update Changelog

Without this, we actually fail to build a library that includes the
bultin getentropy when compiling for 10.11 on 10.12.

ChangeLog

@@ -28,6 +28,19 @@ history is also available from Git.
 
 LibreSSL Portable Release Notes:
 
+2.3.10 - Security and compatibility fixes
+
+	* Avoid a side-channel cache-timing attack that can leak the ECDSA
+	  private keys when signing. This is due to BN_mod_inverse() being
+	  used without the constant time flag being set.
+
+	  This issue was reported by Cesar Pereida Garcia and Billy Brumley
+	  (Tampere University of Technology). The fix was developed by Cesar
+	  Pereida Garcia.
+
+	* iOS and MacOS compatibility updates from Simone Basso and Jacob
+	  Berkman.
+
 2.3.9 - Reliability improvements
 
 	* Avoid continual processing of an unlimited number of TLS records,

m4/check-libc.m4

@@ -47,7 +47,52 @@ AM_CONDITIONAL([HAVE_B64_NTOP], [test "x$ac_cv_func_b64_ntop_arg" = xyes])
 AC_DEFUN([CHECK_CRYPTO_COMPAT], [
 # Check crypto-related libc functions and syscalls
 AC_CHECK_FUNCS([arc4random arc4random_buf arc4random_uniform])
-AC_CHECK_FUNCS([explicit_bzero getauxval getentropy])
+AC_CHECK_FUNCS([explicit_bzero getauxval])
+
+AC_CACHE_CHECK([for getentropy], ac_cv_func_getentropy, [
+	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#include <sys/types.h>
+#include <unistd.h>
+
+/*
+ * Explanation:
+ *
+ *   - iOS <= 10.1 fails because of missing sys/random.h
+ *
+ *   - in macOS 10.12 getentropy is not tagged as introduced in
+ *     10.12 so we cannot use it for target < 10.12
+ */
+#ifdef __APPLE__
+#  include <AvailabilityMacros.h>
+#  include <TargetConditionals.h>
+
+# if (TARGET_OS_IPHONE || TARGET_OS_SIMULATOR)
+#  include <sys/random.h> /* Not available as of iOS <= 10.1 */
+# else
+
+#  include <sys/random.h> /* Pre 10.12 systems should die here */
+
+/* Based on: https://gitweb.torproject.org/tor.git/commit/?id=16fcbd21 */
+#  ifndef MAC_OS_X_VERSION_10_12
+#    define MAC_OS_X_VERSION_10_12 101200 /* Robustness */
+#  endif
+#  if defined(MAC_OS_X_VERSION_MIN_REQUIRED)
+#    if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_12
+#      error "Targeting on Mac OSX 10.11 or earlier"
+#    endif
+#  endif
+
+# endif
+#endif /* __APPLE__ */
+		]], [[
+	char buffer;
+	(void)getentropy(&buffer, sizeof (buffer));
+]])],
+	[ ac_cv_func_getentropy="yes" ],
+	[ ac_cv_func_getentropy="no"
+	])
+])
+
 AC_CHECK_FUNCS([timingsafe_bcmp timingsafe_memcmp])
 AM_CONDITIONAL([HAVE_ARC4RANDOM], [test "x$ac_cv_func_arc4random" = xyes])
 AM_CONDITIONAL([HAVE_ARC4RANDOM_BUF], [test "x$ac_cv_func_arc4random_buf" = xyes])

m4/check-os-options.m4

@@ -17,10 +17,45 @@ case $host_os in
 	*darwin*)
 		HOST_OS=darwin
 		HOST_ABI=macosx
+		#
+		# Don't use arc4random on systems before 10.12 because of
 		# weak seed on failure to open /dev/random, based on latest
 		# public source:
 		# http://www.opensource.apple.com/source/Libc/Libc-997.90.3/gen/FreeBSD/arc4random.c
-		USE_BUILTIN_ARC4RANDOM=yes
+		#
+		# We use the presence of getentropy() to detect 10.12. The
+		# following check take into account that:
+ 		#
+		#   - iOS <= 10.1 fails because of missing getentropy and
+		#     hence they miss sys/random.h
+		#
+		#   - in macOS 10.12 getentropy is not tagged as introduced in
+		#     10.12 so we cannot use it for target < 10.12
+		#
+		AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#include <AvailabilityMacros.h>
+#include <unistd.h>
+#include <sys/random.h>  /* Systems without getentropy() should die here */
+
+/* Based on: https://gitweb.torproject.org/tor.git/commit/?id=16fcbd21 */
+#ifndef MAC_OS_X_VERSION_10_12
+#  define MAC_OS_X_VERSION_10_12 101200
+#endif
+#if defined(MAC_OS_X_VERSION_MIN_REQUIRED)
+#  if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_12
+#    error "Running on Mac OSX 10.11 or earlier"
+#  endif
+#endif
+                       ]], [[
+char buf[1]; getentropy(buf, 1);
+					   ]])],
+                       [ USE_BUILTIN_ARC4RANDOM=no ],
+                       [ USE_BUILTIN_ARC4RANDOM=yes ]
+		)
+		AC_MSG_CHECKING([whether to use builtin arc4random])
+		AC_MSG_RESULT([$USE_BUILTIN_ARC4RANDOM])
+		# Not available on iOS
+		AC_CHECK_HEADER([arpa/telnet.h], [], [BUILD_NC=no])
 		;;
 	*freebsd*)
 		HOST_OS=freebsd