linux-kernel - Re: [PATCH] Add ability to disallow idmapped mounts

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Message-ID: <20220204132616.28de9c4a@tower>
Date:   Fri, 4 Feb 2022 13:26:16 +0300
From:   "Anton V. Boyarshinov" <boyarsh@...linux.org>
To:     Christian Brauner <brauner@...nel.org>
Cc:     viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
        ebiederm@...ssion.com, legion@...nel.org, ldv@...linux.org,
        linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
        Christoph Hellwig <hch@....de>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] Add ability to disallow idmapped mounts

В Fri, 4 Feb 2022 10:45:15 +0100
Christian Brauner <brauner@...nel.org> пишет:

> If you want to turn off idmapped mounts you can already do so today via:
> echo 0 > /proc/sys/user/max_user_namespaces

It turns off much more than idmapped mounts only. More fine grained
control seems better for me.

> They can neither
> be created as an unprivileged user nor can they be created inside user
> namespaces.

But actions of fully privileged user can open non-obvious ways to
privilege escalation.