1. A method, comprising: maintaining, by a computer system, permission information indicating that a first user's access to a data store is based at least in part on a physical location of a second user, wherein the permission information further controls access to the data store based on time frame information indicative of a time frame during which the data store can be accessed; receiving, by the computer system, location information indicating a current location of the first user and a current location of the second user, wherein the current location of the first user is determined by a device of the first user that includes a global positioning system (GPS) and the current location of the second user is determined by a device of the second user that includes a GPS, wherein the location information includes a timestamp indicative of a time at which the current location of the first user was determined; determining, by the computer system, whether a first distance from the current location of the first user to the current location of the second user is within a predetermined distance indicated by the permission information, wherein the predetermined distance specifies a particular distance between the first user and the second user; and based on the first distance being within the predetermined distance, the computer system enabling the first user to access data within the data store, wherein enabling the first user to access the data includes determining that the time indicated by the timestamp is within the time frame indicated by the time frame information.