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[libvirt] [PATCH 1/4] event: track callbackID on daemon side of RPC



Right now, the daemon side of RPC events is hard-coded to at most
one callback per eventID.  But when there are hundreds of domains
or networks coupled and multiple conections, then sending every
event to every connection that wants an event, even for the
connections that only care about events for a particular object,
is inefficient.  In order to track more than one callback in the
server, we need to store callbacks by more than just their
eventID.  This patch rearranges the daemon side to store network
callbacks in a dynamic array, which can eventually be used for
multiple callbacks of the same eventID, although actual behavior
is unchanged without further patches to the RPC protocol.  For
ease of review, domain events are saved for a later patch, as
they touch more code.

While at it, fix a bug where a malicious client could send a
negative eventID to cause network event registration to access
outside of array bounds (thankfully not a CVE, since domain
events were already doing the bounds check, and since network
events have not been released).

* daemon/libvirtd.h (daemonClientPrivate): Alter the tracking of
network events.
* daemon/remote.c (daemonClientEventCallback): New struct.
(remoteEventCallbackFree): New function.
(remoteClientInitHook, remoteRelayNetworkEventLifecycle)
(remoteClientFreeFunc)
(remoteDispatchConnectNetworkEventRegisterAny): Track network
callbacks differently.
(remoteDispatchConnectNetworkEventDeregisterAny): Enforce bounds.

Signed-off-by: Eric Blake <eblake redhat com>
---
 daemon/libvirtd.h |   7 +++-
 daemon/remote.c   | 113 ++++++++++++++++++++++++++++++++++++++----------------
 2 files changed, 85 insertions(+), 35 deletions(-)

diff --git a/daemon/libvirtd.h b/daemon/libvirtd.h
index 47f2589..a260ea1 100644
--- a/daemon/libvirtd.h
+++ b/daemon/libvirtd.h
@@ -1,7 +1,7 @@
 /*
  * libvirtd.h: daemon data structure definitions
  *
- * Copyright (C) 2006-2013 Red Hat, Inc.
+ * Copyright (C) 2006-2014 Red Hat, Inc.
  * Copyright (C) 2006 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -43,6 +43,8 @@ typedef struct daemonClientStream daemonClientStream;
 typedef daemonClientStream *daemonClientStreamPtr;
 typedef struct daemonClientPrivate daemonClientPrivate;
 typedef daemonClientPrivate *daemonClientPrivatePtr;
+typedef struct daemonClientEventCallback daemonClientEventCallback;
+typedef daemonClientEventCallback *daemonClientEventCallbackPtr;

 /* Stores the per-client connection state */
 struct daemonClientPrivate {
@@ -50,7 +52,8 @@ struct daemonClientPrivate {
     virMutex lock;

     int domainEventCallbackID[VIR_DOMAIN_EVENT_ID_LAST];
-    int networkEventCallbackID[VIR_NETWORK_EVENT_ID_LAST];
+    daemonClientEventCallbackPtr *networkEventCallbacks;
+    size_t nnetworkEventCallbacks;

 # if WITH_SASL
     virNetSASLSessionPtr sasl;
diff --git a/daemon/remote.c b/daemon/remote.c
index 6ce9ec1..ae318b2 100644
--- a/daemon/remote.c
+++ b/daemon/remote.c
@@ -1,7 +1,7 @@
 /*
  * remote.c: handlers for RPC method calls
  *
- * Copyright (C) 2007-2013 Red Hat, Inc.
+ * Copyright (C) 2007-2014 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -72,6 +72,12 @@
 # define HYPER_TO_ULONG(_to, _from) (_to) = (_from)
 #endif

+struct daemonClientEventCallback {
+    virNetServerClientPtr client;
+    int eventID;
+    int callbackID;
+};
+
 static virDomainPtr get_nonnull_domain(virConnectPtr conn, remote_nonnull_domain domain);
 static virNetworkPtr get_nonnull_network(virConnectPtr conn, remote_nonnull_network network);
 static virInterfacePtr get_nonnull_interface(virConnectPtr conn, remote_nonnull_interface iface);
@@ -115,6 +121,12 @@ remoteDispatchObjectEventSend(virNetServerClientPtr client,
                               xdrproc_t proc,
                               void *data);

+static void
+remoteEventCallbackFree(void *opaque)
+{
+    VIR_FREE(opaque);
+}
+
 static int remoteRelayDomainEventLifecycle(virConnectPtr conn ATTRIBUTE_UNUSED,
                                            virDomainPtr dom,
                                            int event,
@@ -654,19 +666,21 @@ static virConnectDomainEventGenericCallback domainEventCallbacks[] = {

 verify(ARRAY_CARDINALITY(domainEventCallbacks) == VIR_DOMAIN_EVENT_ID_LAST);

-static int remoteRelayNetworkEventLifecycle(virConnectPtr conn ATTRIBUTE_UNUSED,
-                                            virNetworkPtr net,
-                                            int event,
-                                            int detail,
-                                            void *opaque)
+static int
+remoteRelayNetworkEventLifecycle(virConnectPtr conn ATTRIBUTE_UNUSED,
+                                 virNetworkPtr net,
+                                 int event,
+                                 int detail,
+                                 void *opaque)
 {
-    virNetServerClientPtr client = opaque;
+    daemonClientEventCallbackPtr callback = opaque;
     remote_network_event_lifecycle_msg data;

-    if (!client)
+    if (callback->callbackID < 0)
         return -1;

-    VIR_DEBUG("Relaying network lifecycle event %d, detail %d", event, detail);
+    VIR_DEBUG("Relaying network lifecycle event %d, detail %d, callback %d",
+              event, detail, callback->callbackID);

     /* build return data */
     memset(&data, 0, sizeof(data));
@@ -674,7 +688,7 @@ static int remoteRelayNetworkEventLifecycle(virConnectPtr conn ATTRIBUTE_UNUSED,
     data.event = event;
     data.detail = detail;

-    remoteDispatchObjectEventSend(client, remoteProgram,
+    remoteDispatchObjectEventSend(callback->client, remoteProgram,
                                   REMOTE_PROC_NETWORK_EVENT_LIFECYCLE,
                                   (xdrproc_t)xdr_remote_network_event_lifecycle_msg, &data);

@@ -714,14 +728,20 @@ void remoteClientFreeFunc(void *data)
             priv->domainEventCallbackID[i] = -1;
         }

-        for (i = 0; i < VIR_NETWORK_EVENT_ID_LAST; i++) {
-            if (priv->networkEventCallbackID[i] != -1) {
-                VIR_DEBUG("Deregistering to relay remote events %zu", i);
-                virConnectNetworkEventDeregisterAny(priv->conn,
-                                                    priv->networkEventCallbackID[i]);
+        for (i = 0; i < priv->nnetworkEventCallbacks; i++) {
+            int callbackID = priv->networkEventCallbacks[i]->callbackID;
+            if (callbackID < 0) {
+                VIR_WARN("unexpected incomplete network callback %zu", i);
+                continue;
             }
-            priv->networkEventCallbackID[i] = -1;
+            VIR_DEBUG("Deregistering remote network event relay %d",
+                      callbackID);
+            priv->networkEventCallbacks[i]->callbackID = -1;
+            if (virConnectNetworkEventDeregisterAny(priv->conn,
+                                                    callbackID) < 0)
+                VIR_WARN("unexpected network event deregister failure");
         }
+        VIR_FREE(priv->networkEventCallbacks);

         virConnectClose(priv->conn);

@@ -759,9 +779,6 @@ void *remoteClientInitHook(virNetServerClientPtr client,
     for (i = 0; i < VIR_DOMAIN_EVENT_ID_LAST; i++)
         priv->domainEventCallbackID[i] = -1;

-    for (i = 0; i < VIR_NETWORK_EVENT_ID_LAST; i++)
-        priv->networkEventCallbackID[i] = -1;
-
     virNetServerClientSetCloseHook(client, remoteClientCloseFunc);
     return priv;
 }
@@ -5264,7 +5281,7 @@ cleanup:

 static int
 remoteDispatchConnectNetworkEventRegisterAny(virNetServerPtr server ATTRIBUTE_UNUSED,
-                                             virNetServerClientPtr client ATTRIBUTE_UNUSED,
+                                             virNetServerClientPtr client,
                                              virNetMessagePtr msg ATTRIBUTE_UNUSED,
                                              virNetMessageErrorPtr rerr ATTRIBUTE_UNUSED,
                                              remote_connect_network_event_register_any_args *args,
@@ -5272,6 +5289,8 @@ remoteDispatchConnectNetworkEventRegisterAny(virNetServerPtr server ATTRIBUTE_UN
 {
     int callbackID;
     int rv = -1;
+    daemonClientEventCallbackPtr callback = NULL;
+    daemonClientEventCallbackPtr ref;
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);

@@ -5282,28 +5301,47 @@ remoteDispatchConnectNetworkEventRegisterAny(virNetServerPtr server ATTRIBUTE_UN

     virMutexLock(&priv->lock);

-    if (args->eventID >= VIR_NETWORK_EVENT_ID_LAST) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, _("unsupported network event ID %d"), args->eventID);
+    if (args->eventID >= VIR_NETWORK_EVENT_ID_LAST || args->eventID < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unsupported network event ID %d"), args->eventID);
         goto cleanup;
     }

-    if (priv->networkEventCallbackID[args->eventID] != -1) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, _("network event %d already registered"), args->eventID);
+    /* If we call register first, we could append a complete callback
+     * to our array, but on OOM append failure, we'd have to then hope
+     * deregister works to undo our register.  So instead we append an
+     * incomplete callback to our array, then register, then fix up
+     * our callback; but since VIR_APPEND_ELEMENT clears 'callback' on
+     * success, we use 'ref' to save a copy of the pointer.  */
+    if (VIR_ALLOC(callback) < 0)
+        goto cleanup;
+    callback->client = client;
+    callback->eventID = args->eventID;
+    callback->callbackID = -1;
+    ref = callback;
+    if (VIR_APPEND_ELEMENT(priv->networkEventCallbacks,
+                           priv->nnetworkEventCallbacks,
+                           callback) < 0)
         goto cleanup;
-    }

     if ((callbackID = virConnectNetworkEventRegisterAny(priv->conn,
                                                         NULL,
                                                         args->eventID,
                                                         networkEventCallbacks[args->eventID],
-                                                        client, NULL)) < 0)
+                                                        ref,
+                                                        remoteEventCallbackFree)) < 0) {
+        VIR_SHRINK_N(priv->networkEventCallbacks,
+                     priv->nnetworkEventCallbacks, 1);
+        callback = ref;
         goto cleanup;
+    }

-    priv->networkEventCallbackID[args->eventID] = callbackID;
+    ref->callbackID = callbackID;

     rv = 0;

 cleanup:
+    VIR_FREE(callback);
     if (rv < 0)
         virNetMessageSaveError(rerr);
     virMutexUnlock(&priv->lock);
@@ -5313,7 +5351,7 @@ cleanup:

 static int
 remoteDispatchConnectNetworkEventDeregisterAny(virNetServerPtr server ATTRIBUTE_UNUSED,
-                                               virNetServerClientPtr client ATTRIBUTE_UNUSED,
+                                               virNetServerClientPtr client,
                                                virNetMessagePtr msg ATTRIBUTE_UNUSED,
                                                virNetMessageErrorPtr rerr ATTRIBUTE_UNUSED,
                                                remote_connect_network_event_deregister_any_args *args,
@@ -5321,6 +5359,7 @@ remoteDispatchConnectNetworkEventDeregisterAny(virNetServerPtr server ATTRIBUTE_
 {
     int callbackID = -1;
     int rv = -1;
+    size_t i;
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);

@@ -5331,21 +5370,29 @@ remoteDispatchConnectNetworkEventDeregisterAny(virNetServerPtr server ATTRIBUTE_

     virMutexLock(&priv->lock);

-    if (args->eventID >= VIR_NETWORK_EVENT_ID_LAST) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, _("unsupported event ID %d"), args->eventID);
+    if (args->eventID >= VIR_NETWORK_EVENT_ID_LAST || args->eventID < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unsupported event ID %d"), args->eventID);
         goto cleanup;
     }

-    callbackID = priv->networkEventCallbackID[args->eventID];
+    for (i = 0; i < priv->nnetworkEventCallbacks; i++) {
+        if (priv->networkEventCallbacks[i]->eventID == args->eventID) {
+            callbackID = priv->networkEventCallbacks[i]->callbackID;
+            break;
+        }
+    }
     if (callbackID < 0) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, _("network event %d not registered"), args->eventID);
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("network event %d not registered"), args->eventID);
         goto cleanup;
     }

     if (virConnectNetworkEventDeregisterAny(priv->conn, callbackID) < 0)
         goto cleanup;

-    priv->networkEventCallbackID[args->eventID] = -1;
+    VIR_DELETE_ELEMENT(priv->networkEventCallbacks, i,
+                       priv->nnetworkEventCallbacks);

     rv = 0;

-- 
1.8.4.2


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