linux-kernel - Re: [PATCH] Deny CLONE_PARENT|CLONE

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Message-ID: <20090728190654.GA5806@us.ibm.com>
Date:	Tue, 28 Jul 2009 12:06:54 -0700
From:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
To:	"Serge E. Hallyn" <serue@...ibm.com>
Cc:	Andrew Morton <akpm@...l.org>, oleg@...hat.com, roland@...hat.com,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Oren Laadan <orenl@...columbia.edu>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Containers <containers@...ts.linux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Deny CLONE_PARENT|CLONE_NEWPID combination

Serge E. Hallyn [serue@...ibm.com] wrote:
| Quoting Sukadev Bhattiprolu (sukadev@...ux.vnet.ibm.com):
| > 
| > Deny CLONE_PARENT|CLONE_NEWPID combination.
| > 
| > CLONE_PARENT was used to implement an older threading model.  For consistency
| > with the CLONE_THREAD check in copy_pid_ns(), disable CLONE_PARENT and
| > CLONE_SIGHAND with CLONE_NEWPID, at least until the required semantics of
| > the pid namespaces are clear.
| > 
| > Changelog[v3]:
| > 	Remove CLONE_SIGHAND and for now only fail CLONE_NEWPID|CLONE_PARENT.
| 
| (FWIW your patch description does not reflect this...)

You are right. Here is the patch with updated description.
---

Deny CLONE_PARENT|CLONE_NEWPID|CLONE_SIGHAND combination.

CLONE_PARENT was used to implement an older threading model.  For consistency
with the CLONE_THREAD check in copy_pid_ns(), disable CLONE_PARENT with
CLONE_NEWPID, at least until the required semantics of pid namespaces are
clear.

Changelog[v3]:
	Remove CLONE_SIGHAND and for now only fail CLONE_NEWPID|CLONE_PARENT.
Changelog[v2]:
	[Eric Biederman] Disable CLONE_SIGHAND also ?

Signed-off-by: Sukadev Bhattiprolu <sukadev@...ibm.com>
Acked-by: Roland McGrath <roland@...hat.com>
Acked-by: Serge Hallyn <serue@...ibm.com>
---
 kernel/pid_namespace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-mmotm/kernel/pid_namespace.c
===================================================================
--- linux-mmotm.orig/kernel/pid_namespace.c	2009-07-16 10:03:01.000000000 -0700
+++ linux-mmotm/kernel/pid_namespace.c	2009-07-16 11:37:24.000000000 -0700
@@ -118,7 +118,7 @@
 {
 	if (!(flags & CLONE_NEWPID))
 		return get_pid_ns(old_ns);
-	if (flags & CLONE_THREAD)
+	if (flags & (CLONE_THREAD|CLONE_PARENT))
 		return ERR_PTR(-EINVAL);
 	return create_pid_namespace(old_ns);
 }
--
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