Commit 00cd5c37 authored Apr 30, 2008 by Oleg Nesterov Committed by Linus Torvalds Apr 30, 2008

ptrace: permit ptracing of /sbin/init

Afaics, currently there are no kernel problems with ptracing init, it can't
lose SIGNAL_UNKILLABLE flag and be killed/stopped by accident.

The ability to strace/debug init can be very useful if you try to figure out
why it does not work as expected.

However, admin should know what he does, "gdb /sbin/init 1" stops init, it
can't reap orphaned zombies or take care of /etc/inittab until continued.  It
is even possible to crash init (and thus the whole system) if you wish,
ptracer has full control.

See also the long discussion: http://marc.info/?t=120628018600001



Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 33e9fc7d

kernel/ptrace.c

+0 −8

Original line number	Original line	Diff line number	Diff line
	@@ -168,8 +168,6 @@ int ptrace_attach(struct task_struct *task)
	audit_ptrace(task);		audit_ptrace(task);

	retval = -EPERM;		retval = -EPERM;
	if (task->pid <= 1)
	goto out;
	if (same_thread_group(task, current))		if (same_thread_group(task, current))
	goto out;		goto out;

	@@ -521,12 +519,6 @@ struct task_struct *ptrace_get_task_struct(pid_t pid)
	{		{
	struct task_struct *child;		struct task_struct *child;

	/*
	* Tracing init is not allowed.
	*/
	if (pid == 1)
	return ERR_PTR(-EPERM);

	read_lock(&tasklist_lock);		read_lock(&tasklist_lock);
	child = find_task_by_vpid(pid);		child = find_task_by_vpid(pid);
	if (child)		if (child)