abstractions/nameservice: allow accessing /run/systemd/userdb/

On systems with systemd 245, nss-systemd additionally queries NSS records from systemd-userdbd.service. See https://systemd.io/USER_GROUP_API/ .

(cherry picked from commit 16f9f688)
Fixes: #82


Signed-off-by: nl6720 <nl6720@gmail.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

profiles/apparmor.d/abstractions/nameservice

@@ -29,6 +29,11 @@
   /var/lib/extrausers/group  r,
   /var/lib/extrausers/passwd r,
 
+  # NSS records from systemd-userdbd.service
+  @{run}/systemd/userdb/ r,
+  @{run}/systemd/userdb/io.systemd.{NameServiceSwitch,Multiplexer,DynamicUser,Home} r,
+  @{PROC}/sys/kernel/random/boot_id r,
+
   # When using sssd, the passwd and group files are stored in an alternate path
   # and the nss plugin also needs to talk to a pipe
   /var/lib/sss/mc/group   r,