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

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Tue, 7 Sep 2021 17:40:31 -0400
From:   Vivek Goyal <vgoyal@...hat.com>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     "Dr. David Alan Gilbert" <dgilbert@...hat.com>,
        Andreas Gruenbacher <agruenba@...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, Sep 06, 2021 at 04:56:44PM +0200, Miklos Szeredi wrote:
> 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?

So this namespaced trusted.* xattr domain will basically avoid the need
to have CAP_SYS_ADMIN in init_user_ns, IIUC.  I guess this is better
than giving CAP_SYS_ADMIN in init_user_ns.

Vivek