linux-kernel - Re: [PATCH] kernel/fs: last check for exec credentials on NOEXEC mount

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Message-ID: <C96FCBBF-6D63-431F-AEA8-81B7937CB9B1@kernel.org>
Date: Thu, 01 Aug 2024 20:28:12 -0700
From: Kees Cook <kees@...nel.org>
To: Wojciech Gładysz <wojciech.gladysz@...ogain.com>,
 viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
 ebiederm@...ssion.com, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kernel/fs: last check for exec credentials on NOEXEC mount



On August 1, 2024 5:07:45 AM PDT, "Wojciech Gładysz" <wojciech.gladysz@...ogain.com> wrote:
>Test case: thread mounts NOEXEC fuse to a file being executed.
>WARN_ON_ONCE is triggered yielding panic for some config.
>Add a check to security_bprm_creds_for_exec(bprm).

As others have noted, this is racy. I would still like to keep the redundant check as-is, but let's lower it from WARN to pr_warn_ratelimited, since it's a known race that can be reached from userspace.

-- 
Kees Cook