common/nit.c

   1 /* nit.c
   2
   3    Network Interface Tap (NIT) network interface code, by Ted Lemon
   4    with one crucial tidbit of help from Stu Grossmen. */
   5
   6 /*
   7  * Copyright (c) 2004-2017 by Internet Systems Consortium, Inc. ("ISC")
   8  * Copyright (c) 1996-2003 by Internet Software Consortium
   9  *
  10  * This Source Code Form is subject to the terms of the Mozilla Public
  11  * License, v. 2.0. If a copy of the MPL was not distributed with this
  12  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  15  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  16  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  17  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  18  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  19  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  20  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  21  *
  22  *   Internet Systems Consortium, Inc.
  23  *   PO Box 360
  24  *   Newmarket, NH 03857 USA
  25  *   <info@isc.org>
  26  *   https://www.isc.org/
  27  *
  28  */
  29
  30 #include "dhcpd.h"
  31 #if defined (USE_NIT_SEND) || defined (USE_NIT_RECEIVE)
  32 #include <sys/ioctl.h>
  33 #include <sys/uio.h>
  34
  35 #include <sys/time.h>
  36 #include <net/nit.h>
  37 #include <net/nit_if.h>
  38 #include <net/nit_pf.h>
  39 #include <net/nit_buf.h>
  40 #include <sys/stropts.h>
  41 #include <net/packetfilt.h>
  42
  43 #include <netinet/in_systm.h>
  44 #include "includes/netinet/ip.h"
  45 #include "includes/netinet/udp.h"
  46 #include "includes/netinet/if_ether.h"
  47
  48 /* Reinitializes the specified interface after an address change.   This
  49    is not required for packet-filter APIs. */
  50
  51 #ifdef USE_NIT_SEND
  52 void if_reinitialize_send (info)
  53         struct interface_info *info;
  54 {
  55 }
  56 #endif
  57
  58 #ifdef USE_NIT_RECEIVE
  59 void if_reinitialize_receive (info)
  60         struct interface_info *info;
  61 {
  62 }
  63 #endif
  64
  65 /* Called by get_interface_list for each interface that's discovered.
  66    Opens a packet filter for each interface and adds it to the select
  67    mask. */
  68
  69 int if_register_nit (info)
  70         struct interface_info *info;
  71 {
  72         int sock;
  73         char filename[50];
  74         struct ifreq ifr;
  75         struct strioctl sio;
  76
  77         /* Open a NIT device */
  78         sock = open ("/dev/nit", O_RDWR);
  79         if (sock < 0)
  80                 log_fatal ("Can't open NIT device for %s: %m", info -> name);
  81
  82         /* Set the NIT device to point at this interface. */
  83         sio.ic_cmd = NIOCBIND;
  84         sio.ic_len = sizeof *(info -> ifp);
  85         sio.ic_dp = (char *)(info -> ifp);
  86         sio.ic_timout = INFTIM;
  87         if (ioctl (sock, I_STR, &sio) < 0)
  88                 log_fatal ("Can't attach interface %s to nit device: %m",
  89                        info -> name);
  90
  91         /* Get the low-level address... */
  92         sio.ic_cmd = SIOCGIFADDR;
  93         sio.ic_len = sizeof ifr;
  94         sio.ic_dp = (char *)&ifr;
  95         sio.ic_timout = INFTIM;
  96         if (ioctl (sock, I_STR, &sio) < 0)
  97                 log_fatal ("Can't get physical layer address for %s: %m",
  98                        info -> name);
  99
 100         /* XXX code below assumes ethernet interface! */
 101         info -> hw_address.hlen = 7;
 102         info -> hw_address.hbuf [0] = ARPHRD_ETHER;
 103         memcpy (&info -> hw_address.hbuf [1],
 104                 ifr.ifr_ifru.ifru_addr.sa_data, 6);
 105
 106         if (ioctl (sock, I_PUSH, "pf") < 0)
 107                 log_fatal ("Can't push packet filter onto NIT for %s: %m",
 108                        info -> name);
 109
 110         return sock;
 111 }
 112 #endif /* USE_NIT_SEND || USE_NIT_RECEIVE */
 113
 114 #ifdef USE_NIT_SEND
 115 void if_register_send (info)
 116         struct interface_info *info;
 117 {
 118         /* If we're using the nit API for sending and receiving,
 119            we don't need to register this interface twice. */
 120 #ifndef USE_NIT_RECEIVE
 121         struct packetfilt pf;
 122         struct strioctl sio;
 123
 124         info -> wfdesc = if_register_nit (info);
 125
 126         pf.Pf_Priority = 0;
 127         pf.Pf_FilterLen = 1;
 128         pf.Pf_Filter [0] = ENF_PUSHZERO;
 129
 130         /* Set up an NIT filter that rejects everything... */
 131         sio.ic_cmd = NIOCSETF;
 132         sio.ic_len = sizeof pf;
 133         sio.ic_dp = (char *)&pf;
 134         sio.ic_timout = INFTIM;
 135         if (ioctl (info -> wfdesc, I_STR, &sio) < 0)
 136                 log_fatal ("Can't set NIT filter: %m");
 137 #else
 138         info -> wfdesc = info -> rfdesc;
 139 #endif
 140         if (!quiet_interface_discovery)
 141                 log_info ("Sending on   NIT/%s%s%s",
 142                       print_hw_addr (info -> hw_address.hbuf [0],
 143                                      info -> hw_address.hlen - 1,
 144                                      &info -> hw_address.hbuf [1]),
 145                       (info -> shared_network ? "/" : ""),
 146                       (info -> shared_network ?
 147                        info -> shared_network -> name : ""));
 148 }
 149
 150 void if_deregister_send (info)
 151         struct interface_info *info;
 152 {
 153         /* If we're using the nit API for sending and receiving,
 154            we don't need to register this interface twice. */
 155 #ifndef USE_NIT_RECEIVE
 156         close (info -> wfdesc);
 157 #endif
 158         info -> wfdesc = -1;
 159         if (!quiet_interface_discovery)
 160                 log_info ("Disabling output on NIT/%s%s%s",
 161                       print_hw_addr (info -> hw_address.hbuf [0],
 162                                      info -> hw_address.hlen - 1,
 163                                      &info -> hw_address.hbuf [1]),
 164                       (info -> shared_network ? "/" : ""),
 165                       (info -> shared_network ?
 166                        info -> shared_network -> name : ""));
 167 }
 168 #endif /* USE_NIT_SEND */
 169
 170 #ifdef USE_NIT_RECEIVE
 171 /* Packet filter program...
 172    XXX Changes to the filter program may require changes to the constant
 173    offsets used in if_register_send to patch the NIT program! XXX */
 174
 175 #if defined(RELAY_PORT)
 176 #error "Relay port is not yet supported for NIT"
 177 #endif
 178
 179 void if_register_receive (info)
 180         struct interface_info *info;
 181 {
 182         int flag = 1;
 183         u_int32_t x;
 184         struct packetfilt pf;
 185         struct strioctl sio;
 186         u_int16_t addr [2];
 187         struct timeval t;
 188
 189         /* Open a NIT device and hang it on this interface... */
 190         info -> rfdesc = if_register_nit (info);
 191
 192         /* Set the snap length to 0, which means always take the whole
 193            packet. */
 194         x = 0;
 195         if (ioctl (info -> rfdesc, NIOCSSNAP, &x) < 0)
 196                 log_fatal ("Can't set NIT snap length on %s: %m", info -> name);
 197
 198         /* Set the stream to byte stream mode */
 199         if (ioctl (info -> rfdesc, I_SRDOPT, RMSGN) != 0)
 200                 log_info ("I_SRDOPT failed on %s: %m", info -> name);
 201
 202 #if 0
 203         /* Push on the chunker... */
 204         if (ioctl (info -> rfdesc, I_PUSH, "nbuf") < 0)
 205                 log_fatal ("Can't push chunker onto NIT STREAM: %m");
 206
 207         /* Set the timeout to zero. */
 208         t.tv_sec = 0;
 209         t.tv_usec = 0;
 210         if (ioctl (info -> rfdesc, NIOCSTIME, &t) < 0)
 211                 log_fatal ("Can't set chunk timeout: %m");
 212 #endif
 213
 214         /* Ask for no header... */
 215         x = 0;
 216         if (ioctl (info -> rfdesc, NIOCSFLAGS, &x) < 0)
 217                 log_fatal ("Can't set NIT flags on %s: %m", info -> name);
 218
 219         /* Set up the NIT filter program. */
 220         /* XXX Unlike the BPF filter program, this one won't work if the
 221            XXX IP packet is fragmented or if there are options on the IP
 222            XXX header. */
 223         pf.Pf_Priority = 0;
 224         pf.Pf_FilterLen = 0;
 225
 226         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 6;
 227         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND;
 228         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (ETHERTYPE_IP);
 229         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT;
 230         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (IPPROTO_UDP);
 231         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 11;
 232         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_AND;
 233         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (0xFF);
 234         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_CAND;
 235         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 18;
 236         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND;
 237         pf.Pf_Filter [pf.Pf_FilterLen++] = local_port;
 238
 239         /* Install the filter... */
 240         sio.ic_cmd = NIOCSETF;
 241         sio.ic_len = sizeof pf;
 242         sio.ic_dp = (char *)&pf;
 243         sio.ic_timout = INFTIM;
 244         if (ioctl (info -> rfdesc, I_STR, &sio) < 0)
 245                 log_fatal ("Can't set NIT filter on %s: %m", info -> name);
 246
 247         if (!quiet_interface_discovery)
 248                 log_info ("Listening on NIT/%s%s%s",
 249                       print_hw_addr (info -> hw_address.hbuf [0],
 250                                      info -> hw_address.hlen - 1,
 251                                      &info -> hw_address.hbuf [1]),
 252                       (info -> shared_network ? "/" : ""),
 253                       (info -> shared_network ?
 254                        info -> shared_network -> name : ""));
 255 }
 256
 257 void if_deregister_receive (info)
 258         struct interface_info *info;
 259 {
 260         /* If we're using the nit API for sending and receiving,
 261            we don't need to register this interface twice. */
 262         close (info -> rfdesc);
 263         info -> rfdesc = -1;
 264
 265         if (!quiet_interface_discovery)
 266                 log_info ("Disabling input on NIT/%s%s%s",
 267                       print_hw_addr (info -> hw_address.hbuf [0],
 268                                      info -> hw_address.hlen - 1,
 269                                      &info -> hw_address.hbuf [1]),
 270                       (info -> shared_network ? "/" : ""),
 271                       (info -> shared_network ?
 272                        info -> shared_network -> name : ""));
 273 }
 274 #endif /* USE_NIT_RECEIVE */
 275
 276 #ifdef USE_NIT_SEND
 277 ssize_t send_packet (interface, packet, raw, len, from, to, hto)
 278         struct interface_info *interface;
 279         struct packet *packet;
 280         struct dhcp_packet *raw;
 281         size_t len;
 282         struct in_addr from;
 283         struct sockaddr_in *to;
 284         struct hardware *hto;
 285 {
 286         unsigned hbufp, ibufp;
 287         double hh [16];
 288         double ih [1536 / sizeof (double)];
 289         unsigned char *buf = (unsigned char *)ih;
 290         struct sockaddr *junk;
 291         struct strbuf ctl, data;
 292         struct sockaddr_in foo;
 293         int result;
 294
 295         if (!strcmp (interface -> name, "fallback"))
 296                 return send_fallback (interface, packet, raw,
 297                                       len, from, to, hto);
 298
 299         if (hto == NULL && interface->anycast_mac_addr.hlen)
 300                 hto = &interface->anycast_mac_addr;
 301
 302         /* Start with the sockaddr struct... */
 303         junk = (struct sockaddr *)&hh [0];
 304         hbufp = (((unsigned char *)&junk -> sa_data [0]) -
 305                  (unsigned char *)&hh[0]);
 306         ibufp = 0;
 307
 308         /* Assemble the headers... */
 309         assemble_hw_header (interface, (unsigned char *)junk, &hbufp, hto);
 310         assemble_udp_ip_header (interface, buf, &ibufp,
 311                                 from.s_addr, to -> sin_addr.s_addr,
 312                                 to -> sin_port, (unsigned char *)raw, len);
 313
 314         /* Copy the data into the buffer (yuk). */
 315         memcpy (buf + ibufp, raw, len);
 316
 317         /* Set up the sockaddr structure... */
 318 #if USE_SIN_LEN
 319         junk -> sa_len = hbufp - 2; /* XXX */
 320 #endif
 321         junk -> sa_family = AF_UNSPEC;
 322
 323         /* Set up the msg_buf structure... */
 324         ctl.buf = (char *)&hh [0];
 325         ctl.maxlen = ctl.len = hbufp;
 326         data.buf = (char *)&ih [0];
 327         data.maxlen = data.len = ibufp + len;
 328
 329         result = putmsg (interface -> wfdesc, &ctl, &data, 0);
 330         if (result < 0)
 331                 log_error ("send_packet: %m");
 332         return result;
 333 }
 334 #endif /* USE_NIT_SEND */
 335
 336 #ifdef USE_NIT_RECEIVE
 337 ssize_t receive_packet (interface, buf, len, from, hfrom)
 338         struct interface_info *interface;
 339         unsigned char *buf;
 340         size_t len;
 341         struct sockaddr_in *from;
 342         struct hardware *hfrom;
 343 {
 344         int nread;
 345         int length = 0;
 346         int offset = 0;
 347         unsigned char ibuf [1536];
 348         int bufix = 0;
 349         unsigned paylen;
 350
 351         length = read (interface -> rfdesc, ibuf, sizeof ibuf);
 352         if (length <= 0)
 353                 return length;
 354
 355         /* Decode the physical header... */
 356         offset = decode_hw_header (interface, ibuf, bufix, hfrom);
 357
 358         /* If a physical layer checksum failed (dunno of any
 359            physical layer that supports this, but WTH), skip this
 360            packet. */
 361         if (offset < 0) {
 362                 return 0;
 363         }
 364
 365         bufix += offset;
 366         length -= offset;
 367
 368         /* Decode the IP and UDP headers... */
 369         offset = decode_udp_ip_header (interface, ibuf, bufix,
 370                                        from, length, &paylen, 1);
 371
 372         /* If the IP or UDP checksum was bad, skip the packet... */
 373         if (offset < 0)
 374                 return 0;
 375
 376         bufix += offset;
 377         length -= offset;
 378
 379         if (length < paylen)
 380                 log_fatal("Internal inconsistency at %s:%d.", MDL);
 381
 382         /* Copy out the data in the packet... */
 383         memcpy(buf, &ibuf[bufix], paylen);
 384         return paylen;
 385 }
 386
 387 int can_unicast_without_arp (ip)
 388         struct interface_info *ip;
 389 {
 390         return 1;
 391 }
 392
 393 int can_receive_unicast_unconfigured (ip)
 394         struct interface_info *ip;
 395 {
 396         return 1;
 397 }
 398
 399 int supports_multiple_interfaces (ip)
 400         struct interface_info *ip;
 401 {
 402         return 1;
 403 }
 404
 405 void maybe_setup_fallback ()
 406 {
 407         isc_result_t status;
 408         struct interface_info *fbi = (struct interface_info *)0;
 409         if (setup_fallback (&fbi, MDL)) {
 410                 if_register_fallback (fbi);
 411                 status = omapi_register_io_object ((omapi_object_t *)fbi,
 412                                                    if_readsocket, 0,
 413                                                    fallback_discard, 0, 0);
 414                 if (status != ISC_R_SUCCESS)
 415                         log_fatal ("Can't register I/O handle for %s: %s",
 416                                    fbi -> name, isc_result_totext (status));
 417                 interface_dereference (&fbi, MDL);
 418         }
 419 }
 420 #endif