Re: [PATCH v4 net] ipvs: fix bind to link-local mcast IPv6 address in backup

[Julian Anastasov <ja@ssi.bg>]

	Hello,

On Thu, 16 Jun 2016, Quentin Armitage wrote:

> When using HEAD from
> https://git.kernel.org/cgit/utils/kernel/ipvsadm/ipvsadm.git/,
> 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
> and:
> ipvsadm --start-daemon backup --mcast-interface eth0.60 \
>     --mcast-group 224.0.0.81
> 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@armitage.org.uk>

	Looks good to me, thanks!

Acked-by: Julian Anastasov <ja@ssi.bg>

	Simon, please apply to ipvs tree. Patch compiles
also on stable 4.4.13, 4.5.7 and 4.6.2, so no need for
special versions. The ack is also for the other 3 patches
from v4 (for ipvs-next) but they depend on this patch.

> ---
>  net/netfilter/ipvs/ip_vs_sync.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
> index 803001a..1b07578 100644
> --- 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(struct netns_ipvs *ipvs, int id)
>  		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 *ipvs, struct ipvs_sync_daemon_cfg *c,
>  		if (state == IP_VS_STATE_MASTER)
>  			sock = make_send_sock(ipvs, id);
>  		else
> -			sock = make_receive_sock(ipvs, id);
> +			sock = make_receive_sock(ipvs, id, dev->ifindex);
>  		if (IS_ERR(sock)) {
>  			result = PTR_ERR(sock);
>  			goto outtinfo;
> -- 
> 1.7.7.6

Regards

--
Julian Anastasov <ja@ssi.bg>