From: Robert Shearman <rshearma@vyatta.att-mail.com>
Date: Mon, 1 Oct 2018 08:40:23 +0000 (+0100)
Subject: ipv4: Allow sending multicast packets on specific i/f using VRF socket
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=854da991733d1b4f60042423875e32be7f8f0421;p=linux.git

ipv4: Allow sending multicast packets on specific i/f using VRF socket

It is useful to be able to use the same socket for listening in a
specific VRF, as for sending multicast packets out of a specific
interface. However, the bound device on the socket currently takes
precedence and results in the packets not being sent.

Relax the condition on overriding the output interface to use for
sending packets out of UDP, raw and ping sockets to allow multicast
packets to be sent using the specified multicast interface.

Signed-off-by: Robert Shearman <rshearma@vyatta.att-mail.com>
Signed-off-by: Mike Manning <mmanning@vyatta.att-mail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index f915abff1350a..300921417f89f 100644
--- a/net/ipv4/datagram.c
+++ b/net/ipv4/datagram.c
@@ -42,7 +42,7 @@ int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
 	oif = sk->sk_bound_dev_if;
 	saddr = inet->inet_saddr;
 	if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
-		if (!oif)
+		if (!oif || netif_index_is_l3_master(sock_net(sk), oif))
 			oif = inet->mc_index;
 		if (!saddr)
 			saddr = inet->mc_addr;
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 8d7aaf118a301..7ccb5f87f70b9 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -779,7 +779,7 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	}
 
 	if (ipv4_is_multicast(daddr)) {
-		if (!ipc.oif)
+		if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))
 			ipc.oif = inet->mc_index;
 		if (!saddr)
 			saddr = inet->mc_addr;
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 33df4d76db2d9..8ca3eb06ba042 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -608,7 +608,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		tos |= RTO_ONLINK;
 
 	if (ipv4_is_multicast(daddr)) {
-		if (!ipc.oif)
+		if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))
 			ipc.oif = inet->mc_index;
 		if (!saddr)
 			saddr = inet->mc_addr;
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 7d69dd6fa7e8c..5fc4beb1c3361 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1042,7 +1042,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	}
 
 	if (ipv4_is_multicast(daddr)) {
-		if (!ipc.oif)
+		if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))
 			ipc.oif = inet->mc_index;
 		if (!saddr)
 			saddr = inet->mc_addr;