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>
This commit is contained in:
Oleg Nesterov 2008-04-30 00:53:15 -07:00 коммит произвёл Linus Torvalds
Родитель 33e9fc7d01
Коммит 00cd5c37af
1 изменённых файлов: 0 добавлений и 8 удалений

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@ -168,8 +168,6 @@ int ptrace_attach(struct task_struct *task)
audit_ptrace(task);
retval = -EPERM;
if (task->pid <= 1)
goto out;
if (same_thread_group(task, current))
goto out;
@ -521,12 +519,6 @@ struct task_struct *ptrace_get_task_struct(pid_t pid)
{
struct task_struct *child;
/*
* Tracing init is not allowed.
*/
if (pid == 1)
return ERR_PTR(-EPERM);
read_lock(&tasklist_lock);
child = find_task_by_vpid(pid);
if (child)