Re: [PATCH 3/8] SUNRPC: Set V6ONLY socket option for RPC listener sockets

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, Aug 14, 2008 at 04:34:14PM -0400, Chuck Lever wrote:
> On Aug 14, 2008, at 4:05 PM, J. Bruce Fields wrote:
>> 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?
>
> [PATCH 2/8] changes svc_create() to take an additional argument which  
> specifies the listener's address family.  This value is stored in  
> svc_serv.

Right, but I'm asking about the nfsd server, not the rpc server, and the
user interface, not the in-kernel interface: so suppose I'm a server
administrator, and want my nfs server to listen for ipv6 connections.
Will there be some switch I'll need to flip?

--b.

>
>>> Max Matveev <makc@sgi.com> 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 <chuck.lever@oracle.com>
>>> ---
>>>
>>> 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);
>>>
>>>
>
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com
>
>
>