linux-kernel - Re: [PATCH v3 0/1] Relax restrictions on user.* xattr

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Message-ID: <CAJfpegvbkmdneMxMjYMuNM4+RmWT8S7gaTiDzaq+TCzb0UrQrw@mail.gmail.com>
Date:   Mon, 6 Sep 2021 16:56:44 +0200
From:   Miklos Szeredi <miklos@...redi.hu>
To:     "Dr. David Alan Gilbert" <dgilbert@...hat.com>
Cc:     Andreas Gruenbacher <agruenba@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        virtio-fs-list <virtio-fs@...hat.com>,
        Daniel J Walsh <dwalsh@...hat.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        casey.schaufler@...el.com,
        LSM <linux-security-module@...r.kernel.org>,
        SElinux list <selinux@...r.kernel.org>,
        "Theodore Ts'o" <tytso@....edu>,
        Giuseppe Scrivano <gscrivan@...hat.com>,
        "Fields, Bruce" <bfields@...hat.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Dave Chinner <david@...morbit.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH v3 0/1] Relax restrictions on user.* xattr

On Mon, 6 Sept 2021 at 16:39, Dr. David Alan Gilbert
<dgilbert@...hat.com> wrote:

> IMHO the real problem here is that the user/trusted/system/security
> 'namespaces' are arbitrary hacks rather than a proper namespacing
> mechanism that allows you to create new (nested) namespaces and associate
> permissions with each one.

Indeed.

This is what Eric Biederman suggested at some point for supporting
trusted xattrs within a user namespace:

| For trusted xattrs I think it makes sense in principle.   The namespace
| would probably become something like "trusted<ns-root-uid>.".

Theory sounds simple enough.  Anyone interested in looking at the details?

Thanks,
Miklos