| sysctl.9 (f3066f2be73aa3fe83f9d56b1977e130659da3f3) | sysctl.9 (dba9e9ccbfd771d5521657cc68cc537c7da99e41) |
|---|---|
| 1.\" 2.\" Copyright (c) 2006 Robert N. M. Watson 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 --- 11 unchanged lines hidden (view full) --- 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.\" | 1.\" 2.\" Copyright (c) 2006 Robert N. M. Watson 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 --- 11 unchanged lines hidden (view full) --- 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 January 16, 2010 | 28.Dd April 28, 2006 |
| 29.Dt SYSCTL 9 30.Os 31.Sh NAME 32.Nm SYSCTL_DECL , 33.Nm SYSCTL_INT , 34.Nm SYSCTL_LONG , 35.Nm SYSCTL_NODE , 36.Nm SYSCTL_OPAQUE , 37.Nm SYSCTL_PROC , 38.Nm SYSCTL_STRING , 39.Nm SYSCTL_STRUCT , 40.Nm SYSCTL_UINT , | 29.Dt SYSCTL 9 30.Os 31.Sh NAME 32.Nm SYSCTL_DECL , 33.Nm SYSCTL_INT , 34.Nm SYSCTL_LONG , 35.Nm SYSCTL_NODE , 36.Nm SYSCTL_OPAQUE , 37.Nm SYSCTL_PROC , 38.Nm SYSCTL_STRING , 39.Nm SYSCTL_STRUCT , 40.Nm SYSCTL_UINT , |
| 41.Nm SYSCTL_ULONG , 42.Nm SYSCTL_XINT , 43.Nm SYSCTL_XLONG , 44.Nm SYSCTL_QUAD | 41.Nm SYSCTL_ULONG |
| 45.Nd Static sysctl declaration functions 46.Sh SYNOPSIS 47.In sys/types.h 48.In sys/sysctl.h | 42.Nd Static sysctl declaration functions 43.Sh SYNOPSIS 44.In sys/types.h 45.In sys/sysctl.h |
| 49.Fn SYSCTL_DECL name 50.Fn SYSCTL_INT parent nbr name access ptr val descr 51.Fn SYSCTL_LONG parent nbr name access ptr val descr 52.Fn SYSCTL_NODE parent nbr name access handler descr 53.Fn SYSCTL_OPAQUE parent nbr name access ptr len fmt descr 54.Fn SYSCTL_PROC parent nbr name access ptr arg handler fmt descr 55.Fn SYSCTL_STRING parent nbr name access arg len descr 56.Fn SYSCTL_STRUCT parent nbr name access ptr type descr 57.Fn SYSCTL_UINT parent nbr name access ptr val descr 58.Fn SYSCTL_ULONG parent nbr name access ptr val descr 59.Fn SYSCTL_XINT parent nbr name access ptr val descr 60.Fn SYSCTL_XLONG parent nbr name access ptr val descr 61.Fn SYSCTL_QUAD parent nbr name access ptr val descr | 46.Fo SYSCTL_DECL 47.Fa "name" 48.Fc 49.Fo SYSCTL_INT 50.Fa "parent" 51.Fa "nbr" 52.Fa "name" 53.Fa "access" 54.Fa "ptr" 55.Fa "val" 56.Fa "descr" 57.Fc 58.Fo SYSCTL_LONG 59.Fa "parent" 60.Fa "nbr" 61.Fa "name" 62.Fa "access" 63.Fa "ptr" 64.Fa "val" 65.Fa "descr" 66.Fc 67.Fo SYSCTL_NODE 68.Fa "parent" 69.Fa "nbr" 70.Fa "name" 71.Fa "access" 72.Fa "handler" 73.Fa "descr" 74.Fc 75.Fo SYSCTL_OPAQUE 76.Fa "parent" 77.Fa "nbr" 78.Fa "name" 79.Fa "access" 80.Fa "ptr" 81.Fa "len" 82.Fa "fmt" 83.Fa "descr" 84.Fc 85.Fo SYSCTL_PROC 86.Fa "parent" 87.Fa "nbr" 88.Fa "name" 89.Fa "access" 90.Fa "ptr" 91.Fa "arg" 92.Fa "handler" 93.Fa "fmt" 94.Fa "descr" 95.Fc 96.Fo SYSCTL_STRING 97.Fa "parent" 98.Fa "nbr" 99.Fa "name" 100.Fa "access" 101.Fa "arg" 102.Fa "len" 103.Fa "descr" 104.Fc 105.Fo SYSCTL_STRUCT 106.Fa "parent" 107.Fa "nbr" 108.Fa "name" 109.Fa "access" 110.Fa "ptr" 111.Fa "type" 112.Fa "descr" 113.Fc 114.Fo SYSCTL_UINT 115.Fa "parent" 116.Fa "nbr" 117.Fa "name" 118.Fa "access" 119.Fa "ptr" 120.Fa "val" 121.Fa "descr" 122.Fc 123.Fo SYSCTL_ULONG 124.Fa "parent" 125.Fa "nbr" 126.Fa "name" 127.Fa "access" 128.Fa "ptr" 129.Fa "val" 130.Fa "descr" 131.Fc |
| 62.Sh DESCRIPTION 63The | 132.Sh DESCRIPTION 133The |
| 64.Nm SYSCTL | 134.Nm |
| 65kernel interfaces allow code to statically declare 66.Xr sysctl 8 67MIB entries, which will be initialized when the kernel module containing the 68declaration is initialized. 69When the module is unloaded, the sysctl will be automatically destroyed. 70.Pp | 135kernel interfaces allow code to statically declare 136.Xr sysctl 8 137MIB entries, which will be initialized when the kernel module containing the 138declaration is initialized. 139When the module is unloaded, the sysctl will be automatically destroyed. 140.Pp |
| 71Sysctl nodes are created in a hierarchical tree, with all static nodes being | 141Sysctl nodes are created in a hierarchal tree, with all static nodes being |
| 72represented by named C data structures; in order to create a new node under 73an existing node in the tree, the structure representing the desired parent 74node must be declared in the current context using 75.Fn SYSCTL_DECL . 76.Pp 77New nodes are declared using one of | 142represented by named C data structures; in order to create a new node under 143an existing node in the tree, the structure representing the desired parent 144node must be declared in the current context using 145.Fn SYSCTL_DECL . 146.Pp 147New nodes are declared using one of |
| 78.Fn SYSCTL_INT , 79.Fn SYSCTL_LONG , 80.Fn SYSCTL_NODE , 81.Fn SYSCTL_OPAQUE , 82.Fn SYSCTL_PROC , 83.Fn SYSCTL_STRING , 84.Fn SYSCTL_STRUCT , 85.Fn SYSCTL_UINT , 86.Fn SYSCTL_ULONG , 87.Fn SYSCTL_XINT , 88.Fn SYSCTL_XLONG , | 148.Nm SYSCTL_INT , 149.Nm SYSCTL_LONG , 150.Nm SYSCTL_NODE , 151.Nm SYSCTL_OPAQUE , 152.Nm SYSCTL_PROC , 153.Nm SYSCTL_STRING , 154.Nm SYSCTL_STRUCT , 155.Nm SYSCTL_UINT , |
| 89and | 156and |
| 90.Fn SYSCTL_QUAD . | 157.Nm SYSCTL_ULONG . |
| 91Each macro accepts a parent name, as declared using | 158Each macro accepts a parent name, as declared using |
| 92.Fn SYSCTL_DECL , | 159.Nm SYSCTL_DECL , |
| 93an OID number, typically 94.Dv OID_AUTO , 95a node name, a set of control and access flags, and a description. 96Depending on the macro, a pointer to a variable supporting the MIB entry, a 97size, a value, and a function pointer implementing the MIB entry may also be 98present. 99.Pp 100For most of the above macros, declaring a type as part of the access flags is | 160an OID number, typically 161.Dv OID_AUTO , 162a node name, a set of control and access flags, and a description. 163Depending on the macro, a pointer to a variable supporting the MIB entry, a 164size, a value, and a function pointer implementing the MIB entry may also be 165present. 166.Pp 167For most of the above macros, declaring a type as part of the access flags is |
| 101not necessary \[em] however, when declaring a sysctl implemented by a function, | 168not necessary -- however, when declaring a sysctl implemented by a function, |
| 102including a type in the access mask is required: | 169including a type in the access mask is required: |
| 103.Bl -tag -width ".Dv CTLTYPE_STRING" | 170.Bl -tag -width CTLTYPE_STRING |
| 104.It Dv CTLTYPE_NODE 105This is a node intended to be a parent for other nodes. 106.It Dv CTLTYPE_INT 107This is a signed integer. 108.It Dv CTLTYPE_STRING 109This is a nul-terminated string stored in a character array. 110.It Dv CTLTYPE_QUAD 111This is a 64-bit signed integer. 112.It Dv CTLTYPE_OPAQUE 113This is an opaque data structure. 114.It Dv CTLTYPE_STRUCT 115Alias for 116.Dv CTLTYPE_OPAQUE. 117.It Dv CTLTYPE_UINT 118This is an unsigned integer. 119.It Dv CTLTYPE_LONG 120This is a signed long. 121.It Dv CTLTYPE_ULONG | 171.It Dv CTLTYPE_NODE 172This is a node intended to be a parent for other nodes. 173.It Dv CTLTYPE_INT 174This is a signed integer. 175.It Dv CTLTYPE_STRING 176This is a nul-terminated string stored in a character array. 177.It Dv CTLTYPE_QUAD 178This is a 64-bit signed integer. 179.It Dv CTLTYPE_OPAQUE 180This is an opaque data structure. 181.It Dv CTLTYPE_STRUCT 182Alias for 183.Dv CTLTYPE_OPAQUE. 184.It Dv CTLTYPE_UINT 185This is an unsigned integer. 186.It Dv CTLTYPE_LONG 187This is a signed long. 188.It Dv CTLTYPE_ULONG |
| 122This is an unsigned long. | 189This is an insigned long. |
| 123.El 124.Pp 125All sysctl types except for new node declarations require one or more flags 126to be set indicating the read and write disposition of the sysctl: | 190.El 191.Pp 192All sysctl types except for new node declarations require one or more flags 193to be set indicating the read and write disposition of the sysctl: |
| 127.Bl -tag -width ".Dv CTLFLAG_ANYBODY" | 194.Bl -tag -width CTLFLAG_ANYBODY |
| 128.It Dv CTLFLAG_RD 129This is a read-only sysctl. | 195.It Dv CTLFLAG_RD 196This is a read-only sysctl. |
| 130.It Dv CTLFLAG_WR | 197It Dv CTLFLAG_WR |
| 131This is a writable sysctl. 132.It Dv CTLFLAG_RW 133This sysctl is readable and writable. 134.It Dv CTLFLAG_ANYBODY 135Any user or process can write to this sysctl. 136.It Dv CTLFLAG_SECURE 137This sysctl can be written to only if the effective securelevel of the | 198This is a writable sysctl. 199.It Dv CTLFLAG_RW 200This sysctl is readable and writable. 201.It Dv CTLFLAG_ANYBODY 202Any user or process can write to this sysctl. 203.It Dv CTLFLAG_SECURE 204This sysctl can be written to only if the effective securelevel of the |
| 138process is \[<=] 0. | 205process is <= 0. |
| 139.It Dv CTLFLAG_PRISON 140This sysctl can be written to by processes in 141.Xr jail 2 . 142.It Dv CTLFLAG_SKIP 143When iterating the sysctl name space, do not list this sysctl. 144.It Dv CTLFLAG_TUN 145Also declare a system tunable with the same name to initialize this variable. 146.It Dv CTLFLAG_RDTUN | 206.It Dv CTLFLAG_PRISON 207This sysctl can be written to by processes in 208.Xr jail 2 . 209.It Dv CTLFLAG_SKIP 210When iterating the sysctl name space, do not list this sysctl. 211.It Dv CTLFLAG_TUN 212Also declare a system tunable with the same name to initialize this variable. 213.It Dv CTLFLAG_RDTUN |
| 147Also declare a system tunable with the same name to initialize this variable; | 214Also declare a system tunable with the same name to initalize this variable; |
| 148however, the run-time variable is read-only. 149.El 150.Pp 151When creating new sysctls, careful attention should be paid to the security 152implications of the monitoring or management interface being created. 153Most sysctls present in the kernel are read-only or writable only by the 154superuser. 155Sysctls exporting extensive information on system data structures and 156operation, especially those implemented using procedures, will wish to 157implement access control to limit the undesired exposure of information about 158other processes, network connections, etc. 159.Pp 160The following top level sysctl name spaces are commonly used: | 215however, the run-time variable is read-only. 216.El 217.Pp 218When creating new sysctls, careful attention should be paid to the security 219implications of the monitoring or management interface being created. 220Most sysctls present in the kernel are read-only or writable only by the 221superuser. 222Sysctls exporting extensive information on system data structures and 223operation, especially those implemented using procedures, will wish to 224implement access control to limit the undesired exposure of information about 225other processes, network connections, etc. 226.Pp 227The following top level sysctl name spaces are commonly used: |
| 161.Bl -tag -width ".Va regression" 162.It Va compat | 228.Bl -tag -width regression 229.It Dv compat |
| 163Compatibility layer information. | 230Compatibility layer information. |
| 164.It Va debug | 231.It Dv debug |
| 165Debugging information. 166Various name spaces exist under | 232Debugging information. 233Various name spaces exist under |
| 167.Va debug . 168.It Va hw | 234.Dv debug . 235.It Dv hw |
| 169Hardware and device driver information. | 236Hardware and device driver information. |
| 170.It Va kern | 237.It Dv kern |
| 171Kernel behavior tuning; generally deprecated in favor of more specific 172name spaces. | 238Kernel behavior tuning; generally deprecated in favor of more specific 239name spaces. |
| 173.It Va machdep | 240.It Dv machdep |
| 174Machine-dependent configuration parameters. | 241Machine-dependent configuration parameters. |
| 175.It Va net | 242.It Dv net |
| 176Network subsystem. 177Various protocols have name spaces under | 243Network subsystem. 244Various protocols have name spaces under |
| 178.Va net . 179.It Va regression | 245.Dv net . 246.It Dv regression |
| 180Regression test configuration and information. | 247Regression test configuration and information. |
| 181.It Va security 182Security and security-policy configuration and information. 183.It Va sysctl | 248.It Dv security 249Security and security policy configuration and information. 250.It Dv sysctl |
| 184Reserved name space for the implementation of sysctl. | 251Reserved name space for the implementation of sysctl. |
| 185.It Va user | 252.It Dv user |
| 186Configuration settings relating to user application behavior. | 253Configuration settings relating to user application behavior. |
| 187Generally, configuring applications using kernel sysctls is discouraged. 188.It Va vfs | 254Generally, configuring applications using kernel sysctls is disouraged. 255.It Dv vfs |
| 189Virtual file system configuration and information. | 256Virtual file system configuration and information. |
| 190.It Va vm | 257.It Dv vm |
| 191Virtual memory subsystem configuration and information. 192.El 193.Sh EXAMPLES 194Sample use of | 258Virtual memory subsystem configuration and information. 259.El 260.Sh EXAMPLES 261Sample use of |
| 195.Fn SYSCTL_DECL 196to declare the 197.Va security 198sysctl tree for use by new nodes: | 262.Nm SYSCTL_DECL 263to declare the "security" sysctl tree for use by new nodes: |
| 199.Bd -literal -offset indent 200SYSCTL_DECL(_security); 201.Ed 202.Pp 203Examples of integer, opaque, string, and procedure sysctls follow: 204.Bd -literal -offset indent 205/* 206 * Example of a constant integer value. Notice that the control 207 * flags are CTLFLAG_RD, the variable pointer is NULL, and the 208 * value is declared. | 264.Bd -literal -offset indent 265SYSCTL_DECL(_security); 266.Ed 267.Pp 268Examples of integer, opaque, string, and procedure sysctls follow: 269.Bd -literal -offset indent 270/* 271 * Example of a constant integer value. Notice that the control 272 * flags are CTLFLAG_RD, the variable pointer is NULL, and the 273 * value is declared. |
| 209 * If sysctl(8) should print this value in hex, use 'SYSCTL_XINT'. | |
| 210 */ 211SYSCTL_INT(_debug_sizeof, OID_AUTO, bio, CTLFLAG_RD, NULL, 212 sizeof(struct bio), "sizeof(struct bio)"); 213 214/* 215 * Example of a variable integer value. Notice that the control 216 * flags are CTLFLAG_RW, the variable pointer is set, and the 217 * value is 0. --- 26 unchanged lines hidden (view full) --- 244 * information. Notice that the data type is declared, the NULL 245 * variable pointer and 0 size, the function pointer, and the 246 * format string for sysctl(8). 247 */ 248SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | 249 CTLFLAG_RW, NULL, 0, sysctl_kern_timecounter_hardware, "A", 250 ""); 251.Ed | 274 */ 275SYSCTL_INT(_debug_sizeof, OID_AUTO, bio, CTLFLAG_RD, NULL, 276 sizeof(struct bio), "sizeof(struct bio)"); 277 278/* 279 * Example of a variable integer value. Notice that the control 280 * flags are CTLFLAG_RW, the variable pointer is set, and the 281 * value is 0. --- 26 unchanged lines hidden (view full) --- 308 * information. Notice that the data type is declared, the NULL 309 * variable pointer and 0 size, the function pointer, and the 310 * format string for sysctl(8). 311 */ 312SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | 313 CTLFLAG_RW, NULL, 0, sysctl_kern_timecounter_hardware, "A", 314 ""); 315.Ed |
| 252.Sh SYSCTL NAMING | 316.Pp |
| 253When adding, modifying, or removing sysctl names, it is important to be 254aware that these interfaces may be used by users, libraries, applications, | 317When adding, modifying, or removing sysctl names, it is important to be 318aware that these interfaces may be used by users, libraries, applications, |
| 255or documentation (such as published books), and are implicitly published application interfaces. | 319and even books, and are implicitly published application interfaces. |
| 256As with other application interfaces, caution must be taken not to break 257existing applications, and to think about future use of new name spaces so as 258to avoid the need to rename or remove interfaces that might be depended on in 259the future. | 320As with other application interfaces, caution must be taken not to break 321existing applications, and to think about future use of new name spaces so as 322to avoid the need to rename or remove interfaces that might be depended on in 323the future. |
| 260.Pp 261The semantics chosen for a new sysctl should be as clear as possible, 262and the name of the sysctl must closely reflect its semantics. 263Therefore the sysctl name deserves a fair amount of consideration. 264It should be short but yet representative of the sysctl meaning. 265If the name consists of several words, they should be separated by 266underscore characters, as in 267.Va compute_summary_at_mount . 268Underscore characters may be omitted only if the name consists of not more 269than two words, each being not longer than four characters, as in 270.Va bootfile . 271For boolean sysctls, negative logic should be totally avoided. 272That is, do not use names like 273.Va no_foobar 274or 275.Va foobar_disable . 276They are confusing and lead to configuration errors. 277Use positive logic instead: 278.Va foobar , 279.Va foobar_enable . 280.Pp 281A temporary sysctl node that should not be relied upon must be designated 282as such by a leading underscore character in its name. For example: 283.Va _dirty_hack . | |
| 284.Sh SEE ALSO | 324.Sh SEE ALSO |
| 285.Xr sysctl 3 , | |
| 286.Xr sysctl 8 , 287.Xr sysctl_add_oid 9 , 288.Xr sysctl_ctx_free 9 , 289.Xr sysctl_ctx_init 9 , 290.Xr sysctl_remove_oid 9 291.Sh HISTORY | 325.Xr sysctl 8 , 326.Xr sysctl_add_oid 9 , 327.Xr sysctl_ctx_free 9 , 328.Xr sysctl_ctx_init 9 , 329.Xr sysctl_remove_oid 9 330.Sh HISTORY |
| 292The | |
| 293.Xr sysctl 8 | 331.Xr sysctl 8 |
| 294utility first appeared in | 332first appeared in |
| 295.Bx 4.4 . 296.Sh AUTHORS | 333.Bx 4.4 . 334.Sh AUTHORS |
| 297.An -nosplit 298The 299.Nm sysctl 300implementation originally found in | 335The sysctl implementation originally found in |
| 301.Bx 302has been extensively rewritten by 303.An Poul-Henning Kamp 304in order to add support for name lookups, name space iteration, and dynamic 305addition of MIB nodes. 306.Pp 307This man page was written by 308.An Robert N. M. Watson . | 336.Bx 337has been extensively rewritten by 338.An Poul-Henning Kamp 339in order to add support for name lookups, name space iteration, and dynamic 340addition of MIB nodes. 341.Pp 342This man page was written by 343.An Robert N. M. Watson . |