group.of.nepali.translators team mailing list archive

[Tyler Hicks <tyhicks@xxxxxxxxxxxxx>]

Xenial doesn't have support for lifting lockdown features via sysrq so
I'm marking its task as invalid.

** Also affects: linux (Ubuntu Bionic)
   Importance: Undecided
       Status: New

** Also affects: linux (Ubuntu Xenial)
   Importance: Undecided
       Status: New

** Also affects: linux (Ubuntu Focal)
   Importance: High
     Assignee: Tyler Hicks (tyhicks)
       Status: In Progress

** Also affects: linux (Ubuntu Disco)
   Importance: Undecided
       Status: New

** Also affects: linux (Ubuntu Eoan)
   Importance: Undecided
       Status: New

** Changed in: linux (Ubuntu Eoan)
   Importance: Undecided => High

** Changed in: linux (Ubuntu Eoan)
       Status: New => In Progress

** Changed in: linux (Ubuntu Disco)
       Status: New => In Progress

** Changed in: linux (Ubuntu Disco)
   Importance: Undecided => High

** Changed in: linux (Ubuntu Bionic)
       Status: New => In Progress

** Changed in: linux (Ubuntu Bionic)
   Importance: Undecided => High

** Changed in: linux (Ubuntu Disco)
     Assignee: (unassigned) => Tyler Hicks (tyhicks)

** Changed in: linux (Ubuntu Bionic)
     Assignee: (unassigned) => Tyler Hicks (tyhicks)

** Changed in: linux (Ubuntu Eoan)
     Assignee: (unassigned) => Tyler Hicks (tyhicks)

** Changed in: linux (Ubuntu Xenial)
       Status: New => Invalid

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https://bugs.launchpad.net/bugs/1861238

Title:
  Root can lift kernel lockdown via USB/IP

Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Xenial:
  Invalid
Status in linux source package in Bionic:
  In Progress
Status in linux source package in Disco:
  In Progress
Status in linux source package in Eoan:
  In Progress
Status in linux source package in Focal:
  In Progress

Bug description:
  [Impact]

  It's possible to turn off kernel lockdown by emulating a USB keyboard
  via USB/IP and sending an Alt+SysRq+X key combination through it.

  Ubuntu's kernels have USB/IP enabled (CONFIG_USBIP_VHCI_HCD=m and
  CONFIG_USBIP_CORE=m) with signed usbip_core and vhci_hcd modules
  provided in the linux-extra-modules-* package.

  See the PoC here: https://github.com/xairy/unlockdown#method-1-usbip

  [Test Case]

  $ git clone https://github.com/xairy/unlockdown.git
  $ cd unlockdown/01-usbip/
  $ sudo ./run.sh
  $ dmesg

  # Ensure there are no log entries talking about lifting lockdown:
  sysrq: SysRq : Disabling Secure Boot restrictions
  Lifting lockdown

  # You should see a SysRq help log entry because the Alt+SysRq+X
  # combination should be disabled
  sysrq: SysRq : HELP : loglevel(0-9) reboot(b) crash(c) terminate-all-tasks(e) memory-full-oom-kill(f) kill-all-tasks(i) thaw-filesystems(j) sak(k) show-backtrace-all-active-cpus(l) show-memory-usage(m) nice-all-RT-tasks(n) poweroff(o) show-registers(p) show-all-timers(q) unraw(r) sync(s) show-task-states(t) unmount(u) force-fb(V) show-blocked-tasks(w) dump-ftrace-buffer(z)

  [Regression Potential]

  Some users may see a usability regression due to the Lockdown lift
  sysrq combination being removed. Some users are known to disable
  lockdown, using the sysrq combination, in order to perform some
  "dangerous" operation such as writing to an MSR. It is believed that
  this is a small number of users but it is impossible to know for sure.

  Users that rely on this functionality may need to permanently disable
  secure boot using 'mokutil --disable-validation'.

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