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