From: Willy Tarreau <w@1wt.eu>
To: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
"security@kernel.org" <security@kernel.org>,
X86 ML <x86@kernel.org>, Borislav Petkov <bp@alien8.de>,
Sasha Levin <sasha.levin@oracle.com>,
linux-kernel@vger.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Jan Beulich <jbeulich@suse.com>,
xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH v4 2/3] x86/ldt: Make modify_ldt optional
Date: Sat, 25 Jul 2015 08:23:43 +0200 [thread overview]
Message-ID: <20150725062343.GA3902@1wt.eu> (raw)
In-Reply-To: <7286d77aa81abc38dc40362e2439861427064f6f.1437802102.git.luto@kernel.org>
On Fri, Jul 24, 2015 at 10:36:45PM -0700, Andy Lutomirski wrote:
> The modify_ldt syscall exposes a large attack surface and is
> unnecessary for modern userspace. Make it optional.
Andy, you didn't respond whether you think it wouldn't be better to make
it runtime-configurable instead. The goal here is to ensure distros
ship with modify_ldt disabled by default. But if it means breaking
compatibility with (rare) existing applications, I'm seeing a risk
that they'll ship with it enabled instead, which would make the config
option useless. The CONFIG_DEFAULT_MMAP_ADDR was a good example of
successful deployment of a hardening measure that has been widely
adopted despite its (low) risk of breakage in field because it was
adjustable in field.
That's why here I think we should do the same, and possibly even
emit a warning once to report the first user of modify_ldt if that
can help.
What do you think ?
Willy
next prev parent reply other threads:[~2015-07-25 6:24 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-25 5:36 [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option Andy Lutomirski
2015-07-25 5:36 ` [PATCH v4 1/3] x86/ldt: Make modify_ldt synchronous Andy Lutomirski
2015-07-25 9:03 ` Borislav Petkov
2015-07-25 5:36 ` [PATCH v4 2/3] x86/ldt: Make modify_ldt optional Andy Lutomirski
2015-07-25 6:23 ` Willy Tarreau [this message]
2015-07-25 6:44 ` Andy Lutomirski
2015-07-25 7:50 ` Willy Tarreau
2015-07-25 13:03 ` [PATCH 4/3] x86/ldt: allow to disable modify_ldt at runtime Willy Tarreau
2015-07-25 16:08 ` Andy Lutomirski
2015-07-25 16:33 ` Willy Tarreau
2015-07-25 17:42 ` Andy Lutomirski
2015-07-25 18:45 ` Willy Tarreau
2015-07-27 19:04 ` Kees Cook
2015-07-27 21:37 ` Willy Tarreau
2015-07-25 9:15 ` [PATCH v4 2/3] x86/ldt: Make modify_ldt optional Borislav Petkov
2015-07-25 16:03 ` Andy Lutomirski
2015-07-25 16:35 ` Willy Tarreau
2015-07-25 5:36 ` [PATCH v4 3/3] selftests/x86, x86/ldt: Add a selftest for modify_ldt Andy Lutomirski
2015-07-27 15:52 ` [PATCH v4.1 3.3] " Andy Lutomirski
2015-07-25 6:27 ` [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option Willy Tarreau
2015-07-27 15:36 ` Boris Ostrovsky
2015-07-27 15:53 ` Andy Lutomirski
2015-07-27 16:18 ` Boris Ostrovsky
2015-07-28 2:20 ` Andy Lutomirski
2015-07-28 3:16 ` Andy Lutomirski
2015-07-28 3:23 ` Andy Lutomirski
2015-07-28 3:43 ` Boris Ostrovsky
2015-07-28 10:29 ` Andrew Cooper
2015-07-28 14:05 ` Boris Ostrovsky
2015-07-28 14:35 ` Andrew Cooper
2015-07-28 14:50 ` Boris Ostrovsky
2015-07-28 15:15 ` Konrad Rzeszutek Wilk
2015-07-28 15:39 ` Boris Ostrovsky
2015-07-28 15:23 ` Andrew Cooper
2015-07-28 15:59 ` [Xen-devel] " Boris Ostrovsky
2015-07-28 15:43 ` Andy Lutomirski
2015-07-28 16:30 ` Andrew Cooper
2015-07-28 17:07 ` Andy Lutomirski
2015-07-28 17:10 ` [Xen-devel] " Boris Ostrovsky
2015-07-29 0:21 ` Andy Lutomirski
2015-07-29 0:47 ` Andrew Cooper
2015-07-29 3:01 ` Boris Ostrovsky
2015-07-29 4:26 ` Andy Lutomirski
2015-07-29 5:28 ` Andy Lutomirski
2015-07-29 14:21 ` Andrew Cooper
2015-07-29 14:43 ` Boris Ostrovsky
2015-07-29 19:03 ` Andrew Cooper
2015-07-29 21:23 ` Boris Ostrovsky
2015-07-29 21:26 ` Andy Lutomirski
2015-07-29 21:33 ` Boris Ostrovsky
2015-07-29 21:37 ` Andrew Cooper
2015-07-29 22:05 ` Andy Lutomirski
2015-07-29 22:11 ` Andrew Cooper
2015-07-29 22:40 ` Boris Ostrovsky
2015-07-29 22:46 ` David Vrabel
2015-07-29 22:49 ` Boris Ostrovsky
2015-07-29 22:55 ` David Vrabel
2015-07-29 23:02 ` Andrew Cooper
2015-07-29 23:13 ` Andy Lutomirski
2015-07-30 0:29 ` Andrew Cooper
2015-07-30 18:30 ` Andy Lutomirski
2015-07-30 18:54 ` Andrew Cooper
2015-07-30 20:01 ` Boris Ostrovsky
2015-07-30 20:05 ` Andy Lutomirski
2015-07-30 20:18 ` Boris Ostrovsky
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