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 3E9F9C43331 for ; Tue, 24 Mar 2020 20:32:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 17CC22074D for ; Tue, 24 Mar 2020 20:32:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="S9Srk3vt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728227AbgCXUcr (ORCPT ); Tue, 24 Mar 2020 16:32:47 -0400 Received: from mail-pj1-f65.google.com ([209.85.216.65]:53661 "EHLO mail-pj1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728159AbgCXUco (ORCPT ); Tue, 24 Mar 2020 16:32:44 -0400 Received: by mail-pj1-f65.google.com with SMTP id l36so42390pjb.3 for ; Tue, 24 Mar 2020 13:32:43 -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=c3b1sjWFJGWk+HhbHvBn4evu301M7fqA/kMQ4pyC4tI=; b=S9Srk3vtm/u5AWxb5Lq0VLBe/+/+CUvcc/nWuriifzbcDxo3ZwBkLe8Zpl+BamGg/O HO1v1zWZwiU7plLhdxR37s1Jaqc0uJSA8G7tsY4VxqWCO/G2fiHTxNvERagnEIgId99M jOOdb0wJUrZaXGZR5SVzv7rR8cyPHnbBh6gDc= 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=c3b1sjWFJGWk+HhbHvBn4evu301M7fqA/kMQ4pyC4tI=; b=p98dysPsoiLCWvINyGzqOXX0Qewt2H4rzTD7lkZ2VGDLBZctOE/UXPr28q2Yx7U+0W 0xaamoA3mn6w8EEqI9A83oKfZqfodnnT3p8gWclCQUFWeSzEMvs+CspGjQE00lq7gl33 q77ASfPM3IdmStItrHjPYPWVemxltqLhTGNTMmfn2q+twfdfFTIGxfmBaYqTavUJssD3 ek1WHJMtfBLH71fjjD62hu+iJ5ozb5CPJf0+cGJe81TIHZsfdRs3LciBCx+RjoGKMx2w DSUPmuHX8BOQzD0jqn0rNq2EPHWuEpxHSL0F2PHJ9p9lTYMREmLD8/Ik7TzB3LNvv7l5 tr9g== X-Gm-Message-State: ANhLgQ1tWBlbsVnkyUJl8aM7SLaeuumrnIsz9q8/BIx730iKPQPM3Bio rYQeHeae6APmmDcRXWAL1y8emA== X-Google-Smtp-Source: ADFU+vtXBHEgdg26RkMBmCkSMYW4AGLyko9MzjPWEETXma0en8jpa6fm5D16S9175yT7TTEUnSU+xQ== X-Received: by 2002:a17:90a:1911:: with SMTP id 17mr205762pjg.65.1585081963230; Tue, 24 Mar 2020 13:32:43 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id v26sm3813241pfn.51.2020.03.24.13.32.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2020 13:32:41 -0700 (PDT) From: Kees Cook To: Thomas Gleixner Cc: Kees Cook , Elena Reshetova , x86@kernel.org, Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Ard Biesheuvel , Jann Horn , "Perla, Enrico" , kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 5/5] arm64: entry: Enable random_kstack_offset support Date: Tue, 24 Mar 2020 13:32:31 -0700 Message-Id: <20200324203231.64324-6-keescook@chromium.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200324203231.64324-1-keescook@chromium.org> References: <20200324203231.64324-1-keescook@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 Allow for a randomized stack offset on a per-syscall basis, with roughly 5 bits of entropy. Signed-off-by: Kees Cook --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/syscall.c | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 0b30e884e088..4d5aa4959f72 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -127,6 +127,7 @@ config ARM64 select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT select HAVE_ARCH_PREL32_RELOCATIONS + select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_STACKLEAK select HAVE_ARCH_THREAD_STRUCT_WHITELIST diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index a12c0c88d345..238dbd753b44 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include @@ -42,6 +43,8 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, { long ret; + add_random_kstack_offset(); + if (scno < sc_nr) { syscall_fn_t syscall_fn; syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)]; @@ -51,6 +54,13 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, } regs->regs[0] = ret; + + /* + * Since the compiler chooses a 4 bit alignment for the stack, + * let's save one additional bit (9 total), which gets us up + * near 5 bits of entropy. + */ + choose_random_kstack_offset(get_random_int() & 0x1FF); } static inline bool has_syscall_work(unsigned long flags) -- 2.20.1