linux-kernel - [PATCH 0/2] wait/ptrace: assume _

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Date:	Wed, 16 Mar 2016 00:34:27 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Denys Vlasenko <dvlasenk@...hat.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Jan Kratochvil <jan.kratochvil@...hat.com>,
	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>,
	Pedro Alves <palves@...hat.com>,
	Roland McGrath <roland@...k.frob.com>,
	syzkaller@...glegroups.com, linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] wait/ptrace: assume __WALL if the child is traced

Resend. And sorry for the huge delay. The patches are the same, I only
updated the changelog a little bit.

The previous discussion was a bit confusing, but iirc/iiuc nobody really
argued with this change. In particular strace/gdb maintainers do not think
it can break something.

To remind, 1 and 2 do not depend on each other. But if we decide to not
fix the kernel, then 2/2 makes much more sense. Most init's use waitid()
which doesn't allow __WALL, so the user-space fix will be more complicated
without this patch.

And just in case let me repeat that I agree, PTRACE_TRACEME is ugly. And
probably it should not succeed after re-parenting (in fact I personally
think PTRACE_TRACEME should not even exist). But imho it is too late to
try change this ancient interface, at least I strongly dislike the idea
to add something like is_global_init() check into ptrace_traceme(). And
any "sane" restriction here can break something too, plus this will
complicate the rules.

Oleg.