From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:48620 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932302AbeCLU7W (ORCPT ); Mon, 12 Mar 2018 16:59:22 -0400 Date: Mon, 12 Mar 2018 20:59:20 +0000 From: "Luis R. Rodriguez" To: Waiman Long Cc: "Luis R. Rodriguez" , Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Al Viro , Matthew Wilcox Subject: Re: [PATCH v4 2/6] proc/sysctl: Check for invalid flags bits Message-ID: <20180312205920.GD4449@wotan.suse.de> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2621ea58-174f-bfe9-8c34-12501bb775fa@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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