From 45443583df0ece8523f6b9038e305fa6c01b63f7 Mon Sep 17 00:00:00 2001 From: Guillem Jover Date: Wed, 23 Sep 2015 19:37:37 +0200 Subject: [PATCH] Add explicit_bzero() function from OpenBSD --- include/bsd/string.h | 2 ++ man/Makefile.am | 1 + man/explicit_bzero.3 | 72 ++++++++++++++++++++++++++++++++++++++++++++ src/Makefile.am | 1 + src/explicit_bzero.c | 19 ++++++++++++ src/libbsd.map | 4 +++ test/.gitignore | 1 + test/Makefile.am | 1 + test/bzero.c | 47 +++++++++++++++++++++++++++++ 9 files changed, 148 insertions(+) create mode 100644 man/explicit_bzero.3 create mode 100644 src/explicit_bzero.c create mode 100644 test/bzero.c diff --git a/include/bsd/string.h b/include/bsd/string.h index a2d54b3..ee2f953 100644 --- a/include/bsd/string.h +++ b/include/bsd/string.h @@ -41,6 +41,8 @@ size_t strlcpy(char *dst, const char *src, size_t siz); size_t strlcat(char *dst, const char *src, size_t siz); char *strnstr(const char *str, const char *find, size_t str_len); void strmode(mode_t mode, char *str); + +void explicit_bzero(void *buf, size_t len); __END_DECLS #endif diff --git a/man/Makefile.am b/man/Makefile.am index 1456ef7..f3bcd50 100644 --- a/man/Makefile.am +++ b/man/Makefile.am @@ -23,6 +23,7 @@ dist_man_MANS = \ closefrom.3 \ dehumanize_number.3 \ expand_number.3 \ + explicit_bzero.3 \ fgetln.3 \ fgetwln.3 \ flopen.3 \ diff --git a/man/explicit_bzero.3 b/man/explicit_bzero.3 new file mode 100644 index 0000000..2bed62a --- /dev/null +++ b/man/explicit_bzero.3 @@ -0,0 +1,72 @@ +.\" Copyright (c) 1990, 1991 The Regents of the University of California. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" Chris Torek. +.\" 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. +.\" 3. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. +.\" +.\" $OpenBSD: bzero.3,v 1.10 2014/01/22 21:06:45 tedu Exp $ +.\" +.Dd $Mdocdate: January 22 2014 $ +.Dt BZERO 3 +.Os +.Sh NAME +.Nm explicit_bzero +.Nd write zeroes to a byte string +.Sh LIBRARY +.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd) +.Lb libbsd +.Sh SYNOPSIS +.In bsd/string.h +.Ft void +.Fn explicit_bzero "void *buf" "size_t len" +.Sh DESCRIPTION +The +.Fn explicit_bzero +function writes +.Fa len +zero bytes to the string +.Fa buf . +If +.Fa len +is zero, +.Fn explicit_bzero +does nothing. +.Pp +The +.Fn explicit_bzero +variant behaves the same as the +.Fn bzero +function, but will not be removed by a compiler's dead store optimization +pass, making it useful for clearing sensitive memory such as a password. +.Sh SEE ALSO +.Xr bzero 3 , +.Xr memset 3 , +.Xr swab 3 +.Sh HISTORY +The +.Fn explicit_bzero +function first appeared in +.Ox 5.5 . diff --git a/src/Makefile.am b/src/Makefile.am index de1fe34..1cb04f9 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -50,6 +50,7 @@ libbsd_la_SOURCES = \ dehumanize_number.c \ err.c \ expand_number.c \ + explicit_bzero.c \ fgetln.c \ fgetwln.c \ flopen.c \ diff --git a/src/explicit_bzero.c b/src/explicit_bzero.c new file mode 100644 index 0000000..3e33ca8 --- /dev/null +++ b/src/explicit_bzero.c @@ -0,0 +1,19 @@ +/* $OpenBSD: explicit_bzero.c,v 1.3 2014/06/21 02:34:26 matthew Exp $ */ +/* + * Public domain. + * Written by Matthew Dempsky. + */ + +#include + +__attribute__((weak)) void +__explicit_bzero_hook(void *buf, size_t len) +{ +} + +void +explicit_bzero(void *buf, size_t len) +{ + memset(buf, 0, len); + __explicit_bzero_hook(buf, len); +} diff --git a/src/libbsd.map b/src/libbsd.map index 29e84fd..2b9a3db 100644 --- a/src/libbsd.map +++ b/src/libbsd.map @@ -132,3 +132,7 @@ LIBBSD_0.7 { _time_to_int; _int_to_time; } LIBBSD_0.6; + +LIBBSD_0.8 { + explicit_bzero; +} LIBBSD_0.7; diff --git a/test/.gitignore b/test/.gitignore index e80dcb5..375be31 100644 --- a/test/.gitignore +++ b/test/.gitignore @@ -1,3 +1,4 @@ +bzero closefrom endian fgetln diff --git a/test/Makefile.am b/test/Makefile.am index 6d675e3..2576eeb 100644 --- a/test/Makefile.am +++ b/test/Makefile.am @@ -12,6 +12,7 @@ LDADD = $(top_builddir)/src/libbsd.la check_PROGRAMS = \ headers \ overlay \ + bzero \ closefrom \ endian \ humanize \ diff --git a/test/bzero.c b/test/bzero.c new file mode 100644 index 0000000..227b163 --- /dev/null +++ b/test/bzero.c @@ -0,0 +1,47 @@ +/* + * Copyright © 2015 Guillem Jover + * + * 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. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED ``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. + */ + +#include +#include + +int +main() +{ + unsigned char array[40]; + size_t i; + + memset(array, 0x3e, sizeof(array)); + + explicit_bzero(array, 0); + for (i = 0; i < sizeof(array); i++) + assert(array[i] == 0x3e); + + explicit_bzero(array, sizeof(array)); + for (i = 0; i < sizeof(array); i++) + assert(array[i] == 0); + + return 0; +}