From: "J. Bruce Fields" Subject: Re: [PATCH 3/8] SUNRPC: Set V6ONLY socket option for RPC listener sockets Date: Thu, 14 Aug 2008 16:05:54 -0400 Message-ID: <20080814200554.GI23859@fieldses.org> References: <20080813223653.13068.9467.stgit@manray.1015granger.net> <20080813223953.13068.97829.stgit@manray.1015granger.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: trond.myklebust@netapp.com, trond.myklebust@fys.uio.no, linux-nfs@vger.kernel.org To: Chuck Lever Return-path: Received: from mail.fieldses.org ([66.93.2.214]:42862 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753092AbYHNUGC (ORCPT ); Thu, 14 Aug 2008 16:06:02 -0400 In-Reply-To: <20080813223953.13068.97829.stgit-meopP2rzCrTwdl/1UfZZQIVfYA8g3rJ/@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Aug 13, 2008 at 06:39:54PM -0400, Chuck Lever wrote: > My plan is to use an AF_INET listener on systems that support only IPv4, > and an AF_INET6 listener on systems that can support IPv6. Incoming > IPv4 packets will be posted to an AF_INET6 listener with a mapped IPv4 > address. How will the nfs server choose whether to use AF_INET or AF_INET6? Will we need some new user interface? --b. > > Max Matveev says: > Creating a single listener can be dangerous - if net.ipv6.bindv6only > is enabled then it's possible to create another listener in v4 > namespace on the same port and steal the traffic from the "unifed" > listener. You need to disable V6ONLY explicitly via a sockopt to stop > that. > > Set appropriate socket option on RPC server listener sockets to prevent > this. > > Signed-off-by: Chuck Lever > --- > > net/sunrpc/svcsock.c | 13 +++++++++++++ > 1 files changed, 13 insertions(+), 0 deletions(-) > > diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c > index 3e65719..f91377c 100644 > --- a/net/sunrpc/svcsock.c > +++ b/net/sunrpc/svcsock.c > @@ -1114,6 +1114,7 @@ static struct svc_sock *svc_setup_socket(struct svc_serv *serv, > struct svc_sock *svsk; > struct sock *inet; > int pmap_register = !(flags & SVC_SOCK_ANONYMOUS); > + int val; > > dprintk("svc: svc_setup_socket %p\n", sock); > if (!(svsk = kzalloc(sizeof(*svsk), GFP_KERNEL))) { > @@ -1146,6 +1147,18 @@ static struct svc_sock *svc_setup_socket(struct svc_serv *serv, > else > svc_tcp_init(svsk, serv); > > + /* > + * We start one listener per sv_serv. We want AF_INET > + * requests to be automatically shunted to our AF_INET6 > + * listener using a mapped IPv4 address. Make sure > + * no-one starts an equivalent IPv4 listener, which > + * would steal our incoming connections. > + */ > + val = 0; > + if (serv->sv_family == AF_INET6) > + kernel_setsockopt(sock, SOL_IPV6, IPV6_V6ONLY, > + (char *)&val, sizeof(val)); > + > dprintk("svc: svc_setup_socket created %p (inet %p)\n", > svsk, svsk->sk_sk); > >