On Fri, Mar 24, 2023 at 10:33:49AM -0500, Eric Blake wrote: > Some time after systemd documented LISTEN_PID and LISTEN_FDS for > socket activation, they later added LISTEN_FDNAMES; now documented at: > https://www.freedesktop.org/software/systemd/man/sd_listen_fds.html > > In particular, look at the implementation of sd_listen_fds_with_names(): > https://github.com/systemd/systemd/blob/main/src/libsystemd/sd-daemon/sd-daemon.c > > If we ever pass LISTEN_PID=xxx and LISTEN_FDS=n to a child process, > but leave LISTEN_FDNAMES=... unchanged as inherited from our parent > process, then our child process using sd_listen_fds_with_names() might > see a mismatch in the number of names (unexpected -EINVAL failure), or > even if the number of names matches the values of those names may be > unexpected (with even less predictable results). > > Usually, this is not an issue - the point of LISTEN_PID is to tell > systemd socket activation to ignore all other LISTEN_* if they were > not directed to this particular pid. But if we end up consuming a > socket directed to this qemu process, and later decide to spawn a > child process that also needs systemd socket activation, we must > ensure we are not leaking any stale systemd variables through to that > child. The easiest way to do this is to wipe ALL LISTEN_* variables > at the time we consume a socket, even if we do not yet care about a > LISTEN_FDNAMES passed in from the parent process. > > See also > https://lists.freedesktop.org/archives/systemd-devel/2023-March/048920.html > > Thanks: Laszlo Ersek <ler...@redhat.com> > Signed-off-by: Eric Blake <ebl...@redhat.com> > --- > util/systemd.c | 1 + > 1 file changed, 1 insertion(+)
Reviewed-by: Daniel P. Berrangé <berra...@redhat.com> With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
