Re: SystemCallFilter

[Lennart Poettering <lennart@xxxxxxxxxxxxxx>]

On Di, 28.05.19 14:04, Josef Moellers (jmoellers@xxxxxxx) wrote:

> > Regarding the syscall groupings: yes, the groups exist precisely to
> > improve cases like this. That said, I think we should be careful not
> > have an inflation of groups, and we should ask twice whether a group
> > is really desirable before adding it. I'd argue in the open/openat
> > case the case is not strong enough though: writing a filter
> > blacklisting those is very difficult, as it means you cannot run
> > programs with dynamic libraries (as loading those requires
> > open/openat), which hence limits the applications very much and
> > restricts its use to very few, very technical cases. In those case I
> > have the suspicion the writer of the filters needs to know in very
> > much detail what the semantics are anyway, and he hence isn't helped
> > too much by this group.
> >
> > Note that the @file-system group already includes both, so maybe
> > that's a more adequate solution? (not usable for blacklisting though,
> > only for whirelisting, realistically).
> >
> > Hence, I would argue this is a documentation issue, not a bug
> > really... Does that make sense?
> Yes.
>
> Linux has always been a moving target and in very many circumstances
> this has been A Good Idea!
> I guess I'm too much old school and try to keep to the principle of
> least surprise.

I added some docs about this to this PR:

https://github.com/systemd/systemd/pull/12686

ptal!

Lennart

--
Lennart Poettering, Berlin
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