Copy file mechanism for transferring files between a host system and an emulated file system

• US 5,566,326 A
• Filed: 09/23/1994
• Issued: 10/15/1996
• Est. Priority Date: 09/28/1993
• Status: Expired due to Term

• Current Assignee: Bull HN Information Systems Incorporated (Atos SE)
• Original Assignee: Bull HN Information Systems Incorporated (Atos SE)
• Inventors: Buck, Kenneth J., Perry, Ron B., Bianchi, Richard S., Hirsch, Thomas S.
• Primary Examiner(s): Ray, Gopal C.
• Application Number:
  US08/311,652
• Time in Patent Office: 753 Days
• Field of Search: 395/500, 395/700, 395/600, 395/800, 395/650, 395/187.01, 395/821, 380/4, 380/25, 380/23, 340/825.31, 340/825.34
• US Class Current: 703/26
• CPC Class Codes: G06F 13/10 Program control for peripheral devices G06F13/14 - G06F13/42 take precedence
• CPC Class Codes: G06F 13/105 where the programme performs an input/output emulation function
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/6281 at program execution time, where the protection is within the operating system
• CPC Class Codes: G06F 2221/2105 Dual mode as a secondary aspect
• CPC Class Codes: G06F 9/45537 Provision of facilities of other operating environments, e.g. WINE I/O emulation G06F13/105

Abstract

A host data processing system which includes a plurality of input/output devices operates under the control of an enhanced version of the UNIX operating system. The host system includes an emulator which runs as an application process for executing user emulated system (ES) application programs. The emulator includes a number of emulated system executive service components operating in shared memory and an interpreter, an emulator monitor call unit (EMCU) and a number of server facilities operating in the host memory. The ES executive service command handler and file management components are extended to accommodate dual decor copy command which invokes the file management component to copy files in either direction between the host system and emulated system. The server facilities include mechanisms for performing a trusted user level validation when the dual decor copy command is invoked and access control checking at file access which ensures security relative to preventing both unauthorized user access and compromises in user data through improper use of the copy command.

Claims

1. A host system having a memory organized into shared and host memory areas and a hardware platform including a plurality of input/output devices operatively connected for executing host system instructions and for emulating the execution of emulated system instructions by an emulator running as an application process on said host system, said plurality of input/output devices including input/output devices for storing files contained within emulated system and host file systems, said emulator including a number of emulated system executive service components operating in said shared memory area comprising a command handler unit and file management component operatively coupled to said command handler unit for managing files of said emulated system file system and an interpreter, an emulator monitor call unit (EMCU) and server facilities operating in said host memory area, said host system further including operating system facilities for providing a number of services for host programs, said operating system facilities being coupled to said plurality of input/output devices and to said EMCU, said host system further including a copy file facility for transferring files between said host and emulated system file systems, said copy file facility comprising:

copy command handler means included within said command handler unit, said command handler means in response to each copy file command specifying access to a file within said host file system generating a special monitor call to said EMCU for causing a request input/output operation to be issued to said server facilities;

a user table (USTBL) mechanism located in said host memory area, said USTBL mechanism having a number of locations for storing unique user description entries generated by said EMCU for emulated system users whose identities were previously validated during login; and

,

said server facilities including first server handler means including user security validation means, said security validation means in response to an input/output request generated by said copy command handler means in response to an emulated system user copy file command issued for transferring a host file, performing a validation operation on said emulated system user by accessing said user table mechanism entry associated with said user requesting access to ascertain that said copy file command was issued by a trusted user and would not compromise host system security and second server means coupled to said first server handler means, said second server means receiving said input/output request for performing the execution of copy file command only when said validation operation confirms that the command was issued by a trusted user.

2. The host system of claim 1 wherein said second server means includes access control means for performing an access control check for establishing that said emulated system user has the required access permissions to execute the file copy command for transferring a file between said host and emulated file systems.

3. The host system of claim 2 wherein said second server means performs said validation of access permissions by said access control means at a time when file access is to take place which corresponds to an open command.

4. The host system of claim 2 wherein said operating system includes Inode permission files defining access permissions for each file of said host system, said access control means generating a number of system calls to said operating system for validating user access on the basis of both basic and extended permissions defined by said Inode permission files.

5. The host system of claim 1 wherein each unique user description entry includes emulated system descriptive information associated with the user by said executive service components which is not modifiable by the user.

6. The host system of claim 5 wherein said emulated system descriptive information used to perform said validation operation includes a first portion containing user-id information and second and third portions containing addresses of predetermined data structures used by the executive service components to uniquely identify the user.

7. The host system of claim 6 wherein said first server handler means performs said validation operation by comparing the portions of said emulated system user descriptive information previously stored in said user table mechanism as an entry for the user with corresponding portions of emulated system user descriptive information obtained from said emulated memory area obtained by said first server handler means which is associated with a current user issuing said copy file command.

8. The host system of claim 7 wherein said first server handler means upon determining that there is no identical comparison indicating that the current user is untrustworthy, signals the occurrence of a user security violation and does not initiate a series of operations for enabling execution of the copy file command.

9. The host system of claim 7 wherein said first server handler means upon determining that there is an identical comparison identifying no change in user personality confirming that the current user is trustworthy, initiates a series of operations for enabling execution of the copy file command.

10. The host system of claim 1 wherein said copy file command is a new command added to a set of commands utilized by said emulated system.

11. The host system of claim 10 wherein said copy file command has a predetermined format having a number of different portions, a first portion being coded to specify a new command code for invoking said command handler means, a second portion being coded for designating a complete path name of a source file to be copied, a third portion being coded for designating a complete path name of a destination file to be copied to wherein one of said second and third portions has a pathname which is preceded by a predetermined prefix indicating a host file pathname.

12. The host system of claim 11 wherein said number of different portions further includes a number of optional control arguments coded for designating file type or emulated system file attributes.

13. The host system of claim 12 wherein a first group of said control arguments is coded to designate whether a file is being copied as a binary file or as a text (ASCII) file and said copy command handler means including means for converting a file transferred from said host file system into a format designated by said first group of said control arguments contained in said copy file command.

14. The host system of claim 12 wherein said first group of optional control arguments are formatted as follows:

-BINARY|-B|-TEXT|-T.

15. The host system of claim 12 wherein a second group of said control arguments is coded to designate one of a number of different options including setting file attributes to create a file having the same attributes as an existing emulated system file specified by a specified pathname, setting file attributes to create a first type of emulated system file organization and setting file attributes to create a second type of emulated system file organization and said copy command handler means converting a file transferred from said host file system into a file containing one of said different options specified by said copy file command.

16. The host system of claim 15 wherein said second group of control arguments are formatted as follows:

[-CLONE clone_-- pathname|-SEQ|-S_-- R].

17. The host system of claim 12 wherein a third group of control arguments are coded to specify how a copy file operation is to be completed and said copy command handler means including means for causing said file management component to perform an operation specified by said third group of optional arguments.

18. The host system of claim 17 wherein said third group of control arguments are formatted as follows:

-DELETE|-LIST|-LS.

19. The host system of claim 12 wherein said copy command handler means includes means for verifying that said pathnames, file types and file attributes are valid.

20. The host system of claim 1 wherein said copy command handler means includes buffer means for transferring predetermined size portions of said host file which are larger than sizes used in an emulated system file for increasing efficiency.

21. The host system of claim 20 wherein said size is calculated in a predetermined manner for maximizing efficiency.