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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * G8BPQ compatible "AX.25 via ethernet" driver release 0044 *5 * This code REQUIRES 2.0.0 or higher/ NET3.0296 *7 * This is a "pseudo" network driver to allow AX.25 over Ethernet8 * using G8BPQ encapsulation. It has been extracted from the protocol9 * implementation because10 *11 * - things got unreadable within the protocol stack12 * - to cure the protocol stack from "feature-ism"13 * - a protocol implementation shouldn't need to know on14 * which hardware it is running15 * - user-level programs like the AX.25 utilities shouldn't16 * need to know about the hardware.17 * - IP over ethernet encapsulated AX.25 was impossible18 * - rxecho.c did not work19 * - to have room for extensions20 * - it just deserves to "live" as an own driver21 *22 * This driver can use any ethernet destination address, and can be23 * limited to accept frames from one dedicated ethernet card only.24 *25 * Note that the driver sets up the BPQ devices automagically on26 * startup or (if started before the "insmod" of an ethernet device)27 * on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing28 * the ethernet device (in fact: as soon as another ethernet or bpq29 * device gets "ifconfig"ured).30 *31 * I have heard that several people are thinking of experiments32 * with highspeed packet radio using existing ethernet cards.33 * Well, this driver is prepared for this purpose, just add34 * your tx key control and a txdelay / tailtime algorithm,35 * probably some buffering, and /voila/...36 *37 * History38 * BPQ 001 Joerg(DL1BKE) Extracted BPQ code from AX.2539 * protocol stack and added my own40 * yet existing patches41 * BPQ 002 Joerg(DL1BKE) Scan network device list on42 * startup.43 * BPQ 003 Joerg(DL1BKE) Ethernet destination address44 * and accepted source address45 * can be configured by an ioctl()46 * call.47 * Fixed to match Linux networking48 * 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 84static const char banner[] __initconst = KERN_INFO \85 "AX.25: bpqether driver version 004\n";86 87static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);88static int bpq_device_event(struct notifier_block *, unsigned long, void *);89 90static struct packet_type bpq_packet_type __read_mostly = {91 .type = cpu_to_be16(ETH_P_BPQ),92 .func = bpq_rcv,93};94 95static struct notifier_block bpq_dev_notifier = {96 .notifier_call = bpq_device_event,97};98 99 100struct 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 108static LIST_HEAD(bpq_devices);109 110/*111 * bpqether network devices are paired with ethernet devices below them, so112 * form a special "super class" of normal ethernet devices; split their locks113 * off into a separate class since they always nest.114 */115static struct lock_class_key bpq_netdev_xmit_lock_key;116static struct lock_class_key bpq_netdev_addr_lock_key;117 118static 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 125static 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 device136 */137static 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 device146 */147static 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 159static 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 */170static 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 device194 * 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);221unlock:222 223 rcu_read_unlock();224 225 return 0;226drop_unlock:227 kfree_skb(skb);228 goto unlock;229 230drop:231 kfree_skb(skb);232 return 0;233}234 235/*236 * Send an AX.25 frame via an ethernet interface237 */238static 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 interface250 * 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 the262 * generic networking code so unshare and ensure it's got enough263 * 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 callsign300 */301static int bpq_set_mac_address(struct net_device *dev, void *addr)302{303 struct sockaddr *sa = (struct sockaddr *)addr;304 305 dev_addr_set(dev, sa->sa_data);306 307 return 0;308}309 310/* Ioctl commands311 *312 * SIOCSBPQETHOPT reserved for enhancements313 * SIOCSBPQETHADDR set the destination and accepted314 * source ethernet address (broadcast315 * or multicast: accept all)316 */317static 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 device356 */357static int bpq_open(struct net_device *dev)358{359 netif_start_queue(dev);360 return 0;361}362 363static 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_FS373/*374 * Proc filesystem375 */376static 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 394static 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 else404 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 410static void bpq_seq_stop(struct seq_file *seq, void *v)411 __releases(RCU)412{413 rcu_read_unlock();414}415 416 417static 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 else432 seq_printf(seq, "%pM\n", bpqdev->acpt_addr);433 434 }435 return 0;436}437 438static 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#endif445/* ------------------------------------------------------------------------ */446 447static 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 455static void bpq_setup(struct net_device *dev)456{457 dev->netdev_ops = &bpq_netdev_ops;458 dev->needs_free_netdev = true;459 460 dev->flags = 0;461 dev->lltx = true; /* Allow recursion */462 463#if IS_ENABLED(CONFIG_AX25)464 dev->header_ops = &ax25_header_ops;465#endif466 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 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);473 dev_addr_set(dev, (u8 *)&ax25_defaddr);474}475 476/*477 * Setup a new device.478 */479static int bpq_new_device(struct net_device *edev)480{481 int err;482 struct net_device *ndev;483 struct bpqdev *bpq;484 485 ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN,486 bpq_setup);487 if (!ndev)488 return -ENOMEM;489 490 491 bpq = netdev_priv(ndev);492 dev_hold(edev);493 bpq->ethdev = edev;494 bpq->axdev = ndev;495 496 eth_broadcast_addr(bpq->dest_addr);497 eth_broadcast_addr(bpq->acpt_addr);498 499 err = register_netdevice(ndev);500 if (err)501 goto error;502 bpq_set_lockdep_class(ndev);503 504 /* List protected by RTNL */505 list_add_rcu(&bpq->bpq_list, &bpq_devices);506 return 0;507 508 error:509 dev_put(edev);510 free_netdev(ndev);511 return err;512 513}514 515static void bpq_free_device(struct net_device *ndev)516{517 struct bpqdev *bpq = netdev_priv(ndev);518 519 dev_put(bpq->ethdev);520 list_del_rcu(&bpq->bpq_list);521 522 unregister_netdevice(ndev);523}524 525/*526 * Handle device status changes.527 */528static int bpq_device_event(struct notifier_block *this,529 unsigned long event, void *ptr)530{531 struct net_device *dev = netdev_notifier_info_to_dev(ptr);532 533 if (!net_eq(dev_net(dev), &init_net))534 return NOTIFY_DONE;535 536 if (!dev_is_ethdev(dev) && !bpq_get_ax25_dev(dev))537 return NOTIFY_DONE;538 539 switch (event) {540 case NETDEV_UP: /* new ethernet device -> new BPQ interface */541 if (bpq_get_ax25_dev(dev) == NULL)542 bpq_new_device(dev);543 break;544 545 case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */546 if ((dev = bpq_get_ax25_dev(dev)) != NULL)547 dev_close(dev);548 break;549 550 case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */551 if ((dev = bpq_get_ax25_dev(dev)) != NULL)552 bpq_free_device(dev);553 break;554 default:555 break;556 }557 558 return NOTIFY_DONE;559}560 561 562/* ------------------------------------------------------------------------ */563 564/*565 * Initialize driver. To be called from af_ax25 if not compiled as a566 * module567 */568static int __init bpq_init_driver(void)569{570#ifdef CONFIG_PROC_FS571 if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) {572 printk(KERN_ERR573 "bpq: cannot create /proc/net/bpqether entry.\n");574 return -ENOENT;575 }576#endif /* CONFIG_PROC_FS */577 578 dev_add_pack(&bpq_packet_type);579 580 register_netdevice_notifier(&bpq_dev_notifier);581 582 printk(banner);583 584 return 0;585}586 587static void __exit bpq_cleanup_driver(void)588{589 struct bpqdev *bpq;590 591 dev_remove_pack(&bpq_packet_type);592 593 unregister_netdevice_notifier(&bpq_dev_notifier);594 595 remove_proc_entry("bpqether", init_net.proc_net);596 597 rtnl_lock();598 while (!list_empty(&bpq_devices)) {599 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list);600 bpq_free_device(bpq->axdev);601 }602 rtnl_unlock();603}604 605MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>");606MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet");607MODULE_LICENSE("GPL");608module_init(bpq_init_driver);609module_exit(bpq_cleanup_driver);610