Where does Windows store ACLs and do ACLs follow a file from one machine to another?
Our app uses a component that requires a license file in the directory with our executable, which happens to be a .NET WinForms app though I think it is immaterial to this question. When installed on some XP Pro machines (just three out of several hundred thus far), the component throws a license exception. So I regenerated the license file and sent it to the component vendor (EMC Captiva), where the vendor claims the error is due to the fact that the "Users" group has no read permissions on the file. The user who encounters the error happens to be a local admin, but that is besides the point as I am still curious about the more general question.
So my question is, are ACLs stored in a file such that they follow the file throughout its life, especially when the license file was generated on my dev machine (machine 1), stored in Subversion (machine 2), checked out of source control by TeamCity (machine 3), packaged into an installer by InstallShield (machine 4), and finally deployed to the customer's machine (machine 5) where it was installed by an Administrator? What about after I generate the file on my dev machine (machine 1), upload it to the component vendor via their support site (machine 2), and the support person downloads it to their machine for inspection (machine 3)?
I do not know this for sure (which is why I am asking it here), but I assumed each Windows machine stores ACLs in some central directory/list/table managed by NTFS rather than stored within the file. What happens to the original file's ACL when it is copied from one machine to another, stored in Subversion, packaged into an MSI, etc? Can someone point me to some good references where I can read up on this?
Answer
ACLs are stored in the part of an NTFS partition that does all the background plumbing - the MFT (Master File Table).
The ACL does not follow a file around, since it is not a part of the file (just like the filename it is metadata). The file can cross partition type boundaries (NTFS->FAT), the ACL cannot.
Now if you move a file within one NTFS partition, you might get the impression that ACLs actually follow the file around. This is because during a move, only the filename in the MFT is actually changed. Everything else stays the same.
If you copy a file or move it to another partition or computer (which is actually a copy+delete operation), the copied file will by default inherit the permissions of it's new container (the inheritable ones only, to be precise).
However, there are tools that are capable of retaining the ACL of a file after a copy operation (simply by recreating it on the target file after the copy operation) even over partition or computer boundaries. xcopy can do that, among others.
But since an ACL can contain SIDs that are "domain owned", an ACL entry might not actually be meaningful to the target computer that is not part of the same domain (for example when taking home an NTFS-formatted USB drive). In that case the ACL entry will have no effect.
Other SIDs are "well known", like the "SYSTEM" SID. These will actually be recognized across domain borders.