U2F Zero supports custom commands for blinking the LED and getting data
from the internal hardware RNG. Expose the blinking function as a LED
device, and the internal hardware RNG as an HWRNG so that it can be used
to feed the enthropy pool.
Signed-off-by: Andrej Shadura <andrew.shadura@xxxxxxxxxxxxxxx>
---
drivers/hid/Kconfig | 15 ++
drivers/hid/Makefile | 1 +
drivers/hid/hid-ids.h | 1 +
drivers/hid/hid-u2fzero.c | 371 ++++++++++++++++++++++++++++++++++++++
4 files changed, 388 insertions(+)
create mode 100644 drivers/hid/hid-u2fzero.c
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 61e1953ff921..3de6bf202f20 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -975,6 +975,21 @@ config HID_UDRAW_PS3
Say Y here if you want to use the THQ uDraw gaming tablet for
the PS3.
+config HID_U2FZERO
+ tristate "U2F Zero LED and RNG support"
+ depends on HID
+ depends on LEDS_CLASS
+ help
+ Support for the LED of the U2F Zero device.
+
+ U2F Zero supports custom commands for blinking the LED
+ and getting data from the internal hardware RNG.
+ The internal hardware can be used to feed the enthropy pool.
+
+ U2F Zero only supports blinking its LED, so this driver doesn't
+ allow setting the brightness to anything but 1, which will
+ trigger a single blink and immediately reset to back 0.
+
config HID_WACOM
tristate "Wacom Intuos/Graphire tablet support (USB)"
depends on USB_HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index bd7ac53b75c5..617b1a928b6a 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -107,6 +107,7 @@ obj-$(CONFIG_HID_THRUSTMASTER) += hid-tmff.o
obj-$(CONFIG_HID_TIVO) += hid-tivo.o
obj-$(CONFIG_HID_TOPSEED) += hid-topseed.o
obj-$(CONFIG_HID_TWINHAN) += hid-twinhan.o
+obj-$(CONFIG_HID_U2FZERO) += hid-u2fzero.o
obj-$(CONFIG_HID_UCLOGIC) += hid-uclogic.o
obj-$(CONFIG_HID_UDRAW_PS3) += hid-udraw-ps3.o
obj-$(CONFIG_HID_LED) += hid-led.o
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index bc49909aba8e..070a2fcd8a18 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -309,6 +309,7 @@
#define USB_DEVICE_ID_CYGNAL_RADIO_SI470X 0x818a
#define USB_DEVICE_ID_FOCALTECH_FTXXXX_MULTITOUCH 0x81b9
#define USB_DEVICE_ID_CYGNAL_CP2112 0xea90
+#define USB_DEVICE_ID_U2F_ZERO 0x8acf
#define USB_DEVICE_ID_CYGNAL_RADIO_SI4713 0x8244
diff --git a/drivers/hid/hid-u2fzero.c b/drivers/hid/hid-u2fzero.c
new file mode 100644
index 000000000000..bd4077c93c97
--- /dev/null
+++ b/drivers/hid/hid-u2fzero.c
@@ -0,0 +1,371 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * U2F Zero LED and RNG driver
+ *
+ * Copyright 2018 Andrej Shadura <andrew@xxxxxxxxxx>
+ * 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
+
+/* 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)
+
+/* Custom extensions to the U2FHID protocol */
+#define U2F_CUSTOM_GET_RNG 0x21
+#define U2F_CUSTOM_WINK 0x24
+
+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;
+};
+
+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 = U2F_CUSTOM_WINK,
+ .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 = U2F_CUSTOM_GET_RNG,
+ .bcnth = 0,
+ .bcntl = 0,
+ .data = {0},
+ }
+ };
+ struct u2f_hid_msg resp;
+ int ret;
+ size_t actual_length;
+
+ if (!dev->present) {
+ hid_dbg(dev->hdev, "device not present");
+ return 0;
+ }
+
+ ret = u2fzero_recv(dev, &req, &resp);
+ if (ret < 0)
+ return 0;
+
+ /* only take the minimum amount of data it is safe to take */
+ actual_length = min3((size_t)ret - offsetof(struct u2f_hid_msg,
+ init.data), 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;
+ dev->hwrng.quality = 1024;
+
+ 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;
+
+ dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
+ if (dev == NULL)
+ return -ENOMEM;
+
+ 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, "U2F Zero LED initialised\n");
+
+ ret = u2fzero_init_hwrng(dev, minor);
+ if (ret) {
+ hid_hw_stop(hdev);
+ return ret;
+ }
+
+ hid_info(hdev, "U2F Zero RNG initialised\n");
+
+ 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) },
+ { }
+};
+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 <andrew@xxxxxxxxxx>");
+MODULE_DESCRIPTION("U2F Zero LED and RNG driver");
--
2.19.1
