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 lockdep_rtnl_is_held()) { 153 if (bpq->ethdev == dev) 154 return bpq->axdev; 155 } 156 return NULL; 157 } 158 159 static inline int dev_is_ethdev(struct net_device *dev) 160 { 161 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); 162 } 163 164 /* ------------------------------------------------------------------------ */ 165 166 167 /* 168 * Receive an AX.25 frame via an ethernet interface. 169 */ 170 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) 171 { 172 int len; 173 char * ptr; 174 struct ethhdr *eth; 175 struct bpqdev *bpq; 176 177 if (!net_eq(dev_net(dev), &init_net)) 178 goto drop; 179 180 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 181 return NET_RX_DROP; 182 183 if (!pskb_may_pull(skb, sizeof(struct ethhdr))) 184 goto drop; 185 186 rcu_read_lock(); 187 dev = bpq_get_ax25_dev(dev); 188 189 if (dev == NULL || !netif_running(dev)) 190 goto drop_unlock; 191 192 /* 193 * if we want to accept frames from just one ethernet device 194 * we check the source address of the sender. 195 */ 196 197 bpq = netdev_priv(dev); 198 199 eth = eth_hdr(skb); 200 201 if (!(bpq->acpt_addr[0] & 0x01) && 202 !ether_addr_equal(eth->h_source, bpq->acpt_addr)) 203 goto drop_unlock; 204 205 if (skb_cow(skb, sizeof(struct ethhdr))) 206 goto drop_unlock; 207 208 len = skb->data[0] + skb->data[1] * 256 - 5; 209 210 skb_pull(skb, 2); /* Remove the length bytes */ 211 skb_trim(skb, len); /* Set the length of the data */ 212 213 dev->stats.rx_packets++; 214 dev->stats.rx_bytes += len; 215 216 ptr = skb_push(skb, 1); 217 *ptr = 0; 218 219 skb->protocol = ax25_type_trans(skb, dev); 220 netif_rx(skb); 221 unlock: 222 223 rcu_read_unlock(); 224 225 return 0; 226 drop_unlock: 227 kfree_skb(skb); 228 goto unlock; 229 230 drop: 231 kfree_skb(skb); 232 return 0; 233 } 234 235 /* 236 * Send an AX.25 frame via an ethernet interface 237 */ 238 static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev) 239 { 240 unsigned char *ptr; 241 struct bpqdev *bpq; 242 struct net_device *orig_dev; 243 int size; 244 245 if (skb->protocol == htons(ETH_P_IP)) 246 return ax25_ip_xmit(skb); 247 248 /* 249 * Just to be *really* sure not to send anything if the interface 250 * is down, the ethernet device may have gone. 251 */ 252 if (!netif_running(dev)) { 253 kfree_skb(skb); 254 return NETDEV_TX_OK; 255 } 256 257 skb_pull(skb, 1); /* Drop KISS byte */ 258 size = skb->len; 259 260 /* 261 * We're about to mess with the skb which may still shared with the 262 * generic networking code so unshare and ensure it's got enough 263 * space for the BPQ headers. 264 */ 265 if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) { 266 if (net_ratelimit()) 267 pr_err("bpqether: out of memory\n"); 268 kfree_skb(skb); 269 270 return NETDEV_TX_OK; 271 } 272 273 ptr = skb_push(skb, 2); /* Make space for length */ 274 275 *ptr++ = (size + 5) % 256; 276 *ptr++ = (size + 5) / 256; 277 278 bpq = netdev_priv(dev); 279 280 orig_dev = dev; 281 if ((dev = bpq_get_ether_dev(dev)) == NULL) { 282 orig_dev->stats.tx_dropped++; 283 kfree_skb(skb); 284 return NETDEV_TX_OK; 285 } 286 287 skb->protocol = ax25_type_trans(skb, dev); 288 skb_reset_network_header(skb); 289 dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0); 290 dev->stats.tx_packets++; 291 dev->stats.tx_bytes+=skb->len; 292 293 dev_queue_xmit(skb); 294 netif_wake_queue(dev); 295 return NETDEV_TX_OK; 296 } 297 298 /* 299 * Set AX.25 callsign 300 */ 301 static int bpq_set_mac_address(struct net_device *dev, void *addr) 302 { 303 struct sockaddr *sa = (struct sockaddr *)addr; 304 305 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 306 307 return 0; 308 } 309 310 /* Ioctl commands 311 * 312 * SIOCSBPQETHOPT reserved for enhancements 313 * SIOCSBPQETHADDR set the destination and accepted 314 * source ethernet address (broadcast 315 * or multicast: accept all) 316 */ 317 static int bpq_siocdevprivate(struct net_device *dev, struct ifreq *ifr, 318 void __user *data, int cmd) 319 { 320 struct bpq_ethaddr __user *ethaddr = data; 321 struct bpqdev *bpq = netdev_priv(dev); 322 struct bpq_req req; 323 324 if (!capable(CAP_NET_ADMIN)) 325 return -EPERM; 326 327 switch (cmd) { 328 case SIOCSBPQETHOPT: 329 if (copy_from_user(&req, data, sizeof(struct bpq_req))) 330 return -EFAULT; 331 switch (req.cmd) { 332 case SIOCGBPQETHPARAM: 333 case SIOCSBPQETHPARAM: 334 default: 335 return -EINVAL; 336 } 337 338 break; 339 340 case SIOCSBPQETHADDR: 341 if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN)) 342 return -EFAULT; 343 if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN)) 344 return -EFAULT; 345 break; 346 347 default: 348 return -EINVAL; 349 } 350 351 return 0; 352 } 353 354 /* 355 * open/close a device 356 */ 357 static int bpq_open(struct net_device *dev) 358 { 359 netif_start_queue(dev); 360 return 0; 361 } 362 363 static int bpq_close(struct net_device *dev) 364 { 365 netif_stop_queue(dev); 366 return 0; 367 } 368 369 370 /* ------------------------------------------------------------------------ */ 371 372 #ifdef CONFIG_PROC_FS 373 /* 374 * Proc filesystem 375 */ 376 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos) 377 __acquires(RCU) 378 { 379 int i = 1; 380 struct bpqdev *bpqdev; 381 382 rcu_read_lock(); 383 384 if (*pos == 0) 385 return SEQ_START_TOKEN; 386 387 list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) { 388 if (i == *pos) 389 return bpqdev; 390 } 391 return NULL; 392 } 393 394 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) 395 { 396 struct list_head *p; 397 struct bpqdev *bpqdev = v; 398 399 ++*pos; 400 401 if (v == SEQ_START_TOKEN) 402 p = rcu_dereference(list_next_rcu(&bpq_devices)); 403 else 404 p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list)); 405 406 return (p == &bpq_devices) ? NULL 407 : list_entry(p, struct bpqdev, bpq_list); 408 } 409 410 static void bpq_seq_stop(struct seq_file *seq, void *v) 411 __releases(RCU) 412 { 413 rcu_read_unlock(); 414 } 415 416 417 static int bpq_seq_show(struct seq_file *seq, void *v) 418 { 419 if (v == SEQ_START_TOKEN) 420 seq_puts(seq, 421 "dev ether destination accept from\n"); 422 else { 423 const struct bpqdev *bpqdev = v; 424 425 seq_printf(seq, "%-5s %-10s %pM ", 426 bpqdev->axdev->name, bpqdev->ethdev->name, 427 bpqdev->dest_addr); 428 429 if (is_multicast_ether_addr(bpqdev->acpt_addr)) 430 seq_printf(seq, "*\n"); 431 else 432 seq_printf(seq, "%pM\n", bpqdev->acpt_addr); 433 434 } 435 return 0; 436 } 437 438 static const struct seq_operations bpq_seqops = { 439 .start = bpq_seq_start, 440 .next = bpq_seq_next, 441 .stop = bpq_seq_stop, 442 .show = bpq_seq_show, 443 }; 444 #endif 445 /* ------------------------------------------------------------------------ */ 446 447 static const struct net_device_ops bpq_netdev_ops = { 448 .ndo_open = bpq_open, 449 .ndo_stop = bpq_close, 450 .ndo_start_xmit = bpq_xmit, 451 .ndo_set_mac_address = bpq_set_mac_address, 452 .ndo_siocdevprivate = bpq_siocdevprivate, 453 }; 454 455 static void bpq_setup(struct net_device *dev) 456 { 457 dev->netdev_ops = &bpq_netdev_ops; 458 dev->needs_free_netdev = true; 459 460 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 461 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); 462 463 dev->flags = 0; 464 dev->features = NETIF_F_LLTX; /* Allow recursion */ 465 466 #if IS_ENABLED(CONFIG_AX25) 467 dev->header_ops = &ax25_header_ops; 468 #endif 469 470 dev->type = ARPHRD_AX25; 471 dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN; 472 dev->mtu = AX25_DEF_PACLEN; 473 dev->addr_len = AX25_ADDR_LEN; 474 475 } 476 477 /* 478 * Setup a new device. 479 */ 480 static int bpq_new_device(struct net_device *edev) 481 { 482 int err; 483 struct net_device *ndev; 484 struct bpqdev *bpq; 485 486 ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN, 487 bpq_setup); 488 if (!ndev) 489 return -ENOMEM; 490 491 492 bpq = netdev_priv(ndev); 493 dev_hold(edev); 494 bpq->ethdev = edev; 495 bpq->axdev = ndev; 496 497 eth_broadcast_addr(bpq->dest_addr); 498 eth_broadcast_addr(bpq->acpt_addr); 499 500 err = register_netdevice(ndev); 501 if (err) 502 goto error; 503 bpq_set_lockdep_class(ndev); 504 505 /* List protected by RTNL */ 506 list_add_rcu(&bpq->bpq_list, &bpq_devices); 507 return 0; 508 509 error: 510 dev_put(edev); 511 free_netdev(ndev); 512 return err; 513 514 } 515 516 static void bpq_free_device(struct net_device *ndev) 517 { 518 struct bpqdev *bpq = netdev_priv(ndev); 519 520 dev_put(bpq->ethdev); 521 list_del_rcu(&bpq->bpq_list); 522 523 unregister_netdevice(ndev); 524 } 525 526 /* 527 * Handle device status changes. 528 */ 529 static int bpq_device_event(struct notifier_block *this, 530 unsigned long event, void *ptr) 531 { 532 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 533 534 if (!net_eq(dev_net(dev), &init_net)) 535 return NOTIFY_DONE; 536 537 if (!dev_is_ethdev(dev)) 538 return NOTIFY_DONE; 539 540 switch (event) { 541 case NETDEV_UP: /* new ethernet device -> new BPQ interface */ 542 if (bpq_get_ax25_dev(dev) == NULL) 543 bpq_new_device(dev); 544 break; 545 546 case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */ 547 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 548 dev_close(dev); 549 break; 550 551 case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */ 552 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 553 bpq_free_device(dev); 554 break; 555 default: 556 break; 557 } 558 559 return NOTIFY_DONE; 560 } 561 562 563 /* ------------------------------------------------------------------------ */ 564 565 /* 566 * Initialize driver. To be called from af_ax25 if not compiled as a 567 * module 568 */ 569 static int __init bpq_init_driver(void) 570 { 571 #ifdef CONFIG_PROC_FS 572 if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) { 573 printk(KERN_ERR 574 "bpq: cannot create /proc/net/bpqether entry.\n"); 575 return -ENOENT; 576 } 577 #endif /* CONFIG_PROC_FS */ 578 579 dev_add_pack(&bpq_packet_type); 580 581 register_netdevice_notifier(&bpq_dev_notifier); 582 583 printk(banner); 584 585 return 0; 586 } 587 588 static void __exit bpq_cleanup_driver(void) 589 { 590 struct bpqdev *bpq; 591 592 dev_remove_pack(&bpq_packet_type); 593 594 unregister_netdevice_notifier(&bpq_dev_notifier); 595 596 remove_proc_entry("bpqether", init_net.proc_net); 597 598 rtnl_lock(); 599 while (!list_empty(&bpq_devices)) { 600 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list); 601 bpq_free_device(bpq->axdev); 602 } 603 rtnl_unlock(); 604 } 605 606 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>"); 607 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet"); 608 MODULE_LICENSE("GPL"); 609 module_init(bpq_init_driver); 610 module_exit(bpq_cleanup_driver); 611