x86 Kernel Shadow Stacks Being Worked On For Linux As Powerful Control Flow Protection
Linux kernel shadow stacks being worked on for powerful control flow protection. Intel engineer Dave Hansen sent out patch series for kernel shadow stacks RFC.
Intelligence analysis by Qwen 2.5 (3B)
Linux kernel developers are working on adding shadow stacks for kernel space to provide better control flow protection.
Shadow stacks are like a special stack in the Linux kernel that helps protect against bad things happening, like attacks. It's like having a secret safe for storing important information that can't be easily broken into.
Analysis
{"heading_1":"Intel Engineer's RFC","content_1":"Intel engineer Dave Hansen sent out a patch series for kernel shadow stacks RFC, proposing a proof-of-concept to run the kernel with shadow stacks. The series is a proof-of-concept to run the kernel with shadow stacks.","heading_2":"Current Status and Limitations","content_2":"The current RFC code imposes Flexible Return Event Delivery (FRED) as a requirement. This will limit the kernel shadow stacks support to Intel Panther Lake CPUs and newer or AMD Zen 6 and beyond. The initial limitations are outlined in a patch not for merging.","heading_3":"Incompatible Features","content_3":"Several Linux features are incompatible with kernel shadow stacks, including CPU mitigations like Retpolines, function graph tracing, BPF trampolines, Kexec, EFI mixed mode, KVM, Xen PV, and others."}
Key points
- Intel engineer Dave Hansen sent out a patch series for kernel shadow stacks RFC.
- The RFC code imposes Flexible Return Event Delivery (FRED) as a requirement.
- Several Linux features are incompatible with kernel shadow stacks.
If the kernel shadow stacks work well, it could make Linux even safer from attacks.
There might be some features that can't work with shadow stacks, so we might have to disable them.
