4:44 p.m.
Changes from V1 to V2 of this patch
- I had reversed the logic thinking that icmp type 0 is a echo
request,but it's reply -- needed to reverse the logic
- Found that ebtables takes the --ip-tos argument only as a hex number
This patch enables the skipping of some of the ICMP traffic rules on the
iptables level under certain circumstances so that the following filter
properly enables unidirectional pings:
<filter name='testcase'>
<uuid>d6b1a2af-def6-2898-9f8d-4a74e3c39558</uuid>
<!-- allow incoming ICMP Echo Request -->
<rule action='accept' direction='in' priority='500'>
<icmp type='8'/>
</rule>
<!-- allow outgoing ICMP Echo Reply -->
<rule action='accept' direction='out' priority='500'>
<icmp type='0'/>
</rule>
<!-- drop all other ICMP traffic -->
<rule action='drop' direction='inout' priority='600'>
<icmp/>
</rule>
</filter>
Signed-off-by: Stefan Berger <stefanb(a)us.ibm.com>
---
src/nwfilter/nwfilter_ebiptables_driver.c | 108
+++++++++++++++++-------------
1 file changed, 64 insertions(+), 44 deletions(-)
Index: libvirt-acl/src/nwfilter/nwfilter_ebiptables_driver.c
===================================================================
--- libvirt-acl.orig/src/nwfilter/nwfilter_ebiptables_driver.c
+++ libvirt-acl/src/nwfilter/nwfilter_ebiptables_driver.c
@@ -1022,6 +1022,12 @@ err_exit:
* @ifname : The name of the interface to apply the rule to
* @vars : A map containing the variables to resolve
* @res : The data structure to store the result(s) into
+ * @match : optional string for state match
+ * @accept_target : where to jump to on accepted traffic, i.e.,
"RETURN"
+ * "ACCEPT"
+ * @isIPv6 : Whether this is an IPv6 rule
+ * @maySkipICMP : whether this rule may under certain circumstances
skip
+ * the ICMP rule from being created
*
* Convert a single rule into its representation for later
instantiation
*
@@ -1039,7 +1045,8 @@ _iptablesCreateRuleInstance(int directio
virNWFilterRuleInstPtr res,
const char *match,
const char *accept_target,
- bool isIPv6)
+ bool isIPv6,
+ bool maySkipICMP)
{
char chain[MAX_CHAINNAME_LENGTH];
char number[20];
@@ -1265,6 +1272,10 @@ _iptablesCreateRuleInstance(int directio
if (HAS_ENTRY_ITEM(&rule->p.icmpHdrFilter.dataICMPType)) {
const char *parm;
+
+ if (maySkipICMP)
+ goto exit_no_error;
+
if (rule->prtclType == VIR_NWFILTER_RULE_PROTOCOL_ICMP)
parm = "--icmp-type";
else
@@ -1386,6 +1397,10 @@ err_exit:
return -1;
+exit_no_error:
+ virBufferFreeAndReset(&buf);
+
+ return 0;
}
@@ -1401,15 +1416,19 @@ iptablesCreateRuleInstance(virNWFilterDe
int directionIn = 0;
char chainPrefix[2];
int needState = 1;
+ bool maySkipICMP, inout = false;
if ((rule->tt == VIR_NWFILTER_RULE_DIRECTION_IN) ||
(rule->tt == VIR_NWFILTER_RULE_DIRECTION_INOUT)) {
directionIn = 1;
needState = 0;
+ inout = (rule->tt == VIR_NWFILTER_RULE_DIRECTION_INOUT);
}
chainPrefix[0] = 'F';
+ maySkipICMP = directionIn || inout;
+
chainPrefix[1] = CHAINPREFIX_HOST_IN_TEMP;
rc = _iptablesCreateRuleInstance(directionIn,
chainPrefix,
@@ -1421,10 +1440,14 @@ iptablesCreateRuleInstance(virNWFilterDe
needState ? MATCH_STATE_OUT
: NULL,
"RETURN",
- isIPv6);
+ isIPv6,
+ maySkipICMP);
if (rc)
return rc;
+
+ maySkipICMP = !directionIn || inout;
+
chainPrefix[1] = CHAINPREFIX_HOST_OUT_TEMP;
rc = _iptablesCreateRuleInstance(!directionIn,
chainPrefix,
@@ -1436,10 +1459,13 @@ iptablesCreateRuleInstance(virNWFilterDe
needState ? MATCH_STATE_IN
: NULL,
"ACCEPT",
- isIPv6);
+ isIPv6,
+ maySkipICMP);
if (rc)
return rc;
+ maySkipICMP = directionIn;
+
chainPrefix[0] = 'H';
chainPrefix[1] = CHAINPREFIX_HOST_IN_TEMP;
rc = _iptablesCreateRuleInstance(directionIn,
@@ -1451,9 +1477,8 @@ iptablesCreateRuleInstance(virNWFilterDe
res,
NULL,
"ACCEPT",
- isIPv6);
- if (rc)
- return rc;
+ isIPv6,
+ maySkipICMP);
return rc;
}
@@ -1750,9 +1775,9 @@ ebtablesCreateRuleInstance(char chainPre
}
if (HAS_ENTRY_ITEM(&rule->p.ipHdrFilter.ipHdr.dataDSCP)) {
- if (printDataType(vars,
- number, sizeof(number),
- &rule->p.ipHdrFilter.ipHdr.dataDSCP))
+ if (printDataTypeAsHex(vars,
+ number, sizeof(number),
+
&rule->p.ipHdrFilter.ipHdr.dataDSCP))
goto err_exit;
virBufferVSprintf(&buf,