技术分享 | 安全地无密码登录 MySQL[通俗易懂]

作者：丹尼尔·古斯曼布尔戈斯 翻译：管长龙 原文：https://www.percona.com/blog/2019/11/01/use-mysql-without-a-password/

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/refman/8.0/en/socket-pluggable-authentication.html

• unix_socket：https://mariadb.com/kb/en/library/authentication-plugin-unix-socket/

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 <pkg-mysql-maint@lists.alioth.debian.org>
Original-Maintainer: Debian MySQL Maintainers <<a href="mailto:pkg-mysql-maint@lists.alioth.debian.org">pkg-mysql-maint@lists.alioth.debian.org</a>>

代码100分

安装后，root 用户验证过程如下：

代码100分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：

代码100分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。