TAP AX.25

dmesg.txt

[ 2525.145364] IPv6: ADDRCONF(NETDEV_CHANGE): em1: link becomes ready
[ 2589.973799] skbuff: skb_under_panic: text:ffffffffa0a36810 len:20 put:15 head:ffff880223282a00 data:ffff8802232829fe tail:0x12 end:0xc0 dev:<NULL>
[ 2589.973854] ------------[ cut here ]------------
[ 2589.976829] kernel BUG at /build/linux-RYwSFv/linux-3.16.7-ckt20/net/core/skbuff.c:100!
[ 2589.980700] invalid opcode: 0000 [#3] SMP 
[ 2589.984244] Modules linked in: ax25 tun ctr ccm bnep rtsx_usb_ms memstick rtsx_usb_sdmmc rtsx_usb openafs(PO) nfsd auth_rpcgss oid_registry nfs_acl nfs lockd fscache sunrpc snd_hda_codec_hdmi snd_hda_codec_conexant snd_hda_codec_generic uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core v4l2_common videodev media ecb arc4 brcmsmac cordic brcmutil btusb bluetooth b43 6lowpan_iphc mac80211 cfg80211 ssb x86_pkg_temp_thermal intel_powerclamp mmc_core rng_core intel_rapl pcmcia coretemp pcmcia_core iTCO_wdt iTCO_vendor_support kvm_intel kvm crc32_pclmul joydev cryptd psmouse evdev i2c_i801 serio_raw pcspkr snd_hda_intel i915 snd_hda_controller snd_hda_codec snd_hwdep bcma snd_pcm snd_timer snd soundcore lpc_ich mfd_core shpchp drm_kms_helper drm i2c_algo_bit ideapad_laptop sparse_keymap i2c_core
[ 2589.998557]  rfkill battery ac mei_me video mei button processor fuse parport_pc ppdev lp parport autofs4 ext4 crc16 mbcache jbd2 hid_generic usbhid hid sg sd_mod crc_t10dif sr_mod cdrom crct10dif_generic ahci libahci crct10dif_pclmul crct10dif_common crc32c_intel libata scsi_mod thermal thermal_sys ehci_pci xhci_hcd ehci_hcd alx mdio usbcore usb_common
[ 2590.004952] CPU: 1 PID: 2811 Comm: beacon Tainted: P      D    O  3.16.0-4-amd64 #1 Debian 3.16.7-ckt20-1+deb8u3
[ 2590.006998] Hardware name: LENOVO 20150/INVALID, BIOS 5ECN95WW(V9.00) 12/19/2012
[ 2590.010248] task: ffff8801f6bd8250 ti: ffff8801d7c3c000 task.ti: ffff8801d7c3c000
[ 2590.014238] RIP: 0010:[<ffffffff8150f184>]  [<ffffffff8150f184>] skb_panic+0x5f/0x61
[ 2590.016624] RSP: 0018:ffff8801d7c3fc98  EFLAGS: 00010282
[ 2590.019352] RAX: 0000000000000086 RBX: ffff88022545e400 RCX: 0000000000000000
[ 2590.021485] RDX: ffff88022f24eda0 RSI: ffff88022f24d478 RDI: 0000000000000246
[ 2590.025157] RBP: 0000000000000000 R08: 000000000000000a R09: 0000000000000000
[ 2590.028843] R10: 000000000000038c R11: ffff8801d7c3f9d6 R12: 0000000000000012
[ 2590.032482] R13: 0000000000000004 R14: ffff8801d7d5dc00 R15: ffff8800b919f000
[ 2590.034357] FS:  00007fd7360b4700(0000) GS:ffff88022f240000(0000) knlGS:0000000000000000
[ 2590.037990] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2590.041671] CR2: 00007fd735a73c60 CR3: 00000001cea42000 CR4: 00000000000407e0
[ 2590.045382] Stack:
[ 2590.049070]  ffff8802232829fe 0000000000000012 00000000000000c0 ffffffff8173760c
[ 2590.052813]  ffffffff8140d946 ffffffffa0a36810 0000000000000000 88920003cb817400
[ 2590.056578]  360de10040a89c8a ffff880100000000 ffffffff8113da58 ffff880225ea3220
[ 2590.060288] Call Trace:
[ 2590.064071]  [<ffffffff8140d946>] ? skb_push+0x36/0x40
[ 2590.067791]  [<ffffffffa0a36810>] ? ax25_sendmsg+0x310/0x3f0 [ax25]
[ 2590.071497]  [<ffffffff8113da58>] ? filemap_map_pages+0x1d8/0x230
[ 2590.075188]  [<ffffffff814060fb>] ? sock_sendmsg+0x8b/0xc0
[ 2590.078860]  [<ffffffff8116987c>] ? handle_mm_fault+0x63c/0x11c0
[ 2590.082470]  [<ffffffff8116509c>] ? tlb_flush_mmu_free+0x2c/0x50
[ 2590.086124]  [<ffffffff81190144>] ? __kmalloc+0x4b4/0x4c0
[ 2590.089726]  [<ffffffff81406261>] ? SYSC_sendto+0xf1/0x180
[ 2590.093250]  [<ffffffff811c451a>] ? __fd_install+0x1a/0x50
[ 2590.093275]  [<ffffffff81513d0d>] ? system_call_fast_compare_end+0x10/0x15
[ 2590.093334] Code: 00 00 48 89 44 24 10 8b 87 c8 00 00 00 48 89 44 24 08 48 8b 87 d8 00 00 00 48 c7 c7 38 6f 77 81 48 89 04 24 31 c0 e8 a4 be ff ff <0f> 0b 48 8b 47 30 48 8b 17 80 e6 80 48 0f 44 c7 c3 0f 0b 0f 0b 
[ 2590.093340] RIP  [<ffffffff8150f184>] skb_panic+0x5f/0x61
[ 2590.093341]  RSP <ffff8801d7c3fc98>
[ 2590.093391] ---[ end trace d031dce997a41d8a ]---

tapax25test.c

/*
 * GNU GPLv2+
 *
 * Alejandro Santos 2015
 * @alejolp
 *
 * gcc -Wall -lax25 tapax25test.c
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <fcntl.h>
#include <unistd.h>

#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>

#include <netax25/ax25.h>
#include <netax25/axlib.h>
#include <netax25/axconfig.h>

#include <netdb.h>

/* #include <net/if.h> */
#include <net/if_arp.h>

#include <linux/if.h>
#include <linux/if_tun.h>




int tun_alloc(char *dev)
{
    struct ifreq ifr;
    int fd, err;

    if( (fd = open("/dev/net/tun", O_RDWR)) < 0 )
       return -1;

    memset(&ifr, 0, sizeof(ifr));
    
    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;

    if( *dev )
       strncpy(ifr.ifr_name, dev, IFNAMSIZ);

    if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
       close(fd);
       return err;
    }

    strcpy(dev, ifr.ifr_name);

    if (ioctl(fd, TUNSETLINK, ARPHRD_AX25) == -1) {
        perror("ioctl");
        close(fd);
        return -1;
    }

    if (ioctl(fd, TUNSETPERSIST, 0) == -1) {
        perror("ioctl");
        close(fd);
        return -1;
    }


    return fd;
}

int setifcall(int s, char *ifn, char *name)
{
      char call[7];
      struct ifreq ifr;
      
      if (ax25_aton_entry(name, call) == -1)
            return 1;

      memset(&ifr, 0, sizeof(ifr));
      strcpy(ifr.ifr_name, ifn);
      memcpy(ifr.ifr_hwaddr.sa_data, call, 7);

      ifr.ifr_hwaddr.sa_family = AF_AX25;

      if (ioctl(s, SIOCSIFHWADDR, &ifr) != 0) {
            perror("ioctl: SIOCSIFHWADDR");
            return 1;
      }

      return 0;
}

int setifmtu(int s, char *ifn, int mtu)
{
      struct ifreq ifr;
      
      memset(&ifr, 0, sizeof(ifr));

      strcpy(ifr.ifr_name, ifn);
      ifr.ifr_mtu = mtu; 

      if (ioctl(s, SIOCSIFMTU, &ifr) != 0) {
            perror("ioctl: SIOCSIFMTU");
            return 1;
      }

      return 0;
}

int startiface(int fd, const char* dev, int mtu, struct hostent * hp) 
{
  struct ifreq ifr;

  memset(&ifr, 0, sizeof(ifr));
  strcpy(ifr.ifr_name, dev);

  if (hp != NULL) {
        ifr.ifr_addr.sa_family = AF_INET;
        
        ifr.ifr_addr.sa_data[0] = 0;
        ifr.ifr_addr.sa_data[1] = 0;
        ifr.ifr_addr.sa_data[2] = hp->h_addr_list[0][0];
        ifr.ifr_addr.sa_data[3] = hp->h_addr_list[0][1];
        ifr.ifr_addr.sa_data[4] = hp->h_addr_list[0][2];
        ifr.ifr_addr.sa_data[5] = hp->h_addr_list[0][3];
        ifr.ifr_addr.sa_data[6] = 0;

        if (ioctl(fd, SIOCSIFADDR, &ifr) < 0) {
               perror("SIOCSIFADDR");
               return FALSE;
        }
  }

  ifr.ifr_mtu = mtu;

  if (ioctl(fd, SIOCSIFMTU, &ifr) < 0) {
        perror("SIOCSIFMTU");
        return FALSE;
  }

  if (ioctl(fd, SIOCGIFFLAGS, &ifr) < 0) {
        perror("SIOCGIFFLAGS");
        return FALSE;
  }

  ifr.ifr_flags &= IFF_NOARP;
  ifr.ifr_flags |= IFF_UP;
  ifr.ifr_flags |= IFF_RUNNING;

  if (ioctl(fd, SIOCSIFFLAGS, &ifr) < 0) {
        perror("SIOCSIFFLAGS");
        return FALSE;
  }

  return TRUE;
}

int main(int argc, char** argv) {
    char dev_name[1024] = "em0";
    char call_name[1024] = "LU4EXT-15";
    int tap_fd;
    int i;
    int s, n;
    int mtu = 256;

    if (argc > 1) strncpy(dev_name, argv[1], 1024);
    if (argc > 2) strncpy(call_name, argv[2], 1024);

    printf("Creating TAP AX25 device name %s, call name %s\n", dev_name, call_name);

    tap_fd = tun_alloc(dev_name);

    printf("dev %d name %s\n", tap_fd, dev_name);

    if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
          perror("axparms: socket");
          return 1;
    }

    n = setifcall(s, dev_name, call_name);
    //n = n | setifmtu(s, dev_name, 256);

    startiface(s, dev_name, mtu, 0);

    close(s);

    for (;;) {
      int nread;
      char buffer[2048];

      nread = read(tap_fd,buffer,sizeof(buffer));

      if(nread < 0) {
        perror("Reading from interface");
        close(tap_fd);
        exit(1);
      }

      printf("Read %d bytes from device %s\n", nread, dev_name);

      for (i=0; i<nread; ++i) {
        printf("%02x ", buffer[i]);
      }
      printf("\n");
    }

    return 0;
}