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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 81520C433E2 for ; Mon, 31 Aug 2020 12:48:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 683192068E for ; Mon, 31 Aug 2020 12:48:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727944AbgHaMsX (ORCPT ); Mon, 31 Aug 2020 08:48:23 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:53512 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726167AbgHaMsS (ORCPT ); Mon, 31 Aug 2020 08:48:18 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id B55BBE54C02C1B2B22FA for ; Mon, 31 Aug 2020 20:48:14 +0800 (CST) Received: from [127.0.0.1] (10.174.178.16) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.487.0; Mon, 31 Aug 2020 20:48:06 +0800 To: CC: , , "Linux Kernel Mailing List" From: Xiongfeng Wang Subject: [Question] About SECCOMP issue for ILP32 Message-ID: <30b491ad-a7e1-f7b5-26b8-2cfffc81a080@huawei.com> Date: Mon, 31 Aug 2020 20:48:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.16] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Yury, We were testing the ILP32 feature and came accross a problem. Very apperaciate it if you could give us some help ! We compile the LTP testsuite with '-mabi=ilp32' and run it on a machine with kernel and glibc applied with ILP32 patches. But we failed on one testcase, prctl04. It print the following error info. 'prctl04.c:199: FAIL: SECCOMP_MODE_STRICT doesn't permit read(2) write(2) and _exit(2)' The testcase is like below, syscall 'prctl' followed by a syscall 'write'. prctl(PR_SET_SECCOMP, SECCOMP_MODE_STRICT); SAFE_WRITE(1, fd, "a", 1); When we execute syscall 'write', we receive a SIGKILL. It's not as expected. We track the kernel and found out it is because we failed the syscall_whitelist check in '__secure_computing_strict'. Because flag 'TIF_32BIT_AARCH64' is set, we falls into the 'in_compat_syscall()' branch. We compare the parameter 'this_syscall' with return value of 'get_compat_model_syscalls()' The syscall number of '__NR_write' for ilp32 application is 64, but it is 4 for 'model_syscalls_32' returned from 'get_compat_model_syscalls()' So '__secure_computing_strict' retuned with 'do_exit(SIGKILL)'. We have a modification like below, but I am not sure if it correct or not. --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -618,7 +618,7 @@ static void __secure_computing_strict(int this_syscall) { const int *syscall_whitelist = mode1_syscalls; #ifdef CONFIG_COMPAT - if (in_compat_syscall()) + if (is_a32_compat_task()) syscall_whitelist = get_compat_mode1_syscalls(); #endif do { Thanks, Xiongfeng