tinc/src/net_packet.c

652 lines
17 KiB
C

/*
net_packet.c -- Handles in- and outgoing VPN packets
Copyright (C) 1998-2005 Ivo Timmermans,
2000-2011 Guus Sliepen <guus@tinc-vpn.org>
2010 Timothy Redaelli <timothy@redaelli.eu>
2010 Brandon Black <blblack@gmail.com>
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 <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/pem.h>
#include <openssl/hmac.h>
#ifdef HAVE_ZLIB
#include <zlib.h>
#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;
#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
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) {
ifdebug(TRAFFIC) logger(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;
}
ifdebug(TRAFFIC) logger(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) {
ifdebug(TRAFFIC) logger(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;
ifdebug(TRAFFIC) logger(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; 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;
packet.priority = 0;
ifdebug(TRAFFIC) logger(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) {
ifdebug(TRAFFIC) logger(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) {
ifdebug(TRAFFIC) logger(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)) {
ifdebug(TRAFFIC) logger(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)) {
ifdebug(TRAFFIC) logger(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)) {
ifdebug(TRAFFIC) logger(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)) {
ifdebug(TRAFFIC) logger(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(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(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(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) {
ifdebug(TRAFFIC) logger(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;
int origpriority = origpkt->priority;
#endif
int sock;
if(!n->status.reachable) {
ifdebug(TRAFFIC) logger(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);
ifdebug(TRAFFIC) logger(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])) {
ifdebug(TRAFFIC) logger(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) {
ifdebug(TRAFFIC) logger(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)) {
ifdebug(TRAFFIC) logger(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 */
for(sock = 0; sock < listen_sockets; sock++)
if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
break;
if(sock >= listen_sockets)
sock = 0; /* If none is available, just use the first and hope for the best. */
/* Send the packet */
#if defined(SOL_IP) && defined(IP_TOS)
if(priorityinheritance && origpriority != priority
&& listen_socket[sock].sa.sa.sa_family == AF_INET) {
priority = origpriority;
ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof priority)) /* SO_PRIORITY doesn't seem to work */
logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
}
#endif
if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
if(sockmsgsize(sockerrno)) {
if(n->maxmtu >= origlen)
n->maxmtu = origlen - 1;
if(n->mtu >= origlen)
n->mtu = origlen - 1;
} else
logger(LOG_ERR, "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;
write_packet(packet);
return;
}
ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
packet->len, n->name, n->hostname);
if(!n->status.reachable) {
ifdebug(TRAFFIC) logger(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)
ifdebug(TRAFFIC) logger(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;
ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
packet->len, from->name, from->hostname);
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)
return;
}
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);
}
}
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);
if(last_hard_try == now)
return NULL;
else
last_hard_try = now;
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;
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(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 ifdebug(PROTOCOL) {
hostname = sockaddr2hostname(&from);
logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
free(hostname);
return;
}
else
return;
}
receive_udppacket(n, &pkt);
}
void handle_device_data(int sock, short events, void *data) {
vpn_packet_t packet;
packet.priority = 0;
if(read_packet(&packet)) {
myself->in_packets++;
myself->in_bytes += packet.len;
route(myself, &packet);
}
}