/** * Copyright (C) 2012-2013 Steven Barth * Copyright (C) 2018 Hans Dedecker * * 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" #include "statefiles.h" static void forward_router_solicitation(const struct interface *iface); static void forward_router_advertisement(const struct interface *iface, 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 router_netevent_cb(unsigned long event, struct netevent_handler_info *info); static struct netevent_handler router_netevent_handler = { .cb = router_netevent_cb, }; static FILE *fp_route = NULL; #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX) /* Shutdown helper: close fp_route if open. Safe to call multiple times. */ static void router_shutdown(void) { if (fp_route) { fclose(fp_route); fp_route = NULL; } } int router_init(void) { int ret = 0; if (!(fp_route = fopen("/proc/net/ipv6_route", "r"))) { error("fopen(/proc/net/ipv6_route): %m"); ret = -1; goto out; } if (netlink_add_netevent_handler(&router_netevent_handler) < 0) { error("Failed to add netevent handler"); ret = -1; } atexit(router_shutdown); out: if (ret < 0) router_shutdown(); return ret; } int router_setup_interface(struct interface *iface, bool enable) { int ret = 0; enable = enable && (iface->ra != MODE_DISABLED); if (!fp_route) { ret = -1; goto out; } if (!enable && iface->router_event.uloop.fd >= 0) { if (!iface->master) { uloop_timeout_cancel(&iface->timer_rs); iface->timer_rs.cb = NULL; trigger_router_advert(&iface->timer_rs); } uloop_fd_delete(&iface->router_event.uloop); close(iface->router_event.uloop.fd); iface->router_event.uloop.fd = -1; } else if (enable) { struct icmp6_filter filt; struct ipv6_mreq mreq; int val = 2; if (iface->router_event.uloop.fd < 0) { /* Open ICMPv6 socket */ iface->router_event.uloop.fd = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6); if (iface->router_event.uloop.fd < 0) { error("socket(AF_INET6): %m"); ret = -1; goto out; } if (setsockopt(iface->router_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE, iface->ifname, strlen(iface->ifname)) < 0) { error("setsockopt(SO_BINDTODEVICE): %m"); ret = -1; goto out; } /* Let the kernel compute our checksums */ if (setsockopt(iface->router_event.uloop.fd, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val)) < 0) { error("setsockopt(IPV6_CHECKSUM): %m"); ret = -1; goto out; } /* This is required by RFC 4861 */ val = 255; if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val)) < 0) { error("setsockopt(IPV6_MULTICAST_HOPS): %m"); ret = -1; goto out; } if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val)) < 0) { error("setsockopt(IPV6_UNICAST_HOPS): %m"); ret = -1; goto out; } /* We need to know the source interface */ val = 1; if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val)) < 0) { error("setsockopt(IPV6_RECVPKTINFO): %m"); ret = -1; goto out; } if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val)) < 0) { error("setsockopt(IPV6_RECVHOPLIMIT): %m"); ret = -1; goto out; } /* Don't loop back */ val = 0; if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val)) < 0) { error("setsockopt(IPV6_MULTICAST_LOOP): %m"); ret = -1; goto out; } /* Filter ICMPv6 package types */ ICMP6_FILTER_SETBLOCKALL(&filt); ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt); ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt); if (setsockopt(iface->router_event.uloop.fd, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt)) < 0) { error("setsockopt(ICMP6_FILTER): %m"); ret = -1; goto out; } iface->router_event.handle_dgram = handle_icmpv6; iface->ra_sent = 0; odhcpd_register(&iface->router_event); } else { uloop_timeout_cancel(&iface->timer_rs); iface->timer_rs.cb = NULL; memset(&mreq, 0, sizeof(mreq)); mreq.ipv6mr_interface = iface->ifindex; inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr); setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)); inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr); setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)); } memset(&mreq, 0, sizeof(mreq)); mreq.ipv6mr_interface = iface->ifindex; inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &mreq.ipv6mr_multiaddr); if (iface->ra == MODE_RELAY && iface->master) { inet_pton(AF_INET6, ALL_IPV6_NODES, &mreq.ipv6mr_multiaddr); forward_router_solicitation(iface); } else if (iface->ra == MODE_SERVER) { iface->timer_rs.cb = trigger_router_advert; uloop_timeout_set(&iface->timer_rs, 1000); } if (setsockopt(iface->router_event.uloop.fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) { ret = -1; error("setsockopt(IPV6_ADD_MEMBERSHIP): %m"); goto out; } } out: if (ret < 0 && iface->router_event.uloop.fd >= 0) { if (iface->router_event.uloop.registered) uloop_fd_delete(&iface->router_event.uloop); close(iface->router_event.uloop.fd); iface->router_event.uloop.fd = -1; } return ret; } static void router_netevent_cb(unsigned long event, struct netevent_handler_info *info) { struct interface *iface; switch (event) { case NETEV_IFINDEX_CHANGE: iface = info->iface; if (iface && iface->router_event.uloop.fd >= 0) { if (iface->router_event.uloop.registered) uloop_fd_delete(&iface->router_event.uloop); close(iface->router_event.uloop.fd); iface->router_event.uloop.fd = -1; } break; case NETEV_ROUTE6_ADD: case NETEV_ROUTE6_DEL: if (info->rt.dst_len) break; avl_for_each_element(&interfaces, iface, avl) { if (iface->ra == MODE_SERVER && !iface->master) uloop_timeout_set(&iface->timer_rs, 1000); } break; case NETEV_ADDR6LIST_CHANGE: iface = info->iface; if (iface && iface->ra == MODE_SERVER && !iface->master) uloop_timeout_set(&iface->timer_rs, 1000); break; default: break; } } 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) { struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix_len = 0, .dprefix_len = 0, .preferred_lt = 0, .valid_lt = 0 }; bool found_default = false; char line[512], ifname[16]; rewind(fp_route); 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.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix_len, &rflags) && p.prefix_len > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) { // Find source prefixes by scanning through unreachable-routes p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]); p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]); for (ssize_t i = 0; i < len; ++i) { if (n[i].prefix_len <= 64 && n[i].prefix_len >= p.prefix_len && !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix_len)) { n[i].dprefix_len = p.prefix_len; break; } } } } return found_default; } static int calc_adv_interval(struct interface *iface, uint32_t lowest_found_lifetime, uint32_t *maxival) { uint32_t minival = iface->ra_mininterval; int msecs; *maxival = iface->ra_maxinterval; if (*maxival > lowest_found_lifetime) *maxival = lowest_found_lifetime; odhcpd_urandom(&msecs, sizeof(msecs)); msecs = (labs(msecs) % ((*maxival != minival) ? (*maxival - minival)*1000 : 500)) + minival*1000; /* RFC 2461 6.2.4 For the first MAX_INITIAL_RTR_ADVERTISEMENTS advertisements * if the timer is bigger than MAX_INITIAL_RTR_ADVERT_INTERVAL it should be * set to MAX_INITIAL_RTR_ADVERT_INTERVAL * Off by one as an initial interval timer has already expired */ if ((iface->ra_sent + 1) < MaxInitialRtAdvs && msecs > MaxInitialRtrAdvInterval*1000) msecs = MaxInitialRtrAdvInterval*1000; return msecs; } static uint32_t calc_ra_lifetime(struct interface *iface, uint32_t maxival) { uint32_t lifetime = iface->max_preferred_lifetime; if (iface->ra_lifetime > 0) { lifetime = iface->ra_lifetime; } if (lifetime > 0 && lifetime < maxival) lifetime = maxival; else if (lifetime > RouterLifetime) lifetime = RouterLifetime; return lifetime; } enum { IOV_RA_ADV=0, IOV_RA_PFXS, IOV_RA_ROUTES, IOV_RA_DNS, IOV_RA_SEARCH, IOV_RA_PREF64, IOV_RA_DNR, IOV_RA_ADV_INTERVAL, IOV_RA_CAPT_PORTAL, IOV_RA_TOTAL, }; struct adv_msg { struct nd_router_advert h; struct icmpv6_opt lladdr; struct nd_opt_mtu mtu; }; struct nd_opt_dns_server { uint8_t type; uint8_t len; uint8_t pad; uint8_t pad2; uint32_t lifetime; struct in6_addr addr[]; }; struct nd_opt_search_list { uint8_t type; uint8_t len; uint16_t reserved; uint32_t lifetime; uint8_t name[]; } _o_packed; struct nd_opt_route_info { uint8_t type; uint8_t len; uint8_t prefix_len; uint8_t flags; uint32_t lifetime; uint32_t addr[4]; }; struct nd_opt_pref64_info { uint8_t type; uint8_t len; uint16_t lifetime_plc; uint32_t prefix[3]; }; struct nd_opt_dnr_info { uint8_t type; uint8_t len; uint16_t priority; uint32_t lifetime; uint16_t adn_len; uint8_t body[]; }; struct nd_opt_capt_portal { uint8_t type; uint8_t len; uint8_t data[]; }; /* IPv6 RA PIOs */ inline static int router_compare_pio_addr(const struct ra_pio *pio, const struct odhcpd_ipaddr *addr) { uint8_t cmp_len = max(64, max(pio->length, addr->prefix_len)); return odhcpd_bmemcmp(&pio->prefix, &addr->addr.in6, cmp_len); } static struct ra_pio *router_find_ra_pio(struct interface *iface, struct odhcpd_ipaddr *addr) { for (size_t i = 0; i < iface->pio_cnt; i++) { struct ra_pio *cur_pio = &iface->pios[i]; if (!router_compare_pio_addr(cur_pio, addr)) return cur_pio; } return NULL; } static void router_add_ra_pio(struct interface *iface, struct odhcpd_ipaddr *addr) { char ipv6_str[INET6_ADDRSTRLEN]; struct ra_pio *new_pios, *pio; pio = router_find_ra_pio(iface, addr); if (pio) { if (memcmp(&pio->prefix, &addr->addr.in6, sizeof(struct in6_addr)) != 0 || pio->length != addr->prefix_len) { char new_ipv6_str[INET6_ADDRSTRLEN]; iface->pio_update = true; warn("rfc9096: %s: changed %s/%u -> %s/%u", iface->ifname, inet_ntop(AF_INET6, &pio->prefix, ipv6_str, sizeof(ipv6_str)), pio->length, inet_ntop(AF_INET6, &addr->addr.in6, new_ipv6_str, sizeof(new_ipv6_str)), addr->prefix_len); memcpy(&pio->prefix, &addr->addr.in6, sizeof(struct in6_addr)); pio->length = addr->prefix_len; } if (pio->lifetime) { pio->lifetime = 0; iface->pio_update = true; warn("rfc9096: %s: renew %s/%u", iface->ifname, inet_ntop(AF_INET6, &pio->prefix, ipv6_str, sizeof(ipv6_str)), pio->length); } return; } new_pios = realloc(iface->pios, sizeof(struct ra_pio) * (iface->pio_cnt + 1)); if (!new_pios) return; iface->pios = new_pios; pio = &iface->pios[iface->pio_cnt]; iface->pio_cnt++; memcpy(&pio->prefix, &addr->addr.in6, sizeof(struct in6_addr)); pio->length = addr->prefix_len; pio->lifetime = 0; iface->pio_update = true; info("rfc9096: %s: add %s/%u", iface->ifname, inet_ntop(AF_INET6, &pio->prefix, ipv6_str, sizeof(ipv6_str)), pio->length); } static void router_clear_duplicated_ra_pio(struct interface *iface) { size_t pio_cnt = iface->pio_cnt; char ipv6_str[INET6_ADDRSTRLEN]; for (size_t i = 0; i < iface->pio_cnt; i++) { struct ra_pio *pio_a = &iface->pios[i]; size_t j = i + 1; while (j < iface->pio_cnt) { struct ra_pio *pio_b = &iface->pios[j]; if (pio_a->length == pio_b->length && !memcmp(&pio_a->prefix, &pio_b->prefix, sizeof(struct in6_addr))) { warn("rfc9096: %s: clear duplicated %s/%u", iface->ifname, inet_ntop(AF_INET6, &pio_a->prefix, ipv6_str, sizeof(ipv6_str)), pio_a->length); iface->pios[j] = iface->pios[iface->pio_cnt - 1]; iface->pio_cnt--; } else { j++; } } } if (iface->pio_cnt != pio_cnt) { struct ra_pio *new_pios = realloc(iface->pios, sizeof(struct ra_pio) * iface->pio_cnt); if (new_pios) iface->pios = new_pios; } } static void router_clear_expired_ra_pio(time_t now, struct interface *iface) { size_t i = 0, pio_cnt = iface->pio_cnt; char ipv6_str[INET6_ADDRSTRLEN]; while (i < iface->pio_cnt) { struct ra_pio *cur_pio = &iface->pios[i]; if (ra_pio_expired(cur_pio, now)) { info("rfc9096: %s: clear expired %s/%u", iface->ifname, inet_ntop(AF_INET6, &cur_pio->prefix, ipv6_str, sizeof(ipv6_str)), cur_pio->length); iface->pios[i] = iface->pios[iface->pio_cnt - 1]; iface->pio_cnt--; } else { i++; } } if (!iface->pio_cnt) { free(iface->pios); iface->pios = NULL; } else if (iface->pio_cnt != pio_cnt) { struct ra_pio *new_pios = realloc(iface->pios, sizeof(struct ra_pio) * iface->pio_cnt); if (new_pios) iface->pios = new_pios; } } static void router_stale_ra_pio(struct interface *iface, struct odhcpd_ipaddr *addr, time_t now) { struct ra_pio *pio = router_find_ra_pio(iface, addr); char ipv6_str[INET6_ADDRSTRLEN]; if (!pio || pio->lifetime) return; pio->lifetime = now + iface->max_valid_lifetime; iface->pio_update = true; warn("rfc9096: %s: stale %s/%u", iface->ifname, inet_ntop(AF_INET6, &pio->prefix, ipv6_str, sizeof(ipv6_str)), pio->length); } /* Router Advert server mode */ static int send_router_advert(struct interface *iface, const struct in6_addr *from) { time_t now = odhcpd_time(); struct odhcpd_ipaddr *addrs = NULL; struct adv_msg adv; struct nd_opt_prefix_info *pfxs = NULL; struct nd_opt_dns_server *dns = NULL; struct nd_opt_search_list *search = NULL; struct nd_opt_route_info *routes = NULL; struct nd_opt_pref64_info *pref64 = NULL; struct nd_opt_dnr_info *dnrs = NULL; struct nd_opt_adv_interval adv_interval; struct nd_opt_capt_portal *capt_portal = NULL; struct iovec iov[IOV_RA_TOTAL]; struct sockaddr_in6 dest; size_t dns_sz = 0, search_sz = 0, pref64_sz = 0, dnrs_sz = 0; size_t pfxs_cnt = 0, routes_cnt = 0; size_t total_addr_cnt = 0, valid_addr_cnt = 0; size_t capt_portal_sz = 0; /* * lowest_found_lifetime stores the lowest lifetime of all prefixes; * necessary to find longest adv interval necessary * for shortest lived prefix */ uint32_t lowest_found_lifetime = UINT32_MAX, highest_found_lifetime = 0, maxival, ra_lifetime; int msecs, hlim = iface->ra_hoplimit; bool default_route = false; bool valid_prefix = false; char buf[INET6_ADDRSTRLEN]; router_clear_expired_ra_pio(now, iface); memset(&adv, 0, sizeof(adv)); adv.h.nd_ra_type = ND_ROUTER_ADVERT; if (hlim == 0) hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit"); if (hlim > 0) adv.h.nd_ra_curhoplimit = hlim; adv.h.nd_ra_flags_reserved = iface->ra_flags; 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; if (iface->dhcpv6 != MODE_DISABLED && iface->dhcpv6_pd && iface->dhcpv6_pd_preferred) { /* RFC9762 § 5 * If the network desires to delegate prefixes to devices that support * DHCPv6 prefix delegation but do not support the P flag, it SHOULD * also set the M or O bits in the RA to 1 */ adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED; } adv.h.nd_ra_reachable = htonl(iface->ra_reachabletime); adv.h.nd_ra_retransmit = htonl(iface->ra_retranstime); adv.lladdr.type = ND_OPT_SOURCE_LINKADDR; adv.lladdr.len = 1; odhcpd_get_mac(iface, adv.lladdr.data); adv.mtu.nd_opt_mtu_type = ND_OPT_MTU; adv.mtu.nd_opt_mtu_len = 1; adv.mtu.nd_opt_mtu_mtu = htonl(iface->ra_mtu); iov[IOV_RA_ADV].iov_base = &adv; iov[IOV_RA_ADV].iov_len = sizeof(adv); valid_addr_cnt = (iface->timer_rs.cb /* if not shutdown */ ? iface->addr6_len : 0); // check ra_default if (iface->default_router) { default_route = true; if (iface->default_router > 1) valid_prefix = true; } if (valid_addr_cnt + iface->pio_cnt) { addrs = alloca(sizeof(*addrs) * (valid_addr_cnt + iface->pio_cnt)); if (valid_addr_cnt) { memcpy(addrs, iface->addr6, sizeof(*addrs) * valid_addr_cnt); total_addr_cnt = valid_addr_cnt; /* Check default route */ if (!default_route && parse_routes(addrs, valid_addr_cnt)) default_route = true; } for (size_t i = 0; i < iface->pio_cnt; i++) { struct ra_pio *cur_pio = &iface->pios[i]; bool pio_found = false; for (size_t j = 0; j < valid_addr_cnt; j++) { struct odhcpd_ipaddr *cur_addr = &addrs[j]; if (!router_compare_pio_addr(cur_pio, cur_addr)) { pio_found = true; break; } } if (!pio_found) { struct odhcpd_ipaddr *addr = &addrs[total_addr_cnt]; memcpy(&addr->addr.in6, &cur_pio->prefix, sizeof(addr->addr.in6)); addr->prefix_len = cur_pio->length; addr->preferred_lt = 0; addr->valid_lt = (uint32_t) (now + ND_VALID_LIMIT); total_addr_cnt++; } } } /* Construct Prefix Information options */ if (total_addr_cnt > 0) { pfxs = alloca(total_addr_cnt * sizeof(*pfxs)); memset(pfxs, 0, total_addr_cnt * sizeof(*pfxs)); } for (size_t i = 0; i < total_addr_cnt; ++i) { struct odhcpd_ipaddr *addr = &addrs[i]; struct nd_opt_prefix_info *p = NULL; uint32_t preferred_lt = 0; uint32_t valid_lt = 0; if (addr->prefix_len > 96 || (i < valid_addr_cnt && addr->valid_lt <= (uint32_t)now)) { info("Address %s (prefix %d, valid-lifetime %u) not suitable as RA prefix on %s", inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->prefix_len, addr->valid_lt, iface->name); continue; } if (ADDR_MATCH_PIO_FILTER(addr, iface)) { info("Address %s filtered out as RA prefix on %s", inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), iface->name); continue; /* PIO filtered out of this RA */ } for (size_t j = 0; j < pfxs_cnt; ++j) { if (addr->prefix_len == pfxs[j].nd_opt_pi_prefix_len && !odhcpd_bmemcmp(&pfxs[j].nd_opt_pi_prefix, &addr->addr.in6, addr->prefix_len)) p = &pfxs[j]; } if (!p) p = &pfxs[pfxs_cnt++]; if (addr->preferred_lt > (uint32_t)now) { preferred_lt = TIME_LEFT(addr->preferred_lt, now); if (iface->max_preferred_lifetime && preferred_lt > iface->max_preferred_lifetime) { preferred_lt = iface->max_preferred_lifetime; } } if (addr->valid_lt > (uint32_t)now) { valid_lt = TIME_LEFT(addr->valid_lt, now); if (iface->max_valid_lifetime && valid_lt > iface->max_valid_lifetime) valid_lt = iface->max_valid_lifetime; } if (preferred_lt > valid_lt) { /* * RFC4861 § 6.2.1 * This value [AdvPreferredLifetime] MUST NOT be larger than * AdvValidLifetime. */ preferred_lt = valid_lt; } if (lowest_found_lifetime > valid_lt) lowest_found_lifetime = valid_lt; if ((!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router) && valid_lt) valid_prefix = true; if (!IN6_IS_ADDR_ULA(&addr->addr.in6) && valid_lt) { if (highest_found_lifetime < valid_lt) highest_found_lifetime = valid_lt; } odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr.in6, (iface->ra_advrouter) ? 128 : addr->prefix_len); p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION; p->nd_opt_pi_len = 4; p->nd_opt_pi_prefix_len = (addr->prefix_len < 64) ? 64 : addr->prefix_len; /* RFC9762 DHCPv6-PD Preferred Flag § 6: * Routers SHOULD set the P flag to zero by default... */ 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->ra_slaac && addr->prefix_len <= 64) p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO; if (iface->dhcpv6 != MODE_DISABLED && iface->dhcpv6_pd && iface->dhcpv6_pd_preferred) /* RFC9762 DHCPv6-PD Preferred Flag * We can run both SLAAC and DHCPv6-PD. * §6: * "Routers MUST allow the P flag to be configured separately from the A flag. * ...en/disabling the P flag MUST NOT trigger automatic changes in the A flag * value set by the router." */ p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_PD_PREFERRED; if (iface->ra_advrouter) // RFC6275, §7.2 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR; if (i >= valid_addr_cnt || !preferred_lt) { /* * RFC9096 § 3.5 * * - Any prefixes that were previously advertised by the CE router * via PIOs in RA messages, but that have now become stale, MUST * be advertised with PIOs that have the "Valid Lifetime" and the * "Preferred Lifetime" set to 0 and the "A" and "L" bits * unchanged. */ p->nd_opt_pi_preferred_time = 0; p->nd_opt_pi_valid_time = 0; router_stale_ra_pio(iface, addr, now); } else { p->nd_opt_pi_preferred_time = htonl(preferred_lt); p->nd_opt_pi_valid_time = htonl(valid_lt); router_add_ra_pio(iface, addr); } } router_clear_duplicated_ra_pio(iface); iov[IOV_RA_PFXS].iov_base = pfxs; iov[IOV_RA_PFXS].iov_len = pfxs_cnt * sizeof(*pfxs); /* Calculate periodic transmit */ msecs = calc_adv_interval(iface, lowest_found_lifetime, &maxival); ra_lifetime = calc_ra_lifetime(iface, maxival); if (!highest_found_lifetime) highest_found_lifetime = ra_lifetime; if (!iface->have_link_local) { notice("Skip sending a RA on %s as no link local address is available", iface->name); goto out; } if (default_route && valid_prefix) { adv.h.nd_ra_router_lifetime = htons(ra_lifetime < UINT16_MAX ? ra_lifetime : UINT16_MAX); } else { adv.h.nd_ra_router_lifetime = 0; if (default_route) warn("A default route is present but there is no public prefix " "on %s thus we announce no default route by setting ra_lifetime to 0!", iface->name); else warn("No default route present, setting ra_lifetime to 0!"); } debug("Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name); /* Recursive DNS Server aka RDNSS; RFC8106, §5.1 */ if (iface->ra_dns) { struct in6_addr *dns_addrs6 = NULL, dns_addr6; size_t dns_addrs6_cnt = 0; if (iface->dns_addrs6_cnt > 0) { dns_addrs6 = iface->dns_addrs6; dns_addrs6_cnt = iface->dns_addrs6_cnt; } else if (!odhcpd_get_interface_dns_addr6(iface, &dns_addr6)) { dns_addrs6 = &dns_addr6; dns_addrs6_cnt = 1; } if (dns_addrs6_cnt) { dns_sz = sizeof(*dns) + dns_addrs6_cnt * sizeof(*dns_addrs6); dns = alloca(dns_sz); memset(dns, 0, dns_sz); dns->type = ND_OPT_RECURSIVE_DNS; dns->len = 1 + (2 * dns_addrs6_cnt); dns->lifetime = htonl(highest_found_lifetime); memcpy(dns->addr, dns_addrs6, dns_addrs6_cnt * sizeof(*dns_addrs6)); } } iov[IOV_RA_DNS].iov_base = dns; iov[IOV_RA_DNS].iov_len = dns_sz; /* DNS Search List aka DNSSL; RFC8106, §5.2 */ if (iface->ra_dns && iface->dns_search_len > 0) { search_sz = sizeof(*search) + ((iface->dns_search_len + 7) & ~7); search = alloca(search_sz); *search = (struct nd_opt_search_list) { .type = ND_OPT_DNS_SEARCH, .len = search_sz / 8, .reserved = 0, .lifetime = htonl(highest_found_lifetime), }; memcpy(search->name, iface->dns_search, iface->dns_search_len); } iov[IOV_RA_SEARCH].iov_base = search; iov[IOV_RA_SEARCH].iov_len = search_sz; if (iface->pref64_length) { /* RFC 8781 § 4.1 rounding up lifetime to multiple of 8 */ uint16_t pref64_lifetime = ra_lifetime < (UINT16_MAX - 7) ? ra_lifetime + 7 : (UINT16_MAX - 7); pref64_sz = sizeof(*pref64); pref64 = alloca(pref64_sz); pref64->type = ND_OPT_PREF64; pref64->len = 2; pref64->lifetime_plc = htons((0xfff8 & pref64_lifetime) | (0x7 & iface->pref64_plc)); memcpy(pref64->prefix, iface->pref64_prefix, sizeof(pref64->prefix)); } iov[IOV_RA_PREF64].iov_base = pref64; iov[IOV_RA_PREF64].iov_len = pref64_sz; if (iface->dnr_cnt) { size_t dnr_sz[iface->dnr_cnt]; for (unsigned i = 0; i < iface->dnr_cnt; i++) { dnr_sz[i] = sizeof(struct nd_opt_dnr_info) + iface->dnr[i].adn_len; if (iface->dnr[i].addr6_cnt > 0 || iface->dnr[i].svc_len > 0) { dnr_sz[i] += 2 + iface->dnr[i].addr6_cnt * sizeof(struct in6_addr); dnr_sz[i] += 2 + iface->dnr[i].svc_len; } dnr_sz[i] = (dnr_sz[i] + 7) & ~7; dnrs_sz += dnr_sz[i]; } /* dnrs are sized in multiples of 8, so each dnr should be aligned */ dnrs = alloca(dnrs_sz); memset(dnrs, 0, dnrs_sz); uint8_t *pos = (uint8_t *)dnrs; for (unsigned i = 0; i < iface->dnr_cnt; pos += dnr_sz[i], i++) { struct nd_opt_dnr_info *dnr = (struct nd_opt_dnr_info *)pos; size_t dnr_addr6_sz = iface->dnr[i].addr6_cnt * sizeof(struct in6_addr); uint8_t *tmp = dnr->body; dnr->type = ND_OPT_DNR; dnr->len = dnr_sz[i] / 8; dnr->priority = htons(iface->dnr[i].priority); if (iface->dnr[i].lifetime_set) dnr->lifetime = htonl(iface->dnr[i].lifetime); else dnr->lifetime = htonl(highest_found_lifetime); dnr->adn_len = htons(iface->dnr[i].adn_len); memcpy(tmp, iface->dnr[i].adn, iface->dnr[i].adn_len); tmp += iface->dnr[i].adn_len; *(tmp++) = dnr_addr6_sz >> 8; *(tmp++) = dnr_addr6_sz & 0xff; memcpy(tmp, iface->dnr[i].addr6, dnr_addr6_sz); tmp += dnr_addr6_sz; *(tmp++) = iface->dnr[i].svc_len >> 8; *(tmp++) = iface->dnr[i].svc_len & 0xff; memcpy(tmp, iface->dnr[i].svc, iface->dnr[i].svc_len); } } iov[IOV_RA_DNR].iov_base = dnrs; iov[IOV_RA_DNR].iov_len = dnrs_sz; /* * RFC7084 § 4.3 : * L-3: An IPv6 CE router MUST advertise itself as a router for the * delegated prefix(es) (and ULA prefix if configured to provide * ULA addressing) using the "Route Information Option" specified * in Section 2.3 of [RFC4191]. This advertisement is * independent of having or not having IPv6 connectivity on the * WAN interface. */ if (valid_addr_cnt > 0) { routes = alloca(valid_addr_cnt * sizeof(*routes)); memset(routes, 0, valid_addr_cnt * sizeof(*routes)); } for (size_t i = 0; i < valid_addr_cnt; ++i) { struct odhcpd_ipaddr *addr = &addrs[i]; uint32_t valid_lt; if (addr->dprefix_len >= 64 || addr->dprefix_len == 0 || addr->valid_lt <= (uint32_t)now) { debug("Address %s (dprefix %d, valid-lifetime %u) not suitable as RA route on %s", inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), addr->dprefix_len, addr->valid_lt, iface->name); continue; } if (ADDR_MATCH_PIO_FILTER(addr, iface)) { debug("Address %s filtered out as RA route on %s", inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)), iface->name); continue; } if (addr->dprefix_len > 32) { addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix_len)) - 1)); } else if (addr->dprefix_len <= 32) { addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix_len)) - 1)); addr->addr.in6.s6_addr32[1] = 0; } routes[routes_cnt].type = ND_OPT_ROUTE_INFO; routes[routes_cnt].len = sizeof(*routes) / 8; routes[routes_cnt].prefix_len = addr->dprefix_len; 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; valid_lt = TIME_LEFT(addr->valid_lt, now); if (iface->max_valid_lifetime && valid_lt > iface->max_valid_lifetime) valid_lt = iface->max_valid_lifetime; routes[routes_cnt].lifetime = htonl(valid_lt); routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0]; routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1]; routes[routes_cnt].addr[2] = 0; routes[routes_cnt].addr[3] = 0; routes_cnt++; } iov[IOV_RA_ROUTES].iov_base = routes; iov[IOV_RA_ROUTES].iov_len = routes_cnt * sizeof(*routes); memset(&adv_interval, 0, sizeof(adv_interval)); adv_interval.nd_opt_adv_interval_type = ND_OPT_RTR_ADV_INTERVAL; adv_interval.nd_opt_adv_interval_len = 1; adv_interval.nd_opt_adv_interval_ival = htonl(maxival*1000); iov[IOV_RA_ADV_INTERVAL].iov_base = &adv_interval; iov[IOV_RA_ADV_INTERVAL].iov_len = adv_interval.nd_opt_adv_interval_len * 8; /* RFC 8910 Captive Portal */ if (iface->captive_portal_uri_len > 0) { /* compute pad so that (header + data + pad) is a multiple of 8 */ capt_portal_sz = (sizeof(struct nd_opt_capt_portal) + iface->captive_portal_uri_len + 7) & ~7; capt_portal = alloca(capt_portal_sz); memset(capt_portal, 0, capt_portal_sz); capt_portal->type = ND_OPT_CAPTIVE_PORTAL; capt_portal->len = capt_portal_sz / 8; memcpy(capt_portal->data, iface->captive_portal_uri, iface->captive_portal_uri_len); /* remaining padding bytes already set to 0x00 */ } iov[IOV_RA_CAPT_PORTAL].iov_base = capt_portal; iov[IOV_RA_CAPT_PORTAL].iov_len = capt_portal_sz; memset(&dest, 0, sizeof(dest)); dest.sin6_family = AF_INET6; if (from && !IN6_IS_ADDR_UNSPECIFIED(from)) dest.sin6_addr = *from; else inet_pton(AF_INET6, ALL_IPV6_NODES, &dest.sin6_addr); debug("Sending a RA on %s", iface->name); if (odhcpd_try_send_with_src(iface->router_event.uloop.fd, &dest, iov, ARRAY_SIZE(iov), iface) > 0) { iface->ra_sent++; statefiles_write_prefix_information(iface); } out: 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, _o_unused void *dest) { struct icmp6_hdr *hdr = data; struct sockaddr_in6 *from = addr; if (!router_icmpv6_valid(addr, data, len)) return; if ((iface->ra == MODE_SERVER && !iface->master)) { /* Server mode */ if (hdr->icmp6_type == ND_ROUTER_SOLICIT) send_router_advert(iface, &from->sin6_addr); } else if (iface->ra == MODE_RELAY) { /* Relay mode */ if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master) { struct interface *c; avl_for_each_element(&interfaces, c, avl) { if (!c->master || c->ra != MODE_RELAY) continue; forward_router_solicitation(c); } } else if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master) forward_router_advertisement(iface, data, len); } } /* Forward a router solicitation from slave to master interface */ static void forward_router_solicitation(const struct interface *iface) { struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}}; struct iovec iov = {&rs, sizeof(rs)}; struct sockaddr_in6 all_routers; if (!iface) return; memset(&all_routers, 0, sizeof(all_routers)); all_routers.sin6_family = AF_INET6; inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &all_routers.sin6_addr); all_routers.sin6_scope_id = iface->ifindex; notice("Sending RS to %s", iface->name); odhcpd_send(iface->router_event.uloop.fd, &all_routers, &iov, 1, iface); } /* Forward a router advertisement from master to slave interfaces */ static void forward_router_advertisement(const struct interface *iface, uint8_t *data, size_t len) { struct nd_router_advert *adv = (struct nd_router_advert *)data; struct sockaddr_in6 all_nodes; struct icmpv6_opt *opt; struct interface *c; struct iovec iov = { .iov_base = data, .iov_len = len }; /* Rewrite options */ uint8_t *end = data + len; uint8_t *mac_ptr = NULL; struct in6_addr *dns_addrs6 = NULL; size_t dns_addrs6_cnt = 0; // MTU option struct nd_opt_mtu *mtu_opt = NULL; uint32_t ingress_mtu_val = 0; /* PIO L/A/R/P flag and RA M/O Flags */ uint8_t ra_flags; size_t pio_count = 0; struct fwd_pio_flags { uint8_t *ptr; uint8_t flags; } *pio_flags = NULL; icmpv6_for_each_option(opt, &adv[1], end) { /* check our packet content is not truncated */ if (opt->len == 0 || (uint8_t *)opt + opt->len * 8 > end) { error("Ingress RA packet option for relaying has incorrect length"); return; } switch(opt->type) { case ND_OPT_PREFIX_INFORMATION: pio_count++; break; } } if (pio_count > 0) { pio_flags = alloca(sizeof(*pio_flags) * pio_count); pio_count = 0; } /* Parse existing options */ icmpv6_for_each_option(opt, &adv[1], end) { switch (opt->type) { case ND_OPT_SOURCE_LINKADDR: mac_ptr = opt->data; break; case ND_OPT_RECURSIVE_DNS: if (opt->len > 1) { dns_addrs6 = (struct in6_addr *)&opt->data[6]; dns_addrs6_cnt = (opt->len - 1) / 2; } break; case ND_OPT_MTU: if (opt->len == 1 && (uint8_t *)opt + sizeof(struct nd_opt_mtu) <= end) { mtu_opt = (struct nd_opt_mtu *)opt; ingress_mtu_val = ntohl(mtu_opt->nd_opt_mtu_mtu); } break; case ND_OPT_PREFIX_INFORMATION: /* Store options for each PIO */ pio_flags[pio_count].ptr = &opt->data[1]; pio_flags[pio_count].flags = opt->data[1]; pio_count++; break; } } info("Got a RA on %s", iface->name); /* Indicate a proxy, however we don't follow the rest of RFC 4389 yet * store original upstream RA state */ ra_flags = adv->nd_ra_flags_reserved | ND_RA_FLAG_PROXY; /* Forward advertisement to all slave interfaces */ memset(&all_nodes, 0, sizeof(all_nodes)); all_nodes.sin6_family = AF_INET6; inet_pton(AF_INET6, ALL_IPV6_NODES, &all_nodes.sin6_addr); avl_for_each_element(&interfaces, c, avl) { if (c->ra != MODE_RELAY || c->master) continue; /* Fixup source hardware address option */ if (mac_ptr) odhcpd_get_mac(c, mac_ptr); if (pio_count > 0) debug("RA forward: Rewriting RA PIO flags"); for (size_t i = 0; i < pio_count; i++) { /* restore the flags byte to its upstream state before applying per-interface policy */ *pio_flags[i].ptr = pio_flags[i].flags; /* ensure L flag (on-link) cleared; relayed == not on-link */ *pio_flags[i].ptr &= ~ND_OPT_PI_FLAG_ONLINK; /* upstream no SLAAC, downstream no SLAAC: no change * upstream no SLAAC, downstream SLAAC: no change * upstream SLAAC, downstream SLAAC: no change * upstream SLAAC, downstream no SLAAC: clear flag * Why? We shall not SLAAC downstream if upstream disables it. Sometimes * we just inform about a prefix for DHCPv6 and routing info. */ if (!c->ra_slaac) *pio_flags[i].ptr &= ~ND_OPT_PI_FLAG_AUTO;/* ensure A flag cleared */ /* we have no opinion on the R flag - it can be forwarded */ if (c->dhcpv6 == MODE_DISABLED || !c->dhcpv6_pd || !c->dhcpv6_pd_preferred) *pio_flags[i].ptr &= ~ND_OPT_PI_FLAG_PD_PREFERRED;/* ensure P flag (DHCPv6-PD) cleared */ } /* Apply per-interface modifications of upstream RA state */ adv->nd_ra_flags_reserved = ra_flags; /* Rewrite M/O flags unless we relay DHCPv6 */ if (c->dhcpv6 != MODE_RELAY) { /* Clear the relayed M/O bits */ adv->nd_ra_flags_reserved &= ~(ND_RA_FLAG_MANAGED | ND_RA_FLAG_OTHER); /* Apply the locally configured ra_flags for M and O */ adv->nd_ra_flags_reserved |= c->ra_flags & (ND_RA_FLAG_MANAGED | ND_RA_FLAG_OTHER); } /* If we have to rewrite DNS entries */ if (c->always_rewrite_dns && dns_addrs6 && dns_addrs6_cnt > 0) { const struct in6_addr *rewrite = c->dns_addrs6; struct in6_addr addr; size_t rewrite_cnt = c->dns_addrs6_cnt; if (rewrite_cnt == 0) { if (odhcpd_get_interface_dns_addr6(c, &addr)) continue; /* Unable to comply */ rewrite = &addr; rewrite_cnt = 1; } /* Copy over any other addresses */ for (size_t i = 0; i < dns_addrs6_cnt; ++i) { size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1; dns_addrs6[i] = rewrite[j]; } } /* Rewrite MTU option if local RA MTU is configured */ if (c->ra_mtu && mtu_opt) { if (ingress_mtu_val != c->ra_mtu) { debug("Rewriting RA MTU from %u to %u on %s", ingress_mtu_val, c->ra_mtu, c->name); mtu_opt->nd_opt_mtu_mtu = htonl(c->ra_mtu); } } info("Forward a RA on %s", c->name); odhcpd_send(c->router_event.uloop.fd, &all_nodes, &iov, 1, c); } }