[PATCH 4.19 147/421] net/ipv4: swap flow ports when validating source

Greg Kroah-Hartman
2021-07-19T16:17:52Z

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 b96aa88087be..70e5e9e5d835 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -353,6 +353,8 @@ 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