On Thu 05-05-22 20:34:06, Amir Goldstein wrote: > > One open question I have is what should the kernel do with 'info_type' in > > response it does not understand (in the future when there are possibly more > > different info types). It could just skip it because this should be just > > additional info for introspection (the only mandatory part is in > > fanotify_response, however it could surprise userspace that passed info is > > just getting ignored. To solve this we would have to somewhere report > > supported info types (maybe in fanotify fdinfo in proc). I guess we'll > > cross that bridge when we get to it. > > > > Amir, what do you think? > > Regardless if and how we provide a way to enumerate supported info types, > I would prefer to reject (EINVAL) unknown info types. OK, agreed. I will be also calmer when we do that because then we can be certain userspace does not pass bogus data for unknown info types. > We can provide a command FAN_RESPONSE_TEST to write a test response with > FAN_NOFD and some extra info so the program can test if certain info > types are supported. Hum, that would be an option as well. We don't even need the FAN_RESPONSE_TEST command, do we? The write to fanotify fd for FAN_NOFD fd would just perform validation of the response and either accept it (do nothing) or return EINVAL. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
