From patchwork Sat Feb 17 06:25:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13561258 Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 639371CAA4 for ; Sat, 17 Feb 2024 06:25:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708151150; cv=none; b=JpfCXXTZpxu91DImWSIzC0+Z0Iab1pkUhgx0ORT0PS6TURDkTBedMqH4a2ddLZ/dYVfm5lpE0u+SI2giKUJa2k4HA87bb6pmxorjAZKrVAQBw3uffQUsaNs8ZswzYDvr9pRKrbusGwzhSIKxMyiEAueWfsQp44W0UEVzb3NQ1Wc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708151150; c=relaxed/simple; bh=J8yZ3FuS1LWrR5jVIrwba2SyB7GFZoxGQ5Gq7wzczYA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=qkVGFTMzFaY6F36V+6QmmXnjsyJSXDrhRaDWfGKEKKDk96vt7SBWtoTjRm4Xv5bRLGDwSKDmcc9CFJcr2fVBDhwBm62a0Xy6rUbB5jSQxUjNJVcrCYI68SuAbnqDCuEhN4YwuwKkCSZBCiqhw5AWG7zrgPDjjhRQ9SBHiz9R3kA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=XrMFYxl3; arc=none smtp.client-ip=209.85.210.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="XrMFYxl3" Received: by mail-pf1-f179.google.com with SMTP id d2e1a72fcca58-6e08dd0fa0bso2340958b3a.1 for ; Fri, 16 Feb 2024 22:25:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1708151147; x=1708755947; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=PfIR0fBKHcHTu35XI9I/l5YesMfUJfSS9sUu5LMaD84=; b=XrMFYxl3HbmiYA5MznqQAnAqEKe3T3Dm0cR6E0hq86QLu74Lvhhb7IOERfDTKi3C2Y VocL+m200E/RatXK7Usd3mwvwPIs8cSWxwewolMMJ14LnrNvpomSxHwsI+eyf59ipSwY 6i409nuhdmpRiaDccspRbhRV6R9lXtZKQLQKk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708151147; x=1708755947; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=PfIR0fBKHcHTu35XI9I/l5YesMfUJfSS9sUu5LMaD84=; b=H6N8lML5IA67AvBCr3dt/CMnJno4GftB1ig0LgqrrctPOzsMWKCq3CaOu1y7vePZkg KXk75N9UPYeIns35+FqHa/O/tr2FyegJ2rllIyVi6vahnXVauM3C3PWLKRisIj4wXLbD vLer+LMWPEzOwpkGYZ3qFow/YWc0hcFBIejpz6uawLNjl7Ma98JIEqp1lrJktL1lh1lz 0RyB70rhtZwCXmHeArW2v5DgZVMJwtQ+qldggM9sO0y9/vE0z20bHIAv72HRouYGh+E/ CfimzC/0F1nbs0ziSH3x3Z+Ivmr+kikZz7z8NyHxVjTsjC5P2AglYia9qZzB49AJFAMl vTsw== X-Forwarded-Encrypted: i=1; AJvYcCVX3z9czZbnL1yCS05SlXVW+GQiNOMJyfMwPnOM2HBkCeQg8TWZrSgnPwz2ZvctH5Huzf0Jg/PURQmbwXjSVFrvB5iyoumugIoXR3pQm72V X-Gm-Message-State: AOJu0Yy2EKGqmcXBWpmlgCFGlkfdfotFBztkyKHUw9glRmKQePBJUmCB juUcGHa6NWaFYHQJ5k9Welyl+dmGpXn0yp+9egOdRHjazEzqOAuhGYTIyHry7w== X-Google-Smtp-Source: AGHT+IEN7kra6nhd0C/U//cqra0sN9TAy99jtLP7gl6N1oR+rsshp77a8Yk2AxFV0aGXX6usEqGwwA== X-Received: by 2002:a05:6a00:2292:b0:6e0:8c11:9878 with SMTP id f18-20020a056a00229200b006e08c119878mr13296297pfe.7.1708151147635; Fri, 16 Feb 2024 22:25:47 -0800 (PST) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id p9-20020aa79e89000000b006e35c1aceeesm233949pfq.197.2024.02.16.22.25.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Feb 2024 22:25:46 -0800 (PST) From: Kees Cook To: Jiri Kosina Cc: Kees Cook , y0un9n132@gmail.com, Geert Uytterhoeven , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Peter Zijlstra , Qi Zheng , Alexandre Ghiti , x86@kernel.org, Al Viro , Christian Brauner , Jan Kara , Eric Biederman , Christophe Leroy , Josh Poimboeuf , "Kirill A. Shutemov" , Rick Edgecombe , Brian Gerst , Bjorn Helgaas , Tony Battersby , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org Subject: [PATCH 1/2] x86: Increase brk randomness entropy on x86_64 Date: Fri, 16 Feb 2024 22:25:43 -0800 Message-Id: <20240217062545.1631668-1-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240217062035.work.493-kees@kernel.org> References: <20240217062035.work.493-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1595; i=keescook@chromium.org; h=from:subject; bh=J8yZ3FuS1LWrR5jVIrwba2SyB7GFZoxGQ5Gq7wzczYA=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBl0FFofylSSc0zctidXuws91GIZAfUD3EvfMTgD C7ILFWiQEWJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZdBRaAAKCRCJcvTf3G3A JuvKD/0YST+WQlVawQvhCb3pQXdND3wneO4rAAc1MIaPKKYFGzOMCeSQYBifV0JEeFHph1WsrQC n4+hCw/MTLwSm24DnSu1EEevAaPtL2voVeq16UMZrkG/yapEWn3+250s3daI8qSEHpaTs+lqmrY 20PeyS18a3NDnzD6VRtlc/Ud4NM4lTrD59tsR9Zypsk8QkTOW11SzkDOU36Vewr5lvz9WlASgCb uX115bQ6YNYuZQkpWi0z4MlnmeNcdOuQnupP0FwTKJDVMHrN+vvFac+rR68LNoQtHQMqb0yZKXr iaQfIX0RbdI1t7Ns/XMSdQQfLgvkslY3PnQ7KanuL/2iVQSA+qYKaUHT1q5rU9VB+w3Dck4Dmye Mw0zNvdQB8Y4A4EnGY6HYyO6ucLRSQtEfIuXbYYszYSq6wZmHI2F8gQrXTQN6dKrHavZBh6DOSY Ep4Xtnl5207P/j3tkJ2WlgxPesAECiupJebylL9V96dhr12EkUmNs83ixnDjhgIhd/q1C66ZLuD gOP5XrfxOIcEw0QQFj8sFRcjpHdAnouwZruQruo4ED1IAeSMX2ThvD6Di09uNBuIX4r27aUDkF4 PMMxi3r0jO2Iy/OhTCP2lOG3dtuz7BSAH3EaHzmxqr7QyGazjc6Mux/rumcsyyFjQTLaXMsCYg5 3MpCUeeX8WL+hxg== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 In commit c1d171a00294 ("x86: randomize brk"), arch_randomize_brk() was defined to use a 32MB range (13 bits of entropy), but was never increased when moving to 64-bit. The default arch_randomize_brk() uses 32MB for 32-bit tasks, and 1GB (18 bits of entropy) for 64-bit tasks. Update x86_64 to match the entropy used by arm64 and other 64-bit architectures. Reported-by: y0un9n132@gmail.com Closes: https://lore.kernel.org/linux-hardening/CA+2EKTVLvc8hDZc+2Yhwmus=dzOUG5E4gV7ayCbu0MPJTZzWkw@mail.gmail.com/ Signed-off-by: Kees Cook --- Cc: Jiri Kosina Cc: Geert Uytterhoeven Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Peter Zijlstra Cc: Qi Zheng Cc: Alexandre Ghiti Cc: x86@kernel.org --- arch/x86/kernel/process.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index ab49ade31b0d..45a9d496fe2a 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -1030,7 +1030,10 @@ unsigned long arch_align_stack(unsigned long sp) unsigned long arch_randomize_brk(struct mm_struct *mm) { - return randomize_page(mm->brk, 0x02000000); + if (mmap_is_ia32()) + return randomize_page(mm->brk, SZ_32M); + + return randomize_page(mm->brk, SZ_1G); } /*