Bratter: An Instruction Set Extension for Forward Control-Flow Integrity in RISC-V

Area of Science:

• Computer Architecture
• Cybersecurity
• Systems Software

Background:

• Growing research in control flow integrity (CFI) solutions.
• Emergence of hardware-assisted CFI with instruction set extensions (e.g., ARM's BTI, Intel's CET).
• Existing hardware solutions lack efficiency and scalability for diverse CFI techniques.

Purpose of the Study:

• Propose Bratter, a novel instruction set extension for RISC-V.
• Enable efficient and scalable forward control flow integrity solutions.
• Evaluate the performance impact of Bratter on CFI implementations.

Main Methods:

• Introduction of Branch Tag Registers and dedicated instructions within Bratter.
• Implementation of established CFI solutions: branch regulation and function signature check.
• Performance evaluation of Bratter through experimental analysis.

Main Results:

• Bratter effectively supports multiple CFI solutions simultaneously.
• Minimal overhead for code size (1.20%) and execution time (5.99%) when using Bratter.
• Demonstrates efficient and scalable CFI implementation on RISC-V.

Conclusions:

• Bratter offers a promising hardware-assisted approach for enhancing CFI on RISC-V.
• The proposed instruction set extension addresses limitations of current hardware CFI solutions.
• Bratter enables robust security with acceptable performance trade-offs.