Subject: Re: [PATCH net-next 6/9] net: Fix up inet_addr_type checks

From: David Ahern <[email-masked]>
Date: Tue, 11 Aug 2015 12:18:20 -0600

On 8/11/15 12:14 PM, David Miller wrote:
> From: David Ahern <[email-masked]>
> Date: Mon, 10 Aug 2015 11:50:33 -0600
>
>> @@ -427,6 +428,7 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
>>   	struct net *net = sock_net(sk);
>>   	unsigned short snum;
>>   	int chk_addr_ret;
>> +	int tb_id = 0;
>>   	int err;
>>
>>   	/* If the socket has its own bind function then use it. (RAW) */
>> @@ -448,7 +450,16 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
>>   			goto out;
>>   	}
>>
>> -	chk_addr_ret = inet_addr_type(net, addr->sin_addr.s_addr);
>> +	if (sk->sk_bound_dev_if) {
>> +		struct net_device *dev;
>> +
>> +		rcu_read_lock();
>> +		dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
>> +		if (dev)
>> +			tb_id = vrf_dev_table_rcu(dev);
>> +		rcu_read_unlock();
>> +	}
>> +	chk_addr_ret = inet_addr_type_table(net, addr->sin_addr.s_addr, tb_id);
>>
>>   	/* Not specified by any standard per-se, however it breaks too
>>   	 * many applications when removed.  It is unfortunate since
>   ...
>> diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
>> index b11321a8e58d..d84ae0e30369 100644
>> --- a/net/ipv4/fib_frontend.c
>> +++ b/net/ipv4/fib_frontend.c
>> @@ -226,6 +226,9 @@ static inline unsigned int __inet_dev_addr_type(struct net *net,
>>
>>   	rcu_read_lock();
>>
>> +	if (!tb_id)
>> +		tb_id = RT_TABLE_LOCAL;
>> +
>>   	table = fib_get_table(net, tb_id);
>
> All of this code that quietly translates table ID zero into RT_TABLE_LOCAL is
> confusing.
>
> It would be so much easier to understand if the code was structured like:
>
> 	int tb_id = RT_TABLE_LOCAL;
>
> 	if (doing_vrf_stuff)
> 		tb_id = foo;
>

The intent here was to default to current behavior and to keep the 
details of that in one place. If you prefer table id to always enter 
with the right value I can make that happen.

David