[libvirt] [PATCH v3] Add support for Veritas HyperScale (VxHS) block device protocol

ashish mittal ashmit602 at gmail.com
Mon Apr 17 17:59:38 UTC 2017 

Thanks!

On Mon, Apr 17, 2017 at 9:19 AM, John Ferlan <jferlan at redhat.com> wrote:
>
>
> On 04/14/2017 07:26 PM, ashish mittal wrote:
>> Looking at the code, I suspect significant changes will be needed to
>> support passing TLS arguments for disk devices. Here's what I have
>> right now -
>>
>
> Sure you're going to need to add some code, but there should be enough
> infrastructure there now that is reusable. I made a number of changes
> during the 7.4 release to generate "generic enough" API's that both
> chardev TLS and migrate TLS can use them. Adding a disk TLS option
> should be easy. It was something I had in the back of my mind while
> altering the APIs.
>
> I think if you use cscope and then search on 'haveTLS' you'll get the
> necessary pieces. The 'migTLSAlias' may also give you some ideas.
>
>
>> int
>> qemuProcessPrepareDomain(virConnectPtr conn,
>>                          virQEMUDriverPtr driver,
>>                          virDomainObjPtr vm,
>>                          unsigned int flags)
>> {
>>   ...
>>     VIR_DEBUG("Prepare chardev source backends for TLS");
>>     qemuDomainPrepareChardevSource(vm->def, driver);   <== This is
>> where char devices prepares their TLS...
>>
>>  <=== This is where we would expect a generic "Prepare disk source
>> backends for TLS" for all the disk devices
>>  <=== -- OR -- I can do something specific for VxHS here
>
> I'm not yet sure you need this step for disk TLS. For chardev, it's
> "enforcing" that if the qemu.conf chardevTLS is set, then as long as the
> domain chardev source object using TCP doesn't have a "tls='no'" or
> "tls='yes'" attribute, that TLS gets set for the object. I recall not
> agreeing with exactly how this was implemented for chardevTLS, but I do
> understand why.
>
> You need to decide "how" you see this being utilized. For example, if an
> XML object had "tls='yes'", but a global qemu.conf variable was set to
> 0, then would you expect TLS to work? Conversely, if the global
> qemu.conf was set, then would you expect any disk that could use TLS
> would be forced to try unless the XML configuration explicitly set
> disable. In the long run adding TLS options to a disk startup would
> still be on a protocol by protocol basis.
>
> If you did add this, then it would be a "generic"
>
>     qemuDomainPrepareDiskSource()
>
> where qemuDomainPrepareDiskSource would traverse the vm->def->ndisks
> (like qemuDomainPrepareChardevSourceTLS does for each chardev source)
> looking for disks with a <source> defined and checking the value of the
> haveTLS in order to decide whether to set/clear the flag based on the
> global setting. You wouldn't need the tlsFromConfig - that's there
> because of a cross version migration configuration issue that shouldn't
> apply for your purposes.
>
>
>>
>>     VIR_DEBUG("Add secrets to disks, hostdevs, and chardevs");
>>     if (qemuDomainSecretPrepare(conn, driver, vm) < 0)     <== perhaps
>> changes will be needed here also, but we plan to pass the cert
>> directory, endpoint and ID as plain-text..still would need a place to
>> save these new values..
>
> Yes, but more specifically in qemuDomainSecretDiskPrepare in order to
> lookup of the secret if it exists (logic should be similar to
> qemuDomainSecretChardevPrepare, but specific to disk needs)
>
>>
>>         goto cleanup;
>>   ...
>> }
>>
>> I'm thinking, I would also need to extend one of the following
>> structures to save the TLS related info.
>>
>> struct _virDomainDiskDef {
>> }
>>     --- OR ---
>> struct _qemuDomainDiskPrivate {
>
> This one^^
>
>> }
>>
>> Given that adding TLS support for VxHS (and disk devices in general)
>> will not be trivial, I want to check if this can be taken up at a
>> later time?
>
> No, it'd be preferable to have a complete solution.  That solution
> should be a separately compilable/checkable multi-patch series where
> each patch makes forward progress towards your goal.
>
> Consider first getting the non-TLS environment working. You have some of
> it working with the existing patches - it's updating the generation of
> the command line that would seem to need the adjustment. I think I've
> already pointed out a series or two that should help you in that endeavor.
>
> Then for TLS, again it's a multi-step process
>
>  1. Modify the qemu_conf.c and qemu.conf files to search for new
> disk_vxhs_tls_x509* definitions since I assume that either you'll use
> the existing qemu definitions or you (more likely) want to have some
> directory that would have a VxHS specific environment. I suggest a
> "disk_vxhs_" - just to make it more specific. If some day RBD, iSCSI,
> etc. support TLS, then they'd conceivably have their own "disk_rbd" or
> "disk_icsci" options since each would have their own server to
> authenticate using TLS creds.
>
>  2. Add a "tls='yes'" (similar to how chardev did things) for the disk
> <source> entry. This allows the mechanism to allow/deny on a disk by
> disk basis whether TLS credentials would be needed.
>
>  3. Set up the qemu infrastructure to accept/recognize some sort of tls
> option which would allow the tls-creds-x509 to be added to the command
> line. Start with adding a new entry to _qemuDomainDiskPrivate such as
> "qemuDomainSecretInfoPtr tlsinfo;". Then qemuDomainSecretDiskPrepare is
> where you'll need to adjust to add a possible secret that's used to
> access the TLS credentials (see qemuDomainSecretChardevPrepare for the
> example). Then when the disk is added on the command line you'll have
> the necessary pieces for the two calls qemuBuildObjectSecretCommandLine
> and qemuBuildTLSx509CommandLine used to generate the optional secret and
> required tls-creds-x509 object. The alias you use for that object is
> what then gets added to the command line generation for the VxHS disk.
>
>  4. You'll need to follow a similar process for hotplug support, except
> there's slightly different calls in order to hot plug the secret and tls
> objects.
>
> Although everything needs to go in for the same libvirt release, it's OK
> to get things working and reviewed as they're ready. Be cognizant that
> libvirt releases are monthly - so dropping a large series near the end
> of the month probably would result in review/push falling into the
> subsequent month's release. Also attempting to do everything in a
> smaller subset of patches will result in a request to split things up
> into manageable chunks.
>
> John
>
>>
>> Thanks,
>> Ashish
>>
>>
>> On Tue, Apr 11, 2017 at 4:26 PM, ashish mittal <ashmit602 at gmail.com> wrote:
>>> Thanks for the information. I'll work with this and get back if I get
>>> stuck somewhere.
>>>
>>> My immediate objective is to figure out how to pass the TLS x509
>>> certificate information to the vxhs block device on the qemu command
>>> line. I guess I expected some other block device (i.e. NBD) to call
>>> the qemuBuildTLSx509CommandLine(), but got confused when I did not
>>> find that...
>>>
>>> On Tue, Apr 11, 2017 at 3:47 PM, John Ferlan <jferlan at redhat.com> wrote:
>>>>
>>>>
>>>> On 04/10/2017 07:32 PM, ashish mittal wrote:
>>>>> Hi,
>>>>>
>>>>> I'm trying to figure out what changes are needed in the libvirt vxhs
>>>>> patch to support passing TLS X509 arguments to qemu, similar to the
>>>>> following -
>>>>>
>>>>> Sample QEMU command line passing TLS credentials to the VxHS block
>>>>> device (run in secure mode):
>>>>> ./qemu-io --object
>>>>> tls-creds-x509,id=tls0,dir=/etc/pki/qemu/vxhs,endpoint=client -c 'read
>>>>> -v 66000 2.5k' 'json:{"server.host": "127.0.0.1", "server.port": "9999",
>>>>> "vdisk-id": "/test.raw", "driver": "vxhs", "tls-creds":"tls0"}'
>>>>>
>>>>> I was hoping to find some NBD code related to this, but not able to
>>>>> locate it. Any pointers will be appreciated.
>>>>
>>>> Well you have a couple of things to deal with... There's the creation of
>>>> the TLS object and there's altering the parameters used for the qemu
>>>> command based on your needs/model.
>>>>
>>>> First off you'll need to figure out where/how you're going to define
>>>> where the TLS creds exist. For that, I suspect you'll have code similar
>>>> to how chardevTLS support was added.  Essentially some way to either use
>>>> an existing TLS environment or a way to allow someone to define a vxhs
>>>> specific environment (hint, see src/qemu/qemu_conf.c, src/qemu/qemu.conf
>>>> - I've made changes recently there too).
>>>>
>>>> For the TLS object creation on the command line, see
>>>> qemuBuildTLSx509CommandLine to see how the code builds the
>>>> "tls-creds-x509,id=tls0,dir=/etc/pki/qemu/vxhs,endpoint=client" portion
>>>> of your command line.
>>>>
>>>> I forget if hot plug was in your plan, but see qemuDomainGetTLSObjects,
>>>> qemuDomainAddTLSObjects, and qemuDomainDelTLSObjects for that.
>>>>
>>>> The rest of the command line is going to be a bit tricky since using the
>>>> "newer" driver syntax for libvirt is "sparse". Traditionally libvirt has
>>>> used "-drive file=[$uri:]$path,format=$driver,..."  (use grep "\-drive
>>>> file" tests/*/*.args from a libvirt git directory - you can grep that
>>>> output for gluster or rbd to see the uri format).
>>>>
>>>> IIUC the qemu changes correctly though, you cannot use that "file="
>>>> syntax, instead you'll need to format the command line similar to how
>>>> things were done for gluster to add multiple host support where the
>>>> syntax is "-drive 'file.driver=gluster,file.volume=..." (use grep
>>>> "\-drive file.driver" tests/*/*.args to see how this is done for gluster).
>>>>
>>>> That code/support was added in a series starting at commit id '22ad4a7c'
>>>> and working your way forward through about 18 patches. Using a visual
>>>> tool like gitk helps a lot...
>>>>
>>>> I think what will be easiest is to start at that commit and look "up"
>>>> for gluster specific changes.  Be careful not to fully cut-n-paste
>>>> because there have been patches since that time to fix some issues with
>>>> the initial implementation. I point it out only as a way for you to see
>>>> which modules and where "similar" code exists.
>>>>
>>>> You'll also note there is an nbd patch in that series of patches - not
>>>> sure how much that helps, but it perhaps gives you some amount of
>>>> guidelines. Although I don't believe nbd was added to the command line -
>>>> it was just a way of syntax generation/testing.
>>>>
>>>>
>>>> John
>>>>
>>>>>
>>>>> Thanks,
>>>>> Ashish
>>>>>
>>>>> On Wed, Feb 1, 2017 at 8:36 AM, John Ferlan <jferlan at redhat.com> wrote:
>>>>>> [...]
>>>>>> Pressed send too soon, sigh.
>>>>>>
>>>>>>
>>>>>>>>>
>>>>>>>>> #1. Based on Peter's v2 comments, we don't want to support the
>>>>>>>>> older/legacy syntax for VxHS, so it's something that should be removed -
>>>>>>>>> although we should check for it being present and fail if found.
>>>>>>>>>
>>>>>>>>
>>>>>>>> I am testing with changed code to return error if legacy syntax is
>>>>>>>> found for VxHS. Also added a test case to check for failure on legacy
>>>>>>>> syntax and it seems to pass (test #41 below).
>>>>>>>>
>>>>>>>> Then I added a pass test case to check conversion from new native
>>>>>>>> syntax to XML (test #40 below). That test fails with error
>>>>>>>> 'qemuParseCommandLineDisk:901 : internal error: missing file parameter
>>>>>>>> in drive 'file.driver=vxhs,file.vdisk-id=eb90327c-8302-4725-9e1b...'
>>>>>>>
>>>>>>> The qemu_parse_command.c changes while nice to have weren't even updated
>>>>>>> when multiple gluster servers were added (e.g. commit id '' or '7b7da9e28')
>>>>>>> Check the changes to add the new s
>>>>>>>
>>>>>>> IOW: This code knows how to parse something like:
>>>>>>>
>>>>>>> -drive
>>>>>>> 'file=gluster+unix:///Volume2/Image?socket=/path/to/sock,format=raw,if=none,id=drive-virtio-disk1'
>>>>>>>
>>>>>>> but it's clueless for:
>>>>>>>
>>>>>>> -drive file.driver=gluster,file.volume=Volume3,file.path=/Image.qcow2,\
>>>>>>> file.server.0.type=tcp,file.server.0.host=example.org,file.server.0.port=6000,\
>>>>>>> file.server.1.type=tcp,file.server.1.host=example.org,file.server.1.port=24007,\
>>>>>>> file.server.2.type=unix,file.server.2.socket=/path/to/sock,format=qcow2,\
>>>>>>> if=none,id=drive-virtio-disk2 \
>>>>>>> -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk2,\
>>>>>>> id=virtio-disk2
>>>>>>>
>>>>>>> See
>>>>>>>>
>>>>>>>> Looks like none of the existing tests in qemuargv2xmltest test for the
>>>>>>>> parsing of new syntax, and qemuParseCommandLineDisk() expects to find
>>>>>>>> 'file=' for a drive or it errors out. If this is true, will it be able
>>>>>>>> to parse the new syntax? Some help here please!
>>>>>>
>>>>>> So I wouldn't expect the VxHS code to be able to do that unless you
>>>>>> wanted to be adventurous.  The good news is that this code is primarily
>>>>>> for developers that need to take a qemu command line to generate the
>>>>>> libvirt syntax. It has not really been kept up to date with all the most
>>>>>> recent command line changes. I started to try over a year ago, but got
>>>>>> very side tracked.
>>>>>>
>>>>>>>>
>>>>>>>> Output from the newly added test cases (40 should pass and 41 checks
>>>>>>>> for error) :
>>>>>>>>
>>>>>>>> 40) QEMU ARGV-2-XML disk-drive-network-vxhs
>>>>>>>> ... Got unexpected warning from qemuParseCommandLineString:
>>>>>>>> 2017-01-28 00:57:30.814+0000: 10391: info : libvirt version: 3.0.0
>>>>>>>> 2017-01-28 00:57:30.814+0000: 10391: info : hostname: localhost.localdomain
>>>>>>>> 2017-01-28 00:57:30.814+0000: 10391: error :
>>>>>>>> qemuParseCommandLineDisk:901 : internal error: missing file parameter
>>>>>>>> in drive 'file.driver=vxhs,file.vdisk-id=eb90327c-8302-4725-9e1b-4e85ed4dc251,file.server.host=192.168.0.1,file.server.port=9999,format=raw,if=none,id=drive-virtio-disk0,cache=none'
>>>>>>>> libvirt: QEMU Driver error : internal error: missing file parameter in
>>>>>>>> drive 'file.driver=vxhs,file.vdisk-id=eb90327c-8302-4725-9e1b-4e85ed4dc251,file.server.host=192.168.0.1,file.server.port=9999,format=raw,if=none,id=drive-virtio-disk0,cache=none'
>>>>>>>> FAILED
>>>>>>>>
>>>>>>>> 41) QEMU ARGV-2-XML disk-drive-network-vxhs-fail
>>>>>>>> ... Got expected error from qemuParseCommandLineString:
>>>>>>>> libvirt: QEMU Driver error : internal error: VxHS protocol does not
>>>>>>>> support URI syntax
>>>>>>>> 'vxhs://192.168.0.1:9999/eb90327c-8302-4725-9e1b-4e85ed4dc251'
>>>>>>>> OK
>>>>>>>> 42) QEMU ARGV-2-XML disk-usb                                          ... OK
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> #2. Is the desire to ever support more than 1 host? If not, then is the
>>>>>>>>> "server" syntax you've borrowed from the Gluster code necessary? Could
>>>>>>>>> you just go with the single "host" like NBD and SSH. As it relates to
>>>>>>>>> the qemu command line - I'm not quite as clear. From the example I see
>>>>>>>>> in commit id '7b7da9e28', the gluster syntax would have:
>>>>>>>>>
>>>>>>>>
>>>>>>>> Present understanding is to have only one host. You are right, the
>>>>>>>> "server" part is not necessary. Will have to check with the qemu
>>>>>>>> community on this change.
>>>>>>>>
>>>>>>>>> +file.server.0.type=tcp,file.server.0.host=example.org,file.server.0.port=6000,\
>>>>>>>>> +file.server.1.type=tcp,file.server.1.host=example.org,file.server.1.port=24007,\
>>>>>>>>> +file.server.2.type=unix,file.server.2.socket=/path/to/sock,format=qcow2,\
>>>>>>>>>
>>>>>>>>> whereas, the VxHS syntax is:
>>>>>>>>>  +file.server.host=192.168.0.1,file.server.port=9999,format=raw,if=none,\
>>>>>>>>>
>>>>>>>>> FWIW: I also note there is no ".type=tcp" in your output - so perhaps
>>>>>>>>> the "default" is tcp unless otherwise specified, but I'm sure of the
>>>>>>>>> qemu syntax requirements in this area. I assume that since there's only
>>>>>>>>> 1 server, the ".0, .1, .2" become unnecessary (something added by commit
>>>>>>>>> id 'f1bbc7df4' for multiple gluster hosts).
>>>>>>>>>
>>>>>>>>
>>>>>>>> That's correct. TCP is the default.
>>>>>>>>
>>>>>>>>> I haven't closedly followed the qemu syntax discussion, but it would it
>>>>>>>>> would be possible to use:
>>>>>>>>>
>>>>>>>>> +file.host=192.168.0.1,file.port=9999
>>>>>>>>>
>>>>>>>>
>>>>>>>> That is correct. Above syntax would also work for us. I will pose this
>>>>>>>> suggestion to the qemu community and update with their response.
>>>>>>>>
>>>>>>
>>>>>> It's not that important... I was looking for a simplification and
>>>>>> generation of only what's required. You can continue using the server
>>>>>> syntax - perhaps just leave a note/comment in the code indicating the
>>>>>> decision point and move on.
>>>>>>
>>>>>> [...]
>>>>>>
>>>>>> John

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