Re: [PATCH 6/7] Allow users to require UFFD_SECURE

[Andy Lutomirski]

On Sat, Oct 12, 2019 at 12:16 PM Daniel Colascione <dancol@xxxxxxxxxx> wrote:
>
> This change adds 2 as an allowable value for
> unprivileged_userfaultfd. (Previously, this sysctl could be either 0
> or 1.) When unprivileged_userfaultfd is 2, users with CAP_SYS_PTRACE
> may create userfaultfd with or without UFFD_SECURE, but users without
> CAP_SYS_PTRACE must pass UFFD_SECURE to userfaultfd in order for the
> system call to succeed, effectively forcing them to opt into
> additional security checks.

This patch can go away entirely if you make UFFD_SECURE automatic.