remote: open secondary drivers via remote driver if needed

When the client has a connection to one of the hypervisor specific
daemons (eg virtqemud), the app may still expect to use the secondary
driver APIs (storage, network, etc). None of these will be registered in
the hypervisor daemon, so we must explicitly open a connection to each
of the daemons for the secondary drivers we need.

We don't want to open these secondary driver connections at the same
time as the primary connection is opened though. That would mean that
establishing a connection to virtqemud would immediately trigger
activation of virtnetworkd, virnwfilterd, etc despite that that these
drivers may never be used by the app.

Thus we only open the secondary driver connections at time of first use
by an API call.
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/remote/remote_daemon.h

@@ -70,12 +70,25 @@ struct daemonClientPrivate {
      * called, it will be set back to NULL if that succeeds.
      */
     virConnectPtr conn;
+
+    /* These secondary drivers may point back to 'conn'
+     * in the monolithic daemon setups. Otherwise they
+     * can be NULL and opened on first use, pointing
+     * to remote driver use of an external daemon
+     */
     virConnectPtr interfaceConn;
+    const char *interfaceURI;
     virConnectPtr networkConn;
+    const char *networkURI;
     virConnectPtr nodedevConn;
+    const char *nodedevURI;
     virConnectPtr nwfilterConn;
+    const char *nwfilterURI;
     virConnectPtr secretConn;
+    const char *secretURI;
     virConnectPtr storageConn;
+    const char *storageURI;
+    bool readonly;
 
     daemonClientStreamPtr streams;
 };

src/remote/remote_daemon_dispatch.c

@@ -1941,6 +1941,34 @@ static void remoteClientCloseFunc(virNetServerClientPtr client)
 }
 
 
+static int
+remoteOpenConn(const char *uri,
+               bool readonly,
+               virConnectPtr *conn)
+{
+    VIR_DEBUG("Getting secondary uri=%s readonly=%d conn=%p",
+              NULLSTR(uri), readonly, conn);
+    if (*conn)
+        return 0;
+
+    if (!uri) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("connection not open"));
+        return -1;
+    }
+
+    VIR_DEBUG("Opening driver %s", uri);
+    if (readonly)
+        *conn = virConnectOpenReadOnly(uri);
+    else
+        *conn = virConnectOpen(uri);
+    if (!*conn)
+        return -1;
+    VIR_DEBUG("Opened driver %p", *conn);
+
+    return 0;
+}
+
+
 static virConnectPtr
 remoteGetHypervisorConn(virNetServerClientPtr client)
 {
@@ -1962,10 +1990,10 @@ remoteGetInterfaceConn(virNetServerClientPtr client)
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
 
-    if (!priv->interfaceConn) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("hypervisor connection not open"));
+    if (remoteOpenConn(priv->interfaceURI,
+                       priv->readonly,
+                       &priv->interfaceConn) < 0)
         return NULL;
-    }
 
     return priv->interfaceConn;
 }
@@ -1977,10 +2005,10 @@ remoteGetNetworkConn(virNetServerClientPtr client)
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
 
-    if (!priv->networkConn) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("hypervisor connection not open"));
+    if (remoteOpenConn(priv->networkURI,
+                       priv->readonly,
+                       &priv->networkConn) < 0)
         return NULL;
-    }
 
     return priv->networkConn;
 }
@@ -1992,10 +2020,10 @@ remoteGetNodeDevConn(virNetServerClientPtr client)
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
 
-    if (!priv->nodedevConn) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("hypervisor connection not open"));
+    if (remoteOpenConn(priv->nodedevURI,
+                       priv->readonly,
+                       &priv->nodedevConn) < 0)
         return NULL;
-    }
 
     return priv->nodedevConn;
 }
@@ -2007,10 +2035,10 @@ remoteGetNWFilterConn(virNetServerClientPtr client)
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
 
-    if (!priv->nwfilterConn) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("hypervisor connection not open"));
+    if (remoteOpenConn(priv->nwfilterURI,
+                       priv->readonly,
+                       &priv->nwfilterConn) < 0)
         return NULL;
-    }
 
     return priv->nwfilterConn;
 }
@@ -2022,10 +2050,10 @@ remoteGetSecretConn(virNetServerClientPtr client)
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
 
-    if (!priv->secretConn) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("hypervisor connection not open"));
+    if (remoteOpenConn(priv->secretURI,
+                       priv->readonly,
+                       &priv->secretConn) < 0)
         return NULL;
-    }
 
     return priv->secretConn;
 }
@@ -2037,10 +2065,10 @@ remoteGetStorageConn(virNetServerClientPtr client)
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
 
-    if (!priv->storageConn) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("hypervisor connection not open"));
+    if (remoteOpenConn(priv->storageURI,
+                       priv->readonly,
+                       &priv->storageConn) < 0)
         return NULL;
-    }
 
     return priv->storageConn;
 }
@@ -2077,6 +2105,9 @@ remoteDispatchConnectOpen(virNetServerPtr server ATTRIBUTE_UNUSED,
     unsigned int flags;
     struct daemonClientPrivate *priv = virNetServerClientGetPrivateData(client);
     int rv = -1;
+#ifdef MODULE_NAME
+    const char *type = NULL;
+#endif /* !MODULE_NAME */
 
     VIR_DEBUG("priv=%p conn=%p", priv, priv->conn);
     virMutexLock(&priv->lock);
@@ -2095,20 +2126,94 @@ remoteDispatchConnectOpen(virNetServerPtr server ATTRIBUTE_UNUSED,
     if (virNetServerClientGetReadonly(client))
         flags |= VIR_CONNECT_RO;
 
-    priv->conn =
-        flags & VIR_CONNECT_RO
-        ? virConnectOpenReadOnly(name)
-        : virConnectOpen(name);
+    priv->readonly = flags & VIR_CONNECT_RO;
 
-    if (priv->conn == NULL)
-        goto cleanup;
+    VIR_DEBUG("Opening driver %s", name);
+    if (priv->readonly) {
+        if (!(priv->conn = virConnectOpenReadOnly(name)))
+            goto cleanup;
+    } else {
+        if (!(priv->conn = virConnectOpen(name)))
+            goto cleanup;
+    }
+    VIR_DEBUG("Opened %p", priv->conn);
 
+#ifdef MODULE_NAME
+    /*
+     * For per-driver daemons, we must setup connection URIs
+     * for sub-drivers.
+     */
+    if (!(type = virConnectGetType(priv->conn)))
+        goto cleanup;
+
+    VIR_DEBUG("Primary driver type is '%s'", type);
+    if (STREQ(type, "QEMU") ||
+        STREQ(type, "LIBXL") ||
+        STREQ(type, "LXC") ||
+        STREQ(type, "VBOX") ||
+        STREQ(type, "bhyve") ||
+        STREQ(type, "vz") ||
+        STREQ(type, "Parallels")) {
+        VIR_DEBUG("Hypervisor driver found, setting URIs for secondary drivers");
+        if (getuid() == 0) {
+            priv->interfaceURI = "interface:///system";
+            priv->networkURI = "network:///system";
+            priv->nodedevURI = "nodedev:///system";
+            priv->nwfilterURI = "nwfilter:///system";
+            priv->secretURI = "secret:///system";
+            priv->storageURI = "storage:///system";
+        } else {
+            priv->interfaceURI = "interface:///session";
+            priv->networkURI = "network:///session";
+            priv->nodedevURI = "nodedev:///session";
+            /* No nwfilterURI as this is a root-only driver */
+            priv->secretURI = "secret:///session";
+            priv->storageURI = "storage:///session";
+        }
+    } else if (STREQ(type, "interface")) {
+        VIR_DEBUG("Interface driver found");
+        priv->interfaceConn = virObjectRef(priv->conn);
+    } else if (STREQ(type, "network")) {
+        VIR_DEBUG("Network driver found");
+        priv->networkConn = virObjectRef(priv->conn);
+    } else if (STREQ(type, "nodedev")) {
+        VIR_DEBUG("Nodedev driver found");
+        priv->nodedevConn = virObjectRef(priv->conn);
+    } else if (STREQ(type, "nwfilter")) {
+        VIR_DEBUG("NWFilter driver found");
+        priv->nwfilterConn = virObjectRef(priv->conn);
+    } else if (STREQ(type, "secret")) {
+        VIR_DEBUG("Secret driver found");
+        priv->secretConn = virObjectRef(priv->conn);
+    } else if (STREQ(type, "storage")) {
+        VIR_DEBUG("Storage driver found");
+        priv->storageConn = virObjectRef(priv->conn);
+
+        /* Co-open the secret driver, as apps using the storage driver may well
+         * need access to secrets for storage auth
+         */
+        if (getuid() == 0)
+            priv->secretURI = "secret:///system";
+        else
+            priv->secretURI = "secret:///session";
+    } else {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Unexpected driver type '%s' opened"), type);
+        goto cleanup;
+    }
+#else /* !MODULE_NAME */
+    /*
+     * For libvirtd/virtproxyd one connection handles
+     * all drivers
+     */
+    VIR_DEBUG("Pointing secondary drivers to primary");
     priv->interfaceConn = virObjectRef(priv->conn);
     priv->networkConn = virObjectRef(priv->conn);
     priv->nodedevConn = virObjectRef(priv->conn);
     priv->nwfilterConn = virObjectRef(priv->conn);
     priv->secretConn = virObjectRef(priv->conn);
     priv->storageConn = virObjectRef(priv->conn);
+#endif /* !MODULE_NAME */
 
     /* force update the @readonly attribute which was inherited from the
      * virNetServerService object - this is important for sockets that are RW
@@ -2118,8 +2223,13 @@ remoteDispatchConnectOpen(virNetServerPtr server ATTRIBUTE_UNUSED,
     rv = 0;
 
  cleanup:
-    if (rv < 0)
+    if (rv < 0) {
         virNetMessageSaveError(rerr);
+        if (priv->conn) {
+            virObjectUnref(priv->conn);
+            priv->conn = NULL;
+        }
+    }
     virMutexUnlock(&priv->lock);
     return rv;
 }