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