Aren/NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add getentropy() to libc - a simple wrapper to access the kernel CSPRNG.

Browse Source 
Posted to tech-userlevel@ a week ago and reviewed by riastradh@.

GETENTROPY(3)		   Library Functions Manual		 GETENTROPY(3)

NAME
     getentropy - fill a buffer with high quality random data

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     getentropy(void *buf, size_t buflen);

DESCRIPTION
     The getentropy() function fills a buffer with high quality random data,
     suitable for seeding cryptographically secure psuedorandom number
     generators.

     getentropy() is only intended for seeding random number generators and is
     not intended for use by regular code which simply needs secure random
     data.  For this purpose, please use arc4random(3).

     The maximum value for buflen is 256 bytes.

IMPLEMENTATION NOTES
     getentropy() reads from the sysctl(7) variable kern.arandom.

RETURN VALUES
     The getentropy() function returns 0 on success, and -1 if an error
     occurred.

ERRORS
     getentropy() will succeed unless:

     [EFAULT]		The buf argument points to an invalid memory address.

     [EIO]		Too many bytes were requested.

SEE ALSO
     arc4random(3), rnd(4)

STANDARDS
     The getentropy() function is non-standard.

HISTORY
     The getentropy() function first appeared in OpenBSD 5.6, then in
     FreeBSD 12.0, and NetBSD 10.
This commit is contained in:
nia 2020-05-06 16:17:36 +00:00
parent cc9246a967
commit 5e1fba1a1e
6 changed files with 168 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
distrib/sets/lists/comp/mi
View File

@ -1,4 +1,4 @@
# $NetBSD: mi,v 1.2324 2020/05/01 21:43:23 jdolecek Exp $
# $NetBSD: mi,v 1.2325 2020/05/06 16:17:36 nia Exp $
#
# Note: don't delete entries from here - mark them as "obsolete" instead.
./etc/mtree/set.comp comp-sys-root
@ -7273,6 +7273,7 @@
./usr/share/man/cat3/getdiskrawname.0 comp-c-catman .cat
./usr/share/man/cat3/getdomainname.0 comp-c-catman .cat
./usr/share/man/cat3/getdtablesize.0 comp-c-catman .cat
./usr/share/man/cat3/getentropy.0 comp-c-catman .cat
./usr/share/man/cat3/getenv.0 comp-c-catman .cat
./usr/share/man/cat3/getenv_r.0 comp-c-catman .cat
./usr/share/man/cat3/getfsent.0 comp-c-catman .cat
@ -15316,6 +15317,7 @@
./usr/share/man/html3/getdiskrawname.html comp-c-htmlman html
./usr/share/man/html3/getdomainname.html comp-c-htmlman html
./usr/share/man/html3/getdtablesize.html comp-c-htmlman html
./usr/share/man/html3/getentropy.html comp-c-htmlman html
./usr/share/man/html3/getenv.html comp-c-htmlman html
./usr/share/man/html3/getenv_r.html comp-c-htmlman html
./usr/share/man/html3/getfsent.html comp-c-htmlman html
@ -23297,6 +23299,7 @@
./usr/share/man/man3/getdiskrawname.3 comp-c-man .man
./usr/share/man/man3/getdomainname.3 comp-c-man .man
./usr/share/man/man3/getdtablesize.3 comp-c-man .man
./usr/share/man/man3/getentropy.3 comp-c-man .man
./usr/share/man/man3/getenv.3 comp-c-man .man
./usr/share/man/man3/getenv_r.3 comp-c-man .man
./usr/share/man/man3/getfsent.3 comp-c-man .man

3
include/unistd.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: unistd.h,v 1.156 2020/03/31 16:50:31 kamil Exp $ */
/* $NetBSD: unistd.h,v 1.157 2020/05/06 16:17:36 nia Exp $ */
/*-
* Copyright (c) 1998, 1999, 2008 The NetBSD Foundation, Inc.
@ -338,6 +338,7 @@ int fchroot(int);
int fdiscard(int, off_t, off_t);
int fsync_range(int, int, off_t, off_t);
int getdomainname(char *, size_t);
int getentropy(void *, size_t);
int getgrouplist(const char *, gid_t, gid_t *, int *);
int getgroupmembership(const char *, gid_t, gid_t *, int, int *);
mode_t getmode(const void *, mode_t);

6
lib/libc/gen/Makefile.inc
View File

@ -1,4 +1,4 @@
# $NetBSD: Makefile.inc,v 1.201 2020/04/22 23:32:25 joerg Exp $
# $NetBSD: Makefile.inc,v 1.202 2020/05/06 16:17:36 nia Exp $
# from: @(#)Makefile.inc 8.6 (Berkeley) 5/4/95
# gen sources
@ -15,7 +15,7 @@ SRCS+= alarm.c alphasort.c arc4random.c assert.c asysctl.c \
errc.c errlist.c errno.c execl.c execle.c execlp.c execv.c execvp.c \
exect.c extattr.c fmtcheck.c fmtmsg.c fnmatch.c fstab.c ftok.c \
fts.c ftw.c getbsize.c getcap.c getcwd.c \
getdevmajor.c getdomainname.c getgrent.c \
getdevmajor.c getdomainname.c getentropy.c getgrent.c \
getgrouplist.c getgroupmembership.c gethostname.c \
getloadavg.c getlogin.c getmntinfo.c \
getnetgrent.c getpagesize.c \
@ -60,7 +60,7 @@ MAN+= alarm.3 arc4random.3 basename.3 bsd_signal.3 bswap.3 \
fmtcheck.3 fmtmsg.3 fnmatch.3 fpclassify.3 fpgetmask.3 \
ftok.3 fts.3 ftw.3 \
getbsize.3 cgetcap.3 getcwd.3 getdevmajor.3 \
getdomainname.3 getdiskbyname.3 getfsent.3 \
getdomainname.3 getdiskbyname.3 getentropy.3 getfsent.3 \
getgrent.3 getgrouplist.3 gethostname.3 getlastlogx.3 getloadavg.3 \
getmntinfo.3 getnetgrent.3 getpagesize.3 getpass.3 \
getprogname.3 getpwent.3 getttyent.3 getusershell.3 glob.3 \

93
lib/libc/gen/getentropy.3 Normal file
View File

@ -0,0 +1,93 @@
.\" $NetBSD: getentropy.3,v 1.1 2020/05/06 16:17:36 nia Exp $ $
.\"
.\" Copyright (c) 2020 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Nia Alarie.
.\"
.\" 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``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 FOUNDATION OR CONTRIBUTORS
.\" 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.
.\"
.Dd May 1, 2020
.Dt GETENTROPY 3
.Os
.Sh NAME
.Nm getentropy
.Nd fill a buffer with high quality random data
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn getentropy "void *buf" "size_t buflen"
.Sh DESCRIPTION
.Pp
The
.Fn getentropy
function fills a buffer with high quality random data, suitable for seeding
cryptographically secure psuedorandom number generators.
.Pp
.Fn getentropy
is only intended for seeding random number generators and is not intended
for use by regular code which simply needs secure random data. For this
purpose, please use
.Xr arc4random 3 .
.Pp
The maximum value for
.Li buflen
is 256 bytes.
.Sh IMPLEMENTATION NOTES
.Fn getentropy
reads from the
.Xr sysctl 7
variable
.Li kern.arandom .
.Sh RETURN VALUES
The
.Fn getentropy
function returns 0 on success, and -1 if an error occurred.
.Sh ERRORS
.Fn getentropy
will succeed unless:
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa buf
argument points to an invalid memory address.
.It Bq Er EIO
Too many bytes were requested.
.Sh SEE ALSO
.Xr arc4random 3 ,
.Xr rnd 4
.Sh STANDARDS
The
.Fn getentropy
function is non-standard.
.Sh HISTORY
The
.Fn getentropy
function first appeared in
.Ox 5.6 ,
then in
.Fx 12.0 ,
and
.Nx 10 .

64
lib/libc/gen/getentropy.c Normal file
View File

@ -0,0 +1,64 @@
/* $NetBSD: getentropy.c,v 1.1 2020/05/06 16:17:36 nia Exp $ */
/*-
* Copyright (c) 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Nia Alarie.
*
* 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: getentropy.c,v 1.1 2020/05/06 16:17:36 nia Exp $");
#include "namespace.h"
#include <sys/param.h>
#include <sys/sysctl.h>
#include <errno.h>
#include <unistd.h>
#ifdef __weak_alias
__weak_alias(getentropy,_getentropy)
#endif
int
getentropy(void *buf, size_t buflen)
{
size_t len = buflen;
int name[2] = { CTL_KERN, KERN_ARND };
if (buf == NULL && buflen > 0) {
errno = EFAULT;
return -1;
}
if (buflen > 256) {
errno = EIO;
return -1;
}
return sysctl(name, 2, buf, &len, NULL, 0);
}

3
lib/libc/include/namespace.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: namespace.h,v 1.198 2020/04/18 23:55:50 thorpej Exp $ */
/* $NetBSD: namespace.h,v 1.199 2020/05/06 16:17:36 nia Exp $ */
/*-
* Copyright (c) 1997-2004 The NetBSD Foundation, Inc.
@ -362,6 +362,7 @@
#define getdevmajor _getdevmajor
#define getdiskbyname _getdiskbyname
#define getdomainname _getdomainname
#define getentropy _getentropy
#define getfsent _getfsent
#define getfsfile _getfsfile
#define getfsspec _getfsspec