From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751962AbdJTGpR (ORCPT ); Fri, 20 Oct 2017 02:45:17 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:53082 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751792AbdJTGpP (ORCPT ); Fri, 20 Oct 2017 02:45:15 -0400 Date: Fri, 20 Oct 2017 14:45:02 +0800 From: joeyli To: David Howells Cc: linux-security-module@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, linux-efi@vger.kernel.org, matthew.garrett@nebula.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, jforbes@redhat.com Subject: Re: [PATCH 14/27] ACPI: Limit access to custom_method when the kernel is locked down Message-ID: <20171020064502.GV3285@linux-l9pv.suse> References: <150842463163.7923.11081723749106843698.stgit@warthog.procyon.org.uk> <150842473899.7923.6590815561953001126.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <150842473899.7923.6590815561953001126.stgit@warthog.procyon.org.uk> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 19, 2017 at 03:52:19PM +0100, David Howells wrote: > From: Matthew Garrett > > custom_method effectively allows arbitrary access to system memory, making > it possible for an attacker to circumvent restrictions on module loading. > Disable it if the kernel is locked down. > > Signed-off-by: Matthew Garrett > Signed-off-by: David Howells I have reviewed this patch. Please feel free to add: Reviewed-by: "Lee, Chun-Yi" Thanks! Joey Lee > cc: linux-acpi@vger.kernel.org > --- > > drivers/acpi/custom_method.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c > index c68e72414a67..b33fba70ec51 100644 > --- a/drivers/acpi/custom_method.c > +++ b/drivers/acpi/custom_method.c > @@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, > struct acpi_table_header table; > acpi_status status; > > + if (kernel_is_locked_down("ACPI custom methods")) > + return -EPERM; > + > if (!(*ppos)) { > /* parse the table header to get the table length */ > if (count <= sizeof(struct acpi_table_header)) > > -- > To unsubscribe from this list: send the line "unsubscribe linux-efi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html