1 files changed, 139 insertions, 0 deletions
diff --git a/kernel/utsname.c b/kernel/utsname.c
new file mode 100644
index 000000000..831ea7108
--- /dev/null
+++ b/kernel/utsname.c
@@ -0,0 +1,139 @@
+/*
+ *  Copyright (C) 2004 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/export.h>
+#include <linux/uts.h>
+#include <linux/utsname.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/user_namespace.h>
+#include <linux/proc_ns.h>
+
+static struct uts_namespace *create_uts_ns(void)
+{
+	struct uts_namespace *uts_ns;
+
+	uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
+	if (uts_ns)
+		kref_init(&uts_ns->kref);
+	return uts_ns;
+}
+
+/*
+ * Clone a new ns copying an original utsname, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
+ */
+static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
+					  struct uts_namespace *old_ns)
+{
+	struct uts_namespace *ns;
+	int err;
+
+	ns = create_uts_ns();
+	if (!ns)
+		return ERR_PTR(-ENOMEM);
+
+	err = ns_alloc_inum(&ns->ns);
+	if (err) {
+		kfree(ns);
+		return ERR_PTR(err);
+	}
+
+	ns->ns.ops = &utsns_operations;
+
+	down_read(&uts_sem);
+	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+	ns->user_ns = get_user_ns(user_ns);
+	up_read(&uts_sem);
+	return ns;
+}
+
+/*
+ * Copy task tsk's utsname namespace, or clone it if flags
+ * specifies CLONE_NEWUTS.  In latter case, changes to the
+ * utsname of this process won't be seen by parent, and vice
+ * versa.
+ */
+struct uts_namespace *copy_utsname(unsigned long flags,
+	struct user_namespace *user_ns, struct uts_namespace *old_ns)
+{
+	struct uts_namespace *new_ns;
+
+	BUG_ON(!old_ns);
+	get_uts_ns(old_ns);
+
+	if (!(flags & CLONE_NEWUTS))
+		return old_ns;
+
+	new_ns = clone_uts_ns(user_ns, old_ns);
+
+	put_uts_ns(old_ns);
+	return new_ns;
+}
+
+void free_uts_ns(struct kref *kref)
+{
+	struct uts_namespace *ns;
+
+	ns = container_of(kref, struct uts_namespace, kref);
+	put_user_ns(ns->user_ns);
+	ns_free_inum(&ns->ns);
+	kfree(ns);
+}
+
+static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct uts_namespace, ns);
+}
+
+static struct ns_common *utsns_get(struct task_struct *task)
+{
+	struct uts_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->uts_ns;
+		get_uts_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static void utsns_put(struct ns_common *ns)
+{
+	put_uts_ns(to_uts_ns(ns));
+}
+
+static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+	struct uts_namespace *ns = to_uts_ns(new);
+
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+		return -EPERM;
+
+	get_uts_ns(ns);
+	put_uts_ns(nsproxy->uts_ns);
+	nsproxy->uts_ns = ns;
+	return 0;
+}
+
+const struct proc_ns_operations utsns_operations = {
+	.name		= "uts",
+	.type		= CLONE_NEWUTS,
+	.get		= utsns_get,
+	.put		= utsns_put,
+	.install	= utsns_install,
+};