factotum/libressl-portable
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override native arc4random_buf on FreeBSD

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The FreeBSD-native arc4random_buf implementation falls back to weak
sources of entropy if the sysctl fails. Remove these dangerous fallbacks
by overriding locally.

Unfortunately, pthread_atfork() is broken on FreeBSD (at least 9 and 10)
if a program does not link to -lthr. Callbacks registered with
pthread_atfork() simply fail silently. So, it is not always possible to
detect a PID wraparound. I wish we could do better.

This improves arc4random_buf's safety compared to the native FreeBSD
implementation. Tested on FreeBSD 9 and 10.

ok beck@ deraadt@
This commit is contained in:
Brent Cook
2014-10-27 19:22:03 -05:00
parent 8abf8e1e15
commit 0aeb93b9fc
5 changed files with 19 additions and 4 deletions
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4
crypto/Makefile.am.tpl
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@@ -61,6 +61,9 @@ if !HAVE_ARC4RANDOM_BUF
libcompat_la_SOURCES += compat/arc4random.c
if !HAVE_GETENTROPY
if HOST_FREEBSD
libcompat_la_SOURCES += compat/getentropy_freebsd.c
endif
if HOST_LINUX
libcompat_la_SOURCES += compat/getentropy_linux.c
endif
@@ -88,6 +91,7 @@ endif
noinst_HEADERS = des/ncbc_enc.c
noinst_HEADERS += compat/arc4random.h
noinst_HEADERS += compat/arc4random_freebsd.h
noinst_HEADERS += compat/arc4random_linux.h
noinst_HEADERS += compat/arc4random_osx.h
noinst_HEADERS += compat/arc4random_solaris.h

7
crypto/compat/arc4random.h
View File

@@ -1,7 +1,12 @@
#ifndef LIBCRYPTOCOMPAT_ARC4RANDOM_H
#define LIBCRYPTOCOMPAT_ARC4RANDOM_H
#if defined(__linux__)
#include <sys/param.h>
#if defined(__FreeBSD__)
#include "arc4random_freebsd.h"
#elif defined(__linux__)
#include "arc4random_linux.h"
#elif defined(__APPLE__)