linux-kernel - Re: [RFC PATCH] Add /proc/<pid>/numa

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 4 May 2018 13:12:11 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     "prakash.sangappa" <prakash.sangappa@...cle.com>
Cc:     Christopher Lameter <cl@...ux.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-api@...r.kernel.org,
        akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com,
        n-horiguchi@...jp.nec.com, drepper@...il.com, rientjes@...gle.com
Subject: Re: [RFC PATCH] Add /proc/<pid>/numa_vamaps for numa node information

On Thu 03-05-18 15:39:49, prakash.sangappa wrote:
> 
> 
> On 05/03/2018 11:03 AM, Christopher Lameter wrote:
> > On Tue, 1 May 2018, Prakash Sangappa wrote:
> > 
> > > For analysis purpose it is useful to have numa node information
> > > corresponding mapped address ranges of the process. Currently
> > > /proc/<pid>/numa_maps provides list of numa nodes from where pages are
> > > allocated per VMA of the process. This is not useful if an user needs to
> > > determine which numa node the mapped pages are allocated from for a
> > > particular address range. It would have helped if the numa node information
> > > presented in /proc/<pid>/numa_maps was broken down by VA ranges showing the
> > > exact numa node from where the pages have been allocated.
> > Cant you write a small script that scans the information in numa_maps and
> > then displays the total pages per NUMA node and then a list of which
> > ranges have how many pages on a particular node?
> 
> Don't think we can determine which numa node a given user process
> address range has pages from, based on the existing 'numa_maps' file.

yes we have. See move_pages...
 
> > > reading this file will not be restricted(i.e requiring CAP_SYS_ADMIN).
> > So a prime motivator here is security restricted access to numa_maps?
> No it is the opposite. A regular user should be able to determine
> numa node information.

Well, that breaks the layout randomization, doesn't it?
-- 
Michal Hocko
SUSE Labs