1 files changed, 596 insertions, 259 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 4041f5747e73..392ec2f75f01 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/kernel/ptrace.c
  *
@@ -10,6 +11,9 @@
 #include <linux/capability.h>
 #include <linux/export.h>
 #include <linux/sched.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/coredump.h>
+#include <linux/sched/task.h>
 #include <linux/errno.h>
 #include <linux/mm.h>
 #include <linux/highmem.h>
@@ -26,12 +30,49 @@
 #include <linux/hw_breakpoint.h>
 #include <linux/cn_proc.h>
 #include <linux/compat.h>
+#include <linux/sched/signal.h>
+#include <linux/minmax.h>
+#include <linux/syscall_user_dispatch.h>
 
+#include <asm/syscall.h>	/* for syscall_get_* */
 
-static int ptrace_trapping_sleep_fn(void *flags)
+/*
+ * Access another process' address space via ptrace.
+ * Source/target buffer must be kernel space,
+ * Do not walk the page table directly, use get_user_pages
+ */
+int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
+		     void *buf, int len, unsigned int gup_flags)
 {
-	schedule();
-	return 0;
+	struct mm_struct *mm;
+	int ret;
+
+	mm = get_task_mm(tsk);
+	if (!mm)
+		return 0;
+
+	if (!tsk->ptrace ||
+	    (current != tsk->parent) ||
+	    ((get_dumpable(mm) != SUID_DUMP_USER) &&
+	     !ptracer_capable(tsk, mm->user_ns))) {
+		mmput(mm);
+		return 0;
+	}
+
+	ret = access_remote_vm(mm, addr, buf, len, gup_flags);
+	mmput(mm);
+
+	return ret;
+}
+
+
+void __ptrace_link(struct task_struct *child, struct task_struct *new_parent,
+		   const struct cred *ptracer_cred)
+{
+	BUG_ON(!list_empty(&child->ptrace_entry));
+	list_add(&child->ptrace_entry, &new_parent->ptraced);
+	child->parent = new_parent;
+	child->ptracer_cred = get_cred(ptracer_cred);
 }
 
 /*
@@ -40,11 +81,9 @@ static int ptrace_trapping_sleep_fn(void *flags)
  *
  * Must be called with the tasklist lock write-held.
  */
-void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
+static 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_link(child, new_parent, current_cred());
 }
 
 /**
@@ -77,14 +116,22 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  */
 void __ptrace_unlink(struct task_struct *child)
 {
+	const struct cred *old_cred;
 	BUG_ON(!child->ptrace);
 
-	child->ptrace = 0;
+	clear_task_syscall_work(child, SYSCALL_TRACE);
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
+	clear_task_syscall_work(child, SYSCALL_EMU);
+#endif
+
 	child->parent = child->real_parent;
 	list_del_init(&child->ptrace_entry);
+	old_cred = child->ptracer_cred;
+	child->ptracer_cred = NULL;
+	put_cred(old_cred);
 
 	spin_lock(&child->sighand->siglock);
-
+	child->ptrace = 0;
 	/*
 	 * Clear all pending traps and TRAPPING.  TRAPPING should be
 	 * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
@@ -98,20 +145,9 @@ void __ptrace_unlink(struct task_struct *child)
 	 */
 	if (!(child->flags & PF_EXITING) &&
 	    (child->signal->flags & SIGNAL_STOP_STOPPED ||
-	     child->signal->group_stop_count)) {
+	     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
@@ -124,7 +160,27 @@ void __ptrace_unlink(struct task_struct *child)
 	spin_unlock(&child->sighand->siglock);
 }
 
-/* Ensure that nothing can wake it up, even SIGKILL */
+static bool looks_like_a_spurious_pid(struct task_struct *task)
+{
+	if (task->exit_code != ((PTRACE_EVENT_EXEC << 8) | SIGTRAP))
+		return false;
+
+	if (task_pid_vnr(task) == task->ptrace_message)
+		return false;
+	/*
+	 * The tracee changed its pid but the PTRACE_EVENT_EXEC event
+	 * was not wait()'ed, most probably debugger targets the old
+	 * leader which was destroyed in de_thread().
+	 */
+	return true;
+}
+
+/*
+ * Ensure that nothing can wake it up, even SIGKILL
+ *
+ * A task is switched to this state while a ptrace operation is in progress;
+ * such that the ptrace operation is uninterruptible.
+ */
 static bool ptrace_freeze_traced(struct task_struct *task)
 {
 	bool ret = false;
@@ -134,8 +190,9 @@ static bool ptrace_freeze_traced(struct task_struct *task)
 		return ret;
 
 	spin_lock_irq(&task->sighand->siglock);
-	if (task_is_traced(task) && !__fatal_signal_pending(task)) {
-		task->state = __TASK_TRACED;
+	if (task_is_traced(task) && !looks_like_a_spurious_pid(task) &&
+	    !__fatal_signal_pending(task)) {
+		task->jobctl |= JOBCTL_PTRACE_FROZEN;
 		ret = true;
 	}
 	spin_unlock_irq(&task->sighand->siglock);
@@ -145,17 +202,21 @@ static bool ptrace_freeze_traced(struct task_struct *task)
 
 static void ptrace_unfreeze_traced(struct task_struct *task)
 {
-	if (task->state != __TASK_TRACED)
-		return;
-
-	WARN_ON(!task->ptrace || task->parent != current);
+	unsigned long flags;
 
-	spin_lock_irq(&task->sighand->siglock);
-	if (__fatal_signal_pending(task))
-		wake_up_state(task, __TASK_TRACED);
-	else
-		task->state = TASK_TRACED;
-	spin_unlock_irq(&task->sighand->siglock);
+	/*
+	 * The child may be awake and may have cleared
+	 * JOBCTL_PTRACE_FROZEN (see ptrace_resume).  The child will
+	 * not set JOBCTL_PTRACE_FROZEN or enter __TASK_TRACED anew.
+	 */
+	if (lock_task_sighand(task, &flags)) {
+		task->jobctl &= ~JOBCTL_PTRACE_FROZEN;
+		if (__fatal_signal_pending(task)) {
+			task->jobctl &= ~JOBCTL_TRACED;
+			wake_up_state(task, __TASK_TRACED);
+		}
+		unlock_task_sighand(task, &flags);
+	}
 }
 
 /**
@@ -188,7 +249,6 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 	 */
 	read_lock(&tasklist_lock);
 	if (child->ptrace && child->parent == current) {
-		WARN_ON(child->state == __TASK_TRACED);
 		/*
 		 * child->sighand can't be NULL, release_task()
 		 * does ptrace_unlink() before __exit_signal().
@@ -198,33 +258,32 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 	}
 	read_unlock(&tasklist_lock);
 
-	if (!ret && !ignore_state) {
-		if (!wait_task_inactive(child, __TASK_TRACED)) {
-			/*
-			 * This can only happen if may_ptrace_stop() fails and
-			 * ptrace_stop() changes ->state back to TASK_RUNNING,
-			 * so we should not worry about leaking __TASK_TRACED.
-			 */
-			WARN_ON(child->state == __TASK_TRACED);
-			ret = -ESRCH;
-		}
-	}
+	if (!ret && !ignore_state &&
+	    WARN_ON_ONCE(!wait_task_inactive(child, __TASK_TRACED|TASK_FROZEN)))
+		ret = -ESRCH;
 
 	return ret;
 }
 
-static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
+static bool ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 {
 	if (mode & PTRACE_MODE_NOAUDIT)
-		return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
-	else
-		return has_ns_capability(current, ns, CAP_SYS_PTRACE);
+		return ns_capable_noaudit(ns, CAP_SYS_PTRACE);
+	return ns_capable(ns, CAP_SYS_PTRACE);
 }
 
 /* Returns 0 on success, -errno on denial. */
 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
 	const struct cred *cred = current_cred(), *tcred;
+	struct mm_struct *mm;
+	kuid_t caller_uid;
+	kgid_t caller_gid;
+
+	if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
+		WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
+		return -EPERM;
+	}
 
 	/* May we inspect the given task?
 	 * This check is used both for attaching with ptrace
@@ -234,18 +293,33 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	 * because setting up the necessary parent/child relationship
 	 * or halting the specified task is impossible.
 	 */
-	int dumpable = 0;
+
 	/* Don't let security modules deny introspection */
-	if (task == current)
+	if (same_thread_group(task, current))
 		return 0;
 	rcu_read_lock();
+	if (mode & PTRACE_MODE_FSCREDS) {
+		caller_uid = cred->fsuid;
+		caller_gid = cred->fsgid;
+	} else {
+		/*
+		 * Using the euid would make more sense here, but something
+		 * in userland might rely on the old behavior, and this
+		 * shouldn't be a security problem since
+		 * PTRACE_MODE_REALCREDS implies that the caller explicitly
+		 * used a syscall that requests access to another process
+		 * (and not a filesystem syscall to procfs).
+		 */
+		caller_uid = cred->uid;
+		caller_gid = cred->gid;
+	}
 	tcred = __task_cred(task);
-	if (uid_eq(cred->uid, tcred->euid) &&
-	    uid_eq(cred->uid, tcred->suid) &&
-	    uid_eq(cred->uid, tcred->uid)  &&
-	    gid_eq(cred->gid, tcred->egid) &&
-	    gid_eq(cred->gid, tcred->sgid) &&
-	    gid_eq(cred->gid, tcred->gid))
+	if (uid_eq(caller_uid, tcred->euid) &&
+	    uid_eq(caller_uid, tcred->suid) &&
+	    uid_eq(caller_uid, tcred->uid)  &&
+	    gid_eq(caller_gid, tcred->egid) &&
+	    gid_eq(caller_gid, tcred->sgid) &&
+	    gid_eq(caller_gid, tcred->gid))
 		goto ok;
 	if (ptrace_has_cap(tcred->user_ns, mode))
 		goto ok;
@@ -253,15 +327,21 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	return -EPERM;
 ok:
 	rcu_read_unlock();
+	/*
+	 * If a task drops privileges and becomes nondumpable (through a syscall
+	 * like setresuid()) while we are trying to access it, we must ensure
+	 * that the dumpability is read after the credentials; otherwise,
+	 * we may be able to attach to a task that we shouldn't be able to
+	 * attach to (as if the task had dropped privileges without becoming
+	 * nondumpable).
+	 * Pairs with a write barrier in commit_creds().
+	 */
 	smp_rmb();
-	if (task->mm)
-		dumpable = get_dumpable(task->mm);
-	rcu_read_lock();
-	if (!dumpable && !ptrace_has_cap(__task_cred(task)->user_ns, mode)) {
-		rcu_read_unlock();
-		return -EPERM;
-	}
-	rcu_read_unlock();
+	mm = task->mm;
+	if (mm &&
+	    ((get_dumpable(mm) != SUID_DUMP_USER) &&
+	     !ptrace_has_cap(mm->user_ns, mode)))
+	    return -EPERM;
 
 	return security_ptrace_access_check(task, mode);
 }
@@ -275,6 +355,57 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 	return !err;
 }
 
+static int check_ptrace_options(unsigned long data)
+{
+	if (data & ~(unsigned long)PTRACE_O_MASK)
+		return -EINVAL;
+
+	if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
+		if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
+		    !IS_ENABLED(CONFIG_SECCOMP))
+			return -EINVAL;
+
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+
+		if (seccomp_mode(&current->seccomp) != SECCOMP_MODE_DISABLED ||
+		    current->ptrace & PT_SUSPEND_SECCOMP)
+			return -EPERM;
+	}
+	return 0;
+}
+
+static inline void ptrace_set_stopped(struct task_struct *task, bool seize)
+{
+	guard(spinlock)(&task->sighand->siglock);
+
+	/* SEIZE doesn't trap tracee on attach */
+	if (!seize)
+		send_signal_locked(SIGSTOP, SEND_SIG_PRIV, task, PIDTYPE_PID);
+	/*
+	 * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
+	 * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
+	 * will be cleared if the child completes the transition or any
+	 * event which clears the group stop states happens.  We'll wait
+	 * for the transition to complete before returning from this
+	 * function.
+	 *
+	 * This hides STOPPED -> RUNNING -> TRACED transition from the
+	 * attaching thread but a different thread in the same group can
+	 * still observe the transient RUNNING state.  IOW, if another
+	 * thread's WNOHANG wait(2) on the stopped tracee races against
+	 * ATTACH, the wait(2) may fail due to the transient RUNNING.
+	 *
+	 * The following task_is_stopped() test is safe as both transitions
+	 * in and out of STOPPED are protected by siglock.
+	 */
+	if (task_is_stopped(task) &&
+	    task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) {
+		task->jobctl &= ~JOBCTL_STOPPED;
+		signal_wake_up_state(task, __TASK_STOPPED);
+	}
+}
+
 static int ptrace_attach(struct task_struct *task, long request,
 			 unsigned long addr,
 			 unsigned long flags)
@@ -282,12 +413,20 @@ static int ptrace_attach(struct task_struct *task, long request,
 	bool seize = (request == PTRACE_SEIZE);
 	int retval;
 
-	retval = -EIO;
 	if (seize) {
 		if (addr != 0)
-			goto out;
+			return -EIO;
+		/*
+		 * This duplicates the check in check_ptrace_options() because
+		 * ptrace_attach() and ptrace_setoptions() have historically
+		 * used different error codes for unknown ptrace options.
+		 */
 		if (flags & ~(unsigned long)PTRACE_O_MASK)
-			goto out;
+			return -EIO;
+
+		retval = check_ptrace_options(flags);
+		if (retval)
+			return retval;
 		flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
 	} else {
 		flags = PT_PTRACED;
@@ -295,86 +434,48 @@ static int ptrace_attach(struct task_struct *task, long request,
 
 	audit_ptrace(task);
 
-	retval = -EPERM;
 	if (unlikely(task->flags & PF_KTHREAD))
-		goto out;
+		return -EPERM;
 	if (same_thread_group(task, current))
-		goto out;
+		return -EPERM;
 
 	/*
 	 * Protect exec's credential calculations against our interference;
 	 * SUID, SGID and LSM creds get determined differently
 	 * under ptrace.
 	 */
-	retval = -ERESTARTNOINTR;
-	if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
-		goto out;
-
-	task_lock(task);
-	retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
-	task_unlock(task);
-	if (retval)
-		goto unlock_creds;
-
-	write_lock_irq(&tasklist_lock);
-	retval = -EPERM;
-	if (unlikely(task->exit_state))
-		goto unlock_tasklist;
-	if (task->ptrace)
-		goto unlock_tasklist;
-
-	if (seize)
-		flags |= PT_SEIZED;
-	rcu_read_lock();
-	if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE))
-		flags |= PT_PTRACE_CAP;
-	rcu_read_unlock();
-	task->ptrace = flags;
+	scoped_cond_guard (mutex_intr, return -ERESTARTNOINTR,
+			   &task->signal->cred_guard_mutex) {
 
-	__ptrace_link(task, current);
+		scoped_guard (task_lock, task) {
+			retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
+			if (retval)
+				return retval;
+		}
 
-	/* SEIZE doesn't trap tracee on attach */
-	if (!seize)
-		send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+		scoped_guard (write_lock_irq, &tasklist_lock) {
+			if (unlikely(task->exit_state))
+				return -EPERM;
+			if (task->ptrace)
+				return -EPERM;
 
-	spin_lock(&task->sighand->siglock);
+			task->ptrace = flags;
+			ptrace_link(task, current);
+			ptrace_set_stopped(task, seize);
+		}
+	}
 
 	/*
-	 * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
-	 * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
-	 * will be cleared if the child completes the transition or any
-	 * event which clears the group stop states happens.  We'll wait
-	 * for the transition to complete before returning from this
-	 * function.
-	 *
-	 * This hides STOPPED -> RUNNING -> TRACED transition from the
-	 * attaching thread but a different thread in the same group can
-	 * still observe the transient RUNNING state.  IOW, if another
-	 * thread's WNOHANG wait(2) on the stopped tracee races against
-	 * ATTACH, the wait(2) may fail due to the transient RUNNING.
-	 *
-	 * The following task_is_stopped() test is safe as both transitions
-	 * in and out of STOPPED are protected by siglock.
+	 * We do not bother to change retval or clear JOBCTL_TRAPPING
+	 * if wait_on_bit() was interrupted by SIGKILL. The tracer will
+	 * not return to user-mode, it will exit and clear this bit in
+	 * __ptrace_unlink() if it wasn't already cleared by the tracee;
+	 * and until then nobody can ptrace this task.
 	 */
-	if (task_is_stopped(task) &&
-	    task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
-		signal_wake_up_state(task, __TASK_STOPPED);
+	wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE);
+	proc_ptrace_connector(task, PTRACE_ATTACH);
 
-	spin_unlock(&task->sighand->siglock);
-
-	retval = 0;
-unlock_tasklist:
-	write_unlock_irq(&tasklist_lock);
-unlock_creds:
-	mutex_unlock(&task->signal->cred_guard_mutex);
-out:
-	if (!retval) {
-		wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
-			    ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
-		proc_ptrace_connector(task, PTRACE_ATTACH);
-	}
-
-	return retval;
+	return 0;
 }
 
 /**
@@ -398,7 +499,7 @@ static int ptrace_traceme(void)
 		 */
 		if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 			current->ptrace = PT_PTRACED;
-			__ptrace_link(current, current->real_parent);
+			ptrace_link(current, current->real_parent);
 		}
 	}
 	write_unlock_irq(&tasklist_lock);
@@ -461,66 +562,46 @@ static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 
 static int ptrace_detach(struct task_struct *child, unsigned int data)
 {
-	bool dead = false;
-
 	if (!valid_signal(data))
 		return -EIO;
 
 	/* Architecture-specific hardware disable .. */
 	ptrace_disable(child);
-	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-	flush_ptrace_hw_breakpoint(child);
 
 	write_lock_irq(&tasklist_lock);
 	/*
-	 * This child can be already killed. Make sure de_thread() or
-	 * our sub-thread doing do_wait() didn't do release_task() yet.
+	 * We rely on ptrace_freeze_traced(). It can't be killed and
+	 * untraced by another thread, it can't be a zombie.
 	 */
-	if (child->ptrace) {
-		child->exit_code = data;
-		dead = __ptrace_detach(current, child);
-	}
+	WARN_ON(!child->ptrace || child->exit_state);
+	/*
+	 * tasklist_lock avoids the race with wait_task_stopped(), see
+	 * the comment in ptrace_resume().
+	 */
+	child->exit_code = data;
+	__ptrace_detach(current, child);
 	write_unlock_irq(&tasklist_lock);
 
 	proc_ptrace_connector(child, PTRACE_DETACH);
-	if (unlikely(dead))
-		release_task(child);
 
 	return 0;
 }
 
 /*
  * Detach all tasks we were using ptrace on. Called with tasklist held
- * for writing, and returns with it held too. But note it can release
- * and reacquire the lock.
+ * for writing.
  */
-void exit_ptrace(struct task_struct *tracer)
-	__releases(&tasklist_lock)
-	__acquires(&tasklist_lock)
+void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
 {
 	struct task_struct *p, *n;
-	LIST_HEAD(ptrace_dead);
-
-	if (likely(list_empty(&tracer->ptraced)))
-		return;
 
 	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 		if (unlikely(p->ptrace & PT_EXITKILL))
-			send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
+			send_sig_info(SIGKILL, SEND_SIG_PRIV, p);
 
 		if (__ptrace_detach(tracer, p))
-			list_add(&p->ptrace_entry, &ptrace_dead);
-	}
-
-	write_unlock_irq(&tasklist_lock);
-	BUG_ON(!list_empty(&tracer->ptraced));
-
-	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
-		list_del_init(&p->ptrace_entry);
-		release_task(p);
+			list_add(&p->ptrace_entry, dead);
 	}
-
-	write_lock_irq(&tasklist_lock);
 }
 
 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
@@ -532,7 +613,8 @@ int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst
 		int this_len, retval;
 
 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
-		retval = access_process_vm(tsk, src, buf, this_len, 0);
+		retval = ptrace_access_vm(tsk, src, buf, this_len, FOLL_FORCE);
+
 		if (!retval) {
 			if (copied)
 				break;
@@ -559,7 +641,8 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 		if (copy_from_user(buf, src, this_len))
 			return -EFAULT;
-		retval = access_process_vm(tsk, dst, buf, this_len, 1);
+		retval = ptrace_access_vm(tsk, dst, buf, this_len,
+				FOLL_FORCE | FOLL_WRITE);
 		if (!retval) {
 			if (copied)
 				break;
@@ -576,9 +659,11 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 {
 	unsigned flags;
+	int ret;
 
-	if (data & ~(unsigned long)PTRACE_O_MASK)
-		return -EINVAL;
+	ret = check_ptrace_options(data);
+	if (ret)
+		return ret;
 
 	/* Avoid intermediate state when all opts are cleared */
 	flags = child->ptrace;
@@ -589,7 +674,7 @@ static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 	return 0;
 }
 
-static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
+static int ptrace_getsiginfo(struct task_struct *child, kernel_siginfo_t *info)
 {
 	unsigned long flags;
 	int error = -ESRCH;
@@ -597,7 +682,7 @@ static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 	if (lock_task_sighand(child, &flags)) {
 		error = -EINVAL;
 		if (likely(child->last_siginfo != NULL)) {
-			*info = *child->last_siginfo;
+			copy_siginfo(info, child->last_siginfo);
 			error = 0;
 		}
 		unlock_task_sighand(child, &flags);
@@ -605,7 +690,7 @@ static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 	return error;
 }
 
-static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
+static int ptrace_setsiginfo(struct task_struct *child, const kernel_siginfo_t *info)
 {
 	unsigned long flags;
 	int error = -ESRCH;
@@ -613,7 +698,7 @@ static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 	if (lock_task_sighand(child, &flags)) {
 		error = -EINVAL;
 		if (likely(child->last_siginfo != NULL)) {
-			*child->last_siginfo = *info;
+			copy_siginfo(child->last_siginfo, info);
 			error = 0;
 		}
 		unlock_task_sighand(child, &flags);
@@ -641,33 +726,38 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 	if (arg.nr < 0)
 		return -EINVAL;
 
+	/* Ensure arg.off fits in an unsigned long */
+	if (arg.off > ULONG_MAX)
+		return 0;
+
 	if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
 		pending = &child->signal->shared_pending;
 	else
 		pending = &child->pending;
 
 	for (i = 0; i < arg.nr; ) {
-		siginfo_t info;
-		s32 off = arg.off + i;
+		kernel_siginfo_t info;
+		unsigned long off = arg.off + i;
+		bool found = false;
 
 		spin_lock_irq(&child->sighand->siglock);
 		list_for_each_entry(q, &pending->list, list) {
 			if (!off--) {
+				found = true;
 				copy_siginfo(&info, &q->info);
 				break;
 			}
 		}
 		spin_unlock_irq(&child->sighand->siglock);
 
-		if (off >= 0) /* beyond the end of the list */
+		if (!found) /* beyond the end of the list */
 			break;
 
 #ifdef CONFIG_COMPAT
-		if (unlikely(is_compat_task())) {
+		if (unlikely(in_compat_syscall())) {
 			compat_siginfo_t __user *uinfo = compat_ptr(data);
 
-			if (copy_siginfo_to_user32(uinfo, &info) ||
-			    __put_user(info.si_code, &uinfo->si_code)) {
+			if (copy_siginfo_to_user32(uinfo, &info)) {
 				ret = -EFAULT;
 				break;
 			}
@@ -677,8 +767,7 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 		{
 			siginfo_t __user *uinfo = (siginfo_t __user *) data;
 
-			if (copy_siginfo_to_user(uinfo, &info) ||
-			    __put_user(info.si_code, &uinfo->si_code)) {
+			if (copy_siginfo_to_user(uinfo, &info)) {
 				ret = -EFAULT;
 				break;
 			}
@@ -699,12 +788,26 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 	return ret;
 }
 
-#ifdef PTRACE_SINGLESTEP
-#define is_singlestep(request)		((request) == PTRACE_SINGLESTEP)
-#else
-#define is_singlestep(request)		0
+#ifdef CONFIG_RSEQ
+static long ptrace_get_rseq_configuration(struct task_struct *task,
+					  unsigned long size, void __user *data)
+{
+	struct ptrace_rseq_configuration conf = {
+		.rseq_abi_pointer = (u64)(uintptr_t)task->rseq.usrptr,
+		.rseq_abi_size = task->rseq.len,
+		.signature = task->rseq.sig,
+		.flags = 0,
+	};
+
+	size = min_t(unsigned long, size, sizeof(conf));
+	if (copy_to_user(data, &conf, size))
+		return -EFAULT;
+	return sizeof(conf);
+}
 #endif
 
+#define is_singlestep(request)		((request) == PTRACE_SINGLESTEP)
+
 #ifdef PTRACE_SINGLEBLOCK
 #define is_singleblock(request)		((request) == PTRACE_SINGLEBLOCK)
 #else
@@ -724,15 +827,15 @@ static int ptrace_resume(struct task_struct *child, long request,
 		return -EIO;
 
 	if (request == PTRACE_SYSCALL)
-		set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+		set_task_syscall_work(child, SYSCALL_TRACE);
 	else
-		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+		clear_task_syscall_work(child, SYSCALL_TRACE);
 
-#ifdef TIF_SYSCALL_EMU
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
 	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
-		set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+		set_task_syscall_work(child, SYSCALL_EMU);
 	else
-		clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+		clear_task_syscall_work(child, SYSCALL_EMU);
 #endif
 
 	if (is_singleblock(request)) {
@@ -747,8 +850,20 @@ static int ptrace_resume(struct task_struct *child, long request,
 		user_disable_single_step(child);
 	}
 
+	/*
+	 * Change ->exit_code and ->state under siglock to avoid the race
+	 * with wait_task_stopped() in between; a non-zero ->exit_code will
+	 * wrongly look like another report from tracee.
+	 *
+	 * Note that we need siglock even if ->exit_code == data and/or this
+	 * status was not reported yet, the new status must not be cleared by
+	 * wait_task_stopped() after resume.
+	 */
+	spin_lock_irq(&child->sighand->siglock);
 	child->exit_code = data;
+	child->jobctl &= ~JOBCTL_TRACED;
 	wake_up_state(child, __TASK_TRACED);
+	spin_unlock_irq(&child->sighand->siglock);
 
 	return 0;
 }
@@ -798,14 +913,232 @@ static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
  * to ensure no machine forgets it.
  */
 EXPORT_SYMBOL_GPL(task_user_regset_view);
-#endif
+
+static unsigned long
+ptrace_get_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
+			      struct ptrace_syscall_info *info)
+{
+	unsigned long args[ARRAY_SIZE(info->entry.args)];
+	int i;
+
+	info->entry.nr = syscall_get_nr(child, regs);
+	syscall_get_arguments(child, regs, args);
+	for (i = 0; i < ARRAY_SIZE(args); i++)
+		info->entry.args[i] = args[i];
+
+	/* args is the last field in struct ptrace_syscall_info.entry */
+	return offsetofend(struct ptrace_syscall_info, entry.args);
+}
+
+static unsigned long
+ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
+				struct ptrace_syscall_info *info)
+{
+	/*
+	 * As struct ptrace_syscall_info.entry is currently a subset
+	 * of struct ptrace_syscall_info.seccomp, it makes sense to
+	 * initialize that subset using ptrace_get_syscall_info_entry().
+	 * This can be reconsidered in the future if these structures
+	 * diverge significantly enough.
+	 */
+	ptrace_get_syscall_info_entry(child, regs, info);
+	info->seccomp.ret_data = child->ptrace_message;
+
+	/*
+	 * ret_data is the last non-reserved field
+	 * in struct ptrace_syscall_info.seccomp
+	 */
+	return offsetofend(struct ptrace_syscall_info, seccomp.ret_data);
+}
+
+static unsigned long
+ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
+			     struct ptrace_syscall_info *info)
+{
+	info->exit.rval = syscall_get_error(child, regs);
+	info->exit.is_error = !!info->exit.rval;
+	if (!info->exit.is_error)
+		info->exit.rval = syscall_get_return_value(child, regs);
+
+	/* is_error is the last field in struct ptrace_syscall_info.exit */
+	return offsetofend(struct ptrace_syscall_info, exit.is_error);
+}
+
+static int
+ptrace_get_syscall_info_op(struct task_struct *child)
+{
+	/*
+	 * This does not need lock_task_sighand() to access
+	 * child->last_siginfo because ptrace_freeze_traced()
+	 * called earlier by ptrace_check_attach() ensures that
+	 * the tracee cannot go away and clear its last_siginfo.
+	 */
+	switch (child->last_siginfo ? child->last_siginfo->si_code : 0) {
+	case SIGTRAP | 0x80:
+		switch (child->ptrace_message) {
+		case PTRACE_EVENTMSG_SYSCALL_ENTRY:
+			return PTRACE_SYSCALL_INFO_ENTRY;
+		case PTRACE_EVENTMSG_SYSCALL_EXIT:
+			return PTRACE_SYSCALL_INFO_EXIT;
+		default:
+			return PTRACE_SYSCALL_INFO_NONE;
+		}
+	case SIGTRAP | (PTRACE_EVENT_SECCOMP << 8):
+		return PTRACE_SYSCALL_INFO_SECCOMP;
+	default:
+		return PTRACE_SYSCALL_INFO_NONE;
+	}
+}
+
+static int
+ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
+			void __user *datavp)
+{
+	struct pt_regs *regs = task_pt_regs(child);
+	struct ptrace_syscall_info info = {
+		.op = ptrace_get_syscall_info_op(child),
+		.arch = syscall_get_arch(child),
+		.instruction_pointer = instruction_pointer(regs),
+		.stack_pointer = user_stack_pointer(regs),
+	};
+	unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
+	unsigned long write_size;
+
+	switch (info.op) {
+	case PTRACE_SYSCALL_INFO_ENTRY:
+		actual_size = ptrace_get_syscall_info_entry(child, regs, &info);
+		break;
+	case PTRACE_SYSCALL_INFO_EXIT:
+		actual_size = ptrace_get_syscall_info_exit(child, regs, &info);
+		break;
+	case PTRACE_SYSCALL_INFO_SECCOMP:
+		actual_size = ptrace_get_syscall_info_seccomp(child, regs, &info);
+		break;
+	}
+
+	write_size = min(actual_size, user_size);
+	return copy_to_user(datavp, &info, write_size) ? -EFAULT : actual_size;
+}
+
+static int
+ptrace_set_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
+			      struct ptrace_syscall_info *info)
+{
+	unsigned long args[ARRAY_SIZE(info->entry.args)];
+	int nr = info->entry.nr;
+	int i;
+
+	/*
+	 * Check that the syscall number specified in info->entry.nr
+	 * is either a value of type "int" or a sign-extended value
+	 * of type "int".
+	 */
+	if (nr != info->entry.nr)
+		return -ERANGE;
+
+	for (i = 0; i < ARRAY_SIZE(args); i++) {
+		args[i] = info->entry.args[i];
+		/*
+		 * Check that the syscall argument specified in
+		 * info->entry.args[i] is either a value of type
+		 * "unsigned long" or a sign-extended value of type "long".
+		 */
+		if (args[i] != info->entry.args[i])
+			return -ERANGE;
+	}
+
+	syscall_set_nr(child, regs, nr);
+	/*
+	 * If the syscall number is set to -1, setting syscall arguments is not
+	 * just pointless, it would also clobber the syscall return value on
+	 * those architectures that share the same register both for the first
+	 * argument of syscall and its return value.
+	 */
+	if (nr != -1)
+		syscall_set_arguments(child, regs, args);
+
+	return 0;
+}
+
+static int
+ptrace_set_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
+				struct ptrace_syscall_info *info)
+{
+	/*
+	 * info->entry is currently a subset of info->seccomp,
+	 * info->seccomp.ret_data is currently ignored.
+	 */
+	return ptrace_set_syscall_info_entry(child, regs, info);
+}
+
+static int
+ptrace_set_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
+			     struct ptrace_syscall_info *info)
+{
+	long rval = info->exit.rval;
+
+	/*
+	 * Check that the return value specified in info->exit.rval
+	 * is either a value of type "long" or a sign-extended value
+	 * of type "long".
+	 */
+	if (rval != info->exit.rval)
+		return -ERANGE;
+
+	if (info->exit.is_error)
+		syscall_set_return_value(child, regs, rval, 0);
+	else
+		syscall_set_return_value(child, regs, 0, rval);
+
+	return 0;
+}
+
+static int
+ptrace_set_syscall_info(struct task_struct *child, unsigned long user_size,
+			const void __user *datavp)
+{
+	struct pt_regs *regs = task_pt_regs(child);
+	struct ptrace_syscall_info info;
+
+	if (user_size < sizeof(info))
+		return -EINVAL;
+
+	/*
+	 * The compatibility is tracked by info.op and info.flags: if user-space
+	 * does not instruct us to use unknown extra bits from future versions
+	 * of ptrace_syscall_info, we are not going to read them either.
+	 */
+	if (copy_from_user(&info, datavp, sizeof(info)))
+		return -EFAULT;
+
+	/* Reserved for future use. */
+	if (info.flags || info.reserved)
+		return -EINVAL;
+
+	/* Changing the type of the system call stop is not supported yet. */
+	if (ptrace_get_syscall_info_op(child) != info.op)
+		return -EINVAL;
+
+	switch (info.op) {
+	case PTRACE_SYSCALL_INFO_ENTRY:
+		return ptrace_set_syscall_info_entry(child, regs, &info);
+	case PTRACE_SYSCALL_INFO_EXIT:
+		return ptrace_set_syscall_info_exit(child, regs, &info);
+	case PTRACE_SYSCALL_INFO_SECCOMP:
+		return ptrace_set_syscall_info_seccomp(child, regs, &info);
+	default:
+		/* Other types of system call stops are not supported yet. */
+		return -EINVAL;
+	}
+}
+#endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
 
 int ptrace_request(struct task_struct *child, long request,
 		   unsigned long addr, unsigned long data)
 {
 	bool seized = child->ptrace & PT_SEIZED;
 	int ret = -EIO;
-	siginfo_t siginfo, *si;
+	kernel_siginfo_t siginfo, *si;
 	void __user *datavp = (void __user *) data;
 	unsigned long __user *datalp = datavp;
 	unsigned long flags;
@@ -839,24 +1172,31 @@ int ptrace_request(struct task_struct *child, long request,
 		break;
 
 	case PTRACE_SETSIGINFO:
-		if (copy_from_user(&siginfo, datavp, sizeof siginfo))
-			ret = -EFAULT;
-		else
+		ret = copy_siginfo_from_user(&siginfo, datavp);
+		if (!ret)
 			ret = ptrace_setsiginfo(child, &siginfo);
 		break;
 
-	case PTRACE_GETSIGMASK:
+	case PTRACE_GETSIGMASK: {
+		sigset_t *mask;
+
 		if (addr != sizeof(sigset_t)) {
 			ret = -EINVAL;
 			break;
 		}
 
-		if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
+		if (test_tsk_restore_sigmask(child))
+			mask = &child->saved_sigmask;
+		else
+			mask = &child->blocked;
+
+		if (copy_to_user(datavp, mask, sizeof(sigset_t)))
 			ret = -EFAULT;
 		else
 			ret = 0;
 
 		break;
+	}
 
 	case PTRACE_SETSIGMASK: {
 		sigset_t new_set;
@@ -882,6 +1222,8 @@ int ptrace_request(struct task_struct *child, long request,
 		child->blocked = new_set;
 		spin_unlock_irq(&child->sighand->siglock);
 
+		clear_tsk_restore_sigmask(child);
+
 		ret = 0;
 		break;
 	}
@@ -969,9 +1311,7 @@ int ptrace_request(struct task_struct *child, long request,
 	}
 #endif
 
-#ifdef PTRACE_SINGLESTEP
 	case PTRACE_SINGLESTEP:
-#endif
 #ifdef PTRACE_SINGLEBLOCK
 	case PTRACE_SINGLEBLOCK:
 #endif
@@ -984,9 +1324,8 @@ int ptrace_request(struct task_struct *child, long request,
 		return ptrace_resume(child, request, data);
 
 	case PTRACE_KILL:
-		if (child->exit_state)	/* already dead */
-			return 0;
-		return ptrace_resume(child, request, SIGKILL);
+		send_sig_info(SIGKILL, SEND_SIG_NOINFO, child);
+		return 0;
 
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 	case PTRACE_GETREGSET:
@@ -994,7 +1333,7 @@ int ptrace_request(struct task_struct *child, long request,
 		struct iovec kiov;
 		struct iovec __user *uiov = datavp;
 
-		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
+		if (!access_ok(uiov, sizeof(*uiov)))
 			return -EFAULT;
 
 		if (__get_user(kiov.iov_base, &uiov->iov_base) ||
@@ -1006,32 +1345,44 @@ int ptrace_request(struct task_struct *child, long request,
 			ret = __put_user(kiov.iov_len, &uiov->iov_len);
 		break;
 	}
+
+	case PTRACE_GET_SYSCALL_INFO:
+		ret = ptrace_get_syscall_info(child, addr, datavp);
+		break;
+
+	case PTRACE_SET_SYSCALL_INFO:
+		ret = ptrace_set_syscall_info(child, addr, datavp);
+		break;
 #endif
-	default:
+
+	case PTRACE_SECCOMP_GET_FILTER:
+		ret = seccomp_get_filter(child, addr, datavp);
 		break;
-	}
 
-	return ret;
-}
+	case PTRACE_SECCOMP_GET_METADATA:
+		ret = seccomp_get_metadata(child, addr, datavp);
+		break;
 
-static struct task_struct *ptrace_get_task_struct(pid_t pid)
-{
-	struct task_struct *child;
+#ifdef CONFIG_RSEQ
+	case PTRACE_GET_RSEQ_CONFIGURATION:
+		ret = ptrace_get_rseq_configuration(child, addr, datavp);
+		break;
+#endif
 
-	rcu_read_lock();
-	child = find_task_by_vpid(pid);
-	if (child)
-		get_task_struct(child);
-	rcu_read_unlock();
+	case PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG:
+		ret = syscall_user_dispatch_set_config(child, addr, datavp);
+		break;
 
-	if (!child)
-		return ERR_PTR(-ESRCH);
-	return child;
-}
+	case PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG:
+		ret = syscall_user_dispatch_get_config(child, addr, datavp);
+		break;
 
-#ifndef arch_ptrace_attach
-#define arch_ptrace_attach(child)	do { } while (0)
-#endif
+	default:
+		break;
+	}
+
+	return ret;
+}
 
 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 		unsigned long, data)
@@ -1041,25 +1392,17 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 
 	if (request == PTRACE_TRACEME) {
 		ret = ptrace_traceme();
-		if (!ret)
-			arch_ptrace_attach(current);
 		goto out;
 	}
 
-	child = ptrace_get_task_struct(pid);
-	if (IS_ERR(child)) {
-		ret = PTR_ERR(child);
+	child = find_get_task_by_vpid(pid);
+	if (!child) {
+		ret = -ESRCH;
 		goto out;
 	}
 
 	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
 		ret = ptrace_attach(child, request, addr, data);
-		/*
-		 * Some architectures need to do book-keeping after
-		 * a ptrace attach.
-		 */
-		if (!ret)
-			arch_ptrace_attach(child);
 		goto out_put_task_struct;
 	}
 
@@ -1084,7 +1427,7 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 	unsigned long tmp;
 	int copied;
 
-	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
+	copied = ptrace_access_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE);
 	if (copied != sizeof(tmp))
 		return -EIO;
 	return put_user(tmp, (unsigned long __user *)data);
@@ -1095,25 +1438,26 @@ int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 {
 	int copied;
 
-	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
+	copied = ptrace_access_vm(tsk, addr, &data, sizeof(data),
+			FOLL_FORCE | FOLL_WRITE);
 	return (copied == sizeof(data)) ? 0 : -EIO;
 }
 
 #if defined CONFIG_COMPAT
-#include <linux/compat.h>
 
 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 			  compat_ulong_t addr, compat_ulong_t data)
 {
 	compat_ulong_t __user *datap = compat_ptr(data);
 	compat_ulong_t word;
-	siginfo_t siginfo;
+	kernel_siginfo_t siginfo;
 	int ret;
 
 	switch (request) {
 	case PTRACE_PEEKTEXT:
 	case PTRACE_PEEKDATA:
-		ret = access_process_vm(child, addr, &word, sizeof(word), 0);
+		ret = ptrace_access_vm(child, addr, &word, sizeof(word),
+				FOLL_FORCE);
 		if (ret != sizeof(word))
 			ret = -EIO;
 		else
@@ -1122,7 +1466,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 
 	case PTRACE_POKETEXT:
 	case PTRACE_POKEDATA:
-		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
+		ret = ptrace_access_vm(child, addr, &data, sizeof(data),
+				FOLL_FORCE | FOLL_WRITE);
 		ret = (ret != sizeof(data) ? -EIO : 0);
 		break;
 
@@ -1139,11 +1484,9 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 		break;
 
 	case PTRACE_SETSIGINFO:
-		memset(&siginfo, 0, sizeof siginfo);
-		if (copy_siginfo_from_user32(
-			    &siginfo, (struct compat_siginfo __user *) datap))
-			ret = -EFAULT;
-		else
+		ret = copy_siginfo_from_user32(
+			&siginfo, (struct compat_siginfo __user *) datap);
+		if (!ret)
 			ret = ptrace_setsiginfo(child, &siginfo);
 		break;
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
@@ -1156,7 +1499,7 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 		compat_uptr_t ptr;
 		compat_size_t len;
 
-		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
+		if (!access_ok(uiov, sizeof(*uiov)))
 			return -EFAULT;
 
 		if (__get_user(ptr, &uiov->iov_base) ||
@@ -1180,8 +1523,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 	return ret;
 }
 
-asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
-				  compat_long_t addr, compat_long_t data)
+COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
+		       compat_long_t, addr, compat_long_t, data)
 {
 	struct task_struct *child;
 	long ret;
@@ -1191,20 +1534,14 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
 		goto out;
 	}
 
-	child = ptrace_get_task_struct(pid);
-	if (IS_ERR(child)) {
-		ret = PTR_ERR(child);
+	child = find_get_task_by_vpid(pid);
+	if (!child) {
+		ret = -ESRCH;
 		goto out;
 	}
 
 	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
 		ret = ptrace_attach(child, request, addr, data);
-		/*
-		 * Some architectures need to do book-keeping after
-		 * a ptrace attach.
-		 */
-		if (!ret)
-			arch_ptrace_attach(child);
 		goto out_put_task_struct;
 	}