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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 F0884C11D3D for ; Thu, 27 Feb 2020 16:03:00 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 4E4C12469C for ; Thu, 27 Feb 2020 16:03:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Qsxn4Hk1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E4C12469C 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-17972-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 12193 invoked by uid 550); 27 Feb 2020 16:02:52 -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: Received: (qmail 12173 invoked from network); 27 Feb 2020 16:02:51 -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=9WYvJWXMZ+rcEfofeSJpHlDz/l6UP/pgxaBPI0bVL+I=; b=Qsxn4Hk1uahykr+QWbXHItx2AejCBY1osUAbIGB78L1sCo7B6Il4l6DND0mh7bGD0P VEphLT6LKCT7GeIYw8JhWS4IdRBHN9OjLD6OTWcRutDRZdUgwuaqV/hwpz3zxaBidUgO ggRjZ0IGbj3DcO3j9UNLtGA9Bagw1dMPj4wqU= 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=9WYvJWXMZ+rcEfofeSJpHlDz/l6UP/pgxaBPI0bVL+I=; b=jQo3f2Ld8+IhVOAzHVOjYQ5Tkq0Vhc1OfKSxC+N6biPNvx5tmPza1GQHPmJLPUo2jE ZNqdNldmjSG/7edIxp5dL6jNEGjg8cK5c30pH8Hlt2MQSXUpaaIeTJX0Nh3QnOrncDeC nQ56OlaEW7fbiNW0eGm3Tz+GOWuik9IIO6NzcBtGyjpWxCPO2lpEsJaQPGL7ISZODVcV Mf8GzDm/FM0vDvnpno2nqL0f/tnkj5zLzS+2NYiNMEaAhO4iqTCz6zeJRQbD6kIG1lay oBPEcUbMcTZfRVTHhEkCEvLMgNS0KWP1adZJjsEZZrRoZh5GR/hEodAMOAnY6X9eTwIT sKwA== X-Gm-Message-State: APjAAAWv9uA04vUR+V+1cs12jlXEOLC3xW2nSKr6I4c+wLSBL6nGpbDS AxRPnzHOx0h+HAaG1AgsMzkaXQ== X-Google-Smtp-Source: APXvYqwuoISNzfA3MpWinuXHZq6onkj6FotCRgoAwXWcPcaWOvayXN9eZRYUoFiSP4YFJQB9lCtKzA== X-Received: by 2002:a17:902:265:: with SMTP id 92mr402833plc.292.1582819359541; Thu, 27 Feb 2020 08:02:39 -0800 (PST) Date: Thu, 27 Feb 2020 08:02:37 -0800 From: Kees Cook To: Baoquan He Cc: Kristen Carlson Accardi , dyoung@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, arjan@linux.intel.com, rick.p.edgecombe@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, kexec@lists.infradead.org Subject: Re: [RFC PATCH 09/11] kallsyms: hide layout and expose seed Message-ID: <202002270802.1CA8B32AC@keescook> References: <20200205223950.1212394-1-kristen@linux.intel.com> <20200205223950.1212394-10-kristen@linux.intel.com> <202002060428.08B14F1@keescook> <20200227024253.GA5707@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200227024253.GA5707@MiWiFi-R3L-srv> On Thu, Feb 27, 2020 at 10:42:53AM +0800, Baoquan He wrote: > On 02/06/20 at 09:51am, Kristen Carlson Accardi wrote: > > On Thu, 2020-02-06 at 04:32 -0800, Kees Cook wrote: > > > > In the past, making kallsyms entirely unreadable seemed to break > > > weird > > > stuff in userspace. How about having an alternative view that just > > > contains a alphanumeric sort of the symbol names (and they will > > > continue > > > to have zeroed addresses for unprivileged users)? > > > > > > Or perhaps we wait to hear about this causing a problem, and deal > > > with > > > it then? :) > > > > > > > Yeah - I don't know what people want here. Clearly, we can't leave > > kallsyms the way it is. Removing it entirely is a pretty fast way to > > figure out how people use it though :). > > Kexec-tools and makedumpfile are the users of /proc/kallsyms currently. > We use kallsyms to get page_offset_base and _stext. AIUI, those run as root so they'd be able to consume the uncensored output. -- Kees Cook