selftests/bpf: Cover exclusive map create-time validation

map_excl exercises exclusive-map binding (allowed/denied), map-in-map
and map iterator rejection. It does not cover the create-time validation
of excl_prog_hash: the kernel only accepts a SHA-256-sized hash and
requires the pointer and size to be consistent.

Add map_excl_create_validation to check the rejected combinations:

  # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t map_excl
  [...]
  [    1.780305] clocksource: Switched to clocksource tsc
  #215/1   map_excl/map_excl_allowed:OK
  #215/2   map_excl/map_excl_denied:OK
  #215/3   map_excl/map_excl_no_map_in_map:OK
  #215/4   map_excl/map_excl_no_map_iter:OK
  #215/5   map_excl/map_excl_create_validation:OK
  #215     map_excl:OK
  Summary: 1/5 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260603211658.471212-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/map_excl.c b/tools/testing/selftests/bpf/prog_tests/map_excl.c
index 3088668e2e45..3f4422b9ffa6 100644
--- a/tools/testing/selftests/bpf/prog_tests/map_excl.c
+++ b/tools/testing/selftests/bpf/prog_tests/map_excl.c
@@ -126,6 +126,41 @@ out:
 	close(excl_fd);
 }
 
+static void test_map_excl_create_validation(void)
+{
+	LIBBPF_OPTS(bpf_map_create_opts, o);
+	__u8 hash[SHA256_DIGEST_SIZE] = {};
+	int fd;
+
+	o.excl_prog_hash = hash;
+	o.excl_prog_hash_size = SHA256_DIGEST_SIZE / 2;
+	fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "excl", 4, 4, 1, &o);
+	if (fd >= 0)
+		close(fd);
+	ASSERT_EQ(fd, -EINVAL, "reject short excl_prog_hash_size");
+
+	o.excl_prog_hash = hash;
+	o.excl_prog_hash_size = SHA256_DIGEST_SIZE * 2;
+	fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "excl", 4, 4, 1, &o);
+	if (fd >= 0)
+		close(fd);
+	ASSERT_EQ(fd, -EINVAL, "reject long excl_prog_hash_size");
+
+	o.excl_prog_hash = hash;
+	o.excl_prog_hash_size = 0;
+	fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "excl", 4, 4, 1, &o);
+	if (fd >= 0)
+		close(fd);
+	ASSERT_EQ(fd, -EINVAL, "reject hash pointer with zero size");
+
+	o.excl_prog_hash = NULL;
+	o.excl_prog_hash_size = SHA256_DIGEST_SIZE;
+	fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "excl", 4, 4, 1, &o);
+	if (fd >= 0)
+		close(fd);
+	ASSERT_EQ(fd, -EINVAL, "reject size with NULL hash pointer");
+}
+
 void test_map_excl(void)
 {
 	if (test__start_subtest("map_excl_allowed"))
@@ -136,4 +171,6 @@ void test_map_excl(void)
 		test_map_excl_no_map_in_map();
 	if (test__start_subtest("map_excl_no_map_iter"))
 		test_map_excl_no_map_iter();
+	if (test__start_subtest("map_excl_create_validation"))
+		test_map_excl_create_validation();
 }