Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756392Ab3CSOVy (ORCPT ); Tue, 19 Mar 2013 10:21:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:17190 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755420Ab3CSOVw (ORCPT ); Tue, 19 Mar 2013 10:21:52 -0400 Message-ID: <5148747C.9020803@redhat.com> Date: Tue, 19 Mar 2013 10:21:48 -0400 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110419 Red Hat/3.1.10-1.el6_0 Thunderbird/3.1.10 MIME-Version: 1.0 To: Clemens Ladisch CC: linux-kernel@vger.kernel.org Subject: Re: [PATCH] hpet, allow user controlled mmap for user processes References: <51444171.1080905@ladisch.de> <1363609488-25250-1-git-send-email-prarit@redhat.com> <5148171D.10807@ladisch.de> In-Reply-To: <5148171D.10807@ladisch.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1768 Lines: 58 On 03/19/2013 03:43 AM, Clemens Ladisch wrote: > Prarit Bhargava wrote: >> The CONFIG_HPET_MMAP Kconfig option exposes the memory map of the HPET >> registers to userspace. The Kconfig help points out that in some cases this >> can be a security risk as some systems may erroneously configure the map such >> that additional data is exposed to userspace. >> >> This is a problem for distributions -- some users want the MMAP functionality >> but it comes with a significant security risk. In an effort to mitigate this >> risk, and due to the low number of users of the MMAP functionality, I've >> introduced a kernel parameter, hpet_mmap_enable, that is required in order >> to actually have the HPET MMAP exposed. >> >> [v2]: Clemens suggested modifying the Kconfig help text and making the >> default setting configurable. >> >> Signed-off-by: Prarit Bhargava >> Cc: Clemens Ladisch > >> +++ b/Documentation/kernel-parameters.txt >> + hpet_mmap_enable [X86, HPET_MMAP] option to expose HPET MMAP to >> + userspace. By default this is disabled. > > This now takes a value. > >> + int "Enable HPET MMAP access by default" >> + range 0 1 > > Shouldn't this be bool? I'll fix those in v3. > >> + default 0 > > This breaks backwards compatibility. Does backwards compatibility matter for something like? I have no problem setting it to 1 but I'm more curious from a general kernel point of view. I'll change this in v3 as well. P. P. > > > Regards, > Clemens -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/