[RFC][PATCH 2/5] mqueue namespace: add unshare support

[Dave Hansen <dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

From: Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>

This patch includes the mqueue namespace in the nsproxy object. It  
also adds the support of unshare() and clone() with a new clone flag. 

It's totally harmless for the moment because the current code still 
uses the default mqueue namespace object 'init_mq_ns' 

Changes since v6 Mar 05, 2008: 

	* dropped new clone flag CLONE_NEWMQ and used CLONE_NEWIPC 
	  instead

Changes since v5 Feb 28, 2008: 

	* fix typo in create_new_namespaces()

Changes since v4: 

	* remove CLONE_NEWNS enforcement. stalled user mounts are 
	  handled in the fs ops.

Signed-off-by: Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>
---

 linux-2.6.git-dave/include/linux/init_task.h    |    2 +
 linux-2.6.git-dave/include/linux/mq_namespace.h |    1 
 linux-2.6.git-dave/include/linux/nsproxy.h      |    2 +
 linux-2.6.git-dave/ipc/mq_namespace.c           |   36 +++++++++++++++++++++++-
 linux-2.6.git-dave/kernel/nsproxy.c             |   11 +++++++
 5 files changed, 51 insertions(+), 1 deletion(-)

diff -puN include/linux/init_task.h~mq_namespace-add-mq_namespace-to-nsproxy include/linux/init_task.h
--- linux-2.6.git/include/linux/init_task.h~mq_namespace-add-mq_namespace-to-nsproxy	2008-06-24 12:03:17.000000000 -0700
+++ linux-2.6.git-dave/include/linux/init_task.h	2008-06-24 12:03:17.000000000 -0700
@@ -10,6 +10,7 @@
 #include <linux/user_namespace.h>
 #include <linux/securebits.h>
 #include <net/net_namespace.h>
+#include <linux/mq_namespace.h>
 
 extern struct files_struct init_files;
 
@@ -58,6 +59,7 @@ extern struct nsproxy init_nsproxy;
 	INIT_NET_NS(net_ns)                                             \
 	INIT_IPC_NS(ipc_ns)						\
 	.user_ns	= &init_user_ns,				\
+	INIT_MQ_NS(mq_ns)						\
 }
 
 #define INIT_SIGHAND(sighand) {						\
diff -puN include/linux/mq_namespace.h~mq_namespace-add-mq_namespace-to-nsproxy include/linux/mq_namespace.h
--- linux-2.6.git/include/linux/mq_namespace.h~mq_namespace-add-mq_namespace-to-nsproxy	2008-06-24 12:03:17.000000000 -0700
+++ linux-2.6.git-dave/include/linux/mq_namespace.h	2008-06-24 12:03:17.000000000 -0700
@@ -2,6 +2,7 @@
 #define _LINUX_MQ_NAMESPACE_H
 
 #include <linux/kref.h>
+#include <linux/err.h>
 
 struct vfsmount;
 
diff -puN include/linux/nsproxy.h~mq_namespace-add-mq_namespace-to-nsproxy include/linux/nsproxy.h
--- linux-2.6.git/include/linux/nsproxy.h~mq_namespace-add-mq_namespace-to-nsproxy	2008-06-24 12:03:17.000000000 -0700
+++ linux-2.6.git-dave/include/linux/nsproxy.h	2008-06-24 12:03:17.000000000 -0700
@@ -8,6 +8,7 @@ struct mnt_namespace;
 struct uts_namespace;
 struct ipc_namespace;
 struct pid_namespace;
+struct mq_namespace;
 
 /*
  * A structure to contain pointers to all per-process
@@ -29,6 +30,7 @@ struct nsproxy {
 	struct pid_namespace *pid_ns;
 	struct user_namespace *user_ns;
 	struct net 	     *net_ns;
+	struct mq_namespace *mq_ns;
 };
 extern struct nsproxy init_nsproxy;
 
diff -puN ipc/mq_namespace.c~mq_namespace-add-mq_namespace-to-nsproxy ipc/mq_namespace.c
--- linux-2.6.git/ipc/mq_namespace.c~mq_namespace-add-mq_namespace-to-nsproxy	2008-06-24 12:03:17.000000000 -0700
+++ linux-2.6.git-dave/ipc/mq_namespace.c	2008-06-24 12:03:17.000000000 -0700
@@ -10,14 +10,48 @@
  */
 
 #include <linux/mq_namespace.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+
+static struct mq_namespace *clone_mq_ns(struct mq_namespace *old_ns)
+{
+	struct mq_namespace *mq_ns;
+
+	mq_ns = kmalloc(sizeof(struct mq_namespace), GFP_KERNEL);
+	if (!mq_ns)
+		return ERR_PTR(-ENOMEM);
+
+	kref_init(&mq_ns->kref);
+	mq_ns->queues_count	= 0;
+	mq_ns->queues_max	= DFLT_QUEUESMAX;
+	mq_ns->msg_max		= DFLT_MSGMAX;
+	mq_ns->msgsize_max	= DFLT_MSGSIZEMAX;
+	mq_ns->mnt		= NULL;
+	return mq_ns;
+}
 
 struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
 				struct mq_namespace *old_ns)
 {
+	struct mq_namespace *mq_ns;
+
 	BUG_ON(!old_ns);
-	return get_mq_ns(old_ns);
+	get_mq_ns(old_ns);
+
+	if (!(clone_flags & CLONE_NEWIPC))
+		return old_ns;
+
+	mq_ns = clone_mq_ns(old_ns);
+
+	put_mq_ns(old_ns);
+	return mq_ns;
 }
 
 void free_mq_ns(struct kref *kref)
 {
+	struct mq_namespace *ns;
+
+	ns = container_of(kref, struct mq_namespace, kref);
+	kfree(ns);
 }
diff -puN kernel/nsproxy.c~mq_namespace-add-mq_namespace-to-nsproxy kernel/nsproxy.c
--- linux-2.6.git/kernel/nsproxy.c~mq_namespace-add-mq_namespace-to-nsproxy	2008-06-24 12:03:17.000000000 -0700
+++ linux-2.6.git-dave/kernel/nsproxy.c	2008-06-24 12:03:17.000000000 -0700
@@ -93,8 +93,17 @@ static struct nsproxy *create_new_namesp
 		goto out_net;
 	}
 
+	new_nsp->mq_ns = copy_mq_ns(flags, tsk->nsproxy->mq_ns);
+	if (IS_ERR(new_nsp->mq_ns)) {
+		err = PTR_ERR(new_nsp->mq_ns);
+		goto out_mq;
+	}
+
 	return new_nsp;
 
+out_mq:
+	if (new_nsp->net_ns)
+		put_net(new_nsp->net_ns);
 out_net:
 	if (new_nsp->user_ns)
 		put_user_ns(new_nsp->user_ns);
@@ -182,6 +191,8 @@ void free_nsproxy(struct nsproxy *ns)
 		put_pid_ns(ns->pid_ns);
 	if (ns->user_ns)
 		put_user_ns(ns->user_ns);
+	if (ns->mq_ns)
+		put_mq_ns(ns->mq_ns);
 	put_net(ns->net_ns);
 	kmem_cache_free(nsproxy_cachep, ns);
 }
_