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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 1E185C169C4 for ; Wed, 6 Feb 2019 17:33:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5EDA2186A for ; Wed, 6 Feb 2019 17:33:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jxBVSrqh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730106AbfBFRdm (ORCPT ); Wed, 6 Feb 2019 12:33:42 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:45872 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727594AbfBFRdl (ORCPT ); Wed, 6 Feb 2019 12:33:41 -0500 Received: by mail-pg1-f196.google.com with SMTP id y4so3180725pgc.12; Wed, 06 Feb 2019 09:33:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=rYbgX2FNZSLFQiDq0Ih+9oGqomi8Dxzpd7WK0+FcTcQ=; b=jxBVSrqhK2+6jA9mgt1ZG2E6Yi97wIPX6W+CP4vKddME0zOC5E6Nq1muZXBqDq66Ye VVAsjSUD9dScTXpLAZBgRw1MBsrpIoTC5JQhT21UolL971aHLI6k3RCW7jONQsJbBlzP t9jtC1tCPW113d7khRQ4pUr9iK6z6+Jl2znriGGF6Tc3h8tJm7WgEkq29wzTlX5g7Mg9 7qQk6+j5bVvHFcSvP+fLT9HshRbtp0RQyolyO61o12w+C/C+MMWVvqfybCZv/UsMV/AI BKEhQZUPTuOaO1k+dtte1NfawOt3RDQ2LvtZ9jMask9lAZN5wdlfaI5HXjrthV8o5cSn 2XNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=rYbgX2FNZSLFQiDq0Ih+9oGqomi8Dxzpd7WK0+FcTcQ=; b=SYsVM7QUyhCysuvVB0yUdZK7/URF+rK5JpLhsb/9KlekIXfyzsxuwHv3hz9fYgp8qk U82G/MaSONLfa4RzSDOUNbLA0cSoEKD8prqyJ4xru0XV/QizToYDt7vrlLAyUpa3hBqn Cfm56hlQtHKGzUD/ISD5hyqb881vwb+KJ9ybygZYuNGxqryUUQxMnCt8mBq4zXKIWlW/ ZRuJ8PpCVYtNHkAf/WmOLTjYrKKACSdy+3NHvmqTxM/RTANyn3cq2/W8NMhoEupvCX9C xU7MqEt1om21qhUFbqmTL8KZrRrDKhDG7liMoRqa8V54xeBItbb8Z/YM3YUm/88dR/wP jH/g== X-Gm-Message-State: AHQUAuY7qR7qlh3FNcracmHcPRd157zULVgFShopOGUDNOejhsqUFhzb wGeP2ADcjkjRRukyTVV0PHk= X-Google-Smtp-Source: AHgI3IZO/nBxjBj7hWYe6SBT7x8lwLWKo0SvM/vK6C31+42XzDoMO/FAAmIlRnhVDYWo38sCKnYxiQ== X-Received: by 2002:a65:62da:: with SMTP id m26mr10648561pgv.278.1549474419293; Wed, 06 Feb 2019 09:33:39 -0800 (PST) Received: from [10.33.115.182] ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id a13sm436912pgw.34.2019.02.06.09.33.37 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Feb 2019 09:33:38 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\)) Subject: Re: [PATCH 08/17] x86/ftrace: set trampoline pages as executable From: Nadav Amit In-Reply-To: <20190206112213.2ec9dd5c@gandalf.local.home> Date: Wed, 6 Feb 2019 09:33:35 -0800 Cc: Rick Edgecombe , Andy Lutomirski , Ingo Molnar , LKML , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Borislav Petkov , Dave Hansen , Peter Zijlstra , Damian Tometzki , linux-integrity , LSM List , Andrew Morton , Kernel Hardening , Linux-MM , Will Deacon , Ard Biesheuvel , Kristen Carlson Accardi , deneen.t.dock@intel.com Content-Transfer-Encoding: quoted-printable Message-Id: <5DFA1E3C-A335-4C4B-A86F-904A6CF6D871@gmail.com> References: <20190117003259.23141-1-rick.p.edgecombe@intel.com> <20190117003259.23141-9-rick.p.edgecombe@intel.com> <20190206112213.2ec9dd5c@gandalf.local.home> To: Steven Rostedt X-Mailer: Apple Mail (2.3445.102.3) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Feb 6, 2019, at 8:22 AM, Steven Rostedt = wrote: >=20 > On Wed, 16 Jan 2019 16:32:50 -0800 > Rick Edgecombe wrote: >=20 >> From: Nadav Amit >>=20 >> Since alloc_module() will not set the pages as executable soon, we = need >> to do so for ftrace trampoline pages after they are allocated. >>=20 >> For the time being, we do not change ftrace to use the text_poke() >> interface. As a result, ftrace breaks still breaks W^X. >>=20 >> Cc: Steven Rostedt >> Signed-off-by: Nadav Amit >> Signed-off-by: Rick Edgecombe >> --- >> arch/x86/kernel/ftrace.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >>=20 >> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c >> index 8257a59704ae..eb4a1937e72c 100644 >> --- a/arch/x86/kernel/ftrace.c >> +++ b/arch/x86/kernel/ftrace.c >> @@ -742,6 +742,7 @@ create_trampoline(struct ftrace_ops *ops, = unsigned int *tramp_size) >> unsigned long end_offset; >> unsigned long op_offset; >> unsigned long offset; >> + unsigned long npages; >> unsigned long size; >> unsigned long retq; >> unsigned long *ptr; >> @@ -774,6 +775,7 @@ create_trampoline(struct ftrace_ops *ops, = unsigned int *tramp_size) >> return 0; >>=20 >> *tramp_size =3D size + RET_SIZE + sizeof(void *); >> + npages =3D DIV_ROUND_UP(*tramp_size, PAGE_SIZE); >>=20 >> /* Copy ftrace_caller onto the trampoline memory */ >> ret =3D probe_kernel_read(trampoline, (void *)start_offset, = size); >> @@ -818,6 +820,13 @@ create_trampoline(struct ftrace_ops *ops, = unsigned int *tramp_size) >> /* ALLOC_TRAMP flags lets us know we created it */ >> ops->flags |=3D FTRACE_OPS_FL_ALLOC_TRAMP; >>=20 >> + /* >> + * Module allocation needs to be completed by making the page >> + * executable. The page is still writable, which is a security = hazard, >> + * but anyhow ftrace breaks W^X completely. >> + */ >=20 > Perhaps we should set the page to non writable after the page is > updated? And set it to writable only when we need to update it. You remember that I sent you a patch that changed all these writes into text_poke() and you said that I should defer it until this series is = merged? > As for this patch: >=20 > Reviewed-by: Steven Rostedt (VMware) Thanks!