linux-kernel - Re: [PATCH v3 1/2] exec: add PR_HIDE_SELF

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: <202301271234.8E4A4ED@keescook>
Date:   Fri, 27 Jan 2023 12:34:50 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Christian Brauner <brauner@...nel.org>
Cc:     Giuseppe Scrivano <gscrivan@...hat.com>, bristot@...hat.com,
        ebiederm@...ssion.com, cyphar@...har.com, viro@...iv.linux.org.uk,
        alexl@...hat.com, peterz@...radead.org, bmasney@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] exec: add PR_HIDE_SELF_EXE prctl

On Fri, Jan 27, 2023 at 01:31:13PM +0100, Christian Brauner wrote:
> From: Christian Brauner (Microsoft) <brauner@...nel.org>
> 
> 
> On Fri, 20 Jan 2023 11:25:11 +0100, Giuseppe Scrivano wrote:
> > This patch adds a new prctl called PR_HIDE_SELF_EXE which allows
> > processes to hide their own /proc/*/exe file. When this prctl is
> > used, every access to /proc/*/exe for the calling process will
> > fail with ENOENT.
> > 
> > This is useful for preventing issues like CVE-2019-5736, where an
> > attacker can gain host root access by overwriting the binary
> > in OCI runtimes through file-descriptor mishandling in containers.
> > 
> > [...]
> 
> Only needed for privileged sandboxes. The userspace mitigations Aleksa
> and I did for the CVE in all affected runtimes back then are nifty but
> complicated. The patch is a decent compromise.
> Picking up this prctl() for now,
> 
> [1/2] exec: add PR_HIDE_SELF_EXE prctl
>       commit: 673301182d473ef61a98c292cf64650c73117172
> [2/2] selftests: add tests for prctl(SET_HIDE_SELF_EXE)
>       commit: bafa339eda3f79d567386e1fae59bb0537156c96

Thanks! I'm late to the party, but I came to the same conclusion as you
did. :)

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook