技术分享 | 安全地无密码登录 MySQL

作者:丹尼尔·古斯曼布尔戈斯
翻译:管长龙
原文: https://www.percona.com/blog/...

有人说最好的密码就是你不用记忆的。auth_socket 插件和 MariaDB 的 unix_socket 让这种想法在 MySQL 上变成可能。

  • auth_socket:https://dev.mysql.com/doc/ref...
  • unix_socket:https://mariadb.com/kb/en/lib...

这两个插件虽然不是新发布,但在 MariaDB 10.4 上 unix_socket 已经默认安装,并且是身份验证方法之一。

插件的安装和使用

如上所述,这不是新功能,即使使用 Debian 团队维护的 .deb 安装包安装 MySQL,也会创建 root 用户,以便使用套接字身份验证,对于 MySQL 和 MariaDB 都是如此:

root@app:~# apt-cache show mysql-server-5.7 | grep -i maintainers
Original-Maintainer: Debian MySQL Maintainers 
Original-Maintainer: Debian MySQL Maintainers <pkg-mysql-maint@lists.alioth.debian.org>

安装后,root 用户验证过程如下:

root@app:~# whoami
root
root@app:~# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.27-0ubuntu0.16.04.1 (Ubuntu)

Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select user, host, plugin, authentication_string from mysql.user where user = 'root';
+------+-----------+-------------+-----------------------+
| user | host      | plugin | authentication_string |
+------+-----------+-------------+-----------------------+
| root | localhost | auth_socket |                       |
+------+-----------+-------------+-----------------------+
1 row in set (0.01 sec)

与 MariaDB 相同:

10.0.38-MariaDB-0ubuntu0.16.04.1 Ubuntu 16.04

MariaDB [(none)]> show grants;
+------------------------------------------------------------------------------------------------+
| Grants for root@localhost                                                                      |
+------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED VIA unix_socket WITH GRANT OPTION |
| GRANT PROXY ON ''@'%' TO 'root'@'localhost' WITH GRANT OPTION                                  |
+------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

对于 Percona Server,来自官方 Percona Repo 的 .deb 软件包还将 root 用户身份验证设置为 auth_socket。这是适用于 MySQL 8.0.16-7 和 Ubuntu 16.04 的 Percona Server 的示例:

root@app:~# whoami
root
root@app:~# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.16-7 Percona Server (GPL), Release '7', Revision '613e312'

Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select user, host, plugin, authentication_string from mysql.user where user ='root';
+------+-----------+-------------+-----------------------+
| user | host      | plugin | authentication_string |
+------+-----------+-------------+-----------------------+
| root | localhost | auth_socket |                       |
+------+-----------+-------------+-----------------------+
1 row in set (0.00 sec)

那么,为何如此神奇?该插件使用 SO_PEERCRED 套接字选项,来检查 Linux 用户是否于 MySQL 用户匹配,以获取有关运行客户端程序的用户信息。因此该插件只能在支持 SO_PEERCRED 选项的系统上使用,例如: Linux。 SO_PEERCRED 套接字选项允许检索连接到套接字的进程 uid。然后,他可以获取与 uid 关联的用户名。

vagrant@mysql1:~$ whoami
vagrant
vagrant@mysql1:~$ mysql
ERROR 1698 (28000): Access denied for user 'vagrant'@'localhost'

由于 MySQL 不存在 'vagrant' 用户,因此访问被拒绝。让我们创建用户再次尝试:

MariaDB [(none)]> GRANT ALL PRIVILEGES ON *.* TO 'vagrant'@'localhost' IDENTIFIED VIA unix_socket;
Query OK, 0 rows affected (0.00 sec)

vagrant@mysql1:~$ mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 45
Server version: 10.0.38-MariaDB-0ubuntu0.16.04.1 Ubuntu 16.04
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> show grants;
+---------------------------------------------------------------------------------+
| Grants for vagrant@localhost                                                    |
+---------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'vagrant'@'localhost' IDENTIFIED VIA unix_socket |
+---------------------------------------------------------------------------------+
1 row in set (0.00 sec)

成功!!

现在,让我们在 CentOS 7 上安装的 Percona Server 版本 MySQL 8 上再试一试:

mysql> show variables like '%version%comment';
+-----------------+---------------------------------------------------+
| Variable_name   | Value                                   |
+-----------------+---------------------------------------------------+
| version_comment | Percona Server (GPL), Release 7, Revision 613e312 |
+-----------------+---------------------------------------------------+
1 row in set (0.01 sec)

mysql> CREATE USER 'percona'@'localhost' IDENTIFIED WITH auth_socket;
ERROR 1524 (HY000): Plugin 'auth_socket' is not loaded

失败了,原因是插件未加载:

mysql> pager grep socket
PAGER set to 'grep socket'
mysql> show plugins;
47 rows in set (0.00 sec)

让我们在运行时添加插件:

mysql> nopager
PAGER set to stdout
mysql> INSTALL PLUGIN auth_socket SONAME 'auth_socket.so';
Query OK, 0 rows affected (0.00 sec)

mysql> pager grep socket; show plugins;
PAGER set to 'grep socket'
| auth_socket  | ACTIVE | AUTHENTICATION | auth_socket.so | GPL |
48 rows in set (0.00 sec)

现在我们有了所需的一切。让我们再试一次:

mysql> CREATE USER 'percona'@'localhost' IDENTIFIED WITH auth_socket;
Query OK, 0 rows affected (0.01 sec)
mysql> GRANT ALL PRIVILEGES ON *.* TO 'percona'@'localhost';
Query OK, 0 rows affected (0.01 sec)

现在我们可以以操作系统用户 "percona" 的身份登录。

[percona@ip-192-168-1-111 ~]$ whoami
percona
[percona@ip-192-168-1-111 ~]$ mysql -upercona
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 19
Server version: 8.0.16-7 Percona Server (GPL), Release 7, Revision 613e312
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select user, host, plugin, authentication_string from mysql.user where user ='percona';
+---------+-----------+-------------+-----------------------+
| user    | host   | plugin   | authentication_string |
+---------+-----------+-------------+-----------------------+
| percona | localhost | auth_socket |                       |
+---------+-----------+-------------+-----------------------+
1 row in set (0.00 sec)

再次成功!

问题:我可以尝试以其他的系统用户的身份使用 percona 登录吗?

[percona@ip-192-168-1-111 ~]$ logout
[root@ip-192-168-1-111 ~]# mysql -upercona
ERROR 1698 (28000): Access denied for user 'percona'@'localhost'

不,你不能!

结论

MySQL 在多个方面都足够灵活,其中之一就是身份验证方法。正如我们在这篇文章中所看到的,依靠系统用户可以在没有密码的情况下进行访问。这在几种情况下很有用,但仅提及一种情况:从 RDS / Aurora 迁移到常规 MySQL 并使用 IAM 数据库身份验证保持访问而无需使用密码。

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