In the existing software development ecosystem, security issues introduced by
third-party code cannot be overlooked. Among these security concerns, memory
access vulnerabilities stand out prominently, leading to risks such as the
theft or tampering of sensitive data. To address this issue, software-based
defense mechanisms have been established at the programming language, compiler,
and operating system levels. However, as a trade-off, these mechanisms
significantly reduce software execution efficiency. Hardware-software co-design
approaches have sought to either construct entirely isolated trusted execution
environments or attempt to partition security domains within the same address
space. While such approaches enhance efficiency compared to pure software
methods, they also encounter challenges related to granularity of protection,
performance overhead, and portability. In response to these challenges, we
present the DASICS (Dynamic in-Address-Space Isolation by Code Segments) secure
processor design, which offers dynamic and flexible security protection across
multiple privilege levels, addressing data flow protection, control flow
protection, and secure system calls. We have implemented hardware FPGA
prototypes and software QEMU simulator prototypes based on DASICS, along with
necessary modifications to system software for adaptability. We illustrate the
protective mechanisms and effectiveness of DASICS with two practical examples
and provide potential real-world use cases where DASICS could be applied.Comment: 16 pages, 6 figure