From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751486AbaEFRcB (ORCPT ); Tue, 6 May 2014 13:32:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34168 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750915AbaEFRcA (ORCPT ); Tue, 6 May 2014 13:32:00 -0400 Date: Tue, 6 May 2014 19:31:36 +0200 From: Oleg Nesterov To: Kirill Tkhai Cc: linux-kernel@vger.kernel.org, Andrew Morton , Ingo Molnar , Rusty Russell , tkhai@yandex.ru Subject: Re: [PATCH] kmod: Pass usermodehelper "-b" to use blacklist commands Message-ID: <20140506173136.GA1535@redhat.com> References: <1399363388.3718.59.camel@tkhai> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1399363388.3718.59.camel@tkhai> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/06, Kirill Tkhai wrote: > > User may want to prohibit autoloading of some modules, > which happens when someone in kernel calls request_module(). > > For comparison, udev considers blacklist even if corresponding > hardware presents in the system. In-kernel request_module() > functionality is rather similar to udev's, so user may want > to disallow it too. Personally, I am always nervous (perhaps too much) when it comes to the user-visible changes like this. And if a user/distro wants "-b" it can create a simple script which just execs /sbin/modprobe with "-b" and overwrite /proc/sys/kernel/modprobe. OTOH. What if /proc/sys/kernel/modprobe points to a binary which is not /sbin/modprobe and doesn't expect "-b" ? This can break things. I am not really arguing, but someone should ack this change ;) As for correctness: Reviewed-by: Oleg Nesterov > Signed-off-by: Kirill Tkhai > --- > kernel/kmod.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/kernel/kmod.c b/kernel/kmod.c > index 0ac67a5..68a4ca4 100644 > --- a/kernel/kmod.c > +++ b/kernel/kmod.c > @@ -71,7 +71,7 @@ char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; > > static void free_modprobe_argv(struct subprocess_info *info) > { > - kfree(info->argv[3]); /* check call_modprobe() */ > + kfree(info->argv[4]); /* check call_modprobe() */ > kfree(info->argv); > } > > @@ -85,7 +85,7 @@ static int call_modprobe(char *module_name, int wait) > NULL > }; > > - char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); > + char **argv = kmalloc(sizeof(char *[6]), GFP_KERNEL); > if (!argv) > goto out; > > @@ -95,9 +95,10 @@ static int call_modprobe(char *module_name, int wait) > > argv[0] = modprobe_path; > argv[1] = "-q"; > - argv[2] = "--"; > - argv[3] = module_name; /* check free_modprobe_argv() */ > - argv[4] = NULL; > + argv[2] = "-b"; > + argv[3] = "--"; > + argv[4] = module_name; /* check free_modprobe_argv() */ > + argv[5] = NULL; > > info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL, > NULL, free_modprobe_argv, NULL); > >