/*
   * linux/fs/lockd/mon.c
   *
   * The kernel statd client.
   *
   * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   */
  
  #include <linux/types.h>
  #include <linux/utsname.h>
  #include <linux/kernel.h>

  #include <linux/ktime.h>

  #include <linux/slab.h>

  #include <linux/sunrpc/clnt.h>

  #include <linux/sunrpc/xprtsock.h>

  #include <linux/sunrpc/svc.h>
  #include <linux/lockd/lockd.h>

  #include <asm/unaligned.h>

  #define NLMDBG_FACILITY		NLMDBG_MONITOR

  #define NSM_PROGRAM		100024
  #define NSM_VERSION		1
  
  enum {
  	NSMPROC_NULL,
  	NSMPROC_STAT,
  	NSMPROC_MON,
  	NSMPROC_UNMON,
  	NSMPROC_UNMON_ALL,
  	NSMPROC_SIMU_CRASH,
  	NSMPROC_NOTIFY,
  };

  struct nsm_args {

  	struct nsm_private	*priv;

  	u32			prog;		/* RPC callback info */
  	u32			vers;
  	u32			proc;
  
  	char			*mon_name;
  };
  
  struct nsm_res {
  	u32			status;
  	u32			state;
  };

  static struct rpc_program	nsm_program;

  static				LIST_HEAD(nsm_handles);
  static				DEFINE_SPINLOCK(nsm_lock);

  
  /*
   * Local NSM state
   */

  u32	__read_mostly		nsm_local_state;

  int	__read_mostly		nsm_use_hostnames;

  static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
  {
  	return (struct sockaddr *)&nsm->sm_addr;
  }

  static struct rpc_clnt *nsm_create(void)
  {
  	struct sockaddr_in sin = {
  		.sin_family		= AF_INET,
  		.sin_addr.s_addr	= htonl(INADDR_LOOPBACK),
  	};
  	struct rpc_create_args args = {
  		.protocol		= XPRT_TRANSPORT_UDP,
  		.address		= (struct sockaddr *)&sin,
  		.addrsize		= sizeof(sin),
  		.servername		= "rpc.statd",
  		.program		= &nsm_program,
  		.version		= NSM_VERSION,
  		.authflavor		= RPC_AUTH_NULL,

  		.flags			= RPC_CLNT_CREATE_NOPING,

  	};
  
  	return rpc_create(&args);
  }
  
  static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res)

  {
  	struct rpc_clnt	*clnt;
  	int		status;

  	struct nsm_args args = {

  		.priv		= &nsm->sm_priv,

  		.prog		= NLM_PROGRAM,
  		.vers		= 3,
  		.proc		= NLMPROC_NSM_NOTIFY,

  		.mon_name	= nsm->sm_mon_name,

  	};

  	struct rpc_message msg = {
  		.rpc_argp	= &args,
  		.rpc_resp	= res,
  	};

  
  	clnt = nsm_create();
  	if (IS_ERR(clnt)) {
  		status = PTR_ERR(clnt);

  		dprintk("lockd: failed to create NSM upcall transport, "
  				"status=%d
  ", status);

  		goto out;
  	}

  	memset(res, 0, sizeof(*res));

  	msg.rpc_proc = &clnt->cl_procinfo[proc];
  	status = rpc_call_sync(clnt, &msg, 0);

  	if (status < 0)

  		dprintk("lockd: NSM upcall RPC failed, status=%d
  ",
  				status);

  	else
  		status = 0;

  	rpc_shutdown_client(clnt);

   out:
  	return status;
  }

  /**
   * nsm_monitor - Notify a peer in case we reboot
   * @host: pointer to nlm_host of peer to notify
   *
   * If this peer is not already monitored, this function sends an
   * upcall to the local rpc.statd to record the name/address of
   * the peer to notify in case we reboot.
   *
   * Returns zero if the peer is monitored by the local rpc.statd;
   * otherwise a negative errno value is returned.

   */

  int nsm_monitor(const struct nlm_host *host)

  {

  	struct nsm_handle *nsm = host->h_nsmhandle;

  	struct nsm_res	res;
  	int		status;

  	dprintk("lockd: nsm_monitor(%s)
  ", nsm->sm_name);

  
  	if (nsm->sm_monitored)

  		return 0;

  	/*
  	 * Choose whether to record the caller_name or IP address of
  	 * this peer in the local rpc.statd's database.
  	 */
  	nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;

  	status = nsm_mon_unmon(nsm, NSMPROC_MON, &res);

  	if (unlikely(res.status != 0))

  		status = -EIO;

  	if (unlikely(status < 0)) {

  		printk(KERN_NOTICE "lockd: cannot monitor %s
  ", nsm->sm_name);

  		return status;
  	}
  
  	nsm->sm_monitored = 1;
  	if (unlikely(nsm_local_state != res.state)) {
  		nsm_local_state = res.state;
  		dprintk("lockd: NSM state changed to %d
  ", nsm_local_state);
  	}
  	return 0;

  }

  /**
   * nsm_unmonitor - Unregister peer notification
   * @host: pointer to nlm_host of peer to stop monitoring
   *
   * If this peer is monitored, this function sends an upcall to
   * tell the local rpc.statd not to send this peer a notification
   * when we reboot.

   */

  void nsm_unmonitor(const struct nlm_host *host)

  {

  	struct nsm_handle *nsm = host->h_nsmhandle;

  	struct nsm_res	res;

  	int status;

  	if (atomic_read(&nsm->sm_count) == 1
  	 && nsm->sm_monitored && !nsm->sm_sticky) {

  		dprintk("lockd: nsm_unmonitor(%s)
  ", nsm->sm_name);

  		status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res);

  		if (res.status != 0)
  			status = -EIO;

  		if (status < 0)

  			printk(KERN_NOTICE "lockd: cannot unmonitor %s
  ",

  					nsm->sm_name);

  		else
  			nsm->sm_monitored = 0;

  	}

  }

  static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
  					      const size_t len)
  {
  	struct nsm_handle *nsm;
  
  	list_for_each_entry(nsm, &nsm_handles, sm_link)
  		if (strlen(nsm->sm_name) == len &&
  		    memcmp(nsm->sm_name, hostname, len) == 0)
  			return nsm;
  	return NULL;
  }

  static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
  {
  	struct nsm_handle *nsm;
  
  	list_for_each_entry(nsm, &nsm_handles, sm_link)

  		if (rpc_cmp_addr(nsm_addr(nsm), sap))

  			return nsm;
  	return NULL;
  }

  static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
  {
  	struct nsm_handle *nsm;
  
  	list_for_each_entry(nsm, &nsm_handles, sm_link)
  		if (memcmp(nsm->sm_priv.data, priv->data,
  					sizeof(priv->data)) == 0)
  			return nsm;
  	return NULL;
  }

  /*
   * Construct a unique cookie to match this nsm_handle to this monitored
   * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
   * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
   * requests.
   *

   * The NSM protocol requires that these cookies be unique while the
   * system is running.  We prefer a stronger requirement of making them
   * unique across reboots.  If user space bugs cause a stale cookie to
   * be sent to the kernel, it could cause the wrong host to lose its
   * lock state if cookies were not unique across reboots.
   *
   * The cookies are exposed only to local user space via loopback.  They
   * do not appear on the physical network.  If we want greater security
   * for some reason, nsm_init_private() could perform a one-way hash to
   * obscure the contents of the cookie.

   */
  static void nsm_init_private(struct nsm_handle *nsm)
  {

  	u64 *p = (u64 *)&nsm->sm_priv.data;
  	struct timespec ts;

  	s64 ns;

  
  	ktime_get_ts(&ts);

  	ns = timespec_to_ns(&ts);
  	put_unaligned(ns, p);
  	put_unaligned((unsigned long)nsm, p + 1);

  }

  static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
  					    const size_t salen,
  					    const char *hostname,
  					    const size_t hostname_len)
  {
  	struct nsm_handle *new;
  
  	new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
  	if (unlikely(new == NULL))
  		return NULL;
  
  	atomic_set(&new->sm_count, 1);
  	new->sm_name = (char *)(new + 1);
  	memcpy(nsm_addr(new), sap, salen);
  	new->sm_addrlen = salen;
  	nsm_init_private(new);

  
  	if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
  					sizeof(new->sm_addrbuf)) == 0)
  		(void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
  				"unsupported address family");

  	memcpy(new->sm_name, hostname, hostname_len);
  	new->sm_name[hostname_len] = '\0';
  
  	return new;
  }

  /**

   * nsm_get_handle - Find or create a cached nsm_handle

   * @sap: pointer to socket address of handle to find
   * @salen: length of socket address
   * @hostname: pointer to C string containing hostname to find
   * @hostname_len: length of C string

   *

   * Behavior is modulated by the global nsm_use_hostnames variable.

   *

   * Returns a cached nsm_handle after bumping its ref count, or
   * returns a fresh nsm_handle if a handle that matches @sap and/or
   * @hostname cannot be found in the handle cache.  Returns NULL if
   * an error occurs.

   */

  struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
  				  const size_t salen, const char *hostname,
  				  const size_t hostname_len)

  {

  	struct nsm_handle *cached, *new = NULL;

  	if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
  		if (printk_ratelimit()) {
  			printk(KERN_WARNING "Invalid hostname \"%.*s\" "
  					    "in NFS lock request
  ",
  				(int)hostname_len, hostname);
  		}
  		return NULL;
  	}
  
  retry:
  	spin_lock(&nsm_lock);

  
  	if (nsm_use_hostnames && hostname != NULL)
  		cached = nsm_lookup_hostname(hostname, hostname_len);
  	else
  		cached = nsm_lookup_addr(sap);
  
  	if (cached != NULL) {
  		atomic_inc(&cached->sm_count);
  		spin_unlock(&nsm_lock);
  		kfree(new);
  		dprintk("lockd: found nsm_handle for %s (%s), "
  				"cnt %d
  ", cached->sm_name,
  				cached->sm_addrbuf,
  				atomic_read(&cached->sm_count));
  		return cached;

  	}

  
  	if (new != NULL) {
  		list_add(&new->sm_link, &nsm_handles);
  		spin_unlock(&nsm_lock);

  		dprintk("lockd: created nsm_handle for %s (%s)
  ",

  				new->sm_name, new->sm_addrbuf);
  		return new;

  	}

  	spin_unlock(&nsm_lock);

  	new = nsm_create_handle(sap, salen, hostname, hostname_len);
  	if (unlikely(new == NULL))

  		return NULL;

  	goto retry;

  }
  
  /**

   * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
   * @info: pointer to NLMPROC_SM_NOTIFY arguments
   *

   * Returns a matching nsm_handle if found in the nsm cache. The returned
   * nsm_handle's reference count is bumped. Otherwise returns NULL if some
   * error occurred.

   */
  struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
  {
  	struct nsm_handle *cached;
  
  	spin_lock(&nsm_lock);

  	cached = nsm_lookup_priv(&info->priv);

  	if (unlikely(cached == NULL)) {
  		spin_unlock(&nsm_lock);
  		dprintk("lockd: never saw rebooted peer '%.*s' before
  ",
  				info->len, info->mon);
  		return cached;
  	}
  
  	atomic_inc(&cached->sm_count);
  	spin_unlock(&nsm_lock);

  	dprintk("lockd: host %s (%s) rebooted, cnt %d
  ",
  			cached->sm_name, cached->sm_addrbuf,
  			atomic_read(&cached->sm_count));
  	return cached;
  }
  
  /**

   * nsm_release - Release an NSM handle
   * @nsm: pointer to handle to be released
   *
   */
  void nsm_release(struct nsm_handle *nsm)
  {

  	if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
  		list_del(&nsm->sm_link);
  		spin_unlock(&nsm_lock);

  		dprintk("lockd: destroyed nsm_handle for %s (%s)
  ",
  				nsm->sm_name, nsm->sm_addrbuf);

  		kfree(nsm);
  	}
  }

  /*

   * XDR functions for NSM.

   *
   * See http://www.opengroup.org/ for details on the Network
   * Status Monitor wire protocol.

   */

  static int encode_nsm_string(struct xdr_stream *xdr, const char *string)

  {

  	const u32 len = strlen(string);
  	__be32 *p;
  
  	if (unlikely(len > SM_MAXSTRLEN))
  		return -EIO;
  	p = xdr_reserve_space(xdr, sizeof(u32) + len);
  	if (unlikely(p == NULL))
  		return -EIO;
  	xdr_encode_opaque(p, string, len);
  	return 0;

  }

  /*
   * "mon_name" specifies the host to be monitored.

   */

  static int encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)

  {

  	return encode_nsm_string(xdr, argp->mon_name);

  }

  /*
   * The "my_id" argument specifies the hostname and RPC procedure
   * to be called when the status manager receives notification

   * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"

   * has changed.
   */

  static int encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)

  {

  	int status;
  	__be32 *p;
  
  	status = encode_nsm_string(xdr, utsname()->nodename);
  	if (unlikely(status != 0))
  		return status;
  	p = xdr_reserve_space(xdr, 3 * sizeof(u32));
  	if (unlikely(p == NULL))
  		return -EIO;

  	*p++ = htonl(argp->prog);
  	*p++ = htonl(argp->vers);
  	*p++ = htonl(argp->proc);

  	return 0;

  }

  /*
   * The "mon_id" argument specifies the non-private arguments

   * of an NSMPROC_MON or NSMPROC_UNMON call.

   */

  static int encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)

  {

  	int status;

  	status = encode_mon_name(xdr, argp);
  	if (unlikely(status != 0))
  		return status;
  	return encode_my_id(xdr, argp);

  }

  /*
   * The "priv" argument may contain private information required

   * by the NSMPROC_MON call. This information will be supplied in the
   * NLMPROC_SM_NOTIFY call.

   */

  static int encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)

  {

  	__be32 *p;
  
  	p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
  	if (unlikely(p == NULL))
  		return -EIO;

  	xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);

  	return 0;

  }

  static int xdr_enc_mon(struct rpc_rqst *req, __be32 *p,
  		       const struct nsm_args *argp)

  {

  	struct xdr_stream xdr;
  	int status;

  	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
  	status = encode_mon_id(&xdr, argp);
  	if (unlikely(status))
  		return status;
  	return encode_priv(&xdr, argp);

  }

  static int xdr_enc_unmon(struct rpc_rqst *req, __be32 *p,
  			 const struct nsm_args *argp)

  {

  	struct xdr_stream xdr;
  
  	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
  	return encode_mon_id(&xdr, argp);

  }

  static int xdr_dec_stat_res(struct rpc_rqst *rqstp, __be32 *p,
  			    struct nsm_res *resp)

  {

  	struct xdr_stream xdr;
  
  	xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
  	p = xdr_inline_decode(&xdr, 2 * sizeof(u32));
  	if (unlikely(p == NULL))
  		return -EIO;

  	resp->status = ntohl(*p++);

  	resp->state = ntohl(*p);
  
  	dprintk("lockd: xdr_dec_stat_res status %d state %d
  ",

  			resp->status, resp->state);
  	return 0;
  }

  static int xdr_dec_stat(struct rpc_rqst *rqstp, __be32 *p,
  			struct nsm_res *resp)

  {

  	struct xdr_stream xdr;
  
  	xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
  	p = xdr_inline_decode(&xdr, sizeof(u32));
  	if (unlikely(p == NULL))
  		return -EIO;
  	resp->state = ntohl(*p);
  
  	dprintk("lockd: xdr_dec_stat state %d
  ", resp->state);

  	return 0;
  }
  
  #define SM_my_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))

  #define SM_my_id_sz	(SM_my_name_sz+3)
  #define SM_mon_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))
  #define SM_mon_id_sz	(SM_mon_name_sz+SM_my_id_sz)

  #define SM_priv_sz	(XDR_QUADLEN(SM_PRIV_SIZE))
  #define SM_mon_sz	(SM_mon_id_sz+SM_priv_sz)

  #define SM_monres_sz	2
  #define SM_unmonres_sz	1

  static struct rpc_procinfo	nsm_procedures[] = {

  [NSMPROC_MON] = {
  		.p_proc		= NSMPROC_MON,

  		.p_encode	= (kxdrproc_t)xdr_enc_mon,
  		.p_decode	= (kxdrproc_t)xdr_dec_stat_res,

  		.p_arglen	= SM_mon_sz,
  		.p_replen	= SM_monres_sz,

  		.p_statidx	= NSMPROC_MON,

  		.p_name		= "MONITOR",

  	},

  [NSMPROC_UNMON] = {
  		.p_proc		= NSMPROC_UNMON,

  		.p_encode	= (kxdrproc_t)xdr_enc_unmon,
  		.p_decode	= (kxdrproc_t)xdr_dec_stat,

  		.p_arglen	= SM_mon_id_sz,
  		.p_replen	= SM_unmonres_sz,

  		.p_statidx	= NSMPROC_UNMON,

  		.p_name		= "UNMONITOR",

  	},
  };
  
  static struct rpc_version	nsm_version1 = {

  		.number		= 1,
  		.nrprocs	= ARRAY_SIZE(nsm_procedures),

  		.procs		= nsm_procedures
  };
  
  static struct rpc_version *	nsm_version[] = {
  	[1] = &nsm_version1,
  };
  
  static struct rpc_stat		nsm_stats;
  
  static struct rpc_program	nsm_program = {
  		.name		= "statd",

  		.number		= NSM_PROGRAM,

  		.nrvers		= ARRAY_SIZE(nsm_version),

  		.version	= nsm_version,
  		.stats		= &nsm_stats
  };