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         BPF_STMT(BPF_LD + BPF_B + BPF_ABS,
  50                  ETHER_HDR_LEN), /* check first byte */
  51         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0, 5),
  52         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETHER_HDR_LEN + 1),
  53         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ISO_SAP, 0,
  54                  3), /* check second byte */
  55         BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ETHER_HDR_LEN + 2),
  56         BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x03, 0, 1), /* check third byte */
  57         BPF_STMT(BPF_RET + BPF_K, (unsigned int)-1),
  58         BPF_STMT(BPF_RET + BPF_K, 0)};
  59 unsigned int readblen = 0;
  60 uint8_t *readbuff = NULL;
  61
  62 /*
  63  * Table 9 - Architectural constants for use with ISO 8802 subnetworks
  64  * ISO 10589 - 8.4.8
  65  */
  66
  67 uint8_t ALL_L1_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x14};
  68 uint8_t ALL_L2_ISS[6] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x15};
  69 uint8_t ALL_ISS[6] = {0x09, 0x00, 0x2B, 0x00, 0x00, 0x05};
  70 uint8_t ALL_ESS[6] = {0x09, 0x00, 0x2B, 0x00, 0x00, 0x04};
  71
  72 static char sock_buff[8192];
  73
  74 static int open_bpf_dev(struct isis_circuit *circuit)
  75 {
  76         int i = 0, fd;
  77         char bpfdev[128];
  78         struct ifreq ifr;
  79         unsigned int blen, immediate;
  80 #ifdef BIOCSSEESENT
  81         unsigned int seesent;
  82 #endif
  83         struct timeval timeout;
  84         struct bpf_program bpf_prog;
  85
  86         do {
  87                 (void)snprintf(bpfdev, sizeof(bpfdev), "/dev/bpf%d", i++);
  88                 fd = open(bpfdev, O_RDWR);
  89         } while (fd < 0 && errno == EBUSY);
  90
  91         if (fd < 0) {
  92                 zlog_warn("open_bpf_dev(): failed to create bpf socket: %s",
  93                           safe_strerror(errno));
  94                 return ISIS_WARNING;
  95         }
  96
  97         zlog_debug("Opened BPF device %s", bpfdev);
  98
  99         memcpy(ifr.ifr_name, circuit->interface->name, sizeof(ifr.ifr_name));
 100         if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) < 0) {
 101                 zlog_warn("open_bpf_dev(): failed to bind to interface: %s",
 102                           safe_strerror(errno));
 103                 return ISIS_WARNING;
 104         }
 105
 106         if (ioctl(fd, BIOCGBLEN, (caddr_t)&blen) < 0) {
 107                 zlog_warn("failed to get BPF buffer len");
 108                 blen = circuit->interface->mtu;
 109         }
 110
 111         readblen = blen;
 112
 113         if (readbuff == NULL)
 114                 readbuff = malloc(blen);
 115
 116         zlog_debug("BPF buffer len = %u", blen);
 117
 118         /*  BPF(4): reads return immediately upon packet reception.
 119          *  Otherwise, a read will block until either the kernel
 120          *  buffer becomes full or a timeout occurs.
 121          */
 122         immediate = 1;
 123         if (ioctl(fd, BIOCIMMEDIATE, (caddr_t)&immediate) < 0) {
 124                 zlog_warn("failed to set BPF dev to immediate mode");
 125         }
 126
 127 #ifdef BIOCSSEESENT
 128         /*
 129          * We want to see only incoming packets
 130          */
 131         seesent = 0;
 132         if (ioctl(fd, BIOCSSEESENT, (caddr_t)&seesent) < 0) {
 133                 zlog_warn("failed to set BPF dev to incoming only mode");
 134         }
 135 #endif
 136
 137         /*
 138          * ...but all of them
 139          */
 140         if (ioctl(fd, BIOCPROMISC) < 0) {
 141                 zlog_warn("failed to set BPF dev to promiscuous mode");
 142         }
 143
 144         /*
 145          * If the buffer length is smaller than our mtu, lets try to increase it
 146          */
 147         if (blen < circuit->interface->mtu) {
 148                 if (ioctl(fd, BIOCSBLEN, &circuit->interface->mtu) < 0) {
 149                         zlog_warn("failed to set BPF buffer len (%u to %u)",
 150                                   blen, circuit->interface->mtu);
 151                 }
 152         }
 153
 154         /*
 155          * Set a timeout parameter - hope this helps select()
 156          */
 157         timeout.tv_sec = 600;
 158         timeout.tv_usec = 0;
 159         if (ioctl(fd, BIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 160                 zlog_warn("failed to set BPF device timeout");
 161         }
 162
 163         /*
 164          * And set the filter
 165          */
 166         memset(&bpf_prog, 0, sizeof(struct bpf_program));
 167         bpf_prog.bf_len = 8;
 168         bpf_prog.bf_insns = &(llcfilter[0]);
 169         if (ioctl(fd, BIOCSETF, (caddr_t)&bpf_prog) < 0) {
 170                 zlog_warn("open_bpf_dev(): failed to install filter: %s",
 171                           safe_strerror(errno));
 172                 return ISIS_WARNING;
 173         }
 174
 175         assert(fd > 0);
 176
 177         circuit->fd = fd;
 178
 179         return ISIS_OK;
 180 }
 181
 182 /*
 183  * Create the socket and set the tx/rx funcs
 184  */
 185 int isis_sock_init(struct isis_circuit *circuit)
 186 {
 187         int retval = ISIS_OK;
 188
 189         if (isisd_privs.change(ZPRIVS_RAISE))
 190                 zlog_err("%s: could not raise privs, %s", __func__,
 191                          safe_strerror(errno));
 192
 193         retval = open_bpf_dev(circuit);
 194
 195         if (retval != ISIS_OK) {
 196                 zlog_warn("%s: could not initialize the socket", __func__);
 197                 goto end;
 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                 goto end;
 207         }
 208
 209 end:
 210         if (isisd_privs.change(ZPRIVS_LOWER))
 211                 zlog_err("%s: could not lower privs, %s", __func__,
 212                          safe_strerror(errno));
 213
 214         return retval;
 215 }
 216
 217 int isis_recv_pdu_bcast(struct isis_circuit *circuit, uint8_t *ssnpa)
 218 {
 219         int bytesread = 0, bytestoread, offset, one = 1, err = ISIS_OK;
 220         uint8_t *buff_ptr;
 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         buff_ptr = readbuff;
 242         while (buff_ptr < readbuff + bytesread) {
 243                 bpf_hdr = (struct bpf_hdr *) buff_ptr;
 244                 assert(bpf_hdr->bh_caplen == bpf_hdr->bh_datalen);
 245                 offset = bpf_hdr->bh_hdrlen + LLC_LEN + ETHER_HDR_LEN;
 246
 247                 /* then we lose the BPF, LLC and ethernet headers */
 248                 stream_write(circuit->rcv_stream, buff_ptr + offset,
 249                              bpf_hdr->bh_caplen - LLC_LEN - ETHER_HDR_LEN);
 250                 stream_set_getp(circuit->rcv_stream, 0);
 251
 252                 memcpy(ssnpa, buff_ptr + bpf_hdr->bh_hdrlen + ETHER_ADDR_LEN,
 253                 ETHER_ADDR_LEN);
 254
 255                 err = isis_handle_pdu(circuit, ssnpa);
 256                 stream_reset(circuit->rcv_stream);
 257                 buff_ptr += BPF_WORDALIGN(bpf_hdr->bh_hdrlen +
 258                                                 bpf_hdr->bh_datalen);
 259         }
 260
 261
 262         if (ioctl(circuit->fd, BIOCFLUSH, &one) < 0)
 263                 zlog_warn("Flushing failed: %s", safe_strerror(errno));
 264
 265         return ISIS_OK;
 266 }
 267
 268 int isis_send_pdu_bcast(struct isis_circuit *circuit, int level)
 269 {
 270         struct ether_header *eth;
 271         ssize_t written;
 272         size_t buflen;
 273
 274         buflen = stream_get_endp(circuit->snd_stream) + LLC_LEN + ETHER_HDR_LEN;
 275         if (buflen > sizeof(sock_buff)) {
 276                 zlog_warn(
 277                         "isis_send_pdu_bcast: sock_buff size %zu is less than "
 278                         "output pdu size %zu on circuit %s",
 279                         sizeof(sock_buff), buflen, circuit->interface->name);
 280                 return ISIS_WARNING;
 281         }
 282
 283         stream_set_getp(circuit->snd_stream, 0);
 284
 285         /*
 286          * First the eth header
 287          */
 288         eth = (struct ether_header *)sock_buff;
 289         if (level == 1)
 290                 memcpy(eth->ether_dhost, ALL_L1_ISS, ETH_ALEN);
 291         else
 292                 memcpy(eth->ether_dhost, ALL_L2_ISS, ETH_ALEN);
 293         memcpy(eth->ether_shost, circuit->u.bc.snpa, ETH_ALEN);
 294         size_t frame_size = stream_get_endp(circuit->snd_stream) + LLC_LEN;
 295         eth->ether_type = htons(isis_ethertype(frame_size));
 296
 297         /*
 298          * Then the LLC
 299          */
 300         sock_buff[ETHER_HDR_LEN] = ISO_SAP;
 301         sock_buff[ETHER_HDR_LEN + 1] = ISO_SAP;
 302         sock_buff[ETHER_HDR_LEN + 2] = 0x03;
 303
 304         /* then we copy the data */
 305         memcpy(sock_buff + (LLC_LEN + ETHER_HDR_LEN), circuit->snd_stream->data,
 306                stream_get_endp(circuit->snd_stream));
 307
 308         /* now we can send this */
 309         written = write(circuit->fd, sock_buff, buflen);
 310         if (written < 0) {
 311                 zlog_warn("IS-IS bpf: could not transmit packet on %s: %s",
 312                           circuit->interface->name, safe_strerror(errno));
 313                 if (ERRNO_IO_RETRY(errno))
 314                         return ISIS_WARNING;
 315                 return ISIS_ERROR;
 316         }
 317
 318         return ISIS_OK;
 319 }
 320
 321 #endif /* ISIS_METHOD == ISIS_METHOD_BPF */