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