When running in a user namespace created by an unprivileged user the
owner of /var/run will be reported as the unknown user (as defined in
/proc/sys/kernel/overflowuid) so any access to the directory will
fail.
If the XDG_RUNTIME_DIR environment variable is set, check whether the
current user is also the owner of /var/run. If the owner is different
than the current user, use the $XDG_RUNTIME_DIR/netns directory.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Namespace creation had an unergonomic interface and isn't used, except
for testing code. Remove it; downstream users should really be creating
their own namespaces
