Re: [PATCH v3 1/2] exec: add PR_HIDE_SELF_EXE prctl

[Kees Cook]

On Fri, Jan 27, 2023 at 01:31:13PM +0100, Christian Brauner wrote:
> From: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>
> 
> 
> 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@xxxxxxxxxxxx>

-- 
Kees Cook