drivers/net/hamradio/bpqether.c

   1 /*
   2  *      G8BPQ compatible "AX.25 via ethernet" driver release 004
   3  *
   4  *      This code REQUIRES 2.0.0 or higher/ NET3.029
   5  *
   6  *      This module:
   7  *              This module is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  *      This is a "pseudo" network driver to allow AX.25 over Ethernet
  13  *      using G8BPQ encapsulation. It has been extracted from the protocol
  14  *      implementation because
  15  *
  16  *              - things got unreadable within the protocol stack
  17  *              - to cure the protocol stack from "feature-ism"
  18  *              - a protocol implementation shouldn't need to know on
  19  *                which hardware it is running
  20  *              - user-level programs like the AX.25 utilities shouldn't
  21  *                need to know about the hardware.
  22  *              - IP over ethernet encapsulated AX.25 was impossible
  23  *              - rxecho.c did not work
  24  *              - to have room for extensions
  25  *              - it just deserves to "live" as an own driver
  26  *
  27  *      This driver can use any ethernet destination address, and can be
  28  *      limited to accept frames from one dedicated ethernet card only.
  29  *
  30  *      Note that the driver sets up the BPQ devices automagically on
  31  *      startup or (if started before the "insmod" of an ethernet device)
  32  *      on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing
  33  *      the ethernet device (in fact: as soon as another ethernet or bpq
  34  *      device gets "ifconfig"ured).
  35  *
  36  *      I have heard that several people are thinking of experiments
  37  *      with highspeed packet radio using existing ethernet cards.
  38  *      Well, this driver is prepared for this purpose, just add
  39  *      your tx key control and a txdelay / tailtime algorithm,
  40  *      probably some buffering, and /voila/...
  41  *
  42  *      History
  43  *      BPQ   001       Joerg(DL1BKE)           Extracted BPQ code from AX.25
  44  *                                              protocol stack and added my own
  45  *                                              yet existing patches
  46  *      BPQ   002       Joerg(DL1BKE)           Scan network device list on
  47  *                                              startup.
  48  *      BPQ   003       Joerg(DL1BKE)           Ethernet destination address
  49  *                                              and accepted source address
  50  *                                              can be configured by an ioctl()
  51  *                                              call.
  52  *                                              Fixed to match Linux networking
  53  *                                              changes - 2.1.15.
  54  *      BPQ   004       Joerg(DL1BKE)           Fixed to not lock up on ifconfig.
  55  */
  56
  57 #include <linux/errno.h>
  58 #include <linux/types.h>
  59 #include <linux/socket.h>
  60 #include <linux/in.h>
  61 #include <linux/kernel.h>
  62 #include <linux/string.h>
  63 #include <linux/net.h>
  64 #include <linux/slab.h>
  65 #include <net/ax25.h>
  66 #include <linux/inet.h>
  67 #include <linux/netdevice.h>
  68 #include <linux/etherdevice.h>
  69 #include <linux/if_arp.h>
  70 #include <linux/skbuff.h>
  71 #include <net/sock.h>
  72 #include <linux/uaccess.h>
  73 #include <linux/mm.h>
  74 #include <linux/interrupt.h>
  75 #include <linux/notifier.h>
  76 #include <linux/proc_fs.h>
  77 #include <linux/seq_file.h>
  78 #include <linux/stat.h>
  79 #include <linux/module.h>
  80 #include <linux/init.h>
  81 #include <linux/rtnetlink.h>
  82
  83 #include <net/ip.h>
  84 #include <net/arp.h>
  85 #include <net/net_namespace.h>
  86
  87 #include <linux/bpqether.h>
  88
  89 static const char banner[] __initconst = KERN_INFO \
  90         "AX.25: bpqether driver version 004\n";
  91
  92 static char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
  93
  94 static char bpq_eth_addr[6];
  95
  96 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);
  97 static int bpq_device_event(struct notifier_block *, unsigned long, void *);
  98
  99 static struct packet_type bpq_packet_type __read_mostly = {
 100         .type   = cpu_to_be16(ETH_P_BPQ),
 101         .func   = bpq_rcv,
 102 };
 103
 104 static struct notifier_block bpq_dev_notifier = {
 105         .notifier_call = bpq_device_event,
 106 };
 107
 108
 109 struct bpqdev {
 110         struct list_head bpq_list;      /* list of bpq devices chain */
 111         struct net_device *ethdev;      /* link to ethernet device */
 112         struct net_device *axdev;       /* bpq device (bpq#) */
 113         char   dest_addr[6];            /* ether destination address */
 114         char   acpt_addr[6];            /* accept ether frames from this address only */
 115 };
 116
 117 static LIST_HEAD(bpq_devices);
 118
 119 /*
 120  * bpqether network devices are paired with ethernet devices below them, so
 121  * form a special "super class" of normal ethernet devices; split their locks
 122  * off into a separate class since they always nest.
 123  */
 124 static struct lock_class_key bpq_netdev_xmit_lock_key;
 125 static struct lock_class_key bpq_netdev_addr_lock_key;
 126
 127 static void bpq_set_lockdep_class_one(struct net_device *dev,
 128                                       struct netdev_queue *txq,
 129                                       void *_unused)
 130 {
 131         lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key);
 132 }
 133
 134 static void bpq_set_lockdep_class(struct net_device *dev)
 135 {
 136         lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key);
 137         netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL);
 138 }
 139
 140 /* ------------------------------------------------------------------------ */
 141
 142
 143 /*
 144  *      Get the ethernet device for a BPQ device
 145  */
 146 static inline struct net_device *bpq_get_ether_dev(struct net_device *dev)
 147 {
 148         struct bpqdev *bpq = netdev_priv(dev);
 149
 150         return bpq ? bpq->ethdev : NULL;
 151 }
 152
 153 /*
 154  *      Get the BPQ device for the ethernet device
 155  */
 156 static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev)
 157 {
 158         struct bpqdev *bpq;
 159
 160         list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) {
 161                 if (bpq->ethdev == dev)
 162                         return bpq->axdev;
 163         }
 164         return NULL;
 165 }
 166
 167 static inline int dev_is_ethdev(struct net_device *dev)
 168 {
 169         return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
 170 }
 171
 172 /* ------------------------------------------------------------------------ */
 173
 174
 175 /*
 176  *      Receive an AX.25 frame via an ethernet interface.
 177  */
 178 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
 179 {
 180         int len;
 181         char * ptr;
 182         struct ethhdr *eth;
 183         struct bpqdev *bpq;
 184
 185         if (!net_eq(dev_net(dev), &init_net))
 186                 goto drop;
 187
 188         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
 189                 return NET_RX_DROP;
 190
 191         if (!pskb_may_pull(skb, sizeof(struct ethhdr)))
 192                 goto drop;
 193
 194         rcu_read_lock();
 195         dev = bpq_get_ax25_dev(dev);
 196
 197         if (dev == NULL || !netif_running(dev))
 198                 goto drop_unlock;
 199
 200         /*
 201          * if we want to accept frames from just one ethernet device
 202          * we check the source address of the sender.
 203          */
 204
 205         bpq = netdev_priv(dev);
 206
 207         eth = eth_hdr(skb);
 208
 209         if (!(bpq->acpt_addr[0] & 0x01) &&
 210             !ether_addr_equal(eth->h_source, bpq->acpt_addr))
 211                 goto drop_unlock;
 212
 213         if (skb_cow(skb, sizeof(struct ethhdr)))
 214                 goto drop_unlock;
 215
 216         len = skb->data[0] + skb->data[1] * 256 - 5;
 217
 218         skb_pull(skb, 2);       /* Remove the length bytes */
 219         skb_trim(skb, len);     /* Set the length of the data */
 220
 221         dev->stats.rx_packets++;
 222         dev->stats.rx_bytes += len;
 223
 224         ptr = skb_push(skb, 1);
 225         *ptr = 0;
 226
 227         skb->protocol = ax25_type_trans(skb, dev);
 228         netif_rx(skb);
 229 unlock:
 230
 231         rcu_read_unlock();
 232
 233         return 0;
 234 drop_unlock:
 235         kfree_skb(skb);
 236         goto unlock;
 237
 238 drop:
 239         kfree_skb(skb);
 240         return 0;
 241 }
 242
 243 /*
 244  *      Send an AX.25 frame via an ethernet interface
 245  */
 246 static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev)
 247 {
 248         unsigned char *ptr;
 249         struct bpqdev *bpq;
 250         struct net_device *orig_dev;
 251         int size;
 252
 253         if (skb->protocol == htons(ETH_P_IP))
 254                 return ax25_ip_xmit(skb);
 255
 256         /*
 257          * Just to be *really* sure not to send anything if the interface
 258          * is down, the ethernet device may have gone.
 259          */
 260         if (!netif_running(dev)) {
 261                 kfree_skb(skb);
 262                 return NETDEV_TX_OK;
 263         }
 264
 265         skb_pull(skb, 1);                       /* Drop KISS byte */
 266         size = skb->len;
 267
 268         /*
 269          * We're about to mess with the skb which may still shared with the
 270          * generic networking code so unshare and ensure it's got enough
 271          * space for the BPQ headers.
 272          */
 273         if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) {
 274                 if (net_ratelimit())
 275                         pr_err("bpqether: out of memory\n");
 276                 kfree_skb(skb);
 277
 278                 return NETDEV_TX_OK;
 279         }
 280
 281         ptr = skb_push(skb, 2);                 /* Make space for length */
 282
 283         *ptr++ = (size + 5) % 256;
 284         *ptr++ = (size + 5) / 256;
 285
 286         bpq = netdev_priv(dev);
 287
 288         orig_dev = dev;
 289         if ((dev = bpq_get_ether_dev(dev)) == NULL) {
 290                 orig_dev->stats.tx_dropped++;
 291                 kfree_skb(skb);
 292                 return NETDEV_TX_OK;
 293         }
 294
 295         skb->protocol = ax25_type_trans(skb, dev);
 296         skb_reset_network_header(skb);
 297         dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0);
 298         dev->stats.tx_packets++;
 299         dev->stats.tx_bytes+=skb->len;
 300
 301         dev_queue_xmit(skb);
 302         netif_wake_queue(dev);
 303         return NETDEV_TX_OK;
 304 }
 305
 306 /*
 307  *      Set AX.25 callsign
 308  */
 309 static int bpq_set_mac_address(struct net_device *dev, void *addr)
 310 {
 311     struct sockaddr *sa = (struct sockaddr *)addr;
 312
 313     memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 314
 315     return 0;
 316 }
 317
 318 /*      Ioctl commands
 319  *
 320  *              SIOCSBPQETHOPT          reserved for enhancements
 321  *              SIOCSBPQETHADDR         set the destination and accepted
 322  *                                      source ethernet address (broadcast
 323  *                                      or multicast: accept all)
 324  */
 325 static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 326 {
 327         struct bpq_ethaddr __user *ethaddr = ifr->ifr_data;
 328         struct bpqdev *bpq = netdev_priv(dev);
 329         struct bpq_req req;
 330
 331         if (!capable(CAP_NET_ADMIN))
 332                 return -EPERM;
 333
 334         switch (cmd) {
 335                 case SIOCSBPQETHOPT:
 336                         if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req)))
 337                                 return -EFAULT;
 338                         switch (req.cmd) {
 339                                 case SIOCGBPQETHPARAM:
 340                                 case SIOCSBPQETHPARAM:
 341                                 default:
 342                                         return -EINVAL;
 343                         }
 344
 345                         break;
 346
 347                 case SIOCSBPQETHADDR:
 348                         if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN))
 349                                 return -EFAULT;
 350                         if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN))
 351                                 return -EFAULT;
 352                         break;
 353
 354                 default:
 355                         return -EINVAL;
 356         }
 357
 358         return 0;
 359 }
 360
 361 /*
 362  * open/close a device
 363  */
 364 static int bpq_open(struct net_device *dev)
 365 {
 366         netif_start_queue(dev);
 367         return 0;
 368 }
 369
 370 static int bpq_close(struct net_device *dev)
 371 {
 372         netif_stop_queue(dev);
 373         return 0;
 374 }
 375
 376
 377 /* ------------------------------------------------------------------------ */
 378
 379
 380 /*
 381  *      Proc filesystem
 382  */
 383 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos)
 384         __acquires(RCU)
 385 {
 386         int i = 1;
 387         struct bpqdev *bpqdev;
 388
 389         rcu_read_lock();
 390
 391         if (*pos == 0)
 392                 return SEQ_START_TOKEN;
 393
 394         list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) {
 395                 if (i == *pos)
 396                         return bpqdev;
 397         }
 398         return NULL;
 399 }
 400
 401 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 402 {
 403         struct list_head *p;
 404         struct bpqdev *bpqdev = v;
 405
 406         ++*pos;
 407
 408         if (v == SEQ_START_TOKEN)
 409                 p = rcu_dereference(list_next_rcu(&bpq_devices));
 410         else
 411                 p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list));
 412
 413         return (p == &bpq_devices) ? NULL
 414                 : list_entry(p, struct bpqdev, bpq_list);
 415 }
 416
 417 static void bpq_seq_stop(struct seq_file *seq, void *v)
 418         __releases(RCU)
 419 {
 420         rcu_read_unlock();
 421 }
 422
 423
 424 static int bpq_seq_show(struct seq_file *seq, void *v)
 425 {
 426         if (v == SEQ_START_TOKEN)
 427                 seq_puts(seq,
 428                          "dev   ether      destination        accept from\n");
 429         else {
 430                 const struct bpqdev *bpqdev = v;
 431
 432                 seq_printf(seq, "%-5s %-10s %pM  ",
 433                         bpqdev->axdev->name, bpqdev->ethdev->name,
 434                         bpqdev->dest_addr);
 435
 436                 if (is_multicast_ether_addr(bpqdev->acpt_addr))
 437                         seq_printf(seq, "*\n");
 438                 else
 439                         seq_printf(seq, "%pM\n", bpqdev->acpt_addr);
 440
 441         }
 442         return 0;
 443 }
 444
 445 static const struct seq_operations bpq_seqops = {
 446         .start = bpq_seq_start,
 447         .next = bpq_seq_next,
 448         .stop = bpq_seq_stop,
 449         .show = bpq_seq_show,
 450 };
 451
 452 static int bpq_info_open(struct inode *inode, struct file *file)
 453 {
 454         return seq_open(file, &bpq_seqops);
 455 }
 456
 457 static const struct file_operations bpq_info_fops = {
 458         .owner = THIS_MODULE,
 459         .open = bpq_info_open,
 460         .read = seq_read,
 461         .llseek = seq_lseek,
 462         .release = seq_release,
 463 };
 464
 465
 466 /* ------------------------------------------------------------------------ */
 467
 468 static const struct net_device_ops bpq_netdev_ops = {
 469         .ndo_open            = bpq_open,
 470         .ndo_stop            = bpq_close,
 471         .ndo_start_xmit      = bpq_xmit,
 472         .ndo_set_mac_address = bpq_set_mac_address,
 473         .ndo_do_ioctl        = bpq_ioctl,
 474 };
 475
 476 static void bpq_setup(struct net_device *dev)
 477 {
 478         dev->netdev_ops      = &bpq_netdev_ops;
 479         dev->destructor      = free_netdev;
 480
 481         memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
 482         memcpy(dev->dev_addr,  &ax25_defaddr, AX25_ADDR_LEN);
 483
 484         dev->flags      = 0;
 485         dev->features   = NETIF_F_LLTX; /* Allow recursion */
 486
 487 #if IS_ENABLED(CONFIG_AX25)
 488         dev->header_ops      = &ax25_header_ops;
 489 #endif
 490
 491         dev->type            = ARPHRD_AX25;
 492         dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;
 493         dev->mtu             = AX25_DEF_PACLEN;
 494         dev->addr_len        = AX25_ADDR_LEN;
 495
 496 }
 497
 498 /*
 499  *      Setup a new device.
 500  */
 501 static int bpq_new_device(struct net_device *edev)
 502 {
 503         int err;
 504         struct net_device *ndev;
 505         struct bpqdev *bpq;
 506
 507         ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN,
 508                             bpq_setup);
 509         if (!ndev)
 510                 return -ENOMEM;
 511
 512
 513         bpq = netdev_priv(ndev);
 514         dev_hold(edev);
 515         bpq->ethdev = edev;
 516         bpq->axdev = ndev;
 517
 518         memcpy(bpq->dest_addr, bcast_addr, sizeof(bpq_eth_addr));
 519         memcpy(bpq->acpt_addr, bcast_addr, sizeof(bpq_eth_addr));
 520
 521         err = register_netdevice(ndev);
 522         if (err)
 523                 goto error;
 524         bpq_set_lockdep_class(ndev);
 525
 526         /* List protected by RTNL */
 527         list_add_rcu(&bpq->bpq_list, &bpq_devices);
 528         return 0;
 529
 530  error:
 531         dev_put(edev);
 532         free_netdev(ndev);
 533         return err;
 534
 535 }
 536
 537 static void bpq_free_device(struct net_device *ndev)
 538 {
 539         struct bpqdev *bpq = netdev_priv(ndev);
 540
 541         dev_put(bpq->ethdev);
 542         list_del_rcu(&bpq->bpq_list);
 543
 544         unregister_netdevice(ndev);
 545 }
 546
 547 /*
 548  *      Handle device status changes.
 549  */
 550 static int bpq_device_event(struct notifier_block *this,
 551                             unsigned long event, void *ptr)
 552 {
 553         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 554
 555         if (!net_eq(dev_net(dev), &init_net))
 556                 return NOTIFY_DONE;
 557
 558         if (!dev_is_ethdev(dev))
 559                 return NOTIFY_DONE;
 560
 561         switch (event) {
 562         case NETDEV_UP:         /* new ethernet device -> new BPQ interface */
 563                 if (bpq_get_ax25_dev(dev) == NULL)
 564                         bpq_new_device(dev);
 565                 break;
 566
 567         case NETDEV_DOWN:       /* ethernet device closed -> close BPQ interface */
 568                 if ((dev = bpq_get_ax25_dev(dev)) != NULL)
 569                         dev_close(dev);
 570                 break;
 571
 572         case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */
 573                 if ((dev = bpq_get_ax25_dev(dev)) != NULL)
 574                         bpq_free_device(dev);
 575                 break;
 576         default:
 577                 break;
 578         }
 579
 580         return NOTIFY_DONE;
 581 }
 582
 583
 584 /* ------------------------------------------------------------------------ */
 585
 586 /*
 587  * Initialize driver. To be called from af_ax25 if not compiled as a
 588  * module
 589  */
 590 static int __init bpq_init_driver(void)
 591 {
 592 #ifdef CONFIG_PROC_FS
 593         if (!proc_create("bpqether", S_IRUGO, init_net.proc_net,
 594                          &bpq_info_fops)) {
 595                 printk(KERN_ERR
 596                         "bpq: cannot create /proc/net/bpqether entry.\n");
 597                 return -ENOENT;
 598         }
 599 #endif  /* CONFIG_PROC_FS */
 600
 601         dev_add_pack(&bpq_packet_type);
 602
 603         register_netdevice_notifier(&bpq_dev_notifier);
 604
 605         printk(banner);
 606
 607         return 0;
 608 }
 609
 610 static void __exit bpq_cleanup_driver(void)
 611 {
 612         struct bpqdev *bpq;
 613
 614         dev_remove_pack(&bpq_packet_type);
 615
 616         unregister_netdevice_notifier(&bpq_dev_notifier);
 617
 618         remove_proc_entry("bpqether", init_net.proc_net);
 619
 620         rtnl_lock();
 621         while (!list_empty(&bpq_devices)) {
 622                 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list);
 623                 bpq_free_device(bpq->axdev);
 624         }
 625         rtnl_unlock();
 626 }
 627
 628 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>");
 629 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet");
 630 MODULE_LICENSE("GPL");
 631 module_init(bpq_init_driver);
 632 module_exit(bpq_cleanup_driver);