Overflowing the Kernel Stack with BPF - Security Implications and Mitigations

Explore the critical security implications of eBPF's interaction with the kernel stack in this 23-minute conference talk from the Linux Plumbers Conference. Delve into two fundamental problems in the BPF runtime environment that allow kernel stack overflow. Examine how BPF programs can inherit limited kernel stack space and potentially exceed it, despite verifier checks. Investigate the incomplete restrictions on BPF program nesting, leading to stack exhaustion. Learn about BPF program attachment, stack interactions, and known difficulties with limited kernel stacks. Witness demonstrations of stack overflow scenarios and discuss mitigation strategies for these and future issues arising from implicit verifier assumptions about the runtime execution environment.