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 char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF}; 93 94 static char bpq_eth_addr[6]; 95 96 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *); 97 static int bpq_device_event(struct notifier_block *, unsigned long, void *); 98 99 static struct packet_type bpq_packet_type __read_mostly = { 100 .type = cpu_to_be16(ETH_P_BPQ), 101 .func = bpq_rcv, 102 }; 103 104 static struct notifier_block bpq_dev_notifier = { 105 .notifier_call = bpq_device_event, 106 }; 107 108 109 struct bpqdev { 110 struct list_head bpq_list; /* list of bpq devices chain */ 111 struct net_device *ethdev; /* link to ethernet device */ 112 struct net_device *axdev; /* bpq device (bpq#) */ 113 char dest_addr[6]; /* ether destination address */ 114 char acpt_addr[6]; /* accept ether frames from this address only */ 115 }; 116 117 static LIST_HEAD(bpq_devices); 118 119 /* 120 * bpqether network devices are paired with ethernet devices below them, so 121 * form a special "super class" of normal ethernet devices; split their locks 122 * off into a separate class since they always nest. 123 */ 124 static struct lock_class_key bpq_netdev_xmit_lock_key; 125 static struct lock_class_key bpq_netdev_addr_lock_key; 126 127 static void bpq_set_lockdep_class_one(struct net_device *dev, 128 struct netdev_queue *txq, 129 void *_unused) 130 { 131 lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key); 132 } 133 134 static void bpq_set_lockdep_class(struct net_device *dev) 135 { 136 lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key); 137 netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL); 138 } 139 140 /* ------------------------------------------------------------------------ */ 141 142 143 /* 144 * Get the ethernet device for a BPQ device 145 */ 146 static inline struct net_device *bpq_get_ether_dev(struct net_device *dev) 147 { 148 struct bpqdev *bpq = netdev_priv(dev); 149 150 return bpq ? bpq->ethdev : NULL; 151 } 152 153 /* 154 * Get the BPQ device for the ethernet device 155 */ 156 static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev) 157 { 158 struct bpqdev *bpq; 159 160 list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) { 161 if (bpq->ethdev == dev) 162 return bpq->axdev; 163 } 164 return NULL; 165 } 166 167 static inline int dev_is_ethdev(struct net_device *dev) 168 { 169 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); 170 } 171 172 /* ------------------------------------------------------------------------ */ 173 174 175 /* 176 * Receive an AX.25 frame via an ethernet interface. 177 */ 178 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) 179 { 180 int len; 181 char * ptr; 182 struct ethhdr *eth; 183 struct bpqdev *bpq; 184 185 if (!net_eq(dev_net(dev), &init_net)) 186 goto drop; 187 188 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 189 return NET_RX_DROP; 190 191 if (!pskb_may_pull(skb, sizeof(struct ethhdr))) 192 goto drop; 193 194 rcu_read_lock(); 195 dev = bpq_get_ax25_dev(dev); 196 197 if (dev == NULL || !netif_running(dev)) 198 goto drop_unlock; 199 200 /* 201 * if we want to accept frames from just one ethernet device 202 * we check the source address of the sender. 203 */ 204 205 bpq = netdev_priv(dev); 206 207 eth = eth_hdr(skb); 208 209 if (!(bpq->acpt_addr[0] & 0x01) && 210 !ether_addr_equal(eth->h_source, bpq->acpt_addr)) 211 goto drop_unlock; 212 213 if (skb_cow(skb, sizeof(struct ethhdr))) 214 goto drop_unlock; 215 216 len = skb->data[0] + skb->data[1] * 256 - 5; 217 218 skb_pull(skb, 2); /* Remove the length bytes */ 219 skb_trim(skb, len); /* Set the length of the data */ 220 221 dev->stats.rx_packets++; 222 dev->stats.rx_bytes += len; 223 224 ptr = skb_push(skb, 1); 225 *ptr = 0; 226 227 skb->protocol = ax25_type_trans(skb, dev); 228 netif_rx(skb); 229 unlock: 230 231 rcu_read_unlock(); 232 233 return 0; 234 drop_unlock: 235 kfree_skb(skb); 236 goto unlock; 237 238 drop: 239 kfree_skb(skb); 240 return 0; 241 } 242 243 /* 244 * Send an AX.25 frame via an ethernet interface 245 */ 246 static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev) 247 { 248 unsigned char *ptr; 249 struct bpqdev *bpq; 250 struct net_device *orig_dev; 251 int size; 252 253 if (skb->protocol == htons(ETH_P_IP)) 254 return ax25_ip_xmit(skb); 255 256 /* 257 * Just to be *really* sure not to send anything if the interface 258 * is down, the ethernet device may have gone. 259 */ 260 if (!netif_running(dev)) { 261 kfree_skb(skb); 262 return NETDEV_TX_OK; 263 } 264 265 skb_pull(skb, 1); /* Drop KISS byte */ 266 size = skb->len; 267 268 /* 269 * We're about to mess with the skb which may still shared with the 270 * generic networking code so unshare and ensure it's got enough 271 * space for the BPQ headers. 272 */ 273 if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) { 274 if (net_ratelimit()) 275 pr_err("bpqether: out of memory\n"); 276 kfree_skb(skb); 277 278 return NETDEV_TX_OK; 279 } 280 281 ptr = skb_push(skb, 2); /* Make space for length */ 282 283 *ptr++ = (size + 5) % 256; 284 *ptr++ = (size + 5) / 256; 285 286 bpq = netdev_priv(dev); 287 288 orig_dev = dev; 289 if ((dev = bpq_get_ether_dev(dev)) == NULL) { 290 orig_dev->stats.tx_dropped++; 291 kfree_skb(skb); 292 return NETDEV_TX_OK; 293 } 294 295 skb->protocol = ax25_type_trans(skb, dev); 296 skb_reset_network_header(skb); 297 dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0); 298 dev->stats.tx_packets++; 299 dev->stats.tx_bytes+=skb->len; 300 301 dev_queue_xmit(skb); 302 netif_wake_queue(dev); 303 return NETDEV_TX_OK; 304 } 305 306 /* 307 * Set AX.25 callsign 308 */ 309 static int bpq_set_mac_address(struct net_device *dev, void *addr) 310 { 311 struct sockaddr *sa = (struct sockaddr *)addr; 312 313 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 314 315 return 0; 316 } 317 318 /* Ioctl commands 319 * 320 * SIOCSBPQETHOPT reserved for enhancements 321 * SIOCSBPQETHADDR set the destination and accepted 322 * source ethernet address (broadcast 323 * or multicast: accept all) 324 */ 325 static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) 326 { 327 struct bpq_ethaddr __user *ethaddr = ifr->ifr_data; 328 struct bpqdev *bpq = netdev_priv(dev); 329 struct bpq_req req; 330 331 if (!capable(CAP_NET_ADMIN)) 332 return -EPERM; 333 334 switch (cmd) { 335 case SIOCSBPQETHOPT: 336 if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req))) 337 return -EFAULT; 338 switch (req.cmd) { 339 case SIOCGBPQETHPARAM: 340 case SIOCSBPQETHPARAM: 341 default: 342 return -EINVAL; 343 } 344 345 break; 346 347 case SIOCSBPQETHADDR: 348 if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN)) 349 return -EFAULT; 350 if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN)) 351 return -EFAULT; 352 break; 353 354 default: 355 return -EINVAL; 356 } 357 358 return 0; 359 } 360 361 /* 362 * open/close a device 363 */ 364 static int bpq_open(struct net_device *dev) 365 { 366 netif_start_queue(dev); 367 return 0; 368 } 369 370 static int bpq_close(struct net_device *dev) 371 { 372 netif_stop_queue(dev); 373 return 0; 374 } 375 376 377 /* ------------------------------------------------------------------------ */ 378 379 380 /* 381 * Proc filesystem 382 */ 383 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos) 384 __acquires(RCU) 385 { 386 int i = 1; 387 struct bpqdev *bpqdev; 388 389 rcu_read_lock(); 390 391 if (*pos == 0) 392 return SEQ_START_TOKEN; 393 394 list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) { 395 if (i == *pos) 396 return bpqdev; 397 } 398 return NULL; 399 } 400 401 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) 402 { 403 struct list_head *p; 404 struct bpqdev *bpqdev = v; 405 406 ++*pos; 407 408 if (v == SEQ_START_TOKEN) 409 p = rcu_dereference(list_next_rcu(&bpq_devices)); 410 else 411 p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list)); 412 413 return (p == &bpq_devices) ? NULL 414 : list_entry(p, struct bpqdev, bpq_list); 415 } 416 417 static void bpq_seq_stop(struct seq_file *seq, void *v) 418 __releases(RCU) 419 { 420 rcu_read_unlock(); 421 } 422 423 424 static int bpq_seq_show(struct seq_file *seq, void *v) 425 { 426 if (v == SEQ_START_TOKEN) 427 seq_puts(seq, 428 "dev ether destination accept from\n"); 429 else { 430 const struct bpqdev *bpqdev = v; 431 432 seq_printf(seq, "%-5s %-10s %pM ", 433 bpqdev->axdev->name, bpqdev->ethdev->name, 434 bpqdev->dest_addr); 435 436 if (is_multicast_ether_addr(bpqdev->acpt_addr)) 437 seq_printf(seq, "*\n"); 438 else 439 seq_printf(seq, "%pM\n", bpqdev->acpt_addr); 440 441 } 442 return 0; 443 } 444 445 static const struct seq_operations bpq_seqops = { 446 .start = bpq_seq_start, 447 .next = bpq_seq_next, 448 .stop = bpq_seq_stop, 449 .show = bpq_seq_show, 450 }; 451 452 static int bpq_info_open(struct inode *inode, struct file *file) 453 { 454 return seq_open(file, &bpq_seqops); 455 } 456 457 static const struct file_operations bpq_info_fops = { 458 .owner = THIS_MODULE, 459 .open = bpq_info_open, 460 .read = seq_read, 461 .llseek = seq_lseek, 462 .release = seq_release, 463 }; 464 465 466 /* ------------------------------------------------------------------------ */ 467 468 static const struct net_device_ops bpq_netdev_ops = { 469 .ndo_open = bpq_open, 470 .ndo_stop = bpq_close, 471 .ndo_start_xmit = bpq_xmit, 472 .ndo_set_mac_address = bpq_set_mac_address, 473 .ndo_do_ioctl = bpq_ioctl, 474 }; 475 476 static void bpq_setup(struct net_device *dev) 477 { 478 dev->netdev_ops = &bpq_netdev_ops; 479 dev->needs_free_netdev = true; 480 481 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 482 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); 483 484 dev->flags = 0; 485 dev->features = NETIF_F_LLTX; /* Allow recursion */ 486 487 #if IS_ENABLED(CONFIG_AX25) 488 dev->header_ops = &ax25_header_ops; 489 #endif 490 491 dev->type = ARPHRD_AX25; 492 dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN; 493 dev->mtu = AX25_DEF_PACLEN; 494 dev->addr_len = AX25_ADDR_LEN; 495 496 } 497 498 /* 499 * Setup a new device. 500 */ 501 static int bpq_new_device(struct net_device *edev) 502 { 503 int err; 504 struct net_device *ndev; 505 struct bpqdev *bpq; 506 507 ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN, 508 bpq_setup); 509 if (!ndev) 510 return -ENOMEM; 511 512 513 bpq = netdev_priv(ndev); 514 dev_hold(edev); 515 bpq->ethdev = edev; 516 bpq->axdev = ndev; 517 518 memcpy(bpq->dest_addr, bcast_addr, sizeof(bpq_eth_addr)); 519 memcpy(bpq->acpt_addr, bcast_addr, sizeof(bpq_eth_addr)); 520 521 err = register_netdevice(ndev); 522 if (err) 523 goto error; 524 bpq_set_lockdep_class(ndev); 525 526 /* List protected by RTNL */ 527 list_add_rcu(&bpq->bpq_list, &bpq_devices); 528 return 0; 529 530 error: 531 dev_put(edev); 532 free_netdev(ndev); 533 return err; 534 535 } 536 537 static void bpq_free_device(struct net_device *ndev) 538 { 539 struct bpqdev *bpq = netdev_priv(ndev); 540 541 dev_put(bpq->ethdev); 542 list_del_rcu(&bpq->bpq_list); 543 544 unregister_netdevice(ndev); 545 } 546 547 /* 548 * Handle device status changes. 549 */ 550 static int bpq_device_event(struct notifier_block *this, 551 unsigned long event, void *ptr) 552 { 553 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 554 555 if (!net_eq(dev_net(dev), &init_net)) 556 return NOTIFY_DONE; 557 558 if (!dev_is_ethdev(dev)) 559 return NOTIFY_DONE; 560 561 switch (event) { 562 case NETDEV_UP: /* new ethernet device -> new BPQ interface */ 563 if (bpq_get_ax25_dev(dev) == NULL) 564 bpq_new_device(dev); 565 break; 566 567 case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */ 568 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 569 dev_close(dev); 570 break; 571 572 case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */ 573 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 574 bpq_free_device(dev); 575 break; 576 default: 577 break; 578 } 579 580 return NOTIFY_DONE; 581 } 582 583 584 /* ------------------------------------------------------------------------ */ 585 586 /* 587 * Initialize driver. To be called from af_ax25 if not compiled as a 588 * module 589 */ 590 static int __init bpq_init_driver(void) 591 { 592 #ifdef CONFIG_PROC_FS 593 if (!proc_create("bpqether", S_IRUGO, init_net.proc_net, 594 &bpq_info_fops)) { 595 printk(KERN_ERR 596 "bpq: cannot create /proc/net/bpqether entry.\n"); 597 return -ENOENT; 598 } 599 #endif /* CONFIG_PROC_FS */ 600 601 dev_add_pack(&bpq_packet_type); 602 603 register_netdevice_notifier(&bpq_dev_notifier); 604 605 printk(banner); 606 607 return 0; 608 } 609 610 static void __exit bpq_cleanup_driver(void) 611 { 612 struct bpqdev *bpq; 613 614 dev_remove_pack(&bpq_packet_type); 615 616 unregister_netdevice_notifier(&bpq_dev_notifier); 617 618 remove_proc_entry("bpqether", init_net.proc_net); 619 620 rtnl_lock(); 621 while (!list_empty(&bpq_devices)) { 622 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list); 623 bpq_free_device(bpq->axdev); 624 } 625 rtnl_unlock(); 626 } 627 628 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>"); 629 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet"); 630 MODULE_LICENSE("GPL"); 631 module_init(bpq_init_driver); 632 module_exit(bpq_cleanup_driver); 633