On Tue, Mar 04, 2014 at 04:56:24PM +0100, Michal Privoznik wrote:
On 04.03.2014 16:46, Michal Privoznik wrote:
On 04.03.2014 12:56, Daniel P. Berrange wrote:
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@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.
And I think we want to leave it that way. The value of zero means the feature is disabled. That is, libvirt won't take any actions if count of anonymous clients exceed certain value. It will still take an action though if the number of total clients (both auth and unauth) exceeds max_clients. The action is stop accept()-ing new clients. Trying to invent a bright formula to compute the correct value may lead to us adapting to a certain use case while forgetting about other. And we've been there before (remember 'Set reasonable RSS limit on domain startup'?). If a specific management application using libvirt requires these values it should set it explicitly in the config file rather than relying on libvirt defaults (which would change as libvirt adapts to different management application).
What we can do is change the commented default value in config file. Is that what you had in mind in the first place?
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.
I forgot to reply to this block. But my argumentation stays the same here. Moreover, there's no auth or unauth users in virlockd. I mean, all users are unauth by default and virlockd has no authentication mechanisms to make them authenticate. So either we will pass 0 here and let the rest of code deal with it as if the feature is disabled or pass config->max_clients which results in the same behavior in the end.
I forgot we didn't do auth here. We immediately check the UID of the client and drop them if not root, so we'd actually be perfectly safe to increase max_clients for the lock daemon already. 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 :|