/** * 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 #include #include #include #include #include #include #include #include "odhcpd.h" static int ioctl_sock; static struct nl_sock *rtnl_socket = NULL; static int urandom_fd = -1; static void sighandler(_unused int signal) { uloop_end(); } static void print_usage(const char *app) { printf( "== %s Usage ==\n\n" " -h, --help Print this help\n" " -l level Specify log level 0..7 (default %d)\n", app, config.log_level ); } int main(int argc, char **argv) { openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON); int opt; while ((opt = getopt(argc, argv, "hl:")) != -1) { switch (opt) { case 'h': print_usage(argv[0]); return 0; case 'l': config.log_level = (atoi(optarg) & LOG_PRIMASK); fprintf(stderr, "Log level set to %d\n", config.log_level); break; } } setlogmask(LOG_UPTO(config.log_level)); 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_create_nl_socket(NETLINK_ROUTE))) { syslog(LOG_ERR, "Unable to open nl 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; } struct nl_sock *odhcpd_create_nl_socket(int protocol) { struct nl_sock *nl_sock; nl_sock = nl_socket_alloc(); if (!nl_sock) goto err; if (nl_connect(nl_sock, protocol) < 0) goto err; return nl_sock; err: if (nl_sock) nl_socket_free(nl_sock); return NULL; } // 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; } struct addr_info { int ifindex; int af; struct odhcpd_ipaddr **addrs; int pending; ssize_t ret; }; static int cb_valid_handler(struct nl_msg *msg, void *arg) { struct addr_info *ctxt = (struct addr_info *)arg; struct odhcpd_ipaddr *addrs = *(ctxt->addrs); struct nlmsghdr *hdr = nlmsg_hdr(msg); struct ifaddrmsg *ifa; struct nlattr *nla[__IFA_MAX], *nla_addr = NULL; if (hdr->nlmsg_type != RTM_NEWADDR) return NL_SKIP; ifa = NLMSG_DATA(hdr); if (ifa->ifa_scope != RT_SCOPE_UNIVERSE || (ctxt->af != ifa->ifa_family) || (ctxt->ifindex && ifa->ifa_index != (unsigned)ctxt->ifindex)) return NL_SKIP; nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL); switch (ifa->ifa_family) { case AF_INET6: if (nla[IFA_ADDRESS]) nla_addr = nla[IFA_ADDRESS]; break; case AF_INET: if (nla[IFA_LOCAL]) nla_addr = nla[IFA_LOCAL]; break; default: break; } if (!nla_addr) return NL_SKIP; addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1)); if (!addrs) return NL_SKIP; memset(&addrs[ctxt->ret], 0, sizeof(addrs[ctxt->ret])); addrs[ctxt->ret].prefix = ifa->ifa_prefixlen; nla_memcpy(&addrs[ctxt->ret].addr, nla_addr, sizeof(addrs[ctxt->ret].addr)); if (nla[IFA_BROADCAST]) nla_memcpy(&addrs[ctxt->ret].broadcast, nla[IFA_BROADCAST], sizeof(addrs[ctxt->ret].broadcast)); if (nla[IFA_CACHEINFO]) { struct ifa_cacheinfo *ifc = nla_data(nla[IFA_CACHEINFO]); addrs[ctxt->ret].preferred = ifc->ifa_prefered; addrs[ctxt->ret].valid = ifc->ifa_valid; } if (ifa->ifa_flags & IFA_F_DEPRECATED) addrs[ctxt->ret].preferred = 0; ctxt->ret++; *(ctxt->addrs) = addrs; return NL_OK; } static int cb_finish_handler(_unused struct nl_msg *msg, void *arg) { struct addr_info *ctxt = (struct addr_info *)arg; ctxt->pending = 0; return NL_STOP; } static int cb_error_handler(_unused struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg) { struct addr_info *ctxt = (struct addr_info *)arg; ctxt->pending = 0; ctxt->ret = err->error; return NL_STOP; } static int prefix_cmp(const void *va, const void *vb) { const struct odhcpd_ipaddr *a = va, *b = vb; return (ntohl(a->addr.in.s_addr) < ntohl(b->addr.in.s_addr)) ? 1 : (ntohl(a->addr.in.s_addr) > ntohl(b->addr.in.s_addr)) ? -1 : 0; } // compare IPv6 prefixes static int prefix6_cmp(const void *va, const void *vb) { const struct odhcpd_ipaddr *a = va, *b = vb; uint32_t a_pref = IN6_IS_ADDR_ULA(&a->addr.in6) ? 1 : a->preferred; uint32_t b_pref = IN6_IS_ADDR_ULA(&b->addr.in6) ? 1 : b->preferred; return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0; } // Detect an IPV6-address currently assigned to the given interface ssize_t odhcpd_get_interface_addresses(int ifindex, bool v6, struct odhcpd_ipaddr **addrs) { struct nl_msg *msg; struct ifaddrmsg ifa = { .ifa_family = v6? AF_INET6: AF_INET, .ifa_prefixlen = 0, .ifa_flags = 0, .ifa_scope = 0, .ifa_index = ifindex, }; struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT); struct addr_info ctxt = { .ifindex = ifindex, .af = v6? AF_INET6: AF_INET, .addrs = addrs, .ret = 0, .pending = 1, }; if (!cb) { ctxt.ret = -1; goto out; } msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP); if (!msg) { ctxt.ret = - 1; goto out; } nlmsg_append(msg, &ifa, sizeof(ifa), 0); nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_valid_handler, &ctxt); nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_finish_handler, &ctxt); nl_cb_err(cb, NL_CB_CUSTOM, cb_error_handler, &ctxt); nl_send_auto_complete(rtnl_socket, msg); while (ctxt.pending > 0) nl_recvmsgs(rtnl_socket, cb); nlmsg_free(msg); if (ctxt.ret <= 0) goto out; time_t now = odhcpd_time(); struct odhcpd_ipaddr *addr = *addrs; qsort(addr, ctxt.ret, sizeof(*addr), v6 ? prefix6_cmp : prefix_cmp); for (ssize_t i = 0; i < ctxt.ret; ++i) { if (addr[i].preferred < UINT32_MAX - now) addr[i].preferred += now; if (addr[i].valid < UINT32_MAX - now) addr[i].valid += now; } out: nl_cb_put(cb); return ctxt.ret; } static int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr) { int status = -1; struct sockaddr_in6 addr = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, ifindex}; socklen_t alen = sizeof(addr); int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6); if (!connect(sock, (struct sockaddr*)&addr, sizeof(addr)) && !getsockname(sock, (struct sockaddr*)&addr, &alen)) { *lladdr = addr.sin6_addr; status = 0; } close(sock); return status; } /* * DNS address selection criteria order : * - use IPv6 address with valid lifetime if none is yet selected * - use IPv6 address with a preferred lifetime if the already selected IPv6 address is deprecated * - use an IPv6 ULA address if the already selected IPv6 address is not an ULA address * - use the IPv6 address with the longest preferred lifetime */ int odhcpd_get_interface_dns_addr(const struct interface *iface, struct in6_addr *addr) { time_t now = odhcpd_time(); ssize_t m = -1; for (size_t i = 0; i < iface->ia_addr_len; ++i) { if (iface->ia_addr[i].valid <= (uint32_t)now) continue; if (m < 0) { m = i; continue; } if (iface->ia_addr[m].preferred >= (uint32_t)now && iface->ia_addr[i].preferred < (uint32_t)now) continue; if (IN6_IS_ADDR_ULA(&iface->ia_addr[i].addr.in6)) { if (!IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6)) { m = i; continue; } } else if (IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6)) continue; if (iface->ia_addr[i].preferred > iface->ia_addr[m].preferred) m = i; } if (m >= 0) { *addr = iface->ia_addr[m].addr.in6; return 0; } return odhcpd_get_linklocal_interface_address(iface->ifindex, addr); } int odhcpd_setup_route(const struct in6_addr *addr, const int prefixlen, const struct interface *iface, const struct in6_addr *gw, const uint32_t metric, const bool add) { struct nl_msg *msg; struct rtmsg rtm = { .rtm_family = AF_INET6, .rtm_dst_len = prefixlen, .rtm_src_len = 0, .rtm_table = RT_TABLE_MAIN, .rtm_protocol = (add ? RTPROT_STATIC : RTPROT_UNSPEC), .rtm_scope = (add ? (gw ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK) : RT_SCOPE_NOWHERE), .rtm_type = (add ? RTN_UNICAST : RTN_UNSPEC), }; int ret = 0; msg = nlmsg_alloc_simple(add ? RTM_NEWROUTE : RTM_DELROUTE, add ? NLM_F_CREATE | NLM_F_REPLACE : 0); if (!msg) return -1; nlmsg_append(msg, &rtm, sizeof(rtm), 0); nla_put(msg, RTA_DST, sizeof(*addr), addr); nla_put_u32(msg, RTA_OIF, iface->ifindex); nla_put_u32(msg, RTA_PRIORITY, metric); if (gw) nla_put(msg, RTA_GATEWAY, sizeof(*gw), gw); ret = nl_send_auto_complete(rtnl_socket, msg); nlmsg_free(msg); if (ret < 0) return ret; return nl_wait_for_ack(rtnl_socket); } int odhcpd_setup_proxy_neigh(const struct in6_addr *addr, const struct interface *iface, const bool add) { struct nl_msg *msg; struct ndmsg ndm = { .ndm_family = AF_INET6, .ndm_flags = NTF_PROXY, .ndm_ifindex = iface->ifindex, }; int ret = 0, flags = NLM_F_REQUEST; if (add) flags |= NLM_F_REPLACE | NLM_F_CREATE; msg = nlmsg_alloc_simple(add ? RTM_NEWNEIGH : RTM_DELNEIGH, flags); if (!msg) return -1; nlmsg_append(msg, &ndm, sizeof(ndm), 0); nla_put(msg, NDA_DST, sizeof(*addr), addr); ret = nl_send_auto_complete(rtnl_socket, msg); nlmsg_free(msg); if (ret < 0) return ret; return nl_wait_for_ack(rtnl_socket); } 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; if (u->error) { int ret = -1; socklen_t ret_len = sizeof(ret); getsockopt(u->fd, SOL_SOCKET, SO_ERROR, &ret, &ret_len); u->error = false; if (e->handle_error) e->handle_error(e, ret); } if (e->recv_msgs) { e->recv_msgs(e); return; } 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, "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 | ((event->handle_error) ? ULOOP_ERROR_CB : 0)); } int odhcpd_deregister(struct odhcpd_event *event) { event->uloop.cb = NULL; return uloop_fd_delete(&event->uloop); } 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]); } }