1.\" 2.\" Copyright (c) 2002 Dima Dorfman. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd July 1, 2002 29.Dt DEVFS 8 30.Os 31.Sh NAME 32.Nm devfs 33.Nd "DEVFS control" 34.Sh SYNOPSIS 35.Nm 36.Op Fl m Ar mount-point 37.Ar keyword 38.Ar argument ... 39.Sh DESCRIPTION 40The 41.Nm 42utility provides an interface to manipulate properties of 43.Xr devfs 5 44mounts. 45.Pp 46The 47.Ar keyword 48argument determines the context for 49the rest of the arguments. 50For example, 51most of the commands related to the rule subsystem must be preceded by the 52.Cm rule 53keyword. 54The following flags are common to all keywords: 55.Bl -tag -offset indent 56.It Fl m Ar mount-point 57Operate on 58.Ar mount-point , 59which is expected to be a 60.Xr devfs 5 61mount. 62If this option is not specified, 63.Nm 64operates on 65.Pa /dev . 66.El 67.Ss Rule Subsystem 68The 69.Xr devfs 5 70rule subsystem provides a way for the administrator of a system to control 71the attributes of DEVFS nodes. 72.\" XXX devfs node? entry? what? 73Each DEVFS mount-point has a 74.Dq ruleset , 75or a list of rules, 76associated with it. 77When a device driver creates a new node, 78all the rules in the ruleset associated with each mount-point are applied 79(see below) before the node becomes visible to the userland. 80This permits the administrator to change the properties, 81including the visibility, 82of certain nodes. 83For example, one might want to hide all disk nodes in a 84.Xr jail 2 Ns 's 85.Pa /dev . 86.Ss Rule Manipulation 87Rule manipulation commands follow the 88.Cm rule 89keyword. 90The following flags are common to all of the rule manipulation commands: 91.Bl -tag -offset indent 92.It Fl s Ar ruleset 93Operate on the ruleset with the number 94.Ar ruleset . 95If this is not specified, 96the commands operate on the ruleset currently associated with the 97specified mount-point. 98.El 99.Pp 100The following commands are recognized: 101.Bl -tag -offset indent 102.It Cm rule add Oo Ar rulenum Oc Ar rulespec 103Add the rule described by 104.Ar rulespec 105(defined below) 106to the ruleset. 107The rule has the number 108.Ar rulenum 109if it is explicitly specified; 110otherwise, the rule number is automatically determined by the kernel. 111.It Cm rule apply Ar rulenum | rulespec 112Apply rule number 113.Ar rulenum 114or the rule described by 115.Ar rulespec 116to the mount-point. 117Rules that are 118.Dq applied 119have their conditions checked against all nodes 120in the mount-point and the actions taken if they match. 121.It Cm rule applyset 122Apply all the rules in the ruleset to the mount-point 123(see above for the definition of 124.Dq apply ) . 125.It Cm rule del Ar rulenum 126Delete rule number 127.Ar rulenum 128from the ruleset. 129.It Cm rule delset 130Delete all rules from the ruleset. 131.It Cm rule show Op Ar rulenum 132Display the rule number 133.Ar rulenum , 134or all the rules in the ruleset. 135The output lines (one line per rule) are expected to be valid 136.Ar rulespec Ns s . 137.It Cm rule showsets 138Report the numbers of existing rulesets. 139.It Cm ruleset Ar ruleset 140Set ruleset number 141.Ar ruleset 142as the current ruleset for the mount-point. 143.El 144.Ss Rule Specification 145Rules have two parts: the conditions and the actions. 146The conditions determine which DEVFS nodes the rule matches 147and the actions determine what should be done when a rule matches a node. 148For example, a rule can be written that sets the GID to 149.Dq Li operator 150for all devices of type tape. 151If the first token of a rule specification is a single dash 152.Pq Sq Fl , 153rules are read from the standard input and the rest of the specification 154is ignored. 155.Pp 156The following conditions are recognized. 157Conditions are ANDed together when matching a device; 158if OR is desired, multiple rules can be written. 159.Bl -tag -offset indent 160.It Cm path Ar pattern 161Matches any node with a path that matches 162.Ar pattern , 163which is interpreted as a 164.Xr glob 3 Ns -style 165pattern. 166.It Cm type Ar devtype 167Matches any node that is of type 168.Ar devtype . 169Valid types are 170.Cm disk , mem , tape 171and 172.Cm tty . 173.El 174.Pp 175The following actions are recognized. 176Although there is no explicit delimiter between conditions and actions, 177they may not be intermixed. 178.Bl -tag -offset indent 179.It Cm group Ar gid 180Set the GID of the node to 181.Ar gid , 182which may be a group name 183(looked up in 184.Pa /etc/group ) 185or number. 186.It Cm hide 187Hide the node. 188Nodes may later be revived manually with 189.Xr mknod 8 190or with the 191.Cm unhide 192action. 193.It Cm include Ar ruleset 194Apply all the rules in ruleset number 195.Ar ruleset 196to the node. 197This does not necessarily result in any changes to the node 198(e.g., if none of the rules in the included ruleset match). 199.It Cm mode Ar filemode 200Set the file mode to 201.Ar filemode , 202which is interpreted as in 203.Xr chmod 1 . 204.It Cm user Ar uid 205Set the UID to 206.Ar uid , 207which may be a user name 208(looked up in 209.Pa /etc/passwd ) 210or number. 211.It Cm unhide 212Unhide the node. 213.El 214.Sh IMPLEMENTATION NOTES 215Rulesets are created by the kernel at the first reference 216and destroyed when the last reference disappears. 217E.g., a ruleset is created when a rule is added to it or when it is set 218as the current ruleset for a mount-point, and 219a ruleset is destroyed when the last rule in it is deleted 220and no other references to it exist 221(i.e., it is not included by any rules and it is not the current ruleset 222for any mount-point). 223.Pp 224Ruleset number 0 is the default ruleset for all new mount-points. 225It is always empty, cannot be modified or deleted, and does not show up 226in the output of 227.Cm showsets . 228.Pp 229Rules and rulesets are unique to the entire system, 230not a particular mount-point. 231I.e., a 232.Cm showsets 233will return the same information regardless of the mount-point specified with 234.Fl m . 235The mount-point is only relevant when changing what its current ruleset is 236or when using one of the apply commands. 237.Sh EXAMPLES 238When the system boots, 239the only ruleset that exists is ruleset number 0; 240since the latter may not be modified, we have to create another ruleset 241before adding rules. 242Note that since most of the following examples do not specify 243.Fl m , 244the operations are performed on 245.Pa /dev 246(this only matters for things that might change the properties of nodes). 247.Pp 248.Dl "devfs ruleset 10" 249.Pp 250Specify that ruleset 10 should be the current ruleset for 251.Pa /dev 252(if it does not already exist, it is created). 253.Pp 254.Dl "devfs rule add path speaker mode 666" 255.Pp 256Add a rule that causes all nodes that have a path that matches 257.Dq Li speaker 258(this is only 259.Pa /dev/speaker ) 260to have the file mode 666 (read and write for all). 261Note that if any such nodes already exist, their mode will not be changed 262unless this rule (or ruleset) is explicitly applied (see below). 263The mode 264.Em will 265be changed if the node is created 266.Em after 267the rule is added 268(e.g., the 269.Pa atspeaker 270module is loaded after the above rule is added). 271.Pp 272.Dl "devfs rule applyset" 273.Pp 274Apply all the rules in the current ruleset to all the existing nodes. 275E.g., if the above rule was added after 276.Pa /dev/speaker 277was created, 278this command will cause its file mode to be changed to 666 279as prescribed by the rule. 280.Pp 281.Dl devfs rule add path "snp*" mode 660 group snoopers 282.Pp 283(Quoting the argument to 284.Cm path 285is often necessary to disable the shell's globbing features.) 286For all devices with a path that matches 287.Dq Li snp* , 288set the file more to 660 and the GID to 289.Dq Li snoopers . 290This permits users in the 291.Dq Li snoopers 292group to use the 293.Xr snp 4 294devices. 295.Pp 296.Dl "devfs rule -s 20 add major 53 group games" 297.Pp 298Add a rule to ruleset number 20. 299Since this ruleset is not the current ruleset for any mount-points, 300this rule is never applied automatically (unless ruleset 20 becomes 301a current ruleset for some mount-point at a later time). 302However, it can be applied explicitly, as such: 303.Pp 304.Dl "devfs -m /my/jail/dev rule -s 20 applyset" 305.Pp 306This will apply all rules in ruleset number 20 to the DEVFS mount on 307.Pa /my/jail/dev . 308It does not matter that ruleset 20 is not the current ruleset for that 309mount-point; the rules are still applied. 310.Pp 311.Dl "devfs rule apply hide" 312.Pp 313Since this rule has no conditions, the action 314.Pq Cm hide 315will be applied to all nodes. 316Since hiding all nodes is not very useful, we can undo it: 317.Pp 318.Dl "devfs rule apply unhide" 319.Pp 320which applies 321.Cm unhide 322to all the nodes, 323causing them to reappear. 324.Pp 325.Dl "devfs rule -s 10 add - < my_rules" 326.Pp 327Add all the rules from the file 328.Pa my_rules 329to ruleset 10. 330.Pp 331.Dl "devfs rule -s 20 show | devfs rule -s 10 add -" 332.Pp 333Since 334.Cm show 335outputs valid rules, 336this feature can be used to copy rulesets. 337The above copies all the rules from ruleset 20 into ruleset 10. 338The rule numbers are preserved, 339but ruleset 10 may already have rules with non-conflicting numbers 340(these will be preserved). 341.Sh SEE ALSO 342.Xr chmod 1 , 343.Xr jail 2 , 344.Xr glob 3 , 345.Xr devfs 5 , 346.Xr chown 8 , 347.Xr jail 8 , 348.Xr mknod 8 349.Sh AUTHORS 350.An Dima Dorfman 351