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.
Max Matveev <makc@xxxxxxx> 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@xxxxxxxxxx>
---
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
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