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]
Message-ID: <m1ipwu5lj2.fsf@fess.ebiederm.org>
Date:	Tue, 08 Feb 2011 12:17:05 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Kees Cook <kees.cook@...onical.com>
Cc:	James Morris <jmorris@...ei.org>, linux-kernel@...r.kernel.org,
	Al Viro <viro@....linux.org.uk>
Subject: Re: [SECURITY] /proc/$pid/ leaks contents across setuid exec

Kees Cook <kees.cook@...onical.com> writes:

> On Tue, Feb 08, 2011 at 02:43:15PM +1100, James Morris wrote:
>> On Mon, 7 Feb 2011, Kees Cook wrote:
>> > Sure, I know about O_CLOEXEC, but this is about protecting the
>> > just-been-execed setuid process from the attacking process that has no
>> > reason to set O_CLOEXEC.
>> > 
>> > Something like this needs to be enforced on the kernel side. I.e. these
>> > file in /proc need to have O_CLOEXEC set in a way that cannot be unset.
>> > 
>> > > Changing the behavior in the core kernel will break userspace.
>> > 
>> > I don't think /proc/$pid/* needs to stay open across execs, does it? Or at
>> > least the non-0444 files should be handled separately.
>> 
>> Actually, this seems like a more general kind of bug in proc rather than a 
>> leaked fd.  Each child task should only see its own /proc/[pid] data.
>
> Right, that's precisely the problem. The unprivileged process can read
> the setuid process's /proc files.

If these are things that we actually care about we should sprinkle in a
few more ptrace_may_access calls into implementations of the relevant
proc files.


Eric
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ