contrib/dhcp-3.0/common/bpf.c

   1 /* bpf.c
   2
   3    BPF socket interface code, originally contributed by Archie Cobbs. */
   4
   5 /*
   6  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   7  * Copyright (c) 1996-2003 by Internet Software Consortium
   8  *
   9  * Permission to use, copy, modify, and distribute this software for any
  10  * purpose with or without fee is hereby granted, provided that the above
  11  * copyright notice and this permission notice appear in all copies.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  15  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  19  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  20  *
  21  *   Internet Systems Consortium, Inc.
  22  *   950 Charter Street
  23  *   Redwood City, CA 94063
  24  *   <info@isc.org>
  25  *   http://www.isc.org/
  26  *
  27  * This software was contributed to Internet Systems Consortium
  28  * by Archie Cobbs.
  29  *
  30  * Patches for FDDI support on Digital Unix were written by Bill
  31  * Stapleton, and maintained for a while by Mike Meredith before he
  32  * managed to get me to integrate them.
  33  */
  34
  35 #ifndef lint
  36 static char copyright[] =
  37 "$Id: bpf.c,v 1.48.2.7 2004/11/24 17:39:15 dhankins Exp $ Copyright (c) 2004 Internet Systems Consortium.  All rights reserved.\n";
  38 #endif /* not lint */
  39
  40 #include "dhcpd.h"
  41 #if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE) \
  42                                 || defined (USE_LPF_RECEIVE)
  43 # if defined (USE_LPF_RECEIVE)
  44 #  include <asm/types.h>
  45 #  include <linux/filter.h>
  46 #  define bpf_insn sock_filter /* Linux: dare to be gratuitously different. */
  47 # else
  48 #  include <sys/ioctl.h>
  49 #  include <sys/uio.h>
  50 #  include <net/bpf.h>
  51 #  if defined (NEED_OSF_PFILT_HACKS)
  52 #   include <net/pfilt.h>
  53 #  endif
  54 # endif
  55
  56 #include <netinet/in_systm.h>
  57 #include "includes/netinet/ip.h"
  58 #include "includes/netinet/udp.h"
  59 #include "includes/netinet/if_ether.h"
  60 #endif
  61
  62 /* Reinitializes the specified interface after an address change.   This
  63    is not required for packet-filter APIs. */
  64
  65 #ifdef USE_BPF_SEND
  66 void if_reinitialize_send (info)
  67         struct interface_info *info;
  68 {
  69 }
  70 #endif
  71
  72 #ifdef USE_BPF_RECEIVE
  73 void if_reinitialize_receive (info)
  74         struct interface_info *info;
  75 {
  76 }
  77 #endif
  78
  79 /* Called by get_interface_list for each interface that's discovered.
  80    Opens a packet filter for each interface and adds it to the select
  81    mask. */
  82
  83 #if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE)
  84 int if_register_bpf (info)
  85         struct interface_info *info;
  86 {
  87         int sock;
  88         char filename[50];
  89         int b;
  90
  91         /* Open a BPF device */
  92         for (b = 0; 1; b++) {
  93                 /* %Audit% 31 bytes max. %2004.06.17,Safe% */
  94                 sprintf(filename, BPF_FORMAT, b);
  95                 sock = open (filename, O_RDWR, 0);
  96                 if (sock < 0) {
  97                         if (errno == EBUSY) {
  98                                 continue;
  99                         } else {
 100                                 if (!b)
 101                                         log_fatal ("No bpf devices.%s%s%s",
 102                                                "   Please read the README",
 103                                                " section for your operating",
 104                                                " system.");
 105                                 log_fatal ("Can't find free bpf: %m");
 106                         }
 107                 } else {
 108                         break;
 109                 }
 110         }
 111
 112         /* Set the BPF device to point at this interface. */
 113         if (ioctl (sock, BIOCSETIF, info -> ifp) < 0)
 114                 log_fatal ("Can't attach interface %s to bpf device %s: %m",
 115                        info -> name, filename);
 116
 117         return sock;
 118 }
 119 #endif /* USE_BPF_SEND || USE_BPF_RECEIVE */
 120
 121 #ifdef USE_BPF_SEND
 122 void if_register_send (info)
 123         struct interface_info *info;
 124 {
 125         /* If we're using the bpf API for sending and receiving,
 126            we don't need to register this interface twice. */
 127 #ifndef USE_BPF_RECEIVE
 128         info -> wfdesc = if_register_bpf (info, interface);
 129 #else
 130         info -> wfdesc = info -> rfdesc;
 131 #endif
 132         if (!quiet_interface_discovery)
 133                 log_info ("Sending on   BPF/%s/%s%s%s",
 134                       info -> name,
 135                       print_hw_addr (info -> hw_address.hbuf [0],
 136                                      info -> hw_address.hlen - 1,
 137                                      &info -> hw_address.hbuf [1]),
 138                       (info -> shared_network ? "/" : ""),
 139                       (info -> shared_network ?
 140                        info -> shared_network -> name : ""));
 141 }
 142
 143 void if_deregister_send (info)
 144         struct interface_info *info;
 145 {
 146         /* If we're using the bpf API for sending and receiving,
 147            we don't need to register this interface twice. */
 148 #ifndef USE_BPF_RECEIVE
 149         close (info -> wfdesc);
 150 #endif
 151         info -> wfdesc = -1;
 152
 153         if (!quiet_interface_discovery)
 154                 log_info ("Disabling output on BPF/%s/%s%s%s",
 155                       info -> name,
 156                       print_hw_addr (info -> hw_address.hbuf [0],
 157                                      info -> hw_address.hlen - 1,
 158                                      &info -> hw_address.hbuf [1]),
 159                       (info -> shared_network ? "/" : ""),
 160                       (info -> shared_network ?
 161                        info -> shared_network -> name : ""));
 162 }
 163 #endif /* USE_BPF_SEND */
 164
 165 #if defined (USE_BPF_RECEIVE) || defined (USE_LPF_RECEIVE)
 166 /* Packet filter program...
 167    XXX Changes to the filter program may require changes to the constant
 168    offsets used in if_register_send to patch the BPF program! XXX */
 169
 170 struct bpf_insn dhcp_bpf_filter [] = {
 171         /* Make sure this is an IP packet... */
 172         BPF_STMT (BPF_LD + BPF_H + BPF_ABS, 12),
 173         BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8),
 174
 175         /* Make sure it's a UDP packet... */
 176         BPF_STMT (BPF_LD + BPF_B + BPF_ABS, 23),
 177         BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6),
 178
 179         /* Make sure this isn't a fragment... */
 180         BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20),
 181         BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0),
 182
 183         /* Get the IP header length... */
 184         BPF_STMT (BPF_LDX + BPF_B + BPF_MSH, 14),
 185
 186         /* Make sure it's to the right port... */
 187         BPF_STMT (BPF_LD + BPF_H + BPF_IND, 16),
 188         BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1),             /* patch */
 189
 190         /* If we passed all the tests, ask for the whole packet. */
 191         BPF_STMT(BPF_RET+BPF_K, (u_int)-1),
 192
 193         /* Otherwise, drop it. */
 194         BPF_STMT(BPF_RET+BPF_K, 0),
 195 };
 196
 197 #if defined (DEC_FDDI)
 198 struct bpf_insn *bpf_fddi_filter;
 199 #endif
 200
 201 int dhcp_bpf_filter_len = sizeof dhcp_bpf_filter / sizeof (struct bpf_insn);
 202 #if defined (HAVE_TR_SUPPORT)
 203 struct bpf_insn dhcp_bpf_tr_filter [] = {
 204         /* accept all token ring packets due to variable length header */
 205         /* if we want to get clever, insert the program here */
 206
 207         /* If we passed all the tests, ask for the whole packet. */
 208         BPF_STMT(BPF_RET+BPF_K, (u_int)-1),
 209
 210         /* Otherwise, drop it. */
 211         BPF_STMT(BPF_RET+BPF_K, 0),
 212 };
 213
 214 int dhcp_bpf_tr_filter_len = (sizeof dhcp_bpf_tr_filter /
 215                               sizeof (struct bpf_insn));
 216 #endif /* HAVE_TR_SUPPORT */
 217 #endif /* USE_LPF_RECEIVE || USE_BPF_RECEIVE */
 218
 219 #if defined (USE_BPF_RECEIVE)
 220 void if_register_receive (info)
 221         struct interface_info *info;
 222 {
 223         int flag = 1;
 224         struct bpf_version v;
 225         u_int32_t addr;
 226         struct bpf_program p;
 227         u_int32_t bits;
 228 #ifdef DEC_FDDI
 229         int link_layer;
 230 #endif /* DEC_FDDI */
 231
 232         /* Open a BPF device and hang it on this interface... */
 233         info -> rfdesc = if_register_bpf (info);
 234
 235         /* Make sure the BPF version is in range... */
 236         if (ioctl (info -> rfdesc, BIOCVERSION, &v) < 0)
 237                 log_fatal ("Can't get BPF version: %m");
 238
 239         if (v.bv_major != BPF_MAJOR_VERSION ||
 240             v.bv_minor < BPF_MINOR_VERSION)
 241                 log_fatal ("BPF version mismatch - recompile DHCP!");
 242
 243         /* Set immediate mode so that reads return as soon as a packet
 244            comes in, rather than waiting for the input buffer to fill with
 245            packets. */
 246         if (ioctl (info -> rfdesc, BIOCIMMEDIATE, &flag) < 0)
 247                 log_fatal ("Can't set immediate mode on bpf device: %m");
 248
 249 #ifdef NEED_OSF_PFILT_HACKS
 250         /* Allow the copyall flag to be set... */
 251         if (ioctl(info -> rfdesc, EIOCALLOWCOPYALL, &flag) < 0)
 252                 log_fatal ("Can't set ALLOWCOPYALL: %m");
 253
 254         /* Clear all the packet filter mode bits first... */
 255         bits = 0;
 256         if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
 257                 log_fatal ("Can't clear pfilt bits: %m");
 258
 259         /* Set the ENBATCH, ENCOPYALL, ENBPFHDR bits... */
 260         bits = ENBATCH | ENCOPYALL | ENBPFHDR;
 261         if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
 262                 log_fatal ("Can't set ENBATCH|ENCOPYALL|ENBPFHDR: %m");
 263 #endif
 264         /* Get the required BPF buffer length from the kernel. */
 265         if (ioctl (info -> rfdesc, BIOCGBLEN, &info -> rbuf_max) < 0)
 266                 log_fatal ("Can't get bpf buffer length: %m");
 267         info -> rbuf = dmalloc (info -> rbuf_max, MDL);
 268         if (!info -> rbuf)
 269                 log_fatal ("Can't allocate %ld bytes for bpf input buffer.",
 270                            (long)(info -> rbuf_max));
 271         info -> rbuf_offset = 0;
 272         info -> rbuf_len = 0;
 273
 274         /* Set up the bpf filter program structure. */
 275         p.bf_len = dhcp_bpf_filter_len;
 276
 277 #ifdef DEC_FDDI
 278         /* See if this is an FDDI interface, flag it for later. */
 279         if (ioctl(info -> rfdesc, BIOCGDLT, &link_layer) >= 0 &&
 280             link_layer == DLT_FDDI) {
 281                 if (!bpf_fddi_filter) {
 282                         bpf_fddi_filter = dmalloc (sizeof bpf_fddi_filter,
 283                                                     MDL);
 284                         if (!bpf_fddi_filter)
 285                                 log_fatal ("No memory for FDDI filter.");
 286                         memcpy (bpf_fddi_filter,
 287                                 dhcp_bpf_filter, sizeof dhcp_bpf_filter);
 288                         /* Patch the BPF program to account for the difference
 289                            in length between ethernet headers (14), FDDI and
 290                            802.2 headers (16 +8=24, +10).
 291                            XXX changes to filter program may require changes to
 292                            XXX the insn number(s) used below! */
 293                         bpf_fddi_filter[0].k += 10;
 294                         bpf_fddi_filter[2].k += 10;
 295                         bpf_fddi_filter[4].k += 10;
 296                         bpf_fddi_filter[6].k += 10;
 297                         bpf_fddi_filter[7].k += 10;
 298                 }
 299                 p.bf_insns = bpf_fddi_filter;
 300         } else
 301 #endif /* DEC_FDDI */
 302         p.bf_insns = dhcp_bpf_filter;
 303
 304         /* Patch the server port into the BPF  program...
 305            XXX changes to filter program may require changes
 306            to the insn number(s) used below! XXX */
 307         dhcp_bpf_filter [8].k = ntohs (local_port);
 308
 309         if (ioctl (info -> rfdesc, BIOCSETF, &p) < 0)
 310                 log_fatal ("Can't install packet filter program: %m");
 311         if (!quiet_interface_discovery)
 312                 log_info ("Listening on BPF/%s/%s%s%s",
 313                       info -> name,
 314                       print_hw_addr (info -> hw_address.hbuf [0],
 315                                      info -> hw_address.hlen - 1,
 316                                      &info -> hw_address.hbuf [1]),
 317                       (info -> shared_network ? "/" : ""),
 318                       (info -> shared_network ?
 319                        info -> shared_network -> name : ""));
 320 }
 321
 322 void if_deregister_receive (info)
 323         struct interface_info *info;
 324 {
 325         close (info -> rfdesc);
 326         info -> rfdesc = -1;
 327
 328         if (!quiet_interface_discovery)
 329                 log_info ("Disabling input on BPF/%s/%s%s%s",
 330                       info -> name,
 331                       print_hw_addr (info -> hw_address.hbuf [0],
 332                                      info -> hw_address.hlen - 1,
 333                                      &info -> hw_address.hbuf [1]),
 334                       (info -> shared_network ? "/" : ""),
 335                       (info -> shared_network ?
 336                        info -> shared_network -> name : ""));
 337 }
 338 #endif /* USE_BPF_RECEIVE */
 339
 340 #ifdef USE_BPF_SEND
 341 ssize_t send_packet (interface, packet, raw, len, from, to, hto)
 342         struct interface_info *interface;
 343         struct packet *packet;
 344         struct dhcp_packet *raw;
 345         size_t len;
 346         struct in_addr from;
 347         struct sockaddr_in *to;
 348         struct hardware *hto;
 349 {
 350         unsigned hbufp = 0, ibufp = 0;
 351         double hw [4];
 352         double ip [32];
 353         struct iovec iov [3];
 354         int result;
 355         int fudge;
 356
 357         if (!strcmp (interface -> name, "fallback"))
 358                 return send_fallback (interface, packet, raw,
 359                                       len, from, to, hto);
 360
 361         /* Assemble the headers... */
 362         assemble_hw_header (interface, (unsigned char *)hw, &hbufp, hto);
 363         assemble_udp_ip_header (interface,
 364                                 (unsigned char *)ip, &ibufp, from.s_addr,
 365                                 to -> sin_addr.s_addr, to -> sin_port,
 366                                 (unsigned char *)raw, len);
 367
 368         /* Fire it off */
 369         iov [0].iov_base = ((char *)hw);
 370         iov [0].iov_len = hbufp;
 371         iov [1].iov_base = ((char *)ip);
 372         iov [1].iov_len = ibufp;
 373         iov [2].iov_base = (char *)raw;
 374         iov [2].iov_len = len;
 375
 376         result = writev(interface -> wfdesc, iov, 3);
 377         if (result < 0)
 378                 log_error ("send_packet: %m");
 379         return result;
 380 }
 381 #endif /* USE_BPF_SEND */
 382
 383 #ifdef USE_BPF_RECEIVE
 384 ssize_t receive_packet (interface, buf, len, from, hfrom)
 385         struct interface_info *interface;
 386         unsigned char *buf;
 387         size_t len;
 388         struct sockaddr_in *from;
 389         struct hardware *hfrom;
 390 {
 391         int length = 0;
 392         int offset = 0;
 393         struct bpf_hdr hdr;
 394
 395         /* All this complexity is because BPF doesn't guarantee
 396            that only one packet will be returned at a time.   We're
 397            getting what we deserve, though - this is a terrible abuse
 398            of the BPF interface.   Sigh. */
 399
 400         /* Process packets until we get one we can return or until we've
 401            done a read and gotten nothing we can return... */
 402
 403         do {
 404                 /* If the buffer is empty, fill it. */
 405                 if (interface -> rbuf_offset == interface -> rbuf_len) {
 406                         length = read (interface -> rfdesc,
 407                                        interface -> rbuf,
 408                                        (size_t)interface -> rbuf_max);
 409                         if (length <= 0) {
 410 #ifdef __FreeBSD__
 411                                 if (errno == ENXIO) {
 412 #else
 413                                 if (errno == EIO) {
 414 #endif
 415                                         dhcp_interface_remove
 416                                                 ((omapi_object_t *)interface,
 417                                                  (omapi_object_t *)0);
 418                                 }
 419                                 return length;
 420                         }
 421                         interface -> rbuf_offset = 0;
 422                         interface -> rbuf_len = BPF_WORDALIGN (length);
 423                 }
 424
 425                 /* If there isn't room for a whole bpf header, something went
 426                    wrong, but we'll ignore it and hope it goes away... XXX */
 427                 if (interface -> rbuf_len -
 428                     interface -> rbuf_offset < sizeof hdr) {
 429                         interface -> rbuf_offset = interface -> rbuf_len;
 430                         continue;
 431                 }
 432
 433                 /* Copy out a bpf header... */
 434                 memcpy (&hdr, &interface -> rbuf [interface -> rbuf_offset],
 435                         sizeof hdr);
 436
 437                 /* If the bpf header plus data doesn't fit in what's left
 438                    of the buffer, stick head in sand yet again... */
 439                 if (interface -> rbuf_offset +
 440                     hdr.bh_hdrlen + hdr.bh_caplen > interface -> rbuf_len) {
 441                         interface -> rbuf_offset = interface -> rbuf_len;
 442                         continue;
 443                 }
 444
 445                 /* If the captured data wasn't the whole packet, or if
 446                    the packet won't fit in the input buffer, all we
 447                    can do is drop it. */
 448                 if (hdr.bh_caplen != hdr.bh_datalen) {
 449                         interface -> rbuf_offset =
 450                                 BPF_WORDALIGN (interface -> rbuf_offset +
 451                                                hdr.bh_hdrlen + hdr.bh_caplen);
 452                         continue;
 453                 }
 454
 455                 /* Skip over the BPF header... */
 456                 interface -> rbuf_offset += hdr.bh_hdrlen;
 457
 458                 /* Decode the physical header... */
 459                 offset = decode_hw_header (interface,
 460                                            interface -> rbuf,
 461                                            interface -> rbuf_offset,
 462                                            hfrom);
 463
 464                 /* If a physical layer checksum failed (dunno of any
 465                    physical layer that supports this, but WTH), skip this
 466                    packet. */
 467                 if (offset < 0) {
 468                         interface -> rbuf_offset =
 469                                 BPF_WORDALIGN (interface -> rbuf_offset +
 470                                                hdr.bh_caplen);
 471                         continue;
 472                 }
 473                 interface -> rbuf_offset += offset;
 474                 hdr.bh_caplen -= offset;
 475
 476                 /* Decode the IP and UDP headers... */
 477                 offset = decode_udp_ip_header (interface,
 478                                                interface -> rbuf,
 479                                                interface -> rbuf_offset,
 480                                                from,
 481                                                hdr.bh_caplen);
 482
 483                 /* If the IP or UDP checksum was bad, skip the packet... */
 484                 if (offset < 0) {
 485                         interface -> rbuf_offset =
 486                                 BPF_WORDALIGN (interface -> rbuf_offset +
 487                                                hdr.bh_caplen);
 488                         continue;
 489                 }
 490                 interface -> rbuf_offset = interface -> rbuf_offset + offset;
 491                 hdr.bh_caplen -= offset;
 492
 493                 /* If there's not enough room to stash the packet data,
 494                    we have to skip it (this shouldn't happen in real
 495                    life, though). */
 496                 if (hdr.bh_caplen > len) {
 497                         interface -> rbuf_offset =
 498                                 BPF_WORDALIGN (interface -> rbuf_offset +
 499                                                hdr.bh_caplen);
 500                         continue;
 501                 }
 502
 503                 /* Copy out the data in the packet... */
 504                 memcpy (buf, interface -> rbuf + interface -> rbuf_offset,
 505                         hdr.bh_caplen);
 506                 interface -> rbuf_offset =
 507                         BPF_WORDALIGN (interface -> rbuf_offset +
 508                                        hdr.bh_caplen);
 509                 return hdr.bh_caplen;
 510         } while (!length);
 511         return 0;
 512 }
 513
 514 int can_unicast_without_arp (ip)
 515         struct interface_info *ip;
 516 {
 517         return 1;
 518 }
 519
 520 int can_receive_unicast_unconfigured (ip)
 521         struct interface_info *ip;
 522 {
 523         return 1;
 524 }
 525
 526 int supports_multiple_interfaces (ip)
 527         struct interface_info *ip;
 528 {
 529         return 1;
 530 }
 531
 532 void maybe_setup_fallback ()
 533 {
 534         isc_result_t status;
 535         struct interface_info *fbi = (struct interface_info *)0;
 536         if (setup_fallback (&fbi, MDL)) {
 537                 if_register_fallback (fbi);
 538                 status = omapi_register_io_object ((omapi_object_t *)fbi,
 539                                                    if_readsocket, 0,
 540                                                    fallback_discard, 0, 0);
 541                 if (status != ISC_R_SUCCESS)
 542                         log_fatal ("Can't register I/O handle for %s: %s",
 543                                    fbi -> name, isc_result_totext (status));
 544                 interface_dereference (&fbi, MDL);
 545         }
 546 }
 547 #endif