[PATCH 4.4 21/93] ipvs: fix bind to link-local mcast IPv6 address in backup

From: Greg Kroah-Hartman
Date: Thu Oct 06 2016 - 05:22:09 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Quentin Armitage <quentin@xxxxxxxxxxxxxxx>

commit 3777ed688fba82d0bd43f9fc1ebbc6abe788576d upstream.

When using HEAD from
the command:
ipvsadm --start-daemon backup --mcast-interface eth0.60 \
--mcast-group ff02::1:81
fails with the error message:
Argument list too long

whereas both:
ipvsadm --start-daemon master --mcast-interface eth0.60 \
--mcast-group ff02::1:81
ipvsadm --start-daemon backup --mcast-interface eth0.60 \
are successful.

The error message "Argument list too long" isn't helpful. The error occurs
because an IPv6 address is given in backup mode.

The error is in make_receive_sock() in net/netfilter/ipvs/ip_vs_sync.c,
since it fails to set the interface on the address or the socket before
calling inet6_bind() (via sock->ops->bind), where the test
'if (!sk->sk_bound_dev_if)' failed.

Setting sock->sk->sk_bound_dev_if on the socket before calling
inet6_bind() resolves the issue.

Fixes: d33288172e72 ("ipvs: add more mcast parameters for the sync daemon")
Signed-off-by: Quentin Armitage <quentin@xxxxxxxxxxxxxxx>
Acked-by: Julian Anastasov <ja@xxxxxx>
Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

net/netfilter/ipvs/ip_vs_sync.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/netfilter/ipvs/ip_vs_sync.c
+++ b/net/netfilter/ipvs/ip_vs_sync.c
@@ -1545,7 +1545,8 @@ error:
* Set up receiving multicast socket over UDP
-static struct socket *make_receive_sock(struct netns_ipvs *ipvs, int id)
+static struct socket *make_receive_sock(struct netns_ipvs *ipvs, int id,
+ int ifindex)
/* multicast addr */
union ipvs_sockaddr mcast_addr;
@@ -1566,6 +1567,7 @@ static struct socket *make_receive_sock(
set_sock_size(sock->sk, 0, result);

get_mcast_sockaddr(&mcast_addr, &salen, &ipvs->bcfg, id);
+ sock->sk->sk_bound_dev_if = ifindex;
result = sock->ops->bind(sock, (struct sockaddr *)&mcast_addr, salen);
if (result < 0) {
pr_err("Error binding to the multicast addr\n");
@@ -1868,7 +1870,7 @@ int start_sync_thread(struct netns_ipvs
if (state == IP_VS_STATE_MASTER)
sock = make_send_sock(ipvs, id);
- sock = make_receive_sock(ipvs, id);
+ sock = make_receive_sock(ipvs, id, dev->ifindex);
if (IS_ERR(sock)) {
result = PTR_ERR(sock);
goto outtinfo;