1 /* 2 * This program is free software; you can redistribute it and/or modify 3 * it under the terms of the GNU General Public License as published by 4 * the Free Software Foundation; either version 2 of the License, or 5 * (at your option) any later version. 6 * 7 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk) 8 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) 9 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) 10 * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de) 11 */ 12 #include <linux/errno.h> 13 #include <linux/types.h> 14 #include <linux/socket.h> 15 #include <linux/in.h> 16 #include <linux/kernel.h> 17 #include <linux/timer.h> 18 #include <linux/string.h> 19 #include <linux/sockios.h> 20 #include <linux/net.h> 21 #include <linux/slab.h> 22 #include <net/ax25.h> 23 #include <linux/inet.h> 24 #include <linux/netdevice.h> 25 #include <linux/skbuff.h> 26 #include <linux/netfilter.h> 27 #include <net/sock.h> 28 #include <net/tcp_states.h> 29 #include <asm/uaccess.h> 30 #include <asm/system.h> 31 #include <linux/fcntl.h> 32 #include <linux/mm.h> 33 #include <linux/interrupt.h> 34 35 /* 36 * Given a fragment, queue it on the fragment queue and if the fragment 37 * is complete, send it back to ax25_rx_iframe. 38 */ 39 static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb) 40 { 41 struct sk_buff *skbn, *skbo; 42 43 if (ax25->fragno != 0) { 44 if (!(*skb->data & AX25_SEG_FIRST)) { 45 if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) { 46 /* Enqueue fragment */ 47 ax25->fragno = *skb->data & AX25_SEG_REM; 48 skb_pull(skb, 1); /* skip fragno */ 49 ax25->fraglen += skb->len; 50 skb_queue_tail(&ax25->frag_queue, skb); 51 52 /* Last fragment received ? */ 53 if (ax25->fragno == 0) { 54 skbn = alloc_skb(AX25_MAX_HEADER_LEN + 55 ax25->fraglen, 56 GFP_ATOMIC); 57 if (!skbn) { 58 skb_queue_purge(&ax25->frag_queue); 59 return 1; 60 } 61 62 skb_reserve(skbn, AX25_MAX_HEADER_LEN); 63 64 skbn->dev = ax25->ax25_dev->dev; 65 skb_reset_network_header(skbn); 66 skb_reset_transport_header(skbn); 67 68 /* Copy data from the fragments */ 69 while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) { 70 skb_copy_from_linear_data(skbo, 71 skb_put(skbn, skbo->len), 72 skbo->len); 73 kfree_skb(skbo); 74 } 75 76 ax25->fraglen = 0; 77 78 if (ax25_rx_iframe(ax25, skbn) == 0) 79 kfree_skb(skbn); 80 } 81 82 return 1; 83 } 84 } 85 } else { 86 /* First fragment received */ 87 if (*skb->data & AX25_SEG_FIRST) { 88 skb_queue_purge(&ax25->frag_queue); 89 ax25->fragno = *skb->data & AX25_SEG_REM; 90 skb_pull(skb, 1); /* skip fragno */ 91 ax25->fraglen = skb->len; 92 skb_queue_tail(&ax25->frag_queue, skb); 93 return 1; 94 } 95 } 96 97 return 0; 98 } 99 100 /* 101 * This is where all valid I frames are sent to, to be dispatched to 102 * whichever protocol requires them. 103 */ 104 int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb) 105 { 106 int (*func)(struct sk_buff *, ax25_cb *); 107 unsigned char pid; 108 int queued = 0; 109 110 if (skb == NULL) return 0; 111 112 ax25_start_idletimer(ax25); 113 114 pid = *skb->data; 115 116 if (pid == AX25_P_IP) { 117 /* working around a TCP bug to keep additional listeners 118 * happy. TCP re-uses the buffer and destroys the original 119 * content. 120 */ 121 struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC); 122 if (skbn != NULL) { 123 kfree_skb(skb); 124 skb = skbn; 125 } 126 127 skb_pull(skb, 1); /* Remove PID */ 128 skb->mac_header = skb->network_header; 129 skb_reset_network_header(skb); 130 skb->dev = ax25->ax25_dev->dev; 131 skb->pkt_type = PACKET_HOST; 132 skb->protocol = htons(ETH_P_IP); 133 netif_rx(skb); 134 return 1; 135 } 136 if (pid == AX25_P_SEGMENT) { 137 skb_pull(skb, 1); /* Remove PID */ 138 return ax25_rx_fragment(ax25, skb); 139 } 140 141 if ((func = ax25_protocol_function(pid)) != NULL) { 142 skb_pull(skb, 1); /* Remove PID */ 143 return (*func)(skb, ax25); 144 } 145 146 if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) { 147 if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) || 148 ax25->pidincl) { 149 if (sock_queue_rcv_skb(ax25->sk, skb) == 0) 150 queued = 1; 151 else 152 ax25->condition |= AX25_COND_OWN_RX_BUSY; 153 } 154 } 155 156 return queued; 157 } 158 159 /* 160 * Higher level upcall for a LAPB frame 161 */ 162 static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama) 163 { 164 int queued = 0; 165 166 if (ax25->state == AX25_STATE_0) 167 return 0; 168 169 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { 170 case AX25_PROTO_STD_SIMPLEX: 171 case AX25_PROTO_STD_DUPLEX: 172 queued = ax25_std_frame_in(ax25, skb, type); 173 break; 174 175 #ifdef CONFIG_AX25_DAMA_SLAVE 176 case AX25_PROTO_DAMA_SLAVE: 177 if (dama || ax25->ax25_dev->dama.slave) 178 queued = ax25_ds_frame_in(ax25, skb, type); 179 else 180 queued = ax25_std_frame_in(ax25, skb, type); 181 break; 182 #endif 183 } 184 185 return queued; 186 } 187 188 static int ax25_rcv(struct sk_buff *skb, struct net_device *dev, 189 ax25_address *dev_addr, struct packet_type *ptype) 190 { 191 ax25_address src, dest, *next_digi = NULL; 192 int type = 0, mine = 0, dama; 193 struct sock *make, *sk; 194 ax25_digi dp, reverse_dp; 195 ax25_cb *ax25; 196 ax25_dev *ax25_dev; 197 198 /* 199 * Process the AX.25/LAPB frame. 200 */ 201 202 skb_reset_transport_header(skb); 203 204 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) 205 goto free; 206 207 /* 208 * Parse the address header. 209 */ 210 211 if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL) 212 goto free; 213 214 /* 215 * Ours perhaps ? 216 */ 217 if (dp.lastrepeat + 1 < dp.ndigi) /* Not yet digipeated completely */ 218 next_digi = &dp.calls[dp.lastrepeat + 1]; 219 220 /* 221 * Pull of the AX.25 headers leaving the CTRL/PID bytes 222 */ 223 skb_pull(skb, ax25_addr_size(&dp)); 224 225 /* For our port addresses ? */ 226 if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi) 227 mine = 1; 228 229 /* Also match on any registered callsign from L3/4 */ 230 if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi) 231 mine = 1; 232 233 /* UI frame - bypass LAPB processing */ 234 if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) { 235 skb_set_transport_header(skb, 2); /* skip control and pid */ 236 237 ax25_send_to_raw(&dest, skb, skb->data[1]); 238 239 if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0) 240 goto free; 241 242 /* Now we are pointing at the pid byte */ 243 switch (skb->data[1]) { 244 case AX25_P_IP: 245 skb_pull(skb,2); /* drop PID/CTRL */ 246 skb_reset_transport_header(skb); 247 skb_reset_network_header(skb); 248 skb->dev = dev; 249 skb->pkt_type = PACKET_HOST; 250 skb->protocol = htons(ETH_P_IP); 251 netif_rx(skb); 252 break; 253 254 case AX25_P_ARP: 255 skb_pull(skb,2); 256 skb_reset_transport_header(skb); 257 skb_reset_network_header(skb); 258 skb->dev = dev; 259 skb->pkt_type = PACKET_HOST; 260 skb->protocol = htons(ETH_P_ARP); 261 netif_rx(skb); 262 break; 263 case AX25_P_TEXT: 264 /* Now find a suitable dgram socket */ 265 sk = ax25_get_socket(&dest, &src, SOCK_DGRAM); 266 if (sk != NULL) { 267 bh_lock_sock(sk); 268 if (atomic_read(&sk->sk_rmem_alloc) >= 269 sk->sk_rcvbuf) { 270 kfree_skb(skb); 271 } else { 272 /* 273 * Remove the control and PID. 274 */ 275 skb_pull(skb, 2); 276 if (sock_queue_rcv_skb(sk, skb) != 0) 277 kfree_skb(skb); 278 } 279 bh_unlock_sock(sk); 280 sock_put(sk); 281 } else { 282 kfree_skb(skb); 283 } 284 break; 285 286 default: 287 kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */ 288 break; 289 } 290 291 return 0; 292 } 293 294 /* 295 * Is connected mode supported on this device ? 296 * If not, should we DM the incoming frame (except DMs) or 297 * silently ignore them. For now we stay quiet. 298 */ 299 if (ax25_dev->values[AX25_VALUES_CONMODE] == 0) 300 goto free; 301 302 /* LAPB */ 303 304 /* AX.25 state 1-4 */ 305 306 ax25_digi_invert(&dp, &reverse_dp); 307 308 if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) { 309 /* 310 * Process the frame. If it is queued up internally it 311 * returns one otherwise we free it immediately. This 312 * routine itself wakes the user context layers so we do 313 * no further work 314 */ 315 if (ax25_process_rx_frame(ax25, skb, type, dama) == 0) 316 kfree_skb(skb); 317 318 ax25_cb_put(ax25); 319 return 0; 320 } 321 322 /* AX.25 state 0 (disconnected) */ 323 324 /* a) received not a SABM(E) */ 325 326 if ((*skb->data & ~AX25_PF) != AX25_SABM && 327 (*skb->data & ~AX25_PF) != AX25_SABME) { 328 /* 329 * Never reply to a DM. Also ignore any connects for 330 * addresses that are not our interfaces and not a socket. 331 */ 332 if ((*skb->data & ~AX25_PF) != AX25_DM && mine) 333 ax25_return_dm(dev, &src, &dest, &dp); 334 335 goto free; 336 } 337 338 /* b) received SABM(E) */ 339 340 if (dp.lastrepeat + 1 == dp.ndigi) 341 sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET); 342 else 343 sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET); 344 345 if (sk != NULL) { 346 bh_lock_sock(sk); 347 if (sk_acceptq_is_full(sk) || 348 (make = ax25_make_new(sk, ax25_dev)) == NULL) { 349 if (mine) 350 ax25_return_dm(dev, &src, &dest, &dp); 351 kfree_skb(skb); 352 bh_unlock_sock(sk); 353 sock_put(sk); 354 355 return 0; 356 } 357 358 ax25 = ax25_sk(make); 359 skb_set_owner_r(skb, make); 360 skb_queue_head(&sk->sk_receive_queue, skb); 361 362 make->sk_state = TCP_ESTABLISHED; 363 364 sk->sk_ack_backlog++; 365 bh_unlock_sock(sk); 366 } else { 367 if (!mine) 368 goto free; 369 370 if ((ax25 = ax25_create_cb()) == NULL) { 371 ax25_return_dm(dev, &src, &dest, &dp); 372 goto free; 373 } 374 375 ax25_fillin_cb(ax25, ax25_dev); 376 } 377 378 ax25->source_addr = dest; 379 ax25->dest_addr = src; 380 381 /* 382 * Sort out any digipeated paths. 383 */ 384 if (dp.ndigi && !ax25->digipeat && 385 (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) { 386 kfree_skb(skb); 387 ax25_destroy_socket(ax25); 388 if (sk) 389 sock_put(sk); 390 return 0; 391 } 392 393 if (dp.ndigi == 0) { 394 kfree(ax25->digipeat); 395 ax25->digipeat = NULL; 396 } else { 397 /* Reverse the source SABM's path */ 398 memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi)); 399 } 400 401 if ((*skb->data & ~AX25_PF) == AX25_SABME) { 402 ax25->modulus = AX25_EMODULUS; 403 ax25->window = ax25_dev->values[AX25_VALUES_EWINDOW]; 404 } else { 405 ax25->modulus = AX25_MODULUS; 406 ax25->window = ax25_dev->values[AX25_VALUES_WINDOW]; 407 } 408 409 ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE); 410 411 #ifdef CONFIG_AX25_DAMA_SLAVE 412 if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE) 413 ax25_dama_on(ax25); 414 #endif 415 416 ax25->state = AX25_STATE_3; 417 418 ax25_cb_add(ax25); 419 420 ax25_start_heartbeat(ax25); 421 ax25_start_t3timer(ax25); 422 ax25_start_idletimer(ax25); 423 424 if (sk) { 425 if (!sock_flag(sk, SOCK_DEAD)) 426 sk->sk_data_ready(sk, skb->len); 427 sock_put(sk); 428 } else { 429 free: 430 kfree_skb(skb); 431 } 432 return 0; 433 } 434 435 /* 436 * Receive an AX.25 frame via a SLIP interface. 437 */ 438 int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev, 439 struct packet_type *ptype, struct net_device *orig_dev) 440 { 441 skb_orphan(skb); 442 443 if (!net_eq(dev_net(dev), &init_net)) { 444 kfree_skb(skb); 445 return 0; 446 } 447 448 if ((*skb->data & 0x0F) != 0) { 449 kfree_skb(skb); /* Not a KISS data frame */ 450 return 0; 451 } 452 453 skb_pull(skb, AX25_KISS_HEADER_LEN); /* Remove the KISS byte */ 454 455 return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype); 456 } 457