Re: [Qemu-devel] [PATCH v5 1/2] qemu-nbd: add support for authorization of TLS clients

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Feb 27, 2019 at 03:33:31PM +0000, Daniel P. Berrangé wrote:
> On Wed, Feb 27, 2019 at 08:25:20AM -0600, Eric Blake wrote:
> > On 2/27/19 5:51 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
> > > 
> > > escape the commas in the name and 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' \
> > >            --tls-creds tls0 \
> > >            --tls-authz authz0 \
> > > 	   ....other qemu-nbd args...
> > > 
> > > NB: a real shell command line would not have leading whitespace after
> > > the line continuation, it is just included here for clarity.


> > >  echo "== check TLS works =="
> > > -obj=tls-creds-x509,dir=${tls_dir}/client1,endpoint=client,id=tls0
> > > -$QEMU_IMG info --image-opts --object $obj \
> > > +obj1=tls-creds-x509,dir=${tls_dir}/client1,endpoint=client,id=tls0
> > > +obj2=tls-creds-x509,dir=${tls_dir}/client3,endpoint=client,id=tls0
> > > +$QEMU_IMG info --image-opts --object $obj1 \
> > >      driver=nbd,host=$nbd_tcp_addr,port=$nbd_tcp_port,tls-creds=tls0 \
> > >      2>&1 | sed "s/$nbd_tcp_port/PORT/g"
> > > -$QEMU_NBD_PROG -L -b $nbd_tcp_addr -p $nbd_tcp_port --object $obj \
> > > +$QEMU_IMG info --image-opts --object $obj2 \
> > > +    driver=nbd,host=$nbd_tcp_addr,port=$nbd_tcp_port,tls-creds=tls0 \
> > > +    2>&1 | sed "s/$nbd_tcp_port/PORT/g"
> > > +$QEMU_NBD_PROG -L -b $nbd_tcp_addr -p $nbd_tcp_port --object $obj1 \
> > >      --tls-creds=tls0
> > 
> > It looks like you have both a positive and negative test that a qemu-img
> > client can only connect with the right auth, but only a positive test
> > for a qemu-nbd --list client.  Should we also duplicate the
> > QEMU_NBD_PROG line to use $obj2 for a negative test?
> 
> I can look at that

On reflection I don't think that's needed. This is a server side feature we
are validating. As such it is sufficient to validate with any client app
supporting TLS. IOW, qemu-img is sufficient to prove the server side feature
is working correctly.

> 
> > 
> > >  
> > >  echo
> > > @@ -117,6 +122,26 @@ $QEMU_IO -c 'r -P 0x11 1m 1m' -c 'w -P 0x22 1m 1m' --image-opts \
> > >  
> > >  $QEMU_IO -f $IMGFMT -r -U -c 'r -P 0x22 1m 1m' "$TEST_IMG" | _filter_qemu_io
> > >  
> > > +echo
> > > +echo "== check TLS with authorization =="
> > > +
> > > +nbd_server_stop
> > > +
> > > +nbd_server_start_tcp_socket \
> > > +    --object tls-creds-x509,dir=${tls_dir}/server1,endpoint=server,id=tls0,verify-peer=yes \
> > > +    --object "authz-simple,identity=CN=localhost,,O=Cthulu Dark Lord Enterprises client1,,L=R'lyeh,,C=South Pacific,id=authz0" \
> > > +    --tls-authz authz0 \
> > > +    --tls-creds tls0 \
> > > +    -f $IMGFMT "$TEST_IMG" 2>> "$TEST_DIR/server.log"
> > > +
> > > +$QEMU_IMG info --image-opts \
> > > +    --object tls-creds-x509,dir=${tls_dir}/client1,endpoint=client,id=tls0 \
> > > +    driver=nbd,host=$nbd_tcp_addr,port=$nbd_tcp_port,tls-creds=tls0
> > > +
> > > +$QEMU_IMG info --image-opts \
> > > +    --object tls-creds-x509,dir=${tls_dir}/client3,endpoint=client,id=tls0 \
> > > +    driver=nbd,host=$nbd_tcp_addr,port=$nbd_tcp_port,tls-creds=tls0
> > 
> > Similarly, do we want --list testing here?
> 
> I'll have a look.

For same reason as above, we don't need to repeat with qemu-nbd --list

Regards,
Daniel
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