secure file deletion/SECRM support for JFFS2 and UBIFS

[Chris Packham]

Hi,

We have a customer request for "secure file deletion" for our embedded 
devices (kernel version 4.4.6). The first device is running JFFS2 on 
parallel NOR flash but we expect to see the same requirement pop up on 
our newer devices running UBIFS on top of NAND.

I found a couple of old threads related to UBIFS but they all appear to 
have fallen silent. Nothing really for JFFS2.

For our application we're not really concerned about defeating 
determined attackers who have access to the device and hardware that can 
do detailed analysis on the transistors that make up the chip. But we 
are trying to protect against casual attackers (or recipients of 
re-furbished hardware) who can run 'dd'.

So I think for us it'd be enough to implement chattr +s and have the 
file's data over written with a fixed value (e.g 0 for NOR flash) when 
it's blocks are added to the garbage collection list.

Is that something people on this list would be interested in? I realize 
JFFS2 is kind of in a twilight phase but we're really not able to 
migrate some customers away from it.

Thanks,
Chris