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[219.74.209.211]) by smtp.gmail.com with ESMTPSA id z9-20020aa791c9000000b00640dbbd7830sm6044479pfa.18.2023.07.30.04.50.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 30 Jul 2023 04:50:12 -0700 (PDT) From: Leon Hwang To: ast@kernel.org Cc: daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mykolal@fb.com, shuah@kernel.org, hffilwlqm@gmail.com, tangyeechou@gmail.com, kernel-patches-bot@fb.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next v4 1/2] bpf, xdp: Add tracepoint to xdp attaching failure Date: Sun, 30 Jul 2023 19:49:50 +0800 Message-ID: <20230730114951.74067-2-hffilwlqm@gmail.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230730114951.74067-1-hffilwlqm@gmail.com> References: <20230730114951.74067-1-hffilwlqm@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,HK_RANDOM_ENVFROM, HK_RANDOM_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net When error happens in dev_xdp_attach(), it should have a way to tell users the error message like the netlink approach. To avoid breaking uapi, adding a tracepoint in bpf_xdp_link_attach() is an appropriate way to notify users the error message. Hence, bpf libraries are able to retrieve the error message by this tracepoint, and then report the error message to users. Signed-off-by: Leon Hwang --- include/trace/events/xdp.h | 17 +++++++++++++++++ net/core/dev.c | 5 ++++- 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h index c40fc97f94171..cd89f1d5ce7b8 100644 --- a/include/trace/events/xdp.h +++ b/include/trace/events/xdp.h @@ -404,6 +404,23 @@ TRACE_EVENT(mem_return_failed, ) ); +TRACE_EVENT(bpf_xdp_link_attach_failed, + + TP_PROTO(const char *msg), + + TP_ARGS(msg), + + TP_STRUCT__entry( + __string(msg, msg) + ), + + TP_fast_assign( + __assign_str(msg, msg); + ), + + TP_printk("errmsg=%s", __get_str(msg)) +); + #endif /* _TRACE_XDP_H */ #include diff --git a/net/core/dev.c b/net/core/dev.c index 8e7d0cb540cdb..49bed890f807e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -133,6 +133,7 @@ #include #include #include +#include #include #include #include @@ -9472,6 +9473,7 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) struct bpf_link_primer link_primer; struct bpf_xdp_link *link; struct net_device *dev; + struct netlink_ext_ack extack; int err, fd; rtnl_lock(); @@ -9497,12 +9499,13 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) goto unlock; } - err = dev_xdp_attach_link(dev, NULL, link); + err = dev_xdp_attach_link(dev, &extack, link); rtnl_unlock(); if (err) { link->dev = NULL; bpf_link_cleanup(&link_primer); + trace_bpf_xdp_link_attach_failed(extack._msg); goto out_put_dev; } From patchwork Sun Jul 30 11:49:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13333400 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B25A15BD; Sun, 30 Jul 2023 11:50:23 +0000 (UTC) Received: from mail-io1-xd34.google.com (mail-io1-xd34.google.com [IPv6:2607:f8b0:4864:20::d34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 02A531BCA; Sun, 30 Jul 2023 04:50:18 -0700 (PDT) Received: by mail-io1-xd34.google.com with SMTP id ca18e2360f4ac-79095499a17so60476739f.3; Sun, 30 Jul 2023 04:50:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690717818; x=1691322618; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=jfr1Y42UBgl3e0tdEuSJS6cxP3FzYxJ2E6D2Od/ZUJI=; b=q34ZyETJxnkUKVtdAl87ZXCQRaPMBnMUnOOoxaJxzg+uQDfIJ2fFXCP4ggLtXfQgmL U7JH9j+64DlOHzMa3hohOIPsVt+eEOxDerQTSkQObRrCVMa8PytKTWx+4lgb7tvkzCZG 8arhBnIhtje5LdTOUPKqDyOhvlw5v1RaG6GBnzvNImmtF7svcWZ2D9CsZq6QAhO4fxkJ FaGpP0/9Rw+Iu6xSPBOT7NHeyVQBPG6H3CKWzaoRwqL6R00Res8y5RdpzbN6zdYvs3J6 Newe68YaSJui0oNP3tSxYDrVab4mqnjm2LAxp69rhItX5iW93R/Casml3udemOWjUsAN TwUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690717818; x=1691322618; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=jfr1Y42UBgl3e0tdEuSJS6cxP3FzYxJ2E6D2Od/ZUJI=; b=Ry95Q6OPxBbT9qnJBmzw+IBKK1AAvJ148D9UsR7dEDRp3gLH/msKcx0KkXc60RpdwB GdtVWfJ80TMDxwl88OUqwhmPAs3fDi49dKVUDY6GPjn/9q+S+fNCE5XcG6uIhBrewExV sjlbptliMovjNyLmpx00LSJgZIfaWu5DJFEqTZeA9HVlF2tWNGRwF+RB2UIGp5ZrfgkJ 2RMAUjV9tg/zrWESPd78BymMhRyl4EW8HIvKZUlb2zksiSmBjVPpY6bzH9noH2wkbsJU Rb36JvUm1QCDR+kqKIotPRsxiqCyYDcZSOugVW7+MfbNZksmiEDwRY04dHrfPThN/Mz1 gXAw== X-Gm-Message-State: ABy/qLbfHWJGgq3+BoJLjp2aNK5W/9CuxOC3k5u13K7k1H53pICLK3Ih XqV8pO+iY/XXBt7JT9jtMJ0= X-Google-Smtp-Source: APBJJlHYabs5d+521Nt3ZmEBSUfIhJwIRO3dedJjoRuAR1wcLTNZF6om6dhc5zYP+nd+ls+RoJ03Bw== X-Received: by 2002:a05:6602:392:b0:790:8b8a:e616 with SMTP id f18-20020a056602039200b007908b8ae616mr5560708iov.10.1690717818140; Sun, 30 Jul 2023 04:50:18 -0700 (PDT) Received: from localhost.localdomain (bb219-74-209-211.singnet.com.sg. [219.74.209.211]) by smtp.gmail.com with ESMTPSA id z9-20020aa791c9000000b00640dbbd7830sm6044479pfa.18.2023.07.30.04.50.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 30 Jul 2023 04:50:17 -0700 (PDT) From: Leon Hwang To: ast@kernel.org Cc: daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mykolal@fb.com, shuah@kernel.org, hffilwlqm@gmail.com, tangyeechou@gmail.com, kernel-patches-bot@fb.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next v4 2/2] selftests/bpf: Add testcase for xdp attaching failure tracepoint Date: Sun, 30 Jul 2023 19:49:51 +0800 Message-ID: <20230730114951.74067-3-hffilwlqm@gmail.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230730114951.74067-1-hffilwlqm@gmail.com> References: <20230730114951.74067-1-hffilwlqm@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,HK_RANDOM_ENVFROM, HK_RANDOM_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net Add a test case for the tracepoint of xdp attaching failure by bpf tracepoint when attach XDP to a device with invalid flags option. The bpf tracepoint retrieves error message from the tracepoint, and then put the error message to a perf buffer. The testing code receives error message from perf buffer, and then ASSERT "Invalid XDP flags for BPF link attachment". Signed-off-by: Leon Hwang --- .../selftests/bpf/prog_tests/xdp_attach.c | 65 +++++++++++++++++++ .../bpf/progs/test_xdp_attach_fail.c | 54 +++++++++++++++ 2 files changed, 119 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c index fa3cac5488f5d..8c1cde74e9cd6 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_attach.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include "test_xdp_attach_fail.skel.h" #define IFINDEX_LO 1 #define XDP_FLAGS_REPLACE (1U << 4) @@ -85,10 +86,74 @@ static void test_xdp_attach(const char *file) bpf_object__close(obj1); } +#define ERRMSG_LEN 64 + +struct xdp_errmsg { + char msg[ERRMSG_LEN]; +}; + +static void on_xdp_errmsg(void *ctx, int cpu, void *data, __u32 size) +{ + struct xdp_errmsg *ctx_errmg = ctx, *tp_errmsg = data; + + memcpy(&ctx_errmg->msg, &tp_errmsg->msg, ERRMSG_LEN); +} + +static const char tgt_errmsg[] = "Invalid XDP flags for BPF link attachment"; + +static void test_xdp_attach_fail(const char *file) +{ + int err, fd_xdp; + struct bpf_object *obj = NULL; + struct test_xdp_attach_fail *skel = NULL; + struct perf_buffer *pb = NULL; + struct xdp_errmsg errmsg = {}; + + LIBBPF_OPTS(bpf_link_create_opts, opts); + + skel = test_xdp_attach_fail__open_and_load(); + if (!ASSERT_OK_PTR(skel, "test_xdp_attach_fail__open_and_load")) + goto out_close; + + err = test_xdp_attach_fail__attach(skel); + if (!ASSERT_EQ(err, 0, "test_xdp_attach_fail__attach")) + goto out_close; + + /* set up perf buffer */ + pb = perf_buffer__new(bpf_map__fd(skel->maps.xdp_errmsg_pb), 1, + on_xdp_errmsg, NULL, &errmsg, NULL); + if (!ASSERT_OK_PTR(pb, "perf_buffer__new")) + goto out_close; + + err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &fd_xdp); + if (!ASSERT_EQ(err, 0, "bpf_prog_test_load")) + goto out_close; + + opts.flags = 0xFF; // invalid flags to fail to attach XDP prog + err = bpf_link_create(fd_xdp, IFINDEX_LO, BPF_XDP, &opts); + if (!ASSERT_EQ(err, -EINVAL, "bpf_link_create")) + goto out_close; + + /* read perf buffer */ + err = perf_buffer__poll(pb, 100); + if (!ASSERT_GT(err, -1, "perf_buffer__poll")) + goto out_close; + + ASSERT_STRNEQ((const char *) errmsg.msg, tgt_errmsg, + 42 /* strlen(tgt_errmsg) */, "check error message"); + +out_close: + perf_buffer__free(pb); + bpf_object__close(obj); + test_xdp_attach_fail__destroy(skel); +} + void serial_test_xdp_attach(void) { if (test__start_subtest("xdp_attach")) test_xdp_attach("./test_xdp.bpf.o"); if (test__start_subtest("xdp_attach_dynptr")) test_xdp_attach("./test_xdp_dynptr.bpf.o"); + if (test__start_subtest("xdp_attach_failed")) + test_xdp_attach_fail("./xdp_dummy.bpf.o"); } diff --git a/tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c b/tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c new file mode 100644 index 0000000000000..d7149bbd95f75 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright Leon Hwang */ + +#include +#include + +#define ERRMSG_LEN 64 + +struct xdp_errmsg { + char msg[ERRMSG_LEN]; +}; + +struct { + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); + __type(key, int); + __type(value, int); +} xdp_errmsg_pb SEC(".maps"); + +struct xdp_attach_error_ctx { + unsigned long unused; + + /* + * bpf does not support tracepoint __data_loc directly. + * + * Actually, this field is a 32 bit integer whose value encodes + * information on where to find the actual data. The first 2 bytes is + * the size of the data. The last 2 bytes is the offset from the start + * of the tracepoint struct where the data begins. + * -- https://github.com/iovisor/bpftrace/pull/1542 + */ + __u32 msg; // __data_loc char[] msg; +}; + +/* + * Catch the error message at the tracepoint. + */ + +SEC("tp/xdp/bpf_xdp_link_attach_failed") +int tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx *ctx) +{ + struct xdp_errmsg errmsg; + char *msg = (void *)(__u64) ((void *) ctx + (__u16) ctx->msg); + + bpf_probe_read_kernel_str(&errmsg.msg, ERRMSG_LEN, msg); + bpf_perf_event_output(ctx, &xdp_errmsg_pb, BPF_F_CURRENT_CPU, &errmsg, + ERRMSG_LEN); + return 0; +} + +/* + * Reuse the XDP program in xdp_dummy.c. + */ + +char LICENSE[] SEC("license") = "GPL";