[PATCH RFC 22/31] net: Add network namespace clone support.

[Eric W. Biederman]

From: Eric W. Biederman <ebiederm at xmission.com> - unquoted

This patch allows you to create a new network namespace
using sys_clone(...).

Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
---
 include/linux/sched.h    |    1 +
 kernel/nsproxy.c         |   11 +++++++++++
 net/core/net_namespace.c |   38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+), 0 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4463735..9e0f91a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -26,6 +26,7 @@
 #define CLONE_STOPPED		0x02000000	/* Start in stopped state */
 #define CLONE_NEWUTS		0x04000000	/* New utsname group? */
 #define CLONE_NEWIPC		0x08000000	/* New ipcs */
+#define CLONE_NEWNET		0x20000000	/* New network namespace */
 
 /*
  * Scheduling policies
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 4f3c95a..7861c4c 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -20,6 +20,7 @@
 #include <linux/mnt_namespace.h>
 #include <linux/utsname.h>
 #include <linux/pid_namespace.h>
+#include <net/net_namespace.h>
 
 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 EXPORT_SYMBOL_GPL(init_nsproxy);
@@ -70,6 +71,7 @@ struct nsproxy *dup_namespaces(struct nsproxy *orig)
 			get_ipc_ns(ns->ipc_ns);
 		if (ns->pid_ns)
 			get_pid_ns(ns->pid_ns);
+		get_net(ns->net_ns);
 	}
 
 	return ns;
@@ -117,10 +119,18 @@ int copy_namespaces(int flags, struct task_struct *tsk)
 	if (err)
 		goto out_pid;
 
+	err = copy_net(flags, tsk);
+	if (err)
+		goto out_net;
+
 out:
 	put_nsproxy(old_ns);
 	return err;
 
+out_net:
+	if (new_ns->pid_ns)
+		put_pid_ns(new_ns->pid_ns);
+
 out_pid:
 	if (new_ns->ipc_ns)
 		put_ipc_ns(new_ns->ipc_ns);
@@ -146,5 +156,6 @@ void free_nsproxy(struct nsproxy *ns)
 		put_ipc_ns(ns->ipc_ns);
 	if (ns->pid_ns)
 		put_pid_ns(ns->pid_ns);
+	put_net(ns->net_ns);
 	kfree(ns);
 }
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 93e3879..cc56105 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -175,6 +175,44 @@ out_undo:
 	goto out;
 }
 
+int copy_net(int flags, struct task_struct *tsk)
+{
+	net_t old_net = tsk->nsproxy->net_ns;
+	net_t new_net;
+	int err;
+
+	get_net(old_net);
+
+	if (!(flags & CLONE_NEWNET))
+		return 0;
+
+	err = -EPERM;
+	if (!capable(CAP_SYS_ADMIN))
+		goto out;
+
+	err = -ENOMEM;
+	new_net = net_alloc();
+	if (null_net(new_net))
+		goto out;
+
+	mutex_lock(&net_mutex);
+	err = setup_net(new_net);
+	if (err)
+		goto out_unlock;
+
+	net_lock();
+	net_list_append(new_net);
+	net_unlock();
+
+	tsk->nsproxy->net_ns = new_net;
+
+out_unlock:
+	mutex_unlock(&net_mutex);
+out:
+	put_net(old_net);
+	return err;
+}
+
 void pernet_modcopy(void *pnetdst, const void *src, unsigned long size)
 {
 	net_t net;
-- 
1.4.4.1.g278f