From patchwork Wed Dec 19 21:33:32 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Igor Stoppa X-Patchwork-Id: 10738207 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 3D9236C5 for ; Wed, 19 Dec 2018 21:35:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2F7DA286B3 for ; Wed, 19 Dec 2018 21:35:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 23B20286B4; Wed, 19 Dec 2018 21:35:23 +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 38B41286B2 for ; Wed, 19 Dec 2018 21:35:22 +0000 (UTC) Received: (qmail 32067 invoked by uid 550); 19 Dec 2018 21:34:27 -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 31981 invoked from network); 19 Dec 2018 21:34:26 -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=xeUBKKu9pM2Fl/EWnsAPb2mBNLFsikzJ4KNY/hC/k1s=; b=TZIKF4B0i3koI0BW8axIrrGf4qCRSgVc8vuBMQJuNZ1qpAqlmGEW+bOBxwCcDK/JY3 mNOXn/Lytz0LlgdZK6s3JlI7atnuH7qez7sfQofkmzbIV2f2ZxskOsfp9NEhU5NaQTvN tFggyM8mgzKvz7s8hU9qqgBsaUM8BAmUcWFYR5zWO8a3RW+FvppFPc9fZecShjwJLJh/ lBOqekityzb82UV0NrQDkyhgmPQox8nu6C1HKMReNtzcl/z9UGLkONLrC6fFakRwXStK q/7/hXtBDqCHpIXqfHQ2ugAPMEwgUpSvY+la3Uaoflk84Jo7xJduNGkOWP+FAq0r1yMl V6EQ== 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=xeUBKKu9pM2Fl/EWnsAPb2mBNLFsikzJ4KNY/hC/k1s=; b=PXvq3NDhE05yKGL9AiKIzGqgYoNIWKPynsvRSYOhkF5Wua8ijwRCr2AzYRS/WYW7+B 34Lok5ZEe8H91dNL8PVEnBLxNCGFoLGmPPWer6sg+3g1xk0GwyT4MQcfxJgSh2IT8mMD a9LUfe7aVw9A0q9eidYjQUPC7+EYzVu0JCB6CgF+tKqwJ9vvVoVdm6ZL+Q4R2zJJowp+ 73HX2+VniANrvyTGIS9mq4haJfTBUAAqmGEYYptafDGk7pLdxE169+rOgJfGvUzaPmLy Tez/q54hksfZduQ9PmYzn+0gDipyDcM0UC6QkbsLeAAXpcLGR6qtjUWuwEjlWY5HvPvI Yvpg== X-Gm-Message-State: AA+aEWbIWRxGr7MPE5TCpeSE/7xawePHtPXXXkcQ4OwgG+qv09uIxKYq 9nmSiPfdYmbGYoDNqnVcmVM= X-Google-Smtp-Source: AFSGD/VdVCH5iML0R9nPvIbiMPCBw0CGtT0CPJuGwuUVLfPeSRuvFLi8jSpphGe6vqzW2o8lG9K3Jw== X-Received: by 2002:a2e:890b:: with SMTP id d11-v6mr4048231lji.113.1545255255391; Wed, 19 Dec 2018 13:34:15 -0800 (PST) From: Igor Stoppa X-Google-Original-From: Igor Stoppa To: Andy Lutomirski , Matthew Wilcox , Peter Zijlstra , Dave Hansen , Mimi Zohar Cc: igor.stoppa@huawei.com, Nadav Amit , Kees Cook , 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: Wed, 19 Dec 2018 23:33:32 +0200 Message-Id: <20181219213338.26619-7-igor.stoppa@huawei.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181219213338.26619-1-igor.stoppa@huawei.com> References: <20181219213338.26619-1-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: 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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~