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- // 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;
- 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_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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