From patchwork Wed Sep 9 15:11:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Olsa X-Patchwork-Id: 1360711 X-Patchwork-Delegate: bpf@iogearbox.net 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=kernel.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4Bmmbb119Yz9sV5 for ; Thu, 10 Sep 2020 01:46:51 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730336AbgIIPqi convert rfc822-to-8bit (ORCPT ); Wed, 9 Sep 2020 11:46:38 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:49372 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730462AbgIIPqS (ORCPT ); Wed, 9 Sep 2020 11:46:18 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-574-GlHbXRhlPymod5mQwk-Pig-1; Wed, 09 Sep 2020 11:11:26 -0400 X-MC-Unique: GlHbXRhlPymod5mQwk-Pig-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D6D84801AE8; Wed, 9 Sep 2020 15:11:24 +0000 (UTC) Received: from krava.redhat.com (unknown [10.40.194.81]) by smtp.corp.redhat.com (Postfix) with ESMTP id 57AA9100238E; Wed, 9 Sep 2020 15:11:16 +0000 (UTC) From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann Cc: Eelco Chaudron , netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , Jesper Dangaard Brouer , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= Subject: [PATCH bpf-next 1/2] bpf: Fix context type resolving for extension programs Date: Wed, 9 Sep 2020 17:11:14 +0200 Message-Id: <20200909151115.1559418-1-jolsa@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0.0 X-Mimecast-Originator: kernel.org Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Eelco reported we can't properly access arguments if the tracing program is attached to extension program. Having following program: SEC("classifier/test_pkt_md_access") int test_pkt_md_access(struct __sk_buff *skb) with its extension: SEC("freplace/test_pkt_md_access") int test_pkt_md_access_new(struct __sk_buff *skb) and tracing that extension with: SEC("fentry/test_pkt_md_access_new") int BPF_PROG(fentry, struct sk_buff *skb) It's not possible to access skb argument in the fentry program, with following error from verifier: ; int BPF_PROG(fentry, struct sk_buff *skb) 0: (79) r1 = *(u64 *)(r1 +0) invalid bpf_context access off=0 size=8 The problem is that btf_ctx_access gets the context type for the traced program, which is in this case the extension. But when we trace extension program, we want to get the context type of the program that the extension is attached to, so we can access the argument properly in the trace program. Reported-by: Eelco Chaudron Signed-off-by: Jiri Olsa --- kernel/bpf/btf.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index f9ac6935ab3c..37ad01c32e5a 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3859,6 +3859,14 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, } info->reg_type = PTR_TO_BTF_ID; + + /* When we trace extension program, we want to get the context + * type of the program that the extension is attached to, so + * we can access the argument properly in the trace program. + */ + if (tgt_prog && tgt_prog->type == BPF_PROG_TYPE_EXT) + tgt_prog = tgt_prog->aux->linked_prog; + if (tgt_prog) { ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type, arg); if (ret > 0) { From patchwork Wed Sep 9 15:11:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Olsa X-Patchwork-Id: 1360707 X-Patchwork-Delegate: bpf@iogearbox.net 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=kernel.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BmmL00B3Vz9sTg for ; Thu, 10 Sep 2020 01:35:03 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730251AbgIIPfC convert rfc822-to-8bit (ORCPT ); Wed, 9 Sep 2020 11:35:02 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:31454 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730260AbgIIPaj (ORCPT ); Wed, 9 Sep 2020 11:30:39 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-212-uRGpX_6oPUKM0wPn-n4Dng-1; Wed, 09 Sep 2020 11:11:30 -0400 X-MC-Unique: uRGpX_6oPUKM0wPn-n4Dng-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A239714996; Wed, 9 Sep 2020 15:11:28 +0000 (UTC) Received: from krava.redhat.com (unknown [10.40.194.81]) by smtp.corp.redhat.com (Postfix) with ESMTP id 39C2B1002D41; Wed, 9 Sep 2020 15:11:25 +0000 (UTC) From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , Jesper Dangaard Brouer , Eelco Chaudron , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rg?= =?utf-8?q?ensen?= Subject: [PATCH bpf-next 2/2] selftests/bpf: Adding test for arg dereference in extension trace Date: Wed, 9 Sep 2020 17:11:15 +0200 Message-Id: <20200909151115.1559418-2-jolsa@kernel.org> In-Reply-To: <20200909151115.1559418-1-jolsa@kernel.org> References: <20200909151115.1559418-1-jolsa@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jolsa@kernel.org X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: kernel.org Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Adding test that setup following program: SEC("classifier/test_pkt_md_access") int test_pkt_md_access(struct __sk_buff *skb) with its extension: SEC("freplace/test_pkt_md_access") int test_pkt_md_access_new(struct __sk_buff *skb) and tracing that extension with: SEC("fentry/test_pkt_md_access_new") int BPF_PROG(fentry, struct sk_buff *skb) The test verifies that the tracing program can dereference skb argument properly. Signed-off-by: Jiri Olsa --- .../selftests/bpf/prog_tests/trace_ext.c | 93 +++++++++++++++++++ .../selftests/bpf/progs/test_trace_ext.c | 18 ++++ .../bpf/progs/test_trace_ext_tracing.c | 25 +++++ 3 files changed, 136 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_ext.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 diff --git a/tools/testing/selftests/bpf/prog_tests/trace_ext.c b/tools/testing/selftests/bpf/prog_tests/trace_ext.c new file mode 100644 index 000000000000..1089dafb4653 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/trace_ext.c @@ -0,0 +1,93 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include +#include +#include +#include +#include + +#include "test_trace_ext.skel.h" +#include "test_trace_ext_tracing.skel.h" + +static __u32 duration; + +void test_trace_ext(void) +{ + struct test_trace_ext_tracing *skel_trace = NULL; + struct test_trace_ext_tracing__bss *bss_trace; + const char *file = "./test_pkt_md_access.o"; + struct test_trace_ext *skel_ext = NULL; + struct test_trace_ext__bss *bss_ext; + int err, prog_fd, ext_fd; + struct bpf_object *obj; + char buf[100]; + __u32 retval; + __u64 len; + + err = bpf_prog_load(file, BPF_PROG_TYPE_SCHED_CLS, &obj, &prog_fd); + if (CHECK_FAIL(err)) + return; + + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, + .attach_prog_fd = prog_fd, + ); + + skel_ext = test_trace_ext__open_opts(&opts); + if (CHECK(!skel_ext, "setup", "freplace/test_pkt_md_access open failed\n")) + goto cleanup; + + err = test_trace_ext__load(skel_ext); + if (CHECK(err, "setup", "freplace/test_pkt_md_access load failed\n")) { + libbpf_strerror(err, buf, sizeof(buf)); + fprintf(stderr, "%s\n", buf); + goto cleanup; + } + + err = test_trace_ext__attach(skel_ext); + if (CHECK(err, "setup", "freplace/test_pkt_md_access attach failed: %d\n", err)) + goto cleanup; + + ext_fd = bpf_program__fd(skel_ext->progs.test_pkt_md_access_new); + + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts_trace, + .attach_prog_fd = ext_fd, + ); + + skel_trace = test_trace_ext_tracing__open_opts(&opts_trace); + if (CHECK(!skel_trace, "setup", "tracing/test_pkt_md_access_new open failed\n")) + goto cleanup; + + err = test_trace_ext_tracing__load(skel_trace); + if (CHECK(err, "setup", "tracing/test_pkt_md_access_new load failed\n")) { + libbpf_strerror(err, buf, sizeof(buf)); + fprintf(stderr, "%s\n", buf); + goto cleanup; + } + + err = test_trace_ext_tracing__attach(skel_trace); + if (CHECK(err, "setup", "tracing/test_pkt_md_access_new attach failed: %d\n", err)) + goto cleanup; + + err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4), + NULL, NULL, &retval, &duration); + CHECK(err || retval, "", + "err %d errno %d retval %d duration %d\n", + err, errno, retval, duration); + + bss_ext = skel_ext->bss; + bss_trace = skel_trace->bss; + + len = bss_ext->ext_called; + + CHECK(bss_ext->ext_called == 0, + "check", "failed to trigger freplace/test_pkt_md_access\n"); + CHECK(bss_trace->fentry_called != len, + "check", "failed to trigger fentry/test_pkt_md_access_new\n"); + CHECK(bss_trace->fexit_called != len, + "check", "failed to trigger fexit/test_pkt_md_access_new\n"); + +cleanup: + test_trace_ext__destroy(skel_ext); + bpf_object__close(obj); +} diff --git a/tools/testing/selftests/bpf/progs/test_trace_ext.c b/tools/testing/selftests/bpf/progs/test_trace_ext.c new file mode 100644 index 000000000000..a6318f6b52ee --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_trace_ext.c @@ -0,0 +1,18 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2019 Facebook +#include +#include +#include +#include +#include + +volatile __u64 ext_called = 0; + +SEC("freplace/test_pkt_md_access") +int test_pkt_md_access_new(struct __sk_buff *skb) +{ + ext_called = skb->len; + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/test_trace_ext_tracing.c b/tools/testing/selftests/bpf/progs/test_trace_ext_tracing.c new file mode 100644 index 000000000000..9e52a831446f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_trace_ext_tracing.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "vmlinux.h" +#include +#include + +volatile __u64 fentry_called = 0; + +SEC("fentry/test_pkt_md_access_new") +int BPF_PROG(fentry, struct sk_buff *skb) +{ + fentry_called = skb->len; + return 0; +} + +volatile __u64 fexit_called = 0; + +SEC("fexit/test_pkt_md_access_new") +int BPF_PROG(fexit, struct sk_buff *skb) +{ + fexit_called = skb->len; + return 0; +} + +char _license[] SEC("license") = "GPL";