Re: [Qemu-devel] [PATCH 3/6] migration: add support for a "tls-authz" migration parameter

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

On Fri, Jun 15, 2018 at 06:54:23PM +0100, Dr. David Alan Gilbert wrote:
> * Daniel P. Berrangé (berrange@redhat.com) wrote:
> > From: "Daniel P. Berrange" <berrange@redhat.com>
> > 
> > The QEMU instance that runs as the server for the migration data
> > transport (ie the target QEMU) needs to be able to configure access
> > control so it can prevent unauthorized clients initiating an incoming
> > migration. This adds a new 'tls-authz' migration parameter that is used
> > to provide the QOM ID of a QAuthZ subclass instance that provides the
> > access control check. This is checked against the x509 certificate
> > obtained during the TLS handshake.
> > 
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> 
> I'd appreciate an example of using it, either in the migration docs or
> the commit message.

Hmm, yes, it's an oversight to have missed an example in this commit
message.

> 
> > ---
> >  hmp.c                 |  9 +++++++++
> >  migration/migration.c |  8 ++++++++
> >  migration/tls.c       |  2 +-
> >  qapi/migration.json   | 12 +++++++++++-
> >  4 files changed, 29 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hmp.c b/hmp.c
> > index 74e18db103..bef8ea2531 100644
> > --- a/hmp.c
> > +++ b/hmp.c
> > @@ -370,6 +370,9 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
> >          monitor_printf(mon, "%s: %" PRIu64 "\n",
> >              MigrationParameter_str(MIGRATION_PARAMETER_XBZRLE_CACHE_SIZE),
> >              params->xbzrle_cache_size);
> > +        monitor_printf(mon, " %s: '%s'\n",
> > +            MigrationParameter_str(MIGRATION_PARAMETER_TLS_AUTHZ),
> > +            params->has_tls_authz ? params->tls_authz : "");
> >      }
> >  
> >      qapi_free_MigrationParameters(params);
> > @@ -1632,6 +1635,12 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
> >          p->tls_hostname->type = QTYPE_QSTRING;
> >          visit_type_str(v, param, &p->tls_hostname->u.s, &err);
> >          break;
> > +    case MIGRATION_PARAMETER_TLS_AUTHZ:
> > +        p->has_tls_authz = true;
> > +        p->tls_authz = g_new0(StrOrNull, 1);
> > +        p->tls_authz->type = QTYPE_QSTRING;
> > +        visit_type_str(v, param, &p->tls_authz->u.s, &err);
> > +        break;
> >      case MIGRATION_PARAMETER_MAX_BANDWIDTH:
> >          p->has_max_bandwidth = true;
> >          /*
> > diff --git a/migration/migration.c b/migration/migration.c
> > index 1e99ec9b7e..d14c8d7003 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -645,6 +645,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
> >      params->tls_creds = g_strdup(s->parameters.tls_creds);
> >      params->has_tls_hostname = true;
> >      params->tls_hostname = g_strdup(s->parameters.tls_hostname);
> > +    params->has_tls_authz = true;
> > +    params->tls_authz = g_strdup(s->parameters.tls_authz);
> >      params->has_max_bandwidth = true;
> >      params->max_bandwidth = s->parameters.max_bandwidth;
> >      params->has_downtime_limit = true;
> > @@ -1106,6 +1108,12 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
> >          s->parameters.tls_hostname = g_strdup(params->tls_hostname->u.s);
> >      }
> >  
> > +    if (params->has_tls_authz) {
> > +        g_free(s->parameters.tls_authz);
> > +        assert(params->tls_authz->type == QTYPE_QSTRING);
> > +        s->parameters.tls_authz = g_strdup(params->tls_authz->u.s);
> > +    }
> > +
> >      if (params->has_max_bandwidth) {
> >          s->parameters.max_bandwidth = params->max_bandwidth;
> >          if (s->to_dst_file) {
> > diff --git a/migration/tls.c b/migration/tls.c
> > index 3b9e8c9263..5171afc6c4 100644
> > --- a/migration/tls.c
> > +++ b/migration/tls.c
> > @@ -94,7 +94,7 @@ void migration_tls_channel_process_incoming(MigrationState *s,
> >  
> >      tioc = qio_channel_tls_new_server(
> >          ioc, creds,
> > -        NULL, /* XXX pass ACL name */
> > +        s->parameters.tls_authz,
> >          errp);
> >      if (!tioc) {
> >          return;
> > diff --git a/qapi/migration.json b/qapi/migration.json
> > index f7e10ee90f..b9ba34e3a6 100644
> > --- a/qapi/migration.json
> > +++ b/qapi/migration.json
> > @@ -488,6 +488,10 @@
> >  #                hostname must be provided so that the server's x509
> >  #                certificate identity can be validated. (Since 2.7)
> >  #
> > +# @tls-authz: ID of the 'authz' object subclass that provides access control
> > +#             checking of the TLS x509 certificate distinguished name. (Since
> > +#             2.13)
> > +#
> 
> Oops, 2.13 strikes again :-)
> 
> Other than that, OK from migration and HMP.
> 
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> >  # @max-bandwidth: to set maximum speed for migration. maximum speed in
> >  #                 bytes per second. (Since 2.8)
> >  #
> > @@ -522,7 +526,7 @@
> >  { 'enum': 'MigrationParameter',
> >    'data': ['compress-level', 'compress-threads', 'decompress-threads',
> >             'cpu-throttle-initial', 'cpu-throttle-increment',
> > -           'tls-creds', 'tls-hostname', 'max-bandwidth',
> > +           'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
> >             'downtime-limit', 'x-checkpoint-delay', 'block-incremental',
> >             'x-multifd-channels', 'x-multifd-page-count',
> >             'xbzrle-cache-size' ] }
> > @@ -605,6 +609,7 @@
> >              '*cpu-throttle-increment': 'int',
> >              '*tls-creds': 'StrOrNull',
> >              '*tls-hostname': 'StrOrNull',
> > +            '*tls-authz': 'StrOrNull',
> >              '*max-bandwidth': 'int',
> >              '*downtime-limit': 'int',
> >              '*x-checkpoint-delay': 'int',
> > @@ -667,6 +672,10 @@
> >  #                associated with the migration URI, if any. (Since 2.9)
> >  #                Note: 2.8 reports this by omitting tls-hostname instead.
> >  #
> > +# @tls-authz: ID of the 'authz' object subclass that provides access control
> > +#             checking of the TLS x509 certificate distinguished name. (Since
> > +#             2.13)
> > +#
> >  # @max-bandwidth: to set maximum speed for migration. maximum speed in
> >  #                 bytes per second. (Since 2.8)
> >  #
> > @@ -704,6 +713,7 @@
> >              '*cpu-throttle-increment': 'uint8',
> >              '*tls-creds': 'str',
> >              '*tls-hostname': 'str',
> > +            '*tls-authz': 'str',
> >              '*max-bandwidth': 'size',
> >              '*downtime-limit': 'uint64',
> >              '*x-checkpoint-delay': 'uint32',
> > -- 
> > 2.17.0
> > 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Regards,
Daniel
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