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=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 9C506C433DF for ; Fri, 7 Aug 2020 21:06:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69DD322C9F for ; Fri, 7 Aug 2020 21:06:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="na6mS3PR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726256AbgHGVGg (ORCPT ); Fri, 7 Aug 2020 17:06:36 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:25682 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726045AbgHGVGg (ORCPT ); Fri, 7 Aug 2020 17:06:36 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 077KuuQs007171 for ; Fri, 7 Aug 2020 14:06:35 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=xA+PJgaP2MGZT8owly/cFRkq/+6SX04kkzCp/aaprd8=; b=na6mS3PRY4Y2j5BTkbDC7QpTRv00vAlXsaqJ/1I4SrGm/NfMMmFJ1vyOWPcudOdpu0oE YPtzS/mbbWaPgiQRhvdnpXAOVN5dhyVUf9GlmO5oIx4TUk/OsRzvAPn/sIH3O/g0EZFM D/TAK3tFE2ZgIfjNO9WRgbLAj63IGKzt5fE= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 32s96m9pv2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 07 Aug 2020 14:06:35 -0700 Received: from intmgw002.08.frc2.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Fri, 7 Aug 2020 14:06:34 -0700 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 758062EC5494; Fri, 7 Aug 2020 14:06:32 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Andrii Nakryiko Smtp-Origin-Hostname: devbig012.ftw2.facebook.com To: , , , CC: , , Andrii Nakryiko Smtp-Origin-Cluster: ftw2c04 Subject: [RFC PATCH bpf-next 0/7] libbpf feature probing and sanitization improvements Date: Fri, 7 Aug 2020 14:06:22 -0700 Message-ID: <20200807210629.394335-1-andriin@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-07_20:2020-08-06,2020-08-07 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 impostorscore=0 mlxlogscore=799 spamscore=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=8 adultscore=0 clxscore=1015 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008070147 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org This patch set refactors libbpf feature probing to be done lazily on as-n= eeded basis, instead of proactively testing all possible features libbpf knows about. This allows to scale such detections and mitigations better, witho= ut issues unnecessary syscalls on each bpf_object__load() call. It's also no= w memoized globally, instead of per-bpf_object. Building on that, libbpf will now detect availability of bpf_probe_read_kernel() helper (which means also -user and -str variants)= , and will sanitize BPF program code by replacing such references to generic variants (bpf_probe_read[_str]()). This allows to migrate all BPF program= s into proper -kernel/-user probing helpers, without the fear of breaking t= hem for old kernels. With that, update BPF_CORE_READ() and related macros to use bpf_probe_read_kernel(), as it doesn't make much sense to do CO-RE reloca= tions against user-space types. And the only class of cases in which BPF progra= m might read kernel type from user-space are UAPI data structures which by definition are fixed in their memory layout and don't need relocating. Th= is is exemplified by test_vmlinux test, which is fixed as part of this patch se= t as well. BPF_CORE_READ() is useful for chainingg bpf_probe_read_{kernel,user= }() calls together even without relocation, so we might add user-space varian= ts, if there is a need. While at making libbpf more useful for older kernels, also improve handli= ng of a complete lack of BTF support in kernel by not even attempting to load B= TF info into kernel. This eliminates annoying warning about lack of BTF supp= ort in the kernel and map creation retry without BTF. If user is using featur= es that require kernel BTF support, it will still fail, of course. Andrii Nakryiko (7): libbpf: disable -Wswitch-enum compiler warning libbpf: make kernel feature probing lazy libbpf: factor out common logic of testing and closing FD libbpf: sanitize BPF program code for bpf_probe_read_{kernel,user}[_str] selftests/bpf: fix test_vmlinux test to use bpf_probe_read_user() libbpf: switch tracing and CO-RE helper macros to bpf_probe_read_kernel() libbpf: detect minimal BTF support and skip BTF loading, if missing tools/lib/bpf/Makefile | 2 +- tools/lib/bpf/bpf_core_read.h | 40 ++- tools/lib/bpf/bpf_tracing.h | 4 +- tools/lib/bpf/libbpf.c | 319 +++++++++++------- .../selftests/bpf/progs/test_vmlinux.c | 12 +- 5 files changed, 240 insertions(+), 137 deletions(-) --=20 2.24.1