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
  30 #include <net/sock.h>
  31
  32 MODULE_LICENSE("GPL");
  33 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
  34 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
  35
  36 static u32 cn_idx = CN_IDX_CONNECTOR;
  37 static u32 cn_val = CN_VAL_CONNECTOR;
  38
  39 module_param(cn_idx, uint, 0);
  40 module_param(cn_val, uint, 0);
  41 MODULE_PARM_DESC(cn_idx, "Connector's main device idx.");
  42 MODULE_PARM_DESC(cn_val, "Connector's main device val.");
  43
  44 static DECLARE_MUTEX(notify_lock);
  45 static LIST_HEAD(notify_list);
  46
  47 static struct cn_dev cdev;
  48
  49 int cn_already_initialized = 0;
  50
  51 /*
  52  * msg->seq and msg->ack are used to determine message genealogy.
  53  * When someone sends message it puts there locally unique sequence
  54  * and random acknowledge numbers.  Sequence number may be copied into
  55  * nlmsghdr->nlmsg_seq too.
  56  *
  57  * Sequence number is incremented with each message to be sent.
  58  *
  59  * If we expect reply to our message then the sequence number in
  60  * received message MUST be the same as in original message, and
  61  * acknowledge number MUST be the same + 1.
  62  *
  63  * If we receive a message and its sequence number is not equal to the
  64  * one we are expecting then it is a new message.
  65  *
  66  * If we receive a message and its sequence number is the same as one
  67  * we are expecting but it's acknowledgement number is not equal to
  68  * the acknowledgement number in the original message + 1, then it is
  69  * a new message.
  70  *
  71  */
  72 int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
  73 {
  74         struct cn_callback_entry *__cbq;
  75         unsigned int size;
  76         struct sk_buff *skb;
  77         struct nlmsghdr *nlh;
  78         struct cn_msg *data;
  79         struct cn_dev *dev = &cdev;
  80         u32 group = 0;
  81         int found = 0;
  82
  83         if (!__group) {
  84                 spin_lock_bh(&dev->cbdev->queue_lock);
  85                 list_for_each_entry(__cbq, &dev->cbdev->queue_list,
  86                                     callback_entry) {
  87                         if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
  88                                 found = 1;
  89                                 group = __cbq->group;
  90                         }
  91                 }
  92                 spin_unlock_bh(&dev->cbdev->queue_lock);
  93
  94                 if (!found)
  95                         return -ENODEV;
  96         } else {
  97                 group = __group;
  98         }
  99
 100         size = NLMSG_SPACE(sizeof(*msg) + msg->len);
 101
 102         skb = alloc_skb(size, gfp_mask);
 103         if (!skb)
 104                 return -ENOMEM;
 105
 106         nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
 107
 108         data = NLMSG_DATA(nlh);
 109
 110         memcpy(data, msg, sizeof(*data) + msg->len);
 111
 112         NETLINK_CB(skb).dst_group = group;
 113
 114         netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
 115
 116         return 0;
 117
 118 nlmsg_failure:
 119         kfree_skb(skb);
 120         return -EINVAL;
 121 }
 122
 123 /*
 124  * Callback helper - queues work and setup destructor for given data.
 125  */
 126 static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data)
 127 {
 128         struct cn_callback_entry *__cbq;
 129         struct cn_dev *dev = &cdev;
 130         int err = -ENODEV;
 131
 132         spin_lock_bh(&dev->cbdev->queue_lock);
 133         list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
 134                 if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
 135                         if (likely(!test_bit(0, &__cbq->work.pending) &&
 136                                         __cbq->data.ddata == NULL)) {
 137                                 __cbq->data.callback_priv = msg;
 138
 139                                 __cbq->data.ddata = data;
 140                                 __cbq->data.destruct_data = destruct_data;
 141
 142                                 if (queue_work(dev->cbdev->cn_queue,
 143                                                 &__cbq->work))
 144                                         err = 0;
 145                         } else {
 146                                 struct work_struct *w;
 147                                 struct cn_callback_data *d;
 148
 149                                 w = kzalloc(sizeof(*w) + sizeof(*d), GFP_ATOMIC);
 150                                 if (w) {
 151                                         d = (struct cn_callback_data *)(w+1);
 152
 153                                         d->callback_priv = msg;
 154                                         d->callback = __cbq->data.callback;
 155                                         d->ddata = data;
 156                                         d->destruct_data = destruct_data;
 157                                         d->free = w;
 158
 159                                         INIT_LIST_HEAD(&w->entry);
 160                                         w->pending = 0;
 161                                         w->func = &cn_queue_wrapper;
 162                                         w->data = d;
 163                                         init_timer(&w->timer);
 164
 165                                         if (queue_work(dev->cbdev->cn_queue, w))
 166                                                 err = 0;
 167                                         else {
 168                                                 kfree(w);
 169                                                 err = -EINVAL;
 170                                         }
 171                                 } else
 172                                         err = -ENOMEM;
 173                         }
 174                         break;
 175                 }
 176         }
 177         spin_unlock_bh(&dev->cbdev->queue_lock);
 178
 179         return err;
 180 }
 181
 182 /*
 183  * Skb receive helper - checks skb and msg size and calls callback
 184  * helper.
 185  */
 186 static int __cn_rx_skb(struct sk_buff *skb, struct nlmsghdr *nlh)
 187 {
 188         u32 pid, uid, seq, group;
 189         struct cn_msg *msg;
 190
 191         pid = NETLINK_CREDS(skb)->pid;
 192         uid = NETLINK_CREDS(skb)->uid;
 193         seq = nlh->nlmsg_seq;
 194         group = NETLINK_CB((skb)).dst_group;
 195         msg = NLMSG_DATA(nlh);
 196
 197         return cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
 198 }
 199
 200 /*
 201  * Main netlink receiving function.
 202  *
 203  * It checks skb and netlink header sizes and calls the skb receive
 204  * helper with a shared skb.
 205  */
 206 static void cn_rx_skb(struct sk_buff *__skb)
 207 {
 208         struct nlmsghdr *nlh;
 209         u32 len;
 210         int err;
 211         struct sk_buff *skb;
 212
 213         skb = skb_get(__skb);
 214
 215         if (skb->len >= NLMSG_SPACE(0)) {
 216                 nlh = (struct nlmsghdr *)skb->data;
 217
 218                 if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 219                     skb->len < nlh->nlmsg_len ||
 220                     nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
 221                         kfree_skb(skb);
 222                         goto out;
 223                 }
 224
 225                 len = NLMSG_ALIGN(nlh->nlmsg_len);
 226                 if (len > skb->len)
 227                         len = skb->len;
 228
 229                 err = __cn_rx_skb(skb, nlh);
 230                 if (err < 0)
 231                         kfree_skb(skb);
 232         }
 233
 234 out:
 235         kfree_skb(__skb);
 236 }
 237
 238 /*
 239  * Netlink socket input callback - dequeues the skbs and calls the
 240  * main netlink receiving function.
 241  */
 242 static void cn_input(struct sock *sk, int len)
 243 {
 244         struct sk_buff *skb;
 245
 246         while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL)
 247                 cn_rx_skb(skb);
 248 }
 249
 250 /*
 251  * Notification routing.
 252  *
 253  * Gets id and checks if there are notification request for it's idx
 254  * and val.  If there are such requests notify the listeners with the
 255  * given notify event.
 256  *
 257  */
 258 static void cn_notify(struct cb_id *id, u32 notify_event)
 259 {
 260         struct cn_ctl_entry *ent;
 261
 262         down(&notify_lock);
 263         list_for_each_entry(ent, &notify_list, notify_entry) {
 264                 int i;
 265                 struct cn_notify_req *req;
 266                 struct cn_ctl_msg *ctl = ent->msg;
 267                 int idx_found, val_found;
 268
 269                 idx_found = val_found = 0;
 270
 271                 req = (struct cn_notify_req *)ctl->data;
 272                 for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
 273                         if (id->idx >= req->first &&
 274                                         id->idx < req->first + req->range) {
 275                                 idx_found = 1;
 276                                 break;
 277                         }
 278                 }
 279
 280                 for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
 281                         if (id->val >= req->first &&
 282                                         id->val < req->first + req->range) {
 283                                 val_found = 1;
 284                                 break;
 285                         }
 286                 }
 287
 288                 if (idx_found && val_found) {
 289                         struct cn_msg m = { .ack = notify_event, };
 290
 291                         memcpy(&m.id, id, sizeof(m.id));
 292                         cn_netlink_send(&m, ctl->group, GFP_KERNEL);
 293                 }
 294         }
 295         up(&notify_lock);
 296 }
 297
 298 /*
 299  * Callback add routing - adds callback with given ID and name.
 300  * If there is registered callback with the same ID it will not be added.
 301  *
 302  * May sleep.
 303  */
 304 int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
 305 {
 306         int err;
 307         struct cn_dev *dev = &cdev;
 308
 309         err = cn_queue_add_callback(dev->cbdev, name, id, callback);
 310         if (err)
 311                 return err;
 312
 313         cn_notify(id, 0);
 314
 315         return 0;
 316 }
 317
 318 /*
 319  * Callback remove routing - removes callback
 320  * with given ID.
 321  * If there is no registered callback with given
 322  * ID nothing happens.
 323  *
 324  * May sleep while waiting for reference counter to become zero.
 325  */
 326 void cn_del_callback(struct cb_id *id)
 327 {
 328         struct cn_dev *dev = &cdev;
 329
 330         cn_queue_del_callback(dev->cbdev, id);
 331         cn_notify(id, 1);
 332 }
 333
 334 /*
 335  * Checks two connector's control messages to be the same.
 336  * Returns 1 if they are the same or if the first one is corrupted.
 337  */
 338 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
 339 {
 340         int i;
 341         struct cn_notify_req *req1, *req2;
 342
 343         if (m1->idx_notify_num != m2->idx_notify_num)
 344                 return 0;
 345
 346         if (m1->val_notify_num != m2->val_notify_num)
 347                 return 0;
 348
 349         if (m1->len != m2->len)
 350                 return 0;
 351
 352         if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
 353             m1->len)
 354                 return 1;
 355
 356         req1 = (struct cn_notify_req *)m1->data;
 357         req2 = (struct cn_notify_req *)m2->data;
 358
 359         for (i = 0; i < m1->idx_notify_num; ++i) {
 360                 if (req1->first != req2->first || req1->range != req2->range)
 361                         return 0;
 362                 req1++;
 363                 req2++;
 364         }
 365
 366         for (i = 0; i < m1->val_notify_num; ++i) {
 367                 if (req1->first != req2->first || req1->range != req2->range)
 368                         return 0;
 369                 req1++;
 370                 req2++;
 371         }
 372
 373         return 1;
 374 }
 375
 376 /*
 377  * Main connector device's callback.
 378  *
 379  * Used for notification of a request's processing.
 380  */
 381 static void cn_callback(void *data)
 382 {
 383         struct cn_msg *msg = data;
 384         struct cn_ctl_msg *ctl;
 385         struct cn_ctl_entry *ent;
 386         u32 size;
 387
 388         if (msg->len < sizeof(*ctl))
 389                 return;
 390
 391         ctl = (struct cn_ctl_msg *)msg->data;
 392
 393         size = (sizeof(*ctl) + ((ctl->idx_notify_num +
 394                                  ctl->val_notify_num) *
 395                                 sizeof(struct cn_notify_req)));
 396
 397         if (msg->len != size)
 398                 return;
 399
 400         if (ctl->len + sizeof(*ctl) != msg->len)
 401                 return;
 402
 403         /*
 404          * Remove notification.
 405          */
 406         if (ctl->group == 0) {
 407                 struct cn_ctl_entry *n;
 408
 409                 down(&notify_lock);
 410                 list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
 411                         if (cn_ctl_msg_equals(ent->msg, ctl)) {
 412                                 list_del(&ent->notify_entry);
 413                                 kfree(ent);
 414                         }
 415                 }
 416                 up(&notify_lock);
 417
 418                 return;
 419         }
 420
 421         size += sizeof(*ent);
 422
 423         ent = kzalloc(size, GFP_KERNEL);
 424         if (!ent)
 425                 return;
 426
 427         ent->msg = (struct cn_ctl_msg *)(ent + 1);
 428
 429         memcpy(ent->msg, ctl, size - sizeof(*ent));
 430
 431         down(&notify_lock);
 432         list_add(&ent->notify_entry, &notify_list);
 433         up(&notify_lock);
 434 }
 435
 436 static int __init cn_init(void)
 437 {
 438         struct cn_dev *dev = &cdev;
 439         int err;
 440
 441         dev->input = cn_input;
 442         dev->id.idx = cn_idx;
 443         dev->id.val = cn_val;
 444
 445         dev->nls = netlink_kernel_create(NETLINK_CONNECTOR,
 446                                          CN_NETLINK_USERS + 0xf,
 447                                          dev->input, THIS_MODULE);
 448         if (!dev->nls)
 449                 return -EIO;
 450
 451         dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
 452         if (!dev->cbdev) {
 453                 if (dev->nls->sk_socket)
 454                         sock_release(dev->nls->sk_socket);
 455                 return -EINVAL;
 456         }
 457
 458         err = cn_add_callback(&dev->id, "connector", &cn_callback);
 459         if (err) {
 460                 cn_queue_free_dev(dev->cbdev);
 461                 if (dev->nls->sk_socket)
 462                         sock_release(dev->nls->sk_socket);
 463                 return -EINVAL;
 464         }
 465
 466         cn_already_initialized = 1;
 467
 468         return 0;
 469 }
 470
 471 static void __exit cn_fini(void)
 472 {
 473         struct cn_dev *dev = &cdev;
 474
 475         cn_already_initialized = 0;
 476
 477         cn_del_callback(&dev->id);
 478         cn_queue_free_dev(dev->cbdev);
 479         if (dev->nls->sk_socket)
 480                 sock_release(dev->nls->sk_socket);
 481 }
 482
 483 module_init(cn_init);
 484 module_exit(cn_fini);
 485
 486 EXPORT_SYMBOL_GPL(cn_add_callback);
 487 EXPORT_SYMBOL_GPL(cn_del_callback);
 488 EXPORT_SYMBOL_GPL(cn_netlink_send);