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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 0CFB2C433DB for ; Wed, 3 Feb 2021 09:55:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBFDA64F61 for ; Wed, 3 Feb 2021 09:55:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233557AbhBCJzO (ORCPT ); Wed, 3 Feb 2021 04:55:14 -0500 Received: from mx2.suse.de ([195.135.220.15]:39380 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233105AbhBCJzK (ORCPT ); Wed, 3 Feb 2021 04:55:10 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1612346064; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=W5joaEFyKEmxsNgxXWQzVbFGdC1MUWlZwutGUmy8/jo=; b=Czj/9S9jYfh4hGtMrHwynewDHibaO+tpS/h6ERXNMaoz1jYV/uhHFpHE2yDZz6KyMATppF NkhjXUqOa0e6u386/k5tHN7+AMLcNBxeH5vlpkQgWDz64rfh2bsevcp4CwgxzQVR5Xib8y Be/JT6VIXttyduSzKWy+gH/Dntbt7lY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 203F8AF4C; Wed, 3 Feb 2021 09:54:24 +0000 (UTC) Date: Wed, 3 Feb 2021 10:54:23 +0100 From: Petr Mladek To: Timur Tabi Cc: Steven Rostedt , Sergey Senozhatsky , linux-kernel@vger.kernel.org, vbabka@suse.cz, linux-mm@kvack.org, willy@infradead.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, roman.fietze@magna.com, keescook@chromium.org, john.ogness@linutronix.de, akinobu.mita@gmail.com Subject: Re: [PATCH][RESEND] lib/vsprintf: make-printk-non-secret printks all addresses as unhashed Message-ID: References: <20210202213633.755469-1-timur@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210202213633.755469-1-timur@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2021-02-02 15:36:33, Timur Tabi wrote: > If the make-printk-non-secret command-line parameter is set, then > printk("%p") will print addresses as unhashed. This is useful for > debugging purposes. > > A large warning message is displayed if this option is enabled, > because unhashed addresses, while useful for debugging, exposes > kernel addresses which can be a security risk. > > Signed-off-by: Timur Tabi > --- > lib/vsprintf.c | 34 ++++++++++++++++++++++++++++++++-- > 1 file changed, 32 insertions(+), 2 deletions(-) Please, add also entry into Documentation/admin-guide/kernel-parameters.txt. If we agree that the parameter is acceptable then let's make it properly. > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index 3b53c73580c5..b9f87084afb0 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -2090,6 +2090,30 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode, > return widen_string(buf, buf - buf_start, end, spec); > } > > +/* Disable pointer hashing if requested */ > +static bool debug_never_hash_pointers __ro_after_init; > + > +static int __init debug_never_hash_pointers_enable(char *str) > +{ > + debug_never_hash_pointers = true; > + pr_warn("**********************************************************\n"); > + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n"); > + pr_warn("** **\n"); > + pr_warn("** All pointers that are printed to the console will **\n"); > + pr_warn("** be printed as unhashed. **\n"); > + pr_warn("** **\n"); > + pr_warn("** Kernel memory addresses are exposed, which may **\n"); > + pr_warn("** compromise security on your system. **\n"); > + pr_warn("** **\n"); > + pr_warn("** If you see this message and you are not debugging **\n"); > + pr_warn("** the kernel, report this immediately to your vendor! **\n"); It is a boot parameter. So it should be "system administrtor" instead of vendor. Otherwise, it looks good to me. Best Regards, Petr