linux-kernel - Re: [PATCH v2 00/10] allow unprivileged overlay mounts

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 8 Dec 2020 19:27:13 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Miklos Szeredi <mszeredi@...hat.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-unionfs@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        John Johansen <john.johansen@...onical.com>
Subject: Re: [PATCH v2 00/10] allow unprivileged overlay mounts

On 2020/12/08 1:32, Miklos Szeredi wrote:
> A general observation is that overlayfs does not call security_path_*()
> hooks on the underlying fs.  I don't see this as a problem, because a
> simple bind mount done inside a private mount namespace also defeats the
> path based security checks.  Maybe I'm missing something here, so I'm
> interested in comments from AppArmor and Tomoyo developers.

Regarding TOMOYO, I don't want overlayfs to call security_path_*() hooks on the
underlying fs, but the reason is different. It is not because a simple bind mount
done inside a private mount namespace defeats the path based security checks.
TOMOYO does want to check what device/filesystem is mounted on which location. But
currently TOMOYO is failing to check it due to fsopen()/fsmount()/move_mount() API.