Re: [Qemu-devel] [PATCH 4/7] ccid: add ccid-card-emulated device (v2)

[Anthony Liguori <anthony@codemonkey.ws>]

On 01/11/2011 02:42 AM, Alon Levy wrote:
> This devices uses libcacard (internal) to emulate a smartcard conforming
> to the CAC standard. It attaches to the usb-ccid bus. Usage instructions
> (example command lines) are in the following patch in docs/ccid.txt. It
> uses libcacard which uses nss, so it can work with both hw cards and
> certificates (files).
>
> changes from v1:
>      remove stale comments, use only c-style comments
>      bugfix, forgot to set recv_len
>      change reader name to 'Virtual Reader'
>
> Signed-off-by: Alon Levy<alevy@redhat.com>
> ---
>   Makefile.objs           |    2 +-
>   hw/ccid-card-emulated.c |  534 +++++++++++++++++++++++++++++++++++++++++++++++
>   hw/ccid-card-passthru.c |    1 -
>   3 files changed, 535 insertions(+), 2 deletions(-)
>   create mode 100644 hw/ccid-card-emulated.c
>
> diff --git a/Makefile.objs b/Makefile.objs
> index 6a0030b..303b642 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -197,7 +197,7 @@ hw-obj-$(CONFIG_FDC) += fdc.o
>   hw-obj-$(CONFIG_ACPI) += acpi.o acpi_piix4.o
>   hw-obj-$(CONFIG_APM) += pm_smbus.o apm.o
>   hw-obj-$(CONFIG_DMA) += dma.o
> -hw-obj-$(CONFIG_SMARTCARD) += usb-ccid.o ccid-card-passthru.o
> +hw-obj-$(CONFIG_SMARTCARD) += usb-ccid.o ccid-card-passthru.o ccid-card-emulated.o
>
>   # PPC devices
>   hw-obj-$(CONFIG_OPENPIC) += openpic.o
> diff --git a/hw/ccid-card-emulated.c b/hw/ccid-card-emulated.c
> new file mode 100644
> index 0000000..5531ce1
> --- /dev/null
> +++ b/hw/ccid-card-emulated.c
> @@ -0,0 +1,534 @@
> +/*
> + * CCID Card Device. Emulated card.
> + *
> + * It can be used to provide access to the local hardware in a non exclusive
> + * way, or it can use certificates. It requires the usb-ccid bus.
> + *
> + * Usage 1: standard, mirror hardware reader+card:
> + * qemu .. -usb -device usb-ccid -device ccid-card-emulated
> + *
> + * Usage 2: use certificates, no hardware required
> + * one time: create the certificates:
> + *  for i in 1 2 3; do certutil -d /etc/pki/nssdb -x -t "CT,CT,CT" -S -s "CN=user$i" -n user$i; done
> + * qemu .. -usb -device usb-ccid -device ccid-card-emulated,cert1=user1,cert2=user2,cert3=user3
> + *
> + * If you use a non default db for the certificates you can specify it using the db parameter.
> + *
> + *
> + * Copyright (c) 2010 Red Hat.
> + * Written by Alon Levy.
> + *
> + * This code is licenced under the LGPL.
> + */
> +
> +#include<pthread.h>
> +#include<eventt.h>
> +#include<vevent.h>
> +#include<vreader.h>
> +#include<vcard_emul.h>
> +#include "qemu-char.h"
> +#include "monitor.h"
> +#include "hw/ccid.h"
> +
> +#define DPRINTF(card, lvl, fmt, ...) \
> +do { if (lvl<= card->debug) { printf("ccid-card-emul: %s: " fmt , __func__, ## __VA_ARGS__); } } while (0)
> +
> +#define EMULATED_DEV_NAME "ccid-card-emulated"
> +
> +#define BACKEND_NSS_EMULATED "nss-emulated" /* the default */
> +#define BACKEND_CERTIFICATES "certificates"
> +
> +typedef struct EmulatedState EmulatedState;
> +
> +enum {
> +    EMUL_READER_INSERT = 0,
> +    EMUL_READER_REMOVE,
> +    EMUL_CARD_INSERT,
> +    EMUL_CARD_REMOVE,
> +    EMUL_GUEST_APDU,
> +    EMUL_RESPONSE_APDU,
> +    EMUL_ERROR,
> +};
> +
> +static const char* emul_event_to_string(uint32_t emul_event)
> +{
> +    switch (emul_event) {
> +        case EMUL_READER_INSERT: return "EMUL_READER_INSERT";
> +        case EMUL_READER_REMOVE: return "EMUL_READER_REMOVE";
> +        case EMUL_CARD_INSERT: return "EMUL_CARD_INSERT";
> +        case EMUL_CARD_REMOVE: return "EMUL_CARD_REMOVE";
> +        case EMUL_GUEST_APDU: return "EMUL_GUEST_APDU";
> +        case EMUL_RESPONSE_APDU: return "EMUL_RESPONSE_APDU";
> +        case EMUL_ERROR: return "EMUL_ERROR";
> +        default:
> +            break;
> +    }
> +    return "UNKNOWN";
> +}
> +
> +typedef struct EmulEvent {
> +    QSIMPLEQ_ENTRY(EmulEvent) entry;
> +    union {
> +        struct {
> +            uint32_t type;
> +        } gen;
> +        struct {
> +            uint32_t type;
> +            uint64_t code;
> +        } error;
> +        struct {
> +            uint32_t type;
> +            uint32_t len;
> +            uint8_t data[];
> +        } data;
> +    } p;
> +} EmulEvent;
> +
> +#define MAX_ATR_SIZE 40
> +struct EmulatedState {
> +    CCIDCardState base;
> +    uint8_t  debug;
> +    char*    backend;
> +    char*    cert1;
> +    char*    cert2;
> +    char*    cert3;
> +    char*    db;
> +    uint8_t  atr[MAX_ATR_SIZE];
> +    uint8_t  atr_length;
> +    QSIMPLEQ_HEAD(event_list, EmulEvent) event_list;
> +    pthread_mutex_t event_list_mutex;
> +    VReader *reader;
> +    QSIMPLEQ_HEAD(guest_apdu_list, EmulEvent) guest_apdu_list;
> +    pthread_mutex_t vreader_mutex; /* and guest_apdu_list mutex */
> +    pthread_mutex_t handle_apdu_mutex;
> +    pthread_cond_t handle_apdu_cond;
> +    int      pipe[2];
> +    int      quit_apdu_thread;
> +    pthread_mutex_t apdu_thread_quit_mutex;
> +    pthread_cond_t apdu_thread_quit_cond;
> +};
> +
> +static void emulated_apdu_from_guest(CCIDCardState *base, const uint8_t *apdu, uint32_t len)
> +{
> +    EmulatedState *card = DO_UPCAST(EmulatedState, base, base);
> +    EmulEvent *event = (EmulEvent*)malloc(sizeof(EmulEvent) + len);
> +
> +    assert(event);
> +    event->p.data.type = EMUL_GUEST_APDU;
> +    event->p.data.len = len;
> +    memcpy(event->p.data.data, apdu, len);
> +    pthread_mutex_lock(&card->vreader_mutex);
> +    QSIMPLEQ_INSERT_TAIL(&card->guest_apdu_list, event, entry);
> +    pthread_mutex_unlock(&card->vreader_mutex);
> +    pthread_mutex_lock(&card->handle_apdu_mutex);
> +    pthread_cond_signal(&card->handle_apdu_cond);
> +    pthread_mutex_unlock(&card->handle_apdu_mutex);
> +}
> +
> +static const uint8_t* emulated_get_atr(CCIDCardState *base, uint32_t *len)
> +{
> +    EmulatedState *card = DO_UPCAST(EmulatedState, base, base);
> +
> +    *len = card->atr_length;
> +    return card->atr;
> +}
> +
> +static void emulated_push_event(EmulatedState *card, EmulEvent *event)
> +{
> +    pthread_mutex_lock(&card->event_list_mutex);
> +    QSIMPLEQ_INSERT_TAIL(&(card->event_list), event, entry);
> +    pthread_mutex_unlock(&card->event_list_mutex);
> +    if (write(card->pipe[1], card, 1) != 1) {
> +        DPRINTF(card, 1, "write to pipe failed\n");
> +    }
> +}
> +
> +static void emulated_push_type(EmulatedState *card, uint32_t type)
> +{
> +    EmulEvent *event = (EmulEvent*)malloc(sizeof(EmulEvent));
> +
> +    assert(event);
> +    event->p.gen.type = type;
> +    emulated_push_event(card, event);
> +}
> +
> +static void emulated_push_error(EmulatedState *card, uint64_t code)
> +{
> +    EmulEvent *event = (EmulEvent*)malloc(sizeof(EmulEvent));
> +
> +    assert(event);
> +    event->p.error.type = EMUL_ERROR;
> +    event->p.error.code = code;
> +    emulated_push_event(card, event);
> +}
> +
> +static void emulated_push_data_type(EmulatedState *card, uint32_t type,
> +    const uint8_t *data, uint32_t len)
> +{
> +    EmulEvent *event = (EmulEvent*)malloc(sizeof(EmulEvent) + len);
> +
> +    assert(event);
> +    event->p.data.type = type;
> +    event->p.data.len = len;
> +    memcpy(event->p.data.data, data, len);
> +    emulated_push_event(card, event);
> +}
> +
> +static void emulated_push_reader_insert(EmulatedState *card)
> +{
> +    emulated_push_type(card, EMUL_READER_INSERT);
> +}
> +
> +static void emulated_push_reader_remove(EmulatedState *card)
> +{
> +    emulated_push_type(card, EMUL_READER_REMOVE);
> +}
> +
> +static void emulated_push_card_insert(EmulatedState *card,
> +    const uint8_t *atr, uint32_t len)
> +{
> +    emulated_push_data_type(card, EMUL_CARD_INSERT, atr, len);
> +}
> +
> +static void emulated_push_card_remove(EmulatedState *card)
> +{
> +    emulated_push_type(card, EMUL_CARD_REMOVE);
> +}
> +
> +static void emulated_push_response_apdu(EmulatedState *card,
> +    const uint8_t* apdu, uint32_t len)
> +{
> +    emulated_push_data_type(card, EMUL_RESPONSE_APDU, apdu, len);
> +}
> +
> +#define APDU_BUF_SIZE 270
> +static void *handle_apdu_thread(void* arg)
> +{
> +    EmulatedState *card = arg;
> +    uint8_t recv_data[APDU_BUF_SIZE];
> +    int recv_len;
> +    VReaderStatus reader_status;
> +    EmulEvent *event;
> +
> +    while (1) {
> +        pthread_mutex_lock(&card->handle_apdu_mutex);
> +        pthread_cond_wait(&card->handle_apdu_cond,&card->handle_apdu_mutex);
> +        pthread_mutex_unlock(&card->handle_apdu_mutex);
> +        if (card->quit_apdu_thread) {
> +            card->quit_apdu_thread = 0; // debugging
> +            break;
> +        }
> +        pthread_mutex_lock(&card->vreader_mutex);
> +        while (!QSIMPLEQ_EMPTY(&card->guest_apdu_list)) {
> +            event = QSIMPLEQ_FIRST(&card->guest_apdu_list);
> +            assert((unsigned long)event>  1000);
> +            QSIMPLEQ_REMOVE_HEAD(&card->guest_apdu_list, entry);
> +            if (event->p.data.type != EMUL_GUEST_APDU) {
> +                DPRINTF(card, 1, "unexpected message in handle_apdu_thread\n");
> +                free(event);
> +                continue;
> +            }
> +            if (card->reader == NULL) {
> +                DPRINTF(card, 1, "reader is NULL\n");
> +                free(event);
> +                continue;
> +            }
> +            recv_len = sizeof(recv_data);
> +            reader_status = vreader_xfr_bytes(card->reader,
> +                    event->p.data.data, event->p.data.len,
> +                    recv_data,&recv_len);
> +            DPRINTF(card, 2, "got back apdu of length %d\n", recv_len);
> +            if (reader_status == VREADER_OK) {
> +                emulated_push_response_apdu(card, recv_data, recv_len);
> +            } else {
> +                emulated_push_error(card, reader_status);
> +            }
> +            free(event);
> +        }
> +        pthread_mutex_unlock(&card->vreader_mutex);
> +    }
> +    pthread_mutex_lock(&card->apdu_thread_quit_mutex);
> +    pthread_cond_signal(&card->apdu_thread_quit_cond);
> +    pthread_mutex_unlock(&card->apdu_thread_quit_mutex);
> +    return NULL;
> +}
> +
> +static void *event_thread(void *arg)
> +{
> +    int atr_len = MAX_ATR_SIZE;
> +    uint8_t atr[MAX_ATR_SIZE];
> +    VEvent *event = NULL;
> +    EmulatedState *card = arg;
> +
> +    while (1) {
> +        const char *reader_name;
> +
> +        event = vevent_wait_next_vevent();
> +        if (event == NULL || event->type == VEVENT_LAST) {
> +            break;
> +        }
> +        if (event->type != VEVENT_READER_INSERT) {
> +            if (card->reader == NULL&&  event->reader != NULL) {
> +                // Happens after device_add followed by card remove or insert.
> +                // XXX: create synthetic add_reader events if vcard_emul_init
> +                // already called, which happens if device_del and device_add are
> +                // called
> +                card->reader = vreader_reference(event->reader);
> +            } else {
> +                if (event->reader != card->reader) {
> +                    fprintf(stderr, "ERROR: wrong reader: quiting event_thread\n");
> +                    break;
> +                }
> +            }
> +        }
> +        switch (event->type) {
> +        case VEVENT_READER_INSERT:
> +            /* TODO: take a specific reader. i.e. track which reader
> +             * we are seeing here, check it is the one we want (the first,
> +             * or by a particular name), and ignore if we don't want it.
> +             */
> +            reader_name = vreader_get_name(event->reader);
> +            if (card->reader != NULL) {
> +                DPRINTF(card, 2, "READER INSERT - replacing %s with %s\n",
> +                    vreader_get_name(card->reader), reader_name);
> +                pthread_mutex_lock(&card->vreader_mutex);
> +                vreader_free(card->reader);
> +                pthread_mutex_unlock(&card->vreader_mutex);
> +                emulated_push_reader_remove(card);
> +            }
> +            pthread_mutex_lock(&card->vreader_mutex);
> +            DPRINTF(card, 2, "READER INSERT %s\n", reader_name);
> +            card->reader = vreader_reference(event->reader);
> +            pthread_mutex_unlock(&card->vreader_mutex);
> +            emulated_push_reader_insert(card);
> +            break;
> +        case VEVENT_READER_REMOVE:
> +            DPRINTF(card, 2, " READER REMOVE: %s \n",
> +                    vreader_get_name(event->reader));
> +            pthread_mutex_lock(&card->vreader_mutex);
> +            vreader_free(card->reader);
> +            card->reader = NULL;
> +            pthread_mutex_unlock(&card->vreader_mutex);
> +            emulated_push_reader_remove(card);
> +            break;
> +        case VEVENT_CARD_INSERT:
> +            /* get the ATR (intended as a response to a power on from the
> +             * reader */
> +            atr_len = MAX_ATR_SIZE;
> +            vreader_power_on(event->reader, atr,&atr_len);
> +            card->atr_length = (uint8_t)atr_len;
> +            DPRINTF(card, 2, " CARD INSERT\n");
> +            emulated_push_card_insert(card, atr, atr_len);
> +            break;
> +        case VEVENT_CARD_REMOVE:
> +            DPRINTF(card, 2, " CARD REMOVE\n");
> +            emulated_push_card_remove(card);
> +            break;
> +        case VEVENT_LAST: /* quit */
> +            vevent_delete(event);
> +            return NULL;
> +            break;
> +        default:
> +            break;
> +        }
> +        vevent_delete(event);
> +    }
> +    return NULL;
> +}
> +
> +static void pipe_read(void *opaque)
> +{
> +    EmulatedState *card = opaque;
> +    EmulEvent *event, *next;
> +    char dummy;
> +    int len;
> +
> +    do {
> +        len = read(card->pipe[0],&dummy, sizeof(dummy));
> +    } while (len == sizeof(dummy));
> +    pthread_mutex_lock(&card->event_list_mutex);
> +    QSIMPLEQ_FOREACH_SAFE(event,&card->event_list, entry, next) {
> +        DPRINTF(card, 2, "event %s\n", emul_event_to_string(event->p.gen.type));
> +        switch (event->p.gen.type) {
> +            case EMUL_RESPONSE_APDU:
> +                ccid_card_send_apdu_to_guest(&card->base, event->p.data.data,
> +                    event->p.data.len);
> +                break;
> +            case EMUL_READER_INSERT:
> +                ccid_card_ccid_attach(&card->base);
> +                break;
> +            case EMUL_READER_REMOVE:
> +                ccid_card_ccid_detach(&card->base);
> +                break;
> +            case EMUL_CARD_INSERT:
> +                assert(event->p.data.len<= MAX_ATR_SIZE);
> +                card->atr_length = event->p.data.len;
> +                memcpy(card->atr, event->p.data.data, card->atr_length);
> +                ccid_card_card_inserted(&card->base);
> +                break;
> +            case EMUL_CARD_REMOVE:
> +                ccid_card_card_removed(&card->base);
> +                break;
> +            case EMUL_ERROR:
> +                ccid_card_card_error(&card->base, event->p.error.code);
> +                break;
> +            default:
> +                DPRINTF(card, 2, "unexpected event\n");
> +                break;
> +        }
> +        free(event);
> +    }
> +    QSIMPLEQ_INIT(&card->event_list);
> +    pthread_mutex_unlock(&card->event_list_mutex);
> +}
> +
> +static int init_pipe_signaling(EmulatedState *card)
> +{
> +   if (pipe(card->pipe)<  0) {
> +       DPRINTF(card, 2, "pipe creation failed\n");
> +       return -1;
> +   }
> +   fcntl(card->pipe[0], F_SETFL, O_NONBLOCK);
> +   fcntl(card->pipe[1], F_SETFL, O_NONBLOCK);
> +   fcntl(card->pipe[0], F_SETOWN, getpid());
> +   qemu_set_fd_handler(card->pipe[0], pipe_read, NULL, card);
> +   return 0;
> +}
> +
> +#define CERTIFICATES_DEFAULT_DB "/etc/pki/nssdb"
> +#define CERTIFICATES_ARGS_TEMPLATE "db=\"%s\" use_hw=no soft=(,Virtual Reader,CAC,,%s,%s,%s)"
> +
> +static int wrap_vcard_emul_init(VCardEmulOptions *options)
> +{
> +    static int called = 0;
> +    static int options_was_null = 0;
> +
> +    if (called) {
> +        if ((options == NULL) != options_was_null) {
> +            printf("%s: warning: running emulated with certificates and emulated side by side is not supported\n", __FUNCTION__);
> +            return VCARD_EMUL_FAIL;
> +        }
> +        vcard_emul_replay_insertion_events();
> +        return VCARD_EMUL_OK;
> +    }
> +    options_was_null = (options == NULL);
> +    called = 1;
> +    return vcard_emul_init(options);
> +}
> +
> +static int emulated_initialize_vcard_from_certificates(EmulatedState *card)
> +{
> +    char emul_args[200];
> +    VCardEmulOptions *options = NULL;
> +
> +    snprintf(emul_args, sizeof(emul_args) - 1, CERTIFICATES_ARGS_TEMPLATE,
> +        card->db ? card->db : CERTIFICATES_DEFAULT_DB,
> +        card->cert1, card->cert2, card->cert3);
> +    options = vcard_emul_options(emul_args);
> +    if (options == NULL) {
> +        printf("%s: warning: not using certificates due to initialization error\n", __func__);
> +    }
> +    return wrap_vcard_emul_init(options);
> +}
> +
> +static int emulated_initfn(CCIDCardState *base)
> +{
> +    EmulatedState *card = DO_UPCAST(EmulatedState, base, base);
> +    int rv;
> +    pthread_t thread_id;
> +    VCardEmulError ret;
> +
> +    QSIMPLEQ_INIT(&card->event_list);
> +    QSIMPLEQ_INIT(&card->guest_apdu_list);
> +    pthread_mutex_init(&card->event_list_mutex, NULL);
> +    pthread_mutex_init(&card->vreader_mutex, NULL);
> +    pthread_mutex_init(&card->handle_apdu_mutex, NULL);
> +    pthread_cond_init(&card->handle_apdu_cond, NULL);
> +    card->reader = NULL;
> +    card->quit_apdu_thread = 0;
> +    if (init_pipe_signaling(card)<  0) {
> +        return -1;
> +    }
> +    if (!card->backend) {
> +        card->backend = strdup((char*)BACKEND_NSS_EMULATED);
> +    }
> +    /* TODO: a passthru backened that works on local machine. third card type? */
> +    if (strcmp(BACKEND_CERTIFICATES, card->backend) == 0
> +&&  card->cert1 != NULL&&  card->cert2 != NULL&&  card->cert3 != NULL) {
> +        ret = emulated_initialize_vcard_from_certificates(card);
> +    } else {
> +        if (strcmp(BACKEND_CERTIFICATES, card->backend) == 0) {
> +            printf("%s: you must provide all three certs for certificates backend\n",
> +                EMULATED_DEV_NAME);
> +            return -1;
> +        }
> +        if (card->backend&&  strcmp(BACKEND_NSS_EMULATED, card->backend) != 0) {
> +            printf("%s: bad backend specified. The options are:\n%s (default), %s.\n",
> +                EMULATED_DEV_NAME, BACKEND_NSS_EMULATED, BACKEND_CERTIFICATES);
> +            return -1;
> +        }
> +        /* default to mirroring the local hardware readers */
> +        ret = wrap_vcard_emul_init(NULL);
> +    }
> +    if (ret != VCARD_EMUL_OK) {
> +        printf("%s: failed to initialize vcard\n", EMULATED_DEV_NAME);
> +        return -1;
> +    }
> +    rv = pthread_create(&thread_id, NULL, event_thread, card);
> +    if (rv<  0) {
> +        printf("%s: error creating event thread\n", EMULATED_DEV_NAME);
> +        return -1;
> +    }
>    

Why can't this be implemented with qemu_set_fd_handler?  The event 
thread si just spinning on read.

Regards,

Anthony Liguori

> +    rv = pthread_create(&thread_id, NULL, handle_apdu_thread, card);
> +    if (rv<  0) {
> +        printf("%s: error creating handle_apdu thread\n", EMULATED_DEV_NAME);
> +        return -1;
> +    }
> +    return 0;
> +}
> +
> +static int emulated_exitfn(CCIDCardState *base)
> +{
> +    EmulatedState *card = DO_UPCAST(EmulatedState, base, base);
> +    VEvent *vevent = vevent_new(VEVENT_LAST, NULL, NULL);
> +
> +    vevent_queue_vevent(vevent); /* stop vevent thread */
> +    pthread_mutex_lock(&card->apdu_thread_quit_mutex);
> +    card->quit_apdu_thread = 1; /* stop handle_apdu thread */
> +    pthread_cond_signal(&card->handle_apdu_cond);
> +    pthread_cond_wait(&card->apdu_thread_quit_cond,&card->apdu_thread_quit_mutex);
> +    /* handle_apdu thread stopped, can destroy all of it's mutexes */
> +    pthread_cond_destroy(&card->handle_apdu_cond);
> +    pthread_cond_destroy(&card->apdu_thread_quit_cond);
> +    pthread_mutex_destroy(&card->apdu_thread_quit_mutex);
> +    pthread_mutex_destroy(&card->handle_apdu_mutex);
> +    pthread_mutex_destroy(&card->vreader_mutex);
> +    pthread_mutex_destroy(&card->event_list_mutex);
> +    return 0;
> +}
> +
> +static CCIDCardInfo emulated_card_info = {
> +    .qdev.name = EMULATED_DEV_NAME,
> +    .qdev.size = sizeof(EmulatedState),
> +    .initfn = emulated_initfn,
> +    .exitfn = emulated_exitfn,
> +    .get_atr = emulated_get_atr,
> +    .apdu_from_guest = emulated_apdu_from_guest,
> +    .qdev.unplug    = qdev_simple_unplug_cb,
> +    .qdev.props     = (Property[]) {
> +        DEFINE_PROP_STRING("backend", EmulatedState, backend),
> +        DEFINE_PROP_STRING("cert1", EmulatedState, cert1),
> +        DEFINE_PROP_STRING("cert2", EmulatedState, cert2),
> +        DEFINE_PROP_STRING("cert3", EmulatedState, cert3),
> +        DEFINE_PROP_STRING("db", EmulatedState, db),
> +        DEFINE_PROP_UINT8("debug", EmulatedState, debug, 0),
> +        DEFINE_PROP_END_OF_LIST(),
> +    },
> +};
> +
> +static void ccid_card_emulated_register_devices(void)
> +{
> +    ccid_card_qdev_register(&emulated_card_info);
> +}
> +
> +device_init(ccid_card_emulated_register_devices)
> diff --git a/hw/ccid-card-passthru.c b/hw/ccid-card-passthru.c
> index 6ec4f21..f9fb82c 100644
> --- a/hw/ccid-card-passthru.c
> +++ b/hw/ccid-card-passthru.c
> @@ -253,7 +253,6 @@ static CCIDCardInfo passthru_card_info = {
>       .exitfn = passthru_exitfn,
>       .get_atr = passthru_get_atr,
>       .apdu_from_guest = passthru_apdu_from_guest,
> -    .qdev.unplug    = qdev_simple_unplug_cb,
>       .qdev.props     = (Property[]) {
>           DEFINE_PROP_CHR("chardev", PassthruState, cs),
>           DEFINE_PROP_UINT8("debug", PassthruState, debug, 0),
>