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




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).
>>
>> 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.

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
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.

> 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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