linux-kernel - Re: [PATCH] memfd: drop warning for missing exec-related flags

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Date:   Sun, 10 Sep 2023 14:35:04 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Aleksa Sarai <cyphar@...har.com>
Cc:     Damian Tometzki <dtometzki@...oraproject.org>,
        Christian Brauner <brauner@...nel.org>,
        Daniel Verkamp <dverkamp@...omium.org>,
        Jeff Xu <jeffxu@...gle.com>, Kees Cook <keescook@...omium.org>,
        Shuah Khan <shuah@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memfd: drop warning for missing exec-related flags

On Wed, 06 Sep 2023 17:02:06 +1000 Aleksa Sarai <cyphar@...har.com> wrote:

> Commit 434ed3350f57 ("memfd: improve userspace warnings for missing
> exec-related flags") attempted to make these warnings more useful (so
> they would work as an incentive to get users to switch to specifying
> these flags -- as intended by the original MFD_NOEXEC_SEAL patchset).
> Unfortunately, it turns out that even INFO-level logging is too extreme
> to enable by default and alternative solutions to the spam issue (such
> as doing more extreme rate-limiting per-task) are either too ugly or
> overkill for something as simple as emitting a log as a developer aid.
> 
> Given that the flags are new and there is no harm to not specifying them
> (after all, we maintain backwards compatibility) we can just drop the
> warnings for now until some time in the future when most programs have
> migrated and distributions start using vm.memfd_noexec=1 (where failing
> to pass the flag would result in unexpected errors for programs that use
> executable memfds).
> 
> Fixes: 434ed3350f57 ("memfd: improve userspace warnings for missing exec-related flags")

This was reverted, so please propose a new patch against 6.6-rc1.