30.6 Preventing Exposure of the Encryption Password in a Log

On OES, most of the NSS code runs in kernel space, but some portions are required to run in user space. To communicate across the boundary between user and kernel space, some internal mechanisms were implemented. For debugging purposes, some logging features were added to track these communications between user and kernel space. These logging features are slow and cumbersome, and are intended for use by Novell support engineers to help diagnose any problems that arise. They are not intended for everyday use, and seriously impact performance when they are turned on.

There are two main areas where logging is built into the system. The first is the capacity to log all XML communication to/from the _ADMIN volume. The second is the capacity to log NSS kernel requests to communicate with eDirectory, NICI, and LUM, all of which run in user space.

When working with encrypted volumes it is important to realize that the volume password and key information is exchanged between user and kernel space as encrypted volumes are created and/or mounted. If you have logging enabled on the Linux server when you enter the encryption password, your password and volume key information might show up in the log file.

You must be the root user or an equivalent user with root user privileges to perform the steps required to enable logging, disable logging, or read /var/log/messages. This prevents ordinary users from manipulating the logging environment. We strongly recommend that you protect the physical access to the server and the root user passwords to prevent unauthorized access to your servers.

Even though the logging mechanisms are root user protected, we strongly recommend that you make sure logging is disabled whenever you plan to enter the encryption password for an encrypted NSS volume on your system. You enter an encryption password when you create the volume and when you mount the volume for the first time after any system start or reboot.

Applications such as NSSMU and Perl scripts communicate with NSS via the _admin volume. In these communications, the volume’s encryption password is passed in the clear. There are two utilities that can log these exchanges, the adminusd daemon and the nss /vfs commands in NSSCON. Logs are written to /var/log/messages.

All internal NSS kernel space requests for NetIQ eDirectory, NICI, and Linux User Management are routed through an interface called the NDP (Novell Data Portal). NDP has a user space daemon (ndpapp) and a kernel module (ndpmod). In communications between ndpapp and ndpmod, the volume’s encryption password is obscured, but it can be easily broken. Both ndpapp and ndpmod have a logging capacity, and both of them write their log data to /var/log/messages.