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Fix libvirt upgrade path when nwfilter is used 

Between revision 65fb9d49 and before this patch, an upgrade of libvirt while
VMs are running and instantiating iptables filtering rules due to nwfilter
rules, may leave stray iptables rules behind when shutting VMs down.
Left-over iptables rules may look like this:

Chain FP-vnet0 (1 references)
target     prot opt source               destination         
DROP       tcp  --  0.0.0.0/0            0.0.0.0/0            tcp spt:122
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           

[...]

Chain libvirt-out (1 references)
target     prot opt source               destination         
FO-vnet0   all  --  0.0.0.0/0            0.0.0.0/0           [goto]  PHYSDEV match --physdev-out vnet0



The reason is that the recent nwfilter code only removed filtering rules in
the libvirt-out chain that contain the --physdev-is-bridged parameter.
Older rules didn't match and were not removed.

Note that the user-defined chain FO-vnet0 could not be removed due to the
reference from the rule in libvirt-out.

Often the work around may be done through

service iptables restart
kill -SIGHUP $(pidof libvirtd)

This patch now also removes older libvirt versions' iptables rules.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
This commit is contained in:
Stefan Berger 2013-02-15 21:33:37 -05:00 committed by Stefan Berger
parent a18452d0d2
commit b7d00de2bd
1 changed files with 22 additions and 0 deletions
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22
src/nwfilter/nwfilter_ebiptables_driver.c
View File

@ -167,16 +167,24 @@ static const char ebiptables_script_set_ifs[] =
#define PHYSDEV_IN "--physdev-in"
#define PHYSDEV_OUT "--physdev-is-bridged --physdev-out"
/*
* Previous versions of libvirt only used --physdev-out.
* To be able to upgrade with running VMs we need to be able to
* remove rules generated by those older versions of libvirt.
*/
#define PHYSDEV_OUT_OLD "--physdev-out"
static const char *m_state_out_str = "-m state --state NEW,ESTABLISHED";
static const char *m_state_in_str = "-m state --state ESTABLISHED";
static const char *m_physdev_in_str = "-m physdev " PHYSDEV_IN;
static const char *m_physdev_out_str = "-m physdev " PHYSDEV_OUT;
static const char *m_physdev_out_old_str = "-m physdev " PHYSDEV_OUT_OLD;
#define MATCH_STATE_OUT m_state_out_str
#define MATCH_STATE_IN m_state_in_str
#define MATCH_PHYSDEV_IN m_physdev_in_str
#define MATCH_PHYSDEV_OUT m_physdev_out_str
#define MATCH_PHYSDEV_OUT_OLD m_physdev_out_old_str
#define COMMENT_VARNAME "comment"
@ -821,6 +829,8 @@ _iptablesUnlinkRootChain(virBufferPtr buf,
: CHAINPREFIX_HOST_OUT;
const char *match = (incoming) ? MATCH_PHYSDEV_IN
: MATCH_PHYSDEV_OUT;
const char *old_match = (incoming) ? NULL
: MATCH_PHYSDEV_OUT_OLD;
PRINT_IPT_ROOT_CHAIN(chain, chainPrefix, ifname);
@ -830,6 +840,18 @@ _iptablesUnlinkRootChain(virBufferPtr buf,
basechain,
match, ifname, chain);
/*
* Previous versions of libvirt may have created a rule
* with the --physdev-is-bridged missing. Remove this one
* as well.
*/
if (old_match)
virBufferAsprintf(buf,
"$IPT -D %s "
"%s %s -g %s" CMD_SEPARATOR,
basechain,
old_match, ifname, chain);
return 0;
}