Merge branch 'Support storing struct cgroup * objects as kptrs'

David Vernet says:

====================

In [0], we added support for storing struct task_struct * objects as
kptrs. This patch set extends this effort to also include storing struct
cgroup * object as kptrs.

As with tasks, there are many possible use cases for storing cgroups in
maps. During tracing, for example, it could be useful to query cgroup
statistics such as PSI averages, or tracking which tasks are migrating
to and from the cgroup.

[0]: https://lore.kernel.org/all/20221120051004.3605026-1-void@manifault.com/
====================

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

5 files changed, 678 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x
index 12cf2159975e..b9a3d80204c6 100644
--- a/tools/testing/selftests/bpf/DENYLIST.s390x
+++ b/tools/testing/selftests/bpf/DENYLIST.s390x
@@ -10,6 +10,7 @@ bpf_nf                                   # JIT does not support calling kernel f
 bpf_tcp_ca                               # JIT does not support calling kernel function                                (kfunc)
 cb_refs                                  # expected error message unexpected error: -524                               (trampoline)
 cgroup_hierarchical_stats                # JIT does not support calling kernel function                                (kfunc)
+cgrp_kfunc                               # JIT does not support calling kernel function
 cgrp_local_storage                       # prog_attach unexpected error: -524                                          (trampoline)
 core_read_macros                         # unknown func bpf_probe_read#4                                               (overlapping)
 d_path                                   # failed to auto-attach program 'prog_stat': -524                             (trampoline)
diff --git a/tools/testing/selftests/bpf/prog_tests/cgrp_kfunc.c b/tools/testing/selftests/bpf/prog_tests/cgrp_kfunc.c
new file mode 100644
index 000000000000..973f0c5af965
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/cgrp_kfunc.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#define _GNU_SOURCE
+#include <cgroup_helpers.h>
+#include <test_progs.h>
+
+#include "cgrp_kfunc_failure.skel.h"
+#include "cgrp_kfunc_success.skel.h"
+
+static size_t log_buf_sz = 1 << 20; /* 1 MB */
+static char obj_log_buf[1048576];
+
+static struct cgrp_kfunc_success *open_load_cgrp_kfunc_skel(void)
+{
+	struct cgrp_kfunc_success *skel;
+	int err;
+
+	skel = cgrp_kfunc_success__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return NULL;
+
+	skel->bss->pid = getpid();
+
+	err = cgrp_kfunc_success__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	return skel;
+
+cleanup:
+	cgrp_kfunc_success__destroy(skel);
+	return NULL;
+}
+
+static int mkdir_rm_test_dir(void)
+{
+	int fd;
+	const char *cgrp_path = "cgrp_kfunc";
+
+	fd = create_and_get_cgroup(cgrp_path);
+	if (!ASSERT_GT(fd, 0, "mkdir_cgrp_fd"))
+		return -1;
+
+	close(fd);
+	remove_cgroup(cgrp_path);
+
+	return 0;
+}
+
+static void run_success_test(const char *prog_name)
+{
+	struct cgrp_kfunc_success *skel;
+	struct bpf_program *prog;
+	struct bpf_link *link = NULL;
+
+	skel = open_load_cgrp_kfunc_skel();
+	if (!ASSERT_OK_PTR(skel, "open_load_skel"))
+		return;
+
+	if (!ASSERT_OK(skel->bss->err, "pre_mkdir_err"))
+		goto cleanup;
+
+	prog = bpf_object__find_program_by_name(skel->obj, prog_name);
+	if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+		goto cleanup;
+
+	link = bpf_program__attach(prog);
+	if (!ASSERT_OK_PTR(link, "attached_link"))
+		goto cleanup;
+
+	ASSERT_EQ(skel->bss->invocations, 0, "pre_rmdir_count");
+	if (!ASSERT_OK(mkdir_rm_test_dir(), "cgrp_mkdir"))
+		goto cleanup;
+
+	ASSERT_EQ(skel->bss->invocations, 1, "post_rmdir_count");
+	ASSERT_OK(skel->bss->err, "post_rmdir_err");
+
+cleanup:
+	bpf_link__destroy(link);
+	cgrp_kfunc_success__destroy(skel);
+}
+
+static const char * const success_tests[] = {
+	"test_cgrp_acquire_release_argument",
+	"test_cgrp_acquire_leave_in_map",
+	"test_cgrp_xchg_release",
+	"test_cgrp_get_release",
+	"test_cgrp_get_ancestors",
+};
+
+static struct {
+	const char *prog_name;
+	const char *expected_err_msg;
+} failure_tests[] = {
+	{"cgrp_kfunc_acquire_untrusted", "R1 must be referenced or trusted"},
+	{"cgrp_kfunc_acquire_fp", "arg#0 pointer type STRUCT cgroup must point"},
+	{"cgrp_kfunc_acquire_unsafe_kretprobe", "reg type unsupported for arg#0 function"},
+	{"cgrp_kfunc_acquire_trusted_walked", "R1 must be referenced or trusted"},
+	{"cgrp_kfunc_acquire_null", "arg#0 pointer type STRUCT cgroup must point"},
+	{"cgrp_kfunc_acquire_unreleased", "Unreleased reference"},
+	{"cgrp_kfunc_get_non_kptr_param", "arg#0 expected pointer to map value"},
+	{"cgrp_kfunc_get_non_kptr_acquired", "arg#0 expected pointer to map value"},
+	{"cgrp_kfunc_get_null", "arg#0 expected pointer to map value"},
+	{"cgrp_kfunc_xchg_unreleased", "Unreleased reference"},
+	{"cgrp_kfunc_get_unreleased", "Unreleased reference"},
+	{"cgrp_kfunc_release_untrusted", "arg#0 is untrusted_ptr_or_null_ expected ptr_ or socket"},
+	{"cgrp_kfunc_release_fp", "arg#0 pointer type STRUCT cgroup must point"},
+	{"cgrp_kfunc_release_null", "arg#0 is ptr_or_null_ expected ptr_ or socket"},
+	{"cgrp_kfunc_release_unacquired", "release kernel function bpf_cgroup_release expects"},
+};
+
+static void verify_fail(const char *prog_name, const char *expected_err_msg)
+{
+	LIBBPF_OPTS(bpf_object_open_opts, opts);
+	struct cgrp_kfunc_failure *skel;
+	int err, i;
+
+	opts.kernel_log_buf = obj_log_buf;
+	opts.kernel_log_size = log_buf_sz;
+	opts.kernel_log_level = 1;
+
+	skel = cgrp_kfunc_failure__open_opts(&opts);
+	if (!ASSERT_OK_PTR(skel, "cgrp_kfunc_failure__open_opts"))
+		goto cleanup;
+
+	for (i = 0; i < ARRAY_SIZE(failure_tests); i++) {
+		struct bpf_program *prog;
+		const char *curr_name = failure_tests[i].prog_name;
+
+		prog = bpf_object__find_program_by_name(skel->obj, curr_name);
+		if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+			goto cleanup;
+
+		bpf_program__set_autoload(prog, !strcmp(curr_name, prog_name));
+	}
+
+	err = cgrp_kfunc_failure__load(skel);
+	if (!ASSERT_ERR(err, "unexpected load success"))
+		goto cleanup;
+
+	if (!ASSERT_OK_PTR(strstr(obj_log_buf, expected_err_msg), "expected_err_msg")) {
+		fprintf(stderr, "Expected err_msg: %s\n", expected_err_msg);
+		fprintf(stderr, "Verifier output: %s\n", obj_log_buf);
+	}
+
+cleanup:
+	cgrp_kfunc_failure__destroy(skel);
+}
+
+void test_cgrp_kfunc(void)
+{
+	int i, err;
+
+	err = setup_cgroup_environment();
+	if (!ASSERT_OK(err, "cgrp_env_setup"))
+		goto cleanup;
+
+	for (i = 0; i < ARRAY_SIZE(success_tests); i++) {
+		if (!test__start_subtest(success_tests[i]))
+			continue;
+
+		run_success_test(success_tests[i]);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(failure_tests); i++) {
+		if (!test__start_subtest(failure_tests[i].prog_name))
+			continue;
+
+		verify_fail(failure_tests[i].prog_name, failure_tests[i].expected_err_msg);
+	}
+
+cleanup:
+	cleanup_cgroup_environment();
+}
diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h
new file mode 100644
index 000000000000..7d30855bfe78
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#ifndef _CGRP_KFUNC_COMMON_H
+#define _CGRP_KFUNC_COMMON_H
+
+#include <errno.h>
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct __cgrps_kfunc_map_value {
+	struct cgroup __kptr_ref * cgrp;
+};
+
+struct hash_map {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, int);
+	__type(value, struct __cgrps_kfunc_map_value);
+	__uint(max_entries, 1);
+} __cgrps_kfunc_map SEC(".maps");
+
+struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
+struct cgroup *bpf_cgroup_kptr_get(struct cgroup **pp) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;
+
+static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp)
+{
+	s32 id;
+	long status;
+
+	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
+	if (status)
+		return NULL;
+
+	return bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
+}
+
+static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp)
+{
+	struct __cgrps_kfunc_map_value local, *v;
+	long status;
+	struct cgroup *acquired, *old;
+	s32 id;
+
+	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
+	if (status)
+		return status;
+
+	local.cgrp = NULL;
+	status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
+	if (status)
+		return status;
+
+	v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
+	if (!v) {
+		bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
+		return -ENOENT;
+	}
+
+	acquired = bpf_cgroup_acquire(cgrp);
+	old = bpf_kptr_xchg(&v->cgrp, acquired);
+	if (old) {
+		bpf_cgroup_release(old);
+		return -EEXIST;
+	}
+
+	return 0;
+}
+
+#endif /* _CGRP_KFUNC_COMMON_H */
diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c
new file mode 100644
index 000000000000..a1369b5ebcf8
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+#include "cgrp_kfunc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+/* Prototype for all of the program trace events below:
+ *
+ * TRACE_EVENT(cgroup_mkdir,
+ *         TP_PROTO(struct cgroup *cgrp, const char *path),
+ *         TP_ARGS(cgrp, path)
+ */
+
+static struct __cgrps_kfunc_map_value *insert_lookup_cgrp(struct cgroup *cgrp)
+{
+	int status;
+
+	status = cgrps_kfunc_map_insert(cgrp);
+	if (status)
+		return NULL;
+
+	return cgrps_kfunc_map_value_lookup(cgrp);
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_acquire_untrusted, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *acquired;
+	struct __cgrps_kfunc_map_value *v;
+
+	v = insert_lookup_cgrp(cgrp);
+	if (!v)
+		return 0;
+
+	/* Can't invoke bpf_cgroup_acquire() on an untrusted pointer. */
+	acquired = bpf_cgroup_acquire(v->cgrp);
+	bpf_cgroup_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_acquire_fp, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *acquired, *stack_cgrp = (struct cgroup *)&path;
+
+	/* Can't invoke bpf_cgroup_acquire() on a random frame pointer. */
+	acquired = bpf_cgroup_acquire((struct cgroup *)&stack_cgrp);
+	bpf_cgroup_release(acquired);
+
+	return 0;
+}
+
+SEC("kretprobe/cgroup_destroy_locked")
+int BPF_PROG(cgrp_kfunc_acquire_unsafe_kretprobe, struct cgroup *cgrp)
+{
+	struct cgroup *acquired;
+
+	/* Can't acquire an untrusted struct cgroup * pointer. */
+	acquired = bpf_cgroup_acquire(cgrp);
+	bpf_cgroup_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_acquire_trusted_walked, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *acquired;
+
+	/* Can't invoke bpf_cgroup_acquire() on a pointer obtained from walking a trusted cgroup. */
+	acquired = bpf_cgroup_acquire(cgrp->old_dom_cgrp);
+	bpf_cgroup_release(acquired);
+
+	return 0;
+}
+
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_acquire_null, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *acquired;
+
+	/* Can't invoke bpf_cgroup_acquire() on a NULL pointer. */
+	acquired = bpf_cgroup_acquire(NULL);
+	if (!acquired)
+		return 0;
+	bpf_cgroup_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_acquire_unreleased, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *acquired;
+
+	acquired = bpf_cgroup_acquire(cgrp);
+
+	/* Acquired cgroup is never released. */
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_get_non_kptr_param, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *kptr;
+
+	/* Cannot use bpf_cgroup_kptr_get() on a non-kptr, even on a valid cgroup. */
+	kptr = bpf_cgroup_kptr_get(&cgrp);
+	if (!kptr)
+		return 0;
+
+	bpf_cgroup_release(kptr);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_get_non_kptr_acquired, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *kptr, *acquired;
+
+	acquired = bpf_cgroup_acquire(cgrp);
+
+	/* Cannot use bpf_cgroup_kptr_get() on a non-map-value, even if the kptr was acquired. */
+	kptr = bpf_cgroup_kptr_get(&acquired);
+	bpf_cgroup_release(acquired);
+	if (!kptr)
+		return 0;
+
+	bpf_cgroup_release(kptr);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_get_null, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *kptr;
+
+	/* Cannot use bpf_cgroup_kptr_get() on a NULL pointer. */
+	kptr = bpf_cgroup_kptr_get(NULL);
+	if (!kptr)
+		return 0;
+
+	bpf_cgroup_release(kptr);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_xchg_unreleased, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *kptr;
+	struct __cgrps_kfunc_map_value *v;
+
+	v = insert_lookup_cgrp(cgrp);
+	if (!v)
+		return 0;
+
+	kptr = bpf_kptr_xchg(&v->cgrp, NULL);
+	if (!kptr)
+		return 0;
+
+	/* Kptr retrieved from map is never released. */
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_get_unreleased, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *kptr;
+	struct __cgrps_kfunc_map_value *v;
+
+	v = insert_lookup_cgrp(cgrp);
+	if (!v)
+		return 0;
+
+	kptr = bpf_cgroup_kptr_get(&v->cgrp);
+	if (!kptr)
+		return 0;
+
+	/* Kptr acquired above is never released. */
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_release_untrusted, struct cgroup *cgrp, const char *path)
+{
+	struct __cgrps_kfunc_map_value *v;
+
+	v = insert_lookup_cgrp(cgrp);
+	if (!v)
+		return 0;
+
+	/* Can't invoke bpf_cgroup_release() on an untrusted pointer. */
+	bpf_cgroup_release(v->cgrp);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_release_fp, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *acquired = (struct cgroup *)&path;
+
+	/* Cannot release random frame pointer. */
+	bpf_cgroup_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_release_null, struct cgroup *cgrp, const char *path)
+{
+	struct __cgrps_kfunc_map_value local, *v;
+	long status;
+	struct cgroup *acquired, *old;
+	s32 id;
+
+	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
+	if (status)
+		return 0;
+
+	local.cgrp = NULL;
+	status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
+	if (status)
+		return status;
+
+	v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
+	if (!v)
+		return -ENOENT;
+
+	acquired = bpf_cgroup_acquire(cgrp);
+
+	old = bpf_kptr_xchg(&v->cgrp, acquired);
+
+	/* old cannot be passed to bpf_cgroup_release() without a NULL check. */
+	bpf_cgroup_release(old);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(cgrp_kfunc_release_unacquired, struct cgroup *cgrp, const char *path)
+{
+	/* Cannot release trusted cgroup pointer which was not acquired. */
+	bpf_cgroup_release(cgrp);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c
new file mode 100644
index 000000000000..0c23ea32df9f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+#include "cgrp_kfunc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+int err, pid, invocations;
+
+/* Prototype for all of the program trace events below:
+ *
+ * TRACE_EVENT(cgroup_mkdir,
+ *         TP_PROTO(struct cgroup *cgrp, const char *path),
+ *         TP_ARGS(cgrp, path)
+ */
+
+static bool is_test_kfunc_task(void)
+{
+	int cur_pid = bpf_get_current_pid_tgid() >> 32;
+	bool same = pid == cur_pid;
+
+	if (same)
+		__sync_fetch_and_add(&invocations, 1);
+
+	return same;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(test_cgrp_acquire_release_argument, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *acquired;
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	acquired = bpf_cgroup_acquire(cgrp);
+	bpf_cgroup_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(test_cgrp_acquire_leave_in_map, struct cgroup *cgrp, const char *path)
+{
+	long status;
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	status = cgrps_kfunc_map_insert(cgrp);
+	if (status)
+		err = 1;
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(test_cgrp_xchg_release, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *kptr;
+	struct __cgrps_kfunc_map_value *v;
+	long status;
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	status = cgrps_kfunc_map_insert(cgrp);
+	if (status) {
+		err = 1;
+		return 0;
+	}
+
+	v = cgrps_kfunc_map_value_lookup(cgrp);
+	if (!v) {
+		err = 2;
+		return 0;
+	}
+
+	kptr = bpf_kptr_xchg(&v->cgrp, NULL);
+	if (!kptr) {
+		err = 3;
+		return 0;
+	}
+
+	bpf_cgroup_release(kptr);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(test_cgrp_get_release, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *kptr;
+	struct __cgrps_kfunc_map_value *v;
+	long status;
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	status = cgrps_kfunc_map_insert(cgrp);
+	if (status) {
+		err = 1;
+		return 0;
+	}
+
+	v = cgrps_kfunc_map_value_lookup(cgrp);
+	if (!v) {
+		err = 2;
+		return 0;
+	}
+
+	kptr = bpf_cgroup_kptr_get(&v->cgrp);
+	if (!kptr) {
+		err = 3;
+		return 0;
+	}
+
+	bpf_cgroup_release(kptr);
+
+	return 0;
+}
+
+SEC("tp_btf/cgroup_mkdir")
+int BPF_PROG(test_cgrp_get_ancestors, struct cgroup *cgrp, const char *path)
+{
+	struct cgroup *self, *ancestor1, *invalid;
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	self = bpf_cgroup_ancestor(cgrp, cgrp->level);
+	if (!self) {
+		err = 1;
+		return 0;
+	}
+
+	if (self->self.id != cgrp->self.id) {
+		bpf_cgroup_release(self);
+		err = 2;
+		return 0;
+	}
+	bpf_cgroup_release(self);
+
+	ancestor1 = bpf_cgroup_ancestor(cgrp, cgrp->level - 1);
+	if (!ancestor1) {
+		err = 3;
+		return 0;
+	}
+	bpf_cgroup_release(ancestor1);
+
+	invalid = bpf_cgroup_ancestor(cgrp, 10000);
+	if (invalid) {
+		bpf_cgroup_release(invalid);
+		err = 4;
+		return 0;
+	}
+
+	invalid = bpf_cgroup_ancestor(cgrp, -1);
+	if (invalid) {
+		bpf_cgroup_release(invalid);
+		err = 5;
+		return 0;
+	}
+
+	return 0;
+}