From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 20 Feb 2018 23:55:17 +0000 From: "Luis R. Rodriguez" To: Andrew Morton Cc: Waiman Long , "Luis R. Rodriguez" , Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Al Viro Subject: Re: [PATCH 2/3] sysctl: Warn when a clamped sysctl parameter is set out of range Message-ID: <20180220235517.GE1686@wotan.suse.de> References: <1519059231-2456-1-git-send-email-longman@redhat.com> <1519059231-2456-3-git-send-email-longman@redhat.com> <20180220151705.8b4519f105db8f5c119015f0@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180220151705.8b4519f105db8f5c119015f0@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: On Tue, Feb 20, 2018 at 03:17:05PM -0800, Andrew Morton wrote: > On Mon, 19 Feb 2018 11:53:50 -0500 Waiman Long wrote: > > > Even with clamped sysctl parameters, it is still not that straight > > forward to figure out the exact range of those parameters. One may > > try to write extreme parameter values to see if they get clamped. > > To make it easier, a warning with the expected range will now be > > printed in the kernel ring buffer when a clamped sysctl parameter > > receives an out of range value. > > This assumes that do_proc_dointvec_minmax_conv() and > do_proc_douintvec_minmax_conv() are only ever called by privileged > userspace. Because we mustn't give unprivileged applications a way to > spam the kernel logs. > > That's presumably true in the case of the caller you just added, but I > don't see what we can do to guarantee this in the future, so perhaps we > should add some permission check to the pr_warn()? Beyond what we do with sysctl_perm() on proc_sys_call_handler()? Luis