[PATCH bpf-next v4 02/16] selftests/bpf: Bind an exclusive map through a continuous fd_array

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

Load the exclusive program of map_excl with the map in a continuous
fd_array rather than through its insns alone, which has to work, and
the other program the same way, which has to be refused. The two
programs used to be identical and so shared a digest; give the second
one a value of its own so that the kernel can tell them apart.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 .../selftests/bpf/prog_tests/map_excl.c       | 37 +++++++++++++++++++
 tools/testing/selftests/bpf/progs/map_excl.c  |  3 +-
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/map_excl.c b/tools/testing/selftests/bpf/prog_tests/map_excl.c
index 3f4422b9ffa6..9ff4cd3de2ec 100644
--- a/tools/testing/selftests/bpf/prog_tests/map_excl.c
+++ b/tools/testing/selftests/bpf/prog_tests/map_excl.c
@@ -161,12 +161,49 @@ static void test_map_excl_create_validation(void)
 	ASSERT_EQ(fd, -EINVAL, "reject size with NULL hash pointer");
 }
 
+/*
+ * The exclusive map bound through a continuous fd_array rather than by an
+ * insn. The kernel resolves the array before it verifies the program, so it
+ * has to have the digest of the program at hand by then.
+ */
+static void test_map_excl_fd_array(void)
+{
+	struct map_excl *skel = map_excl__open();
+	LIBBPF_OPTS(bpf_prog_load_opts, opts);
+	int err, fd, map_fd;
+
+	if (!ASSERT_OK_PTR(skel, "map_excl__open"))
+		return;
+	err = bpf_map__set_exclusive_program(skel->maps.excl_map, skel->progs.should_have_access);
+	if (!ASSERT_OK(err, "bpf_map__set_exclusive_program"))
+		goto out;
+
+	bpf_program__set_autoload(skel->progs.should_have_access, true);
+	bpf_program__set_autoload(skel->progs.should_not_have_access, true);
+	err = bpf_object__prepare(skel->obj);
+	if (!ASSERT_OK(err, "map_excl prepare"))
+		goto out;
+
+	map_fd = bpf_map__fd(skel->maps.excl_map);
+	opts.fd_array = &map_fd;
+	opts.fd_array_cnt = 1;
+	fd = bpf_program__clone(skel->progs.should_have_access, &opts);
+	if (ASSERT_GE(fd, 0, "exclusive program with the map in fd_array"))
+		close(fd);
+	fd = bpf_program__clone(skel->progs.should_not_have_access, &opts);
+	ASSERT_EQ(fd, -EACCES, "other program with the map in fd_array");
+out:
+	map_excl__destroy(skel);
+}
+
 void test_map_excl(void)
 {
 	if (test__start_subtest("map_excl_allowed"))
 		test_map_excl_allowed();
 	if (test__start_subtest("map_excl_denied"))
 		test_map_excl_denied();
+	if (test__start_subtest("map_excl_fd_array"))
+		test_map_excl_fd_array();
 	if (test__start_subtest("map_excl_no_map_in_map"))
 		test_map_excl_no_map_in_map();
 	if (test__start_subtest("map_excl_no_map_iter"))
diff --git a/tools/testing/selftests/bpf/progs/map_excl.c b/tools/testing/selftests/bpf/progs/map_excl.c
index d461684728e4..90f127073dff 100644
--- a/tools/testing/selftests/bpf/progs/map_excl.c
+++ b/tools/testing/selftests/bpf/progs/map_excl.c
@@ -27,7 +27,8 @@ int should_have_access(void *ctx)
 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
 int should_not_have_access(void *ctx)
 {
-	int key = 0, value = 0xdeadbeef;
+	/* a different value, so that the two programs do not share a digest */
+	int key = 0, value = 0xbaadf00d;
 
 	bpf_map_update_elem(&excl_map, &key, &value, 0);
 	return 0;
-- 
2.53.0-Meta