zebra/rule_netlink.c

   1 /*
   2  * Zebra Policy Based Routing (PBR) interaction with the kernel using
   3  * netlink.
   4  * Copyright (C) 2018  Cumulus Networks, Inc.
   5  *
   6  * This file is part of FRR.
   7  *
   8  * FRR is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License as published by the
  10  * Free Software Foundation; either version 2, or (at your option) any
  11  * later version.
  12  *
  13  * FRR is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with FRR; see the file COPYING.  If not, write to the Free
  20  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  21  * 02111-1307, USA.
  22  */
  23
  24 #include <zebra.h>
  25
  26 #ifdef HAVE_NETLINK
  27
  28 #include "if.h"
  29 #include "prefix.h"
  30 #include "vrf.h"
  31
  32 #include <linux/fib_rules.h>
  33 #include "zebra/zserv.h"
  34 #include "zebra/zebra_ns.h"
  35 #include "zebra/zebra_vrf.h"
  36 #include "zebra/rt.h"
  37 #include "zebra/interface.h"
  38 #include "zebra/debug.h"
  39 #include "zebra/rtadv.h"
  40 #include "zebra/kernel_netlink.h"
  41 #include "zebra/rule_netlink.h"
  42 #include "zebra/zebra_pbr.h"
  43 #include "zebra/zebra_errors.h"
  44
  45 /* definitions */
  46
  47 /* static function declarations */
  48
  49 /* Private functions */
  50
  51 /* Install or uninstall specified rule for a specific interface.
  52  * Form netlink message and ship it. Currently, notify status after
  53  * waiting for netlink status.
  54  */
  55 static int netlink_rule_update(int cmd, struct zebra_pbr_rule *rule)
  56 {
  57         int family;
  58         int bytelen;
  59         struct {
  60                 struct nlmsghdr n;
  61                 struct fib_rule_hdr frh;
  62                 char buf[NL_PKT_BUF_SIZE];
  63         } req;
  64         struct zebra_ns *zns = zebra_ns_lookup(NS_DEFAULT);
  65         struct sockaddr_nl snl;
  66         char buf1[PREFIX_STRLEN];
  67         char buf2[PREFIX_STRLEN];
  68
  69         memset(&req, 0, sizeof(req) - NL_PKT_BUF_SIZE);
  70         family = PREFIX_FAMILY(&rule->rule.filter.src_ip);
  71         bytelen = (family == AF_INET ? 4 : 16);
  72
  73         req.n.nlmsg_type = cmd;
  74         req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
  75         req.n.nlmsg_flags = NLM_F_REQUEST;
  76         req.n.nlmsg_pid = zns->netlink_cmd.snl.nl_pid;
  77
  78         req.frh.family = family;
  79         req.frh.action = FR_ACT_TO_TBL;
  80
  81         /* rule's pref # */
  82         addattr32(&req.n, sizeof(req), FRA_PRIORITY, rule->rule.priority);
  83
  84         /* interface on which applied */
  85         if (rule->ifp)
  86                 addattr_l(&req.n, sizeof(req), FRA_IFNAME, rule->ifp->name,
  87                           strlen(rule->ifp->name) + 1);
  88
  89         /* source IP, if specified */
  90         if (IS_RULE_FILTERING_ON_SRC_IP(rule)) {
  91                 req.frh.src_len = rule->rule.filter.src_ip.prefixlen;
  92                 addattr_l(&req.n, sizeof(req), FRA_SRC,
  93                           &rule->rule.filter.src_ip.u.prefix, bytelen);
  94         }
  95         /* destination IP, if specified */
  96         if (IS_RULE_FILTERING_ON_DST_IP(rule)) {
  97                 req.frh.dst_len = rule->rule.filter.dst_ip.prefixlen;
  98                 addattr_l(&req.n, sizeof(req), FRA_DST,
  99                           &rule->rule.filter.dst_ip.u.prefix, bytelen);
 100         }
 101
 102         /* fwmark, if specified */
 103         if (IS_RULE_FILTERING_ON_FWMARK(rule)) {
 104                 addattr32(&req.n, sizeof(req), FRA_FWMARK,
 105                           rule->rule.filter.fwmark);
 106         }
 107
 108         /* Route table to use to forward, if filter criteria matches. */
 109         if (rule->rule.action.table < 256)
 110                 req.frh.table = rule->rule.action.table;
 111         else {
 112                 req.frh.table = RT_TABLE_UNSPEC;
 113                 addattr32(&req.n, sizeof(req), FRA_TABLE,
 114                           rule->rule.action.table);
 115         }
 116
 117         if (IS_ZEBRA_DEBUG_KERNEL)
 118                 zlog_debug(
 119                         "Tx %s family %s IF %s(%u) Pref %u Src %s Dst %s Table %u",
 120                         nl_msg_type_to_str(cmd), nl_family_to_str(family),
 121                         rule->ifp ? rule->ifp->name : "Unknown",
 122                         rule->ifp ? rule->ifp->ifindex : 0, rule->rule.priority,
 123                         prefix2str(&rule->rule.filter.src_ip, buf1,
 124                                    sizeof(buf1)),
 125                         prefix2str(&rule->rule.filter.dst_ip, buf2,
 126                                    sizeof(buf2)),
 127                         rule->rule.action.table);
 128
 129         /* Ship off the message.
 130          * Note: Currently, netlink_talk() is a blocking call which returns
 131          * back the status.
 132          */
 133         memset(&snl, 0, sizeof(snl));
 134         snl.nl_family = AF_NETLINK;
 135         return netlink_talk(netlink_talk_filter, &req.n,
 136                             &zns->netlink_cmd, zns, 0);
 137 }
 138
 139
 140 /* Public functions */
 141 /*
 142  * Install specified rule for a specific interface. The preference is what
 143  * goes in the rule to denote relative ordering; it may or may not be the
 144  * same as the rule's user-defined sequence number.
 145  */
 146 enum zebra_dplane_result kernel_add_pbr_rule(struct zebra_pbr_rule *rule)
 147 {
 148         int ret = 0;
 149
 150         ret = netlink_rule_update(RTM_NEWRULE, rule);
 151         kernel_pbr_rule_add_del_status(rule,
 152                                        (!ret) ? ZEBRA_DPLANE_INSTALL_SUCCESS
 153                                               : ZEBRA_DPLANE_INSTALL_FAILURE);
 154
 155         return ZEBRA_DPLANE_REQUEST_SUCCESS;
 156 }
 157
 158 /*
 159  * Uninstall specified rule for a specific interface.
 160  */
 161 enum zebra_dplane_result kernel_del_pbr_rule(struct zebra_pbr_rule *rule)
 162 {
 163         int ret = 0;
 164
 165         ret = netlink_rule_update(RTM_DELRULE, rule);
 166         kernel_pbr_rule_add_del_status(rule,
 167                                        (!ret) ? ZEBRA_DPLANE_DELETE_SUCCESS
 168                                               : ZEBRA_DPLANE_DELETE_FAILURE);
 169
 170         return ZEBRA_DPLANE_REQUEST_SUCCESS;
 171 }
 172
 173 /*
 174  * Handle netlink notification informing a rule add or delete.
 175  * Handling of an ADD is TBD.
 176  * DELs are notified up, if other attributes indicate it may be a
 177  * notification of interest. The expectation is that if this corresponds
 178  * to a PBR rule added by FRR, it will be readded.
 179  */
 180 int netlink_rule_change(struct nlmsghdr *h, ns_id_t ns_id, int startup)
 181 {
 182         struct zebra_ns *zns;
 183         struct fib_rule_hdr *frh;
 184         struct rtattr *tb[FRA_MAX + 1];
 185         int len;
 186         char *ifname;
 187         struct zebra_pbr_rule rule;
 188         char buf1[PREFIX_STRLEN];
 189         char buf2[PREFIX_STRLEN];
 190
 191         /* Basic validation followed by extracting attributes. */
 192         if (h->nlmsg_type != RTM_NEWRULE && h->nlmsg_type != RTM_DELRULE)
 193                 return 0;
 194
 195         /* TBD */
 196         if (h->nlmsg_type == RTM_NEWRULE)
 197                 return 0;
 198
 199         len = h->nlmsg_len - NLMSG_LENGTH(sizeof(struct fib_rule_hdr));
 200         if (len < 0) {
 201                 zlog_err("%s: Message received from netlink is of a broken size: %d %zu",
 202                          __PRETTY_FUNCTION__, h->nlmsg_len,
 203                          (size_t)NLMSG_LENGTH(sizeof(struct fib_rule_hdr)));
 204                 return -1;
 205         }
 206
 207         frh = NLMSG_DATA(h);
 208         if (frh->family != AF_INET && frh->family != AF_INET6) {
 209                 flog_warn(
 210                         EC_ZEBRA_NETLINK_INVALID_AF,
 211                         "Invalid address family: %u received from kernel rule change: %u",
 212                         frh->family, h->nlmsg_type);
 213                 return 0;
 214         }
 215         if (frh->action != FR_ACT_TO_TBL)
 216                 return 0;
 217
 218         memset(tb, 0, sizeof(tb));
 219         netlink_parse_rtattr(tb, FRA_MAX, RTM_RTA(frh), len);
 220
 221         /* TBD: We don't care about rules not specifying an IIF. */
 222         if (tb[FRA_IFNAME] == NULL)
 223                 return 0;
 224
 225         /* If we don't know the interface, we don't care. */
 226         ifname = (char *)RTA_DATA(tb[FRA_IFNAME]);
 227         zns = zebra_ns_lookup(ns_id);
 228         rule.ifp = if_lookup_by_name_per_ns(zns, ifname);
 229         if (!rule.ifp)
 230                 return 0;
 231
 232         memset(&rule, 0, sizeof(rule));
 233         if (tb[FRA_PRIORITY])
 234                 rule.rule.priority = *(uint32_t *)RTA_DATA(tb[FRA_PRIORITY]);
 235
 236         if (tb[FRA_SRC]) {
 237                 if (frh->family == AF_INET)
 238                         memcpy(&rule.rule.filter.src_ip.u.prefix4,
 239                                RTA_DATA(tb[FRA_SRC]), 4);
 240                 else
 241                         memcpy(&rule.rule.filter.src_ip.u.prefix6,
 242                                RTA_DATA(tb[FRA_SRC]), 16);
 243                 rule.rule.filter.src_ip.prefixlen = frh->src_len;
 244                 rule.rule.filter.filter_bm |= PBR_FILTER_SRC_IP;
 245         }
 246
 247         if (tb[FRA_DST]) {
 248                 if (frh->family == AF_INET)
 249                         memcpy(&rule.rule.filter.dst_ip.u.prefix4,
 250                                RTA_DATA(tb[FRA_DST]), 4);
 251                 else
 252                         memcpy(&rule.rule.filter.dst_ip.u.prefix6,
 253                                RTA_DATA(tb[FRA_DST]), 16);
 254                 rule.rule.filter.dst_ip.prefixlen = frh->dst_len;
 255                 rule.rule.filter.filter_bm |= PBR_FILTER_DST_IP;
 256         }
 257
 258         if (tb[FRA_TABLE])
 259                 rule.rule.action.table = *(uint32_t *)RTA_DATA(tb[FRA_TABLE]);
 260         else
 261                 rule.rule.action.table = frh->table;
 262
 263         if (IS_ZEBRA_DEBUG_KERNEL)
 264                 zlog_debug(
 265                         "Rx %s family %s IF %s(%u) Pref %u Src %s Dst %s Table %u",
 266                         nl_msg_type_to_str(h->nlmsg_type),
 267                         nl_family_to_str(frh->family), rule.ifp->name,
 268                         rule.ifp->ifindex, rule.rule.priority,
 269                         prefix2str(&rule.rule.filter.src_ip, buf1,
 270                                    sizeof(buf1)),
 271                         prefix2str(&rule.rule.filter.dst_ip, buf2,
 272                                    sizeof(buf2)),
 273                         rule.rule.action.table);
 274
 275         return kernel_pbr_rule_del(&rule);
 276 }
 277
 278 /*
 279  * Get to know existing PBR rules in the kernel - typically called at startup.
 280  * TBD.
 281  */
 282 int netlink_rules_read(struct zebra_ns *zns)
 283 {
 284         return 0;
 285 }
 286
 287 #endif /* HAVE_NETLINK */