selftests/bpf: Add negative C tests for kptrs

This uses the newly added SEC("?foo") naming to disable autoload of
programs, and then loads them one by one for the object and verifies
that loading fails and matches the returned error string from verifier.
This is similar to already existing verifier tests but provides coverage
for BPF C.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220511194654.765705-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 86 insertions, 1 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/map_kptr.c b/tools/testing/selftests/bpf/prog_tests/map_kptr.c
index 9e2fbda64a65..00819277cb17 100644
--- a/tools/testing/selftests/bpf/prog_tests/map_kptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/map_kptr.c
@@ -2,8 +2,86 @@
 #include <test_progs.h>
 
 #include "map_kptr.skel.h"
+#include "map_kptr_fail.skel.h"
 
-void test_map_kptr(void)
+static char log_buf[1024 * 1024];
+
+struct {
+	const char *prog_name;
+	const char *err_msg;
+} map_kptr_fail_tests[] = {
+	{ "size_not_bpf_dw", "kptr access size must be BPF_DW" },
+	{ "non_const_var_off", "kptr access cannot have variable offset" },
+	{ "non_const_var_off_kptr_xchg", "R1 doesn't have constant offset. kptr has to be" },
+	{ "misaligned_access_write", "kptr access misaligned expected=8 off=7" },
+	{ "misaligned_access_read", "kptr access misaligned expected=8 off=1" },
+	{ "reject_var_off_store", "variable untrusted_ptr_ access var_off=(0x0; 0x1e0)" },
+	{ "reject_bad_type_match", "invalid kptr access, R1 type=untrusted_ptr_prog_test_ref_kfunc" },
+	{ "marked_as_untrusted_or_null", "R1 type=untrusted_ptr_or_null_ expected=percpu_ptr_" },
+	{ "correct_btf_id_check_size", "access beyond struct prog_test_ref_kfunc at off 32 size 4" },
+	{ "inherit_untrusted_on_walk", "R1 type=untrusted_ptr_ expected=percpu_ptr_" },
+	{ "reject_kptr_xchg_on_unref", "off=8 kptr isn't referenced kptr" },
+	{ "reject_kptr_get_no_map_val", "arg#0 expected pointer to map value" },
+	{ "reject_kptr_get_no_null_map_val", "arg#0 expected pointer to map value" },
+	{ "reject_kptr_get_no_kptr", "arg#0 no referenced kptr at map value offset=0" },
+	{ "reject_kptr_get_on_unref", "arg#0 no referenced kptr at map value offset=8" },
+	{ "reject_kptr_get_bad_type_match", "kernel function bpf_kfunc_call_test_kptr_get args#0" },
+	{ "mark_ref_as_untrusted_or_null", "R1 type=untrusted_ptr_or_null_ expected=percpu_ptr_" },
+	{ "reject_untrusted_store_to_ref", "store to referenced kptr disallowed" },
+	{ "reject_bad_type_xchg", "invalid kptr access, R2 type=ptr_prog_test_ref_kfunc expected=ptr_prog_test_member" },
+	{ "reject_untrusted_xchg", "R2 type=untrusted_ptr_ expected=ptr_" },
+	{ "reject_member_of_ref_xchg", "invalid kptr access, R2 type=ptr_prog_test_ref_kfunc" },
+	{ "reject_indirect_helper_access", "kptr cannot be accessed indirectly by helper" },
+	{ "reject_indirect_global_func_access", "kptr cannot be accessed indirectly by helper" },
+	{ "kptr_xchg_ref_state", "Unreleased reference id=5 alloc_insn=" },
+	{ "kptr_get_ref_state", "Unreleased reference id=3 alloc_insn=" },
+};
+
+static void test_map_kptr_fail_prog(const char *prog_name, const char *err_msg)
+{
+	LIBBPF_OPTS(bpf_object_open_opts, opts, .kernel_log_buf = log_buf,
+						.kernel_log_size = sizeof(log_buf),
+						.kernel_log_level = 1);
+	struct map_kptr_fail *skel;
+	struct bpf_program *prog;
+	int ret;
+
+	skel = map_kptr_fail__open_opts(&opts);
+	if (!ASSERT_OK_PTR(skel, "map_kptr_fail__open_opts"))
+		return;
+
+	prog = bpf_object__find_program_by_name(skel->obj, prog_name);
+	if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+		goto end;
+
+	bpf_program__set_autoload(prog, true);
+
+	ret = map_kptr_fail__load(skel);
+	if (!ASSERT_ERR(ret, "map_kptr__load must fail"))
+		goto end;
+
+	if (!ASSERT_OK_PTR(strstr(log_buf, err_msg), "expected error message")) {
+		fprintf(stderr, "Expected: %s\n", err_msg);
+		fprintf(stderr, "Verifier: %s\n", log_buf);
+	}
+
+end:
+	map_kptr_fail__destroy(skel);
+}
+
+static void test_map_kptr_fail(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(map_kptr_fail_tests); i++) {
+		if (!test__start_subtest(map_kptr_fail_tests[i].prog_name))
+			continue;
+		test_map_kptr_fail_prog(map_kptr_fail_tests[i].prog_name,
+					map_kptr_fail_tests[i].err_msg);
+	}
+}
+
+static void test_map_kptr_success(void)
 {
 	struct map_kptr *skel;
 	int key = 0, ret;
@@ -35,3 +113,10 @@ void test_map_kptr(void)
 
 	map_kptr__destroy(skel);
 }
+
+void test_map_kptr(void)
+{
+	if (test__start_subtest("success"))
+		test_map_kptr_success();
+	test_map_kptr_fail();
+}