Clean all tables before applying 'basic' rules

The functions invoked by the IP address learning thread
that apply some basic filtering rules did not clean up
any previous filtering rules that may still be there
(due to a libvirt restart for example). With the
patch below all the rules are cleaned up first.

Also, I am introducing a function to drop all traffic
in case the IP address learning thread could not apply
the rules.

src/conf/nwfilter_conf.h

@@ -521,6 +521,8 @@ typedef int (*virNWFilterApplyDHCPOnlyRules)(const char *ifname,
 
 typedef int (*virNWFilterRemoveBasicRules)(const char *ifname);
 
+typedef int (*virNWFilterDropAllRules)(const char *ifname);
+
 enum techDrvFlags {
     TECHDRV_FLAG_INITIALIZED = (1 << 0),
 };
@@ -544,6 +546,7 @@ struct _virNWFilterTechDriver {
     virNWFilterCanApplyBasicRules canApplyBasicRules;
     virNWFilterApplyBasicRules applyBasicRules;
     virNWFilterApplyDHCPOnlyRules applyDHCPOnlyRules;
+    virNWFilterDropAllRules applyDropAllRules;
     virNWFilterRemoveBasicRules removeBasicRules;
 };
 

src/nwfilter/nwfilter_ebiptables_driver.c

@@ -102,6 +102,7 @@ static const char *m_physdev_out_str = "-m physdev " PHYSDEV_OUT;
 static int ebtablesRemoveBasicRules(const char *ifname);
 static int ebiptablesDriverInit(void);
 static void ebiptablesDriverShutdown(void);
+static int ebtablesCleanAll(const char *ifname);
 
 
 struct ushort_map {
@@ -2679,12 +2680,7 @@ ebtablesApplyBasicRules(const char *ifname,
 
     virFormatMacAddr(macaddr, macaddr_str);
 
-    ebtablesUnlinkTmpRootChain(&buf, 1, ifname);
+    ebtablesCleanAll(ifname);
-    ebtablesUnlinkTmpRootChain(&buf, 0, ifname);
-    ebtablesRemoveTmpSubChains(&buf, ifname);
-    ebtablesRemoveTmpRootChain(&buf, 1, ifname);
-    ebtablesRemoveTmpRootChain(&buf, 0, ifname);
-    ebiptablesExecCLI(&buf, &cli_status);
 
     ebtablesCreateTmpRootChain(&buf, 1, ifname, 1);
 
@@ -2723,6 +2719,7 @@ ebtablesApplyBasicRules(const char *ifname,
                       CMD_STOPONERR(1));
 
     ebtablesLinkTmpRootChain(&buf, 1, ifname, 1);
+    ebtablesRenameTmpRootChain(&buf, 1, ifname);
 
     if (ebiptablesExecCLI(&buf, &cli_status) || cli_status != 0)
         goto tear_down_tmpebchains;
@@ -2730,7 +2727,7 @@ ebtablesApplyBasicRules(const char *ifname,
     return 0;
 
 tear_down_tmpebchains:
-    ebtablesRemoveBasicRules(ifname);
+    ebtablesCleanAll(ifname);
 
     virNWFilterReportError(VIR_ERR_BUILD_FIREWALL,
                            "%s",
@@ -2782,12 +2779,7 @@ ebtablesApplyDHCPOnlyRules(const char *ifname,
 
     virFormatMacAddr(macaddr, macaddr_str);
 
-    ebtablesUnlinkTmpRootChain(&buf, 1, ifname);
+    ebtablesCleanAll(ifname);
-    ebtablesUnlinkTmpRootChain(&buf, 0, ifname);
-    ebtablesRemoveTmpSubChains(&buf, ifname);
-    ebtablesRemoveTmpRootChain(&buf, 1, ifname);
-    ebtablesRemoveTmpRootChain(&buf, 0, ifname);
-    ebiptablesExecCLI(&buf, &cli_status);
 
     ebtablesCreateTmpRootChain(&buf, 1, ifname, 1);
     ebtablesCreateTmpRootChain(&buf, 0, ifname, 1);
@@ -2842,6 +2834,8 @@ ebtablesApplyDHCPOnlyRules(const char *ifname,
 
     ebtablesLinkTmpRootChain(&buf, 1, ifname, 1);
     ebtablesLinkTmpRootChain(&buf, 0, ifname, 1);
+    ebtablesRenameTmpRootChain(&buf, 1, ifname);
+    ebtablesRenameTmpRootChain(&buf, 0, ifname);
 
     if (ebiptablesExecCLI(&buf, &cli_status) || cli_status != 0)
         goto tear_down_tmpebchains;
@@ -2851,7 +2845,7 @@ ebtablesApplyDHCPOnlyRules(const char *ifname,
     return 0;
 
 tear_down_tmpebchains:
-    ebtablesRemoveBasicRules(ifname);
+    ebtablesCleanAll(ifname);
 
     virNWFilterReportError(VIR_ERR_BUILD_FIREWALL,
                            "%s",
@@ -2863,8 +2857,83 @@ tear_down_tmpebchains:
 }
 
 
+/**
+ * ebtablesApplyDropAllRules
+ *
+ * @ifname: name of the backend-interface to which to apply the rules
+ *
+ * Returns 0 on success, 1 on failure with the rules removed
+ *
+ * Apply filtering rules so that the VM cannot receive or send traffic.
+ */
+static int
+ebtablesApplyDropAllRules(const char *ifname)
+{
+    virBuffer buf = VIR_BUFFER_INITIALIZER;
+    int cli_status;
+    char chain_in [MAX_CHAINNAME_LENGTH],
+         chain_out[MAX_CHAINNAME_LENGTH];
+
+    if (!ebtables_cmd_path) {
+        virNWFilterReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                               _("cannot create rules since ebtables tool is "
+                                 "missing."));
+        return 1;
+    }
+
+    ebtablesCleanAll(ifname);
+
+    ebtablesCreateTmpRootChain(&buf, 1, ifname, 1);
+    ebtablesCreateTmpRootChain(&buf, 0, ifname, 1);
+
+    PRINT_ROOT_CHAIN(chain_in , CHAINPREFIX_HOST_IN_TEMP , ifname);
+    PRINT_ROOT_CHAIN(chain_out, CHAINPREFIX_HOST_OUT_TEMP, ifname);
+
+    virBufferVSprintf(&buf,
+                      CMD_DEF("%s -t %s -A %s -j DROP") CMD_SEPARATOR
+                      CMD_EXEC
+                      "%s",
+
+                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE, chain_in,
+                      CMD_STOPONERR(1));
+
+    virBufferVSprintf(&buf,
+                      CMD_DEF("%s -t %s -A %s -j DROP") CMD_SEPARATOR
+                      CMD_EXEC
+                      "%s",
+
+                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE, chain_out,
+                      CMD_STOPONERR(1));
+
+    ebtablesLinkTmpRootChain(&buf, 1, ifname, 1);
+    ebtablesLinkTmpRootChain(&buf, 0, ifname, 1);
+    ebtablesRenameTmpRootChain(&buf, 1, ifname);
+    ebtablesRenameTmpRootChain(&buf, 0, ifname);
+
+    if (ebiptablesExecCLI(&buf, &cli_status) || cli_status != 0)
+        goto tear_down_tmpebchains;
+
+    return 0;
+
+tear_down_tmpebchains:
+    ebtablesCleanAll(ifname);
+
+    virNWFilterReportError(VIR_ERR_BUILD_FIREWALL,
+                           "%s",
+                           _("Some rules could not be created."));
+
+    return 1;
+}
+
+
 static int
 ebtablesRemoveBasicRules(const char *ifname)
+{
+    return ebtablesCleanAll(ifname);
+}
+
+
+static int ebtablesCleanAll(const char *ifname)
 {
     virBuffer buf = VIR_BUFFER_INITIALIZER;
     int cli_status;
@@ -2872,6 +2941,12 @@ ebtablesRemoveBasicRules(const char *ifname)
     if (!ebtables_cmd_path)
         return 0;
 
+    ebtablesUnlinkRootChain(&buf, 1, ifname);
+    ebtablesUnlinkRootChain(&buf, 0, ifname);
+    ebtablesRemoveSubChains(&buf, ifname);
+    ebtablesRemoveRootChain(&buf, 1, ifname);
+    ebtablesRemoveRootChain(&buf, 0, ifname);
+
     ebtablesUnlinkTmpRootChain(&buf, 1, ifname);
     ebtablesUnlinkTmpRootChain(&buf, 0, ifname);
     ebtablesRemoveTmpSubChains(&buf, ifname);
@@ -3265,6 +3340,7 @@ virNWFilterTechDriver ebiptables_driver = {
     .canApplyBasicRules  = ebiptablesCanApplyBasicRules,
     .applyBasicRules     = ebtablesApplyBasicRules,
     .applyDHCPOnlyRules  = ebtablesApplyDHCPOnlyRules,
+    .applyDropAllRules   = ebtablesApplyDropAllRules,
     .removeBasicRules    = ebtablesRemoveBasicRules,
 };
 

src/nwfilter/nwfilter_learnipaddr.c

@@ -598,8 +598,6 @@ learnIPAddressThread(void *arg)
     if (handle)
         pcap_close(handle);
 
-    techdriver->removeBasicRules(req->ifname);
-
     if (req->status == 0) {
         int ret;
         char inetaddr[INET_ADDRSTRLEN];
@@ -624,6 +622,8 @@ learnIPAddressThread(void *arg)
                                  _("encountered an error on interface %s "
                                    "index %d"),
                                  req->ifname, req->ifindex);
+
+        techdriver->applyDropAllRules(req->ifname);
     }
 
     memset(&req->thread, 0x0, sizeof(req->thread));

src/nwfilter/nwfilter_learnipaddr.h

@@ -60,7 +60,7 @@ int virNWFilterLearnIPAddress(virNWFilterTechDriverPtr techdriver,
                               enum howDetect howDetect);
 
 virNWFilterIPAddrLearnReqPtr virNWFilterLookupLearnReq(int ifindex);
-
+int virNWFilterTerminateLearnReq(const char *ifname);
 
 void virNWFilterDelIpAddrForIfname(const char *ifname);
 const char *virNWFilterGetIpAddrForIfname(const char *ifname);