/*
* linux/kernel/ptrace.c
*
* (C) Copyright 1999 Linus Torvalds
*
* Common interfaces for "ptrace()" which we do not want
* to continually duplicate across every architecture.
*/
#include <linux/capability.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/ptrace.h>
#include <linux/security.h>
#include <linux/signal.h>
#include <linux/uio.h>
#include <linux/audit.h>
#include <linux/pid_namespace.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/regset.h>
#include <linux/hw_breakpoint.h>
#include <linux/cn_proc.h>
#include <linux/compat.h>
/*
* ptrace a task: make the debugger its new parent and
* move it to the ptrace list.
*
* Must be called with the tasklist lock write-held.
*/
void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
{
BUG_ON(!list_empty(&child->ptrace_entry));
list_add(&child->ptrace_entry, &new_parent->ptraced);
child->parent = new_parent;
}
/**
* __ptrace_unlink - unlink ptracee and restore its execution state
* @child: ptracee to be unlinked
*
* Remove @child from the ptrace list, move it back to the original parent,
* and restore the execution state so that it conforms to the group stop
* state.
*
* Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
* exiting. For PTRACE_DETACH, unless the ptracee has been killed between
* ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
* If the ptracer is exiting, the ptracee can be in any state.
*
* After detach, the ptracee should be in a state which conforms to the
* group stop. If the group is stopped or in the process of stopping, the
* ptracee should be put into TASK_STOPPED; otherwise, it should be woken
* up from TASK_TRACED.
*
* If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
* it goes through TRACED -> RUNNING -> STOPPED transition which is similar
* to but in the opposite direction of what happens while attaching to a
* stopped task. However, in this direction, the intermediate RUNNING
* state is not hidden even from the current ptracer and if it immediately
* re-attaches and performs a WNOHANG wait(2), it may fail.
*
* CONTEXT:
* write_lock_irq(tasklist_lock)
*/
void __ptrace_unlink(struct task_struct *child)
{
BUG_ON(!child->ptrace);
child->ptrace = 0;
child->parent = child->real_parent;
list_del_init(&child->ptrace_entry);
spin_lock(&child->sighand->siglock);
/*
* Clear all pending traps and TRAPPING. TRAPPING should be
* cleared regardless of JOBCTL_STOP_PENDING. Do it explicitly.
*/
task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
task_clear_jobctl_trapping(child);
/*
* Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
* @child isn't dead.
*/
if (!(child->flags & PF_EXITING) &&
(child->signal->flags & SIGNAL_STOP_STOPPED ||
child->signal->group_stop_count)) {
child->jobctl |= JOBCTL_STOP_PENDING;
/*
* This is only possible if this thread was cloned by the
* traced task running in the stopped group, set the signal
* for the future reports.
* FIXME: we should change ptrace_init_task() to handle this
* case.
*/
if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
child->jobctl |= SIGSTOP;
}
/*
* If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
* @child in the butt. Note that @resume should be used iff @child
* is in TASK_TRACED; otherwise, we might unduly disrupt
* TASK_KILLABLE sleeps.
*/
if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
ptrace_signal_wake_up(child, true);
spin_unlock(&child->sighand->siglock);
}
/* Ensure that nothing can wake it up, even SIGKILL */
static bool ptrace_freeze_traced(struct task_struct *task)
{
bool ret = false;
/* Lockless, nobody but us can set this flag */
if (task->jobctl & JOBCTL_LISTENING)
return ret;
spin_lock_irq(&task->sighand->siglock);
if (task_is_traced(task) &&