All,
Attached is a patch to fix arp_reply when you have multiple possible
routers doing ARP requests to you. Currently arp_reply always replies to the
MAC address that it was given when it starts. However, if you have multiple
routers that can ARP request you, you might respond to the wrong router; in
which case the other router will eventually drop you from it's ARP cache and
stop delivering packets to you. The fix is to always reply to the router that
asked you, not the one you have hard-coded.
I do not have the setup to test this; the customer that does have the
setup has tested the patch and reports that it fixes the problems they were
having.
Signed-off-by: Chris Lalancette <[EMAIL PROTECTED]>
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 3c58846..5833b21 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -331,6 +331,7 @@ static void arp_reply(struct sk_buff *sk
unsigned char *arp_ptr;
int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
__be32 sip, tip;
+ unsigned char *sha;
struct sk_buff *send_skb;
struct netpoll *np = NULL;
@@ -357,9 +358,14 @@ static void arp_reply(struct sk_buff *sk
arp->ar_op != htons(ARPOP_REQUEST))
return;
- arp_ptr = (unsigned char *)(arp+1) + skb->dev->addr_len;
+ arp_ptr = (unsigned char *)(arp+1);
+ /* save the location of the src hw addr */
+ sha = arp_ptr;
+ arp_ptr += skb->dev->addr_len;
memcpy(&sip, arp_ptr, 4);
- arp_ptr += 4 + skb->dev->addr_len;
+ arp_ptr += 4;
+ /* if we actually cared about dst hw addr, it would get copied here */
+ arp_ptr += skb->dev->addr_len;
memcpy(&tip, arp_ptr, 4);
/* Should we ignore arp? */
@@ -382,7 +388,7 @@ static void arp_reply(struct sk_buff *sk
if (np->dev->hard_header &&
np->dev->hard_header(send_skb, skb->dev, ptype,
- np->remote_mac, np->local_mac,
+ sha, np->local_mac,
send_skb->len) < 0) {
kfree_skb(send_skb);
return;
@@ -406,7 +412,7 @@ static void arp_reply(struct sk_buff *sk
arp_ptr += np->dev->addr_len;
memcpy(arp_ptr, &tip, 4);
arp_ptr += 4;
- memcpy(arp_ptr, np->remote_mac, np->dev->addr_len);
+ memcpy(arp_ptr, sha, np->dev->addr_len);
arp_ptr += np->dev->addr_len;
memcpy(arp_ptr, &sip, 4);
