1 /*
2  * llc_conn.c - Driver routines for connection component.
3  *
4  * Copyright (c) 1997 by Procom Technology, Inc.
5  *		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6  *
7  * This program can be redistributed or modified under the terms of the
8  * GNU General Public License as published by the Free Software Foundation.
9  * This program is distributed without any warranty or implied warranty
10  * of merchantability or fitness for a particular purpose.
11  *
12  * See the GNU General Public License for more details.
13  */
14 
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <net/llc_sap.h>
18 #include <net/llc_conn.h>
19 #include <net/sock.h>
20 #include <net/tcp_states.h>
21 #include <net/llc_c_ev.h>
22 #include <net/llc_c_ac.h>
23 #include <net/llc_c_st.h>
24 #include <net/llc_pdu.h>
25 
26 #if 0
27 #define dprintk(args...) printk(KERN_DEBUG args)
28 #else
29 #define dprintk(args...)
30 #endif
31 
32 static int llc_find_offset(int state, int ev_type);
33 static void llc_conn_send_pdus(struct sock *sk);
34 static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
35 static int llc_exec_conn_trans_actions(struct sock *sk,
36 				       struct llc_conn_state_trans *trans,
37 				       struct sk_buff *ev);
38 static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
39 							struct sk_buff *skb);
40 
41 /* Offset table on connection states transition diagram */
42 static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];
43 
44 int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
45 int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
46 int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
47 int sysctl_llc2_busy_timeout = LLC2_BUSY_TIME * HZ;
48 
49 /**
50  *	llc_conn_state_process - sends event to connection state machine
51  *	@sk: connection
52  *	@skb: occurred event
53  *
54  *	Sends an event to connection state machine. After processing event
55  *	(executing it's actions and changing state), upper layer will be
56  *	indicated or confirmed, if needed. Returns 0 for success, 1 for
57  *	failure. The socket lock has to be held before calling this function.
58  */
llc_conn_state_process(struct sock * sk,struct sk_buff * skb)59 int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
60 {
61 	int rc;
62 	struct llc_sock *llc = llc_sk(skb->sk);
63 	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
64 
65 	/*
66 	 * We have to hold the skb, because llc_conn_service will kfree it in
67 	 * the sending path and we need to look at the skb->cb, where we encode
68 	 * llc_conn_state_ev.
69 	 */
70 	skb_get(skb);
71 	ev->ind_prim = ev->cfm_prim = 0;
72 	/*
73 	 * Send event to state machine
74 	 */
75 	rc = llc_conn_service(skb->sk, skb);
76 	if (unlikely(rc != 0)) {
77 		printk(KERN_ERR "%s: llc_conn_service failed\n", __func__);
78 		goto out_kfree_skb;
79 	}
80 
81 	if (unlikely(!ev->ind_prim && !ev->cfm_prim)) {
82 		/* indicate or confirm not required */
83 		if (!skb->next)
84 			goto out_kfree_skb;
85 		goto out_skb_put;
86 	}
87 
88 	if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
89 		skb_get(skb);
90 
91 	switch (ev->ind_prim) {
92 	case LLC_DATA_PRIM:
93 		llc_save_primitive(sk, skb, LLC_DATA_PRIM);
94 		if (unlikely(sock_queue_rcv_skb(sk, skb))) {
95 			/*
96 			 * shouldn't happen
97 			 */
98 			printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
99 			       __func__);
100 			kfree_skb(skb);
101 		}
102 		break;
103 	case LLC_CONN_PRIM:
104 		/*
105 		 * Can't be sock_queue_rcv_skb, because we have to leave the
106 		 * skb->sk pointing to the newly created struct sock in
107 		 * llc_conn_handler. -acme
108 		 */
109 		skb_queue_tail(&sk->sk_receive_queue, skb);
110 		sk->sk_state_change(sk);
111 		break;
112 	case LLC_DISC_PRIM:
113 		sock_hold(sk);
114 		if (sk->sk_type == SOCK_STREAM &&
115 		    sk->sk_state == TCP_ESTABLISHED) {
116 			sk->sk_shutdown       = SHUTDOWN_MASK;
117 			sk->sk_socket->state  = SS_UNCONNECTED;
118 			sk->sk_state          = TCP_CLOSE;
119 			if (!sock_flag(sk, SOCK_DEAD)) {
120 				sock_set_flag(sk, SOCK_DEAD);
121 				sk->sk_state_change(sk);
122 			}
123 		}
124 		kfree_skb(skb);
125 		sock_put(sk);
126 		break;
127 	case LLC_RESET_PRIM:
128 		/*
129 		 * FIXME:
130 		 * RESET is not being notified to upper layers for now
131 		 */
132 		printk(KERN_INFO "%s: received a reset ind!\n", __func__);
133 		kfree_skb(skb);
134 		break;
135 	default:
136 		if (ev->ind_prim) {
137 			printk(KERN_INFO "%s: received unknown %d prim!\n",
138 				__func__, ev->ind_prim);
139 			kfree_skb(skb);
140 		}
141 		/* No indication */
142 		break;
143 	}
144 
145 	switch (ev->cfm_prim) {
146 	case LLC_DATA_PRIM:
147 		if (!llc_data_accept_state(llc->state))
148 			sk->sk_write_space(sk);
149 		else
150 			rc = llc->failed_data_req = 1;
151 		break;
152 	case LLC_CONN_PRIM:
153 		if (sk->sk_type == SOCK_STREAM &&
154 		    sk->sk_state == TCP_SYN_SENT) {
155 			if (ev->status) {
156 				sk->sk_socket->state = SS_UNCONNECTED;
157 				sk->sk_state         = TCP_CLOSE;
158 			} else {
159 				sk->sk_socket->state = SS_CONNECTED;
160 				sk->sk_state         = TCP_ESTABLISHED;
161 			}
162 			sk->sk_state_change(sk);
163 		}
164 		break;
165 	case LLC_DISC_PRIM:
166 		sock_hold(sk);
167 		if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
168 			sk->sk_socket->state = SS_UNCONNECTED;
169 			sk->sk_state         = TCP_CLOSE;
170 			sk->sk_state_change(sk);
171 		}
172 		sock_put(sk);
173 		break;
174 	case LLC_RESET_PRIM:
175 		/*
176 		 * FIXME:
177 		 * RESET is not being notified to upper layers for now
178 		 */
179 		printk(KERN_INFO "%s: received a reset conf!\n", __func__);
180 		break;
181 	default:
182 		if (ev->cfm_prim) {
183 			printk(KERN_INFO "%s: received unknown %d prim!\n",
184 					__func__, ev->cfm_prim);
185 			break;
186 		}
187 		goto out_skb_put; /* No confirmation */
188 	}
189 out_kfree_skb:
190 	kfree_skb(skb);
191 out_skb_put:
192 	kfree_skb(skb);
193 	return rc;
194 }
195 
llc_conn_send_pdu(struct sock * sk,struct sk_buff * skb)196 void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
197 {
198 	/* queue PDU to send to MAC layer */
199 	skb_queue_tail(&sk->sk_write_queue, skb);
200 	llc_conn_send_pdus(sk);
201 }
202 
203 /**
204  *	llc_conn_rtn_pdu - sends received data pdu to upper layer
205  *	@sk: Active connection
206  *	@skb: Received data frame
207  *
208  *	Sends received data pdu to upper layer (by using indicate function).
209  *	Prepares service parameters (prim and prim_data). calling indication
210  *	function will be done in llc_conn_state_process.
211  */
llc_conn_rtn_pdu(struct sock * sk,struct sk_buff * skb)212 void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
213 {
214 	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
215 
216 	ev->ind_prim = LLC_DATA_PRIM;
217 }
218 
219 /**
220  *	llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
221  *	@sk: active connection
222  *	@nr: NR
223  *	@first_p_bit: p_bit value of first pdu
224  *
225  *	Resend all unacknowledged I PDUs, starting with the NR; send first as
226  *	command PDU with P bit equal first_p_bit; if more than one send
227  *	subsequent as command PDUs with P bit equal zero (0).
228  */
llc_conn_resend_i_pdu_as_cmd(struct sock * sk,u8 nr,u8 first_p_bit)229 void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
230 {
231 	struct sk_buff *skb;
232 	struct llc_pdu_sn *pdu;
233 	u16 nbr_unack_pdus;
234 	struct llc_sock *llc;
235 	u8 howmany_resend = 0;
236 
237 	llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
238 	if (!nbr_unack_pdus)
239 		goto out;
240 	/*
241 	 * Process unack PDUs only if unack queue is not empty; remove
242 	 * appropriate PDUs, fix them up, and put them on mac_pdu_q.
243 	 */
244 	llc = llc_sk(sk);
245 
246 	while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
247 		pdu = llc_pdu_sn_hdr(skb);
248 		llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
249 		llc_pdu_set_pf_bit(skb, first_p_bit);
250 		skb_queue_tail(&sk->sk_write_queue, skb);
251 		first_p_bit = 0;
252 		llc->vS = LLC_I_GET_NS(pdu);
253 		howmany_resend++;
254 	}
255 	if (howmany_resend > 0)
256 		llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
257 	/* any PDUs to re-send are queued up; start sending to MAC */
258 	llc_conn_send_pdus(sk);
259 out:;
260 }
261 
262 /**
263  *	llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
264  *	@sk: active connection.
265  *	@nr: NR
266  *	@first_f_bit: f_bit value of first pdu.
267  *
268  *	Resend all unacknowledged I PDUs, starting with the NR; send first as
269  *	response PDU with F bit equal first_f_bit; if more than one send
270  *	subsequent as response PDUs with F bit equal zero (0).
271  */
llc_conn_resend_i_pdu_as_rsp(struct sock * sk,u8 nr,u8 first_f_bit)272 void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
273 {
274 	struct sk_buff *skb;
275 	u16 nbr_unack_pdus;
276 	struct llc_sock *llc = llc_sk(sk);
277 	u8 howmany_resend = 0;
278 
279 	llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
280 	if (!nbr_unack_pdus)
281 		goto out;
282 	/*
283 	 * Process unack PDUs only if unack queue is not empty; remove
284 	 * appropriate PDUs, fix them up, and put them on mac_pdu_q
285 	 */
286 	while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
287 		struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
288 
289 		llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
290 		llc_pdu_set_pf_bit(skb, first_f_bit);
291 		skb_queue_tail(&sk->sk_write_queue, skb);
292 		first_f_bit = 0;
293 		llc->vS = LLC_I_GET_NS(pdu);
294 		howmany_resend++;
295 	}
296 	if (howmany_resend > 0)
297 		llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
298 	/* any PDUs to re-send are queued up; start sending to MAC */
299 	llc_conn_send_pdus(sk);
300 out:;
301 }
302 
303 /**
304  *	llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
305  *	@sk: active connection
306  *	nr: NR
307  *	how_many_unacked: size of pdu_unack_q after removing acked pdus
308  *
309  *	Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
310  *	the number of pdus that removed from queue.
311  */
llc_conn_remove_acked_pdus(struct sock * sk,u8 nr,u16 * how_many_unacked)312 int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
313 {
314 	int pdu_pos, i;
315 	struct sk_buff *skb;
316 	struct llc_pdu_sn *pdu;
317 	int nbr_acked = 0;
318 	struct llc_sock *llc = llc_sk(sk);
319 	int q_len = skb_queue_len(&llc->pdu_unack_q);
320 
321 	if (!q_len)
322 		goto out;
323 	skb = skb_peek(&llc->pdu_unack_q);
324 	pdu = llc_pdu_sn_hdr(skb);
325 
326 	/* finding position of last acked pdu in queue */
327 	pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
328 			(int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
329 
330 	for (i = 0; i < pdu_pos && i < q_len; i++) {
331 		skb = skb_dequeue(&llc->pdu_unack_q);
332 		kfree_skb(skb);
333 		nbr_acked++;
334 	}
335 out:
336 	*how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
337 	return nbr_acked;
338 }
339 
340 /**
341  *	llc_conn_send_pdus - Sends queued PDUs
342  *	@sk: active connection
343  *
344  *	Sends queued pdus to MAC layer for transmission.
345  */
llc_conn_send_pdus(struct sock * sk)346 static void llc_conn_send_pdus(struct sock *sk)
347 {
348 	struct sk_buff *skb;
349 
350 	while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
351 		struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
352 
353 		if (LLC_PDU_TYPE_IS_I(pdu) &&
354 		    !(skb->dev->flags & IFF_LOOPBACK)) {
355 			struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
356 
357 			skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
358 			if (!skb2)
359 				break;
360 			skb = skb2;
361 		}
362 		dev_queue_xmit(skb);
363 	}
364 }
365 
366 /**
367  *	llc_conn_service - finds transition and changes state of connection
368  *	@sk: connection
369  *	@skb: happened event
370  *
371  *	This function finds transition that matches with happened event, then
372  *	executes related actions and finally changes state of connection.
373  *	Returns 0 for success, 1 for failure.
374  */
llc_conn_service(struct sock * sk,struct sk_buff * skb)375 static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
376 {
377 	int rc = 1;
378 	struct llc_sock *llc = llc_sk(sk);
379 	struct llc_conn_state_trans *trans;
380 
381 	if (llc->state > NBR_CONN_STATES)
382 		goto out;
383 	rc = 0;
384 	trans = llc_qualify_conn_ev(sk, skb);
385 	if (trans) {
386 		rc = llc_exec_conn_trans_actions(sk, trans, skb);
387 		if (!rc && trans->next_state != NO_STATE_CHANGE) {
388 			llc->state = trans->next_state;
389 			if (!llc_data_accept_state(llc->state))
390 				sk->sk_state_change(sk);
391 		}
392 	}
393 out:
394 	return rc;
395 }
396 
397 /**
398  *	llc_qualify_conn_ev - finds transition for event
399  *	@sk: connection
400  *	@skb: happened event
401  *
402  *	This function finds transition that matches with happened event.
403  *	Returns pointer to found transition on success, %NULL otherwise.
404  */
llc_qualify_conn_ev(struct sock * sk,struct sk_buff * skb)405 static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
406 							struct sk_buff *skb)
407 {
408 	struct llc_conn_state_trans **next_trans;
409 	llc_conn_ev_qfyr_t *next_qualifier;
410 	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
411 	struct llc_sock *llc = llc_sk(sk);
412 	struct llc_conn_state *curr_state =
413 					&llc_conn_state_table[llc->state - 1];
414 
415 	/* search thru events for this state until
416 	 * list exhausted or until no more
417 	 */
418 	for (next_trans = curr_state->transitions +
419 		llc_find_offset(llc->state - 1, ev->type);
420 	     (*next_trans)->ev; next_trans++) {
421 		if (!((*next_trans)->ev)(sk, skb)) {
422 			/* got POSSIBLE event match; the event may require
423 			 * qualification based on the values of a number of
424 			 * state flags; if all qualifications are met (i.e.,
425 			 * if all qualifying functions return success, or 0,
426 			 * then this is THE event we're looking for
427 			 */
428 			for (next_qualifier = (*next_trans)->ev_qualifiers;
429 			     next_qualifier && *next_qualifier &&
430 			     !(*next_qualifier)(sk, skb); next_qualifier++)
431 				/* nothing */;
432 			if (!next_qualifier || !*next_qualifier)
433 				/* all qualifiers executed successfully; this is
434 				 * our transition; return it so we can perform
435 				 * the associated actions & change the state
436 				 */
437 				return *next_trans;
438 		}
439 	}
440 	return NULL;
441 }
442 
443 /**
444  *	llc_exec_conn_trans_actions - executes related actions
445  *	@sk: connection
446  *	@trans: transition that it's actions must be performed
447  *	@skb: event
448  *
449  *	Executes actions that is related to happened event. Returns 0 for
450  *	success, 1 to indicate failure of at least one action.
451  */
llc_exec_conn_trans_actions(struct sock * sk,struct llc_conn_state_trans * trans,struct sk_buff * skb)452 static int llc_exec_conn_trans_actions(struct sock *sk,
453 				       struct llc_conn_state_trans *trans,
454 				       struct sk_buff *skb)
455 {
456 	int rc = 0;
457 	llc_conn_action_t *next_action;
458 
459 	for (next_action = trans->ev_actions;
460 	     next_action && *next_action; next_action++) {
461 		int rc2 = (*next_action)(sk, skb);
462 
463 		if (rc2 == 2) {
464 			rc = rc2;
465 			break;
466 		} else if (rc2)
467 			rc = 1;
468 	}
469 	return rc;
470 }
471 
llc_estab_match(const struct llc_sap * sap,const struct llc_addr * daddr,const struct llc_addr * laddr,const struct sock * sk)472 static inline bool llc_estab_match(const struct llc_sap *sap,
473 				   const struct llc_addr *daddr,
474 				   const struct llc_addr *laddr,
475 				   const struct sock *sk)
476 {
477 	struct llc_sock *llc = llc_sk(sk);
478 
479 	return llc->laddr.lsap == laddr->lsap &&
480 		llc->daddr.lsap == daddr->lsap &&
481 		llc_mac_match(llc->laddr.mac, laddr->mac) &&
482 		llc_mac_match(llc->daddr.mac, daddr->mac);
483 }
484 
485 /**
486  *	__llc_lookup_established - Finds connection for the remote/local sap/mac
487  *	@sap: SAP
488  *	@daddr: address of remote LLC (MAC + SAP)
489  *	@laddr: address of local LLC (MAC + SAP)
490  *
491  *	Search connection list of the SAP and finds connection using the remote
492  *	mac, remote sap, local mac, and local sap. Returns pointer for
493  *	connection found, %NULL otherwise.
494  *	Caller has to make sure local_bh is disabled.
495  */
__llc_lookup_established(struct llc_sap * sap,struct llc_addr * daddr,struct llc_addr * laddr)496 static struct sock *__llc_lookup_established(struct llc_sap *sap,
497 					     struct llc_addr *daddr,
498 					     struct llc_addr *laddr)
499 {
500 	struct sock *rc;
501 	struct hlist_nulls_node *node;
502 	int slot = llc_sk_laddr_hashfn(sap, laddr);
503 	struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
504 
505 	rcu_read_lock();
506 again:
507 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
508 		if (llc_estab_match(sap, daddr, laddr, rc)) {
509 			/* Extra checks required by SLAB_DESTROY_BY_RCU */
510 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
511 				goto again;
512 			if (unlikely(llc_sk(rc)->sap != sap ||
513 				     !llc_estab_match(sap, daddr, laddr, rc))) {
514 				sock_put(rc);
515 				continue;
516 			}
517 			goto found;
518 		}
519 	}
520 	rc = NULL;
521 	/*
522 	 * if the nulls value we got at the end of this lookup is
523 	 * not the expected one, we must restart lookup.
524 	 * We probably met an item that was moved to another chain.
525 	 */
526 	if (unlikely(get_nulls_value(node) != slot))
527 		goto again;
528 found:
529 	rcu_read_unlock();
530 	return rc;
531 }
532 
llc_lookup_established(struct llc_sap * sap,struct llc_addr * daddr,struct llc_addr * laddr)533 struct sock *llc_lookup_established(struct llc_sap *sap,
534 				    struct llc_addr *daddr,
535 				    struct llc_addr *laddr)
536 {
537 	struct sock *sk;
538 
539 	local_bh_disable();
540 	sk = __llc_lookup_established(sap, daddr, laddr);
541 	local_bh_enable();
542 	return sk;
543 }
544 
llc_listener_match(const struct llc_sap * sap,const struct llc_addr * laddr,const struct sock * sk)545 static inline bool llc_listener_match(const struct llc_sap *sap,
546 				      const struct llc_addr *laddr,
547 				      const struct sock *sk)
548 {
549 	struct llc_sock *llc = llc_sk(sk);
550 
551 	return sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_LISTEN &&
552 		llc->laddr.lsap == laddr->lsap &&
553 		llc_mac_match(llc->laddr.mac, laddr->mac);
554 }
555 
__llc_lookup_listener(struct llc_sap * sap,struct llc_addr * laddr)556 static struct sock *__llc_lookup_listener(struct llc_sap *sap,
557 					  struct llc_addr *laddr)
558 {
559 	struct sock *rc;
560 	struct hlist_nulls_node *node;
561 	int slot = llc_sk_laddr_hashfn(sap, laddr);
562 	struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
563 
564 	rcu_read_lock();
565 again:
566 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
567 		if (llc_listener_match(sap, laddr, rc)) {
568 			/* Extra checks required by SLAB_DESTROY_BY_RCU */
569 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
570 				goto again;
571 			if (unlikely(llc_sk(rc)->sap != sap ||
572 				     !llc_listener_match(sap, laddr, rc))) {
573 				sock_put(rc);
574 				continue;
575 			}
576 			goto found;
577 		}
578 	}
579 	rc = NULL;
580 	/*
581 	 * if the nulls value we got at the end of this lookup is
582 	 * not the expected one, we must restart lookup.
583 	 * We probably met an item that was moved to another chain.
584 	 */
585 	if (unlikely(get_nulls_value(node) != slot))
586 		goto again;
587 found:
588 	rcu_read_unlock();
589 	return rc;
590 }
591 
592 /**
593  *	llc_lookup_listener - Finds listener for local MAC + SAP
594  *	@sap: SAP
595  *	@laddr: address of local LLC (MAC + SAP)
596  *
597  *	Search connection list of the SAP and finds connection listening on
598  *	local mac, and local sap. Returns pointer for parent socket found,
599  *	%NULL otherwise.
600  *	Caller has to make sure local_bh is disabled.
601  */
llc_lookup_listener(struct llc_sap * sap,struct llc_addr * laddr)602 static struct sock *llc_lookup_listener(struct llc_sap *sap,
603 					struct llc_addr *laddr)
604 {
605 	static struct llc_addr null_addr;
606 	struct sock *rc = __llc_lookup_listener(sap, laddr);
607 
608 	if (!rc)
609 		rc = __llc_lookup_listener(sap, &null_addr);
610 
611 	return rc;
612 }
613 
__llc_lookup(struct llc_sap * sap,struct llc_addr * daddr,struct llc_addr * laddr)614 static struct sock *__llc_lookup(struct llc_sap *sap,
615 				 struct llc_addr *daddr,
616 				 struct llc_addr *laddr)
617 {
618 	struct sock *sk = __llc_lookup_established(sap, daddr, laddr);
619 
620 	return sk ? : llc_lookup_listener(sap, laddr);
621 }
622 
623 /**
624  *	llc_data_accept_state - designates if in this state data can be sent.
625  *	@state: state of connection.
626  *
627  *	Returns 0 if data can be sent, 1 otherwise.
628  */
llc_data_accept_state(u8 state)629 u8 llc_data_accept_state(u8 state)
630 {
631 	return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
632 	       state != LLC_CONN_STATE_REJ;
633 }
634 
635 /**
636  *	llc_find_next_offset - finds offset for next category of transitions
637  *	@state: state table.
638  *	@offset: start offset.
639  *
640  *	Finds offset of next category of transitions in transition table.
641  *	Returns the start index of next category.
642  */
llc_find_next_offset(struct llc_conn_state * state,u16 offset)643 static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
644 {
645 	u16 cnt = 0;
646 	struct llc_conn_state_trans **next_trans;
647 
648 	for (next_trans = state->transitions + offset;
649 	     (*next_trans)->ev; next_trans++)
650 		++cnt;
651 	return cnt;
652 }
653 
654 /**
655  *	llc_build_offset_table - builds offset table of connection
656  *
657  *	Fills offset table of connection state transition table
658  *	(llc_offset_table).
659  */
llc_build_offset_table(void)660 void __init llc_build_offset_table(void)
661 {
662 	struct llc_conn_state *curr_state;
663 	int state, ev_type, next_offset;
664 
665 	for (state = 0; state < NBR_CONN_STATES; state++) {
666 		curr_state = &llc_conn_state_table[state];
667 		next_offset = 0;
668 		for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
669 			llc_offset_table[state][ev_type] = next_offset;
670 			next_offset += llc_find_next_offset(curr_state,
671 							    next_offset) + 1;
672 		}
673 	}
674 }
675 
676 /**
677  *	llc_find_offset - finds start offset of category of transitions
678  *	@state: state of connection
679  *	@ev_type: type of happened event
680  *
681  *	Finds start offset of desired category of transitions. Returns the
682  *	desired start offset.
683  */
llc_find_offset(int state,int ev_type)684 static int llc_find_offset(int state, int ev_type)
685 {
686 	int rc = 0;
687 	/* at this stage, llc_offset_table[..][2] is not important. it is for
688 	 * init_pf_cycle and I don't know what is it.
689 	 */
690 	switch (ev_type) {
691 	case LLC_CONN_EV_TYPE_PRIM:
692 		rc = llc_offset_table[state][0]; break;
693 	case LLC_CONN_EV_TYPE_PDU:
694 		rc = llc_offset_table[state][4]; break;
695 	case LLC_CONN_EV_TYPE_SIMPLE:
696 		rc = llc_offset_table[state][1]; break;
697 	case LLC_CONN_EV_TYPE_P_TMR:
698 	case LLC_CONN_EV_TYPE_ACK_TMR:
699 	case LLC_CONN_EV_TYPE_REJ_TMR:
700 	case LLC_CONN_EV_TYPE_BUSY_TMR:
701 		rc = llc_offset_table[state][3]; break;
702 	}
703 	return rc;
704 }
705 
706 /**
707  *	llc_sap_add_socket - adds a socket to a SAP
708  *	@sap: SAP
709  *	@sk: socket
710  *
711  *	This function adds a socket to the hash tables of a SAP.
712  */
llc_sap_add_socket(struct llc_sap * sap,struct sock * sk)713 void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
714 {
715 	struct llc_sock *llc = llc_sk(sk);
716 	struct hlist_head *dev_hb = llc_sk_dev_hash(sap, llc->dev->ifindex);
717 	struct hlist_nulls_head *laddr_hb = llc_sk_laddr_hash(sap, &llc->laddr);
718 
719 	llc_sap_hold(sap);
720 	llc_sk(sk)->sap = sap;
721 
722 	spin_lock_bh(&sap->sk_lock);
723 	sap->sk_count++;
724 	sk_nulls_add_node_rcu(sk, laddr_hb);
725 	hlist_add_head(&llc->dev_hash_node, dev_hb);
726 	spin_unlock_bh(&sap->sk_lock);
727 }
728 
729 /**
730  *	llc_sap_remove_socket - removes a socket from SAP
731  *	@sap: SAP
732  *	@sk: socket
733  *
734  *	This function removes a connection from the hash tables of a SAP if
735  *	the connection was in this list.
736  */
llc_sap_remove_socket(struct llc_sap * sap,struct sock * sk)737 void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
738 {
739 	struct llc_sock *llc = llc_sk(sk);
740 
741 	spin_lock_bh(&sap->sk_lock);
742 	sk_nulls_del_node_init_rcu(sk);
743 	hlist_del(&llc->dev_hash_node);
744 	sap->sk_count--;
745 	spin_unlock_bh(&sap->sk_lock);
746 	llc_sap_put(sap);
747 }
748 
749 /**
750  *	llc_conn_rcv - sends received pdus to the connection state machine
751  *	@sk: current connection structure.
752  *	@skb: received frame.
753  *
754  *	Sends received pdus to the connection state machine.
755  */
llc_conn_rcv(struct sock * sk,struct sk_buff * skb)756 static int llc_conn_rcv(struct sock* sk, struct sk_buff *skb)
757 {
758 	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
759 
760 	ev->type   = LLC_CONN_EV_TYPE_PDU;
761 	ev->reason = 0;
762 	return llc_conn_state_process(sk, skb);
763 }
764 
llc_create_incoming_sock(struct sock * sk,struct net_device * dev,struct llc_addr * saddr,struct llc_addr * daddr)765 static struct sock *llc_create_incoming_sock(struct sock *sk,
766 					     struct net_device *dev,
767 					     struct llc_addr *saddr,
768 					     struct llc_addr *daddr)
769 {
770 	struct sock *newsk = llc_sk_alloc(sock_net(sk), sk->sk_family, GFP_ATOMIC,
771 					  sk->sk_prot);
772 	struct llc_sock *newllc, *llc = llc_sk(sk);
773 
774 	if (!newsk)
775 		goto out;
776 	newllc = llc_sk(newsk);
777 	memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
778 	memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
779 	newllc->dev = dev;
780 	dev_hold(dev);
781 	llc_sap_add_socket(llc->sap, newsk);
782 	llc_sap_hold(llc->sap);
783 out:
784 	return newsk;
785 }
786 
llc_conn_handler(struct llc_sap * sap,struct sk_buff * skb)787 void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
788 {
789 	struct llc_addr saddr, daddr;
790 	struct sock *sk;
791 
792 	llc_pdu_decode_sa(skb, saddr.mac);
793 	llc_pdu_decode_ssap(skb, &saddr.lsap);
794 	llc_pdu_decode_da(skb, daddr.mac);
795 	llc_pdu_decode_dsap(skb, &daddr.lsap);
796 
797 	sk = __llc_lookup(sap, &saddr, &daddr);
798 	if (!sk)
799 		goto drop;
800 
801 	bh_lock_sock(sk);
802 	/*
803 	 * This has to be done here and not at the upper layer ->accept
804 	 * method because of the way the PROCOM state machine works:
805 	 * it needs to set several state variables (see, for instance,
806 	 * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
807 	 * the originator of the new connection, and this state has to be
808 	 * in the newly created struct sock private area. -acme
809 	 */
810 	if (unlikely(sk->sk_state == TCP_LISTEN)) {
811 		struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
812 							      &saddr, &daddr);
813 		if (!newsk)
814 			goto drop_unlock;
815 		skb_set_owner_r(skb, newsk);
816 	} else {
817 		/*
818 		 * Can't be skb_set_owner_r, this will be done at the
819 		 * llc_conn_state_process function, later on, when we will use
820 		 * skb_queue_rcv_skb to send it to upper layers, this is
821 		 * another trick required to cope with how the PROCOM state
822 		 * machine works. -acme
823 		 */
824 		skb->sk = sk;
825 	}
826 	if (!sock_owned_by_user(sk))
827 		llc_conn_rcv(sk, skb);
828 	else {
829 		dprintk("%s: adding to backlog...\n", __func__);
830 		llc_set_backlog_type(skb, LLC_PACKET);
831 		if (sk_add_backlog(sk, skb))
832 			goto drop_unlock;
833 	}
834 out:
835 	bh_unlock_sock(sk);
836 	sock_put(sk);
837 	return;
838 drop:
839 	kfree_skb(skb);
840 	return;
841 drop_unlock:
842 	kfree_skb(skb);
843 	goto out;
844 }
845 
846 #undef LLC_REFCNT_DEBUG
847 #ifdef LLC_REFCNT_DEBUG
848 static atomic_t llc_sock_nr;
849 #endif
850 
851 /**
852  *	llc_backlog_rcv - Processes rx frames and expired timers.
853  *	@sk: LLC sock (p8022 connection)
854  *	@skb: queued rx frame or event
855  *
856  *	This function processes frames that has received and timers that has
857  *	expired during sending an I pdu (refer to data_req_handler).  frames
858  *	queue by llc_rcv function (llc_mac.c) and timers queue by timer
859  *	callback functions(llc_c_ac.c).
860  */
llc_backlog_rcv(struct sock * sk,struct sk_buff * skb)861 static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
862 {
863 	int rc = 0;
864 	struct llc_sock *llc = llc_sk(sk);
865 
866 	if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
867 		if (likely(llc->state > 1)) /* not closed */
868 			rc = llc_conn_rcv(sk, skb);
869 		else
870 			goto out_kfree_skb;
871 	} else if (llc_backlog_type(skb) == LLC_EVENT) {
872 		/* timer expiration event */
873 		if (likely(llc->state > 1))  /* not closed */
874 			rc = llc_conn_state_process(sk, skb);
875 		else
876 			goto out_kfree_skb;
877 	} else {
878 		printk(KERN_ERR "%s: invalid skb in backlog\n", __func__);
879 		goto out_kfree_skb;
880 	}
881 out:
882 	return rc;
883 out_kfree_skb:
884 	kfree_skb(skb);
885 	goto out;
886 }
887 
888 /**
889  *     llc_sk_init - Initializes a socket with default llc values.
890  *     @sk: socket to initialize.
891  *
892  *     Initializes a socket with default llc values.
893  */
llc_sk_init(struct sock * sk)894 static void llc_sk_init(struct sock* sk)
895 {
896 	struct llc_sock *llc = llc_sk(sk);
897 
898 	llc->state    = LLC_CONN_STATE_ADM;
899 	llc->inc_cntr = llc->dec_cntr = 2;
900 	llc->dec_step = llc->connect_step = 1;
901 
902 	setup_timer(&llc->ack_timer.timer, llc_conn_ack_tmr_cb,
903 			(unsigned long)sk);
904 	llc->ack_timer.expire	      = sysctl_llc2_ack_timeout;
905 
906 	setup_timer(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb,
907 			(unsigned long)sk);
908 	llc->pf_cycle_timer.expire	   = sysctl_llc2_p_timeout;
909 
910 	setup_timer(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb,
911 			(unsigned long)sk);
912 	llc->rej_sent_timer.expire	   = sysctl_llc2_rej_timeout;
913 
914 	setup_timer(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb,
915 			(unsigned long)sk);
916 	llc->busy_state_timer.expire	     = sysctl_llc2_busy_timeout;
917 
918 	llc->n2 = 2;   /* max retransmit */
919 	llc->k  = 2;   /* tx win size, will adjust dynam */
920 	llc->rw = 128; /* rx win size (opt and equal to
921 			* tx_win of remote LLC) */
922 	skb_queue_head_init(&llc->pdu_unack_q);
923 	sk->sk_backlog_rcv = llc_backlog_rcv;
924 }
925 
926 /**
927  *	llc_sk_alloc - Allocates LLC sock
928  *	@family: upper layer protocol family
929  *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
930  *
931  *	Allocates a LLC sock and initializes it. Returns the new LLC sock
932  *	or %NULL if there's no memory available for one
933  */
llc_sk_alloc(struct net * net,int family,gfp_t priority,struct proto * prot)934 struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
935 {
936 	struct sock *sk = sk_alloc(net, family, priority, prot);
937 
938 	if (!sk)
939 		goto out;
940 	llc_sk_init(sk);
941 	sock_init_data(NULL, sk);
942 #ifdef LLC_REFCNT_DEBUG
943 	atomic_inc(&llc_sock_nr);
944 	printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
945 		__func__, atomic_read(&llc_sock_nr));
946 #endif
947 out:
948 	return sk;
949 }
950 
951 /**
952  *	llc_sk_free - Frees a LLC socket
953  *	@sk - socket to free
954  *
955  *	Frees a LLC socket
956  */
llc_sk_free(struct sock * sk)957 void llc_sk_free(struct sock *sk)
958 {
959 	struct llc_sock *llc = llc_sk(sk);
960 
961 	llc->state = LLC_CONN_OUT_OF_SVC;
962 	/* Stop all (possibly) running timers */
963 	llc_conn_ac_stop_all_timers(sk, NULL);
964 #ifdef DEBUG_LLC_CONN_ALLOC
965 	printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
966 		skb_queue_len(&llc->pdu_unack_q),
967 		skb_queue_len(&sk->sk_write_queue));
968 #endif
969 	skb_queue_purge(&sk->sk_receive_queue);
970 	skb_queue_purge(&sk->sk_write_queue);
971 	skb_queue_purge(&llc->pdu_unack_q);
972 #ifdef LLC_REFCNT_DEBUG
973 	if (atomic_read(&sk->sk_refcnt) != 1) {
974 		printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
975 			sk, __func__, atomic_read(&sk->sk_refcnt));
976 		printk(KERN_DEBUG "%d LLC sockets are still alive\n",
977 			atomic_read(&llc_sock_nr));
978 	} else {
979 		atomic_dec(&llc_sock_nr);
980 		printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
981 			__func__, atomic_read(&llc_sock_nr));
982 	}
983 #endif
984 	sock_put(sk);
985 }
986 
987 /**
988  *	llc_sk_reset - resets a connection
989  *	@sk: LLC socket to reset
990  *
991  *	Resets a connection to the out of service state. Stops its timers
992  *	and frees any frames in the queues of the connection.
993  */
llc_sk_reset(struct sock * sk)994 void llc_sk_reset(struct sock *sk)
995 {
996 	struct llc_sock *llc = llc_sk(sk);
997 
998 	llc_conn_ac_stop_all_timers(sk, NULL);
999 	skb_queue_purge(&sk->sk_write_queue);
1000 	skb_queue_purge(&llc->pdu_unack_q);
1001 	llc->remote_busy_flag	= 0;
1002 	llc->cause_flag		= 0;
1003 	llc->retry_count	= 0;
1004 	llc_conn_set_p_flag(sk, 0);
1005 	llc->f_flag		= 0;
1006 	llc->s_flag		= 0;
1007 	llc->ack_pf		= 0;
1008 	llc->first_pdu_Ns	= 0;
1009 	llc->ack_must_be_send	= 0;
1010 	llc->dec_step		= 1;
1011 	llc->inc_cntr		= 2;
1012 	llc->dec_cntr		= 2;
1013 	llc->X			= 0;
1014 	llc->failed_data_req	= 0 ;
1015 	llc->last_nr		= 0;
1016 }
1017