From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-4.6 required=5.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,T_DKIM_INVALID, T_RP_MATCHES_RCVD autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 825A77DE76 for ; Tue, 27 Mar 2018 17:01:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752446AbeC0RBP (ORCPT ); Tue, 27 Mar 2018 13:01:15 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:44308 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751890AbeC0Q5s (ORCPT ); Tue, 27 Mar 2018 12:57:48 -0400 Received: by mail-wr0-f194.google.com with SMTP id u46so23109396wrc.11 for ; Tue, 27 Mar 2018 09:57:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=2unNROHG+8feIGotHXszhTuGPmpRY6bXBkim4UFPTaQ=; b=SXjhznolWo1hvxBRtHpKTOT8IY9XixA/kKc+IfwHbe8/lVgq1y2AV4kboGXl4kHBxk nyoqKsfwJUXwGk7PAMzPpGAO6gXLGQaIui2hzXXzgRXwJ/2ve6BuovPgdsTP76XDK+B6 ROO512Wu1uPsfVIS5QzZzMKq+ZFMbEhFW2S4MkFpLDoPvWcsNnBau5SPXgRjV3RRLQc7 Z7zMEp0ijm3LVZcWKI3kn9YqJbPNmQaKv390RnL7+NgPIDNwvdDA7HVAXVV0l21PLoNP 05xXhc/k3Wu4XrlSPtaZ4mlXnQwjalDCe/8Y/drJ2a1rwdPdu5+SOCo27z9I4Tub3/5v /feg== 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:mime-version :content-transfer-encoding; bh=2unNROHG+8feIGotHXszhTuGPmpRY6bXBkim4UFPTaQ=; b=T9/4f1xtcpJyYKHhoIEuMQ75+TSomwAdZiIcB19y9gTqnglJLUGzd/dhYqJlcxKD4j cy9fDrxC+fMDiiYbyCJmhN7hrf9s1R0NG64mcRhU3DnsSg/kOEr704V02rP+Ifti0xhk oRQO+iQfrnrsi8VNo47C93uvOFkIWDPlp5ZUeo5ZA3k53DbcCoKIlVuY7LlphRm0GIUd BB6YrfgZZNY3OoYqPfkEMeVqoA/ipA4E42MU4/qsd8VdXY7MvNqg7WsZ7VWbbG13KXwx Yse54Z5wSFyTzVPJi2mGA6JGm2Lt92RHbUQumJPLOQC4Mit1s7uAO5xQ0UbWI/0ezTyo UXNg== X-Gm-Message-State: AElRT7FqhBntzwWxni9YvMH/HFeKd1qaf60tJaIo3QDl2sTx81hzxfl1 qv0VbgXg2cmGOnckRxw1HkrFsQ== X-Google-Smtp-Source: AIpwx4+SqilrH2teukLBq3OM04gQK/o6scnPl5VTqxM3lBxwZh4twkUP46cBr9jr5WdaxdB1/7zZTw== X-Received: by 10.223.183.75 with SMTP id n11mr135507wre.22.1522169866448; Tue, 27 Mar 2018 09:57:46 -0700 (PDT) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:84be:a42a:826d:c530]) by smtp.gmail.com with ESMTPSA id 93sm1622992wrh.46.2018.03.27.09.57.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Mar 2018 09:57:45 -0700 (PDT) From: Andrey Konovalov To: Catalin Marinas , Will Deacon , Jonathan Corbet , Mark Rutland , Robin Murphy , Al Viro , Andrey Konovalov , James Morse , Kees Cook , Bart Van Assche , Kate Stewart , Greg Kroah-Hartman , Thomas Gleixner , Philippe Ombredanne , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Dan Williams , "Aneesh Kumar K . V" , Zi Yan , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan Subject: [RFC PATCH v2 0/6] arm64: untag user pointers passed to the kernel Date: Tue, 27 Mar 2018 18:57:36 +0200 Message-Id: X-Mailer: git-send-email 2.17.0.rc0.231.g781580f067-goog MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Hi! arm64 has a feature called Top Byte Ignore, which allows to embed pointer tags into the top byte of each pointer. Userspace programs (such as HWASan, a memory debugging tool [1]) might use this feature and pass tagged user pointers to the kernel through syscalls or other interfaces. This patch makes a few of the kernel interfaces accept tagged user pointers. The kernel is already able to handle user faults with tagged pointers and has the untagged_addr macro, which this patchset reuses. We're not trying to cover all possible ways the kernel accepts user pointers in one patchset, so this one should be considered as a start. Thanks! [1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html Changes in RFC v2: - Added "#ifndef untagged_addr..." fallback in linux/uaccess.h instead of defining it for each arch individually. - Updated Documentation/arm64/tagged-pointers.txt. - Dropped “mm, arm64: untag user addresses in memory syscalls”. - Rebased onto 3eb2ce82 (4.16-rc7). Andrey Konovalov (6): arm64: add type casts to untagged_addr macro uaccess: add untagged_addr definition for other arches arm64: untag user addresses in copy_from_user and others mm, arm64: untag user addresses in mm/gup.c lib, arm64: untag addrs passed to strncpy_from_user and strnlen_user arm64: update Documentation/arm64/tagged-pointers.txt Documentation/arm64/tagged-pointers.txt | 5 +++-- arch/arm64/include/asm/uaccess.h | 9 +++++++-- include/linux/uaccess.h | 4 ++++ lib/strncpy_from_user.c | 2 ++ lib/strnlen_user.c | 2 ++ mm/gup.c | 12 ++++++++++++ 6 files changed, 30 insertions(+), 4 deletions(-) -- 2.17.0.rc0.231.g781580f067-goog -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html