From: Kees Cook <keescook@chromium.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: John Wood <john.wood@gmx.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Shuah Khan <shuah@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Arnd Bergmann <arnd@arndb.de>,
valdis.kletnieks@vt.edu,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Randy Dunlap <rdunlap@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-arch@vger.kernel.org,
linux-hardening@vger.kernel.org,
kernel-hardening@lists.openwall.com
Subject: Re: [PATCH v8 0/8] Fork brute force attack mitigation
Date: Wed, 9 Jun 2021 09:52:29 -0700 [thread overview]
Message-ID: <202106090951.8C1B5BAD@keescook> (raw)
In-Reply-To: <cbfd306b-6e37-a697-ebdb-4a5029d36583@linux.intel.com>
On Tue, Jun 08, 2021 at 04:38:15PM -0700, Andi Kleen wrote:
>
> On 6/8/2021 4:19 PM, Kees Cook wrote:
> > On Sat, Jun 05, 2021 at 05:03:57PM +0200, John Wood wrote:
> > > [...]
> > > the kselftest to avoid the detection ;) ). So, in this version, to track
> > > all the statistical data (info related with application crashes), the
> > > extended attributes feature for the executable files are used. The xattr is
> > > also used to mark the executables as "not allowed" when an attack is
> > > detected. Then, the execve system call rely on this flag to avoid following
> > > executions of this file.
> > I have some concerns about this being actually usable and not creating
> > DoS situations. For example, let's say an attacker had found a hard-to-hit
> > bug in "sudo", and starts brute forcing it. When the brute LSM notices,
> > it'll make "sudo" unusable for the entire system, yes?
> >
> > And a reboot won't fix it, either, IIUC.
> >
> The whole point of the mitigation is to trade potential attacks against DOS.
>
> If you're worried about DOS the whole thing is not for you.
Right, but there's no need to make a system unusable for everyone else.
There's nothing here that relaxes the defense (i.e. stop spawning apache
for 10 minutes). Writing it to disk with nothing that undoes it seems a
bit too much. :)
--
Kees Cook
next prev parent reply other threads:[~2021-06-09 16:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-05 15:03 [PATCH v8 0/8] Fork brute force attack mitigation John Wood
2021-06-05 15:03 ` [PATCH v8 1/8] security: Add LSM hook at the point where a task gets a fatal signal John Wood
2021-06-05 15:03 ` [PATCH v8 2/8] security/brute: Define a LSM and add sysctl attributes John Wood
2021-06-05 15:04 ` [PATCH v8 3/8] security/brute: Detect a brute force attack John Wood
2021-06-05 15:04 ` [PATCH v8 4/8] security/brute: Mitigate " John Wood
2021-06-05 15:04 ` [PATCH v8 5/8] security/brute: Notify to userspace "task killed" John Wood
2021-06-05 15:04 ` [PATCH v8 6/8] selftests/brute: Add tests for the Brute LSM John Wood
2021-06-05 15:04 ` [PATCH v8 7/8] Documentation: Add documentation " John Wood
2021-06-05 15:04 ` [PATCH v8 8/8] MAINTAINERS: Add a new entry " John Wood
2021-06-08 23:19 ` [PATCH v8 0/8] Fork brute force attack mitigation Kees Cook
2021-06-08 23:38 ` Andi Kleen
2021-06-09 16:52 ` Kees Cook [this message]
2021-06-11 15:41 ` John Wood
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