[PATCH] namespaces: add nsproxy

This patch adds a nsproxy structure to the task struct.  Later patches will
move the fs namespace pointer into this structure, and introduce a new utsname
namespace into the nsproxy.

The vserver and openvz functionality, then, would be implemented in large part
by virtualizing/isolating more and more resources into namespaces, each
contained in the nsproxy.

[akpm@osdl.org: build fix]
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Andrey Savochkin <saw@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 77 insertions, 0 deletions

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
new file mode 100644
index 000000000000..ad9508865473
--- /dev/null
+++ b/kernel/nsproxy.c
@@ -0,0 +1,77 @@
+/*
+ *  Copyright (C) 2006 IBM Corporation
+ *
+ *  Author: Serge Hallyn <serue@us.ibm.com>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License as
+ *  published by the Free Software Foundation, version 2 of the
+ *  License.
+ */
+
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/nsproxy.h>
+
+static inline void get_nsproxy(struct nsproxy *ns)
+{
+        atomic_inc(&ns->count);
+}
+
+void get_task_namespaces(struct task_struct *tsk)
+{
+        struct nsproxy *ns = tsk->nsproxy;
+        if (ns) {
+                get_nsproxy(ns);
+        }
+}
+
+/*
+ * creates a copy of "orig" with refcount 1.
+ * This does not grab references to the contained namespaces,
+ * so that needs to be done by dup_namespaces.
+ */
+static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
+{
+        struct nsproxy *ns;
+
+        ns = kmalloc(sizeof(struct nsproxy), GFP_KERNEL);
+        if (ns) {
+                memcpy(ns, orig, sizeof(struct nsproxy));
+                atomic_set(&ns->count, 1);
+        }
+        return ns;
+}
+
+/*
+ * copies the nsproxy, setting refcount to 1, and grabbing a
+ * reference to all contained namespaces.  Called from
+ * sys_unshare()
+ */
+struct nsproxy *dup_namespaces(struct nsproxy *orig)
+{
+        struct nsproxy *ns = clone_namespaces(orig);
+
+        return ns;
+}
+
+/*
+ * called from clone.  This now handles copy for nsproxy and all
+ * namespaces therein.
+ */
+int copy_namespaces(int flags, struct task_struct *tsk)
+{
+        struct nsproxy *old_ns = tsk->nsproxy;
+
+        if (!old_ns)
+                return 0;
+
+        get_nsproxy(old_ns);
+
+        return 0;
+}
+
+void free_nsproxy(struct nsproxy *ns)
+{
+                kfree(ns);
+}