bgpd/bgp_flowspec.c

   1 /* BGP FlowSpec for packet handling
   2  * Portions:
   3  *     Copyright (C) 2017 ChinaTelecom SDN Group
   4  *     Copyright (C) 2018 6WIND
   5  *
   6  * FRRouting is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * FRRouting is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include <zebra.h>
  22 #include <math.h>
  23
  24 #include "prefix.h"
  25 #include "lib_errors.h"
  26
  27 #include "bgpd/bgpd.h"
  28 #include "bgpd/bgp_route.h"
  29 #include "bgpd/bgp_flowspec.h"
  30 #include "bgpd/bgp_flowspec_util.h"
  31 #include "bgpd/bgp_flowspec_private.h"
  32 #include "bgpd/bgp_ecommunity.h"
  33 #include "bgpd/bgp_debug.h"
  34 #include "bgpd/bgp_errors.h"
  35
  36 static int bgp_fs_nlri_validate(uint8_t *nlri_content, uint32_t len)
  37 {
  38         uint32_t offset = 0;
  39         int type;
  40         int ret = 0, error = 0;
  41
  42         while (offset < len-1) {
  43                 type = nlri_content[offset];
  44                 offset++;
  45                 switch (type) {
  46                 case FLOWSPEC_DEST_PREFIX:
  47                 case FLOWSPEC_SRC_PREFIX:
  48                         ret = bgp_flowspec_ip_address(
  49                                                 BGP_FLOWSPEC_VALIDATE_ONLY,
  50                                                 nlri_content + offset,
  51                                                 len - offset, NULL, &error);
  52                         break;
  53                 case FLOWSPEC_IP_PROTOCOL:
  54                 case FLOWSPEC_PORT:
  55                 case FLOWSPEC_DEST_PORT:
  56                 case FLOWSPEC_SRC_PORT:
  57                 case FLOWSPEC_ICMP_TYPE:
  58                 case FLOWSPEC_ICMP_CODE:
  59                         ret = bgp_flowspec_op_decode(BGP_FLOWSPEC_VALIDATE_ONLY,
  60                                                    nlri_content + offset,
  61                                                    len - offset, NULL, &error);
  62                         break;
  63                 case FLOWSPEC_TCP_FLAGS:
  64                 case FLOWSPEC_FRAGMENT:
  65                         ret = bgp_flowspec_bitmask_decode(
  66                                                    BGP_FLOWSPEC_VALIDATE_ONLY,
  67                                                    nlri_content + offset,
  68                                                    len - offset, NULL, &error);
  69                         break;
  70                 case FLOWSPEC_PKT_LEN:
  71                 case FLOWSPEC_DSCP:
  72                         ret = bgp_flowspec_op_decode(
  73                                                 BGP_FLOWSPEC_VALIDATE_ONLY,
  74                                                 nlri_content + offset,
  75                                                 len - offset, NULL, &error);
  76                         break;
  77                 default:
  78                         error = -1;
  79                         break;
  80                 }
  81                 offset += ret;
  82                 if (error < 0)
  83                         break;
  84         }
  85         return error;
  86 }
  87
  88 int bgp_nlri_parse_flowspec(struct peer *peer, struct attr *attr,
  89                             struct bgp_nlri *packet, int withdraw)
  90 {
  91         uint8_t *pnt;
  92         uint8_t *lim;
  93         afi_t afi;
  94         safi_t safi;
  95         int psize = 0;
  96         struct prefix p;
  97         int ret;
  98         void *temp;
  99
 100         /* Start processing the NLRI - there may be multiple in the MP_REACH */
 101         pnt = packet->nlri;
 102         lim = pnt + packet->length;
 103         afi = packet->afi;
 104         safi = packet->safi;
 105
 106         if (afi == AFI_IP6) {
 107                 flog_err(EC_LIB_DEVELOPMENT, "BGP flowspec IPv6 not supported");
 108                 return -1;
 109         }
 110
 111         if (packet->length >= FLOWSPEC_NLRI_SIZELIMIT) {
 112                 flog_err(EC_BGP_FLOWSPEC_PACKET,
 113                          "BGP flowspec nlri length maximum reached (%u)",
 114                          packet->length);
 115                 return -1;
 116         }
 117
 118         for (; pnt < lim; pnt += psize) {
 119                 /* Clear prefix structure. */
 120                 memset(&p, 0, sizeof(struct prefix));
 121
 122                 /* All FlowSpec NLRI begin with length. */
 123                 if (pnt + 1 > lim)
 124                         return -1;
 125
 126                 psize = *pnt++;
 127
 128                 /* When packet overflow occur return immediately. */
 129                 if (pnt + psize > lim) {
 130                         flog_err(
 131                                 EC_BGP_FLOWSPEC_PACKET,
 132                                 "Flowspec NLRI length inconsistent ( size %u seen)",
 133                                 psize);
 134                         return -1;
 135                 }
 136                 if (bgp_fs_nlri_validate(pnt, psize) < 0) {
 137                         flog_err(
 138                                 EC_BGP_FLOWSPEC_PACKET,
 139                                 "Bad flowspec format or NLRI options not supported");
 140                         return -1;
 141                 }
 142                 p.family = AF_FLOWSPEC;
 143                 p.prefixlen = 0;
 144                 /* Flowspec encoding is in bytes */
 145                 p.u.prefix_flowspec.prefixlen = psize;
 146                 temp = XCALLOC(MTYPE_TMP, psize);
 147                 memcpy(temp, pnt, psize);
 148                 p.u.prefix_flowspec.ptr = (uintptr_t) temp;
 149
 150                 if (BGP_DEBUG(flowspec, FLOWSPEC)) {
 151                         char return_string[BGP_FLOWSPEC_NLRI_STRING_MAX];
 152                         char local_string[BGP_FLOWSPEC_NLRI_STRING_MAX*2+16];
 153                         char ec_string[BGP_FLOWSPEC_NLRI_STRING_MAX];
 154                         char *s = NULL;
 155
 156                         bgp_fs_nlri_get_string((unsigned char *)
 157                                                p.u.prefix_flowspec.ptr,
 158                                                p.u.prefix_flowspec.prefixlen,
 159                                                return_string,
 160                                                NLRI_STRING_FORMAT_MIN, NULL);
 161                         snprintf(ec_string, sizeof(ec_string),
 162                                  "EC{none}");
 163                         if (attr && attr->ecommunity) {
 164                                 s = ecommunity_ecom2str(attr->ecommunity,
 165                                                 ECOMMUNITY_FORMAT_ROUTE_MAP, 0);
 166                                 snprintf(ec_string, sizeof(ec_string),
 167                                          "EC{%s}",
 168                                         s == NULL ? "none" : s);
 169
 170                                 if (s)
 171                                         ecommunity_strfree(&s);
 172                         }
 173                         snprintf(local_string, sizeof(local_string),
 174                                  "FS Rx %s %s %s %s", withdraw ?
 175                                  "Withdraw":"Update",
 176                                  afi2str(afi), return_string,
 177                                  attr != NULL ? ec_string : "");
 178                         zlog_info("%s", local_string);
 179                 }
 180                 /* Process the route. */
 181                 if (!withdraw)
 182                         ret = bgp_update(peer, &p, 0, attr,
 183                                          afi, safi,
 184                                          ZEBRA_ROUTE_BGP, BGP_ROUTE_NORMAL,
 185                                          NULL, NULL, 0, 0, NULL);
 186                 else
 187                         ret = bgp_withdraw(peer, &p, 0, attr,
 188                                            afi, safi,
 189                                            ZEBRA_ROUTE_BGP, BGP_ROUTE_NORMAL,
 190                                            NULL, NULL, 0, NULL);
 191                 if (ret) {
 192                         flog_err(EC_BGP_FLOWSPEC_INSTALLATION,
 193                                  "Flowspec NLRI failed to be %s.",
 194                                  attr ? "added" : "withdrawn");
 195                         return -1;
 196                 }
 197         }
 198         return 0;
 199 }