[CRIU] [PATCH 2/2] inet: set IP_FREEBIND before binding socket to an ipv6 address

[Pavel Emelyanov]

On 11/19/2015 03:38 PM, Andrew Vagin wrote:
> On Thu, Nov 19, 2015 at 03:33:37PM +0300, Pavel Emelyanov wrote:
>> On 11/18/2015 06:58 PM, Andrey Vagin wrote:
>>> From: Andrew Vagin <avagin at virtuozzo.com>
>>>
>>> When we restore ipv6 addresses, they go through a “tentative” phase
>>> and sockets could not be bound to them in this moment.
>>>
>>> Reported-by: Ross Boucher <boucher at gmail.com>
>>> Signed-off-by: Andrew Vagin <avagin at virtuozzo.com>
>>> ---
>>>  sk-inet.c | 29 ++++++++++++++++++++++++-----
>>>  1 file changed, 24 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/sk-inet.c b/sk-inet.c
>>> index 779a1bd..a973000 100644
>>> --- a/sk-inet.c
>>> +++ b/sk-inet.c
>>> @@ -633,17 +633,29 @@ static int restore_sockaddr(union sockaddr_inet *sa,
>>>  
>>>  int inet_bind(int sk, struct inet_sk_info *ii)
>>>  {
>>> +	bool rst_freebind = false;
>>>  	union sockaddr_inet addr;
>>>  	int addr_size;
>>> -	int val;
>>>  
>>>  	addr_size = restore_sockaddr(&addr, ii->ie->family,
>>>  			ii->ie->src_port, ii->ie->src_addr);
>>>  
>>> -	val = 1;
>>> -	if (setsockopt(sk, SOL_IP, IP_FREEBIND, &val, sizeof(int))) {
>>> -		pr_perror("Unable to set IP_FREEBIND");
>>> -		return -1;
>>> +	/*
>>> +	 * ipv6 addresses go through a “tentative” phase and
>>> +	 * sockets could not be bound to them in this moment
>>> +	 * without setting IP_FREEBIND.
>>> +	 */
>>> +	if (ii->ie->family == AF_INET6) {
>>> +		int yes = 1;
>>> +
>>> +		if (restore_opt(sk, SOL_IP, IP_FREEBIND, &yes))
>>> +			return -1;
>>> +
>>> +		if (ii->ie->ip_opts && ii->ie->ip_opts->freebind)
>>> +			/* don't restore freebind in restore_ip_opts() */
>>
>> At all? When will it get restored then?
> 
> We set the right value here, 

Where? If we're in this if branch then rst_freebin is false and we
don't even call restore_opt() below.

> so we don't need to restore it in restore_ip_opts()
>>
>>> +			ii->ie->ip_opts->has_freebind = false;
>>> +		else
>>> +			rst_freebind = true;
>>>  	}
>>>  
>>>  	if (bind(sk, (struct sockaddr *)&addr, addr_size) == -1) {
>>> @@ -651,6 +663,13 @@ int inet_bind(int sk, struct inet_sk_info *ii)
>>>  		return -1;
>>>  	}
>>>  
>>> +	if (rst_freebind) {
>>> +		int no = 0;
>>> +
>>> +		if (restore_opt(sk, SOL_IP, IP_FREEBIND, &no))
>>> +			return -1;
>>
>> Why here? Why not delay "NO" till actual options restore?
> 
> because we restore only "yes", "no" is default.

Yes, "no" is the default and you just set "no" _again_ here. Why?

>>
>>> +	}
>>> +
>>>  	return 0;
>>>  }
>>>  
>>>
>>
> .
>