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Re: [libvirt] [PATCH v3 1/6] qemu-nbd: add support for authorization of TLS clients



On 10/9/18 8:23 AM, Daniel P. Berrangé wrote:
From: "Daniel P. Berrange" <berrange redhat com>

Currently any client which can complete the TLS handshake is able to use
the NBD server. The server admin can turn on the 'verify-peer' option
for the x509 creds to require the client to provide a x509 certificate.
This means the client will have to acquire a certificate from the CA
before they are permitted to use the NBD server. This is still a fairly
low bar to cross.

This adds a '--tls-authz OBJECT-ID' option to the qemu-nbd command which
takes the ID of a previously added 'QAuthZ' object instance. This will
be used to validate the client's x509 distinguished name. Clients
failing the authorization check will not be permitted to use the NBD
server.

For example to setup authorization that only allows connection from a client
whose x509 certificate distinguished name is

    CN=laptop.example.com,O=Example Org,L=London,ST=London,C=GB

use:

   qemu-nbd --object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\
                     endpoint=server,verify-peer=yes \
            --object authz-simple,id=auth0,identity=CN=laptop.example.com,,\
                     O=Example Org,,L=London,,ST=London,,C=GB \

Missing shell quoting around the space in 'Example Org'. It's also fairly obvious that actual shell commands can't have leading space between \-newline line continuations.

            --tls-creds tls0 \
            --tls-authz authz0
	   ....other qemu-nbd args...

Signed-off-by: Daniel P. Berrange <berrange redhat com>
---
  include/block/nbd.h |  2 +-
  nbd/server.c        | 10 +++++-----
  qemu-nbd.c          | 13 ++++++++++++-
  qemu-nbd.texi       |  4 ++++
  4 files changed, 22 insertions(+), 7 deletions(-)


+++ b/qemu-nbd.c
@@ -52,6 +52,7 @@
  #define QEMU_NBD_OPT_TLSCREDS      261
  #define QEMU_NBD_OPT_IMAGE_OPTS    262
  #define QEMU_NBD_OPT_FORK          263
+#define QEMU_NBD_OPT_TLSAUTHZ      264

@@ -532,6 +534,7 @@ int main(int argc, char **argv)
          { "image-opts", no_argument, NULL, QEMU_NBD_OPT_IMAGE_OPTS },
          { "trace", required_argument, NULL, 'T' },
          { "fork", no_argument, NULL, QEMU_NBD_OPT_FORK },
+        { "tls-authz", no_argument, NULL, QEMU_NBD_OPT_TLSAUTHZ },
          { NULL, 0, NULL, 0 }
      };

Missing a change to qemu-nbd --help to describe the new option.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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