/** * 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 #include #include #include #include #include #include #include #include #include #include "odhcpd.h" static int ioctl_sock; static int rtnl_socket = -1; static int rtnl_seq = 0; static int urandom_fd = -1; static void sighandler(_unused int signal) { uloop_end(); } int main() { openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON); setlogmask(LOG_UPTO(LOG_WARNING)); uloop_init(); if (getuid() != 0) { syslog(LOG_ERR, "Must be run as root!"); return 2; } ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0); if ((rtnl_socket = odhcpd_open_rtnl()) < 0) { syslog(LOG_ERR, "Unable to open socket: %s", strerror(errno)); return 2; } if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0) return 4; signal(SIGUSR1, SIG_IGN); signal(SIGINT, sighandler); signal(SIGTERM, sighandler); if (init_router()) return 4; if (init_dhcpv6()) return 4; if (init_ndp()) return 4; if (init_dhcpv4()) return 4; odhcpd_run(); return 0; } int odhcpd_open_rtnl(void) { int sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE); // Connect to the kernel netlink interface struct sockaddr_nl nl = {.nl_family = AF_NETLINK}; if (connect(sock, (struct sockaddr*)&nl, sizeof(nl))) { syslog(LOG_ERR, "Failed to connect to kernel rtnetlink: %s", strerror(errno)); return -1; } return sock; } // Read IPv6 MTU for interface int odhcpd_get_interface_config(const char *ifname, const char *what) { char buf[64]; const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/%s"; snprintf(buf, sizeof(buf), sysctl_pattern, ifname, what); int fd = open(buf, O_RDONLY); ssize_t len = read(fd, buf, sizeof(buf) - 1); close(fd); if (len < 0) return -1; buf[len] = 0; return atoi(buf); } // Read IPv6 MAC for interface int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6]) { struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name)); if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0) return -1; memcpy(mac, ifr.ifr_hwaddr.sa_data, 6); return 0; } // Forwards a packet on a specific interface ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest, struct iovec *iov, size_t iov_len, const struct interface *iface) { // Construct headers uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0}; struct msghdr msg = { .msg_name = (void *) dest, .msg_namelen = sizeof(*dest), .msg_iov = iov, .msg_iovlen = iov_len, .msg_control = cmsg_buf, .msg_controllen = sizeof(cmsg_buf), .msg_flags = 0 }; // Set control data (define destination interface) struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg); chdr->cmsg_level = IPPROTO_IPV6; chdr->cmsg_type = IPV6_PKTINFO; chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr); pktinfo->ipi6_ifindex = iface->ifindex; // Also set scope ID if link-local if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr) || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr)) dest->sin6_scope_id = iface->ifindex; char ipbuf[INET6_ADDRSTRLEN]; inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf)); ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT); if (sent < 0) syslog(LOG_NOTICE, "Failed to send to %s%%%s (%s)", ipbuf, iface->ifname, strerror(errno)); else syslog(LOG_DEBUG, "Sent %li bytes to %s%%%s", (long)sent, ipbuf, iface->ifname); return sent; } int odhcpd_iterate_interface_neighbors(const struct interface *iface, void(*cb_neigh)(const struct in6_addr *addr, const struct interface *iface, void *data), void *data) { struct { struct nlmsghdr nhm; struct ndmsg ndm; } req = {{sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP, ++rtnl_seq, 0}, {AF_INET6, 0, 0, iface->ifindex, 0, 0, 0}}; if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req)) return -1; uint8_t buf[8192]; ssize_t len = 0; for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) { while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) { len = recv(rtnl_socket, buf, sizeof(buf), 0); nhm = (struct nlmsghdr*)buf; if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) { if (errno == EINTR) continue; else return -1; } } if (nhm->nlmsg_type != RTM_NEWNEIGH) break; struct ndmsg *ndm = NLMSG_DATA(nhm); if (ndm->ndm_ifindex != iface->ifindex || !(ndm->ndm_state & (NUD_STALE | NUD_REACHABLE | NUD_PERMANENT))) continue; struct rtattr *rta = (struct rtattr*)&ndm[1]; size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ndm)); while (RTA_OK(rta, alen)) { if (rta->rta_type == NDA_DST && RTA_PAYLOAD(rta) == sizeof(struct in6_addr)) { cb_neigh(RTA_DATA(rta), iface, data); break; } else { rta = RTA_NEXT(rta, alen); } } } return 0; } // Detect an IPV6-address currently assigned to the given interface ssize_t odhcpd_get_interface_addresses(int ifindex, struct odhcpd_ipaddr *addrs, size_t cnt) { struct { struct nlmsghdr nhm; struct ifaddrmsg ifa; } req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP, ++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}}; if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req)) return 0; uint8_t buf[8192]; ssize_t len = 0, ret = 0; for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) { while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) { len = recv(rtnl_socket, buf, sizeof(buf), 0); nhm = (struct nlmsghdr*)buf; if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) { if (errno == EINTR) continue; else return ret; } } if (nhm->nlmsg_type != RTM_NEWADDR) break; // Skip address but keep clearing socket buffer if (ret >= (ssize_t)cnt) continue; struct ifaddrmsg *ifa = NLMSG_DATA(nhm); if (ifa->ifa_scope != RT_SCOPE_UNIVERSE || (ifindex && ifa->ifa_index != (unsigned)ifindex)) continue; struct rtattr *rta = (struct rtattr*)&ifa[1]; size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa)); memset(&addrs[ret], 0, sizeof(addrs[ret])); addrs[ret].prefix = ifa->ifa_prefixlen; while (RTA_OK(rta, alen)) { if (rta->rta_type == IFA_ADDRESS) { memcpy(&addrs[ret].addr, RTA_DATA(rta), sizeof(struct in6_addr)); } else if (rta->rta_type == IFA_CACHEINFO) { struct ifa_cacheinfo *ifc = RTA_DATA(rta); addrs[ret].preferred = ifc->ifa_prefered; addrs[ret].valid = ifc->ifa_valid; } rta = RTA_NEXT(rta, alen); } if (ifa->ifa_flags & IFA_F_DEPRECATED) addrs[ret].preferred = 0; ++ret; } return ret; } int odhcpd_get_preferred_interface_address(int ifindex, struct in6_addr *addr) { struct odhcpd_ipaddr ipaddrs[8]; ssize_t ip_cnt = odhcpd_get_interface_addresses(ifindex, ipaddrs, ARRAY_SIZE(ipaddrs)); uint32_t preferred = 0; int ret = 0; for (ssize_t i = 0; i < ip_cnt; i++) { struct odhcpd_ipaddr *ipaddr = &ipaddrs[i]; if (ipaddr->preferred > preferred || !preferred) { preferred = ipaddr->preferred; *addr = ipaddr->addr; ret = 1; } } return ret; } void odhcpd_setup_route(const struct in6_addr *addr, int prefixlen, const struct interface *iface, const struct in6_addr *gw, int metric, bool add) { struct req { struct nlmsghdr nh; struct rtmsg rtm; struct rtattr rta_dst; struct in6_addr dst_addr; struct rtattr rta_oif; uint32_t ifindex; struct rtattr rta_table; uint32_t table; struct rtattr rta_prio; uint32_t prio; struct rtattr rta_gw; struct in6_addr gw; } req = { {sizeof(req), 0, NLM_F_REQUEST, ++rtnl_seq, 0}, {AF_INET6, prefixlen, 0, 0, 0, 0, 0, 0, 0}, {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_DST}, *addr, {sizeof(struct rtattr) + sizeof(uint32_t), RTA_OIF}, iface->ifindex, {sizeof(struct rtattr) + sizeof(uint32_t), RTA_TABLE}, RT_TABLE_MAIN, {sizeof(struct rtattr) + sizeof(uint32_t), RTA_PRIORITY}, metric, {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_GATEWAY}, IN6ADDR_ANY_INIT, }; if (gw) req.gw = *gw; if (add) { req.nh.nlmsg_type = RTM_NEWROUTE; req.nh.nlmsg_flags |= (NLM_F_CREATE | NLM_F_REPLACE); req.rtm.rtm_protocol = RTPROT_STATIC; req.rtm.rtm_scope = (gw) ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK; req.rtm.rtm_type = RTN_UNICAST; } else { req.nh.nlmsg_type = RTM_DELROUTE; req.rtm.rtm_scope = RT_SCOPE_NOWHERE; } req.nh.nlmsg_len = (gw) ? sizeof(req) : offsetof(struct req, rta_gw); send(rtnl_socket, &req, req.nh.nlmsg_len, MSG_DONTWAIT); } struct interface* odhcpd_get_interface_by_index(int ifindex) { struct interface *iface; list_for_each_entry(iface, &interfaces, head) if (iface->ifindex == ifindex) return iface; return NULL; } struct interface* odhcpd_get_interface_by_name(const char *name) { struct interface *iface; list_for_each_entry(iface, &interfaces, head) if (!strcmp(iface->ifname, name)) return iface; return NULL; } struct interface* odhcpd_get_master_interface(void) { struct interface *iface; list_for_each_entry(iface, &interfaces, head) if (iface->master) return iface; return NULL; } // Convenience function to receive and do basic validation of packets static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events) { struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop); uint8_t data_buf[RELAYD_BUFFER_SIZE], cmsg_buf[128]; union { struct sockaddr_in6 in6; struct sockaddr_in in; struct sockaddr_ll ll; struct sockaddr_nl nl; } addr; while (true) { struct iovec iov = {data_buf, sizeof(data_buf)}; struct msghdr msg = { .msg_name = (void *) &addr, .msg_namelen = sizeof(addr), .msg_iov = &iov, .msg_iovlen = 1, .msg_control = cmsg_buf, .msg_controllen = sizeof(cmsg_buf), .msg_flags = 0 }; ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT); if (len < 0) { if (errno == EAGAIN) break; else continue; } // Extract destination interface int destiface = 0; int *hlim = NULL; void *dest = NULL; struct in6_pktinfo *pktinfo; struct in_pktinfo *pkt4info; for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL; ch = CMSG_NXTHDR(&msg, ch)) { if (ch->cmsg_level == IPPROTO_IPV6 && ch->cmsg_type == IPV6_PKTINFO) { pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch); destiface = pktinfo->ipi6_ifindex; dest = &pktinfo->ipi6_addr; } else if (ch->cmsg_level == IPPROTO_IP && ch->cmsg_type == IP_PKTINFO) { pkt4info = (struct in_pktinfo*)CMSG_DATA(ch); destiface = pkt4info->ipi_ifindex; dest = &pkt4info->ipi_addr; } else if (ch->cmsg_level == IPPROTO_IPV6 && ch->cmsg_type == IPV6_HOPLIMIT) { hlim = (int*)CMSG_DATA(ch); } } // Check hoplimit if received if (hlim && *hlim != 255) continue; // Detect interface for packet sockets if (addr.ll.sll_family == AF_PACKET) destiface = addr.ll.sll_ifindex; struct interface *iface = odhcpd_get_interface_by_index(destiface); if (!iface && addr.nl.nl_family != AF_NETLINK) continue; char ipbuf[INET6_ADDRSTRLEN] = "kernel"; if (addr.ll.sll_family == AF_PACKET && len >= (ssize_t)sizeof(struct ip6_hdr)) inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf)); else if (addr.in6.sin6_family == AF_INET6) inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf)); else if (addr.in.sin_family == AF_INET) inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf)); syslog(LOG_DEBUG, "--"); syslog(LOG_DEBUG, "Received %li Bytes from %s%%%s", (long)len, ipbuf, (iface) ? iface->ifname : "netlink"); e->handle_dgram(&addr, data_buf, len, iface, dest); } } // Register events for the multiplexer int odhcpd_register(struct odhcpd_event *event) { event->uloop.cb = odhcpd_receive_packets; return uloop_fd_add(&event->uloop, ULOOP_READ); } void odhcpd_process(struct odhcpd_event *event) { odhcpd_receive_packets(&event->uloop, 0); } int odhcpd_urandom(void *data, size_t len) { return read(urandom_fd, data, len); } time_t odhcpd_time(void) { struct timespec ts; syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts); return ts.tv_sec; } static const char hexdigits[] = "0123456789abcdef"; static const int8_t hexvals[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, }; ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src) { size_t c; for (c = 0; c < len && src[0] && src[1]; ++c) { int8_t x = (int8_t)*src++; int8_t y = (int8_t)*src++; if (x < 0 || (x = hexvals[x]) < 0 || y < 0 || (y = hexvals[y]) < 0) return -1; dst[c] = x << 4 | y; while (((int8_t)*src) < 0 || (*src && hexvals[(uint8_t)*src] < 0)) src++; } return c; } void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len) { for (size_t i = 0; i < len; ++i) { *dst++ = hexdigits[src[i] >> 4]; *dst++ = hexdigits[src[i] & 0x0f]; } *dst = 0; } int odhcpd_bmemcmp(const void *av, const void *bv, size_t bits) { const uint8_t *a = av, *b = bv; size_t bytes = bits / 8; bits %= 8; int res = memcmp(a, b, bytes); if (res == 0 && bits > 0) res = (a[bytes] >> (8 - bits)) - (b[bytes] >> (8 - bits)); return res; } void odhcpd_bmemcpy(void *av, const void *bv, size_t bits) { uint8_t *a = av; const uint8_t *b = bv; size_t bytes = bits / 8; bits %= 8; memcpy(a, b, bytes); if (bits > 0) { uint8_t mask = (1 << (8 - bits)) - 1; a[bytes] = (a[bytes] & mask) | ((~mask) & b[bytes]); } }