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Re: [libvirt] [PATCH v4 2/3] conf: Introduce TLS options for VxHS block device clients



On Mon, Jul 17, 2017 at 4:50 PM, John Ferlan <jferlan redhat com> wrote:
>
>
> On 07/12/2017 06:09 PM, ashish mittal wrote:
>> On Fri, Jun 30, 2017 at 1:29 PM, John Ferlan <jferlan redhat com> wrote:
>>>
>>>
>>> On 06/29/2017 10:02 PM, Ashish Mittal wrote:
>>>> From: Ashish Mittal <ashish mittal veritas com>
>>>>
>>>> Add a new TLS X.509 certificate type - "vxhs". This will handle the
>>>> creation of a TLS certificate capability for properly configured
>>>> VxHS network block device clients.
>>>>
>>>> Signed-off-by: Ashish Mittal <ashish mittal veritas com>
>>>> ---
>>>> Changelog:
>>>>
>>>> (1) Add two new options in /etc/libvirt/qemu.conf
>>>>     to control TLS behavior with VxHS block devices
>>>>     "vxhs_tls" and "vxhs_tls_x509_cert_dir".
>>>> (2) Setting "vxhs_tls=1" in /etc/libvirt/qemu.conf will enable
>>>>     TLS for VxHS block devices.
>>>> (3) "vxhs_tls_x509_cert_dir" can be set to the full path where the
>>>>     TLS certificates and keys are saved. If this value is missing,
>>>>     the "default_tls_x509_cert_dir" will be used instead.
>>>>
>>>>  src/qemu/libvirtd_qemu.aug         |  4 ++++
>>>>  src/qemu/qemu.conf                 | 23 +++++++++++++++++++++++
>>>>  src/qemu/qemu_conf.c               |  7 +++++++
>>>>  src/qemu/qemu_conf.h               |  3 +++
>>>>  src/qemu/test_libvirtd_qemu.aug.in |  2 ++
>>>>  5 files changed, 39 insertions(+)
>>>>
>>>
>>> FWIW: I have another patch upstream:
>>>
>>> https://www.redhat.com/archives/libvir-list/2017-June/msg01341.html
>>>
>>> Which is making some textual and code changes to qemu.conf and
>>> qemu_conf.c - just so you are aware.
>>>
>>>
>>>> diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug
>>>> index e1983d1..c19bf3a 100644
>>>> --- a/src/qemu/libvirtd_qemu.aug
>>>> +++ b/src/qemu/libvirtd_qemu.aug
>>>> @@ -115,6 +115,9 @@ module Libvirtd_qemu =
>>>>
>>>>     let memory_entry = str_entry "memory_backing_dir"
>>>>
>>>> +   let vxhs_entry = bool_entry "vxhs_tls"
>>>> +                 | str_entry "vxhs_tls_x509_cert_dir"
>>>> +
>>>>     (* Each entry in the config is one of the following ... *)
>>>>     let entry = default_tls_entry
>>>>               | vnc_entry
>>>> @@ -133,6 +136,7 @@ module Libvirtd_qemu =
>>>>               | nvram_entry
>>>>               | gluster_debug_level_entry
>>>>               | memory_entry
>>>> +             | vxhs_entry
>>>>
>>>>     let comment = [ label "#comment" . del /#[ \t]*/ "# " .  store /([^ \t\n][^\n]*)?/ . del /\n/ "\n" ]
>>>>     let empty = [ label "#empty" . eol ]
>>>> diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf
>>>> index e6c0832..83c2377 100644
>>>> --- a/src/qemu/qemu.conf
>>>> +++ b/src/qemu/qemu.conf
>>>> @@ -250,6 +250,29 @@
>>>>  #chardev_tls_x509_secret_uuid = "00000000-0000-0000-0000-000000000000"
>>>>
>>>>
>>>> +# Enable use of TLS encryption on the VxHS network block devices.
>>>> +#
>>>> +# When the VxHS network block device server is set up appropriately,
>>>> +# x509 certificates are used for authentication between the clients
>>>> +# (qemu processes) and the remote VxHS server.
>>>> +#
>>>> +# It is necessary to setup CA and issue client and server certificates
>>>> +# before enabling this.
>>>> +#
>>>> +#vxhs_tls = 1
>>>> +
>>>> +
>>>> +# In order to override the default TLS certificate location for VxHS
>>>> +# device TCP certificates, supply a valid path to the certificate directory.
>>>> +# This is used to authenticate the VxHS block device clients to the VxHS
>>>> +# server.
>>>> +#
>>>> +# If the provided path does not exist then the default_tls_x509_cert_dir
>>>> +# path will be used.
>>>> +#
>>>> +#vxhs_tls_x509_cert_dir = "/etc/pki/libvirt-vxhs"
>>>> +
>>>> +
>>>>  # In order to override the default TLS certificate location for migration
>>>>  # certificates, supply a valid path to the certificate directory. If the
>>>>  # provided path does not exist then the default_tls_x509_cert_dir path
>>>
>>> In patch 3, the call to qemuBuildTLSx509CommandLine has a @verifypeer
>>> parameter = true, thus it's always going to expect to verify the client
>>> rather than making that determination using *_tls_x509_verify. So that
>>> means you have to describe the environment as requiring the
>>> client-cert.pem and client-key.pem files (like the description for default).
>>>

As you have rightly noted later, we are actually setting up the client
TLS env here (libvirt/qemu = vxhs client). I hope the default
libvirt/qemu TLS env can be used for setting up the client connection
also! If not, then I guess I just have to mandate a dedicated vxhs TLS
env.

vxhs server TLS env setup would happen separately. So the @verifypeer
parameter = true in qemuBuildTLSx509CommandLine would apply to the
client connection and be ignored anyway (is true by default for the
client). If, on the vxhs server side, we were to set up the env with
@verifypeer parameter = false, then the client (libvirt/qemu) would
not need client-cert.pem and client-key.pem files. That said, we do
desire authentication of the client, and the client-cert.pem and
client-key.pem files would be needed in that case. I hope my
understanding is not terribly wrong.

>>> Since you set the @addpasswordid to false on input, that just means the
>>> certificate server-key.pem file cannot be encrypted - something else
>>> that would need to be described.
>>>
>>
>> During the QEMU discussions on VxHS support for TLS, it was a agreed
>> that it was not necessary to encrypt the cert files.
>>
>>> Based on these two configuration settings, that means if vxhs_tls=1,
>>> then vxhs_tls_x509_cert_dir must be set to something other than the
>>> default environment. IOW: both must be defined and that would need to be
>>> validated during config read and cause failure (e.g. vxhsTLSx509certdir
>>> != defaultTLSx509certdir
>>>
>>> IOW: You're essentially *requiring* someone to set this up and don't
>>> handle the/a default environment. Hopefully this makes sense, it's
>>> Friday afternoon and I have a TLS migraine ;-).
>>>
>>
>> The ideal way is for VxHS to be able to use the default TLS
>> environment. These settings are for the VxHS client i.e. QEMU. VxHS
>> server would be running on a remote host and would have it's own
>> configuration settings.
>>
>> Could you please give me some pointers on what changes would be
>> required to reuse the default TLS environment? I am hoping these would
>> not necessitate any change in the qemu vxhs code.
>>
>
> The reality is - I don't believe you have to do anything other than
> describe if the default environment is using a password, then the
> consumer must create their own vxhs certificate environment that doesn't
> require a password/secret to decrypt the certificate.
>

Thanks for your response. I think I understand this better now!

Please correct me if the understanding below is not accurate -

(1) the default TLS environment could potentially use encrypted TLS
certificates (I guess it's only the *key.pem files that would need to
be encrypted).
(2) if it is indeed using encrypted TLS key.pem files, then it passes
along a secret password to decrypt the key files. This secret is
passed along to QEMU for actual processing. Therefore, if I wanted to
support secrets with vxhs, I would first have to change qemu code.
(3) VxHS does not accept secrets, therefore it cannot use the default
TLS env if it has been encrypted.
(4) I guess, as you have pointed out, I would have to add code to
check if the default TLS env is using secrets, and fail the operation
if a dedicated VxHS env has not been provided in this scenario.


> Of course this is all predicated on the thought that the certificate
> being used is not validating libvirt<->qemu, rather its validating
> qemu<->vxhs-server. There's a bit of black magic that happens that I

That is correct! For the VxHS block device, qemu is the client and the
vxhs block device server would be remote. We are setting up the qemu
client TLS environment via libvirt. The vxhs server TLS setup would be
done separately from within the vxhs server code.

> haven't dug into. I'm assuming that you'd be testing both a cert and
> non-cert environment... Add to your testing a 'what-if' someone provides
> a default environment *and* that environment required the secret. In
> that case, you should expect a failure.
>

I will add try to add this test case. Thanks!

>> Thanks,
>> Ashish
>>
>>
>>> John
>>>
>>>> diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
>>>> index 73c33d6..f3813d4 100644
>>>> --- a/src/qemu/qemu_conf.c
>>>> +++ b/src/qemu/qemu_conf.c
>>>> @@ -280,6 +280,7 @@ virQEMUDriverConfigPtr virQEMUDriverConfigNew(bool privileged)
>>>>      SET_TLS_X509_CERT_DEFAULT(spice);
>>>>      SET_TLS_X509_CERT_DEFAULT(chardev);
>>>>      SET_TLS_X509_CERT_DEFAULT(migrate);
>>>> +    SET_TLS_X509_CERT_DEFAULT(vxhs);
>>>>
>>>>  #undef SET_TLS_X509_CERT_DEFAULT
>>>>
>>>> @@ -395,6 +396,8 @@ static void virQEMUDriverConfigDispose(void *obj)
>>>>      VIR_FREE(cfg->chardevTLSx509certdir);
>>>>      VIR_FREE(cfg->chardevTLSx509secretUUID);
>>>>
>>>> +    VIR_FREE(cfg->vxhsTLSx509certdir);
>>>> +
>>>>      VIR_FREE(cfg->migrateTLSx509certdir);
>>>>      VIR_FREE(cfg->migrateTLSx509secretUUID);
>>>>
>>>> @@ -533,6 +536,10 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
>>>>          goto cleanup;
>>>>      if (virConfGetValueBool(conf, "spice_auto_unix_socket", &cfg->spiceAutoUnixSocket) < 0)
>>>>          goto cleanup;
>>>> +    if (virConfGetValueBool(conf, "vxhs_tls", &cfg->vxhsTLS) < 0)
>>>> +        goto cleanup;
>>>> +    if (virConfGetValueString(conf, "vxhs_tls_x509_cert_dir", &cfg->vxhsTLSx509certdir) < 0)
>>>> +        goto cleanup;
>>>>
>>>>  #define GET_CONFIG_TLS_CERTINFO(val)                                        \
>>>>      do {                                                                    \
>>>> diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
>>>> index 1407eef..96c0225 100644
>>>> --- a/src/qemu/qemu_conf.h
>>>> +++ b/src/qemu/qemu_conf.h
>>>> @@ -201,6 +201,9 @@ struct _virQEMUDriverConfig {
>>>>      unsigned int glusterDebugLevel;
>>>>
>>>>      char *memoryBackingDir;
>>>> +
>>>> +    bool vxhsTLS;
>>>> +    char *vxhsTLSx509certdir;
>>>>  };
>>>>
>>>>  /* Main driver state */
>>>> diff --git a/src/qemu/test_libvirtd_qemu.aug.in b/src/qemu/test_libvirtd_qemu.aug.in
>>>> index 3e317bc..dfe88f4 100644
>>>> --- a/src/qemu/test_libvirtd_qemu.aug.in
>>>> +++ b/src/qemu/test_libvirtd_qemu.aug.in
>>>> @@ -25,6 +25,8 @@ module Test_libvirtd_qemu =
>>>>  { "chardev_tls_x509_cert_dir" = "/etc/pki/libvirt-chardev" }
>>>>  { "chardev_tls_x509_verify" = "1" }
>>>>  { "chardev_tls_x509_secret_uuid" = "00000000-0000-0000-0000-000000000000" }
>>>> +{ "vxhs_tls" = "1" }
>>>> +{ "vxhs_tls_x509_cert_dir" = "/etc/pki/libvirt-vxhs" }
>>>>  { "migrate_tls_x509_cert_dir" = "/etc/pki/libvirt-migrate" }
>>>>  { "migrate_tls_x509_verify" = "1" }
>>>>  { "migrate_tls_x509_secret_uuid" = "00000000-0000-0000-0000-000000000000" }
>>>>


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