1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * G8BPQ compatible "AX.25 via ethernet" driver release 004 4 * 5 * This code REQUIRES 2.0.0 or higher/ NET3.029 6 * 7 * This is a "pseudo" network driver to allow AX.25 over Ethernet 8 * using G8BPQ encapsulation. It has been extracted from the protocol 9 * implementation because 10 * 11 * - things got unreadable within the protocol stack 12 * - to cure the protocol stack from "feature-ism" 13 * - a protocol implementation shouldn't need to know on 14 * which hardware it is running 15 * - user-level programs like the AX.25 utilities shouldn't 16 * need to know about the hardware. 17 * - IP over ethernet encapsulated AX.25 was impossible 18 * - rxecho.c did not work 19 * - to have room for extensions 20 * - it just deserves to "live" as an own driver 21 * 22 * This driver can use any ethernet destination address, and can be 23 * limited to accept frames from one dedicated ethernet card only. 24 * 25 * Note that the driver sets up the BPQ devices automagically on 26 * startup or (if started before the "insmod" of an ethernet device) 27 * on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing 28 * the ethernet device (in fact: as soon as another ethernet or bpq 29 * device gets "ifconfig"ured). 30 * 31 * I have heard that several people are thinking of experiments 32 * with highspeed packet radio using existing ethernet cards. 33 * Well, this driver is prepared for this purpose, just add 34 * your tx key control and a txdelay / tailtime algorithm, 35 * probably some buffering, and /voila/... 36 * 37 * History 38 * BPQ 001 Joerg(DL1BKE) Extracted BPQ code from AX.25 39 * protocol stack and added my own 40 * yet existing patches 41 * BPQ 002 Joerg(DL1BKE) Scan network device list on 42 * startup. 43 * BPQ 003 Joerg(DL1BKE) Ethernet destination address 44 * and accepted source address 45 * can be configured by an ioctl() 46 * call. 47 * Fixed to match Linux networking 48 * changes - 2.1.15. 49 * BPQ 004 Joerg(DL1BKE) Fixed to not lock up on ifconfig. 50 */ 51 52 #include <linux/errno.h> 53 #include <linux/types.h> 54 #include <linux/socket.h> 55 #include <linux/in.h> 56 #include <linux/kernel.h> 57 #include <linux/string.h> 58 #include <linux/net.h> 59 #include <linux/slab.h> 60 #include <net/ax25.h> 61 #include <linux/inet.h> 62 #include <linux/netdevice.h> 63 #include <linux/etherdevice.h> 64 #include <linux/if_arp.h> 65 #include <linux/skbuff.h> 66 #include <net/sock.h> 67 #include <linux/uaccess.h> 68 #include <linux/mm.h> 69 #include <linux/interrupt.h> 70 #include <linux/notifier.h> 71 #include <linux/proc_fs.h> 72 #include <linux/seq_file.h> 73 #include <linux/stat.h> 74 #include <linux/module.h> 75 #include <linux/init.h> 76 #include <linux/rtnetlink.h> 77 78 #include <net/ip.h> 79 #include <net/arp.h> 80 #include <net/netdev_lock.h> 81 #include <net/net_namespace.h> 82 83 #include <linux/bpqether.h> 84 85 static const char banner[] __initconst = KERN_INFO \ 86 "AX.25: bpqether driver version 004\n"; 87 88 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *); 89 static int bpq_device_event(struct notifier_block *, unsigned long, void *); 90 91 static struct packet_type bpq_packet_type __read_mostly = { 92 .type = cpu_to_be16(ETH_P_BPQ), 93 .func = bpq_rcv, 94 }; 95 96 static struct notifier_block bpq_dev_notifier = { 97 .notifier_call = bpq_device_event, 98 }; 99 100 101 struct bpqdev { 102 struct list_head bpq_list; /* list of bpq devices chain */ 103 struct net_device *ethdev; /* link to ethernet device */ 104 struct net_device *axdev; /* bpq device (bpq#) */ 105 char dest_addr[6]; /* ether destination address */ 106 char acpt_addr[6]; /* accept ether frames from this address only */ 107 }; 108 109 static LIST_HEAD(bpq_devices); 110 111 /* ------------------------------------------------------------------------ */ 112 113 114 /* 115 * Get the ethernet device for a BPQ device 116 */ 117 static inline struct net_device *bpq_get_ether_dev(struct net_device *dev) 118 { 119 struct bpqdev *bpq = netdev_priv(dev); 120 121 return bpq ? bpq->ethdev : NULL; 122 } 123 124 /* 125 * Get the BPQ device for the ethernet device 126 */ 127 static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev) 128 { 129 struct bpqdev *bpq; 130 131 list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list, 132 lockdep_rtnl_is_held()) { 133 if (bpq->ethdev == dev) 134 return bpq->axdev; 135 } 136 return NULL; 137 } 138 139 static inline int dev_is_ethdev(struct net_device *dev) 140 { 141 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); 142 } 143 144 /* ------------------------------------------------------------------------ */ 145 146 147 /* 148 * Receive an AX.25 frame via an ethernet interface. 149 */ 150 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) 151 { 152 int len; 153 char * ptr; 154 struct ethhdr *eth; 155 struct bpqdev *bpq; 156 157 if (!net_eq(dev_net(dev), &init_net)) 158 goto drop; 159 160 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 161 return NET_RX_DROP; 162 163 if (!pskb_may_pull(skb, sizeof(struct ethhdr))) 164 goto drop; 165 166 rcu_read_lock(); 167 dev = bpq_get_ax25_dev(dev); 168 169 if (dev == NULL || !netif_running(dev)) 170 goto drop_unlock; 171 172 /* 173 * if we want to accept frames from just one ethernet device 174 * we check the source address of the sender. 175 */ 176 177 bpq = netdev_priv(dev); 178 179 eth = eth_hdr(skb); 180 181 if (!(bpq->acpt_addr[0] & 0x01) && 182 !ether_addr_equal(eth->h_source, bpq->acpt_addr)) 183 goto drop_unlock; 184 185 if (skb_cow(skb, sizeof(struct ethhdr))) 186 goto drop_unlock; 187 188 len = skb->data[0] + skb->data[1] * 256 - 5; 189 190 skb_pull(skb, 2); /* Remove the length bytes */ 191 skb_trim(skb, len); /* Set the length of the data */ 192 193 dev->stats.rx_packets++; 194 dev->stats.rx_bytes += len; 195 196 ptr = skb_push(skb, 1); 197 *ptr = 0; 198 199 skb->protocol = ax25_type_trans(skb, dev); 200 netif_rx(skb); 201 unlock: 202 203 rcu_read_unlock(); 204 205 return 0; 206 drop_unlock: 207 kfree_skb(skb); 208 goto unlock; 209 210 drop: 211 kfree_skb(skb); 212 return 0; 213 } 214 215 /* 216 * Send an AX.25 frame via an ethernet interface 217 */ 218 static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev) 219 { 220 unsigned char *ptr; 221 struct bpqdev *bpq; 222 struct net_device *orig_dev; 223 int size; 224 225 if (skb->protocol == htons(ETH_P_IP)) 226 return ax25_ip_xmit(skb); 227 228 /* 229 * Just to be *really* sure not to send anything if the interface 230 * is down, the ethernet device may have gone. 231 */ 232 if (!netif_running(dev)) { 233 kfree_skb(skb); 234 return NETDEV_TX_OK; 235 } 236 237 skb_pull(skb, 1); /* Drop KISS byte */ 238 size = skb->len; 239 240 /* 241 * We're about to mess with the skb which may still shared with the 242 * generic networking code so unshare and ensure it's got enough 243 * space for the BPQ headers. 244 */ 245 if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) { 246 if (net_ratelimit()) 247 pr_err("bpqether: out of memory\n"); 248 kfree_skb(skb); 249 250 return NETDEV_TX_OK; 251 } 252 253 ptr = skb_push(skb, 2); /* Make space for length */ 254 255 *ptr++ = (size + 5) % 256; 256 *ptr++ = (size + 5) / 256; 257 258 bpq = netdev_priv(dev); 259 260 orig_dev = dev; 261 if ((dev = bpq_get_ether_dev(dev)) == NULL) { 262 orig_dev->stats.tx_dropped++; 263 kfree_skb(skb); 264 return NETDEV_TX_OK; 265 } 266 267 skb->protocol = ax25_type_trans(skb, dev); 268 skb_reset_network_header(skb); 269 dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0); 270 dev->stats.tx_packets++; 271 dev->stats.tx_bytes+=skb->len; 272 273 dev_queue_xmit(skb); 274 netif_wake_queue(dev); 275 return NETDEV_TX_OK; 276 } 277 278 /* 279 * Set AX.25 callsign 280 */ 281 static int bpq_set_mac_address(struct net_device *dev, void *addr) 282 { 283 struct sockaddr *sa = (struct sockaddr *)addr; 284 285 dev_addr_set(dev, sa->sa_data); 286 287 return 0; 288 } 289 290 /* Ioctl commands 291 * 292 * SIOCSBPQETHOPT reserved for enhancements 293 * SIOCSBPQETHADDR set the destination and accepted 294 * source ethernet address (broadcast 295 * or multicast: accept all) 296 */ 297 static int bpq_siocdevprivate(struct net_device *dev, struct ifreq *ifr, 298 void __user *data, int cmd) 299 { 300 struct bpq_ethaddr __user *ethaddr = data; 301 struct bpqdev *bpq = netdev_priv(dev); 302 struct bpq_req req; 303 304 if (!capable(CAP_NET_ADMIN)) 305 return -EPERM; 306 307 switch (cmd) { 308 case SIOCSBPQETHOPT: 309 if (copy_from_user(&req, data, sizeof(struct bpq_req))) 310 return -EFAULT; 311 switch (req.cmd) { 312 case SIOCGBPQETHPARAM: 313 case SIOCSBPQETHPARAM: 314 default: 315 return -EINVAL; 316 } 317 318 break; 319 320 case SIOCSBPQETHADDR: 321 if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN)) 322 return -EFAULT; 323 if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN)) 324 return -EFAULT; 325 break; 326 327 default: 328 return -EINVAL; 329 } 330 331 return 0; 332 } 333 334 /* 335 * open/close a device 336 */ 337 static int bpq_open(struct net_device *dev) 338 { 339 netif_start_queue(dev); 340 return 0; 341 } 342 343 static int bpq_close(struct net_device *dev) 344 { 345 netif_stop_queue(dev); 346 return 0; 347 } 348 349 350 /* ------------------------------------------------------------------------ */ 351 352 #ifdef CONFIG_PROC_FS 353 /* 354 * Proc filesystem 355 */ 356 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos) 357 __acquires(RCU) 358 { 359 int i = 1; 360 struct bpqdev *bpqdev; 361 362 rcu_read_lock(); 363 364 if (*pos == 0) 365 return SEQ_START_TOKEN; 366 367 list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) { 368 if (i == *pos) 369 return bpqdev; 370 } 371 return NULL; 372 } 373 374 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) 375 { 376 struct list_head *p; 377 struct bpqdev *bpqdev = v; 378 379 ++*pos; 380 381 if (v == SEQ_START_TOKEN) 382 p = rcu_dereference(list_next_rcu(&bpq_devices)); 383 else 384 p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list)); 385 386 return (p == &bpq_devices) ? NULL 387 : list_entry(p, struct bpqdev, bpq_list); 388 } 389 390 static void bpq_seq_stop(struct seq_file *seq, void *v) 391 __releases(RCU) 392 { 393 rcu_read_unlock(); 394 } 395 396 397 static int bpq_seq_show(struct seq_file *seq, void *v) 398 { 399 if (v == SEQ_START_TOKEN) 400 seq_puts(seq, 401 "dev ether destination accept from\n"); 402 else { 403 const struct bpqdev *bpqdev = v; 404 405 seq_printf(seq, "%-5s %-10s %pM ", 406 bpqdev->axdev->name, bpqdev->ethdev->name, 407 bpqdev->dest_addr); 408 409 if (is_multicast_ether_addr(bpqdev->acpt_addr)) 410 seq_printf(seq, "*\n"); 411 else 412 seq_printf(seq, "%pM\n", bpqdev->acpt_addr); 413 414 } 415 return 0; 416 } 417 418 static const struct seq_operations bpq_seqops = { 419 .start = bpq_seq_start, 420 .next = bpq_seq_next, 421 .stop = bpq_seq_stop, 422 .show = bpq_seq_show, 423 }; 424 #endif 425 /* ------------------------------------------------------------------------ */ 426 427 static const struct net_device_ops bpq_netdev_ops = { 428 .ndo_open = bpq_open, 429 .ndo_stop = bpq_close, 430 .ndo_start_xmit = bpq_xmit, 431 .ndo_set_mac_address = bpq_set_mac_address, 432 .ndo_siocdevprivate = bpq_siocdevprivate, 433 }; 434 435 static void bpq_setup(struct net_device *dev) 436 { 437 netdev_lockdep_set_classes(dev); 438 439 dev->netdev_ops = &bpq_netdev_ops; 440 dev->needs_free_netdev = true; 441 442 dev->flags = 0; 443 dev->lltx = true; /* Allow recursion */ 444 445 #if IS_ENABLED(CONFIG_AX25) 446 dev->header_ops = &ax25_header_ops; 447 #endif 448 449 dev->type = ARPHRD_AX25; 450 dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN; 451 dev->mtu = AX25_DEF_PACLEN; 452 dev->addr_len = AX25_ADDR_LEN; 453 454 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 455 dev_addr_set(dev, (u8 *)&ax25_defaddr); 456 } 457 458 /* 459 * Setup a new device. 460 */ 461 static int bpq_new_device(struct net_device *edev) 462 { 463 int err; 464 struct net_device *ndev; 465 struct bpqdev *bpq; 466 467 ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN, 468 bpq_setup); 469 if (!ndev) 470 return -ENOMEM; 471 472 473 bpq = netdev_priv(ndev); 474 dev_hold(edev); 475 bpq->ethdev = edev; 476 bpq->axdev = ndev; 477 478 eth_broadcast_addr(bpq->dest_addr); 479 eth_broadcast_addr(bpq->acpt_addr); 480 481 err = register_netdevice(ndev); 482 if (err) 483 goto error; 484 485 /* List protected by RTNL */ 486 list_add_rcu(&bpq->bpq_list, &bpq_devices); 487 return 0; 488 489 error: 490 dev_put(edev); 491 free_netdev(ndev); 492 return err; 493 494 } 495 496 static void bpq_free_device(struct net_device *ndev) 497 { 498 struct bpqdev *bpq = netdev_priv(ndev); 499 500 dev_put(bpq->ethdev); 501 list_del_rcu(&bpq->bpq_list); 502 503 unregister_netdevice(ndev); 504 } 505 506 /* 507 * Handle device status changes. 508 */ 509 static int bpq_device_event(struct notifier_block *this, 510 unsigned long event, void *ptr) 511 { 512 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 513 514 if (!net_eq(dev_net(dev), &init_net)) 515 return NOTIFY_DONE; 516 517 if (!dev_is_ethdev(dev) && !bpq_get_ax25_dev(dev)) 518 return NOTIFY_DONE; 519 520 switch (event) { 521 case NETDEV_UP: /* new ethernet device -> new BPQ interface */ 522 if (bpq_get_ax25_dev(dev) == NULL) 523 bpq_new_device(dev); 524 break; 525 526 case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */ 527 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 528 dev_close(dev); 529 break; 530 531 case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */ 532 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 533 bpq_free_device(dev); 534 break; 535 default: 536 break; 537 } 538 539 return NOTIFY_DONE; 540 } 541 542 543 /* ------------------------------------------------------------------------ */ 544 545 /* 546 * Initialize driver. To be called from af_ax25 if not compiled as a 547 * module 548 */ 549 static int __init bpq_init_driver(void) 550 { 551 #ifdef CONFIG_PROC_FS 552 if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) { 553 printk(KERN_ERR 554 "bpq: cannot create /proc/net/bpqether entry.\n"); 555 return -ENOENT; 556 } 557 #endif /* CONFIG_PROC_FS */ 558 559 dev_add_pack(&bpq_packet_type); 560 561 register_netdevice_notifier(&bpq_dev_notifier); 562 563 printk(banner); 564 565 return 0; 566 } 567 568 static void __exit bpq_cleanup_driver(void) 569 { 570 struct bpqdev *bpq; 571 572 dev_remove_pack(&bpq_packet_type); 573 574 unregister_netdevice_notifier(&bpq_dev_notifier); 575 576 remove_proc_entry("bpqether", init_net.proc_net); 577 578 rtnl_lock(); 579 while (!list_empty(&bpq_devices)) { 580 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list); 581 bpq_free_device(bpq->axdev); 582 } 583 rtnl_unlock(); 584 } 585 586 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>"); 587 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet"); 588 MODULE_LICENSE("GPL"); 589 module_init(bpq_init_driver); 590 module_exit(bpq_cleanup_driver); 591