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)
68 static char ethmac[6] = "\x00\x13\x37\x00\x00\x00"; /* last 3 bytes will be randomized */
69 static pcap_t *pcap_fp = NULL;
70 static pcap_t *pcap_fp_rx = NULL;
71 static const char *ifname = DEFAULT_IFNAME;
72 static char pktbuf_b[PCAP_MRU];
73 static struct ead_packet *pktbuf = (struct ead_packet *)pktbuf_b;
74 static u16_t nid = 0xffff; /* node id */
75 static char username[32] = "";
76 static int state = EAD_TYPE_SET_USERNAME;
77 static const char *passwd_file = PASSWD_FILE;
78 static const char password[MAXPARAMLEN];
79 static bool child_pending = false;
81 static unsigned char abuf[MAXPARAMLEN + 1];
82 static unsigned char pwbuf[MAXPARAMLEN];
83 static unsigned char saltbuf[MAXSALTLEN];
84 static unsigned char pw_saltbuf[MAXSALTLEN];
85 static struct list_head instances;
86 static const char *dev_name = DEFAULT_DEVNAME;
87 static bool nonfork = false;
90 static const char *brname = NULL;
94 struct list_head list;
103 static struct t_pwent tpe = {
106 .password.data = pwbuf,
108 .salt.data = saltbuf,
111 struct t_confent *tce = NULL;
112 static struct t_server *ts = NULL;
113 static struct t_num A, *B = NULL;
117 prepare_password(void)
119 static char lbuf[1024];
120 unsigned char dig[SHA_DIGESTSIZE];
121 BigInteger x, v, n, g;
123 int ulen = strlen(username);
126 lbuf[sizeof(lbuf) - 1] = 0;
128 f = fopen(passwd_file, "r");
132 while (fgets(lbuf, sizeof(lbuf) - 1, f) != NULL) {
135 if (strncmp(lbuf, username, ulen) != 0)
138 if (lbuf[ulen] != ':')
141 str = &lbuf[ulen + 1];
143 if (strncmp(str, "$1$", 3) != 0)
146 s2 = strchr(str + 3, '$');
150 if (s2 - str >= MAXSALTLEN)
153 strncpy((char *) pw_saltbuf, str, s2 - str);
154 pw_saltbuf[s2 - str] = 0;
156 s2 = strchr(s2, ':');
161 if (s2 - str >= MAXPARAMLEN)
164 strncpy((char *)password, str, MAXPARAMLEN);
174 tce = gettcid(tpe.index);
176 t_random(tpe.password.data, SALTLEN);
177 } while (memcmp(saltbuf, (char *)dig, sizeof(saltbuf)) == 0);
181 n = BigIntegerFromBytes(tce->modulus.data, tce->modulus.len);
182 g = BigIntegerFromBytes(tce->generator.data, tce->generator.len);
183 v = BigIntegerFromInt(0);
186 SHA1Update(&ctxt, (unsigned char *) username, strlen(username));
187 SHA1Update(&ctxt, (unsigned char *) ":", 1);
188 SHA1Update(&ctxt, (unsigned char *) password, strlen(password));
189 SHA1Final(dig, &ctxt);
192 SHA1Update(&ctxt, saltbuf, tpe.salt.len);
193 SHA1Update(&ctxt, dig, sizeof(dig));
194 SHA1Final(dig, &ctxt);
196 /* x = H(s, H(u, ':', p)) */
197 x = BigIntegerFromBytes(dig, sizeof(dig));
199 BigIntegerModExp(v, g, x, n);
200 tpe.password.len = BigIntegerToBytes(v, (unsigned char *)pwbuf);
210 chksum(u16_t sum, const u8_t *data, u16_t len)
214 const u8_t *last_byte;
217 last_byte = data + len - 1;
219 while(dataptr < last_byte) { /* At least two more bytes */
220 t = (dataptr[0] << 8) + dataptr[1];
228 if(dataptr == last_byte) {
229 t = (dataptr[0] << 8) + 0;
236 /* Return sum in host byte order. */
241 ead_send_packet_clone(struct ead_packet *pkt)
245 memcpy(pktbuf, pkt, offsetof(struct ead_packet, msg));
246 memcpy(pktbuf->eh.ether_shost, ethmac, 6);
247 memcpy(pktbuf->eh.ether_dhost, pkt->eh.ether_shost, 6);
250 len = sizeof(struct ead_packet) - sizeof(struct ether_header) + ntohl(pktbuf->msg.len);
251 pktbuf->len[0] = len >> 8;
252 pktbuf->len[1] = len & 0xff;
253 memcpy(pktbuf->srcipaddr, &pkt->msg.ip, 4);
254 memcpy(pktbuf->destipaddr, pkt->srcipaddr, 4);
257 pktbuf->ipchksum = 0;
258 sum = chksum(0, (void *) &pktbuf->vhl, UIP_IPH_LEN);
261 pktbuf->ipchksum = htons(~sum);
264 pktbuf->srcport = pkt->destport;
265 pktbuf->destport = pkt->srcport;
269 pktbuf->udplen = htons(len);
270 pktbuf->udpchksum = 0;
271 sum = len + UIP_PROTO_UDP;
272 sum = chksum(sum, (void *) &pktbuf->srcipaddr[0], 8); /* src, dest ip */
273 sum = chksum(sum, (void *) &pktbuf->srcport, len);
276 pktbuf->udpchksum = htons(~sum);
277 pcap_sendpacket(pcap_fp, (void *) pktbuf, sizeof(struct ead_packet) + ntohl(pktbuf->msg.len));
281 set_state(int nstate)
286 if (nstate < state) {
287 if ((nstate < EAD_TYPE_GET_PRIME) &&
288 (state >= EAD_TYPE_GET_PRIME)) {
296 case EAD_TYPE_SET_USERNAME:
297 if (!prepare_password())
299 ts = t_serveropenraw(&tpe, tce);
303 case EAD_TYPE_GET_PRIME:
304 B = t_servergenexp(ts);
306 case EAD_TYPE_SEND_A:
307 skey = t_servergetkey(ts, &A);
321 handle_ping(struct ead_packet *pkt, int len, int *nstate)
323 struct ead_msg *msg = &pktbuf->msg;
324 struct ead_msg_pong *pong = EAD_DATA(msg, pong);
327 slen = strlen(dev_name);
331 msg->len = htonl(sizeof(struct ead_msg_pong) + slen);
332 strncpy(pong->name, dev_name, slen);
333 pong->name[slen] = 0;
334 pong->auth_type = htons(EAD_AUTH_MD5);
340 handle_set_username(struct ead_packet *pkt, int len, int *nstate)
342 struct ead_msg *msg = &pkt->msg;
343 struct ead_msg_user *user = EAD_DATA(msg, user);
345 set_state(EAD_TYPE_SET_USERNAME); /* clear old state */
346 strncpy(username, user->username, sizeof(username));
347 username[sizeof(username)] = 0;
352 *nstate = EAD_TYPE_GET_PRIME;
357 handle_get_prime(struct ead_packet *pkt, int len, int *nstate)
359 struct ead_msg *msg = &pktbuf->msg;
360 struct ead_msg_salt *salt = EAD_DATA(msg, salt);
362 msg->len = htonl(sizeof(struct ead_msg_salt));
363 salt->prime = tce->index - 1;
364 salt->len = ts->s.len;
365 memcpy(salt->salt, ts->s.data, ts->s.len);
366 memcpy(salt->ext_salt, pw_saltbuf, MAXSALTLEN);
368 *nstate = EAD_TYPE_SEND_A;
373 handle_send_a(struct ead_packet *pkt, int len, int *nstate)
375 struct ead_msg *msg = &pkt->msg;
376 struct ead_msg_number *number = EAD_DATA(msg, number);
377 len = ntohl(msg->len) - sizeof(struct ead_msg_number);
379 if (len > MAXPARAMLEN + 1)
384 memcpy(A.data, number->data, len);
387 number = EAD_DATA(msg, number);
388 msg->len = htonl(sizeof(struct ead_msg_number) + B->len);
389 memcpy(number->data, B->data, B->len);
391 *nstate = EAD_TYPE_SEND_AUTH;
396 handle_send_auth(struct ead_packet *pkt, int len, int *nstate)
398 struct ead_msg *msg = &pkt->msg;
399 struct ead_msg_auth *auth = EAD_DATA(msg, auth);
401 if (t_serververify(ts, auth->data) != 0) {
402 DEBUG(2, "Client authentication failed\n");
403 *nstate = EAD_TYPE_SET_USERNAME;
408 auth = EAD_DATA(msg, auth);
409 msg->len = htonl(sizeof(struct ead_msg_auth));
411 DEBUG(2, "Client authentication successful\n");
412 memcpy(auth->data, t_serverresponse(ts), sizeof(auth->data));
414 *nstate = EAD_TYPE_SEND_CMD;
419 handle_send_cmd(struct ead_packet *pkt, int len, int *nstate)
421 struct ead_msg *msg = &pkt->msg;
422 struct ead_msg_cmd *cmd = EAD_ENC_DATA(msg, cmd);
423 struct ead_msg_cmd_data *cmddata;
424 struct timeval tv, to, tn;
433 datalen = ead_decrypt_message(msg) - sizeof(struct ead_msg_cmd);
437 type = ntohs(cmd->type);
438 timeout = ntohs(cmd->timeout);
441 cmd->data[datalen] = 0;
447 fcntl(pfd[0], F_SETFL, O_NONBLOCK | fcntl(pfd[0], F_GETFL));
448 child_pending = true;
452 fd = open("/dev/null", O_RDWR);
458 system((char *)cmd->data);
460 } else if (pid > 0) {
463 timeout = EAD_CMD_TIMEOUT;
469 case EAD_CMD_BACKGROUND:
472 /* close stdin, stdout, stderr, replace with fd to /dev/null */
473 fd = open("/dev/null", O_RDWR);
479 system((char *)cmd->data);
481 } else if (pid > 0) {
490 cmddata = EAD_ENC_DATA(msg, cmd_data);
495 /* send keepalive packets every 200 ms so that the client doesn't timeout */
496 gettimeofday(&to, NULL);
497 memcpy(&tn, &to, sizeof(tn));
498 tv.tv_usec = PCAP_TIMEOUT * 1000;
502 FD_SET(pfd[0], &fds);
503 nfds = select(pfd[0] + 1, &fds, NULL, NULL, &tv);
506 bytes = read(pfd[0], cmddata->data, 1024);
510 if (!bytes && !child_pending)
512 DEBUG(3, "Sending %d bytes of console data, type=%d, timeout=%d\n", bytes, ntohl(msg->type), timeout);
513 ead_encrypt_message(msg, sizeof(struct ead_msg_cmd_data) + bytes);
514 ead_send_packet_clone(pkt);
515 gettimeofday(&tn, NULL);
516 } while (tn.tv_sec < to.tv_sec + timeout);
523 ead_encrypt_message(msg, sizeof(struct ead_msg_cmd_data));
531 parse_message(struct ead_packet *pkt, int len)
533 bool (*handler)(struct ead_packet *pkt, int len, int *nstate);
534 int min_len = sizeof(struct ead_packet);
536 int type = ntohl(pkt->msg.type);
538 if ((type >= EAD_TYPE_GET_PRIME) &&
544 handler = handle_ping;
546 case EAD_TYPE_SET_USERNAME:
547 handler = handle_set_username;
548 min_len += sizeof(struct ead_msg_user);
550 case EAD_TYPE_GET_PRIME:
551 handler = handle_get_prime;
553 case EAD_TYPE_SEND_A:
554 handler = handle_send_a;
555 min_len += sizeof(struct ead_msg_number);
557 case EAD_TYPE_SEND_AUTH:
558 handler = handle_send_auth;
559 min_len += sizeof(struct ead_msg_auth);
561 case EAD_TYPE_SEND_CMD:
562 handler = handle_send_cmd;
563 min_len += sizeof(struct ead_msg_cmd) + sizeof(struct ead_msg_encrypted);
570 DEBUG(2, "discarding packet: message too small\n");
574 pktbuf->msg.magic = htonl(EAD_MAGIC);
575 pktbuf->msg.type = htonl(type + 1);
576 pktbuf->msg.nid = htons(nid);
579 if (handler(pkt, len, &nstate)) {
580 DEBUG(2, "sending response to packet type %d: %d\n", type + 1, ntohl(pktbuf->msg.len));
581 /* format response packet */
582 ead_send_packet_clone(pkt);
588 handle_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes)
590 struct ead_packet *pkt = (struct ead_packet *) bytes;
592 if (h->len < sizeof(struct ead_packet))
595 if (pkt->eh.ether_type != htons(ETHERTYPE_IP))
598 if (memcmp(pkt->eh.ether_dhost, "\xff\xff\xff\xff\xff\xff", 6) != 0)
601 if (pkt->proto != UIP_PROTO_UDP)
604 if (pkt->destport != htons(EAD_PORT))
607 if (pkt->msg.magic != htonl(EAD_MAGIC))
610 if (h->len < sizeof(struct ead_packet) + ntohl(pkt->msg.len))
613 if ((pkt->msg.nid != 0xffff) &&
614 (pkt->msg.nid != htons(nid)))
617 parse_message(pkt, h->len);
621 ead_pcap_reopen(bool first)
623 static char errbuf[PCAP_ERRBUF_SIZE] = "";
625 if (pcap_fp_rx && (pcap_fp_rx != pcap_fp))
626 pcap_close(pcap_fp_rx);
633 pcap_fp = pcap_open_live(ifname, PCAP_MRU, 1, PCAP_TIMEOUT, errbuf);
636 pcap_fp_rx = pcap_open_live(brname, PCAP_MRU, 1, PCAP_TIMEOUT, errbuf);
639 pcap_fp_rx = pcap_fp;
640 pcap_setfilter(pcap_fp_rx, &pktfilter);
641 if (first && !pcap_fp) {
642 DEBUG(1, "WARNING: unable to open interface '%s'\n", ifname);
655 if (pcap_dispatch(pcap_fp_rx, 1, handle_packet, NULL) < 0) {
656 ead_pcap_reopen(false);
664 usage(const char *prog)
666 fprintf(stderr, "Usage: %s [<options>]\n"
668 "\t-B Run in background mode\n"
669 "\t-d <device> Set the device to listen on\n"
670 "\t-D <name> Set the name of the device visible to clients\n"
671 "\t-p <file> Set the password file for authenticating\n"
672 "\t-P <file> Write a pidfile\n"
678 server_handle_sigchld(int sig)
680 struct ead_instance *in;
685 list_for_each(p, &instances) {
686 in = list_entry(p, struct ead_instance, list);
696 instance_handle_sigchld(int sig)
700 child_pending = false;
704 start_server(struct ead_instance *i)
715 signal(SIGCHLD, instance_handle_sigchld);
721 ead_pcap_reopen(true);
724 if (pcap_fp_rx != pcap_fp)
725 pcap_close(pcap_fp_rx);
732 start_servers(bool restart)
734 struct ead_instance *in;
737 list_for_each(p, &instances) {
738 in = list_entry(p, struct ead_instance, list);
748 stop_server(struct ead_instance *in, bool do_free)
751 kill(in->pid, SIGKILL);
760 server_handle_sigint(int sig)
762 struct ead_instance *in;
763 struct list_head *p, *tmp;
765 list_for_each_safe(p, tmp, &instances) {
766 in = list_entry(p, struct ead_instance, list);
767 stop_server(in, true);
774 check_bridge_port(const char *br, const char *port, void *arg)
776 struct ead_instance *in;
777 struct list_head *p, *tmp;
779 list_for_each(p, &instances) {
780 in = list_entry(p, struct ead_instance, list);
782 if (strcmp(in->name, port) != 0)
786 if (strcmp(in->bridge, br) == 0)
789 strncpy(in->bridge, br, sizeof(in->bridge));
790 DEBUG(2, "assigning port %s to bridge %s\n", in->name, in->bridge);
791 stop_server(in, false);
797 check_bridge(const char *name, void *arg)
799 br_foreach_port(name, check_bridge_port, arg);
805 check_all_interfaces(void)
808 struct ead_instance *in;
809 struct list_head *p, *tmp;
811 br_foreach_bridge(check_bridge, NULL);
813 /* look for interfaces that are no longer part of a bridge */
814 list_for_each(p, &instances) {
815 in = list_entry(p, struct ead_instance, list);
818 in->br_check = false;
819 } else if (in->bridge[0]) {
820 DEBUG(2, "removing port %s from bridge %s\n", in->name, in->bridge);
822 stop_server(in, false);
829 int main(int argc, char **argv)
831 struct ead_instance *in;
834 const char *pidfile = NULL;
835 bool background = false;
839 return usage(argv[0]);
841 INIT_LIST_HEAD(&instances);
842 while ((ch = getopt(argc, argv, "Bd:D:fhp:P:")) != -1) {
851 return usage(argv[0]);
853 in = malloc(sizeof(struct ead_instance));
854 memset(in, 0, sizeof(struct ead_instance));
855 INIT_LIST_HEAD(&in->list);
856 strncpy(in->name, optarg, sizeof(in->name) - 1);
857 list_add(&in->list, &instances);
864 passwd_file = optarg;
871 signal(SIGCHLD, server_handle_sigchld);
872 signal(SIGINT, server_handle_sigint);
873 signal(SIGTERM, server_handle_sigint);
874 signal(SIGKILL, server_handle_sigint);
877 fprintf(stderr, "Error: ead needs at least one interface\n");
885 fd = open("/dev/null", O_RDWR);
896 fd = open(pidfile, O_CREAT|O_WRONLY|O_EXCL, 0644);
898 len = sprintf(pid, "%d\n", getpid());
904 /* randomize the mac address */
905 fd = open("/dev/urandom", O_RDONLY);
910 read(fd, ethmac + 3, 3);
912 nid = *(((u16_t *) ethmac) + 2);
914 start_servers(false);
921 check_all_interfaces();