selftests/bpf: Some basic __uptr tests

Make sure the memory of uptrs have been mapped to the kernel properly.
Also ensure the values of uptrs in the kernel haven't been copied
to userspace.

It also has the syscall update_elem/delete_elem test to test the
pin/unpin code paths.

Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-9-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 63 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/task_ls_uptr.c b/tools/testing/selftests/bpf/progs/task_ls_uptr.c
new file mode 100644
index 000000000000..ddbe11b46eef
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/task_ls_uptr.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "uptr_test_common.h"
+
+struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct value_type);
+} datamap SEC(".maps");
+
+pid_t target_pid = 0;
+pid_t parent_pid = 0;
+
+SEC("tp_btf/sys_enter")
+int on_enter(__u64 *ctx)
+{
+	struct task_struct *task, *data_task;
+	struct value_type *ptr;
+	struct user_data *udata;
+	struct cgroup *cgrp;
+
+	task = bpf_get_current_task_btf();
+	if (task->pid != target_pid)
+		return 0;
+
+	data_task = bpf_task_from_pid(parent_pid);
+	if (!data_task)
+		return 0;
+
+	ptr = bpf_task_storage_get(&datamap, data_task, 0, 0);
+	bpf_task_release(data_task);
+	if (!ptr)
+		return 0;
+
+	cgrp = bpf_kptr_xchg(&ptr->cgrp, NULL);
+	if (cgrp) {
+		int lvl = cgrp->level;
+
+		bpf_cgroup_release(cgrp);
+		return lvl;
+	}
+
+	udata = ptr->udata;
+	if (!udata || udata->result)
+		return 0;
+	udata->result = MAGIC_VALUE + udata->a + udata->b;
+
+	udata = ptr->nested.udata;
+	if (udata && !udata->nested_result)
+		udata->nested_result = udata->result;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";