From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751934AbeB0UuC (ORCPT ); Tue, 27 Feb 2018 15:50:02 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47480 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751721AbeB0UuB (ORCPT ); Tue, 27 Feb 2018 15:50:01 -0500 From: Waiman Long To: "Luis R. Rodriguez" , Kees Cook Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Al Viro , Waiman Long Subject: [PATCH v2 0/5] ipc: Clamp *mni to the real IPCMNI limit Date: Tue, 27 Feb 2018 15:49:46 -0500 Message-Id: <1519764591-27456-1-git-send-email-longman@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v1->v2: - Add kdoc comments to the do_proc_do{u}intvec_minmax_conv_param structures. - Add a new flags field to the ctl_table structure for specifying whether range clamping should be activated instead of adding new sysctl parameter handlers. - Clamp the semmni value embedded in the multi-values sem parameter. v1 patch: https://lkml.org/lkml/2018/2/19/453 The sysctl parameters msgmni, shmmni and semmni have an inherent limit of IPC_MNI (32k). However, users may not be aware of that because they can write a value much higher than that without getting any error or notification. Reading the parameters back will show the newly written values which are not real. Enforcing the limit by failing sysctl parameter write, however, can break existing user applications. To address this delemma, a new flags field is introduced into the ctl_table. The value CTL_FLAGS_CLAMP_RANGE can be added to any ctl_table entries to enable a looser range clamping without returning any error. For example, .flags = CTL_FLAGS_CLAMP_RANGE, This flags value are now used for the range checking of shmmni, msgmni and semmni without breaking existing applications. If any out of range value is written to those sysctl parameters, the following warning will be printed instead. Kernel parameter "shmmni" was set out of range [0, 32768], clamped to 32768. Reading the values back will show 32768 instead of some fake values. Waiman Long (5): sysctl: Add kdoc comments to do_proc_do{u}intvec_minmax_conv_param sysctl: Add flags to support min/max range clamping sysctl: Warn when a clamped sysctl parameter is set out of range ipc: Clamp msgmni and shmmni to the real IPCMNI limit ipc: Clamp semmni to the real IPCMNI limit include/linux/sysctl.h | 7 ++++ ipc/ipc_sysctl.c | 29 +++++++++++-- ipc/sem.c | 33 +++++++++++++++ ipc/util.h | 4 ++ kernel/sysctl.c | 111 +++++++++++++++++++++++++++++++++++++++++++++---- 5 files changed, 173 insertions(+), 11 deletions(-) -- 1.8.3.1