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linus.newbert 06-22-2010 02:27 AM

livecd and encrypted home

While working on a custom livecd (based on Kubuntu 9.10 LiveCd) I stumbled upon a 100% reproducible bug (or better missing feature to go to a wishlist):
- boot from the livecd
- create a new user with admin rights and encrypted home
- logout ubuntu
- login with new user
- copy a binary into the home folder of the new user
- run it. Fails with

binary_name: Function not implemented
I saw a simmilar bug but related to a newer kernel 2.6.33. My kernel is 2.6.31-14. The bug also is reproducible for 2.6.31-20.

XavierP 06-23-2010 02:59 AM

Good find - you should also report this to the Ubuntu developers mailing list.

Welcome to LQ :)

linus.newbert 06-24-2010 07:14 AM

I did. Thanks for the suggestion. I hope it gets answered. Somehow I think its related to the whole livecd infrastructure: squashfs, initrd aso. The weird thing about it is that if I try to run the binary through valgrind (for debugging purposes) it runs just fine. Maybe that sheds some light upon the issue at stake.

linus.newbert 06-29-2010 04:04 AM

Hello again,

Tried also a simplified scenario on Lucid with similar results:
- boot from live cd
- create a user with encrypted home:

adduser --gecos "" --encrypt-home testuser
- su to the new user:

# su testuser
$ ecryptfs-mount-private

- copy a binary into home and run it

$ cp /bin/ls ~/
$ cd ~
$ ./ls
ls: Function not implemented

linus.newbert 07-07-2010 10:55 PM

It seems like a dead-end for now:


Your question #116953 on ecryptfs-utils in ubuntu changed:

Status: Open => Answered

Dustin Kirkland proposed the following answer:
This is because eCryptfs is not supported on top of any stacked
filesystems (nfs, cifs, samba, or aufs).
So I guess this qualifies for a solution to my issue ...

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