Public bug reported: In disco and eoan, lockdown is automatically enforced when secure boot is on [0]. Because lockdown was not in the mailine kernel at the time, some disto-specific patches were added to the kernel, including one that drastically restricts BPF usage by completely disabling the use of the `bpf()` system call when lockdown is on [1].
A consequence of that decision is that no application relying on eBPF can run on 19.04/19.10, unless secure boot / lockdown is disabled. For example, Cilium (cilium.io) strongly relies on BPF programs to implement its datapath and securing network connectivity between containers. Other applications like Suricata or Sysdig also rely on BPF to some extent. None of which will work by default on a EFI machine with secure boot activated. If I understand correctly, kernel 5.4 (to be used in focal) will have a different, lighter restricton (comming from mainline Linux kernel) [2], so `bpf()` for networking use cases should mostly work on 20.04. Is my understanding correct? If so, could this patch be backported to 19.10 (and 19.04, if still supported) instead of completely disabling the syscall on lockdown? Links: [0] https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/disco/commit/?id=d0db99473fc3bb8a5d03f99ed454ac7ca5e7d517 [1] https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/disco/commit/?id=2a68c65abae66d28e2acb3245cb156ae2ea6eb1d [2] https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=9d1f8be5cf42b497a3bddf1d523f2bb142e9318c ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1863234 Title: Disabling bpf() syscall on kernel lockdown break apps when secure boot is on To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1863234/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
