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Synchronize on NetBSD-CVS (2013/12/1 12:00:00 UTC)

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- Fix for possible unset uid/gid in toproto
 - Fix for default mtree style
 - Update libelf
 - Importing libexecinfo
 - Resynchronize GCC, mpc, gmp, mpfr
 - build.sh: Replace params with show-params.
     This has been done as the make target has been renamed in the same
     way, while a new target named params has been added. This new
     target generates a file containing all the parameters, instead of
     printing it on the console.
 - Update test48 with new etc/services (Fix by Ben Gras <ben@minix3.org)
     get getservbyport() out of the inner loop

Change-Id: Ie6ad5226fa2621ff9f0dee8782ea48f9443d2091
This commit is contained in:
Lionel Sambuc
2013-12-06 12:04:52 +01:00
parent ff10274392
commit 84d9c625bf
4655 changed files with 379317 additions and 151059 deletions
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88
lib/libc/string/consttime_memequal.3 Normal file
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.\" $NetBSD: consttime_memequal.3,v 1.2 2013/08/28 15:24:41 riastradh Exp $
.\"
.\" Copyright (c) 2013 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This documentation is derived from text contributed to The NetBSD
.\" Foundation by Taylor R. Campbell.
.\"
.\" 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 August 28, 2013
.Dt CONSTTIME_MEMEQUAL 3
.Os
.Sh NAME
.Nm consttime_memequal
.Nd compare byte strings for equality without timing leaks
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In string.h
.Ft int
.Fn consttime_memequal "void *b1" "void *b2" "size_t len"
.Sh DESCRIPTION
The
.Fn consttime_memequal
function compares
.Fa len
bytes of memory at
.Fa b1
and
.Fa b2
for equality, returning zero if they are distinct and nonzero if they
are identical.
.Pp
The time taken by
.Fn consttime_memequal
depends on
.Fa len ,
but not on the data at
.Fa b1
or
.Fa b2 .
Thus,
.Fn consttime_memequal
is appropriate for comparing cryptographic secrets, hashes, message
authentication codes, etc., without leaking information about them
through a timing side channel.
In crypto literature,
.Fn consttime_memequal
is said to take
.Sq constant time ,
meaning time that does not vary depending on the data it processes.
.Pp
Note that unlike
.Xr memcmp 3 ,
.Fn consttime_memequal
does not return a lexicographic ordering on the data at
.Fa b1
and
.Fa b2 ;
it tells only whether they are equal.
.Sh SEE ALSO
.Xr explicit_memset 3 ,
.Xr memcmp 3
.Sh HISTORY
The
.Fn consttime_memequal
function appeared in
.Nx 7.0 .