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