[PATCH net] ping: fix the sk_bound_dev_if match in ping_lookup

[PATCH net] ping: fix the sk_bound_dev_if match in ping_lookup

[Xin Long]

When 'ping' changes to use PING socket instead of RAW socket by:

   # sysctl -w net.ipv4.ping_group_range="0 100"

the selftests 'router_broadcast.sh' will fail, as such command

  # ip vrf exec vrf-h1 ping -I veth0 198.51.100.255 -b

can't receive the response skb by the PING socket. It's caused by mismatch
of sk_bound_dev_if and dif in ping_rcv() when looking up the PING socket,
as dif is vrf-h1 if dif's master was set to vrf-h1.

This patch is to fix this regression by also checking the sk_bound_dev_if
against sdif so that the packets can stil be received even if the socket
is not bound to the vrf device but to the real iif.

Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
Reported-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/ipv4/ping.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 0e56df3a45e2..bcf7bc71cb56 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -220,7 +220,8 @@ static struct sock *ping_lookup(struct net *net, struct sk_buff *skb, u16 ident)
 			continue;
 		}
 
-		if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)
+		if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif &&
+		    sk->sk_bound_dev_if != inet_sdif(skb))
 			continue;
 
 		sock_hold(sk);
-- 
2.27.0

Re: [PATCH net] ping: fix the sk_bound_dev_if match in ping_lookup

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Sat, 22 Jan 2022 06:40:56 -0500 you wrote:
> When 'ping' changes to use PING socket instead of RAW socket by:
> 
>    # sysctl -w net.ipv4.ping_group_range="0 100"
> 
> the selftests 'router_broadcast.sh' will fail, as such command
> 
>   # ip vrf exec vrf-h1 ping -I veth0 198.51.100.255 -b
> 
> [...]

Here is the summary with links:
  - [net] ping: fix the sk_bound_dev_if match in ping_lookup
    https://git.kernel.org/netdev/net/c/2afc3b5a31f9

You are awesome, thank you!
-- 
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