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/netdev_lock.h> 81 #include <net/net_namespace.h> 82 83 #include <linux/bpqether.h> 84 85 static const char banner[] __initconst = KERN_INFO \ 86 "AX.25: bpqether driver version 004\n"; 87 88 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *); 89 static int bpq_device_event(struct notifier_block *, unsigned long, void *); 90 91 static struct packet_type bpq_packet_type __read_mostly = { 92 .type = cpu_to_be16(ETH_P_BPQ), 93 .func = bpq_rcv, 94 }; 95 96 static struct notifier_block bpq_dev_notifier = { 97 .notifier_call = bpq_device_event, 98 }; 99 100 101 struct bpqdev { 102 struct list_head bpq_list; /* list of bpq devices chain */ 103 struct net_device *ethdev; /* link to ethernet device */ 104 struct net_device *axdev; /* bpq device (bpq#) */ 105 char dest_addr[6]; /* ether destination address */ 106 char acpt_addr[6]; /* accept ether frames from this address only */ 107 }; 108 109 static LIST_HEAD(bpq_devices); 110 111 /* ------------------------------------------------------------------------ */ 112 113 114 /* 115 * Get the ethernet device for a BPQ device 116 */ 117 static inline struct net_device *bpq_get_ether_dev(struct net_device *dev) 118 { 119 struct bpqdev *bpq = netdev_priv(dev); 120 121 return bpq ? bpq->ethdev : NULL; 122 } 123 124 /* 125 * Get the BPQ device for the ethernet device 126 */ 127 static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev) 128 { 129 struct bpqdev *bpq; 130 131 list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list, 132 lockdep_rtnl_is_held()) { 133 if (bpq->ethdev == dev) 134 return bpq->axdev; 135 } 136 return NULL; 137 } 138 139 static inline int dev_is_ethdev(struct net_device *dev) 140 { 141 return dev->type == ARPHRD_ETHER && !netdev_need_ops_lock(dev); 142 } 143 144 /* ------------------------------------------------------------------------ */ 145 146 147 /* 148 * Receive an AX.25 frame via an ethernet interface. 149 */ 150 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) 151 { 152 int len; 153 char * ptr; 154 struct ethhdr *eth; 155 struct bpqdev *bpq; 156 157 if (!net_eq(dev_net(dev), &init_net)) 158 goto drop; 159 160 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 161 return NET_RX_DROP; 162 163 if (!pskb_may_pull(skb, sizeof(struct ethhdr))) 164 goto drop; 165 166 rcu_read_lock(); 167 dev = bpq_get_ax25_dev(dev); 168 169 if (dev == NULL || !netif_running(dev)) 170 goto drop_unlock; 171 172 /* 173 * if we want to accept frames from just one ethernet device 174 * we check the source address of the sender. 175 */ 176 177 bpq = netdev_priv(dev); 178 179 eth = eth_hdr(skb); 180 181 if (!(bpq->acpt_addr[0] & 0x01) && 182 !ether_addr_equal(eth->h_source, bpq->acpt_addr)) 183 goto drop_unlock; 184 185 if (skb_cow(skb, sizeof(struct ethhdr))) 186 goto drop_unlock; 187 188 len = skb->data[0] + skb->data[1] * 256 - 5; 189 190 if (len < 0 || len > skb->len - 2) 191 goto drop_unlock; 192 193 skb_pull(skb, 2); /* Remove the length bytes */ 194 skb_trim(skb, len); /* Set the length of the data */ 195 196 dev->stats.rx_packets++; 197 dev->stats.rx_bytes += len; 198 199 ptr = skb_push(skb, 1); 200 *ptr = 0; 201 202 skb->protocol = ax25_type_trans(skb, dev); 203 netif_rx(skb); 204 unlock: 205 206 rcu_read_unlock(); 207 208 return 0; 209 drop_unlock: 210 kfree_skb(skb); 211 goto unlock; 212 213 drop: 214 kfree_skb(skb); 215 return 0; 216 } 217 218 /* 219 * Send an AX.25 frame via an ethernet interface 220 */ 221 static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev) 222 { 223 unsigned char *ptr; 224 struct bpqdev *bpq; 225 struct net_device *orig_dev; 226 int size; 227 228 if (skb->protocol == htons(ETH_P_IP)) 229 return ax25_ip_xmit(skb); 230 231 /* 232 * Just to be *really* sure not to send anything if the interface 233 * is down, the ethernet device may have gone. 234 */ 235 if (!netif_running(dev)) { 236 kfree_skb(skb); 237 return NETDEV_TX_OK; 238 } 239 240 skb_pull(skb, 1); /* Drop KISS byte */ 241 size = skb->len; 242 243 /* 244 * We're about to mess with the skb which may still shared with the 245 * generic networking code so unshare and ensure it's got enough 246 * space for the BPQ headers. 247 */ 248 if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) { 249 if (net_ratelimit()) 250 pr_err("bpqether: out of memory\n"); 251 kfree_skb(skb); 252 253 return NETDEV_TX_OK; 254 } 255 256 ptr = skb_push(skb, 2); /* Make space for length */ 257 258 *ptr++ = (size + 5) % 256; 259 *ptr++ = (size + 5) / 256; 260 261 bpq = netdev_priv(dev); 262 263 orig_dev = dev; 264 if ((dev = bpq_get_ether_dev(dev)) == NULL) { 265 orig_dev->stats.tx_dropped++; 266 kfree_skb(skb); 267 return NETDEV_TX_OK; 268 } 269 270 skb->protocol = ax25_type_trans(skb, dev); 271 skb_reset_network_header(skb); 272 dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0); 273 dev->stats.tx_packets++; 274 dev->stats.tx_bytes+=skb->len; 275 276 dev_queue_xmit(skb); 277 netif_wake_queue(dev); 278 return NETDEV_TX_OK; 279 } 280 281 /* 282 * Set AX.25 callsign 283 */ 284 static int bpq_set_mac_address(struct net_device *dev, void *addr) 285 { 286 struct sockaddr *sa = (struct sockaddr *)addr; 287 288 dev_addr_set(dev, sa->sa_data); 289 290 return 0; 291 } 292 293 /* Ioctl commands 294 * 295 * SIOCSBPQETHOPT reserved for enhancements 296 * SIOCSBPQETHADDR set the destination and accepted 297 * source ethernet address (broadcast 298 * or multicast: accept all) 299 */ 300 static int bpq_siocdevprivate(struct net_device *dev, struct ifreq *ifr, 301 void __user *data, int cmd) 302 { 303 struct bpq_ethaddr __user *ethaddr = data; 304 struct bpqdev *bpq = netdev_priv(dev); 305 struct bpq_req req; 306 307 if (!capable(CAP_NET_ADMIN)) 308 return -EPERM; 309 310 switch (cmd) { 311 case SIOCSBPQETHOPT: 312 if (copy_from_user(&req, data, sizeof(struct bpq_req))) 313 return -EFAULT; 314 switch (req.cmd) { 315 case SIOCGBPQETHPARAM: 316 case SIOCSBPQETHPARAM: 317 default: 318 return -EINVAL; 319 } 320 321 break; 322 323 case SIOCSBPQETHADDR: 324 if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN)) 325 return -EFAULT; 326 if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN)) 327 return -EFAULT; 328 break; 329 330 default: 331 return -EINVAL; 332 } 333 334 return 0; 335 } 336 337 /* 338 * open/close a device 339 */ 340 static int bpq_open(struct net_device *dev) 341 { 342 netif_start_queue(dev); 343 return 0; 344 } 345 346 static int bpq_close(struct net_device *dev) 347 { 348 netif_stop_queue(dev); 349 return 0; 350 } 351 352 353 /* ------------------------------------------------------------------------ */ 354 355 #ifdef CONFIG_PROC_FS 356 /* 357 * Proc filesystem 358 */ 359 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos) 360 __acquires(RCU) 361 { 362 int i = 1; 363 struct bpqdev *bpqdev; 364 365 rcu_read_lock(); 366 367 if (*pos == 0) 368 return SEQ_START_TOKEN; 369 370 list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) { 371 if (i == *pos) 372 return bpqdev; 373 } 374 return NULL; 375 } 376 377 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) 378 { 379 struct list_head *p; 380 struct bpqdev *bpqdev = v; 381 382 ++*pos; 383 384 if (v == SEQ_START_TOKEN) 385 p = rcu_dereference(list_next_rcu(&bpq_devices)); 386 else 387 p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list)); 388 389 return (p == &bpq_devices) ? NULL 390 : list_entry(p, struct bpqdev, bpq_list); 391 } 392 393 static void bpq_seq_stop(struct seq_file *seq, void *v) 394 __releases(RCU) 395 { 396 rcu_read_unlock(); 397 } 398 399 400 static int bpq_seq_show(struct seq_file *seq, void *v) 401 { 402 if (v == SEQ_START_TOKEN) 403 seq_puts(seq, 404 "dev ether destination accept from\n"); 405 else { 406 const struct bpqdev *bpqdev = v; 407 408 seq_printf(seq, "%-5s %-10s %pM ", 409 bpqdev->axdev->name, bpqdev->ethdev->name, 410 bpqdev->dest_addr); 411 412 if (is_multicast_ether_addr(bpqdev->acpt_addr)) 413 seq_printf(seq, "*\n"); 414 else 415 seq_printf(seq, "%pM\n", bpqdev->acpt_addr); 416 417 } 418 return 0; 419 } 420 421 static const struct seq_operations bpq_seqops = { 422 .start = bpq_seq_start, 423 .next = bpq_seq_next, 424 .stop = bpq_seq_stop, 425 .show = bpq_seq_show, 426 }; 427 #endif 428 /* ------------------------------------------------------------------------ */ 429 430 static const struct net_device_ops bpq_netdev_ops = { 431 .ndo_open = bpq_open, 432 .ndo_stop = bpq_close, 433 .ndo_start_xmit = bpq_xmit, 434 .ndo_set_mac_address = bpq_set_mac_address, 435 .ndo_siocdevprivate = bpq_siocdevprivate, 436 }; 437 438 static void bpq_setup(struct net_device *dev) 439 { 440 netdev_lockdep_set_classes(dev); 441 442 dev->netdev_ops = &bpq_netdev_ops; 443 dev->needs_free_netdev = true; 444 445 dev->flags = 0; 446 dev->lltx = true; /* Allow recursion */ 447 448 #if IS_ENABLED(CONFIG_AX25) 449 dev->header_ops = &ax25_header_ops; 450 #endif 451 452 dev->type = ARPHRD_AX25; 453 dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN; 454 dev->mtu = AX25_DEF_PACLEN; 455 dev->addr_len = AX25_ADDR_LEN; 456 457 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 458 dev_addr_set(dev, (u8 *)&ax25_defaddr); 459 } 460 461 /* 462 * Setup a new device. 463 */ 464 static int bpq_new_device(struct net_device *edev) 465 { 466 int err; 467 struct net_device *ndev; 468 struct bpqdev *bpq; 469 470 ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN, 471 bpq_setup); 472 if (!ndev) 473 return -ENOMEM; 474 475 476 bpq = netdev_priv(ndev); 477 dev_hold(edev); 478 bpq->ethdev = edev; 479 bpq->axdev = ndev; 480 481 eth_broadcast_addr(bpq->dest_addr); 482 eth_broadcast_addr(bpq->acpt_addr); 483 484 err = register_netdevice(ndev); 485 if (err) 486 goto error; 487 488 /* List protected by RTNL */ 489 list_add_rcu(&bpq->bpq_list, &bpq_devices); 490 return 0; 491 492 error: 493 dev_put(edev); 494 free_netdev(ndev); 495 return err; 496 497 } 498 499 static void bpq_free_device(struct net_device *ndev) 500 { 501 struct bpqdev *bpq = netdev_priv(ndev); 502 503 dev_put(bpq->ethdev); 504 list_del_rcu(&bpq->bpq_list); 505 506 unregister_netdevice(ndev); 507 } 508 509 /* 510 * Handle device status changes. 511 */ 512 static int bpq_device_event(struct notifier_block *this, 513 unsigned long event, void *ptr) 514 { 515 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 516 517 if (!net_eq(dev_net(dev), &init_net)) 518 return NOTIFY_DONE; 519 520 if (!dev_is_ethdev(dev) && !bpq_get_ax25_dev(dev)) 521 return NOTIFY_DONE; 522 523 switch (event) { 524 case NETDEV_UP: /* new ethernet device -> new BPQ interface */ 525 if (bpq_get_ax25_dev(dev) == NULL) 526 bpq_new_device(dev); 527 break; 528 529 case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */ 530 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 531 dev_close(dev); 532 break; 533 534 case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */ 535 if ((dev = bpq_get_ax25_dev(dev)) != NULL) 536 bpq_free_device(dev); 537 break; 538 default: 539 break; 540 } 541 542 return NOTIFY_DONE; 543 } 544 545 546 /* ------------------------------------------------------------------------ */ 547 548 /* 549 * Initialize driver. To be called from af_ax25 if not compiled as a 550 * module 551 */ 552 static int __init bpq_init_driver(void) 553 { 554 #ifdef CONFIG_PROC_FS 555 if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) { 556 printk(KERN_ERR 557 "bpq: cannot create /proc/net/bpqether entry.\n"); 558 return -ENOENT; 559 } 560 #endif /* CONFIG_PROC_FS */ 561 562 dev_add_pack(&bpq_packet_type); 563 564 register_netdevice_notifier(&bpq_dev_notifier); 565 566 printk(banner); 567 568 return 0; 569 } 570 571 static void __exit bpq_cleanup_driver(void) 572 { 573 struct bpqdev *bpq; 574 575 dev_remove_pack(&bpq_packet_type); 576 577 unregister_netdevice_notifier(&bpq_dev_notifier); 578 579 remove_proc_entry("bpqether", init_net.proc_net); 580 581 rtnl_lock(); 582 while (!list_empty(&bpq_devices)) { 583 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list); 584 bpq_free_device(bpq->axdev); 585 } 586 rtnl_unlock(); 587 } 588 589 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>"); 590 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet"); 591 MODULE_LICENSE("GPL"); 592 module_init(bpq_init_driver); 593 module_exit(bpq_cleanup_driver); 594