/* net_packet.c -- Handles in- and outgoing VPN packets Copyright (C) 1998-2005 Ivo Timmermans, 2000-2012 Guus Sliepen 2010 Timothy Redaelli 2010 Brandon Black This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. 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. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include "system.h" #include #include #include #include #include #ifdef HAVE_ZLIB #include #endif #ifdef HAVE_LZO #include LZO1X_H #endif #include "splay_tree.h" #include "cipher.h" #include "conf.h" #include "connection.h" #include "crypto.h" #include "digest.h" #include "device.h" #include "ethernet.h" #include "graph.h" #include "logger.h" #include "net.h" #include "netutl.h" #include "protocol.h" #include "process.h" #include "route.h" #include "utils.h" #include "xalloc.h" int keylifetime = 0; #ifdef HAVE_LZO static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS]; #endif static void send_udppacket(node_t *, vpn_packet_t *); unsigned replaywin = 16; bool localdiscovery = false; #define MAX_SEQNO 1073741824 /* mtuprobes == 1..30: initial discovery, send bursts with 1 second interval mtuprobes == 31: sleep pinginterval seconds mtuprobes == 32: send 1 burst, sleep pingtimeout second mtuprobes == 33: no response from other side, restart PMTU discovery process Probes are sent in batches of three, with random sizes between the lower and upper boundaries for the MTU thus far discovered. In case local discovery is enabled, a fourth packet is added to each batch, which will be broadcast to the local network. */ static void send_mtu_probe_handler(int fd, short events, void *data) { node_t *n = data; vpn_packet_t packet; int len, i; int timeout = 1; n->mtuprobes++; if(!n->status.reachable || !n->status.validkey) { logger(DEBUG_TRAFFIC, LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname); n->mtuprobes = 0; return; } if(n->mtuprobes > 32) { if(!n->minmtu) { n->mtuprobes = 31; timeout = pinginterval; goto end; } logger(DEBUG_TRAFFIC, LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname); n->mtuprobes = 1; n->minmtu = 0; n->maxmtu = MTU; } if(n->mtuprobes >= 10 && n->mtuprobes < 32 && !n->minmtu) { logger(DEBUG_TRAFFIC, LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname); n->mtuprobes = 31; } if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) { if(n->minmtu > n->maxmtu) n->minmtu = n->maxmtu; else n->maxmtu = n->minmtu; n->mtu = n->minmtu; logger(DEBUG_TRAFFIC, LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes); n->mtuprobes = 31; } if(n->mtuprobes == 31) { timeout = pinginterval; goto end; } else if(n->mtuprobes == 32) { timeout = pingtimeout; } for(i = 0; i < 3 + localdiscovery; i++) { if(n->maxmtu <= n->minmtu) len = n->maxmtu; else len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu); if(len < 64) len = 64; memset(packet.data, 0, 14); randomize(packet.data + 14, len - 14); packet.len = len; if(i >= 3 && n->mtuprobes <= 10) packet.priority = -1; else packet.priority = 0; logger(DEBUG_TRAFFIC, LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname); send_udppacket(n, &packet); } end: event_add(&n->mtuevent, &(struct timeval){timeout, 0}); } void send_mtu_probe(node_t *n) { if(!timeout_initialized(&n->mtuevent)) timeout_set(&n->mtuevent, send_mtu_probe_handler, n); send_mtu_probe_handler(0, 0, n); } static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) { logger(DEBUG_TRAFFIC, LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname); if(!packet->data[0]) { packet->data[0] = 1; send_udppacket(n, packet); } else { if(n->mtuprobes > 30) { if(n->minmtu) n->mtuprobes = 30; else n->mtuprobes = 1; } if(len > n->maxmtu) len = n->maxmtu; if(n->minmtu < len) n->minmtu = len; } } static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) { if(level == 0) { memcpy(dest, source, len); return len; } else if(level == 10) { #ifdef HAVE_LZO lzo_uint lzolen = MAXSIZE; lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem); return lzolen; #else return -1; #endif } else if(level < 10) { #ifdef HAVE_ZLIB unsigned long destlen = MAXSIZE; if(compress2(dest, &destlen, source, len, level) == Z_OK) return destlen; else #endif return -1; } else { #ifdef HAVE_LZO lzo_uint lzolen = MAXSIZE; lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem); return lzolen; #else return -1; #endif } return -1; } static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) { if(level == 0) { memcpy(dest, source, len); return len; } else if(level > 9) { #ifdef HAVE_LZO lzo_uint lzolen = MAXSIZE; if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK) return lzolen; else #endif return -1; } #ifdef HAVE_ZLIB else { unsigned long destlen = MAXSIZE; if(uncompress(dest, &destlen, source, len) == Z_OK) return destlen; else return -1; } #endif return -1; } /* VPN packet I/O */ static void receive_packet(node_t *n, vpn_packet_t *packet) { logger(DEBUG_TRAFFIC, LOG_DEBUG, "Received packet of %d bytes from %s (%s)", packet->len, n->name, n->hostname); n->in_packets++; n->in_bytes += packet->len; route(n, packet); } static bool try_mac(node_t *n, const vpn_packet_t *inpkt) { if(!digest_active(&n->indigest) || inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest)) return false; return digest_verify(&n->indigest, &inpkt->seqno, inpkt->len - n->indigest.maclength, (const char *)&inpkt->seqno + inpkt->len - n->indigest.maclength); } static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) { vpn_packet_t pkt1, pkt2; vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 }; int nextpkt = 0; vpn_packet_t *outpkt = pkt[0]; size_t outlen; if(!cipher_active(&n->incipher)) { logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet", n->name, n->hostname); return; } /* Check packet length */ if(inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest)) { logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got too short packet from %s (%s)", n->name, n->hostname); return; } /* Check the message authentication code */ if(digest_active(&n->indigest)) { inpkt->len -= n->indigest.maclength; if(!digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len)) { logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got unauthenticated packet from %s (%s)", n->name, n->hostname); return; } } /* Decrypt the packet */ if(cipher_active(&n->incipher)) { outpkt = pkt[nextpkt++]; outlen = MAXSIZE; if(!cipher_decrypt(&n->incipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) { logger(DEBUG_TRAFFIC, LOG_DEBUG, "Error decrypting packet from %s (%s)", n->name, n->hostname); return; } outpkt->len = outlen; inpkt = outpkt; } /* Check the sequence number */ inpkt->len -= sizeof inpkt->seqno; inpkt->seqno = ntohl(inpkt->seqno); if(replaywin) { if(inpkt->seqno != n->received_seqno + 1) { if(inpkt->seqno >= n->received_seqno + replaywin * 8) { if(n->farfuture++ < replaywin >> 2) { logger(DEBUG_ALWAYS, LOG_WARNING, "Packet from %s (%s) is %d seqs in the future, dropped (%u)", n->name, n->hostname, inpkt->seqno - n->received_seqno - 1, n->farfuture); return; } logger(DEBUG_ALWAYS, LOG_WARNING, "Lost %d packets from %s (%s)", inpkt->seqno - n->received_seqno - 1, n->name, n->hostname); memset(n->late, 0, replaywin); } else if (inpkt->seqno <= n->received_seqno) { if((n->received_seqno >= replaywin * 8 && inpkt->seqno <= n->received_seqno - replaywin * 8) || !(n->late[(inpkt->seqno / 8) % replaywin] & (1 << inpkt->seqno % 8))) { logger(DEBUG_ALWAYS, LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d", n->name, n->hostname, inpkt->seqno, n->received_seqno); return; } } else { for(int i = n->received_seqno + 1; i < inpkt->seqno; i++) n->late[(i / 8) % replaywin] |= 1 << i % 8; } } n->farfuture = 0; n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8); } if(inpkt->seqno > n->received_seqno) n->received_seqno = inpkt->seqno; if(n->received_seqno > MAX_SEQNO) regenerate_key(); /* Decompress the packet */ length_t origlen = inpkt->len; if(n->incompression) { outpkt = pkt[nextpkt++]; if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) { logger(DEBUG_TRAFFIC, LOG_ERR, "Error while uncompressing packet from %s (%s)", n->name, n->hostname); return; } inpkt = outpkt; origlen -= MTU/64 + 20; } inpkt->priority = 0; if(!inpkt->data[12] && !inpkt->data[13]) mtu_probe_h(n, inpkt, origlen); else receive_packet(n, inpkt); } void receive_tcppacket(connection_t *c, const char *buffer, int len) { vpn_packet_t outpkt; outpkt.len = len; if(c->options & OPTION_TCPONLY) outpkt.priority = 0; else outpkt.priority = -1; memcpy(outpkt.data, buffer, len); receive_packet(c->node, &outpkt); } static void send_udppacket(node_t *n, vpn_packet_t *origpkt) { vpn_packet_t pkt1, pkt2; vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 }; vpn_packet_t *inpkt = origpkt; int nextpkt = 0; vpn_packet_t *outpkt; int origlen = origpkt->len; size_t outlen; #if defined(SOL_IP) && defined(IP_TOS) static int priority = 0; #endif int origpriority = origpkt->priority; if(!n->status.reachable) { logger(DEBUG_TRAFFIC, LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname); return; } /* Make sure we have a valid key */ if(!n->status.validkey) { time_t now = time(NULL); logger(DEBUG_TRAFFIC, LOG_INFO, "No valid key known yet for %s (%s), forwarding via TCP", n->name, n->hostname); if(n->last_req_key + 10 <= now) { send_req_key(n); n->last_req_key = now; } send_tcppacket(n->nexthop->connection, origpkt); return; } if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) { logger(DEBUG_TRAFFIC, LOG_INFO, "Packet for %s (%s) larger than minimum MTU, forwarding via %s", n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP"); if(n != n->nexthop) send_packet(n->nexthop, origpkt); else send_tcppacket(n->nexthop->connection, origpkt); return; } /* Compress the packet */ if(n->outcompression) { outpkt = pkt[nextpkt++]; if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) { logger(DEBUG_TRAFFIC, LOG_ERR, "Error while compressing packet to %s (%s)", n->name, n->hostname); return; } inpkt = outpkt; } /* Add sequence number */ inpkt->seqno = htonl(++(n->sent_seqno)); inpkt->len += sizeof inpkt->seqno; /* Encrypt the packet */ if(cipher_active(&n->outcipher)) { outpkt = pkt[nextpkt++]; outlen = MAXSIZE; if(!cipher_encrypt(&n->outcipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) { logger(DEBUG_TRAFFIC, LOG_ERR, "Error while encrypting packet to %s (%s)", n->name, n->hostname); goto end; } outpkt->len = outlen; inpkt = outpkt; } /* Add the message authentication code */ if(digest_active(&n->outdigest)) { digest_create(&n->outdigest, &inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len); inpkt->len += digest_length(&n->outdigest); } /* Determine which socket we have to use */ if(n->address.sa.sa_family != listen_socket[n->sock].sa.sa.sa_family) { for(int sock = 0; sock < listen_sockets; sock++) { if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family) { n->sock = sock; break; } } } /* Send the packet */ struct sockaddr *sa; socklen_t sl; int sock; /* Overloaded use of priority field: -1 means local broadcast */ if(origpriority == -1 && n->prevedge) { struct sockaddr_in in; in.sin_family = AF_INET; in.sin_addr.s_addr = -1; in.sin_port = n->prevedge->address.in.sin_port; sa = (struct sockaddr *)∈ sl = sizeof in; sock = 0; } else { if(origpriority == -1) origpriority = 0; sa = &(n->address.sa); sl = SALEN(n->address.sa); sock = n->sock; } #if defined(SOL_IP) && defined(IP_TOS) if(priorityinheritance && origpriority != priority && listen_socket[n->sock].sa.sa.sa_family == AF_INET) { priority = origpriority; logger(DEBUG_TRAFFIC, LOG_DEBUG, "Setting outgoing packet priority to %d", priority); if(setsockopt(listen_socket[n->sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */ logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno)); } #endif if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, sa, sl) < 0 && !sockwouldblock(sockerrno)) { if(sockmsgsize(sockerrno)) { if(n->maxmtu >= origlen) n->maxmtu = origlen - 1; if(n->mtu >= origlen) n->mtu = origlen - 1; } else logger(DEBUG_TRAFFIC, LOG_WARNING, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno)); } end: origpkt->len = origlen; } /* send a packet to the given vpn ip. */ void send_packet(node_t *n, vpn_packet_t *packet) { node_t *via; if(n == myself) { if(overwrite_mac) memcpy(packet->data, mymac.x, ETH_ALEN); n->out_packets++; n->out_bytes += packet->len; devops.write(packet); return; } logger(DEBUG_TRAFFIC, LOG_ERR, "Sending packet of %d bytes to %s (%s)", packet->len, n->name, n->hostname); if(!n->status.reachable) { logger(DEBUG_TRAFFIC, LOG_INFO, "Node %s (%s) is not reachable", n->name, n->hostname); return; } n->out_packets++; n->out_bytes += packet->len; via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via; if(via != n) logger(DEBUG_TRAFFIC, LOG_INFO, "Sending packet to %s via %s (%s)", n->name, via->name, n->via->hostname); if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) { if(!send_tcppacket(via->connection, packet)) terminate_connection(via->connection, true); } else send_udppacket(via, packet); } /* Broadcast a packet using the minimum spanning tree */ void broadcast_packet(const node_t *from, vpn_packet_t *packet) { splay_node_t *node; connection_t *c; node_t *n; // Always give ourself a copy of the packet. if(from != myself) send_packet(myself, packet); // In TunnelServer mode, do not forward broadcast packets. // The MST might not be valid and create loops. if(tunnelserver || broadcast_mode == BMODE_NONE) return; logger(DEBUG_TRAFFIC, LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)", packet->len, from->name, from->hostname); switch(broadcast_mode) { // In MST mode, broadcast packets travel via the Minimum Spanning Tree. // This guarantees all nodes receive the broadcast packet, and // usually distributes the sending of broadcast packets over all nodes. case BMODE_MST: for(node = connection_tree->head; node; node = node->next) { c = node->data; if(c->status.active && c->status.mst && c != from->nexthop->connection) send_packet(c->node, packet); } break; // In direct mode, we send copies to each node we know of. // However, this only reaches nodes that can be reached in a single hop. // We don't have enough information to forward broadcast packets in this case. case BMODE_DIRECT: if(from != myself) break; for(node = node_udp_tree->head; node; node = node->next) { n = node->data; if(n->status.reachable && ((n->via == myself && n->nexthop == n) || n->via == n)) send_packet(n, packet); } break; default: break; } } static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) { splay_node_t *node; edge_t *e; node_t *n = NULL; bool hard = false; static time_t last_hard_try = 0; time_t now = time(NULL); for(node = edge_weight_tree->head; node; node = node->next) { e = node->data; if(e->to == myself) continue; if(sockaddrcmp_noport(from, &e->address)) { if(last_hard_try == now) continue; hard = true; } if(!try_mac(e->to, pkt)) continue; n = e->to; break; } if(hard) last_hard_try = now; last_hard_try = now; return n; } void handle_incoming_vpn_data(int sock, short events, void *data) { vpn_packet_t pkt; char *hostname; sockaddr_t from; socklen_t fromlen = sizeof from; node_t *n; int len; len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen); if(len <= 0 || len > MAXSIZE) { if(!sockwouldblock(sockerrno)) logger(DEBUG_ALWAYS, LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno)); return; } pkt.len = len; sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */ n = lookup_node_udp(&from); if(!n) { n = try_harder(&from, &pkt); if(n) update_node_udp(n, &from); else if(debug_level >= DEBUG_PROTOCOL) { hostname = sockaddr2hostname(&from); logger(DEBUG_PROTOCOL, LOG_WARNING, "Received UDP packet from unknown source %s", hostname); free(hostname); return; } else return; } n->sock = (intptr_t)data; receive_udppacket(n, &pkt); } void handle_device_data(int sock, short events, void *data) { vpn_packet_t packet; packet.priority = 0; if(devops.read(&packet)) { myself->in_packets++; myself->in_bytes += packet.len; route(myself, &packet); } }