From: Tomasz Dzieciol <tomasz.dziec...@nokia.com>
Fix an issue where is_garp variable is not set when arp_accept option is
disabled for a net device. There might be a situation where gratuitous ARP
will be ignored when an existing neighbour is updated in a time smaller
than LOCKTIME (for example by a timer - transition between states).
Signed-off-by: Tomasz Dzieciol <tomasz.dziec...@nokia.com>
---
net/ipv4/arp.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 51b27ae..9fd23c9 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -641,6 +641,13 @@ void arp_xmit(struct sk_buff *skb)
}
EXPORT_SYMBOL(arp_xmit);
+static inline bool arp_is_gratuitous(unsigned int addr_type,
+ int op, __be32 sip, __be32 tip)
+{
+ return op == ARPOP_REQUEST && tip == sip &&
+ addr_type == RTN_UNICAST;
+}
+
/*
* Process an arp request.
*/
@@ -836,19 +843,30 @@ static int arp_process(struct net *net, struct sock *sk,
struct sk_buff *skb)
n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
if (IN_DEV_ARP_ACCEPT(in_dev)) {
- unsigned int addr_type = inet_addr_type_dev_table(net, dev,
sip);
+ unsigned int addr_type = inet_addr_type_dev_table(net,
+ dev, sip);
/* Unsolicited ARP is not accepted by default.
It is possible, that this option should be enabled for some
devices (strip is candidate)
*/
- is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip &&
- addr_type == RTN_UNICAST;
+ is_garp = arp_is_gratuitous(addr_type, ntohs(arp->ar_op),
+ sip, tip);
if (!n &&
((arp->ar_op == htons(ARPOP_REPLY) &&
addr_type == RTN_UNICAST) || is_garp))
n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
+ } else if (n) {
+ unsigned int addr_type = inet_addr_type_dev_table(net,
+ dev, sip);
+
+ /* If the ARP table already contains the IP address of the
+ gratuitous arp frame, the arp table will be updated
+ regardless if this setting is on or off.
+ */
+ is_garp = arp_is_gratuitous(addr_type, ntohs(arp->ar_op),
+ sip, tip);
}
if (n) {
--
2.5.0
