MySQL繞過授予information_schema中對(duì)象時(shí)報(bào)ERROR 1044錯(cuò)誤怎么解決

本篇文章為大家展示了MySQL繞過授予information_schema中對(duì)象時(shí)報(bào)ERROR 1044錯(cuò)誤怎么解決，內(nèi)容簡(jiǎn)明扼要并且容易理解，絕對(duì)能使你眼前一亮，通過這篇文章的詳細(xì)介紹希望你能有所收獲。

因?yàn)镸ySQL的很多功能都依賴主鍵，我想用zabbix用戶，來監(jiān)控業(yè)務(wù)數(shù)據(jù)庫(kù)的所有表，是否都建立了主鍵。

監(jiān)控的語句是：

FROM  information_schema.tables t1 
    LEFT OUTER JOIN information_schema.table_constraints t2 
          ON t1.table_schema = t2.table_schema 
            AND t1.table_name = t2.table_name 
            AND t2.constraint_name IN ( 'PRIMARY' ) 
WHERE t2.table_name IS NULL 
    AND t1.table_schema NOT IN ( 'information_schema', 'myawr', 'mysql', 
                  'performance_schema', 
                  'slowlog', 'sys', 'test' ) 
    AND t1.table_type = 'BASE TABLE' 

但是我不希望zabbix用戶，能讀取業(yè)務(wù)庫(kù)的數(shù)據(jù)。一旦不給zabbix用戶讀取業(yè)務(wù)庫(kù)數(shù)據(jù)的權(quán)限，那么information_schema.TABLES 和 information_schema.TABLE_CONSTRAINTS 就不包含業(yè)務(wù)庫(kù)的表信息了，也就統(tǒng)計(jì)不出來業(yè)務(wù)庫(kù)的表是否有建主鍵。有沒有什么辦法，即讓zabbix不能讀取業(yè)務(wù)庫(kù)數(shù)據(jù)，又能監(jiān)控是否業(yè)務(wù)庫(kù)的表沒有建立主鍵？

首先，我們要知道一個(gè)事實(shí)：information_schema下的視圖沒法授權(quán)給某個(gè)用戶。如下所示

mysql> GRANT SELECT ON information_schema.TABLES TO test@'%';
ERROR 1044 (42000): Access denied for user 'root'@'localhost' to database 'information_schema'

關(guān)于這個(gè)問題，可以參考mos上這篇文章：Why Setting Privileges on INFORMATION_SCHEMA does not Work (文檔 ID 1941558.1)

APPLIES TO:

MySQL Server - Version 5.6 and later

Information in this document applies to any platform.

GOAL

To determine how MySQL privileges work for INFORMATION_SCHEMA.

SOLUTION

A simple GRANT statement would be something like:

mysql> grant select,execute on information_schema.* to 'dbadm'@'localhost';

ERROR 1044 (42000): Access denied for user 'root'@'localhost' to database 'information_schema'

The error indicates that the super user does not have the privileges to change the information_schema access privileges.

Which seems to go against what is normally the case for the root account which has SUPER privileges.

The reason for this error is that the information_schema database is actually a virtual database that is built when the service is started.

It is made up of tables and views designed to keep track of the server meta-data, that is, details of all the tables, procedures etc. in the database server.

So looking specifically at the above command, there is an attempt to add SELECT and EXECUTE privileges to this specialised database.

The SELECT option is not required however, because all users have the ability to read the tables in the information_schema database, so this is redundant.

The EXECUTE option does not make sense, because you are not allowed to create procedures in this special database.

There is also no capability to modify the tables in terms of INSERT, UPDATE, DELETE etc., so privileges are hard coded instead of managed per user.

那么怎么解決這個(gè)授權(quán)問題呢？ 直接授權(quán)不行，那么我們只能繞過這個(gè)問題，間接實(shí)現(xiàn)授權(quán)。思路如下：首先創(chuàng)建一個(gè)存儲(chǔ)過程（用戶數(shù)據(jù)庫(kù)），此存儲(chǔ)過程找出沒有主鍵的表的數(shù)量，然后將其授予test用戶。

DELIMITER //
CREATE DEFINER=`root`@`localhost` PROCEDURE `moitor_without_primarykey`()
BEGIN
   SELECT COUNT(*) 
FROM  information_schema.tables t1 
    LEFT OUTER JOIN information_schema.table_constraints t2 
          ON t1.table_schema = t2.table_schema 
            AND t1.table_name = t2.table_name 
            AND t2.constraint_name IN ( 'PRIMARY' ) 
WHERE t2.table_name IS NULL 
    AND t1.table_schema NOT IN ( 'information_schema', 'myawr', 'mysql', 
                  'performance_schema', 
                  'slowlog', 'sys', 'test' ) 
    AND t1.table_type = 'BASE TABLE';
END //
DELIMITER ;
 
 
mysql> GRANT EXECUTE ON PROCEDURE moitor_without_primarykey TO 'test'@'%';
Query OK, 0 rows affected (0.02 sec)

此時(shí)test就能間接的去查詢information_schema下的對(duì)象了。

mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| test@%     |
+----------------+
1 row in set (0.00 sec)
 
mysql> call moitor_without_primarykey;
+----------+
| COUNT(*) |
+----------+
|    6 |
+----------+
1 row in set (0.02 sec)
 
Query OK, 0 rows affected (0.02 sec)

查看test用戶的權(quán)限。

mysql> show grants for test@'%';
+-------------------------------------------------------------------------------+
| Grants for test@%                               |
+-------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO `test`@`%`                       |
| GRANT EXECUTE ON PROCEDURE `zabbix`.`moitor_without_primarykey` TO `test`@`%` |
+-------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

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