From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F181C2D0EC for ; Fri, 10 Apr 2020 21:33:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2FD7220801 for ; Fri, 10 Apr 2020 21:33:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="lfCSC+Vf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2FD7220801 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D83E98E007F; Fri, 10 Apr 2020 17:33:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D0C218E0067; Fri, 10 Apr 2020 17:33:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C72D58E007F; Fri, 10 Apr 2020 17:33:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0093.hostedemail.com [216.40.44.93]) by kanga.kvack.org (Postfix) with ESMTP id B05C28E0067 for ; Fri, 10 Apr 2020 17:33:52 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 680D3A75D for ; Fri, 10 Apr 2020 21:33:52 +0000 (UTC) X-FDA: 76693247904.30.dust21_3ee32f814fb50 X-HE-Tag: dust21_3ee32f814fb50 X-Filterd-Recvd-Size: 3946 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Fri, 10 Apr 2020 21:33:52 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E979F2145D; Fri, 10 Apr 2020 21:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586554431; bh=cC5+55+3yY1F2aB/+pv+cBqehv5R68X1Y7lsm/oPntM=; h=Date:From:To:Subject:In-Reply-To:From; b=lfCSC+VfFC3e9IifYkO5nBTrIF7hdXbHfK5zDl+eGtj/7DMNPubHtuMUdFYvjK7iW Vpzyf4iJRmjdJGczuJo8k89JuQ6CQpXIGzlSL7EKu/TU6GBK18vUQDoXi7FBq8Agim c86YMoTcNZ7DkuMq2zyY8U43wHFMpof6qjli/U4M= Date: Fri, 10 Apr 2020 14:33:50 -0700 From: Andrew Morton To: akpm@linux-foundation.org, ast@kernel.org, ebiggers@google.com, gregkh@linuxfoundation.org, jeffv@google.com, jeyu@kernel.org, keescook@chromium.org, linux-mm@kvack.org, mcgrof@kernel.org, mm-commits@vger.kernel.org, neilb@suse.com, torvalds@linux-foundation.org Subject: [patch 28/35] docs: admin-guide: document the kernel.modprobe sysctl Message-ID: <20200410213350.o21mcrRmh%akpm@linux-foundation.org> In-Reply-To: <20200410143047.bf34a933ce1affdc042c7c80@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Eric Biggers Subject: docs: admin-guide: document the kernel.modprobe sysctl Document the kernel.modprobe sysctl in the same place that all the other kernel.* sysctls are documented. Make sure to mention how to use this sysctl to completely disable module autoloading, and how this sysctl relates to CONFIG_STATIC_USERMODEHELPER. [ebiggers@google.com: v5] Link: http://lkml.kernel.org/r/20200318230515.171692-4-ebiggers@kernel.org Link: http://lkml.kernel.org/r/20200312202552.241885-4-ebiggers@kernel.org Signed-off-by: Eric Biggers Cc: Alexei Starovoitov Cc: Greg Kroah-Hartman Cc: Jeff Vander Stoep Cc: Jessica Yu Cc: Kees Cook Cc: Luis Chamberlain Cc: NeilBrown Signed-off-by: Andrew Morton --- Documentation/admin-guide/sysctl/kernel.rst | 21 ++++++++++++++++++ 1 file changed, 21 insertions(+) --- a/Documentation/admin-guide/sysctl/kernel.rst~docs-admin-guide-document-the-kernelmodprobe-sysctl +++ a/Documentation/admin-guide/sysctl/kernel.rst @@ -446,6 +446,27 @@ Notes: successful IPC object allocation. If an IPC object allocation syscall fails, it is undefined if the value remains unmodified or is reset to -1. +modprobe: +========= + +The path to the usermode helper for autoloading kernel modules, by +default "/sbin/modprobe". This binary is executed when the kernel +requests a module. For example, if userspace passes an unknown +filesystem type to mount(), then the kernel will automatically request +the corresponding filesystem module by executing this usermode helper. +This usermode helper should insert the needed module into the kernel. + +This sysctl only affects module autoloading. It has no effect on the +ability to explicitly insert modules. + +If this sysctl is set to the empty string, then module autoloading is +completely disabled. The kernel will not try to execute a usermode +helper at all, nor will it call the kernel_module_request LSM hook. + +If CONFIG_STATIC_USERMODEHELPER=y is set in the kernel configuration, +then the configured static usermode helper overrides this sysctl, +except that the empty string is still accepted to completely disable +module autoloading as described above. nmi_watchdog ============ _