Hi fellow selfhoster,

Im a bit lost on the following scenario and im unable to find any documentation about it so i was hoping some smart people here could point me in the right direction.

I have a linux software raid 6 that contains a LUKS partition with ext4 in it. I would like to automount the ext4 when im rebooting. The root partition is also using LUKS and i have successfully setup the decryption for this parition but im uncertain on how to do this with this raid setup since im not sure where in the boot process linux recognizes my raid and when the decryption happens.

This is what i have:

[root@nfs-rocky-1 ~]# cat /etc/mdadm.conf
ARRAY /dev/md/server1:0 metadata=1.2 UUID=3e198408:2236ed3d:1dc13a8e:e5f91e52

On a reboot the raid does get automaticly recognizes but i still have to do cryptsetup luksOpen /dev/md0 raid & mount /dev/mapper/raid /mnt/data.

What would be the best way to do this? Im a bit scared of doing this im not certain of since i don’t want my machine to be stuck at a boot.

Just a like to an article that dicusses something like this already would help me greatly.

    • Hercules@lemmy.worldOPEnglish
      1·
      4 months ago

      Is the /etc/crypttab.d path that you are using specificly chosen or can it be whatever? This path doesn’t exists on my system and online i don’t see any mentions of it.

      • nublug@piefed.blahaj.zoneEnglish
        1·
        4 months ago

        the crypttab.d thing is called a drop-in directory. linux will read files you make in these and overwrite the config files with the values in the drop-in files. it’s a way to add your own edits to config files without editing the default config files directly, so you don’t have to say manually copy crypttab to crypttab.old for a backup and instead always have a default config to fall back to if things go wrong by just commenting out your few changes in the drop-in file.

    • Hercules@lemmy.worldOPEnglish
      1·
      4 months ago

      :D while your steps were very clear i think i fked up.

      cryptsetup luksAddKey /dev/mapper/raid /etc/crypttab.d/keyfile-data.bin --new-key-slot 1 gave: Device /dev/mapper/raid is not a valid LUKS device.. I assume this is a typo from your end since /dev/md0 is my luks volume. But altering this gave me: slot is already in use kind of error.

      That can be explained since i tested something simular like you suggested earlier. Afterwhich i removed my key i generated and added to the volume. Then i did cryptsetup luksRemoveKey /dev/md0.

      Now when i try to add it i get No key available with this passphrase.

      I don’t have enough knowledge about cryptsetup to know what excactly i did wrong.

      Do you by any change have an explaination?

      In case this is usefull:

      [root@nfs-rocky-1 ~]# cryptsetup luksDump /dev/md0
LUKS header information
Version:       	2
Epoch:         	6
Metadata area: 	16384 [bytes]
Keyslots area: 	16744448 [bytes]
UUID:          	485df758-6cec-49e3-aceb-438aaaedc833
Label:         	(no label)
Subsystem:     	(no subsystem)
Flags:       	(no flags)

Data segments:
  0: crypt
	offset: 16777216 [bytes]
	length: (whole device)
	cipher: aes-xts-plain64
	sector: 4096 [bytes]

Keyslots:
  1: luks2
	Key:        512 bits
	Priority:   normal
	Cipher:     aes-xts-plain64
	Cipher key: 512 bits
	PBKDF:      argon2id
	Time cost:  4
	Memory:     1048576
	Threads:    4
	Salt:       17 c5 ff 7f b9 10 43 41 16 5a c8 28 44 b9 df 64
	            a8 1d 40 41 9f a1 70 85 34 06 52 8d ba 29 bd ef
	AF stripes: 4000
	AF hash:    sha256
	Area offset:290816 [bytes]
	Area length:258048 [bytes]
	Digest ID:  0
  2: luks2
	Key:        512 bits
	Priority:   normal
	Cipher:     aes-xts-plain64
	Cipher key: 512 bits
	PBKDF:      argon2id
	Time cost:  12
	Memory:     1048576
	Threads:    4
	Salt:       64 97 db 49 f1 18 b9 57 3b 02 53 37 b3 11 8e 44
	            71 d1 70 b2 b9 58 4c db e2 6b 36 95 7c dd d2 be
	AF stripes: 4000
	AF hash:    sha256
	Area offset:548864 [bytes]
	Area length:258048 [bytes]
	Digest ID:  0
Tokens:
Digests:
  0: pbkdf2
	Hash:       sha256
	Iterations: 105703
	Salt:       ae ac f1 9f df 47 27 9e 64 28 52 53 9a 9b cd 77
	            74 15 66 f6 8b 3c bd f4 29 dc f1 b1 c5 15 3b f6
	Digest:     07 5f 2f 6b d3 c5 bf b6 54 58 5e b4 44 df 8c b8
	            2b da fa 5c 40 a5 89 cc 0e 3b 70 69 57 d5 7c f5
[root@nfs-rocky-1 ~]#