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} 440