Revert "Merge branch 'master' of https://github.com/yangyangduo/securityguards"

This reverts commit d45ac716bf75f7ee5ee597838526dfa04d8998c9, reversing
changes made to e2b872ec77a1b8019f1a499f9de3ffe6f03ae982.
Revert 491a0b6..1f63d84

This rolls back to commit 491a0b60b5b4db8f26b8777a824567201817b8a2.