Privileges and Devices

The privilege model uses privileges to protect system interfaces that are protected by file permissions alone in the superuser model. In a system with privileges, file permissions are too weak to protect the interfaces. A privilege such as proc_owner could override file permissions and then give full access to all of the system.

Therefore, ownership of the device directory is not sufficient to open a device. For example, members of the group sys are no longer automatically allowed to open the /dev/ip device. The file permissions on /dev/ip are 0666, but the net_rawaccess privilege is required to open the device.

Device policy is controlled by privileges. The getdevpolicy command displays the device policy for every device. The device configuration command, devfsadm, installs the device policy. The devfsadm command binds privilege sets with open for reading or writing of devices. For more information, see the getdevpolicy(1M) and devfsadm(1M) man pages.

Device policy allows you more flexibility in granting permission to open devices. You can require different privileges or more privileges than the default device policy. The privilege requirements can be modified for the device policy and for the driver proper. You can modify the privileges when installing, adding, or updating a device driver.

The add_drv and update_drv commands can modify device policy entries and driver-specific privileges. You must be running a process with the full set of privileges to change the device policy. For more information, see the add_drv(1M) and update_drv(1M) man pages.