[Lustre-devel] Security issues
Peter.Braam at Sun.COM
Fri Aug 8 20:47:15 PDT 2008
On 8/8/08 11:44 AM, "Eric Mei" <Eric.Mei at Sun.COM> wrote:
> Peter Braam wrote:
>> On 8/8/08 11:03 AM, "Eric Barton" <eeb at sun.com> wrote:
>> 1. Securing bulk data.
>> It seems to me that it _is_ appropriate to use the GSSAPI to secure the
>> transfer of bulk data between client and server since it's
>> effectively just
>> another message. I can see (at least naively) that it would be good to
>> avoid double encryption in the case where file contents are actually
>> encrypted on disk.
>> You are not telling me that we are going through a lot of re-design,
>> that we are encrypting data and that then we are not storing it
>> encrypted on disk? Come on, adding an EA with a key to decrypt is not
>> so hard and one gets lots of value from it.
>> But even in this case, don't we still have to sign the
>> (encrypted) bulk so that the receiver can be sure it arrived intact?
>> Well, yes, but as I indicated you can sign the hash that is stored on
>> (ZFS) disk for this. That avoids generating the hash twice. So I am
>> really not convinced yet.
> Peter, are you saying that except using NASD-style protocol, we don't
> need to encrypt/sign bulk data at all?
You do need to sign it and encrypt it - for multiple purposes, to secure the
wire transaction and for storage on the server.
>> The issue is not the message mechanism, but is what identity to use for
>> GSS to authenticate and how to manage and revoke that etc.
> Here we only want to protect on-wire data, the gss authentication is
> only for the "node", not particular user, as you pointed out previously.
Yes, and how is this managed? This is not so trivial.
>> 2. Securing Capabilities.
>> If we want to be sure that a Capability given to client A cannot be
>> snooped and used by client B we either (a) have to make the Capability
>> secret (i.e. never passed in cleartext) or (b) have to make the
>> identify which client it is valid for.
>> It seems to me that (b) is preferrable since it ensures that a malicious
>> client cannot leak Capabilities to a 3rd party. The downside is
>> that this
>> multiplies the number of unique Capabilities by the number of clients,
>> potentially increasing CPU load when 1000s of clients all open the same
>> shared file and each require unique Capabilities to access the
>> stripe objects.
>> Do we have a feel for how bad this could be?
>> Yes, very bad, and it is absolutely necessary to have an option that
>> avoids this (also 1000s is out of date it could be 100x worse). That
>> option could be to simply not have security on the compute cluster if
>> customers agree with this.
>> We also need to discuss your proposals with a review committee from LLNL
>> and Sandia, as we did during the PF discussions.
> We're trying to figure out a way to generate only one capability for
> each MD object, but somehow mingled with per-export data to generate
> client-unique capability, but till now we haven't found a good solution.
> The other thought is using some kind of light-weight, but still
> reasonably secure hash algorithm. By changing the KEY frequently enough
> (e.g. every 2 hours) we can still be secure. But we'v no idea what hash
> algorithm could fit our needs.
More information about the lustre-devel