Blog

[EXTRA CREDIT] Write an equals method for SpacePirate. Two instances of SpacePirate are equal if their parent’s variables are equal and if they have the same crewSize and spaceship. You must use the parent’s equals method for credit.

Constructor chaining … (select one)

Write a getter for bounty and pirateCount. Write a setter for name and bounty.

A stimulus is detected by a receptor and the response is salivation. How many synapses are involved in the reflex pathway? Assume the sensory neuron has a receptor membrane and that there is an integrating neuron. 

These questions are from the discretionary and mandatory access control modules. All students in a class belong to a group G and are able to access class resources because G is granted the necessary permissions. Assume Alice has tested out of a topic and does not need to take the quiz Q on this topic. The professor does not want Alice to have access to Q but wants Alice to remain in group G so she can access other resources. Also, the professor wants to grant access to Q to all other students by granting the desired access to G. The mechanisms provided by various operating systems can be used to meet this access control requirement. Explain how this can be achieved most efficiently and correctly in Linux with extended access control lists (EACLs) and in Windows. First, provide the access control entries (ACEs) for Alice and G with their types and permissions for the quiz Q in each system. After this, discuss which of these ACEs will be checked if Alice tries to gain access to the quiz Q and is denied access. (2+2+2+2  pts.) The Bell and La Padula (BLP) and Biba models address confidentiality and integrity of data in a system that supports mandatory access control. A system allows read-down as is done by BLP, and writes by a user are only allowed at the user’s level (no writes to higher levels are allowed). Does this system satisfy the confidentiality and integrity goals of the BLP and Biba models? First, describe the BLP and Biba requirements and then explain if the requirements of each model are satisfied. (2+2+2+2 pts.) A certain company has many customers and some of them have conflict-of-interest (CoI) relationships. Also, employees can only access company data by executing applications approved by the company based on the functions they perform in the company. The people responsible for access provisioning in this company came up with the following scheme.  All files of a given customer must be stored in a single directory (it could be a container-like unit when using cloud storage). Initially, users are allowed to execute applications based on their needs and each application is granted access to files required for its execution. Access could be removed when applications execute. In particular,  when user U executes application A which accesses files from customer C’s directory, access to all files in directories of customers who have a CoI relationship with C is turned off for application A when it is executed by U.   Give two examples of policies discussed in the mandatory access control module of the course that could be used to control access to documents by this company. Explain your answer by discussing the specific data access requirements of the company that are satisfied by each policy. (2+2 pts.)  Does the suggested implementation correctly enforce each policy that you recommend for the company? Provide a brief justification for your answer. (4+4 pts.)

We studied hardware support that is provided by modern processor architectures to protect TCB data and code from untrusted user code. In particular, we examined in detail the hardware support provided by successive generations of Intel processors. Answer the following questions for these processors. Provide a brief explanation that justifies your answer. In the protected mode, what descriptor protection level (DPL) is used for a segment that has TCB or kernel code and data? Also, what page protection level (PPL) is used for pages that store such segment code/data? (2+2  pts.) Does kernel code always execute at the highest privilege level?  Explain your answer. (1+2  pts.) The MOV instruction in the Intel instruction set architecture can be used to move data between registers and memory. It can also be used to load certain control registers like CR3 which stores page table base address. Consider two cases where the MOV instruction is used to load a value stored in a memory location into (i) the stack pointer register (ESP), and (ii) the CR3 register. Can the MOV instruction in each of these cases be executed by user-level code? Is MOV a privileged instruction every time it is used or it depends on its operands? Explain your answer.  (4+2+2 pts.) True or false: With the VT-x virtualization extensions and a Type I hypervisor, a system call made by user code always requires processor mode to change from non-root to root. Briefly explain your answer. (2+2 pts.) True or false: With the Intel SGX extensions, successful exploitation of a hypervisor vulnerability can result in the disclosure of sensitive data that should only be accessed inside an enclave by the enclave’s code. Briefly explain your answer. (2+2  pts.)

A nurse is preparing to administer terbutaline, a medication used to manage preterm labor, to a patient via subcutaneous injection. Which needle size and gauge should the nurse select for this administration?

Consider a normal distribution with a mean of 120 and a standard deviation of 6. Use the Empirical Rule to determine the proportion of data values between 108 and 114. Draw yourself a curve like the one below to help you answer this question.

Is the variable “Number of courses this semester” an example of a discrete or continuous variable?

Which of the following best describes declarative memory?