How do the names in the file security dialog map to access control masks?

Raymond Chen

Raymond

When you call up the file security dialog, you’ll see options like “Full Control” and “Read and Execute”. That’s really nice as friendly names go, but when you’re digging into the security descriptor, you may need to know what those permissions really map to when it comes down to bits. First, the summary attributes:

Friendly name Access mask Inheritance
Full control FILE_ALL_ACCESS CONTAINER_INHERIT_ACE + OBJECT_INHERIT_ACE
Modify FILE_GENERIC_READ | FILE_GENERIC_WRITE | FILE_GENERIC_EXECUTE | DELETE CONTAINER_INHERIT_ACE + OBJECT_INHERIT_ACE
Read and execute FILE_GENERIC_READ | FILE_GENERIC_EXECUTE CONTAINER_INHERIT_ACE + OBJECT_INHERIT_ACE
List folder contents FILE_GENERIC_READ | FILE_GENERIC_EXECUTE CONTAINER_INHERIT_ACE
Read FILE_GENERIC_READ CONTAINER_INHERIT_ACE + OBJECT_INHERIT_ACE
Write FILE_GENERIC_WRITE & ~READ_CONTROL CONTAINER_INHERIT_ACE + OBJECT_INHERIT_ACE

If you go to the Advanced view, then you get much more precise control:

Friendly name Access mask
Traverse Folder / Execute File FILE_TRAVERSE == FILE_EXECUTE
List Folder / Read Data FILE_LIST_DIRECTORY == FILE_READ_DATA
Read Attributes FILE_READ_ATTRIBUTES
Read Extended Attriibutes FILE_READ_EA
Create Files / Write Data FILE_ADD_FILE == FILE_WRITE_DATA
Create Folders / Append Data FILE_ADD_SUBDIRECTORY == FILE_APPEND_DATA
Write Attributes FILE_WRITE_ATTRIBUTES
Write Extended Attributes FILE_WRITE_EA
Delete Subfolders and Files FILE_DELETE_CHILD
Delete FILE_DELETE
Read Permissions READ_CONTROL
Change Permissions WRITE_DAC
Take Ownership WRITE_OWNER

(In the Advanced view, you control inheritance from the “Apply to” drop-down combo box.) Note that the “Delete Subfolders and Files” and “Delete” attributes together determine whether you can delete a file or subdirectory: You can delete an item either if you have DELETE permission on the item or if you have DELETE_CHILD permission on its parent. This “combo” allows you to set up a directory where everybody can create files and can delete files that they have created, while still retaining the ability as the directory’s owner to delete any file in it. You do this by granting yourself DELETE_CHILD permission on the directory and granting DELETE to CREATOR_OWNER as an inheritable attribute. Since you have DELETE_CHILD permission, you can delete anything in the directory. And since the creator/owner has DELETE permission, people can delete the files that they themselves created.

[Update 2pm: INHERIT_ONLY_ACE should be OBJECT_INHERIT_ACE.]

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