On 10/07/2011 12:54 PM, Eric Sandeen wrote:
On 10/7/11 1:35 PM, Darrick J. Wong wrote:
On Fri, Oct 07, 2011 at 12:11:05AM -0700, Allison Henderson wrote:
This patch modifies both ext4 and jbd2 such that the journal
blocks which may contain file data, are securely deleted
after the files data blocks are deleted.
Because old journal blocks may contain file data, we need
a way to find those blocks again when it comes time to secure
delete the file. This patch adds a new list to the journal
structure to keep track of which vfs blocks the journal blocks
contain.
After a truncate or a punch hole operation has completed, a
new function ext4_secure_delete_jblks is called that flushes
the journal, and then searches the list for any journal blocks
that were used to journal the blocks that were just removed.
The found journal blocks are then secure deleted.
And what about directory data? Those would appear to remain in the
journal at least... And xattrs?
#!/bin/bash
rm -f testsecdel
truncate --size 256m testsecdel
mkfs.ext4 -F testsecdel&>/dev/null
mount -o loop testsecdel mnt/
echo securedata> mnt/securefilename
setfattr -n user.securexattrname -v securexattrvalue mnt/securefilename
LONGATTR=`for I in 1 2 3 4 5 6 7 8 9 0; do echo -n veryveryveryveryveryveryverylongsecurexattrvalue; done`
setfattr -n user.longsecurexattrname -v $LONGATTR mnt/securefilename
sync
rm -f mnt/securefilename
umount mnt
strings testsecdel
yields:
/mnt/test2/mnt
lost+found
securexattrname
Ylongsecurexattrname
mselinux
veryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvalueveryveryveryveryveryveryverylongsecurexattrvaluesecurexattrvalueunconfined_u:object_r:file_t:s0
lost+found
securefilename
/mnt/test2/mnt
(this was with ext4.ko hacked to always enable secure delete)
-Eric
alrighty, I will need to figure out how to get those out of there too.
I will add this to my test case. Thx!
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