MySQL datamasking using ProxySQL

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Percona Live Amsterdam is just finished… there was an entire room full day about MySQL 8.0 which is wonderful but there was also another product that everybody was talking about: ProxySQL (great job René).

Ronald Bradford and the MySQL engineering team were discussing about what tool was missing in the MySQL ecosystem and Mark Leith highlighted that a datamasking utility was really missing.masking

Having used already ProxySQL for Group Replication and other tests, I knew that it would be possible to use it also for this purpose. After a very short discussion and a nightly chat with René, this is an example on how you can achieve this missing (and sometime heavy) task.

Description:

  • one CUSTOMERS table with sensitive information like Credit Card numbers (those are fake)
  • a developer user that doesn’t need to access those numbers

So we decided this:

  • the developer can only use SELECT (and EXECUTE)proxysql-resized
  • the developer can access all columns
  • but credit card numbers (cc_num) must be masked, but the last 4 digits
  • the developer can’t perform SELECT * on that specific table

This is our table:

+----+-----------+-------------+------------+------------------+----------+
| id | firstname | lastname    | cc_type    | cc_num           | cc_verif |
+----+-----------+-------------+------------+------------------+----------+
|  1 | Frederic  | Descamps    | mastercard | 5275653223285289 |      456 |
|  8 | Dim0      | Vanoverbeke | mastercard | 5345654523285289 |      123 |
| 15 | Kenny     | Gryp        | visa       | 4916066793184589 |      456 |
+----+-----------+-------------+------------+------------------+----------+

So first we will create on our database server the developer’s user:

MySQL> GRANT SELECT, USE on myapp.* to 'devel'@'%' identified by 'password';

Now let’s configure ProxySQL (I assume here that you already have installed and started proxysql) from it’s admin interface:

# mysql -u admin -padmin -h 127.0.0.1 -P6032

The first step is to create a user here too:

ProxySQL> INSERT INTO mysql_users(username,password,default_hostgroup) 
          VALUES ('devel','password',1);
and now our MySQL server if it's not yet referenced:
ProxySQL> INSERT INTO mysql_servers(hostgroup_id,hostname,port) 
          VALUES (1,'mysql1',3306);

We can load those settings in runtime and then save then to disk too:

ProxySQL> LOAD MYSQL SERVERS TO RUNTIME;
ProxySQL> LOAD MYSQL USERS TO RUNTIME;
ProxySQL> SAVE SERVERS USERS TO DISK;
ProxySQL> SAVE MYSQL USERS TO DISK;

We can already try and see that our developer can still read our data. Let’s work on this now.

ProxySQL> INSERT INTO mysql_query_rules (rule_id,active,username,match_pattern,error_msg)     
          VALUES (90,1,'devel','^SELECT \*.*FROM.*CUSTOMERS',   
          'Query not allowed due to sensitive information, please contact dba@myapp.com');

Let’s load it in runtime and test:

ProxySQL> LOAD MYSQL QUERY RULES TO RUNTIME;

# mysql -u devel -ppassword -h 127.0.0.1 -P 6033

mysql> select * from myapp.CUSTOMERS;
ERROR 1148 (42000): Query not allowed due to sensitive information, please contact dba@myapp.com

Wooohooo it worked 😉

And the datamasking ? This is our next step, let’s enter the following rule:

ProxySQL> INSERT INTO mysql_query_rules (rule_id,active,username,match_pattern,replace_pattern,apply)
          VALUES (1,1,'devel','^[sS][eE][lL][eE][cC][tT] (.*)cc_num([ ,])(.*)', 
                "SELECT \1CONCAT(REPEAT('X',12),RIGHT(cc_num,4)) cc_num\2\3",1);

ProxySQL> LOAD MYSQL QUERY RULES TO RUNTIME;

We can test it again:

mysql> select firstname, cc_num from myapp.CUSTOMERS;
+-----------+------------------+
| firstname | cc_num           |
+-----------+------------------+
| Frederic  | XXXXXXXXXXXX5289 |
| Dim0      | XXXXXXXXXXXX5289 |
| Kenny     | XXXXXXXXXXXX4589 |
+-----------+------------------+

Wooohoooo it worked again 😉

Note: if you find ways to workaround the datamasking, let me know, thank you.

Don’t forget to also save your rules to disk:

ProxySQL> SAVE MYSQL QUERY RULES TO DISK;

As you can see it’s possible to have a very quick datamasking solution for MySQL using ProxySQL.

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9 thoughts on “MySQL datamasking using ProxySQL

  1. Would it work with a “select *”?

    I think that a easier solution would be create a view “masked_customers” with the cc masked and rewrite select/update/delete/inserts to that view for “devel”.

    Regards,

    1. Hi Francisco,

      As written in the article, select * is not allowed for that table.

      View can indeed be an option but it can also cause performance issue in certain circumstances.

  2. > if you find ways to workaround the datamasking, let me know, thank you.

    Wouldn’t queries like these work :
    * select firstname, cc_num, cc_num from myapp.CUSTOMERS;
    * select firstname, `cc_num` from myapp.CUSTOMERS;
    * select firstname, cc_num
    from myapp.CUSTOMERS;

    1. Hey Thomas !

      Thank you for this feedback and indeed you are right, good catch, let me try to improve the regexp !

      Cheers

  3. What will happen to these queries
    (1) select firstname, /* cc_num */, from myapp.CUSTOMERS;
    (2) select a.* from myapp.CUSTOMERS a
    (3) /* */ select firstname, cc_num from myapp.CUSTOMERS;

    1. Hi Dipti,

      Thank you for these examples, I’m currently working on new implementation. That will help me to improve it !

  4. In addition, a user with the right permissions could create a view and access the data indirectly…

    create view bleh as select * from customer;
    select * from bleh;

  5. i want to implementation of data masking using proxysql in linux o/s.i have created db and tables from my root and create a db_user also and granted all privileges to this user,first one i login into admin and create table mysql_users and mysql_servers also and insert the values from proxysql> prompt.then i load and save it.then after i have inserted mysql query rules on my created table (that i was created from root ).then load mysql query rules to runtime.after that i log into my db_user and created and insert the mysql_query_rules,but when i load mysql query rules for runtime….ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘MYSQL QUERY RULES TO RUNTIME’ at line 1 this error has come.
    so please suggest me what i do ??

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