netdev - [PATCH] ipv4: fix the problem of ping failure in some cases

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Date:   Sat, 22 Aug 2020 15:46:37 +0800
From:   guodeqing <geffrey.guo@...wei.com>
To:     <davem@...emloft.net>
CC:     <kuba@...nel.org>, <dsahern@...il.com>, <netdev@...r.kernel.org>,
        <geffrey.guo@...wei.com>
Subject: [PATCH] ipv4: fix the problem of ping failure in some cases

ie.,
$ ifconfig eth0 9.9.9.9 netmask 255.255.255.0

$ ping -I lo 9.9.9.9
ping: Warning: source address might be selected on device other than lo.
PING 9.9.9.9 (9.9.9.9) from 9.9.9.9 lo: 56(84) bytes of data.

4 packets transmitted, 0 received, 100% packet loss, time 3068ms

This is because the return value of __raw_v4_lookup in raw_v4_input
is null, the packets cannot be sent to the ping application.
The reason of the __raw_v4_lookup failure is that sk_bound_dev_if and
dif/sdif are not equal in raw_sk_bound_dev_eq.

Here I add a check of whether the sk_bound_dev_if is LOOPBACK_IFINDEX
to solve this problem.

Fixes: 19e4e768064a8 ("ipv4: Fix raw socket lookup for local traffic")
Signed-off-by: guodeqing <geffrey.guo@...wei.com>
---
 include/net/inet_sock.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index a3702d1..7707b1d 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -144,7 +144,7 @@ static inline bool inet_bound_dev_eq(bool l3mdev_accept, int bound_dev_if,
 {
 	if (!bound_dev_if)
 		return !sdif || l3mdev_accept;
-	return bound_dev_if == dif || bound_dev_if == sdif;
+	return bound_dev_if == dif || bound_dev_if == sdif || bound_dev_if == LOOPBACK_IFINDEX;
 }

 struct inet_cork {
-- 
2.7.4