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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 86BD7C10F14 for ; Wed, 10 Apr 2019 17:48:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C48B2082E for ; Wed, 10 Apr 2019 17:48:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="dDcJMViz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730245AbfDJRsF (ORCPT ); Wed, 10 Apr 2019 13:48:05 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:34084 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730156AbfDJRsE (ORCPT ); Wed, 10 Apr 2019 13:48:04 -0400 Received: by mail-pf1-f193.google.com with SMTP id b3so1935780pfd.1 for ; Wed, 10 Apr 2019 10:48:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=sbutHiCZ8mGxfyY9QSUioqjtpuKW2Q5N9kWxngYGrGQ=; b=dDcJMVizqpsIxP1GaENl0R/3F7wvMJlKcWI+khcgfVdfGkqvLa3RfggN5bN1CsnMh/ kJpy17p0XXe6vbOB8d9d6eyDwmIAWBLfM7I0SXPx/pdf40lEkCKCkiWn5pYGqHv3DiXS QMVJU5qVKOrKTeQPRze2Hi8xB9JvFOyoorVDg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=sbutHiCZ8mGxfyY9QSUioqjtpuKW2Q5N9kWxngYGrGQ=; b=m/Zve18UbkyKqc1K2sGW5Fx68f6WJTV2e+oDKXwJ2OgV3fim4205IlIvvVgLubG0pp 5htQr8qd/J+CyLr8jtBeZK9e2IYgr0ebixyZFbOfoCx0j6k3TuUb1TjHFq/mkvxDh8JG Usu7AS46sH54sSB0E0fbZRtUe1BNZajbhv6YpzoreZ6bpSx1LHYkAYFXZUysTqy8rOTY QR9FogvyeA82HiY+q8Qgg7/wztqsncc4RME06wytrkvaXmmZIMYSlYnNiAUASS7tqqYN hqZGYR9pK7MMPNHAXVGW8GV1crZf8phmK9zeObeCtXB0exQ3y5wGoUmw3QsM/5jycH9s IgTg== X-Gm-Message-State: APjAAAX9eWtGh6/3yPkfT0u0GDK51PckcX62ooG0GlElb+V4EGUDro/S EPaA7uYwOKZwu/ZMdus5A2M5HZ8n8OM= X-Google-Smtp-Source: APXvYqxpsrtFwPwC2NMCBJeO4o6A92ulkAQ1biyJqNy6WYgouj9AdzvPIpyrg/tsadDPOXi+vTXCSA== X-Received: by 2002:a63:e845:: with SMTP id a5mr43320973pgk.246.1554918483038; Wed, 10 Apr 2019 10:48:03 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id y20sm32535485pfe.188.2019.04.10.10.48.01 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 10 Apr 2019 10:48:02 -0700 (PDT) Date: Wed, 10 Apr 2019 13:48:00 -0400 From: Joel Fernandes To: Kees Cook Cc: LKML , "Paul E. McKenney" , Steven Rostedt , Mathieu Desnoyers , rcu@vger.kernel.org, Kernel Hardening , Android Kernel Team , Jessica Yu Subject: Re: [PATCH 1/2] module: Prepare for addition of new ro_after_init sections Message-ID: <20190410174800.GA259061@google.com> References: <20190410011418.76408-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 10, 2019 at 09:26:44AM -0700, Kees Cook wrote: > On Tue, Apr 9, 2019 at 6:14 PM Joel Fernandes (Google) > wrote: > > > > For the purposes of hardening modules by adding sections to > > ro_after_init sections, prepare for addition of new ro_after_init > > entries which we do in future patches. Create a table to which new > > entries could be added later. This makes it less error prone and reduce > > code duplication. > > > > Cc: paulmck@linux.vnet.ibm.com > > Cc: rostedt@goodmis.org > > Cc: mathieu.desnoyers@efficios.com > > Cc: rcu@vger.kernel.org > > Cc: kernel-hardening@lists.openwall.com > > Cc: kernel-team@android.com > > Suggested-by: keescook@chromium.org > > Signed-off-by: Joel Fernandes (Google) > > > > --- > > kernel/module.c | 42 ++++++++++++++++++++++++------------------ > > 1 file changed, 24 insertions(+), 18 deletions(-) > > > > diff --git a/kernel/module.c b/kernel/module.c > > index 524da609c884..f9221381d076 100644 > > --- a/kernel/module.c > > +++ b/kernel/module.c > > @@ -3300,11 +3300,28 @@ static bool blacklisted(const char *module_name) > > } > > core_param(module_blacklist, module_blacklist, charp, 0400); > > > > +/* > > + * Mark ro_after_init section with SHF_RO_AFTER_INIT so that > > + * layout_sections() can put it in the right place. > > + * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. > > + */ > > +static char *ro_after_init_sections[] = { > > static const char * const ... Need to make sure the table and its > strings can't be changed. :) Will fix :) > > + ".data..ro_after_init", > > + > > + /* > > + * __jump_table structures are never modified, with the exception of > > + * entries that refer to code in the __init section, which are > > + * annotated as such at module load time. > > + */ > > + "__jump_table", > > + NULL > > Since this table is known at build time, you don't need a NULL > terminator, you can use ARRAY_SIZE() instead. Ok, sounds good. You are absolutely right. > > +}; > > + > > static struct module *layout_and_allocate(struct load_info *info, int flags) > > { > > struct module *mod; > > unsigned int ndx; > > - int err; > > + int err, i; > > > > err = check_modinfo(info->mod, info, flags); > > if (err) > > @@ -3319,23 +3336,12 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) > > /* We will do a special allocation for per-cpu sections later. */ > > info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; > > > > - /* > > - * Mark ro_after_init section with SHF_RO_AFTER_INIT so that > > - * layout_sections() can put it in the right place. > > - * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. > > - */ > > - ndx = find_sec(info, ".data..ro_after_init"); > > - if (ndx) > > - info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; > > - /* > > - * Mark the __jump_table section as ro_after_init as well: these data > > - * structures are never modified, with the exception of entries that > > - * refer to code in the __init section, which are annotated as such > > - * at module load time. > > - */ > > - ndx = find_sec(info, "__jump_table"); > > - if (ndx) > > - info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; > > + /* Set sh_flags for read-only after init sections */ > > + for (i = 0; ro_after_init_sections[i]; i++) { > > i.e. for (i = 0; i < ARRAY_SIZE(ro_after_init_sections); i++) Yep. > > + ndx = find_sec(info, ro_after_init_sections[i]); > > + if (ndx) > > + info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; > > + } > > > > /* Determine total sizes, and put offsets in sh_entsize. For now > > this is done generically; there doesn't appear to be any > > Otherwise, yeah, looks good to me. Thanks, if you are Ok with it, I will add your Reviewed-by tag as well. - Joel