libc/sys/modctl.2

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.Dd April 26, 2020
.Dt MODCTL 2
.Os
.Sh NAME
.Nm modctl
.Nd module control
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/module.h
.Ft int
.Fn modctl "int operation" "void *argp"
.Sh DESCRIPTION
.Fn modctl
provides control over loaded kernel modules.
The argument
.Fa operation
is one of
.Dv MODCTL_LOAD ,
.Dv MODCTL_UNLOAD ,
.Dv MODCTL_STAT ,
or
.Dv MODCTL_EXISTS .
The argument
.Fa argp
depends on the
.Fa operation
to be performed.
.Pp
Operations are:
.Bl -tag -width MODCTL_UNLOAD
.It Dv MODCTL_LOAD
Load a module.
The
.Fa argp
argument should be a pointer to a
.Em modctl_load_t
structure, described below.
.It Dv MODCTL_UNLOAD
Unload a module.
In this case,
.Fa argp
should be a string containing the name of the module to be unloaded.
.It Dv MODCTL_STAT
Return a list of loaded modules.
In this case, the
.Fa argp
argument should be a
.Em struct iovec
pointing to a suitable block of memory.
The kernel will fill this block with
.Bl -bullet
.It
a count of the number of modules loaded,
.It
an array of
.Em modstat_t
structures, one per loaded module, and
.It
a series of NUL-terminated strings containing the modules'
required modules lists.
.El
.Pp
If the block is not large enough, the data returned will be truncated
to fit.
The kernel will then update the
.Fa iov_len
member of the
.Em iovec
to reflect the size of the complete report, regardless of whether this
is larger or smaller than the size passed in.
.It Dv MODCTL_EXISTS
Test to see if the kernel was compiled with
.Dq options MODULAR
and whether or
not modules may be loaded at the moment.
In this case,
.Fa argp
should be an integer.
It should be
.Dq 0
to test if a user can load a module via
.Dv MODCTL_LOAD ,
or it should be
.Dq 1
to test if the system can autoload modules.
Note that this
test does not consider the sysctl
.Li kern.module.autoload .
.El
.Ss Data Types
The
.Em modctl_load_t
structure used with
.Dv MODCTL_LOAD
contains the following elements, which should be filled in by the caller:
.Bl -tag -width aaaaaaaa
.It Fa "const char *ml_filename"
The name/path of the module to load.
.It Fa "int ml_flags"
Zero or more of the following flag values:
.Bl -tag -compact -width "MODCTL_LOAD_FORCE"
.It Dv MODCTL_NO_PROP
Don't load
.Ao module Ac Ns Pa .plist .
.It Dv MODCTL_LOAD_FORCE
Ignore kernel version mismatch.
.El
.It Fa "const char *ml_props"
Externalized proplib dictionary to pass to module.
.It Fa "size_t ml_propslen"
Size of the dictionary blob.
.Fa ml_props
may be
.Dv NULL
in which case
.Fa ml_propslen
must be
.Dv 0 .
An upper limit of 4096 bytes is imposed on the value of ml_propslen.
Attempting to load a proplib dictionary larger than this size will return
.Er ENOMEM .
.El
.Pp
The
.Em modstat_t
structure used with
.Dv MODCTL_STAT
contains the following elements, which are filled in by the kernel:
.Bl -tag -width aaaaaaaa
.It Fa "char ms_name[MAXMODNAME]"
The name of the module.
.It Fa "modsrc_t ms_source"
One of the following enumerated constants:
.Bl -tag -compact -width "MODULE_SOURCE_FILESYS"
.It Dv MODULE_SOURCE_KERNEL
The module is compiled into the kernel.
.It Dv MODULE_SOURCE_BOOT
The module was provided by the bootstrap loader.
.It Dv MODULE_SOURCE_FILESYS
The module was loaded from the file system.
.El
.It Fa "modclass_t ms_class"
One of the following enumerated constants:
.Bl -tag -compact -width "MODULE_SOURCE_FILESYS"
.It Dv MODULE_CLASS_SECMODEL
Security model.
.It Dv MODULE_CLASS_VFS
File system.
.It Dv MODULE_CLASS_DRIVER
Device driver.
.It Dv MODULE_CLASS_EXEC
Executable file format.
.It Dv MODULE_CLASS_MISC
Miscellaneous.
.El
.It Fa "uint64_t ms_addr"
The load address within the kernel of the module's text segment.
(This value is available only for privileged users.)
.It Fa "u_int ms_size"
Loaded size of the module's text segment.
(This value is available only for privileged users.)
.It Fa "u_int ms_refcnt"
Current number of live references to this module.
.It Fa "u_int ms_flags"
The module's flags:
.Bl -tag -compact -width "MODFLAG_AUTO_LOADED"
.It Dv MODFLAG_MUST_FORCE
The "force" flag must be specified to reload this module.
.It Dv MODFLAG_AUTO_LOADED
The module was auto-loaded by the operating system.
.El
.It Fa "uint_ms_reqoffset"
The offset (in bytes) from the beginning of the required-module data.
.El
.Sh RETURN VALUES
Upon successful completion, the value returned is 0.
.Pp
Otherwise, a value of \-1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn modctl
will fail if:
.Bl -tag -width Er
.It Bq Er EBUSY
The argument
.Fa operation
is
.Dv MODCTL_UNLOAD
and the module is in use or the module is compiled into the kernel.
.It Bq Er EDEADLK
The argument
.Fa operation
is
.Dv MODCTL_LOAD
and there is a circular dependency in the module's dependency chain.
.It Bq Er EEXIST
The argument
.Fa operation
is
.Dv MODCTL_LOAD
and the module is already loaded.
.It Bq Er EFAULT
A bad address was given for
.Fa argp .
.It Bq Er EFBIG
The argument
.Fa operation
is
.Dv MODCTL_LOAD ,
the specified module resides in the file system, and the module's default
proplib file was too large.
.It Bq Er EINVAL
The argument
.Fa operation
is invalid.
.Pp
The argument
.Fa operation
is
.Dv MODCTL_LOAD
and ml_props is not
.Dv NULL
and
.Dq ml_propslen
is
.Dv 0 ,
or
ml_props is
.Dv NULL
and
.Dq ml_propslen
is not
.Dv 0 .
The kernel is unable to internalize the plist.
Or, there is a problem with the module or <module>.plist.
.It Bq Er ENAMETOOLONG
A module name/path is too long.
.It Bq Er ENOENT
The argument
.Fa operation
is
.Dv MODCTL_LOAD
and the module or a dependency can't be found.
.Pp
The argument
.Fa operation
is
.Dv MODCTL_UNLOAD
and no module by the name of
.Fa argp
is loaded.
.It Bq Er ENOEXEC
The argument
.Fa operation
is
.Dv MODCTL_LOAD
and the module is not a valid object for the system.
Most likely, one or more undefined symbols could not be resolved by the
in-kernel linker.
.It Bq Er ENOMEM
There was not enough memory to perform the
.Fa operation .
.It Bq Er ENOSYS
The argument
.Fa operation
is
.Dv MODLOAD_EXIST
and the kernel does not include
.Dq options MODULAR .
.It Bq Er EPERM
Not allowed to perform the
.Fa operation .
.It Bq Er EPROGMISMATCH
The argument
.Fa operation
is
.Dv MODCTL_LOAD ,
the
.Fa ml_flags
field in the
.Em modctl_load_t
structure does not include
.Dv MODCTL_LOAD_FORCE ,
and the requested module does not match the current kernel's version
information.
.El
.Sh SEE ALSO
.Xr module 7 ,
.Xr sysctl 7 ,
.Xr module 9
.Sh HISTORY
The
.Fn modctl
function call first appeared in
.Nx 5.0 .