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 "math.h"
  22
  23 #include <zebra.h>
  24 #include "prefix.h"
  25
  26 #include "bgpd/bgpd.h"
  27 #include "bgpd/bgp_route.h"
  28 #include "bgpd/bgp_flowspec.h"
  29 #include "bgpd/bgp_flowspec_util.h"
  30 #include "bgpd/bgp_flowspec_private.h"
  31 #include "bgpd/bgp_ecommunity.h"
  32 #include "bgpd/bgp_debug.h"
  33
  34 static int bgp_fs_nlri_validate(uint8_t *nlri_content, uint32_t len)
  35 {
  36         uint32_t offset = 0;
  37         int type;
  38         int ret = 0, error = 0;
  39
  40         while (offset < len-1) {
  41                 type = nlri_content[offset];
  42                 offset++;
  43                 switch (type) {
  44                 case FLOWSPEC_DEST_PREFIX:
  45                 case FLOWSPEC_SRC_PREFIX:
  46                         ret = bgp_flowspec_ip_address(
  47                                                 BGP_FLOWSPEC_VALIDATE_ONLY,
  48                                                 nlri_content + offset,
  49                                                 len - offset, NULL, &error);
  50                         break;
  51                 case FLOWSPEC_IP_PROTOCOL:
  52                 case FLOWSPEC_PORT:
  53                 case FLOWSPEC_DEST_PORT:
  54                 case FLOWSPEC_SRC_PORT:
  55                 case FLOWSPEC_ICMP_TYPE:
  56                 case FLOWSPEC_ICMP_CODE:
  57                         ret = bgp_flowspec_op_decode(BGP_FLOWSPEC_VALIDATE_ONLY,
  58                                                    nlri_content + offset,
  59                                                    len - offset, NULL, &error);
  60                         break;
  61                 case FLOWSPEC_TCP_FLAGS:
  62                 case FLOWSPEC_FRAGMENT:
  63                         ret = bgp_flowspec_bitmask_decode(
  64                                                    BGP_FLOWSPEC_VALIDATE_ONLY,
  65                                                    nlri_content + offset,
  66                                                    len - offset, NULL, &error);
  67                         break;
  68                 case FLOWSPEC_PKT_LEN:
  69                 case FLOWSPEC_DSCP:
  70                         ret = bgp_flowspec_op_decode(
  71                                                 BGP_FLOWSPEC_VALIDATE_ONLY,
  72                                                 nlri_content + offset,
  73                                                 len - offset, NULL, &error);
  74                         break;
  75                 default:
  76                         error = -1;
  77                         break;
  78                 }
  79                 offset += ret;
  80                 if (error < 0)
  81                         break;
  82         }
  83         return error;
  84 }
  85
  86 int bgp_nlri_parse_flowspec(struct peer *peer, struct attr *attr,
  87                             struct bgp_nlri *packet, int withdraw)
  88 {
  89         uint8_t *pnt;
  90         uint8_t *lim;
  91         afi_t afi;
  92         safi_t safi;
  93         int psize = 0;
  94         struct prefix p;
  95         int ret;
  96         void *temp;
  97
  98         /* Start processing the NLRI - there may be multiple in the MP_REACH */
  99         pnt = packet->nlri;
 100         lim = pnt + packet->length;
 101         afi = packet->afi;
 102         safi = packet->safi;
 103
 104         if (afi == AFI_IP6) {
 105                 zlog_err("BGP flowspec IPv6 not supported");
 106                 return -1;
 107         }
 108
 109         if (packet->length >= FLOWSPEC_NLRI_SIZELIMIT) {
 110                 zlog_err("BGP flowspec nlri length maximum reached (%u)",
 111                          packet->length);
 112                 return -1;
 113         }
 114
 115         for (; pnt < lim; pnt += psize) {
 116                 /* Clear prefix structure. */
 117                 memset(&p, 0, sizeof(struct prefix));
 118
 119                 /* All FlowSpec NLRI begin with length. */
 120                 if (pnt + 1 > lim)
 121                         return -1;
 122
 123                 psize = *pnt++;
 124
 125                 /* When packet overflow occur return immediately. */
 126                 if (pnt + psize > lim) {
 127                         zlog_err("Flowspec NLRI length inconsistent ( size %u seen)",
 128                                  psize);
 129                         return -1;
 130                 }
 131                 if (bgp_fs_nlri_validate(pnt, psize) < 0) {
 132                         zlog_err("Bad flowspec format or NLRI options not supported");
 133                         return -1;
 134                 }
 135                 p.family = AF_FLOWSPEC;
 136                 p.prefixlen = 0;
 137                 /* Flowspec encoding is in bytes */
 138                 p.u.prefix_flowspec.prefixlen = psize;
 139                 temp = XCALLOC(MTYPE_TMP, psize);
 140                 memcpy(temp, pnt, psize);
 141                 p.u.prefix_flowspec.ptr = (uintptr_t) temp;
 142
 143                 if (BGP_DEBUG(flowspec, FLOWSPEC)) {
 144                         char return_string[BGP_FLOWSPEC_NLRI_STRING_MAX];
 145                         char local_string[BGP_FLOWSPEC_NLRI_STRING_MAX * 2];
 146                         char ec_string[BGP_FLOWSPEC_NLRI_STRING_MAX];
 147                         char *s = NULL;
 148
 149                         bgp_fs_nlri_get_string((unsigned char *)
 150                                                p.u.prefix_flowspec.ptr,
 151                                                p.u.prefix_flowspec.prefixlen,
 152                                                return_string,
 153                                                NLRI_STRING_FORMAT_MIN, NULL);
 154                         snprintf(ec_string, sizeof(ec_string),
 155                                  "EC{none}");
 156                         if (attr && attr->ecommunity) {
 157                                 s = ecommunity_ecom2str(attr->ecommunity,
 158                                                 ECOMMUNITY_FORMAT_ROUTE_MAP, 0);
 159                                 snprintf(ec_string, sizeof(ec_string),
 160                                          "EC{%s}",
 161                                         s == NULL ? "none" : s);
 162
 163                                 if (s)
 164                                         ecommunity_strfree(&s);
 165                         }
 166                         snprintf(local_string, sizeof(local_string),
 167                                  "FS Rx %s %s %s %s", withdraw ?
 168                                  "Withdraw":"Update",
 169                                  afi2str(afi), return_string,
 170                                  attr != NULL ? ec_string : "");
 171                         zlog_info("%s", local_string);
 172                 }
 173                 /* Process the route. */
 174                 if (!withdraw)
 175                         ret = bgp_update(peer, &p, 0, attr,
 176                                          afi, safi,
 177                                          ZEBRA_ROUTE_BGP, BGP_ROUTE_NORMAL,
 178                                          NULL, NULL, 0, 0, NULL);
 179                 else
 180                         ret = bgp_withdraw(peer, &p, 0, attr,
 181                                            afi, safi,
 182                                            ZEBRA_ROUTE_BGP, BGP_ROUTE_NORMAL,
 183                                            NULL, NULL, 0, NULL);
 184                 if (ret) {
 185                         zlog_err("Flowspec NLRI failed to be %s.",
 186                                  attr ? "added" : "withdrawn");
 187                         return -1;
 188                 }
 189         }
 190         return 0;
 191 }