Re: [PATCH 1/1] userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK

[Mike Rapoport]

Hi Daniel,

On Tue, Nov 05, 2019 at 08:41:18AM -0800, Daniel Colascione wrote:
> On Tue, Nov 5, 2019 at 8:24 AM Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote:
> > The long term plan is to introduce UFFD_FEATURE_EVENT_FORK2 feature
> > flag that uses the ioctl to receive the child uffd, it'll consume more
> > CPU, but it wouldn't require the PTRACE privilege anymore.
> 
> Why not just have callers retrieve FDs using recvmsg? This way, you
> retrieve the message packet and the file descriptor at the same time
> and you don't need any appreciable extra CPU use.

I don't follow you here. Can you elaborate on how recvmsg would be used in
this case?

-- 
Sincerely yours,
Mike.