forked from Qortal/Brooklyn
2a709f28fa
* 0day explit mitigation * Memory corruption prevention * Privilege escalation prevention * Buffer over flow prevention * File System corruption defense * Thread escape prevention This may very well be the most intensive inclusion to BrooklynR. This will not be part of an x86 suite nor it will be released as tool kit. The security core toolkit will remain part of kernel base.
122 lines
3.3 KiB
C
122 lines
3.3 KiB
C
#include <linux/spinlock.h>
|
|
#include <linux/task_work.h>
|
|
#include <linux/tracehook.h>
|
|
|
|
static struct callback_head work_exited; /* all we need is ->next == NULL */
|
|
|
|
/**
|
|
* task_work_add - ask the @task to execute @work->func()
|
|
* @task: the task which should run the callback
|
|
* @work: the callback to run
|
|
* @notify: send the notification if true
|
|
*
|
|
* Queue @work for task_work_run() below and notify the @task if @notify.
|
|
* Fails if the @task is exiting/exited and thus it can't process this @work.
|
|
* Otherwise @work->func() will be called when the @task returns from kernel
|
|
* mode or exits.
|
|
*
|
|
* This is like the signal handler which runs in kernel mode, but it doesn't
|
|
* try to wake up the @task.
|
|
*
|
|
* Note: there is no ordering guarantee on works queued here.
|
|
*
|
|
* RETURNS:
|
|
* 0 if succeeds or -ESRCH.
|
|
*/
|
|
int
|
|
task_work_add(struct task_struct *task, struct callback_head *work, bool notify)
|
|
{
|
|
struct callback_head *head;
|
|
|
|
do {
|
|
head = READ_ONCE(task->task_works);
|
|
if (unlikely(head == &work_exited))
|
|
return -ESRCH;
|
|
work->next = head;
|
|
} while (cmpxchg(&task->task_works, head, work) != head);
|
|
|
|
if (notify)
|
|
set_notify_resume(task);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* task_work_cancel - cancel a pending work added by task_work_add()
|
|
* @task: the task which should execute the work
|
|
* @func: identifies the work to remove
|
|
*
|
|
* Find the last queued pending work with ->func == @func and remove
|
|
* it from queue.
|
|
*
|
|
* RETURNS:
|
|
* The found work or NULL if not found.
|
|
*/
|
|
struct callback_head *
|
|
task_work_cancel(struct task_struct *task, task_work_func_t func)
|
|
{
|
|
struct callback_head **pprev = &task->task_works;
|
|
struct callback_head *work;
|
|
unsigned long flags;
|
|
|
|
if (likely(!task->task_works))
|
|
return NULL;
|
|
/*
|
|
* If cmpxchg() fails we continue without updating pprev.
|
|
* Either we raced with task_work_add() which added the
|
|
* new entry before this work, we will find it again. Or
|
|
* we raced with task_work_run(), *pprev == NULL/exited.
|
|
*/
|
|
raw_spin_lock_irqsave(&task->pi_lock, flags);
|
|
while ((work = lockless_dereference(*pprev))) {
|
|
if (work->func != func)
|
|
pprev = &work->next;
|
|
else if (cmpxchg(pprev, work, work->next) == work)
|
|
break;
|
|
}
|
|
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
|
|
|
|
return work;
|
|
}
|
|
|
|
/**
|
|
* task_work_run - execute the works added by task_work_add()
|
|
*
|
|
* Flush the pending works. Should be used by the core kernel code.
|
|
* Called before the task returns to the user-mode or stops, or when
|
|
* it exits. In the latter case task_work_add() can no longer add the
|
|
* new work after task_work_run() returns.
|
|
*/
|
|
void task_work_run(void)
|
|
{
|
|
struct task_struct *task = current;
|
|
struct callback_head *work, *head, *next;
|
|
|
|
for (;;) {
|
|
/*
|
|
* work->func() can do task_work_add(), do not set
|
|
* work_exited unless the list is empty.
|
|
*/
|
|
do {
|
|
work = READ_ONCE(task->task_works);
|
|
head = !work && (task->flags & PF_EXITING) ?
|
|
&work_exited : NULL;
|
|
} while (cmpxchg(&task->task_works, work, head) != work);
|
|
|
|
if (!work)
|
|
break;
|
|
/*
|
|
* Synchronize with task_work_cancel(). It can't remove
|
|
* the first entry == work, cmpxchg(task_works) should
|
|
* fail, but it can play with *work and other entries.
|
|
*/
|
|
raw_spin_unlock_wait(&task->pi_lock);
|
|
|
|
do {
|
|
next = work->next;
|
|
work->func(work);
|
|
work = next;
|
|
cond_resched();
|
|
} while (work);
|
|
}
|
|
}
|