From patchwork Thu Sep 17 20:20:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Patchwork-Id: 1366430 Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=gfn7ZHAH; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BspHL2SW8z9sRR for ; Fri, 18 Sep 2020 06:20:14 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726601AbgIQUUM (ORCPT ); Thu, 17 Sep 2020 16:20:12 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:51328 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726551AbgIQUUK (ORCPT ); Thu, 17 Sep 2020 16:20:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600374007; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=Y/gm/lqx1rB+klxtCVXjA/M0emGyI14+LImzRquikw0=; b=gfn7ZHAHUhetjKXk7ZG4p7qw80tF1dBWJ9skeVex8vHE2i60j9tY8vPATPdJRCsvKWtCDv 9nd0CmbqvjiVYUlabp3QEevTTEIxXtw678Gs/NNtEOYRFVzfdsFTT6VP0e3beNLVTA5c4k 7cixPSTolGGavc4oC86ZxyceHf8WJZI= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-258-G7CImC-7Pb2eTJMSepjkNA-1; Thu, 17 Sep 2020 16:20:04 -0400 X-MC-Unique: G7CImC-7Pb2eTJMSepjkNA-1 Received: by mail-ed1-f69.google.com with SMTP id i22so1393569edu.1 for ; Thu, 17 Sep 2020 13:20:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:user-agent :mime-version:content-transfer-encoding; bh=Y/gm/lqx1rB+klxtCVXjA/M0emGyI14+LImzRquikw0=; b=GHO8RwtlyrwAmZ5QcV0xf/c5HGABX3QiTeLhvms9lXyJ3zcSuV8kN+ho7hp5RnMrAS 5IH4YLRmlVrX+rZOtQTERlsRs/zrYlwjhsA4K6wca8tb6AqIbcHxzbQo+jM5c6v/b6mS dY3fnjEKwUeOT1nD369+YcBgleFltVCRKgpWqEVMxKTCMaNpWt3G78fnwTMLolVJujNB b9YiMu7jJIaB34T0qZ/n6vFbvaKqnt84r1KHrJwGRCnZ22H+3tiiMvjj1TAlpCFAJqeB 8cYknGqziZgUTi8B0XPSemL5cGZpWk1UH5uE8VuXr6D9FG+l4Irn3pNbtr0b3yqmim3n KKwg== X-Gm-Message-State: AOAM530vDYzfMGvPWeUqaIA4twtHOn8Vce6W9L+kQNNsSq0GnY4Lzt/Z Ig61fV9Wc1QEIL0bhljnNDtUbt3QuI7ifcQiMkiDN0vBzRGD2ln2OJOsgkSfm6L2iPUysbE7ozB vQmcdjWl4iSCoNbI3 X-Received: by 2002:a17:906:4e4a:: with SMTP id g10mr31503553ejw.274.1600374002460; Thu, 17 Sep 2020 13:20:02 -0700 (PDT) X-Google-Smtp-Source: ABdhPJx9Hic0whsoTUweQJ68zOVwjwPa9dGu40GsFYMsZk094psyGbsiKkBquOxWnQHpFyDf0tQngQ== X-Received: by 2002:a17:906:4e4a:: with SMTP id g10mr31503526ejw.274.1600374002030; Thu, 17 Sep 2020 13:20:02 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id h13sm691706ejl.77.2020.09.17.13.20.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2020 13:20:01 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id AD54F183A90; Thu, 17 Sep 2020 22:20:00 +0200 (CEST) Subject: [PATCH bpf-next v6 00/10] bpf: Support multi-attach for freplace programs From: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Alexei Starovoitov Cc: Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , Jiri Olsa , Eelco Chaudron , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org Date: Thu, 17 Sep 2020 22:20:00 +0200 Message-ID: <160037400056.28970.7647821897296177963.stgit@toke.dk> User-Agent: StGit/0.23 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This series adds support attaching freplace BPF programs to multiple targets. This is needed to support incremental attachment of multiple XDP programs using the libxdp dispatcher model. The first patch fixes an issue that came up in review: The verifier will currently allow MODIFY_RETURN tracing functions to attach to other BPF programs, even though it is pretty clear from the commit messages introducing the functionality that this was not the intention. This patch is included in the serise because the subsequent refactoring patches touch the same code. The next three patches are refactoring patches: Patch 2 is a trivial change to the logging in the verifier, split out to make the subsequent refactor easier to read. Patch 3 refactors check_attach_btf_id() so that the checks on program and target compatibility can be reused when attaching to a secondary location. Patch 4 moves prog_aux->linked_prog and the trampoline to be embedded in bpf_tracing_link on attach, and freed by the link release logic, and introduces a mutex to protect the writing of the pointers in prog->aux. Based on these refactorings, it becomes pretty straight-forward to support multiple-attach for freplace programs (patch 5). This is simply a matter of creating a second bpf_tracing_link if a target is supplied. However, for API consistency with other types of link attach, this option is added to the BPF_LINK_CREATE API instead of extending bpf_raw_tracepoint_open(). Patch 6 is a port of Jiri Olsa's patch to support fentry/fexit on freplace programs. His approach of getting the target type from the target program reference no longer works after we've gotten rid of linked_prog (because the bpf_tracing_link reference disappears on attach). Instead, we used the saved reference to the target prog type that is also used to verify compatibility on secondary freplace attachment. Patches 7 is the accompanying libbpf update, and patches 8-10 are selftests: patch 8 tests for the multi-freplace functionality itself, patch 9 is Jiri's previous selftest for the fentry-to-freplace fix, and patch 10 is a test for the change introduced in patch 1, blocking MODIFY_RETURN functions from attaching to other BPF programs. With this series, libxdp and xdp-tools can successfully attach multiple programs one at a time. To play with this, use the 'freplace-multi-attach' branch of xdp-tools: $ git clone --recurse-submodules --branch freplace-multi-attach https://github.com/xdp-project/xdp-tools $ cd xdp-tools $ make $ sudo ./xdp-loader/xdp-loader load veth0 lib/testing/xdp_drop.o $ sudo ./xdp-loader/xdp-loader load veth0 lib/testing/xdp_pass.o $ sudo ./xdp-loader/xdp-loader status The series is also available here: https://git.kernel.org/pub/scm/linux/kernel/git/toke/linux.git/log/?h=bpf-freplace-multi-attach-alt-06 Changelog: v6: - Rebase to latest bpf-next - Simplify logic in bpf_tracing_prog_attach() - Don't create a new attach_type for link_create(), disambiguate on prog->type instead - Use raw_tracepoint_open() in libbpf bpf_program__attach_ftrace() if called with NULL target - Switch bpf_program__attach_ftrace() to take function name as parameter instead of btf_id - Add a patch disallowing MODIFY_RETURN programs from attaching to other BPF programs, and an accompanying selftest (patches 1 and 10) v5: - Fix typo in inline function definition of bpf_trampoline_get() - Don't put bpf_tracing_link in prog->aux, use a mutex to protect tgt_prog and trampoline instead, and move them to the link on attach. - Restore Jiri as author of the last selftest patch v4: - Cleanup the refactored check_attach_btf_id() to make the logic easier to follow - Fix cleanup paths for bpf_tracing_link - Use xchg() for removing the bpf_tracing_link from prog->aux and restore on (some) failures - Use BPF_LINK_CREATE operation to create link with target instead of extending raw_tracepoint_open - Fold update of tools/ UAPI header into main patch - Update arg dereference patch to use skeletons and set_attach_target() v3: - Get rid of prog_aux->linked_prog entirely in favour of a bpf_tracing_link - Incorporate Jiri's fix for attaching fentry to freplace programs v2: - Drop the log arguments from bpf_raw_tracepoint_open - Fix kbot errors - Rebase to latest bpf-next --- Jiri Olsa (1): selftests/bpf: Adding test for arg dereference in extension trace Toke Høiland-Jørgensen (9): bpf: disallow attaching modify_return tracing functions to other BPF programs bpf: change logging calls from verbose() to bpf_log() and use log pointer bpf: verifier: refactor check_attach_btf_id() bpf: move prog->aux->linked_prog and trampoline into bpf_link on attach bpf: support attaching freplace programs to multiple attach points bpf: Fix context type resolving for extension programs libbpf: add support for freplace attachment in bpf_link_create selftests: add test for multiple attachments of freplace program selftests: Add selftest for disallowing modify_return attachment to freplace include/linux/bpf.h | 26 +- include/linux/bpf_verifier.h | 14 +- include/uapi/linux/bpf.h | 9 +- kernel/bpf/btf.c | 21 +- kernel/bpf/core.c | 9 +- kernel/bpf/syscall.c | 136 ++++++++-- kernel/bpf/trampoline.c | 32 ++- kernel/bpf/verifier.c | 247 ++++++++++-------- tools/include/uapi/linux/bpf.h | 9 +- tools/lib/bpf/bpf.c | 1 + tools/lib/bpf/bpf.h | 3 +- tools/lib/bpf/libbpf.c | 36 ++- tools/lib/bpf/libbpf.h | 3 + tools/lib/bpf/libbpf.map | 1 + .../selftests/bpf/prog_tests/fexit_bpf2bpf.c | 225 +++++++++++++--- .../selftests/bpf/prog_tests/trace_ext.c | 111 ++++++++ .../selftests/bpf/progs/fmod_ret_freplace.c | 14 + .../bpf/progs/freplace_get_constant.c | 15 ++ .../selftests/bpf/progs/test_trace_ext.c | 18 ++ .../bpf/progs/test_trace_ext_tracing.c | 25 ++ 20 files changed, 765 insertions(+), 190 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_ext.c create mode 100644 tools/testing/selftests/bpf/progs/fmod_ret_freplace.c create mode 100644 tools/testing/selftests/bpf/progs/freplace_get_constant.c create mode 100644 tools/testing/selftests/bpf/progs/test_trace_ext.c create mode 100644 tools/testing/selftests/bpf/progs/test_trace_ext_tracing.c