Re: [PATCH] peer_pid checking in ip_queue

[Patrick McHardy <kaber@trash.net>]

Pablo Neira wrote:
> Hi,
> 
> Henrik Nordstrom wrote:
> 
>> What about when the user program closes? How bad it is to have read 
>> the pid and then there is no userspace there?
>>  
>>
> As Patrick pointed out before, netlink is not reliable, so it will drop 
> the packets sent to an user space which doesn't exist without 
> notification. But if the user space program closes properly, peer_pid 
> will be reset. Have a look at ipq_rcv_nl_event and netlink_release. 
> AFAIK, if the user space program hangs or dies, kernel will release the 
> socket later, so for quite some time netlink will drop packets. Am I right?

Well, if it hangs the socket buffer will fill over time until
it reaches its limits, but there is nothing we can do. But
we can do something for the almost-known-no-listener case :)

Regards
Patrick

> 
> regards,
> Pablo
>