X-Git-Url: https://git.decadent.org.uk/gitweb/?p=nfs-utils.git;a=blobdiff_plain;f=utils%2Fstatd%2Fstatd.man;h=4ddb634041d57abd1609ae23a19a5a1615844269;hp=e8be9f3b4fb12d1035f3898050eb7710c321617b;hb=ec8a23e674ba39b3c4048095c4d848dfb1b15c0f;hpb=7dd134204d88c22b414a4ecfcd986efb57fedebf diff --git a/utils/statd/statd.man b/utils/statd/statd.man index e8be9f3..4ddb634 100644 --- a/utils/statd/statd.man +++ b/utils/statd/statd.man @@ -1,191 +1,403 @@ -.\" -.\" statd(8) +.\"@(#)rpc.statd.8" .\" .\" Copyright (C) 1999 Olaf Kirch .\" Modified by Jeffrey A. Uphoff, 1999, 2002, 2005. .\" Modified by Lon Hohberger, 2000. .\" Modified by Paul Clements, 2004. -.TH rpc.statd 8 "31 Aug 2004" +.\" +.\" Rewritten by Chuck Lever , 2009. +.\" Copyright 2009 Oracle. All rights reserved. +.\" +.TH RPC.STATD 8 "1 November 2009 .SH NAME -rpc.statd \- NSM status monitor +rpc.statd \- NSM service daemon .SH SYNOPSIS -.B "rpc.statd [-FNL] [-d] [-?] [-n " name "] [-o " port "] [-p " port "] [-H " prog "] [-V]" +.BI "rpc.statd [-dh?FLNvVw] [-H " prog "] [-n " my-name "] [-o " outgoing-port "] [-p " listener-port "] [-P " path " ] .SH DESCRIPTION -The +File locks are not part of persistent file system state. +Lock state is thus lost when a host reboots. +.PP +Network file systems must also detect when lock state is lost +because a remote host has rebooted. +After an NFS client reboots, an NFS server must release all file locks +held by applications that were running on that client. +After a server reboots, a client must remind the +server of file locks held by applications running on that client. +.PP +For NFS version 2 [RFC1094] and NFS version 3 [RFC1813], the +.I Network Status Monitor +protocol (or NSM for short) +is used to notify NFS peers of reboots. +On Linux, two separate user-space components constitute the NSM service: +.TP .B rpc.statd -server implements the NSM (Network Status Monitor) RPC protocol. -This service is somewhat misnamed, since it doesn't actually provide -active monitoring as one might suspect; instead, NSM implements a -reboot notification service. It is used by the NFS file locking service, -.BR rpc.lockd , -to implement lock recovery when the NFS server machine crashes and -reboots. -.SS Operation -For each NFS client or server machine to be monitored, -.B rpc.statd -creates a file in -.BR /var/lib/nfs/sm . -When starting, it normally runs +A daemon that listens for reboot notifications from other hosts, and +manages the list of hosts to be notified when the local system reboots +.TP +.B sm-notify +A helper program that notifies NFS peers after the local system reboots +.PP +The local NFS lock manager alerts its local +.B rpc.statd +of each remote peer that should be monitored. +When the local system reboots, the .B sm-notify -to iterate through these files and notify the -peer +command notifies the NSM service on monitored peers of the reboot. +When a remote reboots, that peer notifies the local +.BR rpc.statd , +which in turn passes the reboot notification +back to the local NFS lock manager. +.SH NSM OPERATION IN DETAIL +The first file locking interaction between an NFS client and server causes +the NFS lock managers on both peers to contact their local NSM service to +store information about the opposite peer. +On Linux, the local lock manager contacts +.BR rpc.statd . +.PP +.B rpc.statd +records information about each monitored NFS peer on persistent storage. +This information describes how to contact a remote peer +in case the local system reboots, +how to recognize which monitored peer is reporting a reboot, +and how to notify the local lock manager when a monitored peer +indicates it has rebooted. +.PP +An NFS client sends a hostname, known as the client's +.IR caller_name , +in each file lock request. +An NFS server can use this hostname to send asynchronous GRANT +calls to a client, or to notify the client it has rebooted. +.PP +The Linux NFS server can provide the client's +.I caller_name +or the client's network address to +.BR rpc.statd . +For the purposes of the NSM protocol, +this name or address is known as the monitored peer's +.IR mon_name . +In addition, the local lock manager tells .B rpc.statd -on those machines. +what it thinks its own hostname is. +For the purposes of the NSM protocol, +this hostname is known as +.IR my_name . +.PP +There is no equivalent interaction between an NFS server and a client +to inform the client of the server's +.IR caller_name . +Therefore NFS clients do not actually know what +.I mon_name +an NFS server might use in an SM_NOTIFY request. +The Linux NFS client uses the server hostname from the mount command +to identify rebooting NFS servers. +.SS Reboot notification +When the local system reboots, the +.B sm-notify +command reads the list of monitored peers from persistent storage and +sends an SM_NOTIFY request to the NSM service on each listed remote peer. +It uses the +.I mon_name +string as the destination. +To identify which host has rebooted, the +.B sm-notify +command normally sends the results of +.BR gethostname (3) +as the +.I my_name +string. +The remote +.B rpc.statd +matches incoming SM_NOTIFY requests using this string, +or the caller's network address, +to one or more peers on its own monitor list. +.PP +If +.B rpc.statd +does not find a peer on its monitor list that matches +an incoming SM_NOTIFY request, +the notification is not forwarded to the local lock manager. +In addition, each peer has its own +.IR "NSM state number" , +a 32-bit integer that is bumped after each reboot by the +.B sm-notify +command. +.B rpc.statd +uses this number to distinguish between actual reboots +and replayed notifications. +.PP +Part of NFS lock recovery is rediscovering +which peers need to be monitored again. +The +.B sm-notify +command clears the monitor list on persistent storage after each reboot. .SH OPTIONS .TP -.B -F -By default, +.BR -d , " --no-syslog +Causes .B rpc.statd -forks and puts itself in the background when started. The -.B -F -argument tells it to remain in the foreground. This option is -mainly for debugging purposes. -.TP -.B -d -By default, -.B rpc.statd -sends logging messages via -.BR syslog (3) -to system log. The -.B -d -argument forces it to log verbose output to -.B stderr -instead. This option is mainly for debugging purposes, and may only -be used in conjunction with the +to write log messages on +.I stderr +instead of to the system log, +if the .B -F -parameter. +option was also specified. .TP -.BI "\-n," "" " \-\-name " name -specify a name for -.B rpc.statd -to use as the local hostname. By default, -.BR rpc.statd -will call -.BR gethostname (2) -to get the local hostname. Specifying -a local hostname may be useful for machines with more than one -interfaces. +.BR -F , " --foreground +Keeps +.B rpc.statd +attached to its controlling terminal so that NSM +operation can be monitored directly or run under a debugger. +If this option is not specified, +.B rpc.statd +backgrounds itself soon after it starts. .TP -.BI "\-o," "" " \-\-outgoing\-port " port -specify a port for -.B rpc.statd -to send outgoing status requests from. By default, -.BR rpc.statd -will ask -.BR portmap (8) -to assign it a port number. As of this writing, there is not -a standard port number that -.BR portmap -always or usually assigns. Specifying -a port may be useful when implementing a firewall. +.BR -h , " -?" , " --help +Causes +.B rpc.statd +to display usage information on +.I stderr +and then exit. .TP -.BI "\-p," "" " \-\-port " port -specify a port for -.B rpc.statd -to listen on. By default, -.BR rpc.statd -will ask -.BR portmap (8) -to assign it a port number. As of this writing, there is not -a standard port number that -.BR portmap -always or usually assigns. Specifying -a port may be useful when implementing a firewall. +.BI "\-H," "" " \-\-ha-callout " prog +Specifies a high availability callout program. +If this option is not specified, no callouts are performed. +See the +.B High-availability callouts +section below for details. .TP -.BI "\-P," "" " \-\-state\-directory\-path " directory -specify a directory in which to place statd state information. -If this option is not specified the default of -.BR /var/lib/nfs -is used. +.BR -L , " --no-notify +Prevents +.B rpc.statd +from running the +.B sm-notify +command when it starts up, +preserving the existing NSM state number and monitor list. +.IP +Note: the +.B sm-notify +command contains a check to ensure it runs only once after each system reboot. +This prevents spurious reboot notification if +.B rpc.statd +restarts without the +.B -L +option. .TP -.B -N -Causes statd to run in the notify-only mode. When started in this mode, the -statd program will check its state directory, send notifications to any -monitored nodes, and exit once the notifications have been sent. This mode is -used to enable Highly Available NFS implementations (i.e. HA-NFS). -This mode is deprecated \- +.BI "\-n, " "" "\-\-name " ipaddr " | " hostname +Specifies the bind address used for RPC listener sockets. +The +.I ipaddr +form can be expressed as either an IPv4 or an IPv6 presentation address. +If this option is not specified, +.B rpc.statd +uses a wildcard address as the transport bind address. +.IP +This string is also passed to the .B sm-notify -should be used directly instead. +command to be used as the source address from which +to send reboot notification requests. +See +.BR sm-notify (8) +for details. .TP -.BR -L , " --no-notify -Inhibits the running of -.BR sm-notify . -If +.BR -N +Causes +.B rpc.statd +to run the .B sm-notify -is run by some other script at boot time, there is no need for -.B statd -to start sm-notify itself. This can be appropriate if starting of -statd needs to be delayed until it is actually need. In such cases +command, and then exit. +Since the +.B sm-notify +command can also be run directly, this option is deprecated. +.TP +.BI "\-o," "" " \-\-outgoing\-port " port +Specifies the source port number the .B sm-notify -should still be run at boot time. +command should use when sending reboot notifications. +See +.BR sm-notify (8) +for details. .TP -.BI "\-H, " "" " \-\-ha-callout " prog -Specify a high availability callout program, which will receive callouts -for all client monitor and unmonitor requests. This allows +.BI "\-p," "" " \-\-port " port +Specifies the port number used for RPC listener sockets. +If this option is not specified, .B rpc.statd -to be used in a High Availability NFS (HA-NFS) environment. The -program will be run with 3 arguments: The first is either -.B add-client -or -.B del-client -depending on the reason for the callout. -The second will be the name of the client. -The third will be the name of the server as known to the client. +chooses a random ephemeral port for each listener socket. +.IP +This option can be used to fix the port value of its listeners when +SM_NOTIFY requests must traverse a firewall between clients and servers. .TP -.B -? -Causes +.BI "\-P, " "" \-\-state\-directory\-path " pathname +Specifies the pathname of the parent directory +where NSM state information resides. +If this option is not specified, .B rpc.statd -to print out command-line help and exit. +uses +.I /var/lib/nfs +by default. +.IP +After starting, +.B rpc.statd +attempts to set its effective UID and GID to the owner +and group of this directory. .TP -.B -V +.BR -v ", " -V ", " --version Causes .B rpc.statd -to print out version information and exit. - - - -.SH TCP_WRAPPERS SUPPORT -This +to display version information on +.I stderr +and then exit. +.SH SECURITY +The +.B rpc.statd +daemon must be started as root to acquire privileges needed +to create sockets with privileged source ports, and to access the +state information database. +Because +.B rpc.statd +maintains a long-running network service, however, it drops root privileges +as soon as it starts up to reduce the risk of a privilege escalation attack. +.PP +During normal operation, +the effective user ID it chooses is the owner of the state directory. +This allows it to continue to access files in that directory after it +has dropped its root privileges. +To control which user ID +.B rpc.statd +chooses, simply use +.BR chown (1) +to set the owner of +the state directory. +.PP +You can also protect your .B rpc.statd -version is protected by the +listeners using the +.B tcp_wrapper +library or +.BR iptables (8). +Note that the +.B tcp_wrapper +library supports only IPv4 networking. +To use the .B tcp_wrapper -library. You have to give the clients access to -.B rpc.statd -if they should be allowed to use it. To allow connects from clients of -the .bar.com domain you could use the following line in /etc/hosts.allow: - -statd: .bar.com - -You have to use the daemon name +library, add the hostnames of peers that should be allowed access to +.IR /etc/hosts.allow . +Use the daemon name .B statd -for the daemon name (even if the binary has a different name). - -For further information please have a look at the +even if the +.B rpc.statd +binary has a different filename. +.P +For further information see the .BR tcpd (8) and .BR hosts_access (5) -manual pages. - -.SH SIGNALS -.BR SIGUSR1 -causes -.B rpc.statd -to re-read the notify list from disk -and send notifications to clients. This can be used in High Availability NFS -(HA-NFS) environments to notify clients to reacquire file locks upon takeover -of an NFS export from another server. - +man pages. +.SH ADDITIONAL NOTES +Lock recovery after a reboot is critical to maintaining data integrity +and preventing unnecessary application hangs. +.PP +To help +.B rpc.statd +match SM_NOTIFY requests to NLM requests, a number of best practices +should be observed, including: +.IP +The UTS nodename of your systems should match the DNS names that NFS +peers use to contact them +.IP +The UTS nodenames of your systems should always be fully qualified domain names +.IP +The forward and reverse DNS mapping of the UTS nodenames should be +consistent +.IP +The hostname the client uses to mount the server should match the server's +.I mon_name +in SM_NOTIFY requests it sends +.IP +The use of network addresses as a +.I mon_name +or a +.I my_name +string should be avoided when +interoperating with non-Linux NFS implementations. +.PP +Unmounting an NFS file system does not necessarily stop +either the NFS client or server from monitoring each other. +Both may continue monitoring each other for a time in case subsequent +NFS traffic between the two results in fresh mounts and additional +file locking. +.PP +On Linux, if the +.B lockd +kernel module is unloaded during normal operation, +all remote NFS peers are unmonitored. +This can happen on an NFS client, for example, +if an automounter removes all NFS mount +points due to inactivity. +.SS High-availability callouts +.B rpc.statd +can exec a special callout program during processing of +successful SM_MON, SM_UNMON, and SM_UNMON_ALL requests. +Such a program may be used in High Availability NFS (HA-NFS) +environments to track lock state that may need to be migrated after +a system reboot. +.PP +The name of the callout program is specified with the +.B -H +option. +The program is run with 3 arguments: +The first is either +.B add-client +or +.B del-client +depending on the reason for the callout. +The second is the +.I mon_name +of the monitored peer. +The third is the +.I caller_name +of the requesting lock manager. +.SS IPv6 and TI-RPC support +TI-RPC is a pre-requisite for supporting NFS on IPv6. +If TI-RPC support is built into +.BR rpc.statd , +it attempts to start listeners on network transports marked +'visible' in +.IR /etc/netconfig . +As long as at least one network transport listener starts successfully, +.B rpc.statd +will operate. .SH FILES -.BR /var/lib/nfs/state +.TP 2.5i +.I /var/lib/nfs/sm +directory containing monitor list +.TP 2.5i +.I /var/lib/nfs/sm.bak +directory containing notify list +.TP 2.5i +.I /var/lib/nfs/state +NSM state number for this host +.TP 2.5i +.I /var/run/run.statd.pid +pid file +.TP 2.5i +.I /etc/netconfig +network transport capability database +.SH SEE ALSO +.BR sm-notify (8), +.BR nfs (5), +.BR rpc.nfsd (8), +.BR rpcbind (8), +.BR tcpd (8), +.BR hosts_access (5), +.BR iptables (8), +.BR netconfig (5) +.sp +RFC 1094 - "NFS: Network File System Protocol Specification" .br -.BR /var/lib/nfs/sm/* +RFC 1813 - "NFS Version 3 Protocol Specification" .br -.BR /var/lib/nfs/sm.bak/* -.SH SEE ALSO -.BR rpc.nfsd(8), -.BR portmap(8) +OpenGroup Protocols for Interworking: XNFS, Version 3W - Chapter 11 .SH AUTHORS -.br Jeff Uphoff .br Olaf Kirch @@ -195,3 +407,5 @@ H.J. Lu Lon Hohberger .br Paul Clements +.br +Chuck Lever