Re: [5.2 REGRESSION] Generic vDSO breaks seccomp-enabled userspace on i386

[Peter Zijlstra]

On Tue, Jul 23, 2019 at 07:04:46AM -0700, Andy Lutomirski wrote:
> 
> 
> > On Jul 23, 2019, at 2:18 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > 
> >> On Mon, Jul 22, 2019 at 04:47:36PM -0700, Andy Lutomirski wrote:
> >> 
> >> I don't love this whole concept, but I also don't have a better idea.
> > 
> > Are we really talking about changing the kernel because BPF is expecting
> > things? That is, did we just elevate everything BPF can observe to ABI?
> > 
> 
> No, this isnât about internals in the kernel mode sense.

*phew*, I was scared for a wee moment.

> Itâs about the smallish number of cases where the kernel causes user
> code to do a specific syscall and the user has a policy that doesnât
> allow that syscall.  This is visible to user code via seccomp and
> ptrace.
> 
> Yes, itâs obnoxious.  Do you have any suggestions?

Not really; I think I just demonstrated I don't fully understand the
problem space here :/