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 #include "lib_errors.h"
  36
  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 #include "isisd/isis_pdu.h"
  46
  47 #include "privs.h"
  48
  49 struct bpf_insn llcfilter[] = {
  50         BPF_STMT(BPF_LD + BPF_B + BPF_ABS,
  51                  ETHER_HDR_LEN), /* check first byte */
  52         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0, 5),
  53         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETHER_HDR_LEN + 1),
  54         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0,
  55                  3), /* check second byte */
  56         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETHER_HDR_LEN + 2),
  57         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x03, 0, 1), /* check third byte */
  58         BPF_STMT(BPF_RET + BPF_K, (unsigned int)-1),
  59         BPF_STMT(BPF_RET + BPF_K, 0)};
  60 unsigned int readblen = 0;
  61 uint8_t *readbuff = NULL;
  62
  63 /*
  64  * Table 9 - Architectural constants for use with ISO 8802 subnetworks
  65  * ISO 10589 - 8.4.8
  66  */
  67
  68 static const uint8_t ALL_L1_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x14};
  69 static const uint8_t ALL_L2_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x15};
  70 static char sock_buff[16384];
  71
  72 static int open_bpf_dev(struct isis_circuit *circuit)
  73 {
  74         int i = 0, fd;
  75         char bpfdev[128];
  76         struct ifreq ifr;
  77         unsigned int blen, immediate;
  78 #ifdef BIOCSSEESENT
  79         unsigned int seesent;
  80 #endif
  81         struct timeval timeout;
  82         struct bpf_program bpf_prog;
  83
  84         do {
  85                 (void)snprintf(bpfdev, sizeof(bpfdev), "/dev/bpf%d", i++);
  86                 fd = open(bpfdev, O_RDWR);
  87         } while (fd < 0 && errno == EBUSY);
  88
  89         if (fd < 0) {
  90                 zlog_warn("open_bpf_dev(): failed to create bpf socket: %s",
  91                           safe_strerror(errno));
  92                 return ISIS_WARNING;
  93         }
  94
  95         zlog_debug("Opened BPF device %s", bpfdev);
  96
  97         memcpy(ifr.ifr_name, circuit->interface->name, sizeof(ifr.ifr_name));
  98         if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) < 0) {
  99                 zlog_warn("open_bpf_dev(): failed to bind to interface: %s",
 100                           safe_strerror(errno));
 101                 return ISIS_WARNING;
 102         }
 103
 104         if (ioctl(fd, BIOCGBLEN, (caddr_t)&blen) < 0) {
 105                 zlog_warn("failed to get BPF buffer len");
 106                 blen = circuit->interface->mtu;
 107         }
 108
 109         readblen = blen;
 110
 111         if (readbuff == NULL)
 112                 readbuff = malloc(blen);
 113
 114         zlog_debug("BPF buffer len = %u", blen);
 115
 116         /*  BPF(4): reads return immediately upon packet reception.
 117          *  Otherwise, a read will block until either the kernel
 118          *  buffer becomes full or a timeout occurs.
 119          */
 120         immediate = 1;
 121         if (ioctl(fd, BIOCIMMEDIATE, (caddr_t)&immediate) < 0) {
 122                 zlog_warn("failed to set BPF dev to immediate mode");
 123         }
 124
 125 #ifdef BIOCSSEESENT
 126         /*
 127          * We want to see only incoming packets
 128          */
 129         seesent = 0;
 130         if (ioctl(fd, BIOCSSEESENT, (caddr_t)&seesent) < 0) {
 131                 zlog_warn("failed to set BPF dev to incoming only mode");
 132         }
 133 #endif
 134
 135         /*
 136          * ...but all of them
 137          */
 138         if (ioctl(fd, BIOCPROMISC) < 0) {
 139                 zlog_warn("failed to set BPF dev to promiscuous mode");
 140         }
 141
 142         /*
 143          * If the buffer length is smaller than our mtu, lets try to increase it
 144          */
 145         if (blen < circuit->interface->mtu) {
 146                 if (ioctl(fd, BIOCSBLEN, &circuit->interface->mtu) < 0) {
 147                         zlog_warn("failed to set BPF buffer len (%u to %u)",
 148                                   blen, circuit->interface->mtu);
 149                 }
 150         }
 151
 152         /*
 153          * Set a timeout parameter - hope this helps select()
 154          */
 155         timeout.tv_sec = 600;
 156         timeout.tv_usec = 0;
 157         if (ioctl(fd, BIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 158                 zlog_warn("failed to set BPF device timeout");
 159         }
 160
 161         /*
 162          * And set the filter
 163          */
 164         memset(&bpf_prog, 0, sizeof(bpf_prog));
 165         bpf_prog.bf_len = 8;
 166         bpf_prog.bf_insns = &(llcfilter[0]);
 167         if (ioctl(fd, BIOCSETF, (caddr_t)&bpf_prog) < 0) {
 168                 zlog_warn("%s: failed to install filter: %s", __func__,
 169                           safe_strerror(errno));
 170                 return ISIS_WARNING;
 171         }
 172
 173         assert(fd > 0);
 174
 175         circuit->fd = fd;
 176
 177         return ISIS_OK;
 178 }
 179
 180 /*
 181  * Create the socket and set the tx/rx funcs
 182  */
 183 int isis_sock_init(struct isis_circuit *circuit)
 184 {
 185         int retval = ISIS_OK;
 186
 187         frr_with_privs(&isisd_privs) {
 188
 189                 retval = open_bpf_dev(circuit);
 190
 191                 if (retval != ISIS_OK) {
 192                         zlog_warn("%s: could not initialize the socket",
 193                                   __func__);
 194                         break;
 195                 }
 196
 197                 if (if_is_broadcast(circuit->interface)) {
 198                         circuit->tx = isis_send_pdu_bcast;
 199                         circuit->rx = isis_recv_pdu_bcast;
 200                 } else {
 201                         zlog_warn("%s: unknown circuit type", __func__);
 202                         retval = ISIS_WARNING;
 203                         break;
 204                 }
 205         }
 206
 207         return retval;
 208 }
 209
 210 int isis_recv_pdu_bcast(struct isis_circuit *circuit, uint8_t *ssnpa)
 211 {
 212         int bytesread = 0, bytestoread = 0, offset, one = 1;
 213         uint8_t *buff_ptr;
 214         struct bpf_hdr *bpf_hdr;
 215
 216         assert(circuit->fd > 0);
 217
 218         if (ioctl(circuit->fd, FIONREAD, (caddr_t)&bytestoread) < 0) {
 219                 zlog_warn("ioctl() FIONREAD failed: %s", safe_strerror(errno));
 220         }
 221
 222         if (bytestoread) {
 223                 bytesread = read(circuit->fd, readbuff, readblen);
 224         }
 225         if (bytesread < 0) {
 226                 zlog_warn("%s: read() failed: %s", __func__,
 227                           safe_strerror(errno));
 228                 return ISIS_WARNING;
 229         }
 230
 231         if (bytesread == 0)
 232                 return ISIS_WARNING;
 233
 234         buff_ptr = readbuff;
 235         while (buff_ptr < readbuff + bytesread) {
 236                 bpf_hdr = (struct bpf_hdr *) buff_ptr;
 237                 assert(bpf_hdr->bh_caplen == bpf_hdr->bh_datalen);
 238                 offset = bpf_hdr->bh_hdrlen + LLC_LEN + ETHER_HDR_LEN;
 239
 240                 /* then we lose the BPF, LLC and ethernet headers */
 241                 stream_write(circuit->rcv_stream, buff_ptr + offset,
 242                              bpf_hdr->bh_caplen - LLC_LEN - ETHER_HDR_LEN);
 243                 stream_set_getp(circuit->rcv_stream, 0);
 244
 245                 memcpy(ssnpa, buff_ptr + bpf_hdr->bh_hdrlen + ETHER_ADDR_LEN,
 246                 ETHER_ADDR_LEN);
 247
 248                 isis_handle_pdu(circuit, ssnpa);
 249                 stream_reset(circuit->rcv_stream);
 250                 buff_ptr += BPF_WORDALIGN(bpf_hdr->bh_hdrlen +
 251                                                 bpf_hdr->bh_datalen);
 252         }
 253
 254
 255         if (ioctl(circuit->fd, BIOCFLUSH, &one) < 0)
 256                 zlog_warn("Flushing failed: %s", safe_strerror(errno));
 257
 258         return ISIS_OK;
 259 }
 260
 261 int isis_send_pdu_bcast(struct isis_circuit *circuit, int level)
 262 {
 263         struct ether_header *eth;
 264         ssize_t written;
 265         size_t buflen;
 266
 267         buflen = stream_get_endp(circuit->snd_stream) + LLC_LEN + ETHER_HDR_LEN;
 268         if (buflen > sizeof(sock_buff)) {
 269                 zlog_warn(
 270                         "%s: sock_buff size %zu is less than output pdu size %zu on circuit %s",
 271                         __func__, sizeof(sock_buff), buflen,
 272                         circuit->interface->name);
 273                 return ISIS_WARNING;
 274         }
 275
 276         stream_set_getp(circuit->snd_stream, 0);
 277
 278         /*
 279          * First the eth header
 280          */
 281         eth = (struct ether_header *)sock_buff;
 282         if (level == 1)
 283                 memcpy(eth->ether_dhost, ALL_L1_ISS, ETH_ALEN);
 284         else
 285                 memcpy(eth->ether_dhost, ALL_L2_ISS, ETH_ALEN);
 286         memcpy(eth->ether_shost, circuit->u.bc.snpa, ETH_ALEN);
 287         size_t frame_size = stream_get_endp(circuit->snd_stream) + LLC_LEN;
 288         eth->ether_type = htons(isis_ethertype(frame_size));
 289
 290         /*
 291          * Then the LLC
 292          */
 293         sock_buff[ETHER_HDR_LEN] = ISO_SAP;
 294         sock_buff[ETHER_HDR_LEN + 1] = ISO_SAP;
 295         sock_buff[ETHER_HDR_LEN + 2] = 0x03;
 296
 297         /* then we copy the data */
 298         memcpy(sock_buff + (LLC_LEN + ETHER_HDR_LEN), circuit->snd_stream->data,
 299                stream_get_endp(circuit->snd_stream));
 300
 301         /* now we can send this */
 302         written = write(circuit->fd, sock_buff, buflen);
 303         if (written < 0) {
 304                 zlog_warn("IS-IS bpf: could not transmit packet on %s: %s",
 305                           circuit->interface->name, safe_strerror(errno));
 306                 if (ERRNO_IO_RETRY(errno))
 307                         return ISIS_WARNING;
 308                 return ISIS_ERROR;
 309         }
 310
 311         return ISIS_OK;
 312 }
 313
 314 #endif /* ISIS_METHOD == ISIS_METHOD_BPF */