/** * Copyright (C) 2012-2013 Steven Barth * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License v2 as published by * the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "router.h" #include "ndp.h" static void handle_solicit(void *addr, void *data, size_t len, struct interface *iface, void *dest); static void handle_rtnetlink(void *addr, void *data, size_t len, struct interface *iface, void *dest); static uint32_t rtnl_seqid = 0; static int ping_socket = -1; static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink}; // Filter ICMPv6 messages of type neighbor soliciation static struct sock_filter bpf[] = { BPF_STMT(BPF_LD | BPF_B | BPF_ABS, offsetof(struct ip6_hdr, ip6_nxt)), BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, IPPROTO_ICMPV6, 0, 3), BPF_STMT(BPF_LD | BPF_B | BPF_ABS, sizeof(struct ip6_hdr) + offsetof(struct icmp6_hdr, icmp6_type)), BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ND_NEIGHBOR_SOLICIT, 0, 1), BPF_STMT(BPF_RET | BPF_K, 0xffffffff), BPF_STMT(BPF_RET | BPF_K, 0), }; static const struct sock_fprog bpf_prog = {sizeof(bpf) / sizeof(*bpf), bpf}; // Initialize NDP-proxy int init_ndp(void) { // Setup netlink socket if ((rtnl_event.uloop.fd = odhcpd_open_rtnl()) < 0) return -1; // Receive netlink neighbor and ip-address events uint32_t group = RTNLGRP_IPV6_IFADDR; setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group)); group = RTNLGRP_IPV6_ROUTE; setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group)); odhcpd_register(&rtnl_event); // Open ICMPv6 socket ping_socket = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6); if (ping_socket < 0) { syslog(LOG_ERR, "Unable to open raw socket: %s", strerror(errno)); return -1; } int val = 2; setsockopt(ping_socket, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val)); // This is required by RFC 4861 val = 255; setsockopt(ping_socket, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val)); setsockopt(ping_socket, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val)); // Filter all packages, we only want to send struct icmp6_filter filt; ICMP6_FILTER_SETBLOCKALL(&filt); setsockopt(ping_socket, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt)); // Netlink socket, continued... group = RTNLGRP_NEIGH; setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group)); return 0; } static void dump_neigh_table(bool proxy) { struct { struct nlmsghdr nh; struct ndmsg ndm; } req = { {sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP, ++rtnl_seqid, 0}, {.ndm_family = AF_INET6, .ndm_flags = (proxy) ? NTF_PROXY : 0} }; send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT); odhcpd_process(&rtnl_event); } int setup_ndp_interface(struct interface *iface, bool enable) { char procbuf[64]; snprintf(procbuf, sizeof(procbuf), "/proc/sys/net/ipv6/conf/%s/proxy_ndp", iface->ifname); int procfd = open(procbuf, O_WRONLY); bool dump_neigh = false; if (iface->ndp_event.uloop.fd > 0) { uloop_fd_delete(&iface->ndp_event.uloop); close(iface->ndp_event.uloop.fd); iface->ndp_event.uloop.fd = -1; if (!enable || iface->ndp != RELAYD_RELAY) if (write(procfd, "0\n", 2) < 0) {} dump_neigh = true; } if (enable && (iface->ra == RELAYD_SERVER || iface->dhcpv6 == RELAYD_SERVER || iface->ndp == RELAYD_RELAY)) { // Synthesize initial address events struct { struct nlmsghdr nh; struct ifaddrmsg ifa; } req2 = { {sizeof(req2), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP, ++rtnl_seqid, 0}, {.ifa_family = AF_INET6, .ifa_index = iface->ifindex} }; send(rtnl_event.uloop.fd, &req2, sizeof(req2), MSG_DONTWAIT); } if (enable && iface->ndp == RELAYD_RELAY) { if (write(procfd, "1\n", 2) < 0) {} close(procfd); int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6)); if (sock < 0) { syslog(LOG_ERR, "Unable to open packet socket: %s", strerror(errno)); return -1; } #ifdef PACKET_RECV_TYPE int pktt = 1 << PACKET_MULTICAST; setsockopt(sock, SOL_PACKET, PACKET_RECV_TYPE, &pktt, sizeof(pktt)); #endif if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &bpf_prog, sizeof(bpf_prog))) { syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno)); return -1; } struct sockaddr_ll ll = { .sll_family = AF_PACKET, .sll_ifindex = iface->ifindex, .sll_protocol = htons(ETH_P_IPV6), .sll_hatype = 0, .sll_pkttype = 0, .sll_halen = 0, .sll_addr = {0}, }; bind(sock, (struct sockaddr*)&ll, sizeof(ll)); struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}}; setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq)); iface->ndp_event.uloop.fd = sock; iface->ndp_event.handle_dgram = handle_solicit; odhcpd_register(&iface->ndp_event); // If we already were enabled dump is unnecessary, if not do dump if (!dump_neigh) dump_neigh_table(false); else dump_neigh = false; } else { close(procfd); } if (dump_neigh) dump_neigh_table(true); return 0; } // Send an ICMP-ECHO. This is less for actually pinging but for the // neighbor cache to be kept up-to-date. static void ping6(struct in6_addr *addr, const struct interface *iface) { struct sockaddr_in6 dest = {AF_INET6, 0, 0, *addr, iface->ifindex}; struct icmp6_hdr echo = {.icmp6_type = ICMP6_ECHO_REQUEST}; struct iovec iov = {&echo, sizeof(echo)}; odhcpd_setup_route(addr, 128, iface, NULL, 128, true); odhcpd_send(ping_socket, &dest, &iov, 1, iface); odhcpd_setup_route(addr, 128, iface, NULL, 128, false); } // Handle solicitations static void handle_solicit(void *addr, void *data, size_t len, struct interface *iface, _unused void *dest) { struct ip6_hdr *ip6 = data; struct nd_neighbor_solicit *req = (struct nd_neighbor_solicit*)&ip6[1]; struct sockaddr_ll *ll = addr; // Solicitation is for duplicate address detection bool ns_is_dad = IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src); // Don't forward any non-DAD solicitation for external ifaces // TODO: check if we should even forward DADs for them if (iface->external && !ns_is_dad) return; if (len < sizeof(*ip6) + sizeof(*req)) return; // Invalid reqicitation if (IN6_IS_ADDR_LINKLOCAL(&req->nd_ns_target) || IN6_IS_ADDR_LOOPBACK(&req->nd_ns_target) || IN6_IS_ADDR_MULTICAST(&req->nd_ns_target)) return; // Invalid target char ipbuf[INET6_ADDRSTRLEN]; inet_ntop(AF_INET6, &req->nd_ns_target, ipbuf, sizeof(ipbuf)); syslog(LOG_DEBUG, "Got a NS for %s", ipbuf); uint8_t mac[6]; odhcpd_get_mac(iface, mac); if (!memcmp(ll->sll_addr, mac, sizeof(mac))) return; // Looped back struct interface *c; list_for_each_entry(c, &interfaces, head) if (iface->ndp == RELAYD_RELAY && iface != c && (ns_is_dad || !c->external)) ping6(&req->nd_ns_target, c); } // Use rtnetlink to modify kernel routes static void setup_route(struct in6_addr *addr, struct interface *iface, bool add) { char namebuf[INET6_ADDRSTRLEN]; inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf)); syslog(LOG_NOTICE, "%s about %s on %s", (add) ? "Learned" : "Forgot", namebuf, iface->ifname); if (iface->learn_routes) odhcpd_setup_route(addr, 128, iface, NULL, 1024, add); } // Handler for neighbor cache entries from the kernel. This is our source // to learn and unlearn hosts on interfaces. static void handle_rtnetlink(_unused void *addr, void *data, size_t len, _unused struct interface *iface, _unused void *dest) { bool dump_neigh = false; struct in6_addr last_solicited = IN6ADDR_ANY_INIT; for (struct nlmsghdr *nh = data; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) { struct ndmsg *ndm = NLMSG_DATA(nh); struct rtmsg *rtm = NLMSG_DATA(nh); bool is_addr = (nh->nlmsg_type == RTM_NEWADDR || nh->nlmsg_type == RTM_DELADDR); bool is_route = (nh->nlmsg_type == RTM_NEWROUTE || nh->nlmsg_type == RTM_DELROUTE); bool is_neigh = (nh->nlmsg_type == RTM_NEWNEIGH || nh->nlmsg_type == RTM_DELNEIGH); // Family and ifindex are on the same offset for NEIGH and ADDR if ((!is_addr && !is_route && !is_neigh) || NLMSG_PAYLOAD(nh, 0) < sizeof(*ndm) || ndm->ndm_family != AF_INET6) continue; // Inform about a change in default route if (is_route && rtm->rtm_dst_len == 0) raise(SIGUSR1); else if (is_route) continue; // Data to retrieve size_t rta_offset = (is_addr) ? sizeof(struct ifaddrmsg) : sizeof(*ndm); uint16_t atype = (is_addr) ? IFA_ADDRESS : NDA_DST; ssize_t alen = NLMSG_PAYLOAD(nh, rta_offset); struct in6_addr *addr = NULL; for (struct rtattr *rta = (void*)(((uint8_t*)ndm) + rta_offset); RTA_OK(rta, alen); rta = RTA_NEXT(rta, alen)) { if (rta->rta_type == atype && RTA_PAYLOAD(rta) >= sizeof(*addr)) { addr = RTA_DATA(rta); } } // Lookup interface struct interface *iface = odhcpd_get_interface_by_index(ndm->ndm_ifindex); if (!iface) continue; // Keep-alive neighbor entries for RA sending if (nh->nlmsg_type == RTM_DELNEIGH && !(ndm->ndm_state & NUD_FAILED) && addr && IN6_IS_ADDR_LINKLOCAL(addr) && iface->ra == RELAYD_SERVER) ping6(addr, iface); // Address not specified or unrelated if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) || IN6_IS_ADDR_MULTICAST(addr)) continue; // Check for states bool add; if (is_addr) add = (nh->nlmsg_type == RTM_NEWADDR); else add = (nh->nlmsg_type == RTM_NEWNEIGH && (ndm->ndm_state & (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE | NUD_PERMANENT | NUD_NOARP))); if (iface->ndp == RELAYD_RELAY) { // Replay change to all neighbor cache struct { struct nlmsghdr nh; struct ndmsg ndm; struct nlattr nla_dst; struct in6_addr dst; } req = { {sizeof(req), RTM_DELNEIGH, NLM_F_REQUEST, ++rtnl_seqid, 0}, {.ndm_family = AF_INET6, .ndm_flags = NTF_PROXY}, {sizeof(struct nlattr) + sizeof(struct in6_addr), NDA_DST}, *addr }; if (ndm->ndm_flags & NTF_PROXY) { // Dump & flush proxy entries if (nh->nlmsg_type == RTM_NEWNEIGH) { req.ndm.ndm_ifindex = iface->ifindex; send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT); setup_route(addr, iface, false); dump_neigh = true; } } else if (add) { struct interface *c; list_for_each_entry(c, &interfaces, head) { if (iface == c) continue; if (c->ndp == RELAYD_RELAY) { req.nh.nlmsg_type = RTM_NEWNEIGH; req.nh.nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE; req.ndm.ndm_ifindex = c->ifindex; send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT); } else { // Delete NDP cache from interfaces without relay req.nh.nlmsg_type = RTM_DELNEIGH; req.nh.nlmsg_flags &= ~(NLM_F_CREATE | NLM_F_REPLACE); req.ndm.ndm_ifindex = c->ifindex; send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT); } } setup_route(addr, iface, true); } else { if (nh->nlmsg_type == RTM_NEWNEIGH) { // might be locally originating if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) { last_solicited = *addr; struct interface *c; list_for_each_entry(c, &interfaces, head) if (iface->ndp == RELAYD_RELAY && iface != c && !c->external == false) ping6(addr, c); } } else { struct interface *c; list_for_each_entry(c, &interfaces, head) { if (c->ndp == RELAYD_RELAY && iface != c) { req.ndm.ndm_ifindex = c->ifindex; send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT); } } setup_route(addr, iface, false); // also: dump to add proxies back in case it moved elsewhere dump_neigh = true; } } } if (is_addr) { if (iface->ra == RELAYD_SERVER) raise(SIGUSR1); // Inform about a change in addresses if (iface->dhcpv6 == RELAYD_SERVER) iface->ia_reconf = true; } } if (dump_neigh) dump_neigh_table(false); }