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=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 77E1DC606BD for ; Mon, 8 Jul 2019 17:49:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D793218A6 for ; Mon, 8 Jul 2019 17:49:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="kU0hTEVJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404035AbfGHRt6 (ORCPT ); Mon, 8 Jul 2019 13:49:58 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:45134 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390638AbfGHRtj (ORCPT ); Mon, 8 Jul 2019 13:49:39 -0400 Received: by mail-pf1-f194.google.com with SMTP id r1so7932777pfq.12 for ; Mon, 08 Jul 2019 10:49:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ePdEUdrca6fFwO52Os//aVk9SOcvqdOqJdcWyryzZTw=; b=kU0hTEVJAcl6SkM40WFYbml9NRVB/VRgYvcodBevBVS7b5Dci28pvYAr2xfhi/axgn eBQEcW6Js8KEf09C6+AFw/yxAlwdgGyE2B1AsbeW+pGDw2pR18c+hPy5YlvCsK4qNBBV 8XE2uXEe8ZEhINFcEgDl/BiQWMLWv9/IddJBg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ePdEUdrca6fFwO52Os//aVk9SOcvqdOqJdcWyryzZTw=; b=jreecDq2Atl3nm5czNaX7/WTSzfQ7x8DmNekQA6p0iFjmB34dja35BvGQgUQSf66Wb rc0wlgXTSXwCHqrJg1x4tyogHCTUennm8w3Qs9Zobz1LtT/97eeqFW3hIvx67WkddCsW QyqkVJfpnKrqoltquMsp2q2KDFn4T5FiPQ8qiUDdg1TVyJqNXRSHHQ4UJqivp3ZRbw8o 6na1/hkgfWSnBWJqNbASFfNt0e2vZ/vD6Aoeq6iglPjSti40B9LUDl2viGok9BWINdfP B65EstILt0VyM7jQYfo9e47nrsNot/kuyT6MKOjFkqYmn8/nUhbsqA1gs/Q7h2oi5wz2 0D5w== X-Gm-Message-State: APjAAAUqHWUdgSoW2okXwTpAuWRK6DqTLRlnYQzs7foQAvx1rVrIXSQ/ DVBU8ALjY1fcUCSXswHfAyWF/g== X-Google-Smtp-Source: APXvYqxlefZEZZIMWA46QmINk8z9e/nAo/rW+qIWGkvdt+qwKeKFE8s8d+qOafqM7Ad1JAdHYwQagA== X-Received: by 2002:a63:231c:: with SMTP id j28mr25012871pgj.430.1562608178690; Mon, 08 Jul 2019 10:49:38 -0700 (PDT) Received: from skynet.sea.corp.google.com ([2620:0:1008:1100:c4b5:ec23:d87b:d6d3]) by smtp.gmail.com with ESMTPSA id j1sm20151686pfe.101.2019.07.08.10.49.38 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 08 Jul 2019 10:49:38 -0700 (PDT) From: Thomas Garnier To: kernel-hardening@lists.openwall.com Cc: kristen@linux.intel.com, keescook@chromium.org, Thomas Garnier , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, Juergen Gross , Boris Ostrovsky , Feng Tang , Maran Wilson , Andy Lutomirski , linux-kernel@vger.kernel.org Subject: [PATCH v8 08/11] x86/boot/64: Adapt assembly for PIE support Date: Mon, 8 Jul 2019 10:49:01 -0700 Message-Id: <20190708174913.123308-9-thgarnie@chromium.org> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog In-Reply-To: <20190708174913.123308-1-thgarnie@chromium.org> References: <20190708174913.123308-1-thgarnie@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change the assembly code to use only relative references of symbols for the kernel to be PIE compatible. Early at boot, the kernel is mapped at a temporary address while preparing the page table. To know the changes needed for the page table with KASLR, the boot code calculate the difference between the expected address of the kernel and the one chosen by KASLR. It does not work with PIE because all symbols in code are relatives. Instead of getting the future relocated virtual address, you will get the current temporary mapping. Instructions were changed to have absolute 64-bit references. Position Independent Executable (PIE) support will allow to extend the KASLR randomization range below 0xffffffff80000000. Signed-off-by: Thomas Garnier Reviewed-by: Kees Cook --- arch/x86/kernel/head_64.S | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index bcd206c8ac90..64a4f0a22b20 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -90,8 +90,10 @@ startup_64: popq %rsi /* Form the CR3 value being sure to include the CR3 modifier */ - addq $(early_top_pgt - __START_KERNEL_map), %rax + movabs $(early_top_pgt - __START_KERNEL_map), %rcx + addq %rcx, %rax jmp 1f + ENTRY(secondary_startup_64) UNWIND_HINT_EMPTY /* @@ -120,7 +122,8 @@ ENTRY(secondary_startup_64) popq %rsi /* Form the CR3 value being sure to include the CR3 modifier */ - addq $(init_top_pgt - __START_KERNEL_map), %rax + movabs $(init_top_pgt - __START_KERNEL_map), %rcx + addq %rcx, %rax 1: /* Enable PAE mode, PGE and LA57 */ @@ -138,7 +141,7 @@ ENTRY(secondary_startup_64) movq %rax, %cr3 /* Ensure I am executing from virtual addresses */ - movq $1f, %rax + movabs $1f, %rax ANNOTATE_RETPOLINE_SAFE jmp *%rax 1: @@ -235,11 +238,12 @@ ENTRY(secondary_startup_64) * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect, * address given in m16:64. */ - pushq $.Lafter_lret # put return address on stack for unwinder + movabs $.Lafter_lret, %rax + pushq %rax # put return address on stack for unwinder xorl %ebp, %ebp # clear frame pointer - movq initial_code(%rip), %rax + leaq initial_code(%rip), %rax pushq $__KERNEL_CS # set correct cs - pushq %rax # target address in negative space + pushq (%rax) # target address in negative space lretq .Lafter_lret: END(secondary_startup_64) -- 2.22.0.410.gd8fdbe21b5-goog