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_cn_work(__cbq, &__cbq->work))
 149                                         err = 0;
 150                                 else
 151                                         err = -EINVAL;
 152                         } else {
 153                                 struct cn_callback_data *d;
 154
 155                                 err = -ENOMEM;
 156                                 __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
 157                                 if (__new_cbq) {
 158                                         d = &__new_cbq->data;
 159                                         d->callback_priv = msg;
 160                                         d->callback = __cbq->data.callback;
 161                                         d->ddata = data;
 162                                         d->destruct_data = destruct_data;
 163                                         d->free = __new_cbq;
 164
 165                                         __new_cbq->pdev = __cbq->pdev;
 166
 167                                         INIT_WORK(&__new_cbq->work,
 168                                                         &cn_queue_wrapper);
 169
 170                                         if (queue_cn_work(__new_cbq,
 171                                                     &__new_cbq->work))
 172                                                 err = 0;
 173                                         else {
 174                                                 kfree(__new_cbq);
 175                                                 err = -EINVAL;
 176                                         }
 177                                 }
 178                         }
 179                         break;
 180                 }
 181         }
 182         spin_unlock_bh(&dev->cbdev->queue_lock);
 183
 184         return err;
 185 }
 186
 187 /*
 188  * Main netlink receiving function.
 189  *
 190  * It checks skb, netlink header and msg sizes, and calls callback helper.
 191  */
 192 static void cn_rx_skb(struct sk_buff *__skb)
 193 {
 194         struct cn_msg *msg;
 195         struct nlmsghdr *nlh;
 196         int err;
 197         struct sk_buff *skb;
 198
 199         skb = skb_get(__skb);
 200
 201         if (skb->len >= NLMSG_SPACE(0)) {
 202                 nlh = nlmsg_hdr(skb);
 203
 204                 if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 205                     skb->len < nlh->nlmsg_len ||
 206                     nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
 207                         kfree_skb(skb);
 208                         return;
 209                 }
 210
 211                 msg = NLMSG_DATA(nlh);
 212                 err = cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
 213                 if (err < 0)
 214                         kfree_skb(skb);
 215         }
 216 }
 217
 218 /*
 219  * Notification routing.
 220  *
 221  * Gets id and checks if there are notification request for it's idx
 222  * and val.  If there are such requests notify the listeners with the
 223  * given notify event.
 224  *
 225  */
 226 static void cn_notify(struct cb_id *id, u32 notify_event)
 227 {
 228         struct cn_ctl_entry *ent;
 229
 230         mutex_lock(&notify_lock);
 231         list_for_each_entry(ent, &notify_list, notify_entry) {
 232                 int i;
 233                 struct cn_notify_req *req;
 234                 struct cn_ctl_msg *ctl = ent->msg;
 235                 int idx_found, val_found;
 236
 237                 idx_found = val_found = 0;
 238
 239                 req = (struct cn_notify_req *)ctl->data;
 240                 for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
 241                         if (id->idx >= req->first &&
 242                                         id->idx < req->first + req->range) {
 243                                 idx_found = 1;
 244                                 break;
 245                         }
 246                 }
 247
 248                 for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
 249                         if (id->val >= req->first &&
 250                                         id->val < req->first + req->range) {
 251                                 val_found = 1;
 252                                 break;
 253                         }
 254                 }
 255
 256                 if (idx_found && val_found) {
 257                         struct cn_msg m = { .ack = notify_event, };
 258
 259                         memcpy(&m.id, id, sizeof(m.id));
 260                         cn_netlink_send(&m, ctl->group, GFP_KERNEL);
 261                 }
 262         }
 263         mutex_unlock(&notify_lock);
 264 }
 265
 266 /*
 267  * Callback add routing - adds callback with given ID and name.
 268  * If there is registered callback with the same ID it will not be added.
 269  *
 270  * May sleep.
 271  */
 272 int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
 273 {
 274         int err;
 275         struct cn_dev *dev = &cdev;
 276
 277         if (!cn_already_initialized)
 278                 return -EAGAIN;
 279
 280         err = cn_queue_add_callback(dev->cbdev, name, id, callback);
 281         if (err)
 282                 return err;
 283
 284         cn_notify(id, 0);
 285
 286         return 0;
 287 }
 288 EXPORT_SYMBOL_GPL(cn_add_callback);
 289
 290 /*
 291  * Callback remove routing - removes callback
 292  * with given ID.
 293  * If there is no registered callback with given
 294  * ID nothing happens.
 295  *
 296  * May sleep while waiting for reference counter to become zero.
 297  */
 298 void cn_del_callback(struct cb_id *id)
 299 {
 300         struct cn_dev *dev = &cdev;
 301
 302         cn_queue_del_callback(dev->cbdev, id);
 303         cn_notify(id, 1);
 304 }
 305 EXPORT_SYMBOL_GPL(cn_del_callback);
 306
 307 /*
 308  * Checks two connector's control messages to be the same.
 309  * Returns 1 if they are the same or if the first one is corrupted.
 310  */
 311 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
 312 {
 313         int i;
 314         struct cn_notify_req *req1, *req2;
 315
 316         if (m1->idx_notify_num != m2->idx_notify_num)
 317                 return 0;
 318
 319         if (m1->val_notify_num != m2->val_notify_num)
 320                 return 0;
 321
 322         if (m1->len != m2->len)
 323                 return 0;
 324
 325         if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
 326             m1->len)
 327                 return 1;
 328
 329         req1 = (struct cn_notify_req *)m1->data;
 330         req2 = (struct cn_notify_req *)m2->data;
 331
 332         for (i = 0; i < m1->idx_notify_num; ++i) {
 333                 if (req1->first != req2->first || req1->range != req2->range)
 334                         return 0;
 335                 req1++;
 336                 req2++;
 337         }
 338
 339         for (i = 0; i < m1->val_notify_num; ++i) {
 340                 if (req1->first != req2->first || req1->range != req2->range)
 341                         return 0;
 342                 req1++;
 343                 req2++;
 344         }
 345
 346         return 1;
 347 }
 348
 349 /*
 350  * Main connector device's callback.
 351  *
 352  * Used for notification of a request's processing.
 353  */
 354 static void cn_callback(void *data)
 355 {
 356         struct cn_msg *msg = data;
 357         struct cn_ctl_msg *ctl;
 358         struct cn_ctl_entry *ent;
 359         u32 size;
 360
 361         if (msg->len < sizeof(*ctl))
 362                 return;
 363
 364         ctl = (struct cn_ctl_msg *)msg->data;
 365
 366         size = (sizeof(*ctl) + ((ctl->idx_notify_num +
 367                                  ctl->val_notify_num) *
 368                                 sizeof(struct cn_notify_req)));
 369
 370         if (msg->len != size)
 371                 return;
 372
 373         if (ctl->len + sizeof(*ctl) != msg->len)
 374                 return;
 375
 376         /*
 377          * Remove notification.
 378          */
 379         if (ctl->group == 0) {
 380                 struct cn_ctl_entry *n;
 381
 382                 mutex_lock(&notify_lock);
 383                 list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
 384                         if (cn_ctl_msg_equals(ent->msg, ctl)) {
 385                                 list_del(&ent->notify_entry);
 386                                 kfree(ent);
 387                         }
 388                 }
 389                 mutex_unlock(&notify_lock);
 390
 391                 return;
 392         }
 393
 394         size += sizeof(*ent);
 395
 396         ent = kzalloc(size, GFP_KERNEL);
 397         if (!ent)
 398                 return;
 399
 400         ent->msg = (struct cn_ctl_msg *)(ent + 1);
 401
 402         memcpy(ent->msg, ctl, size - sizeof(*ent));
 403
 404         mutex_lock(&notify_lock);
 405         list_add(&ent->notify_entry, &notify_list);
 406         mutex_unlock(&notify_lock);
 407 }
 408
 409 static int cn_proc_show(struct seq_file *m, void *v)
 410 {
 411         struct cn_queue_dev *dev = cdev.cbdev;
 412         struct cn_callback_entry *cbq;
 413
 414         seq_printf(m, "Name            ID\n");
 415
 416         spin_lock_bh(&dev->queue_lock);
 417
 418         list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
 419                 seq_printf(m, "%-15s %u:%u\n",
 420                            cbq->id.name,
 421                            cbq->id.id.idx,
 422                            cbq->id.id.val);
 423         }
 424
 425         spin_unlock_bh(&dev->queue_lock);
 426
 427         return 0;
 428 }
 429
 430 static int cn_proc_open(struct inode *inode, struct file *file)
 431 {
 432         return single_open(file, cn_proc_show, NULL);
 433 }
 434
 435 static const struct file_operations cn_file_ops = {
 436         .owner   = THIS_MODULE,
 437         .open    = cn_proc_open,
 438         .read    = seq_read,
 439         .llseek  = seq_lseek,
 440         .release = single_release
 441 };
 442
 443 static int __devinit cn_init(void)
 444 {
 445         struct cn_dev *dev = &cdev;
 446         int err;
 447
 448         dev->input = cn_rx_skb;
 449         dev->id.idx = cn_idx;
 450         dev->id.val = cn_val;
 451
 452         dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
 453                                          CN_NETLINK_USERS + 0xf,
 454                                          dev->input, NULL, THIS_MODULE);
 455         if (!dev->nls)
 456                 return -EIO;
 457
 458         dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
 459         if (!dev->cbdev) {
 460                 netlink_kernel_release(dev->nls);
 461                 return -EINVAL;
 462         }
 463
 464         cn_already_initialized = 1;
 465
 466         err = cn_add_callback(&dev->id, "connector", &cn_callback);
 467         if (err) {
 468                 cn_already_initialized = 0;
 469                 cn_queue_free_dev(dev->cbdev);
 470                 netlink_kernel_release(dev->nls);
 471                 return -EINVAL;
 472         }
 473
 474         proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
 475
 476         return 0;
 477 }
 478
 479 static void __devexit cn_fini(void)
 480 {
 481         struct cn_dev *dev = &cdev;
 482
 483         cn_already_initialized = 0;
 484
 485         proc_net_remove(&init_net, "connector");
 486
 487         cn_del_callback(&dev->id);
 488         cn_queue_free_dev(dev->cbdev);
 489         netlink_kernel_release(dev->nls);
 490 }
 491
 492 subsys_initcall(cn_init);
 493 module_exit(cn_fini);