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-rw-r--r--kernel/user_namespace.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
new file mode 100644
index 00000000000..d055d987850
--- /dev/null
+++ b/kernel/user_namespace.c
@@ -0,0 +1,87 @@
+/*
+ * 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>
+#include <linux/user_namespace.h>
+
+struct user_namespace init_user_ns = {
+ .kref = {
+ .refcount = ATOMIC_INIT(2),
+ },
+ .root_user = &root_user,
+};
+
+EXPORT_SYMBOL_GPL(init_user_ns);
+
+#ifdef CONFIG_USER_NS
+
+/*
+ * Clone a new ns copying an original user ns, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return NULL on error (failure to kmalloc), new ns otherwise
+ */
+static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
+{
+ struct user_namespace *ns;
+ struct user_struct *new_user;
+ int n;
+
+ ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
+ if (!ns)
+ return ERR_PTR(-ENOMEM);
+
+ kref_init(&ns->kref);
+
+ for (n = 0; n < UIDHASH_SZ; ++n)
+ INIT_LIST_HEAD(ns->uidhash_table + n);
+
+ /* Insert new root user. */
+ ns->root_user = alloc_uid(ns, 0);
+ if (!ns->root_user) {
+ kfree(ns);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* Reset current->user with a new one */
+ new_user = alloc_uid(ns, current->uid);
+ if (!new_user) {
+ free_uid(ns->root_user);
+ kfree(ns);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ switch_uid(new_user);
+ return ns;
+}
+
+struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
+{
+ struct user_namespace *new_ns;
+
+ BUG_ON(!old_ns);
+ get_user_ns(old_ns);
+
+ if (!(flags & CLONE_NEWUSER))
+ return old_ns;
+
+ new_ns = clone_user_ns(old_ns);
+
+ put_user_ns(old_ns);
+ return new_ns;
+}
+
+void free_user_ns(struct kref *kref)
+{
+ struct user_namespace *ns;
+
+ ns = container_of(kref, struct user_namespace, kref);
+ kfree(ns);
+}
+
+#endif /* CONFIG_USER_NS */