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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8AA9C433EF for ; Wed, 13 Oct 2021 07:09:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C66DF61039 for ; Wed, 13 Oct 2021 07:09:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238323AbhJMHLW (ORCPT ); Wed, 13 Oct 2021 03:11:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232118AbhJMHLU (ORCPT ); Wed, 13 Oct 2021 03:11:20 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BBB45C061746 for ; Wed, 13 Oct 2021 00:09:17 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id np13so1457591pjb.4 for ; Wed, 13 Oct 2021 00:09:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=9B8532Yqv4ro9UPpSECsrKFDalIVcpozoR3xlP35mOo=; b=mOSmWjnWgLyjFNwZ0JklI8sCKMnMMWbDMjBEiqgViAMnDbbLoqtyhfRZSXhu78BZva fZi0/vUzbbm9hey6oND+v9LEaQMLMU+ZNQpseYV/sBelGJ8lZ6Uni5v40eDIb3NjnOvq Fz3mNpV5Hm0WMOjWDkkg0bltm0biFBS/mCHk4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=9B8532Yqv4ro9UPpSECsrKFDalIVcpozoR3xlP35mOo=; b=N37iuo7soK4iTNOt9BaLcWap6ozyMDXqNVKtaWnwO0fA0n1dRuOOi7N4Jst2zIpmHu s+A75MPF++0AKx9KnbdwXRW7HcN3LgUjrG1aFqs+GSAA2LfYZlY5ycsUaJpKUtzfd5fP B/gW7g9T4B8NmNohFlmYCDdYTdvhsk0UgKpuyJJkAewujrfbH7EShQNnUaonU3hJ+Tq4 R/8y3sqLgPQzcwfsHbXInuwXlcFrRTY79epqD3gJYYLSEhA+chMw0j/G+PAQvV7SoFnp 9t0wovxXY/Q0GMMMMB8FqmiEXZvuqi/z+tBIzyVf31IZ1vBoIhdaWTdMiWn6vd/B3d9U J5vw== X-Gm-Message-State: AOAM530I0HNdroXpfCAVSvfVP//WEBlhvY9rCaKLXqm1TLeIrf6hyrmu r+9nO2M6LvHnlApJn32j7Z8LIw== X-Google-Smtp-Source: ABdhPJwNfT+PN9/6KcLorXFjdNFizJJQ4LNC6e+5MQ9vFZUDGTpFiM1qVaKprUL29bSaC2DkxYGXsw== X-Received: by 2002:a17:90a:6542:: with SMTP id f2mr8159904pjs.159.1634108957279; Wed, 13 Oct 2021 00:09:17 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id p2sm4697310pja.51.2021.10.13.00.09.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Oct 2021 00:09:16 -0700 (PDT) Date: Wed, 13 Oct 2021 00:09:16 -0700 From: Kees Cook To: Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Andrew Morton , "James E.J. Bottomley" , Helge Deller , Arnd Bergmann , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v1 09/10] lkdtm: Fix lkdtm_EXEC_RODATA() Message-ID: <202110130008.EC5E957D4A@keescook> References: <7da92e59e148bd23564d63bdd8bcfaba0ba6d1f1.1633964380.git.christophe.leroy@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7da92e59e148bd23564d63bdd8bcfaba0ba6d1f1.1633964380.git.christophe.leroy@csgroup.eu> Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Mon, Oct 11, 2021 at 05:25:36PM +0200, Christophe Leroy wrote: > Behind a location, lkdtm_EXEC_RODATA() executes a real function, > not a copy of do_nothing(). > > So do it directly instead of using execute_location(). I don't understand this. Why does the next patch not fix this? -Kees > > And fix displayed addresses by dereferencing the function descriptors. > > Signed-off-by: Christophe Leroy > --- > drivers/misc/lkdtm/perms.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c > index 442d60ed25ef..da16564e1ecd 100644 > --- a/drivers/misc/lkdtm/perms.c > +++ b/drivers/misc/lkdtm/perms.c > @@ -153,7 +153,14 @@ void lkdtm_EXEC_VMALLOC(void) > > void lkdtm_EXEC_RODATA(void) > { > - execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS); > + pr_info("attempting ok execution at %px\n", > + dereference_symbol_descriptor(do_nothing)); > + do_nothing(); > + > + pr_info("attempting bad execution at %px\n", > + dereference_symbol_descriptor(lkdtm_rodata_do_nothing)); > + lkdtm_rodata_do_nothing(); > + pr_err("FAIL: func returned\n"); > } > > void lkdtm_EXEC_USERSPACE(void) > -- > 2.31.1 > -- Kees Cook