Thread: Patch for 's' file attribute in ext4 filesystem?

the manpage 'chattr' command includes following:

when file 's' attribute set deleted, blocks zeroed , written disk. note: please make sure read bugs , limitations section @ end of document.

... seems pretty slick, in aforementioned "bugs , limitations" section, says this:

the 'c', 's', , 'u' attributes not honored ext2 , ext3 filesystems implemented in current mainline linux kernels. these attributes may implemented in future versions of ext2 , ext3 filesystems.

this attribute isn't supported in ext4 either (see below). seems incredibly convenient way securely overwrite files - know of patch allow this? little light google-ing didn't turn up...

attribute not working: (and shred working expected)

code:

root@linux:/# mount /dev/sdb1 /mnt root@linux:/# echo "jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj" > /mnt/thing.txt root@linux:/# umount /mnt root@linux:/# hexdump -c /dev/sdb1 | grep "jjjjjjjjjjjjjjjj" 00840c00  4a 4a 4a 4a 4a 4a 4a 4a  4a 4a 4a 4a 4a 4a 4a 4a  |jjjjjjjjjjjjjjjj| root@linux:/# mount /dev/sdb1 /mnt root@linux:/# rm -rf /mnt/thing.txt root@linux:/# umount /mnt root@linux:/# hexdump -c /dev/sdb1 | grep "jjjjjjjjjjjjjjjj" 00840c00  4a 4a 4a 4a 4a 4a 4a 4a  4a 4a 4a 4a 4a 4a 4a 4a  |jjjjjjjjjjjjjjjj| root@linux:/# mount /dev/sdb1 /mnt root@linux:/# echo "kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk" > /mnt/thing2.txt root@linux:/# chattr +s /mnt/thing2.txt root@linux:/# umount /mnt root@linux:/# hexdump -c /dev/sdb1 | grep "kkkkkkkkkkkkkkkk" 00840c00  4b 4b 4b 4b 4b 4b 4b 4b  4b 4b 4b 4b 4b 4b 4b 4b  |kkkkkkkkkkkkkkkk| root@linux:/# mount /dev/sdb1 /mnt root@linux:/# lsattr /mnt s----------------e- /mnt/thing2.txt root@linux:/# rm -rf /mnt/thing2.txt root@linux:/# umount /mnt root@linux:/# hexdump -c /dev/sdb1 | grep "kkkkkkkkkkkkkkkk" 00840c00  4b 4b 4b 4b 4b 4b 4b 4b  4b 4b 4b 4b 4b 4b 4b 4b  |kkkkkkkkkkkkkkkk| root@linux:/# mount /dev/sdb1 /mnt root@linux:/# shred /mnt/thing2.txt root@linux:/# umount /mnt root@linux:/# hexdump -c /dev/sdb1 | grep "kkkkkkkkkkkkkkkk" root@linux:/# exit

Forum The Ubuntu Forum Community Ubuntu Specialised Support Security [all variants] Patch for 's' file attribute in ext4 filesystem?

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