From: Hangbin Liu <[email protected]>
Date: Tue, 20 Aug 2019 10:19:47 +0800
> In commit 93a714d6b53d ("multicast: Extend ip address command to enable
> multicast group join/leave on") we added a new flag IFA_F_MCAUTOJOIN
> to make user able to add multicast address on ethernet interface.
>
> This works for IPv4, but not for IPv6. See the inet6_addr_add code.
>
> static int inet6_addr_add()
> {
> ...
> if (cfg->ifa_flags & IFA_F_MCAUTOJOIN) {
> ipv6_mc_config(net->ipv6.mc_autojoin_sk, true...)
> }
>
> ifp = ipv6_add_addr(idev, cfg, true, extack); <- always fail with maddr
> if (!IS_ERR(ifp)) {
> ...
> } else if (cfg->ifa_flags & IFA_F_MCAUTOJOIN) {
> ipv6_mc_config(net->ipv6.mc_autojoin_sk, false...)
> }
> }
>
> But in ipv6_add_addr() it will check the address type and reject multicast
> address directly. So this feature is never worked for IPv6.
>
> We should not remove the multicast address check totally in ipv6_add_addr(),
> but could accept multicast address only when IFA_F_MCAUTOJOIN flag supplied.
>
> v2: update commit description
>
> Reported-by: Jianlin Shi <[email protected]>
> Fixes: 93a714d6b53d ("multicast: Extend ip address command to enable
> multicast group join/leave on")
> Signed-off-by: Hangbin Liu <[email protected]>
Applied and queued up for -stable.
