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=-3.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 09C9DC2BB1D for ; Tue, 7 Apr 2020 11:13:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD334206F7 for ; Tue, 7 Apr 2020 11:13:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="0j+dqzCw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728562AbgDGLNN (ORCPT ); Tue, 7 Apr 2020 07:13:13 -0400 Received: from merlin.infradead.org ([205.233.59.134]:42482 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728495AbgDGLNJ (ORCPT ); Tue, 7 Apr 2020 07:13:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=jKJXZpzzDrrjmwLNRHLcBZgkJJqiHAXwqSXGUdiOBYo=; b=0j+dqzCwYKeCySGxRekkKqS18I Ci4hvKzYPKjEPtpr0yDYoOQfLkgInKK5Am6VbHyjnWE+6tpIXnkM++yfH69CFy+71eKW0wOLC15EM mGUfAbvj14OTkzee+xcIuGyRFMTgOF1sOzUhvQTCqHlgi6mh3Nmqd1Mkv1N2wiijcwvjjIfEsPut9 meT/gty9dwvqxnuuGuK4n8ZnF2tQvNjMvv04Q8Z595cDgt0rF3ckoUIpnvHZEvJcT8vT3VgJNc8ew 4oVAMlOUcslek5ZWl43n7ciUgQp1chuZYE6BI0o52KWcC1c1GVM5X+ZmFJ5EkMGTD34EdVgEPW9BD 55DFhRVg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jLm9m-0007DP-Oh; Tue, 07 Apr 2020 11:12:39 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 4E45D30604B; Tue, 7 Apr 2020 13:12:36 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 25ACF29C96F21; Tue, 7 Apr 2020 13:12:36 +0200 (CEST) Message-Id: <20200407111007.429362016@infradead.org> User-Agent: quilt/0.65 Date: Tue, 07 Apr 2020 13:02:40 +0200 From: Peter Zijlstra To: tglx@linutronix.de, linux-kernel@vger.kernel.org Cc: hch@infradead.org, sean.j.christopherson@intel.com, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, kenny@panix.com, peterz@infradead.org, jeyu@kernel.org, rasmus.villemoes@prevas.dk, pbonzini@redhat.com, fenghua.yu@intel.com, xiaoyao.li@intel.com, nadav.amit@gmail.com, thellstrom@vmware.com, tony.luck@intel.com, rostedt@goodmis.org, gregkh@linuxfoundation.org, jannh@google.com, keescook@chromium.org, David.Laight@aculab.com, dcovelli@vmware.com, mhiramat@kernel.org Subject: [PATCH 4/4] x86,module: Detect CRn and DRn manipulation References: <20200407110236.930134290@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since we now have infrastructure to analyze module text, disallow modules that write to CRn and DRn registers. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/module.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -266,6 +266,22 @@ static bool insn_is_vmx(struct insn *ins return false; } +static bool insn_is_mov_CRn(struct insn *insn) +{ + if (insn->opcode.bytes[0] == 0x0f && insn->opcode.bytes[1] == 0x22) + return true; + + return false; +} + +static bool insn_is_mov_DRn(struct insn *insn) +{ + if (insn->opcode.bytes[0] == 0x0f && insn->opcode.bytes[1] == 0x23) + return true; + + return false; +} + static int decode_module(struct module *mod, void *text, void *text_end, bool sld_safe) { bool allow_vmx = sld_safe || !split_lock_enabled(); @@ -285,6 +301,11 @@ static int decode_module(struct module * return -ENOEXEC; } + if (insn_is_mov_CRn(&insn) || insn_is_mov_DRn(&insn)) { + pr_err("Module writes to CRn or DRn, please use the proper accessors: %s\n", mod->name); + return -ENOEXEC; + } + text += insn.length; }