package/wpa_supplicant: add Smart card option

CONFIG_SMARTCARD was unconditionally disabled which has meant that
even if OpenSSL is compiled with engine support and the supplicant is
configured to use an engine it would warn that it was compiled without
engine support.

This mechanism is used to enable the more secure forms of 802.1x
networking authentication such as EAP-TLS with hardware-delegated
cryptography and private keys protected in hardware.

Enabling the option will allow delegating private key access to TPM2,
ARM TrustZone and other specialized secure hardware for establishing a
network connection.

Signed-off-by: Lars Wikman <lars@underjord.io>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/wpa_supplicant/Config.in

@@ -175,4 +175,12 @@ config BR2_PACKAGE_WPA_SUPPLICANT_DBUS_INTROSPECTION
 	help
 	  Add introspection support for the DBus control interface.
 
+config BR2_PACKAGE_WPA_SUPPLICANT_SMARTCARD
+	bool "Smartcard support"
+	select BR2_PACKAGE_OPENSSL
+	select BR2_PACKAGE_OPENSSL_FORCE_LIBOPENSSL
+	help
+	  Enable the smart card support. Required for OpenSSL engines
+	  to work using PKCS11 and 802.1x
+
 endif

package/wpa_supplicant/wpa_supplicant.mk

@@ -24,9 +24,6 @@ WPA_SUPPLICANT_CONFIG_ENABLE = \
 	CONFIG_INTERNAL_LIBTOMMATH \
 	CONFIG_MATCH_IFACE
 
-WPA_SUPPLICANT_CONFIG_DISABLE = \
-	CONFIG_SMARTCARD
-
 # libnl-3 needs -lm (for rint) and -lpthread if linking statically
 # And library order matters hence stick -lnl-3 first since it's appended
 # in the wpa_supplicant Makefiles as in LIBS+=-lnl-3 ... thus failing
@@ -191,6 +188,12 @@ WPA_SUPPLICANT_DEPENDENCIES += readline
 WPA_SUPPLICANT_CONFIG_ENABLE += CONFIG_READLINE
 endif
 
+ifeq ($(BR2_PACKAGE_WPA_SUPPLICANT_SMARTCARD),y)
+WPA_SUPPLICANT_CONFIG_ENABLE += CONFIG_SMARTCARD
+else
+WPA_SUPPLICANT_CONFIG_DISABLE += CONFIG_SMARTCARD
+endif
+
 ifeq ($(BR2_PACKAGE_WPA_SUPPLICANT_CTRL_IFACE),y)
 define WPA_SUPPLICANT_ENABLE_CTRL_IFACE
 	sed -i '/ctrl_interface/s/^#//g' $(TARGET_DIR)/etc/wpa_supplicant.conf