17.20.5 Security Considerations for the InnoDB memcached Plugin (original) (raw)

17.20.5 Security Considerations for the InnoDB memcached Plugin

Caution

Consult this section before deploying thedaemon_memcached plugin on a production server, or even on a test server if the MySQL instance contains sensitive data.

Because memcached does not use an authentication mechanism by default, and the optional SASL authentication is not as strong as traditional DBMS security measures, only keep non-sensitive data in the MySQL instance that uses the daemon_memcached plugin, and wall off any servers that use this configuration from potential intruders. Do not allow memcached access to these servers from the Internet; only allow access from within a firewalled intranet, ideally from a subnet whose membership you can restrict.

Password-Protecting memcached Using SASL

SASL support provides the capability to protect your MySQL database from unauthenticated access throughmemcached clients. This section explains how to enable SASL with the daemon_memcached plugin. The steps are almost identical to those performed to enabled SASL for a traditional memcached server.

SASL stands for “Simple Authentication and Security Layer”, a standard for adding authentication support to connection-based protocols. memcached added SASL support in version 1.4.3.

SASL authentication is only supported with the binary protocol.

memcached clients are only able to accessInnoDB tables that are registered in theinnodb_memcache.containers table. Even though a DBA can place access restrictions on such tables, access through memcached applications cannot be controlled. For this reason, SASL support is provided to control access to InnoDB tables associated with the daemon_memcached plugin.

The following section shows how to build, enable, and test an SASL-enabled daemon_memcached plugin.

Building and Enabling SASL with the InnoDB memcached Plugin

By default, an SASL-enabled daemon_memcached plugin is not included in MySQL release packages, since an SASL-enabled daemon_memcached plugin requires building memcached with SASL libraries. To enable SASL support, download the MySQL source and rebuild thedaemon_memcached plugin after downloading the SASL libraries:

1. Install the SASL development and utility libraries. For example, on Ubuntu, use apt-get to obtain the libraries:

sudo apt-get -f install libsasl2-2 sasl2-bin libsasl2-2 libsasl2-dev libsasl2-modules  

1. Build the daemon_memcached plugin shared libraries with SASL capability by addingENABLE_MEMCACHED_SASL=1 to yourcmake options.memcached also provides simple cleartext password support, which facilitates testing. To enable simple cleartext password support, specify the ENABLE_MEMCACHED_SASL_PWDB=1 cmake option.
   In summary, add following three cmake options:

cmake ... -DWITH_INNODB_MEMCACHED=1 -DENABLE_MEMCACHED_SASL=1 -DENABLE_MEMCACHED_SASL_PWDB=1  

1. Install the daemon_memcached plugin, as described in Section 17.20.3, “Setting Up the InnoDB memcached Plugin”.
2. Configure a user name and password file. (This example usesmemcached simple cleartext password support.)
   1. In a file, create a user namedtestname and define the password astestpasswd:

   echo "testname:testpasswd:::::::" >/home/jy/memcached-sasl-db  

   1. Configure the MEMCACHED_SASL_PWDB environment variable to informmemcached of the user name and password file:

   export MEMCACHED_SASL_PWDB=/home/jy/memcached-sasl-db  

   1. Inform memcached that a cleartext password is used:

   echo "mech_list: plain" > /home/jy/work2/msasl/clients/memcached.conf  
   export SASL_CONF_PATH=/home/jy/work2/msasl/clients  

3. Enable SASL by restarting the MySQL server with thememcached -S option encoded in thedaemon_memcached_option configuration parameter:

mysqld ... --daemon_memcached_option="-S"  

1. To test the setup, use an SASL-enabled client such asSASL-enabled libmemcached.

memcp --servers=localhost:11211 --binary  --username=testname  
  --password=password myfile.txt  
memcat --servers=localhost:11211 --binary --username=testname  
  --password=password myfile.txt  

If you specify an incorrect user name or password, the operation is rejected with a memcache error AUTHENTICATION FAILURE message. In this case, examine the cleartext password set in thememcached-sasl-db file to verify that the credentials you supplied are correct.

There are other methods to test SASL authentication withmemcached, but the method described above is the most straightforward.