netdev - Re: Possible mistake in commit 3ca459eaba1b ("tun: fix group permission check")

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Message-ID: <fd2f411b-c499-47dc-8472-321d42a35f13@yandex.ru>
Date: Tue, 28 Jan 2025 17:45:43 +0300
From: stsp <stsp2@...dex.ru>
To: Ondrej Mosnacek <omosnace@...hat.com>,
 Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: Willem de Bruijn <willemb@...gle.com>, Jason Wang <jasowang@...hat.com>,
 Jakub Kicinski <kuba@...nel.org>, network dev <netdev@...r.kernel.org>,
 Linux Security Module list <linux-security-module@...r.kernel.org>,
 SElinux list <selinux@...r.kernel.org>
Subject: Re: Possible mistake in commit 3ca459eaba1b ("tun: fix group
 permission check")

28.01.2025 17:20, Ondrej Mosnacek пишет:
> That could work, but the semantics become a bit weird, actually: When
> you set both uid and gid, one of them needs to match. If you unset
> uid/gid, you get a stricter condition (gid/uid must match). And if you
> then also unset the other one, you suddenly get a less strict
> condition than the first two - nothing has to match.
Maybe this means that
unsetting with -1 is something
that shouldn't be done and/or
allowed?
In this case you only stricten.
Modulo the inability to set both
user/group at the same time,
so you still get "less strict" when
setting group after user already
set...