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Re: [Qemu-devel] [PATCH v8 1/2] block/vxhs.c: Add support for a new bloc

From: ashish mittal
Subject: Re: [Qemu-devel] [PATCH v8 1/2] block/vxhs.c: Add support for a new block device type called "vxhs"
Date: Fri, 17 Mar 2017 18:44:56 -0700

On Thu, Mar 16, 2017 at 5:29 PM, ashish mittal <address@hidden> wrote:
> On Mon, Mar 13, 2017 at 2:57 AM, Daniel P. Berrange <address@hidden> wrote:
>> On Tue, Mar 07, 2017 at 05:27:55PM -0800, ashish mittal wrote:
>>> Thanks! There is one more input I need some help with!
>>> VxHS network library opens a fixed number of connection channels to a
>>> given host, and all the vdisks (that connect to the same host) share
>>> these connection channels.
>>> Therefore, we need to open secure channels to a specific target host
>>> only once for the first vdisk that connects to that host. All the
>>> other vdisks that connect to the same target host will share the same
>>> set of secure communication channels.
>>> I hope the above scheme is acceptable?
>>> If yes, then we have a couple of options to implement this:
>>> (1) Accept the TLS credentials per vdisk using the previously
>>> discussed --object tls-creds-x509 mechanism. In this case, if more
>>> than one vdisk have the same host info, then we will use only the
>>> first one's creds to set up the secure connection, and ignore the
>>> others. vdisks that connect to different target hosts will use their
>>> individual tls-creds-x509 to set up the secure channels. This is, of
>>> course, not relevant for qemu-img/qemu-io as they can open only one
>>> vdisk at a time.
>> It looks like option 1 here is the way to go. Just report an error if
>> there are multiple creds provided for the same host and they don't
>> match.
> I have made changes to implement option 1 in the library (branch
> per_channel_ssl).
> Can you please help review it?
> https://github.com/VeritasHyperScale/libqnio/compare/per_channel_ssl
> Here's the changelog:
> (1) Changed code to not use instance UUID for setting up SSL context.
> (2) User is supposed to pass the cacert, client_key and client_cert
>     files to iio_open(). These will be used to set up a per-channel secure SSL
>     connection to the server. All three values are needed to set up a
>     secure connection.
> (3) If the secure channel to a particular host is already open, other
>     block device connections to the same host will have to provide
>     TLS/SSL credentials that match the original one.
> (4) Set default locations for trusted client CA certificates
>      based on user specified cacert file.
> NB - I have given steps to test SSL communication (using the supplied
> test client/server programs) in the commit log. I have not tested
> using qemu binary yet. Will run more tests in the days to come.
> qemu vxhs patch changes should be pretty straightforward, given that
> we have already discussed how to implement passing --object
> tls-creds-x509 per block device.
> Thanks!

Update -
(1) Successfully tested SSL communication using qemu-io and the test server.
(2) Minor changes to per_channel_ssl branch.
(3) Created a pull request.

Please review per convenience. Thanks!

>>> (2) Instead of having a per-vdisk --object tls-creds-x509, have a
>>> single such argument on the command line for vxhs block device code to
>>> consume - if that is possible! One way to achieve this could be the
>>> user/password authentication we discussed earlier, which we could use
>>> to pass the directory where cert/keys are kept.
>>> (3) Use the instance UUID, when available, to lookup the cert files
>>> per instance (i.e. for qemu-kvm), and use the --object tls-creds-x509
>>> mechanism, when instance UUID is NULL (i.e. qemu-io, qemu-img etc).
>>> The cert/key files are anyway protected by file permissions in either
>>> case, so I guess there is no additional security provided by either
>>> method.
>> Regards,
>> Daniel
>> --
>> |: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
>> |: http://libvirt.org              -o-             http://virt-manager.org :|
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