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

From: Andy Lutomirski
Date: Tue Jul 23 2019 - 10:04:51 EST

> 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. 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?