From patchwork Wed Feb 13 22:41:36 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Igor Stoppa X-Patchwork-Id: 10811045 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 3C1371575 for ; Wed, 13 Feb 2019 22:43:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2CA2C2E3C5 for ; Wed, 13 Feb 2019 22:43:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 20CBC2E5C4; Wed, 13 Feb 2019 22:43:09 +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 3E8792E3C5 for ; Wed, 13 Feb 2019 22:43:08 +0000 (UTC) Received: (qmail 1201 invoked by uid 550); 13 Feb 2019 22:42:32 -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 1130 invoked from network); 13 Feb 2019 22:42:31 -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=ULj+THdUZNWpGpW+KM463NwXvBXWj/ziG70TMcSMLTrDNndnvryzpWfDrOvQsAMlCy WTqTZgCLccOezugr9gkA0PatiHtL3QYcaVFHXdeDbHSfxmJnJ51XdhRFY2aUkbBgSTXx tipXJL3Dy6QXxBL3zVgPtPq1ANzRsbGAy0+TigONDh7YYLPUk1GGivftv1kHhyKzxr+p oyQSUS3fuoSUEsbw4S9g37thArexER13LrUX+3yjAYx3TqSBBIUg7eNLJ1ItQYMqyIY6 X6RFb4SUKd44Df0ltx5kfaGf/joUGmooAumJyOgvpEFh9LCb/dYw4CmmbPPAwy2VlDMo 0ODQ== 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=J+DFlfY9p8tkoAQVKArcj2fZXrtzDTzVm+KYZ6Vrn4hFnR3BkPcc7owfrmZP+cqaUn mbkKIKRJh5NsL3x0Pcd+8bIUiBkVhuT+AKFNaUCRYliMKeGg09kOLhSxtpY8WA16oN1G 2fBjISgLemfq0gWjjSpMiCTO3GIN9inbq+hNpQzgugQ5xQvX7lzOeNUio+5a9caV/eXs T4CsKikmRTHZn25+qIHZrlsfVMpbHsV18doKPDmB/wEcfH241CvCGqpeQ3PDpxShMw0h 8Jz8R3b2aKxmNUKsvN60n6zOeMl4eBco3c/4Ishn7WhquNlGuhNGtDF2FuYuNpkPkjVo ++Iw== X-Gm-Message-State: AHQUAuZ7gg6Qh62Nmok2R/4XARa0+7RQYv2s4nvbrOezODraBHAaBrJw IYV8Y5smnVVIQXR0O73P72g= X-Google-Smtp-Source: AHgI3IYegSvkdqTo7yAMNGYKpTH4etQCyxzK1x4a5zwRFav668/1dvUCN1p823cxzwulFtPYhon3xA== X-Received: by 2002:adf:9004:: with SMTP id h4mr302936wrh.49.1550097740125; Wed, 13 Feb 2019 14:42:20 -0800 (PST) From: Igor Stoppa X-Google-Original-From: Igor Stoppa To: Cc: Igor Stoppa , Andy Lutomirski , Nadav Amit , Matthew Wilcox , Peter Zijlstra , Kees Cook , Dave Hansen , Mimi Zohar , Thiago Jung Bauermann , Ahmed Soliman , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v5 07/12] __wr_after_init: Documentation: self-protection Date: Thu, 14 Feb 2019 00:41:36 +0200 Message-Id: X-Mailer: git-send-email 2.19.1 In-Reply-To: References: 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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~