3 ms·

It doesn't have to be a lock, since MCS can have (AFAIK) 1023 different categories and multiple processes can access the same resource depending on their catego

• gizmo686 6y ago
  1023 is the limit. If you can fit within 1023, then a simple MCS policy could work without lock-like implications. Android works around the 1023 limit by giving each app a set of categories. This works when a file can only ever be owned by 1 app, but becomes more difficult when multiple owners are possible. E.G. If you want to grant access to the catagory set c1,c10,c20 and c5,c15,c25 then you need to make sure there is nothing running as c1,c15,c20. This is probably doable, but I have not worked out what is does to the effective number of catagories you could have. > EDIT: Good point about requesting related resources though, not sure how you'd go about that (I'm not even sure you'd actually want that either since you could include '../../../etc/passwd' or something as an <img> tag) The answer is in step 5. Somehow, the userspace security manager needs to know that firefox is not allowed to use ../../../etc/passwd, but is (maybe?) allowed to use ../index.html. As I said. SELinux can be an effective component of a secure desktop system. But you need to overlay it with some other security system; and at this point no one has figured out what that security system should look like from a user perspective.