From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754718AbeCHSLj (ORCPT ); Thu, 8 Mar 2018 13:11:39 -0500 Received: from mx2.suse.de ([195.135.220.15]:45493 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751984AbeCHSLh (ORCPT ); Thu, 8 Mar 2018 13:11:37 -0500 Date: Thu, 8 Mar 2018 18:11:36 +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 v3 4/6] sysctl: Warn when a clamped sysctl parameter is set out of range Message-ID: <20180308181136.GE4449@wotan.suse.de> References: <1519926220-7453-1-git-send-email-longman@redhat.com> <1519926220-7453-5-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1519926220-7453-5-git-send-email-longman@redhat.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 01, 2018 at 12:43:38PM -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. > > Signed-off-by: Waiman Long > --- > include/linux/sysctl.h | 3 +++ > kernel/sysctl.c | 52 ++++++++++++++++++++++++++++++++++++++++++-------- > 2 files changed, 47 insertions(+), 8 deletions(-) > > diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h > index 448aa72..3db57af 100644 > --- a/include/linux/sysctl.h > +++ b/include/linux/sysctl.h > @@ -130,11 +130,14 @@ struct ctl_table > * @CTL_FLAGS_CLAMP_RANGE: Set to indicate that the entry should be > * flexibly clamped to min/max range in case the user provided > * an incorrect value. > + * @CTL_FLAGS_OOR_WARNED: Set to indicate that an out of range warning > + * had been issued for that entry. > * > * At most 16 different flags will be allowed. > */ > enum ctl_table_flags { > CTL_FLAGS_CLAMP_RANGE = BIT(0), > + CTL_FLAGS_OOR_WARNED = BIT(1), > }; > > struct ctl_node { > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > index af351ed..6c68e77 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -2505,6 +2505,7 @@ static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write, > * @min: pointer to minimum allowable value > * @max: pointer to maximum allowable value > * @flags: pointer to flags > + * @name: sysctl parameter name > * > * The do_proc_dointvec_minmax_conv_param structure provides the > * minimum and maximum values for doing range checking for those sysctl > @@ -2514,31 +2515,50 @@ struct do_proc_dointvec_minmax_conv_param { > int *min; > int *max; > uint16_t *flags; > + const char *name; > }; > > +/* Out of range warning message */ > +#define proc_ctl_warn(type, ...) \ > + pr_warn("Kernel parameter \"%s\" was set out of range [%" \ > + #type ", %" #type "], clamped to %" #type ".\n", __VA_ARGS__) > + Usage of pr_*() macros are best used if and when you first also define #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt Also if we can avoid adding a new define for a pr_warn wrapper even better. I'd much prefer to have a helper static void routine which gets some params and does the print than have a define. However you choose, I just don't want a #define around a simple pr_warn(). Luis