Re: /dev/ksyms permissions

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 18/01/2018 à 11:03, Tom Ivar Helbekkmo a écrit :
> Maxime Villard <max%M00nBSD.net@localhost> writes:
>
> > So, making /dev/ksyms 440 root:kmem should not break anything.
> >
> > If it does, then there's a bug in the offending tool in the first place.
>
> Agreed.  systat is one of them.  It takes care to call kvm_openfiles()
> while setgid kmem, but kvm_openfiles() doesn't open /dev/ksyms,
> expecting that the other kvm functions can do that at need.  So when
> e.g. 'systat vmstat' calls kvm_nlist() after privileges have been
> dropped, it fails:
>
> systat: nlist: can't find following symbols:
>   _intrnames
>   _eintrnames
>   _intrcnt
>   _eintrcnt
>   _allevents

Well, looking at the code, it seems to me that _kvm_open() should be changed
to keep /dev/ksyms open, the same way it keeps /dev/kmem open.