Implement "Move to VM" service

[marmarek]

Reported by joanna on 12 Mar 2013 14:57 UTC
A trivial extension of our qubes.FileCopy, only that the file should be removed (shred) from the source VM after the copy completes. Trivial, but handy...

Migrated-From: https://wiki.qubes-os.org/ticket/725

[marmarek]

Modified by joanna on 18 Nov 2013 13:56 UTC

[marmarek]

Modified by joanna on 18 Nov 2013 13:56 UTC

[marmarek]

Comment by marmarek on 24 Mar 2014 03:00 UTC
The problem with shred is it doesn't support recursive operation (qvm-copy-to-vm supports directories, so qvm-move-to-vm also should).
But thanks to "discard" mount option it shouldn't be necessary - VM kernel tells dom0 that block freed by removed file aren't used anymore and respective part of private.img is reclaimed. Simple test:

[~](user@testvm)$ echo unique-string-eeV8mees1 > test.txt 
[~](user@testvm)$ sync
[~](user@testvm)$ sudo grep 'unique-string-eeV8mees1' /dev/xvdb
Binary file /dev/xvdb matches
[~](user@testvm)$ rm -f test.txt
[~](user@testvm)$ sync
[~](user@testvm)$ sudo grep 'unique-string-eeV8mees1' /dev/xvdb
[~](user@testvm)$ 

Note that dom0 filesystem still could contain removed data, but in case of "Move to VM" service it isn't a problem - the data is already present in another VM private.img.

[marmarek]

Comment by marmarek on 24 Mar 2014 03:00 UTC
The problem with shred is it doesn't support recursive operation (qvm-copy-to-vm supports directories, so qvm-move-to-vm also should).
But thanks to "discard" mount option it shouldn't be necessary - VM kernel tells dom0 that block freed by removed file aren't used anymore and respective part of private.img is reclaimed. Simple test:

[~](user@testvm)$ echo unique-string-eeV8mees1 > test.txt 
[~](user@testvm)$ sync
[~](user@testvm)$ sudo grep 'unique-string-eeV8mees1' /dev/xvdb
Binary file /dev/xvdb matches
[~](user@testvm)$ rm -f test.txt
[~](user@testvm)$ sync
[~](user@testvm)$ sudo grep 'unique-string-eeV8mees1' /dev/xvdb
[~](user@testvm)$ 

Note that dom0 filesystem still could contain removed data, but in case of "Move to VM" service it isn't a problem - the data is already present in another VM private.img.

[marmarek]

Comment by marmarek on 24 Mar 2014 04:20 UTC
http://git.qubes-os.org/?p=marmarek/core-agent-linux.git;a=commit;h=fe6453978903d6a2a4fc1003b635c44733bbb3b3

[marmarek]

Comment by marmarek on 24 Mar 2014 04:20 UTC
http://git.qubes-os.org/?p=marmarek/core-agent-linux.git;a=commit;h=fe6453978903d6a2a4fc1003b635c44733bbb3b3