[PATCH bpf-next 8/9] selftests/bpf: Verify iter link_create logs

[Leon Hwang <leon.hwang@linux.dev>]

Check the error code, log message, and reported log size for invalid target
FDs, flags, and iterator information. Also cover attaching a sleepable
program to an iterator that does not support it.

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
 .../selftests/bpf/prog_tests/iter_link.c      | 132 ++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/iter_link.c

diff --git a/tools/testing/selftests/bpf/prog_tests/iter_link.c b/tools/testing/selftests/bpf/prog_tests/iter_link.c
new file mode 100644
index 000000000000..c684a109091a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/iter_link.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include "bpf_iter_bpf_map.skel.h"
+
+static void test_iter_link_create_log(int target_fd, struct bpf_link_create_opts *opts,
+				      __u64 flags, int err_exp, const char *msg)
+{
+	struct bpf_iter_bpf_map *skel;
+	char log_buf[128] = {};
+	int err, fd, prog_fd;
+	LIBBPF_OPTS(bpf_log_opts, log_opts,
+		.buf = log_buf,
+		.size = sizeof(log_buf),
+		.level = 1,
+	);
+
+	skel = bpf_iter_bpf_map__open();
+	if (!ASSERT_OK_PTR(skel, "bpf_iter_bpf_map__open"))
+		return;
+
+	err = bpf_program__set_flags(skel->progs.dump_bpf_map, flags);
+	if (!ASSERT_OK(err, "bpf_program__set_flags"))
+		goto out;
+
+	err = bpf_iter_bpf_map__load(skel);
+	if (!ASSERT_OK(err, "bpf_iter_bpf_map__load"))
+		goto out;
+
+	opts->log_opts = &log_opts;
+	prog_fd = bpf_program__fd(skel->progs.dump_bpf_map);
+	fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER, opts);
+	if (!ASSERT_LT(fd, 0, "bpf_link_create")) {
+		close(fd);
+		goto out;
+	}
+
+	ASSERT_EQ(fd, err_exp, "err");
+	ASSERT_STREQ(log_buf, msg, "log_buf");
+	ASSERT_EQ(log_opts.true_size, strlen(msg) + 1, "log_size");
+
+out:
+	bpf_iter_bpf_map__destroy(skel);
+}
+
+static void test_log_invalid_target_fd(void)
+{
+	const char *msg = "Invalid target_fd.\n";
+	LIBBPF_OPTS(bpf_link_create_opts, opts);
+
+	test_iter_link_create_log(-1, &opts, 0, -EINVAL, msg);
+}
+
+static void test_log_invalid_flags(void)
+{
+	const char *msg = "Invalid flags.\n";
+	LIBBPF_OPTS(bpf_link_create_opts, opts,
+		    .flags = 1,
+	);
+
+	test_iter_link_create_log(0, &opts, 0, -EINVAL, msg);
+}
+
+static void test_log_iter_info_only(void)
+{
+	const char *msg = "iter_info and iter_info_len must be both set or both unset.\n";
+	union bpf_iter_link_info info = {};
+	LIBBPF_OPTS(bpf_link_create_opts, opts,
+		    .iter.info = &info,
+	);
+
+	test_iter_link_create_log(0, &opts, 0, -EINVAL, msg);
+}
+
+static void test_log_iter_info_len_only(void)
+{
+	const char *msg = "iter_info and iter_info_len must be both set or both unset.\n";
+	LIBBPF_OPTS(bpf_link_create_opts, opts,
+		    .iter.len = sizeof(union bpf_iter_link_info),
+	);
+
+	test_iter_link_create_log(0, &opts, 0, -EINVAL, msg);
+}
+
+static void test_log_invalid_iter_info(void)
+{
+	unsigned char info[sizeof(union bpf_iter_link_info) + 1] = {};
+	const char *msg = "Invalid iter_info.\n";
+	LIBBPF_OPTS(bpf_link_create_opts, opts,
+		    .iter.info = (union bpf_iter_link_info *)info,
+		    .iter.len = sizeof(info),
+	);
+
+	info[sizeof(info) - 1] = 1;
+	test_iter_link_create_log(0, &opts, 0, -E2BIG, msg);
+}
+
+static void test_log_invalid_iter_info_len(void)
+{
+	const char *msg = "Invalid iter_info_len.\n";
+	LIBBPF_OPTS(bpf_link_create_opts, opts,
+		    .iter.info = (union bpf_iter_link_info *)1,
+		    .iter.len = sizeof(union bpf_iter_link_info),
+	);
+
+	test_iter_link_create_log(0, &opts, 0, -EFAULT, msg);
+}
+
+static void test_log_invalid_prog(void)
+{
+	const char *msg = "The iter target does not support the bpf prog.\n";
+	LIBBPF_OPTS(bpf_link_create_opts, opts);
+
+	test_iter_link_create_log(0, &opts, BPF_F_SLEEPABLE, -EINVAL, msg);
+}
+
+void test_iter_link_log(void)
+{
+	if (test__start_subtest("invalid_target_fd"))
+		test_log_invalid_target_fd();
+	if (test__start_subtest("invalid_flags"))
+		test_log_invalid_flags();
+	if (test__start_subtest("iter_info_only"))
+		test_log_iter_info_only();
+	if (test__start_subtest("iter_info_len_only"))
+		test_log_iter_info_len_only();
+	if (test__start_subtest("invalid_iter_info"))
+		test_log_invalid_iter_info();
+	if (test__start_subtest("invalid_iter_info_len"))
+		test_log_invalid_iter_info_len();
+	if (test__start_subtest("invalid_prog"))
+		test_log_invalid_prog();
+}
-- 
2.55.0