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

[David Ahern <dsahern@gmail.com>]

On 6/21/21 9:17 AM, Wang Shanker wrote:
> 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")

I believe the hash should be 12 chars: 5a847a6e1477

> Signed-off-by: Miao Wang <shankerwangmiao@gmail.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))
> 

Reviewed-by: David Ahern <dsahern@kernel.org>