Revert "user namespace: Add function that checks if the UID map is defined"

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4O25G
CVE: NA

--------------------------------

This reverts commit 44a41d57.
Signed-off-by: NZhang Tianxing <zhangtianxing3@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Acked-by: Xiu Jianfeng<xiujianfeng@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

include/linux/user_namespace.h

@@ -141,7 +141,6 @@ extern bool in_userns(const struct user_namespace *ancestor,
 		       const struct user_namespace *child);
 extern bool current_in_userns(const struct user_namespace *target_ns);
 struct ns_common *ns_get_owner(struct ns_common *ns);
-extern bool userns_set_uidmap(const struct user_namespace *ns);
 #else
 
 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
@@ -186,11 +185,6 @@ static inline struct ns_common *ns_get_owner(struct ns_common *ns)
 {
 	return ERR_PTR(-EPERM);
 }
-
-static inline bool userns_set_uidmap(const struct user_namespace *ns)
-{
-	return true;
-}
 #endif
 
 #endif /* _LINUX_USER_H */

kernel/user_namespace.c

@@ -1291,17 +1291,6 @@ bool current_in_userns(const struct user_namespace *target_ns)
 }
 EXPORT_SYMBOL(current_in_userns);
 
-bool userns_set_uidmap(const struct user_namespace *ns)
-{
-	bool mapping_defined;
-
-	mutex_lock(&userns_state_mutex);
-	mapping_defined = ns->uid_map.nr_extents != 0;
-	mutex_unlock(&userns_state_mutex);
-
-	return mapping_defined;
-}
-
 static inline struct user_namespace *to_user_ns(struct ns_common *ns)
 {
 	return container_of(ns, struct user_namespace, ns);