2 * Emergency Access Daemon
3 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2
7 * as published by the Free Software Foundation
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
15 #include <sys/types.h>
17 #include <sys/select.h>
31 #include <t_defines.h>
37 #include "ead-crypt.h"
42 #include "libbridge_init.c"
45 #define PASSWD_FILE "/etc/passwd"
47 #ifndef DEFAULT_IFNAME
48 #define DEFAULT_IFNAME "eth0"
51 #ifndef DEFAULT_DEVNAME
52 #define DEFAULT_DEVNAME "Unknown"
56 #define PCAP_TIMEOUT 200
58 #if EAD_DEBUGLEVEL >= 1
59 #define DEBUG(n, format, ...) do { \
60 if (EAD_DEBUGLEVEL >= n) \
61 fprintf(stderr, format, ##__VA_ARGS__); \
65 #define DEBUG(n, format, ...) do {} while(0)
69 struct list_head list;
79 static char ethmac[6] = "\x00\x13\x37\x00\x00\x00"; /* last 3 bytes will be randomized */
80 static pcap_t *pcap_fp = NULL;
81 static pcap_t *pcap_fp_rx = NULL;
82 static char pktbuf_b[PCAP_MRU];
83 static struct ead_packet *pktbuf = (struct ead_packet *)pktbuf_b;
84 static u16_t nid = 0xffff; /* node id */
85 static char username[32] = "";
86 static int state = EAD_TYPE_SET_USERNAME;
87 static const char *passwd_file = PASSWD_FILE;
88 static const char password[MAXPARAMLEN];
89 static bool child_pending = false;
91 static unsigned char abuf[MAXPARAMLEN + 1];
92 static unsigned char pwbuf[MAXPARAMLEN];
93 static unsigned char saltbuf[MAXSALTLEN];
94 static unsigned char pw_saltbuf[MAXSALTLEN];
95 static struct list_head instances;
96 static const char *dev_name = DEFAULT_DEVNAME;
97 static bool nonfork = false;
98 static struct ead_instance *instance = NULL;
100 static struct t_pwent tpe = {
103 .password.data = pwbuf,
105 .salt.data = saltbuf,
108 struct t_confent *tce = NULL;
109 static struct t_server *ts = NULL;
110 static struct t_num A, *B = NULL;
114 get_random_bytes(void *ptr, int len)
118 fd = open("/dev/urandom", O_RDONLY);
128 prepare_password(void)
130 static char lbuf[1024];
131 unsigned char dig[SHA_DIGESTSIZE];
132 BigInteger x, v, n, g;
134 int ulen = strlen(username);
137 lbuf[sizeof(lbuf) - 1] = 0;
139 f = fopen(passwd_file, "r");
143 while (fgets(lbuf, sizeof(lbuf) - 1, f) != NULL) {
146 if (strncmp(lbuf, username, ulen) != 0)
149 if (lbuf[ulen] != ':')
152 str = &lbuf[ulen + 1];
154 if (strncmp(str, "$1$", 3) != 0)
157 s2 = strchr(str + 3, '$');
161 if (s2 - str >= MAXSALTLEN)
164 strncpy((char *) pw_saltbuf, str, s2 - str);
165 pw_saltbuf[s2 - str] = 0;
167 s2 = strchr(s2, ':');
172 if (s2 - str >= MAXPARAMLEN)
175 strncpy((char *)password, str, MAXPARAMLEN);
185 tce = gettcid(tpe.index);
187 t_random(tpe.password.data, SALTLEN);
188 } while (memcmp(saltbuf, (char *)dig, sizeof(saltbuf)) == 0);
192 n = BigIntegerFromBytes(tce->modulus.data, tce->modulus.len);
193 g = BigIntegerFromBytes(tce->generator.data, tce->generator.len);
194 v = BigIntegerFromInt(0);
197 SHA1Update(&ctxt, (unsigned char *) username, strlen(username));
198 SHA1Update(&ctxt, (unsigned char *) ":", 1);
199 SHA1Update(&ctxt, (unsigned char *) password, strlen(password));
200 SHA1Final(dig, &ctxt);
203 SHA1Update(&ctxt, saltbuf, tpe.salt.len);
204 SHA1Update(&ctxt, dig, sizeof(dig));
205 SHA1Final(dig, &ctxt);
207 /* x = H(s, H(u, ':', p)) */
208 x = BigIntegerFromBytes(dig, sizeof(dig));
210 BigIntegerModExp(v, g, x, n);
211 tpe.password.len = BigIntegerToBytes(v, (unsigned char *)pwbuf);
221 chksum(u16_t sum, const u8_t *data, u16_t len)
225 const u8_t *last_byte;
228 last_byte = data + len - 1;
230 while(dataptr < last_byte) { /* At least two more bytes */
231 t = (dataptr[0] << 8) + dataptr[1];
239 if(dataptr == last_byte) {
240 t = (dataptr[0] << 8) + 0;
247 /* Return sum in host byte order. */
252 ead_send_packet_clone(struct ead_packet *pkt)
256 memcpy(pktbuf, pkt, offsetof(struct ead_packet, msg));
257 memcpy(pktbuf->eh.ether_shost, ethmac, 6);
258 memcpy(pktbuf->eh.ether_dhost, pkt->eh.ether_shost, 6);
261 len = sizeof(struct ead_packet) - sizeof(struct ether_header) + ntohl(pktbuf->msg.len);
262 pktbuf->len[0] = len >> 8;
263 pktbuf->len[1] = len & 0xff;
264 memcpy(pktbuf->srcipaddr, &pkt->msg.ip, 4);
265 memcpy(pktbuf->destipaddr, pkt->srcipaddr, 4);
268 pktbuf->ipchksum = 0;
269 sum = chksum(0, (void *) &pktbuf->vhl, UIP_IPH_LEN);
272 pktbuf->ipchksum = htons(~sum);
275 pktbuf->srcport = pkt->destport;
276 pktbuf->destport = pkt->srcport;
280 pktbuf->udplen = htons(len);
281 pktbuf->udpchksum = 0;
282 sum = len + UIP_PROTO_UDP;
283 sum = chksum(sum, (void *) &pktbuf->srcipaddr[0], 8); /* src, dest ip */
284 sum = chksum(sum, (void *) &pktbuf->srcport, len);
287 pktbuf->udpchksum = htons(~sum);
288 pcap_sendpacket(pcap_fp, (void *) pktbuf, sizeof(struct ead_packet) + ntohl(pktbuf->msg.len));
292 set_state(int nstate)
297 if (nstate < state) {
298 if ((nstate < EAD_TYPE_GET_PRIME) &&
299 (state >= EAD_TYPE_GET_PRIME)) {
307 case EAD_TYPE_SET_USERNAME:
308 if (!prepare_password())
310 ts = t_serveropenraw(&tpe, tce);
314 case EAD_TYPE_GET_PRIME:
315 B = t_servergenexp(ts);
317 case EAD_TYPE_SEND_A:
318 skey = t_servergetkey(ts, &A);
332 handle_ping(struct ead_packet *pkt, int len, int *nstate)
334 struct ead_msg *msg = &pktbuf->msg;
335 struct ead_msg_pong *pong = EAD_DATA(msg, pong);
338 slen = strlen(dev_name);
342 msg->len = htonl(sizeof(struct ead_msg_pong) + slen);
343 strncpy(pong->name, dev_name, slen);
344 pong->name[slen] = 0;
345 pong->auth_type = htons(EAD_AUTH_MD5);
351 handle_set_username(struct ead_packet *pkt, int len, int *nstate)
353 struct ead_msg *msg = &pkt->msg;
354 struct ead_msg_user *user = EAD_DATA(msg, user);
356 set_state(EAD_TYPE_SET_USERNAME); /* clear old state */
357 strncpy(username, user->username, sizeof(username));
358 username[sizeof(username) - 1] = 0;
363 *nstate = EAD_TYPE_GET_PRIME;
368 handle_get_prime(struct ead_packet *pkt, int len, int *nstate)
370 struct ead_msg *msg = &pktbuf->msg;
371 struct ead_msg_salt *salt = EAD_DATA(msg, salt);
373 msg->len = htonl(sizeof(struct ead_msg_salt));
374 salt->prime = tce->index - 1;
375 salt->len = ts->s.len;
376 memcpy(salt->salt, ts->s.data, ts->s.len);
377 memcpy(salt->ext_salt, pw_saltbuf, MAXSALTLEN);
379 *nstate = EAD_TYPE_SEND_A;
384 handle_send_a(struct ead_packet *pkt, int len, int *nstate)
386 struct ead_msg *msg = &pkt->msg;
387 struct ead_msg_number *number = EAD_DATA(msg, number);
388 len = ntohl(msg->len) - sizeof(struct ead_msg_number);
390 if (len > MAXPARAMLEN + 1)
395 memcpy(A.data, number->data, len);
398 number = EAD_DATA(msg, number);
399 msg->len = htonl(sizeof(struct ead_msg_number) + B->len);
400 memcpy(number->data, B->data, B->len);
402 *nstate = EAD_TYPE_SEND_AUTH;
407 handle_send_auth(struct ead_packet *pkt, int len, int *nstate)
409 struct ead_msg *msg = &pkt->msg;
410 struct ead_msg_auth *auth = EAD_DATA(msg, auth);
412 if (t_serververify(ts, auth->data) != 0) {
413 DEBUG(2, "Client authentication failed\n");
414 *nstate = EAD_TYPE_SET_USERNAME;
419 auth = EAD_DATA(msg, auth);
420 msg->len = htonl(sizeof(struct ead_msg_auth));
422 DEBUG(2, "Client authentication successful\n");
423 memcpy(auth->data, t_serverresponse(ts), sizeof(auth->data));
425 *nstate = EAD_TYPE_SEND_CMD;
430 handle_send_cmd(struct ead_packet *pkt, int len, int *nstate)
432 struct ead_msg *msg = &pkt->msg;
433 struct ead_msg_cmd *cmd = EAD_ENC_DATA(msg, cmd);
434 struct ead_msg_cmd_data *cmddata;
435 struct timeval tv, to, tn;
444 datalen = ead_decrypt_message(msg) - sizeof(struct ead_msg_cmd);
448 type = ntohs(cmd->type);
449 timeout = ntohs(cmd->timeout);
452 cmd->data[datalen] = 0;
458 fcntl(pfd[0], F_SETFL, O_NONBLOCK | fcntl(pfd[0], F_GETFL));
459 child_pending = true;
463 fd = open("/dev/null", O_RDWR);
469 system((char *)cmd->data);
471 } else if (pid > 0) {
474 timeout = EAD_CMD_TIMEOUT;
480 case EAD_CMD_BACKGROUND:
483 /* close stdin, stdout, stderr, replace with fd to /dev/null */
484 fd = open("/dev/null", O_RDWR);
490 system((char *)cmd->data);
492 } else if (pid > 0) {
501 cmddata = EAD_ENC_DATA(msg, cmd_data);
506 /* send keepalive packets every 200 ms so that the client doesn't timeout */
507 gettimeofday(&to, NULL);
508 memcpy(&tn, &to, sizeof(tn));
509 tv.tv_usec = PCAP_TIMEOUT * 1000;
513 FD_SET(pfd[0], &fds);
514 nfds = select(pfd[0] + 1, &fds, NULL, NULL, &tv);
517 bytes = read(pfd[0], cmddata->data, 1024);
521 if (!bytes && !child_pending)
523 DEBUG(3, "Sending %d bytes of console data, type=%d, timeout=%d\n", bytes, ntohl(msg->type), timeout);
524 ead_encrypt_message(msg, sizeof(struct ead_msg_cmd_data) + bytes);
525 ead_send_packet_clone(pkt);
526 gettimeofday(&tn, NULL);
527 } while (tn.tv_sec < to.tv_sec + timeout);
534 ead_encrypt_message(msg, sizeof(struct ead_msg_cmd_data));
542 parse_message(struct ead_packet *pkt, int len)
544 bool (*handler)(struct ead_packet *pkt, int len, int *nstate);
545 int min_len = sizeof(struct ead_packet);
547 int type = ntohl(pkt->msg.type);
549 if ((type >= EAD_TYPE_GET_PRIME) &&
553 if ((type != EAD_TYPE_PING) &&
554 ((ntohs(pkt->msg.sid) & EAD_INSTANCE_MASK) >>
555 EAD_INSTANCE_SHIFT) != instance->id)
560 handler = handle_ping;
562 case EAD_TYPE_SET_USERNAME:
563 handler = handle_set_username;
564 min_len += sizeof(struct ead_msg_user);
566 case EAD_TYPE_GET_PRIME:
567 handler = handle_get_prime;
569 case EAD_TYPE_SEND_A:
570 handler = handle_send_a;
571 min_len += sizeof(struct ead_msg_number);
573 case EAD_TYPE_SEND_AUTH:
574 handler = handle_send_auth;
575 min_len += sizeof(struct ead_msg_auth);
577 case EAD_TYPE_SEND_CMD:
578 handler = handle_send_cmd;
579 min_len += sizeof(struct ead_msg_cmd) + sizeof(struct ead_msg_encrypted);
586 DEBUG(2, "discarding packet: message too small\n");
590 pktbuf->msg.magic = htonl(EAD_MAGIC);
591 pktbuf->msg.type = htonl(type + 1);
592 pktbuf->msg.nid = htons(nid);
593 pktbuf->msg.sid = pkt->msg.sid;
596 if (handler(pkt, len, &nstate)) {
597 DEBUG(2, "sending response to packet type %d: %d\n", type + 1, ntohl(pktbuf->msg.len));
598 /* format response packet */
599 ead_send_packet_clone(pkt);
605 handle_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes)
607 struct ead_packet *pkt = (struct ead_packet *) bytes;
609 if (h->len < sizeof(struct ead_packet))
612 if (pkt->eh.ether_type != htons(ETHERTYPE_IP))
615 if (memcmp(pkt->eh.ether_dhost, "\xff\xff\xff\xff\xff\xff", 6) != 0)
618 if (pkt->proto != UIP_PROTO_UDP)
621 if (pkt->destport != htons(EAD_PORT))
624 if (pkt->msg.magic != htonl(EAD_MAGIC))
627 if (h->len < sizeof(struct ead_packet) + ntohl(pkt->msg.len))
630 if ((pkt->msg.nid != 0xffff) &&
631 (pkt->msg.nid != htons(nid)))
634 parse_message(pkt, h->len);
638 ead_pcap_reopen(bool first)
640 static char errbuf[PCAP_ERRBUF_SIZE] = "";
642 if (pcap_fp_rx && (pcap_fp_rx != pcap_fp))
643 pcap_close(pcap_fp_rx);
650 pcap_fp = pcap_open_live(instance->ifname, PCAP_MRU, 1, PCAP_TIMEOUT, errbuf);
652 if (instance->bridge[0])
653 pcap_fp_rx = pcap_open_live(instance->bridge, PCAP_MRU, 1, PCAP_TIMEOUT, errbuf);
656 pcap_fp_rx = pcap_fp;
657 pcap_setfilter(pcap_fp_rx, &pktfilter);
658 if (first && !pcap_fp) {
659 DEBUG(1, "WARNING: unable to open interface '%s'\n", instance->ifname);
672 if (pcap_dispatch(pcap_fp_rx, 1, handle_packet, NULL) < 0) {
673 ead_pcap_reopen(false);
681 usage(const char *prog)
683 fprintf(stderr, "Usage: %s [<options>]\n"
685 "\t-B Run in background mode\n"
686 "\t-d <device> Set the device to listen on\n"
687 "\t-D <name> Set the name of the device visible to clients\n"
688 "\t-p <file> Set the password file for authenticating\n"
689 "\t-P <file> Write a pidfile\n"
695 server_handle_sigchld(int sig)
697 struct ead_instance *in;
702 list_for_each(p, &instances) {
703 in = list_entry(p, struct ead_instance, list);
713 instance_handle_sigchld(int sig)
717 child_pending = false;
721 start_server(struct ead_instance *i)
733 signal(SIGCHLD, instance_handle_sigchld);
734 ead_pcap_reopen(true);
737 if (pcap_fp_rx != pcap_fp)
738 pcap_close(pcap_fp_rx);
745 start_servers(bool restart)
747 struct ead_instance *in;
750 list_for_each(p, &instances) {
751 in = list_entry(p, struct ead_instance, list);
761 stop_server(struct ead_instance *in, bool do_free)
764 kill(in->pid, SIGKILL);
773 server_handle_sigint(int sig)
775 struct ead_instance *in;
776 struct list_head *p, *tmp;
778 list_for_each_safe(p, tmp, &instances) {
779 in = list_entry(p, struct ead_instance, list);
780 stop_server(in, true);
787 check_bridge_port(const char *br, const char *port, void *arg)
789 struct ead_instance *in;
790 struct list_head *p, *tmp;
792 list_for_each(p, &instances) {
793 in = list_entry(p, struct ead_instance, list);
795 if (strcmp(in->ifname, port) != 0)
799 if (strcmp(in->bridge, br) == 0)
802 strncpy(in->bridge, br, sizeof(in->bridge));
803 DEBUG(2, "assigning port %s to bridge %s\n", in->ifname, in->bridge);
804 stop_server(in, false);
810 check_bridge(const char *name, void *arg)
812 br_foreach_port(name, check_bridge_port, arg);
818 check_all_interfaces(void)
821 struct ead_instance *in;
822 struct list_head *p, *tmp;
824 br_foreach_bridge(check_bridge, NULL);
826 /* look for interfaces that are no longer part of a bridge */
827 list_for_each(p, &instances) {
828 in = list_entry(p, struct ead_instance, list);
831 in->br_check = false;
832 } else if (in->bridge[0]) {
833 DEBUG(2, "removing port %s from bridge %s\n", in->ifname, in->bridge);
835 stop_server(in, false);
842 int main(int argc, char **argv)
844 struct ead_instance *in;
846 const char *pidfile = NULL;
847 bool background = false;
852 return usage(argv[0]);
854 INIT_LIST_HEAD(&instances);
855 while ((ch = getopt(argc, argv, "Bd:D:fhp:P:")) != -1) {
864 return usage(argv[0]);
866 in = malloc(sizeof(struct ead_instance));
867 memset(in, 0, sizeof(struct ead_instance));
868 INIT_LIST_HEAD(&in->list);
869 strncpy(in->ifname, optarg, sizeof(in->ifname) - 1);
870 list_add(&in->list, &instances);
877 passwd_file = optarg;
884 signal(SIGCHLD, server_handle_sigchld);
885 signal(SIGINT, server_handle_sigint);
886 signal(SIGTERM, server_handle_sigint);
887 signal(SIGKILL, server_handle_sigint);
890 fprintf(stderr, "Error: ead needs at least one interface\n");
898 fd = open("/dev/null", O_RDWR);
909 fd = open(pidfile, O_CREAT|O_WRONLY|O_EXCL, 0644);
911 len = sprintf(pid, "%d\n", getpid());
917 /* randomize the mac address */
918 get_random_bytes(ethmac + 3, 3);
919 nid = *(((u16_t *) ethmac) + 2);
921 start_servers(false);
928 check_all_interfaces();