EPF: Evil Packet Filter


Di Jin, Vaggelis Atlidakis, and Vasileios P. Kemerlis, Brown University


The OS kernel is at the forefront of a system's security. Therefore, its own security is crucial for the correctness and integrity of user applications. With a plethora of bugs continuously discovered in OS kernel code, defenses and mitigations are essential for practical kernel security. One important defense strategy is to isolate user-controlled memory from kernel-accessible memory, in order to mitigate attacks like ret2usr and ret2dir. We present EPF (Evil Packet Filter): a new method for bypassing various (both deployed and proposed) kernel isolation techniques by abusing the BPF infrastructure of the Linux kernel: i.e., by leveraging BPF code, provided by unprivileged users/programs, as attack payloads. We demonstrate two different EPF instances, namely BPF-Reuse and BPF-ROP, which utilize malicious BPF payloads to mount privilege escalation attacks in both 32- and 64-bit x86 platforms. We also present the design, implementation, and evaluation of a set of defenses to enforce the isolation between BPF instructions and benign kernel data, and the integrity of BPF program execution, effectively providing protection against EPF-based attacks. Our implemented defenses show minimal overhead (<3%) in BPF-heavy tasks.

USENIX ATC '23 Open Access Sponsored by
King Abdullah University of Science and Technology (KAUST)

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This content is available to:

@inproceedings {288737,
author = {Di Jin and Vaggelis Atlidakis and Vasileios P. Kemerlis},
title = {{EPF}: Evil Packet Filter},
booktitle = {2023 USENIX Annual Technical Conference (USENIX ATC 23)},
year = {2023},
isbn = {978-1-939133-35-9},
address = {Boston, MA},
pages = {735--751},
url = {https://www.usenix.org/conference/atc23/presentation/jin},
publisher = {USENIX Association},
month = jul

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