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From: Andy Lutomirski <luto@amacapital.net>
Date: Mon, 30 Jun 2014 07:49:41 -0700
Message-ID: <CALCETrU=HLmw9n-DxPkFV1xP5wtzQ7-YF3-uao6YiGZODA9kdw@mail.gmail.com>
Subject: Re: [PATCH 01/11] fs: add O_BENEATH_ONLY flag to openat(2)
To: David Drysdale <drysdale@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
        LSM List <linux-security-module@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        James Morris <james.l.morris@oracle.com>,
        Kees Cook <keescook@chromium.org>,
        Linux API <linux-api@vger.kernel.org>,
        Meredydd Luff <meredydd@senatehouse.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org

On Jun 30, 2014 3:36 AM, "David Drysdale" <drysdale@google.com> wrote:
>
> Add a new O_BENEATH_ONLY flag for openat(2) which restricts the
> provided path, rejecting (with -EACCES) paths that are not beneath
> the provided dfd.  In particular, reject:
>  - paths that contain .. components
>  - paths that begin with /
>  - symlinks that have paths as above.

I like this a lot.  However, I think I'd like it even better if it
were AT_BENEATH_ONLY so that it could be added to the rest of the *at
family.

--Andy
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