LUKS decrypted partition mapped name

Francesco

5/22/24, 11:49 AM

I've successfully configured LUKS encryption on various partitions (root, home, extra) on ubuntu 22.04. I've to insert a password for decrypting the root part and after other partitions are decrypted using a file that is inside the root partition.

Everything works but there's an annoying thing:

the home partition /dev/nvme0n1p7, this is the crypttab file:

nvme0n1p6_crypt UUID=6566c7ae-f3f7-464f-8eb7-bec2a5499d82 none luks,discard
nvme0n1p7_crypt UUID=d50b5303-b96a-4a69-9512-a7e276e66be7 /etc/luks/boot_os.keyfile luks,discard,noearly
nvme0n1p8_crypt UUID=7790ba4d-aff2-4305-83cf-a259cbbb721f /etc/luks/boot_os.keyfile luks,discard,noearly
nvme0n1p4_crypt UUID=ac79140b-5c17-4c4b-8d33-c30241ad63ee /etc/luks/boot_os.keyfile luks,discard

here the fstab:

/dev/mapper/nvme0n1p6_crypt /               ext4    errors=remount-ro 0       1
/dev/nvme0n1p1              /boot           ext4    defaults          0       2
UUID=B960-650F              /boot/efi       vfat    umask=0077        0       1
/dev/mapper/home            /home           ext4    defaults          0       2
/dev/mapper/nvme0n1p8_crypt /works          ext4    defaults          0       2
/dev/mapper/nvme0n1p4_crypt none            swap    sw                0       0

I had to change mapped device that is mounted as home to /dev/mapper/home instead of /dev/mapper/nvme0n1p7_crypt because otherwise the system doesn't boot properly.

Other partitions mapper devices are following the crypttab file.

I really don't understand why. Where can this "home" alias be configured? This partition has a /home label, can this the reason why this name is used? Strange that it's not used with other partitions tho.

EDIT: Removed noearly because it seems it's not used:

May 24 10:35:39 think systemd-cryptsetup[1567]: Encountered unknown /etc/crypttab option 'noearly', ignoring.

EDIT AGAIN: This morning during a boot the encrypted partition has been decrypted with the correct name /dev/mapper/nvme0n1p7_crypt but after changing the fstab on the next reboot the mapped device was again /dev/mapper/home. I think it depends on when this operation is done but I cannot find any documentation around this

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Sebastian

5/22/24, 5:35 PM

Is that the content of your `/etc/crypttab`? Can you post the entire content of `/etc/crypttab` and `/etc/fstab`?

Francesco

5/22/24, 10:14 PM

@Sebastian added the full content of the two files you asked for in the question

Sebastian

5/23/24, 9:21 PM

Thanks. What do you mean by "the system doesn't boot properly"? Maybe you can try removing the `noearly` option from the entry in question, not sure that is the reason but it's worth a shot.

Francesco

5/24/24, 10:03 AM

@Sebastian the home partition isn't mounted and GDM doesn't start but only a shell is dropped. This morning it happened that the partition has been mounted with the `nvme0n1p7_crypt` name once and after changing `fstab` accordingly again on the next reboot it was again back to `home`. I think it's something related to when the part is mounted. I've removed the `noearly` already also because it seems it's not used: `May 24 10:35:39 think systemd-cryptsetup[1567]: Encountered unknown /etc/crypttab option 'noearly', ignoring.`

Sebastian

5/25/24, 6:03 PM

I'm afraid I am at a loss as to what happens. The only thing I can imagine is that something goes wrong during the boot/decryption process. The fact that it seems to occur randomly suggests there might be some timing problem. I would maybe try to decrypt the home partition with a password instead of a keyfile (you can add it as a second keyslot) and see if that works.

Elon Musk

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