're bin_t or not.  The 'guest-exec' command is essentially
a giant hole that defeats the purpose of confining qemu-ga with SELinux
at all IMHO.

IMHO execution of external commands should only be allowed after toggling
a SELinux boolean tunable.


With regards,
Daniel
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