From patchwork Fri Dec 21 18:14:17 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Igor Stoppa X-Patchwork-Id: 10740843 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 00FB76C5 for ; Fri, 21 Dec 2018 18:15:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E915528426 for ; Fri, 21 Dec 2018 18:15:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DCF99284AA; Fri, 21 Dec 2018 18:15:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.0 required=2.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id C830328622 for ; Fri, 21 Dec 2018 18:15:48 +0000 (UTC) Received: (qmail 1147 invoked by uid 550); 21 Dec 2018 18:15:08 -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: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 1068 invoked from network); 21 Dec 2018 18:15:07 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references:reply-to :mime-version:content-transfer-encoding; bh=y4zotDQYnZoXB9lfg1fC2W7czb+qE54ZRjKDYZQbGrM=; b=SvsaISUsENLTRerxTlrw5WngUCL6xcuf+y6j/r5ybSpTEfxaevKrsab709fKKhBFHj bDwmZRFgmlGlLH6FjZIZscR0mARSzL5Yc1Hymyod01ulZ++YoZYQqgmNdt5hGgCy/c1w dOBT1TON7MOsOs6Xw7MVbfxdS7EHIQYmGSXAmKQBDdENjV/u+AOBJ2y2A59gz4QamBCP UTifq3MQpLnaFdW5Xk4MLjGbO5nBEo9pGRwBG+W6PIBX76n7iZh9k2R9oNkzAxmSHaKA Z19GApJN2rFbLKVpY9/VsZ+zfN78gSapfg+d5LN8SNYSOESPzDlqQaFJ+a0L0WMvu1B/ svYw== 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:reply-to:mime-version:content-transfer-encoding; bh=y4zotDQYnZoXB9lfg1fC2W7czb+qE54ZRjKDYZQbGrM=; b=D+6sGn/o/wdnoBirSoIA4C8d4LK1B48BAdR68RUAvUXFhgiOLY6HVjvwTPVE4972dN 2kSpMVFgRlJWub6h7R8bU86uaBXLuieSI3+pdn1F0ze6fltDOpgSa1iR83yqsEjHORDC OeRt2twq92m8rF7r/qGnT/RzKBokO1cGE/wVHX5kVPwHKT7R04qsQdXVX1ji58IKi/tV 7A0i+F8VCT7r3bv5+skbapYzPkrceaih6abvWGTEoQc5e16oYCvx0fnfObNCQdiie4M8 tbNM831zIsISEsuHOCvpBy94wcY2cxr7x+W6l2rduYlWyQQNPPFtxiLmtcaM26990x7d N7bw== X-Gm-Message-State: AA+aEWZcMu0g2TANb+HH5pRQyW+j2uDswfUEF4SsLAaWb+j2MYDcauah P5m8OrXhMinoUwMdEnzwi5U= X-Google-Smtp-Source: AFSGD/UUw4QOTr1Fz5pqLC5tPgrFCIm78stVTJm1s66btznV4xeiArrlcZYeL5woLgX/8UrqetsuTw== X-Received: by 2002:a19:a60c:: with SMTP id p12mr2115400lfe.63.1545416096496; Fri, 21 Dec 2018 10:14:56 -0800 (PST) From: Igor Stoppa X-Google-Original-From: Igor Stoppa To: Andy Lutomirski , Matthew Wilcox , Peter Zijlstra , Dave Hansen , Mimi Zohar , Thiago Jung Bauermann Cc: igor.stoppa@huawei.com, Nadav Amit , Kees Cook , Ahmed Soliman , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 06/12] __wr_after_init: Documentation: self-protection Date: Fri, 21 Dec 2018 20:14:17 +0200 Message-Id: <20181221181423.20455-7-igor.stoppa@huawei.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181221181423.20455-1-igor.stoppa@huawei.com> References: <20181221181423.20455-1-igor.stoppa@huawei.com> MIME-Version: 1.0 X-Virus-Scanned: ClamAV using ClamSMTP Update the self-protection documentation, to mention also the use of the __wr_after_init attribute. Signed-off-by: Igor Stoppa CC: Andy Lutomirski CC: Nadav Amit CC: Matthew Wilcox CC: Peter Zijlstra CC: Kees Cook CC: Dave Hansen CC: Mimi Zohar CC: Thiago Jung Bauermann CC: Ahmed Soliman CC: linux-integrity@vger.kernel.org CC: kernel-hardening@lists.openwall.com CC: linux-mm@kvack.org CC: linux-kernel@vger.kernel.org --- Documentation/security/self-protection.rst | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/Documentation/security/self-protection.rst b/Documentation/security/self-protection.rst index f584fb74b4ff..df2614bc25b9 100644 --- a/Documentation/security/self-protection.rst +++ b/Documentation/security/self-protection.rst @@ -84,12 +84,14 @@ For variables that are initialized once at ``__init`` time, these can be marked with the (new and under development) ``__ro_after_init`` attribute. -What remains are variables that are updated rarely (e.g. GDT). These -will need another infrastructure (similar to the temporary exceptions -made to kernel code mentioned above) that allow them to spend the rest -of their lifetime read-only. (For example, when being updated, only the -CPU thread performing the update would be given uninterruptible write -access to the memory.) +Others, which are statically allocated, but still need to be updated +rarely, can be marked with the ``__wr_after_init`` attribute. + +The update mechanism must avoid exposing the data to rogue alterations +during the update. For example, only the CPU thread performing the update +would be given uninterruptible write access to the memory. + +Currently there is no protection available for data allocated dynamically. Segregation of kernel memory from userspace memory ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~