Enabling session level restrictions for devices having disjoint stacks

1. A method, performed by a filter driver in a virtual desktop infrastructure environment, for determining when a device is redirected, the method comprising:

in response to a filter driver being loaded on a device stack that pertains to a device, identifying a root driver of the device stack;

querying the root driver for a container ID of the device;

obtaining a container ID of each device that is enumerated by a redirection virtual bus driver;

determining that the container ID of the device matches the container ID of a particular device that is enumerated by the redirection virtual bus driver; and

obtaining a session ID associated with the particular device.

2. The method of claim 1 , further comprising:

employing the session ID to implement session level restrictions.

3. The method of claim 2 , wherein implementing session level restrictions comprises blocking I/O requests that are not associated with the session ID.

4. The method of claim 2 , wherein implementing session level restrictions comprises removing one or more symbolic links to the particular device from a global object manager namespace and adding the one or more symbolic links to a local object manager namespace associated with the session ID.

5. The method of claim 1 , wherein the root driver is queried for the container ID of the device in response to determining that the root driver is not the redirection virtual bus driver.

6. The method of claim 1 , wherein obtaining a container ID of each device that is enumerated by a redirection virtual bus driver comprises accessing a child list of the redirection virtual bus driver.

7. The method of claim 1 , wherein the root driver is a virtual bus driver that implements a disjoint device stack.

8. The method of claim 1 , wherein the session ID of the particular device is obtained from the redirection virtual bus driver.

9. One or more computer storage media storing computer executable instructions which, when executed by one or more processors, implement a filter driver, the filter driver being configured to perform the following:

identify a root driver of a device stack on which the filter driver is loaded, the device stack pertaining to a device;

determine whether the root driver is a redirection virtual bus driver such that when it is determined that the root driver is not the redirection virtual bus driver, the filter driver obtains, from the root driver, a container ID of the device and compares the container ID of the device to a container ID of each device enumerated by the redirection virtual bus driver; and

when the container ID of the device matches the container ID of a particular device enumerated by the redirection virtual bus driver, the filter driver implements session level restrictions using a session ID associated with the particular device.

10. The computer storage media of claim 9 , wherein identifying the root driver comprises traversing the device stack until reaching a bottommost driver in the device stack.

11. The computer storage media of claim 9 , wherein the filter driver obtains the session ID of the particular device from the redirection virtual bus driver.

12. The computer storage media of claim 9 , wherein the filter driver is further configured to perform the following:

when it is determined that the root driver is the redirection virtual bus driver, the filter driver obtains, from the redirection virtual bus driver, a session ID of the device and implements session level restrictions using the session ID obtained from the redirection virtual bus driver.

13. The computer storage media of claim 9 , wherein the filter driver is further configured to perform the following:

when the container ID of the device does not match the container ID of any device enumerated by the redirection virtual bus driver, the filter driver foregoes implementing session level restrictions.

14. The computer storage media of claim 9 , wherein comparing the container ID of the device to a container ID of each device enumerated by the redirection virtual bus driver comprises obtaining a list of the devices enumerated by the redirection virtual bus driver and employing the list to obtain the container ID of each of the devices in the list.

15. The computer storage media of claim 9 , wherein implementing session level restrictions comprises one or more of:

blocking I/O requests that are not associated with the session ID; or

removing symbolic links to the particular device from a global object manager namespace.

16. A method, performed by a filter driver, for determining whether to implement session level restrictions, the method comprising:

in response to being loaded on a device stack that has been created on a server in response to a first device being redirected to the server, identifying a root driver of the device stack;

querying the root driver for a container ID of the first device;

obtaining a list of devices enumerated by a virtual bus driver;

comparing the container ID of the first device to container IDs of the devices in the list; and

upon determining that the container ID of the first device matches the container ID of a particular device in the list, obtaining a session ID associated with the particular device and employing the session ID to implement session level restrictions.

17. The method of claim 16 , further comprising:

upon determining that the container ID of the first device does not match the container ID of any of the devices in the list, foregoing implementing session level restrictions.

18. The method of claim 16 , wherein the root driver is queried for the container ID of the first device after determining that the root driver is not the redirection virtual bus driver.

19. The method of claim 16 , wherein implementing session level restrictions comprises blocking I/O requests that are not associated with the session ID.

20. The method of claim 16 , wherein the device stack represents a COM port device.