From patchwork Mon Jul 8 17:49:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Garnier X-Patchwork-Id: 11035547 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C176213B1 for ; Mon, 8 Jul 2019 17:51:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AD5AB284C3 for ; Mon, 8 Jul 2019 17:51:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9F5DB2853C; Mon, 8 Jul 2019 17:51:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id C77B6284C3 for ; Mon, 8 Jul 2019 17:51:09 +0000 (UTC) Received: (qmail 28441 invoked by uid 550); 8 Jul 2019 17:49:52 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 28377 invoked from network); 8 Jul 2019 17:49:50 -0000 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=In4rxyE8xoIq9hv+/Rl93qCG1sjI2TBb8rYoBjZpO1n+a3+hhAjWXigbDN/xEzPsUS qlV6o4KnkDo25CH/FqbHpOC0clJe+4iO3F8Mp/FYBs2j42rQjRU5C1OpjwYYE/U9pJ0A 5vOocNDssVqy3WrZ2XQXzF6UMuHdtMC1rnngv8ZZDarDwMndivyX5SYvJzr/vC7nPI7e LQJ3fe4PYCRY8e3h6cZNR8G1hQMbjO/vO2mEqsyX0xyPN+o6i1eBKuhcUR/tb/F2zm/H XAxAt7m/+sPnLLvU6f8xlnWXopd6agR1i0KM70JHX/Q9rJEEaxQGypO12LqqrQt/XPV+ m/6g== X-Gm-Message-State: APjAAAXDmPGOKJZEtAv5KH1Q3muw66/50I9WkA6QoY1w70/20OIG5ydz ec4nTLnZZoLzqgWuceRSIHn6fQGJd8k= 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) 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 X-Virus-Scanned: ClamAV using ClamSMTP 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)