linux-kernel - Re: [PATCH 03/26] signal: Do not perform permission checks when sending pdeath

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:   Tue, 6 Jun 2017 13:01:40 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kees Cook <keescook@...omium.org>,
        Roland McGrath <roland@...k.frob.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        David Howells <dhowells@...hat.com>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
Subject: Re: [PATCH 03/26] signal: Do not perform permission checks when
 sending pdeath_signal

On Tue, Jun 6, 2017 at 12:03 PM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
>
> As this is more permisssive there is no chance anything will break.

Actually, I do worry about the security issues here.

The thing is, the parent may be some system daemon that wants to catch
SIGCHLD, but we've used prctl and changed pdeath_signal to something
else (like SIGSEGV or something).

Do we really want to be able to kill a system daemon that we couldn't
use kill() on directly, just because that system daemon spawned us?

So I think those permission checks may actually be a good idea.
Although possibly they should be in prctl()..

                   Linus