[libvirt] [PATCH v2 2/2] daemon: Introduce max_anonymous_clients

[Daniel P. Berrange]

On Mon, Mar 03, 2014 at 06:22:44PM +0100, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=981729
> 
> This config tunable allows users to determine the maximum number of
> accepted but yet not authenticated users.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  daemon/libvirtd-config.c    |  1 +
>  daemon/libvirtd-config.h    |  1 +
>  daemon/libvirtd.aug         |  1 +
>  daemon/libvirtd.c           |  1 +
>  daemon/libvirtd.conf        |  4 ++++
>  daemon/test_libvirtd.aug.in |  1 +
>  src/locking/lock_daemon.c   |  3 +--
>  src/lxc/lxc_controller.c    |  2 +-
>  src/rpc/virnetserver.c      | 52 +++++++++++++++++++++++++++++++++++++++++++--
>  src/rpc/virnetserver.h      |  1 +
>  10 files changed, 62 insertions(+), 5 deletions(-)
> 
> diff --git a/daemon/libvirtd-config.c b/daemon/libvirtd-config.c
> index c816fda..04482c5 100644
> --- a/daemon/libvirtd-config.c
> +++ b/daemon/libvirtd-config.c
> @@ -415,6 +415,7 @@ daemonConfigLoadOptions(struct daemonConfig *data,
>      GET_CONF_INT(conf, filename, max_workers);
>      GET_CONF_INT(conf, filename, max_clients);
>      GET_CONF_INT(conf, filename, max_queued_clients);
> +    GET_CONF_INT(conf, filename, max_anonymous_clients);
>  
>      GET_CONF_INT(conf, filename, prio_workers);
>  

You need a 'data->max_anonymous_clients = 20' initialization somewher
in this file, otherwise it'll default to 0.

Also, don't we want to increase 'max_clients' to something much
larger like 5000 now that we rely on max_anonymous_clients to
protect against DOS attack.

> diff --git a/daemon/libvirtd.conf b/daemon/libvirtd.conf
> index 073c178..880f46a 100644
> --- a/daemon/libvirtd.conf
> +++ b/daemon/libvirtd.conf
> @@ -263,6 +263,10 @@
>  # connection succeeds.
>  #max_queued_clients = 1000
>  
> +# The maximum length of queue of accepted but not yet not
> +# authenticated clients. The default value is zero, meaning
> +# the feature is disabled.
> +#max_anonymous_clients = 20

same not about increasing max_clients value here.

> diff --git a/src/locking/lock_daemon.c b/src/locking/lock_daemon.c
> index e047751..054ece2 100644
> --- a/src/locking/lock_daemon.c
> +++ b/src/locking/lock_daemon.c
> @@ -145,8 +145,7 @@ virLockDaemonNew(virLockDaemonConfigPtr config, bool privileged)
>      }
>  
>      if (!(lockd->srv = virNetServerNew(1, 1, 0, config->max_clients,
> -                                       -1, 0,
> -                                       false, NULL,
> +                                       0, -1, 0, false, NULL,
>                                         virLockDaemonClientNew,
>                                         virLockDaemonClientPreExecRestart,
>                                         virLockDaemonClientFree,

We need to support max_anonymous_clients in the lock daemon config file
too and increase its max clients to something huge too. Each VM started
corresponds to an open client with the lock daemon, so we need that
value to be quite high.

> @@ -457,6 +468,7 @@ virNetServerPtr virNetServerNewPostExecRestart(virJSONValuePtr object,
>      unsigned int max_workers;
>      unsigned int priority_workers;
>      unsigned int max_clients;
> +    unsigned int nclients_unauth_max;
>      unsigned int keepaliveInterval;
>      unsigned int keepaliveCount;
>      bool keepaliveRequired;
> @@ -482,6 +494,11 @@ virNetServerPtr virNetServerNewPostExecRestart(virJSONValuePtr object,
>                         _("Missing max_clients data in JSON document"));
>          goto error;
>      }
> +    if (virJSONValueObjectGetNumberUint(object, "nclients_unauth_max", &nclients_unauth_max) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("Missing nclients_unauth_max data in JSON document"));

We can't raise an error here - that'll cause failure upon RPM upgrade
from version which didn't have this setting. Need to set some kind of
sensible default value upon upgrade.

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|