1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
.\"
.\" sm-notify(8)
.\"
.\" Copyright (C) 2004 Olaf Kirch <okir@suse.de>
.TH sm-notify 8 "19 Mar 2007
.SH NAME
sm-notify \- Send out NSM reboot notifications
.SH SYNOPSIS
.BI "/sbin/sm-notify [-df] [-m " time "] [-p " port "] [-P " path "] [-v " my_name " ]
.SH DESCRIPTION
File locking over NFS (v2 and v3) requires a facility to notify peers in
case of a reboot, so that clients can reclaim locks after
a server crash, and/or
servers can release locks held by the rebooted client.
.PP
This is a two-step process: during normal
operations, a mechanism is required to keep track of which
hosts need to be informed of a reboot. And of course,
notifications need to be sent out during reboot.
The protocol used for this is called NSM, for
.IR "Network Status Monitor" .
.PP
This implementation separates these into separate program.
.B rpc.statd
tracks hosts which need to be notified and this
.B sm-notify
performs the notification. When
.B rpc.statd
is started it will typically started
.B sm-notify
but this is configurable.
.SS Operation
For each NFS client or server machine to be monitored,
.B rpc.statd
creates a file in
.BR /var/lib/nfs/sm ", "
and removes the file if monitoring is no longer required.
.PP
When the machine is rebooted,
.B sm-notify
iterates through these files and notifies the peer
.B statd
server on those machines.
.PP
Each machine has an
.I "NSM state" ,
which is basically an integer counter that is incremented
each time the machine reboots. This counter is stored
in
.BR /var/lib/nfs/state ,
and updated by
.BR sm-notify .
.SS Security
.B sm-notify
has little need for root privileges and so drops them as soon as
possible.
It continues to need to make changes to the
.B sm
and
.B sm.bak
directories so to be able to drop privileges, these must be writable
by a non-privileged user. If these directories are owned by a
non-root user,
.B sm-notify
will drop privilege to match that user once it has created sockets for
sending out request (for which it needs privileged) but before it
processes any reply (which is the most likely source of possible
privilege abuse).
.SH OPTIONS
.TP
.BI -m " failtime
When notifying hosts,
.B sm-notify
will try to contact each host for up to 15 minutes,
and will give up if unable to reach it within this time
frame.
.IP
Using the
.B -m
option, you can override this. A value of 0 tells
sm-notify to retry indefinitely; any other value is
interpreted as the maximum retry time in minutes.
.TP
.BI -v " ipaddr-or-hostname
This option tells
.B sm-notify
to bind to the specified
.IR ipaddr ,
(or the ipaddr of the given
.IR hostname )
so that all notification packets originate from this address.
This is useful for NFS failover. The given name is also used as the
.I name
of this host in the NSM request.
.TP
.BI -p " port
instructs
.B sm-notify
to bind to the indicated IP
.IR port
number. If this option is not given, it will try to bind to
a randomly chosen privileged port below 1024.
.TP
.BI -P " /path/to/state/directory
If
.B sm-notify
should look in a no-standard place of state file, the path can be
given here. The directories
.B sm
and
.B sm.bak
and the file
.B state
must exist in that directory with the standard names.
.TP
.B -f
If the state path has not been reset with
.BR -P ,
.B sm-notify
will normally create a file in
.B /var/run
to indicate that it has been
run. If this file is found when
.B sm-notify
starts, it will not run again (as it is normally only needed once per
reboot).
If
.B -f
(for
.BR force )
is given,
.B sm-notify
will run even if the file in
.B /var/run
is present.
.TP
.B -n
Do not update the NSM state. This is for testing only. Setting this
flag implies
.BR -f .
.TP
.B -d
Enables debugging.
By default,
.B sm-notify
forks and puts itself in the background after obtaining the
list of hosts from
.BR /var/lib/nfs/sm .
.SH FILES
.BR /var/lib/nfs/state
.br
.BR /var/lib/nfs/sm/*
.br
.BR /var/lib/nfs/sm.bak/*
.br
.BR /var/run/sm-notify.pid
.SH SEE ALSO
.BR rpc.nfsd(8),
.BR portmap(8)
.SH AUTHORS
.br
Olaf Kirch <okir@suse.de>
|
