From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753425AbbIROOX (ORCPT <rfc822;w@1wt.eu>);
	Fri, 18 Sep 2015 10:14:23 -0400
Received: from mx1.redhat.com ([209.132.183.28]:38135 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751823AbbIROOW (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Fri, 18 Sep 2015 10:14:22 -0400
From: Paul Moore <pmoore@redhat.com>
To: Paul Osmialowski <p.osmialowsk@samsung.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Daniel Mack <daniel@zonque.org>,
        David Herrmann <dh.herrmann@googlemail.com>,
        Djalal Harouni <tixxdz@opendz.org>, linux-kernel@vger.kernel.org,
        Lukasz Pawelczyk <l.pawelczyk@samsung.com>
Subject: Re: [RFC] kdbus: use LSM hooks to restrict ability to send file descriptors
Date: Fri, 18 Sep 2015 10:14:20 -0400
Message-ID: <6251998.tInjJR3Jq3@sifl>
Organization: Red Hat
User-Agent: KMail/4.14.10 (Linux/4.1.5-gentoo; KDE/4.14.12; x86_64; ; )
In-Reply-To: <1442582823-7368-1-git-send-email-p.osmialowsk@samsung.com>
References: <1442582823-7368-1-git-send-email-p.osmialowsk@samsung.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Friday, September 18, 2015 03:27:03 PM Paul Osmialowski wrote:
> The goal of this patch is to reproduce on kdbus the same behavior
> that is expressed by Unix Domain Sockets when it comes to restricting
> ability to pass opened file descriptors.
> 
> Signed-off-by: Paul Osmialowski <p.osmialowsk@samsung.com>
> ---
>  ipc/kdbus/message.c | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)

Hi Paul,

I've been reworking my original kdbus LSM/SELinux hooks in order to simplify 
things and make them a bit more consistent with the binder and other IPC-esque 
hooks, I'm hoping to post a RFC for them soon.

A few comments below ... 

> diff --git a/ipc/kdbus/message.c b/ipc/kdbus/message.c
> index ae565cd..b083431 100644
> --- a/ipc/kdbus/message.c
> +++ b/ipc/kdbus/message.c
> @@ -24,6 +24,7 @@
>  #include <linux/sizes.h>
>  #include <linux/slab.h>
>  #include <linux/uaccess.h>
> +#include <linux/security.h>
>  #include <net/sock.h>
> 
>  #include "bus.h"
> @@ -150,13 +151,19 @@ int kdbus_gaps_install(struct kdbus_gaps *gaps, struct
> kdbus_pool_slice *slice, for (i = 0; i < gaps->n_fds; ++i) {
>  			int fd;
> 
> -			fd = get_unused_fd_flags(O_CLOEXEC);
> -			if (fd < 0)
> +			if (gaps->fd_files[i] &&
> +				    security_file_receive(gaps->fd_files[i])) {
>  				incomplete_fds = true;
> +				fds[n_fds++] = -1;
> +			} else {
> +				fd = get_unused_fd_flags(O_CLOEXEC);
> +				if (fd < 0)
> +					incomplete_fds = true;

My patch is a little different (no fd_files[i] validity check, diff if 
structure, etc.) but the basic idea is the same.

> -			WARN_ON(!gaps->fd_files[i]);
> +				WARN_ON(!gaps->fd_files[i]);

You probably want to move this before the LSM hook.

> -			fds[n_fds++] = fd < 0 ? -1 : fd;
> +				fds[n_fds++] = fd < 0 ? -1 : fd;
> +			}
>  		}
> 
>  		/*
> @@ -178,6 +185,13 @@ int kdbus_gaps_install(struct kdbus_gaps *gaps, struct
> kdbus_pool_slice *slice, for (i = 0; i < gaps->n_memfds; ++i) {
>  		int memfd;
> 
> +		if (gaps->memfd_files[i] &&
> +			    security_file_receive(gaps->memfd_files[i])) {
> +			incomplete_fds = true;
> +			fds[n_fds++] = -1;
> +			continue;
> +		}

Similar to above, including the WARN_ON() movement.

>  		memfd = get_unused_fd_flags(O_CLOEXEC);
>  		if (memfd < 0) {
>  			incomplete_fds = true;

-- 
paul moore
security @ redhat