From f17f7648a49aa6728649ddf79bdbcac4f1970ce4 Mon Sep 17 00:00:00 2001 From: Hangbin Liu Date: Tue, 20 Aug 2019 10:19:47 +0800 Subject: [PATCH] ipv6/addrconf: allow adding multicast addr if IFA_F_MCAUTOJOIN is set 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 Fixes: 93a714d6b53d ("multicast: Extend ip address command to enable multicast group join/leave on") Reported-by: Jianlin Shi Signed-off-by: Hangbin Liu Signed-off-by: David S. Miller --- net/ipv6/addrconf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index dc73888c7859..ced995f3fec4 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -1045,7 +1045,8 @@ ipv6_add_addr(struct inet6_dev *idev, struct ifa6_config *cfg, int err = 0; if (addr_type == IPV6_ADDR_ANY || - addr_type & IPV6_ADDR_MULTICAST || + (addr_type & IPV6_ADDR_MULTICAST && + !(cfg->ifa_flags & IFA_F_MCAUTOJOIN)) || (!(idev->dev->flags & IFF_LOOPBACK) && !netif_is_l3_master(idev->dev) && addr_type & IPV6_ADDR_LOOPBACK)) -- 2.30.2