[Adding the LSM mailing list: missed this patchset initially]
On Thu, 20 Jun 2019, Andy Lutomirski wrote:
> This patch exemplifies why I don't like this approach:
>
> > @@ -97,6 +97,7 @@ enum lockdown_reason {
> > LOCKDOWN_INTEGRITY_MAX,
> > LOCKDOWN_KCORE,
> > LOCKDOWN_KPROBES,
> > + LOCKDOWN_BPF,
> > LOCKDOWN_CONFIDENTIALITY_MAX,
>
> > --- a/security/lockdown/lockdown.c
> > +++ b/security/lockdown/lockdown.c
> > @@ -33,6 +33,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
> > [LOCKDOWN_INTEGRITY_MAX] = "integrity",
> > [LOCKDOWN_KCORE] = "/proc/kcore access",
> > [LOCKDOWN_KPROBES] = "use of kprobes",
> > + [LOCKDOWN_BPF] = "use of bpf",
> > [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
>
> The text here says "use of bpf", but what this patch is *really* doing
> is locking down use of BPF to read kernel memory. If the details
> change, then every LSM needs to get updated, and we risk breaking user
> policies that are based on LSMs that offer excessively fine
> granularity.
Can you give an example of how the details might change?
> I'd be more comfortable if the LSM only got to see "confidentiality"
> or "integrity".
These are not sufficient for creating a useful policy for the SELinux
case.
--
James Morris
<jmorris@xxxxxxxxx>
