[mirror_ubuntu-jammy-kernel.git] / fs / nfs / callback.c

// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/nfs/callback.c
 *
 * Copyright (C) 2004 Trond Myklebust
 *
 * NFSv4 callback handling
 */

#include <linux/completion.h>
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/nfs_fs.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/bc_xprt.h>

#include <net/inet_sock.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "internal.h"
#include "netns.h"

#define NFSDBG_FACILITY NFSDBG_CALLBACK

struct nfs_callback_data {
	unsigned int users;
	struct svc_serv *serv;
};

static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
static DEFINE_MUTEX(nfs_callback_mutex);
static struct svc_program nfs4_callback_program;

static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net)
{
	const struct cred *cred = current_cred();
	int ret;
	struct nfs_net *nn = net_generic(net, nfs_net_id);

	ret = svc_create_xprt(serv, "tcp", net, PF_INET,
				nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
				cred);
	if (ret <= 0)
		goto out_err;
	nn->nfs_callback_tcpport = ret;
	dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
		nn->nfs_callback_tcpport, PF_INET, net->ns.inum);

	ret = svc_create_xprt(serv, "tcp", net, PF_INET6,
				nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
				cred);
	if (ret > 0) {
		nn->nfs_callback_tcpport6 = ret;
		dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
			nn->nfs_callback_tcpport6, PF_INET6, net->ns.inum);
	} else if (ret != -EAFNOSUPPORT)
		goto out_err;
	return 0;

out_err:
	return (ret) ? ret : -ENOMEM;
}

/*
 * This is the NFSv4 callback kernel thread.
 */
static int
nfs4_callback_svc(void *vrqstp)
{
	int err;
	struct svc_rqst *rqstp = vrqstp;

	set_freezable();

	while (!kthread_freezable_should_stop(NULL)) {

		if (signal_pending(current))
			flush_signals(current);
		/*
		 * Listen for a request on the socket
		 */
		err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
		if (err == -EAGAIN || err == -EINTR)
			continue;
		svc_process(rqstp);
	}
	svc_exit_thread(rqstp);
	module_put_and_exit(0);
	return 0;
}

#if defined(CONFIG_NFS_V4_1)
/*
 * The callback service for NFSv4.1 callbacks
 */
static int
nfs41_callback_svc(void *vrqstp)
{
	struct svc_rqst *rqstp = vrqstp;
	struct svc_serv *serv = rqstp->rq_server;
	struct rpc_rqst *req;
	int error;
	DEFINE_WAIT(wq);

	set_freezable();

	while (!kthread_freezable_should_stop(NULL)) {

		if (signal_pending(current))
			flush_signals(current);

		prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
		spin_lock_bh(&serv->sv_cb_lock);
		if (!list_empty(&serv->sv_cb_list)) {
			req = list_first_entry(&serv->sv_cb_list,
					struct rpc_rqst, rq_bc_list);
			list_del(&req->rq_bc_list);
			spin_unlock_bh(&serv->sv_cb_lock);
			finish_wait(&serv->sv_cb_waitq, &wq);
			dprintk("Invoking bc_svc_process()\n");
			error = bc_svc_process(serv, req, rqstp);
			dprintk("bc_svc_process() returned w/ error code= %d\n",
				error);
		} else {
			spin_unlock_bh(&serv->sv_cb_lock);
			if (!kthread_should_stop())
				schedule();
			finish_wait(&serv->sv_cb_waitq, &wq);
		}
	}
	svc_exit_thread(rqstp);
	module_put_and_exit(0);
	return 0;
}

static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
		struct svc_serv *serv)
{
	if (minorversion)
		/*
		 * Save the svc_serv in the transport so that it can
		 * be referenced when the session backchannel is initialized
		 */
		xprt->bc_serv = serv;
}
#else
static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
		struct svc_serv *serv)
{
}
#endif /* CONFIG_NFS_V4_1 */

static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
				  struct svc_serv *serv)
{
	int nrservs = nfs_callback_nr_threads;
	int ret;

	nfs_callback_bc_serv(minorversion, xprt, serv);

	if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
		nrservs = NFS4_MIN_NR_CALLBACK_THREADS;

	if (serv->sv_nrthreads-1 == nrservs)
		return 0;

	ret = serv->sv_ops->svo_setup(serv, NULL, nrservs);
	if (ret) {
		serv->sv_ops->svo_setup(serv, NULL, 0);
		return ret;
	}
	dprintk("nfs_callback_up: service started\n");
	return 0;
}

static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
{
	struct nfs_net *nn = net_generic(net, nfs_net_id);

	if (--nn->cb_users[minorversion])
		return;

	dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum);
	svc_shutdown_net(serv, net);
}

static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
			       struct net *net, struct rpc_xprt *xprt)
{
	struct nfs_net *nn = net_generic(net, nfs_net_id);
	int ret;

	if (nn->cb_users[minorversion]++)
		return 0;

	dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum);

	ret = svc_bind(serv, net);
	if (ret < 0) {
		printk(KERN_WARNING "NFS: bind callback service failed\n");
		goto err_bind;
	}

	ret = 0;
	if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
		ret = nfs4_callback_up_net(serv, net);
	else if (xprt->ops->bc_setup)
		set_bc_enabled(serv);
	else
		ret = -EPROTONOSUPPORT;

	if (ret < 0) {
		printk(KERN_ERR "NFS: callback service start failed\n");
		goto err_socks;
	}
	return 0;

err_socks:
	svc_rpcb_cleanup(serv, net);
err_bind:
	nn->cb_users[minorversion]--;
	dprintk("NFS: Couldn't create callback socket: err = %d; "
			"net = %x\n", ret, net->ns.inum);
	return ret;
}

static const struct svc_serv_ops nfs40_cb_sv_ops = {
	.svo_function		= nfs4_callback_svc,
	.svo_enqueue_xprt	= svc_xprt_do_enqueue,
	.svo_setup		= svc_set_num_threads_sync,
	.svo_module		= THIS_MODULE,
};
#if defined(CONFIG_NFS_V4_1)
static const struct svc_serv_ops nfs41_cb_sv_ops = {
	.svo_function		= nfs41_callback_svc,
	.svo_enqueue_xprt	= svc_xprt_do_enqueue,
	.svo_setup		= svc_set_num_threads_sync,
	.svo_module		= THIS_MODULE,
};

static const struct svc_serv_ops *nfs4_cb_sv_ops[] = {
	[0] = &nfs40_cb_sv_ops,
	[1] = &nfs41_cb_sv_ops,
};
#else
static const struct svc_serv_ops *nfs4_cb_sv_ops[] = {
	[0] = &nfs40_cb_sv_ops,
	[1] = NULL,
};
#endif

static struct svc_serv *nfs_callback_create_svc(int minorversion)
{
	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
	const struct svc_serv_ops *sv_ops;
	struct svc_serv *serv;

	/*
	 * Check whether we're already up and running.
	 */
	if (cb_info->serv) {
		/*
		 * Note: increase service usage, because later in case of error
		 * svc_destroy() will be called.
		 */
		svc_get(cb_info->serv);
		return cb_info->serv;
	}

	switch (minorversion) {
	case 0:
		sv_ops = nfs4_cb_sv_ops[0];
		break;
	default:
		sv_ops = nfs4_cb_sv_ops[1];
	}

	if (sv_ops == NULL)
		return ERR_PTR(-ENOTSUPP);

	/*
	 * Sanity check: if there's no task,
	 * we should be the first user ...
	 */
	if (cb_info->users)
		printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
			cb_info->users);

	serv = svc_create_pooled(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, sv_ops);
	if (!serv) {
		printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
		return ERR_PTR(-ENOMEM);
	}
	cb_info->serv = serv;
	/* As there is only one thread we need to over-ride the
	 * default maximum of 80 connections
	 */
	serv->sv_maxconn = 1024;
	dprintk("nfs_callback_create_svc: service created\n");
	return serv;
}

/*
 * Bring up the callback thread if it is not already up.
 */
int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
{
	struct svc_serv *serv;
	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
	int ret;
	struct net *net = xprt->xprt_net;

	mutex_lock(&nfs_callback_mutex);

	serv = nfs_callback_create_svc(minorversion);
	if (IS_ERR(serv)) {
		ret = PTR_ERR(serv);
		goto err_create;
	}

	ret = nfs_callback_up_net(minorversion, serv, net, xprt);
	if (ret < 0)
		goto err_net;

	ret = nfs_callback_start_svc(minorversion, xprt, serv);
	if (ret < 0)
		goto err_start;

	cb_info->users++;
	/*
	 * svc_create creates the svc_serv with sv_nrthreads == 1, and then
	 * svc_prepare_thread increments that. So we need to call svc_destroy
	 * on both success and failure so that the refcount is 1 when the
	 * thread exits.
	 */
err_net:
	if (!cb_info->users)
		cb_info->serv = NULL;
	svc_destroy(serv);
err_create:
	mutex_unlock(&nfs_callback_mutex);
	return ret;

err_start:
	nfs_callback_down_net(minorversion, serv, net);
	dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
	goto err_net;
}

/*
 * Kill the callback thread if it's no longer being used.
 */
void nfs_callback_down(int minorversion, struct net *net)
{
	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
	struct svc_serv *serv;

	mutex_lock(&nfs_callback_mutex);
	serv = cb_info->serv;
	nfs_callback_down_net(minorversion, serv, net);
	cb_info->users--;
	if (cb_info->users == 0) {
		svc_get(serv);
		serv->sv_ops->svo_setup(serv, NULL, 0);
		svc_destroy(serv);
		dprintk("nfs_callback_down: service destroyed\n");
		cb_info->serv = NULL;
	}
	mutex_unlock(&nfs_callback_mutex);
}

/* Boolean check of RPC_AUTH_GSS principal */
int
check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
{
	char *p = rqstp->rq_cred.cr_principal;

	if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
		return 1;

	/* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
	if (clp->cl_minorversion != 0)
		return 0;
	/*
	 * It might just be a normal user principal, in which case
	 * userspace won't bother to tell us the name at all.
	 */
	if (p == NULL)
		return 0;

	/*
	 * Did we get the acceptor from userland during the SETCLIENID
	 * negotiation?
	 */
	if (clp->cl_acceptor)
		return !strcmp(p, clp->cl_acceptor);

	/*
	 * Otherwise try to verify it using the cl_hostname. Note that this
	 * doesn't work if a non-canonical hostname was used in the devname.
	 */

	/* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */

	if (memcmp(p, "nfs@", 4) != 0)
		return 0;
	p += 4;
	if (strcmp(p, clp->cl_hostname) != 0)
		return 0;
	return 1;
}

/*
 * pg_authenticate method for nfsv4 callback threads.
 *
 * The authflavor has been negotiated, so an incorrect flavor is a server
 * bug. Deny packets with incorrect authflavor.
 *
 * All other checking done after NFS decoding where the nfs_client can be
 * found in nfs4_callback_compound
 */
static int nfs_callback_authenticate(struct svc_rqst *rqstp)
{
	switch (rqstp->rq_authop->flavour) {
	case RPC_AUTH_NULL:
		if (rqstp->rq_proc != CB_NULL)
			return SVC_DENIED;
		break;
	case RPC_AUTH_GSS:
		/* No RPC_AUTH_GSS support yet in NFSv4.1 */
		 if (svc_is_backchannel(rqstp))
			return SVC_DENIED;
	}
	return SVC_OK;
}

/*
 * Define NFS4 callback program
 */
static const struct svc_version *nfs4_callback_version[] = {
	[1] = &nfs4_callback_version1,
	[4] = &nfs4_callback_version4,
};

static struct svc_stat nfs4_callback_stats;

static struct svc_program nfs4_callback_program = {
	.pg_prog = NFS4_CALLBACK,			/* RPC service number */
	.pg_nvers = ARRAY_SIZE(nfs4_callback_version),	/* Number of entries */
	.pg_vers = nfs4_callback_version,		/* version table */
	.pg_name = "NFSv4 callback",			/* service name */
	.pg_class = "nfs",				/* authentication class */
	.pg_stats = &nfs4_callback_stats,
	.pg_authenticate = nfs_callback_authenticate,
	.pg_init_request = svc_generic_init_request,
	.pg_rpcbind_set	= svc_generic_rpcbind_set,
};
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* linux/fs/nfs/callback.c
	4	*
	5	* Copyright (C) 2004 Trond Myklebust
	6	*
	7	* NFSv4 callback handling
	8	*/
	9
	10	#include <linux/completion.h>
	11	#include <linux/ip.h>
	12	#include <linux/module.h>
	13	#include <linux/sched/signal.h>
	14	#include <linux/sunrpc/svc.h>
	15	#include <linux/sunrpc/svcsock.h>
	16	#include <linux/nfs_fs.h>
	17	#include <linux/errno.h>
	18	#include <linux/mutex.h>
	19	#include <linux/freezer.h>
	20	#include <linux/kthread.h>
	21	#include <linux/sunrpc/svcauth_gss.h>
	22	#include <linux/sunrpc/bc_xprt.h>
	23
	24	#include <net/inet_sock.h>
	25
	26	#include "nfs4_fs.h"
	27	#include "callback.h"
	28	#include "internal.h"
	29	#include "netns.h"
	30
	31	#define NFSDBG_FACILITY NFSDBG_CALLBACK
	32
	33	struct nfs_callback_data {
	34	unsigned int users;
	35	struct svc_serv *serv;
	36	};
	37
	38	static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
	39	static DEFINE_MUTEX(nfs_callback_mutex);
	40	static struct svc_program nfs4_callback_program;
	41
	42	static int nfs4_callback_up_net(struct svc_serv serv, struct net net)
	43	{
	44	const struct cred *cred = current_cred();
	45	int ret;
	46	struct nfs_net *nn = net_generic(net, nfs_net_id);
	47
	48	ret = svc_create_xprt(serv, "tcp", net, PF_INET,
	49	nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
	50	cred);
	51	if (ret <= 0)
	52	goto out_err;
	53	nn->nfs_callback_tcpport = ret;
	54	dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
	55	nn->nfs_callback_tcpport, PF_INET, net->ns.inum);
	56
	57	ret = svc_create_xprt(serv, "tcp", net, PF_INET6,
	58	nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS,
	59	cred);
	60	if (ret > 0) {
	61	nn->nfs_callback_tcpport6 = ret;
	62	dprintk("NFS: Callback listener port = %u (af %u, net %x)\n",
	63	nn->nfs_callback_tcpport6, PF_INET6, net->ns.inum);
	64	} else if (ret != -EAFNOSUPPORT)
	65	goto out_err;
	66	return 0;
	67
	68	out_err:
	69	return (ret) ? ret : -ENOMEM;
	70	}
	71
	72	/*
	73	* This is the NFSv4 callback kernel thread.
	74	*/
	75	static int
	76	nfs4_callback_svc(void *vrqstp)
	77	{
	78	int err;
	79	struct svc_rqst *rqstp = vrqstp;
	80
	81	set_freezable();
	82
	83	while (!kthread_freezable_should_stop(NULL)) {
	84
	85	if (signal_pending(current))
	86	flush_signals(current);
	87	/*
	88	* Listen for a request on the socket
	89	*/
	90	err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
	91	if (err == -EAGAIN \|\| err == -EINTR)
	92	continue;
	93	svc_process(rqstp);
	94	}
	95	svc_exit_thread(rqstp);
	96	module_put_and_exit(0);
	97	return 0;
	98	}
	99
	100	#if defined(CONFIG_NFS_V4_1)
	101	/*
	102	* The callback service for NFSv4.1 callbacks
	103	*/
	104	static int
	105	nfs41_callback_svc(void *vrqstp)
	106	{
	107	struct svc_rqst *rqstp = vrqstp;
	108	struct svc_serv *serv = rqstp->rq_server;
	109	struct rpc_rqst *req;
	110	int error;
	111	DEFINE_WAIT(wq);
	112
	113	set_freezable();
	114
	115	while (!kthread_freezable_should_stop(NULL)) {
	116
	117	if (signal_pending(current))
	118	flush_signals(current);
	119
	120	prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
	121	spin_lock_bh(&serv->sv_cb_lock);
	122	if (!list_empty(&serv->sv_cb_list)) {
	123	req = list_first_entry(&serv->sv_cb_list,
	124	struct rpc_rqst, rq_bc_list);
	125	list_del(&req->rq_bc_list);
	126	spin_unlock_bh(&serv->sv_cb_lock);
	127	finish_wait(&serv->sv_cb_waitq, &wq);
	128	dprintk("Invoking bc_svc_process()\n");
	129	error = bc_svc_process(serv, req, rqstp);
	130	dprintk("bc_svc_process() returned w/ error code= %d\n",
	131	error);
	132	} else {
	133	spin_unlock_bh(&serv->sv_cb_lock);
	134	if (!kthread_should_stop())
	135	schedule();
	136	finish_wait(&serv->sv_cb_waitq, &wq);
	137	}
	138	}
	139	svc_exit_thread(rqstp);
	140	module_put_and_exit(0);
	141	return 0;
	142	}
	143
	144	static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
	145	struct svc_serv *serv)
	146	{
	147	if (minorversion)
	148	/*
	149	* Save the svc_serv in the transport so that it can
	150	* be referenced when the session backchannel is initialized
	151	*/
	152	xprt->bc_serv = serv;
	153	}
	154	#else
	155	static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
	156	struct svc_serv *serv)
	157	{
	158	}
	159	#endif /* CONFIG_NFS_V4_1 */
	160
	161	static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
	162	struct svc_serv *serv)
	163	{
	164	int nrservs = nfs_callback_nr_threads;
	165	int ret;
	166
	167	nfs_callback_bc_serv(minorversion, xprt, serv);
	168
	169	if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
	170	nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
	171
	172	if (serv->sv_nrthreads-1 == nrservs)
	173	return 0;
	174
	175	ret = serv->sv_ops->svo_setup(serv, NULL, nrservs);
	176	if (ret) {
	177	serv->sv_ops->svo_setup(serv, NULL, 0);
	178	return ret;
	179	}
	180	dprintk("nfs_callback_up: service started\n");
	181	return 0;
	182	}
	183
	184	static void nfs_callback_down_net(u32 minorversion, struct svc_serv serv, struct net net)
	185	{
	186	struct nfs_net *nn = net_generic(net, nfs_net_id);
	187
	188	if (--nn->cb_users[minorversion])
	189	return;
	190
	191	dprintk("NFS: destroy per-net callback data; net=%x\n", net->ns.inum);
	192	svc_shutdown_net(serv, net);
	193	}
	194
	195	static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
	196	struct net net, struct rpc_xprt xprt)
	197	{
	198	struct nfs_net *nn = net_generic(net, nfs_net_id);
	199	int ret;
	200
	201	if (nn->cb_users[minorversion]++)
	202	return 0;
	203
	204	dprintk("NFS: create per-net callback data; net=%x\n", net->ns.inum);
	205
	206	ret = svc_bind(serv, net);
	207	if (ret < 0) {
	208	printk(KERN_WARNING "NFS: bind callback service failed\n");
	209	goto err_bind;
	210	}
	211
	212	ret = 0;
	213	if (!IS_ENABLED(CONFIG_NFS_V4_1) \|\| minorversion == 0)
	214	ret = nfs4_callback_up_net(serv, net);
	215	else if (xprt->ops->bc_setup)
	216	set_bc_enabled(serv);
	217	else
	218	ret = -EPROTONOSUPPORT;
	219
	220	if (ret < 0) {
	221	printk(KERN_ERR "NFS: callback service start failed\n");
	222	goto err_socks;
	223	}
	224	return 0;
	225
	226	err_socks:
	227	svc_rpcb_cleanup(serv, net);
	228	err_bind:
	229	nn->cb_users[minorversion]--;
	230	dprintk("NFS: Couldn't create callback socket: err = %d; "
	231	"net = %x\n", ret, net->ns.inum);
	232	return ret;
	233	}
	234
	235	static const struct svc_serv_ops nfs40_cb_sv_ops = {
	236	.svo_function = nfs4_callback_svc,
	237	.svo_enqueue_xprt = svc_xprt_do_enqueue,
	238	.svo_setup = svc_set_num_threads_sync,
	239	.svo_module = THIS_MODULE,
	240	};
	241	#if defined(CONFIG_NFS_V4_1)
	242	static const struct svc_serv_ops nfs41_cb_sv_ops = {
	243	.svo_function = nfs41_callback_svc,
	244	.svo_enqueue_xprt = svc_xprt_do_enqueue,
	245	.svo_setup = svc_set_num_threads_sync,
	246	.svo_module = THIS_MODULE,
	247	};
	248
	249	static const struct svc_serv_ops *nfs4_cb_sv_ops[] = {
	250	[0] = &nfs40_cb_sv_ops,
	251	[1] = &nfs41_cb_sv_ops,
	252	};
	253	#else
	254	static const struct svc_serv_ops *nfs4_cb_sv_ops[] = {
	255	[0] = &nfs40_cb_sv_ops,
	256	[1] = NULL,
	257	};
	258	#endif
	259
	260	static struct svc_serv *nfs_callback_create_svc(int minorversion)
	261	{
	262	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
	263	const struct svc_serv_ops *sv_ops;
	264	struct svc_serv *serv;
	265
	266	/*
	267	* Check whether we're already up and running.
	268	*/
	269	if (cb_info->serv) {
	270	/*
	271	* Note: increase service usage, because later in case of error
	272	* svc_destroy() will be called.
	273	*/
	274	svc_get(cb_info->serv);
	275	return cb_info->serv;
	276	}
	277
	278	switch (minorversion) {
	279	case 0:
	280	sv_ops = nfs4_cb_sv_ops[0];
	281	break;
	282	default:
	283	sv_ops = nfs4_cb_sv_ops[1];
	284	}
	285
	286	if (sv_ops == NULL)
	287	return ERR_PTR(-ENOTSUPP);
	288
	289	/*
	290	* Sanity check: if there's no task,
	291	* we should be the first user ...
	292	*/
	293	if (cb_info->users)
	294	printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
	295	cb_info->users);
	296
	297	serv = svc_create_pooled(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, sv_ops);
	298	if (!serv) {
	299	printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
	300	return ERR_PTR(-ENOMEM);
	301	}
	302	cb_info->serv = serv;
	303	/* As there is only one thread we need to over-ride the
	304	* default maximum of 80 connections
	305	*/
	306	serv->sv_maxconn = 1024;
	307	dprintk("nfs_callback_create_svc: service created\n");
	308	return serv;
	309	}
	310
	311	/*
	312	* Bring up the callback thread if it is not already up.
	313	*/
	314	int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
	315	{
	316	struct svc_serv *serv;
	317	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
	318	int ret;
	319	struct net *net = xprt->xprt_net;
	320
	321	mutex_lock(&nfs_callback_mutex);
	322
	323	serv = nfs_callback_create_svc(minorversion);
	324	if (IS_ERR(serv)) {
	325	ret = PTR_ERR(serv);
	326	goto err_create;
	327	}
	328
	329	ret = nfs_callback_up_net(minorversion, serv, net, xprt);
	330	if (ret < 0)
	331	goto err_net;
	332
	333	ret = nfs_callback_start_svc(minorversion, xprt, serv);
	334	if (ret < 0)
	335	goto err_start;
	336
	337	cb_info->users++;
	338	/*
	339	* svc_create creates the svc_serv with sv_nrthreads == 1, and then
	340	* svc_prepare_thread increments that. So we need to call svc_destroy
	341	* on both success and failure so that the refcount is 1 when the
	342	* thread exits.
	343	*/
	344	err_net:
	345	if (!cb_info->users)
	346	cb_info->serv = NULL;
	347	svc_destroy(serv);
	348	err_create:
	349	mutex_unlock(&nfs_callback_mutex);
	350	return ret;
	351
	352	err_start:
	353	nfs_callback_down_net(minorversion, serv, net);
	354	dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
	355	goto err_net;
	356	}
	357
	358	/*
	359	* Kill the callback thread if it's no longer being used.
	360	*/
	361	void nfs_callback_down(int minorversion, struct net *net)
	362	{
	363	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
	364	struct svc_serv *serv;
	365
	366	mutex_lock(&nfs_callback_mutex);
	367	serv = cb_info->serv;
	368	nfs_callback_down_net(minorversion, serv, net);
	369	cb_info->users--;
	370	if (cb_info->users == 0) {
	371	svc_get(serv);
	372	serv->sv_ops->svo_setup(serv, NULL, 0);
	373	svc_destroy(serv);
	374	dprintk("nfs_callback_down: service destroyed\n");
	375	cb_info->serv = NULL;
	376	}
	377	mutex_unlock(&nfs_callback_mutex);
	378	}
	379
	380	/* Boolean check of RPC_AUTH_GSS principal */
	381	int
	382	check_gss_callback_principal(struct nfs_client clp, struct svc_rqst rqstp)
	383	{
	384	char *p = rqstp->rq_cred.cr_principal;
	385
	386	if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
	387	return 1;
	388
	389	/* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
	390	if (clp->cl_minorversion != 0)
	391	return 0;
	392	/*
	393	* It might just be a normal user principal, in which case
	394	* userspace won't bother to tell us the name at all.
	395	*/
	396	if (p == NULL)
	397	return 0;
	398
	399	/*
	400	* Did we get the acceptor from userland during the SETCLIENID
	401	* negotiation?
	402	*/
	403	if (clp->cl_acceptor)
	404	return !strcmp(p, clp->cl_acceptor);
	405
	406	/*
	407	* Otherwise try to verify it using the cl_hostname. Note that this
	408	* doesn't work if a non-canonical hostname was used in the devname.
	409	*/
	410
	411	/* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
	412
	413	if (memcmp(p, "nfs@", 4) != 0)
	414	return 0;
	415	p += 4;
	416	if (strcmp(p, clp->cl_hostname) != 0)
	417	return 0;
	418	return 1;
	419	}
	420
	421	/*
	422	* pg_authenticate method for nfsv4 callback threads.
	423	*
	424	* The authflavor has been negotiated, so an incorrect flavor is a server
	425	* bug. Deny packets with incorrect authflavor.
	426	*
	427	* All other checking done after NFS decoding where the nfs_client can be
	428	* found in nfs4_callback_compound
	429	*/
	430	static int nfs_callback_authenticate(struct svc_rqst *rqstp)
	431	{
	432	switch (rqstp->rq_authop->flavour) {
	433	case RPC_AUTH_NULL:
	434	if (rqstp->rq_proc != CB_NULL)
	435	return SVC_DENIED;
	436	break;
	437	case RPC_AUTH_GSS:
	438	/* No RPC_AUTH_GSS support yet in NFSv4.1 */
	439	if (svc_is_backchannel(rqstp))
	440	return SVC_DENIED;
	441	}
	442	return SVC_OK;
	443	}
	444
	445	/*
	446	* Define NFS4 callback program
	447	*/
	448	static const struct svc_version *nfs4_callback_version[] = {
	449	[1] = &nfs4_callback_version1,
	450	[4] = &nfs4_callback_version4,
	451	};
	452
	453	static struct svc_stat nfs4_callback_stats;
	454
	455	static struct svc_program nfs4_callback_program = {
	456	.pg_prog = NFS4_CALLBACK, /* RPC service number */
	457	.pg_nvers = ARRAY_SIZE(nfs4_callback_version), /* Number of entries */
	458	.pg_vers = nfs4_callback_version, /* version table */
	459	.pg_name = "NFSv4 callback", /* service name */
	460	.pg_class = "nfs", /* authentication class */
	461	.pg_stats = &nfs4_callback_stats,
	462	.pg_authenticate = nfs_callback_authenticate,
	463	.pg_init_request = svc_generic_init_request,
	464	.pg_rpcbind_set = svc_generic_rpcbind_set,
	465	};