Derrick McKee (Purdue University), Yianni Giannaris (MIT CSAIL), Carolina Ortega (MIT CSAIL), Howard Shrobe (MIT CSAIL), Mathias Payer (EPFL), Hamed Okhravi (MIT Lincoln Laboratory), Nathan Burow (MIT Lincoln Laboratory)

Commodity operating system kernels remain monolithic for practical and historical reasons.All kernel code shares a single address space, executes with elevated processor privileges, and has largely unhindered access to all data, including data irrelevant to the completion of a specific task. Applying the principle of least privilege, which limits available resources only to those needed to perform a particular task, to compartmentalize the kernel would realize major security gains, similar to microkernels yet without the major redesign effort. Here, we introduce a compartmentalization design, called a Hardware-Assisted Kernel Compartment (HAKC), that approximates least privilege separation, while minimizing both developer effort and performance overhead. HAKC divides code and data into separate partitions, and specifies an access policy for each partition. Data is owned by a single partition, and a partition's access-control policy is enforced at runtime, preventing unauthorized data access. When a partition needs to transfer control flow to outside itself, data ownership is transferred to the target, and transferred back upon return. The HAKC design allows for isolating code and data from the rest of the kernel, without utilizing any additional Trusted Computing Base while compartmentalized code is executing. Instead, HAKC relies on hardware for enforcement.

Loadable kernel modules (LKMs), which dynamically load kernel code and data providing specialized functionality, are the single largest part of the Linux source base. Unfortunately, their collective size and complexity makes LKMs the cause of the majority of CVEs issued for the Linux kernel. The combination of a large attack surface in kernel modules, and the monolithic design of the Linux kernel, make LKMs ideal candidates for compartmentalization. To demonstrate the effectiveness of our approach, we implement HAKC in Linux v5.10 using extensions to the Arm v8.5-A ISA, and compartmentalize the `ipv6.ko` LKM, which consists of over 55k LOC. The average overhead measured in `Apachebench` tests was just 1.6%--24%. Additionally, we compartmentalize the `nf_tables.ko` packet filtering LKM, and measure the combined impact of using both LKMs. We find a reasonable linear growth in overhead when both compartmentalized LKMs are used. Finally, we measure no significant difference in performance when using the compartmentalized `ipv6.ko` LKM over the unmodified LKM during real-world web browsing experiments on the Alexa Top 50.

View More Papers

Privacy in Urban Sensing with Instrumented Fleets, Using Air...

Ismi Abidi (IIT Delhi), Ishan Nangia (MPI-SWS), Paarijaat Aditya (Nokia Bell Labs), Rijurekha Sen (IIT Delhi)

Read More

insecure:// Vulnerability Analysis of URI Scheme Handling in Android...

Abdulla Aldoseri (University of Birmingham) and David Oswald (University of Birmingham)

Read More

F-PKI: Enabling Innovation and Trust Flexibility in the HTTPS...

Laurent Chuat (ETH Zurich), Cyrill Krähenbühl (ETH Zürich), Prateek Mittal (Princeton University), Adrian Perrig (ETH Zurich)

Read More

Building Embedded Systems Like It’s 1996

Ruotong Yu (Stevens Institute of Technology, University of Utah), Francesca Del Nin (University of Padua), Yuchen Zhang (Stevens Institute of Technology), Shan Huang (Stevens Institute of Technology), Pallavi Kaliyar (Norwegian University of Science and Technology), Sarah Zakto (Cyber Independent Testing Lab), Mauro Conti (University of Padua, Delft University of Technology), Georgios Portokalidis (Stevens Institute of…

Read More