4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: David Ahern dsa@cumulusnetworks.com
[ Upstream commit 7bb387c5ab12aeac3d5eea28686489ff46b53ca9 ]
IP_MULTICAST_IF fails if sk_bound_dev_if is already set and the new index does not match it. e.g.,
ntpd[15381]: setsockopt IP_MULTICAST_IF 192.168.1.23 fails: Invalid argument
Relax the check in setsockopt to allow setting mc_index to an L3 slave if sk_bound_dev_if points to an L3 master.
Make a similar change for IPv6. In this case change the device lookup to take the rcu_read_lock avoiding a refcnt. The rcu lock is also needed for the lookup of a potential L3 master device.
This really only silences a setsockopt failure since uses of mc_index are secondary to sk_bound_dev_if if it is set. In both cases, if either index is an L3 slave or master, lookups are directed to the same FIB table so relaxing the check at setsockopt time causes no harm.
Patch is based on a suggested change by Darwin for a problem noted in their code base.
Suggested-by: Darwin Dingel darwin.dingel@alliedtelesis.co.nz Signed-off-by: David Ahern dsa@cumulusnetworks.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/ip_sockglue.c | 7 ++++++- net/ipv6/ipv6_sockglue.c | 16 ++++++++++++---- 2 files changed, 18 insertions(+), 5 deletions(-)
--- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -808,6 +808,7 @@ static int do_ip_setsockopt(struct sock { struct ip_mreqn mreq; struct net_device *dev = NULL; + int midx;
if (sk->sk_type == SOCK_STREAM) goto e_inval; @@ -852,11 +853,15 @@ static int do_ip_setsockopt(struct sock err = -EADDRNOTAVAIL; if (!dev) break; + + midx = l3mdev_master_ifindex(dev); + dev_put(dev);
err = -EINVAL; if (sk->sk_bound_dev_if && - mreq.imr_ifindex != sk->sk_bound_dev_if) + mreq.imr_ifindex != sk->sk_bound_dev_if && + (!midx || midx != sk->sk_bound_dev_if)) break;
inet->mc_index = mreq.imr_ifindex; --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -583,16 +583,24 @@ done:
if (val) { struct net_device *dev; + int midx;
- if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != val) - goto e_inval; + rcu_read_lock();
- dev = dev_get_by_index(net, val); + dev = dev_get_by_index_rcu(net, val); if (!dev) { + rcu_read_unlock(); retv = -ENODEV; break; } - dev_put(dev); + midx = l3mdev_master_ifindex_rcu(dev); + + rcu_read_unlock(); + + if (sk->sk_bound_dev_if && + sk->sk_bound_dev_if != val && + (!midx || midx != sk->sk_bound_dev_if)) + goto e_inval; } np->mcast_oif = val; retv = 0;