1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Greybus Component Authentication Protocol (CAP) Driver.
4 *
5 * Copyright 2016 Google Inc.
6 * Copyright 2016 Linaro Ltd.
7 */
8
9 #include <linux/greybus.h>
10 #include <linux/cdev.h>
11 #include <linux/fs.h>
12 #include <linux/ioctl.h>
13 #include <linux/uaccess.h>
14
15 #include "greybus_authentication.h"
16 #include "firmware.h"
17
18 #define CAP_TIMEOUT_MS 1000
19
20 /*
21 * Number of minor devices this driver supports.
22 * There will be exactly one required per Interface.
23 */
24 #define NUM_MINORS U8_MAX
25
26 struct gb_cap {
27 struct device *parent;
28 struct gb_connection *connection;
29 struct kref kref;
30 struct list_head node;
31 bool disabled; /* connection getting disabled */
32
33 struct mutex mutex;
34 struct cdev cdev;
35 struct device *class_device;
36 dev_t dev_num;
37 };
38
39 static struct class *cap_class;
40 static dev_t cap_dev_num;
41 static DEFINE_IDA(cap_minors_map);
42 static LIST_HEAD(cap_list);
43 static DEFINE_MUTEX(list_mutex);
44
cap_kref_release(struct kref * kref)45 static void cap_kref_release(struct kref *kref)
46 {
47 struct gb_cap *cap = container_of(kref, struct gb_cap, kref);
48
49 kfree(cap);
50 }
51
52 /*
53 * All users of cap take a reference (from within list_mutex lock), before
54 * they get a pointer to play with. And the structure will be freed only after
55 * the last user has put the reference to it.
56 */
put_cap(struct gb_cap * cap)57 static void put_cap(struct gb_cap *cap)
58 {
59 kref_put(&cap->kref, cap_kref_release);
60 }
61
62 /* Caller must call put_cap() after using struct gb_cap */
get_cap(struct cdev * cdev)63 static struct gb_cap *get_cap(struct cdev *cdev)
64 {
65 struct gb_cap *cap;
66
67 mutex_lock(&list_mutex);
68
69 list_for_each_entry(cap, &cap_list, node) {
70 if (&cap->cdev == cdev) {
71 kref_get(&cap->kref);
72 goto unlock;
73 }
74 }
75
76 cap = NULL;
77
78 unlock:
79 mutex_unlock(&list_mutex);
80
81 return cap;
82 }
83
cap_get_endpoint_uid(struct gb_cap * cap,u8 * euid)84 static int cap_get_endpoint_uid(struct gb_cap *cap, u8 *euid)
85 {
86 struct gb_connection *connection = cap->connection;
87 struct gb_cap_get_endpoint_uid_response response;
88 int ret;
89
90 ret = gb_operation_sync(connection, GB_CAP_TYPE_GET_ENDPOINT_UID, NULL,
91 0, &response, sizeof(response));
92 if (ret) {
93 dev_err(cap->parent, "failed to get endpoint uid (%d)\n", ret);
94 return ret;
95 }
96
97 memcpy(euid, response.uid, sizeof(response.uid));
98
99 return 0;
100 }
101
cap_get_ims_certificate(struct gb_cap * cap,u32 class,u32 id,u8 * certificate,u32 * size,u8 * result)102 static int cap_get_ims_certificate(struct gb_cap *cap, u32 class, u32 id,
103 u8 *certificate, u32 *size, u8 *result)
104 {
105 struct gb_connection *connection = cap->connection;
106 struct gb_cap_get_ims_certificate_request *request;
107 struct gb_cap_get_ims_certificate_response *response;
108 size_t max_size = gb_operation_get_payload_size_max(connection);
109 struct gb_operation *op;
110 int ret;
111
112 op = gb_operation_create_flags(connection,
113 GB_CAP_TYPE_GET_IMS_CERTIFICATE,
114 sizeof(*request), max_size,
115 GB_OPERATION_FLAG_SHORT_RESPONSE,
116 GFP_KERNEL);
117 if (!op)
118 return -ENOMEM;
119
120 request = op->request->payload;
121 request->certificate_class = cpu_to_le32(class);
122 request->certificate_id = cpu_to_le32(id);
123
124 ret = gb_operation_request_send_sync(op);
125 if (ret) {
126 dev_err(cap->parent, "failed to get certificate (%d)\n", ret);
127 goto done;
128 }
129
130 response = op->response->payload;
131 *result = response->result_code;
132 *size = op->response->payload_size - sizeof(*response);
133 memcpy(certificate, response->certificate, *size);
134
135 done:
136 gb_operation_put(op);
137 return ret;
138 }
139
cap_authenticate(struct gb_cap * cap,u32 auth_type,u8 * uid,u8 * challenge,u8 * result,u8 * auth_response,u32 * signature_size,u8 * signature)140 static int cap_authenticate(struct gb_cap *cap, u32 auth_type, u8 *uid,
141 u8 *challenge, u8 *result, u8 *auth_response,
142 u32 *signature_size, u8 *signature)
143 {
144 struct gb_connection *connection = cap->connection;
145 struct gb_cap_authenticate_request *request;
146 struct gb_cap_authenticate_response *response;
147 size_t max_size = gb_operation_get_payload_size_max(connection);
148 struct gb_operation *op;
149 int ret;
150
151 op = gb_operation_create_flags(connection, GB_CAP_TYPE_AUTHENTICATE,
152 sizeof(*request), max_size,
153 GB_OPERATION_FLAG_SHORT_RESPONSE,
154 GFP_KERNEL);
155 if (!op)
156 return -ENOMEM;
157
158 request = op->request->payload;
159 request->auth_type = cpu_to_le32(auth_type);
160 memcpy(request->uid, uid, sizeof(request->uid));
161 memcpy(request->challenge, challenge, sizeof(request->challenge));
162
163 ret = gb_operation_request_send_sync(op);
164 if (ret) {
165 dev_err(cap->parent, "failed to authenticate (%d)\n", ret);
166 goto done;
167 }
168
169 response = op->response->payload;
170 *result = response->result_code;
171 *signature_size = op->response->payload_size - sizeof(*response);
172 memcpy(auth_response, response->response, sizeof(response->response));
173 memcpy(signature, response->signature, *signature_size);
174
175 done:
176 gb_operation_put(op);
177 return ret;
178 }
179
180 /* Char device fops */
181
cap_open(struct inode * inode,struct file * file)182 static int cap_open(struct inode *inode, struct file *file)
183 {
184 struct gb_cap *cap = get_cap(inode->i_cdev);
185
186 /* cap structure can't get freed until file descriptor is closed */
187 if (cap) {
188 file->private_data = cap;
189 return 0;
190 }
191
192 return -ENODEV;
193 }
194
cap_release(struct inode * inode,struct file * file)195 static int cap_release(struct inode *inode, struct file *file)
196 {
197 struct gb_cap *cap = file->private_data;
198
199 put_cap(cap);
200 return 0;
201 }
202
cap_ioctl(struct gb_cap * cap,unsigned int cmd,void __user * buf)203 static int cap_ioctl(struct gb_cap *cap, unsigned int cmd,
204 void __user *buf)
205 {
206 struct cap_ioc_get_endpoint_uid endpoint_uid;
207 struct cap_ioc_get_ims_certificate *ims_cert;
208 struct cap_ioc_authenticate *authenticate;
209 size_t size;
210 int ret;
211
212 switch (cmd) {
213 case CAP_IOC_GET_ENDPOINT_UID:
214 ret = cap_get_endpoint_uid(cap, endpoint_uid.uid);
215 if (ret)
216 return ret;
217
218 if (copy_to_user(buf, &endpoint_uid, sizeof(endpoint_uid)))
219 return -EFAULT;
220
221 return 0;
222 case CAP_IOC_GET_IMS_CERTIFICATE:
223 size = sizeof(*ims_cert);
224 ims_cert = memdup_user(buf, size);
225 if (IS_ERR(ims_cert))
226 return PTR_ERR(ims_cert);
227
228 ret = cap_get_ims_certificate(cap, ims_cert->certificate_class,
229 ims_cert->certificate_id,
230 ims_cert->certificate,
231 &ims_cert->cert_size,
232 &ims_cert->result_code);
233 if (!ret && copy_to_user(buf, ims_cert, size))
234 ret = -EFAULT;
235 kfree(ims_cert);
236
237 return ret;
238 case CAP_IOC_AUTHENTICATE:
239 size = sizeof(*authenticate);
240 authenticate = memdup_user(buf, size);
241 if (IS_ERR(authenticate))
242 return PTR_ERR(authenticate);
243
244 ret = cap_authenticate(cap, authenticate->auth_type,
245 authenticate->uid,
246 authenticate->challenge,
247 &authenticate->result_code,
248 authenticate->response,
249 &authenticate->signature_size,
250 authenticate->signature);
251 if (!ret && copy_to_user(buf, authenticate, size))
252 ret = -EFAULT;
253 kfree(authenticate);
254
255 return ret;
256 default:
257 return -ENOTTY;
258 }
259 }
260
cap_ioctl_unlocked(struct file * file,unsigned int cmd,unsigned long arg)261 static long cap_ioctl_unlocked(struct file *file, unsigned int cmd,
262 unsigned long arg)
263 {
264 struct gb_cap *cap = file->private_data;
265 struct gb_bundle *bundle = cap->connection->bundle;
266 int ret = -ENODEV;
267
268 /*
269 * Serialize ioctls.
270 *
271 * We don't want the user to do multiple authentication operations in
272 * parallel.
273 *
274 * This is also used to protect ->disabled, which is used to check if
275 * the connection is getting disconnected, so that we don't start any
276 * new operations.
277 */
278 mutex_lock(&cap->mutex);
279 if (!cap->disabled) {
280 ret = gb_pm_runtime_get_sync(bundle);
281 if (!ret) {
282 ret = cap_ioctl(cap, cmd, (void __user *)arg);
283 gb_pm_runtime_put_autosuspend(bundle);
284 }
285 }
286 mutex_unlock(&cap->mutex);
287
288 return ret;
289 }
290
291 static const struct file_operations cap_fops = {
292 .owner = THIS_MODULE,
293 .open = cap_open,
294 .release = cap_release,
295 .unlocked_ioctl = cap_ioctl_unlocked,
296 };
297
gb_cap_connection_init(struct gb_connection * connection)298 int gb_cap_connection_init(struct gb_connection *connection)
299 {
300 struct gb_cap *cap;
301 int ret, minor;
302
303 if (!connection)
304 return 0;
305
306 cap = kzalloc(sizeof(*cap), GFP_KERNEL);
307 if (!cap)
308 return -ENOMEM;
309
310 cap->parent = &connection->bundle->dev;
311 cap->connection = connection;
312 mutex_init(&cap->mutex);
313 gb_connection_set_data(connection, cap);
314 kref_init(&cap->kref);
315
316 mutex_lock(&list_mutex);
317 list_add(&cap->node, &cap_list);
318 mutex_unlock(&list_mutex);
319
320 ret = gb_connection_enable(connection);
321 if (ret)
322 goto err_list_del;
323
324 minor = ida_simple_get(&cap_minors_map, 0, NUM_MINORS, GFP_KERNEL);
325 if (minor < 0) {
326 ret = minor;
327 goto err_connection_disable;
328 }
329
330 /* Add a char device to allow userspace to interact with cap */
331 cap->dev_num = MKDEV(MAJOR(cap_dev_num), minor);
332 cdev_init(&cap->cdev, &cap_fops);
333
334 ret = cdev_add(&cap->cdev, cap->dev_num, 1);
335 if (ret)
336 goto err_remove_ida;
337
338 /* Add a soft link to the previously added char-dev within the bundle */
339 cap->class_device = device_create(cap_class, cap->parent, cap->dev_num,
340 NULL, "gb-authenticate-%d", minor);
341 if (IS_ERR(cap->class_device)) {
342 ret = PTR_ERR(cap->class_device);
343 goto err_del_cdev;
344 }
345
346 return 0;
347
348 err_del_cdev:
349 cdev_del(&cap->cdev);
350 err_remove_ida:
351 ida_simple_remove(&cap_minors_map, minor);
352 err_connection_disable:
353 gb_connection_disable(connection);
354 err_list_del:
355 mutex_lock(&list_mutex);
356 list_del(&cap->node);
357 mutex_unlock(&list_mutex);
358
359 put_cap(cap);
360
361 return ret;
362 }
363
gb_cap_connection_exit(struct gb_connection * connection)364 void gb_cap_connection_exit(struct gb_connection *connection)
365 {
366 struct gb_cap *cap;
367
368 if (!connection)
369 return;
370
371 cap = gb_connection_get_data(connection);
372
373 device_destroy(cap_class, cap->dev_num);
374 cdev_del(&cap->cdev);
375 ida_simple_remove(&cap_minors_map, MINOR(cap->dev_num));
376
377 /*
378 * Disallow any new ioctl operations on the char device and wait for
379 * existing ones to finish.
380 */
381 mutex_lock(&cap->mutex);
382 cap->disabled = true;
383 mutex_unlock(&cap->mutex);
384
385 /* All pending greybus operations should have finished by now */
386 gb_connection_disable(cap->connection);
387
388 /* Disallow new users to get access to the cap structure */
389 mutex_lock(&list_mutex);
390 list_del(&cap->node);
391 mutex_unlock(&list_mutex);
392
393 /*
394 * All current users of cap would have taken a reference to it by
395 * now, we can drop our reference and wait the last user will get
396 * cap freed.
397 */
398 put_cap(cap);
399 }
400
cap_init(void)401 int cap_init(void)
402 {
403 int ret;
404
405 cap_class = class_create("gb_authenticate");
406 if (IS_ERR(cap_class))
407 return PTR_ERR(cap_class);
408
409 ret = alloc_chrdev_region(&cap_dev_num, 0, NUM_MINORS,
410 "gb_authenticate");
411 if (ret)
412 goto err_remove_class;
413
414 return 0;
415
416 err_remove_class:
417 class_destroy(cap_class);
418 return ret;
419 }
420
cap_exit(void)421 void cap_exit(void)
422 {
423 unregister_chrdev_region(cap_dev_num, NUM_MINORS);
424 class_destroy(cap_class);
425 ida_destroy(&cap_minors_map);
426 }
427
