/** * 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 "router.h" #include "odhcpd.h" static void forward_router_solicitation(const struct interface *iface); static void forward_router_advertisement(uint8_t *data, size_t len); static void handle_icmpv6(void *addr, void *data, size_t len, struct interface *iface, void *dest); static void trigger_router_advert(struct uloop_timeout *event); static void sigusr1_refresh(int signal); static struct odhcpd_event router_event = {.uloop = {.fd = -1}, .handle_dgram = handle_icmpv6, }; static FILE *fp_route = NULL; #define RA_IOV_LEN 6 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX) int init_router(void) { // Open ICMPv6 socket int sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6); if (sock < 0 && errno != EAFNOSUPPORT) { syslog(LOG_ERR, "Failed to open RAW-socket: %s", strerror(errno)); return -1; } // Let the kernel compute our checksums int val = 2; setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val)); // This is required by RFC 4861 val = 255; setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val)); setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val)); // We need to know the source interface val = 1; setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val)); setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val)); // Don't loop back val = 0; setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val)); // Filter ICMPv6 package types struct icmp6_filter filt; ICMP6_FILTER_SETBLOCKALL(&filt); ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt); ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt); setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt)); // Register socket router_event.uloop.fd = sock; odhcpd_register(&router_event); if (!(fp_route = fopen("/proc/net/ipv6_route", "r"))) syslog(LOG_ERR, "Failed to open routing table: %s", strerror(errno)); signal(SIGUSR1, sigusr1_refresh); return 0; } int setup_router_interface(struct interface *iface, bool enable) { if (!fp_route || router_event.uloop.fd < 0) return -1; struct ipv6_mreq all_nodes = {ALL_IPV6_NODES, iface->ifindex}; struct ipv6_mreq all_routers = {ALL_IPV6_ROUTERS, iface->ifindex}; uloop_timeout_cancel(&iface->timer_rs); iface->timer_rs.cb = NULL; if (iface->ifindex <= 0) return -1; setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &all_nodes, sizeof(all_nodes)); setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &all_routers, sizeof(all_routers)); if (!enable) { if (iface->ra) trigger_router_advert(&iface->timer_rs); } else { void *mreq = &all_routers; if (iface->ra == RELAYD_RELAY && iface->master) { mreq = &all_nodes; forward_router_solicitation(iface); } else if (iface->ra == RELAYD_SERVER && !iface->master) { iface->timer_rs.cb = trigger_router_advert; uloop_timeout_set(&iface->timer_rs, 1000); } if (iface->ra == RELAYD_RELAY || (iface->ra == RELAYD_SERVER && !iface->master)) setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, mreq, sizeof(all_nodes)); } return 0; } // Signal handler to resend all RDs static void sigusr1_refresh(_unused int signal) { struct interface *iface; list_for_each_entry(iface, &interfaces, head) if (iface->ra == RELAYD_SERVER && !iface->master) uloop_timeout_set(&iface->timer_rs, 1000); } static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len) { struct icmp6_hdr *hdr = (struct icmp6_hdr *)data; struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len]; /* Hoplimit is already checked in odhcpd_receive_packets */ if (len < sizeof(*hdr) || hdr->icmp6_code) return false; switch (hdr->icmp6_type) { case ND_ROUTER_ADVERT: if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr)) return false; opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1); break; case ND_ROUTER_SOLICIT: opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1); break; default: return false; } icmpv6_for_each_option(opt, opt, end) if (opt->type == ND_OPT_SOURCE_LINKADDR && IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) && hdr->icmp6_type == ND_ROUTER_SOLICIT) return false; // Check all options parsed successfully return opt == end; } // Detect whether a default route exists, also find the source prefixes static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len) { rewind(fp_route); char line[512], ifname[16]; bool found_default = false; struct odhcpd_ipaddr p = {IN6ADDR_ANY_INIT, 0, 0, 0, 0}; while (fgets(line, sizeof(line), fp_route)) { uint32_t rflags; if (sscanf(line, "00000000000000000000000000000000 00 " "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) && strcmp(ifname, "lo")) { found_default = true; } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s " "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo", &p.addr.s6_addr32[0], &p.addr.s6_addr32[1], &p.prefix, &rflags) && p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) { // Find source prefixes by scanning through unreachable-routes p.addr.s6_addr32[0] = htonl(p.addr.s6_addr32[0]); p.addr.s6_addr32[1] = htonl(p.addr.s6_addr32[1]); for (ssize_t i = 0; i < len; ++i) { if (n[i].prefix <= 64 && n[i].prefix >= p.prefix && !odhcpd_bmemcmp(&p.addr, &n[i].addr, p.prefix)) { n[i].dprefix = p.prefix; break; } } } } return found_default; } static int calc_adv_interval(struct interface *iface, uint32_t minvalid, uint32_t *maxival) { uint32_t minival = iface->ra_mininterval; int msecs; *maxival = iface->ra_maxinterval; if (*maxival > minvalid/3) *maxival = minvalid/3; if (*maxival > MaxRtrAdvInterval) *maxival = MaxRtrAdvInterval; else if (*maxival < 4) *maxival = 4; if (minival < MinRtrAdvInterval) minival = MinRtrAdvInterval; else if (minival > (*maxival * 3)/4) minival = (*maxival >= 9 ? *maxival/3 : *maxival); odhcpd_urandom(&msecs, sizeof(msecs)); msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) + minival*1000; return msecs; } static uint16_t calc_ra_lifetime(struct interface *iface, uint32_t maxival) { uint16_t lifetime = 3*maxival; if (iface->ra_lifetime >= 0) { lifetime = iface->ra_lifetime; if (lifetime < maxival) lifetime = maxival; else if (lifetime > 9000) lifetime = 9000; } return lifetime; } // Router Advert server mode static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from) { time_t now = odhcpd_time(); int mtu = odhcpd_get_interface_config(iface->ifname, "mtu"); int hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit"); if (mtu < 1280) mtu = 1280; struct { struct nd_router_advert h; struct icmpv6_opt lladdr; struct nd_opt_mtu mtu; struct nd_opt_prefix_info prefix[sizeof(iface->ia_addr) / sizeof(*iface->ia_addr)]; } adv = { .h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0}, .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}}, .mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)}, }; if (hlim > 0) adv.h.nd_ra_curhoplimit = hlim; if (iface->dhcpv6) adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER; if (iface->managed >= RELAYD_MANAGED_MFLAG) adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED; if (iface->route_preference < 0) adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW; else if (iface->route_preference > 0) adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH; odhcpd_get_mac(iface, adv.lladdr.data); // If not currently shutting down struct odhcpd_ipaddr addrs[RELAYD_MAX_ADDRS]; ssize_t ipcnt = 0; uint32_t minvalid = UINT32_MAX; bool default_route = false; bool valid_prefix = false; // If not shutdown if (iface->timer_rs.cb) { ipcnt = iface->ia_addr_len; memcpy(addrs, iface->ia_addr, ipcnt * sizeof(*addrs)); // Check default route if (iface->default_router) { default_route = true; if (iface->default_router > 1) valid_prefix = true; } else if (parse_routes(addrs, ipcnt)) default_route = true; } // Construct Prefix Information options size_t cnt = 0; struct in6_addr dns_pref, *dns_addr = &dns_pref; size_t dns_cnt = 1; odhcpd_get_linklocal_interface_address(iface->ifindex, &dns_pref); for (ssize_t i = 0; i < ipcnt; ++i) { struct odhcpd_ipaddr *addr = &addrs[i]; uint32_t preferred = 0; uint32_t valid = 0; if (addr->prefix > 96 || addr->valid <= (uint32_t)now) { char namebuf[INET6_ADDRSTRLEN]; inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf)); syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s", namebuf, addr->prefix, addr->valid, iface->ifname); continue; } struct nd_opt_prefix_info *p = NULL; for (size_t i = 0; i < cnt; ++i) { if (addr->prefix == adv.prefix[i].nd_opt_pi_prefix_len && !odhcpd_bmemcmp(&adv.prefix[i].nd_opt_pi_prefix, &addr->addr, addr->prefix)) p = &adv.prefix[i]; } if (!p) { if (cnt >= ARRAY_SIZE(adv.prefix)) break; p = &adv.prefix[cnt++]; } if (addr->preferred > (uint32_t)now) { preferred = TIME_LEFT(addr->preferred, now); if (iface->ra_useleasetime && preferred > iface->dhcpv4_leasetime) preferred = iface->dhcpv4_leasetime; } valid = TIME_LEFT(addr->valid, now); if (iface->ra_useleasetime) { if (valid > iface->dhcpv4_leasetime) valid = iface->dhcpv4_leasetime; } else if (!preferred && valid < 7200) valid = 0; if (minvalid > valid) minvalid = valid; if (!IN6_IS_ADDR_ULA(&addr->addr) || iface->default_router) valid_prefix = true; odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr, (iface->ra_advrouter) ? 128 : addr->prefix); p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION; p->nd_opt_pi_len = 4; p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix; p->nd_opt_pi_flags_reserved = 0; if (!iface->ra_not_onlink) p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK; if (iface->managed < RELAYD_MANAGED_NO_AFLAG && addr->prefix <= 64) p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO; if (iface->ra_advrouter) p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR; p->nd_opt_pi_preferred_time = htonl(preferred); p->nd_opt_pi_valid_time = htonl(valid); } // Calculate periodic transmit uint32_t maxival; int msecs = calc_adv_interval(iface, minvalid, &maxival); if (default_route) { if (!valid_prefix) { syslog(LOG_WARNING, "A default route is present but there is no public prefix " "on %s thus we don't announce a default route!", iface->ifname); adv.h.nd_ra_router_lifetime = 0; } else adv.h.nd_ra_router_lifetime = htons(calc_ra_lifetime(iface, maxival)); } else adv.h.nd_ra_router_lifetime = 0; syslog(LOG_INFO, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->ifname); // DNS Recursive DNS if (iface->dns_cnt > 0) { dns_addr = iface->dns; dns_cnt = iface->dns_cnt; } if (!dns_addr || IN6_IS_ADDR_UNSPECIFIED(dns_addr)) dns_cnt = 0; struct { uint8_t type; uint8_t len; uint8_t pad; uint8_t pad2; uint32_t lifetime; } dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, 0}; // DNS Search options uint8_t search_buf[256], *search_domain = iface->search; size_t search_len = iface->search_len, search_padded = 0; if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) { int len = dn_comp(_res.dnsrch[0], search_buf, sizeof(search_buf), NULL, NULL); if (len > 0) { search_domain = search_buf; search_len = len; } } if (search_len > 0) search_padded = ((search_len + 7) & (~7)) + 8; struct { uint8_t type; uint8_t len; uint8_t pad; uint8_t pad2; uint32_t lifetime; uint8_t name[]; } *search = alloca(sizeof(*search) + search_padded); search->type = ND_OPT_DNS_SEARCH; search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0; search->pad = 0; search->pad2 = 0; memcpy(search->name, search_domain, search_len); memset(&search->name[search_len], 0, search_padded - search_len); size_t routes_cnt = 0; struct { uint8_t type; uint8_t len; uint8_t prefix; uint8_t flags; uint32_t lifetime; uint32_t addr[4]; } routes[RELAYD_MAX_PREFIXES]; for (ssize_t i = 0; i < ipcnt; ++i) { struct odhcpd_ipaddr *addr = &addrs[i]; if (addr->dprefix > 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now || (addr->dprefix == 64 && addr->prefix == 64)) { continue; // Address not suitable } else if (addr->dprefix > 32) { addr->addr.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1)); } else if (addr->dprefix <= 32) { addr->addr.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1)); addr->addr.s6_addr32[1] = 0; } routes[routes_cnt].type = ND_OPT_ROUTE_INFO; routes[routes_cnt].len = sizeof(*routes) / 8; routes[routes_cnt].prefix = addr->dprefix; routes[routes_cnt].flags = 0; if (iface->route_preference < 0) routes[routes_cnt].flags |= ND_RA_PREF_LOW; else if (iface->route_preference > 0) routes[routes_cnt].flags |= ND_RA_PREF_HIGH; routes[routes_cnt].lifetime = htonl(TIME_LEFT(addr->valid, now)); routes[routes_cnt].addr[0] = addr->addr.s6_addr32[0]; routes[routes_cnt].addr[1] = addr->addr.s6_addr32[1]; routes[routes_cnt].addr[2] = 0; routes[routes_cnt].addr[3] = 0; ++routes_cnt; } search->lifetime = htonl(maxival*10); dns.lifetime = search->lifetime; struct icmpv6_opt adv_interval = { .type = ND_OPT_RTR_ADV_INTERVAL, .len = 1, .data = {0, 0, (maxival*1000) >> 24, (maxival*1000) >> 16, (maxival*1000) >> 8, maxival*1000} }; struct iovec iov[RA_IOV_LEN] = { {&adv, (uint8_t*)&adv.prefix[cnt] - (uint8_t*)&adv}, {&routes, routes_cnt * sizeof(*routes)}, {&dns, (dns_cnt) ? sizeof(dns) : 0}, {dns_addr, dns_cnt * sizeof(*dns_addr)}, {search, search->len * 8}, {&adv_interval, adv_interval.len * 8}}; struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0}; if (from && !IN6_IS_ADDR_UNSPECIFIED(from)) dest.sin6_addr = *from; odhcpd_send(router_event.uloop.fd, &dest, iov, ARRAY_SIZE(iov), iface); return msecs; } static void trigger_router_advert(struct uloop_timeout *event) { struct interface *iface = container_of(event, struct interface, timer_rs); int msecs = send_router_advert(iface, NULL); // Rearm timer if not shut down if (event->cb) uloop_timeout_set(event, msecs); } // Event handler for incoming ICMPv6 packets static void handle_icmpv6(void *addr, void *data, size_t len, struct interface *iface, _unused void *dest) { struct icmp6_hdr *hdr = data; struct sockaddr_in6 *from = addr; if (!router_icmpv6_valid(addr, data, len)) return; if ((iface->ra == RELAYD_SERVER && !iface->master)) { // Server mode if (hdr->icmp6_type == ND_ROUTER_SOLICIT) send_router_advert(iface, &from->sin6_addr); } else if (iface->ra == RELAYD_RELAY) { // Relay mode if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master) forward_router_advertisement(data, len); else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) forward_router_solicitation(odhcpd_get_master_interface()); } } // Forward router solicitation static void forward_router_solicitation(const struct interface *iface) { if (!iface) return; struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}}; struct iovec iov = {&rs, sizeof(rs)}; struct sockaddr_in6 all_routers = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, iface->ifindex}; syslog(LOG_NOTICE, "Sending RS to %s", iface->ifname); odhcpd_send(router_event.uloop.fd, &all_routers, &iov, 1, iface); } // Handler for incoming router solicitations on slave interfaces static void forward_router_advertisement(uint8_t *data, size_t len) { struct nd_router_advert *adv = (struct nd_router_advert *)data; // Rewrite options uint8_t *end = data + len; uint8_t *mac_ptr = NULL; struct in6_addr *dns_ptr = NULL; size_t dns_count = 0; struct icmpv6_opt *opt; icmpv6_for_each_option(opt, &adv[1], end) { if (opt->type == ND_OPT_SOURCE_LINKADDR) { // Store address of source MAC-address mac_ptr = opt->data; } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) { // Check if we have to rewrite DNS dns_ptr = (struct in6_addr*)&opt->data[6]; dns_count = (opt->len - 1) / 2; } } syslog(LOG_NOTICE, "Got a RA"); // Indicate a proxy, however we don't follow the rest of RFC 4389 yet adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY; // Forward advertisement to all slave interfaces struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0}; struct iovec iov = {data, len}; struct interface *iface; list_for_each_entry(iface, &interfaces, head) { if (iface->ra != RELAYD_RELAY || iface->master) continue; // Fixup source hardware address option if (mac_ptr) odhcpd_get_mac(iface, mac_ptr); // If we have to rewrite DNS entries if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) { const struct in6_addr *rewrite = iface->dns; struct in6_addr addr; size_t rewrite_cnt = iface->dns_cnt; if (rewrite_cnt == 0) { if (odhcpd_get_linklocal_interface_address(iface->ifindex, &addr)) continue; // Unable to comply rewrite = &addr; rewrite_cnt = 1; } // Copy over any other addresses for (size_t i = 0; i < dns_count; ++i) { size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1; dns_ptr[i] = rewrite[j]; } } odhcpd_send(router_event.uloop.fd, &all_nodes, &iov, 1, iface); } }