1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * 4 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk) 5 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) 6 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) 7 * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de) 8 */ 9 #include <linux/errno.h> 10 #include <linux/types.h> 11 #include <linux/socket.h> 12 #include <linux/in.h> 13 #include <linux/kernel.h> 14 #include <linux/timer.h> 15 #include <linux/string.h> 16 #include <linux/sockios.h> 17 #include <linux/net.h> 18 #include <linux/slab.h> 19 #include <net/ax25.h> 20 #include <linux/inet.h> 21 #include <linux/netdevice.h> 22 #include <linux/skbuff.h> 23 #include <net/sock.h> 24 #include <net/tcp_states.h> 25 #include <linux/uaccess.h> 26 #include <linux/fcntl.h> 27 #include <linux/mm.h> 28 #include <linux/interrupt.h> 29 30 /* 31 * Given a fragment, queue it on the fragment queue and if the fragment 32 * is complete, send it back to ax25_rx_iframe. 33 */ 34 static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb) 35 { 36 struct sk_buff *skbn, *skbo; 37 38 if (ax25->fragno != 0) { 39 if (!(*skb->data & AX25_SEG_FIRST)) { 40 if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) { 41 /* Enqueue fragment */ 42 ax25->fragno = *skb->data & AX25_SEG_REM; 43 skb_pull(skb, 1); /* skip fragno */ 44 ax25->fraglen += skb->len; 45 skb_queue_tail(&ax25->frag_queue, skb); 46 47 /* Last fragment received ? */ 48 if (ax25->fragno == 0) { 49 skbn = alloc_skb(AX25_MAX_HEADER_LEN + 50 ax25->fraglen, 51 GFP_ATOMIC); 52 if (!skbn) { 53 skb_queue_purge(&ax25->frag_queue); 54 return 1; 55 } 56 57 skb_reserve(skbn, AX25_MAX_HEADER_LEN); 58 59 skbn->dev = ax25->ax25_dev->dev; 60 skb_reset_network_header(skbn); 61 skb_reset_transport_header(skbn); 62 63 /* Copy data from the fragments */ 64 while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) { 65 skb_copy_from_linear_data(skbo, 66 skb_put(skbn, skbo->len), 67 skbo->len); 68 kfree_skb(skbo); 69 } 70 71 ax25->fraglen = 0; 72 73 if (ax25_rx_iframe(ax25, skbn) == 0) 74 kfree_skb(skbn); 75 } 76 77 return 1; 78 } 79 } 80 } else { 81 /* First fragment received */ 82 if (*skb->data & AX25_SEG_FIRST) { 83 skb_queue_purge(&ax25->frag_queue); 84 ax25->fragno = *skb->data & AX25_SEG_REM; 85 skb_pull(skb, 1); /* skip fragno */ 86 ax25->fraglen = skb->len; 87 skb_queue_tail(&ax25->frag_queue, skb); 88 return 1; 89 } 90 } 91 92 return 0; 93 } 94 95 /* 96 * This is where all valid I frames are sent to, to be dispatched to 97 * whichever protocol requires them. 98 */ 99 int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb) 100 { 101 int (*func)(struct sk_buff *, ax25_cb *); 102 unsigned char pid; 103 int queued = 0; 104 105 if (skb == NULL) return 0; 106 107 ax25_start_idletimer(ax25); 108 109 pid = *skb->data; 110 111 if (pid == AX25_P_IP) { 112 /* working around a TCP bug to keep additional listeners 113 * happy. TCP re-uses the buffer and destroys the original 114 * content. 115 */ 116 struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC); 117 if (skbn != NULL) { 118 kfree_skb(skb); 119 skb = skbn; 120 } 121 122 skb_pull(skb, 1); /* Remove PID */ 123 skb->mac_header = skb->network_header; 124 skb_reset_network_header(skb); 125 skb->dev = ax25->ax25_dev->dev; 126 skb->pkt_type = PACKET_HOST; 127 skb->protocol = htons(ETH_P_IP); 128 netif_rx(skb); 129 return 1; 130 } 131 if (pid == AX25_P_SEGMENT) { 132 skb_pull(skb, 1); /* Remove PID */ 133 return ax25_rx_fragment(ax25, skb); 134 } 135 136 if ((func = ax25_protocol_function(pid)) != NULL) { 137 skb_pull(skb, 1); /* Remove PID */ 138 return (*func)(skb, ax25); 139 } 140 141 if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) { 142 if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) || 143 ax25->pidincl) { 144 if (sock_queue_rcv_skb(ax25->sk, skb) == 0) 145 queued = 1; 146 else 147 ax25->condition |= AX25_COND_OWN_RX_BUSY; 148 } 149 } 150 151 return queued; 152 } 153 154 /* 155 * Higher level upcall for a LAPB frame 156 */ 157 static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama) 158 { 159 int queued = 0; 160 161 if (ax25->state == AX25_STATE_0) 162 return 0; 163 164 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { 165 case AX25_PROTO_STD_SIMPLEX: 166 case AX25_PROTO_STD_DUPLEX: 167 queued = ax25_std_frame_in(ax25, skb, type); 168 break; 169 170 #ifdef CONFIG_AX25_DAMA_SLAVE 171 case AX25_PROTO_DAMA_SLAVE: 172 if (dama || ax25->ax25_dev->dama.slave) 173 queued = ax25_ds_frame_in(ax25, skb, type); 174 else 175 queued = ax25_std_frame_in(ax25, skb, type); 176 break; 177 #endif 178 } 179 180 return queued; 181 } 182 183 static int ax25_rcv(struct sk_buff *skb, struct net_device *dev, 184 const ax25_address *dev_addr, struct packet_type *ptype) 185 { 186 ax25_address src, dest, *next_digi = NULL; 187 int type = 0, mine = 0, dama; 188 struct sock *make, *sk; 189 ax25_digi dp, reverse_dp; 190 ax25_cb *ax25; 191 ax25_dev *ax25_dev; 192 193 /* 194 * Process the AX.25/LAPB frame. 195 */ 196 197 skb_reset_transport_header(skb); 198 199 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) 200 goto free; 201 202 /* 203 * Parse the address header. 204 */ 205 206 if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL) 207 goto free; 208 209 /* 210 * Ours perhaps ? 211 */ 212 if (dp.lastrepeat + 1 < dp.ndigi) /* Not yet digipeated completely */ 213 next_digi = &dp.calls[dp.lastrepeat + 1]; 214 215 /* 216 * Pull of the AX.25 headers leaving the CTRL/PID bytes 217 */ 218 skb_pull(skb, ax25_addr_size(&dp)); 219 220 /* For our port addresses ? */ 221 if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi) 222 mine = 1; 223 224 /* Also match on any registered callsign from L3/4 */ 225 if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi) 226 mine = 1; 227 228 /* UI frame - bypass LAPB processing */ 229 if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) { 230 skb_set_transport_header(skb, 2); /* skip control and pid */ 231 232 ax25_send_to_raw(&dest, skb, skb->data[1]); 233 234 if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0) 235 goto free; 236 237 /* Now we are pointing at the pid byte */ 238 switch (skb->data[1]) { 239 case AX25_P_IP: 240 skb_pull(skb,2); /* drop PID/CTRL */ 241 skb_reset_transport_header(skb); 242 skb_reset_network_header(skb); 243 skb->dev = dev; 244 skb->pkt_type = PACKET_HOST; 245 skb->protocol = htons(ETH_P_IP); 246 netif_rx(skb); 247 break; 248 249 case AX25_P_ARP: 250 skb_pull(skb,2); 251 skb_reset_transport_header(skb); 252 skb_reset_network_header(skb); 253 skb->dev = dev; 254 skb->pkt_type = PACKET_HOST; 255 skb->protocol = htons(ETH_P_ARP); 256 netif_rx(skb); 257 break; 258 case AX25_P_TEXT: 259 /* Now find a suitable dgram socket */ 260 sk = ax25_get_socket(&dest, &src, SOCK_DGRAM); 261 if (sk != NULL) { 262 bh_lock_sock(sk); 263 if (atomic_read(&sk->sk_rmem_alloc) >= 264 sk->sk_rcvbuf) { 265 kfree_skb(skb); 266 } else { 267 /* 268 * Remove the control and PID. 269 */ 270 skb_pull(skb, 2); 271 if (sock_queue_rcv_skb(sk, skb) != 0) 272 kfree_skb(skb); 273 } 274 bh_unlock_sock(sk); 275 sock_put(sk); 276 } else { 277 kfree_skb(skb); 278 } 279 break; 280 281 default: 282 kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */ 283 break; 284 } 285 286 return 0; 287 } 288 289 /* 290 * Is connected mode supported on this device ? 291 * If not, should we DM the incoming frame (except DMs) or 292 * silently ignore them. For now we stay quiet. 293 */ 294 if (ax25_dev->values[AX25_VALUES_CONMODE] == 0) 295 goto free; 296 297 /* LAPB */ 298 299 /* AX.25 state 1-4 */ 300 301 ax25_digi_invert(&dp, &reverse_dp); 302 303 if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) { 304 /* 305 * Process the frame. If it is queued up internally it 306 * returns one otherwise we free it immediately. This 307 * routine itself wakes the user context layers so we do 308 * no further work 309 */ 310 if (ax25_process_rx_frame(ax25, skb, type, dama) == 0) 311 kfree_skb(skb); 312 313 ax25_cb_put(ax25); 314 return 0; 315 } 316 317 /* AX.25 state 0 (disconnected) */ 318 319 /* a) received not a SABM(E) */ 320 321 if ((*skb->data & ~AX25_PF) != AX25_SABM && 322 (*skb->data & ~AX25_PF) != AX25_SABME) { 323 /* 324 * Never reply to a DM. Also ignore any connects for 325 * addresses that are not our interfaces and not a socket. 326 */ 327 if ((*skb->data & ~AX25_PF) != AX25_DM && mine) 328 ax25_return_dm(dev, &src, &dest, &dp); 329 330 goto free; 331 } 332 333 /* b) received SABM(E) */ 334 335 if (dp.lastrepeat + 1 == dp.ndigi) 336 sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET); 337 else 338 sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET); 339 340 if (sk != NULL) { 341 bh_lock_sock(sk); 342 if (sk_acceptq_is_full(sk) || 343 (make = ax25_make_new(sk, ax25_dev)) == NULL) { 344 if (mine) 345 ax25_return_dm(dev, &src, &dest, &dp); 346 kfree_skb(skb); 347 bh_unlock_sock(sk); 348 sock_put(sk); 349 350 return 0; 351 } 352 353 ax25 = sk_to_ax25(make); 354 skb_set_owner_r(skb, make); 355 skb_queue_head(&sk->sk_receive_queue, skb); 356 357 make->sk_state = TCP_ESTABLISHED; 358 359 sk_acceptq_added(sk); 360 bh_unlock_sock(sk); 361 } else { 362 if (!mine) 363 goto free; 364 365 if ((ax25 = ax25_create_cb()) == NULL) { 366 ax25_return_dm(dev, &src, &dest, &dp); 367 goto free; 368 } 369 370 ax25_fillin_cb(ax25, ax25_dev); 371 } 372 373 ax25->source_addr = dest; 374 ax25->dest_addr = src; 375 376 /* 377 * Sort out any digipeated paths. 378 */ 379 if (dp.ndigi && !ax25->digipeat && 380 (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) { 381 kfree_skb(skb); 382 ax25_destroy_socket(ax25); 383 if (sk) 384 sock_put(sk); 385 return 0; 386 } 387 388 if (dp.ndigi == 0) { 389 kfree(ax25->digipeat); 390 ax25->digipeat = NULL; 391 } else { 392 /* Reverse the source SABM's path */ 393 memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi)); 394 } 395 396 if ((*skb->data & ~AX25_PF) == AX25_SABME) { 397 ax25->modulus = AX25_EMODULUS; 398 ax25->window = ax25_dev->values[AX25_VALUES_EWINDOW]; 399 } else { 400 ax25->modulus = AX25_MODULUS; 401 ax25->window = ax25_dev->values[AX25_VALUES_WINDOW]; 402 } 403 404 ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE); 405 406 #ifdef CONFIG_AX25_DAMA_SLAVE 407 if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE) 408 ax25_dama_on(ax25); 409 #endif 410 411 ax25->state = AX25_STATE_3; 412 413 ax25_cb_add(ax25); 414 415 ax25_start_heartbeat(ax25); 416 ax25_start_t3timer(ax25); 417 ax25_start_idletimer(ax25); 418 419 if (sk) { 420 if (!sock_flag(sk, SOCK_DEAD)) 421 sk->sk_data_ready(sk); 422 sock_put(sk); 423 } else { 424 free: 425 kfree_skb(skb); 426 } 427 return 0; 428 } 429 430 /* 431 * Receive an AX.25 frame via a SLIP interface. 432 */ 433 int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev, 434 struct packet_type *ptype, struct net_device *orig_dev) 435 { 436 skb_orphan(skb); 437 438 if (!net_eq(dev_net(dev), &init_net)) { 439 kfree_skb(skb); 440 return 0; 441 } 442 443 if ((*skb->data & 0x0F) != 0) { 444 kfree_skb(skb); /* Not a KISS data frame */ 445 return 0; 446 } 447 448 skb_pull(skb, AX25_KISS_HEADER_LEN); /* Remove the KISS byte */ 449 450 return ax25_rcv(skb, dev, (const ax25_address *)dev->dev_addr, ptype); 451 } 452