[PATCH v3 3/7] mm, security: Fix missed security_task_movememory()

[Yafang Shao]

On Sat, Dec 2, 2023 at 4:50 AM Serge E. Hallyn <serge at hallyn.com> wrote:
>
> On Fri, Dec 01, 2023 at 09:46:32AM +0000, Yafang Shao wrote:
> > Considering that MPOL_F_NUMA_BALANCING or  mbind(2) using either
> > MPOL_MF_MOVE or MPOL_MF_MOVE_ALL are capable of memory movement, it's
> > essential to include security_task_movememory() to cover this
> > functionality as well. It was identified during a code review.
>
> Hm - this doesn't have any bad side effects for you when using selinux?
> The selinux_task_movememory() hook checks for PROCESS__SETSCHED privs.
> The two existing security_task_movememory() calls are in cases where we
> expect the caller to be affecting another task identified by pid, so
> that makes sense.  Is an MPOL_MV_MOVE to move your own pages actually
> analogous to that?
>
> Much like the concern you mentioned in your intro about requiring
> CAP_SYS_NICE and thereby expanding its use, it seems that here you
> will be regressing some mbind users unless the granting of PROCESS__SETSCHED
> is widened.

Ah, it appears that this change might lead to regression. I overlooked
its association with the PROCESS__SETSCHED privilege. I'll exclude
this patch from the upcoming version.
Thanks for your review.

-- 
Regards
Yafang