Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933490Ab3CSHnb (ORCPT ); Tue, 19 Mar 2013 03:43:31 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:49777 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933075Ab3CSHn3 (ORCPT ); Tue, 19 Mar 2013 03:43:29 -0400 X-Sasl-enc: YWqM2Otrevxykj86btem2uRNOCBMrBxflV5rz2JGOQek 1363679008 Message-ID: <5148171D.10807@ladisch.de> Date: Tue, 19 Mar 2013 08:43:25 +0100 From: Clemens Ladisch User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130307 Thunderbird/17.0.4 MIME-Version: 1.0 To: Prarit Bhargava 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> In-Reply-To: <1363609488-25250-1-git-send-email-prarit@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1452 Lines: 41 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? > + default 0 This breaks backwards compatibility. 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/