drivers/connector/connector.c

   1 /*
   2  *      connector.c
   3  *
   4  * 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru>
   5  * All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/list.h>
  25 #include <linux/skbuff.h>
  26 #include <linux/netlink.h>
  27 #include <linux/moduleparam.h>
  28 #include <linux/connector.h>
  29 #include <linux/mutex.h>
  30
  31 #include <net/sock.h>
  32
  33 MODULE_LICENSE("GPL");
  34 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
  35 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
  36
  37 static u32 cn_idx = CN_IDX_CONNECTOR;
  38 static u32 cn_val = CN_VAL_CONNECTOR;
  39
  40 module_param(cn_idx, uint, 0);
  41 module_param(cn_val, uint, 0);
  42 MODULE_PARM_DESC(cn_idx, "Connector's main device idx.");
  43 MODULE_PARM_DESC(cn_val, "Connector's main device val.");
  44
  45 static DEFINE_MUTEX(notify_lock);
  46 static LIST_HEAD(notify_list);
  47
  48 static struct cn_dev cdev;
  49
  50 int cn_already_initialized = 0;
  51
  52 /*
  53  * msg->seq and msg->ack are used to determine message genealogy.
  54  * When someone sends message it puts there locally unique sequence
  55  * and random acknowledge numbers.  Sequence number may be copied into
  56  * nlmsghdr->nlmsg_seq too.
  57  *
  58  * Sequence number is incremented with each message to be sent.
  59  *
  60  * If we expect reply to our message then the sequence number in
  61  * received message MUST be the same as in original message, and
  62  * acknowledge number MUST be the same + 1.
  63  *
  64  * If we receive a message and its sequence number is not equal to the
  65  * one we are expecting then it is a new message.
  66  *
  67  * If we receive a message and its sequence number is the same as one
  68  * we are expecting but it's acknowledgement number is not equal to
  69  * the acknowledgement number in the original message + 1, then it is
  70  * a new message.
  71  *
  72  */
  73 int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
  74 {
  75         struct cn_callback_entry *__cbq;
  76         unsigned int size;
  77         struct sk_buff *skb;
  78         struct nlmsghdr *nlh;
  79         struct cn_msg *data;
  80         struct cn_dev *dev = &cdev;
  81         u32 group = 0;
  82         int found = 0;
  83
  84         if (!__group) {
  85                 spin_lock_bh(&dev->cbdev->queue_lock);
  86                 list_for_each_entry(__cbq, &dev->cbdev->queue_list,
  87                                     callback_entry) {
  88                         if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
  89                                 found = 1;
  90                                 group = __cbq->group;
  91                         }
  92                 }
  93                 spin_unlock_bh(&dev->cbdev->queue_lock);
  94
  95                 if (!found)
  96                         return -ENODEV;
  97         } else {
  98                 group = __group;
  99         }
 100
 101         if (!netlink_has_listeners(dev->nls, group))
 102                 return -ESRCH;
 103
 104         size = NLMSG_SPACE(sizeof(*msg) + msg->len);
 105
 106         skb = alloc_skb(size, gfp_mask);
 107         if (!skb)
 108                 return -ENOMEM;
 109
 110         nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
 111
 112         data = NLMSG_DATA(nlh);
 113
 114         memcpy(data, msg, sizeof(*data) + msg->len);
 115
 116         NETLINK_CB(skb).dst_group = group;
 117
 118         return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
 119
 120 nlmsg_failure:
 121         kfree_skb(skb);
 122         return -EINVAL;
 123 }
 124 EXPORT_SYMBOL_GPL(cn_netlink_send);
 125
 126 /*
 127  * Callback helper - queues work and setup destructor for given data.
 128  */
 129 static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data)
 130 {
 131         struct cn_callback_entry *__cbq, *__new_cbq;
 132         struct cn_dev *dev = &cdev;
 133         int err = -ENODEV;
 134
 135         spin_lock_bh(&dev->cbdev->queue_lock);
 136         list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
 137                 if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
 138                         if (likely(!work_pending(&__cbq->work) &&
 139                                         __cbq->data.ddata == NULL)) {
 140                                 __cbq->data.callback_priv = msg;
 141
 142                                 __cbq->data.ddata = data;
 143                                 __cbq->data.destruct_data = destruct_data;
 144
 145                                 if (queue_work(dev->cbdev->cn_queue,
 146                                                         &__cbq->work))
 147                                         err = 0;
 148                                 else
 149                                         err = -EINVAL;
 150                         } else {
 151                                 struct cn_callback_data *d;
 152
 153                                 err = -ENOMEM;
 154                                 __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
 155                                 if (__new_cbq) {
 156                                         d = &__new_cbq->data;
 157                                         d->callback_priv = msg;
 158                                         d->callback = __cbq->data.callback;
 159                                         d->ddata = data;
 160                                         d->destruct_data = destruct_data;
 161                                         d->free = __new_cbq;
 162
 163                                         INIT_WORK(&__new_cbq->work,
 164                                                         &cn_queue_wrapper);
 165
 166                                         if (queue_work(dev->cbdev->cn_queue,
 167                                                     &__new_cbq->work))
 168                                                 err = 0;
 169                                         else {
 170                                                 kfree(__new_cbq);
 171                                                 err = -EINVAL;
 172                                         }
 173                                 }
 174                         }
 175                         break;
 176                 }
 177         }
 178         spin_unlock_bh(&dev->cbdev->queue_lock);
 179
 180         return err;
 181 }
 182
 183 /*
 184  * Skb receive helper - checks skb and msg size and calls callback
 185  * helper.
 186  */
 187 static int __cn_rx_skb(struct sk_buff *skb, struct nlmsghdr *nlh)
 188 {
 189         u32 pid, uid, seq, group;
 190         struct cn_msg *msg;
 191
 192         pid = NETLINK_CREDS(skb)->pid;
 193         uid = NETLINK_CREDS(skb)->uid;
 194         seq = nlh->nlmsg_seq;
 195         group = NETLINK_CB((skb)).dst_group;
 196         msg = NLMSG_DATA(nlh);
 197
 198         return cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
 199 }
 200
 201 /*
 202  * Main netlink receiving function.
 203  *
 204  * It checks skb and netlink header sizes and calls the skb receive
 205  * helper with a shared skb.
 206  */
 207 static void cn_rx_skb(struct sk_buff *__skb)
 208 {
 209         struct nlmsghdr *nlh;
 210         u32 len;
 211         int err;
 212         struct sk_buff *skb;
 213
 214         skb = skb_get(__skb);
 215
 216         if (skb->len >= NLMSG_SPACE(0)) {
 217                 nlh = nlmsg_hdr(skb);
 218
 219                 if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 220                     skb->len < nlh->nlmsg_len ||
 221                     nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
 222                         kfree_skb(skb);
 223                         return;
 224                 }
 225
 226                 len = NLMSG_ALIGN(nlh->nlmsg_len);
 227                 if (len > skb->len)
 228                         len = skb->len;
 229
 230                 err = __cn_rx_skb(skb, nlh);
 231                 if (err < 0)
 232                         kfree_skb(skb);
 233         }
 234 }
 235
 236 /*
 237  * Notification routing.
 238  *
 239  * Gets id and checks if there are notification request for it's idx
 240  * and val.  If there are such requests notify the listeners with the
 241  * given notify event.
 242  *
 243  */
 244 static void cn_notify(struct cb_id *id, u32 notify_event)
 245 {
 246         struct cn_ctl_entry *ent;
 247
 248         mutex_lock(&notify_lock);
 249         list_for_each_entry(ent, &notify_list, notify_entry) {
 250                 int i;
 251                 struct cn_notify_req *req;
 252                 struct cn_ctl_msg *ctl = ent->msg;
 253                 int idx_found, val_found;
 254
 255                 idx_found = val_found = 0;
 256
 257                 req = (struct cn_notify_req *)ctl->data;
 258                 for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
 259                         if (id->idx >= req->first &&
 260                                         id->idx < req->first + req->range) {
 261                                 idx_found = 1;
 262                                 break;
 263                         }
 264                 }
 265
 266                 for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
 267                         if (id->val >= req->first &&
 268                                         id->val < req->first + req->range) {
 269                                 val_found = 1;
 270                                 break;
 271                         }
 272                 }
 273
 274                 if (idx_found && val_found) {
 275                         struct cn_msg m = { .ack = notify_event, };
 276
 277                         memcpy(&m.id, id, sizeof(m.id));
 278                         cn_netlink_send(&m, ctl->group, GFP_KERNEL);
 279                 }
 280         }
 281         mutex_unlock(&notify_lock);
 282 }
 283
 284 /*
 285  * Callback add routing - adds callback with given ID and name.
 286  * If there is registered callback with the same ID it will not be added.
 287  *
 288  * May sleep.
 289  */
 290 int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
 291 {
 292         int err;
 293         struct cn_dev *dev = &cdev;
 294
 295         if (!cn_already_initialized)
 296                 return -EAGAIN;
 297
 298         err = cn_queue_add_callback(dev->cbdev, name, id, callback);
 299         if (err)
 300                 return err;
 301
 302         cn_notify(id, 0);
 303
 304         return 0;
 305 }
 306 EXPORT_SYMBOL_GPL(cn_add_callback);
 307
 308 /*
 309  * Callback remove routing - removes callback
 310  * with given ID.
 311  * If there is no registered callback with given
 312  * ID nothing happens.
 313  *
 314  * May sleep while waiting for reference counter to become zero.
 315  */
 316 void cn_del_callback(struct cb_id *id)
 317 {
 318         struct cn_dev *dev = &cdev;
 319
 320         cn_queue_del_callback(dev->cbdev, id);
 321         cn_notify(id, 1);
 322 }
 323 EXPORT_SYMBOL_GPL(cn_del_callback);
 324
 325 /*
 326  * Checks two connector's control messages to be the same.
 327  * Returns 1 if they are the same or if the first one is corrupted.
 328  */
 329 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
 330 {
 331         int i;
 332         struct cn_notify_req *req1, *req2;
 333
 334         if (m1->idx_notify_num != m2->idx_notify_num)
 335                 return 0;
 336
 337         if (m1->val_notify_num != m2->val_notify_num)
 338                 return 0;
 339
 340         if (m1->len != m2->len)
 341                 return 0;
 342
 343         if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
 344             m1->len)
 345                 return 1;
 346
 347         req1 = (struct cn_notify_req *)m1->data;
 348         req2 = (struct cn_notify_req *)m2->data;
 349
 350         for (i = 0; i < m1->idx_notify_num; ++i) {
 351                 if (req1->first != req2->first || req1->range != req2->range)
 352                         return 0;
 353                 req1++;
 354                 req2++;
 355         }
 356
 357         for (i = 0; i < m1->val_notify_num; ++i) {
 358                 if (req1->first != req2->first || req1->range != req2->range)
 359                         return 0;
 360                 req1++;
 361                 req2++;
 362         }
 363
 364         return 1;
 365 }
 366
 367 /*
 368  * Main connector device's callback.
 369  *
 370  * Used for notification of a request's processing.
 371  */
 372 static void cn_callback(void *data)
 373 {
 374         struct cn_msg *msg = data;
 375         struct cn_ctl_msg *ctl;
 376         struct cn_ctl_entry *ent;
 377         u32 size;
 378
 379         if (msg->len < sizeof(*ctl))
 380                 return;
 381
 382         ctl = (struct cn_ctl_msg *)msg->data;
 383
 384         size = (sizeof(*ctl) + ((ctl->idx_notify_num +
 385                                  ctl->val_notify_num) *
 386                                 sizeof(struct cn_notify_req)));
 387
 388         if (msg->len != size)
 389                 return;
 390
 391         if (ctl->len + sizeof(*ctl) != msg->len)
 392                 return;
 393
 394         /*
 395          * Remove notification.
 396          */
 397         if (ctl->group == 0) {
 398                 struct cn_ctl_entry *n;
 399
 400                 mutex_lock(&notify_lock);
 401                 list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
 402                         if (cn_ctl_msg_equals(ent->msg, ctl)) {
 403                                 list_del(&ent->notify_entry);
 404                                 kfree(ent);
 405                         }
 406                 }
 407                 mutex_unlock(&notify_lock);
 408
 409                 return;
 410         }
 411
 412         size += sizeof(*ent);
 413
 414         ent = kzalloc(size, GFP_KERNEL);
 415         if (!ent)
 416                 return;
 417
 418         ent->msg = (struct cn_ctl_msg *)(ent + 1);
 419
 420         memcpy(ent->msg, ctl, size - sizeof(*ent));
 421
 422         mutex_lock(&notify_lock);
 423         list_add(&ent->notify_entry, &notify_list);
 424         mutex_unlock(&notify_lock);
 425 }
 426
 427 static int __devinit cn_init(void)
 428 {
 429         struct cn_dev *dev = &cdev;
 430         int err;
 431
 432         dev->input = cn_rx_skb;
 433         dev->id.idx = cn_idx;
 434         dev->id.val = cn_val;
 435
 436         dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
 437                                          CN_NETLINK_USERS + 0xf,
 438                                          dev->input, NULL, THIS_MODULE);
 439         if (!dev->nls)
 440                 return -EIO;
 441
 442         dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
 443         if (!dev->cbdev) {
 444                 if (dev->nls->sk_socket)
 445                         sock_release(dev->nls->sk_socket);
 446                 return -EINVAL;
 447         }
 448
 449         cn_already_initialized = 1;
 450
 451         err = cn_add_callback(&dev->id, "connector", &cn_callback);
 452         if (err) {
 453                 cn_already_initialized = 0;
 454                 cn_queue_free_dev(dev->cbdev);
 455                 if (dev->nls->sk_socket)
 456                         sock_release(dev->nls->sk_socket);
 457                 return -EINVAL;
 458         }
 459
 460         return 0;
 461 }
 462
 463 static void __devexit cn_fini(void)
 464 {
 465         struct cn_dev *dev = &cdev;
 466
 467         cn_already_initialized = 0;
 468
 469         cn_del_callback(&dev->id);
 470         cn_queue_free_dev(dev->cbdev);
 471         if (dev->nls->sk_socket)
 472                 sock_release(dev->nls->sk_socket);
 473 }
 474
 475 subsys_initcall(cn_init);
 476 module_exit(cn_fini);