1 files changed, 326 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
new file mode 100644
index 000000000000..ad88a3796ddf
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
@@ -0,0 +1,326 @@
+// 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 "bpf_misc.h"
+#include "task_kfunc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+/* Prototype for all of the program trace events below:
+ *
+ * TRACE_EVENT(task_newtask,
+ *         TP_PROTO(struct task_struct *p, u64 clone_flags)
+ */
+
+static struct __tasks_kfunc_map_value *insert_lookup_task(struct task_struct *task)
+{
+	int status;
+
+	status = tasks_kfunc_map_insert(task);
+	if (status)
+		return NULL;
+
+	return tasks_kfunc_map_value_lookup(task);
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(task_kfunc_acquire_untrusted, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired;
+	struct __tasks_kfunc_map_value *v;
+
+	v = insert_lookup_task(task);
+	if (!v)
+		return 0;
+
+	/* Can't invoke bpf_task_acquire() on an untrusted pointer. */
+	acquired = bpf_task_acquire(v->task);
+	if (!acquired)
+		return 0;
+
+	bpf_task_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("arg#0 pointer type STRUCT task_struct must point")
+int BPF_PROG(task_kfunc_acquire_fp, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired, *stack_task = (struct task_struct *)&clone_flags;
+
+	/* Can't invoke bpf_task_acquire() on a random frame pointer. */
+	acquired = bpf_task_acquire((struct task_struct *)&stack_task);
+	if (!acquired)
+		return 0;
+
+	bpf_task_release(acquired);
+
+	return 0;
+}
+
+SEC("kretprobe/free_task")
+__failure __msg("calling kernel function bpf_task_acquire is not allowed")
+int BPF_PROG(task_kfunc_acquire_unsafe_kretprobe, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired;
+
+	/* Can't call bpf_task_acquire() or bpf_task_release() in an untrusted prog. */
+	acquired = bpf_task_acquire(task);
+	if (!acquired)
+		return 0;
+	bpf_task_release(acquired);
+
+	return 0;
+}
+
+SEC("kretprobe/free_task")
+__failure __msg("calling kernel function bpf_task_acquire is not allowed")
+int BPF_PROG(task_kfunc_acquire_unsafe_kretprobe_rcu, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired;
+
+	bpf_rcu_read_lock();
+	if (!task) {
+		bpf_rcu_read_unlock();
+		return 0;
+	}
+	/* Can't call bpf_task_acquire() or bpf_task_release() in an untrusted prog. */
+	acquired = bpf_task_acquire(task);
+	if (acquired)
+		bpf_task_release(acquired);
+	bpf_rcu_read_unlock();
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(task_kfunc_acquire_null, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired;
+
+	/* Can't invoke bpf_task_acquire() on a NULL pointer. */
+	acquired = bpf_task_acquire(NULL);
+	if (!acquired)
+		return 0;
+	bpf_task_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Unreleased reference")
+int BPF_PROG(task_kfunc_acquire_unreleased, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired;
+
+	acquired = bpf_task_acquire(task);
+
+	/* Acquired task is never released. */
+	__sink(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Unreleased reference")
+int BPF_PROG(task_kfunc_xchg_unreleased, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *kptr;
+	struct __tasks_kfunc_map_value *v;
+
+	v = insert_lookup_task(task);
+	if (!v)
+		return 0;
+
+	kptr = bpf_kptr_xchg(&v->task, NULL);
+	if (!kptr)
+		return 0;
+
+	/* Kptr retrieved from map is never released. */
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(task_kfunc_acquire_release_no_null_check, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired;
+
+	acquired = bpf_task_acquire(task);
+	/* Can't invoke bpf_task_release() on an acquired task without a NULL check. */
+	bpf_task_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(task_kfunc_release_untrusted, struct task_struct *task, u64 clone_flags)
+{
+	struct __tasks_kfunc_map_value *v;
+
+	v = insert_lookup_task(task);
+	if (!v)
+		return 0;
+
+	/* Can't invoke bpf_task_release() on an untrusted pointer. */
+	bpf_task_release(v->task);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("arg#0 pointer type STRUCT task_struct must point")
+int BPF_PROG(task_kfunc_release_fp, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired = (struct task_struct *)&clone_flags;
+
+	/* Cannot release random frame pointer. */
+	bpf_task_release(acquired);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(task_kfunc_release_null, struct task_struct *task, u64 clone_flags)
+{
+	struct __tasks_kfunc_map_value local, *v;
+	long status;
+	struct task_struct *acquired, *old;
+	s32 pid;
+
+	status = bpf_probe_read_kernel(&pid, sizeof(pid), &task->pid);
+	if (status)
+		return 0;
+
+	local.task = NULL;
+	status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);
+	if (status)
+		return status;
+
+	v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
+	if (!v)
+		return -ENOENT;
+
+	acquired = bpf_task_acquire(task);
+	if (!acquired)
+		return -EEXIST;
+
+	old = bpf_kptr_xchg(&v->task, acquired);
+
+	/* old cannot be passed to bpf_task_release() without a NULL check. */
+	bpf_task_release(old);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("release kernel function bpf_task_release expects")
+int BPF_PROG(task_kfunc_release_unacquired, struct task_struct *task, u64 clone_flags)
+{
+	/* Cannot release trusted task pointer which was not acquired. */
+	bpf_task_release(task);
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(task_kfunc_from_pid_no_null_check, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *acquired;
+
+	acquired = bpf_task_from_pid(task->pid);
+
+	/* Releasing bpf_task_from_pid() lookup without a NULL check. */
+	bpf_task_release(acquired);
+
+	return 0;
+}
+
+SEC("lsm/task_free")
+__failure __msg("R1 must be a rcu pointer")
+int BPF_PROG(task_kfunc_from_lsm_task_free, struct task_struct *task)
+{
+	struct task_struct *acquired;
+
+	/* the argument of lsm task_free hook is untrusted. */
+	acquired = bpf_task_acquire(task);
+	if (!acquired)
+		return 0;
+
+	bpf_task_release(acquired);
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("access beyond the end of member comm")
+int BPF_PROG(task_access_comm1, struct task_struct *task, u64 clone_flags)
+{
+	bpf_strncmp(task->comm, 17, "foo");
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("access beyond the end of member comm")
+int BPF_PROG(task_access_comm2, struct task_struct *task, u64 clone_flags)
+{
+	bpf_strncmp(task->comm + 1, 16, "foo");
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("write into memory")
+int BPF_PROG(task_access_comm3, struct task_struct *task, u64 clone_flags)
+{
+	bpf_probe_read_kernel(task->comm, 16, task->comm);
+	return 0;
+}
+
+SEC("fentry/__set_task_comm")
+__failure __msg("R1 type=ptr_ expected")
+int BPF_PROG(task_access_comm4, struct task_struct *task, const char *buf, bool exec)
+{
+	/*
+	 * task->comm is a legacy ptr_to_btf_id. The verifier cannot guarantee
+	 * its safety. Hence it cannot be accessed with normal load insns.
+	 */
+	bpf_strncmp(task->comm, 16, "foo");
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("R1 must be referenced or trusted")
+int BPF_PROG(task_kfunc_release_in_map, struct task_struct *task, u64 clone_flags)
+{
+	struct task_struct *local;
+	struct __tasks_kfunc_map_value *v;
+
+	if (tasks_kfunc_map_insert(task))
+		return 0;
+
+	v = tasks_kfunc_map_value_lookup(task);
+	if (!v)
+		return 0;
+
+	bpf_rcu_read_lock();
+	local = v->task;
+	if (!local) {
+		bpf_rcu_read_unlock();
+		return 0;
+	}
+	/* Can't release a kptr that's still stored in a map. */
+	bpf_task_release(local);
+	bpf_rcu_read_unlock();
+
+	return 0;
+}