Subject: [PATCH bpf-next v3 8/8] selftests/bpf: Test load and dump metadata with btftool and skel

From: Stanislav Fomichev <[email-masked]>
Date: Fri, 28 Aug 2020 12:36:03 -0700

From: YiFei Zhu <[email-masked]>

This is a simple test to check that loading and dumping metadata
in btftool works, whether or not metadata contents are used by the
program.

A C test is also added to make sure the skeleton code can read the
metadata values, and we also check that trying to re-bind the map
causes EEXIST, so we are sure the map is already bound by libbpf
when loading skeleton.

Cc: YiFei Zhu <[email-masked]>
Signed-off-by: YiFei Zhu <[email-masked]>
Signed-off-by: Stanislav Fomichev <[email-masked]>
---
 tools/testing/selftests/bpf/Makefile          |  3 +-
 .../selftests/bpf/prog_tests/metadata.c       | 83 +++++++++++++++++++
 .../selftests/bpf/progs/metadata_unused.c     | 15 ++++
 .../selftests/bpf/progs/metadata_used.c       | 15 ++++
 .../selftests/bpf/test_bpftool_metadata.sh    | 82 ++++++++++++++++++
 5 files changed, 197 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/metadata.c
 create mode 100644 tools/testing/selftests/bpf/progs/metadata_unused.c
 create mode 100644 tools/testing/selftests/bpf/progs/metadata_used.c
 create mode 100755 tools/testing/selftests/bpf/test_bpftool_metadata.sh

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 09657d0afb5c..f7fd1503d210 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -68,7 +68,8 @@ TEST_PROGS := test_kmod.sh \
 	test_tc_edt.sh \
 	test_xdping.sh \
 	test_bpftool_build.sh \
-	test_bpftool.sh
+	test_bpftool.sh \
+	test_bpftool_metadata.sh \
 
 TEST_PROGS_EXTENDED := with_addr.sh \
 	with_tunnels.sh \
diff --git a/tools/testing/selftests/bpf/prog_tests/metadata.c b/tools/testing/selftests/bpf/prog_tests/metadata.c
new file mode 100644
index 000000000000..086a601a3f74
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/metadata.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright 2020 Google LLC.
+ */
+
+#include <test_progs.h>
+#include <cgroup_helpers.h>
+#include <network_helpers.h>
+
+#include "metadata_unused.skel.h"
+#include "metadata_used.skel.h"
+
+static int duration;
+
+static void test_metadata_unused(void)
+{
+	struct metadata_unused *obj;
+	int err;
+
+	obj = metadata_unused__open_and_load();
+	if (CHECK(!obj, "skel-load", "errno %d", errno))
+		return;
+
+	/* Assert that we can access the metadata in skel and the values are
+	 * what we expect.
+	 */
+	if (CHECK(strncmp(obj->metadata->metadata_a, "foo",
+			  sizeof(obj->metadata->metadata_a)),
+		  "metadata_a", "expected \"foo\", value differ"))
+		goto close_bpf_object;
+	if (CHECK(obj->metadata->metadata_b != 1, "metadata_b",
+		  "expected 1, got %d", obj->metadata->metadata_b))
+		goto close_bpf_object;
+
+	/* Assert that binding metadata map to prog again results in EEXIST. */
+	err = bpf_prog_bind_map(bpf_program__fd(obj->progs.prog),
+				bpf_map__fd(obj->maps.metadata), NULL);
+	CHECK(!err || errno != EEXIST, "rebind_map",
+	      "errno %d, expected EEXIST", errno);
+
+close_bpf_object:
+	metadata_unused__destroy(obj);
+}
+
+static void test_metadata_used(void)
+{
+	struct metadata_used *obj;
+	int err;
+
+	obj = metadata_used__open_and_load();
+	if (CHECK(!obj, "skel-load", "errno %d", errno))
+		return;
+
+	/* Assert that we can access the metadata in skel and the values are
+	 * what we expect.
+	 */
+	if (CHECK(strncmp(obj->metadata->metadata_a, "bar",
+			  sizeof(obj->metadata->metadata_a)),
+		  "metadata_a", "expected \"bar\", value differ"))
+		goto close_bpf_object;
+	if (CHECK(obj->metadata->metadata_b != 2, "metadata_b",
+		  "expected 2, got %d", obj->metadata->metadata_b))
+		goto close_bpf_object;
+
+	/* Assert that binding metadata map to prog again results in EEXIST. */
+	err = bpf_prog_bind_map(bpf_program__fd(obj->progs.prog),
+				bpf_map__fd(obj->maps.metadata), NULL);
+	CHECK(!err || errno != EEXIST, "rebind_map",
+	      "errno %d, expected EEXIST", errno);
+
+close_bpf_object:
+	metadata_used__destroy(obj);
+}
+
+void test_metadata(void)
+{
+	if (test__start_subtest("unused"))
+		test_metadata_unused();
+
+	if (test__start_subtest("used"))
+		test_metadata_used();
+}
diff --git a/tools/testing/selftests/bpf/progs/metadata_unused.c b/tools/testing/selftests/bpf/progs/metadata_unused.c
new file mode 100644
index 000000000000..523b3c332426
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/metadata_unused.c
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+char metadata_a[] SEC(".metadata") = "foo";
+int metadata_b SEC(".metadata") = 1;
+
+SEC("cgroup_skb/egress")
+int prog(struct xdp_md *ctx)
+{
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/metadata_used.c b/tools/testing/selftests/bpf/progs/metadata_used.c
new file mode 100644
index 000000000000..59785404f7bb
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/metadata_used.c
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+char metadata_a[] SEC(".metadata") = "bar";
+int metadata_b SEC(".metadata") = 2;
+
+SEC("cgroup_skb/egress")
+int prog(struct xdp_md *ctx)
+{
+	return metadata_b ? 1 : 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_bpftool_metadata.sh b/tools/testing/selftests/bpf/test_bpftool_metadata.sh
new file mode 100755
index 000000000000..a7515c09dc2d
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_bpftool_metadata.sh
@@ -0,0 +1,82 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+TESTNAME=bpftool_metadata
+BPF_FS=$(awk '$3 == "bpf" {print $2; exit}' /proc/mounts)
+BPF_DIR=$BPF_FS/test_$TESTNAME
+
+_cleanup()
+{
+	set +e
+	rm -rf $BPF_DIR 2> /dev/null
+}
+
+cleanup_skip()
+{
+	echo "selftests: $TESTNAME [SKIP]"
+	_cleanup
+
+	exit $ksft_skip
+}
+
+cleanup()
+{
+	if [ "$?" = 0 ]; then
+		echo "selftests: $TESTNAME [PASS]"
+	else
+		echo "selftests: $TESTNAME [FAILED]"
+	fi
+	_cleanup
+}
+
+if [ $(id -u) -ne 0 ]; then
+	echo "selftests: $TESTNAME [SKIP] Need root privileges"
+	exit $ksft_skip
+fi
+
+if [ -z "$BPF_FS" ]; then
+	echo "selftests: $TESTNAME [SKIP] Could not run test without bpffs mounted"
+	exit $ksft_skip
+fi
+
+if ! bpftool version > /dev/null 2>&1; then
+	echo "selftests: $TESTNAME [SKIP] Could not run test without bpftool"
+	exit $ksft_skip
+fi
+
+set -e
+
+trap cleanup_skip EXIT
+
+mkdir $BPF_DIR
+
+trap cleanup EXIT
+
+bpftool prog load metadata_unused.o $BPF_DIR/unused
+
+METADATA_PLAIN="$(bpftool prog --metadata)"
+echo "$METADATA_PLAIN" | grep 'metadata_a = "foo"' > /dev/null
+echo "$METADATA_PLAIN" | grep 'metadata_b = 1' > /dev/null
+
+bpftool prog --metadata --json | grep '"metadata":{"metadata_a":"foo","metadata_b":1}' > /dev/null
+
+bpftool map | grep 'metada.metadata' > /dev/null
+
+rm $BPF_DIR/unused
+
+bpftool prog load metadata_used.o $BPF_DIR/used
+
+METADATA_PLAIN="$(bpftool prog --metadata)"
+echo "$METADATA_PLAIN" | grep 'metadata_a = "bar"' > /dev/null
+echo "$METADATA_PLAIN" | grep 'metadata_b = 2' > /dev/null
+
+bpftool prog --metadata --json | grep '"metadata":{"metadata_a":"bar","metadata_b":2}' > /dev/null
+
+bpftool map | grep 'metada.metadata' > /dev/null
+
+rm $BPF_DIR/used
+
+exit 0
-- 
2.28.0.402.g5ffc5be6b7-goog