source: src/linux/universal/linux-3.18/net/llc/llc_sap.c @ 31869

Last change on this file since 31869 was 31869, checked in by brainslayer, 6 weeks ago

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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
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        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 */
201static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
202{
203        struct llc_sap_state_ev *ev = llc_sap_ev(skb);
204
205        /*
206         * We have to hold the skb, because llc_sap_next_state
207         * will kfree it in the sending path and we need to
208         * look at the skb->cb, where we encode llc_sap_state_ev.
209         */
210        skb_get(skb);
211        ev->ind_cfm_flag = 0;
212        llc_sap_next_state(sap, skb);
213        if (ev->ind_cfm_flag == LLC_IND) {
214                if (skb->sk->sk_state == TCP_LISTEN)
215                        kfree_skb(skb);
216                else {
217                        llc_save_primitive(skb->sk, skb, ev->prim);
218
219                        /* queue skb to the user. */
220                        if (sock_queue_rcv_skb(skb->sk, skb))
221                                kfree_skb(skb);
222                }
223        }
224        kfree_skb(skb);
225}
226
227/**
228 *      llc_build_and_send_test_pkt - TEST interface for upper layers.
229 *      @sap: sap to use
230 *      @skb: packet to send
231 *      @dmac: destination mac address
232 *      @dsap: destination sap
233 *
234 *      This function is called when upper layer wants to send a TEST pdu.
235 *      Returns 0 for success, 1 otherwise.
236 */
237void llc_build_and_send_test_pkt(struct llc_sap *sap,
238                                 struct sk_buff *skb, u8 *dmac, u8 dsap)
239{
240        struct llc_sap_state_ev *ev = llc_sap_ev(skb);
241
242        ev->saddr.lsap = sap->laddr.lsap;
243        ev->daddr.lsap = dsap;
244        memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
245        memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
246
247        ev->type      = LLC_SAP_EV_TYPE_PRIM;
248        ev->prim      = LLC_TEST_PRIM;
249        ev->prim_type = LLC_PRIM_TYPE_REQ;
250        llc_sap_state_process(sap, skb);
251}
252
253/**
254 *      llc_build_and_send_xid_pkt - XID interface for upper layers
255 *      @sap: sap to use
256 *      @skb: packet to send
257 *      @dmac: destination mac address
258 *      @dsap: destination sap
259 *
260 *      This function is called when upper layer wants to send a XID pdu.
261 *      Returns 0 for success, 1 otherwise.
262 */
263void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
264                                u8 *dmac, u8 dsap)
265{
266        struct llc_sap_state_ev *ev = llc_sap_ev(skb);
267
268        ev->saddr.lsap = sap->laddr.lsap;
269        ev->daddr.lsap = dsap;
270        memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
271        memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
272
273        ev->type      = LLC_SAP_EV_TYPE_PRIM;
274        ev->prim      = LLC_XID_PRIM;
275        ev->prim_type = LLC_PRIM_TYPE_REQ;
276        llc_sap_state_process(sap, skb);
277}
278
279/**
280 *      llc_sap_rcv - sends received pdus to the sap state machine
281 *      @sap: current sap component structure.
282 *      @skb: received frame.
283 *
284 *      Sends received pdus to the sap state machine.
285 */
286static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
287                        struct sock *sk)
288{
289        struct llc_sap_state_ev *ev = llc_sap_ev(skb);
290
291        ev->type   = LLC_SAP_EV_TYPE_PDU;
292        ev->reason = 0;
293        skb_orphan(skb);
294        sock_hold(sk);
295        skb->sk = sk;
296        skb->destructor = sock_efree;
297        llc_sap_state_process(sap, skb);
298}
299
300static inline bool llc_dgram_match(const struct llc_sap *sap,
301                                   const struct llc_addr *laddr,
302                                   const struct sock *sk)
303{
304     struct llc_sock *llc = llc_sk(sk);
305
306     return sk->sk_type == SOCK_DGRAM &&
307          llc->laddr.lsap == laddr->lsap &&
308          ether_addr_equal(llc->laddr.mac, laddr->mac);
309}
310
311/**
312 *      llc_lookup_dgram - Finds dgram socket for the local sap/mac
313 *      @sap: SAP
314 *      @laddr: address of local LLC (MAC + SAP)
315 *
316 *      Search socket list of the SAP and finds connection using the local
317 *      mac, and local sap. Returns pointer for socket found, %NULL otherwise.
318 */
319static struct sock *llc_lookup_dgram(struct llc_sap *sap,
320                                     const struct llc_addr *laddr)
321{
322        struct sock *rc;
323        struct hlist_nulls_node *node;
324        int slot = llc_sk_laddr_hashfn(sap, laddr);
325        struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
326
327        rcu_read_lock_bh();
328again:
329        sk_nulls_for_each_rcu(rc, node, laddr_hb) {
330                if (llc_dgram_match(sap, laddr, rc)) {
331                        /* Extra checks required by SLAB_DESTROY_BY_RCU */
332                        if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
333                                goto again;
334                        if (unlikely(llc_sk(rc)->sap != sap ||
335                                     !llc_dgram_match(sap, laddr, rc))) {
336                                sock_put(rc);
337                                continue;
338                        }
339                        goto found;
340                }
341        }
342        rc = NULL;
343        /*
344         * if the nulls value we got at the end of this lookup is
345         * not the expected one, we must restart lookup.
346         * We probably met an item that was moved to another chain.
347         */
348        if (unlikely(get_nulls_value(node) != slot))
349                goto again;
350found:
351        rcu_read_unlock_bh();
352        return rc;
353}
354
355static inline bool llc_mcast_match(const struct llc_sap *sap,
356                                   const struct llc_addr *laddr,
357                                   const struct sk_buff *skb,
358                                   const struct sock *sk)
359{
360     struct llc_sock *llc = llc_sk(sk);
361
362     return sk->sk_type == SOCK_DGRAM &&
363          llc->laddr.lsap == laddr->lsap &&
364          llc->dev == skb->dev;
365}
366
367static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
368                         struct sock **stack, int count)
369{
370        struct sk_buff *skb1;
371        int i;
372
373        for (i = 0; i < count; i++) {
374                skb1 = skb_clone(skb, GFP_ATOMIC);
375                if (!skb1) {
376                        sock_put(stack[i]);
377                        continue;
378                }
379
380                llc_sap_rcv(sap, skb1, stack[i]);
381                sock_put(stack[i]);
382        }
383}
384
385/**
386 *      llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
387 *      @sap: SAP
388 *      @laddr: address of local LLC (MAC + SAP)
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, count = 256 / sizeof(struct sock *);
398        struct sock *sk, *stack[count];
399        struct llc_sock *llc;
400        struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
401
402        spin_lock_bh(&sap->sk_lock);
403        hlist_for_each_entry(llc, dev_hb, dev_hash_node) {
404
405                sk = &llc->sk;
406
407                if (!llc_mcast_match(sap, laddr, skb, sk))
408                        continue;
409
410                sock_hold(sk);
411                if (i < count)
412                        stack[i++] = sk;
413                else {
414                        llc_do_mcast(sap, skb, stack, i);
415                        i = 0;
416                }
417        }
418        spin_unlock_bh(&sap->sk_lock);
419
420        llc_do_mcast(sap, skb, stack, i);
421}
422
423
424void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
425{
426        struct llc_addr laddr;
427
428        llc_pdu_decode_da(skb, laddr.mac);
429        llc_pdu_decode_dsap(skb, &laddr.lsap);
430
431        if (is_multicast_ether_addr(laddr.mac)) {
432                llc_sap_mcast(sap, &laddr, skb);
433                kfree_skb(skb);
434        } else {
435                struct sock *sk = llc_lookup_dgram(sap, &laddr);
436                if (sk) {
437                        llc_sap_rcv(sap, skb, sk);
438                        sock_put(sk);
439                } else
440                        kfree_skb(skb);
441        }
442}
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