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                                 afi_t afi)
  38 {
  39         uint32_t offset = 0;
  40         int type;
  41         int ret = 0, error = 0;
  42
  43         while (offset < len-1) {
  44                 type = nlri_content[offset];
  45                 offset++;
  46                 switch (type) {
  47                 case FLOWSPEC_DEST_PREFIX:
  48                 case FLOWSPEC_SRC_PREFIX:
  49                         ret = bgp_flowspec_ip_address(
  50                                                 BGP_FLOWSPEC_VALIDATE_ONLY,
  51                                                 nlri_content + offset,
  52                                                 len - offset, NULL, &error,
  53                                                 afi);
  54                         break;
  55                 case FLOWSPEC_IP_PROTOCOL:
  56                 case FLOWSPEC_PORT:
  57                 case FLOWSPEC_DEST_PORT:
  58                 case FLOWSPEC_SRC_PORT:
  59                 case FLOWSPEC_ICMP_TYPE:
  60                 case FLOWSPEC_ICMP_CODE:
  61                         ret = bgp_flowspec_op_decode(BGP_FLOWSPEC_VALIDATE_ONLY,
  62                                                    nlri_content + offset,
  63                                                    len - offset, NULL, &error);
  64                         break;
  65                 case FLOWSPEC_TCP_FLAGS:
  66                 case FLOWSPEC_FRAGMENT:
  67                         ret = bgp_flowspec_bitmask_decode(
  68                                                    BGP_FLOWSPEC_VALIDATE_ONLY,
  69                                                    nlri_content + offset,
  70                                                    len - offset, NULL, &error);
  71                         break;
  72                 case FLOWSPEC_PKT_LEN:
  73                 case FLOWSPEC_DSCP:
  74                         ret = bgp_flowspec_op_decode(
  75                                                 BGP_FLOWSPEC_VALIDATE_ONLY,
  76                                                 nlri_content + offset,
  77                                                 len - offset, NULL, &error);
  78                         break;
  79                 default:
  80                         error = -1;
  81                         break;
  82                 }
  83                 offset += ret;
  84                 if (error < 0)
  85                         break;
  86         }
  87         return error;
  88 }
  89
  90 int bgp_nlri_parse_flowspec(struct peer *peer, struct attr *attr,
  91                             struct bgp_nlri *packet, int withdraw)
  92 {
  93         uint8_t *pnt;
  94         uint8_t *lim;
  95         afi_t afi;
  96         safi_t safi;
  97         int psize = 0;
  98         struct prefix p;
  99         int ret;
 100         void *temp;
 101
 102         /* Start processing the NLRI - there may be multiple in the MP_REACH */
 103         pnt = packet->nlri;
 104         lim = pnt + packet->length;
 105         afi = packet->afi;
 106         safi = packet->safi;
 107
 108         if (packet->length >= FLOWSPEC_NLRI_SIZELIMIT_EXTENDED) {
 109                 flog_err(EC_BGP_FLOWSPEC_PACKET,
 110                          "BGP flowspec nlri length maximum reached (%u)",
 111                          packet->length);
 112                 return BGP_NLRI_PARSE_ERROR_FLOWSPEC_NLRI_SIZELIMIT;
 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 BGP_NLRI_PARSE_ERROR_PACKET_OVERFLOW;
 122
 123                 psize = *pnt++;
 124                 if (psize >= FLOWSPEC_NLRI_SIZELIMIT) {
 125                         psize &= 0x0f;
 126                         psize = psize << 8;
 127                         psize |= *pnt++;
 128                 }
 129                 /* When packet overflow occur return immediately. */
 130                 if (pnt + psize > lim) {
 131                         flog_err(
 132                                 EC_BGP_FLOWSPEC_PACKET,
 133                                 "Flowspec NLRI length inconsistent ( size %u seen)",
 134                                 psize);
 135                         return BGP_NLRI_PARSE_ERROR_PACKET_OVERFLOW;
 136                 }
 137                 if (bgp_fs_nlri_validate(pnt, psize, afi) < 0) {
 138                         flog_err(
 139                                 EC_BGP_FLOWSPEC_PACKET,
 140                                 "Bad flowspec format or NLRI options not supported");
 141                         return BGP_NLRI_PARSE_ERROR_FLOWSPEC_BAD_FORMAT;
 142                 }
 143                 p.family = AF_FLOWSPEC;
 144                 p.prefixlen = 0;
 145                 /* Flowspec encoding is in bytes */
 146                 p.u.prefix_flowspec.prefixlen = psize;
 147                 p.u.prefix_flowspec.family = afi2family(afi);
 148                 temp = XCALLOC(MTYPE_TMP, psize);
 149                 memcpy(temp, pnt, psize);
 150                 p.u.prefix_flowspec.ptr = (uintptr_t) temp;
 151
 152                 if (BGP_DEBUG(flowspec, FLOWSPEC)) {
 153                         char return_string[BGP_FLOWSPEC_NLRI_STRING_MAX];
 154                         char local_string[BGP_FLOWSPEC_NLRI_STRING_MAX*2+16];
 155                         char ec_string[BGP_FLOWSPEC_NLRI_STRING_MAX];
 156                         char *s = NULL;
 157
 158                         bgp_fs_nlri_get_string((unsigned char *)
 159                                                p.u.prefix_flowspec.ptr,
 160                                                p.u.prefix_flowspec.prefixlen,
 161                                                return_string,
 162                                                NLRI_STRING_FORMAT_MIN, NULL,
 163                                                afi);
 164                         snprintf(ec_string, sizeof(ec_string),
 165                                  "EC{none}");
 166                         if (attr && attr->ecommunity) {
 167                                 s = ecommunity_ecom2str(attr->ecommunity,
 168                                                 ECOMMUNITY_FORMAT_ROUTE_MAP, 0);
 169                                 snprintf(ec_string, sizeof(ec_string),
 170                                          "EC{%s}",
 171                                         s == NULL ? "none" : s);
 172
 173                                 if (s)
 174                                         ecommunity_strfree(&s);
 175                         }
 176                         snprintf(local_string, sizeof(local_string),
 177                                  "FS Rx %s %s %s %s", withdraw ?
 178                                  "Withdraw":"Update",
 179                                  afi2str(afi), return_string,
 180                                  attr != NULL ? ec_string : "");
 181                         zlog_info("%s", local_string);
 182                 }
 183                 /* Process the route. */
 184                 if (!withdraw)
 185                         ret = bgp_update(peer, &p, 0, attr,
 186                                          afi, safi,
 187                                          ZEBRA_ROUTE_BGP, BGP_ROUTE_NORMAL,
 188                                          NULL, NULL, 0, 0, NULL);
 189                 else
 190                         ret = bgp_withdraw(peer, &p, 0, attr,
 191                                            afi, safi,
 192                                            ZEBRA_ROUTE_BGP, BGP_ROUTE_NORMAL,
 193                                            NULL, NULL, 0, NULL);
 194                 if (ret) {
 195                         flog_err(EC_BGP_FLOWSPEC_INSTALLATION,
 196                                  "Flowspec NLRI failed to be %s.",
 197                                  attr ? "added" : "withdrawn");
 198                         return BGP_NLRI_PARSE_ERROR;
 199                 }
 200         }
 201         return BGP_NLRI_PARSE_OK;
 202 }