On Fri, Jul 23, 2021 at 06:18:55PM +0200, Kevin Wolf wrote:
Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben:
Under SELinux, Unix domain sockets have two labels. One is on the
disk and can be set with commands such as chcon(1). There is a
different label stored in memory (called the process label). This can
only be set by the process creating the socket. When using SELinux +
SVirt and wanting qemu to be able to connect to a qemu-nbd instance,
you must set both labels correctly first.
For qemu-nbd the options to set the second label are awkward. You can
create the socket in a wrapper program and then exec into qemu-nbd.
Or you could try something with LD_PRELOAD.
This commit adds the ability to set the label straightforwardly on the
command line, via the new --selinux-label flag. (The name of the flag
is the same as the equivalent nbdkit option.)
A worked example showing how to use the new option can be found in
this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
I suppose this would also be relevant for the built-in NBD server,
especially in the context of qemu-storage-daemon?
It depends on the usage scenario really. nbdkit / qemu-nbd are
not commonly run under any SELinux policy, so then end up being
unconfined_t. A QEMU NBD client can't connect to an unconfined_t
socket, so we need to override it with this arg.
In the case of qemu system emulator, under libvirt, it will
already have a svirt_t type, so in that case there is no need
to override the type for the socket.
For qsd there's not really any strong practice established
but i expect most current usage is unconfined_t too and
would benefit from setting label.
If so, is this something specific to NBD sockets, or would it actually
make sense to have it as a generic option in UnixSocketAddress?
It is applicable to inet sockets too in fact.