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Securing Systems and Attached Devices in Oracle® Solaris 11.4

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Updated: July 2019
 
 

Controlling Access to Devices

Peripheral devices that are attached to a computer system pose a security risk. Microphones can pick up conversations and transmit them to remote systems. CD-ROMs can leave their information behind for reading by the next user of the CD-ROM device. Printers can be accessed remotely. Devices that are integral to the system, for example, network interfaces such as bge0, can also present security issues.

    Oracle Solaris software provides several methods of controlling access to devices.

  • Set device policy – You can require that the process that is accessing a particular device be run with a set of privileges. Processes without those privileges cannot use the device. At boot time, Oracle Solaris software configures device policy. Third-party drivers can be configured with device policy during installation. After installation, you as the administrator can add device policy to a device.

  • Make devices allocatable – You can require that a user must allocate a device before use. Allocation restricts the use of a device to one user at a time. You can further require that the user be authorized to use the device.

  • Prevent devices from being used – You can prevent the use of a device, such as a microphone, by any user on a computer system. For example, a computer kiosk might be a good candidate for making certain devices unavailable for use.

  • Confine a device to a particular zone – You can assign the use of a device to a non-global zone. For more information, see Device Use in Non-Global Zones in Creating and Using Oracle Solaris Zones.

Device Policy

The device policy mechanism enables you to specify that processes that open a device require certain privileges. Devices that are protected by device policy can only be accessed by processes that are running with the privileges that the device policy specifies. Oracle Solaris provides default device policy. For example, network interfaces such as bge0 require that the processes that access the interface be running with the net_rawaccess privilege. The requirement is enforced in the kernel. For more information about privileges, see Process Rights Management in Securing Users and Processes in Oracle Solaris 11.4.

In Oracle Solaris, devices are protected with file permissions and with device policy. For example, the /dev/ip file has 666 permissions. However, the device can only be opened by a process with the appropriate privileges.

The configuration of device policy can be audited. The AUE_MODDEVPLCY audit event records changes in device policy.

Device Allocation

    The device allocation mechanism enables you to restrict access to a peripheral device, such as a CD-ROM. If device allocation is not enabled, peripheral devices are protected only by file permissions. For example, by default, peripheral devices are available for the following uses:

  • Any user can read and write to a CD-ROM drive or disc.

  • Any user can attach a microphone.

  • Any user can access an attached printer.

Device allocation can restrict a device to authorized users. Device allocation can also prevent a device from being accessed at all. A user who allocates a device has exclusive use of that device until the user deallocates the device. When a device is deallocated, device-clean scripts erase any leftover data. You can write a device-clean script to purge information from devices that do not have a script. For an example, see Writing New Device-Clean Scripts.

Attempts to allocate a device, deallocate a device, and list allocatable devices can be audited. The audit events are part of the other audit class.