linux-kernel - Re: [PATCH v2 03/10] ovl: check privs before decoding file handle

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]

Message-ID: <CAOQ4uxjDEVnz3Y_BqH41J4+E5dWRPyut_VPokEeMBNALx9oQhw@mail.gmail.com>
Date:   Wed, 9 Dec 2020 20:16:10 +0200
From:   Amir Goldstein <amir73il@...il.com>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Miklos Szeredi <mszeredi@...hat.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        overlayfs <linux-unionfs@...r.kernel.org>,
        LSM List <linux-security-module@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 03/10] ovl: check privs before decoding file handle

On Wed, Dec 9, 2020 at 6:20 PM Miklos Szeredi <miklos@...redi.hu> wrote:
>
> On Wed, Dec 9, 2020 at 11:13 AM Miklos Szeredi <miklos@...redi.hu> wrote:
>
> > Hard link indexing should work without fh decoding, since it is only
> > encoding the file handle to search for the index entry, and encoding
> > is not privileged.
>
> Tested this a bit and while hard link indexing does work,  inode
> lookup is broken since it uses the origin inode as a key (which is not

Yes, that is what I meant by ovl_check_origin() is broken.

> available) instead of using the origin value directly.  This is
> fixable, but needs a fair amount of restructuring, so let's just

Maybe it also requires on-disk changes.
We should be able to use the origin fh as the key for lower inode,
but we need the lower st_inode for initializing the ovl inode with
correct ino. If we cannot decode lower inode from origin fh, I think
we would need to store the ino in user.overlay.ino on copy up or
maintain redirect, but redirect is not supported either with user ns mount...

> postpone this and disable index for now, as you suggested.
>

Nobody seems to be enabling it anyway :-/

Thanks,
Amir.