netdev - [PATCH net-next] ipv4: Allow sending multicast packets on specific i/f using VRF socket

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Date:   Mon,  1 Oct 2018 09:40:23 +0100
From:   Mike Manning <mmanning@...tta.att-mail.com>
To:     netdev@...r.kernel.org
Cc:     Robert Shearman <rshearma@...tta.att-mail.com>
Subject: [PATCH net-next] ipv4: Allow sending multicast packets on specific i/f using VRF socket

From: Robert Shearman <rshearma@...tta.att-mail.com>

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@...tta.att-mail.com>
Signed-off-by: Mike Manning <mmanning@...tta.att-mail.com>
---
 net/ipv4/datagram.c | 2 +-
 net/ipv4/ping.c     | 2 +-
 net/ipv4/raw.c      | 2 +-
 net/ipv4/udp.c      | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index f915abff1350..300921417f89 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 8d7aaf118a30..7ccb5f87f70b 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 33df4d76db2d..8ca3eb06ba04 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 f4e35b2ff8b8..3386b3b0218c 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;
-- 
2.11.0