Date: Sun, 11 Mar 2012 18:49:53 +0100 From: Oleg Nesterov <oleg@...hat.com> To: Djalal Harouni <tixxdz@...ndz.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Alan Cox <alan@...rguk.ukuu.org.uk> Cc: linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com, Andrew Morton <akpm@...ux-foundation.org>, Al Viro <viro@...iv.linux.org.uk>, Alexey Dobriyan <adobriyan@...il.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, Vasiliy Kulikov <segoon@...nwall.com>, Kees Cook <keescook@...omium.org>, Solar Designer <solar@...nwall.com>, WANG Cong <xiyou.wangcong@...il.com>, James Morris <james.l.morris@...cle.com>, linux-security-module@...r.kernel.org, linux-fsdevel@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>, Ingo Molnar <mingo@...e.hu>, Stephen Wilson <wilsons@...rt.ca>, "Jason A. Donenfeld" <Jason@...c4.com> Subject: self_exec_id/parent_exec_id && CLONE_PARENT (change subject) On 03/11, Oleg Nesterov wrote: > > Well, I don't think it is right to add this counter into task_struct. > > It should be per-process, signal_struct makes more sense. Or may be > mm_struct. > > Btw this is also true for parent_exec_id/self_exec_id, but this is > another story. In fact I think it would be nice to kill parent_exec_id/self_exec_id. Afaics, this only problem is clone(CLONE_PARENT | SIGXXX). I expect the answer is "no, can break existing applications", but I'll ask anyway. Can't we change this? IOW, can't we modify copy_process - p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); + p->exit_signal = + (clone_flags & CLONE_THREAD) ? -1 : + (clobe_flags & CLONE_PARENT) ? current->group_leader->exit_signal : + (clone_flags & CSIGNAL); (or simply use SIGCHLD instead of group_leader->exit_signal). Then we can kill parent_exec_id/self_exec_id if me modify de_thread() to set ->exit_signal = SIGCHLD for every child. I am also asking because the change above looks like the fix to me. The child must not control its ->exit_signal, it is the parent who decides which signal the child should use for notification. And to me, clone(CLONE_PARENT | SIGXXX) looks like a violation of rule above. Oleg.
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