Verus: Verifying Rust Programs using Linear Ghost Types

The Rust programming language provides a powerful type system that checks linearity and borrowing, allowing code to safely manipulate memory without garbage collection making ideal for developing low-level, high-assurance systems. For such systems, formal verification can be useful prove functional correctness properties beyond safety. This paper presents Verus, an SMT-based tool formally verifying programs. With programmers express proofs specifications using the language, take advantage of Rust's linear types borrow checking. We show how this allows linearly typed permissions let memory, pointers, concurrent resources. Verus organizes novel mode distinguishes specifications, which are not checked from executable proofs, borrowing. formalize Verus' linearity, modes in small lambda calculus, we safety termination proofs. demonstrate on series examples, including pointer-manipulating (an xor-based doubly linked list), with interior mutability, code.