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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Mike Manning <mmanning@vyatta.att-mail.com>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 66/83] net: prefer socket bound to interface when not in VRF
Date:   Mon, 11 Oct 2021 15:46:26 +0200
Message-Id: <20211011134510.664399259@linuxfoundation.org>
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From: Mike Manning <mvrmanning@gmail.com>

[ Upstream commit 8d6c414cd2fb74aa6812e9bfec6178f8246c4f3a ]

The commit 6da5b0f027a8 ("net: ensure unbound datagram socket to be
chosen when not in a VRF") modified compute_score() so that a device
match is always made, not just in the case of an l3mdev skb, then
increments the score also for unbound sockets. This ensures that
sockets bound to an l3mdev are never selected when not in a VRF.
But as unbound and bound sockets are now scored equally, this results
in the last opened socket being selected if there are matches in the
default VRF for an unbound socket and a socket bound to a dev that is
not an l3mdev. However, handling prior to this commit was to always
select the bound socket in this case. Reinstate this handling by
incrementing the score only for bound sockets. The required isolation
due to choosing between an unbound socket and a socket bound to an
l3mdev remains in place due to the device match always being made.
The same approach is taken for compute_score() for stream sockets.

Fixes: 6da5b0f027a8 ("net: ensure unbound datagram socket to be chosen when not in a VRF")
Fixes: e78190581aff ("net: ensure unbound stream socket to be chosen when not in a VRF")
Signed-off-by: Mike Manning <mmanning@vyatta.att-mail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/cf0a8523-b362-1edf-ee78-eef63cbbb428@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv4/inet_hashtables.c  | 4 +++-
 net/ipv4/udp.c              | 3 ++-
 net/ipv6/inet6_hashtables.c | 2 +-
 net/ipv6/udp.c              | 3 ++-
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 45fb450b4522..f3fd5c911ed0 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -242,8 +242,10 @@ static inline int compute_score(struct sock *sk, struct net *net,
 
 		if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 			return -1;
+		score =  sk->sk_bound_dev_if ? 2 : 1;
 
-		score = sk->sk_family == PF_INET ? 2 : 1;
+		if (sk->sk_family == PF_INET)
+			score++;
 		if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 			score++;
 	}
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index bd7fd9b1f24c..655f0d8a13d3 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -390,7 +390,8 @@ static int compute_score(struct sock *sk, struct net *net,
 					dif, sdif);
 	if (!dev_match)
 		return -1;
-	score += 4;
+	if (sk->sk_bound_dev_if)
+		score += 4;
 
 	if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 		score++;
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 55c290d55605..67c9114835c8 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -106,7 +106,7 @@ static inline int compute_score(struct sock *sk, struct net *net,
 		if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 			return -1;
 
-		score = 1;
+		score =  sk->sk_bound_dev_if ? 2 : 1;
 		if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 			score++;
 	}
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 1943ae5103eb..bae6b51a9bd4 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -133,7 +133,8 @@ static int compute_score(struct sock *sk, struct net *net,
 	dev_match = udp_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif);
 	if (!dev_match)
 		return -1;
-	score++;
+	if (sk->sk_bound_dev_if)
+		score++;
 
 	if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 		score++;
-- 
2.33.0