hid-u2fzero.c 8.5 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * U2F Zero LED and RNG driver
  4. *
  5. * Copyright 2018 Andrej Shadura <[email protected]>
  6. * Loosely based on drivers/hid/hid-led.c
  7. * and drivers/usb/misc/chaoskey.c
  8. *
  9. * This program is free software; you can redistribute it and/or
  10. * modify it under the terms of the GNU General Public License as
  11. * published by the Free Software Foundation, version 2.
  12. */
  13. #include <linux/hid.h>
  14. #include <linux/hidraw.h>
  15. #include <linux/hw_random.h>
  16. #include <linux/leds.h>
  17. #include <linux/module.h>
  18. #include <linux/mutex.h>
  19. #include <linux/usb.h>
  20. #include "usbhid/usbhid.h"
  21. #include "hid-ids.h"
  22. #define DRIVER_SHORT "u2fzero"
  23. #define HID_REPORT_SIZE 64
  24. enum hw_revision {
  25. HW_U2FZERO,
  26. HW_NITROKEY_U2F,
  27. };
  28. struct hw_revision_config {
  29. u8 rng_cmd;
  30. u8 wink_cmd;
  31. const char *name;
  32. };
  33. static const struct hw_revision_config hw_configs[] = {
  34. [HW_U2FZERO] = {
  35. .rng_cmd = 0x21,
  36. .wink_cmd = 0x24,
  37. .name = "U2F Zero",
  38. },
  39. [HW_NITROKEY_U2F] = {
  40. .rng_cmd = 0xc0,
  41. .wink_cmd = 0xc2,
  42. .name = "NitroKey U2F",
  43. },
  44. };
  45. /* We only use broadcast (CID-less) messages */
  46. #define CID_BROADCAST 0xffffffff
  47. struct u2f_hid_msg {
  48. u32 cid;
  49. union {
  50. struct {
  51. u8 cmd;
  52. u8 bcnth;
  53. u8 bcntl;
  54. u8 data[HID_REPORT_SIZE - 7];
  55. } init;
  56. struct {
  57. u8 seq;
  58. u8 data[HID_REPORT_SIZE - 5];
  59. } cont;
  60. };
  61. } __packed;
  62. struct u2f_hid_report {
  63. u8 report_type;
  64. struct u2f_hid_msg msg;
  65. } __packed;
  66. #define U2F_HID_MSG_LEN(f) (size_t)(((f).init.bcnth << 8) + (f).init.bcntl)
  67. struct u2fzero_device {
  68. struct hid_device *hdev;
  69. struct urb *urb; /* URB for the RNG data */
  70. struct led_classdev ldev; /* Embedded struct for led */
  71. struct hwrng hwrng; /* Embedded struct for hwrng */
  72. char *led_name;
  73. char *rng_name;
  74. u8 *buf_out;
  75. u8 *buf_in;
  76. struct mutex lock;
  77. bool present;
  78. kernel_ulong_t hw_revision;
  79. };
  80. static int u2fzero_send(struct u2fzero_device *dev, struct u2f_hid_report *req)
  81. {
  82. int ret;
  83. mutex_lock(&dev->lock);
  84. memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
  85. ret = hid_hw_output_report(dev->hdev, dev->buf_out,
  86. sizeof(struct u2f_hid_msg));
  87. mutex_unlock(&dev->lock);
  88. if (ret < 0)
  89. return ret;
  90. return ret == sizeof(struct u2f_hid_msg) ? 0 : -EMSGSIZE;
  91. }
  92. struct u2fzero_transfer_context {
  93. struct completion done;
  94. int status;
  95. };
  96. static void u2fzero_read_callback(struct urb *urb)
  97. {
  98. struct u2fzero_transfer_context *ctx = urb->context;
  99. ctx->status = urb->status;
  100. complete(&ctx->done);
  101. }
  102. static int u2fzero_recv(struct u2fzero_device *dev,
  103. struct u2f_hid_report *req,
  104. struct u2f_hid_msg *resp)
  105. {
  106. int ret;
  107. struct hid_device *hdev = dev->hdev;
  108. struct u2fzero_transfer_context ctx;
  109. mutex_lock(&dev->lock);
  110. memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
  111. dev->urb->context = &ctx;
  112. init_completion(&ctx.done);
  113. ret = usb_submit_urb(dev->urb, GFP_NOIO);
  114. if (unlikely(ret)) {
  115. hid_err(hdev, "usb_submit_urb failed: %d", ret);
  116. goto err;
  117. }
  118. ret = hid_hw_output_report(dev->hdev, dev->buf_out,
  119. sizeof(struct u2f_hid_msg));
  120. if (ret < 0) {
  121. hid_err(hdev, "hid_hw_output_report failed: %d", ret);
  122. goto err;
  123. }
  124. ret = (wait_for_completion_timeout(
  125. &ctx.done, msecs_to_jiffies(USB_CTRL_SET_TIMEOUT)));
  126. if (ret == 0) {
  127. usb_kill_urb(dev->urb);
  128. hid_err(hdev, "urb submission timed out");
  129. } else {
  130. ret = dev->urb->actual_length;
  131. memcpy(resp, dev->buf_in, ret);
  132. }
  133. err:
  134. mutex_unlock(&dev->lock);
  135. return ret;
  136. }
  137. static int u2fzero_blink(struct led_classdev *ldev)
  138. {
  139. struct u2fzero_device *dev = container_of(ldev,
  140. struct u2fzero_device, ldev);
  141. struct u2f_hid_report req = {
  142. .report_type = 0,
  143. .msg.cid = CID_BROADCAST,
  144. .msg.init = {
  145. .cmd = hw_configs[dev->hw_revision].wink_cmd,
  146. .bcnth = 0,
  147. .bcntl = 0,
  148. .data = {0},
  149. }
  150. };
  151. return u2fzero_send(dev, &req);
  152. }
  153. static int u2fzero_brightness_set(struct led_classdev *ldev,
  154. enum led_brightness brightness)
  155. {
  156. ldev->brightness = LED_OFF;
  157. if (brightness)
  158. return u2fzero_blink(ldev);
  159. else
  160. return 0;
  161. }
  162. static int u2fzero_rng_read(struct hwrng *rng, void *data,
  163. size_t max, bool wait)
  164. {
  165. struct u2fzero_device *dev = container_of(rng,
  166. struct u2fzero_device, hwrng);
  167. struct u2f_hid_report req = {
  168. .report_type = 0,
  169. .msg.cid = CID_BROADCAST,
  170. .msg.init = {
  171. .cmd = hw_configs[dev->hw_revision].rng_cmd,
  172. .bcnth = 0,
  173. .bcntl = 0,
  174. .data = {0},
  175. }
  176. };
  177. struct u2f_hid_msg resp;
  178. int ret;
  179. size_t actual_length;
  180. /* valid packets must have a correct header */
  181. int min_length = offsetof(struct u2f_hid_msg, init.data);
  182. if (!dev->present) {
  183. hid_dbg(dev->hdev, "device not present");
  184. return 0;
  185. }
  186. ret = u2fzero_recv(dev, &req, &resp);
  187. /* ignore errors or packets without data */
  188. if (ret < min_length)
  189. return 0;
  190. /* only take the minimum amount of data it is safe to take */
  191. actual_length = min3((size_t)ret - min_length,
  192. U2F_HID_MSG_LEN(resp), max);
  193. memcpy(data, resp.init.data, actual_length);
  194. return actual_length;
  195. }
  196. static int u2fzero_init_led(struct u2fzero_device *dev,
  197. unsigned int minor)
  198. {
  199. dev->led_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
  200. "%s%u", DRIVER_SHORT, minor);
  201. if (dev->led_name == NULL)
  202. return -ENOMEM;
  203. dev->ldev.name = dev->led_name;
  204. dev->ldev.max_brightness = LED_ON;
  205. dev->ldev.flags = LED_HW_PLUGGABLE;
  206. dev->ldev.brightness_set_blocking = u2fzero_brightness_set;
  207. return devm_led_classdev_register(&dev->hdev->dev, &dev->ldev);
  208. }
  209. static int u2fzero_init_hwrng(struct u2fzero_device *dev,
  210. unsigned int minor)
  211. {
  212. dev->rng_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
  213. "%s-rng%u", DRIVER_SHORT, minor);
  214. if (dev->rng_name == NULL)
  215. return -ENOMEM;
  216. dev->hwrng.name = dev->rng_name;
  217. dev->hwrng.read = u2fzero_rng_read;
  218. dev->hwrng.quality = 1;
  219. return devm_hwrng_register(&dev->hdev->dev, &dev->hwrng);
  220. }
  221. static int u2fzero_fill_in_urb(struct u2fzero_device *dev)
  222. {
  223. struct hid_device *hdev = dev->hdev;
  224. struct usb_device *udev;
  225. struct usbhid_device *usbhid = hdev->driver_data;
  226. unsigned int pipe_in;
  227. struct usb_host_endpoint *ep;
  228. if (dev->hdev->bus != BUS_USB)
  229. return -EINVAL;
  230. udev = hid_to_usb_dev(hdev);
  231. if (!usbhid->urbout || !usbhid->urbin)
  232. return -ENODEV;
  233. ep = usb_pipe_endpoint(udev, usbhid->urbin->pipe);
  234. if (!ep)
  235. return -ENODEV;
  236. dev->urb = usb_alloc_urb(0, GFP_KERNEL);
  237. if (!dev->urb)
  238. return -ENOMEM;
  239. pipe_in = (usbhid->urbin->pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
  240. usb_fill_int_urb(dev->urb,
  241. udev,
  242. pipe_in,
  243. dev->buf_in,
  244. HID_REPORT_SIZE,
  245. u2fzero_read_callback,
  246. NULL,
  247. ep->desc.bInterval);
  248. return 0;
  249. }
  250. static int u2fzero_probe(struct hid_device *hdev,
  251. const struct hid_device_id *id)
  252. {
  253. struct u2fzero_device *dev;
  254. unsigned int minor;
  255. int ret;
  256. if (!hid_is_usb(hdev))
  257. return -EINVAL;
  258. dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
  259. if (dev == NULL)
  260. return -ENOMEM;
  261. dev->hw_revision = id->driver_data;
  262. dev->buf_out = devm_kmalloc(&hdev->dev,
  263. sizeof(struct u2f_hid_report), GFP_KERNEL);
  264. if (dev->buf_out == NULL)
  265. return -ENOMEM;
  266. dev->buf_in = devm_kmalloc(&hdev->dev,
  267. sizeof(struct u2f_hid_msg), GFP_KERNEL);
  268. if (dev->buf_in == NULL)
  269. return -ENOMEM;
  270. ret = hid_parse(hdev);
  271. if (ret)
  272. return ret;
  273. dev->hdev = hdev;
  274. hid_set_drvdata(hdev, dev);
  275. mutex_init(&dev->lock);
  276. ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
  277. if (ret)
  278. return ret;
  279. u2fzero_fill_in_urb(dev);
  280. dev->present = true;
  281. minor = ((struct hidraw *) hdev->hidraw)->minor;
  282. ret = u2fzero_init_led(dev, minor);
  283. if (ret) {
  284. hid_hw_stop(hdev);
  285. return ret;
  286. }
  287. hid_info(hdev, "%s LED initialised\n", hw_configs[dev->hw_revision].name);
  288. ret = u2fzero_init_hwrng(dev, minor);
  289. if (ret) {
  290. hid_hw_stop(hdev);
  291. return ret;
  292. }
  293. hid_info(hdev, "%s RNG initialised\n", hw_configs[dev->hw_revision].name);
  294. return 0;
  295. }
  296. static void u2fzero_remove(struct hid_device *hdev)
  297. {
  298. struct u2fzero_device *dev = hid_get_drvdata(hdev);
  299. mutex_lock(&dev->lock);
  300. dev->present = false;
  301. mutex_unlock(&dev->lock);
  302. hid_hw_stop(hdev);
  303. usb_poison_urb(dev->urb);
  304. usb_free_urb(dev->urb);
  305. }
  306. static const struct hid_device_id u2fzero_table[] = {
  307. { HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL,
  308. USB_DEVICE_ID_U2F_ZERO),
  309. .driver_data = HW_U2FZERO },
  310. { HID_USB_DEVICE(USB_VENDOR_ID_CLAY_LOGIC,
  311. USB_DEVICE_ID_NITROKEY_U2F),
  312. .driver_data = HW_NITROKEY_U2F },
  313. { }
  314. };
  315. MODULE_DEVICE_TABLE(hid, u2fzero_table);
  316. static struct hid_driver u2fzero_driver = {
  317. .name = "hid-" DRIVER_SHORT,
  318. .probe = u2fzero_probe,
  319. .remove = u2fzero_remove,
  320. .id_table = u2fzero_table,
  321. };
  322. module_hid_driver(u2fzero_driver);
  323. MODULE_LICENSE("GPL");
  324. MODULE_AUTHOR("Andrej Shadura <[email protected]>");
  325. MODULE_DESCRIPTION("U2F Zero LED and RNG driver");