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v3.1
  1/*
  2 * llc_sap.c - driver routines for SAP 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 <net/llc.h>
 16#include <net/llc_if.h>
 17#include <net/llc_conn.h>
 18#include <net/llc_pdu.h>
 19#include <net/llc_sap.h>
 20#include <net/llc_s_ac.h>
 21#include <net/llc_s_ev.h>
 22#include <net/llc_s_st.h>
 23#include <net/sock.h>
 24#include <net/tcp_states.h>
 25#include <linux/llc.h>
 26#include <linux/slab.h>
 27
 28static int llc_mac_header_len(unsigned short devtype)
 29{
 30	switch (devtype) {
 31	case ARPHRD_ETHER:
 32	case ARPHRD_LOOPBACK:
 33		return sizeof(struct ethhdr);
 34#if defined(CONFIG_TR) || defined(CONFIG_TR_MODULE)
 35	case ARPHRD_IEEE802_TR:
 36		return sizeof(struct trh_hdr);
 37#endif
 38	}
 39	return 0;
 40}
 41
 42/**
 43 *	llc_alloc_frame - allocates sk_buff for frame
 
 44 *	@dev: network device this skb will be sent over
 45 *	@type: pdu type to allocate
 46 *	@data_size: data size to allocate
 47 *
 48 *	Allocates an sk_buff for frame and initializes sk_buff fields.
 49 *	Returns allocated skb or %NULL when out of memory.
 50 */
 51struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev,
 52				u8 type, u32 data_size)
 53{
 54	int hlen = type == LLC_PDU_TYPE_U ? 3 : 4;
 55	struct sk_buff *skb;
 56
 57	hlen += llc_mac_header_len(dev->type);
 58	skb = alloc_skb(hlen + data_size, GFP_ATOMIC);
 59
 60	if (skb) {
 61		skb_reset_mac_header(skb);
 62		skb_reserve(skb, hlen);
 63		skb_reset_network_header(skb);
 64		skb_reset_transport_header(skb);
 65		skb->protocol = htons(ETH_P_802_2);
 66		skb->dev      = dev;
 67		if (sk != NULL)
 68			skb_set_owner_w(skb, sk);
 69	}
 70	return skb;
 71}
 72
 73void llc_save_primitive(struct sock *sk, struct sk_buff* skb, u8 prim)
 74{
 75	struct sockaddr_llc *addr;
 76
 77       /* save primitive for use by the user. */
 78	addr		  = llc_ui_skb_cb(skb);
 79
 80	memset(addr, 0, sizeof(*addr));
 81	addr->sllc_family = sk->sk_family;
 82	addr->sllc_arphrd = skb->dev->type;
 83	addr->sllc_test   = prim == LLC_TEST_PRIM;
 84	addr->sllc_xid    = prim == LLC_XID_PRIM;
 85	addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
 86	llc_pdu_decode_sa(skb, addr->sllc_mac);
 87	llc_pdu_decode_ssap(skb, &addr->sllc_sap);
 88}
 89
 90/**
 91 *	llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
 92 *	@sap: pointer to SAP
 93 *	@skb: received pdu
 94 */
 95void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
 96{
 97	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 98	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 99
100	switch (LLC_U_PDU_RSP(pdu)) {
101	case LLC_1_PDU_CMD_TEST:
102		ev->prim = LLC_TEST_PRIM;	break;
103	case LLC_1_PDU_CMD_XID:
104		ev->prim = LLC_XID_PRIM;	break;
105	case LLC_1_PDU_CMD_UI:
106		ev->prim = LLC_DATAUNIT_PRIM;	break;
107	}
108	ev->ind_cfm_flag = LLC_IND;
109}
110
111/**
112 *	llc_find_sap_trans - finds transition for event
113 *	@sap: pointer to SAP
114 *	@skb: happened event
115 *
116 *	This function finds transition that matches with happened event.
117 *	Returns the pointer to found transition on success or %NULL for
118 *	failure.
119 */
120static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
121						      struct sk_buff* skb)
122{
123	int i = 0;
124	struct llc_sap_state_trans *rc = NULL;
125	struct llc_sap_state_trans **next_trans;
126	struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
127	/*
128	 * Search thru events for this state until list exhausted or until
129	 * its obvious the event is not valid for the current state
130	 */
131	for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
132		if (!next_trans[i]->ev(sap, skb)) {
133			rc = next_trans[i]; /* got event match; return it */
134			break;
135		}
136	return rc;
137}
138
139/**
140 *	llc_exec_sap_trans_actions - execute actions related to event
141 *	@sap: pointer to SAP
142 *	@trans: pointer to transition that it's actions must be performed
143 *	@skb: happened event.
144 *
145 *	This function executes actions that is related to happened event.
146 *	Returns 0 for success and 1 for failure of at least one action.
147 */
148static int llc_exec_sap_trans_actions(struct llc_sap *sap,
149				      struct llc_sap_state_trans *trans,
150				      struct sk_buff *skb)
151{
152	int rc = 0;
153	llc_sap_action_t *next_action = trans->ev_actions;
154
155	for (; next_action && *next_action; next_action++)
156		if ((*next_action)(sap, skb))
157			rc = 1;
158	return rc;
159}
160
161/**
162 *	llc_sap_next_state - finds transition, execs actions & change SAP state
163 *	@sap: pointer to SAP
164 *	@skb: happened event
165 *
166 *	This function finds transition that matches with happened event, then
167 *	executes related actions and finally changes state of SAP. It returns
168 *	0 on success and 1 for failure.
169 */
170static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
171{
172	int rc = 1;
173	struct llc_sap_state_trans *trans;
174
175	if (sap->state > LLC_NR_SAP_STATES)
176		goto out;
177	trans = llc_find_sap_trans(sap, skb);
178	if (!trans)
179		goto out;
180	/*
181	 * Got the state to which we next transition; perform the actions
182	 * associated with this transition before actually transitioning to the
183	 * next state
184	 */
185	rc = llc_exec_sap_trans_actions(sap, trans, skb);
186	if (rc)
187		goto out;
188	/*
189	 * Transition SAP to next state if all actions execute successfully
190	 */
191	sap->state = trans->next_state;
192out:
193	return rc;
194}
195
196/**
197 *	llc_sap_state_process - sends event to SAP state machine
198 *	@sap: sap to use
199 *	@skb: pointer to occurred event
200 *
201 *	After executing actions of the event, upper layer will be indicated
202 *	if needed(on receiving an UI frame). sk can be null for the
203 *	datalink_proto case.
 
 
204 */
205static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
206{
207	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
208
209	/*
210	 * We have to hold the skb, because llc_sap_next_state
211	 * will kfree it in the sending path and we need to
212	 * look at the skb->cb, where we encode llc_sap_state_ev.
213	 */
214	skb_get(skb);
215	ev->ind_cfm_flag = 0;
216	llc_sap_next_state(sap, skb);
217	if (ev->ind_cfm_flag == LLC_IND) {
218		if (skb->sk->sk_state == TCP_LISTEN)
219			kfree_skb(skb);
220		else {
221			llc_save_primitive(skb->sk, skb, ev->prim);
222
223			/* queue skb to the user. */
224			if (sock_queue_rcv_skb(skb->sk, skb))
225				kfree_skb(skb);
226		}
 
 
227	}
228	kfree_skb(skb);
229}
230
231/**
232 *	llc_build_and_send_test_pkt - TEST interface for upper layers.
233 *	@sap: sap to use
234 *	@skb: packet to send
235 *	@dmac: destination mac address
236 *	@dsap: destination sap
237 *
238 *	This function is called when upper layer wants to send a TEST pdu.
239 *	Returns 0 for success, 1 otherwise.
240 */
241void llc_build_and_send_test_pkt(struct llc_sap *sap,
242				 struct sk_buff *skb, u8 *dmac, u8 dsap)
243{
244	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
245
246	ev->saddr.lsap = sap->laddr.lsap;
247	ev->daddr.lsap = dsap;
248	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
249	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
250
251	ev->type      = LLC_SAP_EV_TYPE_PRIM;
252	ev->prim      = LLC_TEST_PRIM;
253	ev->prim_type = LLC_PRIM_TYPE_REQ;
254	llc_sap_state_process(sap, skb);
255}
256
257/**
258 *	llc_build_and_send_xid_pkt - XID interface for upper layers
259 *	@sap: sap to use
260 *	@skb: packet to send
261 *	@dmac: destination mac address
262 *	@dsap: destination sap
263 *
264 *	This function is called when upper layer wants to send a XID pdu.
265 *	Returns 0 for success, 1 otherwise.
266 */
267void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
268				u8 *dmac, u8 dsap)
269{
270	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
271
272	ev->saddr.lsap = sap->laddr.lsap;
273	ev->daddr.lsap = dsap;
274	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
275	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
276
277	ev->type      = LLC_SAP_EV_TYPE_PRIM;
278	ev->prim      = LLC_XID_PRIM;
279	ev->prim_type = LLC_PRIM_TYPE_REQ;
280	llc_sap_state_process(sap, skb);
281}
282
283/**
284 *	llc_sap_rcv - sends received pdus to the sap state machine
285 *	@sap: current sap component structure.
286 *	@skb: received frame.
 
287 *
288 *	Sends received pdus to the sap state machine.
289 */
290static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
291			struct sock *sk)
292{
293	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
294
295	ev->type   = LLC_SAP_EV_TYPE_PDU;
296	ev->reason = 0;
 
 
297	skb->sk = sk;
 
298	llc_sap_state_process(sap, skb);
299}
300
301static inline bool llc_dgram_match(const struct llc_sap *sap,
302				   const struct llc_addr *laddr,
303				   const struct sock *sk)
304{
305     struct llc_sock *llc = llc_sk(sk);
306
307     return sk->sk_type == SOCK_DGRAM &&
308	  llc->laddr.lsap == laddr->lsap &&
309	  llc_mac_match(llc->laddr.mac, laddr->mac);
310}
311
312/**
313 *	llc_lookup_dgram - Finds dgram socket for the local sap/mac
314 *	@sap: SAP
315 *	@laddr: address of local LLC (MAC + SAP)
316 *
317 *	Search socket list of the SAP and finds connection using the local
318 *	mac, and local sap. Returns pointer for socket found, %NULL otherwise.
319 */
320static struct sock *llc_lookup_dgram(struct llc_sap *sap,
321				     const struct llc_addr *laddr)
322{
323	struct sock *rc;
324	struct hlist_nulls_node *node;
325	int slot = llc_sk_laddr_hashfn(sap, laddr);
326	struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
327
328	rcu_read_lock_bh();
329again:
330	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
331		if (llc_dgram_match(sap, laddr, rc)) {
332			/* Extra checks required by SLAB_DESTROY_BY_RCU */
333			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
334				goto again;
335			if (unlikely(llc_sk(rc)->sap != sap ||
336				     !llc_dgram_match(sap, laddr, rc))) {
337				sock_put(rc);
338				continue;
339			}
340			goto found;
341		}
342	}
343	rc = NULL;
344	/*
345	 * if the nulls value we got at the end of this lookup is
346	 * not the expected one, we must restart lookup.
347	 * We probably met an item that was moved to another chain.
348	 */
349	if (unlikely(get_nulls_value(node) != slot))
350		goto again;
351found:
352	rcu_read_unlock_bh();
353	return rc;
354}
355
356static inline bool llc_mcast_match(const struct llc_sap *sap,
357				   const struct llc_addr *laddr,
358				   const struct sk_buff *skb,
359				   const struct sock *sk)
360{
361     struct llc_sock *llc = llc_sk(sk);
362
363     return sk->sk_type == SOCK_DGRAM &&
364	  llc->laddr.lsap == laddr->lsap &&
365	  llc->dev == skb->dev;
366}
367
368static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
369			 struct sock **stack, int count)
370{
371	struct sk_buff *skb1;
372	int i;
373
374	for (i = 0; i < count; i++) {
375		skb1 = skb_clone(skb, GFP_ATOMIC);
376		if (!skb1) {
377			sock_put(stack[i]);
378			continue;
379		}
380
381		llc_sap_rcv(sap, skb1, stack[i]);
382		sock_put(stack[i]);
383	}
384}
385
386/**
387 * 	llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
388 *	@sap: SAP
389 *	@laddr: address of local LLC (MAC + SAP)
 
390 *
391 *	Search socket list of the SAP and finds connections with same sap.
392 *	Deliver clone to each.
393 */
394static void llc_sap_mcast(struct llc_sap *sap,
395			  const struct llc_addr *laddr,
396			  struct sk_buff *skb)
397{
398	int i = 0, count = 256 / sizeof(struct sock *);
399	struct sock *sk, *stack[count];
400	struct hlist_node *node;
401	struct llc_sock *llc;
402	struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
403
404	spin_lock_bh(&sap->sk_lock);
405	hlist_for_each_entry(llc, node, dev_hb, dev_hash_node) {
406
407		sk = &llc->sk;
408
409		if (!llc_mcast_match(sap, laddr, skb, sk))
410			continue;
411
412		sock_hold(sk);
413		if (i < count)
414			stack[i++] = sk;
415		else {
416			llc_do_mcast(sap, skb, stack, i);
417			i = 0;
418		}
419	}
420	spin_unlock_bh(&sap->sk_lock);
421
422	llc_do_mcast(sap, skb, stack, i);
423}
424
425
426void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
427{
428	struct llc_addr laddr;
429
430	llc_pdu_decode_da(skb, laddr.mac);
431	llc_pdu_decode_dsap(skb, &laddr.lsap);
432
433	if (llc_mac_multicast(laddr.mac)) {
434		llc_sap_mcast(sap, &laddr, skb);
435		kfree_skb(skb);
436	} else {
437		struct sock *sk = llc_lookup_dgram(sap, &laddr);
438		if (sk) {
439			llc_sap_rcv(sap, skb, sk);
440			sock_put(sk);
441		} else
442			kfree_skb(skb);
443	}
444}
v5.9
  1/*
  2 * llc_sap.c - driver routines for SAP 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 <net/llc.h>
 16#include <net/llc_if.h>
 17#include <net/llc_conn.h>
 18#include <net/llc_pdu.h>
 19#include <net/llc_sap.h>
 20#include <net/llc_s_ac.h>
 21#include <net/llc_s_ev.h>
 22#include <net/llc_s_st.h>
 23#include <net/sock.h>
 24#include <net/tcp_states.h>
 25#include <linux/llc.h>
 26#include <linux/slab.h>
 27
 28static int llc_mac_header_len(unsigned short devtype)
 29{
 30	switch (devtype) {
 31	case ARPHRD_ETHER:
 32	case ARPHRD_LOOPBACK:
 33		return sizeof(struct ethhdr);
 
 
 
 
 34	}
 35	return 0;
 36}
 37
 38/**
 39 *	llc_alloc_frame - allocates sk_buff for frame
 40 *	@sk:  socket to allocate frame to
 41 *	@dev: network device this skb will be sent over
 42 *	@type: pdu type to allocate
 43 *	@data_size: data size to allocate
 44 *
 45 *	Allocates an sk_buff for frame and initializes sk_buff fields.
 46 *	Returns allocated skb or %NULL when out of memory.
 47 */
 48struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev,
 49				u8 type, u32 data_size)
 50{
 51	int hlen = type == LLC_PDU_TYPE_U ? 3 : 4;
 52	struct sk_buff *skb;
 53
 54	hlen += llc_mac_header_len(dev->type);
 55	skb = alloc_skb(hlen + data_size, GFP_ATOMIC);
 56
 57	if (skb) {
 58		skb_reset_mac_header(skb);
 59		skb_reserve(skb, hlen);
 60		skb_reset_network_header(skb);
 61		skb_reset_transport_header(skb);
 62		skb->protocol = htons(ETH_P_802_2);
 63		skb->dev      = dev;
 64		if (sk != NULL)
 65			skb_set_owner_w(skb, sk);
 66	}
 67	return skb;
 68}
 69
 70void llc_save_primitive(struct sock *sk, struct sk_buff *skb, u8 prim)
 71{
 72	struct sockaddr_llc *addr;
 73
 74       /* save primitive for use by the user. */
 75	addr		  = llc_ui_skb_cb(skb);
 76
 77	memset(addr, 0, sizeof(*addr));
 78	addr->sllc_family = sk->sk_family;
 79	addr->sllc_arphrd = skb->dev->type;
 80	addr->sllc_test   = prim == LLC_TEST_PRIM;
 81	addr->sllc_xid    = prim == LLC_XID_PRIM;
 82	addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
 83	llc_pdu_decode_sa(skb, addr->sllc_mac);
 84	llc_pdu_decode_ssap(skb, &addr->sllc_sap);
 85}
 86
 87/**
 88 *	llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
 89 *	@sap: pointer to SAP
 90 *	@skb: received pdu
 91 */
 92void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
 93{
 94	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 95	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 96
 97	switch (LLC_U_PDU_RSP(pdu)) {
 98	case LLC_1_PDU_CMD_TEST:
 99		ev->prim = LLC_TEST_PRIM;	break;
100	case LLC_1_PDU_CMD_XID:
101		ev->prim = LLC_XID_PRIM;	break;
102	case LLC_1_PDU_CMD_UI:
103		ev->prim = LLC_DATAUNIT_PRIM;	break;
104	}
105	ev->ind_cfm_flag = LLC_IND;
106}
107
108/**
109 *	llc_find_sap_trans - finds transition for event
110 *	@sap: pointer to SAP
111 *	@skb: happened event
112 *
113 *	This function finds transition that matches with happened event.
114 *	Returns the pointer to found transition on success or %NULL for
115 *	failure.
116 */
117static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
118						      struct sk_buff *skb)
119{
120	int i = 0;
121	struct llc_sap_state_trans *rc = NULL;
122	struct llc_sap_state_trans **next_trans;
123	struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
124	/*
125	 * Search thru events for this state until list exhausted or until
126	 * its obvious the event is not valid for the current state
127	 */
128	for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
129		if (!next_trans[i]->ev(sap, skb)) {
130			rc = next_trans[i]; /* got event match; return it */
131			break;
132		}
133	return rc;
134}
135
136/**
137 *	llc_exec_sap_trans_actions - execute actions related to event
138 *	@sap: pointer to SAP
139 *	@trans: pointer to transition that it's actions must be performed
140 *	@skb: happened event.
141 *
142 *	This function executes actions that is related to happened event.
143 *	Returns 0 for success and 1 for failure of at least one action.
144 */
145static int llc_exec_sap_trans_actions(struct llc_sap *sap,
146				      struct llc_sap_state_trans *trans,
147				      struct sk_buff *skb)
148{
149	int rc = 0;
150	const llc_sap_action_t *next_action = trans->ev_actions;
151
152	for (; next_action && *next_action; next_action++)
153		if ((*next_action)(sap, skb))
154			rc = 1;
155	return rc;
156}
157
158/**
159 *	llc_sap_next_state - finds transition, execs actions & change SAP state
160 *	@sap: pointer to SAP
161 *	@skb: happened event
162 *
163 *	This function finds transition that matches with happened event, then
164 *	executes related actions and finally changes state of SAP. It returns
165 *	0 on success and 1 for failure.
166 */
167static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
168{
169	int rc = 1;
170	struct llc_sap_state_trans *trans;
171
172	if (sap->state > LLC_NR_SAP_STATES)
173		goto out;
174	trans = llc_find_sap_trans(sap, skb);
175	if (!trans)
176		goto out;
177	/*
178	 * Got the state to which we next transition; perform the actions
179	 * associated with this transition before actually transitioning to the
180	 * next state
181	 */
182	rc = llc_exec_sap_trans_actions(sap, trans, skb);
183	if (rc)
184		goto out;
185	/*
186	 * Transition SAP to next state if all actions execute successfully
187	 */
188	sap->state = trans->next_state;
189out:
190	return rc;
191}
192
193/**
194 *	llc_sap_state_process - sends event to SAP state machine
195 *	@sap: sap to use
196 *	@skb: pointer to occurred event
197 *
198 *	After executing actions of the event, upper layer will be indicated
199 *	if needed(on receiving an UI frame). sk can be null for the
200 *	datalink_proto case.
201 *
202 *	This function always consumes a reference to the skb.
203 */
204static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
205{
206	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
207
 
 
 
 
 
 
208	ev->ind_cfm_flag = 0;
209	llc_sap_next_state(sap, skb);
 
 
 
 
 
210
211	if (ev->ind_cfm_flag == LLC_IND && skb->sk->sk_state != TCP_LISTEN) {
212		llc_save_primitive(skb->sk, skb, ev->prim);
213
214		/* queue skb to the user. */
215		if (sock_queue_rcv_skb(skb->sk, skb) == 0)
216			return;
217	}
218	kfree_skb(skb);
219}
220
221/**
222 *	llc_build_and_send_test_pkt - TEST interface for upper layers.
223 *	@sap: sap to use
224 *	@skb: packet to send
225 *	@dmac: destination mac address
226 *	@dsap: destination sap
227 *
228 *	This function is called when upper layer wants to send a TEST pdu.
229 *	Returns 0 for success, 1 otherwise.
230 */
231void llc_build_and_send_test_pkt(struct llc_sap *sap,
232				 struct sk_buff *skb, u8 *dmac, u8 dsap)
233{
234	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
235
236	ev->saddr.lsap = sap->laddr.lsap;
237	ev->daddr.lsap = dsap;
238	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
239	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
240
241	ev->type      = LLC_SAP_EV_TYPE_PRIM;
242	ev->prim      = LLC_TEST_PRIM;
243	ev->prim_type = LLC_PRIM_TYPE_REQ;
244	llc_sap_state_process(sap, skb);
245}
246
247/**
248 *	llc_build_and_send_xid_pkt - XID interface for upper layers
249 *	@sap: sap to use
250 *	@skb: packet to send
251 *	@dmac: destination mac address
252 *	@dsap: destination sap
253 *
254 *	This function is called when upper layer wants to send a XID pdu.
255 *	Returns 0 for success, 1 otherwise.
256 */
257void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
258				u8 *dmac, u8 dsap)
259{
260	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
261
262	ev->saddr.lsap = sap->laddr.lsap;
263	ev->daddr.lsap = dsap;
264	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
265	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
266
267	ev->type      = LLC_SAP_EV_TYPE_PRIM;
268	ev->prim      = LLC_XID_PRIM;
269	ev->prim_type = LLC_PRIM_TYPE_REQ;
270	llc_sap_state_process(sap, skb);
271}
272
273/**
274 *	llc_sap_rcv - sends received pdus to the sap state machine
275 *	@sap: current sap component structure.
276 *	@skb: received frame.
277 *	@sk:  socket to associate to frame
278 *
279 *	Sends received pdus to the sap state machine.
280 */
281static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
282			struct sock *sk)
283{
284	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
285
286	ev->type   = LLC_SAP_EV_TYPE_PDU;
287	ev->reason = 0;
288	skb_orphan(skb);
289	sock_hold(sk);
290	skb->sk = sk;
291	skb->destructor = sock_efree;
292	llc_sap_state_process(sap, skb);
293}
294
295static inline bool llc_dgram_match(const struct llc_sap *sap,
296				   const struct llc_addr *laddr,
297				   const struct sock *sk)
298{
299     struct llc_sock *llc = llc_sk(sk);
300
301     return sk->sk_type == SOCK_DGRAM &&
302	  llc->laddr.lsap == laddr->lsap &&
303	  ether_addr_equal(llc->laddr.mac, laddr->mac);
304}
305
306/**
307 *	llc_lookup_dgram - Finds dgram socket for the local sap/mac
308 *	@sap: SAP
309 *	@laddr: address of local LLC (MAC + SAP)
310 *
311 *	Search socket list of the SAP and finds connection using the local
312 *	mac, and local sap. Returns pointer for socket found, %NULL otherwise.
313 */
314static struct sock *llc_lookup_dgram(struct llc_sap *sap,
315				     const struct llc_addr *laddr)
316{
317	struct sock *rc;
318	struct hlist_nulls_node *node;
319	int slot = llc_sk_laddr_hashfn(sap, laddr);
320	struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
321
322	rcu_read_lock_bh();
323again:
324	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
325		if (llc_dgram_match(sap, laddr, rc)) {
326			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
327			if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
328				goto again;
329			if (unlikely(llc_sk(rc)->sap != sap ||
330				     !llc_dgram_match(sap, laddr, rc))) {
331				sock_put(rc);
332				continue;
333			}
334			goto found;
335		}
336	}
337	rc = NULL;
338	/*
339	 * if the nulls value we got at the end of this lookup is
340	 * not the expected one, we must restart lookup.
341	 * We probably met an item that was moved to another chain.
342	 */
343	if (unlikely(get_nulls_value(node) != slot))
344		goto again;
345found:
346	rcu_read_unlock_bh();
347	return rc;
348}
349
350static inline bool llc_mcast_match(const struct llc_sap *sap,
351				   const struct llc_addr *laddr,
352				   const struct sk_buff *skb,
353				   const struct sock *sk)
354{
355     struct llc_sock *llc = llc_sk(sk);
356
357     return sk->sk_type == SOCK_DGRAM &&
358	  llc->laddr.lsap == laddr->lsap &&
359	  llc->dev == skb->dev;
360}
361
362static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
363			 struct sock **stack, int count)
364{
365	struct sk_buff *skb1;
366	int i;
367
368	for (i = 0; i < count; i++) {
369		skb1 = skb_clone(skb, GFP_ATOMIC);
370		if (!skb1) {
371			sock_put(stack[i]);
372			continue;
373		}
374
375		llc_sap_rcv(sap, skb1, stack[i]);
376		sock_put(stack[i]);
377	}
378}
379
380/**
381 * 	llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
382 *	@sap: SAP
383 *	@laddr: address of local LLC (MAC + SAP)
384 *	@skb: PDU to deliver
385 *
386 *	Search socket list of the SAP and finds connections with same sap.
387 *	Deliver clone to each.
388 */
389static void llc_sap_mcast(struct llc_sap *sap,
390			  const struct llc_addr *laddr,
391			  struct sk_buff *skb)
392{
393	int i = 0;
394	struct sock *sk;
395	struct sock *stack[256 / sizeof(struct sock *)];
396	struct llc_sock *llc;
397	struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
398
399	spin_lock_bh(&sap->sk_lock);
400	hlist_for_each_entry(llc, dev_hb, dev_hash_node) {
401
402		sk = &llc->sk;
403
404		if (!llc_mcast_match(sap, laddr, skb, sk))
405			continue;
406
407		sock_hold(sk);
408		if (i < ARRAY_SIZE(stack))
409			stack[i++] = sk;
410		else {
411			llc_do_mcast(sap, skb, stack, i);
412			i = 0;
413		}
414	}
415	spin_unlock_bh(&sap->sk_lock);
416
417	llc_do_mcast(sap, skb, stack, i);
418}
419
420
421void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
422{
423	struct llc_addr laddr;
424
425	llc_pdu_decode_da(skb, laddr.mac);
426	llc_pdu_decode_dsap(skb, &laddr.lsap);
427
428	if (is_multicast_ether_addr(laddr.mac)) {
429		llc_sap_mcast(sap, &laddr, skb);
430		kfree_skb(skb);
431	} else {
432		struct sock *sk = llc_lookup_dgram(sap, &laddr);
433		if (sk) {
434			llc_sap_rcv(sap, skb, sk);
435			sock_put(sk);
436		} else
437			kfree_skb(skb);
438	}
439}