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 #include <linux/proc_fs.h>
  31 #include <linux/spinlock.h>
  32
  33 #include <net/sock.h>
  34
  35 MODULE_LICENSE("GPL");
  36 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
  37 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
  38
  39 static u32 cn_idx = CN_IDX_CONNECTOR;
  40 static u32 cn_val = CN_VAL_CONNECTOR;
  41
  42 module_param(cn_idx, uint, 0);
  43 module_param(cn_val, uint, 0);
  44 MODULE_PARM_DESC(cn_idx, "Connector's main device idx.");
  45 MODULE_PARM_DESC(cn_val, "Connector's main device val.");
  46
  47 static DEFINE_MUTEX(notify_lock);
  48 static LIST_HEAD(notify_list);
  49
  50 static struct cn_dev cdev;
  51
  52 static int cn_already_initialized;
  53
  54 /*
  55  * msg->seq and msg->ack are used to determine message genealogy.
  56  * When someone sends message it puts there locally unique sequence
  57  * and random acknowledge numbers.  Sequence number may be copied into
  58  * nlmsghdr->nlmsg_seq too.
  59  *
  60  * Sequence number is incremented with each message to be sent.
  61  *
  62  * If we expect reply to our message then the sequence number in
  63  * received message MUST be the same as in original message, and
  64  * acknowledge number MUST be the same + 1.
  65  *
  66  * If we receive a message and its sequence number is not equal to the
  67  * one we are expecting then it is a new message.
  68  *
  69  * If we receive a message and its sequence number is the same as one
  70  * we are expecting but it's acknowledgement number is not equal to
  71  * the acknowledgement number in the original message + 1, then it is
  72  * a new message.
  73  *
  74  */
  75 int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
  76 {
  77         struct cn_callback_entry *__cbq;
  78         unsigned int size;
  79         struct sk_buff *skb;
  80         struct nlmsghdr *nlh;
  81         struct cn_msg *data;
  82         struct cn_dev *dev = &cdev;
  83         u32 group = 0;
  84         int found = 0;
  85
  86         if (!__group) {
  87                 spin_lock_bh(&dev->cbdev->queue_lock);
  88                 list_for_each_entry(__cbq, &dev->cbdev->queue_list,
  89                                     callback_entry) {
  90                         if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
  91                                 found = 1;
  92                                 group = __cbq->group;
  93                                 break;
  94                         }
  95                 }
  96                 spin_unlock_bh(&dev->cbdev->queue_lock);
  97
  98                 if (!found)
  99                         return -ENODEV;
 100         } else {
 101                 group = __group;
 102         }
 103
 104         if (!netlink_has_listeners(dev->nls, group))
 105                 return -ESRCH;
 106
 107         size = NLMSG_SPACE(sizeof(*msg) + msg->len);
 108
 109         skb = alloc_skb(size, gfp_mask);
 110         if (!skb)
 111                 return -ENOMEM;
 112
 113         nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
 114
 115         data = NLMSG_DATA(nlh);
 116
 117         memcpy(data, msg, sizeof(*data) + msg->len);
 118
 119         NETLINK_CB(skb).dst_group = group;
 120
 121         return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
 122
 123 nlmsg_failure:
 124         kfree_skb(skb);
 125         return -EINVAL;
 126 }
 127 EXPORT_SYMBOL_GPL(cn_netlink_send);
 128
 129 /*
 130  * Callback helper - queues work and setup destructor for given data.
 131  */
 132 static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data)
 133 {
 134         struct cn_callback_entry *__cbq, *__new_cbq;
 135         struct cn_dev *dev = &cdev;
 136         int err = -ENODEV;
 137
 138         spin_lock_bh(&dev->cbdev->queue_lock);
 139         list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
 140                 if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
 141                         if (likely(!work_pending(&__cbq->work) &&
 142                                         __cbq->data.ddata == NULL)) {
 143                                 __cbq->data.callback_priv = msg;
 144
 145                                 __cbq->data.ddata = data;
 146                                 __cbq->data.destruct_data = destruct_data;
 147
 148                                 if (queue_work(dev->cbdev->cn_queue,
 149                                                         &__cbq->work))
 150                                         err = 0;
 151                                 else
 152                                         err = -EINVAL;
 153                         } else {
 154                                 struct cn_callback_data *d;
 155
 156                                 err = -ENOMEM;
 157                                 __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
 158                                 if (__new_cbq) {
 159                                         d = &__new_cbq->data;
 160                                         d->callback_priv = msg;
 161                                         d->callback = __cbq->data.callback;
 162                                         d->ddata = data;
 163                                         d->destruct_data = destruct_data;
 164                                         d->free = __new_cbq;
 165
 166                                         INIT_WORK(&__new_cbq->work,
 167                                                         &cn_queue_wrapper);
 168
 169                                         if (queue_work(dev->cbdev->cn_queue,
 170                                                     &__new_cbq->work))
 171                                                 err = 0;
 172                                         else {
 173                                                 kfree(__new_cbq);
 174                                                 err = -EINVAL;
 175                                         }
 176                                 }
 177                         }
 178                         break;
 179                 }
 180         }
 181         spin_unlock_bh(&dev->cbdev->queue_lock);
 182
 183         return err;
 184 }
 185
 186 /*
 187  * Main netlink receiving function.
 188  *
 189  * It checks skb, netlink header and msg sizes, and calls callback helper.
 190  */
 191 static void cn_rx_skb(struct sk_buff *__skb)
 192 {
 193         struct cn_msg *msg;
 194         struct nlmsghdr *nlh;
 195         int err;
 196         struct sk_buff *skb;
 197
 198         skb = skb_get(__skb);
 199
 200         if (skb->len >= NLMSG_SPACE(0)) {
 201                 nlh = nlmsg_hdr(skb);
 202
 203                 if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 204                     skb->len < nlh->nlmsg_len ||
 205                     nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
 206                         kfree_skb(skb);
 207                         return;
 208                 }
 209
 210                 msg = NLMSG_DATA(nlh);
 211                 err = cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
 212                 if (err < 0)
 213                         kfree_skb(skb);
 214         }
 215 }
 216
 217 /*
 218  * Notification routing.
 219  *
 220  * Gets id and checks if there are notification request for it's idx
 221  * and val.  If there are such requests notify the listeners with the
 222  * given notify event.
 223  *
 224  */
 225 static void cn_notify(struct cb_id *id, u32 notify_event)
 226 {
 227         struct cn_ctl_entry *ent;
 228
 229         mutex_lock(&notify_lock);
 230         list_for_each_entry(ent, &notify_list, notify_entry) {
 231                 int i;
 232                 struct cn_notify_req *req;
 233                 struct cn_ctl_msg *ctl = ent->msg;
 234                 int idx_found, val_found;
 235
 236                 idx_found = val_found = 0;
 237
 238                 req = (struct cn_notify_req *)ctl->data;
 239                 for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
 240                         if (id->idx >= req->first &&
 241                                         id->idx < req->first + req->range) {
 242                                 idx_found = 1;
 243                                 break;
 244                         }
 245                 }
 246
 247                 for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
 248                         if (id->val >= req->first &&
 249                                         id->val < req->first + req->range) {
 250                                 val_found = 1;
 251                                 break;
 252                         }
 253                 }
 254
 255                 if (idx_found && val_found) {
 256                         struct cn_msg m = { .ack = notify_event, };
 257
 258                         memcpy(&m.id, id, sizeof(m.id));
 259                         cn_netlink_send(&m, ctl->group, GFP_KERNEL);
 260                 }
 261         }
 262         mutex_unlock(&notify_lock);
 263 }
 264
 265 /*
 266  * Callback add routing - adds callback with given ID and name.
 267  * If there is registered callback with the same ID it will not be added.
 268  *
 269  * May sleep.
 270  */
 271 int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
 272 {
 273         int err;
 274         struct cn_dev *dev = &cdev;
 275
 276         if (!cn_already_initialized)
 277                 return -EAGAIN;
 278
 279         err = cn_queue_add_callback(dev->cbdev, name, id, callback);
 280         if (err)
 281                 return err;
 282
 283         cn_notify(id, 0);
 284
 285         return 0;
 286 }
 287 EXPORT_SYMBOL_GPL(cn_add_callback);
 288
 289 /*
 290  * Callback remove routing - removes callback
 291  * with given ID.
 292  * If there is no registered callback with given
 293  * ID nothing happens.
 294  *
 295  * May sleep while waiting for reference counter to become zero.
 296  */
 297 void cn_del_callback(struct cb_id *id)
 298 {
 299         struct cn_dev *dev = &cdev;
 300
 301         cn_queue_del_callback(dev->cbdev, id);
 302         cn_notify(id, 1);
 303 }
 304 EXPORT_SYMBOL_GPL(cn_del_callback);
 305
 306 /*
 307  * Checks two connector's control messages to be the same.
 308  * Returns 1 if they are the same or if the first one is corrupted.
 309  */
 310 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
 311 {
 312         int i;
 313         struct cn_notify_req *req1, *req2;
 314
 315         if (m1->idx_notify_num != m2->idx_notify_num)
 316                 return 0;
 317
 318         if (m1->val_notify_num != m2->val_notify_num)
 319                 return 0;
 320
 321         if (m1->len != m2->len)
 322                 return 0;
 323
 324         if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
 325             m1->len)
 326                 return 1;
 327
 328         req1 = (struct cn_notify_req *)m1->data;
 329         req2 = (struct cn_notify_req *)m2->data;
 330
 331         for (i = 0; i < m1->idx_notify_num; ++i) {
 332                 if (req1->first != req2->first || req1->range != req2->range)
 333                         return 0;
 334                 req1++;
 335                 req2++;
 336         }
 337
 338         for (i = 0; i < m1->val_notify_num; ++i) {
 339                 if (req1->first != req2->first || req1->range != req2->range)
 340                         return 0;
 341                 req1++;
 342                 req2++;
 343         }
 344
 345         return 1;
 346 }
 347
 348 /*
 349  * Main connector device's callback.
 350  *
 351  * Used for notification of a request's processing.
 352  */
 353 static void cn_callback(void *data)
 354 {
 355         struct cn_msg *msg = data;
 356         struct cn_ctl_msg *ctl;
 357         struct cn_ctl_entry *ent;
 358         u32 size;
 359
 360         if (msg->len < sizeof(*ctl))
 361                 return;
 362
 363         ctl = (struct cn_ctl_msg *)msg->data;
 364
 365         size = (sizeof(*ctl) + ((ctl->idx_notify_num +
 366                                  ctl->val_notify_num) *
 367                                 sizeof(struct cn_notify_req)));
 368
 369         if (msg->len != size)
 370                 return;
 371
 372         if (ctl->len + sizeof(*ctl) != msg->len)
 373                 return;
 374
 375         /*
 376          * Remove notification.
 377          */
 378         if (ctl->group == 0) {
 379                 struct cn_ctl_entry *n;
 380
 381                 mutex_lock(&notify_lock);
 382                 list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
 383                         if (cn_ctl_msg_equals(ent->msg, ctl)) {
 384                                 list_del(&ent->notify_entry);
 385                                 kfree(ent);
 386                         }
 387                 }
 388                 mutex_unlock(&notify_lock);
 389
 390                 return;
 391         }
 392
 393         size += sizeof(*ent);
 394
 395         ent = kzalloc(size, GFP_KERNEL);
 396         if (!ent)
 397                 return;
 398
 399         ent->msg = (struct cn_ctl_msg *)(ent + 1);
 400
 401         memcpy(ent->msg, ctl, size - sizeof(*ent));
 402
 403         mutex_lock(&notify_lock);
 404         list_add(&ent->notify_entry, &notify_list);
 405         mutex_unlock(&notify_lock);
 406 }
 407
 408 static int cn_proc_show(struct seq_file *m, void *v)
 409 {
 410         struct cn_queue_dev *dev = cdev.cbdev;
 411         struct cn_callback_entry *cbq;
 412
 413         seq_printf(m, "Name            ID\n");
 414
 415         spin_lock_bh(&dev->queue_lock);
 416
 417         list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
 418                 seq_printf(m, "%-15s %u:%u\n",
 419                            cbq->id.name,
 420                            cbq->id.id.idx,
 421                            cbq->id.id.val);
 422         }
 423
 424         spin_unlock_bh(&dev->queue_lock);
 425
 426         return 0;
 427 }
 428
 429 static int cn_proc_open(struct inode *inode, struct file *file)
 430 {
 431         return single_open(file, cn_proc_show, NULL);
 432 }
 433
 434 static const struct file_operations cn_file_ops = {
 435         .owner   = THIS_MODULE,
 436         .open    = cn_proc_open,
 437         .read    = seq_read,
 438         .llseek  = seq_lseek,
 439         .release = single_release
 440 };
 441
 442 static int __devinit cn_init(void)
 443 {
 444         struct cn_dev *dev = &cdev;
 445         int err;
 446
 447         dev->input = cn_rx_skb;
 448         dev->id.idx = cn_idx;
 449         dev->id.val = cn_val;
 450
 451         dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
 452                                          CN_NETLINK_USERS + 0xf,
 453                                          dev->input, NULL, THIS_MODULE);
 454         if (!dev->nls)
 455                 return -EIO;
 456
 457         dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
 458         if (!dev->cbdev) {
 459                 netlink_kernel_release(dev->nls);
 460                 return -EINVAL;
 461         }
 462
 463         cn_already_initialized = 1;
 464
 465         err = cn_add_callback(&dev->id, "connector", &cn_callback);
 466         if (err) {
 467                 cn_already_initialized = 0;
 468                 cn_queue_free_dev(dev->cbdev);
 469                 netlink_kernel_release(dev->nls);
 470                 return -EINVAL;
 471         }
 472
 473         proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
 474
 475         return 0;
 476 }
 477
 478 static void __devexit cn_fini(void)
 479 {
 480         struct cn_dev *dev = &cdev;
 481
 482         cn_already_initialized = 0;
 483
 484         proc_net_remove(&init_net, "connector");
 485
 486         cn_del_callback(&dev->id);
 487         cn_queue_free_dev(dev->cbdev);
 488         netlink_kernel_release(dev->nls);
 489 }
 490
 491 subsys_initcall(cn_init);
 492 module_exit(cn_fini);