Re: [PATCH 02/12] block: pass desired TLS hostname through from block driver client

[Eric Blake]

On Thu, Mar 03, 2022 at 04:03:20PM +0000, Daniel P. Berrangé wrote:
> In
> 
>   commit a71d597b989fd701b923f09b3c20ac4fcaa55e81
>   Author: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>   Date:   Thu Jun 10 13:08:00 2021 +0300
> 
>     block/nbd: reuse nbd_co_do_establish_connection() in nbd_open()
> 
> the use of the 'hostname' field from the BDRVNBDState struct was
> lost, and 'nbd_connect' just hardcoded it to match the IP socket
> address. This was a harmless bug at the time since we block use
> with anything other than IP sockets.
> 
> Shortly though, We want to allow the caller to override the hostname

s/We/we/

> used in the TLS certificate checks. This is to allow for TLS
> when doing port forwarding or tunneling. Thus we need to reinstate
> the passing along of the 'hostname'.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  block/nbd.c             |  7 ++++---
>  include/block/nbd.h     |  3 ++-
>  nbd/client-connection.c | 12 +++++++++---
>  3 files changed, 15 insertions(+), 7 deletions(-)

Nice - this a great step towards fixing a longstanding annoyance of
mine that libnbd and nbdkit support TLS over Unix sockets, but qemu
didn't.

> @@ -1875,7 +1875,8 @@ static int nbd_open(BlockDriverState *bs, QDict 
> *options, int flags,
>      }
>  
>      s->conn = nbd_client_connection_new(s->saddr, true, s->export,
> -                                        s->x_dirty_bitmap, s->tlscreds);
> +                                        s->x_dirty_bitmap, s->tlscreds,
> +                                        s->tlshostname);
>  
>      if (s->open_timeout) {
>          nbd_client_connection_enable_retry(s->conn);
> diff --git a/include/block/nbd.h b/include/block/nbd.h
> index 78d101b774..a98eb665da 100644
> --- a/include/block/nbd.h
> +++ b/include/block/nbd.h
> @@ -415,7 +415,8 @@ NBDClientConnection *nbd_client_connection_new(const 
> SocketAddress *saddr,
>                                                 bool do_negotiation,
>                                                 const char *export_name,
>                                                 const char *x_dirty_bitmap,
> -                                               QCryptoTLSCreds *tlscreds);
> +                                               QCryptoTLSCreds *tlscreds,
> +                                               const char *tlshostname);

We already have a lot of parameters; does it make sense to bundle
tlshostname into the QCryptoTLSCreds struct at all?  But that would
change the QAPI (or maybe you do it later in the series), it is not a
show-stopper to this patch.

Reviewed-by: Eric Blake <eblake@redhat.com>

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