Touch but Don't Look - Running the Kernel in Execute Only Memory

Explore the concept of execute-only memory and its implementation in the Linux kernel through this informative conference talk from the Linux Plumbers Conference. Dive into the benefits of execute-only memory for protecting against code-reading attacks and its potential impact on kernel security. Learn about the novel implementation approach across QEMU, KVM, and the guest Linux Kernel, which involves manipulating physical address bits to create execute-only guest virtual memory. Discover the proposed APIs for utilizing execute-only memory in userspace and the necessary changes to the Linux kernel to support this feature. Gain insights into the challenges and considerations for running the kernel in execute-only memory, including code patterns that may need to be avoided in future kernel development. Understand the implications for features like KASLR, ASLR, and fine-grained ASLR, as well as the potential impact on performance and reliability.