drivers/connector/connector.c

   1 /*
   2  *      connector.c
   3  *
   4  * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
   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 <zbr@ioremap.net>");
  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 sk_buff *skb)
 133 {
 134         struct cn_callback_entry *__cbq, *__new_cbq;
 135         struct cn_dev *dev = &cdev;
 136         struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb));
 137         int err = -ENODEV;
 138
 139         spin_lock_bh(&dev->cbdev->queue_lock);
 140         list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
 141                 if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
 142                         if (likely(!work_pending(&__cbq->work) &&
 143                                         __cbq->data.skb == NULL)) {
 144                                 __cbq->data.skb = skb;
 145
 146                                 if (queue_cn_work(__cbq, &__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->skb = skb;
 158                                         d->callback = __cbq->data.callback;
 159                                         d->free = __new_cbq;
 160
 161                                         __new_cbq->pdev = __cbq->pdev;
 162
 163                                         INIT_WORK(&__new_cbq->work,
 164                                                         &cn_queue_wrapper);
 165
 166                                         if (queue_cn_work(__new_cbq,
 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  * Main netlink receiving function.
 185  *
 186  * It checks skb, netlink header and msg sizes, and calls callback helper.
 187  */
 188 static void cn_rx_skb(struct sk_buff *__skb)
 189 {
 190         struct nlmsghdr *nlh;
 191         int err;
 192         struct sk_buff *skb;
 193
 194         skb = skb_get(__skb);
 195
 196         if (skb->len >= NLMSG_SPACE(0)) {
 197                 nlh = nlmsg_hdr(skb);
 198
 199                 if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 200                     skb->len < nlh->nlmsg_len ||
 201                     nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
 202                         kfree_skb(skb);
 203                         return;
 204                 }
 205
 206                 err = cn_call_callback(skb);
 207                 if (err < 0)
 208                         kfree_skb(skb);
 209         }
 210 }
 211
 212 /*
 213  * Notification routing.
 214  *
 215  * Gets id and checks if there are notification request for it's idx
 216  * and val.  If there are such requests notify the listeners with the
 217  * given notify event.
 218  *
 219  */
 220 static void cn_notify(struct cb_id *id, u32 notify_event)
 221 {
 222         struct cn_ctl_entry *ent;
 223
 224         mutex_lock(&notify_lock);
 225         list_for_each_entry(ent, &notify_list, notify_entry) {
 226                 int i;
 227                 struct cn_notify_req *req;
 228                 struct cn_ctl_msg *ctl = ent->msg;
 229                 int idx_found, val_found;
 230
 231                 idx_found = val_found = 0;
 232
 233                 req = (struct cn_notify_req *)ctl->data;
 234                 for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
 235                         if (id->idx >= req->first &&
 236                                         id->idx < req->first + req->range) {
 237                                 idx_found = 1;
 238                                 break;
 239                         }
 240                 }
 241
 242                 for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
 243                         if (id->val >= req->first &&
 244                                         id->val < req->first + req->range) {
 245                                 val_found = 1;
 246                                 break;
 247                         }
 248                 }
 249
 250                 if (idx_found && val_found) {
 251                         struct cn_msg m = { .ack = notify_event, };
 252
 253                         memcpy(&m.id, id, sizeof(m.id));
 254                         cn_netlink_send(&m, ctl->group, GFP_KERNEL);
 255                 }
 256         }
 257         mutex_unlock(&notify_lock);
 258 }
 259
 260 /*
 261  * Callback add routing - adds callback with given ID and name.
 262  * If there is registered callback with the same ID it will not be added.
 263  *
 264  * May sleep.
 265  */
 266 int cn_add_callback(struct cb_id *id, char *name,
 267                     void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
 268 {
 269         int err;
 270         struct cn_dev *dev = &cdev;
 271
 272         if (!cn_already_initialized)
 273                 return -EAGAIN;
 274
 275         err = cn_queue_add_callback(dev->cbdev, name, id, callback);
 276         if (err)
 277                 return err;
 278
 279         cn_notify(id, 0);
 280
 281         return 0;
 282 }
 283 EXPORT_SYMBOL_GPL(cn_add_callback);
 284
 285 /*
 286  * Callback remove routing - removes callback
 287  * with given ID.
 288  * If there is no registered callback with given
 289  * ID nothing happens.
 290  *
 291  * May sleep while waiting for reference counter to become zero.
 292  */
 293 void cn_del_callback(struct cb_id *id)
 294 {
 295         struct cn_dev *dev = &cdev;
 296
 297         cn_queue_del_callback(dev->cbdev, id);
 298         cn_notify(id, 1);
 299 }
 300 EXPORT_SYMBOL_GPL(cn_del_callback);
 301
 302 /*
 303  * Checks two connector's control messages to be the same.
 304  * Returns 1 if they are the same or if the first one is corrupted.
 305  */
 306 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
 307 {
 308         int i;
 309         struct cn_notify_req *req1, *req2;
 310
 311         if (m1->idx_notify_num != m2->idx_notify_num)
 312                 return 0;
 313
 314         if (m1->val_notify_num != m2->val_notify_num)
 315                 return 0;
 316
 317         if (m1->len != m2->len)
 318                 return 0;
 319
 320         if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
 321             m1->len)
 322                 return 1;
 323
 324         req1 = (struct cn_notify_req *)m1->data;
 325         req2 = (struct cn_notify_req *)m2->data;
 326
 327         for (i = 0; i < m1->idx_notify_num; ++i) {
 328                 if (req1->first != req2->first || req1->range != req2->range)
 329                         return 0;
 330                 req1++;
 331                 req2++;
 332         }
 333
 334         for (i = 0; i < m1->val_notify_num; ++i) {
 335                 if (req1->first != req2->first || req1->range != req2->range)
 336                         return 0;
 337                 req1++;
 338                 req2++;
 339         }
 340
 341         return 1;
 342 }
 343
 344 /*
 345  * Main connector device's callback.
 346  *
 347  * Used for notification of a request's processing.
 348  */
 349 static void cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
 350 {
 351         struct cn_ctl_msg *ctl;
 352         struct cn_ctl_entry *ent;
 353         u32 size;
 354
 355         if (msg->len < sizeof(*ctl))
 356                 return;
 357
 358         ctl = (struct cn_ctl_msg *)msg->data;
 359
 360         size = (sizeof(*ctl) + ((ctl->idx_notify_num +
 361                                  ctl->val_notify_num) *
 362                                 sizeof(struct cn_notify_req)));
 363
 364         if (msg->len != size)
 365                 return;
 366
 367         if (ctl->len + sizeof(*ctl) != msg->len)
 368                 return;
 369
 370         /*
 371          * Remove notification.
 372          */
 373         if (ctl->group == 0) {
 374                 struct cn_ctl_entry *n;
 375
 376                 mutex_lock(&notify_lock);
 377                 list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
 378                         if (cn_ctl_msg_equals(ent->msg, ctl)) {
 379                                 list_del(&ent->notify_entry);
 380                                 kfree(ent);
 381                         }
 382                 }
 383                 mutex_unlock(&notify_lock);
 384
 385                 return;
 386         }
 387
 388         size += sizeof(*ent);
 389
 390         ent = kzalloc(size, GFP_KERNEL);
 391         if (!ent)
 392                 return;
 393
 394         ent->msg = (struct cn_ctl_msg *)(ent + 1);
 395
 396         memcpy(ent->msg, ctl, size - sizeof(*ent));
 397
 398         mutex_lock(&notify_lock);
 399         list_add(&ent->notify_entry, &notify_list);
 400         mutex_unlock(&notify_lock);
 401 }
 402
 403 static int cn_proc_show(struct seq_file *m, void *v)
 404 {
 405         struct cn_queue_dev *dev = cdev.cbdev;
 406         struct cn_callback_entry *cbq;
 407
 408         seq_printf(m, "Name            ID\n");
 409
 410         spin_lock_bh(&dev->queue_lock);
 411
 412         list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
 413                 seq_printf(m, "%-15s %u:%u\n",
 414                            cbq->id.name,
 415                            cbq->id.id.idx,
 416                            cbq->id.id.val);
 417         }
 418
 419         spin_unlock_bh(&dev->queue_lock);
 420
 421         return 0;
 422 }
 423
 424 static int cn_proc_open(struct inode *inode, struct file *file)
 425 {
 426         return single_open(file, cn_proc_show, NULL);
 427 }
 428
 429 static const struct file_operations cn_file_ops = {
 430         .owner   = THIS_MODULE,
 431         .open    = cn_proc_open,
 432         .read    = seq_read,
 433         .llseek  = seq_lseek,
 434         .release = single_release
 435 };
 436
 437 static int __devinit cn_init(void)
 438 {
 439         struct cn_dev *dev = &cdev;
 440         int err;
 441
 442         dev->input = cn_rx_skb;
 443         dev->id.idx = cn_idx;
 444         dev->id.val = cn_val;
 445
 446         dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
 447                                          CN_NETLINK_USERS + 0xf,
 448                                          dev->input, NULL, THIS_MODULE);
 449         if (!dev->nls)
 450                 return -EIO;
 451
 452         dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
 453         if (!dev->cbdev) {
 454                 netlink_kernel_release(dev->nls);
 455                 return -EINVAL;
 456         }
 457
 458         cn_already_initialized = 1;
 459
 460         err = cn_add_callback(&dev->id, "connector", &cn_callback);
 461         if (err) {
 462                 cn_already_initialized = 0;
 463                 cn_queue_free_dev(dev->cbdev);
 464                 netlink_kernel_release(dev->nls);
 465                 return -EINVAL;
 466         }
 467
 468         proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
 469
 470         return 0;
 471 }
 472
 473 static void __devexit cn_fini(void)
 474 {
 475         struct cn_dev *dev = &cdev;
 476
 477         cn_already_initialized = 0;
 478
 479         proc_net_remove(&init_net, "connector");
 480
 481         cn_del_callback(&dev->id);
 482         cn_queue_free_dev(dev->cbdev);
 483         netlink_kernel_release(dev->nls);
 484 }
 485
 486 subsys_initcall(cn_init);
 487 module_exit(cn_fini);