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