SUNRPC: Register both netids for AF_INET6 servers

TI-RPC is a user-space library of RPC functions that replaces ONC RPC
and allows RPC to operate in the new world of IPv6.

TI-RPC combines the concept of a transport protocol (UDP and TCP)
and a protocol family (PF_INET and PF_INET6) into a single identifier
called a "netid."  For example, "udp" means UDP over IPv4, and "udp6"
means UDP over IPv6.

For rpcbind, then, the RPC service tuple that is registered and
advertised is:

  [RPC program, RPC version, service address and port, netid]

instead of

  [RPC program, RPC version, port, protocol]

Service address is typically ANYADDR, but can be a specific address
of one of the interfaces on a multi-homed host.  The third item in
the new tuple is expressed as a universal address.

The current Linux rpcbind implementation registers a netid for both
protocol families when RPCB_SET is done for just the PF_INET6 version
of the netid (ie udp6 or tcp6).  So registering "udp6" causes a
registration for "udp" to appear automatically as well.

We've recently determined that this is incorrect behavior.  In the
TI-RPC world, "udp6" is not meant to imply that the registered RPC
service handles requests from AF_INET as well, even if the listener
socket does address mapping.  "udp" and "udp6" are entirely separate
capabilities, and must be registered separately.

The Linux kernel, unlike TI-RPC, leverages address mapping to allow a
single listener socket to handle requests for both AF_INET and AF_INET6.
This is still OK, but the kernel currently assumes registering "udp6"
will cover "udp" as well.  It registers only "udp6" for it's AF_INET6
services, even though they handle both AF_INET and AF_INET6 on the same
port.

So svc_register() actually needs to register both "udp" and "udp6"
explicitly (and likewise for TCP).  Until rpcbind is fixed, the
kernel can ignore the return code for the second RPCB_SET call.

Please merge this with commit 15231312:

    SUNRPC: Support IPv6 when registering kernel RPC services

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: Olaf Kirch <okir@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 100 insertions, 43 deletions

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index c43ccb628052..b8d2fcd0f715 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -720,69 +720,125 @@ svc_exit_thread(struct svc_rqst *rqstp)
 EXPORT_SYMBOL(svc_exit_thread);
 
 #ifdef CONFIG_SUNRPC_REGISTER_V4
+
 /*
- * Registering kernel RPC services with rpcbind version 2 will work
- * over either IPv4 or IPv6, since the Linux kernel always registers
- * services for the "any" address.
- *
- * However, the local rpcbind daemon listens on either only AF_INET
- * or AF_INET6 (never both).  When it listens on AF_INET6, an rpcbind
- * version 2 registration will result in registering the service at
- * IN6ADDR_ANY, even if the RPC service being registered is not
- * IPv6-enabled.
+ * Register an "inet" protocol family netid with the local
+ * rpcbind daemon via an rpcbind v4 SET request.
  *
- * Rpcbind version 4 allows us to be a little more specific.  Kernel
- * RPC services that don't yet support AF_INET6 can register
- * themselves as IPv4-only with the local rpcbind daemon, even if the
- * daemon is listening only on AF_INET6.
+ * No netconfig infrastructure is available in the kernel, so
+ * we map IP_ protocol numbers to netids by hand.
  *
- * And, registering IPv6-enabled kernel RPC services via AF_INET6
- * verifies that the local user space rpcbind daemon is properly
- * configured to support remote AF_INET6 rpcbind requests.
- *
- * An AF_INET6 registration request will fail if the local rpcbind
- * daemon is not set up to listen on AF_INET6.  Likewise, we fail
- * AF_INET6 registration requests if svc_register() is configured to
- * support only rpcbind version 2.
+ * Returns zero on success; a negative errno value is returned
+ * if any error occurs.
  */
-static int __svc_register(const u32 program, const u32 version,
-                          const sa_family_t family,
-                          const unsigned short protocol,
-                          const unsigned short port)
+static int __svc_rpcb_register4(const u32 program, const u32 version,
+                                const unsigned short protocol,
+                                const unsigned short port)
 {
         struct sockaddr_in sin = {
                 .sin_family             = AF_INET,
                 .sin_addr.s_addr        = htonl(INADDR_ANY),
                 .sin_port               = htons(port),
         };
+        char *netid;
+
+        switch (protocol) {
+        case IPPROTO_UDP:
+                netid = RPCBIND_NETID_UDP;
+                break;
+        case IPPROTO_TCP:
+                netid = RPCBIND_NETID_TCP;
+                break;
+        default:
+                return -EPROTONOSUPPORT;
+        }
+
+        return rpcb_v4_register(program, version,
+                                (struct sockaddr *)&sin, netid);
+}
+
+/*
+ * Register an "inet6" protocol family netid with the local
+ * rpcbind daemon via an rpcbind v4 SET request.
+ *
+ * No netconfig infrastructure is available in the kernel, so
+ * we map IP_ protocol numbers to netids by hand.
+ *
+ * Returns zero on success; a negative errno value is returned
+ * if any error occurs.
+ */
+static int __svc_rpcb_register6(const u32 program, const u32 version,
+                                const unsigned short protocol,
+                                const unsigned short port)
+{
         struct sockaddr_in6 sin6 = {
                 .sin6_family            = AF_INET6,
                 .sin6_addr              = IN6ADDR_ANY_INIT,
                 .sin6_port              = htons(port),
         };
-        struct sockaddr *sap;
         char *netid;
 
-        switch (family) {
-        case AF_INET:
-                sap = (struct sockaddr *)&sin;
-                netid = RPCBIND_NETID_TCP;
-                if (protocol == IPPROTO_UDP)
-                        netid = RPCBIND_NETID_UDP;
+        switch (protocol) {
+        case IPPROTO_UDP:
+                netid = RPCBIND_NETID_UDP6;
                 break;
-        case AF_INET6:
-                sap = (struct sockaddr *)&sin6;
+        case IPPROTO_TCP:
                 netid = RPCBIND_NETID_TCP6;
-                if (protocol == IPPROTO_UDP)
-                        netid = RPCBIND_NETID_UDP6;
                 break;
         default:
-                return -EAFNOSUPPORT;
+                return -EPROTONOSUPPORT;
+        }
+
+        return rpcb_v4_register(program, version,
+                                (struct sockaddr *)&sin6, netid);
+}
+
+/*
+ * Register a kernel RPC service via rpcbind version 4.
+ *
+ * Returns zero on success; a negative errno value is returned
+ * if any error occurs.
+ */
+static int __svc_register(const u32 program, const u32 version,
+                          const sa_family_t family,
+                          const unsigned short protocol,
+                          const unsigned short port)
+{
+        int error;
+
+        switch (family) {
+        case AF_INET:
+                return __svc_rpcb_register4(program, version,
+                                                protocol, port);
+        case AF_INET6:
+                error = __svc_rpcb_register6(program, version,
+                                                protocol, port);
+                if (error < 0)
+                        return error;
+
+                /*
+                 * Work around bug in some versions of Linux rpcbind
+                 * which don't allow registration of both inet and
+                 * inet6 netids.
+                 *
+                 * Error return ignored for now.
+                 */
+                __svc_rpcb_register4(program, version,
+                                                protocol, port);
+                return 0;
         }
 
-        return rpcb_v4_register(program, version, sap, netid);
+        return -EAFNOSUPPORT;
 }
-#else
+
+#else   /* CONFIG_SUNRPC_REGISTER_V4 */
+
+/*
+ * Register a kernel RPC service via rpcbind version 2.
+ *
+ * Returns zero on success; a negative errno value is returned
+ * if any error occurs.
+ */
 static int __svc_register(const u32 program, const u32 version,
                           sa_family_t family,
                           const unsigned short protocol,
@@ -793,7 +849,8 @@ static int __svc_register(const u32 program, const u32 version,
 
         return rpcb_register(program, version, protocol, port);
 }
-#endif
+
+#endif /* CONFIG_SUNRPC_REGISTER_V4 */
 
 /**
  * svc_register - register an RPC service with the local portmapper
@@ -817,12 +874,12 @@ int svc_register(const struct svc_serv *serv, const unsigned short proto,
                         if (progp->pg_vers[i] == NULL)
                                 continue;
 
-                        dprintk("svc: svc_register(%s, %u, %s, %u, %d)%s\n",
+                        dprintk("svc: svc_register(%sv%d, %s, %u, %u)%s\n",
                                         progp->pg_name,
-                                        serv->sv_family,
+                                        i,
                                         proto == IPPROTO_UDP?  "udp" : "tcp",
                                         port,
-                                        i,
+                                        serv->sv_family,
                                         progp->pg_vers[i]->vs_hidden?
                                                 " (but not telling portmap)" : "");