Messages in this thread | | | Date | Tue, 17 Feb 2004 13:00:21 +0100 | From | Pavel Machek <> | Subject | Re: PATCH - ext2fs privacy (i.e. secure deletion) patch |
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Hi!
> At which point, in the presence of the theoretical mount option, it becomes > easy to reduce the work load to "a long list of block operations" by making > the shredding unconditional. > > That is, instead of thinking of it as shredding a file, the (arbitrarily > named) "zerofree" mount option is passed and every block that is released > from active file system use is zeroed. E.g. file blocks, directory blocks, > attribute blocks, everything. That just takes (at the worst) a list/queue > and a block-write of a block-sized page containing all zeros (or, better > yet, an optionally-user-supplied squeegee pattern.) So take/make the > free_block() routine and make it submit a "dirty block" to the I/O buffering > system. If the block is immediately re-used then even the write expense > amortizes to near zero for clearing that block (or unwritten > fragment).
I see a small problem with that: some "interesting" data, such as file names, are smaller than a block. With this kind of implementation, you'd never wipe those. Pavel [un-erase no longer works even on ext3, that's nothing new]
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