Hello,
I'm trying to migrate my setup from systemd.mount[1] to autofs/automount
userspace daemon. I have a local disk encrypted with LUKS and a samba share
with a keyfile for this disk. The goal is to automatically mount and decrypt
this disk when connected to my home network.
Below is my configuration. I'm mounting the encrypted disk with
/sbin/mount.crypt helper from pam_mount[2].
# Master map file
/- /home/mliszcz/var/autofs/router.map --timeout=60
/- /home/mliszcz/var/autofs/disk.map --timeout=60
# router.map
/mnt/router -fstype=cifs,ro,guest,vers=2.0 ://172.18.0.5/USB_DISK
# disk map
/mnt/data -fstype=crypt,keyfile=/mnt/router/encryption.keyfile,fsk_cipher=none
:/dev/loop0p1
While /mnt/data is being mounted I'm seeing below logs:
attempting to mount entry /mnt/data
mount(generic): failed to mount /dev/loop0p1 (type crypt) on /mnt/data
failed to mount /mnt/data
I debugged this a bit. The mount helper for /mnt/data tries to access
/mnt/router/encryption.keyfile, but it does not trigger automounting of
/mnt/router. It seems that this is by design - there is already some code
in autofs for handling dependent mounts (open(2) call with changed uid/gid
to trigger mounting of the dependency before executing the actual mount
command). But it only works if the two mounts share the mountpoint prefix.
I verified this by changing the daemon/spawn.c file as follows:
@@ -454,6 +454,9 @@ static int do_spawn(unsigned logopt, unsigned int wait,
* let the VFS handle returns to each individual
* waiter.
*/
+ if(strcmp(argv[loc], "/dev/loop0p1") == 0)
+ fd = open("/mnt/router", O_DIRECTORY);
+ else
fd = open(argv[loc], O_DIRECTORY);
if (fd != -1)
close(fd);
Now I'm wondering if it would be possible to add a generic mechanism for
declaring dependencies in autofs maps to make this work. If this could be
accepted I can even work on a patch, provided that I get some pointers.
Kind regards,
Michal
[1]: https://www.freedesktop.org/software/systemd/man/systemd.mount.html
[2]: https://inai.de/projects/pam_mount/
