[PATCH net] udp: fix SO_BINDTODEVICE

Damir reported a breakage of SO_BINDTODEVICE for UDP sockets.
In absence of VRF devices, after commit fb74c27735f0 ("net:
ipv4: add second dif to udp socket lookups") the dif mismatch
isn't fatal anymore for UDP socket lookup with non null
sk_bound_dev_if, breaking SO_BINDTODEVICE semantics.

This changeset addresses the issue making the dif match mandatory
again in the above scenario.

Reported-by: Damir Mansurov <redacted>
Fixes: fb74c27735f0 ("net: ipv4: add second dif to udp socket lookups")
Fixes: 1801b570dd2a ("net: ipv6: add second dif to udp socket lookups")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/ipv4/udp.c | 4 ++--
 net/ipv6/udp.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 24b5c59b1c53..c2a292dfd137 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c

@@ -401,9 +401,9 @@ static int compute_score(struct sock *sk, struct net *net,
 		bool dev_match = (sk->sk_bound_dev_if == dif ||
 				  sk->sk_bound_dev_if == sdif);
 
-		if (exact_dif && !dev_match)
+		if (!dev_match)
 			return -1;
-		if (sk->sk_bound_dev_if && dev_match)
+		if (sk->sk_bound_dev_if)
 			score += 4;
 	}
 

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 4ec76a87aeb8..ea0730028e5d 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c

@@ -148,9 +148,9 @@ static int compute_score(struct sock *sk, struct net *net,
 		bool dev_match = (sk->sk_bound_dev_if == dif ||
 				  sk->sk_bound_dev_if == sdif);
 
-		if (exact_dif && !dev_match)
+		if (!dev_match)
 			return -1;
-		if (sk->sk_bound_dev_if && dev_match)
+		if (sk->sk_bound_dev_if)
 			score++;
 	}
 

-- 
2.14.3

On 5/9/18 4:42 AM, Paolo Abeni wrote:

Damir reported a breakage of SO_BINDTODEVICE for UDP sockets.
In absence of VRF devices, after commit fb74c27735f0 ("net:
ipv4: add second dif to udp socket lookups") the dif mismatch
isn't fatal anymore for UDP socket lookup with non null
sk_bound_dev_if, breaking SO_BINDTODEVICE semantics.

This changeset addresses the issue making the dif match mandatory
again in the above scenario.

Reported-by: Damir Mansurov <redacted>
Fixes: fb74c27735f0 ("net: ipv4: add second dif to udp socket lookups")
Fixes: 1801b570dd2a ("net: ipv6: add second dif to udp socket lookups")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/ipv4/udp.c | 4 ++--
 net/ipv6/udp.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

Acked-by: David Ahern <redacted>

From: Paolo Abeni <pabeni@redhat.com>
Date: Wed,  9 May 2018 12:42:34 +0200

Damir reported a breakage of SO_BINDTODEVICE for UDP sockets.
In absence of VRF devices, after commit fb74c27735f0 ("net:
ipv4: add second dif to udp socket lookups") the dif mismatch
isn't fatal anymore for UDP socket lookup with non null
sk_bound_dev_if, breaking SO_BINDTODEVICE semantics.

This changeset addresses the issue making the dif match mandatory
again in the above scenario.

Reported-by: Damir Mansurov <redacted>
Fixes: fb74c27735f0 ("net: ipv4: add second dif to udp socket lookups")
Fixes: 1801b570dd2a ("net: ipv6: add second dif to udp socket lookups")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Applied.