Date:   Fri, 27 Jan 2023 12:34:50 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Christian Brauner <brauner@kernel.org>
Cc:     Giuseppe Scrivano <gscrivan@redhat.com>, bristot@redhat.com,
        ebiederm@xmission.com, cyphar@cyphar.com, viro@zeniv.linux.org.uk,
        alexl@redhat.com, peterz@infradead.org, bmasney@redhat.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] exec: add PR_HIDE_SELF_EXE prctl
Message-ID: <202301271234.8E4A4ED@keescook>
References: <20230120102512.3195094-1-gscrivan@redhat.com>
 <167482213665.546991.3626486119597692007.b4-ty@kernel.org>
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On Fri, Jan 27, 2023 at 01:31:13PM +0100, Christian Brauner wrote:
> From: Christian Brauner (Microsoft) <brauner@kernel.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@chromium.org>

-- 
Kees Cook