netdev - Re: [PATCH 2/5] net: Make rtnetlink infrastructure network namespace aware

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <46FE72E3.3000402@trash.net>
Date:	Sat, 29 Sep 2007 17:44:35 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	Linux Containers <containers@...ts.osdl.org>
Subject: Re: [PATCH 2/5] net: Make rtnetlink infrastructure network namespace
 aware

Eric W. Biederman wrote:
>  void rtnl_unlock(void)
>  {
> -	mutex_unlock(&rtnl_mutex);
> -	if (rtnl && rtnl->sk_receive_queue.qlen)
> +	struct net *net;
> +
> +	/*
> +	 * Loop through all of the rtnl sockets until none of them (in
> +	 * a live network namespace) have queue packets.
> +	 *
> +	 * We have to be careful with the locking here as
> +	 * sk_data_ready aka rtnetlink_rcv takes the rtnl_mutex.
> +	 *
> +	 * To ensure the network namespace does not exit while
> +	 * we are processing packets on it's rtnl socket we
> +	 * grab a reference to the network namespace, ignoring
> +	 * it if the network namespace has already exited.
> +	 */
> +retry:
> +	for_each_net(net) {
> +		struct sock *rtnl = net->rtnl;
> +
> +		if (!rtnl || !rtnl->sk_receive_queue.qlen)
> +			continue;
> +
> +		if (!maybe_get_net(net))
> +			continue;
> +
> +		mutex_unlock(&rtnl_mutex);
>  		rtnl->sk_data_ready(rtnl, 0);
> +		mutex_lock(&rtnl_mutex);
> +		put_net(net);
> +		goto retry;
> +	}
> +	mutex_unlock(&rtnl_mutex);
> +
>  	netdev_run_todo();
>  }


I'm wondering why this receive queue processing on unlock is still
necessary today, we don't do trylock in rtnetlink_rcv anymore, so
all senders will simply wait until the lock is released and then
process the queue.
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html