drivers/staging/greybus/authentication.c

   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
  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  */
  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 */
  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
  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
 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
 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
 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
 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
 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
 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
 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
 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
 401 int cap_init(void)
 402 {
 403         int ret;
 404
 405         cap_class = class_create(THIS_MODULE, "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
 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 }