From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49258 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932408AbeCLVC4 (ORCPT ); Mon, 12 Mar 2018 17:02:56 -0400 Subject: Re: [PATCH v4 2/6] proc/sysctl: Check for invalid flags bits To: "Luis R. Rodriguez" Cc: Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Al Viro , Matthew Wilcox References: <1520885744-1546-1-git-send-email-longman@redhat.com> <1520885744-1546-3-git-send-email-longman@redhat.com> <20180312204614.GZ4449@wotan.suse.de> <2621ea58-174f-bfe9-8c34-12501bb775fa@redhat.com> <20180312205920.GD4449@wotan.suse.de> From: Waiman Long Message-ID: Date: Mon, 12 Mar 2018 17:02:55 -0400 MIME-Version: 1.0 In-Reply-To: <20180312205920.GD4449@wotan.suse.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 03/12/2018 04:59 PM, Luis R. Rodriguez wrote: > On Mon, Mar 12, 2018 at 04:54:51PM -0400, Waiman Long wrote: >> On 03/12/2018 04:46 PM, Luis R. Rodriguez wrote: >>> On Mon, Mar 12, 2018 at 04:15:40PM -0400, Waiman Long wrote: >>>> Checking code is added to check for invalid flags in the ctl_table >>>> and return error if an unknown flag is used. >>> This should be merged with the first patch otherwise there are atomic >>> points in time on the commit log history where invalid values are allowed >>> and that makes no sense. >>> >>> This can probably be expanded to verify semantics further. Details >>> below. >>>> Signed-off-by: Waiman Long >>>> --- >>>> fs/proc/proc_sysctl.c | 12 ++++++++++++ >>>> 1 file changed, 12 insertions(+) >>>> >>>> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c >>>> index 493c975..67c0c82 100644 >>>> --- a/fs/proc/proc_sysctl.c >>>> +++ b/fs/proc/proc_sysctl.c >>>> @@ -1092,6 +1092,16 @@ static int sysctl_check_table_array(const char *path, struct ctl_table *table) >>>> return err; >>>> } >>>> >>>> +static int sysctl_check_flags(const char *path, struct ctl_table *table) >>>> +{ >>>> + int err = 0; >>>> + >>>> + if (table->flags & ~CTL_TABLE_FLAGS_ALL) >>>> + err = sysctl_err(path, table, "invalid flags"); >>> What if a range for the upper limit is set but not the lower limit and >>> the user goes over the lower limit? >>> >>> How about the inverse? >>> >>> Do we need both ranges set? >>> >>> Luis >> This check is just to make sure that no invalid flag bit is set. Range >> clamping is just one of flag bits, though this is the only one currently >> supported. In fact, it is allowed that the minimum or maximum can be >> left unspecified. In this case, no minimum or maximum checking will be >> done. So I don't see anything related to range checking should be put here. > What if minimum is greater than maximum? > > Luis Yes, you are right. That is a valid check. I am going to add that in the next patch. Cheers, Longman