Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN

[Daniel Micay]

On Tue, 2017-05-30 at 19:00 -0400, Matt Brown wrote:
> On 5/30/17 4:22 PM, Daniel Micay wrote:
> > > Thanks, I didn't know that android was doing this. I still think
> > > this
> > > feature
> > > is worthwhile for people to be able to harden their systems
> > > against
> > > this attack
> > > vector without having to implement a MAC.
> > 
> > Since there's a capable LSM hook for ioctl already, it means it
> > could go
> > in Yama with ptrace_scope but core kernel code would still need to
> > be
> > changed to track the owning tty. I think Yama vs. core kernel
> > shouldn't
> > matter much anymore due to stackable LSMs.
> > 
> 
> What does everyone think about a v8 that moves this feature under Yama
> and uses
> the file_ioctl LSM hook?

It would only make a difference if it could be fully contained there, as
in not depending on tracking the tty owner.