Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1098 insertions, 0 deletions

diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c
new file mode 100644
index 000000000..82afb5669
--- /dev/null
+++ b/net/sunrpc/rpcb_clnt.c
@@ -0,0 +1,1098 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * In-kernel rpcbind client supporting versions 2, 3, and 4 of the rpcbind
+ * protocol
+ *
+ * Based on RFC 1833: "Binding Protocols for ONC RPC Version 2" and
+ * RFC 3530: "Network File System (NFS) version 4 Protocol"
+ *
+ * Original: Gilles Quillard, Bull Open Source, 2005 <gilles.quillard@bull.net>
+ * Updated: Chuck Lever, Oracle Corporation, 2007 <chuck.lever@oracle.com>
+ *
+ * Descended from net/sunrpc/pmap_clnt.c,
+ *  Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/module.h>
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/un.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <net/ipv6.h>
+
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/addr.h>
+#include <linux/sunrpc/sched.h>
+#include <linux/sunrpc/xprtsock.h>
+
+#include <trace/events/sunrpc.h>
+
+#include "netns.h"
+
+#define RPCBIND_SOCK_PATHNAME	"/var/run/rpcbind.sock"
+
+#define RPCBIND_PROGRAM		(100000u)
+#define RPCBIND_PORT		(111u)
+
+#define RPCBVERS_2		(2u)
+#define RPCBVERS_3		(3u)
+#define RPCBVERS_4		(4u)
+
+enum {
+	RPCBPROC_NULL,
+	RPCBPROC_SET,
+	RPCBPROC_UNSET,
+	RPCBPROC_GETPORT,
+	RPCBPROC_GETADDR = 3,		/* alias for GETPORT */
+	RPCBPROC_DUMP,
+	RPCBPROC_CALLIT,
+	RPCBPROC_BCAST = 5,		/* alias for CALLIT */
+	RPCBPROC_GETTIME,
+	RPCBPROC_UADDR2TADDR,
+	RPCBPROC_TADDR2UADDR,
+	RPCBPROC_GETVERSADDR,
+	RPCBPROC_INDIRECT,
+	RPCBPROC_GETADDRLIST,
+	RPCBPROC_GETSTAT,
+};
+
+/*
+ * r_owner
+ *
+ * The "owner" is allowed to unset a service in the rpcbind database.
+ *
+ * For AF_LOCAL SET/UNSET requests, rpcbind treats this string as a
+ * UID which it maps to a local user name via a password lookup.
+ * In all other cases it is ignored.
+ *
+ * For SET/UNSET requests, user space provides a value, even for
+ * network requests, and GETADDR uses an empty string.  We follow
+ * those precedents here.
+ */
+#define RPCB_OWNER_STRING	"0"
+#define RPCB_MAXOWNERLEN	sizeof(RPCB_OWNER_STRING)
+
+/*
+ * XDR data type sizes
+ */
+#define RPCB_program_sz		(1)
+#define RPCB_version_sz		(1)
+#define RPCB_protocol_sz	(1)
+#define RPCB_port_sz		(1)
+#define RPCB_boolean_sz		(1)
+
+#define RPCB_netid_sz		(1 + XDR_QUADLEN(RPCBIND_MAXNETIDLEN))
+#define RPCB_addr_sz		(1 + XDR_QUADLEN(RPCBIND_MAXUADDRLEN))
+#define RPCB_ownerstring_sz	(1 + XDR_QUADLEN(RPCB_MAXOWNERLEN))
+
+/*
+ * XDR argument and result sizes
+ */
+#define RPCB_mappingargs_sz	(RPCB_program_sz + RPCB_version_sz + \
+				RPCB_protocol_sz + RPCB_port_sz)
+#define RPCB_getaddrargs_sz	(RPCB_program_sz + RPCB_version_sz + \
+				RPCB_netid_sz + RPCB_addr_sz + \
+				RPCB_ownerstring_sz)
+
+#define RPCB_getportres_sz	RPCB_port_sz
+#define RPCB_setres_sz		RPCB_boolean_sz
+
+/*
+ * Note that RFC 1833 does not put any size restrictions on the
+ * address string returned by the remote rpcbind database.
+ */
+#define RPCB_getaddrres_sz	RPCB_addr_sz
+
+static void			rpcb_getport_done(struct rpc_task *, void *);
+static void			rpcb_map_release(void *data);
+static const struct rpc_program	rpcb_program;
+
+struct rpcbind_args {
+	struct rpc_xprt *	r_xprt;
+
+	u32			r_prog;
+	u32			r_vers;
+	u32			r_prot;
+	unsigned short		r_port;
+	const char *		r_netid;
+	const char *		r_addr;
+	const char *		r_owner;
+
+	int			r_status;
+};
+
+static const struct rpc_procinfo rpcb_procedures2[];
+static const struct rpc_procinfo rpcb_procedures3[];
+static const struct rpc_procinfo rpcb_procedures4[];
+
+struct rpcb_info {
+	u32			rpc_vers;
+	const struct rpc_procinfo *rpc_proc;
+};
+
+static const struct rpcb_info rpcb_next_version[];
+static const struct rpcb_info rpcb_next_version6[];
+
+static const struct rpc_call_ops rpcb_getport_ops = {
+	.rpc_call_done		= rpcb_getport_done,
+	.rpc_release		= rpcb_map_release,
+};
+
+static void rpcb_wake_rpcbind_waiters(struct rpc_xprt *xprt, int status)
+{
+	xprt_clear_binding(xprt);
+	rpc_wake_up_status(&xprt->binding, status);
+}
+
+static void rpcb_map_release(void *data)
+{
+	struct rpcbind_args *map = data;
+
+	rpcb_wake_rpcbind_waiters(map->r_xprt, map->r_status);
+	xprt_put(map->r_xprt);
+	kfree(map->r_addr);
+	kfree(map);
+}
+
+static int rpcb_get_local(struct net *net)
+{
+	int cnt;
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+	spin_lock(&sn->rpcb_clnt_lock);
+	if (sn->rpcb_users)
+		sn->rpcb_users++;
+	cnt = sn->rpcb_users;
+	spin_unlock(&sn->rpcb_clnt_lock);
+
+	return cnt;
+}
+
+void rpcb_put_local(struct net *net)
+{
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+	struct rpc_clnt *clnt = sn->rpcb_local_clnt;
+	struct rpc_clnt *clnt4 = sn->rpcb_local_clnt4;
+	int shutdown = 0;
+
+	spin_lock(&sn->rpcb_clnt_lock);
+	if (sn->rpcb_users) {
+		if (--sn->rpcb_users == 0) {
+			sn->rpcb_local_clnt = NULL;
+			sn->rpcb_local_clnt4 = NULL;
+		}
+		shutdown = !sn->rpcb_users;
+	}
+	spin_unlock(&sn->rpcb_clnt_lock);
+
+	if (shutdown) {
+		/*
+		 * cleanup_rpcb_clnt - remove xprtsock's sysctls, unregister
+		 */
+		if (clnt4)
+			rpc_shutdown_client(clnt4);
+		if (clnt)
+			rpc_shutdown_client(clnt);
+	}
+}
+
+static void rpcb_set_local(struct net *net, struct rpc_clnt *clnt,
+			struct rpc_clnt *clnt4,
+			bool is_af_local)
+{
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+	/* Protected by rpcb_create_local_mutex */
+	sn->rpcb_local_clnt = clnt;
+	sn->rpcb_local_clnt4 = clnt4;
+	sn->rpcb_is_af_local = is_af_local ? 1 : 0;
+	smp_wmb();
+	sn->rpcb_users = 1;
+}
+
+/*
+ * Returns zero on success, otherwise a negative errno value
+ * is returned.
+ */
+static int rpcb_create_local_unix(struct net *net)
+{
+	static const struct sockaddr_un rpcb_localaddr_rpcbind = {
+		.sun_family		= AF_LOCAL,
+		.sun_path		= RPCBIND_SOCK_PATHNAME,
+	};
+	struct rpc_create_args args = {
+		.net		= net,
+		.protocol	= XPRT_TRANSPORT_LOCAL,
+		.address	= (struct sockaddr *)&rpcb_localaddr_rpcbind,
+		.addrsize	= sizeof(rpcb_localaddr_rpcbind),
+		.servername	= "localhost",
+		.program	= &rpcb_program,
+		.version	= RPCBVERS_2,
+		.authflavor	= RPC_AUTH_NULL,
+		.cred		= current_cred(),
+		/*
+		 * We turn off the idle timeout to prevent the kernel
+		 * from automatically disconnecting the socket.
+		 * Otherwise, we'd have to cache the mount namespace
+		 * of the caller and somehow pass that to the socket
+		 * reconnect code.
+		 */
+		.flags		= RPC_CLNT_CREATE_NO_IDLE_TIMEOUT,
+	};
+	struct rpc_clnt *clnt, *clnt4;
+	int result = 0;
+
+	/*
+	 * Because we requested an RPC PING at transport creation time,
+	 * this works only if the user space portmapper is rpcbind, and
+	 * it's listening on AF_LOCAL on the named socket.
+	 */
+	clnt = rpc_create(&args);
+	if (IS_ERR(clnt)) {
+		result = PTR_ERR(clnt);
+		goto out;
+	}
+
+	clnt4 = rpc_bind_new_program(clnt, &rpcb_program, RPCBVERS_4);
+	if (IS_ERR(clnt4))
+		clnt4 = NULL;
+
+	rpcb_set_local(net, clnt, clnt4, true);
+
+out:
+	return result;
+}
+
+/*
+ * Returns zero on success, otherwise a negative errno value
+ * is returned.
+ */
+static int rpcb_create_local_net(struct net *net)
+{
+	static const struct sockaddr_in rpcb_inaddr_loopback = {
+		.sin_family		= AF_INET,
+		.sin_addr.s_addr	= htonl(INADDR_LOOPBACK),
+		.sin_port		= htons(RPCBIND_PORT),
+	};
+	struct rpc_create_args args = {
+		.net		= net,
+		.protocol	= XPRT_TRANSPORT_TCP,
+		.address	= (struct sockaddr *)&rpcb_inaddr_loopback,
+		.addrsize	= sizeof(rpcb_inaddr_loopback),
+		.servername	= "localhost",
+		.program	= &rpcb_program,
+		.version	= RPCBVERS_2,
+		.authflavor	= RPC_AUTH_UNIX,
+		.cred		= current_cred(),
+		.flags		= RPC_CLNT_CREATE_NOPING,
+	};
+	struct rpc_clnt *clnt, *clnt4;
+	int result = 0;
+
+	clnt = rpc_create(&args);
+	if (IS_ERR(clnt)) {
+		result = PTR_ERR(clnt);
+		goto out;
+	}
+
+	/*
+	 * This results in an RPC ping.  On systems running portmapper,
+	 * the v4 ping will fail.  Proceed anyway, but disallow rpcb
+	 * v4 upcalls.
+	 */
+	clnt4 = rpc_bind_new_program(clnt, &rpcb_program, RPCBVERS_4);
+	if (IS_ERR(clnt4))
+		clnt4 = NULL;
+
+	rpcb_set_local(net, clnt, clnt4, false);
+
+out:
+	return result;
+}
+
+/*
+ * Returns zero on success, otherwise a negative errno value
+ * is returned.
+ */
+int rpcb_create_local(struct net *net)
+{
+	static DEFINE_MUTEX(rpcb_create_local_mutex);
+	int result = 0;
+
+	if (rpcb_get_local(net))
+		return result;
+
+	mutex_lock(&rpcb_create_local_mutex);
+	if (rpcb_get_local(net))
+		goto out;
+
+	if (rpcb_create_local_unix(net) != 0)
+		result = rpcb_create_local_net(net);
+
+out:
+	mutex_unlock(&rpcb_create_local_mutex);
+	return result;
+}
+
+static struct rpc_clnt *rpcb_create(struct net *net, const char *nodename,
+				    const char *hostname,
+				    struct sockaddr *srvaddr, size_t salen,
+				    int proto, u32 version,
+				    const struct cred *cred,
+				    const struct rpc_timeout *timeo)
+{
+	struct rpc_create_args args = {
+		.net		= net,
+		.protocol	= proto,
+		.address	= srvaddr,
+		.addrsize	= salen,
+		.timeout	= timeo,
+		.servername	= hostname,
+		.nodename	= nodename,
+		.program	= &rpcb_program,
+		.version	= version,
+		.authflavor	= RPC_AUTH_UNIX,
+		.cred		= cred,
+		.flags		= (RPC_CLNT_CREATE_NOPING |
+					RPC_CLNT_CREATE_NONPRIVPORT),
+	};
+
+	switch (srvaddr->sa_family) {
+	case AF_INET:
+		((struct sockaddr_in *)srvaddr)->sin_port = htons(RPCBIND_PORT);
+		break;
+	case AF_INET6:
+		((struct sockaddr_in6 *)srvaddr)->sin6_port = htons(RPCBIND_PORT);
+		break;
+	default:
+		return ERR_PTR(-EAFNOSUPPORT);
+	}
+
+	return rpc_create(&args);
+}
+
+static int rpcb_register_call(struct sunrpc_net *sn, struct rpc_clnt *clnt, struct rpc_message *msg, bool is_set)
+{
+	int flags = RPC_TASK_NOCONNECT;
+	int error, result = 0;
+
+	if (is_set || !sn->rpcb_is_af_local)
+		flags = RPC_TASK_SOFTCONN;
+	msg->rpc_resp = &result;
+
+	error = rpc_call_sync(clnt, msg, flags);
+	if (error < 0)
+		return error;
+
+	if (!result)
+		return -EACCES;
+	return 0;
+}
+
+/**
+ * rpcb_register - set or unset a port registration with the local rpcbind svc
+ * @net: target network namespace
+ * @prog: RPC program number to bind
+ * @vers: RPC version number to bind
+ * @prot: transport protocol to register
+ * @port: port value to register
+ *
+ * Returns zero if the registration request was dispatched successfully
+ * and the rpcbind daemon returned success.  Otherwise, returns an errno
+ * value that reflects the nature of the error (request could not be
+ * dispatched, timed out, or rpcbind returned an error).
+ *
+ * RPC services invoke this function to advertise their contact
+ * information via the system's rpcbind daemon.  RPC services
+ * invoke this function once for each [program, version, transport]
+ * tuple they wish to advertise.
+ *
+ * Callers may also unregister RPC services that are no longer
+ * available by setting the passed-in port to zero.  This removes
+ * all registered transports for [program, version] from the local
+ * rpcbind database.
+ *
+ * This function uses rpcbind protocol version 2 to contact the
+ * local rpcbind daemon.
+ *
+ * Registration works over both AF_INET and AF_INET6, and services
+ * registered via this function are advertised as available for any
+ * address.  If the local rpcbind daemon is listening on AF_INET6,
+ * services registered via this function will be advertised on
+ * IN6ADDR_ANY (ie available for all AF_INET and AF_INET6
+ * addresses).
+ */
+int rpcb_register(struct net *net, u32 prog, u32 vers, int prot, unsigned short port)
+{
+	struct rpcbind_args map = {
+		.r_prog		= prog,
+		.r_vers		= vers,
+		.r_prot		= prot,
+		.r_port		= port,
+	};
+	struct rpc_message msg = {
+		.rpc_argp	= &map,
+	};
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+	bool is_set = false;
+
+	trace_pmap_register(prog, vers, prot, port);
+
+	msg.rpc_proc = &rpcb_procedures2[RPCBPROC_UNSET];
+	if (port != 0) {
+		msg.rpc_proc = &rpcb_procedures2[RPCBPROC_SET];
+		is_set = true;
+	}
+
+	return rpcb_register_call(sn, sn->rpcb_local_clnt, &msg, is_set);
+}
+
+/*
+ * Fill in AF_INET family-specific arguments to register
+ */
+static int rpcb_register_inet4(struct sunrpc_net *sn,
+			       const struct sockaddr *sap,
+			       struct rpc_message *msg)
+{
+	const struct sockaddr_in *sin = (const struct sockaddr_in *)sap;
+	struct rpcbind_args *map = msg->rpc_argp;
+	unsigned short port = ntohs(sin->sin_port);
+	bool is_set = false;
+	int result;
+
+	map->r_addr = rpc_sockaddr2uaddr(sap, GFP_KERNEL);
+
+	msg->rpc_proc = &rpcb_procedures4[RPCBPROC_UNSET];
+	if (port != 0) {
+		msg->rpc_proc = &rpcb_procedures4[RPCBPROC_SET];
+		is_set = true;
+	}
+
+	result = rpcb_register_call(sn, sn->rpcb_local_clnt4, msg, is_set);
+	kfree(map->r_addr);
+	return result;
+}
+
+/*
+ * Fill in AF_INET6 family-specific arguments to register
+ */
+static int rpcb_register_inet6(struct sunrpc_net *sn,
+			       const struct sockaddr *sap,
+			       struct rpc_message *msg)
+{
+	const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)sap;
+	struct rpcbind_args *map = msg->rpc_argp;
+	unsigned short port = ntohs(sin6->sin6_port);
+	bool is_set = false;
+	int result;
+
+	map->r_addr = rpc_sockaddr2uaddr(sap, GFP_KERNEL);
+
+	msg->rpc_proc = &rpcb_procedures4[RPCBPROC_UNSET];
+	if (port != 0) {
+		msg->rpc_proc = &rpcb_procedures4[RPCBPROC_SET];
+		is_set = true;
+	}
+
+	result = rpcb_register_call(sn, sn->rpcb_local_clnt4, msg, is_set);
+	kfree(map->r_addr);
+	return result;
+}
+
+static int rpcb_unregister_all_protofamilies(struct sunrpc_net *sn,
+					     struct rpc_message *msg)
+{
+	struct rpcbind_args *map = msg->rpc_argp;
+
+	trace_rpcb_unregister(map->r_prog, map->r_vers, map->r_netid);
+
+	map->r_addr = "";
+	msg->rpc_proc = &rpcb_procedures4[RPCBPROC_UNSET];
+
+	return rpcb_register_call(sn, sn->rpcb_local_clnt4, msg, false);
+}
+
+/**
+ * rpcb_v4_register - set or unset a port registration with the local rpcbind
+ * @net: target network namespace
+ * @program: RPC program number of service to (un)register
+ * @version: RPC version number of service to (un)register
+ * @address: address family, IP address, and port to (un)register
+ * @netid: netid of transport protocol to (un)register
+ *
+ * Returns zero if the registration request was dispatched successfully
+ * and the rpcbind daemon returned success.  Otherwise, returns an errno
+ * value that reflects the nature of the error (request could not be
+ * dispatched, timed out, or rpcbind returned an error).
+ *
+ * RPC services invoke this function to advertise their contact
+ * information via the system's rpcbind daemon.  RPC services
+ * invoke this function once for each [program, version, address,
+ * netid] tuple they wish to advertise.
+ *
+ * Callers may also unregister RPC services that are registered at a
+ * specific address by setting the port number in @address to zero.
+ * They may unregister all registered protocol families at once for
+ * a service by passing a NULL @address argument.  If @netid is ""
+ * then all netids for [program, version, address] are unregistered.
+ *
+ * This function uses rpcbind protocol version 4 to contact the
+ * local rpcbind daemon.  The local rpcbind daemon must support
+ * version 4 of the rpcbind protocol in order for these functions
+ * to register a service successfully.
+ *
+ * Supported netids include "udp" and "tcp" for UDP and TCP over
+ * IPv4, and "udp6" and "tcp6" for UDP and TCP over IPv6,
+ * respectively.
+ *
+ * The contents of @address determine the address family and the
+ * port to be registered.  The usual practice is to pass INADDR_ANY
+ * as the raw address, but specifying a non-zero address is also
+ * supported by this API if the caller wishes to advertise an RPC
+ * service on a specific network interface.
+ *
+ * Note that passing in INADDR_ANY does not create the same service
+ * registration as IN6ADDR_ANY.  The former advertises an RPC
+ * service on any IPv4 address, but not on IPv6.  The latter
+ * advertises the service on all IPv4 and IPv6 addresses.
+ */
+int rpcb_v4_register(struct net *net, const u32 program, const u32 version,
+		     const struct sockaddr *address, const char *netid)
+{
+	struct rpcbind_args map = {
+		.r_prog		= program,
+		.r_vers		= version,
+		.r_netid	= netid,
+		.r_owner	= RPCB_OWNER_STRING,
+	};
+	struct rpc_message msg = {
+		.rpc_argp	= &map,
+	};
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+	if (sn->rpcb_local_clnt4 == NULL)
+		return -EPROTONOSUPPORT;
+
+	if (address == NULL)
+		return rpcb_unregister_all_protofamilies(sn, &msg);
+
+	trace_rpcb_register(map.r_prog, map.r_vers, map.r_addr, map.r_netid);
+
+	switch (address->sa_family) {
+	case AF_INET:
+		return rpcb_register_inet4(sn, address, &msg);
+	case AF_INET6:
+		return rpcb_register_inet6(sn, address, &msg);
+	}
+
+	return -EAFNOSUPPORT;
+}
+
+static struct rpc_task *rpcb_call_async(struct rpc_clnt *rpcb_clnt,
+		struct rpcbind_args *map, const struct rpc_procinfo *proc)
+{
+	struct rpc_message msg = {
+		.rpc_proc = proc,
+		.rpc_argp = map,
+		.rpc_resp = map,
+	};
+	struct rpc_task_setup task_setup_data = {
+		.rpc_client = rpcb_clnt,
+		.rpc_message = &msg,
+		.callback_ops = &rpcb_getport_ops,
+		.callback_data = map,
+		.flags = RPC_TASK_ASYNC | RPC_TASK_SOFTCONN,
+	};
+
+	return rpc_run_task(&task_setup_data);
+}
+
+/*
+ * In the case where rpc clients have been cloned, we want to make
+ * sure that we use the program number/version etc of the actual
+ * owner of the xprt. To do so, we walk back up the tree of parents
+ * to find whoever created the transport and/or whoever has the
+ * autobind flag set.
+ */
+static struct rpc_clnt *rpcb_find_transport_owner(struct rpc_clnt *clnt)
+{
+	struct rpc_clnt *parent = clnt->cl_parent;
+	struct rpc_xprt_switch *xps = rcu_access_pointer(clnt->cl_xpi.xpi_xpswitch);
+
+	while (parent != clnt) {
+		if (rcu_access_pointer(parent->cl_xpi.xpi_xpswitch) != xps)
+			break;
+		if (clnt->cl_autobind)
+			break;
+		clnt = parent;
+		parent = parent->cl_parent;
+	}
+	return clnt;
+}
+
+/**
+ * rpcb_getport_async - obtain the port for a given RPC service on a given host
+ * @task: task that is waiting for portmapper request
+ *
+ * This one can be called for an ongoing RPC request, and can be used in
+ * an async (rpciod) context.
+ */
+void rpcb_getport_async(struct rpc_task *task)
+{
+	struct rpc_clnt *clnt;
+	const struct rpc_procinfo *proc;
+	u32 bind_version;
+	struct rpc_xprt *xprt;
+	struct rpc_clnt	*rpcb_clnt;
+	struct rpcbind_args *map;
+	struct rpc_task	*child;
+	struct sockaddr_storage addr;
+	struct sockaddr *sap = (struct sockaddr *)&addr;
+	size_t salen;
+	int status;
+
+	rcu_read_lock();
+	clnt = rpcb_find_transport_owner(task->tk_client);
+	rcu_read_unlock();
+	xprt = xprt_get(task->tk_xprt);
+
+	/* Put self on the wait queue to ensure we get notified if
+	 * some other task is already attempting to bind the port */
+	rpc_sleep_on_timeout(&xprt->binding, task,
+			NULL, jiffies + xprt->bind_timeout);
+
+	if (xprt_test_and_set_binding(xprt)) {
+		xprt_put(xprt);
+		return;
+	}
+
+	/* Someone else may have bound if we slept */
+	if (xprt_bound(xprt)) {
+		status = 0;
+		goto bailout_nofree;
+	}
+
+	/* Parent transport's destination address */
+	salen = rpc_peeraddr(clnt, sap, sizeof(addr));
+
+	/* Don't ever use rpcbind v2 for AF_INET6 requests */
+	switch (sap->sa_family) {
+	case AF_INET:
+		proc = rpcb_next_version[xprt->bind_index].rpc_proc;
+		bind_version = rpcb_next_version[xprt->bind_index].rpc_vers;
+		break;
+	case AF_INET6:
+		proc = rpcb_next_version6[xprt->bind_index].rpc_proc;
+		bind_version = rpcb_next_version6[xprt->bind_index].rpc_vers;
+		break;
+	default:
+		status = -EAFNOSUPPORT;
+		goto bailout_nofree;
+	}
+	if (proc == NULL) {
+		xprt->bind_index = 0;
+		status = -EPFNOSUPPORT;
+		goto bailout_nofree;
+	}
+
+	trace_rpcb_getport(clnt, task, bind_version);
+
+	rpcb_clnt = rpcb_create(xprt->xprt_net,
+				clnt->cl_nodename,
+				xprt->servername, sap, salen,
+				xprt->prot, bind_version,
+				clnt->cl_cred,
+				task->tk_client->cl_timeout);
+	if (IS_ERR(rpcb_clnt)) {
+		status = PTR_ERR(rpcb_clnt);
+		goto bailout_nofree;
+	}
+
+	map = kzalloc(sizeof(struct rpcbind_args), rpc_task_gfp_mask());
+	if (!map) {
+		status = -ENOMEM;
+		goto bailout_release_client;
+	}
+	map->r_prog = clnt->cl_prog;
+	map->r_vers = clnt->cl_vers;
+	map->r_prot = xprt->prot;
+	map->r_port = 0;
+	map->r_xprt = xprt;
+	map->r_status = -EIO;
+
+	switch (bind_version) {
+	case RPCBVERS_4:
+	case RPCBVERS_3:
+		map->r_netid = xprt->address_strings[RPC_DISPLAY_NETID];
+		map->r_addr = rpc_sockaddr2uaddr(sap, rpc_task_gfp_mask());
+		if (!map->r_addr) {
+			status = -ENOMEM;
+			goto bailout_free_args;
+		}
+		map->r_owner = "";
+		break;
+	case RPCBVERS_2:
+		map->r_addr = NULL;
+		break;
+	default:
+		BUG();
+	}
+
+	child = rpcb_call_async(rpcb_clnt, map, proc);
+	rpc_release_client(rpcb_clnt);
+	if (IS_ERR(child)) {
+		/* rpcb_map_release() has freed the arguments */
+		return;
+	}
+
+	xprt->stat.bind_count++;
+	rpc_put_task(child);
+	return;
+
+bailout_free_args:
+	kfree(map);
+bailout_release_client:
+	rpc_release_client(rpcb_clnt);
+bailout_nofree:
+	rpcb_wake_rpcbind_waiters(xprt, status);
+	task->tk_status = status;
+	xprt_put(xprt);
+}
+EXPORT_SYMBOL_GPL(rpcb_getport_async);
+
+/*
+ * Rpcbind child task calls this callback via tk_exit.
+ */
+static void rpcb_getport_done(struct rpc_task *child, void *data)
+{
+	struct rpcbind_args *map = data;
+	struct rpc_xprt *xprt = map->r_xprt;
+
+	map->r_status = child->tk_status;
+
+	/* Garbage reply: retry with a lesser rpcbind version */
+	if (map->r_status == -EIO)
+		map->r_status = -EPROTONOSUPPORT;
+
+	/* rpcbind server doesn't support this rpcbind protocol version */
+	if (map->r_status == -EPROTONOSUPPORT)
+		xprt->bind_index++;
+
+	if (map->r_status < 0) {
+		/* rpcbind server not available on remote host? */
+		map->r_port = 0;
+
+	} else if (map->r_port == 0) {
+		/* Requested RPC service wasn't registered on remote host */
+		map->r_status = -EACCES;
+	} else {
+		/* Succeeded */
+		map->r_status = 0;
+	}
+
+	trace_rpcb_setport(child, map->r_status, map->r_port);
+	xprt->ops->set_port(xprt, map->r_port);
+	if (map->r_port)
+		xprt_set_bound(xprt);
+}
+
+/*
+ * XDR functions for rpcbind
+ */
+
+static void rpcb_enc_mapping(struct rpc_rqst *req, struct xdr_stream *xdr,
+			     const void *data)
+{
+	const struct rpcbind_args *rpcb = data;
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, RPCB_mappingargs_sz << 2);
+	*p++ = cpu_to_be32(rpcb->r_prog);
+	*p++ = cpu_to_be32(rpcb->r_vers);
+	*p++ = cpu_to_be32(rpcb->r_prot);
+	*p   = cpu_to_be32(rpcb->r_port);
+}
+
+static int rpcb_dec_getport(struct rpc_rqst *req, struct xdr_stream *xdr,
+			    void *data)
+{
+	struct rpcbind_args *rpcb = data;
+	unsigned long port;
+	__be32 *p;
+
+	rpcb->r_port = 0;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(p == NULL))
+		return -EIO;
+
+	port = be32_to_cpup(p);
+	if (unlikely(port > USHRT_MAX))
+		return -EIO;
+
+	rpcb->r_port = port;
+	return 0;
+}
+
+static int rpcb_dec_set(struct rpc_rqst *req, struct xdr_stream *xdr,
+			void *data)
+{
+	unsigned int *boolp = data;
+	__be32 *p;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(p == NULL))
+		return -EIO;
+
+	*boolp = 0;
+	if (*p != xdr_zero)
+		*boolp = 1;
+	return 0;
+}
+
+static void encode_rpcb_string(struct xdr_stream *xdr, const char *string,
+			       const u32 maxstrlen)
+{
+	__be32 *p;
+	u32 len;
+
+	len = strlen(string);
+	WARN_ON_ONCE(len > maxstrlen);
+	if (len > maxstrlen)
+		/* truncate and hope for the best */
+		len = maxstrlen;
+	p = xdr_reserve_space(xdr, 4 + len);
+	xdr_encode_opaque(p, string, len);
+}
+
+static void rpcb_enc_getaddr(struct rpc_rqst *req, struct xdr_stream *xdr,
+			     const void *data)
+{
+	const struct rpcbind_args *rpcb = data;
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, (RPCB_program_sz + RPCB_version_sz) << 2);
+	*p++ = cpu_to_be32(rpcb->r_prog);
+	*p = cpu_to_be32(rpcb->r_vers);
+
+	encode_rpcb_string(xdr, rpcb->r_netid, RPCBIND_MAXNETIDLEN);
+	encode_rpcb_string(xdr, rpcb->r_addr, RPCBIND_MAXUADDRLEN);
+	encode_rpcb_string(xdr, rpcb->r_owner, RPCB_MAXOWNERLEN);
+}
+
+static int rpcb_dec_getaddr(struct rpc_rqst *req, struct xdr_stream *xdr,
+			    void *data)
+{
+	struct rpcbind_args *rpcb = data;
+	struct sockaddr_storage address;
+	struct sockaddr *sap = (struct sockaddr *)&address;
+	__be32 *p;
+	u32 len;
+
+	rpcb->r_port = 0;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(p == NULL))
+		goto out_fail;
+	len = be32_to_cpup(p);
+
+	/*
+	 * If the returned universal address is a null string,
+	 * the requested RPC service was not registered.
+	 */
+	if (len == 0)
+		return 0;
+
+	if (unlikely(len > RPCBIND_MAXUADDRLEN))
+		goto out_fail;
+
+	p = xdr_inline_decode(xdr, len);
+	if (unlikely(p == NULL))
+		goto out_fail;
+
+	if (rpc_uaddr2sockaddr(req->rq_xprt->xprt_net, (char *)p, len,
+				sap, sizeof(address)) == 0)
+		goto out_fail;
+	rpcb->r_port = rpc_get_port(sap);
+
+	return 0;
+
+out_fail:
+	return -EIO;
+}
+
+/*
+ * Not all rpcbind procedures described in RFC 1833 are implemented
+ * since the Linux kernel RPC code requires only these.
+ */
+
+static const struct rpc_procinfo rpcb_procedures2[] = {
+	[RPCBPROC_SET] = {
+		.p_proc		= RPCBPROC_SET,
+		.p_encode	= rpcb_enc_mapping,
+		.p_decode	= rpcb_dec_set,
+		.p_arglen	= RPCB_mappingargs_sz,
+		.p_replen	= RPCB_setres_sz,
+		.p_statidx	= RPCBPROC_SET,
+		.p_timer	= 0,
+		.p_name		= "SET",
+	},
+	[RPCBPROC_UNSET] = {
+		.p_proc		= RPCBPROC_UNSET,
+		.p_encode	= rpcb_enc_mapping,
+		.p_decode	= rpcb_dec_set,
+		.p_arglen	= RPCB_mappingargs_sz,
+		.p_replen	= RPCB_setres_sz,
+		.p_statidx	= RPCBPROC_UNSET,
+		.p_timer	= 0,
+		.p_name		= "UNSET",
+	},
+	[RPCBPROC_GETPORT] = {
+		.p_proc		= RPCBPROC_GETPORT,
+		.p_encode	= rpcb_enc_mapping,
+		.p_decode	= rpcb_dec_getport,
+		.p_arglen	= RPCB_mappingargs_sz,
+		.p_replen	= RPCB_getportres_sz,
+		.p_statidx	= RPCBPROC_GETPORT,
+		.p_timer	= 0,
+		.p_name		= "GETPORT",
+	},
+};
+
+static const struct rpc_procinfo rpcb_procedures3[] = {
+	[RPCBPROC_SET] = {
+		.p_proc		= RPCBPROC_SET,
+		.p_encode	= rpcb_enc_getaddr,
+		.p_decode	= rpcb_dec_set,
+		.p_arglen	= RPCB_getaddrargs_sz,
+		.p_replen	= RPCB_setres_sz,
+		.p_statidx	= RPCBPROC_SET,
+		.p_timer	= 0,
+		.p_name		= "SET",
+	},
+	[RPCBPROC_UNSET] = {
+		.p_proc		= RPCBPROC_UNSET,
+		.p_encode	= rpcb_enc_getaddr,
+		.p_decode	= rpcb_dec_set,
+		.p_arglen	= RPCB_getaddrargs_sz,
+		.p_replen	= RPCB_setres_sz,
+		.p_statidx	= RPCBPROC_UNSET,
+		.p_timer	= 0,
+		.p_name		= "UNSET",
+	},
+	[RPCBPROC_GETADDR] = {
+		.p_proc		= RPCBPROC_GETADDR,
+		.p_encode	= rpcb_enc_getaddr,
+		.p_decode	= rpcb_dec_getaddr,
+		.p_arglen	= RPCB_getaddrargs_sz,
+		.p_replen	= RPCB_getaddrres_sz,
+		.p_statidx	= RPCBPROC_GETADDR,
+		.p_timer	= 0,
+		.p_name		= "GETADDR",
+	},
+};
+
+static const struct rpc_procinfo rpcb_procedures4[] = {
+	[RPCBPROC_SET] = {
+		.p_proc		= RPCBPROC_SET,
+		.p_encode	= rpcb_enc_getaddr,
+		.p_decode	= rpcb_dec_set,
+		.p_arglen	= RPCB_getaddrargs_sz,
+		.p_replen	= RPCB_setres_sz,
+		.p_statidx	= RPCBPROC_SET,
+		.p_timer	= 0,
+		.p_name		= "SET",
+	},
+	[RPCBPROC_UNSET] = {
+		.p_proc		= RPCBPROC_UNSET,
+		.p_encode	= rpcb_enc_getaddr,
+		.p_decode	= rpcb_dec_set,
+		.p_arglen	= RPCB_getaddrargs_sz,
+		.p_replen	= RPCB_setres_sz,
+		.p_statidx	= RPCBPROC_UNSET,
+		.p_timer	= 0,
+		.p_name		= "UNSET",
+	},
+	[RPCBPROC_GETADDR] = {
+		.p_proc		= RPCBPROC_GETADDR,
+		.p_encode	= rpcb_enc_getaddr,
+		.p_decode	= rpcb_dec_getaddr,
+		.p_arglen	= RPCB_getaddrargs_sz,
+		.p_replen	= RPCB_getaddrres_sz,
+		.p_statidx	= RPCBPROC_GETADDR,
+		.p_timer	= 0,
+		.p_name		= "GETADDR",
+	},
+};
+
+static const struct rpcb_info rpcb_next_version[] = {
+	{
+		.rpc_vers	= RPCBVERS_2,
+		.rpc_proc	= &rpcb_procedures2[RPCBPROC_GETPORT],
+	},
+	{
+		.rpc_proc	= NULL,
+	},
+};
+
+static const struct rpcb_info rpcb_next_version6[] = {
+	{
+		.rpc_vers	= RPCBVERS_4,
+		.rpc_proc	= &rpcb_procedures4[RPCBPROC_GETADDR],
+	},
+	{
+		.rpc_vers	= RPCBVERS_3,
+		.rpc_proc	= &rpcb_procedures3[RPCBPROC_GETADDR],
+	},
+	{
+		.rpc_proc	= NULL,
+	},
+};
+
+static unsigned int rpcb_version2_counts[ARRAY_SIZE(rpcb_procedures2)];
+static const struct rpc_version rpcb_version2 = {
+	.number		= RPCBVERS_2,
+	.nrprocs	= ARRAY_SIZE(rpcb_procedures2),
+	.procs		= rpcb_procedures2,
+	.counts		= rpcb_version2_counts,
+};
+
+static unsigned int rpcb_version3_counts[ARRAY_SIZE(rpcb_procedures3)];
+static const struct rpc_version rpcb_version3 = {
+	.number		= RPCBVERS_3,
+	.nrprocs	= ARRAY_SIZE(rpcb_procedures3),
+	.procs		= rpcb_procedures3,
+	.counts		= rpcb_version3_counts,
+};
+
+static unsigned int rpcb_version4_counts[ARRAY_SIZE(rpcb_procedures4)];
+static const struct rpc_version rpcb_version4 = {
+	.number		= RPCBVERS_4,
+	.nrprocs	= ARRAY_SIZE(rpcb_procedures4),
+	.procs		= rpcb_procedures4,
+	.counts		= rpcb_version4_counts,
+};
+
+static const struct rpc_version *rpcb_version[] = {
+	NULL,
+	NULL,
+	&rpcb_version2,
+	&rpcb_version3,
+	&rpcb_version4
+};
+
+static struct rpc_stat rpcb_stats;
+
+static const struct rpc_program rpcb_program = {
+	.name		= "rpcbind",
+	.number		= RPCBIND_PROGRAM,
+	.nrvers		= ARRAY_SIZE(rpcb_version),
+	.version	= rpcb_version,
+	.stats		= &rpcb_stats,
+};