pam_mount

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pam_mount can be used to automatically mount an encrypted home partition (encrypted with, for example, LUKS or ECryptfs) on user log in. It will mount your /home (or whatever mount point you like) when you log in using your login manager or when logging in on console. The encrypted drive's passphrase should be the same as your linux user's password, so you do not have to type in two different passphrases to login.

Warning: pam_mount can also unmount your partitions when you close your last session but this does not work out of the box due to the use of pam_systemd.so in the pam stack, see Talk:Pam mount#automatic unmounting and systemd.
Note: As at November 2018, pam_mount does not yet support luks2 encrypted partitions. A workaround could be to use pam_mount-gitAUR, see [1].

General setup

Install the pam_mount package.

Edit /etc/security/pam_mount.conf.xml as follows:

/etc/security/pam_mount.conf.xml
  <!-- Generic encrypted partition example -->
  <volume user="USERNAME" fstype="auto" path="/dev/sdaX" mountpoint="/home" options="fsck,noatime" />
  
  <!-- Example using CIFS -->
  <volume
      fstype="cifs"
      server="server.example.com"
      path="share_name"
      mountpoint="~/mnt/share_name"
      uid="10000-19999"
      options="sec=krb5i,vers=3.0,cruid=%(USERUID)"
  />
  <mkmountpoint enable="1" remove="true" />

</pam_mount>

Notes:

  • Insert 2 new lines at the end of the file, but before the last closing tag, </pam_mount>.
  • USERNAME should be replaced with your user name.
  • /dev/sdaX should be replaced with the corresponding device or container file.
  • fstype="auto" can be changed to any type that is present in /usr/bin/mount.type. "auto" should work fine in most cases. Use fstype="crypt" so that the loop device gets closed at logout for volumes needing it.
  • Add mount options, if needed. Note that mount.cifs does not read smb.conf and so all options must be specified. In the example, uid matches the local smb.conf parameter idmap config ... : range = so that pam_mount is not called for a Unix only user. Kerberos is indicated by krb5, SMB3.0 is specified because the other end may not support SMB1 which is the default. Signing is enabled with the i on the end of krb5i. See mount.cifs(8) for more details.

Veracrypt volumes

pam_mount doesn't support Veracrypt volumes natively, but there is a workaround

/etc/security/pam_mount.conf.xml
<volume user="username" fstype="crypt" path="/dev/disk/by-partuuid/partition_uuid" mountpoint="vcrypt"/>
<volume user="username" fstype="auto" path="/dev/mapper/vcrypt" mountpoint="/media/mountpoint"/>

<cryptmount>cryptsetup --veracrypt open --type tcrypt %(VOLUME) %(MNTPT)</cryptmount>
<cryptumount>cryptsetup close %(MNTPT)</cryptumount>

If you also have LUKS volumes, you can use a different fstype for Veracrypt volume instead of crypt with cryptmount/cryptumount, for example ncpfs with ncpmount/ncpumount. Just make sure you don't use NCP filesystem.

F2FS encryption

There is a trick to make pam_mount add a F2FS decryption key to your session keyring. The salt you chose when encrypting directory(es) with f2fscrypt needs to match the one in /etc/security/pam_mount.conf.xml (0x1111 in below example) and passphrase needs to match the user's login password. This example assumes you're not mounting FUSE filesystems with pam_mount. If you do, choose a different <*mount> tag pairs instead of <fusemount> and <fuseumount>, like <ncpmount>/<ncpumount>.

/etc/security/pam_mount.conf.xml
<fusemount>f2fscrypt add_key -S 0x1111</fusemount>
<fuseumount>f2fscrypt new_session</fuseumount>
<volume noroot="1" ssh="0" fstype="fuse" path="/tmp/not-a-real-path-0" mountpoint="/tmp/not-a-real-path-1"/>

<volume> doesn't do anything except trigger the commands in <fusemount> and <fuseumount> After login you can verify that your session keyring has a F2FS decryption key:

$ keyctl show
Session Keyring
 910133222 --alswrv   1000   100  keyring: _ses
 301049775 --alswrv   1000 65534   \_ keyring: _uid.1000
 013481035 --alsw-v   1000   100   \_ logon: f2fs:2e64cf4a5bafcd7

Login manager configuration

In general, you have to edit configuration files in /etc/pam.d so that pam_mount will be called on login. The correct order of entries in each file is important. It is necessary to edit /etc/pam.d/system-login as shown below. If you use a display manager make sure its file includes system-login. Example configuration files follow, with the added lines in bold. The pam_succeed line before pam_mount in session skips pam_mount (success=n means skip the next n lines) if the systemd-user service is running through the PAM stack. This avoids double mount attempts and errors relating to dropped privileges.

/etc/pam.d/system-login
#%PAM-1.0

auth       required   pam_tally2.so        onerr=succeed file=/var/log/tallylog
auth       required   pam_shells.so
auth       requisite  pam_nologin.so
auth       optional   pam_mount.so
auth       include    system-auth

account    required   pam_tally2.so
account    required   pam_access.so
account    required   pam_nologin.so
account    include    system-auth

password   optional   pam_mount.so
password   include    system-auth

session    optional   pam_loginuid.so
session    optional   pam_keyinit.so       force revoke
session [success=1 default=ignore]  pam_succeed_if.so  service = systemd-user quiet
session    optional   pam_mount.so
session    include    system-auth
session    optional   pam_motd.so          motd=/etc/motd
session    optional   pam_mail.so          dir=/var/spool/mail standard quiet
-session   optional   pam_systemd.so
session    required   pam_env.so

SLiM

Tango-go-next.pngThis article or section is a candidate for moving to SLiM.Tango-go-next.png

Notes: We are discouraging the use of SLiM in its article, there's not much of a point in highlighting this here. (Discuss in Talk:Pam mount#)

For SLiM:

/etc/pam.d/slim
auth            requisite       pam_nologin.so
auth            required        pam_env.so
auth            required        pam_unix.so
auth            optional        pam_mount.so
account         required        pam_unix.so
password        required        pam_unix.so
password        optional        pam_mount.so
session         required        pam_limits.so
session         required        pam_unix.so
session         optional        pam_mount.so
session         optional        pam_loginuid.so
session         optional        pam_ck_connector.so