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Pryka

Member

Registered: 2018-02-07

Posts: 85

[SOLVED]Can I corrupt data by skipping ecryptfs-umount-private?

Hi!

I'm currently using ecryptfs on my /home dir.  With automount/umount option when login/logout to user account. But since unmount is susceptible to break it don't really work. And I don't mind it.

But I have question regarding it. Is it safe not to do ecryptfs-umount-private before restart or shutdown? Can I corrupt my data by not using it but just shutting down machine?

Last edited by Pryka (2018-03-15 11:31:17)

jaergenoth

Member

Registered: 2015-01-16

Posts: 85

Re: [SOLVED]Can I corrupt data by skipping ecryptfs-umount-private?

If you are automounting it with the PAM-module, it is unmounted automatically.

The system administrator can add the pam_ecryptfs.so module to the PAM stack and automatically perform the unmount on logout.

ecryptfs-umount-private is just a wrapper script that calls umount and also clears the kernel keyring.

Edit:
You are right that the unmounting of ecryptfs automatically after logout seems to be bugged; it never worked when I still used it.
But when the system is being powered off, all pending writes are written to the disks and then after that all filesystems are unmounted (umount.ecryptfs_private gets called).
So it's perfectly fine to not manually unmount it.

Last edited by jaergenoth (2018-03-15 11:06:42)

frostschutz

Member

Registered: 2013-11-15

Posts: 1,658

Re: [SOLVED]Can I corrupt data by skipping ecryptfs-umount-private?

Well, the possibilities roughly are

a) it manages to umount the ecryptfs on shutdown anyway,

b) it doesn't manage to, so /home can't be umounted and will be re-mounted read-only instead,

c) the remount read-only fails too

If you get a), it would be perfect... b) would be still acceptable... c) might be bad.

Pryka

Member

Registered: 2018-02-07

Posts: 85

Re: [SOLVED]Can I corrupt data by skipping ecryptfs-umount-private?

If you are automounting it with the PAM-module, it is unmounted automatically.

The system administrator can add the pam_ecryptfs.so module to the PAM stack and automatically perform the unmount on logout.

ecryptfs-umount-private is just a wrapper script that calls umount and also clears the kernel keyring.

Edit:
You are right that the unmounting of ecryptfs automatically after logout seems to be bugged; it never worked when I still used it.
But when the system is being powered off, all pending writes are written to the disks and then after that all filesystems are unmounted (umount.ecryptfs_private gets called).
So it's perfectly fine to not manually unmount it.

Oh. Thank you for the info. I'm little calmer right now.

Well, the possibilities roughly are

a) it manages to umount the ecryptfs on shutdown anyway,

b) it doesn't manage to, so /home can't be umounted and will be re-mounted read-only instead,

c) the remount read-only fails too

If you get a), it would be perfect... b) would be still acceptable... c) might be bad.

I found this in my logs:

mar 15 10:49:57 Iluvatar systemd[1]: Unmounting /home...
mar 15 10:49:57 Iluvatar systemd[1]: Unmounted /home.

It looks that my /home is unmounting fine.

EDIT:
Probably solved then. Will add a mark to the topic.

Last edited by Pryka (2018-03-15 11:30:54)