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