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 } 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 */ 47 struct 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 69 void 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 */ 91 void 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 */ 116 static 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 */ 144 static 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 const 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 */ 166 static 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; 188 out: 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 */ 201 static 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 */ 237 void 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 */ 263 void 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 */ 286 static 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 } 299 300 static 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 */ 319 static 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(); 328 again: 329 sk_nulls_for_each_rcu(rc, node, laddr_hb) { 330 if (llc_dgram_match(sap, laddr, rc)) { 331 /* Extra checks required by SLAB_TYPESAFE_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; 350 found: 351 rcu_read_unlock_bh(); 352 return rc; 353 } 354 355 static 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 } 366 367 static 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 */ 393 static 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 } 422 423 424 void 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 } 443