drivers/net/hamradio/bpqether.c

   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);