netdev - [PATCH] net/ipv4: swap flow ports when validating source

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Message-Id: <1B652E0A-2749-4B75-BC6D-2DAE2A4555A8@gmail.com>
Date:   Mon, 21 Jun 2021 23:17:32 +0800
From:   Wang Shanker <shankerwangmiao@...il.com>
To:     netdev@...r.kernel.org
Cc:     David Ahern <dsahern@...il.com>,
        Roopa Prabhu <roopa@...ulusnetworks.com>
Subject: [PATCH] net/ipv4: swap flow ports when validating source

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: 5a847a6 ("net/ipv4: Initialize proto and ports in flow struct")
Signed-off-by: Miao Wang <shankerwangmiao@...il.com>
---
 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))
-- 
2.20.1