1 / 18

Windows Object Manager

Windows Object Manager. CS 470 -- Spring 2002. Overview. The object paradigm NT Objects and the Object Manager Object Structure Object Naming Object Handles Object Retention and Resource Limits. Objects in Windows NT/2K/XP. Provide a uniform access method Provide human readable names

lavey
Download Presentation

Windows Object Manager

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Windows Object Manager CS 470 -- Spring 2002

  2. Overview • The object paradigm • NT Objects and the Object Manager • Object Structure • Object Naming • Object Handles • Object Retention and Resource Limits

  3. Objects in Windows NT/2K/XP • Provide a uniform access method • Provide human readable names • Centralize security • Uniform charging method for use of resources • Uniform object retention method • Support resource inheritance by child processes

  4. Examples of Objects • Processes and Threads (Process Manager) • Sections (Memory Manager) • File (I/O Manager) • Events, Semaphores, Mutants, Timers • Access Tokens (Security system) • Object Directories, Symbolic Links (Object Manager) • Registry keys and many more…

  5. Process Structure Access Token Virtual Address Space Description Process Object Table Handle 1 Thread a Handle 2 File c Handle 3 Section f

  6. Object Manager • Creates and deletes objects • Sole source of handles for accessing objects • At each use of handle, verifies access is allowed by the particular user • Deletes temporary objects when no longer needed • Enforces quotas for various object types

  7. Object Creation • Allocation of memory for the object • Attaches security descriptor (who can do what to the object) • Insertion into object directory structure • Create handle and return to caller

  8. Opening Objects • Caller specifies desired access rights • Object manager calls security reference monitor; Security reference monitor checks against security descriptor to see what is permitted; Object manager stores granted access rights in object handle which is returned to caller. • Handle needed for all object accesses. Object manager checks all accesses against granted access rights.

  9. Object Structure Type Object Object 1 Object 2 Name Type name Directory Access Types Object Header Sec Desc Etc. Etc. Handle Database Handle Count Object Body Object Type Specific Proc1 Handle Proc1 Count Etc. Object 3

  10. Object name Object directory Security Descriptor Quota Charges Open handle count Open handle database Reference Count Kernel/user mode Type Object Pointer Object Header Entries

  11. Object Type Name Access Types Synchronizable? Pool Type Default Quota Charges Generic Rights Map Methods: open, close, delete, parse, query name, query/set security Type Name, e.g. process Possible access methods Can threads wait on this Allowed to page out? How much to charge (paged, non-paged pool) What is GEN. READ, etc? Routines called by object manager during various generic services Type Object Attributes

  12. Close Duplicate Handle Query object Query security Set Security Wait for single object Wait for multiple objects Invalidates handle Shares an object Get info about attributes Get security descriptor Set security descriptor Synchronize with 1 object Synchronize with multiple objects Generic Object Services

  13. Object Names • Used to distinguish objects, to find objects, and to share objects. • Name lookup is expensive -- so done only during creation (to put in object tree) and open. • Each computer (which may be a multiprocessor) has its own name space. • Name space is a single tree

  14. Object Directory Object Type Type Name Object Directory Methods Parse Name List Body Create object dir Open object dir Query object dir Services

  15. Symbolic Link Object Type Symbolic Link Type Name Substitute String Creation Date Body Create Symbolic Link Open Symbolic Link Query Symbolic Link Services

  16. Symbolic Link Example \ Device DosDevices Floppy0 A: mark1 \Device\Floppy0 Mark1.c Mark1.ppt

  17. Object Handles • Index into a process’s object table. So they are valid only in the process. • Obtained by creating, opening, inheriting, or receiving a duplicated handle from another process. • Attributes: Protect from Close, Audit on Close, Inheritable. Granted Access Rights Pointer to Object Attributes

  18. Retention and Quotas • Object Retention via open handle count and then by reference count • Quotas for use of paged pool, non-paged pool, paging file, and security descriptor. Limits are soft until memory manager disallows extension. • Typically single Quota Block for session, but Windows 2K/XP has jobs

More Related