/*
   * 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/sunrpc/svc.h>
  #include <linux/sunrpc/svcsock.h>
  #include <linux/nfs_fs.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"

  
  #define NFSDBG_FACILITY NFSDBG_CALLBACK
  
  struct nfs_callback_data {
  	unsigned int users;

  	struct svc_serv *serv;

  	struct svc_rqst *rqst;

  	struct task_struct *task;

  };

  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;

  unsigned int nfs_callback_set_tcpport;

  unsigned short nfs_callback_tcpport;

  unsigned short nfs_callback_tcpport6;

  #define NFS_CALLBACK_MAXPORTNR (65535U)

  static int param_set_portnr(const char *val, const struct kernel_param *kp)

  {

  	unsigned long num;
  	int ret;
  
  	if (!val)
  		return -EINVAL;
  	ret = strict_strtoul(val, 0, &num);
  	if (ret == -EINVAL || num > NFS_CALLBACK_MAXPORTNR)

  		return -EINVAL;

  	*((unsigned int *)kp->arg) = num;

  	return 0;
  }

  static struct kernel_param_ops param_ops_portnr = {
  	.set = param_set_portnr,
  	.get = param_get_uint,
  };

  #define param_check_portnr(name, p) __param_check(name, p, unsigned int);
  
  module_param_named(callback_tcpport, nfs_callback_set_tcpport, portnr, 0644);

  
  /*

   * This is the NFSv4 callback kernel thread.

   */

  static int

  nfs4_callback_svc(void *vrqstp)

  {

  	int err, preverr = 0;

  	struct svc_rqst *rqstp = vrqstp;

  	set_freezable();

  	while (!kthread_should_stop()) {

  		/*
  		 * Listen for a request on the socket
  		 */

  		err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);

  		if (err == -EAGAIN || err == -EINTR) {
  			preverr = err;

  			continue;

  		}

  		if (err < 0) {

  			if (err != preverr) {
  				printk(KERN_WARNING "%s: unexpected error "
  					"from svc_recv (%d)
  ", __func__, err);
  				preverr = err;
  			}
  			schedule_timeout_uninterruptible(HZ);
  			continue;

  		}

  		preverr = err;

  		svc_process(rqstp);

  	}

  	return 0;

  }
  
  /*

   * Prepare to bring up the NFSv4 callback service

   */

  struct svc_rqst *
  nfs4_callback_up(struct svc_serv *serv)

  {

  	int ret;

  	ret = svc_create_xprt(serv, "tcp", &init_net, PF_INET,

  				nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);

  	if (ret <= 0)

  		goto out_err;

  	nfs_callback_tcpport = ret;

  	dprintk("NFS: Callback listener port = %u (af %u)
  ",

  			nfs_callback_tcpport, PF_INET);

  	ret = svc_create_xprt(serv, "tcp", &init_net, PF_INET6,

  				nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
  	if (ret > 0) {
  		nfs_callback_tcpport6 = ret;
  		dprintk("NFS: Callback listener port = %u (af %u)
  ",
  				nfs_callback_tcpport6, PF_INET6);

  	} else if (ret == -EAFNOSUPPORT)
  		ret = 0;
  	else

  		goto out_err;

  	return svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);

  
  out_err:
  	if (ret == 0)
  		ret = -ENOMEM;
  	return ERR_PTR(ret);
  }

  #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_should_stop()) {
  		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);
  			dprintk("Invoking bc_svc_process()
  ");
  			error = bc_svc_process(serv, req, rqstp);
  			dprintk("bc_svc_process() returned w/ error code= %d
  ",
  				error);
  		} else {
  			spin_unlock_bh(&serv->sv_cb_lock);
  			schedule();
  		}
  		finish_wait(&serv->sv_cb_waitq, &wq);
  	}

  	return 0;
  }
  
  /*
   * Bring up the NFSv4.1 callback service
   */
  struct svc_rqst *
  nfs41_callback_up(struct svc_serv *serv, struct rpc_xprt *xprt)
  {

  	struct svc_rqst *rqstp;
  	int ret;

  	/*
  	 * Create an svc_sock for the back channel service that shares the
  	 * fore channel connection.
  	 * Returns the input port (0) and sets the svc_serv bc_xprt on success
  	 */
  	ret = svc_create_xprt(serv, "tcp-bc", &init_net, PF_INET, 0,
  			      SVC_SOCK_ANONYMOUS);
  	if (ret < 0) {
  		rqstp = ERR_PTR(ret);

  		goto out;

  	}

  	/*
  	 * Save the svc_serv in the transport so that it can
  	 * be referenced when the session backchannel is initialized
  	 */
  	xprt->bc_serv = serv;
  
  	INIT_LIST_HEAD(&serv->sv_cb_list);
  	spin_lock_init(&serv->sv_cb_lock);
  	init_waitqueue_head(&serv->sv_cb_waitq);

  	rqstp = svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);

  	if (IS_ERR(rqstp)) {

  		svc_xprt_put(serv->sv_bc_xprt);
  		serv->sv_bc_xprt = NULL;

  	}

  out:

  	dprintk("--> %s return %ld
  ", __func__,
  		IS_ERR(rqstp) ? PTR_ERR(rqstp) : 0);

  	return rqstp;

  }
  
  static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
  		struct svc_serv *serv, struct rpc_xprt *xprt,
  		struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
  {
  	if (minorversion) {
  		*rqstpp = nfs41_callback_up(serv, xprt);
  		*callback_svc = nfs41_callback_svc;
  	}
  	return minorversion;
  }
  
  static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
  		struct nfs_callback_data *cb_info)
  {
  	if (minorversion)
  		xprt->bc_serv = cb_info->serv;
  }
  #else
  static inline int nfs_minorversion_callback_svc_setup(u32 minorversion,
  		struct svc_serv *serv, struct rpc_xprt *xprt,
  		struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
  {
  	return 0;
  }
  
  static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
  		struct nfs_callback_data *cb_info)
  {
  }
  #endif /* CONFIG_NFS_V4_1 */

  /*
   * 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 = NULL;
  	struct svc_rqst *rqstp;
  	int (*callback_svc)(void *vrqstp);

  	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];

  	char svc_name[12];
  	int ret = 0;

  	int minorversion_setup;

  
  	mutex_lock(&nfs_callback_mutex);

  	if (cb_info->users++ || cb_info->task != NULL) {
  		nfs_callback_bc_serv(minorversion, xprt, cb_info);

  		goto out;

  	}

  	serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
  	if (!serv) {
  		ret = -ENOMEM;
  		goto out_err;
  	}

  	minorversion_setup =  nfs_minorversion_callback_svc_setup(minorversion,
  					serv, xprt, &rqstp, &callback_svc);
  	if (!minorversion_setup) {
  		/* v4.0 callback setup */

  		rqstp = nfs4_callback_up(serv);
  		callback_svc = nfs4_callback_svc;

  	}
  
  	if (IS_ERR(rqstp)) {
  		ret = PTR_ERR(rqstp);

  		goto out_err;

  	}
  
  	svc_sock_update_bufs(serv);

  	sprintf(svc_name, "nfsv4.%u-svc", minorversion);

  	cb_info->serv = serv;
  	cb_info->rqst = rqstp;
  	cb_info->task = kthread_run(callback_svc, cb_info->rqst, svc_name);
  	if (IS_ERR(cb_info->task)) {
  		ret = PTR_ERR(cb_info->task);
  		svc_exit_thread(cb_info->rqst);
  		cb_info->rqst = NULL;
  		cb_info->task = NULL;

  		goto out_err;
  	}

  out:

  	/*
  	 * 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.
  	 */
  	if (serv)
  		svc_destroy(serv);

  	mutex_unlock(&nfs_callback_mutex);

  	return ret;

  out_err:

  	dprintk("NFS: Couldn't create callback socket or server thread; "
  		"err = %d
  ", ret);

  	cb_info->users--;

  	goto out;
  }
  
  /*

   * Kill the callback thread if it's no longer being used.

   */

  void nfs_callback_down(int minorversion)

  {

  	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];

  	mutex_lock(&nfs_callback_mutex);

  	cb_info->users--;
  	if (cb_info->users == 0 && cb_info->task != NULL) {
  		kthread_stop(cb_info->task);
  		svc_exit_thread(cb_info->rqst);
  		cb_info->serv = NULL;
  		cb_info->rqst = NULL;
  		cb_info->task = 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)

  {
  	struct rpc_clnt *r = clp->cl_rpcclient;
  	char *p = svc_gss_principal(rqstp);

  	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;

  
  	/* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
  
  	if (memcmp(p, "nfs@", 4) != 0)

  		return 0;

  	p += 4;
  	if (strcmp(p, r->cl_server) != 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. Drop 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_DROP;
  		break;
  	case RPC_AUTH_GSS:
  		/* No RPC_AUTH_GSS support yet in NFSv4.1 */
  		 if (svc_is_backchannel(rqstp))
  			return SVC_DROP;

  	}

  	return SVC_OK;

  }
  
  /*
   * Define NFS4 callback program
   */

  static 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,
  };