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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 | |
28 | static 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 | #ifdef CONFIG_TR |
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 | */ |
51 | struct 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 | |
73 | void 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 | */ |
95 | void 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 | */ |
120 | static 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 | */ |
148 | static 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 | */ |
170 | static 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; |
192 | out: |
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 | */ |
205 | static 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 | */ |
241 | void 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 | */ |
267 | void 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 | */ |
290 | static 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 | |
301 | static 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 | */ |
320 | static 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(); |
329 | again: |
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; |
351 | found: |
352 | rcu_read_unlock_bh(); |
353 | return rc; |
354 | } |
355 | |
356 | static 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 | |
368 | static 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 | */ |
394 | static 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 | |
426 | void 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 | } |
445 |
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