From patchwork Sun Jun 26 03:13:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuang Wang X-Patchwork-Id: 12895581 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA170C433EF for ; Sun, 26 Jun 2022 03:13:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233880AbiFZDNY (ORCPT ); Sat, 25 Jun 2022 23:13:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230050AbiFZDNW (ORCPT ); Sat, 25 Jun 2022 23:13:22 -0400 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE1DEA459; Sat, 25 Jun 2022 20:13:20 -0700 (PDT) Received: by mail-pl1-x629.google.com with SMTP id l6so5338025plg.11; Sat, 25 Jun 2022 20:13:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=SgbVSj7uwsLnvEUbZN3GbnRrDYKXQqdcuWn4sqFZbNg=; b=iB/S/QAzCdI/g68PoramR6Mb+h4Ws1VqmlViROnz2he1H/oDuPwxBxpg/huDmxrIT0 LU2ZfiKSl+9snTtgUhkgEwliW/p1M0u4m+V8VhbGA60++/wOkmQ+RPNixycJl1o0X8En omrRBRfy5taE4pp8adIjzbfMBJwW2dHMFaSGrKIifxROgor8FmJfWCz8ouUdVrX8NmTE TVow5tT5P3fxnJztRXhjzmiMKXNpSBwPubHud6Eo4lozVgS9/tdBXZF4089cn6QhW7X6 nypcsCBhKZxN0n5LzRN9lqftJOrZk3jzGe74M6iLoFbbV55wWiPdpal6alAqtcOwNXeP 0xyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=SgbVSj7uwsLnvEUbZN3GbnRrDYKXQqdcuWn4sqFZbNg=; b=czlaj5KANe7T2gZcyW4sjMBNrjrfwT23gORugF2CdSF4lEfZyB/I49tIqaXPByKPBn obM0imRPK2EzshfJdFUqxOmo7ukZMi1ENgbh9ES4u46pNK9HjxDJCdnwJeH4agOL39wn ZYrsvREpcoZM4e/O+iAS1UaRp0rqkLMvvA1uGvRXLE5XRQkuwJZ1LBuzaVYcHUjxBykJ GZA0uuFWefrI6uxW2cOwaXu2i66r1pzyl3+NeeCRCYpoyYnjYJhWYXLpsoddWz3Fso6p hQFE7vN3dU6AXTy2b92LxiIRlddzJfFP3ezrI2omFAQOpn08/uZZgJBVipT45oSV5Vfu AIfQ== X-Gm-Message-State: AJIora9l3Os00m7/ySkMY77zm8Lc6PDPF+6mRRcwwWh+usNdUq69QNUy 9lblMkuQxWvTw4M3qM59EO8= X-Google-Smtp-Source: AGRyM1stAWGoo0bxh88Zdi6Q4DRIQGkWuqyjqvmBVE9AZu+PgPasDI6mXiAa9YTxhVomXojubSDOjw== X-Received: by 2002:a17:902:da87:b0:16a:2158:9a11 with SMTP id j7-20020a170902da8700b0016a21589a11mr7268381plx.71.1656213200211; Sat, 25 Jun 2022 20:13:20 -0700 (PDT) Received: from localhost.localdomain ([47.242.114.172]) by smtp.gmail.com with ESMTPSA id q16-20020a17090311d000b001636c0b98a7sm4366652plh.226.2022.06.25.20.13.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 25 Jun 2022 20:13:19 -0700 (PDT) From: Chuang W Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Masami Hiramatsu , Chuang W , Jingren Zhou Subject: [PATCH v3] libbpf: Cleanup the legacy kprobe_event on failed add/attach_event() Date: Sun, 26 Jun 2022 11:13:01 +0800 Message-Id: <20220626031301.60390-1-nashuiliang@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Before the 0bc11ed5ab60 commit ("kprobes: Allow kprobes coexist with livepatch"), in a scenario where livepatch and kprobe coexist on the same function entry, the creation of kprobe_event using add_kprobe_event_legacy() will be successful, at the same time as a trace event (e.g. /debugfs/tracing/events/kprobe/XXX) will exist, but perf_event_open() will return an error because both livepatch and kprobe use FTRACE_OPS_FL_IPMODIFY. As follows: 1) add a livepatch $ insmod livepatch-XXX.ko 2) add a kprobe using tracefs API (i.e. add_kprobe_event_legacy) $ echo 'p:mykprobe XXX' > /sys/kernel/debug/tracing/kprobe_events 3) enable this kprobe (i.e. sys_perf_event_open) This will return an error, -EBUSY. On Andrii Nakryiko's comment, few error paths in bpf_program__attach_kprobe_opts() which should need to call remove_kprobe_event_legacy(). With this patch, whenever an error is returned after add_kprobe_event_legacy() or bpf_program__attach_perf_event_opts(), this ensures that the created kprobe_event is cleaned. Signed-off-by: Chuang W Signed-off-by: Jingren Zhou --- V2->v3: - add detail commits - call remove_kprobe_event_legacy() on failed bpf_program__attach_perf_event_opts() tools/lib/bpf/libbpf.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 49e359cd34df..038b0cb3313f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10811,10 +10811,11 @@ static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe, } type = determine_kprobe_perf_type_legacy(probe_name, retprobe); if (type < 0) { + err = type; pr_warn("failed to determine legacy kprobe event id for '%s+0x%zx': %s\n", kfunc_name, offset, - libbpf_strerror_r(type, errmsg, sizeof(errmsg))); - return type; + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); + goto clear_kprobe_event; } attr.size = sizeof(attr); attr.config = type; @@ -10828,9 +10829,14 @@ static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe, err = -errno; pr_warn("legacy kprobe perf_event_open() failed: %s\n", libbpf_strerror_r(err, errmsg, sizeof(errmsg))); - return err; + goto clear_kprobe_event; } return pfd; + +clear_kprobe_event: + /* Clear the newly added legacy kprobe_event */ + remove_kprobe_event_legacy(probe_name, retprobe); + return err; } struct bpf_link * @@ -10899,6 +10905,9 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog, return link; err_out: + /* Clear the newly added legacy kprobe_event */ + if (legacy) + remove_kprobe_event_legacy(legacy_probe, retprobe); free(legacy_probe); return libbpf_err_ptr(err); }