lkml.org 
[lkml]   [2013]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: proc hidepid=2 and SGID programs
On Sun, Sep 15, 2013 at 01:58 -0700, Christian Kujau wrote:
> Vasiliy Kulikov <segoon@openwall.com> wrote:
> >> But still, I wonder if this is
> >> intended behaviour.
> >
> >Yes.
> >
> >If you think such side channel attacks are something you don't care,
> >just turn hidepid off. That's why it is an option.
> >
> >If you want to turn it off for some users, use gid=XXX.
>
> Maybe my initial question got lost in the noise: I merely wondered why "pgrep sgid-program" returned nothing but "kill pics off stiff program" was possible. Sure, if that's intended behavior, so be it. I just don't understand the (technical) reasoning behind this.

If process A may ptrace process B, A may kill B. In this case A may see
any information about B.

If process A may not ptrace process B, A probably still may kill B. But
A may not see any information about B.

In sense of information gathering hidepid doesn't differ setgid'ed
processes and common processes of another user. As *some* privileges
differ between a subject and an object, they are considered as being in
different security domains. Information leakage crossing the
interdomain border between these domains might help an attacker, so it
is denied.

--
Vasily Kulikov
http://www.openwall.com - bringing security into open computing environments


\
 
 \ /
  Last update: 2013-09-19 14:01    [W:0.086 / U:0.304 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site