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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, Miao Wang <shankerwangmiao@gmail.com>,
        David Ahern <dsahern@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 383/593] net/ipv4: swap flow ports when validating source
Date:   Mon, 12 Jul 2021 08:09:03 +0200
Message-Id: <20210712060929.145260623@linuxfoundation.org>
In-Reply-To: <20210712060843.180606720@linuxfoundation.org>
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From: Miao Wang <shankerwangmiao@gmail.com>

[ Upstream commit c69f114d09891adfa3e301a35d9e872b8b7b5a50 ]

When doing source address validation, the flowi4 struct used for
fib_lookup should be in the reverse direction to the given skb.
fl4_dport and fl4_sport returned by fib4_rules_early_flow_dissect
should thus be swapped.

Fixes: 5a847a6e1477 ("net/ipv4: Initialize proto and ports in flow struct")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv4/fib_frontend.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 84bb707bd88d..647bceab56c2 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -371,6 +371,8 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 		fl4.flowi4_proto = 0;
 		fl4.fl4_sport = 0;
 		fl4.fl4_dport = 0;
+	} else {
+		swap(fl4.fl4_sport, fl4.fl4_dport);
 	}
 
 	if (fib_lookup(net, &fl4, &res, 0))
-- 
2.30.2