u2f.c

/*
 * U2F USB device.
 *
 * Copyright (c) 2020 César Belley <cesar.belley@lse.epita.fr>
 * Written by César Belley <cesar.belley@lse.epita.fr>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu/osdep.h"
#include "qemu/module.h"
#include "qapi/error.h"
#include "hw/usb.h"
#include "hw/usb/hid.h"
#include "migration/vmstate.h"
#include "desc.h"

#include "u2f.h"

/* U2F key Vendor / Product */
#define U2F_KEY_VENDOR_NUM     0x46f4 /* CRC16() of "QEMU" */
#define U2F_KEY_PRODUCT_NUM    0x0005

enum {
    STR_MANUFACTURER = 1,
    STR_PRODUCT,
    STR_SERIALNUMBER,
    STR_CONFIG,
    STR_INTERFACE
};

static const USBDescStrings desc_strings = {
    [STR_MANUFACTURER]     = "QEMU",
    [STR_PRODUCT]          = "U2F USB key",
    [STR_SERIALNUMBER]     = "0",
    [STR_CONFIG]           = "U2F key config",
    [STR_INTERFACE]        = "U2F key interface"
};

static const USBDescIface desc_iface_u2f_key = {
    .bInterfaceNumber              = 0,
    .bNumEndpoints                 = 2,
    .bInterfaceClass               = USB_CLASS_HID,
    .bInterfaceSubClass            = 0x0,
    .bInterfaceProtocol            = 0x0,
    .ndesc                         = 1,
    .descs = (USBDescOther[]) {
        {
            /* HID descriptor */
            .data = (uint8_t[]) {
                0x09,          /*  u8  bLength */
                USB_DT_HID,    /*  u8  bDescriptorType */
                0x10, 0x01,    /*  u16 HID_class */
                0x00,          /*  u8  country_code */
                0x01,          /*  u8  num_descriptors */
                USB_DT_REPORT, /*  u8  type: Report */
                0x22, 0,       /*  u16 len */
            },
        },
    },
    .eps = (USBDescEndpoint[]) {
        {
            .bEndpointAddress      = USB_DIR_IN | 0x01,
            .bmAttributes          = USB_ENDPOINT_XFER_INT,
            .wMaxPacketSize        = U2FHID_PACKET_SIZE,
            .bInterval             = 0x05,
        }, {
            .bEndpointAddress      = USB_DIR_OUT | 0x01,
            .bmAttributes          = USB_ENDPOINT_XFER_INT,
            .wMaxPacketSize        = U2FHID_PACKET_SIZE,
            .bInterval             = 0x05,
        },
    },

};

static const USBDescDevice desc_device_u2f_key = {
    .bcdUSB                        = 0x0100,
    .bMaxPacketSize0               = U2FHID_PACKET_SIZE,
    .bNumConfigurations            = 1,
    .confs = (USBDescConfig[]) {
        {
            .bNumInterfaces        = 1,
            .bConfigurationValue   = 1,
            .iConfiguration        = STR_CONFIG,
            .bmAttributes          = USB_CFG_ATT_ONE,
            .bMaxPower             = 15,
            .nif = 1,
            .ifs = &desc_iface_u2f_key,
        },
    },
};

static const USBDesc desc_u2f_key = {
    .id = {
        .idVendor          = U2F_KEY_VENDOR_NUM,
        .idProduct         = U2F_KEY_PRODUCT_NUM,
        .bcdDevice         = 0,
        .iManufacturer     = STR_MANUFACTURER,
        .iProduct          = STR_PRODUCT,
        .iSerialNumber     = STR_SERIALNUMBER,
    },
    .full = &desc_device_u2f_key,
    .str  = desc_strings,
};

static const uint8_t u2f_key_hid_report_desc[] = {
    0x06, 0xd0, 0xf1, /* Usage Page (FIDO) */
    0x09, 0x01,       /* Usage (FIDO) */
    0xa1, 0x01,       /* Collection (HID Application) */
    0x09, 0x20,       /*    Usage (FIDO data in) */
    0x15, 0x00,       /*        Logical Minimum (0) */
    0x26, 0xFF, 0x00, /*        Logical Maximum (0xff) */
    0x75, 0x08,       /*        Report Size (8) */
    0x95, 0x40,       /*        Report Count (0x40) */
    0x81, 0x02,       /*        Input (Data, Variable, Absolute) */
    0x09, 0x21,       /*    Usage (FIDO data out) */
    0x15, 0x00,       /*        Logical Minimum (0) */
    0x26, 0xFF, 0x00, /*        Logical Maximum  (0xFF) */
    0x75, 0x08,       /*        Report Size (8) */
    0x95, 0x40,       /*        Report Count (0x40) */
    0x91, 0x02,       /*        Output (Data, Variable, Absolute) */
    0xC0              /* End Collection */
};

static void u2f_key_reset(U2FKeyState *key)
{
    key->pending_in_start = 0;
    key->pending_in_end = 0;
    key->pending_in_num = 0;
}

static void u2f_key_handle_reset(USBDevice *dev)
{
    U2FKeyState *key = U2F_KEY(dev);

    u2f_key_reset(key);
}

static void u2f_key_handle_control(USBDevice *dev, USBPacket *p,
               int request, int value, int index, int length, uint8_t *data)
{
    U2FKeyState *key = U2F_KEY(dev);
    int ret;

    ret = usb_desc_handle_control(dev, p, request, value, index, length, data);
    if (ret >= 0) {
        return;
    }

    switch (request) {
    case InterfaceRequest | USB_REQ_GET_DESCRIPTOR:
        switch (value >> 8) {
        case 0x22:
            memcpy(data, u2f_key_hid_report_desc,
                   sizeof(u2f_key_hid_report_desc));
            p->actual_length = sizeof(u2f_key_hid_report_desc);
            break;
        default:
            goto fail;
        }
        break;
    case HID_GET_IDLE:
        data[0] = key->idle;
        p->actual_length = 1;
        break;
    case HID_SET_IDLE:
        key->idle = (uint8_t)(value >> 8);
        break;
    default:
    fail:
        p->status = USB_RET_STALL;
        break;
    }

}

static void u2f_key_recv_from_guest(U2FKeyState *key, USBPacket *p)
{
    U2FKeyClass *kc = U2F_KEY_GET_CLASS(key);
    uint8_t packet[U2FHID_PACKET_SIZE];

    if (kc->recv_from_guest == NULL || p->iov.size != U2FHID_PACKET_SIZE) {
        return;
    }

    usb_packet_copy(p, packet, p->iov.size);
    kc->recv_from_guest(key, packet);
}

static void u2f_pending_in_add(U2FKeyState *key,
                               const uint8_t packet[U2FHID_PACKET_SIZE])
{
    uint8_t index;

    if (key->pending_in_num >= U2FHID_PENDING_IN_NUM) {
        return;
    }

    index = key->pending_in_end;
    key->pending_in_end = (index + 1) % U2FHID_PENDING_IN_NUM;
    ++key->pending_in_num;

    memcpy(key->pending_in[index], packet, U2FHID_PACKET_SIZE);
}

static uint8_t *u2f_pending_in_get(U2FKeyState *key)
{
    uint8_t index;

    if (key->pending_in_num == 0) {
        return NULL;
    }

    index = key->pending_in_start;
    key->pending_in_start = (index + 1) % U2FHID_PENDING_IN_NUM;
    --key->pending_in_num;

    return key->pending_in[index];
}

static void u2f_key_handle_data(USBDevice *dev, USBPacket *p)
{
    U2FKeyState *key = U2F_KEY(dev);
    uint8_t *packet_in;

    /* Endpoint number check */
    if (p->ep->nr != 1) {
        p->status = USB_RET_STALL;
        return;
    }

    switch (p->pid) {
    case USB_TOKEN_OUT:
        u2f_key_recv_from_guest(key, p);
        break;
    case USB_TOKEN_IN:
        packet_in = u2f_pending_in_get(key);
        if (packet_in == NULL) {
            p->status = USB_RET_NAK;
            return;
        }
        usb_packet_copy(p, packet_in, U2FHID_PACKET_SIZE);
        break;
    default:
        p->status = USB_RET_STALL;
        break;
    }
}

void u2f_send_to_guest(U2FKeyState *key,
                       const uint8_t packet[U2FHID_PACKET_SIZE])
{
    u2f_pending_in_add(key, packet);
    usb_wakeup(key->ep, 0);
}

static void u2f_key_unrealize(USBDevice *dev)
{
    U2FKeyState *key = U2F_KEY(dev);
    U2FKeyClass *kc = U2F_KEY_GET_CLASS(key);

    if (kc->unrealize != NULL) {
        kc->unrealize(key);
    }
}

static void u2f_key_realize(USBDevice *dev, Error **errp)
{
    U2FKeyState *key = U2F_KEY(dev);
    U2FKeyClass *kc = U2F_KEY_GET_CLASS(key);
    Error *local_err = NULL;

    usb_desc_create_serial(dev);
    usb_desc_init(dev);
    u2f_key_reset(key);

    if (kc->realize != NULL) {
        kc->realize(key, &local_err);
        if (local_err != NULL) {
            error_propagate(errp, local_err);
            return;
        }
    }
    key->ep = usb_ep_get(dev, USB_TOKEN_IN, 1);
}

const VMStateDescription vmstate_u2f_key = {
    .name = "u2f-key",
    .version_id = 1,
    .minimum_version_id = 1,
    .fields = (VMStateField[]) {
        VMSTATE_USB_DEVICE(dev, U2FKeyState),
        VMSTATE_UINT8(idle, U2FKeyState),
        VMSTATE_UINT8_2DARRAY(pending_in, U2FKeyState,
            U2FHID_PENDING_IN_NUM, U2FHID_PACKET_SIZE),
        VMSTATE_UINT8(pending_in_start, U2FKeyState),
        VMSTATE_UINT8(pending_in_end, U2FKeyState),
        VMSTATE_UINT8(pending_in_num, U2FKeyState),
        VMSTATE_END_OF_LIST()
    }
};

static void u2f_key_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    USBDeviceClass *uc = USB_DEVICE_CLASS(klass);

    uc->product_desc   = "QEMU U2F USB key";
    uc->usb_desc       = &desc_u2f_key;
    uc->handle_reset   = u2f_key_handle_reset;
    uc->handle_control = u2f_key_handle_control;
    uc->handle_data    = u2f_key_handle_data;
    uc->handle_attach  = usb_desc_attach;
    uc->realize        = u2f_key_realize;
    uc->unrealize      = u2f_key_unrealize;
    dc->desc           = "QEMU U2F key";
    dc->vmsd           = &vmstate_u2f_key;
}

static const TypeInfo u2f_key_info = {
    .name          = TYPE_U2F_KEY,
    .parent        = TYPE_USB_DEVICE,
    .instance_size = sizeof(U2FKeyState),
    .abstract      = true,
    .class_size    = sizeof(U2FKeyClass),
    .class_init    = u2f_key_class_init,
};

static void u2f_key_register_types(void)
{
    type_register_static(&u2f_key_info);
}

type_init(u2f_key_register_types)