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SubjectRe: Can't hardlink in different dirs. (BUG#826)

[Pavel Machek <pavel@suse.cz>]
> > > I still think that adding feature to truncate file before deletion
> > > into rm would make you happy, Andrea. That handles both open() and
> > > link() cases nicely.
[me]
> > I agree. Something like this? (Lightly tested.)
[Pavel Machek]
> YES! That should stop andrea complaining :-). [Anyway, problem with
> inode quota remains.] Please submit this patch to
> bug-gnu-utils@prep.ai.mit.edu and make sure it gets included.

If I get time I will. The patch still needs not only documentation but
also autoconf portability crud before GNU maintainers would want it.

> (It would be nice to document that -T is good idea when removing suid
> executables and when working on so hostile remote system that they
> try to kill your quota.)

And, in general, any time you want the file *gone* more than you want
it *unlinked*. If you don't have write access to the directory, for
example, -T will at least truncate the file.

I thought about a companion flag to zero the file contents, for a
similar effect except that the file will no longer be accessible even
reading the raw block device. Not a very strong security measure:

* Doing this probably won't remove *all* traces of your file; think FS
journal, location before the last defrag, etc.
* There are a lot of ways to delete files that don't go through rm, and
some are easy to overlook. One obvious example: Emacs unlinks foo~
(without zeroing) before renaming foo to foo~ and writing a new foo
* The physical disk will still have traces of the old data on it so the
NSA can probably still read it

With that in mind, does anyone else think this would be worthwhile?

Peter

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