From patchwork Mon Apr 27 20:12:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 220473 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=-8.9 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 DA3C8C54FD0 for ; Mon, 27 Apr 2020 20:12:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B67F42072D for ; Mon, 27 Apr 2020 20:12:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="QNdrNq45" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726752AbgD0UMj (ORCPT ); Mon, 27 Apr 2020 16:12:39 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:51400 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725919AbgD0UMi (ORCPT ); Mon, 27 Apr 2020 16:12:38 -0400 Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 03RKAj9B025684 for ; Mon, 27 Apr 2020 13:12:37 -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=ppiUiYcTNREpJMCXv9jCfRZetzLJRH4pmtu6ytKy4q8=; b=QNdrNq456wo+ey77058G5FAusGKBoP8ScpxKAQR7w0/2f+7BK9JrnbWYDCzykO8ngIVI KM4yvIEFiHD9c9pPIyZsHQKs92u6GsoDR/2xZ9URN1UrwNjgk8n9x9/yDa95yOeVPR6U M21nvehaz4oaTesqWu6i8z8hxA0Oj4dFGgw= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 30n515t6xj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 27 Apr 2020 13:12:37 -0700 Received: from intmgw002.08.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::d) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1847.3; Mon, 27 Apr 2020 13:12:36 -0700 Received: by devbig003.ftw2.facebook.com (Postfix, from userid 128203) id 3976D3700871; Mon, 27 Apr 2020 13:12:35 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Yonghong Song Smtp-Origin-Hostname: devbig003.ftw2.facebook.com To: Andrii Nakryiko , , Martin KaFai Lau , CC: Alexei Starovoitov , Daniel Borkmann , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next v1 00/19] bpf: implement bpf iterator for kernel data Date: Mon, 27 Apr 2020 13:12:35 -0700 Message-ID: <20200427201235.2994549-1-yhs@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-27_15:2020-04-27,2020-04-27 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 adultscore=0 malwarescore=0 impostorscore=0 clxscore=1015 spamscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 mlxlogscore=999 phishscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004270164 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Motivation: The current way to dump kernel data structures mostly: 1. /proc system 2. various specific tools like "ss" which requires kernel support. 3. drgn The dropback for the first two is that whenever you want to dump more, you need change the kernel. For example, Martin wants to dump socket local storage with "ss". Kernel change is needed for it to work ([1]). This is also the direct motivation for this work. drgn ([2]) solves this proble nicely and no kernel change is not needed. But since drgn is not able to verify the validity of a particular pointer value, it might present the wrong results in rare cases. In this patch set, we introduce bpf iterator. Initial kernel changes are still needed for interested kernel data, but a later data structure change will not require kernel changes any more. bpf program itself can adapt to new data structure changes. This will give certain flexibility with guaranteed correctness. In this patch set, kernel seq_ops is used to facilitate iterating through kernel data, similar to current /proc and many other lossless kernel dumping facilities. In the future, different iterators can be implemented to trade off losslessness for other criteria e.g. no repeated object visits, etc. User Interface: 1. Similar to prog/map/link, the iterator can be pinned into a path within a bpffs mount point. 2. The bpftool command can pin an iterator to a file bpftool iter pin 3. Use `cat ` to dump the contents. Use `rm -f ` to remove the pinned iterator. 4. The anonymous iterator can be created as well. Please see patch #17 andd #18 for bpf programs and bpf iterator output examples. Note that certain iterators are namespace aware. For example, task and task_file targets only iterate through current pid namespace. ipv6_route and netlink will iterate through current net namespace. Please see individual patches for implementation details. Performance: The bpf iterator provides in-kernel aggregation abilities for kernel data. This can greatly improve performance compared to e.g., iterating all process directories under /proc. For example, I did an experiment on my VM with an application forking different number of tasks and each forked process opening various number of files. The following is the result with the latency with unit of microseconds: # of forked tasks # of open files # of bpf_prog calls # latency (us) 100 100 11503 7586 1000 1000 1013203 709513 10000 100 1130203 764519 The number of bpf_prog calls may be more than forked tasks multipled by open files since there are other tasks running on the system. The bpf program is a do-nothing program. One millions of bpf calls takes less than one second. Future Work: Although the initial motivation is from Martin's sk_local_storage, this patch didn't implement tcp6 sockets and sk_local_storage. The /proc/net/tcp6 involves three types of sockets, timewait, request and tcp6 sockets. Some kind of type casting or other mechanism is needed to handle all these socket types in one bpf program. This will be addressed in future work. Currently, we do not support kernel data generated under module. This requires some BTF work. More work for more iterators, e.g., bpf_progs, cgroups, bpf_map elements, etc. Changelog: RFC v2 ([3]) -> non-RFC v1: - rename bpfdump to bpf_iter - use bpffs instead of a new file system - use bpf_link to streamline and simplify iterator creation. References: [1]: https://lore.kernel.org/bpf/20200225230427.1976129-1-kafai@fb.com [2]: https://github.com/osandov/drgn [3]: https://lore.kernel.org/bpf/40e427e2-5b15-e9aa-e2cb-42dc1b53d047@gmail.com/T/ Yonghong Song (19): net: refactor net assignment for seq_net_private structure bpf: implement an interface to register bpf_iter targets bpf: add bpf_map iterator bpf: allow loading of a bpf_iter program bpf: support bpf tracing/iter programs for BPF_LINK_CREATE bpf: support bpf tracing/iter programs for BPF_LINK_UPDATE bpf: create anonymous bpf iterator bpf: create file bpf iterator bpf: add PTR_TO_BTF_ID_OR_NULL support bpf: add netlink and ipv6_route targets bpf: add task and task/file targets bpf: add bpf_seq_printf and bpf_seq_write helpers bpf: handle spilled PTR_TO_BTF_ID properly when checking stack_boundary bpf: support variable length array in tracing programs tools/libbpf: add bpf_iter support tools/bpftool: add bpf_iter support for bptool tools/bpf: selftests: add iterator programs for ipv6_route and netlink tools/bpf: selftests: add iter progs for bpf_map/task/task_file tools/bpf: selftests: add bpf_iter selftests fs/proc/proc_net.c | 5 +- include/linux/bpf.h | 33 ++ include/linux/seq_file_net.h | 8 + include/uapi/linux/bpf.h | 38 +- kernel/bpf/Makefile | 2 +- kernel/bpf/bpf_iter.c | 358 ++++++++++++++++++ kernel/bpf/btf.c | 38 +- kernel/bpf/inode.c | 28 ++ kernel/bpf/map_iter.c | 107 ++++++ kernel/bpf/syscall.c | 62 ++- kernel/bpf/task_iter.c | 319 ++++++++++++++++ kernel/bpf/verifier.c | 47 ++- kernel/trace/bpf_trace.c | 159 ++++++++ net/ipv6/ip6_fib.c | 71 +++- net/ipv6/route.c | 30 ++ net/netlink/af_netlink.c | 99 ++++- scripts/bpf_helpers_doc.py | 2 + .../bpftool/Documentation/bpftool-iter.rst | 71 ++++ tools/bpf/bpftool/bash-completion/bpftool | 13 + tools/bpf/bpftool/iter.c | 84 ++++ tools/bpf/bpftool/main.c | 3 +- tools/bpf/bpftool/main.h | 1 + tools/include/uapi/linux/bpf.h | 38 +- tools/lib/bpf/bpf.c | 11 + tools/lib/bpf/bpf.h | 2 + tools/lib/bpf/bpf_tracing.h | 23 ++ tools/lib/bpf/libbpf.c | 60 +++ tools/lib/bpf/libbpf.h | 11 + tools/lib/bpf/libbpf.map | 7 + .../selftests/bpf/prog_tests/bpf_iter.c | 180 +++++++++ .../selftests/bpf/progs/bpf_iter_bpf_map.c | 32 ++ .../selftests/bpf/progs/bpf_iter_ipv6_route.c | 69 ++++ .../selftests/bpf/progs/bpf_iter_netlink.c | 77 ++++ .../selftests/bpf/progs/bpf_iter_task.c | 29 ++ .../selftests/bpf/progs/bpf_iter_task_file.c | 28 ++ .../selftests/bpf/progs/bpf_iter_test_kern1.c | 4 + .../selftests/bpf/progs/bpf_iter_test_kern2.c | 4 + .../selftests/bpf/progs/bpf_iter_test_kern3.c | 18 + .../bpf/progs/bpf_iter_test_kern_common.h | 22 ++ 39 files changed, 2174 insertions(+), 19 deletions(-) create mode 100644 kernel/bpf/bpf_iter.c create mode 100644 kernel/bpf/map_iter.c create mode 100644 kernel/bpf/task_iter.c create mode 100644 tools/bpf/bpftool/Documentation/bpftool-iter.rst create mode 100644 tools/bpf/bpftool/iter.c create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_iter.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_ipv6_route.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_netlink.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_file.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern1.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern2.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern3.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern_common.h