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

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Date:   Mon, 23 Jan 2023 20:21:28 +0100
From:   Giuseppe Scrivano <gscrivan@...hat.com>
To:     "Colin Walters" <walters@...bum.org>
Cc:     linux-kernel@...r.kernel.org, "Kees Cook" <keescook@...omium.org>,
        bristot@...hat.com, "Eric W. Biederman" <ebiederm@...ssion.com>,
        brauner@...nel.org, "Aleksa Sarai" <cyphar@...har.com>,
        "Al Viro" <viro@...iv.linux.org.uk>,
        "Alexander Larsson" <alexl@...hat.com>, peterz@...radead.org,
        bmasney@...hat.com
Subject: Re: [PATCH v3 1/2] exec: add PR_HIDE_SELF_EXE prctl

"Colin Walters" <walters@...bum.org> writes:

> On Fri, Jan 20, 2023, at 5:25 AM, 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.
>
> How about a mount option for procfs like `mount -t procfs procfs /proc -o rw,nosuid,nodev,magiclink-no-xdev`
>
> Where `magiclink-no-xdev` would cause all magic links to fail to cross a pid namespace or so?

wouldn't that break also stuff like "/proc/self/fd/$FD" after you join a
different PID namespace?