// SPDX-License-Identifier: GPL-2.0
/*
* U2F Zero LED and RNG driver
*
* Copyright 2018 Andrej Shadura <[email protected]>
* Loosely based on drivers/hid/hid-led.c
* and drivers/usb/misc/chaoskey.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2.
*/
#include <linux/hid.h>
#include <linux/hidraw.h>
#include <linux/hw_random.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/usb.h>
#include "usbhid/usbhid.h"
#include "hid-ids.h"
#define DRIVER_SHORT "u2fzero"
#define HID_REPORT_SIZE 64
enum hw_revision {
HW_U2FZERO,
HW_NITROKEY_U2F,
};
struct hw_revision_config {
u8 rng_cmd;
u8 wink_cmd;
const char *name;
};
static const struct hw_revision_config hw_configs[] = {
[HW_U2FZERO] = {
.rng_cmd = 0x21,
.wink_cmd = 0x24,
.name = "U2F Zero",
},
[HW_NITROKEY_U2F] = {
.rng_cmd = 0xc0,
.wink_cmd = 0xc2,
.name = "NitroKey U2F",
},
};
/* We only use broadcast (CID-less) messages */
#define CID_BROADCAST 0xffffffff
struct u2f_hid_msg {
u32 cid;
union {
struct {
u8 cmd;
u8 bcnth;
u8 bcntl;
u8 data[HID_REPORT_SIZE - 7];
} init;
struct {
u8 seq;
u8 data[HID_REPORT_SIZE - 5];
} cont;
};
} __packed;
struct u2f_hid_report {
u8 report_type;
struct u2f_hid_msg msg;
} __packed;
#define U2F_HID_MSG_LEN(f) (size_t)(((f).init.bcnth << 8) + (f).init.bcntl)
struct u2fzero_device {
struct hid_device *hdev;
struct urb *urb; /* URB for the RNG data */
struct led_classdev ldev; /* Embedded struct for led */
struct hwrng hwrng; /* Embedded struct for hwrng */
char *led_name;
char *rng_name;
u8 *buf_out;
u8 *buf_in;
struct mutex lock;
bool present;
kernel_ulong_t hw_revision;
};
static int u2fzero_send(struct u2fzero_device *dev, struct u2f_hid_report *req)
{
int ret;
mutex_lock(&dev->lock);
memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
ret = hid_hw_output_report(dev->hdev, dev->buf_out,
sizeof(struct u2f_hid_msg));
mutex_unlock(&dev->lock);
if (ret < 0)
return ret;
return ret == sizeof(struct u2f_hid_msg) ? 0 : -EMSGSIZE;
}
struct u2fzero_transfer_context {
struct completion done;
int status;
};
static void u2fzero_read_callback(struct urb *urb)
{
struct u2fzero_transfer_context *ctx = urb->context;
ctx->status = urb->status;
complete(&ctx->done);
}
static int u2fzero_recv(struct u2fzero_device *dev,
struct u2f_hid_report *req,
struct u2f_hid_msg *resp)
{
int ret;
struct hid_device *hdev = dev->hdev;
struct u2fzero_transfer_context ctx;
mutex_lock(&dev->lock);
memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
dev->urb->context = &ctx;
init_completion(&ctx.done);
ret = usb_submit_urb(dev->urb, GFP_NOIO);
if (unlikely(ret)) {
hid_err(hdev, "usb_submit_urb failed: %d", ret);
goto err;
}
ret = hid_hw_output_report(dev->hdev, dev->buf_out,
sizeof(struct u2f_hid_msg));
if (ret < 0) {
hid_err(hdev, "hid_hw_output_report failed: %d", ret);
goto err;
}
ret = (wait_for_completion_timeout(
&ctx.done, msecs_to_jiffies(USB_CTRL_SET_TIMEOUT)));
if (ret == 0) {
usb_kill_urb(dev->urb);
hid_err(hdev, "urb submission timed out");
} else {
ret = dev->urb->actual_length;
memcpy(resp, dev->buf_in, ret);
}
err:
mutex_unlock(&dev->lock);
return ret;
}
static int u2fzero_blink(struct led_classdev *ldev)
{
struct u2fzero_device *dev = container_of(ldev,
struct u2fzero_device, ldev);
struct u2f_hid_report req = {
.report_type = 0,
.msg.cid = CID_BROADCAST,
.msg.init = {
.cmd = hw_configs[dev->hw_revision].wink_cmd,
.bcnth = 0,
.bcntl = 0,
.data = {0},
}
};
return u2fzero_send(dev, &req);
}
static int u2fzero_brightness_set(struct led_classdev *ldev,
enum led_brightness brightness)
{
ldev->brightness = LED_OFF;
if (brightness)
return u2fzero_blink(ldev);
else
return 0;
}
static int u2fzero_rng_read(struct hwrng *rng, void *data,
size_t max, bool wait)
{
struct u2fzero_device *dev = container_of(rng,
struct u2fzero_device, hwrng);
struct u2f_hid_report req = {
.report_type = 0,
.msg.cid = CID_BROADCAST,
.msg.init = {
.cmd = hw_configs[dev->hw_revision].rng_cmd,
.bcnth = 0,
.bcntl = 0,
.data = {0},
}
};
struct u2f_hid_msg resp;
int ret;
size_t actual_length;
/* valid packets must have a correct header */
int min_length = offsetof(struct u2f_hid_msg, init.data);
if (!dev->present) {
hid_dbg(dev->hdev, "device not present");
return 0;
}
ret = u2fzero_recv(dev, &req, &resp);
/* ignore errors or packets without data */
if (ret < min_length)
return 0;
/* only take the minimum amount of data it is safe to take */
actual_length = min3((size_t)ret - min_length,
U2F_HID_MSG_LEN(resp), max);
memcpy(data, resp.init.data, actual_length);
return actual_length;
}
static int u2fzero_init_led(struct u2fzero_device *dev,
unsigned int minor)
{
dev->led_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
"%s%u", DRIVER_SHORT, minor);
if (dev->led_name == NULL)
return -ENOMEM;
dev->ldev.name = dev->led_name;
dev->ldev.max_brightness = LED_ON;
dev->ldev.flags = LED_HW_PLUGGABLE;
dev->ldev.brightness_set_blocking = u2fzero_brightness_set;
return devm_led_classdev_register(&dev->hdev->dev, &dev->ldev);
}
static int u2fzero_init_hwrng(struct u2fzero_device *dev,
unsigned int minor)
{
dev->rng_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
"%s-rng%u", DRIVER_SHORT, minor);
if (dev->rng_name == NULL)
return -ENOMEM;
dev->hwrng.name = dev->rng_name;
dev->hwrng.read = u2fzero_rng_read;
return devm_hwrng_register(&dev->hdev->dev, &dev->hwrng);
}
static int u2fzero_fill_in_urb(struct u2fzero_device *dev)
{
struct hid_device *hdev = dev->hdev;
struct usb_device *udev;
struct usbhid_device *usbhid = hdev->driver_data;
unsigned int pipe_in;
struct usb_host_endpoint *ep;
if (dev->hdev->bus != BUS_USB)
return -EINVAL;
udev = hid_to_usb_dev(hdev);
if (!usbhid->urbout || !usbhid->urbin)
return -ENODEV;
ep = usb_pipe_endpoint(udev, usbhid->urbin->pipe);
if (!ep)
return -ENODEV;
dev->urb = usb_alloc_urb(0, GFP_KERNEL);
if (!dev->urb)
return -ENOMEM;
pipe_in = (usbhid->urbin->pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
usb_fill_int_urb(dev->urb,
udev,
pipe_in,
dev->buf_in,
HID_REPORT_SIZE,
u2fzero_read_callback,
NULL,
ep->desc.bInterval);
return 0;
}
static int u2fzero_probe(struct hid_device *hdev,
const struct hid_device_id *id)
{
struct u2fzero_device *dev;
unsigned int minor;
int ret;
if (!hid_is_usb(hdev))
return -EINVAL;
dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
if (dev == NULL)
return -ENOMEM;
dev->hw_revision = id->driver_data;
dev->buf_out = devm_kmalloc(&hdev->dev,
sizeof(struct u2f_hid_report), GFP_KERNEL);
if (dev->buf_out == NULL)
return -ENOMEM;
dev->buf_in = devm_kmalloc(&hdev->dev,
sizeof(struct u2f_hid_msg), GFP_KERNEL);
if (dev->buf_in == NULL)
return -ENOMEM;
ret = hid_parse(hdev);
if (ret)
return ret;
dev->hdev = hdev;
hid_set_drvdata(hdev, dev);
mutex_init(&dev->lock);
ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
if (ret)
return ret;
u2fzero_fill_in_urb(dev);
dev->present = true;
minor = ((struct hidraw *) hdev->hidraw)->minor;
ret = u2fzero_init_led(dev, minor);
if (ret) {
hid_hw_stop(hdev);
return ret;
}
hid_info(hdev, "%s LED initialised\n", hw_configs[dev->hw_revision].name);
ret = u2fzero_init_hwrng(dev, minor);
if (ret) {
hid_hw_stop(hdev);
return ret;
}
hid_info(hdev, "%s RNG initialised\n", hw_configs[dev->hw_revision].name);
return 0;
}
static void u2fzero_remove(struct hid_device *hdev)
{
struct u2fzero_device *dev = hid_get_drvdata(hdev);
mutex_lock(&dev->lock);
dev->present = false;
mutex_unlock(&dev->lock);
hid_hw_stop(hdev);
usb_poison_urb(dev->urb);
usb_free_urb(dev->urb);
}
static const struct hid_device_id u2fzero_table[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL,
USB_DEVICE_ID_U2F_ZERO),
.driver_data = HW_U2FZERO },
{ HID_USB_DEVICE(USB_VENDOR_ID_CLAY_LOGIC,
USB_DEVICE_ID_NITROKEY_U2F),
.driver_data = HW_NITROKEY_U2F },
{ }
};
MODULE_DEVICE_TABLE(hid, u2fzero_table);
static struct hid_driver u2fzero_driver = {
.name = "hid-" DRIVER_SHORT,
.probe = u2fzero_probe,
.remove = u2fzero_remove,
.id_table = u2fzero_table,
};
module_hid_driver(u2fzero_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Andrej Shadura <[email protected]>");
MODULE_DESCRIPTION("U2F Zero LED and RNG driver");
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