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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
14#include <linux/hid.h>
15#include <linux/hidraw.h>
16#include <linux/hw_random.h>
17#include <linux/leds.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/usb.h>
21
22#include "usbhid/usbhid.h"
23#include "hid-ids.h"
24
25#define DRIVER_SHORT "u2fzero"
26
27#define HID_REPORT_SIZE 64
28
29enum hw_revision {
30 HW_U2FZERO,
31 HW_NITROKEY_U2F,
32};
33
34struct hw_revision_config {
35 u8 rng_cmd;
36 u8 wink_cmd;
37 const char *name;
38};
39
40static const struct hw_revision_config hw_configs[] = {
41 [HW_U2FZERO] = {
42 .rng_cmd = 0x21,
43 .wink_cmd = 0x24,
44 .name = "U2F Zero",
45 },
46 [HW_NITROKEY_U2F] = {
47 .rng_cmd = 0xc0,
48 .wink_cmd = 0xc2,
49 .name = "NitroKey U2F",
50 },
51};
52
53/* We only use broadcast (CID-less) messages */
54#define CID_BROADCAST 0xffffffff
55
56struct u2f_hid_msg {
57 u32 cid;
58 union {
59 struct {
60 u8 cmd;
61 u8 bcnth;
62 u8 bcntl;
63 u8 data[HID_REPORT_SIZE - 7];
64 } init;
65 struct {
66 u8 seq;
67 u8 data[HID_REPORT_SIZE - 5];
68 } cont;
69 };
70} __packed;
71
72struct u2f_hid_report {
73 u8 report_type;
74 struct u2f_hid_msg msg;
75} __packed;
76
77#define U2F_HID_MSG_LEN(f) (size_t)(((f).init.bcnth << 8) + (f).init.bcntl)
78
79struct u2fzero_device {
80 struct hid_device *hdev;
81 struct urb *urb; /* URB for the RNG data */
82 struct led_classdev ldev; /* Embedded struct for led */
83 struct hwrng hwrng; /* Embedded struct for hwrng */
84 char *led_name;
85 char *rng_name;
86 u8 *buf_out;
87 u8 *buf_in;
88 struct mutex lock;
89 bool present;
90 kernel_ulong_t hw_revision;
91};
92
93static int u2fzero_send(struct u2fzero_device *dev, struct u2f_hid_report *req)
94{
95 int ret;
96
97 mutex_lock(&dev->lock);
98
99 memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
100
101 ret = hid_hw_output_report(dev->hdev, dev->buf_out,
102 sizeof(struct u2f_hid_msg));
103
104 mutex_unlock(&dev->lock);
105
106 if (ret < 0)
107 return ret;
108
109 return ret == sizeof(struct u2f_hid_msg) ? 0 : -EMSGSIZE;
110}
111
112struct u2fzero_transfer_context {
113 struct completion done;
114 int status;
115};
116
117static void u2fzero_read_callback(struct urb *urb)
118{
119 struct u2fzero_transfer_context *ctx = urb->context;
120
121 ctx->status = urb->status;
122 complete(&ctx->done);
123}
124
125static int u2fzero_recv(struct u2fzero_device *dev,
126 struct u2f_hid_report *req,
127 struct u2f_hid_msg *resp)
128{
129 int ret;
130 struct hid_device *hdev = dev->hdev;
131 struct u2fzero_transfer_context ctx;
132
133 mutex_lock(&dev->lock);
134
135 memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
136
137 dev->urb->context = &ctx;
138 init_completion(&ctx.done);
139
140 ret = usb_submit_urb(dev->urb, GFP_NOIO);
141 if (unlikely(ret)) {
142 hid_err(hdev, "usb_submit_urb failed: %d", ret);
143 goto err;
144 }
145
146 ret = hid_hw_output_report(dev->hdev, dev->buf_out,
147 sizeof(struct u2f_hid_msg));
148
149 if (ret < 0) {
150 hid_err(hdev, "hid_hw_output_report failed: %d", ret);
151 goto err;
152 }
153
154 ret = (wait_for_completion_timeout(
155 &ctx.done, msecs_to_jiffies(USB_CTRL_SET_TIMEOUT)));
156 if (ret == 0) {
157 usb_kill_urb(dev->urb);
158 hid_err(hdev, "urb submission timed out");
159 } else {
160 ret = dev->urb->actual_length;
161 memcpy(resp, dev->buf_in, ret);
162 }
163
164err:
165 mutex_unlock(&dev->lock);
166
167 return ret;
168}
169
170static int u2fzero_blink(struct led_classdev *ldev)
171{
172 struct u2fzero_device *dev = container_of(ldev,
173 struct u2fzero_device, ldev);
174 struct u2f_hid_report req = {
175 .report_type = 0,
176 .msg.cid = CID_BROADCAST,
177 .msg.init = {
178 .cmd = hw_configs[dev->hw_revision].wink_cmd,
179 .bcnth = 0,
180 .bcntl = 0,
181 .data = {0},
182 }
183 };
184 return u2fzero_send(dev, &req);
185}
186
187static int u2fzero_brightness_set(struct led_classdev *ldev,
188 enum led_brightness brightness)
189{
190 ldev->brightness = LED_OFF;
191 if (brightness)
192 return u2fzero_blink(ldev);
193 else
194 return 0;
195}
196
197static int u2fzero_rng_read(struct hwrng *rng, void *data,
198 size_t max, bool wait)
199{
200 struct u2fzero_device *dev = container_of(rng,
201 struct u2fzero_device, hwrng);
202 struct u2f_hid_report req = {
203 .report_type = 0,
204 .msg.cid = CID_BROADCAST,
205 .msg.init = {
206 .cmd = hw_configs[dev->hw_revision].rng_cmd,
207 .bcnth = 0,
208 .bcntl = 0,
209 .data = {0},
210 }
211 };
212 struct u2f_hid_msg resp;
213 int ret;
214 size_t actual_length;
215 /* valid packets must have a correct header */
216 int min_length = offsetof(struct u2f_hid_msg, init.data);
217
218 if (!dev->present) {
219 hid_dbg(dev->hdev, "device not present");
220 return 0;
221 }
222
223 ret = u2fzero_recv(dev, &req, &resp);
224
225 /* ignore errors or packets without data */
226 if (ret < min_length)
227 return 0;
228
229 /* only take the minimum amount of data it is safe to take */
230 actual_length = min3((size_t)ret - min_length,
231 U2F_HID_MSG_LEN(resp), max);
232
233 memcpy(data, resp.init.data, actual_length);
234
235 return actual_length;
236}
237
238static int u2fzero_init_led(struct u2fzero_device *dev,
239 unsigned int minor)
240{
241 dev->led_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
242 "%s%u", DRIVER_SHORT, minor);
243 if (dev->led_name == NULL)
244 return -ENOMEM;
245
246 dev->ldev.name = dev->led_name;
247 dev->ldev.max_brightness = LED_ON;
248 dev->ldev.flags = LED_HW_PLUGGABLE;
249 dev->ldev.brightness_set_blocking = u2fzero_brightness_set;
250
251 return devm_led_classdev_register(&dev->hdev->dev, &dev->ldev);
252}
253
254static int u2fzero_init_hwrng(struct u2fzero_device *dev,
255 unsigned int minor)
256{
257 dev->rng_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
258 "%s-rng%u", DRIVER_SHORT, minor);
259 if (dev->rng_name == NULL)
260 return -ENOMEM;
261
262 dev->hwrng.name = dev->rng_name;
263 dev->hwrng.read = u2fzero_rng_read;
264
265 return devm_hwrng_register(&dev->hdev->dev, &dev->hwrng);
266}
267
268static int u2fzero_fill_in_urb(struct u2fzero_device *dev)
269{
270 struct hid_device *hdev = dev->hdev;
271 struct usb_device *udev;
272 struct usbhid_device *usbhid = hdev->driver_data;
273 unsigned int pipe_in;
274 struct usb_host_endpoint *ep;
275
276 if (dev->hdev->bus != BUS_USB)
277 return -EINVAL;
278
279 udev = hid_to_usb_dev(hdev);
280
281 if (!usbhid->urbout || !usbhid->urbin)
282 return -ENODEV;
283
284 ep = usb_pipe_endpoint(udev, usbhid->urbin->pipe);
285 if (!ep)
286 return -ENODEV;
287
288 dev->urb = usb_alloc_urb(0, GFP_KERNEL);
289 if (!dev->urb)
290 return -ENOMEM;
291
292 pipe_in = (usbhid->urbin->pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
293
294 usb_fill_int_urb(dev->urb,
295 udev,
296 pipe_in,
297 dev->buf_in,
298 HID_REPORT_SIZE,
299 u2fzero_read_callback,
300 NULL,
301 ep->desc.bInterval);
302
303 return 0;
304}
305
306static int u2fzero_probe(struct hid_device *hdev,
307 const struct hid_device_id *id)
308{
309 struct u2fzero_device *dev;
310 unsigned int minor;
311 int ret;
312
313 if (!hid_is_usb(hdev))
314 return -EINVAL;
315
316 dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
317 if (dev == NULL)
318 return -ENOMEM;
319
320 dev->hw_revision = id->driver_data;
321
322 dev->buf_out = devm_kmalloc(&hdev->dev,
323 sizeof(struct u2f_hid_report), GFP_KERNEL);
324 if (dev->buf_out == NULL)
325 return -ENOMEM;
326
327 dev->buf_in = devm_kmalloc(&hdev->dev,
328 sizeof(struct u2f_hid_msg), GFP_KERNEL);
329 if (dev->buf_in == NULL)
330 return -ENOMEM;
331
332 ret = hid_parse(hdev);
333 if (ret)
334 return ret;
335
336 dev->hdev = hdev;
337 hid_set_drvdata(hdev, dev);
338 mutex_init(&dev->lock);
339
340 ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
341 if (ret)
342 return ret;
343
344 ret = u2fzero_fill_in_urb(dev);
345 if (ret)
346 goto err_hid_hw_stop;
347
348 dev->present = true;
349
350 minor = ((struct hidraw *) hdev->hidraw)->minor;
351
352 ret = u2fzero_init_led(dev, minor);
353 if (ret)
354 goto err_free_urb;
355
356 hid_info(hdev, "%s LED initialised\n", hw_configs[dev->hw_revision].name);
357
358 ret = u2fzero_init_hwrng(dev, minor);
359 if (ret)
360 goto err_free_urb;
361
362 hid_info(hdev, "%s RNG initialised\n", hw_configs[dev->hw_revision].name);
363
364 return 0;
365
366err_free_urb:
367 usb_free_urb(dev->urb);
368err_hid_hw_stop:
369 hid_hw_stop(hdev);
370 return ret;
371}
372
373static void u2fzero_remove(struct hid_device *hdev)
374{
375 struct u2fzero_device *dev = hid_get_drvdata(hdev);
376
377 mutex_lock(&dev->lock);
378 dev->present = false;
379 mutex_unlock(&dev->lock);
380
381 hid_hw_stop(hdev);
382 usb_poison_urb(dev->urb);
383 usb_free_urb(dev->urb);
384}
385
386static const struct hid_device_id u2fzero_table[] = {
387 { HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL,
388 USB_DEVICE_ID_U2F_ZERO),
389 .driver_data = HW_U2FZERO },
390 { HID_USB_DEVICE(USB_VENDOR_ID_CLAY_LOGIC,
391 USB_DEVICE_ID_NITROKEY_U2F),
392 .driver_data = HW_NITROKEY_U2F },
393 { }
394};
395MODULE_DEVICE_TABLE(hid, u2fzero_table);
396
397static struct hid_driver u2fzero_driver = {
398 .name = "hid-" DRIVER_SHORT,
399 .probe = u2fzero_probe,
400 .remove = u2fzero_remove,
401 .id_table = u2fzero_table,
402};
403
404module_hid_driver(u2fzero_driver);
405
406MODULE_LICENSE("GPL");
407MODULE_AUTHOR("Andrej Shadura <[email protected]>");
408MODULE_DESCRIPTION("U2F Zero LED and RNG driver");