drivers/hid/hid-u2fzero.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * U2F Zero LED and RNG driver
  *
  * Copyright 2018 Andrej Shadura <andrew@shadura.me>
  * 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;
 	dev->hwrng.quality = 1;

 	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_using_ll_driver(hdev, &usb_hid_driver))
 		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 <andrew@shadura.me>");
 MODULE_DESCRIPTION("U2F Zero LED and RNG driver");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* U2F Zero LED and RNG driver
	*
	* Copyright 2018 Andrej Shadura <andrew@shadura.me>
	* 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;
	dev->hwrng.quality = 1;

	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_using_ll_driver(hdev, &usb_hid_driver))
	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 <andrew@shadura.me>");
	MODULE_DESCRIPTION("U2F Zero LED and RNG driver");