From ecd4c29c2aef8c3bd36136a0509144d9ef12016f Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@clickhouse.com>
Date: Sat, 17 Sep 2022 03:55:39 +0200
Subject: [PATCH] Forbid invocations of dlopen

---
 programs/main.cpp | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/programs/main.cpp b/programs/main.cpp
index fef0ad688e2..cc21015f5a7 100644
--- a/programs/main.cpp
+++ b/programs/main.cpp
@@ -402,6 +402,36 @@ void checkHarmfulEnvironmentVariables(char ** argv)
 }
 
 
+/// Don't allow dlopen in the main ClickHouse binary, because it is harmful and insecure.
+/// We don't use it. But it can be used by some libraries for implementation of "plugins".
+/// We absolutely discourage the ancient technique of loading
+/// 3rd-party uncontrolled dangerous libraries into the process address space,
+/// because it is insane.
+
+extern "C"
+{
+    void * dlopen(const char *, int)
+    {
+        return nullptr;
+    }
+
+    void * dlmopen(long, const char *, int)
+    {
+        return nullptr;
+    }
+
+    int dlclose(void *)
+    {
+        return 0;
+    }
+
+    const char * dlerror()
+    {
+        return "ClickHouse does not allow dynamic library loading";
+    }
+}
+
+
 /// This allows to implement assert to forbid initialization of a class in static constructors.
 /// Usage:
 ///