pam_mount always deletes mount point

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#102 pam_mount always deletes mount point

Milestone: pam_mount

Status: open-works-for-me

Owner: Jan Engelhardt

Labels: pam_mount (94)

Priority: 5

Updated: 2013-12-22

Created: 2012-03-31

Creator: stefan

Private: No

I'm using pam_mount to mount and encrypted luks partition on top of LVM.

Pam_mount version 2.10 always removes a mount point even when stated in pam_mount.xml to not remove it.
System: Ubuntu 12.04 x64 beta1
pam_mount version 2.10
pam_mount.xml: http://pastebin.com/3BmesDBs
I've had the mkmountpoint enabled with enable=0, remove=false; enable=1, remove=false; and completely commented. Everytime when I reboot the mountpoint gets deleted.
After I login to the system and create the mountpoint manually the mount command works normal.

Let me know if you need more details.

Discussion

Blue Duck - 2012-07-24

Exctly same issue here, for weeks. Any progress in resolution?

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Jan Engelhardt - 2012-07-30

I cannot reproduce your problem. Also note that pam_mount only runs when you login, and when you logout. If the directory disappears during reboot, that is a problem of your distribution and/or how you set your system configuration up.

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Jan Engelhardt - 2012-07-30

status: open --> pending-works-for-me
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stefan - 2012-08-01

status: pending-works-for-me --> open-works-for-me
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stefan - 2012-08-01

Just throwing down a couple of ideas until I get to test:

Have you tried reproducing it in ubuntu 12.04 or on another disto?
How are you trying to reproduce it ? Maybe I can help you with that.

How can the "distro" delete a sub-directory in the /media directory but not any of the other sub-directories ?
How can it delete just the sub-directory that has been specified in the pam_mount.xml ?

This worked fine in previous versions of pam_mount, last time I tried it in ubuntu 11.04 I think.

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stefan - 2012-08-01

This is what I've done to successfully reproduce the problem on my laptop.

I've moved pam_mount.xml out of /etc
I've manually created /meda/<dir> ( mountpoint )
Reboot
As expected, the directory is still there after the reboot.
Moved pam_mount.xml in its place in /etc
Reboot
The /media/<dir> is not there anymore.

This makes me point a finger at pam_mount for the deletion of the mount point.
Let me know if you need other details.

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Jan Engelhardt - 2012-08-01

>Have you tried reproducing it in ubuntu 12.04 or on another disto?

openSUSE 12.1, the one I am developing on.

>How are you trying to reproduce it ? Maybe I can help you with that.

I change to another user with "su - gt" (gt is my other trash user), for which volume(s) are configured depending on whatever I have to debug. For use with your problem, I reused what I had left in:

<volume user="gt" path="/home/gt" mountpoint="/home/foo/bar/gt"
options="bind"/>

/home/foo does not exist; on login, so pam_mount will create /home/foo/bar/gt (because it did not exist and I have enable="1"), and on logout, pam_mount 2.13 will also remove /home/foo/bar/gt (but not /home/foo/bar nor /home/foo), because pam_mount itself was the creator of the mountpoint, and because remove=1.

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Jan Engelhardt - 2012-08-01

Keep in mind that /media may be configured by certain advanced distributions (particularly those with systemd) to be a tmpfs, since /media is only meant to hold dirs to more mountpoints (for attached USB disks, etc.). As tmpfs is volatile, its content may be cleared across reboots.

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stefan - 2012-08-01

I can confirm that /media is not mounted as tmpfs.

Filesystem Size Used Avail Use% Mounted on
/dev/sda2 155G 122G 26G 83% /
udev 3.9G 12K 3.9G 1% /dev
tmpfs 1.6G 1.2M 1.6G 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 3.9G 344K 3.9G 1% /run/shm

Any idea what else to troubleshoot ?
In my case pam_mount has not been the creator of the mountpoint. Should it delete the mountpoint ?
I have this in the settings xml

<volume user="stefan" fstype="crypt" path="/dev/disk/by-uuid/d39c4101-9ac7-4b9c-89da-16e3d544b0c6" mountpoint="/media/truecrypt1" options="fsck,relatime" />



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Jan Engelhardt - 2012-08-01

pam_mount should never delete a mntpt it has not created.

To that end, I identified one spot where it might do that nevertheless... on login, when mounting of a volume fails, versions up to and including 2.13 will unconditionally attempt to rmdir the directory.

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stefan - 2012-08-01

As promising as your find looks, how can I troubleshoot further ?

In my case the lvm gets mounted correctly, once I'm logged in all I have to do is create /media/truecrypt1 ( mountpoint ) and then
mount /media/truecrypt1
I don't mount the underlying lvm manually.

Any ideas how I can troubleshoot further ?
How do you troubleshoot on your machine ?

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stefan - 2012-08-12

Another test that I've ran:
I've changed the mount point location in pam_mount.xml and in /etc/fstab to point to /home/stefan/truecrypt1
I've created the directory manually
After rebooting the directory gets removed ( I suspect by pam-mount ) since this directory is located in my home directory and it is not in any system accessed directories.

Any other thoughts on how to troubleshoot ?

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Jan Engelhardt - 2012-08-13

Make sure that you only log in as root - on the text console tty1 perhaps -, and from there, use `su - stefan` to execute pam_mount on change to and from stefan. The directory should not be removed.

If for some reason, pam_mount is executed on reboot (it should not), you would find appropriate messages in /var/log/messages at the time of shutdown.

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stefan - 2013-12-22

I gave pam_mount another try and this time it is succesfully mounting my encrypted partition.

System: Ubuntu 13.10 x64
pam_mount version 2.14

$ dpkg -l libpam-mount ii libpam-mount 2.14~zgit3+966c6bea-3 amd64 PAM module that can mount volumes for a user session

From my point of view this bug looks like it has been fixed.
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