From: Hangbin Liu liuhangbin@gmail.com
[ Upstream commit f17f7648a49aa6728649ddf79bdbcac4f1970ce4 ]
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 jishi@redhat.com Signed-off-by: Hangbin Liu liuhangbin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/addrconf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -995,7 +995,8 @@ ipv6_add_addr(struct inet6_dev *idev, st 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) && addr_type & IPV6_ADDR_LOOPBACK)) return ERR_PTR(-EADDRNOTAVAIL);