kernelnewbies.kernelnewbies.org archive mirror
 help / color / mirror / Atom feed
From: Andi Kleen <ak@linux.intel.com>
To: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
Cc: kernel-hardening@lists.openwall.com,
	John Wood <john.wood@gmx.com>, Kees Cook <keescook@chromium.org>,
	kernelnewbies@kernelnewbies.org
Subject: Re: Notify special task kill using wait* functions
Date: Wed, 7 Apr 2021 18:51:48 -0700	[thread overview]
Message-ID: <20210408015148.GB3762101@tassilo.jf.intel.com> (raw)
In-Reply-To: <184666.1617827926@turing-police>

> I didn't even finish the line that starts "From now on.." before I started
> wondering "How can I abuse this to hang or crash a system?"  And it only took
> me a few seconds to come up with an attack. All you need to do is find a way to
> sigsegv /bin/bash... and that's easy to do by forking, excecve /bin/bash, and
> then use ptrace() to screw the child process's stack and cause a sigsegv.
> 
> Say goodnight Gracie...

Yes there is certainly DoS potential, but that's kind of inevitable
for the proposal. It's a trade between allowing attacks and allowing DoS,
with the idea that a DoS is more benign.

I'm more worried that it doesn't actually prevent the attacks 
unless we make sure systemd and other supervisor daemons understand it,
so that they don't restart.

Any caching of state is inherently insecure because any caches of limited
size can be always thrashed by a purposeful attacker. I suppose the
only thing that would work is to actually write something to the 
executable itself on disk, but of course that doesn't always work either.

-Andi

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

  reply	other threads:[~2021-04-08  2:06 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30 17:34 John Wood
2021-03-30 18:40 ` Valdis Klētnieks
2021-04-02 12:49   ` John Wood
2021-04-03  3:50     ` Valdis Klētnieks
2021-04-03  7:02       ` John Wood
2021-04-03 21:34         ` Valdis Klētnieks
2021-04-04  9:48           ` John Wood
2021-04-04 21:10             ` Valdis Klētnieks
2021-04-05  7:31               ` John Wood
2021-04-06 23:55                 ` Valdis Klētnieks
2021-04-07 17:51                   ` John Wood
2021-04-07 20:38                     ` Valdis Klētnieks
2021-04-08  1:51                       ` Andi Kleen [this message]
2021-04-09 14:29                         ` John Wood
2021-04-09 15:06                           ` Andi Kleen
2021-04-09 16:08                             ` John Wood
2021-04-09 23:28                             ` Valdis Klētnieks
2021-04-11  8:46                               ` John Wood

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210408015148.GB3762101@tassilo.jf.intel.com \
    --to=ak@linux.intel.com \
    --cc=john.wood@gmx.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=kernelnewbies@kernelnewbies.org \
    --cc=valdis.kletnieks@vt.edu \
    --subject='Re: Notify special task kill using wait* functions' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).