MDEV-24040 Named pipe permission issue

Tighten access control - deny FILE_CREATE_PIPE_INSTANCE permission to
everyone except current user (the one that runs mysqld)

sql/mysqld.cc

@@ -2582,6 +2582,62 @@ static MYSQL_SOCKET activate_tcp_port(uint port)
   DBUG_RETURN(ip_sock);
 }
 
+#ifdef _WIN32
+/*
+  Create a security descriptor for pipe.
+  - Use low integrity level, so that it is possible to connect
+  from any process.
+  - Give current user read/write access to pipe.
+  - Give Everyone read/write access to pipe minus FILE_CREATE_PIPE_INSTANCE
+*/
+static void init_pipe_security_descriptor()
+{
+#define SDDL_FMT "S:(ML;; NW;;; LW) D:(A;; 0x%08x;;; WD)(A;; FRFW;;; %s)"
+#define EVERYONE_PIPE_ACCESS_MASK                                             \
+  (FILE_READ_DATA | FILE_READ_EA | FILE_READ_ATTRIBUTES | READ_CONTROL |      \
+   SYNCHRONIZE | FILE_WRITE_DATA | FILE_WRITE_EA | FILE_WRITE_ATTRIBUTES)
+
+  /*
+    Figure out SID of the user that runs the server, then create SDDL string
+    for pipe permissions, and convert it to the security descriptor.
+  */
+  char sddl_string[sizeof(SDDL_FMT) + 8 + SECURITY_MAX_SID_STRING_CHARACTERS];
+  struct
+  {
+    TOKEN_USER token_user;
+    BYTE buffer[SECURITY_MAX_SID_SIZE];
+  } token_buffer;
+  HANDLE token;
+  DWORD tmp;
+
+  if (!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &token))
+    goto fail;
+
+  if (!GetTokenInformation(token, TokenUser, &token_buffer,
+                           (DWORD) sizeof(token_buffer), &tmp))
+    goto fail;
+
+  CloseHandle(token);
+
+  char *current_user_string_sid;
+  if (!ConvertSidToStringSid(token_buffer.token_user.User.Sid,
+                             &current_user_string_sid))
+    goto fail;
+
+  snprintf(sddl_string, sizeof(sddl_string), SDDL_FMT,
+           EVERYONE_PIPE_ACCESS_MASK, current_user_string_sid);
+  LocalFree(current_user_string_sid);
+
+  if (ConvertStringSecurityDescriptorToSecurityDescriptor(sddl_string,
+      SDDL_REVISION_1, &saPipeSecurity.lpSecurityDescriptor, 0))
+    return;
+
+fail:
+  sql_perror("Can't start server : Initialize security descriptor");
+  unireg_abort(1);
+}
+#endif
+
 static void network_init(void)
 {
 #ifdef HAVE_SYS_UN_H
@@ -2619,19 +2675,7 @@ static void network_init(void)
 
     strxnmov(pipe_name, sizeof(pipe_name)-1, "\\\\.\\pipe\\",
 	     mysqld_unix_port, NullS);
-    /*
-      Create a security descriptor for pipe.
-      - Use low integrity level, so that it is possible to connect
-      from any process.
-      - Give Everyone read/write access to pipe.
-    */
-    if (!ConvertStringSecurityDescriptorToSecurityDescriptor(
-         "S:(ML;; NW;;; LW) D:(A;; FRFW;;; WD)",
-         SDDL_REVISION_1, &saPipeSecurity.lpSecurityDescriptor, NULL))
-    {
-      sql_perror("Can't start server : Initialize security descriptor");
-      unireg_abort(1);
-    }
+    init_pipe_security_descriptor();
     saPipeSecurity.nLength = sizeof(SECURITY_ATTRIBUTES);
     saPipeSecurity.bInheritHandle = FALSE;
     if ((hPipe= CreateNamedPipe(pipe_name,