It is possible to create user defined attributes values which can be entered as part of the user definition and then utilized in either policy conditions and/or values returned in authorization. This is a generic mechanism to meet the use case you define
This can be achieved as follows
1) Define an identity attribute of type IP address (under System Administration->Configuration->Dictionaries->Internal)
2) Define users and enter their assigned IP address to this attribute
3) Define an authorization profile that uses the define the IP address from the user record. Enter a manually defined attribute, Framed-IP-Address with Dynamic value selected as the IP address attribute in Internal Users dictionary
4) Select the authorization profile as result in authorization policy
