Dm-crypt/Mounting at login - ArchWiki

# Dm-crypt/Mounting at login

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Related articles

- pam_mount

It is possible to configure PAM and systemd to automatically mount a dm-crypt encrypted home partition when its owner logs in, and to unmount it when he logs out.

This tutorial assumes you have already created your encrypted partition, as described in Dm-crypt/Encrypting a non-root file system.

Note:

- You need to use the same password for your user account and for LUKS.
- In all the examples, replace `YOURNAME` with your username, `1000` with your user ID and `PARTITION` with the name of your encrypted partition's device.

## Mounting at login

pam_exec can be used to unlock the device at login. Edit `/etc/pam.d/system-login` and add the line below emphasized in bold after `auth include system-auth`:

Note: GDM, LightDM, and maybe other display managers might require `pam_exec` for `session` as well, see Talk:Dm-crypt/Mounting at login#pam_exec required for session & using script.

This article or section is out of date.

Reason: These instructions no longer work. (Discuss in Talk:Dm-crypt/Mounting at login#pam LUKS partition auto mount on login returning exit code 2)

    /etc/pam.d/system-login

    ...

    auth       include    system-auth
    auth       optional   pam_exec.so expose_authtok quiet /usr/bin/cryptsetup open /dev/PARTITION home-YOURNAME

    ...

Now edit `/etc/fstab` to mount the unlocked device using systemd.automount:

    /etc/fstab

    ...

    /dev/mapper/home-YOURNAME  /home/YOURNAME     ext4            rw,noatime,noauto,x-systemd.automount 0 2

    ...

Your home directory will be mounted automatically on the first access made by your desktop environment or shell.

## Unmouting at logout

After you log out of all your sessions, systemd-logind automatically shuts down `user@1000.service`. Therefore, you can specify that your mountpoint requires it, and systemd will unmount it automatically:

    /etc/systemd/system/home-YOURNAME.mount.d/logout.conf

    [Unit]
    Requires=user@1000.service

This will however create a circular dependency loop that cannot by resolved automatically by systemd, so you need to describe the dependencies and ordering explicitly:

    /etc/systemd/system/user@1000.service.d/homedir.conf

    [Unit]
    Requires=home-YOURNAME.mount
    After=home-YOURNAME.mount

Note: If your desktop environment or some other application does not kill all its processes on logout, you might need to set `KillUserProcesses=yes` in `/etc/systemd/logind.conf`.

### Locking

After unmounting, the device will still be unlocked, and it will be possible to mount it without re-entering password. You can set up and enable a service that starts when the device gets unlocked (`BindsTo=dev-mapper-home\x2dYOURNAME.device`) and dies after the device gets unmounted (`Requires,Before=home-YOURNAME.mount`), locking the device in the process (`ExecStop=cryptsetup close`):

    /etc/systemd/system/cryptsetup-YOURNAME.service

    [Unit]
    DefaultDependencies=no
    BindsTo=dev-PARTITION.device
    After=dev-PARTITION.device
    BindsTo=dev-mapper-home\x2dYOURNAME.device
    Requires=home-YOURNAME.mount
    Before=home-YOURNAME.mount
    Conflicts=umount.target
    Before=umount.target

    [Service]
    Type=oneshot
    RemainAfterExit=yes
    TimeoutSec=0
    ExecStop=/usr/bin/cryptsetup close home-YOURNAME

    [Install]
    RequiredBy=dev-mapper-home\x2dYOURNAME.device

Note: `dev-PARTITION` is the result of `systemd-escape -p /dev/PARTITION`
Category:

- Disk encryption

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