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=-5.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 092D2C432C3 for ; Sat, 30 Nov 2019 16:54:29 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 5047D2082E for ; Sat, 30 Nov 2019 16:54:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="F/Kzqsus" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5047D2082E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17452-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 32370 invoked by uid 550); 30 Nov 2019 16:54:22 -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: Received: (qmail 32333 invoked from network); 30 Nov 2019 16:54:21 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=S16QwN1PJCMUwwyc17ejUqn/u5LVGvSs9+4bN3omUNc=; b=F/KzqsusGPe7Zn0GUrXYjNAodrpEb9VoVg6jUn9pg7QHUSes9ytznoUiSAGY3Yin4+ h9y27cgGOhuaRnO8J+iMoPKyPPiurN2hlKgyzr0qhf2Txv15ZH1PNE5nfvpPqrkhtUbw d+Fr4tU0rkGeKr+Q/zTzoed5fpSVko4UTrkVY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=S16QwN1PJCMUwwyc17ejUqn/u5LVGvSs9+4bN3omUNc=; b=nKUEnJ1E6rRs7WmVyyEn/YT7P1DZLCrvdiDGSwyToITQA/ghbximxmqp7/mGq9sskP bbe9TxrB6ZMh/6MOg+ELyPwNzJ1cUjaWIoFxHX7j261vvXaGi49177Xa5gOGOiIw0NoS f3urIEnsDOvYjqIcHAixCXpomo2CfyQmbtneuwtjs7tVnHJGgTLpF7jEZ8x9A/xAMugM R2uL+SfWD4KKx39hzYP2xKaxSNSkDkGL/2FWYi4uipPY6OhgqLEZFps0YbJmCYnlyH3X bz5HtXfzL9jBVY9OdDxdDod3VhHouZhLh7ovEdFOwy4JiW6RyCVFkJ+NM2VWei3NdsQC zBbA== X-Gm-Message-State: APjAAAVkqNUG/5mB8PFBOHZMAoSJjQjmXHyB6vN+/yePvJtkBQt9YHM4 zzfgaOrdPuOf3DHeTWG2Uu0h2A== X-Google-Smtp-Source: APXvYqw+/5iJg0WtA+4N3AeqRbX/HSrtVfbM6eVzp09WQVwdr6Lsmy0wnDLoENPMHu+zvrkZBGzAUQ== X-Received: by 2002:a17:90a:30a4:: with SMTP id h33mr25192180pjb.50.1575132849541; Sat, 30 Nov 2019 08:54:09 -0800 (PST) Date: Sat, 30 Nov 2019 08:54:07 -0800 From: Kees Cook To: Mark Rutland Cc: Kassad , kernel-hardening@lists.openwall.com Subject: Re: Contributing to KSPP newbie Message-ID: <201911300853.4F17BA5C@keescook> References: <20191129112825.GA27873@lakrids.cambridge.arm.com> <201911300846.E8606B5B2@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201911300846.E8606B5B2@keescook> On Sat, Nov 30, 2019 at 08:48:23AM -0800, Kees Cook wrote: > On Fri, Nov 29, 2019 at 11:29:13AM +0000, Mark Rutland wrote: > > On Thu, Nov 28, 2019 at 11:39:11PM -0500, Kassad wrote: > > > Hey Kees, > > > > > > I'm 3rd university student interested in learning more about the linux kernel. > > > I'm came across this subsystem, since it aligns with my interest in security. > > > Do you think as a newbie this task https://github.com/KSPP/linux/issues/11 will > > > be a good starting point? > > > > I think this specific task (Disable arm32 kuser helpers) has already > > been done, and the ticket is stale. > > Oh, thank you! I entirely missed both of these commits. I've added > notes to the bug and closed it. > > > > > On arm CONFIG_KUSER_HELPERS can be disabled on kernels that don't need > > to run on HW prior to ARMv6. See commit: > > > > f6f91b0d9fd971c6 ("ARM: allow kuser helpers to be removed from the vector page") > > > > On arm64, CONFIG_KUSER_HELPERS can be disabled on any kernel. See > > commit: > > > > 1b3cf2c2a3f42b ("arm64: compat: Add KUSER_HELPERS config option") > > (Typo: a1b3cf2c2a3f42b) Typo typo: af1b3cf2c2a3f42bbb680812ff1bbd715ac8af69 > > -Kees > > > > > Thanks, > > Mark. > > -- > Kees Cook -- Kees Cook