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/dict.h"
  38 #include "isisd/isis_constants.h"
  39 #include "isisd/isis_common.h"
  40 #include "isisd/isis_circuit.h"
  41 #include "isisd/isis_flags.h"
  42 #include "isisd/isisd.h"
  43 #include "isisd/isis_constants.h"
  44 #include "isisd/isis_circuit.h"
  45 #include "isisd/isis_network.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 uint8_t ALL_L1_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x14};
  69 uint8_t ALL_L2_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x15};
  70 uint8_t ALL_ISS[6] = {0x09, 0x00, 0x2B, 0x00, 0x00, 0x05};
  71 uint8_t 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         unsigned int blen, immediate;
  81 #ifdef BIOCSSEESENT
  82         unsigned 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         frr_elevate_privs(&isisd_privs) {
 191
 192                 retval = open_bpf_dev(circuit);
 193
 194                 if (retval != ISIS_OK) {
 195                         zlog_warn("%s: could not initialize the socket",
 196                                   __func__);
 197                         break;
 198                 }
 199
 200                 if (if_is_broadcast(circuit->interface)) {
 201                         circuit->tx = isis_send_pdu_bcast;
 202                         circuit->rx = isis_recv_pdu_bcast;
 203                 } else {
 204                         zlog_warn("isis_sock_init(): unknown circuit type");
 205                         retval = ISIS_WARNING;
 206                         break;
 207                 }
 208         }
 209
 210         return retval;
 211 }
 212
 213 int isis_recv_pdu_bcast(struct isis_circuit *circuit, uint8_t *ssnpa)
 214 {
 215         int bytesread = 0, bytestoread, offset, one = 1, err = ISIS_OK;
 216         uint8_t *buff_ptr;
 217         struct bpf_hdr *bpf_hdr;
 218
 219         assert(circuit->fd > 0);
 220
 221         if (ioctl(circuit->fd, FIONREAD, (caddr_t)&bytestoread) < 0) {
 222                 zlog_warn("ioctl() FIONREAD failed: %s", safe_strerror(errno));
 223         }
 224
 225         if (bytestoread) {
 226                 bytesread = read(circuit->fd, readbuff, readblen);
 227         }
 228         if (bytesread < 0) {
 229                 zlog_warn("isis_recv_pdu_bcast(): read() failed: %s",
 230                                 safe_strerror(errno));
 231                 return ISIS_WARNING;
 232         }
 233
 234         if (bytesread == 0)
 235                 return ISIS_WARNING;
 236
 237         buff_ptr = readbuff;
 238         while (buff_ptr < readbuff + bytesread) {
 239                 bpf_hdr = (struct bpf_hdr *) buff_ptr;
 240                 assert(bpf_hdr->bh_caplen == bpf_hdr->bh_datalen);
 241                 offset = bpf_hdr->bh_hdrlen + LLC_LEN + ETHER_HDR_LEN;
 242
 243                 /* then we lose the BPF, LLC and ethernet headers */
 244                 stream_write(circuit->rcv_stream, buff_ptr + offset,
 245                              bpf_hdr->bh_caplen - LLC_LEN - ETHER_HDR_LEN);
 246                 stream_set_getp(circuit->rcv_stream, 0);
 247
 248                 memcpy(ssnpa, buff_ptr + bpf_hdr->bh_hdrlen + ETHER_ADDR_LEN,
 249                 ETHER_ADDR_LEN);
 250
 251                 err = isis_handle_pdu(circuit, ssnpa);
 252                 stream_reset(circuit->rcv_stream);
 253                 buff_ptr += BPF_WORDALIGN(bpf_hdr->bh_hdrlen +
 254                                                 bpf_hdr->bh_datalen);
 255         }
 256
 257
 258         if (ioctl(circuit->fd, BIOCFLUSH, &one) < 0)
 259                 zlog_warn("Flushing failed: %s", safe_strerror(errno));
 260
 261         return ISIS_OK;
 262 }
 263
 264 int isis_send_pdu_bcast(struct isis_circuit *circuit, int level)
 265 {
 266         struct ether_header *eth;
 267         ssize_t written;
 268         size_t buflen;
 269
 270         buflen = stream_get_endp(circuit->snd_stream) + LLC_LEN + ETHER_HDR_LEN;
 271         if (buflen > sizeof(sock_buff)) {
 272                 zlog_warn(
 273                         "isis_send_pdu_bcast: sock_buff size %zu is less than "
 274                         "output pdu size %zu on circuit %s",
 275                         sizeof(sock_buff), buflen, circuit->interface->name);
 276                 return ISIS_WARNING;
 277         }
 278
 279         stream_set_getp(circuit->snd_stream, 0);
 280
 281         /*
 282          * First the eth header
 283          */
 284         eth = (struct ether_header *)sock_buff;
 285         if (level == 1)
 286                 memcpy(eth->ether_dhost, ALL_L1_ISS, ETH_ALEN);
 287         else
 288                 memcpy(eth->ether_dhost, ALL_L2_ISS, ETH_ALEN);
 289         memcpy(eth->ether_shost, circuit->u.bc.snpa, ETH_ALEN);
 290         size_t frame_size = stream_get_endp(circuit->snd_stream) + LLC_LEN;
 291         eth->ether_type = htons(isis_ethertype(frame_size));
 292
 293         /*
 294          * Then the LLC
 295          */
 296         sock_buff[ETHER_HDR_LEN] = ISO_SAP;
 297         sock_buff[ETHER_HDR_LEN + 1] = ISO_SAP;
 298         sock_buff[ETHER_HDR_LEN + 2] = 0x03;
 299
 300         /* then we copy the data */
 301         memcpy(sock_buff + (LLC_LEN + ETHER_HDR_LEN), circuit->snd_stream->data,
 302                stream_get_endp(circuit->snd_stream));
 303
 304         /* now we can send this */
 305         written = write(circuit->fd, sock_buff, buflen);
 306         if (written < 0) {
 307                 zlog_warn("IS-IS bpf: could not transmit packet on %s: %s",
 308                           circuit->interface->name, safe_strerror(errno));
 309                 if (ERRNO_IO_RETRY(errno))
 310                         return ISIS_WARNING;
 311                 return ISIS_ERROR;
 312         }
 313
 314         return ISIS_OK;
 315 }
 316
 317 #endif /* ISIS_METHOD == ISIS_METHOD_BPF */