can't open a tomb on sshfs (ubuntu lucid)

[boyska]

That's a strange issue. Here's the scenario. A tomb is on a remote server. The key is on our usb pen. We mount the remote server filesystem using sshfs. tomb has troubles when opening it.

Some notes:

• file $tombname detects it correctly
• deleting the check does not solve the problem: cryptsetup fails
• copying the tomb on local filesystem make it work
• lot of ssh servers tried

This bug does NOT happen on archlinux. So, I think the problem is on a old version of cryptsetup. on archlinux I have cryptsetup 1.4.1; every ubuntu version has cryptsetup 1.1 (so upgrading to natty narwal won't solve); debian stable has 1.1, testing and unstable has 1.3

Can anyone check this on as much platform/combination to confirm/disprove my hypothesis?

It would be especially good to know WHICH version of cryptsetup is required to do this and if there is a workaround

EDIT: it happens on archlinux, too. It seems a permission problem, see below.

[jaromil]

damn, now I kind of understand why truecrypt ships their own cryptsetup :/

[jaromil]

check made with Tomb 1.2 (current stable) also from arch doesn't mount a tomb over sshfs. file on file tomb gives:

16:48 LUKS encrypted file, ver 1 [aes, cbc-essiv:sha256, sha1] UUID: c4c4ac8c-dad8-4bfa-bc80-30b1200543f7

instead cryptsetup isLuks gives a 1 and the error is:

16:53 Impossibile trovare un device di loopback libero.

which to us right now means the loopback device limit is reached by mounting an sshfs.

how stoopid from a distro to keep such a limit so low...

[boyska]

o0 that's odd. This would also mean that mounting two tombs will make losetup reach the limit? and, is there a way to increase the number of loopback devices with a command? (btw, is sshfs a loopback device ? I did not think so)

[nignux]

Il giorno Wed, 18 Jan 2012 03:52:57 -0800 BoySka reply@reply.github.com ha scritto:

That's a nasty issue. Here's the scenario. A tomb is on a remote server. The key is on our usb pen. We mount the remote server filesystem using sshfs. tomb has troubles when opening it.

Some notes:

• file $tombname detects it correctly
• deleting the check does not solve the problem: cryptsetup fails
• copying the tomb on local filesystem make it work
• lot of ssh servers tried

This bug does NOT happen on archlinux. So, I think the problem is on a old version of cryptsetup. on archlinux I have cryptsetup 1.4.1; every ubuntu version has cryptsetup 1.1 (so upgrading to natty narwal won't solve); debian stable has 1.1, testing and unstable has 1.3

This is not correct, I have archlinux too so the same version of cryptsetup.

I think that is a permissions issue because if I mount as root with sshfs there are no problems whit the cryptsetup check but if I try as normal user it fails.

Can anyone check this on as much platform/combination to confirm/disprove my hypothesis?

It would be especially good to know WHICH version of cryptsetup is required to do this and if there is a workaround

How do you mount your remote fs with sshfs?

[ nignux ----------------------------------------- nignux@freaknet.org ] [ GPG-ID:: 28B4358A ------------------------------- http://pgp.mit.edu ] [ GPG-Fingerprint:: 24E1 483B 7BE1 0853 87DA C1E4 3915 F8AC 28B4 358A ]

[boyska]

thanks for your testing nignux. Indeed, I have double-checked and you're right. doing sudo sshfs works, doing sshfs as user does not work. The problem, I suppose, is that root cannot access an sshfs mounting.

$ sshfs blah@host /mount/point
$ sudo bash
# cd /mount/point
bash: cd: point: Permesso negato

so it cannot access the tomb.

So, it seems it's NOT a cryptsetup issue, but an sshfs issue; maybe there is an option which enables root access to sshfs.

[nignux]

Il giorno Sun, 22 Jan 2012 04:53:17 -0800 BoySka reply@reply.github.com ha scritto:

thanks for your testing nignux. Indeed, I have double-checked and you're right. doing sudo sshfs works, doing sshfs as user does not work. The problem, I suppose, is that root cannot access an sshfs mounting.

$ sshfs blah@host /mount/point
$ sudo bash
# cd /mount/point
bash: cd: point: Permesso negato

so it cannot access the tomb.

So, it seems it's NOT a cryptsetup issue, but an sshfs issue; maybe there is an option which enables root access to sshfs.

Yes and IT WORKS.

sshfs -o allow_root user@remote.host:/ /local/mountpoint/

[ nignux ----------------------------------------- nignux@freaknet.org ] [ GPG-ID:: 28B4358A ------------------------------- http://pgp.mit.edu ] [ GPG-Fingerprint:: 24E1 483B 7BE1 0853 87DA C1E4 3915 F8AC 28B4 358A ]

[boyska]

if this is confirmed as a solution (I think so), it can be closed documenting it (it's not strictly tomb-related, but it is a common setup, so we should document it, I think)

[jaromil]

yes should be documented, thanks guys for finding it, that was itchy scratchy

[boyska]

who wants to be the first to write it? :) https://github.com/dyne/Tomb/wiki/TombSshfs

[jaromil]

closing the issue, as it was solved a year ago.