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(¬ify_lock); 263 list_for_each_entry(ent, ¬ify_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(¬ify_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(¬ify_lock); 410 list_for_each_entry_safe(ent, n, ¬ify_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(¬ify_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(¬ify_lock); 432 list_add(&ent->notify_entry, ¬ify_list); 433 up(¬ify_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); 489