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 #if defined(CONFIG_TR) || defined(CONFIG_TR_MODULE) 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