Support for wolfSSL in OpenVPN

This patch adds support for wolfSSL in OpenVPN. Support is added by using
wolfSSL's OpenSSL compatibility layer. Function calls are left unchanged
and instead the OpenSSL includes point to wolfSSL headers and OpenVPN is
linked against the wolfSSL library. The wolfSSL installation directory is
detected using pkg-config.

As requested by OpenVPN maintainers, this patch does not include
wolfssl/options.h on its own. By defining the macro EXTERNAL_OPTS_OPENVPN
in the configure script wolfSSL will include wolfssl/options.h on its own
(change added in https://github.com/wolfSSL/wolfssl/pull/2825). The patch
adds an option `--disable-wolfssl-options-h` in case the user would like
to supply their own settings file for wolfSSL.

wolfSSL:
Support added in: https://github.com/wolfSSL/wolfssl/pull/2503
```
git clone https://github.com/wolfSSL/wolfssl.git
cd wolfssl
./autogen.sh
./configure --enable-openvpn
make
sudo make install
```

OpenVPN:
```
autoreconf -i -v -f
./configure --with-crypto-library=wolfssl
make
make check
sudo make install
```

Signed-off-by: Juliusz Sosinowicz <juliusz@wolfssl.com>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20210317181153.83716-1-juliusz@wolfssl.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg21686.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

1 files changed, 108 insertions, 2 deletions

diff --git a/configure.ac b/configure.ac
index 54427d8..428bebe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -264,16 +264,23 @@ AC_ARG_WITH(
 
 AC_ARG_WITH(
 	[crypto-library],
-	[AS_HELP_STRING([--with-crypto-library=library], [build with the given crypto library, TYPE=openssl|mbedtls @<:@default=openssl@:>@])],
+	[AS_HELP_STRING([--with-crypto-library=library], [build with the given crypto library, TYPE=openssl|mbedtls|wolfssl @<:@default=openssl@:>@])],
 	[
 		case "${withval}" in
-			openssl|mbedtls) ;;
+			openssl|mbedtls|wolfssl) ;;
 			*) AC_MSG_ERROR([bad value ${withval} for --with-crypto-library]) ;;
 		esac
 	],
 	[with_crypto_library="openssl"]
 )
 
+AC_ARG_ENABLE(
+	[wolfssl-options-h],
+	[AS_HELP_STRING([--disable-wolfssl-options-h], [Disable including options.h in wolfSSL @<:@default=yes@:>@])],
+	,
+	[enable_wolfssl_options_h="yes"]
+)
+
 AC_ARG_VAR([PLUGINDIR], [Path of plug-in directory @<:@default=LIBDIR/openvpn/plugins@:>@])
 if test -n "${PLUGINDIR}"; then
 	plugindir="${PLUGINDIR}"
@@ -1019,6 +1026,105 @@ elif test "${with_crypto_library}" = "mbedtls"; then
 	AC_DEFINE([ENABLE_CRYPTO_MBEDTLS], [1], [Use mbed TLS library])
 	CRYPTO_CFLAGS="${MBEDTLS_CFLAGS}"
 	CRYPTO_LIBS="${MBEDTLS_LIBS}"
+
+elif test "${with_crypto_library}" = "wolfssl"; then
+	AC_ARG_VAR([WOLFSSL_CFLAGS], [C compiler flags for wolfssl. The include directory should
+								  contain the regular wolfSSL header files but also the
+								  wolfSSL OpenSSL header files. Ex: -I/usr/local/include
+								  -I/usr/local/include/wolfssl])
+	AC_ARG_VAR([WOLFSSL_LIBS], [linker flags for wolfssl])
+
+	saved_CFLAGS="${CFLAGS}"
+	saved_LIBS="${LIBS}"
+
+	if test -z "${WOLFSSL_CFLAGS}" -a -z "${WOLFSSL_LIBS}"; then
+		# if the user did not explicitly specify flags, try to autodetect
+		PKG_CHECK_MODULES(
+			[WOLFSSL],
+			[wolfssl],
+			[],
+			[AC_MSG_ERROR([Could not find wolfSSL.])]
+		)
+		PKG_CHECK_VAR(
+			[WOLFSSL_INCLUDEDIR],
+			[wolfssl],
+			[includedir],
+			[],
+			[AC_MSG_ERROR([Could not find wolfSSL includedir variable.])]
+		)
+		WOLFSSL_CFLAGS="${WOLFSSL_CFLAGS} -I${WOLFSSL_INCLUDEDIR}/wolfssl"
+	fi
+	saved_CFLAGS="${CFLAGS}"
+	saved_LIBS="${LIBS}"
+	CFLAGS="${CFLAGS} ${WOLFSSL_CFLAGS}"
+	LIBS="${LIBS} ${WOLFSSL_LIBS}"
+
+	AC_CHECK_LIB(
+		[wolfssl],
+		[wolfSSL_Init],
+		[],
+		[AC_MSG_ERROR([Could not link wolfSSL library.])]
+	)
+	AC_CHECK_HEADER([wolfssl/options.h],,[AC_MSG_ERROR([wolfSSL header wolfssl/options.h not found!])])
+
+	# wolfSSL signal EKM support
+	have_export_keying_material="yes"
+
+	AC_DEFINE([HAVE_HMAC_CTX_NEW], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_HMAC_CTX_FREE], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_HMAC_CTX_RESET], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_MD_CTX_NEW], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_MD_CTX_FREE], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_MD_CTX_RESET], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_CIPHER_CTX_RESET], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_OPENSSL_VERSION], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_SSL_CTX_GET_DEFAULT_PASSWD_CB], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_SSL_CTX_GET_DEFAULT_PASSWD_CB_USERDATA], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_SSL_CTX_SET_SECURITY_LEVEL], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_X509_GET0_NOTBEFORE], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_X509_GET0_NOTAFTER], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_X509_GET0_PUBKEY], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_X509_STORE_GET0_OBJECTS], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_X509_OBJECT_FREE], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_X509_OBJECT_GET_TYPE], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_PKEY_ID], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_PKEY_GET0_RSA], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_PKEY_GET0_DSA], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EVP_PKEY_GET0_EC_KEY], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_SET_FLAGS], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_BITS], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_GET0_KEY], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_SET0_KEY], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_DSA_GET0_PQG], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_DSA_BITS], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_NEW], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_FREE], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET_PUB_ENC], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET_PUB_DEC], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET_PRIV_ENC], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET_PRIV_DEC], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET_INIT], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET_SIGN], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET_FINISH], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_SET0_APP_DATA], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_RSA_METH_GET0_APP_DATA], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+	AC_DEFINE([HAVE_EC_GROUP_ORDER_BITS], [1], [Emulate AC_CHECK_FUNCS since these are defined as macros])
+
+	if test "${enable_wolfssl_options_h}" = "yes"; then
+		AC_DEFINE([EXTERNAL_OPTS_OPENVPN], [1], [Include options.h from wolfSSL library])
+	else
+		AC_DEFINE([WOLFSSL_USER_SETTINGS], [1], [Use custom user_settings.h file for wolfSSL library])
+	fi
+
+	have_export_keying_material="yes"
+
+	CFLAGS="${saved_CFLAGS}"
+	LIBS="${saved_LIBS}"
+
+	AC_DEFINE([ENABLE_CRYPTO_WOLFSSL], [1], [Use wolfSSL crypto library])
+	AC_DEFINE([ENABLE_CRYPTO_OPENSSL], [1], [Use wolfSSL openssl compatibility layer])
+	CRYPTO_CFLAGS="${WOLFSSL_CFLAGS}"
+	CRYPTO_LIBS="${WOLFSSL_LIBS}"
 else
 	AC_MSG_ERROR([Invalid crypto library: ${with_crypto_library}])
 fi