experimental nfc support on linux

joint work w/ Ludvig Michaelsson, who did a lot of the heavy
lifting. thank you!

README.adoc

@@ -23,6 +23,8 @@ file for the full license text.
 
 *libfido2* is known to work on Linux, MacOS, Windows, OpenBSD, and FreeBSD.
 
+On Linux, *experimental* NFC support is available in git HEAD.
+
 === Documentation
 
 Documentation is available in troff and HTML formats. An

src/CMakeLists.txt

@@ -44,7 +44,7 @@ elseif(WIN32)
 elseif(APPLE)
 	list(APPEND FIDO_SOURCES hid_osx.c)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
-	list(APPEND FIDO_SOURCES hid_linux.c hid_unix.c)
+	list(APPEND FIDO_SOURCES hid_linux.c hid_unix.c netlink.c nfc_linux.c)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "NetBSD")
 	list(APPEND FIDO_SOURCES hid_netbsd.c hid_unix.c)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")

src/dev.c

@@ -271,6 +271,11 @@ fido_dev_info_manifest(fido_dev_info_t *devlist, size_t ilen, size_t *olen)
 	if (fido_dev_register_manifest_func(fido_hid_manifest) != FIDO_OK)
 		return (FIDO_ERR_INTERNAL);
 
+#ifdef __linux__
+	if (fido_dev_register_manifest_func(fido_nfc_manifest) != FIDO_OK)
+		return (FIDO_ERR_INTERNAL);
+#endif
+
 	for (curr = manifest_funcs; curr != NULL; curr = curr->next) {
 		curr_olen = 0;
 		m_func = curr->manifest_func;
@@ -297,6 +302,28 @@ fido_dev_open_with_info(fido_dev_t *dev)
 int
 fido_dev_open(fido_dev_t *dev, const char *path)
 {
+#ifdef __linux__
+	/*
+	 * this is a hack to get existing applications up and running with nfc;
+	 * it will *NOT* be part of a libfido2 release. to support nfc in your
+	 * application, please change it to use fido_dev_open_with_info().
+	 */
+	if (strncmp(path, "/sys", strlen("/sys")) == 0 && strlen(path) > 4 &&
+	    path[strlen(path) - 4] == 'n' && path[strlen(path) - 3] == 'f' &&
+	    path[strlen(path) - 2] == 'c') {
+		dev->io_own = true;
+		dev->io = (fido_dev_io_t) {
+			fido_nfc_open,
+			fido_nfc_close,
+			fido_nfc_read,
+			fido_nfc_write,
+		};
+		dev->transport = (fido_dev_transport_t) {
+			fido_nfc_rx,
+			fido_nfc_tx,
+		};
+	}
+#endif
 	return (fido_dev_open_wait(dev, path, -1));
 }
 

src/extern.h

@@ -95,6 +95,14 @@ int fido_hid_unix_wait(int, int);
 size_t fido_hid_report_in_len(void *);
 size_t fido_hid_report_out_len(void *);
 
+/* nfc i/o */
+void *fido_nfc_open(const char *);
+void  fido_nfc_close(void *);
+int fido_nfc_read(void *, unsigned char *, size_t, int);
+int fido_nfc_write(void *, const unsigned char *, size_t);
+int fido_nfc_rx(fido_dev_t *, uint8_t, unsigned char *, size_t, int);
+int fido_nfc_tx(fido_dev_t *, uint8_t, const unsigned char *, size_t);
+
 /* generic i/o */
 int fido_rx_cbor_status(fido_dev_t *, int);
 int fido_rx(fido_dev_t *, uint8_t, void *, size_t, int);
@@ -150,8 +158,9 @@ int fido_verify_sig_eddsa(const fido_blob_t *, const eddsa_pk_t *,
 int fido_get_signed_hash(int, fido_blob_t *, const fido_blob_t *,
     const fido_blob_t *);
 
-/* hid device manifest */
+/* device manifest functions */
 int fido_hid_manifest(fido_dev_info_t *, size_t, size_t *);
+int fido_nfc_manifest(fido_dev_info_t *, size_t, size_t *);
 
 /* device manifest registration */
 typedef int (*dev_manifest_func_t)(fido_dev_info_t *, size_t, size_t *);

src/fido/param.h

@@ -43,6 +43,7 @@
 #define U2F_AUTH_CHECK			0x07
 
 /* ISO7816-4 status words. */
+#define SW1_MORE_DATA			0x61
 #define SW_CONDITIONS_NOT_SATISFIED	0x6985
 #define SW_WRONG_DATA			0x6a80
 #define SW_NO_ERROR			0x9000

src/iso7816.c

@@ -8,7 +8,7 @@
 #include "fido.h"
 
 iso7816_apdu_t *
-iso7816_new(uint8_t ins, uint8_t p1, uint16_t payload_len)
+iso7816_new(uint8_t cla, uint8_t ins, uint8_t p1, uint16_t payload_len)
 {
 	iso7816_apdu_t	*apdu;
 	size_t		 alloc_len;
@@ -21,6 +21,7 @@ iso7816_new(uint8_t ins, uint8_t p1, uint16_t payload_len)
 	apdu->alloc_len = alloc_len;
 	apdu->payload_len = payload_len;
 	apdu->payload_ptr = apdu->payload;
+	apdu->header.cla = cla;
 	apdu->header.ins = ins;
 	apdu->header.p1 = p1;
 	apdu->header.lc2 = (uint8_t)((payload_len >> 8) & 0xff);

src/iso7816.h

@@ -38,7 +38,7 @@ struct iso7816_apdu {
 
 const unsigned char *iso7816_ptr(const iso7816_apdu_t *);
 int iso7816_add(iso7816_apdu_t *, const void *, size_t);
-iso7816_apdu_t *iso7816_new(uint8_t, uint8_t, uint16_t);
+iso7816_apdu_t *iso7816_new(uint8_t, uint8_t, uint8_t, uint16_t);
 size_t iso7816_len(const iso7816_apdu_t *);
 void iso7816_free(iso7816_apdu_t **);