Thinking about a universal UUID mount

New features which should be implemented in Porteus; suggestions are welcome. All questions or problems with testing releases (alpha, beta, or rc) should go in their relevant thread here, rather than the Bug Reports section.
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sams
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Thinking about a universal UUID mount

Post#1 by sams » 24 May 2012, 03:45

I'm looking at the implementation of magic folders with LUKS container introduced in rc2. What I want is to mount a container on (UUID identified media) in folders.cfg

But the device is mounted in different locations on different computers, it could be /mnt/sdb1, /mnt/sdc1. If I run porteus as copy2ram, the boot media isn't automouted, but KDE will want to mount it in a predictable place, /media/<UUID> (obviously this doesn't help here since the container won't be mounted)

I have toyed with a script expansion in folders.cfg, but that is a severely damaged approach. I feel I want the mount equivalent of /dev/disk/by-uuid (I'm thinking of something on the /proc filesystem). Maybe I'm missing something that's already here?

thoughts?

Posted after 51 minute 23 seconds:
Partially answering my own question, you can put a wildcard in folders.cfg and bash will expand it out. In my case bash expands it to the single mounted match (yuck?), and everything works. ie:

/mnt/*/porteus/container.dat /tmp/alreadyExistingMountPoint

Would be better if there were a reliable way to specify, but this is going to allow some cool stuff for now. Keep the better ideas coming please!

cheers!

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fanthom
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Re: Thinking about a universal UUID mount

Post#2 by fanthom » 24 May 2012, 07:50

hi sams,
If I run porteus as copy2ram, the boot media isn't automouted
please use 'noeject' cheatcode together with copy2ram so nothing will be unmounted during boot.

@Ahau
please update copy2ram cheat description with note about 'noeject' as users may be not aware of this.
What I want is to mount a container on (UUID identified media) in folders.cfg
good idea and this could be default for magic folders. i have implemented UUID->sdXY translation function in rc.S:

Code: Select all

# Source:
src=`sed -n "$x"p /etc/magic_folders/folders.cfg | cut -d " " -f1`
# UUID to sdXY translation:
uuid=`echo $src | cut -d/ -f3`
dev=`blkid -U $uuid | cut -d/ -f3`
src=`echo $src | sed s/$uuid/$dev/g`
# Destination:
dest=`sed -n "$x"p /etc/magic_folders/folders.cfg | cut -d " " -f2`
which translate for example:

Code: Select all

/mnt/120a9458-07c9-4e50-a9ec-894ad115e101/magic /home/guest
to

Code: Select all

/mnt/sda4/magic /home/guest
and all works ok on my end :)

@brokenman
please include similar function in 'magic folders' tool which does backwards translation: sdXY->UUID.
in short words: we want to have /mnt/UUID in /etc/magic_folders/folders.cfg instead of /mnt/sdXY

Cheers
Please add [Solved] to your thread title if the solution was found.

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brokenman
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Re: Thinking about a universal UUID mount

Post#3 by brokenman » 24 May 2012, 13:20

Done. Uploaded new gtkmagic-folder to the box.

Reminder for rc.S to accommodate multiple lines in /etc/magic_folders/folders.cfg
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Wear your underpants on the outside and put on a cape.

sams
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Re: Thinking about a universal UUID mount

Post#4 by sams » 24 May 2012, 21:42

Fanthom, your idea looks good, right on.

(I'm deleting a mistaken bug report here regarding apparent size of a LUKS container...)

Posted after 2 hours 40 minutes 39 seconds:
Here's a shell dump of how I moved a user's directory from /home to an encrypted LUKS container:

Code: Select all

# NOTE: my /tmp is a big place off the union fs, make sure you pick a suitable working directory
$ mkdir -p /tmp/xxx

$ time ( nice dd if=/dev/urandom of=/tmp/xxx/container.dat bs=1M count=644 ; sync )
675282944 bytes (675 MB) copied, 74.0459 s, 9.1 MB/s
real    1m14.081s

$ ls -la /usr/local/bin/makeloop
-rwxr-xr-x 1 root root 201 May 23 09:08 /usr/local/bin/makeloop

$ makeloop 
20
$ makeloop 
20

$ mknod /dev/loop20 b 7 20

$ losetup /dev/loop20 /tmp/xxx/container.dat 

$ losetup -a | grep container
/dev/loop20: [0011]:18686 (/tmp/xxx/container.dat)

$ cryptsetup --verbose --verify-passphrase luksFormat /dev/loop20
Enter LUKS passphrase: 
Verify passphrase: 
Command successful.

$ cryptsetup luksOpen /dev/loop20 crybaby
Enter passphrase for /dev/loop20: 

$ mkfs.ext2 -m 1 -O dir_index,filetype,sparse_super /dev/mapper/crybaby

$ mkdir /tmp/containerMountPoint

$ chown mySecureName:myGroup /tmp/containerMountPoint

$ chmod 750 /tmp/containerMountPoint 

$ mount -o noatime /dev/mapper/crybaby /tmp/containerMountPoint

$ mount
/dev/sdc1 on /media/1uuid2uuid3 type ext2 (rw,nosuid,nodev,uhelper=udisks)
/dev/mapper/crybaby on /tmp/containerMountPoint type ext2 (rw,noatime)

root@porteus:/tmp/containerMountPoint  
$ ls
lost+found

root@porteus:/tmp/containerMountPoint  
$ cd ~mySecureName

root@porteus:/home/mySecureName  
$ cd ..

root@porteus:/home  
$ tar cf - mySecureName | ( cd /tmp/containerMountPoint ; tar xf - ) ; sync

root@porteus:/home  
$ cd /tmp/containerMountPoint

root@porteus:/tmp/containerMountPoint  
$ la
total 24
drwxr-xr-x  4 root           root     4096 May 23 11:26 .
drwxrwxrwt 11 root           root      240 May 23 11:18 ..
drwx------  2 root           root    16384 May 23 10:13 lost+found
drwxr-x--- 13 mySecureName   myGroup  4096 Apr  2 19:27 mySecureName

root@porteus:/tmp/containerMountPoint  
$ cd 

root@porteus:~  
$ umount /tmp/containerMountPoint

root@porteus:~  
$ cryptsetup luksClose crybaby

root@porteus:~  
$ losetup -d /dev/loop20

root@porteus:~  
$ rm /dev/loop20

root@porteus:~  
$ cp /tmp/xxx/container.dat /media/1uuid2uuid3/porteus/ ; sync
I hope this helps someone. Note that I don't recommend recommend mounting on or big data dumps to /tmp, but my mounts are different than the default.

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