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

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Message-ID: <CAJfpeguvt-Mia9YmT55q3R9tSFocpgq7FzjDKJgnaOEQsaBNVA@mail.gmail.com>
Date:   Wed, 9 Dec 2020 17:20:43 +0100
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Amir Goldstein <amir73il@...il.com>
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 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
available) instead of using the origin value directly.  This is
fixable, but needs a fair amount of restructuring, so let's just
postpone this and disable index for now, as you suggested.

Thanks,
Miklos