isisd/isis_bpf.c

   1 /*
   2  * IS-IS Rout(e)ing protocol - isis_bpf.c
   3  *
   4  * Copyright (C) 2001,2002    Sampo Saaristo
   5  *                            Tampere University of Technology
   6  *                            Institute of Communications Engineering
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public Licenseas published by the Free
  10  * Software Foundation; either version 2 of the License, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,but WITHOUT
  14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16  * more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; see the file COPYING; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <zebra.h>
  24 #if ISIS_METHOD == ISIS_METHOD_BPF
  25 #include <net/if.h>
  26 #include <netinet/if_ether.h>
  27 #include <sys/time.h>
  28 #include <sys/ioctl.h>
  29 #include <net/bpf.h>
  30
  31 #include "log.h"
  32 #include "network.h"
  33 #include "stream.h"
  34 #include "if.h"
  35
  36 #include "isisd/dict.h"
  37 #include "isisd/isis_constants.h"
  38 #include "isisd/isis_common.h"
  39 #include "isisd/isis_circuit.h"
  40 #include "isisd/isis_flags.h"
  41 #include "isisd/isisd.h"
  42 #include "isisd/isis_constants.h"
  43 #include "isisd/isis_circuit.h"
  44 #include "isisd/isis_network.h"
  45
  46 #include "privs.h"
  47
  48 extern struct zebra_privs_t isisd_privs;
  49
  50 struct bpf_insn llcfilter[] = {
  51         /* check first byte */
  52         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETH_ALEN),
  53         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0, 5),
  54         /* check second byte */
  55         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETH_ALEN + 1),
  56         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0, 3),
  57         /* check third byte */
  58         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETH_ALEN + 2),
  59         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x03, 0, 1),
  60         BPF_STMT(BPF_RET + BPF_K, (u_int)-1),
  61         BPF_STMT(BPF_RET + BPF_K, 0)};
  62 u_int readblen = 0;
  63 u_char *readbuff = NULL;
  64
  65 /*
  66  * Table 9 - Architectural constants for use with ISO 8802 subnetworks
  67  * ISO 10589 - 8.4.8
  68  */
  69
  70 u_char ALL_L1_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x14};
  71 u_char ALL_L2_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x15};
  72 u_char ALL_ISS[6] = {0x09, 0x00, 0x2B, 0x00, 0x00, 0x05};
  73 u_char ALL_ESS[6] = {0x09, 0x00, 0x2B, 0x00, 0x00, 0x04};
  74
  75 static char sock_buff[8192];
  76
  77 static int open_bpf_dev(struct isis_circuit *circuit)
  78 {
  79         int i = 0, fd;
  80         char bpfdev[128];
  81         struct ifreq ifr;
  82         u_int blen, immediate;
  83 #ifdef BIOCSSEESENT
  84         u_int seesent;
  85 #endif
  86         struct timeval timeout;
  87         struct bpf_program bpf_prog;
  88
  89         do {
  90                 (void)snprintf(bpfdev, sizeof(bpfdev), "/dev/bpf%d", i++);
  91                 fd = open(bpfdev, O_RDWR);
  92         } while (fd < 0 && errno == EBUSY);
  93
  94         if (fd < 0) {
  95                 zlog_warn("open_bpf_dev(): failed to create bpf socket: %s",
  96                           safe_strerror(errno));
  97                 return ISIS_WARNING;
  98         }
  99
 100         zlog_debug("Opened BPF device %s", bpfdev);
 101
 102         memcpy(ifr.ifr_name, circuit->interface->name, sizeof(ifr.ifr_name));
 103         if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) < 0) {
 104                 zlog_warn("open_bpf_dev(): failed to bind to interface: %s",
 105                           safe_strerror(errno));
 106                 return ISIS_WARNING;
 107         }
 108
 109         if (ioctl(fd, BIOCGBLEN, (caddr_t)&blen) < 0) {
 110                 zlog_warn("failed to get BPF buffer len");
 111                 blen = circuit->interface->mtu;
 112         }
 113
 114         readblen = blen;
 115
 116         if (readbuff == NULL)
 117                 readbuff = malloc(blen);
 118
 119         zlog_debug("BPF buffer len = %u", blen);
 120
 121         /*  BPF(4): reads return immediately upon packet reception.
 122          *  Otherwise, a read will block until either the kernel
 123          *  buffer becomes full or a timeout occurs.
 124          */
 125         immediate = 1;
 126         if (ioctl(fd, BIOCIMMEDIATE, (caddr_t)&immediate) < 0) {
 127                 zlog_warn("failed to set BPF dev to immediate mode");
 128         }
 129
 130 #ifdef BIOCSSEESENT
 131         /*
 132          * We want to see only incoming packets
 133          */
 134         seesent = 0;
 135         if (ioctl(fd, BIOCSSEESENT, (caddr_t)&seesent) < 0) {
 136                 zlog_warn("failed to set BPF dev to incoming only mode");
 137         }
 138 #endif
 139
 140         /*
 141          * ...but all of them
 142          */
 143         if (ioctl(fd, BIOCPROMISC) < 0) {
 144                 zlog_warn("failed to set BPF dev to promiscuous mode");
 145         }
 146
 147         /*
 148          * If the buffer length is smaller than our mtu, lets try to increase it
 149          */
 150         if (blen < circuit->interface->mtu) {
 151                 if (ioctl(fd, BIOCSBLEN, &circuit->interface->mtu) < 0) {
 152                         zlog_warn("failed to set BPF buffer len (%u to %u)",
 153                                   blen, circuit->interface->mtu);
 154                 }
 155         }
 156
 157         /*
 158          * Set a timeout parameter - hope this helps select()
 159          */
 160         timeout.tv_sec = 600;
 161         timeout.tv_usec = 0;
 162         if (ioctl(fd, BIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 163                 zlog_warn("failed to set BPF device timeout");
 164         }
 165
 166         /*
 167          * And set the filter
 168          */
 169         memset(&bpf_prog, 0, sizeof(struct bpf_program));
 170         bpf_prog.bf_len = 8;
 171         bpf_prog.bf_insns = &(llcfilter[0]);
 172         if (ioctl(fd, BIOCSETF, (caddr_t)&bpf_prog) < 0) {
 173                 zlog_warn("open_bpf_dev(): failed to install filter: %s",
 174                           safe_strerror(errno));
 175                 return ISIS_WARNING;
 176         }
 177
 178         assert(fd > 0);
 179
 180         circuit->fd = fd;
 181
 182         return ISIS_OK;
 183 }
 184
 185 /*
 186  * Create the socket and set the tx/rx funcs
 187  */
 188 int isis_sock_init(struct isis_circuit *circuit)
 189 {
 190         int retval = ISIS_OK;
 191
 192         if (isisd_privs.change(ZPRIVS_RAISE))
 193                 zlog_err("%s: could not raise privs, %s", __func__,
 194                          safe_strerror(errno));
 195
 196         retval = open_bpf_dev(circuit);
 197
 198         if (retval != ISIS_OK) {
 199                 zlog_warn("%s: could not initialize the socket", __func__);
 200                 goto end;
 201         }
 202
 203         if (if_is_broadcast(circuit->interface)) {
 204                 circuit->tx = isis_send_pdu_bcast;
 205                 circuit->rx = isis_recv_pdu_bcast;
 206         } else {
 207                 zlog_warn("isis_sock_init(): unknown circuit type");
 208                 retval = ISIS_WARNING;
 209                 goto end;
 210         }
 211
 212 end:
 213         if (isisd_privs.change(ZPRIVS_LOWER))
 214                 zlog_err("%s: could not lower privs, %s", __func__,
 215                          safe_strerror(errno));
 216
 217         return retval;
 218 }
 219
 220 int isis_recv_pdu_bcast(struct isis_circuit *circuit, u_char *ssnpa)
 221 {
 222         int bytesread = 0, bytestoread, offset, one = 1;
 223         struct bpf_hdr *bpf_hdr;
 224
 225         assert(circuit->fd > 0);
 226
 227         if (ioctl(circuit->fd, FIONREAD, (caddr_t)&bytestoread) < 0) {
 228                 zlog_warn("ioctl() FIONREAD failed: %s", safe_strerror(errno));
 229         }
 230
 231         if (bytestoread) {
 232                 bytesread = read(circuit->fd, readbuff, readblen);
 233         }
 234         if (bytesread < 0) {
 235                 zlog_warn("isis_recv_pdu_bcast(): read() failed: %s",
 236                           safe_strerror(errno));
 237                 return ISIS_WARNING;
 238         }
 239
 240         if (bytesread == 0)
 241                 return ISIS_WARNING;
 242
 243         bpf_hdr = (struct bpf_hdr *)readbuff;
 244
 245         assert(bpf_hdr->bh_caplen == bpf_hdr->bh_datalen);
 246
 247         offset = bpf_hdr->bh_hdrlen + LLC_LEN + ETH_ALEN;
 248
 249         /* then we lose the BPF, LLC and ethernet headers */
 250         stream_write(circuit->rcv_stream, readbuff + offset,
 251                      bpf_hdr->bh_caplen - LLC_LEN - ETH_ALEN);
 252         stream_set_getp(circuit->rcv_stream, 0);
 253
 254         memcpy(ssnpa, readbuff + bpf_hdr->bh_hdrlen + ETH_ALEN, ETH_ALEN);
 255
 256         if (ioctl(circuit->fd, BIOCFLUSH, &one) < 0)
 257                 zlog_warn("Flushing failed: %s", safe_strerror(errno));
 258
 259         return ISIS_OK;
 260 }
 261
 262 int isis_send_pdu_bcast(struct isis_circuit *circuit, int level)
 263 {
 264         struct ether_header *eth;
 265         ssize_t written;
 266         size_t buflen;
 267
 268         buflen = stream_get_endp(circuit->snd_stream) + LLC_LEN + ETH_ALEN;
 269         if (buflen > sizeof(sock_buff)) {
 270                 zlog_warn(
 271                         "isis_send_pdu_bcast: sock_buff size %zu is less than "
 272                         "output pdu size %zu on circuit %s",
 273                         sizeof(sock_buff), buflen, circuit->interface->name);
 274                 return ISIS_WARNING;
 275         }
 276
 277         stream_set_getp(circuit->snd_stream, 0);
 278
 279         /*
 280          * First the eth header
 281          */
 282         eth = (struct ether_header *)sock_buff;
 283         if (level == 1)
 284                 memcpy(eth->ether_dhost, ALL_L1_ISS, ETH_ALEN);
 285         else
 286                 memcpy(eth->ether_dhost, ALL_L2_ISS, ETH_ALEN);
 287         memcpy(eth->ether_shost, circuit->u.bc.snpa, ETH_ALEN);
 288         size_t frame_size = stream_get_endp(circuit->snd_stream) + LLC_LEN;
 289         eth->ether_type = htons(isis_ethertype(frame_size));
 290
 291         /*
 292          * Then the LLC
 293          */
 294         sock_buff[ETH_ALEN] = ISO_SAP;
 295         sock_buff[ETH_ALEN + 1] = ISO_SAP;
 296         sock_buff[ETH_ALEN + 2] = 0x03;
 297
 298         /* then we copy the data */
 299         memcpy(sock_buff + (LLC_LEN + ETH_ALEN), circuit->snd_stream->data,
 300                stream_get_endp(circuit->snd_stream));
 301
 302         /* now we can send this */
 303         written = write(circuit->fd, sock_buff, buflen);
 304         if (written < 0) {
 305                 zlog_warn("IS-IS bpf: could not transmit packet on %s: %s",
 306                           circuit->interface->name, safe_strerror(errno));
 307                 if (ERRNO_IO_RETRY(errno))
 308                         return ISIS_WARNING;
 309                 return ISIS_ERROR;
 310         }
 311
 312         return ISIS_OK;
 313 }
 314
 315 #endif /* ISIS_METHOD == ISIS_METHOD_BPF */