>Number: 145300
>Category: kern
>Synopsis: ARP table mapping is not refreshed on a MAC address change
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Apr 02 17:00:13 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator: Boris Astardzhiev
>Release: FreeBSD 8.0
>Organization:
Smartcom Bulgaria AD
>Environment:
FreeBSD boris-fbsd.smartcom.bg 8.0-RELEASE-p2 FreeBSD 8.0-RELEASE-p2 #3: Tue
Mar 30 18:58:50 EEST 2010
[email protected]:/usr/src/sys/i386/compile/KGDB i386
>Description:
On changing a link layer (MAC) address of a network interface that has an
AF_INET address family applied to it the ARP table remains untouched reporting
that the AF_INET address family is still mapped to the previous MAC address. An
ARP table flush does not solve the problem.
>How-To-Repeat:
Here's a walk-through regarding the specified problem.
boris-fbsd# ifconfig em1
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 08:00:27:07:bb:b7
inet 192.168.56.2 netmask 0xffffff00 broadcast 192.168.56.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
boris-fbsd# arp -a -n
? (192.168.56.2) at 08:00:27:07:bb:b7 on em1 permanent [ethernet]
boris-fbsd# ifconfig em1 ether 11:22:33:44:55:66
boris-fbsd# ifconfig em1
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 11:22:33:44:55:66
inet 192.168.56.2 netmask 0xffffff00 broadcast 192.168.56.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
boris-fbsd# arp -a -n
? (192.168.56.2) at 08:00:27:07:bb:b7 on em1 permanent [ethernet]
boris-fbsd# arp -a -d
192.168.56.2 (192.168.56.2) deleted
boris-fbsd# arp -a -n
? (192.168.56.2) at 08:00:27:07:bb:b7 on em1 permanent [ethernet]
boris-fbsd#
As you may have noticed the MAC address reported in the ARP table remains the
old one though it's been changed.
>Fix:
A patch is applied.
Patch attached with submission follows:
--- usr/src/sys/net/if.c 2010-04-02 19:15:39.000000000 +0300
+++ /usr/src/sys/net/if.c 2010-04-02 19:16:57.000000000 +0300
@@ -142,6 +142,11 @@
static void if_attach_internal(struct ifnet *, int);
static void if_detach_internal(struct ifnet *, int);
+#ifdef INET
+/* XXX: better way to grab access to this function? */
+extern void arp_ifscrub(struct ifnet *ifp, uint32_t addr);
+#endif /* INET */
+
#ifdef INET6
/*
* XXX: declare here to avoid to include many inet6 related files..
@@ -3197,8 +3202,14 @@
* the address change.
*/
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
- if (ifa->ifa_addr->sa_family == AF_INET)
+ if (ifa->ifa_addr->sa_family == AF_INET) {
+ struct in_ifaddr *ia = (struct in_ifaddr *)ifa;
+
+ /* Delete previous mappings in the ARP table
+ * first then send a gratuitous ARP */
+ arp_ifscrub(ifp,
(uint32_t)(IA_SIN(ia)->sin_addr.s_addr));
arp_ifinit(ifp, ifa);
+ }
}
#endif
}
>Release-Note:
>Audit-Trail:
>Unformatted:
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