nhrpd/netlink_arp.c

   1 /* NHRP netlink/neighbor table arpd code
   2  * Copyright (c) 2014-2016 Timo Teräs
   3  *
   4  * This file is free software: you may copy, redistribute and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  */
   9
  10 #include <fcntl.h>
  11 #include <net/if.h>
  12 #include <netinet/if_ether.h>
  13 #include <linux/netlink.h>
  14 #include <linux/neighbour.h>
  15 #include <linux/netfilter/nfnetlink_log.h>
  16
  17 #include "thread.h"
  18 #include "nhrpd.h"
  19 #include "netlink.h"
  20 #include "znl.h"
  21
  22 int netlink_req_fd = -1;
  23 int netlink_nflog_group;
  24 static int netlink_log_fd = -1;
  25 static struct thread *netlink_log_thread;
  26 static int netlink_listen_fd = -1;
  27
  28 typedef void (*netlink_dispatch_f)(struct nlmsghdr *msg, struct zbuf *zb);
  29
  30 void netlink_update_binding(struct interface *ifp, union sockunion *proto, union sockunion *nbma)
  31 {
  32         struct nlmsghdr *n;
  33         struct ndmsg *ndm;
  34         struct zbuf *zb = zbuf_alloc(512);
  35
  36         n = znl_nlmsg_push(zb, nbma ? RTM_NEWNEIGH : RTM_DELNEIGH, NLM_F_REQUEST | NLM_F_REPLACE | NLM_F_CREATE);
  37         ndm = znl_push(zb, sizeof(*ndm));
  38         *ndm = (struct ndmsg) {
  39                 .ndm_family = sockunion_family(proto),
  40                 .ndm_ifindex = ifp->ifindex,
  41                 .ndm_type = RTN_UNICAST,
  42                 .ndm_state = nbma ? NUD_REACHABLE : NUD_FAILED,
  43         };
  44         znl_rta_push(zb, NDA_DST, sockunion_get_addr(proto), family2addrsize(sockunion_family(proto)));
  45         if (nbma)
  46                 znl_rta_push(zb, NDA_LLADDR, sockunion_get_addr(nbma), family2addrsize(sockunion_family(nbma)));
  47         znl_nlmsg_complete(zb, n);
  48         zbuf_send(zb, netlink_req_fd);
  49         zbuf_recv(zb, netlink_req_fd);
  50         zbuf_free(zb);
  51 }
  52
  53 static void netlink_neigh_msg(struct nlmsghdr *msg, struct zbuf *zb)
  54 {
  55         struct ndmsg *ndm;
  56         struct rtattr *rta;
  57         struct nhrp_cache *c;
  58         struct interface *ifp;
  59         struct zbuf payload;
  60         union sockunion addr;
  61         size_t len;
  62         char buf[SU_ADDRSTRLEN];
  63         int state;
  64
  65         ndm = znl_pull(zb, sizeof(*ndm));
  66         if (!ndm) return;
  67
  68         sockunion_family(&addr) = AF_UNSPEC;
  69         while ((rta = znl_rta_pull(zb, &payload)) != NULL) {
  70                 len = zbuf_used(&payload);
  71                 switch (rta->rta_type) {
  72                 case NDA_DST:
  73                         sockunion_set(&addr, ndm->ndm_family, zbuf_pulln(&payload, len), len);
  74                         break;
  75                 }
  76         }
  77
  78         ifp = if_lookup_by_index(ndm->ndm_ifindex);
  79         if (!ifp || sockunion_family(&addr) == AF_UNSPEC)
  80                 return;
  81
  82         c = nhrp_cache_get(ifp, &addr, 0);
  83         if (!c)
  84                 return;
  85
  86         if (msg->nlmsg_type == RTM_GETNEIGH) {
  87                 debugf(NHRP_DEBUG_KERNEL, "Netlink: who-has %s dev %s",
  88                         sockunion2str(&addr, buf, sizeof buf),
  89                         ifp->name);
  90
  91                 if (c->cur.type >= NHRP_CACHE_CACHED) {
  92                         nhrp_cache_set_used(c, 1);
  93                         netlink_update_binding(ifp, &addr, &c->cur.peer->vc->remote.nbma);
  94                 }
  95         } else {
  96                 debugf(NHRP_DEBUG_KERNEL, "Netlink: update %s dev %s nud %x",
  97                         sockunion2str(&addr, buf, sizeof buf),
  98                         ifp->name, ndm->ndm_state);
  99
 100                 state = (msg->nlmsg_type == RTM_NEWNEIGH) ? ndm->ndm_state : NUD_FAILED;
 101                 nhrp_cache_set_used(c, state == NUD_REACHABLE);
 102         }
 103 }
 104
 105 static int netlink_route_recv(struct thread *t)
 106 {
 107         uint8_t buf[ZNL_BUFFER_SIZE];
 108         int fd = THREAD_FD(t);
 109         struct zbuf payload, zb;
 110         struct nlmsghdr *n;
 111
 112         zbuf_init(&zb, buf, sizeof(buf), 0);
 113         while (zbuf_recv(&zb, fd) > 0) {
 114                 while ((n = znl_nlmsg_pull(&zb, &payload)) != 0) {
 115                         debugf(NHRP_DEBUG_KERNEL, "Netlink: Received msg_type %u, msg_flags %u",
 116                                 n->nlmsg_type, n->nlmsg_flags);
 117                         switch (n->nlmsg_type) {
 118                         case RTM_GETNEIGH:
 119                         case RTM_NEWNEIGH:
 120                         case RTM_DELNEIGH:
 121                                 netlink_neigh_msg(n, &payload);
 122                                 break;
 123                         }
 124                 }
 125         }
 126
 127         thread_add_read(master, netlink_route_recv, 0, fd);
 128
 129         return 0;
 130 }
 131
 132 static void netlink_log_register(int fd, int group)
 133 {
 134         struct nlmsghdr *n;
 135         struct nfgenmsg *nf;
 136         struct nfulnl_msg_config_cmd cmd;
 137         struct zbuf *zb = zbuf_alloc(512);
 138
 139         n = znl_nlmsg_push(zb, (NFNL_SUBSYS_ULOG<<8) | NFULNL_MSG_CONFIG, NLM_F_REQUEST | NLM_F_ACK);
 140         nf = znl_push(zb, sizeof(*nf));
 141         *nf = (struct nfgenmsg) {
 142                 .nfgen_family = AF_UNSPEC,
 143                 .version = NFNETLINK_V0,
 144                 .res_id = htons(group),
 145         };
 146         cmd.command = NFULNL_CFG_CMD_BIND;
 147         znl_rta_push(zb, NFULA_CFG_CMD, &cmd, sizeof(cmd));
 148         znl_nlmsg_complete(zb, n);
 149
 150         zbuf_send(zb, fd);
 151         zbuf_free(zb);
 152 }
 153
 154 static void netlink_log_indication(struct nlmsghdr *msg, struct zbuf *zb)
 155 {
 156         struct nfgenmsg *nf;
 157         struct rtattr *rta;
 158         struct zbuf rtapl, pktpl;
 159         struct interface *ifp;
 160         struct nfulnl_msg_packet_hdr *pkthdr = NULL;
 161         uint32_t *in_ndx = NULL;
 162
 163         nf = znl_pull(zb, sizeof(*nf));
 164         if (!nf) return;
 165
 166         memset(&pktpl, 0, sizeof(pktpl));
 167         while ((rta = znl_rta_pull(zb, &rtapl)) != NULL) {
 168                 switch (rta->rta_type) {
 169                 case NFULA_PACKET_HDR:
 170                         pkthdr = znl_pull(&rtapl, sizeof(*pkthdr));
 171                         break;
 172                 case NFULA_IFINDEX_INDEV:
 173                         in_ndx = znl_pull(&rtapl, sizeof(*in_ndx));
 174                         break;
 175                 case NFULA_PAYLOAD:
 176                         pktpl = rtapl;
 177                         break;
 178                 /* NFULA_HWHDR exists and is supposed to contain source
 179                  * hardware address. However, for ip_gre it seems to be
 180                  * the nexthop destination address if the packet matches
 181                  * route. */
 182                 }
 183         }
 184
 185         if (!pkthdr || !in_ndx || !zbuf_used(&pktpl))
 186                 return;
 187
 188         ifp = if_lookup_by_index(htonl(*in_ndx));
 189         if (!ifp)
 190                 return;
 191
 192         nhrp_peer_send_indication(ifp, htons(pkthdr->hw_protocol), &pktpl);
 193 }
 194
 195 static int netlink_log_recv(struct thread *t)
 196 {
 197         uint8_t buf[ZNL_BUFFER_SIZE];
 198         int fd = THREAD_FD(t);
 199         struct zbuf payload, zb;
 200         struct nlmsghdr *n;
 201
 202         netlink_log_thread = NULL;
 203
 204         zbuf_init(&zb, buf, sizeof(buf), 0);
 205         while (zbuf_recv(&zb, fd) > 0) {
 206                 while ((n = znl_nlmsg_pull(&zb, &payload)) != 0) {
 207                         debugf(NHRP_DEBUG_KERNEL, "Netlink-log: Received msg_type %u, msg_flags %u",
 208                                 n->nlmsg_type, n->nlmsg_flags);
 209                         switch (n->nlmsg_type) {
 210                         case (NFNL_SUBSYS_ULOG<<8) | NFULNL_MSG_PACKET:
 211                                 netlink_log_indication(n, &payload);
 212                                 break;
 213                         }
 214                 }
 215         }
 216
 217         THREAD_READ_ON(master, netlink_log_thread, netlink_log_recv, 0, netlink_log_fd);
 218
 219         return 0;
 220 }
 221
 222 void netlink_set_nflog_group(int nlgroup)
 223 {
 224         if (netlink_log_fd >= 0) {
 225                 THREAD_OFF(netlink_log_thread);
 226                 close(netlink_log_fd);
 227                 netlink_log_fd = -1;
 228         }
 229         netlink_nflog_group = nlgroup;
 230         if (nlgroup) {
 231                 netlink_log_fd = znl_open(NETLINK_NETFILTER,  0);
 232                 netlink_log_register(netlink_log_fd, nlgroup);
 233                 THREAD_READ_ON(master, netlink_log_thread, netlink_log_recv, 0, netlink_log_fd);
 234         }
 235 }
 236
 237 int netlink_init(void)
 238 {
 239         netlink_req_fd = znl_open(NETLINK_ROUTE, 0);
 240         netlink_listen_fd = znl_open(NETLINK_ROUTE, RTMGRP_NEIGH);
 241         thread_add_read(master, netlink_route_recv, 0, netlink_listen_fd);
 242
 243         return 0;
 244 }
 245
 246 int netlink_configure_arp(unsigned int ifindex, int pf)
 247 {
 248         struct nlmsghdr *n;
 249         struct ndtmsg *ndtm;
 250         struct rtattr *rta;
 251         struct zbuf *zb = zbuf_alloc(512);
 252         int r;
 253
 254         n = znl_nlmsg_push(zb, RTM_SETNEIGHTBL, NLM_F_REQUEST | NLM_F_REPLACE);
 255         ndtm = znl_push(zb, sizeof(*ndtm));
 256         *ndtm = (struct ndtmsg) {
 257                 .ndtm_family = pf,
 258         };
 259
 260         znl_rta_push(zb, NDTA_NAME, pf == AF_INET ? "arp_cache" : "ndisc_cache", 10);
 261
 262         rta = znl_rta_nested_push(zb, NDTA_PARMS);
 263         znl_rta_push_u32(zb, NDTPA_IFINDEX, ifindex);
 264         znl_rta_push_u32(zb, NDTPA_APP_PROBES, 1);
 265         znl_rta_push_u32(zb, NDTPA_MCAST_PROBES, 0);
 266         znl_rta_push_u32(zb, NDTPA_UCAST_PROBES, 0);
 267         znl_rta_nested_complete(zb, rta);
 268
 269         znl_nlmsg_complete(zb, n);
 270         r = zbuf_send(zb, netlink_req_fd);
 271         zbuf_recv(zb, netlink_req_fd);
 272         zbuf_free(zb);
 273
 274         return r;
 275 }