selftests/bpf: Add additional tests for bpf_lookup_*_key()

Add a test to ensure that bpf_lookup_user_key() creates a referenced
special keyring when the KEY_LOOKUP_CREATE flag is passed to this function.

Ensure that the kfunc rejects invalid flags.

Ensure that a keyring can be obtained from bpf_lookup_system_key() when one
of the pre-determined keyring IDs is provided.

The test is currently blacklisted for s390x (JIT does not support calling
kernel function).

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Link: https://lore.kernel.org/r/20220920075951.929132-12-roberto.sassu@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 112 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/lookup_key.c b/tools/testing/selftests/bpf/prog_tests/lookup_key.c
new file mode 100644
index 000000000000..68025e88f352
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/lookup_key.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ */
+
+#include <linux/keyctl.h>
+#include <test_progs.h>
+
+#include "test_lookup_key.skel.h"
+
+#define KEY_LOOKUP_CREATE	0x01
+#define KEY_LOOKUP_PARTIAL	0x02
+
+static bool kfunc_not_supported;
+
+static int libbpf_print_cb(enum libbpf_print_level level, const char *fmt,
+			   va_list args)
+{
+	char *func;
+
+	if (strcmp(fmt, "libbpf: extern (func ksym) '%s': not found in kernel or module BTFs\n"))
+		return 0;
+
+	func = va_arg(args, char *);
+
+	if (strcmp(func, "bpf_lookup_user_key") && strcmp(func, "bpf_key_put") &&
+	    strcmp(func, "bpf_lookup_system_key"))
+		return 0;
+
+	kfunc_not_supported = true;
+	return 0;
+}
+
+void test_lookup_key(void)
+{
+	libbpf_print_fn_t old_print_cb;
+	struct test_lookup_key *skel;
+	__u32 next_id;
+	int ret;
+
+	skel = test_lookup_key__open();
+	if (!ASSERT_OK_PTR(skel, "test_lookup_key__open"))
+		return;
+
+	old_print_cb = libbpf_set_print(libbpf_print_cb);
+	ret = test_lookup_key__load(skel);
+	libbpf_set_print(old_print_cb);
+
+	if (ret < 0 && kfunc_not_supported) {
+		printf("%s:SKIP:bpf_lookup_*_key(), bpf_key_put() kfuncs not supported\n",
+		       __func__);
+		test__skip();
+		goto close_prog;
+	}
+
+	if (!ASSERT_OK(ret, "test_lookup_key__load"))
+		goto close_prog;
+
+	ret = test_lookup_key__attach(skel);
+	if (!ASSERT_OK(ret, "test_lookup_key__attach"))
+		goto close_prog;
+
+	skel->bss->monitored_pid = getpid();
+	skel->bss->key_serial = KEY_SPEC_THREAD_KEYRING;
+
+	/* The thread-specific keyring does not exist, this test fails. */
+	skel->bss->flags = 0;
+
+	ret = bpf_prog_get_next_id(0, &next_id);
+	if (!ASSERT_LT(ret, 0, "bpf_prog_get_next_id"))
+		goto close_prog;
+
+	/* Force creation of the thread-specific keyring, this test succeeds. */
+	skel->bss->flags = KEY_LOOKUP_CREATE;
+
+	ret = bpf_prog_get_next_id(0, &next_id);
+	if (!ASSERT_OK(ret, "bpf_prog_get_next_id"))
+		goto close_prog;
+
+	/* Pass both lookup flags for parameter validation. */
+	skel->bss->flags = KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL;
+
+	ret = bpf_prog_get_next_id(0, &next_id);
+	if (!ASSERT_OK(ret, "bpf_prog_get_next_id"))
+		goto close_prog;
+
+	/* Pass invalid flags. */
+	skel->bss->flags = UINT64_MAX;
+
+	ret = bpf_prog_get_next_id(0, &next_id);
+	if (!ASSERT_LT(ret, 0, "bpf_prog_get_next_id"))
+		goto close_prog;
+
+	skel->bss->key_serial = 0;
+	skel->bss->key_id = 1;
+
+	ret = bpf_prog_get_next_id(0, &next_id);
+	if (!ASSERT_OK(ret, "bpf_prog_get_next_id"))
+		goto close_prog;
+
+	skel->bss->key_id = UINT32_MAX;
+
+	ret = bpf_prog_get_next_id(0, &next_id);
+	ASSERT_LT(ret, 0, "bpf_prog_get_next_id");
+
+close_prog:
+	skel->bss->monitored_pid = 0;
+	test_lookup_key__destroy(skel);
+}