hw/usb/ccid-card-passthru.c - qemu - Git at Google

 /*
  * CCID Passthru Card Device emulation
  *
  * Copyright (c) 2011 Red Hat.
  * Written by Alon Levy.
  *
  * This work is licensed under the terms of the GNU GPL, version 2.1 or later.
  * See the COPYING file in the top-level directory.
  */

 #include "qemu/osdep.h"
 #include "qemu/units.h"
 #include <libcacard.h>
 #include "chardev/char-fe.h"
 #include "qemu/error-report.h"
 #include "qemu/sockets.h"
 #include "ccid.h"
 #include "qapi/error.h"

 #define DPRINTF(card, lvl, fmt, ...)                    \
 do {                                                    \
     if (lvl <= card->debug) {                           \
         printf("ccid-card-passthru: " fmt , ## __VA_ARGS__);     \
     }                                                   \
 } while (0)

 #define D_WARN 1
 #define D_INFO 2
 #define D_MORE_INFO 3
 #define D_VERBOSE 4

 /* TODO: do we still need this? */
 static const uint8_t DEFAULT_ATR[] = {
 /*
  * From some example somewhere
  * 0x3B, 0xB0, 0x18, 0x00, 0xD1, 0x81, 0x05, 0xB1, 0x40, 0x38, 0x1F, 0x03, 0x28
  */

 /* From an Athena smart card */
  0x3B, 0xD5, 0x18, 0xFF, 0x80, 0x91, 0xFE, 0x1F, 0xC3, 0x80, 0x73, 0xC8, 0x21,
  0x13, 0x08
 };

 #define VSCARD_IN_SIZE      (64 * KiB)

 /* maximum size of ATR - from 7816-3 */
 #define MAX_ATR_SIZE        40

 typedef struct PassthruState PassthruState;

 struct PassthruState {
     CCIDCardState base;
     CharBackend cs;
     uint8_t  vscard_in_data[VSCARD_IN_SIZE];
     uint32_t vscard_in_pos;
     uint32_t vscard_in_hdr;
     uint8_t  atr[MAX_ATR_SIZE];
     uint8_t  atr_length;
     uint8_t  debug;
 };

 #define TYPE_CCID_PASSTHRU "ccid-card-passthru"
 #define PASSTHRU_CCID_CARD(obj) \
     OBJECT_CHECK(PassthruState, (obj), TYPE_CCID_PASSTHRU)

 /*
  * VSCard protocol over chardev
  * This code should not depend on the card type.
  */

 static void ccid_card_vscard_send_msg(PassthruState *s,
         VSCMsgType type, uint32_t reader_id,
         const uint8_t *payload, uint32_t length)
 {
     VSCMsgHeader scr_msg_header;

     scr_msg_header.type = htonl(type);
     scr_msg_header.reader_id = htonl(reader_id);
     scr_msg_header.length = htonl(length);
     /* XXX this blocks entire thread. Rewrite to use
      * qemu_chr_fe_write and background I/O callbacks */
     qemu_chr_fe_write_all(&s->cs, (uint8_t *)&scr_msg_header,
                           sizeof(VSCMsgHeader));
     qemu_chr_fe_write_all(&s->cs, payload, length);
 }

 static void ccid_card_vscard_send_apdu(PassthruState *s,
     const uint8_t *apdu, uint32_t length)
 {
     ccid_card_vscard_send_msg(
         s, VSC_APDU, VSCARD_MINIMAL_READER_ID, apdu, length);
 }

 static void ccid_card_vscard_send_error(PassthruState *s,
                     uint32_t reader_id, VSCErrorCode code)
 {
     VSCMsgError msg = {.code = htonl(code)};

     ccid_card_vscard_send_msg(
         s, VSC_Error, reader_id, (uint8_t *)&msg, sizeof(msg));
 }

 static void ccid_card_vscard_send_init(PassthruState *s)
 {
     VSCMsgInit msg = {
         .version = htonl(VSCARD_VERSION),
         .magic = VSCARD_MAGIC,
         .capabilities = {0}
     };

     ccid_card_vscard_send_msg(s, VSC_Init, VSCARD_UNDEFINED_READER_ID,
                          (uint8_t *)&msg, sizeof(msg));
 }

 static int ccid_card_vscard_can_read(void *opaque)
 {
     PassthruState *card = opaque;

     return VSCARD_IN_SIZE >= card->vscard_in_pos ?
            VSCARD_IN_SIZE - card->vscard_in_pos : 0;
 }

 static void ccid_card_vscard_handle_init(
     PassthruState *card, VSCMsgHeader *hdr, VSCMsgInit *init)
 {
     uint32_t *capabilities;
     int num_capabilities;
     int i;

     capabilities = init->capabilities;
     num_capabilities =
         1 + ((hdr->length - sizeof(VSCMsgInit)) / sizeof(uint32_t));
     init->version = ntohl(init->version);
     for (i = 0 ; i < num_capabilities; ++i) {
         capabilities[i] = ntohl(capabilities[i]);
     }
     if (init->magic != VSCARD_MAGIC) {
         error_report("wrong magic");
         /* we can't disconnect the chardev */
     }
     if (init->version != VSCARD_VERSION) {
         DPRINTF(card, D_WARN,
             "got version %d, have %d", init->version, VSCARD_VERSION);
     }
     /* future handling of capabilities, none exist atm */
     ccid_card_vscard_send_init(card);
 }

 static int check_atr(PassthruState *card, uint8_t *data, int len)
 {
     int historical_length, opt_bytes;
     int td_count = 0;
     int td;

     if (len < 2) {
         return 0;
     }
     historical_length = data[1] & 0xf;
     opt_bytes = 0;
     if (data[0] != 0x3b && data[0] != 0x3f) {
         DPRINTF(card, D_WARN, "atr's T0 is 0x%X, not in {0x3b, 0x3f}\n",
                 data[0]);
         return 0;
     }
     td_count = 0;
     td = data[1] >> 4;
     while (td && td_count < 2 && opt_bytes + historical_length + 2 < len) {
         td_count++;
         if (td & 0x1) {
             opt_bytes++;
         }
         if (td & 0x2) {
             opt_bytes++;
         }
         if (td & 0x4) {
             opt_bytes++;
         }
         if (td & 0x8) {
             opt_bytes++;
             td = data[opt_bytes + 2] >> 4;
         }
     }
     if (len < 2 + historical_length + opt_bytes) {
         DPRINTF(card, D_WARN,
             "atr too short: len %d, but historical_len %d, T1 0x%X\n",
             len, historical_length, data[1]);
         return 0;
     }
     if (len > 2 + historical_length + opt_bytes) {
         DPRINTF(card, D_WARN,
             "atr too long: len %d, but hist/opt %d/%d, T1 0x%X\n",
             len, historical_length, opt_bytes, data[1]);
         /* let it through */
     }
     DPRINTF(card, D_VERBOSE,
             "atr passes check: %d total length, %d historical, %d optional\n",
             len, historical_length, opt_bytes);

     return 1;
 }

 static void ccid_card_vscard_handle_message(PassthruState *card,
     VSCMsgHeader *scr_msg_header)
 {
     uint8_t *data = (uint8_t *)&scr_msg_header[1];

     switch (scr_msg_header->type) {
     case VSC_ATR:
         DPRINTF(card, D_INFO, "VSC_ATR %d\n", scr_msg_header->length);
         if (scr_msg_header->length > MAX_ATR_SIZE) {
             error_report("ATR size exceeds spec, ignoring");
             ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
                                         VSC_GENERAL_ERROR);
             break;
         }
         if (!check_atr(card, data, scr_msg_header->length)) {
             error_report("ATR is inconsistent, ignoring");
             ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
                                         VSC_GENERAL_ERROR);
             break;
         }
         memcpy(card->atr, data, scr_msg_header->length);
         card->atr_length = scr_msg_header->length;
         ccid_card_card_inserted(&card->base);
         ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
                                     VSC_SUCCESS);
         break;
     case VSC_APDU:
         ccid_card_send_apdu_to_guest(
             &card->base, data, scr_msg_header->length);
         break;
     case VSC_CardRemove:
         DPRINTF(card, D_INFO, "VSC_CardRemove\n");
         ccid_card_card_removed(&card->base);
         ccid_card_vscard_send_error(card,
             scr_msg_header->reader_id, VSC_SUCCESS);
         break;
     case VSC_Init:
         ccid_card_vscard_handle_init(
             card, scr_msg_header, (VSCMsgInit *)data);
         break;
     case VSC_Error:
         ccid_card_card_error(&card->base, *(uint32_t *)data);
         break;
     case VSC_ReaderAdd:
         if (ccid_card_ccid_attach(&card->base) < 0) {
             ccid_card_vscard_send_error(card, VSCARD_UNDEFINED_READER_ID,
                                       VSC_CANNOT_ADD_MORE_READERS);
         } else {
             ccid_card_vscard_send_error(card, VSCARD_MINIMAL_READER_ID,
                                         VSC_SUCCESS);
         }
         break;
     case VSC_ReaderRemove:
         ccid_card_ccid_detach(&card->base);
         ccid_card_vscard_send_error(card,
             scr_msg_header->reader_id, VSC_SUCCESS);
         break;
     default:
         printf("usb-ccid: chardev: unexpected message of type %X\n",
                scr_msg_header->type);
         ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
             VSC_GENERAL_ERROR);
     }
 }

 static void ccid_card_vscard_drop_connection(PassthruState *card)
 {
     qemu_chr_fe_deinit(&card->cs, true);
     card->vscard_in_pos = card->vscard_in_hdr = 0;
 }

 static void ccid_card_vscard_read(void *opaque, const uint8_t *buf, int size)
 {
     PassthruState *card = opaque;
     VSCMsgHeader *hdr;

     if (card->vscard_in_pos + size > VSCARD_IN_SIZE) {
         error_report("no room for data: pos %u +  size %d > %" PRId64 "."
                      " dropping connection.",
                      card->vscard_in_pos, size, VSCARD_IN_SIZE);
         ccid_card_vscard_drop_connection(card);
         return;
     }
     assert(card->vscard_in_pos < VSCARD_IN_SIZE);
     assert(card->vscard_in_hdr < VSCARD_IN_SIZE);
     memcpy(card->vscard_in_data + card->vscard_in_pos, buf, size);
     card->vscard_in_pos += size;
     hdr = (VSCMsgHeader *)(card->vscard_in_data + card->vscard_in_hdr);

     while ((card->vscard_in_pos - card->vscard_in_hdr >= sizeof(VSCMsgHeader))
          &&(card->vscard_in_pos - card->vscard_in_hdr >=
                                   sizeof(VSCMsgHeader) + ntohl(hdr->length))) {
         hdr->reader_id = ntohl(hdr->reader_id);
         hdr->length = ntohl(hdr->length);
         hdr->type = ntohl(hdr->type);
         ccid_card_vscard_handle_message(card, hdr);
         card->vscard_in_hdr += hdr->length + sizeof(VSCMsgHeader);
         hdr = (VSCMsgHeader *)(card->vscard_in_data + card->vscard_in_hdr);
     }
     if (card->vscard_in_hdr == card->vscard_in_pos) {
         card->vscard_in_pos = card->vscard_in_hdr = 0;
     }
 }

 static void ccid_card_vscard_event(void *opaque, int event)
 {
     PassthruState *card = opaque;

     switch (event) {
     case CHR_EVENT_BREAK:
         card->vscard_in_pos = card->vscard_in_hdr = 0;
         break;
     case CHR_EVENT_OPENED:
         DPRINTF(card, D_INFO, "%s: CHR_EVENT_OPENED\n", __func__);
         break;
     }
 }

 /* End VSCard handling */

 static void passthru_apdu_from_guest(
     CCIDCardState *base, const uint8_t *apdu, uint32_t len)
 {
     PassthruState *card = PASSTHRU_CCID_CARD(base);

     if (!qemu_chr_fe_backend_connected(&card->cs)) {
         printf("ccid-passthru: no chardev, discarding apdu length %d\n", len);
         return;
     }
     ccid_card_vscard_send_apdu(card, apdu, len);
 }

 static const uint8_t *passthru_get_atr(CCIDCardState *base, uint32_t *len)
 {
     PassthruState *card = PASSTHRU_CCID_CARD(base);

     *len = card->atr_length;
     return card->atr;
 }

 static void passthru_realize(CCIDCardState *base, Error **errp)
 {
     PassthruState *card = PASSTHRU_CCID_CARD(base);

     card->vscard_in_pos = 0;
     card->vscard_in_hdr = 0;
     if (qemu_chr_fe_backend_connected(&card->cs)) {
         DPRINTF(card, D_INFO, "ccid-card-passthru: initing chardev");
         qemu_chr_fe_set_handlers(&card->cs,
             ccid_card_vscard_can_read,
             ccid_card_vscard_read,
             ccid_card_vscard_event, NULL, card, NULL, true);
         ccid_card_vscard_send_init(card);
     } else {
         error_setg(errp, "missing chardev");
         return;
     }
     card->debug = parse_debug_env("QEMU_CCID_PASSTHRU_DEBUG", D_VERBOSE,
                                   card->debug);
     assert(sizeof(DEFAULT_ATR) <= MAX_ATR_SIZE);
     memcpy(card->atr, DEFAULT_ATR, sizeof(DEFAULT_ATR));
     card->atr_length = sizeof(DEFAULT_ATR);
 }

 static VMStateDescription passthru_vmstate = {
     .name = "ccid-card-passthru",
     .version_id = 1,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_BUFFER(vscard_in_data, PassthruState),
         VMSTATE_UINT32(vscard_in_pos, PassthruState),
         VMSTATE_UINT32(vscard_in_hdr, PassthruState),
         VMSTATE_BUFFER(atr, PassthruState),
         VMSTATE_UINT8(atr_length, PassthruState),
         VMSTATE_END_OF_LIST()
     }
 };

 static Property passthru_card_properties[] = {
     DEFINE_PROP_CHR("chardev", PassthruState, cs),
     DEFINE_PROP_UINT8("debug", PassthruState, debug, 0),
     DEFINE_PROP_END_OF_LIST(),
 };

 static void passthru_class_initfn(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     CCIDCardClass *cc = CCID_CARD_CLASS(klass);

     cc->realize = passthru_realize;
     cc->get_atr = passthru_get_atr;
     cc->apdu_from_guest = passthru_apdu_from_guest;
     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
     dc->desc = "passthrough smartcard";
     dc->vmsd = &passthru_vmstate;
     dc->props = passthru_card_properties;
 }

 static const TypeInfo passthru_card_info = {
     .name          = TYPE_CCID_PASSTHRU,
     .parent        = TYPE_CCID_CARD,
     .instance_size = sizeof(PassthruState),
     .class_init    = passthru_class_initfn,
 };

 static void ccid_card_passthru_register_types(void)
 {
     type_register_static(&passthru_card_info);
 }

 type_init(ccid_card_passthru_register_types)
	/*
	* CCID Passthru Card Device emulation
	*
	* Copyright (c) 2011 Red Hat.
	* Written by Alon Levy.
	*
	* This work is licensed under the terms of the GNU GPL, version 2.1 or later.
	* See the COPYING file in the top-level directory.
	*/

	#include "qemu/osdep.h"
	#include "qemu/units.h"
	#include <libcacard.h>
	#include "chardev/char-fe.h"
	#include "qemu/error-report.h"
	#include "qemu/sockets.h"
	#include "ccid.h"
	#include "qapi/error.h"

	#define DPRINTF(card, lvl, fmt, ...) \
	do { \
	if (lvl <= card->debug) { \
	printf("ccid-card-passthru: " fmt , ## __VA_ARGS__); \
	} \
	} while (0)

	#define D_WARN 1
	#define D_INFO 2
	#define D_MORE_INFO 3
	#define D_VERBOSE 4

	/* TODO: do we still need this? */
	static const uint8_t DEFAULT_ATR[] = {
	/*
	* From some example somewhere
	* 0x3B, 0xB0, 0x18, 0x00, 0xD1, 0x81, 0x05, 0xB1, 0x40, 0x38, 0x1F, 0x03, 0x28
	*/

	/* From an Athena smart card */
	0x3B, 0xD5, 0x18, 0xFF, 0x80, 0x91, 0xFE, 0x1F, 0xC3, 0x80, 0x73, 0xC8, 0x21,
	0x13, 0x08
	};

	#define VSCARD_IN_SIZE (64 * KiB)

	/* maximum size of ATR - from 7816-3 */
	#define MAX_ATR_SIZE 40

	typedef struct PassthruState PassthruState;

	struct PassthruState {
	CCIDCardState base;
	CharBackend cs;
	uint8_t vscard_in_data[VSCARD_IN_SIZE];
	uint32_t vscard_in_pos;
	uint32_t vscard_in_hdr;
	uint8_t atr[MAX_ATR_SIZE];
	uint8_t atr_length;
	uint8_t debug;
	};

	#define TYPE_CCID_PASSTHRU "ccid-card-passthru"
	#define PASSTHRU_CCID_CARD(obj) \
	OBJECT_CHECK(PassthruState, (obj), TYPE_CCID_PASSTHRU)

	/*
	* VSCard protocol over chardev
	* This code should not depend on the card type.
	*/

	static void ccid_card_vscard_send_msg(PassthruState *s,
	VSCMsgType type, uint32_t reader_id,
	const uint8_t *payload, uint32_t length)
	{
	VSCMsgHeader scr_msg_header;

	scr_msg_header.type = htonl(type);
	scr_msg_header.reader_id = htonl(reader_id);
	scr_msg_header.length = htonl(length);
	/* XXX this blocks entire thread. Rewrite to use
	* qemu_chr_fe_write and background I/O callbacks */
	qemu_chr_fe_write_all(&s->cs, (uint8_t *)&scr_msg_header,
	sizeof(VSCMsgHeader));
	qemu_chr_fe_write_all(&s->cs, payload, length);
	}

	static void ccid_card_vscard_send_apdu(PassthruState *s,
	const uint8_t *apdu, uint32_t length)
	{
	ccid_card_vscard_send_msg(
	s, VSC_APDU, VSCARD_MINIMAL_READER_ID, apdu, length);
	}

	static void ccid_card_vscard_send_error(PassthruState *s,
	uint32_t reader_id, VSCErrorCode code)
	{
	VSCMsgError msg = {.code = htonl(code)};

	ccid_card_vscard_send_msg(
	s, VSC_Error, reader_id, (uint8_t *)&msg, sizeof(msg));
	}

	static void ccid_card_vscard_send_init(PassthruState *s)
	{
	VSCMsgInit msg = {
	.version = htonl(VSCARD_VERSION),
	.magic = VSCARD_MAGIC,
	.capabilities = {0}
	};

	ccid_card_vscard_send_msg(s, VSC_Init, VSCARD_UNDEFINED_READER_ID,
	(uint8_t *)&msg, sizeof(msg));
	}

	static int ccid_card_vscard_can_read(void *opaque)
	{
	PassthruState *card = opaque;

	return VSCARD_IN_SIZE >= card->vscard_in_pos ?
	VSCARD_IN_SIZE - card->vscard_in_pos : 0;
	}

	static void ccid_card_vscard_handle_init(
	PassthruState card, VSCMsgHeader hdr, VSCMsgInit *init)
	{
	uint32_t *capabilities;
	int num_capabilities;
	int i;

	capabilities = init->capabilities;
	num_capabilities =
	1 + ((hdr->length - sizeof(VSCMsgInit)) / sizeof(uint32_t));
	init->version = ntohl(init->version);
	for (i = 0 ; i < num_capabilities; ++i) {
	capabilities[i] = ntohl(capabilities[i]);
	}
	if (init->magic != VSCARD_MAGIC) {
	error_report("wrong magic");
	/* we can't disconnect the chardev */
	}
	if (init->version != VSCARD_VERSION) {
	DPRINTF(card, D_WARN,
	"got version %d, have %d", init->version, VSCARD_VERSION);
	}
	/* future handling of capabilities, none exist atm */
	ccid_card_vscard_send_init(card);
	}

	static int check_atr(PassthruState card, uint8_t data, int len)
	{
	int historical_length, opt_bytes;
	int td_count = 0;
	int td;

	if (len < 2) {
	return 0;
	}
	historical_length = data[1] & 0xf;
	opt_bytes = 0;
	if (data[0] != 0x3b && data[0] != 0x3f) {
	DPRINTF(card, D_WARN, "atr's T0 is 0x%X, not in {0x3b, 0x3f}\n",
	data[0]);
	return 0;
	}
	td_count = 0;
	td = data[1] >> 4;
	while (td && td_count < 2 && opt_bytes + historical_length + 2 < len) {
	td_count++;
	if (td & 0x1) {
	opt_bytes++;
	}
	if (td & 0x2) {
	opt_bytes++;
	}
	if (td & 0x4) {
	opt_bytes++;
	}
	if (td & 0x8) {
	opt_bytes++;
	td = data[opt_bytes + 2] >> 4;
	}
	}
	if (len < 2 + historical_length + opt_bytes) {
	DPRINTF(card, D_WARN,
	"atr too short: len %d, but historical_len %d, T1 0x%X\n",
	len, historical_length, data[1]);
	return 0;
	}
	if (len > 2 + historical_length + opt_bytes) {
	DPRINTF(card, D_WARN,
	"atr too long: len %d, but hist/opt %d/%d, T1 0x%X\n",
	len, historical_length, opt_bytes, data[1]);
	/* let it through */
	}
	DPRINTF(card, D_VERBOSE,
	"atr passes check: %d total length, %d historical, %d optional\n",
	len, historical_length, opt_bytes);

	return 1;
	}

	static void ccid_card_vscard_handle_message(PassthruState *card,
	VSCMsgHeader *scr_msg_header)
	{
	uint8_t data = (uint8_t )&scr_msg_header[1];

	switch (scr_msg_header->type) {
	case VSC_ATR:
	DPRINTF(card, D_INFO, "VSC_ATR %d\n", scr_msg_header->length);
	if (scr_msg_header->length > MAX_ATR_SIZE) {
	error_report("ATR size exceeds spec, ignoring");
	ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
	VSC_GENERAL_ERROR);
	break;
	}
	if (!check_atr(card, data, scr_msg_header->length)) {
	error_report("ATR is inconsistent, ignoring");
	ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
	VSC_GENERAL_ERROR);
	break;
	}
	memcpy(card->atr, data, scr_msg_header->length);
	card->atr_length = scr_msg_header->length;
	ccid_card_card_inserted(&card->base);
	ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
	VSC_SUCCESS);
	break;
	case VSC_APDU:
	ccid_card_send_apdu_to_guest(
	&card->base, data, scr_msg_header->length);
	break;
	case VSC_CardRemove:
	DPRINTF(card, D_INFO, "VSC_CardRemove\n");
	ccid_card_card_removed(&card->base);
	ccid_card_vscard_send_error(card,
	scr_msg_header->reader_id, VSC_SUCCESS);
	break;
	case VSC_Init:
	ccid_card_vscard_handle_init(
	card, scr_msg_header, (VSCMsgInit *)data);
	break;
	case VSC_Error:
	ccid_card_card_error(&card->base, (uint32_t )data);
	break;
	case VSC_ReaderAdd:
	if (ccid_card_ccid_attach(&card->base) < 0) {
	ccid_card_vscard_send_error(card, VSCARD_UNDEFINED_READER_ID,
	VSC_CANNOT_ADD_MORE_READERS);
	} else {
	ccid_card_vscard_send_error(card, VSCARD_MINIMAL_READER_ID,
	VSC_SUCCESS);
	}
	break;
	case VSC_ReaderRemove:
	ccid_card_ccid_detach(&card->base);
	ccid_card_vscard_send_error(card,
	scr_msg_header->reader_id, VSC_SUCCESS);
	break;
	default:
	printf("usb-ccid: chardev: unexpected message of type %X\n",
	scr_msg_header->type);
	ccid_card_vscard_send_error(card, scr_msg_header->reader_id,
	VSC_GENERAL_ERROR);
	}
	}

	static void ccid_card_vscard_drop_connection(PassthruState *card)
	{
	qemu_chr_fe_deinit(&card->cs, true);
	card->vscard_in_pos = card->vscard_in_hdr = 0;
	}

	static void ccid_card_vscard_read(void opaque, const uint8_t buf, int size)
	{
	PassthruState *card = opaque;
	VSCMsgHeader *hdr;

	if (card->vscard_in_pos + size > VSCARD_IN_SIZE) {
	error_report("no room for data: pos %u + size %d > %" PRId64 "."
	" dropping connection.",
	card->vscard_in_pos, size, VSCARD_IN_SIZE);
	ccid_card_vscard_drop_connection(card);
	return;
	}
	assert(card->vscard_in_pos < VSCARD_IN_SIZE);
	assert(card->vscard_in_hdr < VSCARD_IN_SIZE);
	memcpy(card->vscard_in_data + card->vscard_in_pos, buf, size);
	card->vscard_in_pos += size;
	hdr = (VSCMsgHeader *)(card->vscard_in_data + card->vscard_in_hdr);

	while ((card->vscard_in_pos - card->vscard_in_hdr >= sizeof(VSCMsgHeader))
	&&(card->vscard_in_pos - card->vscard_in_hdr >=
	sizeof(VSCMsgHeader) + ntohl(hdr->length))) {
	hdr->reader_id = ntohl(hdr->reader_id);
	hdr->length = ntohl(hdr->length);
	hdr->type = ntohl(hdr->type);
	ccid_card_vscard_handle_message(card, hdr);
	card->vscard_in_hdr += hdr->length + sizeof(VSCMsgHeader);
	hdr = (VSCMsgHeader *)(card->vscard_in_data + card->vscard_in_hdr);
	}
	if (card->vscard_in_hdr == card->vscard_in_pos) {
	card->vscard_in_pos = card->vscard_in_hdr = 0;
	}
	}

	static void ccid_card_vscard_event(void *opaque, int event)
	{
	PassthruState *card = opaque;

	switch (event) {
	case CHR_EVENT_BREAK:
	card->vscard_in_pos = card->vscard_in_hdr = 0;
	break;
	case CHR_EVENT_OPENED:
	DPRINTF(card, D_INFO, "%s: CHR_EVENT_OPENED\n", __func__);
	break;
	}
	}

	/* End VSCard handling */

	static void passthru_apdu_from_guest(
	CCIDCardState base, const uint8_t apdu, uint32_t len)
	{
	PassthruState *card = PASSTHRU_CCID_CARD(base);

	if (!qemu_chr_fe_backend_connected(&card->cs)) {
	printf("ccid-passthru: no chardev, discarding apdu length %d\n", len);
	return;
	}
	ccid_card_vscard_send_apdu(card, apdu, len);
	}

	static const uint8_t passthru_get_atr(CCIDCardState base, uint32_t *len)
	{
	PassthruState *card = PASSTHRU_CCID_CARD(base);

	*len = card->atr_length;
	return card->atr;
	}

	static void passthru_realize(CCIDCardState base, Error *errp)
	{
	PassthruState *card = PASSTHRU_CCID_CARD(base);

	card->vscard_in_pos = 0;
	card->vscard_in_hdr = 0;
	if (qemu_chr_fe_backend_connected(&card->cs)) {
	DPRINTF(card, D_INFO, "ccid-card-passthru: initing chardev");
	qemu_chr_fe_set_handlers(&card->cs,
	ccid_card_vscard_can_read,
	ccid_card_vscard_read,
	ccid_card_vscard_event, NULL, card, NULL, true);
	ccid_card_vscard_send_init(card);
	} else {
	error_setg(errp, "missing chardev");
	return;
	}
	card->debug = parse_debug_env("QEMU_CCID_PASSTHRU_DEBUG", D_VERBOSE,
	card->debug);
	assert(sizeof(DEFAULT_ATR) <= MAX_ATR_SIZE);
	memcpy(card->atr, DEFAULT_ATR, sizeof(DEFAULT_ATR));
	card->atr_length = sizeof(DEFAULT_ATR);
	}

	static VMStateDescription passthru_vmstate = {
	.name = "ccid-card-passthru",
	.version_id = 1,
	.minimum_version_id = 1,
	.fields = (VMStateField[]) {
	VMSTATE_BUFFER(vscard_in_data, PassthruState),
	VMSTATE_UINT32(vscard_in_pos, PassthruState),
	VMSTATE_UINT32(vscard_in_hdr, PassthruState),
	VMSTATE_BUFFER(atr, PassthruState),
	VMSTATE_UINT8(atr_length, PassthruState),
	VMSTATE_END_OF_LIST()
	}
	};

	static Property passthru_card_properties[] = {
	DEFINE_PROP_CHR("chardev", PassthruState, cs),
	DEFINE_PROP_UINT8("debug", PassthruState, debug, 0),
	DEFINE_PROP_END_OF_LIST(),
	};

	static void passthru_class_initfn(ObjectClass klass, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(klass);
	CCIDCardClass *cc = CCID_CARD_CLASS(klass);

	cc->realize = passthru_realize;
	cc->get_atr = passthru_get_atr;
	cc->apdu_from_guest = passthru_apdu_from_guest;
	set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
	dc->desc = "passthrough smartcard";
	dc->vmsd = &passthru_vmstate;
	dc->props = passthru_card_properties;
	}

	static const TypeInfo passthru_card_info = {
	.name = TYPE_CCID_PASSTHRU,
	.parent = TYPE_CCID_CARD,
	.instance_size = sizeof(PassthruState),
	.class_init = passthru_class_initfn,
	};

	static void ccid_card_passthru_register_types(void)
	{
	type_register_static(&passthru_card_info);
	}

	type_init(ccid_card_passthru_register_types)