Hammer history security concern

Bill Hacker wbh at conducive.org
Tue Sep 8 16:06:05 PDT 2009

Simon 'corecode' Schubert wrote:
Hammer history mounts allow access to deleted files.

This can be an issue if you realized that this data should not have been 
available in the first place.

An alternate scenario is that group membership changed, and you don't 
want the new group members to have access to past data.

I think we should address this in some sort in the release.  One way is 
to only allow the owner to access the snapshot, and ignore group/other 
permissions on snapshots.  This is probably very inconvenient, 
especially for root owned system directories.

Another way would be to somehow combine current and past owner/flags, 
but this is probably hard to reason about.

Likewise conventional tape archives - hence an admin issue more than 
architectural - and by no means a situation unique to Hammer [1].


- given the manner in which Hammer operates, 'obliterate' style delete with 
multiple randomized overwrite at the relevant physical media storage locations 
wouldn't seem to get the job done, and/or could be highly impractical to apply 
over multi-generation history - most especially where networked / remote / 
removable media is involved - and is not under the thumb of [one of] the file 

In this respect, Hammer is a bit like the proverbial 'cautious' government clerk 
told to destroy certain files:

Naturally, he made a copy of each before burning, just to cover his a** ....

Sounds like a utility [ set] is needed?

ELSE - as always - end-lusers warned to privately encrypt their valuables as 
they go...


Bill Hacker

[1]  *Any* storage media, especially incremental or 'layered' ones - sedimentary 
rock for example - is a potential source of recovery of historical information 
that the original owner might have wished kept private.

Think of the embarassment of the dinosaur outed 135 million years on ....as 
having been stupid enough to have mis-stepped and suffocated in a mudhole....


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