** Changed in: ubuntu-z-systems
Status: New => Invalid
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https://bugs.launchpad.net/bugs/1875826
Title:
Kdumping on an Ubuntu 20.04 guest with an encrypted root partition
drops user to initramfs console
Status in Ubuntu on IBM z Systems:
Invalid
Status in makedumpfile package in Ubuntu:
Invalid
Status in makedumpfile source package in Focal:
Invalid
Status in makedumpfile source package in Groovy:
Invalid
Bug description:
Kdump log
---Problem Description---
The expectation for Secure Execution is that users encrypt their root device
as part of the setup process. However, Kdumping on an Ubuntu 20.04 guest with
an encrypted root partition drops user to initramfs console. When attempted on
a non-secure, but encrypted guest, results came out to be the same.
---uname output---
Linux T257KVX 5.4.0-21-generic #25-Ubuntu SMP Sat Mar 28 13:10:00 UTC 2020
s390x s390x s390x GNU/Linux
Machine Type = Type: 8562 Model: A00, LT2
---Debugger---
A debugger is not configured
---Steps to Reproduce---
1. Create a guest with an encrypted root partition. Encryption was done
using the process available within the install.
virt-install --name ali-kdump-enc --vcpu 2 --memory 4096 --disk
size=8,path=/guestimages/ali-kdump-enc.qcow2,driver.iommu=on --network
network=default,model=virtio,driver.iommu=on --controller type=virtio-
serial,driver.iommu=on --controller type=scsi,driver.iommu=on
--memballoon none --boot hd --cdrom http://cdimage.ubuntu.com/ubuntu-
server/daily-live/current/focal-live-server-s390x.iso
2. Install linux-crashdump
apt install linux-crashdump
3. Proceed through to converting the guest into a secure one, taking extra
steps to make the crashkernel large enough to accommodate the swiotlb (I used
1G)
sudo genprotimg -r /boot/initrd.img -p parmfile -i /boot/vmlinuz --no-verify
-o /boot/secure-linux -V -k T257.crt
4. zipl and reboot into the now secured guest
5. Verify that kdump is ready
- kdump-config show
- kdump-config status
- cat /sys/kernel/kexec_crash_size
6. Trigger a dump
sudo sysctl -w kernel.sysrq=1
echo c > /proc/sysrq-trigger
However, when this happens, I get the results presented in the kdump-
sec-enc.log file.
I suspected it was due to the root partition being encrypted and
expecting a password on startup (as this happened on an encrypted,
non-secure guest, but not on their non-encrypted counterparts), so I
attempted to setup a keyfile on a new guest that I created before the
installation of linux-crashdump, and conversion into a secure guest
using the following set of steps.
1. Create the key file in the unencrypted /boot partition
# dd if=/dev/urandom of=/boot/keyfile bs=1024 count=4
2. Set permissions
# chmod 0400 /boot/keyfile
3. Add the new file as unlock key to the encrypted volume
# cryptsetup -v luksAddKey /dev/vda2 /boot/keyfile
Enter any passphrase:
Enter your old/existing passphrase here. Expected output:
Key slot 0 unlocked.
Command successful.
4. Update /etc/crypttab with the line:
vda2_crypt UUID=684af433-487f-4c81-b310-81338a49588d /boot/keyfile luks
5. Update /etc/cryptsetup-initramfs/conf-hook to allow enable your keyfile at
boot, e.g.:
KEYFILE_PATTERN=/boot/keyfile
6. Update initramfs with the following: update-initramfs -u
This will bypass the request for a password on boot, however, I still
ran into the same errors presented in the log file (kdump-sec-
enc.log).
-Post a private note with access information to the machine that the
bug is occuring on.
Guest Log
Guest's qemu log file
The kernel version for the guest that this was executed on is as follows:
xxxxx-kdump-sec-enc:~$ uname -r
5.4.0-26-generic
The host is slightly behind, but the bug takes place in context of the
guest's starting and stopping
Canonical, please advice on how to enable dumping onto an encrypted
volume to maintain confidentiality.
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