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 struct bpf_insn llcfilter[] = {
  49         /* check first byte */
  50         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETH_ALEN),
  51         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0, 5),
  52         /* check second byte */
  53         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETH_ALEN + 1),
  54         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0, 3),
  55         /* check third byte */
  56         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETH_ALEN + 2),
  57         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x03, 0, 1),
  58         BPF_STMT(BPF_RET + BPF_K, (u_int)-1),
  59         BPF_STMT(BPF_RET + BPF_K, 0)};
  60 u_int readblen = 0;
  61 u_char *readbuff = NULL;
  62
  63 /*
  64  * Table 9 - Architectural constants for use with ISO 8802 subnetworks
  65  * ISO 10589 - 8.4.8
  66  */
  67
  68 u_char ALL_L1_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x14};
  69 u_char ALL_L2_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x15};
  70 u_char ALL_ISS[6] = {0x09, 0x00, 0x2B, 0x00, 0x00, 0x05};
  71 u_char ALL_ESS[6] = {0x09, 0x00, 0x2B, 0x00, 0x00, 0x04};
  72
  73 static char sock_buff[8192];
  74
  75 static int open_bpf_dev(struct isis_circuit *circuit)
  76 {
  77         int i = 0, fd;
  78         char bpfdev[128];
  79         struct ifreq ifr;
  80         u_int blen, immediate;
  81 #ifdef BIOCSSEESENT
  82         u_int seesent;
  83 #endif
  84         struct timeval timeout;
  85         struct bpf_program bpf_prog;
  86
  87         do {
  88                 (void)snprintf(bpfdev, sizeof(bpfdev), "/dev/bpf%d", i++);
  89                 fd = open(bpfdev, O_RDWR);
  90         } while (fd < 0 && errno == EBUSY);
  91
  92         if (fd < 0) {
  93                 zlog_warn("open_bpf_dev(): failed to create bpf socket: %s",
  94                           safe_strerror(errno));
  95                 return ISIS_WARNING;
  96         }
  97
  98         zlog_debug("Opened BPF device %s", bpfdev);
  99
 100         memcpy(ifr.ifr_name, circuit->interface->name, sizeof(ifr.ifr_name));
 101         if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) < 0) {
 102                 zlog_warn("open_bpf_dev(): failed to bind to interface: %s",
 103                           safe_strerror(errno));
 104                 return ISIS_WARNING;
 105         }
 106
 107         if (ioctl(fd, BIOCGBLEN, (caddr_t)&blen) < 0) {
 108                 zlog_warn("failed to get BPF buffer len");
 109                 blen = circuit->interface->mtu;
 110         }
 111
 112         readblen = blen;
 113
 114         if (readbuff == NULL)
 115                 readbuff = malloc(blen);
 116
 117         zlog_debug("BPF buffer len = %u", blen);
 118
 119         /*  BPF(4): reads return immediately upon packet reception.
 120          *  Otherwise, a read will block until either the kernel
 121          *  buffer becomes full or a timeout occurs.
 122          */
 123         immediate = 1;
 124         if (ioctl(fd, BIOCIMMEDIATE, (caddr_t)&immediate) < 0) {
 125                 zlog_warn("failed to set BPF dev to immediate mode");
 126         }
 127
 128 #ifdef BIOCSSEESENT
 129         /*
 130          * We want to see only incoming packets
 131          */
 132         seesent = 0;
 133         if (ioctl(fd, BIOCSSEESENT, (caddr_t)&seesent) < 0) {
 134                 zlog_warn("failed to set BPF dev to incoming only mode");
 135         }
 136 #endif
 137
 138         /*
 139          * ...but all of them
 140          */
 141         if (ioctl(fd, BIOCPROMISC) < 0) {
 142                 zlog_warn("failed to set BPF dev to promiscuous mode");
 143         }
 144
 145         /*
 146          * If the buffer length is smaller than our mtu, lets try to increase it
 147          */
 148         if (blen < circuit->interface->mtu) {
 149                 if (ioctl(fd, BIOCSBLEN, &circuit->interface->mtu) < 0) {
 150                         zlog_warn("failed to set BPF buffer len (%u to %u)",
 151                                   blen, circuit->interface->mtu);
 152                 }
 153         }
 154
 155         /*
 156          * Set a timeout parameter - hope this helps select()
 157          */
 158         timeout.tv_sec = 600;
 159         timeout.tv_usec = 0;
 160         if (ioctl(fd, BIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 161                 zlog_warn("failed to set BPF device timeout");
 162         }
 163
 164         /*
 165          * And set the filter
 166          */
 167         memset(&bpf_prog, 0, sizeof(struct bpf_program));
 168         bpf_prog.bf_len = 8;
 169         bpf_prog.bf_insns = &(llcfilter[0]);
 170         if (ioctl(fd, BIOCSETF, (caddr_t)&bpf_prog) < 0) {
 171                 zlog_warn("open_bpf_dev(): failed to install filter: %s",
 172                           safe_strerror(errno));
 173                 return ISIS_WARNING;
 174         }
 175
 176         assert(fd > 0);
 177
 178         circuit->fd = fd;
 179
 180         return ISIS_OK;
 181 }
 182
 183 /*
 184  * Create the socket and set the tx/rx funcs
 185  */
 186 int isis_sock_init(struct isis_circuit *circuit)
 187 {
 188         int retval = ISIS_OK;
 189
 190         if (isisd_privs.change(ZPRIVS_RAISE))
 191                 zlog_err("%s: could not raise privs, %s", __func__,
 192                          safe_strerror(errno));
 193
 194         retval = open_bpf_dev(circuit);
 195
 196         if (retval != ISIS_OK) {
 197                 zlog_warn("%s: could not initialize the socket", __func__);
 198                 goto end;
 199         }
 200
 201         if (if_is_broadcast(circuit->interface)) {
 202                 circuit->tx = isis_send_pdu_bcast;
 203                 circuit->rx = isis_recv_pdu_bcast;
 204         } else {
 205                 zlog_warn("isis_sock_init(): unknown circuit type");
 206                 retval = ISIS_WARNING;
 207                 goto end;
 208         }
 209
 210 end:
 211         if (isisd_privs.change(ZPRIVS_LOWER))
 212                 zlog_err("%s: could not lower privs, %s", __func__,
 213                          safe_strerror(errno));
 214
 215         return retval;
 216 }
 217
 218 int isis_recv_pdu_bcast(struct isis_circuit *circuit, u_char *ssnpa)
 219 {
 220         int bytesread = 0, bytestoread, offset, one = 1;
 221         struct bpf_hdr *bpf_hdr;
 222
 223         assert(circuit->fd > 0);
 224
 225         if (ioctl(circuit->fd, FIONREAD, (caddr_t)&bytestoread) < 0) {
 226                 zlog_warn("ioctl() FIONREAD failed: %s", safe_strerror(errno));
 227         }
 228
 229         if (bytestoread) {
 230                 bytesread = read(circuit->fd, readbuff, readblen);
 231         }
 232         if (bytesread < 0) {
 233                 zlog_warn("isis_recv_pdu_bcast(): read() failed: %s",
 234                           safe_strerror(errno));
 235                 return ISIS_WARNING;
 236         }
 237
 238         if (bytesread == 0)
 239                 return ISIS_WARNING;
 240
 241         bpf_hdr = (struct bpf_hdr *)readbuff;
 242
 243         assert(bpf_hdr->bh_caplen == bpf_hdr->bh_datalen);
 244
 245         offset = bpf_hdr->bh_hdrlen + LLC_LEN + ETH_ALEN;
 246
 247         /* then we lose the BPF, LLC and ethernet headers */
 248         stream_write(circuit->rcv_stream, readbuff + offset,
 249                      bpf_hdr->bh_caplen - LLC_LEN - ETH_ALEN);
 250         stream_set_getp(circuit->rcv_stream, 0);
 251
 252         memcpy(ssnpa, readbuff + bpf_hdr->bh_hdrlen + ETH_ALEN, ETH_ALEN);
 253
 254         if (ioctl(circuit->fd, BIOCFLUSH, &one) < 0)
 255                 zlog_warn("Flushing failed: %s", safe_strerror(errno));
 256
 257         return ISIS_OK;
 258 }
 259
 260 int isis_send_pdu_bcast(struct isis_circuit *circuit, int level)
 261 {
 262         struct ether_header *eth;
 263         ssize_t written;
 264         size_t buflen;
 265
 266         buflen = stream_get_endp(circuit->snd_stream) + LLC_LEN + ETH_ALEN;
 267         if (buflen > sizeof(sock_buff)) {
 268                 zlog_warn(
 269                         "isis_send_pdu_bcast: sock_buff size %zu is less than "
 270                         "output pdu size %zu on circuit %s",
 271                         sizeof(sock_buff), buflen, circuit->interface->name);
 272                 return ISIS_WARNING;
 273         }
 274
 275         stream_set_getp(circuit->snd_stream, 0);
 276
 277         /*
 278          * First the eth header
 279          */
 280         eth = (struct ether_header *)sock_buff;
 281         if (level == 1)
 282                 memcpy(eth->ether_dhost, ALL_L1_ISS, ETH_ALEN);
 283         else
 284                 memcpy(eth->ether_dhost, ALL_L2_ISS, ETH_ALEN);
 285         memcpy(eth->ether_shost, circuit->u.bc.snpa, ETH_ALEN);
 286         size_t frame_size = stream_get_endp(circuit->snd_stream) + LLC_LEN;
 287         eth->ether_type = htons(isis_ethertype(frame_size));
 288
 289         /*
 290          * Then the LLC
 291          */
 292         sock_buff[ETH_ALEN] = ISO_SAP;
 293         sock_buff[ETH_ALEN + 1] = ISO_SAP;
 294         sock_buff[ETH_ALEN + 2] = 0x03;
 295
 296         /* then we copy the data */
 297         memcpy(sock_buff + (LLC_LEN + ETH_ALEN), circuit->snd_stream->data,
 298                stream_get_endp(circuit->snd_stream));
 299
 300         /* now we can send this */
 301         written = write(circuit->fd, sock_buff, buflen);
 302         if (written < 0) {
 303                 zlog_warn("IS-IS bpf: could not transmit packet on %s: %s",
 304                           circuit->interface->name, safe_strerror(errno));
 305                 if (ERRNO_IO_RETRY(errno))
 306                         return ISIS_WARNING;
 307                 return ISIS_ERROR;
 308         }
 309
 310         return ISIS_OK;
 311 }
 312
 313 #endif /* ISIS_METHOD == ISIS_METHOD_BPF */