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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 DF48EC388F7 for ; Thu, 5 Nov 2020 23:32:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7652E20759 for ; Thu, 5 Nov 2020 23:32:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="OvTqSmKe"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="RxgZeOOA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732181AbgKEXcA (ORCPT ); Thu, 5 Nov 2020 18:32:00 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:27476 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726801AbgKEXcA (ORCPT ); Thu, 5 Nov 2020 18:32:00 -0500 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0A5NU8Wl009926; Thu, 5 Nov 2020 15:31:41 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : content-id : content-transfer-encoding : mime-version; s=facebook; bh=ugVAzyJCqI/sOxs9O4+p+LQxiIm+RG8kcv27g8c6m7A=; b=OvTqSmKefv19Kv9RYTemPkLNd2t4aUjd3d3xVBttWJanbbb3SO7gF4yxLPNl5V8uo4dd fZuDXKNBsiNOHLglOZ8a0WMToT2J4elciMACFsOtBq9cAwCzw24mWYsxV3sT+EG6+St1 V5me3ya14qjDFkMPqkvShbM2sZnhwEsLEus= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 34kf5cd5td-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Thu, 05 Nov 2020 15:31:41 -0800 Received: from NAM02-CY1-obe.outbound.protection.outlook.com (100.104.31.183) by o365-in.thefacebook.com (100.104.36.103) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Thu, 5 Nov 2020 15:31:40 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ZymxPNXyAINMxzK8FzprJwEA3LZP1u5Wyn2tXtumS1mbHTyJWxyMgv/BKk53IcxY6i9OoRiTxvJPo5ZeAx70ANI1ZlDbTBPdvGxcSWbHWw578EFWY3+iqI1m3HwkYEdB4BiKwy/w/xghH3d2JwkqhtZ2Zb+RLn2veZP2MacSqcsaD6aCC6Fu1zuZwttNTre97NqLXQ+LtZrrKNhIaFJS4oxDFgHUytZgi3yBVGFmxtm0TzOimgWxq4jkG0fBCqlPgA0xDoz7ttvHInA5iAe5rZpgEoRBGXZIxutsJ8O/R7adICcb+N7xxMxYTNFdjiOGMnWksi6TRYKcpga2GtYuLw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=ugVAzyJCqI/sOxs9O4+p+LQxiIm+RG8kcv27g8c6m7A=; b=CKJQjNQ1GzQ0XdMS5jOzh1Gnqyr/AK7YBQueTFKX0WxSfH0snbbHJoeLDALjdKlC9PWzDh03PdD6PbbBwiIbV3Ln3dEPjPyeWFnqDwHnxFnN8V9GwbpozPZYXGAl0bkS56DOZShbQ5ONeny0DkCQHpfsl07Y5ODQfEplVdAMuNpswZppPuunRKnE/QFF+AwZ8/pe27ser+GrQ3ntahJ91uXcOle0gokRzOHFMG//EUsXaBBEMuPWjWzDJ/a98PwozfrJNzEFWtESLZnDN6VSlHVj+6uToAYXdI86fKf5ryiT03udqP+U2E6OVQIs+xI7M0b1hLB5oKmRGl0zb8JHpA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector2-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=ugVAzyJCqI/sOxs9O4+p+LQxiIm+RG8kcv27g8c6m7A=; b=RxgZeOOAeJvoQyWg4tUr+PRGOB+xvIC64J2bhTkaPjP8EGCoJgLiv0Qz+jO7HCiwL5zB3irIzpDq8eBZpkS1p9sCDuZ5prPnGDxywBOkjrGlW5/W6EoLRL2G1slE/ESh5m1EDx8+jdRd3hFpn8DC37A/vSMlOUQy7uWZZHEg2vY= Received: from BYAPR15MB2999.namprd15.prod.outlook.com (2603:10b6:a03:fa::12) by BYAPR15MB2695.namprd15.prod.outlook.com (2603:10b6:a03:150::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.29; Thu, 5 Nov 2020 23:31:38 +0000 Received: from BYAPR15MB2999.namprd15.prod.outlook.com ([fe80::7d77:205b:bbc4:4c70]) by BYAPR15MB2999.namprd15.prod.outlook.com ([fe80::7d77:205b:bbc4:4c70%6]) with mapi id 15.20.3499.030; Thu, 5 Nov 2020 23:31:38 +0000 From: Song Liu To: Daniel Xu CC: Andrii Nakryiko , bpf , open list , Alexei Starovoitov , Daniel Borkmann , Kernel Team Subject: Re: [PATCH bpf v2 2/2] selftest/bpf: Test bpf_probe_read_user_str() strips trailing bytes after NUL Thread-Topic: [PATCH bpf v2 2/2] selftest/bpf: Test bpf_probe_read_user_str() strips trailing bytes after NUL Thread-Index: AQHWsxsKExRyW1CBMkWOL7EY14SiVKm6ECwAgAAesgCAAAKHgA== Date: Thu, 5 Nov 2020 23:31:38 +0000 Message-ID: <32285B9E-976A-4357-8C97-6A394926BDFE@fb.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3608.120.23.2.4) authentication-results: dxuuu.xyz; dkim=none (message not signed) header.d=none;dxuuu.xyz; dmarc=none action=none header.from=fb.com; x-originating-ip: [2620:10d:c090:400::5:ca49] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 0a8600ca-ae60-42bd-9a9c-08d881e2f156 x-ms-traffictypediagnostic: BYAPR15MB2695: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-fb-source: Internal x-ms-oob-tlc-oobclassifiers: OLM:5236; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: rbpztSLItffFPwNbfKskw9b5MJRM4E/dVeLOh9dUoJR/m1n1KcfY4cFQt8KxHEwErBg9GZ1FZBe7QMWotz/wr2zeSOKTlMNi6RLcpEJGOFJ3DoNzDMwktWFxuTKv46uRRASKzpqXDo2ZSutKG2uEaMXRCeH1TiGqBFwof5cbzi6GaofBCyucWteR8JGLpMQAYs1nXfOYO2ZKW3u1gnzT6NkHRaBjwnEvGQp04P+8NMW7r4iyiLOcDxy6ekS/keaJ5NJeqwA0fFSVm1Lu74s99uNswg+3w3yVtT+cOYYLgGIQ47ZxdJ6pE9C7wG33iAi7kXir2C0SJ2pWgcDfqvKkBg== x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR15MB2999.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFS:(376002)(136003)(366004)(346002)(396003)(39860400002)(66946007)(91956017)(6486002)(6512007)(66556008)(66446008)(316002)(66476007)(76116006)(33656002)(54906003)(186003)(6916009)(2616005)(64756008)(8676002)(36756003)(8936002)(4326008)(71200400001)(5660300002)(2906002)(6506007)(86362001)(53546011)(478600001);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata: 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 Content-Type: text/plain; charset="us-ascii" Content-ID: <1338DC8AF5FA0C4C865EF430627C1ADE@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB2999.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0a8600ca-ae60-42bd-9a9c-08d881e2f156 X-MS-Exchange-CrossTenant-originalarrivaltime: 05 Nov 2020 23:31:38.2852 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 6z+qljmYjf9KzzEGQtypE/eQSqaMoM1na1uGmSX5tRQsiZ5v3Yqu6nIOaNBDQX4e2DJ7oKtcB4m4OXF1fRvjRg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2695 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-11-05_16:2020-11-05,2020-11-05 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 spamscore=0 clxscore=1015 phishscore=0 impostorscore=0 mlxscore=0 mlxlogscore=999 suspectscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011050153 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Nov 5, 2020, at 3:22 PM, Daniel Xu wrote: >=20 > On Thu Nov 5, 2020 at 1:32 PM PST, Andrii Nakryiko wrote: >> On Wed, Nov 4, 2020 at 8:51 PM Daniel Xu wrote: > [...] >>> diff --git a/tools/testing/selftests/bpf/progs/test_probe_read_user_str= .c b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c >>> new file mode 100644 >>> index 000000000000..41c3e296566e >>> --- /dev/null >>> +++ b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c >>> @@ -0,0 +1,34 @@ >>> +// SPDX-License-Identifier: GPL-2.0 >>> + >>> +#include >>> +#include >>> +#include >>> + >>> +#include >>> + >>> +struct sys_enter_write_args { >>> + unsigned long long pad; >>> + int syscall_nr; >>> + int pad1; /* 4 byte hole */ >>=20 >> I have a hunch that this explicit padding might break on big-endian >> architectures?.. >>=20 >> Can you instead include "vmlinux.h" in this file and use struct >> trace_event_raw_sys_enter? you'll just need ctx->args[2] to get that >> buffer pointer. >>=20 >> Alternatively, and it's probably simpler overall would be to just >> provide user-space pointer through global variable: >>=20 >> void *user_ptr; >>=20 >>=20 >> bpf_probe_read_user_str(buf, ..., user_ptr); >>=20 >> From user-space: >>=20 >> skel->bss->user_ptr =3D &my_userspace_buf; >>=20 >> Full control. You can trigger tracepoint with just an usleep(1), for >> instance. >=20 > Yeah, that sounds better. I'll send a v4 with passing a ptr. >=20 > Thanks, > Daniel One more comment, how about we test multiple strings with different=20 lengths? In this way, we can catch other alignment issues.=20 Thanks, Song