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Access Control List (ACL) Implementation Project---Project Issues

These are some of the issues / challenges that may arise, while you are implementing the second project on ACL. This section will help to think about the issues so that you can get a head start to your project. Below listed are some of the common issues, which will help you to think about the whole project and its implementation.

1. ACL Representation – This is one of the important issues that the students would need to think about of how to represent the ACL. They would need to think about how they can represent their access control list, whether they are going to make the ACL in a user defined way. They would need to think how they are going to allow ACL’s to specify access permissions on a per user (principal) basis, rather than the current owner-group-other protection method. Is the student going to fix a particular representation or whether the representation will be flexible?

2. Storing the ACL’s – This is another challenging part of the project where the student needs to think where exactly he needs to store his access control list. He must think whether he can create a pointer to an indirect disk block and make that block with the block number point to the inode or can he use the unused slot (last entry) of the inode. Another issue that may arise will be, How feasibly can you extend the inode, is it easy to do so?

3. File Pointer Issues – The ACL is implemented by modifying the file system. And once the ACL is represented and stored in the FS, do we have any file pointer issues, any dangling pointers, which may cause file-handle leaks? This is an issue that the student would need to think about.

4. User Management of ACL’s - This is yet another important issue that the student would need to think about. The user can manage the access control list (user defined), how is this going to be implemented? What are the key decisions that need to be taken? Are you planning to keep an user table corresponding to uid, gid, and permissions? These are some of the issues he needs to think about.

5. System Policy - The student would need to think about how he is going to define the system policy to map the whole system. 

6. Conflicts - The owner of an object can change its ACL at any time, thus making it easy to prohibit access that were previously allowed. This change will not affect for the users who have currently the file open. Does this create a conflict?





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