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Thread: NBDE (clevis and tang) support in 18.04

  1. #1
    Join Date
    Jun 2018
    Beans
    1

    Unhappy NBDE (clevis and tang) support in 18.04

    Running Ubuntu 18.04 with an unencrypted root volume. For what I need this to do, that's fine. But I need to mount and decrypt secondary disks. Following Red Hat's directions here since every google search for Ubuntu and NBDE/Clevis&Tang takes me there.

    *This procedure works flawlessly on RHEL 7.x and CentOS 7.x.

    I've gotten as far as partitioning (not using LVM here), encrypting, binding it to a tang server.
    First I install the packages:

    Code:
    apt-get install clevis clevis-systemd clevis-dracut clevis-luks
    Then I set up the disk

    Code:
    echo '<TEMPPASS>'| cryptsetup --verbose luksFormat /dev/xvdc1
    Code:
    clevis bind luks -f -k- -d /dev/xvdc1 tang '{"url":"http://<IP>:<PORT>","thp":"<KEY>"}' <<< "<TEMPPASS>"
    Get rid of the temporary passkey

    Code:
    echo "<TEMPPASS>" | cryptsetup luksRemoveKey /dev/xvdc1
    Unlock the device

    Code:
    clevis luks unlock -d /dev/xvdc1 -n testluksvol
    And Bob's your Auntie. Then I format it and verify it can mount.

    Code:
    mkfs.ext4 /dev/mapper/testluksvol
    Code:
    mount /dev/mapper/testluksvol /testluksvol
    So far so good. I add the entries to /etc/fstab using _netdev as the directions said:

    Code:
    /dev/mapper/testluksvol /testluksvol    ext4    defaults,_netdev 0 2
    Add the entry to /etc/crypttab, also with _netdev, though I didn't think Ubuntu crypttab supported that since it isn't in the crypttab manpage, but whatevs. We're making Chef Boy'R'D here, not world class bolognese:

    Code:
    testluksvol     UUID=<DEVICE UUID>       none    _netdev
    And finally, enable clevis-luks-askpass.path

    Code:
    systemctl enable clevis-luks-askpass.path
    Then we reboot... and it doesn't work. No auto decrypt, no auto mount. It sits for a bit running a job for the device before finally giving up and finishing the boot. So we go look in /var/log/syslog and see this:

    Code:
    Jun 22 23:06:22 ubuntu03 systemd[1]: dev-disk-by\x2duuid-72ebf50e\x2dc3de\x2d468a\x2d89c3\x2defc869757a51.device: Job dev-disk-by\x2duuid-72ebf50e\x2dc3de\x2d468a\x2d89c3\x2defc86975
    7a51.device/start timed out.
    Jun 22 23:06:22 ubuntu03 systemd[1]: Timed out waiting for device dev-disk-by\x2duuid-72ebf50e\x2dc3de\x2d468a\x2d89c3\x2defc869757a51.device.
    Jun 22 23:06:22 ubuntu03 systemd[1]: Dependency failed for Cryptography Setup for testluksvol.
    Jun 22 23:06:22 ubuntu03 systemd[1]: Dependency failed for dev-mapper-testluksvol.device.
    Jun 22 23:06:22 ubuntu03 systemd[1]: Dependency failed for /testluksvol.
    Jun 22 23:06:22 ubuntu03 systemd[1]: Dependency failed for Remote File Systems.
    Jun 22 23:06:22 ubuntu03 systemd[1]: remote-fs.target: Job remote-fs.target/start failed with result 'dependency'.
    Jun 22 23:06:22 ubuntu03 systemd[1]: testluksvol.mount: Job testluksvol.mount/start failed with result 'dependency'.
    Jun 22 23:06:22 ubuntu03 systemd[1]: Dependency failed for File System Check on /dev/mapper/testluksvol.
    Jun 22 23:06:22 ubuntu03 systemd[1]: systemd-fsck@dev-mapper-testluksvol.service: Job systemd-fsck@dev-mapper-testluksvol.service/start failed with result 'dependency'.
    Jun 22 23:06:22 ubuntu03 systemd[1]: dev-mapper-testluksvol.device: Job dev-mapper-testluksvol.device/start failed with result 'dependency'.
    Jun 22 23:06:22 ubuntu03 systemd[1]: Dependency failed for Local Encrypted Volumes.
    Jun 22 23:06:22 ubuntu03 systemd[1]: cryptsetup.target: Job cryptsetup.target/start failed with result 'dependency'.
    Jun 22 23:06:22 ubuntu03 systemd[1]: systemd-cryptsetup@testluksvol.service: Job systemd-cryptsetup@testluksvol.service/start failed with result 'dependency'.
    Jun 22 23:06:22 ubuntu03 systemd[1]: dev-disk-by\x2duuid-72ebf50e\x2dc3de\x2d468a\x2d89c3\x2defc869757a51.device: Job dev-disk-by\x2duuid-72ebf50e\x2dc3de\x2d468a\x2d89c3\x2defc86975
    7a51.device/start failed with result 'timeout'.
    This is a bit beyond frustrating. I got 18.04 specifically because it was supposed to have support for clevis & tang. I wanted to integrate it into an existing env that is running tang servers.
    Can anyone, for the love of Linus Torvalds, tell me what I'm doing wrong?

    *Update: I discovered that my disk UUID was wrong. Hence broken. Once I updated that, things worked correctly. I'm embarrassingly closing this help request.

    Last edited by rkramer1; June 28th, 2018 at 09:03 PM. Reason: Solved the problem

  2. #2
    Join Date
    Nov 2006
    Beans
    83

    Re: NBDE (clevis and tang) support in 18.04

    Thanks for sharing your setup!

    Did you manage to get Clevis to work with an encrypted root volume?

    I'm trying but it seems that dracut won't bring up the network at initramfs stage; at least I can't see the client requesting a DHCP lease and I can't ping it at the root password prompt. Once root is decrypted everything works fine.

    How can I enable networking in dracut? I already ran

    Code:
    dracut -f --kernel-cmdline "ip=dhcp"
    and during dracut initialization it tells me that the networking module is enabled:
    Code:
    *** Including module: network ***
    but still no network at the LUKS password prompt.
    Those Who Sacrifice Liberty For Security Deserve Neither. - Benjamin Franklin

  3. #3
    Join Date
    Nov 2018
    Beans
    8

    Re: NBDE (clevis and tang) support in 18.04

    Re Dracut and Networking in 18.04: I've actually just ran into this same problem. Doesn't happen in KVM of course. Did you find a solution?

  4. #4
    Join Date
    Nov 2006
    Beans
    83

    Re: NBDE (clevis and tang) support in 18.04

    Unfortunately not. Is it working on KVM for you? Maybe a required driver or module is missing in the initramfs.
    Those Who Sacrifice Liberty For Security Deserve Neither. - Benjamin Franklin

  5. #5
    Join Date
    Nov 2018
    Beans
    8

    Re: NBDE (clevis and tang) support in 18.04

    Yes, I've gotten it working with KVM. As virtual machines aren't a target of this project that's rather meaningless. I was hoping to find a solution to this quickly but as all projects go my attention got diverted. I'd really like to avoid pulling in an un-merged patch just to get NBDE working in my enterprise environment. https://github.com/latchset/clevis/pull/35

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