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 April 21, 2013 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 -width 15n 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 -width 15n 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 -width 15n 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 -width 15n 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 -width 15n 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). 199Include commands in the referenced 200.Ar ruleset 201are not resolved. 202.It Cm mode Ar filemode 203Set the file mode to 204.Ar filemode , 205which is interpreted as in 206.Xr chmod 1 . 207.It Cm user Ar uid 208Set the UID to 209.Ar uid , 210which may be a user name 211(looked up in 212.Pa /etc/passwd ) 213or number. 214.It Cm unhide 215Unhide the node. 216.El 217.Sh IMPLEMENTATION NOTES 218Rulesets are created by the kernel at the first reference 219and destroyed when the last reference disappears. 220E.g., a ruleset is created when a rule is added to it or when it is set 221as the current ruleset for a mount-point, and 222a ruleset is destroyed when the last rule in it is deleted 223and no other references to it exist 224(i.e., it is not included by any rules and it is not the current ruleset 225for any mount-point). 226.Pp 227Ruleset number 0 is the default ruleset for all new mount-points. 228It is always empty, cannot be modified or deleted, and does not show up 229in the output of 230.Cm showsets . 231.Pp 232Rules and rulesets are unique to the entire system, 233not a particular mount-point. 234I.e., a 235.Cm showsets 236will return the same information regardless of the mount-point specified with 237.Fl m . 238The mount-point is only relevant when changing what its current ruleset is 239or when using one of the apply commands. 240.Sh FILES 241.Bl -tag -width "Pa /usr/share/examples/etc/devfs.conf" -compact 242.It Pa /etc/defaults/devfs.rules 243Default 244.Nm 245configuration file. 246.It Pa /etc/devfs.rules 247Local 248.Nm 249configuration file. Rulesets in here override those in 250.Pa /etc/defaults/devfs.rules 251with the same ruleset number, otherwise the two files are effectively merged. 252.It Pa /etc/devfs.conf 253Boot-time 254.Nm 255configuration file. 256.It Pa /usr/share/examples/etc/devfs.conf 257Example boot-time 258.Nm 259configuration file. 260.El 261.Sh EXAMPLES 262When the system boots, 263the only ruleset that exists is ruleset number 0; 264since the latter may not be modified, we have to create another ruleset 265before adding rules. 266Note that since most of the following examples do not specify 267.Fl m , 268the operations are performed on 269.Pa /dev 270(this only matters for things that might change the properties of nodes). 271.Pp 272Specify that ruleset 10 should be the current ruleset for 273.Pa /dev 274(if it does not already exist, it is created): 275.Pp 276.Dl "devfs ruleset 10" 277.Pp 278Add a rule that causes all nodes that have a path that matches 279.Dq Li speaker 280(this is only 281.Pa /dev/speaker ) 282to have the file mode 666 (read and write for all). 283Note that if any such nodes already exist, their mode will not be changed 284unless this rule (or ruleset) is explicitly applied (see below). 285The mode 286.Em will 287be changed if the node is created 288.Em after 289the rule is added 290(e.g., the 291.Pa atspeaker 292module is loaded after the above rule is added): 293.Pp 294.Dl "devfs rule add path speaker mode 666" 295.Pp 296Apply all the rules in the current ruleset to all the existing nodes. 297E.g., if the below rule was added after 298.Pa /dev/speaker 299was created, 300this command will cause its file mode to be changed to 666 301as prescribed by the rule: 302.Pp 303.Dl "devfs rule applyset" 304.Pp 305For all devices with a path that matches 306.Dq Li snp* , 307set the file mode to 660 and the GID to 308.Dq Li snoopers . 309This permits users in the 310.Dq Li snoopers 311group to use the 312.Xr snp 4 313devices 314(quoting the argument to 315.Cm path 316is often necessary to disable the shell's globbing features): 317.Pp 318.Dl devfs rule add path "snp*" mode 660 group snoopers 319.Pp 320Add a rule to ruleset number 20. 321Since this ruleset is not the current ruleset for any mount-points, 322this rule is never applied automatically (unless ruleset 20 becomes 323a current ruleset for some mount-point at a later time): 324.Pp 325.Dl "devfs rule -s 20 add type disk group wheel" 326.Pp 327Explicitly apply all rules in ruleset number 20 to the DEVFS mount on 328.Pa /my/jail/dev . 329It does not matter that ruleset 20 is not the current ruleset for that 330mount-point; the rules are still applied: 331.Pp 332.Dl "devfs -m /my/jail/dev rule -s 20 applyset" 333.Pp 334Since the following rule has no conditions, the action 335.Pq Cm hide 336will be applied to all nodes: 337.Pp 338.Dl "devfs rule apply hide" 339.Pp 340Since hiding all nodes is not very useful, we can undo it. 341The following applies 342.Cm unhide 343to all the nodes, 344causing them to reappear: 345.Pp 346.Dl "devfs rule apply unhide" 347.Pp 348Add all the rules from the file 349.Pa my_rules 350to ruleset 10: 351.Pp 352.Dl "devfs rule -s 10 add - < my_rules" 353.Pp 354The below copies all the rules from ruleset 20 into ruleset 10. 355The rule numbers are preserved, 356but ruleset 10 may already have rules with non-conflicting numbers 357(these will be preserved). 358Since 359.Cm show 360outputs valid rules, 361this feature can be used to copy rulesets: 362.Pp 363.Dl "devfs rule -s 20 show | devfs rule -s 10 add -" 364.Sh SEE ALSO 365.Xr chmod 1 , 366.Xr jail 2 , 367.Xr glob 3 , 368.Xr devfs 5 , 369.Xr devfs.conf 5 , 370.Xr devfs.rules 5 , 371.Xr chown 8 , 372.Xr jail 8 , 373.Xr mknod 8 374.Sh AUTHORS 375.An Dima Dorfman 376