Make filter creation in root table more flexible

Use the previously introduced chain priorities to sort the chains for access
from an interface's 'root' table and have them created in the proper order.
This gets rid of a lot of code that was previously creating the chains in a 
more hardcoded way.

To determine what protocol a filter is used for evaluation do prefix-
matching, i.e., the filter 'arp' is used to filter for the 'arp' protocol,
'ipv4' for the 'ipv4' protocol and 'arp-xyz' will also be used to filter
for the 'arp' protocol following the prefix 'arp' in its name.
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>

src/nwfilter/nwfilter_ebiptables_driver.c

@@ -140,6 +140,11 @@ enum l3_proto_idx {
 
 #define USHORTMAP_ENTRY_IDX(IDX, ATT, VAL) [IDX] = { .attr = ATT, .val = VAL }
 
+/* A lookup table for translating ethernet protocol IDs to human readable
+ * strings. None of the human readable strings must be found as a prefix
+ * in another entry here (example 'ab' would be found in 'abc') to allow
+ * for prefix matching.
+ */
 static const struct ushort_map l3_protocols[] = {
     USHORTMAP_ENTRY_IDX(L3_PROTO_IPV4_IDX, ETHERTYPE_IP    , "ipv4"),
     USHORTMAP_ENTRY_IDX(L3_PROTO_IPV6_IDX, ETHERTYPE_IPV6  , "ipv6"),
@@ -2662,6 +2667,7 @@ ebtablesCreateTmpSubChain(virBufferPtr buf,
                           int incoming,
                           const char *ifname,
                           enum l3_proto_idx protoidx,
+                          const char *filtername,
                           int stopOnError)
 {
     char rootchain[MAX_CHAINNAME_LENGTH], chain[MAX_CHAINNAME_LENGTH];
@@ -2669,7 +2675,8 @@ ebtablesCreateTmpSubChain(virBufferPtr buf,
                                   : CHAINPREFIX_HOST_OUT_TEMP;
 
     PRINT_ROOT_CHAIN(rootchain, chainPrefix, ifname);
-    PRINT_CHAIN(chain, chainPrefix, ifname, l3_protocols[protoidx].val);
+    PRINT_CHAIN(chain, chainPrefix, ifname,
+                (filtername) ? filtername : l3_protocols[protoidx].val);
 
     virBufferAsprintf(buf,
                       CMD_DEF("%s -t %s -N %s") CMD_SEPARATOR
@@ -3176,6 +3183,14 @@ ebiptablesRuleOrderSort(const void *a, const void *b)
     return ((*insta)->priority - (*instb)->priority);
 }
 
+static int
+ebiptablesFilterOrderSort(const virHashKeyValuePairPtr a,
+                          const virHashKeyValuePairPtr b)
+{
+    /* elements' values has been limited to range [-1000, 1000] */
+    return *(virNWFilterChainPriority *)a->value -
+           *(virNWFilterChainPriority *)b->value;
+}
 
 static void
 iptablesCheckBridgeNFCallEnabled(bool isIPv6)
@@ -3215,6 +3230,54 @@ iptablesCheckBridgeNFCallEnabled(bool isIPv6)
     }
 }
 
+/*
+ * Given a filtername determine the protocol it is used for evaluating
+ * We do prefix-matching to determine the protocol.
+ */
+static enum l3_proto_idx
+ebtablesGetProtoIdxByFiltername(const char *filtername)
+{
+    enum l3_proto_idx idx;
+
+    for (idx = 0; idx < L3_PROTO_LAST_IDX; idx++) {
+        if (STRPREFIX(filtername, l3_protocols[idx].val)) {
+            return idx;
+        }
+    }
+
+    return -1;
+}
+
+static int
+ebtablesCreateTmpRootAndSubChains(virBufferPtr buf,
+                                  const char *ifname,
+                                  virHashTablePtr chains, int direction)
+{
+    int rc = 0, i;
+    virHashKeyValuePairPtr filter_names;
+
+    if (ebtablesCreateTmpRootChain(buf, direction, ifname, 1) < 0)
+        return -1;
+
+    filter_names = virHashGetItems(chains,
+                                   ebiptablesFilterOrderSort);
+    if (filter_names == NULL)
+        return -1;
+
+    for (i = 0; filter_names[i].key; i++) {
+        enum l3_proto_idx idx = ebtablesGetProtoIdxByFiltername(
+                                  filter_names[i].key);
+        if ((int)idx < 0)
+            continue;
+        rc = ebtablesCreateTmpSubChain(buf, direction, ifname, idx,
+                                       filter_names[i].key, 1);
+        if (rc < 0)
+            break;
+    }
+
+    VIR_FREE(filter_names);
+    return rc;
+}
 
 static int
 ebiptablesApplyNewRules(virConnectPtr conn ATTRIBUTE_UNUSED,
@@ -3225,24 +3288,43 @@ ebiptablesApplyNewRules(virConnectPtr conn ATTRIBUTE_UNUSED,
     int i;
     int cli_status;
     ebiptablesRuleInstPtr *inst = (ebiptablesRuleInstPtr *)_inst;
-    int chains_in = 0, chains_out = 0;
     virBuffer buf = VIR_BUFFER_INITIALIZER;
+    virHashTablePtr chains_in_set  = virHashCreate(10, NULL);
+    virHashTablePtr chains_out_set = virHashCreate(10, NULL);
     bool haveIptables = false;
     bool haveIp6tables = false;
 
+    if (!chains_in_set || !chains_out_set) {
+        virReportOOMError();
+        goto exit_free_sets;
+    }
+
     if (nruleInstances > 1 && inst)
         qsort(inst, nruleInstances, sizeof(inst[0]), ebiptablesRuleOrderSort);
 
+    /* scan the rules to see which chains need to be created */
     for (i = 0; i < nruleInstances; i++) {
         sa_assert (inst);
         if (inst[i]->ruleType == RT_EBTABLES) {
-            if (inst[i]->chainprefix == CHAINPREFIX_HOST_IN_TEMP)
-                chains_in  |= (1 << inst[i]->neededProtocolChain);
-            else
-                chains_out |= (1 << inst[i]->neededProtocolChain);
+            const char *name = virNWFilterChainSuffixTypeToString(
+                                      inst[i]->neededProtocolChain);
+            if (inst[i]->chainprefix == CHAINPREFIX_HOST_IN_TEMP) {
+                if (virHashUpdateEntry(chains_in_set, name,
+                                       &inst[i]->chainPriority)) {
+                    virReportOOMError();
+                    goto exit_free_sets;
+                }
+            } else {
+                if (virHashUpdateEntry(chains_out_set, name,
+                                       &inst[i]->chainPriority)) {
+                    virReportOOMError();
+                    goto exit_free_sets;
+                }
+            }
         }
     }
 
+    /* cleanup whatever may exist */
     if (ebtables_cmd_path) {
         ebtablesUnlinkTmpRootChain(&buf, 1, ifname);
         ebtablesUnlinkTmpRootChain(&buf, 0, ifname);
@@ -3252,30 +3334,11 @@ ebiptablesApplyNewRules(virConnectPtr conn ATTRIBUTE_UNUSED,
         ebiptablesExecCLI(&buf, &cli_status);
     }
 
-    if (chains_in != 0)
-        ebtablesCreateTmpRootChain(&buf, 1, ifname, 1);
-    if (chains_out != 0)
-        ebtablesCreateTmpRootChain(&buf, 0, ifname, 1);
-
-    if (chains_in  & (1 << VIR_NWFILTER_CHAINSUFFIX_IPv4))
-        ebtablesCreateTmpSubChain(&buf, 1, ifname, L3_PROTO_IPV4_IDX, 1);
-    if (chains_out & (1 << VIR_NWFILTER_CHAINSUFFIX_IPv4))
-        ebtablesCreateTmpSubChain(&buf, 0, ifname, L3_PROTO_IPV4_IDX, 1);
-
-    if (chains_in  & (1 << VIR_NWFILTER_CHAINSUFFIX_IPv6))
-        ebtablesCreateTmpSubChain(&buf, 1, ifname, L3_PROTO_IPV6_IDX, 1);
-    if (chains_out & (1 << VIR_NWFILTER_CHAINSUFFIX_IPv6))
-        ebtablesCreateTmpSubChain(&buf, 0, ifname, L3_PROTO_IPV6_IDX, 1);
-
-    /* keep arp,rarp as last */
-    if (chains_in  & (1 << VIR_NWFILTER_CHAINSUFFIX_ARP))
-        ebtablesCreateTmpSubChain(&buf, 1, ifname, L3_PROTO_ARP_IDX, 1);
-    if (chains_out & (1 << VIR_NWFILTER_CHAINSUFFIX_ARP))
-        ebtablesCreateTmpSubChain(&buf, 0, ifname, L3_PROTO_ARP_IDX, 1);
-    if (chains_in  & (1 << VIR_NWFILTER_CHAINSUFFIX_RARP))
-        ebtablesCreateTmpSubChain(&buf, 1, ifname, L3_PROTO_RARP_IDX, 1);
-    if (chains_out & (1 << VIR_NWFILTER_CHAINSUFFIX_RARP))
-        ebtablesCreateTmpSubChain(&buf, 0, ifname, L3_PROTO_RARP_IDX, 1);
+    /* create needed chains */
+    if (ebtablesCreateTmpRootAndSubChains(&buf, ifname, chains_in_set , 1) ||
+        ebtablesCreateTmpRootAndSubChains(&buf, ifname, chains_out_set, 0)) {
+        goto tear_down_tmpebchains;
+    }
 
     if (ebiptablesExecCLI(&buf, &cli_status) || cli_status != 0)
         goto tear_down_tmpebchains;
@@ -3365,14 +3428,17 @@ ebiptablesApplyNewRules(virConnectPtr conn ATTRIBUTE_UNUSED,
         iptablesCheckBridgeNFCallEnabled(true);
     }
 
-    if (chains_in != 0)
+    if (virHashSize(chains_in_set) != 0)
         ebtablesLinkTmpRootChain(&buf, 1, ifname, 1);
-    if (chains_out != 0)
+    if (virHashSize(chains_out_set) != 0)
         ebtablesLinkTmpRootChain(&buf, 0, ifname, 1);
 
     if (ebiptablesExecCLI(&buf, &cli_status) || cli_status != 0)
         goto tear_down_ebsubchains_and_unlink;
 
+    virHashFree(chains_in_set);
+    virHashFree(chains_out_set);
+
     return 0;
 
 tear_down_ebsubchains_and_unlink:
@@ -3407,6 +3473,10 @@ tear_down_tmpebchains:
                              "interface %s."),
                            ifname);
 
+exit_free_sets:
+    virHashFree(chains_in_set);
+    virHashFree(chains_out_set);
+
     return 1;
 }