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 <rjo...@redhat.com> > > I suppose this would also be relevant for the built-in NBD server, > especially in the context of qemu-storage-daemon? > > If so, is this something specific to NBD sockets, or would it actually > make sense to have it as a generic option in UnixSocketAddress?
For other NBD sockets, most likely. I'm not sure about Unix sockets in general (as in: I know they also have the two label thing, but I don't know if there's a situation where SVirt protects other sockets apart from NBD sockets). I'm sure Dan will know ... By the way although it appears that setsockcreatecon_raw is setting a global flag, it seems to actually use a thread-local variable, so implementing this (although still ugly) would not require locks. https://github.com/SELinuxProject/selinux/blob/32611aea6543e3a8f32635857e37b4332b0b5c99/libselinux/src/procattr.c#L347 Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top
