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Build: Avoid SHA256_Init on FreeBSD and MINIX 3. 

On FreeBSD 10 and older, SHA256_Init from libmd conflicts
with libcrypto from OpenSSL. The OpenSSL version has
different sizeof(SHA256_CTX) and it can cause weird
problems if wrong SHA256_Init gets used.

Looking at the source, MINIX 3 seems to have a similar issue but
I'm not sure. To be safe, I disabled SHA256_Init on MINIX 3 too.

NetBSD has SHA256_Init in libc and they had a similar problem,
but they already fixed it in 2009.

Thanks to Jim Wilcoxson for the bug report that helped
in finding the problem.
This commit is contained in:
Lasse Collin 2016-03-10 20:26:49 +02:00
parent faf302137e
commit 473ef0dc69
1 changed files with 21 additions and 6 deletions
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27
configure.ac
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@ -669,18 +669,32 @@ TUKLIB_PHYSMEM
TUKLIB_CPUCORES
TUKLIB_MBSTR
# Check for system-provided SHA-256. At least the following is supported:
# Check for system-provided SHA-256. The supported implementations are listed
# below. The detection for the ones marked with [*] has been intentionally
# disabled because they have symbol name conflicts with OpenSSL's libcrypto
# which can cause weird problems (clean namespaces would make things too
# boring, I guess).
#
# OS Headers Library Type Function
# FreeBSD sys/types.h + sha256.h libmd SHA256_CTX SHA256_Init
# FreeBSD sys/types.h + sha256.h libmd SHA256_CTX SHA256_Init [*]
# NetBSD sys/types.h + sha2.h SHA256_CTX SHA256_Init
# OpenBSD sys/types.h + sha2.h SHA2_CTX SHA256Init
# Solaris sys/types.h + sha2.h libmd SHA256_CTX SHA256Init
# MINIX 3 sys/types.h + minix/sha2.h libutil SHA256_CTX SHA256_Init
# MINIX 3 sys/types.h + minix/sha2.h libutil SHA256_CTX SHA256_Init [*]
# Darwin CommonCrypto/CommonDigest.h CC_SHA256_CTX CC_SHA256_Init
#
# Note that Darwin's CC_SHA256_Update takes buffer size as uint32_t instead
# of size_t.
# Notes:
#
# - NetBSD's SHA256_Init doesn't conflict with libcrypto because
# libcrypto on NetBSD was made to use the libc implementation to avoid
# this exact symbol conflict problem:
# http://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2009-012.txt.asc
#
# - As of 2016-03-10, FreeBSD seems to have the issue fixed in SVN head
# but not in the FreeBSD 10 branch.
#
# - Darwin's CC_SHA256_Update takes buffer size as uint32_t instead
# of size_t.
#
# We don't check for e.g. OpenSSL or libgcrypt because we don't want
# to introduce dependencies to other packages by default. Maybe such
@ -712,7 +726,8 @@ if test "x$enable_check_sha256" = "xyes"; then
#ifdef HAVE_MINIX_SHA2_H
# include <minix/sha2.h>
#endif]])
AC_SEARCH_LIBS([SHA256_Init], [md util])
dnl Omit detection of the FreeBSD and MINIX 3 versions:
dnl AC_SEARCH_LIBS([SHA256_Init], [md util])
AC_SEARCH_LIBS([SHA256Init], [md])
AC_CHECK_FUNCS([CC_SHA256_Init SHA256_Init SHA256Init],
[break])