Re: fanotify - overall design before I start sending patches

Pavel Machek
2009-08-08T10:34:54Z

Hi!

> > By the above you're hosed anyway since starting a new one will fail due
> > to there being no daemon, right? Might as well forfeit all security
> > measures once the daemon dies. That is let security depend on there
> > being a daemon connected.
>
> Nope. You should stop calling and thinking of it as a security system.
> As I've said multiple times it is at best an indexing and integrity
> checking system. We fail open. We don't prevent or care about
> malicious local attacks. When a group is evicted everything is going to
> just work. The whole reason for the timeout is because I don't trust
> userspace not to get it wrong and I'd rather not lose my box because of
> it. Yes, the reset I'm proposing allows userspace to screw the

Well, if you are using this for hierarchical storage, then this daemon
will bring the system down.

Face it, you _are_ developing a security system; otherwise features of
fanotify do not make sense. (And you are developing _bad_ security
system).

So... what about just scrapping the open vetoing -- at least from
initial version?

> > Seems like a weird thing to me, suppose you DoS the system on purpose
> > and all clients start getting wonky, you kill them all, and are left
> > with non, then you cannot access any of your files anymore and
> > everything grinds to a halt?
>
> Nope, you DoS the system on purpose all the listeners get evicted, now
> everything else will be able to open/read data without those listeners
> paying attention. When a group is evicted it's evicted. It no longer
> needs to say yes or no.

Yes so I hammer your web server and you loose your antivirus
protection.

> > Like said, having the filesystem block actions based on external
> > processes seems just asking for trouble.
>
> Or it seems like exactly what hierarchical storage management systems
> want....

Timeout does not make sense for hierarchical storage.
Pavel

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