linux/drivers/net/hamradio/bpqether.c
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   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 <asm/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
  89static const char banner[] __initconst = KERN_INFO \
  90        "AX.25: bpqether driver version 004\n";
  91
  92static char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
  93
  94static char bpq_eth_addr[6];
  95
  96static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);
  97static int bpq_device_event(struct notifier_block *, unsigned long, void *);
  98
  99static struct packet_type bpq_packet_type __read_mostly = {
 100        .type   = cpu_to_be16(ETH_P_BPQ),
 101        .func   = bpq_rcv,
 102};
 103
 104static struct notifier_block bpq_dev_notifier = {
 105        .notifier_call = bpq_device_event,
 106};
 107
 108
 109struct 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
 117static 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 */
 124static struct lock_class_key bpq_netdev_xmit_lock_key;
 125static struct lock_class_key bpq_netdev_addr_lock_key;
 126
 127static 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
 134static 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 */
 146static 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 */
 156static 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
 167static 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 */
 178static 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);
 229unlock:
 230
 231        rcu_read_unlock();
 232
 233        return 0;
 234drop_unlock:
 235        kfree_skb(skb);
 236        goto unlock;
 237
 238drop:
 239        kfree_skb(skb);
 240        return 0;
 241}
 242
 243/*
 244 *      Send an AX.25 frame via an ethernet interface
 245 */
 246static 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 */
 309static 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 */
 325static 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 */
 364static int bpq_open(struct net_device *dev)
 365{
 366        netif_start_queue(dev);
 367        return 0;
 368}
 369
 370static 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 */
 383static 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
 401static 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
 417static void bpq_seq_stop(struct seq_file *seq, void *v)
 418        __releases(RCU)
 419{
 420        rcu_read_unlock();
 421}
 422
 423
 424static 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
 445static 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
 452static int bpq_info_open(struct inode *inode, struct file *file)
 453{
 454        return seq_open(file, &bpq_seqops);
 455}
 456
 457static 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
 468static 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
 476static 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 */
 501static 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
 537static 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 */
 550static 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 */
 590static 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
 610static 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
 628MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>");
 629MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet");
 630MODULE_LICENSE("GPL");
 631module_init(bpq_init_driver);
 632module_exit(bpq_cleanup_driver);
 633