// 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_experimental.h"
#include "task_kfunc_common.h"
char _license[] SEC("license") = "GPL";
int err, pid;
/* Prototype for all of the program trace events below:
*
* TRACE_EVENT(task_newtask,
* TP_PROTO(struct task_struct *p, u64 clone_flags)
*/
struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak;
struct task_struct *bpf_task_acquire___one(struct task_struct *task) __ksym __weak;
/* The two-param bpf_task_acquire doesn't exist */
struct task_struct *bpf_task_acquire___two(struct task_struct *p, void *ctx) __ksym __weak;
/* Incorrect type for first param */
struct task_struct *bpf_task_acquire___three(void *ctx) __ksym __weak;
void invalid_kfunc(void) __ksym __weak;
void bpf_testmod_test_mod_kfunc(int i) __ksym __weak;
static bool is_test_kfunc_task(void)
{
int cur_pid = bpf_get_current_pid_tgid() >> 32;
return pid == cur_pid;
}
static int test_acquire_release(struct task_struct *task)
{
struct task_struct *acquired = NULL;
if (!bpf_ksym_exists(bpf_task_acquire)) {
err = 3;
return 0;
}
if (!bpf_ksym_exists(bpf_testmod_test_mod_kfunc)) {
err = 4;
return 0;
}
if (bpf_ksym_exists(invalid_kfunc)) {
/* the verifier's dead code elimination should remove this */
err = 5;
asm volatile ("goto -1"); /* for (;;); */
}
acquired = bpf_task_acquire(task);
if (acquired)
bpf_task_release(acquired);
else
err = 6;
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_kfunc_flavor_relo, struct task_struct *task, u64 clone_flags)
{
struct task_struct *acquired = NULL;
int fake_ctx = 42;
if (bpf_ksym_exists(bpf_task_acquire___one)) {
acquired = bpf_task_acquire___one(task);
} else if (bpf_ksym_exists(bpf_task_acquire___two)) {
/* Here, bpf_object__resolve_ksym_func_btf_id's find_ksym_btf_id
* call will find vmlinux's bpf_task_acquire, but subsequent
* bpf_core_types_are_compat will fail
*/
acquired = bpf_task_acquire___two(task, &fake_ctx);
err = 3;
return 0;
} else if (bpf_ksym_exists(bpf_task_acquire___three)) {
/* bpf_core_types_are_compat will fail similarly to above case */
acquired = bpf_task_acquire___three(&fake_ctx);
err = 4;
return 0;
}
if (acquired)
bpf_task_release(acquired);
else
err = 5;
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_kfunc_flavor_relo_not_found, struct task_struct *task, u64 clone_flags)
{
/* Neither symbol should successfully resolve.
* Success or failure of one ___flavor should not affect others
*/
if (bpf_ksym_exists(bpf_task_acquire___two))
err = 1;
else if (bpf_ksym_exists(bpf_task_acquire___three))
err = 2;
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_acquire_release_argument, struct task_struct *task, u64 clone_flags)
{
if (!is_test_kfunc_task())
return 0;
return test_acquire_release(task);
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_acquire_release_current, struct task_struct *task, u64 clone_flags)
{
if (!is_test_kfunc_task())
return 0;
return test_acquire_release(bpf_get_current_task_btf());
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_acquire_leave_in_map, struct task_struct *task, u64 clone_flags)
{
long status;
if (!is_test_kfunc_task())
return 0;
status = tasks_kfunc_map_insert(task);
if (status)
err = 1;
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_xchg_release, struct task_struct *task, u64 clone_flags)
{
struct task_struct *kptr, *acquired;
struct __tasks_kfunc_map_value *v, *local;
int refcnt, refcnt_after_drop;
long status;
if (!is_test_kfunc_task())
return 0;
status = tasks_kfunc_map_insert(task);
if (status) {
err = 1;
return 0;
}
v = tasks_kfunc_map_value_lookup(task);
if (!v) {
err = 2;
return 0;
}
kptr = bpf_kptr_xchg(&v->task, NULL);
if (!kptr) {
err = 3;
return 0;
}
local = bpf_obj_new(typeof(*local));
if (!local) {
err = 4;
bpf_task_release(kptr);
return 0;
}
kptr = bpf_kptr_xchg(&local->task, kptr);
if (kptr) {
err = 5;
bpf_obj_drop(local);
bpf_task_release(kptr);
return 0;
}
kptr = bpf_kptr_xchg(&local->task, NULL);
if (!kptr) {
err = 6;
bpf_obj_drop(local);
return 0;
}
/* Stash a copy into local kptr and check if it is released recursively */
acquired = bpf_task_acquire(kptr);
if (!acquired) {
err = 7;
bpf_obj_drop(local);
bpf_task_release(kptr);
return 0;
}
bpf_probe_read_kernel(&refcnt, sizeof(refcnt), &acquired->rcu_users);
acquired = bpf_kptr_xchg(&local->task, acquired);
if (acquired) {
err = 8;
bpf_obj_drop(local);
bpf_task_release(kptr);
bpf_task_release(acquired);
return 0;
}
bpf_obj_drop(local);
bpf_probe_read_kernel(&refcnt_after_drop, sizeof(refcnt_after_drop), &kptr->rcu_users);
if (refcnt != refcnt_after_drop + 1) {
err = 9;
bpf_task_release(kptr);
return 0;
}
bpf_task_release(kptr);
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_map_acquire_release, struct task_struct *task, u64 clone_flags)
{
struct task_struct *kptr;
struct __tasks_kfunc_map_value *v;
long status;
if (!is_test_kfunc_task())
return 0;
status = tasks_kfunc_map_insert(task);
if (status) {
err = 1;
return 0;
}
v = tasks_kfunc_map_value_lookup(task);
if (!v) {
err = 2;
return 0;
}
bpf_rcu_read_lock();
kptr = v->task;
if (!kptr) {
err = 3;
} else {
kptr = bpf_task_acquire(kptr);
if (!kptr)
err = 4;
else
bpf_task_release(kptr);
}
bpf_rcu_read_unlock();
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_current_acquire_release, struct task_struct *task, u64 clone_flags)
{
struct task_struct *current, *acquired;
if (!is_test_kfunc_task())
return 0;
current = bpf_get_current_task_btf();
acquired = bpf_task_acquire(current);
if (acquired)
bpf_task_release(acquired);
else
err = 1;
return 0;
}
static void lookup_compare_pid(const struct task_struct *p)
{
struct task_struct *acquired;
acquired = bpf_task_from_pid(p->pid);
if (!acquired) {
err = 1;
return;
}
if (acquired->pid != p->pid)
err = 2;
bpf_task_release(acquired);
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_from_pid_arg, struct task_struct *task, u64 clone_flags)
{
if (!is_test_kfunc_task())
return 0;
lookup_compare_pid(task);
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_from_pid_current, struct task_struct *task, u64 clone_flags)
{
if (!is_test_kfunc_task())
return 0;
lookup_compare_pid(bpf_get_current_task_btf());
return 0;
}
static int is_pid_lookup_valid(s32 pid)
{
struct task_struct *acquired;
acquired = bpf_task_from_pid(pid);
if (acquired) {
bpf_task_release(acquired);
return 1;
}
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(test_task_from_pid_invalid, struct task_struct *task, u64 clone_flags)
{
if (!is_test_kfunc_task())
return 0;
bpf_strncmp(task->comm, 12, "foo");
bpf_strncmp(task->comm, 16, "foo");
bpf_strncmp(&task->comm[8], 4, "foo");
if (is_pid_lookup_valid(-1)) {
err = 1;
return 0;
}
if (is_pid_lookup_valid(0xcafef00d)) {
err = 2;
return 0;
}
return 0;
}
SEC("tp_btf/task_newtask")
int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags)
{
struct task_struct *acquired;
/* task->group_leader is listed as a trusted, non-NULL field of task struct. */
acquired = bpf_task_acquire(task->group_leader);
if (acquired)
bpf_task_release(acquired);
else
err = 1;
return 0;
}
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