Allow signed kernels to be kexec'ed under lockdown

[Thadeu Lima de Souza Cascardo]

[Impact]
Under kernel lockdown, one can't kexec unless it's using kexec_file_load with a signed kernel.

[Test case]
It was verified that a signed kernel could be loaded with kexec -s, and properly booted.

[Regression Potential]
A security issue, as we allow more kernels to be loaded than we would like to. Though, that's already the case in cosmic.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1798441

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Brad Figg (brad-figg)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed-bionic'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-42.45

---------------
linux (4.15.0-42.45) bionic; urgency=medium

  * linux: 4.15.0-42.45 -proposed tracker (LP: #1803592)

  * [FEAT] Guest-dedicated Crypto Adapters (LP: #1787405)
    - KVM: s390: reset crypto attributes for all vcpus
    - KVM: s390: vsie: simulate VCPU SIE entry/exit
    - KVM: s390: introduce and use KVM_REQ_VSIE_RESTART
    - KVM: s390: refactor crypto initialization
    - s390: vfio-ap: base implementation of VFIO AP device driver
    - s390: vfio-ap: register matrix device with VFIO mdev framework
    - s390: vfio-ap: sysfs interfaces to configure adapters
    - s390: vfio-ap: sysfs interfaces to configure domains
    - s390: vfio-ap: sysfs interfaces to configure control domains
    - s390: vfio-ap: sysfs interface to view matrix mdev matrix
    - KVM: s390: interface to clear CRYCB masks
    - s390: vfio-ap: implement mediated device open callback
    - s390: vfio-ap: implement VFIO_DEVICE_GET_INFO ioctl
    - s390: vfio-ap: zeroize the AP queues
    - s390: vfio-ap: implement VFIO_DEVICE_RESET ioctl
    - KVM: s390: Clear Crypto Control Block when using vSIE
    - KVM: s390: vsie: Do the CRYCB validation first
    - KVM: s390: vsie: Make use of CRYCB FORMAT2 clear
    - KVM: s390: vsie: Allow CRYCB FORMAT-2
    - KVM: s390: vsie: allow CRYCB FORMAT-1
    - KVM: s390: vsie: allow CRYCB FORMAT-0
    - KVM: s390: vsie: allow guest FORMAT-0 CRYCB on host FORMAT-1
    - KVM: s390: vsie: allow guest FORMAT-1 CRYCB on host FORMAT-2
    - KVM: s390: vsie: allow guest FORMAT-0 CRYCB on host FORMAT-2
    - KVM: s390: device attrs to enable/disable AP interpretation
    - KVM: s390: CPU model support for AP virtualization
    - s390: doc: detailed specifications for AP virtualization
    - KVM: s390: fix locking for crypto setting error path
    - KVM: s390: Tracing APCB changes
    - s390: vfio-ap: setup APCB mask using KVM dedicated function
    - s390/zcrypt: Add ZAPQ inline function.
    - s390/zcrypt: Review inline assembler constraints.
    - s390/zcrypt: Integrate ap_asm.h into include/asm/ap.h.
    - s390/zcrypt: fix ap_instructions_available() returncodes
    - s390/zcrypt: remove VLA usage from the AP bus
    - s390/zcrypt: Remove deprecated ioctls.
    - s390/zcrypt: Remove deprecated zcrypt proc interface.
    - s390/zcrypt: Support up to 256 crypto adapters.
    - [Config:] Enable CONFIG_S390_AP_IOMMU and set CONFIG_VFIO_AP to module.

  * Bypass of mount visibility through userns + mount propagation (LP: #1789161)
    - mount: Retest MNT_LOCKED in do_umount
    - mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED mounts

  * CVE-2018-18955: nested user namespaces with more than five extents
    incorrectly grant privileges over inode (LP: #1801924) // CVE-2018-18955
    - userns: also map extents in the reverse map to kernel IDs

  * kdump fail due to an IRQ storm (LP: #1797990)
    - SAUCE: x86/PCI: Export find_cap() to be used in early PCI code
    - SAUCE: x86/quirks: Add parameter to clear MSIs early on boot
    - SAUCE: x86/quirks: Scan all busses for early PCI quirks

 -- Thadeu Lima de Souza Cascardo <email address hidden> Thu, 15 Nov 2018 17:01:46 ...

[Andy Whitcroft (apw)]

This bug was erroneously marked for verification in bionic; verification is not required and verification-needed-bionic is being removed.