Messages in this thread |  | | Date | Wed, 15 May 1996 18:45:15 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: Still no secure rm in pre2.0.4 |
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From: Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl> Date: Wed, 15 May 1996 21:36:28 +0200 (MET DST)
I just noticed that pre2.0.4 still doesn't support the secure deletion feature of the ext2 filesystem (which is disabled due to bad interaction with shared mappings). Are there any plans to put it back in the kernel before the 2.0 release? The Linus' comments in fs/ext2/truncate.c have some suggestions how to implement this.
I doubt it, since that would be a pretty significant change, and I don't think any of the ext2 developers have time just about now.
Now that we have the kernel random number generator, it could be used here too, instead of the simple predictable one. If the random device is made a config option and it is disabled, we could simply fill the deleted disk blocks with zeros - if you are paranoid about such things, you probably have the random device enabled :-).
You don't need secure randomness for the purpose of overwriting files; if you want to do more than a simple zeroization of the files, you need to use very carefully constructed sets of patterns to really erase the magnetic domains on the hard disk. These patterns are hardware dependent, but there are some 15-32 pass patterns (!) which should work for most hardware. It's really slow, though...
A program to clear all unused space on a filesystem would be nice...
Well, all of the tools you need to write such a program are in the ext2 library. Someone just has to do it! :-)
- Ted
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