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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
29
30#define CID_BROADCAST 0xffffffff
31
32struct u2f_hid_msg {
33 u32 cid;
34 union {
35 struct {
36 u8 cmd;
37 u8 bcnth;
38 u8 bcntl;
39 u8 data[HID_REPORT_SIZE - 7];
40 } init;
41 struct {
42 u8 seq;
43 u8 data[HID_REPORT_SIZE - 5];
44 } cont;
45 };
46} __packed;
47
48struct u2f_hid_report {
49 u8 report_type;
50 struct u2f_hid_msg msg;
51} __packed;
52
53#define U2F_HID_MSG_LEN(f) (size_t)(((f).init.bcnth << 8) + (f).init.bcntl)
54
55
56#define U2F_CUSTOM_GET_RNG 0x21
57#define U2F_CUSTOM_WINK 0x24
58
59struct u2fzero_device {
60 struct hid_device *hdev;
61 struct urb *urb;
62 struct led_classdev ldev;
63 struct hwrng hwrng;
64 char *led_name;
65 char *rng_name;
66 u8 *buf_out;
67 u8 *buf_in;
68 struct mutex lock;
69 bool present;
70};
71
72static int u2fzero_send(struct u2fzero_device *dev, struct u2f_hid_report *req)
73{
74 int ret;
75
76 mutex_lock(&dev->lock);
77
78 memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
79
80 ret = hid_hw_output_report(dev->hdev, dev->buf_out,
81 sizeof(struct u2f_hid_msg));
82
83 mutex_unlock(&dev->lock);
84
85 if (ret < 0)
86 return ret;
87
88 return ret == sizeof(struct u2f_hid_msg) ? 0 : -EMSGSIZE;
89}
90
91struct u2fzero_transfer_context {
92 struct completion done;
93 int status;
94};
95
96static void u2fzero_read_callback(struct urb *urb)
97{
98 struct u2fzero_transfer_context *ctx = urb->context;
99
100 ctx->status = urb->status;
101 complete(&ctx->done);
102}
103
104static int u2fzero_recv(struct u2fzero_device *dev,
105 struct u2f_hid_report *req,
106 struct u2f_hid_msg *resp)
107{
108 int ret;
109 struct hid_device *hdev = dev->hdev;
110 struct u2fzero_transfer_context ctx;
111
112 mutex_lock(&dev->lock);
113
114 memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
115
116 dev->urb->context = &ctx;
117 init_completion(&ctx.done);
118
119 ret = usb_submit_urb(dev->urb, GFP_NOIO);
120 if (unlikely(ret)) {
121 hid_err(hdev, "usb_submit_urb failed: %d", ret);
122 goto err;
123 }
124
125 ret = hid_hw_output_report(dev->hdev, dev->buf_out,
126 sizeof(struct u2f_hid_msg));
127
128 if (ret < 0) {
129 hid_err(hdev, "hid_hw_output_report failed: %d", ret);
130 goto err;
131 }
132
133 ret = (wait_for_completion_timeout(
134 &ctx.done, msecs_to_jiffies(USB_CTRL_SET_TIMEOUT)));
135 if (ret < 0) {
136 usb_kill_urb(dev->urb);
137 hid_err(hdev, "urb submission timed out");
138 } else {
139 ret = dev->urb->actual_length;
140 memcpy(resp, dev->buf_in, ret);
141 }
142
143err:
144 mutex_unlock(&dev->lock);
145
146 return ret;
147}
148
149static int u2fzero_blink(struct led_classdev *ldev)
150{
151 struct u2fzero_device *dev = container_of(ldev,
152 struct u2fzero_device, ldev);
153 struct u2f_hid_report req = {
154 .report_type = 0,
155 .msg.cid = CID_BROADCAST,
156 .msg.init = {
157 .cmd = U2F_CUSTOM_WINK,
158 .bcnth = 0,
159 .bcntl = 0,
160 .data = {0},
161 }
162 };
163 return u2fzero_send(dev, &req);
164}
165
166static int u2fzero_brightness_set(struct led_classdev *ldev,
167 enum led_brightness brightness)
168{
169 ldev->brightness = LED_OFF;
170 if (brightness)
171 return u2fzero_blink(ldev);
172 else
173 return 0;
174}
175
176static int u2fzero_rng_read(struct hwrng *rng, void *data,
177 size_t max, bool wait)
178{
179 struct u2fzero_device *dev = container_of(rng,
180 struct u2fzero_device, hwrng);
181 struct u2f_hid_report req = {
182 .report_type = 0,
183 .msg.cid = CID_BROADCAST,
184 .msg.init = {
185 .cmd = U2F_CUSTOM_GET_RNG,
186 .bcnth = 0,
187 .bcntl = 0,
188 .data = {0},
189 }
190 };
191 struct u2f_hid_msg resp;
192 int ret;
193 size_t actual_length;
194
195 if (!dev->present) {
196 hid_dbg(dev->hdev, "device not present");
197 return 0;
198 }
199
200 ret = u2fzero_recv(dev, &req, &resp);
201 if (ret < 0)
202 return 0;
203
204
205 actual_length = min3((size_t)ret - offsetof(struct u2f_hid_msg,
206 init.data), U2F_HID_MSG_LEN(resp), max);
207
208 memcpy(data, resp.init.data, actual_length);
209
210 return actual_length;
211}
212
213static int u2fzero_init_led(struct u2fzero_device *dev,
214 unsigned int minor)
215{
216 dev->led_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
217 "%s%u", DRIVER_SHORT, minor);
218 if (dev->led_name == NULL)
219 return -ENOMEM;
220
221 dev->ldev.name = dev->led_name;
222 dev->ldev.max_brightness = LED_ON;
223 dev->ldev.flags = LED_HW_PLUGGABLE;
224 dev->ldev.brightness_set_blocking = u2fzero_brightness_set;
225
226 return devm_led_classdev_register(&dev->hdev->dev, &dev->ldev);
227}
228
229static int u2fzero_init_hwrng(struct u2fzero_device *dev,
230 unsigned int minor)
231{
232 dev->rng_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
233 "%s-rng%u", DRIVER_SHORT, minor);
234 if (dev->rng_name == NULL)
235 return -ENOMEM;
236
237 dev->hwrng.name = dev->rng_name;
238 dev->hwrng.read = u2fzero_rng_read;
239 dev->hwrng.quality = 1;
240
241 return devm_hwrng_register(&dev->hdev->dev, &dev->hwrng);
242}
243
244static int u2fzero_fill_in_urb(struct u2fzero_device *dev)
245{
246 struct hid_device *hdev = dev->hdev;
247 struct usb_device *udev;
248 struct usbhid_device *usbhid = hdev->driver_data;
249 unsigned int pipe_in;
250 struct usb_host_endpoint *ep;
251
252 if (dev->hdev->bus != BUS_USB)
253 return -EINVAL;
254
255 udev = hid_to_usb_dev(hdev);
256
257 if (!usbhid->urbout || !usbhid->urbin)
258 return -ENODEV;
259
260 ep = usb_pipe_endpoint(udev, usbhid->urbin->pipe);
261 if (!ep)
262 return -ENODEV;
263
264 dev->urb = usb_alloc_urb(0, GFP_KERNEL);
265 if (!dev->urb)
266 return -ENOMEM;
267
268 pipe_in = (usbhid->urbin->pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
269
270 usb_fill_int_urb(dev->urb,
271 udev,
272 pipe_in,
273 dev->buf_in,
274 HID_REPORT_SIZE,
275 u2fzero_read_callback,
276 NULL,
277 ep->desc.bInterval);
278
279 return 0;
280}
281
282static int u2fzero_probe(struct hid_device *hdev,
283 const struct hid_device_id *id)
284{
285 struct u2fzero_device *dev;
286 unsigned int minor;
287 int ret;
288
289 if (!hid_is_using_ll_driver(hdev, &usb_hid_driver))
290 return -EINVAL;
291
292 dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
293 if (dev == NULL)
294 return -ENOMEM;
295
296 dev->buf_out = devm_kmalloc(&hdev->dev,
297 sizeof(struct u2f_hid_report), GFP_KERNEL);
298 if (dev->buf_out == NULL)
299 return -ENOMEM;
300
301 dev->buf_in = devm_kmalloc(&hdev->dev,
302 sizeof(struct u2f_hid_msg), GFP_KERNEL);
303 if (dev->buf_in == NULL)
304 return -ENOMEM;
305
306 ret = hid_parse(hdev);
307 if (ret)
308 return ret;
309
310 dev->hdev = hdev;
311 hid_set_drvdata(hdev, dev);
312 mutex_init(&dev->lock);
313
314 ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
315 if (ret)
316 return ret;
317
318 u2fzero_fill_in_urb(dev);
319
320 dev->present = true;
321
322 minor = ((struct hidraw *) hdev->hidraw)->minor;
323
324 ret = u2fzero_init_led(dev, minor);
325 if (ret) {
326 hid_hw_stop(hdev);
327 return ret;
328 }
329
330 hid_info(hdev, "U2F Zero LED initialised\n");
331
332 ret = u2fzero_init_hwrng(dev, minor);
333 if (ret) {
334 hid_hw_stop(hdev);
335 return ret;
336 }
337
338 hid_info(hdev, "U2F Zero RNG initialised\n");
339
340 return 0;
341}
342
343static void u2fzero_remove(struct hid_device *hdev)
344{
345 struct u2fzero_device *dev = hid_get_drvdata(hdev);
346
347 mutex_lock(&dev->lock);
348 dev->present = false;
349 mutex_unlock(&dev->lock);
350
351 hid_hw_stop(hdev);
352 usb_poison_urb(dev->urb);
353 usb_free_urb(dev->urb);
354}
355
356static const struct hid_device_id u2fzero_table[] = {
357 { HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL,
358 USB_DEVICE_ID_U2F_ZERO) },
359 { }
360};
361MODULE_DEVICE_TABLE(hid, u2fzero_table);
362
363static struct hid_driver u2fzero_driver = {
364 .name = "hid-" DRIVER_SHORT,
365 .probe = u2fzero_probe,
366 .remove = u2fzero_remove,
367 .id_table = u2fzero_table,
368};
369
370module_hid_driver(u2fzero_driver);
371
372MODULE_LICENSE("GPL");
373MODULE_AUTHOR("Andrej Shadura <andrew@shadura.me>");
374MODULE_DESCRIPTION("U2F Zero LED and RNG driver");
375
