1 /* 2 * G8BPQ compatible "AX.25 via ethernet" driver release 004 3 * 4 * This code REQUIRES 2.0.0 or higher/ NET3.029 5 * 6 * This module: 7 * This module is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 * 12 * This is a "pseudo" network driver to allow AX.25 over Ethernet 13 * using G8BPQ encapsulation. It has been extracted from the protocol 14 * implementation because 15 * 16 * - things got unreadable within the protocol stack 17 * - to cure the protocol stack from "feature-ism" 18 * - a protocol implementation shouldn't need to know on 19 * which hardware it is running 20 * - user-level programs like the AX.25 utilities shouldn't 21 * need to know about the hardware. 22 * - IP over ethernet encapsulated AX.25 was impossible 23 * - rxecho.c did not work 24 * - to have room for extensions 25 * - it just deserves to "live" as an own driver 26 * 27 * This driver can use any ethernet destination address, and can be 28 * limited to accept frames from one dedicated ethernet card only. 29 * 30 * Note that the driver sets up the BPQ devices automagically on 31 * startup or (if started before the "insmod" of an ethernet device) 32 * on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing 33 * the ethernet device (in fact: as soon as another ethernet or bpq 34 * device gets "ifconfig"ured). 35 * 36 * I have heard that several people are thinking of experiments 37 * with highspeed packet radio using existing ethernet cards. 38 * Well, this driver is prepared for this purpose, just add 39 * your tx key control and a txdelay / tailtime algorithm, 40 * probably some buffering, and /voila/... 41 * 42 * History 43 * BPQ 001 Joerg(DL1BKE) Extracted BPQ code from AX.25 44 * protocol stack and added my own 45 * yet existing patches 46 * BPQ 002 Joerg(DL1BKE) Scan network device list on 47 * startup. 48 * BPQ 003 Joerg(DL1BKE) Ethernet destination address 49 * and accepted source address 50 * can be configured by an ioctl() 51 * call. 52 * Fixed to match Linux networking 53 * changes - 2.1.15. 54 * BPQ 004 Joerg(DL1BKE) Fixed to not lock up on ifconfig. 55 */ 56 57 #include <linux/errno.h> 58 #include <linux/types.h> 59 #include <linux/socket.h> 60 #include <linux/in.h> 61 #include <linux/kernel.h> 62 #include <linux/string.h> 63 #include <linux/net.h> 64 #include <linux/slab.h> 65 #include <net/ax25.h> 66 #include <linux/inet.h> 67 #include <linux/netdevice.h> 68 #include <linux/etherdevice.h> 69 #include <linux/if_arp.h> 70 #include <linux/skbuff.h> 71 #include <net/sock.h> 72 #include <linux/uaccess.h> 73 #include <linux/mm.h> 74 #include <linux/interrupt.h> 75 #include <linux/notifier.h> 76 #include <linux/proc_fs.h> 77 #include <linux/seq_file.h> 78 #include <linux/stat.h> 79 #include <linux/module.h> 80 #include <linux/init.h> 81 #include <linux/rtnetlink.h> 82 83 #include <net/ip.h> 84 #include <net/arp.h> 85 #include <net/net_namespace.h> 86 87 #include <linux/bpqether.h> 88 89 static const char banner[] __initconst = KERN_INFO \ 90 "AX.25: bpqether driver version 004\n"; 91 92 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *); 93 static int bpq_device_event(struct notifier_block *, unsigned long, void *); 94 95 static struct packet_type bpq_packet_type __read_mostly = { 96 .type = cpu_to_be16(ETH_P_BPQ), 97 .func = bpq_rcv, 98 }; 99 100 static struct notifier_block bpq_dev_notifier = { 101 .notifier_call = bpq_device_event, 102 }; 103 104 105 struct bpqdev { 106 struct list_head bpq_list; /* list of bpq devices chain */ 107 struct net_device *ethdev; /* link to ethernet device */ 108 struct net_device *axdev; /* bpq device (bpq#) */ 109 char dest_addr[6]; /* ether destination address */ 110 char acpt_addr[6]; /* accept ether frames from this address only */ 111 }; 112 113 static LIST_HEAD(bpq_devices); 114 115 /* 116 * bpqether network devices are paired with ethernet devices below them, so 117 * form a special "super class" of normal ethernet devices; split their locks 118 * off into a separate class since they always nest. 119 */ 120 static struct lock_class_key bpq_netdev_xmit_lock_key; 121 static struct lock_class_key bpq_netdev_addr_lock_key; 122 123 static void bpq_set_lockdep_class_one(struct net_device *dev, 124 struct netdev_queue *txq, 125 void *_unused) 126 { 127 lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key); 128 } 129 130 static void bpq_set_lockdep_class(struct net_device *dev) 131 { 132 lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key); 133 netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL); 134 } 135 136 /* ------------------------------------------------------------------------ */ 137 138 139 /* 140 * Get the ethernet device for a BPQ device 141 */ 142 static inline struct net_device *bpq_get_ether_dev(struct net_device *dev) 143 { 144 struct bpqdev *bpq = netdev_priv(dev); 145 146 return bpq ? bpq->ethdev : NULL; 147 } 148 149 /* 150 * Get the BPQ device for the ethernet device 151 */ 152 static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev) 153 { 154 struct bpqdev *bpq; 155 156 list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) { 157 if (bpq->ethdev == dev) 158 return bpq->axdev; 159 } 160 return NULL; 161 } 162 163 static inline int dev_is_ethdev(struct net_device *dev) 164 { 165 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); 166 } 167 168 /* ------------------------------------------------------------------------ */ 169 170 171 /* 172 * Receive an AX.25 frame via an ethernet interface. 173 */ 174 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) 175 { 176 int len; 177 char * ptr; 178 struct ethhdr *eth; 179 struct bpqdev *bpq; 180 181 if (!net_eq(dev_net(dev), &init_net)) 182 goto drop; 183 184 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 185 return NET_RX_DROP; 186 187 if (!pskb_may_pull(skb, sizeof(struct ethhdr))) 188 goto drop; 189 190 rcu_read_lock(); 191 dev = bpq_get_ax25_dev(dev); 192 193 if (dev == NULL || !netif_running(dev)) 194 goto drop_unlock; 195 196 /* 197 * if we want to accept frames from just one ethernet device 198 * we check the source address of the sender. 199 */ 200 201 bpq = netdev_priv(dev); 202 203 eth = eth_hdr(skb); 204 205 if (!(bpq->acpt_addr[0] & 0x01) && 206 !ether_addr_equal(eth->h_source, bpq->acpt_addr)) 207 goto drop_unlock; 208 209 if (skb_cow(skb, sizeof(struct ethhdr))) 210 goto drop_unlock; 211 212 len = skb->data[0] + skb->data[1] * 256 - 5; 213 214 skb_pull(skb, 2); /* Remove the length bytes */ 215 skb_trim(skb, len); /* Set the length of the data */ 216 217 dev->stats.rx_packets++; 218 dev->stats.rx_bytes += len; 219 220 ptr = skb_push(skb, 1); 221 *ptr = 0; 222 223 skb->protocol = ax25_type_trans(skb, dev); 224 netif_rx(skb); 225 unlock: 226 227 rcu_read_unlock(); 228 229 return 0; 230 drop_unlock: 231 kfree_skb(skb); 232 goto unlock; 233 234 drop: 235 kfree_skb(skb); 236 return 0; 237 } 238 239 /* 240 * Send an AX.25 frame via an ethernet interface 241 */ 242 static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev) 243 { 244 unsigned char *ptr; 245 struct bpqdev *bpq; 246 struct net_device *orig_dev; 247 int size; 248 249 if (skb->protocol == htons(ETH_P_IP)) 250 return ax25_ip_xmit(skb); 251 252 /* 253 * Just to be *really* sure not to send anything if the interface 254 * is down, the ethernet device may have gone. 255 */ 256 if (!netif_running(dev)) { 257 kfree_skb(skb); 258 return NETDEV_TX_OK; 259 } 260 261 skb_pull(skb, 1); /* Drop KISS byte */ 262 size = skb->len; 263 264 /* 265 * We're about to mess with the skb which may still shared with the 266 * generic networking code so unshare and ensure it's got enough 267 * space for the BPQ headers. 268 */ 269 if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) { 270 if (net_ratelimit()) 271 pr_err("bpqether: out of memory\n"); 272 kfree_skb(skb); 273 274 return NETDEV_TX_OK; 275 } 276 277 ptr = skb_push(skb, 2); /* Make space for length */ 278 279 *ptr++ = (size + 5) % 256; 280 *ptr++ = (size + 5) / 256; 281 282 bpq = netdev_priv(dev); 283 284 orig_dev = dev; 285 if ((dev = bpq_get_ether_dev(dev)) == NULL) { 286 orig_dev->stats.tx_dropped++; 287 kfree_skb(skb); 288 return NETDEV_TX_OK; 289 } 290 291 skb->protocol = ax25_type_trans(skb, dev); 292 skb_reset_network_header(skb); 293 dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0); 294 dev->stats.tx_packets++; 295 dev->stats.tx_bytes+=skb->len; 296 297 dev_queue_xmit(skb); 298 netif_wake_queue(dev); 299 return NETDEV_TX_OK; 300 } 301 302 /* 303 * Set AX.25 callsign 304 */ 305 static int bpq_set_mac_address(struct net_device *dev, void *addr) 306 { 307 struct sockaddr *sa = (struct sockaddr *)addr; 308 309 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 310 311 return 0; 312 } 313 314 /* Ioctl commands 315 * 316 * SIOCSBPQETHOPT reserved for enhancements 317 * SIOCSBPQETHADDR set the destination and accepted 318 * source ethernet address (broadcast 319 * or multicast: accept all) 320 */ 321 static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) 322 { 323 struct bpq_ethaddr __user *ethaddr = ifr->ifr_data; 324 struct bpqdev *bpq = netdev_priv(dev); 325 struct bpq_req req; 326 327 if (!capable(CAP_NET_ADMIN)) 328 return -EPERM; 329 330 switch (cmd) { 331 case SIOCSBPQETHOPT: 332 if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req))) 333 return -EFAULT; 334 switch (req.cmd) { 335 case SIOCGBPQETHPARAM: 336 case SIOCSBPQETHPARAM: 337 default: 338 return -EINVAL; 339 } 340 341 break; 342 343 case SIOCSBPQETHADDR: 344 if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN)) 345 return -EFAULT; 346 if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN)) 347 return -EFAULT; 348 break; 349 350 default: 351 return -EINVAL; 352 } 353 354 return 0; 355 } 356 357 /* 358 * open/close a device 359 */ 360 static int bpq_open(struct net_device *dev) 361 { 362 netif_start_queue(dev); 363 return 0; 364 } 365 366 static int bpq_close(struct net_device *dev) 367 { 368 netif_stop_queue(dev); 369 return 0; 370 } 371 372 373 /* ------------------------------------------------------------------------ */ 374 375 376 /* 377 * Proc filesystem 378 */ 379 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos) 380 __acquires(RCU) 381 { 382 int i = 1; 383 struct bpqdev *bpqdev; 384 385 rcu_read_lock(); 386 387 if (*pos == 0) 388 return SEQ_START_TOKEN; 389 390 list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) { 391 if (i == *pos) 392 return bpqdev; 393 } 394 return NULL; 395 } 396 397 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) 398 { 399 struct list_head *p; 400 struct bpqdev *bpqdev = v; 401 402 ++*pos; 403 404 if (v == SEQ_START_TOKEN) 405 p = rcu_dereference(list_next_rcu(&bpq_devices)); 406 else 407 p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list)); 408 409 return (p == &bpq_devices) ? NULL 410 : list_entry(p, struct bpqdev, bpq_list); 411 } 412 413 static void bpq_seq_stop(struct seq_file *seq, void *v) 414 __releases(RCU) 415 { 416 rcu_read_unlock(); 417 } 418 419 420 static int bpq_seq_show(struct seq_file *seq, void *v) 421 { 422 if (v == SEQ_START_TOKEN) 423 seq_puts(seq, 424 "dev ether destination accept from\n"); 425 else { 426 const struct bpqdev *bpqdev = v; 427 428 seq_printf(seq, "%-5s %-10s %pM ", 429 bpqdev->axdev->name, bpqdev->ethdev->name, 430 bpqdev->dest_addr); 431 432 if (is_multicast_ether_addr(bpqdev->acpt_addr)) 433 seq_printf(seq, "*\n"); 434 else 435 seq_printf(seq, "%pM\n", bpqdev->acpt_addr); 436 437 } 438 return 0; 439 } 440 441 static const struct seq_operations bpq_seqops = { 442 .start = bpq_seq_start, 443 .next = bpq_seq_next, 444 .stop = bpq_seq_stop, 445 .show = bpq_seq_show, 446 }; 447 448 /* ------------------------------------------------------------------------ */ 449 450 static const struct net_device_ops bpq_netdev_ops = { 451 .ndo_open = bpq_open, 452 .ndo_stop = bpq_close, 453 .ndo_start_xmit = bpq_xmit, 454 .ndo_set_mac_address = bpq_set_mac_address, 455 .ndo_do_ioctl = bpq_ioctl, 456 }; 457 458 static void bpq_setup(struct net_device *dev) 459 { 460 dev->netdev_ops = &bpq_netdev_ops; 461 dev->needs_free_netdev = true; 462 463 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 464 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); 465 466 dev->flags = 0; 467 dev->features = NETIF_F_LLTX; /* Allow recursion */ 468 469 #if IS_ENABLED(CONFIG_AX25) 470 dev->header_ops = &ax25_header_ops; 471 #endif 472 473 dev->type = ARPHRD_AX25; 474 dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN; 475 dev->mtu = AX25_DEF_PACLEN; 476 dev->addr_len = AX25_ADDR_LEN; 477 478 } 479 480 /* 481 * Setup a new device. 482 */ 483 static int bpq_new_device(struct net_device *edev) 484 { 485 int err; 486 struct net_device *ndev; 487 struct bpqdev *bpq; 488 489 ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN, 490 bpq_setup); 491 if (!ndev) 492 return -ENOMEM; 493 494 495 bpq = netdev_priv(ndev); 496 dev_hold(edev); 497 bpq->ethdev = edev; 498 bpq->axdev = ndev; 499 500 eth_broadcast_addr(bpq->dest_addr); 501 eth_broadcast_addr(bpq->acpt_addr); 502 503 err = register_netdevice(ndev); 504 if (err) 505 goto error; 506 bpq_set_lockdep_class(ndev); 507 508 /* List protected by RTNL */ 509 list_add_rcu(&bpq->bpq_list, &bpq_devices); 510 return 0; 511 512 error: 513 dev_put(edev); 514 free_netdev(ndev); 515 return err; 516 517 } 518 519 static void bpq_free_device(struct net_device *ndev) 520 { 521 struct bpqdev *bpq = netdev_priv(ndev); 522 523 dev_put(bpq->ethdev); 524 list_del_rcu(&bpq->bpq_list); 525 526 unregister_netdevice(ndev); 527 } 528 529 /* 530 * Handle device status changes. 531 */ 532 static int bpq_device_event(struct notifier_block *this, 533 unsigned long event, void *ptr) 534 { 535 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 536 537 if (!net_eq(dev_net(dev), &init_net)) 538 return NOTIFY_DONE; 539 540 if (!dev_is_ethdev(dev)) 541 return NOTIFY_DONE; 542 543 switch (event) { 544 case NETDEV_UP: /* new ethernet device -> new BPQ interface */ 545 if (bpq_get_ax25_dev(dev) == NULL) 546 bpq_new_device(dev); 547 break; 548 549 case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */ 550 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 551 dev_close(dev); 552 break; 553 554 case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */ 555 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 556 bpq_free_device(dev); 557 break; 558 default: 559 break; 560 } 561 562 return NOTIFY_DONE; 563 } 564 565 566 /* ------------------------------------------------------------------------ */ 567 568 /* 569 * Initialize driver. To be called from af_ax25 if not compiled as a 570 * module 571 */ 572 static int __init bpq_init_driver(void) 573 { 574 #ifdef CONFIG_PROC_FS 575 if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) { 576 printk(KERN_ERR 577 "bpq: cannot create /proc/net/bpqether entry.\n"); 578 return -ENOENT; 579 } 580 #endif /* CONFIG_PROC_FS */ 581 582 dev_add_pack(&bpq_packet_type); 583 584 register_netdevice_notifier(&bpq_dev_notifier); 585 586 printk(banner); 587 588 return 0; 589 } 590 591 static void __exit bpq_cleanup_driver(void) 592 { 593 struct bpqdev *bpq; 594 595 dev_remove_pack(&bpq_packet_type); 596 597 unregister_netdevice_notifier(&bpq_dev_notifier); 598 599 remove_proc_entry("bpqether", init_net.proc_net); 600 601 rtnl_lock(); 602 while (!list_empty(&bpq_devices)) { 603 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list); 604 bpq_free_device(bpq->axdev); 605 } 606 rtnl_unlock(); 607 } 608 609 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>"); 610 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet"); 611 MODULE_LICENSE("GPL"); 612 module_init(bpq_init_driver); 613 module_exit(bpq_cleanup_driver); 614