Trusted communications with child processes

• US 8,161,544 B2
• Filed: 07/19/2006
• Issued: 04/17/2012
• Est. Priority Date: 07/19/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Dubhashi, Kedarnath Atmaram, Schwartz, Jonathan D., Muthukrishnan, Sambavi, Skaria, Simon
• Primary Examiner(s): Arani, Taghi
• Assistant Examiner(s): Darrow, Justin T
• Application Number:
  US11/488,979
• Publication Number:
  US 20080022281A1
• Time in Patent Office: 2,099 Days
• Field of Search: 726/17, 726/18, 726/20, 726 22- 24, 713/164, 713/167, 713/187, 718/106
• US Class Current: 726/17
• CPC Class Codes: G06F 9/547 Remote procedure calls [RPC]; Web services

Abstract

A method to identify a child process to a parent process in an operating system includes obtaining a token and login identifier from the operating system. The parent process creates a remote procedure call communications endpoint to communicate with the child process. Thereafter, a child process is spawned by the parent process. A child-initiated request to communicate with the parent process is then received by the parent process. In order to verify the identity of the child-initiated request, the parent process impersonates the child process and receives as identifier that identifies the requestor child process. The requestor process identifier and the spawned child identifier are compared. Based on the comparison, the parent process responds to the child-initiated request. In another embodiment, process identifiers are used by the parent process to verify the identity of a child process the requests communication with the parent process.

Claims

1. A method to identify a child process to a parent process on an operating system in computer software using impersonation of a requestor process, the method comprising:

obtaining a token from the operating system, the token obtained by the parent process;

creating a communications endpoint by the parent process and establishing a parent server for processing requests;

spawning, by the parent process, a child process and passing the endpoint to the child process wherein access to the child process is limited, the child process having a child security identifier;

receiving a requestor-initiated request to communicate with the parent process, the request including a security identifier for a requestor process;

impersonating the requestor process by the parent process, the operating system providing a security identifier that identifies the requestor process to the parent process;

comparing the requestor process security identifier with the child security identifier, thereby identifying the requestor process as a child process spawned by the parent process; and

responding, by the parent process, to the requestor-initiated request if the comparison is a match of security identifiers.

2. The method of claim 1, wherein obtaining a token from the operating system comprises:

calling into a security subsystem of the operating system by the parent process and receiving a token containing a logon identifier.

3. The method of claim 1, wherein creating a communications endpoint comprises creating a remote procedure call (RPC) communications endpoint.

4. The method of claim 1, wherein spawning further comprises:

setting, by the parent process, a discretionary access control list that identifies processes allowed to access the child process.

5. The method of claim 4, wherein only a parent process identity is permitted access to the child process.

6. The method of claim 1, further comprising:

receiving, by the parent process, a notification returned by the Operating System identifying a termination of child process; and

refusing communications requests once the child process terminates.

7. The method of claim 6, wherein the termination notification is returned in a separate thread and the endpoint is closed by the parent process.

8. The method of claim 1, wherein receiving a requestor-initiated request comprises receiving by the parent process a requestor-initiated request for sending and receiving data.

9. The method of claim 1, wherein impersonating the requestor process to the operating system comprises using an application programming interface invoked by the parent process upon the operating system.

10. The method of claim 1, further comprising:

closing the endpoint, by the parent process, if the comparison of security identifiers is not a match.

11. The method of claim 1, further comprising:

repeating the steps of impersonating, comparing, and responding to every new request to communicate with the parent process.

12. A method to identify a child process to a parent process in an operating system in computer software using a process identifier, the method comprising:

obtaining a token from the operating system, the token obtained by the parent process;

creating a communications endpoint by the parent process and establishing a parent server for process responses;

spawning, by the parent process, a child process and passing the endpoint to the child process wherein access to the child process is limited, the spawning also producing a child process identifier;

receiving a requestor-initiated request to communicate with the parent process, the request made to the endpoint and including a requestor process identifier;

querying the operating system, by the parent process, for a spawned child process identifier, the operating system providing the spawned child process identifier;

comparing the requestor-initiated process identifier with the spawned child process identifier;

thereby identifying a requesting process as the child process spawned by the parent process; and

responding, by the parent process, to the requestor-initiated request if the comparison is a match of process identifiers.

13. The method of claim 12, wherein obtaining a token from the operating system comprises:

calling into a security subsystem of the operating system by the parent process and receiving a token containing a logon identifier.

14. The method of claim 12, wherein creating a communications endpoint comprises creating a remote procedure call (RPC) communications endpoint.

15. The method of claim 12, further comprising:

receiving, by the parent process, a notification returned by the child process identifying a terminated child process; and

refusing communications requests with the terminated child process.

16. The method of claim 12, wherein receiving a requestor-initiated communications request comprises receiving by the parent process a requestor-initiated request for sending and receiving data.

17. The method of claim 12, further comprising:

closing the endpoint, by the parent process, if the comparison of process identifiers is not a match.

18. The method of claim 12, wherein if the parent process receives a child process notification corresponding to the child process, the notification received in a separate thread, then the child process is terminated and the parent process subsequently refuses all communication requests from the child process and closes the endpoint.

19. The method of claim 12, further comprising:

repeating the steps of querying, comparing, and responding to every new requestor-initiated request to communicate with the parent process.

20. The method of claim 12, further comprising setting a security descriptor on the child process by the parent process once the child process is spawned.