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=-8.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no 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 8F0C4CA9EC9 for ; Mon, 4 Nov 2019 23:42:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DA0F214D9 for ; Mon, 4 Nov 2019 23:42:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="oGPkCL7M" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730045AbfKDXmX (ORCPT ); Mon, 4 Nov 2019 18:42:23 -0500 Received: from mail-ua1-f66.google.com ([209.85.222.66]:41278 "EHLO mail-ua1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729693AbfKDXmX (ORCPT ); Mon, 4 Nov 2019 18:42:23 -0500 Received: by mail-ua1-f66.google.com with SMTP id o9so3804127uat.8 for ; Mon, 04 Nov 2019 15:42:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=r7KXOloQM0IlfDWd2ZmUfquqt9+rdW/LWeVsYzZS5Yo=; b=oGPkCL7MQlhqPwAizXy81wfFgmEWqswSVaJ070q7QSMUHV4rPFEYIVwwPUoI9JzQsV tjGNPbiNdqm3wtOwdKjIJhkvEjEXR8IE1Pm1iGuTui1lsJ+zyZeDnmwaGc2e6IpIiC7j 9DxB+dahbSm/W3s0bm4fZ+Ya8dVCfIpGNF7eIHGT9X8eK1ysYtT0Awoo+UNrLzgXT1M8 6lCULIQcB4PBf/VReN8veBI+zOWkOCacAf5D4mMyNLo05/F1kRUX0ZUZHRqR65q2ltF0 9f1oEkjctFu+UunQvKHg6uh6X+4dlnVuWcEQ+Q7Gr/HjdzHoxvC8WHhHXsbWPLqqmzQT XpXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=r7KXOloQM0IlfDWd2ZmUfquqt9+rdW/LWeVsYzZS5Yo=; b=YIJMl3kWWD2lzt0/9Twp933TQ8eUvBGKG6mko2WjTweATl1x5YLHWNxlvQZbEXEMpb vEJ4TyYv8pQF3MQhtzwYYrVnSRXC6JzlJM6A0wFLH6gQMwz7VHTErGsNSQCv3qPj4NzR a62OYKiZShYEQGd7cFnId60qkYlknRkAiUST8rnLNnqgyGIZ7pmBFHLDH6vGh8BJTzu6 frA64NoRFk3/W1LMsuP6ousMbHv/sWxK4u2mnRza/VFqUr+lGg6nPi8sddBlXhA9YYVE IFifG7qvps1z2tUGbSgcU2sWLE1Ho39zBG8NWxd8Rq3iWHqPvfSobPrjrhZ3xqIWavXy 4MXA== X-Gm-Message-State: APjAAAW1S74UHO7fK5Vfk1LRF6VVxW0tEwtNjY2Q4eFuKC1mHOZw5dDK 3//yIBDV+kU35Lzs0K6SdDtiM9VahvyA5DIApYw/Lg== X-Google-Smtp-Source: APXvYqz8I4cRB5IWTivRJgxux0uUc15gQK8/fyRxTXKNu37vOixhqfpx8UpDAvilaBEvuvDWvryENhED0MHmtPoojeg= X-Received: by 2002:ab0:1451:: with SMTP id c17mr4197520uae.110.1572910941690; Mon, 04 Nov 2019 15:42:21 -0800 (PST) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191101221150.116536-1-samitolvanen@google.com> <20191101221150.116536-11-samitolvanen@google.com> <20191104170454.GA2024@lakrids.cambridge.arm.com> In-Reply-To: <20191104170454.GA2024@lakrids.cambridge.arm.com> From: Sami Tolvanen Date: Mon, 4 Nov 2019 15:42:09 -0800 Message-ID: Subject: Re: [PATCH v4 10/17] arm64: disable kretprobes with SCS To: Mark Rutland Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux , Kernel Hardening , linux-arm-kernel , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 4, 2019 at 9:05 AM Mark Rutland wrote: > I'm a bit confused as to why that's the case -- could you please > elaborate on how this is incompatible? > > IIUC kretrobes works by patching the function entry point with a BRK, so > that it can modify the LR _before_ it is saved to the stack. I don't see > how SCS affects that. You're correct. While this may not be optimal for reducing attack surface, I just tested this to confirm that there's no functional conflict. I'll drop this and related patches from v5. Sami