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