xref: /openbmc/linux/net/llc/llc_sap.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 
27 /**
28  *	llc_alloc_frame - allocates sk_buff for frame
29  *	@dev: network device this skb will be sent over
30  *
31  *	Allocates an sk_buff for frame and initializes sk_buff fields.
32  *	Returns allocated skb or %NULL when out of memory.
33  */
34 struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev)
35 {
36 	struct sk_buff *skb = alloc_skb(128, GFP_ATOMIC);
37 
38 	if (skb) {
39 		skb_reset_mac_header(skb);
40 		skb_reserve(skb, 50);
41 		skb_reset_network_header(skb);
42 		skb_reset_transport_header(skb);
43 		skb->protocol = htons(ETH_P_802_2);
44 		skb->dev      = dev;
45 		if (sk != NULL)
46 			skb_set_owner_w(skb, sk);
47 	}
48 	return skb;
49 }
50 
51 void llc_save_primitive(struct sock *sk, struct sk_buff* skb, u8 prim)
52 {
53 	struct sockaddr_llc *addr;
54 
55        /* save primitive for use by the user. */
56 	addr		  = llc_ui_skb_cb(skb);
57 
58 	memset(addr, 0, sizeof(*addr));
59 	addr->sllc_family = sk->sk_family;
60 	addr->sllc_arphrd = skb->dev->type;
61 	addr->sllc_test   = prim == LLC_TEST_PRIM;
62 	addr->sllc_xid    = prim == LLC_XID_PRIM;
63 	addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
64 	llc_pdu_decode_sa(skb, addr->sllc_mac);
65 	llc_pdu_decode_ssap(skb, &addr->sllc_sap);
66 }
67 
68 /**
69  *	llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
70  *	@sap: pointer to SAP
71  *	@skb: received pdu
72  */
73 void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
74 {
75 	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
76 	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
77 
78 	switch (LLC_U_PDU_RSP(pdu)) {
79 	case LLC_1_PDU_CMD_TEST:
80 		ev->prim = LLC_TEST_PRIM;	break;
81 	case LLC_1_PDU_CMD_XID:
82 		ev->prim = LLC_XID_PRIM;	break;
83 	case LLC_1_PDU_CMD_UI:
84 		ev->prim = LLC_DATAUNIT_PRIM;	break;
85 	}
86 	ev->ind_cfm_flag = LLC_IND;
87 }
88 
89 /**
90  *	llc_find_sap_trans - finds transition for event
91  *	@sap: pointer to SAP
92  *	@skb: happened event
93  *
94  *	This function finds transition that matches with happened event.
95  *	Returns the pointer to found transition on success or %NULL for
96  *	failure.
97  */
98 static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
99 						      struct sk_buff* skb)
100 {
101 	int i = 0;
102 	struct llc_sap_state_trans *rc = NULL;
103 	struct llc_sap_state_trans **next_trans;
104 	struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
105 	/*
106 	 * Search thru events for this state until list exhausted or until
107 	 * its obvious the event is not valid for the current state
108 	 */
109 	for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
110 		if (!next_trans[i]->ev(sap, skb)) {
111 			rc = next_trans[i]; /* got event match; return it */
112 			break;
113 		}
114 	return rc;
115 }
116 
117 /**
118  *	llc_exec_sap_trans_actions - execute actions related to event
119  *	@sap: pointer to SAP
120  *	@trans: pointer to transition that it's actions must be performed
121  *	@skb: happened event.
122  *
123  *	This function executes actions that is related to happened event.
124  *	Returns 0 for success and 1 for failure of at least one action.
125  */
126 static int llc_exec_sap_trans_actions(struct llc_sap *sap,
127 				      struct llc_sap_state_trans *trans,
128 				      struct sk_buff *skb)
129 {
130 	int rc = 0;
131 	llc_sap_action_t *next_action = trans->ev_actions;
132 
133 	for (; next_action && *next_action; next_action++)
134 		if ((*next_action)(sap, skb))
135 			rc = 1;
136 	return rc;
137 }
138 
139 /**
140  *	llc_sap_next_state - finds transition, execs actions & change SAP state
141  *	@sap: pointer to SAP
142  *	@skb: happened event
143  *
144  *	This function finds transition that matches with happened event, then
145  *	executes related actions and finally changes state of SAP. It returns
146  *	0 on success and 1 for failure.
147  */
148 static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
149 {
150 	int rc = 1;
151 	struct llc_sap_state_trans *trans;
152 
153 	if (sap->state > LLC_NR_SAP_STATES)
154 		goto out;
155 	trans = llc_find_sap_trans(sap, skb);
156 	if (!trans)
157 		goto out;
158 	/*
159 	 * Got the state to which we next transition; perform the actions
160 	 * associated with this transition before actually transitioning to the
161 	 * next state
162 	 */
163 	rc = llc_exec_sap_trans_actions(sap, trans, skb);
164 	if (rc)
165 		goto out;
166 	/*
167 	 * Transition SAP to next state if all actions execute successfully
168 	 */
169 	sap->state = trans->next_state;
170 out:
171 	return rc;
172 }
173 
174 /**
175  *	llc_sap_state_process - sends event to SAP state machine
176  *	@sap: sap to use
177  *	@skb: pointer to occurred event
178  *
179  *	After executing actions of the event, upper layer will be indicated
180  *	if needed(on receiving an UI frame). sk can be null for the
181  *	datalink_proto case.
182  */
183 static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
184 {
185 	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
186 
187 	/*
188 	 * We have to hold the skb, because llc_sap_next_state
189 	 * will kfree it in the sending path and we need to
190 	 * look at the skb->cb, where we encode llc_sap_state_ev.
191 	 */
192 	skb_get(skb);
193 	ev->ind_cfm_flag = 0;
194 	llc_sap_next_state(sap, skb);
195 	if (ev->ind_cfm_flag == LLC_IND) {
196 		if (skb->sk->sk_state == TCP_LISTEN)
197 			kfree_skb(skb);
198 		else {
199 			llc_save_primitive(skb->sk, skb, ev->prim);
200 
201 			/* queue skb to the user. */
202 			if (sock_queue_rcv_skb(skb->sk, skb))
203 				kfree_skb(skb);
204 		}
205 	}
206 	kfree_skb(skb);
207 }
208 
209 /**
210  *	llc_build_and_send_test_pkt - TEST interface for upper layers.
211  *	@sap: sap to use
212  *	@skb: packet to send
213  *	@dmac: destination mac address
214  *	@dsap: destination sap
215  *
216  *	This function is called when upper layer wants to send a TEST pdu.
217  *	Returns 0 for success, 1 otherwise.
218  */
219 void llc_build_and_send_test_pkt(struct llc_sap *sap,
220 				 struct sk_buff *skb, u8 *dmac, u8 dsap)
221 {
222 	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
223 
224 	ev->saddr.lsap = sap->laddr.lsap;
225 	ev->daddr.lsap = dsap;
226 	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
227 	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
228 
229 	ev->type      = LLC_SAP_EV_TYPE_PRIM;
230 	ev->prim      = LLC_TEST_PRIM;
231 	ev->prim_type = LLC_PRIM_TYPE_REQ;
232 	llc_sap_state_process(sap, skb);
233 }
234 
235 /**
236  *	llc_build_and_send_xid_pkt - XID interface for upper layers
237  *	@sap: sap to use
238  *	@skb: packet to send
239  *	@dmac: destination mac address
240  *	@dsap: destination sap
241  *
242  *	This function is called when upper layer wants to send a XID pdu.
243  *	Returns 0 for success, 1 otherwise.
244  */
245 void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
246 				u8 *dmac, u8 dsap)
247 {
248 	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
249 
250 	ev->saddr.lsap = sap->laddr.lsap;
251 	ev->daddr.lsap = dsap;
252 	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
253 	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
254 
255 	ev->type      = LLC_SAP_EV_TYPE_PRIM;
256 	ev->prim      = LLC_XID_PRIM;
257 	ev->prim_type = LLC_PRIM_TYPE_REQ;
258 	llc_sap_state_process(sap, skb);
259 }
260 
261 /**
262  *	llc_sap_rcv - sends received pdus to the sap state machine
263  *	@sap: current sap component structure.
264  *	@skb: received frame.
265  *
266  *	Sends received pdus to the sap state machine.
267  */
268 static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb)
269 {
270 	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
271 
272 	ev->type   = LLC_SAP_EV_TYPE_PDU;
273 	ev->reason = 0;
274 	llc_sap_state_process(sap, skb);
275 }
276 
277 /**
278  *	llc_lookup_dgram - Finds dgram socket for the local sap/mac
279  *	@sap: SAP
280  *	@laddr: address of local LLC (MAC + SAP)
281  *
282  *	Search socket list of the SAP and finds connection using the local
283  *	mac, and local sap. Returns pointer for socket found, %NULL otherwise.
284  */
285 static struct sock *llc_lookup_dgram(struct llc_sap *sap,
286 				     const struct llc_addr *laddr)
287 {
288 	struct sock *rc;
289 	struct hlist_node *node;
290 
291 	read_lock_bh(&sap->sk_list.lock);
292 	sk_for_each(rc, node, &sap->sk_list.list) {
293 		struct llc_sock *llc = llc_sk(rc);
294 
295 		if (rc->sk_type == SOCK_DGRAM &&
296 		    llc->laddr.lsap == laddr->lsap &&
297 		    llc_mac_match(llc->laddr.mac, laddr->mac)) {
298 			sock_hold(rc);
299 			goto found;
300 		}
301 	}
302 	rc = NULL;
303 found:
304 	read_unlock_bh(&sap->sk_list.lock);
305 	return rc;
306 }
307 
308 /**
309  * 	llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
310  *	@sap: SAP
311  *	@laddr: address of local LLC (MAC + SAP)
312  *
313  *	Search socket list of the SAP and finds connections with same sap.
314  *	Deliver clone to each.
315  */
316 static void llc_sap_mcast(struct llc_sap *sap,
317 			  const struct llc_addr *laddr,
318 			  struct sk_buff *skb)
319 {
320 	struct sock *sk;
321 	struct hlist_node *node;
322 
323 	read_lock_bh(&sap->sk_list.lock);
324 	sk_for_each(sk, node, &sap->sk_list.list) {
325 		struct llc_sock *llc = llc_sk(sk);
326 		struct sk_buff *skb1;
327 
328 		if (sk->sk_type != SOCK_DGRAM)
329 			continue;
330 
331 		if (llc->laddr.lsap != laddr->lsap)
332 			continue;
333 
334 		if (llc->dev != skb->dev)
335 			continue;
336 
337 		skb1 = skb_clone(skb, GFP_ATOMIC);
338 		if (!skb1)
339 			break;
340 
341 		sock_hold(sk);
342 		skb_set_owner_r(skb1, sk);
343 		llc_sap_rcv(sap, skb1);
344 		sock_put(sk);
345 	}
346 	read_unlock_bh(&sap->sk_list.lock);
347 }
348 
349 
350 void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
351 {
352 	struct llc_addr laddr;
353 
354 	llc_pdu_decode_da(skb, laddr.mac);
355 	llc_pdu_decode_dsap(skb, &laddr.lsap);
356 
357 	if (llc_mac_multicast(laddr.mac)) {
358 		llc_sap_mcast(sap, &laddr, skb);
359 		kfree_skb(skb);
360 	} else {
361 		struct sock *sk = llc_lookup_dgram(sap, &laddr);
362 		if (sk) {
363 			skb_set_owner_r(skb, sk);
364 			llc_sap_rcv(sap, skb);
365 			sock_put(sk);
366 		} else
367 			kfree_skb(skb);
368 	}
369 }
370