xref: /openbmc/linux/net/caif/caif_socket.c (revision e23feb16)
1 /*
2  * Copyright (C) ST-Ericsson AB 2010
3  * Author:	Sjur Brendeland
4  * License terms: GNU General Public License (GPL) version 2
5  */
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
8 
9 #include <linux/fs.h>
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/spinlock.h>
14 #include <linux/mutex.h>
15 #include <linux/list.h>
16 #include <linux/wait.h>
17 #include <linux/poll.h>
18 #include <linux/tcp.h>
19 #include <linux/uaccess.h>
20 #include <linux/debugfs.h>
21 #include <linux/caif/caif_socket.h>
22 #include <linux/pkt_sched.h>
23 #include <net/sock.h>
24 #include <net/tcp_states.h>
25 #include <net/caif/caif_layer.h>
26 #include <net/caif/caif_dev.h>
27 #include <net/caif/cfpkt.h>
28 
29 MODULE_LICENSE("GPL");
30 MODULE_ALIAS_NETPROTO(AF_CAIF);
31 
32 /*
33  * CAIF state is re-using the TCP socket states.
34  * caif_states stored in sk_state reflect the state as reported by
35  * the CAIF stack, while sk_socket->state is the state of the socket.
36  */
37 enum caif_states {
38 	CAIF_CONNECTED		= TCP_ESTABLISHED,
39 	CAIF_CONNECTING	= TCP_SYN_SENT,
40 	CAIF_DISCONNECTED	= TCP_CLOSE
41 };
42 
43 #define TX_FLOW_ON_BIT	1
44 #define RX_FLOW_ON_BIT	2
45 
46 struct caifsock {
47 	struct sock sk; /* must be first member */
48 	struct cflayer layer;
49 	u32 flow_state;
50 	struct caif_connect_request conn_req;
51 	struct mutex readlock;
52 	struct dentry *debugfs_socket_dir;
53 	int headroom, tailroom, maxframe;
54 };
55 
56 static int rx_flow_is_on(struct caifsock *cf_sk)
57 {
58 	return test_bit(RX_FLOW_ON_BIT,
59 			(void *) &cf_sk->flow_state);
60 }
61 
62 static int tx_flow_is_on(struct caifsock *cf_sk)
63 {
64 	return test_bit(TX_FLOW_ON_BIT,
65 			(void *) &cf_sk->flow_state);
66 }
67 
68 static void set_rx_flow_off(struct caifsock *cf_sk)
69 {
70 	 clear_bit(RX_FLOW_ON_BIT,
71 		 (void *) &cf_sk->flow_state);
72 }
73 
74 static void set_rx_flow_on(struct caifsock *cf_sk)
75 {
76 	 set_bit(RX_FLOW_ON_BIT,
77 			(void *) &cf_sk->flow_state);
78 }
79 
80 static void set_tx_flow_off(struct caifsock *cf_sk)
81 {
82 	 clear_bit(TX_FLOW_ON_BIT,
83 		(void *) &cf_sk->flow_state);
84 }
85 
86 static void set_tx_flow_on(struct caifsock *cf_sk)
87 {
88 	 set_bit(TX_FLOW_ON_BIT,
89 		(void *) &cf_sk->flow_state);
90 }
91 
92 static void caif_read_lock(struct sock *sk)
93 {
94 	struct caifsock *cf_sk;
95 	cf_sk = container_of(sk, struct caifsock, sk);
96 	mutex_lock(&cf_sk->readlock);
97 }
98 
99 static void caif_read_unlock(struct sock *sk)
100 {
101 	struct caifsock *cf_sk;
102 	cf_sk = container_of(sk, struct caifsock, sk);
103 	mutex_unlock(&cf_sk->readlock);
104 }
105 
106 static int sk_rcvbuf_lowwater(struct caifsock *cf_sk)
107 {
108 	/* A quarter of full buffer is used a low water mark */
109 	return cf_sk->sk.sk_rcvbuf / 4;
110 }
111 
112 static void caif_flow_ctrl(struct sock *sk, int mode)
113 {
114 	struct caifsock *cf_sk;
115 	cf_sk = container_of(sk, struct caifsock, sk);
116 	if (cf_sk->layer.dn && cf_sk->layer.dn->modemcmd)
117 		cf_sk->layer.dn->modemcmd(cf_sk->layer.dn, mode);
118 }
119 
120 /*
121  * Copied from sock.c:sock_queue_rcv_skb(), but changed so packets are
122  * not dropped, but CAIF is sending flow off instead.
123  */
124 static int caif_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
125 {
126 	int err;
127 	int skb_len;
128 	unsigned long flags;
129 	struct sk_buff_head *list = &sk->sk_receive_queue;
130 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
131 
132 	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
133 		(unsigned int)sk->sk_rcvbuf && rx_flow_is_on(cf_sk)) {
134 		net_dbg_ratelimited("sending flow OFF (queue len = %d %d)\n",
135 				    atomic_read(&cf_sk->sk.sk_rmem_alloc),
136 				    sk_rcvbuf_lowwater(cf_sk));
137 		set_rx_flow_off(cf_sk);
138 		caif_flow_ctrl(sk, CAIF_MODEMCMD_FLOW_OFF_REQ);
139 	}
140 
141 	err = sk_filter(sk, skb);
142 	if (err)
143 		return err;
144 	if (!sk_rmem_schedule(sk, skb, skb->truesize) && rx_flow_is_on(cf_sk)) {
145 		set_rx_flow_off(cf_sk);
146 		net_dbg_ratelimited("sending flow OFF due to rmem_schedule\n");
147 		caif_flow_ctrl(sk, CAIF_MODEMCMD_FLOW_OFF_REQ);
148 	}
149 	skb->dev = NULL;
150 	skb_set_owner_r(skb, sk);
151 	/* Cache the SKB length before we tack it onto the receive
152 	 * queue. Once it is added it no longer belongs to us and
153 	 * may be freed by other threads of control pulling packets
154 	 * from the queue.
155 	 */
156 	skb_len = skb->len;
157 	spin_lock_irqsave(&list->lock, flags);
158 	if (!sock_flag(sk, SOCK_DEAD))
159 		__skb_queue_tail(list, skb);
160 	spin_unlock_irqrestore(&list->lock, flags);
161 
162 	if (!sock_flag(sk, SOCK_DEAD))
163 		sk->sk_data_ready(sk, skb_len);
164 	else
165 		kfree_skb(skb);
166 	return 0;
167 }
168 
169 /* Packet Receive Callback function called from CAIF Stack */
170 static int caif_sktrecv_cb(struct cflayer *layr, struct cfpkt *pkt)
171 {
172 	struct caifsock *cf_sk;
173 	struct sk_buff *skb;
174 
175 	cf_sk = container_of(layr, struct caifsock, layer);
176 	skb = cfpkt_tonative(pkt);
177 
178 	if (unlikely(cf_sk->sk.sk_state != CAIF_CONNECTED)) {
179 		kfree_skb(skb);
180 		return 0;
181 	}
182 	caif_queue_rcv_skb(&cf_sk->sk, skb);
183 	return 0;
184 }
185 
186 static void cfsk_hold(struct cflayer *layr)
187 {
188 	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
189 	sock_hold(&cf_sk->sk);
190 }
191 
192 static void cfsk_put(struct cflayer *layr)
193 {
194 	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
195 	sock_put(&cf_sk->sk);
196 }
197 
198 /* Packet Control Callback function called from CAIF */
199 static void caif_ctrl_cb(struct cflayer *layr,
200 			 enum caif_ctrlcmd flow,
201 			 int phyid)
202 {
203 	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
204 	switch (flow) {
205 	case CAIF_CTRLCMD_FLOW_ON_IND:
206 		/* OK from modem to start sending again */
207 		set_tx_flow_on(cf_sk);
208 		cf_sk->sk.sk_state_change(&cf_sk->sk);
209 		break;
210 
211 	case CAIF_CTRLCMD_FLOW_OFF_IND:
212 		/* Modem asks us to shut up */
213 		set_tx_flow_off(cf_sk);
214 		cf_sk->sk.sk_state_change(&cf_sk->sk);
215 		break;
216 
217 	case CAIF_CTRLCMD_INIT_RSP:
218 		/* We're now connected */
219 		caif_client_register_refcnt(&cf_sk->layer,
220 						cfsk_hold, cfsk_put);
221 		cf_sk->sk.sk_state = CAIF_CONNECTED;
222 		set_tx_flow_on(cf_sk);
223 		cf_sk->sk.sk_shutdown = 0;
224 		cf_sk->sk.sk_state_change(&cf_sk->sk);
225 		break;
226 
227 	case CAIF_CTRLCMD_DEINIT_RSP:
228 		/* We're now disconnected */
229 		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
230 		cf_sk->sk.sk_state_change(&cf_sk->sk);
231 		break;
232 
233 	case CAIF_CTRLCMD_INIT_FAIL_RSP:
234 		/* Connect request failed */
235 		cf_sk->sk.sk_err = ECONNREFUSED;
236 		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
237 		cf_sk->sk.sk_shutdown = SHUTDOWN_MASK;
238 		/*
239 		 * Socket "standards" seems to require POLLOUT to
240 		 * be set at connect failure.
241 		 */
242 		set_tx_flow_on(cf_sk);
243 		cf_sk->sk.sk_state_change(&cf_sk->sk);
244 		break;
245 
246 	case CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND:
247 		/* Modem has closed this connection, or device is down. */
248 		cf_sk->sk.sk_shutdown = SHUTDOWN_MASK;
249 		cf_sk->sk.sk_err = ECONNRESET;
250 		set_rx_flow_on(cf_sk);
251 		cf_sk->sk.sk_error_report(&cf_sk->sk);
252 		break;
253 
254 	default:
255 		pr_debug("Unexpected flow command %d\n", flow);
256 	}
257 }
258 
259 static void caif_check_flow_release(struct sock *sk)
260 {
261 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
262 
263 	if (rx_flow_is_on(cf_sk))
264 		return;
265 
266 	if (atomic_read(&sk->sk_rmem_alloc) <= sk_rcvbuf_lowwater(cf_sk)) {
267 			set_rx_flow_on(cf_sk);
268 			caif_flow_ctrl(sk, CAIF_MODEMCMD_FLOW_ON_REQ);
269 	}
270 }
271 
272 /*
273  * Copied from unix_dgram_recvmsg, but removed credit checks,
274  * changed locking, address handling and added MSG_TRUNC.
275  */
276 static int caif_seqpkt_recvmsg(struct kiocb *iocb, struct socket *sock,
277 			       struct msghdr *m, size_t len, int flags)
278 
279 {
280 	struct sock *sk = sock->sk;
281 	struct sk_buff *skb;
282 	int ret;
283 	int copylen;
284 
285 	ret = -EOPNOTSUPP;
286 	if (m->msg_flags&MSG_OOB)
287 		goto read_error;
288 
289 	m->msg_namelen = 0;
290 
291 	skb = skb_recv_datagram(sk, flags, 0 , &ret);
292 	if (!skb)
293 		goto read_error;
294 	copylen = skb->len;
295 	if (len < copylen) {
296 		m->msg_flags |= MSG_TRUNC;
297 		copylen = len;
298 	}
299 
300 	ret = skb_copy_datagram_iovec(skb, 0, m->msg_iov, copylen);
301 	if (ret)
302 		goto out_free;
303 
304 	ret = (flags & MSG_TRUNC) ? skb->len : copylen;
305 out_free:
306 	skb_free_datagram(sk, skb);
307 	caif_check_flow_release(sk);
308 	return ret;
309 
310 read_error:
311 	return ret;
312 }
313 
314 
315 /* Copied from unix_stream_wait_data, identical except for lock call. */
316 static long caif_stream_data_wait(struct sock *sk, long timeo)
317 {
318 	DEFINE_WAIT(wait);
319 	lock_sock(sk);
320 
321 	for (;;) {
322 		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
323 
324 		if (!skb_queue_empty(&sk->sk_receive_queue) ||
325 			sk->sk_err ||
326 			sk->sk_state != CAIF_CONNECTED ||
327 			sock_flag(sk, SOCK_DEAD) ||
328 			(sk->sk_shutdown & RCV_SHUTDOWN) ||
329 			signal_pending(current) ||
330 			!timeo)
331 			break;
332 
333 		set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
334 		release_sock(sk);
335 		timeo = schedule_timeout(timeo);
336 		lock_sock(sk);
337 		clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
338 	}
339 
340 	finish_wait(sk_sleep(sk), &wait);
341 	release_sock(sk);
342 	return timeo;
343 }
344 
345 
346 /*
347  * Copied from unix_stream_recvmsg, but removed credit checks,
348  * changed locking calls, changed address handling.
349  */
350 static int caif_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
351 			       struct msghdr *msg, size_t size,
352 			       int flags)
353 {
354 	struct sock *sk = sock->sk;
355 	int copied = 0;
356 	int target;
357 	int err = 0;
358 	long timeo;
359 
360 	err = -EOPNOTSUPP;
361 	if (flags&MSG_OOB)
362 		goto out;
363 
364 	msg->msg_namelen = 0;
365 
366 	/*
367 	 * Lock the socket to prevent queue disordering
368 	 * while sleeps in memcpy_tomsg
369 	 */
370 	err = -EAGAIN;
371 	if (sk->sk_state == CAIF_CONNECTING)
372 		goto out;
373 
374 	caif_read_lock(sk);
375 	target = sock_rcvlowat(sk, flags&MSG_WAITALL, size);
376 	timeo = sock_rcvtimeo(sk, flags&MSG_DONTWAIT);
377 
378 	do {
379 		int chunk;
380 		struct sk_buff *skb;
381 
382 		lock_sock(sk);
383 		skb = skb_dequeue(&sk->sk_receive_queue);
384 		caif_check_flow_release(sk);
385 
386 		if (skb == NULL) {
387 			if (copied >= target)
388 				goto unlock;
389 			/*
390 			 *	POSIX 1003.1g mandates this order.
391 			 */
392 			err = sock_error(sk);
393 			if (err)
394 				goto unlock;
395 			err = -ECONNRESET;
396 			if (sk->sk_shutdown & RCV_SHUTDOWN)
397 				goto unlock;
398 
399 			err = -EPIPE;
400 			if (sk->sk_state != CAIF_CONNECTED)
401 				goto unlock;
402 			if (sock_flag(sk, SOCK_DEAD))
403 				goto unlock;
404 
405 			release_sock(sk);
406 
407 			err = -EAGAIN;
408 			if (!timeo)
409 				break;
410 
411 			caif_read_unlock(sk);
412 
413 			timeo = caif_stream_data_wait(sk, timeo);
414 
415 			if (signal_pending(current)) {
416 				err = sock_intr_errno(timeo);
417 				goto out;
418 			}
419 			caif_read_lock(sk);
420 			continue;
421 unlock:
422 			release_sock(sk);
423 			break;
424 		}
425 		release_sock(sk);
426 		chunk = min_t(unsigned int, skb->len, size);
427 		if (memcpy_toiovec(msg->msg_iov, skb->data, chunk)) {
428 			skb_queue_head(&sk->sk_receive_queue, skb);
429 			if (copied == 0)
430 				copied = -EFAULT;
431 			break;
432 		}
433 		copied += chunk;
434 		size -= chunk;
435 
436 		/* Mark read part of skb as used */
437 		if (!(flags & MSG_PEEK)) {
438 			skb_pull(skb, chunk);
439 
440 			/* put the skb back if we didn't use it up. */
441 			if (skb->len) {
442 				skb_queue_head(&sk->sk_receive_queue, skb);
443 				break;
444 			}
445 			kfree_skb(skb);
446 
447 		} else {
448 			/*
449 			 * It is questionable, see note in unix_dgram_recvmsg.
450 			 */
451 			/* put message back and return */
452 			skb_queue_head(&sk->sk_receive_queue, skb);
453 			break;
454 		}
455 	} while (size);
456 	caif_read_unlock(sk);
457 
458 out:
459 	return copied ? : err;
460 }
461 
462 /*
463  * Copied from sock.c:sock_wait_for_wmem, but change to wait for
464  * CAIF flow-on and sock_writable.
465  */
466 static long caif_wait_for_flow_on(struct caifsock *cf_sk,
467 				  int wait_writeable, long timeo, int *err)
468 {
469 	struct sock *sk = &cf_sk->sk;
470 	DEFINE_WAIT(wait);
471 	for (;;) {
472 		*err = 0;
473 		if (tx_flow_is_on(cf_sk) &&
474 			(!wait_writeable || sock_writeable(&cf_sk->sk)))
475 			break;
476 		*err = -ETIMEDOUT;
477 		if (!timeo)
478 			break;
479 		*err = -ERESTARTSYS;
480 		if (signal_pending(current))
481 			break;
482 		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
483 		*err = -ECONNRESET;
484 		if (sk->sk_shutdown & SHUTDOWN_MASK)
485 			break;
486 		*err = -sk->sk_err;
487 		if (sk->sk_err)
488 			break;
489 		*err = -EPIPE;
490 		if (cf_sk->sk.sk_state != CAIF_CONNECTED)
491 			break;
492 		timeo = schedule_timeout(timeo);
493 	}
494 	finish_wait(sk_sleep(sk), &wait);
495 	return timeo;
496 }
497 
498 /*
499  * Transmit a SKB. The device may temporarily request re-transmission
500  * by returning EAGAIN.
501  */
502 static int transmit_skb(struct sk_buff *skb, struct caifsock *cf_sk,
503 			int noblock, long timeo)
504 {
505 	struct cfpkt *pkt;
506 
507 	pkt = cfpkt_fromnative(CAIF_DIR_OUT, skb);
508 	memset(skb->cb, 0, sizeof(struct caif_payload_info));
509 	cfpkt_set_prio(pkt, cf_sk->sk.sk_priority);
510 
511 	if (cf_sk->layer.dn == NULL) {
512 		kfree_skb(skb);
513 		return -EINVAL;
514 	}
515 
516 	return cf_sk->layer.dn->transmit(cf_sk->layer.dn, pkt);
517 }
518 
519 /* Copied from af_unix:unix_dgram_sendmsg, and adapted to CAIF */
520 static int caif_seqpkt_sendmsg(struct kiocb *kiocb, struct socket *sock,
521 			       struct msghdr *msg, size_t len)
522 {
523 	struct sock *sk = sock->sk;
524 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
525 	int buffer_size;
526 	int ret = 0;
527 	struct sk_buff *skb = NULL;
528 	int noblock;
529 	long timeo;
530 	caif_assert(cf_sk);
531 	ret = sock_error(sk);
532 	if (ret)
533 		goto err;
534 
535 	ret = -EOPNOTSUPP;
536 	if (msg->msg_flags&MSG_OOB)
537 		goto err;
538 
539 	ret = -EOPNOTSUPP;
540 	if (msg->msg_namelen)
541 		goto err;
542 
543 	ret = -EINVAL;
544 	if (unlikely(msg->msg_iov->iov_base == NULL))
545 		goto err;
546 	noblock = msg->msg_flags & MSG_DONTWAIT;
547 
548 	timeo = sock_sndtimeo(sk, noblock);
549 	timeo = caif_wait_for_flow_on(container_of(sk, struct caifsock, sk),
550 				1, timeo, &ret);
551 
552 	if (ret)
553 		goto err;
554 	ret = -EPIPE;
555 	if (cf_sk->sk.sk_state != CAIF_CONNECTED ||
556 		sock_flag(sk, SOCK_DEAD) ||
557 		(sk->sk_shutdown & RCV_SHUTDOWN))
558 		goto err;
559 
560 	/* Error if trying to write more than maximum frame size. */
561 	ret = -EMSGSIZE;
562 	if (len > cf_sk->maxframe && cf_sk->sk.sk_protocol != CAIFPROTO_RFM)
563 		goto err;
564 
565 	buffer_size = len + cf_sk->headroom + cf_sk->tailroom;
566 
567 	ret = -ENOMEM;
568 	skb = sock_alloc_send_skb(sk, buffer_size, noblock, &ret);
569 
570 	if (!skb || skb_tailroom(skb) < buffer_size)
571 		goto err;
572 
573 	skb_reserve(skb, cf_sk->headroom);
574 
575 	ret = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
576 
577 	if (ret)
578 		goto err;
579 	ret = transmit_skb(skb, cf_sk, noblock, timeo);
580 	if (ret < 0)
581 		/* skb is already freed */
582 		return ret;
583 
584 	return len;
585 err:
586 	kfree_skb(skb);
587 	return ret;
588 }
589 
590 /*
591  * Copied from unix_stream_sendmsg and adapted to CAIF:
592  * Changed removed permission handling and added waiting for flow on
593  * and other minor adaptations.
594  */
595 static int caif_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
596 			       struct msghdr *msg, size_t len)
597 {
598 	struct sock *sk = sock->sk;
599 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
600 	int err, size;
601 	struct sk_buff *skb;
602 	int sent = 0;
603 	long timeo;
604 
605 	err = -EOPNOTSUPP;
606 	if (unlikely(msg->msg_flags&MSG_OOB))
607 		goto out_err;
608 
609 	if (unlikely(msg->msg_namelen))
610 		goto out_err;
611 
612 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
613 	timeo = caif_wait_for_flow_on(cf_sk, 1, timeo, &err);
614 
615 	if (unlikely(sk->sk_shutdown & SEND_SHUTDOWN))
616 		goto pipe_err;
617 
618 	while (sent < len) {
619 
620 		size = len-sent;
621 
622 		if (size > cf_sk->maxframe)
623 			size = cf_sk->maxframe;
624 
625 		/* If size is more than half of sndbuf, chop up message */
626 		if (size > ((sk->sk_sndbuf >> 1) - 64))
627 			size = (sk->sk_sndbuf >> 1) - 64;
628 
629 		if (size > SKB_MAX_ALLOC)
630 			size = SKB_MAX_ALLOC;
631 
632 		skb = sock_alloc_send_skb(sk,
633 					size + cf_sk->headroom +
634 					cf_sk->tailroom,
635 					msg->msg_flags&MSG_DONTWAIT,
636 					&err);
637 		if (skb == NULL)
638 			goto out_err;
639 
640 		skb_reserve(skb, cf_sk->headroom);
641 		/*
642 		 *	If you pass two values to the sock_alloc_send_skb
643 		 *	it tries to grab the large buffer with GFP_NOFS
644 		 *	(which can fail easily), and if it fails grab the
645 		 *	fallback size buffer which is under a page and will
646 		 *	succeed. [Alan]
647 		 */
648 		size = min_t(int, size, skb_tailroom(skb));
649 
650 		err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
651 		if (err) {
652 			kfree_skb(skb);
653 			goto out_err;
654 		}
655 		err = transmit_skb(skb, cf_sk,
656 				msg->msg_flags&MSG_DONTWAIT, timeo);
657 		if (err < 0)
658 			/* skb is already freed */
659 			goto pipe_err;
660 
661 		sent += size;
662 	}
663 
664 	return sent;
665 
666 pipe_err:
667 	if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
668 		send_sig(SIGPIPE, current, 0);
669 	err = -EPIPE;
670 out_err:
671 	return sent ? : err;
672 }
673 
674 static int setsockopt(struct socket *sock,
675 		      int lvl, int opt, char __user *ov, unsigned int ol)
676 {
677 	struct sock *sk = sock->sk;
678 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
679 	int linksel;
680 
681 	if (cf_sk->sk.sk_socket->state != SS_UNCONNECTED)
682 		return -ENOPROTOOPT;
683 
684 	switch (opt) {
685 	case CAIFSO_LINK_SELECT:
686 		if (ol < sizeof(int))
687 			return -EINVAL;
688 		if (lvl != SOL_CAIF)
689 			goto bad_sol;
690 		if (copy_from_user(&linksel, ov, sizeof(int)))
691 			return -EINVAL;
692 		lock_sock(&(cf_sk->sk));
693 		cf_sk->conn_req.link_selector = linksel;
694 		release_sock(&cf_sk->sk);
695 		return 0;
696 
697 	case CAIFSO_REQ_PARAM:
698 		if (lvl != SOL_CAIF)
699 			goto bad_sol;
700 		if (cf_sk->sk.sk_protocol != CAIFPROTO_UTIL)
701 			return -ENOPROTOOPT;
702 		lock_sock(&(cf_sk->sk));
703 		if (ol > sizeof(cf_sk->conn_req.param.data) ||
704 			copy_from_user(&cf_sk->conn_req.param.data, ov, ol)) {
705 			release_sock(&cf_sk->sk);
706 			return -EINVAL;
707 		}
708 		cf_sk->conn_req.param.size = ol;
709 		release_sock(&cf_sk->sk);
710 		return 0;
711 
712 	default:
713 		return -ENOPROTOOPT;
714 	}
715 
716 	return 0;
717 bad_sol:
718 	return -ENOPROTOOPT;
719 
720 }
721 
722 /*
723  * caif_connect() - Connect a CAIF Socket
724  * Copied and modified af_irda.c:irda_connect().
725  *
726  * Note : by consulting "errno", the user space caller may learn the cause
727  * of the failure. Most of them are visible in the function, others may come
728  * from subroutines called and are listed here :
729  *  o -EAFNOSUPPORT: bad socket family or type.
730  *  o -ESOCKTNOSUPPORT: bad socket type or protocol
731  *  o -EINVAL: bad socket address, or CAIF link type
732  *  o -ECONNREFUSED: remote end refused the connection.
733  *  o -EINPROGRESS: connect request sent but timed out (or non-blocking)
734  *  o -EISCONN: already connected.
735  *  o -ETIMEDOUT: Connection timed out (send timeout)
736  *  o -ENODEV: No link layer to send request
737  *  o -ECONNRESET: Received Shutdown indication or lost link layer
738  *  o -ENOMEM: Out of memory
739  *
740  *  State Strategy:
741  *  o sk_state: holds the CAIF_* protocol state, it's updated by
742  *	caif_ctrl_cb.
743  *  o sock->state: holds the SS_* socket state and is updated by connect and
744  *	disconnect.
745  */
746 static int caif_connect(struct socket *sock, struct sockaddr *uaddr,
747 			int addr_len, int flags)
748 {
749 	struct sock *sk = sock->sk;
750 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
751 	long timeo;
752 	int err;
753 	int ifindex, headroom, tailroom;
754 	unsigned int mtu;
755 	struct net_device *dev;
756 
757 	lock_sock(sk);
758 
759 	err = -EAFNOSUPPORT;
760 	if (uaddr->sa_family != AF_CAIF)
761 		goto out;
762 
763 	switch (sock->state) {
764 	case SS_UNCONNECTED:
765 		/* Normal case, a fresh connect */
766 		caif_assert(sk->sk_state == CAIF_DISCONNECTED);
767 		break;
768 	case SS_CONNECTING:
769 		switch (sk->sk_state) {
770 		case CAIF_CONNECTED:
771 			sock->state = SS_CONNECTED;
772 			err = -EISCONN;
773 			goto out;
774 		case CAIF_DISCONNECTED:
775 			/* Reconnect allowed */
776 			break;
777 		case CAIF_CONNECTING:
778 			err = -EALREADY;
779 			if (flags & O_NONBLOCK)
780 				goto out;
781 			goto wait_connect;
782 		}
783 		break;
784 	case SS_CONNECTED:
785 		caif_assert(sk->sk_state == CAIF_CONNECTED ||
786 				sk->sk_state == CAIF_DISCONNECTED);
787 		if (sk->sk_shutdown & SHUTDOWN_MASK) {
788 			/* Allow re-connect after SHUTDOWN_IND */
789 			caif_disconnect_client(sock_net(sk), &cf_sk->layer);
790 			caif_free_client(&cf_sk->layer);
791 			break;
792 		}
793 		/* No reconnect on a seqpacket socket */
794 		err = -EISCONN;
795 		goto out;
796 	case SS_DISCONNECTING:
797 	case SS_FREE:
798 		caif_assert(1); /*Should never happen */
799 		break;
800 	}
801 	sk->sk_state = CAIF_DISCONNECTED;
802 	sock->state = SS_UNCONNECTED;
803 	sk_stream_kill_queues(&cf_sk->sk);
804 
805 	err = -EINVAL;
806 	if (addr_len != sizeof(struct sockaddr_caif))
807 		goto out;
808 
809 	memcpy(&cf_sk->conn_req.sockaddr, uaddr,
810 		sizeof(struct sockaddr_caif));
811 
812 	/* Move to connecting socket, start sending Connect Requests */
813 	sock->state = SS_CONNECTING;
814 	sk->sk_state = CAIF_CONNECTING;
815 
816 	/* Check priority value comming from socket */
817 	/* if priority value is out of range it will be ajusted */
818 	if (cf_sk->sk.sk_priority > CAIF_PRIO_MAX)
819 		cf_sk->conn_req.priority = CAIF_PRIO_MAX;
820 	else if (cf_sk->sk.sk_priority < CAIF_PRIO_MIN)
821 		cf_sk->conn_req.priority = CAIF_PRIO_MIN;
822 	else
823 		cf_sk->conn_req.priority = cf_sk->sk.sk_priority;
824 
825 	/*ifindex = id of the interface.*/
826 	cf_sk->conn_req.ifindex = cf_sk->sk.sk_bound_dev_if;
827 
828 	cf_sk->layer.receive = caif_sktrecv_cb;
829 
830 	err = caif_connect_client(sock_net(sk), &cf_sk->conn_req,
831 				&cf_sk->layer, &ifindex, &headroom, &tailroom);
832 
833 	if (err < 0) {
834 		cf_sk->sk.sk_socket->state = SS_UNCONNECTED;
835 		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
836 		goto out;
837 	}
838 
839 	err = -ENODEV;
840 	rcu_read_lock();
841 	dev = dev_get_by_index_rcu(sock_net(sk), ifindex);
842 	if (!dev) {
843 		rcu_read_unlock();
844 		goto out;
845 	}
846 	cf_sk->headroom = LL_RESERVED_SPACE_EXTRA(dev, headroom);
847 	mtu = dev->mtu;
848 	rcu_read_unlock();
849 
850 	cf_sk->tailroom = tailroom;
851 	cf_sk->maxframe = mtu - (headroom + tailroom);
852 	if (cf_sk->maxframe < 1) {
853 		pr_warn("CAIF Interface MTU too small (%d)\n", dev->mtu);
854 		err = -ENODEV;
855 		goto out;
856 	}
857 
858 	err = -EINPROGRESS;
859 wait_connect:
860 
861 	if (sk->sk_state != CAIF_CONNECTED && (flags & O_NONBLOCK))
862 		goto out;
863 
864 	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
865 
866 	release_sock(sk);
867 	err = -ERESTARTSYS;
868 	timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
869 			sk->sk_state != CAIF_CONNECTING,
870 			timeo);
871 	lock_sock(sk);
872 	if (timeo < 0)
873 		goto out; /* -ERESTARTSYS */
874 
875 	err = -ETIMEDOUT;
876 	if (timeo == 0 && sk->sk_state != CAIF_CONNECTED)
877 		goto out;
878 	if (sk->sk_state != CAIF_CONNECTED) {
879 		sock->state = SS_UNCONNECTED;
880 		err = sock_error(sk);
881 		if (!err)
882 			err = -ECONNREFUSED;
883 		goto out;
884 	}
885 	sock->state = SS_CONNECTED;
886 	err = 0;
887 out:
888 	release_sock(sk);
889 	return err;
890 }
891 
892 /*
893  * caif_release() - Disconnect a CAIF Socket
894  * Copied and modified af_irda.c:irda_release().
895  */
896 static int caif_release(struct socket *sock)
897 {
898 	struct sock *sk = sock->sk;
899 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
900 
901 	if (!sk)
902 		return 0;
903 
904 	set_tx_flow_off(cf_sk);
905 
906 	/*
907 	 * Ensure that packets are not queued after this point in time.
908 	 * caif_queue_rcv_skb checks SOCK_DEAD holding the queue lock,
909 	 * this ensures no packets when sock is dead.
910 	 */
911 	spin_lock_bh(&sk->sk_receive_queue.lock);
912 	sock_set_flag(sk, SOCK_DEAD);
913 	spin_unlock_bh(&sk->sk_receive_queue.lock);
914 	sock->sk = NULL;
915 
916 	WARN_ON(IS_ERR(cf_sk->debugfs_socket_dir));
917 	if (cf_sk->debugfs_socket_dir != NULL)
918 		debugfs_remove_recursive(cf_sk->debugfs_socket_dir);
919 
920 	lock_sock(&(cf_sk->sk));
921 	sk->sk_state = CAIF_DISCONNECTED;
922 	sk->sk_shutdown = SHUTDOWN_MASK;
923 
924 	caif_disconnect_client(sock_net(sk), &cf_sk->layer);
925 	cf_sk->sk.sk_socket->state = SS_DISCONNECTING;
926 	wake_up_interruptible_poll(sk_sleep(sk), POLLERR|POLLHUP);
927 
928 	sock_orphan(sk);
929 	sk_stream_kill_queues(&cf_sk->sk);
930 	release_sock(sk);
931 	sock_put(sk);
932 	return 0;
933 }
934 
935 /* Copied from af_unix.c:unix_poll(), added CAIF tx_flow handling */
936 static unsigned int caif_poll(struct file *file,
937 			      struct socket *sock, poll_table *wait)
938 {
939 	struct sock *sk = sock->sk;
940 	unsigned int mask;
941 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
942 
943 	sock_poll_wait(file, sk_sleep(sk), wait);
944 	mask = 0;
945 
946 	/* exceptional events? */
947 	if (sk->sk_err)
948 		mask |= POLLERR;
949 	if (sk->sk_shutdown == SHUTDOWN_MASK)
950 		mask |= POLLHUP;
951 	if (sk->sk_shutdown & RCV_SHUTDOWN)
952 		mask |= POLLRDHUP;
953 
954 	/* readable? */
955 	if (!skb_queue_empty(&sk->sk_receive_queue) ||
956 		(sk->sk_shutdown & RCV_SHUTDOWN))
957 		mask |= POLLIN | POLLRDNORM;
958 
959 	/*
960 	 * we set writable also when the other side has shut down the
961 	 * connection. This prevents stuck sockets.
962 	 */
963 	if (sock_writeable(sk) && tx_flow_is_on(cf_sk))
964 		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
965 
966 	return mask;
967 }
968 
969 static const struct proto_ops caif_seqpacket_ops = {
970 	.family = PF_CAIF,
971 	.owner = THIS_MODULE,
972 	.release = caif_release,
973 	.bind = sock_no_bind,
974 	.connect = caif_connect,
975 	.socketpair = sock_no_socketpair,
976 	.accept = sock_no_accept,
977 	.getname = sock_no_getname,
978 	.poll = caif_poll,
979 	.ioctl = sock_no_ioctl,
980 	.listen = sock_no_listen,
981 	.shutdown = sock_no_shutdown,
982 	.setsockopt = setsockopt,
983 	.getsockopt = sock_no_getsockopt,
984 	.sendmsg = caif_seqpkt_sendmsg,
985 	.recvmsg = caif_seqpkt_recvmsg,
986 	.mmap = sock_no_mmap,
987 	.sendpage = sock_no_sendpage,
988 };
989 
990 static const struct proto_ops caif_stream_ops = {
991 	.family = PF_CAIF,
992 	.owner = THIS_MODULE,
993 	.release = caif_release,
994 	.bind = sock_no_bind,
995 	.connect = caif_connect,
996 	.socketpair = sock_no_socketpair,
997 	.accept = sock_no_accept,
998 	.getname = sock_no_getname,
999 	.poll = caif_poll,
1000 	.ioctl = sock_no_ioctl,
1001 	.listen = sock_no_listen,
1002 	.shutdown = sock_no_shutdown,
1003 	.setsockopt = setsockopt,
1004 	.getsockopt = sock_no_getsockopt,
1005 	.sendmsg = caif_stream_sendmsg,
1006 	.recvmsg = caif_stream_recvmsg,
1007 	.mmap = sock_no_mmap,
1008 	.sendpage = sock_no_sendpage,
1009 };
1010 
1011 /* This function is called when a socket is finally destroyed. */
1012 static void caif_sock_destructor(struct sock *sk)
1013 {
1014 	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
1015 	caif_assert(!atomic_read(&sk->sk_wmem_alloc));
1016 	caif_assert(sk_unhashed(sk));
1017 	caif_assert(!sk->sk_socket);
1018 	if (!sock_flag(sk, SOCK_DEAD)) {
1019 		pr_debug("Attempt to release alive CAIF socket: %p\n", sk);
1020 		return;
1021 	}
1022 	sk_stream_kill_queues(&cf_sk->sk);
1023 	caif_free_client(&cf_sk->layer);
1024 }
1025 
1026 static int caif_create(struct net *net, struct socket *sock, int protocol,
1027 		       int kern)
1028 {
1029 	struct sock *sk = NULL;
1030 	struct caifsock *cf_sk = NULL;
1031 	static struct proto prot = {.name = "PF_CAIF",
1032 		.owner = THIS_MODULE,
1033 		.obj_size = sizeof(struct caifsock),
1034 	};
1035 
1036 	if (!capable(CAP_SYS_ADMIN) && !capable(CAP_NET_ADMIN))
1037 		return -EPERM;
1038 	/*
1039 	 * The sock->type specifies the socket type to use.
1040 	 * The CAIF socket is a packet stream in the sense
1041 	 * that it is packet based. CAIF trusts the reliability
1042 	 * of the link, no resending is implemented.
1043 	 */
1044 	if (sock->type == SOCK_SEQPACKET)
1045 		sock->ops = &caif_seqpacket_ops;
1046 	else if (sock->type == SOCK_STREAM)
1047 		sock->ops = &caif_stream_ops;
1048 	else
1049 		return -ESOCKTNOSUPPORT;
1050 
1051 	if (protocol < 0 || protocol >= CAIFPROTO_MAX)
1052 		return -EPROTONOSUPPORT;
1053 	/*
1054 	 * Set the socket state to unconnected.	 The socket state
1055 	 * is really not used at all in the net/core or socket.c but the
1056 	 * initialization makes sure that sock->state is not uninitialized.
1057 	 */
1058 	sk = sk_alloc(net, PF_CAIF, GFP_KERNEL, &prot);
1059 	if (!sk)
1060 		return -ENOMEM;
1061 
1062 	cf_sk = container_of(sk, struct caifsock, sk);
1063 
1064 	/* Store the protocol */
1065 	sk->sk_protocol = (unsigned char) protocol;
1066 
1067 	/* Initialize default priority for well-known cases */
1068 	switch (protocol) {
1069 	case CAIFPROTO_AT:
1070 		sk->sk_priority = TC_PRIO_CONTROL;
1071 		break;
1072 	case CAIFPROTO_RFM:
1073 		sk->sk_priority = TC_PRIO_INTERACTIVE_BULK;
1074 		break;
1075 	default:
1076 		sk->sk_priority = TC_PRIO_BESTEFFORT;
1077 	}
1078 
1079 	/*
1080 	 * Lock in order to try to stop someone from opening the socket
1081 	 * too early.
1082 	 */
1083 	lock_sock(&(cf_sk->sk));
1084 
1085 	/* Initialize the nozero default sock structure data. */
1086 	sock_init_data(sock, sk);
1087 	sk->sk_destruct = caif_sock_destructor;
1088 
1089 	mutex_init(&cf_sk->readlock); /* single task reading lock */
1090 	cf_sk->layer.ctrlcmd = caif_ctrl_cb;
1091 	cf_sk->sk.sk_socket->state = SS_UNCONNECTED;
1092 	cf_sk->sk.sk_state = CAIF_DISCONNECTED;
1093 
1094 	set_tx_flow_off(cf_sk);
1095 	set_rx_flow_on(cf_sk);
1096 
1097 	/* Set default options on configuration */
1098 	cf_sk->conn_req.link_selector = CAIF_LINK_LOW_LATENCY;
1099 	cf_sk->conn_req.protocol = protocol;
1100 	release_sock(&cf_sk->sk);
1101 	return 0;
1102 }
1103 
1104 
1105 static struct net_proto_family caif_family_ops = {
1106 	.family = PF_CAIF,
1107 	.create = caif_create,
1108 	.owner = THIS_MODULE,
1109 };
1110 
1111 static int __init caif_sktinit_module(void)
1112 {
1113 	int err = sock_register(&caif_family_ops);
1114 	if (!err)
1115 		return err;
1116 	return 0;
1117 }
1118 
1119 static void __exit caif_sktexit_module(void)
1120 {
1121 	sock_unregister(PF_CAIF);
1122 }
1123 module_init(caif_sktinit_module);
1124 module_exit(caif_sktexit_module);
1125