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v6.2
  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}
v6.13.7
  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 const struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
118							    struct sk_buff *skb)
119{
120	int i = 0;
121	const struct llc_sap_state_trans *rc = NULL;
122	const 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				      const 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	const struct llc_sap_state_trans *trans;
170	int rc = 1;
 
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				   const struct net *net)
299{
300     struct llc_sock *llc = llc_sk(sk);
301
302     return sk->sk_type == SOCK_DGRAM &&
303	     net_eq(sock_net(sk), net) &&
304	     llc->laddr.lsap == laddr->lsap &&
305	     ether_addr_equal(llc->laddr.mac, laddr->mac);
306}
307
308/**
309 *	llc_lookup_dgram - Finds dgram socket for the local sap/mac
310 *	@sap: SAP
311 *	@laddr: address of local LLC (MAC + SAP)
312 *	@net: netns to look up a socket in
313 *
314 *	Search socket list of the SAP and finds connection using the local
315 *	mac, and local sap. Returns pointer for socket found, %NULL otherwise.
316 */
317static struct sock *llc_lookup_dgram(struct llc_sap *sap,
318				     const struct llc_addr *laddr,
319				     const struct net *net)
320{
321	struct sock *rc;
322	struct hlist_nulls_node *node;
323	int slot = llc_sk_laddr_hashfn(sap, laddr);
324	struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
325
326	rcu_read_lock_bh();
327again:
328	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
329		if (llc_dgram_match(sap, laddr, rc, net)) {
330			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
331			if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
332				goto again;
333			if (unlikely(llc_sk(rc)->sap != sap ||
334				     !llc_dgram_match(sap, laddr, rc, net))) {
335				sock_put(rc);
336				continue;
337			}
338			goto found;
339		}
340	}
341	rc = NULL;
342	/*
343	 * if the nulls value we got at the end of this lookup is
344	 * not the expected one, we must restart lookup.
345	 * We probably met an item that was moved to another chain.
346	 */
347	if (unlikely(get_nulls_value(node) != slot))
348		goto again;
349found:
350	rcu_read_unlock_bh();
351	return rc;
352}
353
354static inline bool llc_mcast_match(const struct llc_sap *sap,
355				   const struct llc_addr *laddr,
356				   const struct sk_buff *skb,
357				   const struct sock *sk)
358{
359     struct llc_sock *llc = llc_sk(sk);
360
361     return sk->sk_type == SOCK_DGRAM &&
362	  llc->laddr.lsap == laddr->lsap &&
363	  llc->dev == skb->dev;
364}
365
366static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
367			 struct sock **stack, int count)
368{
369	struct sk_buff *skb1;
370	int i;
371
372	for (i = 0; i < count; i++) {
373		skb1 = skb_clone(skb, GFP_ATOMIC);
374		if (!skb1) {
375			sock_put(stack[i]);
376			continue;
377		}
378
379		llc_sap_rcv(sap, skb1, stack[i]);
380		sock_put(stack[i]);
381	}
382}
383
384/**
385 * 	llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
386 *	@sap: SAP
387 *	@laddr: address of local LLC (MAC + SAP)
388 *	@skb: PDU to deliver
389 *
390 *	Search socket list of the SAP and finds connections with same sap.
391 *	Deliver clone to each.
392 */
393static void llc_sap_mcast(struct llc_sap *sap,
394			  const struct llc_addr *laddr,
395			  struct sk_buff *skb)
396{
397	int i = 0;
398	struct sock *sk;
399	struct sock *stack[256 / sizeof(struct sock *)];
400	struct llc_sock *llc;
401	struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
402
403	spin_lock_bh(&sap->sk_lock);
404	hlist_for_each_entry(llc, dev_hb, dev_hash_node) {
405
406		sk = &llc->sk;
407
408		if (!llc_mcast_match(sap, laddr, skb, sk))
409			continue;
410
411		sock_hold(sk);
412		if (i < ARRAY_SIZE(stack))
413			stack[i++] = sk;
414		else {
415			llc_do_mcast(sap, skb, stack, i);
416			i = 0;
417		}
418	}
419	spin_unlock_bh(&sap->sk_lock);
420
421	llc_do_mcast(sap, skb, stack, i);
422}
423
424
425void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
426{
427	struct llc_addr laddr;
428
429	llc_pdu_decode_da(skb, laddr.mac);
430	llc_pdu_decode_dsap(skb, &laddr.lsap);
431
432	if (is_multicast_ether_addr(laddr.mac)) {
433		llc_sap_mcast(sap, &laddr, skb);
434		kfree_skb(skb);
435	} else {
436		struct sock *sk = llc_lookup_dgram(sap, &laddr, dev_net(skb->dev));
437		if (sk) {
438			llc_sap_rcv(sap, skb, sk);
439			sock_put(sk);
440		} else
441			kfree_skb(skb);
442	}
443}