mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-22 11:17:19 +00:00
113 lines
3.0 KiB
Groff
113 lines
3.0 KiB
Groff
.\"
|
|
.\" Copyright (c) 2002 Mark R V Murray
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
|
|
.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd February 6, 2002
|
|
.Dt RANDOM_HARVEST 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm random_harvest
|
|
.Nd gather entropy from the kernel for the entropy device
|
|
.Sh SYNOPSIS
|
|
.In sys/types.h
|
|
.In sys/random.h
|
|
.Ft void
|
|
.Fo random_harvest
|
|
.Fa "void *entropy"
|
|
.Fa "u_int size"
|
|
.Fa "u_int bits"
|
|
.Fa "u_int frac"
|
|
.Fa "enum esource source"
|
|
.Fc
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn random_harvest
|
|
function is used by device drivers
|
|
and other kernel processes to pass data
|
|
that is considered (at least partially) stochastic
|
|
to the entropy device.
|
|
.Pp
|
|
The caller should pass a pointer (to no more than 16 bytes) of
|
|
the
|
|
.Dq random
|
|
data in
|
|
.Fa entropy .
|
|
The argument
|
|
.Fa size
|
|
contains the number of bytes pointed to.
|
|
The caller should
|
|
.Em "very conservatively"
|
|
estimate the number of random bits
|
|
in the sample,
|
|
and pass this in
|
|
.Fa bits
|
|
or
|
|
.Fa frac .
|
|
If the estimated number of bits per sample is an integer, then
|
|
.Fa bits
|
|
is used, and
|
|
.Fa frac
|
|
is 0.
|
|
Otherwise,
|
|
for low-entropy samples,
|
|
.Dq fractional
|
|
entropy can be supplied in
|
|
.Fa frac .
|
|
(This is considered to be
|
|
.Fa frac /
|
|
1024 bits of entropy.)
|
|
The
|
|
.Fa source
|
|
is chosen from
|
|
.Dv RANDOM_WRITE , RANDOM_KEYBOARD , RANDOM_MOUSE , RANDOM_NET
|
|
and
|
|
.Dv RANDOM_INTERRUPT ,
|
|
and is used to indicate the source of the entropy.
|
|
.Pp
|
|
Interrupt harvesting has been simplified
|
|
for the kernel programmer.
|
|
If a device driver registers an interrupt handler
|
|
with
|
|
.Xr BUS_SETUP_INTR 9
|
|
or
|
|
.Xr bus_setup_intr 9 ,
|
|
then it is only necessary to
|
|
include the
|
|
.Dv INTR_ENTROPY
|
|
bit in the
|
|
.Fa flags
|
|
argument to have that interrupt source
|
|
be used for entropy harvesting.
|
|
.Sh SEE ALSO
|
|
.Xr random 4 ,
|
|
.Xr BUS_SETUP_INTR 9
|
|
.Sh AUTHORS
|
|
The
|
|
.Fx
|
|
.Xr random 4
|
|
entropy device and supporting documentation was written by
|
|
.An Mark R V Murray .
|