mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 02:39:48 +00:00
493 lines
11 KiB
C
493 lines
11 KiB
C
/*
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* linux/kernel/ptrace.c
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*
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* (C) Copyright 1999 Linus Torvalds
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*
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* Common interfaces for "ptrace()" which we do not want
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* to continually duplicate across every architecture.
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*/
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#include <linux/capability.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/pagemap.h>
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#include <linux/smp_lock.h>
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#include <linux/ptrace.h>
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#include <linux/security.h>
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#include <linux/signal.h>
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#include <linux/audit.h>
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#include <asm/pgtable.h>
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#include <asm/uaccess.h>
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/*
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* ptrace a task: make the debugger its new parent and
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* move it to the ptrace list.
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*
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* Must be called with the tasklist lock write-held.
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*/
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void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
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{
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BUG_ON(!list_empty(&child->ptrace_list));
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if (child->parent == new_parent)
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return;
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list_add(&child->ptrace_list, &child->parent->ptrace_children);
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remove_parent(child);
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child->parent = new_parent;
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add_parent(child);
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}
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/*
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* Turn a tracing stop into a normal stop now, since with no tracer there
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* would be no way to wake it up with SIGCONT or SIGKILL. If there was a
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* signal sent that would resume the child, but didn't because it was in
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* TASK_TRACED, resume it now.
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* Requires that irqs be disabled.
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*/
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void ptrace_untrace(struct task_struct *child)
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{
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spin_lock(&child->sighand->siglock);
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if (child->state == TASK_TRACED) {
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if (child->signal->flags & SIGNAL_STOP_STOPPED) {
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child->state = TASK_STOPPED;
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} else {
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signal_wake_up(child, 1);
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}
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}
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spin_unlock(&child->sighand->siglock);
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}
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/*
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* unptrace a task: move it back to its original parent and
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* remove it from the ptrace list.
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*
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* Must be called with the tasklist lock write-held.
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*/
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void __ptrace_unlink(struct task_struct *child)
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{
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BUG_ON(!child->ptrace);
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child->ptrace = 0;
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if (!list_empty(&child->ptrace_list)) {
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list_del_init(&child->ptrace_list);
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remove_parent(child);
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child->parent = child->real_parent;
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add_parent(child);
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}
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if (child->state == TASK_TRACED)
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ptrace_untrace(child);
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}
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/*
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* Check that we have indeed attached to the thing..
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*/
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int ptrace_check_attach(struct task_struct *child, int kill)
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{
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int ret = -ESRCH;
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/*
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* We take the read lock around doing both checks to close a
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* possible race where someone else was tracing our child and
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* detached between these two checks. After this locked check,
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* we are sure that this is our traced child and that can only
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* be changed by us so it's not changing right after this.
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*/
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read_lock(&tasklist_lock);
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if ((child->ptrace & PT_PTRACED) && child->parent == current &&
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(!(child->ptrace & PT_ATTACHED) || child->real_parent != current)
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&& child->signal != NULL) {
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ret = 0;
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spin_lock_irq(&child->sighand->siglock);
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if (child->state == TASK_STOPPED) {
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child->state = TASK_TRACED;
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} else if (child->state != TASK_TRACED && !kill) {
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ret = -ESRCH;
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}
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spin_unlock_irq(&child->sighand->siglock);
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}
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read_unlock(&tasklist_lock);
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if (!ret && !kill) {
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wait_task_inactive(child);
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}
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/* All systems go.. */
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return ret;
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}
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static int may_attach(struct task_struct *task)
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{
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/* May we inspect the given task?
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* This check is used both for attaching with ptrace
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* and for allowing access to sensitive information in /proc.
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*
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* ptrace_attach denies several cases that /proc allows
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* because setting up the necessary parent/child relationship
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* or halting the specified task is impossible.
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*/
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int dumpable = 0;
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/* Don't let security modules deny introspection */
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if (task == current)
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return 0;
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if (((current->uid != task->euid) ||
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(current->uid != task->suid) ||
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(current->uid != task->uid) ||
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(current->gid != task->egid) ||
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(current->gid != task->sgid) ||
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(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
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return -EPERM;
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smp_rmb();
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if (task->mm)
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dumpable = task->mm->dumpable;
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if (!dumpable && !capable(CAP_SYS_PTRACE))
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return -EPERM;
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return security_ptrace(current, task);
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}
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int ptrace_may_attach(struct task_struct *task)
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{
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int err;
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task_lock(task);
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err = may_attach(task);
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task_unlock(task);
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return !err;
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}
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int ptrace_attach(struct task_struct *task)
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{
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int retval;
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audit_ptrace(task);
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retval = -EPERM;
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if (task->pid <= 1)
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goto out;
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if (task->tgid == current->tgid)
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goto out;
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repeat:
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/*
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* Nasty, nasty.
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*
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* We want to hold both the task-lock and the
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* tasklist_lock for writing at the same time.
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* But that's against the rules (tasklist_lock
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* is taken for reading by interrupts on other
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* cpu's that may have task_lock).
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*/
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task_lock(task);
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local_irq_disable();
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if (!write_trylock(&tasklist_lock)) {
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local_irq_enable();
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task_unlock(task);
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do {
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cpu_relax();
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} while (!write_can_lock(&tasklist_lock));
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goto repeat;
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}
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if (!task->mm)
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goto bad;
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/* the same process cannot be attached many times */
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if (task->ptrace & PT_PTRACED)
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goto bad;
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retval = may_attach(task);
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if (retval)
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goto bad;
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/* Go */
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task->ptrace |= PT_PTRACED | ((task->real_parent != current)
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? PT_ATTACHED : 0);
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if (capable(CAP_SYS_PTRACE))
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task->ptrace |= PT_PTRACE_CAP;
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__ptrace_link(task, current);
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force_sig_specific(SIGSTOP, task);
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bad:
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write_unlock_irq(&tasklist_lock);
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task_unlock(task);
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out:
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return retval;
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}
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static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
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{
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child->exit_code = data;
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/* .. re-parent .. */
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__ptrace_unlink(child);
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/* .. and wake it up. */
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if (child->exit_state != EXIT_ZOMBIE)
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wake_up_process(child);
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}
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int ptrace_detach(struct task_struct *child, unsigned int data)
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{
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if (!valid_signal(data))
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return -EIO;
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/* Architecture-specific hardware disable .. */
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ptrace_disable(child);
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write_lock_irq(&tasklist_lock);
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/* protect against de_thread()->release_task() */
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if (child->ptrace)
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__ptrace_detach(child, data);
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write_unlock_irq(&tasklist_lock);
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return 0;
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}
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int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
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{
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int copied = 0;
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while (len > 0) {
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char buf[128];
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int this_len, retval;
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this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
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retval = access_process_vm(tsk, src, buf, this_len, 0);
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if (!retval) {
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if (copied)
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break;
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return -EIO;
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}
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if (copy_to_user(dst, buf, retval))
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return -EFAULT;
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copied += retval;
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src += retval;
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dst += retval;
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len -= retval;
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}
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return copied;
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}
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int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
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{
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int copied = 0;
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while (len > 0) {
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char buf[128];
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int this_len, retval;
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this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
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if (copy_from_user(buf, src, this_len))
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return -EFAULT;
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retval = access_process_vm(tsk, dst, buf, this_len, 1);
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if (!retval) {
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if (copied)
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break;
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return -EIO;
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}
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copied += retval;
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src += retval;
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dst += retval;
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len -= retval;
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}
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return copied;
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}
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static int ptrace_setoptions(struct task_struct *child, long data)
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{
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child->ptrace &= ~PT_TRACE_MASK;
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if (data & PTRACE_O_TRACESYSGOOD)
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child->ptrace |= PT_TRACESYSGOOD;
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if (data & PTRACE_O_TRACEFORK)
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child->ptrace |= PT_TRACE_FORK;
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if (data & PTRACE_O_TRACEVFORK)
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child->ptrace |= PT_TRACE_VFORK;
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if (data & PTRACE_O_TRACECLONE)
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child->ptrace |= PT_TRACE_CLONE;
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if (data & PTRACE_O_TRACEEXEC)
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child->ptrace |= PT_TRACE_EXEC;
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if (data & PTRACE_O_TRACEVFORKDONE)
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child->ptrace |= PT_TRACE_VFORK_DONE;
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if (data & PTRACE_O_TRACEEXIT)
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child->ptrace |= PT_TRACE_EXIT;
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return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
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}
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static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
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{
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siginfo_t lastinfo;
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int error = -ESRCH;
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read_lock(&tasklist_lock);
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if (likely(child->sighand != NULL)) {
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error = -EINVAL;
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spin_lock_irq(&child->sighand->siglock);
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if (likely(child->last_siginfo != NULL)) {
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lastinfo = *child->last_siginfo;
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error = 0;
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}
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spin_unlock_irq(&child->sighand->siglock);
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}
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read_unlock(&tasklist_lock);
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if (!error)
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return copy_siginfo_to_user(data, &lastinfo);
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return error;
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}
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static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
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{
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siginfo_t newinfo;
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int error = -ESRCH;
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if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
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return -EFAULT;
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read_lock(&tasklist_lock);
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if (likely(child->sighand != NULL)) {
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error = -EINVAL;
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spin_lock_irq(&child->sighand->siglock);
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if (likely(child->last_siginfo != NULL)) {
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*child->last_siginfo = newinfo;
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error = 0;
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}
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spin_unlock_irq(&child->sighand->siglock);
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}
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read_unlock(&tasklist_lock);
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return error;
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}
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int ptrace_request(struct task_struct *child, long request,
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long addr, long data)
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{
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int ret = -EIO;
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switch (request) {
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#ifdef PTRACE_OLDSETOPTIONS
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case PTRACE_OLDSETOPTIONS:
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#endif
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case PTRACE_SETOPTIONS:
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ret = ptrace_setoptions(child, data);
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break;
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case PTRACE_GETEVENTMSG:
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ret = put_user(child->ptrace_message, (unsigned long __user *) data);
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break;
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case PTRACE_GETSIGINFO:
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ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
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break;
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case PTRACE_SETSIGINFO:
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ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
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break;
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default:
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break;
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}
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return ret;
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}
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/**
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* ptrace_traceme -- helper for PTRACE_TRACEME
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*
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* Performs checks and sets PT_PTRACED.
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* Should be used by all ptrace implementations for PTRACE_TRACEME.
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*/
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int ptrace_traceme(void)
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{
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int ret = -EPERM;
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/*
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* Are we already being traced?
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*/
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task_lock(current);
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if (!(current->ptrace & PT_PTRACED)) {
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ret = security_ptrace(current->parent, current);
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/*
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* Set the ptrace bit in the process ptrace flags.
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*/
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if (!ret)
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current->ptrace |= PT_PTRACED;
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}
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task_unlock(current);
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return ret;
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}
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/**
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* ptrace_get_task_struct -- grab a task struct reference for ptrace
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* @pid: process id to grab a task_struct reference of
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*
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* This function is a helper for ptrace implementations. It checks
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* permissions and then grabs a task struct for use of the actual
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* ptrace implementation.
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*
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* Returns the task_struct for @pid or an ERR_PTR() on failure.
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*/
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struct task_struct *ptrace_get_task_struct(pid_t pid)
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{
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struct task_struct *child;
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/*
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* Tracing init is not allowed.
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*/
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if (pid == 1)
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return ERR_PTR(-EPERM);
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read_lock(&tasklist_lock);
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child = find_task_by_pid(pid);
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if (child)
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get_task_struct(child);
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read_unlock(&tasklist_lock);
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if (!child)
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return ERR_PTR(-ESRCH);
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return child;
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}
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#ifndef __ARCH_SYS_PTRACE
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asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
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{
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struct task_struct *child;
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long ret;
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/*
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* This lock_kernel fixes a subtle race with suid exec
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*/
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lock_kernel();
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if (request == PTRACE_TRACEME) {
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ret = ptrace_traceme();
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goto out;
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}
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child = ptrace_get_task_struct(pid);
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if (IS_ERR(child)) {
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ret = PTR_ERR(child);
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goto out;
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}
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if (request == PTRACE_ATTACH) {
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ret = ptrace_attach(child);
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goto out_put_task_struct;
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}
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ret = ptrace_check_attach(child, request == PTRACE_KILL);
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if (ret < 0)
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goto out_put_task_struct;
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ret = arch_ptrace(child, request, addr, data);
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if (ret < 0)
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goto out_put_task_struct;
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out_put_task_struct:
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put_task_struct(child);
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out:
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unlock_kernel();
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return ret;
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}
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#endif /* __ARCH_SYS_PTRACE */
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