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Message-ID: <cbfd306b-6e37-a697-ebdb-4a5029d36583@linux.intel.com>
Date: Tue, 8 Jun 2021 16:38:15 -0700
From: Andi Kleen <ak@...ux.intel.com>
To: Kees Cook <keescook@...omium.org>, John Wood <john.wood@....com>
Cc: Jann Horn <jannh@...gle.com>, Jonathan Corbet <corbet@....net>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
Shuah Khan <shuah@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Arnd Bergmann <arnd@...db.de>, valdis.kletnieks@...edu,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Randy Dunlap <rdunlap@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-arch@...r.kernel.org,
linux-hardening@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v8 0/8] Fork brute force attack mitigation
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.
-Andi
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