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-rw-r--r--kernel/user_namespace.c46
1 files changed, 45 insertions, 1 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 3d79642..89a27e8 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -21,6 +21,45 @@ 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 NULL;
+
+ 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 NULL;
+ }
+
+ /* 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 NULL;
+ }
+
+ switch_uid(new_user);
+ return ns;
+}
+
struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
{
struct user_namespace *new_ns;
@@ -28,7 +67,12 @@ struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
BUG_ON(!old_ns);
get_user_ns(old_ns);
- new_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;
}
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