From: Michael Stone <michael@laptop•org>
To: Pavel Machek <pavel@ucw•cz>
Cc: linux-kernel@vger•kernel.org, netdev@vger•kernel.org,
linux-security-module@vger•kernel.org,
"Andi Kleen" <andi@firstfloor•org>, "David Lang" <david@lang•hm>,
"Oliver Hartkopp" <socketcan@hartkopp•net>,
"Alan Cox" <alan@lxorguk•ukuu.org.uk>,
"Herbert Xu" <herbert@gondor•apana.org.au>,
"Valdis Kletnieks" <Valdis.Kletnieks@vt•edu>,
"Bryan Donlan" <bdonlan@gmail•com>,
"Evgeniy Polyakov" <zbr@ioremap•net>,
"C. Scott Ananian" <cscott@cscott•net>,
"James Morris" <jmorris@namei•org>,
"Eric W. Biederman" <ebiederm@xmission•com>,
"Bernie Innocenti" <bernie@codewiz•org>,
"Mark Seaborn" <mrs@mythic-beasts•com>,
"Randy Dunlap" <randy.dunlap@oracle•com>,
"Américo Wang" <xiyou.wangcong@gmail•com>,
"Tetsuo Handa" <penguin-kernel@i-love•sakura.ne.jp>,
"Samir Bellabes" <sam@synack•fr>,
"Casey Schaufler" <casey@schaufler-ca•com>,
"Serge E. Hallyn" <serue@us•ibm.com>,
"Michael Stone" <michael@lapt>
Subject: Re: RFC: disablenetwork facility. (v4)
Date: Mon, 28 Dec 2009 01:07:59 -0500 [thread overview]
Message-ID: <20091228060759.GB13266@heat> (raw)
In-Reply-To: <20091227190802.GH11737@elf.ucw.cz>
Pavel Machek wrote:
> "I can't see" is not strong enough test, I'd say.
>
> For example, I can easily imagine something like pam falling back to
> local authentication when network is unavailable. If you disable
> network for su...
>
> It would be also extremely easy to DoS something like sendmail -- if
> it forks into background and then serves other users' requests.
Pavel,
I spent some time this afternoon reflecting on the scenarios that you sketched
above. This reflection resulted in three concrete responses:
1. Anyone depending on their network for authentication already has to deal
with availability faults. disablenetwork doesn't change anything
fundamental there.
2. Anyone able to use disablenetwork to block a privilege escalation via su
or to influence sendmail will be able to disrupt the privilege escalation
or mail transfer by manipulating the ancestors of su or sendmail in plenty
of other ways including, for example, via ptrace(), kill(), manipulation
of PATH, manipulation of X11 events and IPC, manipulation of TTYs, and so
on.
3. As I pointed out before, disablenetwork _is_ controlled by a build-time
configuration option, its use _is_ still subject to any existing MAC
policy, and it _is_ easy to control for simply by talking to a
known-unrestricted process over an unrestricted IPC channel like a Unix
socket.
and a short meta-response:
As I see it, the whole point of isolation facilities like disablenetwork is
to convert _nasty_ faults like secrecy and integrity faults into _local_
availability faults. Consequently, it is completely unsurprising that we
can't meet stringent availability goals via isolation without either relaxing
our other security goals or falling back to strong assumptions about the
state of our initial environment.
However, we should not therefore ignore the bottom line which is that
the additional isolation enabled by disablenetwork represents an excellent
security risk/reward tradeoff for many people and should be made more widely
available to these people on these grounds.
Regards,
Michael
P.S. - Thanks again for your assistance in thinking through these scenarios and
in refining the security case for the disablenetwork feature.
next prev parent reply other threads:[~2009-12-28 6:07 UTC|newest]
Thread overview: 157+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-27 1:04 RFC: disablenetwork facility. (v4) Michael Stone
2009-12-27 1:06 ` [PATCH 1/3] Security: Add disablenetwork interface. (v4) Michael Stone
2009-12-27 3:26 ` Serge E. Hallyn
2009-12-28 18:13 ` Serge E. Hallyn
2009-12-29 1:21 ` Michael Stone
2009-12-29 5:26 ` Serge E. Hallyn
2009-12-27 7:53 ` Pavel Machek
2009-12-29 1:25 ` Michael Stone
2009-12-30 10:09 ` Pavel Machek
2009-12-30 18:47 ` Serge E. Hallyn
2009-12-27 1:06 ` [PATCH 2/3] Security: Implement disablenetwork semantics. (v4) Michael Stone
2009-12-27 1:20 ` Tetsuo Handa
2009-12-30 18:50 ` Serge E. Hallyn
2010-01-01 14:31 ` Pavel Machek
2010-01-10 21:11 ` James Morris
2010-01-10 21:16 ` Pavel Machek
2010-01-10 21:44 ` James Morris
2010-01-10 21:54 ` Michael Stone
2010-01-10 21:58 ` Pavel Machek
2010-01-10 22:40 ` Michael Stone
2010-01-11 1:07 ` Tetsuo Handa
2010-01-11 1:45 ` Michael Stone
2010-01-11 17:49 ` Serge E. Hallyn
2010-01-12 6:10 ` Michael Stone
2010-01-12 15:52 ` Serge E. Hallyn
2010-01-14 9:23 ` Pavel Machek
2010-01-14 15:00 ` Serge E. Hallyn
2010-01-14 16:36 ` Michael Stone
2010-01-14 16:47 ` Serge E. Hallyn
[not found] ` <20100114171309.GA6372@heat>
2010-01-14 17:36 ` Serge E. Hallyn
2010-01-15 8:10 ` disablenetwork (v5) patches Michael Stone
2010-01-15 8:12 ` disablenetwork (v5): Remove a TOCTTOU race by passing flags by value Michael Stone
2010-01-15 8:12 ` disablenetwork (v5): Simplify the disablenetwork sendmsg hook Michael Stone
2010-01-15 8:13 ` disablenetwork (v5): Require CAP_SETPCAP to enable disablenetwork Michael Stone
2010-01-17 2:58 ` Andrew G. Morgan
[not found] ` <20100117044825.GA2712@heat>
2010-01-17 4:58 ` disablenetwork (v5): Require CAP_SETPCAP to enable Andrew G. Morgan
2010-01-18 19:30 ` Serge E. Hallyn
2010-01-15 8:13 ` disablenetwork (v5): Update documentation for PR_NETWORK_ENABLE_DN Michael Stone
2010-01-17 6:01 ` disablenetwork (v5) patches Kyle Moffett
[not found] ` <20100117180728.GA2848@heat>
2010-01-17 21:17 ` Kyle Moffett
2010-01-11 1:46 ` [PATCH 2/3] Security: Implement disablenetwork semantics. (v4) Casey Schaufler
2010-01-12 3:19 ` Valdis.Kletnieks
2010-01-12 4:01 ` Casey Schaufler
2010-01-11 12:01 ` Pavel Machek
2010-01-12 2:54 ` Valdis.Kletnieks
2010-01-12 7:59 ` Pavel Machek
2010-01-12 14:28 ` Valdis.Kletnieks
2010-01-14 9:22 ` Pavel Machek
2010-01-18 12:54 ` Valdis.Kletnieks
2010-01-18 15:56 ` Andrew G. Morgan
2010-01-10 22:18 ` Kyle Moffett
2010-01-10 23:08 ` Michael Stone
2010-01-10 23:41 ` Bryan Donlan
2010-01-11 1:50 ` Casey Schaufler
2010-01-11 2:15 ` Bryan Donlan
2010-01-11 11:53 ` Pavel Machek
2010-01-10 22:58 ` James Morris
2009-12-27 1:07 ` [PATCH 3/3] Security: Document disablenetwork. (v4) Michael Stone
2009-12-27 1:39 ` Tetsuo Handa
2009-12-27 16:25 ` Michael Stone
2009-12-27 8:36 ` RFC: disablenetwork facility. (v4) Tetsuo Handa
2009-12-27 8:38 ` Pavel Machek
2009-12-27 11:49 ` Tetsuo Handa
2009-12-27 12:18 ` Al Viro
2009-12-27 15:03 ` Serge E. Hallyn
2009-12-27 15:47 ` Michael Stone
2009-12-27 16:12 ` Serge E. Hallyn
2009-12-27 16:36 ` Michael Stone
2009-12-27 18:06 ` Pavel Machek
2009-12-27 19:08 ` Pavel Machek
2009-12-28 6:07 ` Michael Stone [this message]
2009-12-28 10:10 ` Pavel Machek
2009-12-28 14:37 ` Valdis.Kletnieks
2009-12-28 20:55 ` Pavel Machek
2009-12-28 21:28 ` Valdis.Kletnieks
2009-12-28 21:33 ` Bryan Donlan
2009-12-29 6:08 ` Serge E. Hallyn
2010-01-01 15:06 ` Pavel Machek
2009-12-28 16:31 ` Michael Stone
2009-12-28 21:08 ` Pavel Machek
2009-12-28 21:24 ` Valdis.Kletnieks
2009-12-28 18:13 ` Serge E. Hallyn
2009-12-29 5:01 ` Michael Stone
2009-12-29 5:56 ` Serge E. Hallyn
2009-12-29 16:31 ` Michael Stone
2009-12-29 11:06 ` Eric W. Biederman
2009-12-29 15:11 ` Serge E. Hallyn
2009-12-29 16:05 ` Bryan Donlan
2009-12-29 16:39 ` Serge E. Hallyn
2009-12-29 17:01 ` Bryan Donlan
2009-12-29 18:36 ` Eric W. Biederman
2009-12-29 19:08 ` Bryan Donlan
2009-12-29 20:56 ` Eric W. Biederman
2009-12-29 21:27 ` Serge E. Hallyn
2009-12-29 21:46 ` Valdis.Kletnieks
2009-12-29 22:16 ` Serge E. Hallyn
2009-12-29 20:10 ` Benny Amorsen
2009-12-29 20:40 ` Eric W. Biederman
2009-12-29 20:43 ` Bryan Donlan
2009-12-29 21:11 ` Alan Cox
2009-12-29 21:14 ` Bryan Donlan
2009-12-29 21:35 ` Alan Cox
2009-12-29 21:29 ` Eric W. Biederman
2009-12-29 22:36 ` Serge E. Hallyn
2009-12-30 3:26 ` Eric W. Biederman
2009-12-30 3:50 ` Serge E. Hallyn
2009-12-30 4:29 ` Eric W. Biederman
2009-12-30 18:00 ` Serge E. Hallyn
2009-12-30 21:12 ` Eric W. Biederman
2009-12-30 3:35 ` [RFC][PATCH] Unprivileged: Disable acquisition of privileges Eric W. Biederman
2009-12-30 3:54 ` Bryan Donlan
2009-12-30 4:33 ` Eric W. Biederman
2009-12-30 4:57 ` Bryan Donlan
2009-12-30 12:47 ` Eric W. Biederman
2009-12-30 12:49 ` [RFC][PATCH v2] Unprivileged: Disable raising " Eric W. Biederman
2009-12-30 14:52 ` Andrew G. Morgan
2009-12-30 18:35 ` Serge E. Hallyn
2009-12-30 20:07 ` Eric W. Biederman
2009-12-30 20:17 ` Serge E. Hallyn
2009-12-30 21:15 ` [RFC][PATCH v3] " Eric W. Biederman
2009-12-30 21:29 ` Alan Cox
2009-12-30 21:36 ` Eric W. Biederman
2009-12-30 23:00 ` Alan Cox
2009-12-31 2:44 ` Bryan Donlan
2009-12-31 17:33 ` Alan Cox
2009-12-31 17:52 ` Serge E. Hallyn
2009-12-31 18:20 ` Andrew G. Morgan
2009-12-31 18:32 ` Eric W. Biederman
2010-01-01 14:43 ` Alan Cox
2010-01-01 14:53 ` Pavel Machek
2010-01-01 16:26 ` Eric W. Biederman
2010-01-01 21:35 ` Casey Schaufler
2010-01-01 22:39 ` Alan Cox
2010-01-01 23:18 ` Casey Schaufler
2010-01-02 0:42 ` Peter Dolding
[not found] ` <4B3FB0FC.3030809@schaufler-ca.com>
2010-01-03 1:43 ` Peter Dolding
2009-12-31 18:41 ` Eric W. Biederman
2009-12-31 21:46 ` Serge E. Hallyn
2010-01-01 21:17 ` Andrew G. Morgan
2010-01-01 14:57 ` Alan Cox
2009-12-31 8:57 ` Eric W. Biederman
2009-12-31 13:00 ` Samir Bellabes
2009-12-31 14:08 ` Peter Dolding
2009-12-31 17:06 ` Alan Cox
2010-01-01 0:12 ` Peter Dolding
2010-01-01 10:28 ` Pavel Machek
2009-12-31 15:25 ` Serge E. Hallyn
2009-12-31 16:48 ` Eric W. Biederman
2009-12-30 18:29 ` [RFC][PATCH v2] " Serge E. Hallyn
2009-12-30 20:45 ` Eric W. Biederman
2009-12-29 18:03 ` RFC: disablenetwork facility. (v4) Eric W. Biederman
2009-12-29 16:06 ` Michael Stone
2010-01-01 15:11 ` Pavel Machek
2009-12-27 8:51 ` Al Viro
2009-12-27 11:23 ` Valdis.Kletnieks
2009-12-27 12:45 ` Andi Kleen
2009-12-27 15:55 ` Michael Stone
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