| 1 | /* |
| 2 | * Emergency Access Daemon |
| 3 | * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org> |
| 4 | * |
| 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 |
| 8 | * |
| 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. |
| 13 | */ |
| 14 | |
| 15 | #include <sys/types.h> |
| 16 | #include <sys/time.h> |
| 17 | #include <sys/select.h> |
| 18 | #include <stdio.h> |
| 19 | #include <stddef.h> |
| 20 | #include <stdlib.h> |
| 21 | #include <string.h> |
| 22 | #include <unistd.h> |
| 23 | #include <stdbool.h> |
| 24 | #include <fcntl.h> |
| 25 | #include <signal.h> |
| 26 | #include <pcap.h> |
| 27 | #include <pcap-bpf.h> |
| 28 | #include <t_pwd.h> |
| 29 | #include <t_read.h> |
| 30 | #include <t_sha.h> |
| 31 | #include <t_defines.h> |
| 32 | #include <t_server.h> |
| 33 | |
| 34 | #include "list.h" |
| 35 | #include "ead.h" |
| 36 | #include "ead-pcap.h" |
| 37 | #include "ead-crypt.h" |
| 38 | |
| 39 | #include "filter.c" |
| 40 | |
| 41 | #ifdef linux |
| 42 | #include "libbridge_init.c" |
| 43 | #endif |
| 44 | |
| 45 | #ifdef linux |
| 46 | #include <linux/if_packet.h> |
| 47 | #endif |
| 48 | |
| 49 | #define PASSWD_FILE "/etc/passwd" |
| 50 | |
| 51 | #ifndef DEFAULT_IFNAME |
| 52 | #define DEFAULT_IFNAME "eth0" |
| 53 | #endif |
| 54 | |
| 55 | #ifndef DEFAULT_DEVNAME |
| 56 | #define DEFAULT_DEVNAME "Unknown" |
| 57 | #endif |
| 58 | |
| 59 | #define PCAP_MRU 1600 |
| 60 | #define PCAP_TIMEOUT 200 |
| 61 | |
| 62 | #if EAD_DEBUGLEVEL >= 1 |
| 63 | #define DEBUG(n, format, ...) do { \ |
| 64 | if (EAD_DEBUGLEVEL >= n) \ |
| 65 | fprintf(stderr, format, ##__VA_ARGS__); \ |
| 66 | } while (0); |
| 67 | |
| 68 | #else |
| 69 | #define DEBUG(n, format, ...) do {} while(0) |
| 70 | #endif |
| 71 | |
| 72 | struct ead_instance { |
| 73 | struct list_head list; |
| 74 | char ifname[16]; |
| 75 | int pid; |
| 76 | char id; |
| 77 | #ifdef linux |
| 78 | char bridge[16]; |
| 79 | bool br_check; |
| 80 | #endif |
| 81 | }; |
| 82 | |
| 83 | static char ethmac[6] = "\x00\x13\x37\x00\x00\x00"; /* last 3 bytes will be randomized */ |
| 84 | static pcap_t *pcap_fp = NULL; |
| 85 | static pcap_t *pcap_fp_rx = NULL; |
| 86 | static char pktbuf_b[PCAP_MRU]; |
| 87 | static struct ead_packet *pktbuf = (struct ead_packet *)pktbuf_b; |
| 88 | static u16_t nid = 0xffff; /* node id */ |
| 89 | static char username[32] = ""; |
| 90 | static int state = EAD_TYPE_SET_USERNAME; |
| 91 | static const char *passwd_file = PASSWD_FILE; |
| 92 | static const char password[MAXPARAMLEN]; |
| 93 | static bool child_pending = false; |
| 94 | |
| 95 | static unsigned char abuf[MAXPARAMLEN + 1]; |
| 96 | static unsigned char pwbuf[MAXPARAMLEN]; |
| 97 | static unsigned char saltbuf[MAXSALTLEN]; |
| 98 | static unsigned char pw_saltbuf[MAXSALTLEN]; |
| 99 | static struct list_head instances; |
| 100 | static const char *dev_name = DEFAULT_DEVNAME; |
| 101 | static bool nonfork = false; |
| 102 | static struct ead_instance *instance = NULL; |
| 103 | |
| 104 | static struct t_pwent tpe = { |
| 105 | .name = username, |
| 106 | .index = 1, |
| 107 | .password.data = pwbuf, |
| 108 | .password.len = 0, |
| 109 | .salt.data = saltbuf, |
| 110 | .salt.len = 0, |
| 111 | }; |
| 112 | struct t_confent *tce = NULL; |
| 113 | static struct t_server *ts = NULL; |
| 114 | static struct t_num A, *B = NULL; |
| 115 | unsigned char *skey; |
| 116 | |
| 117 | static void |
| 118 | set_recv_type(pcap_t *p, bool rx) |
| 119 | { |
| 120 | #ifdef PACKET_RECV_TYPE |
| 121 | struct sockaddr_ll sll; |
| 122 | struct ifreq ifr; |
| 123 | int ifindex, mask; |
| 124 | int fd, ret; |
| 125 | |
| 126 | fd = pcap_get_selectable_fd(p); |
| 127 | if (fd < 0) |
| 128 | return; |
| 129 | |
| 130 | if (rx) |
| 131 | mask = 1 << PACKET_BROADCAST; |
| 132 | else |
| 133 | mask = 0; |
| 134 | |
| 135 | ret = setsockopt(fd, SOL_PACKET, PACKET_RECV_TYPE, &mask, sizeof(mask)); |
| 136 | #endif |
| 137 | } |
| 138 | |
| 139 | |
| 140 | static pcap_t * |
| 141 | ead_open_pcap(const char *ifname, char *errbuf, bool rx) |
| 142 | { |
| 143 | pcap_t *p; |
| 144 | |
| 145 | p = pcap_create(ifname, errbuf); |
| 146 | if (p == NULL) |
| 147 | goto out; |
| 148 | |
| 149 | pcap_set_snaplen(p, PCAP_MRU); |
| 150 | pcap_set_promisc(p, rx); |
| 151 | pcap_set_timeout(p, PCAP_TIMEOUT); |
| 152 | #ifdef HAS_PROTO_EXTENSION |
| 153 | pcap_set_protocol(p, (rx ? htons(ETH_P_IP) : 0)); |
| 154 | #endif |
| 155 | pcap_set_buffer_size(p, (rx ? 10 : 1) * PCAP_MRU); |
| 156 | pcap_activate(p); |
| 157 | set_recv_type(p, rx); |
| 158 | out: |
| 159 | return p; |
| 160 | } |
| 161 | |
| 162 | static void |
| 163 | get_random_bytes(void *ptr, int len) |
| 164 | { |
| 165 | int fd; |
| 166 | |
| 167 | fd = open("/dev/urandom", O_RDONLY); |
| 168 | if (fd < 0) { |
| 169 | perror("open"); |
| 170 | exit(1); |
| 171 | } |
| 172 | read(fd, ptr, len); |
| 173 | close(fd); |
| 174 | } |
| 175 | |
| 176 | static bool |
| 177 | prepare_password(void) |
| 178 | { |
| 179 | static char lbuf[1024]; |
| 180 | unsigned char dig[SHA_DIGESTSIZE]; |
| 181 | BigInteger x, v, n, g; |
| 182 | SHA1_CTX ctxt; |
| 183 | int ulen = strlen(username); |
| 184 | FILE *f; |
| 185 | |
| 186 | lbuf[sizeof(lbuf) - 1] = 0; |
| 187 | |
| 188 | f = fopen(passwd_file, "r"); |
| 189 | if (!f) |
| 190 | return false; |
| 191 | |
| 192 | while (fgets(lbuf, sizeof(lbuf) - 1, f) != NULL) { |
| 193 | char *str, *s2; |
| 194 | |
| 195 | if (strncmp(lbuf, username, ulen) != 0) |
| 196 | continue; |
| 197 | |
| 198 | if (lbuf[ulen] != ':') |
| 199 | continue; |
| 200 | |
| 201 | str = &lbuf[ulen + 1]; |
| 202 | |
| 203 | if (strncmp(str, "$1$", 3) != 0) |
| 204 | continue; |
| 205 | |
| 206 | s2 = strchr(str + 3, '$'); |
| 207 | if (!s2) |
| 208 | continue; |
| 209 | |
| 210 | if (s2 - str >= MAXSALTLEN) |
| 211 | continue; |
| 212 | |
| 213 | strncpy((char *) pw_saltbuf, str, s2 - str); |
| 214 | pw_saltbuf[s2 - str] = 0; |
| 215 | |
| 216 | s2 = strchr(s2, ':'); |
| 217 | if (!s2) |
| 218 | continue; |
| 219 | |
| 220 | *s2 = 0; |
| 221 | if (s2 - str >= MAXPARAMLEN) |
| 222 | continue; |
| 223 | |
| 224 | strncpy((char *)password, str, MAXPARAMLEN); |
| 225 | fclose(f); |
| 226 | goto hash_password; |
| 227 | } |
| 228 | |
| 229 | /* not found */ |
| 230 | fclose(f); |
| 231 | return false; |
| 232 | |
| 233 | hash_password: |
| 234 | tce = gettcid(tpe.index); |
| 235 | do { |
| 236 | t_random(tpe.password.data, SALTLEN); |
| 237 | } while (memcmp(saltbuf, (char *)dig, sizeof(saltbuf)) == 0); |
| 238 | if (saltbuf[0] == 0) |
| 239 | saltbuf[0] = 0xff; |
| 240 | |
| 241 | n = BigIntegerFromBytes(tce->modulus.data, tce->modulus.len); |
| 242 | g = BigIntegerFromBytes(tce->generator.data, tce->generator.len); |
| 243 | v = BigIntegerFromInt(0); |
| 244 | |
| 245 | SHA1Init(&ctxt); |
| 246 | SHA1Update(&ctxt, (unsigned char *) username, strlen(username)); |
| 247 | SHA1Update(&ctxt, (unsigned char *) ":", 1); |
| 248 | SHA1Update(&ctxt, (unsigned char *) password, strlen(password)); |
| 249 | SHA1Final(dig, &ctxt); |
| 250 | |
| 251 | SHA1Init(&ctxt); |
| 252 | SHA1Update(&ctxt, saltbuf, tpe.salt.len); |
| 253 | SHA1Update(&ctxt, dig, sizeof(dig)); |
| 254 | SHA1Final(dig, &ctxt); |
| 255 | |
| 256 | /* x = H(s, H(u, ':', p)) */ |
| 257 | x = BigIntegerFromBytes(dig, sizeof(dig)); |
| 258 | |
| 259 | BigIntegerModExp(v, g, x, n); |
| 260 | tpe.password.len = BigIntegerToBytes(v, (unsigned char *)pwbuf); |
| 261 | |
| 262 | BigIntegerFree(v); |
| 263 | BigIntegerFree(x); |
| 264 | BigIntegerFree(g); |
| 265 | BigIntegerFree(n); |
| 266 | return true; |
| 267 | } |
| 268 | |
| 269 | static u16_t |
| 270 | chksum(u16_t sum, const u8_t *data, u16_t len) |
| 271 | { |
| 272 | u16_t t; |
| 273 | const u8_t *dataptr; |
| 274 | const u8_t *last_byte; |
| 275 | |
| 276 | dataptr = data; |
| 277 | last_byte = data + len - 1; |
| 278 | |
| 279 | while(dataptr < last_byte) { /* At least two more bytes */ |
| 280 | t = (dataptr[0] << 8) + dataptr[1]; |
| 281 | sum += t; |
| 282 | if(sum < t) { |
| 283 | sum++; /* carry */ |
| 284 | } |
| 285 | dataptr += 2; |
| 286 | } |
| 287 | |
| 288 | if(dataptr == last_byte) { |
| 289 | t = (dataptr[0] << 8) + 0; |
| 290 | sum += t; |
| 291 | if(sum < t) { |
| 292 | sum++; /* carry */ |
| 293 | } |
| 294 | } |
| 295 | |
| 296 | /* Return sum in host byte order. */ |
| 297 | return sum; |
| 298 | } |
| 299 | |
| 300 | static void |
| 301 | ead_send_packet_clone(struct ead_packet *pkt) |
| 302 | { |
| 303 | u16_t len, sum; |
| 304 | |
| 305 | memcpy(pktbuf, pkt, offsetof(struct ead_packet, msg)); |
| 306 | memcpy(pktbuf->eh.ether_shost, ethmac, 6); |
| 307 | memcpy(pktbuf->eh.ether_dhost, pkt->eh.ether_shost, 6); |
| 308 | |
| 309 | /* ip header */ |
| 310 | len = sizeof(struct ead_packet) - sizeof(struct ether_header) + ntohl(pktbuf->msg.len); |
| 311 | pktbuf->len[0] = len >> 8; |
| 312 | pktbuf->len[1] = len & 0xff; |
| 313 | memcpy(pktbuf->srcipaddr, &pkt->msg.ip, 4); |
| 314 | memcpy(pktbuf->destipaddr, pkt->srcipaddr, 4); |
| 315 | |
| 316 | /* ip checksum */ |
| 317 | pktbuf->ipchksum = 0; |
| 318 | sum = chksum(0, (void *) &pktbuf->vhl, UIP_IPH_LEN); |
| 319 | if (sum == 0) |
| 320 | sum = 0xffff; |
| 321 | pktbuf->ipchksum = htons(~sum); |
| 322 | |
| 323 | /* udp header */ |
| 324 | pktbuf->srcport = pkt->destport; |
| 325 | pktbuf->destport = pkt->srcport; |
| 326 | |
| 327 | /* udp checksum */ |
| 328 | len -= UIP_IPH_LEN; |
| 329 | pktbuf->udplen = htons(len); |
| 330 | pktbuf->udpchksum = 0; |
| 331 | sum = len + UIP_PROTO_UDP; |
| 332 | sum = chksum(sum, (void *) &pktbuf->srcipaddr[0], 8); /* src, dest ip */ |
| 333 | sum = chksum(sum, (void *) &pktbuf->srcport, len); |
| 334 | if (sum == 0) |
| 335 | sum = 0xffff; |
| 336 | pktbuf->udpchksum = htons(~sum); |
| 337 | pcap_sendpacket(pcap_fp, (void *) pktbuf, sizeof(struct ead_packet) + ntohl(pktbuf->msg.len)); |
| 338 | } |
| 339 | |
| 340 | static void |
| 341 | set_state(int nstate) |
| 342 | { |
| 343 | if (state == nstate) |
| 344 | return; |
| 345 | |
| 346 | if (nstate < state) { |
| 347 | if ((nstate < EAD_TYPE_GET_PRIME) && |
| 348 | (state >= EAD_TYPE_GET_PRIME)) { |
| 349 | t_serverclose(ts); |
| 350 | ts = NULL; |
| 351 | } |
| 352 | goto done; |
| 353 | } |
| 354 | |
| 355 | switch(state) { |
| 356 | case EAD_TYPE_SET_USERNAME: |
| 357 | if (!prepare_password()) |
| 358 | goto error; |
| 359 | ts = t_serveropenraw(&tpe, tce); |
| 360 | if (!ts) |
| 361 | goto error; |
| 362 | break; |
| 363 | case EAD_TYPE_GET_PRIME: |
| 364 | B = t_servergenexp(ts); |
| 365 | break; |
| 366 | case EAD_TYPE_SEND_A: |
| 367 | skey = t_servergetkey(ts, &A); |
| 368 | if (!skey) |
| 369 | goto error; |
| 370 | |
| 371 | ead_set_key(skey); |
| 372 | break; |
| 373 | } |
| 374 | done: |
| 375 | state = nstate; |
| 376 | error: |
| 377 | return; |
| 378 | } |
| 379 | |
| 380 | static bool |
| 381 | handle_ping(struct ead_packet *pkt, int len, int *nstate) |
| 382 | { |
| 383 | struct ead_msg *msg = &pktbuf->msg; |
| 384 | struct ead_msg_pong *pong = EAD_DATA(msg, pong); |
| 385 | int slen; |
| 386 | |
| 387 | slen = strlen(dev_name); |
| 388 | if (slen > 1024) |
| 389 | slen = 1024; |
| 390 | |
| 391 | msg->len = htonl(sizeof(struct ead_msg_pong) + slen); |
| 392 | strncpy(pong->name, dev_name, slen); |
| 393 | pong->name[slen] = 0; |
| 394 | pong->auth_type = htons(EAD_AUTH_MD5); |
| 395 | |
| 396 | return true; |
| 397 | } |
| 398 | |
| 399 | static bool |
| 400 | handle_set_username(struct ead_packet *pkt, int len, int *nstate) |
| 401 | { |
| 402 | struct ead_msg *msg = &pkt->msg; |
| 403 | struct ead_msg_user *user = EAD_DATA(msg, user); |
| 404 | |
| 405 | set_state(EAD_TYPE_SET_USERNAME); /* clear old state */ |
| 406 | strncpy(username, user->username, sizeof(username)); |
| 407 | username[sizeof(username) - 1] = 0; |
| 408 | |
| 409 | msg = &pktbuf->msg; |
| 410 | msg->len = 0; |
| 411 | |
| 412 | *nstate = EAD_TYPE_GET_PRIME; |
| 413 | return true; |
| 414 | } |
| 415 | |
| 416 | static bool |
| 417 | handle_get_prime(struct ead_packet *pkt, int len, int *nstate) |
| 418 | { |
| 419 | struct ead_msg *msg = &pktbuf->msg; |
| 420 | struct ead_msg_salt *salt = EAD_DATA(msg, salt); |
| 421 | |
| 422 | msg->len = htonl(sizeof(struct ead_msg_salt)); |
| 423 | salt->prime = tce->index - 1; |
| 424 | salt->len = ts->s.len; |
| 425 | memcpy(salt->salt, ts->s.data, ts->s.len); |
| 426 | memcpy(salt->ext_salt, pw_saltbuf, MAXSALTLEN); |
| 427 | |
| 428 | *nstate = EAD_TYPE_SEND_A; |
| 429 | return true; |
| 430 | } |
| 431 | |
| 432 | static bool |
| 433 | handle_send_a(struct ead_packet *pkt, int len, int *nstate) |
| 434 | { |
| 435 | struct ead_msg *msg = &pkt->msg; |
| 436 | struct ead_msg_number *number = EAD_DATA(msg, number); |
| 437 | len = ntohl(msg->len) - sizeof(struct ead_msg_number); |
| 438 | |
| 439 | if (len > MAXPARAMLEN + 1) |
| 440 | return false; |
| 441 | |
| 442 | A.len = len; |
| 443 | A.data = abuf; |
| 444 | memcpy(A.data, number->data, len); |
| 445 | |
| 446 | msg = &pktbuf->msg; |
| 447 | number = EAD_DATA(msg, number); |
| 448 | msg->len = htonl(sizeof(struct ead_msg_number) + B->len); |
| 449 | memcpy(number->data, B->data, B->len); |
| 450 | |
| 451 | *nstate = EAD_TYPE_SEND_AUTH; |
| 452 | return true; |
| 453 | } |
| 454 | |
| 455 | static bool |
| 456 | handle_send_auth(struct ead_packet *pkt, int len, int *nstate) |
| 457 | { |
| 458 | struct ead_msg *msg = &pkt->msg; |
| 459 | struct ead_msg_auth *auth = EAD_DATA(msg, auth); |
| 460 | |
| 461 | if (t_serververify(ts, auth->data) != 0) { |
| 462 | DEBUG(2, "Client authentication failed\n"); |
| 463 | *nstate = EAD_TYPE_SET_USERNAME; |
| 464 | return false; |
| 465 | } |
| 466 | |
| 467 | msg = &pktbuf->msg; |
| 468 | auth = EAD_DATA(msg, auth); |
| 469 | msg->len = htonl(sizeof(struct ead_msg_auth)); |
| 470 | |
| 471 | DEBUG(2, "Client authentication successful\n"); |
| 472 | memcpy(auth->data, t_serverresponse(ts), sizeof(auth->data)); |
| 473 | |
| 474 | *nstate = EAD_TYPE_SEND_CMD; |
| 475 | return true; |
| 476 | } |
| 477 | |
| 478 | static bool |
| 479 | handle_send_cmd(struct ead_packet *pkt, int len, int *nstate) |
| 480 | { |
| 481 | struct ead_msg *msg = &pkt->msg; |
| 482 | struct ead_msg_cmd *cmd = EAD_ENC_DATA(msg, cmd); |
| 483 | struct ead_msg_cmd_data *cmddata; |
| 484 | struct timeval tv, to, tn; |
| 485 | int pfd[2], fd; |
| 486 | fd_set fds; |
| 487 | pid_t pid; |
| 488 | bool stream = false; |
| 489 | int timeout; |
| 490 | int type; |
| 491 | int datalen; |
| 492 | |
| 493 | datalen = ead_decrypt_message(msg) - sizeof(struct ead_msg_cmd); |
| 494 | if (datalen <= 0) |
| 495 | return false; |
| 496 | |
| 497 | type = ntohs(cmd->type); |
| 498 | timeout = ntohs(cmd->timeout); |
| 499 | |
| 500 | FD_ZERO(&fds); |
| 501 | cmd->data[datalen] = 0; |
| 502 | switch(type) { |
| 503 | case EAD_CMD_NORMAL: |
| 504 | if (pipe(pfd) < 0) |
| 505 | return false; |
| 506 | |
| 507 | fcntl(pfd[0], F_SETFL, O_NONBLOCK | fcntl(pfd[0], F_GETFL)); |
| 508 | child_pending = true; |
| 509 | pid = fork(); |
| 510 | if (pid == 0) { |
| 511 | close(pfd[0]); |
| 512 | fd = open("/dev/null", O_RDWR); |
| 513 | if (fd > 0) { |
| 514 | dup2(fd, 0); |
| 515 | dup2(pfd[1], 1); |
| 516 | dup2(pfd[1], 2); |
| 517 | } |
| 518 | system((char *)cmd->data); |
| 519 | exit(0); |
| 520 | } else if (pid > 0) { |
| 521 | close(pfd[1]); |
| 522 | if (!timeout) |
| 523 | timeout = EAD_CMD_TIMEOUT; |
| 524 | |
| 525 | stream = true; |
| 526 | break; |
| 527 | } |
| 528 | return false; |
| 529 | case EAD_CMD_BACKGROUND: |
| 530 | pid = fork(); |
| 531 | if (pid == 0) { |
| 532 | /* close stdin, stdout, stderr, replace with fd to /dev/null */ |
| 533 | fd = open("/dev/null", O_RDWR); |
| 534 | if (fd > 0) { |
| 535 | dup2(fd, 0); |
| 536 | dup2(fd, 1); |
| 537 | dup2(fd, 2); |
| 538 | } |
| 539 | system((char *)cmd->data); |
| 540 | exit(0); |
| 541 | } else if (pid > 0) { |
| 542 | break; |
| 543 | } |
| 544 | return false; |
| 545 | default: |
| 546 | return false; |
| 547 | } |
| 548 | |
| 549 | msg = &pktbuf->msg; |
| 550 | cmddata = EAD_ENC_DATA(msg, cmd_data); |
| 551 | |
| 552 | if (stream) { |
| 553 | int nfds, bytes; |
| 554 | |
| 555 | /* send keepalive packets every 200 ms so that the client doesn't timeout */ |
| 556 | gettimeofday(&to, NULL); |
| 557 | memcpy(&tn, &to, sizeof(tn)); |
| 558 | tv.tv_usec = PCAP_TIMEOUT * 1000; |
| 559 | tv.tv_sec = 0; |
| 560 | do { |
| 561 | cmddata->done = 0; |
| 562 | FD_SET(pfd[0], &fds); |
| 563 | nfds = select(pfd[0] + 1, &fds, NULL, NULL, &tv); |
| 564 | bytes = 0; |
| 565 | if (nfds > 0) { |
| 566 | bytes = read(pfd[0], cmddata->data, 1024); |
| 567 | if (bytes < 0) |
| 568 | bytes = 0; |
| 569 | } |
| 570 | if (!bytes && !child_pending) |
| 571 | break; |
| 572 | DEBUG(3, "Sending %d bytes of console data, type=%d, timeout=%d\n", bytes, ntohl(msg->type), timeout); |
| 573 | ead_encrypt_message(msg, sizeof(struct ead_msg_cmd_data) + bytes); |
| 574 | ead_send_packet_clone(pkt); |
| 575 | gettimeofday(&tn, NULL); |
| 576 | } while (tn.tv_sec < to.tv_sec + timeout); |
| 577 | if (child_pending) { |
| 578 | kill(pid, SIGKILL); |
| 579 | return false; |
| 580 | } |
| 581 | } |
| 582 | cmddata->done = 1; |
| 583 | ead_encrypt_message(msg, sizeof(struct ead_msg_cmd_data)); |
| 584 | |
| 585 | return true; |
| 586 | } |
| 587 | |
| 588 | |
| 589 | |
| 590 | static void |
| 591 | parse_message(struct ead_packet *pkt, int len) |
| 592 | { |
| 593 | bool (*handler)(struct ead_packet *pkt, int len, int *nstate); |
| 594 | int min_len = sizeof(struct ead_packet); |
| 595 | int nstate = state; |
| 596 | int type = ntohl(pkt->msg.type); |
| 597 | |
| 598 | if ((type >= EAD_TYPE_GET_PRIME) && |
| 599 | (state != type)) |
| 600 | return; |
| 601 | |
| 602 | if ((type != EAD_TYPE_PING) && |
| 603 | ((ntohs(pkt->msg.sid) & EAD_INSTANCE_MASK) >> |
| 604 | EAD_INSTANCE_SHIFT) != instance->id) |
| 605 | return; |
| 606 | |
| 607 | switch(type) { |
| 608 | case EAD_TYPE_PING: |
| 609 | handler = handle_ping; |
| 610 | break; |
| 611 | case EAD_TYPE_SET_USERNAME: |
| 612 | handler = handle_set_username; |
| 613 | min_len += sizeof(struct ead_msg_user); |
| 614 | break; |
| 615 | case EAD_TYPE_GET_PRIME: |
| 616 | handler = handle_get_prime; |
| 617 | break; |
| 618 | case EAD_TYPE_SEND_A: |
| 619 | handler = handle_send_a; |
| 620 | min_len += sizeof(struct ead_msg_number); |
| 621 | break; |
| 622 | case EAD_TYPE_SEND_AUTH: |
| 623 | handler = handle_send_auth; |
| 624 | min_len += sizeof(struct ead_msg_auth); |
| 625 | break; |
| 626 | case EAD_TYPE_SEND_CMD: |
| 627 | handler = handle_send_cmd; |
| 628 | min_len += sizeof(struct ead_msg_cmd) + sizeof(struct ead_msg_encrypted); |
| 629 | break; |
| 630 | default: |
| 631 | return; |
| 632 | } |
| 633 | |
| 634 | if (len < min_len) { |
| 635 | DEBUG(2, "discarding packet: message too small\n"); |
| 636 | return; |
| 637 | } |
| 638 | |
| 639 | pktbuf->msg.magic = htonl(EAD_MAGIC); |
| 640 | pktbuf->msg.type = htonl(type + 1); |
| 641 | pktbuf->msg.nid = htons(nid); |
| 642 | pktbuf->msg.sid = pkt->msg.sid; |
| 643 | pktbuf->msg.len = 0; |
| 644 | |
| 645 | if (handler(pkt, len, &nstate)) { |
| 646 | DEBUG(2, "sending response to packet type %d: %d\n", type + 1, ntohl(pktbuf->msg.len)); |
| 647 | /* format response packet */ |
| 648 | ead_send_packet_clone(pkt); |
| 649 | } |
| 650 | set_state(nstate); |
| 651 | } |
| 652 | |
| 653 | static void |
| 654 | handle_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes) |
| 655 | { |
| 656 | struct ead_packet *pkt = (struct ead_packet *) bytes; |
| 657 | |
| 658 | if (h->len < sizeof(struct ead_packet)) |
| 659 | return; |
| 660 | |
| 661 | if (pkt->eh.ether_type != htons(ETHERTYPE_IP)) |
| 662 | return; |
| 663 | |
| 664 | if (memcmp(pkt->eh.ether_dhost, "\xff\xff\xff\xff\xff\xff", 6) != 0) |
| 665 | return; |
| 666 | |
| 667 | if (pkt->proto != UIP_PROTO_UDP) |
| 668 | return; |
| 669 | |
| 670 | if (pkt->destport != htons(EAD_PORT)) |
| 671 | return; |
| 672 | |
| 673 | if (pkt->msg.magic != htonl(EAD_MAGIC)) |
| 674 | return; |
| 675 | |
| 676 | if (h->len < sizeof(struct ead_packet) + ntohl(pkt->msg.len)) |
| 677 | return; |
| 678 | |
| 679 | if ((pkt->msg.nid != 0xffff) && |
| 680 | (pkt->msg.nid != htons(nid))) |
| 681 | return; |
| 682 | |
| 683 | parse_message(pkt, h->len); |
| 684 | } |
| 685 | |
| 686 | static void |
| 687 | ead_pcap_reopen(bool first) |
| 688 | { |
| 689 | static char errbuf[PCAP_ERRBUF_SIZE] = ""; |
| 690 | |
| 691 | if (pcap_fp_rx && (pcap_fp_rx != pcap_fp)) |
| 692 | pcap_close(pcap_fp_rx); |
| 693 | |
| 694 | if (pcap_fp) |
| 695 | pcap_close(pcap_fp); |
| 696 | |
| 697 | pcap_fp_rx = NULL; |
| 698 | do { |
| 699 | #ifdef linux |
| 700 | if (instance->bridge[0]) { |
| 701 | pcap_fp_rx = ead_open_pcap(instance->bridge, errbuf, 1); |
| 702 | pcap_fp = ead_open_pcap(instance->ifname, errbuf, 0); |
| 703 | } else |
| 704 | #endif |
| 705 | { |
| 706 | pcap_fp = ead_open_pcap(instance->ifname, errbuf, 1); |
| 707 | } |
| 708 | |
| 709 | if (!pcap_fp_rx) |
| 710 | pcap_fp_rx = pcap_fp; |
| 711 | if (first && !pcap_fp) { |
| 712 | DEBUG(1, "WARNING: unable to open interface '%s'\n", instance->ifname); |
| 713 | first = false; |
| 714 | } |
| 715 | if (!pcap_fp) |
| 716 | sleep(1); |
| 717 | } while (!pcap_fp); |
| 718 | pcap_setfilter(pcap_fp_rx, &pktfilter); |
| 719 | } |
| 720 | |
| 721 | |
| 722 | static void |
| 723 | ead_pktloop(void) |
| 724 | { |
| 725 | while (1) { |
| 726 | if (pcap_dispatch(pcap_fp_rx, 1, handle_packet, NULL) < 0) { |
| 727 | ead_pcap_reopen(false); |
| 728 | continue; |
| 729 | } |
| 730 | } |
| 731 | } |
| 732 | |
| 733 | |
| 734 | static int |
| 735 | usage(const char *prog) |
| 736 | { |
| 737 | fprintf(stderr, "Usage: %s [<options>]\n" |
| 738 | "Options:\n" |
| 739 | "\t-B Run in background mode\n" |
| 740 | "\t-d <device> Set the device to listen on\n" |
| 741 | "\t-D <name> Set the name of the device visible to clients\n" |
| 742 | "\t-p <file> Set the password file for authenticating\n" |
| 743 | "\t-P <file> Write a pidfile\n" |
| 744 | "\n", prog); |
| 745 | return -1; |
| 746 | } |
| 747 | |
| 748 | static void |
| 749 | server_handle_sigchld(int sig) |
| 750 | { |
| 751 | struct ead_instance *in; |
| 752 | struct list_head *p; |
| 753 | int pid = 0; |
| 754 | wait(&pid); |
| 755 | |
| 756 | list_for_each(p, &instances) { |
| 757 | in = list_entry(p, struct ead_instance, list); |
| 758 | if (pid != in->pid) |
| 759 | continue; |
| 760 | |
| 761 | in->pid = 0; |
| 762 | break; |
| 763 | } |
| 764 | } |
| 765 | |
| 766 | static void |
| 767 | instance_handle_sigchld(int sig) |
| 768 | { |
| 769 | int pid = 0; |
| 770 | wait(&pid); |
| 771 | child_pending = false; |
| 772 | } |
| 773 | |
| 774 | static void |
| 775 | start_server(struct ead_instance *i) |
| 776 | { |
| 777 | if (!nonfork) { |
| 778 | i->pid = fork(); |
| 779 | if (i->pid != 0) { |
| 780 | if (i->pid < 0) |
| 781 | i->pid = 0; |
| 782 | return; |
| 783 | } |
| 784 | } |
| 785 | |
| 786 | instance = i; |
| 787 | signal(SIGCHLD, instance_handle_sigchld); |
| 788 | ead_pcap_reopen(true); |
| 789 | ead_pktloop(); |
| 790 | pcap_close(pcap_fp); |
| 791 | if (pcap_fp_rx != pcap_fp) |
| 792 | pcap_close(pcap_fp_rx); |
| 793 | |
| 794 | exit(0); |
| 795 | } |
| 796 | |
| 797 | |
| 798 | static void |
| 799 | start_servers(bool restart) |
| 800 | { |
| 801 | struct ead_instance *in; |
| 802 | struct list_head *p; |
| 803 | |
| 804 | list_for_each(p, &instances) { |
| 805 | in = list_entry(p, struct ead_instance, list); |
| 806 | if (in->pid > 0) |
| 807 | continue; |
| 808 | |
| 809 | sleep(1); |
| 810 | start_server(in); |
| 811 | } |
| 812 | } |
| 813 | |
| 814 | static void |
| 815 | stop_server(struct ead_instance *in, bool do_free) |
| 816 | { |
| 817 | if (in->pid > 0) |
| 818 | kill(in->pid, SIGKILL); |
| 819 | in->pid = 0; |
| 820 | if (do_free) { |
| 821 | list_del(&in->list); |
| 822 | free(in); |
| 823 | } |
| 824 | } |
| 825 | |
| 826 | static void |
| 827 | server_handle_sigint(int sig) |
| 828 | { |
| 829 | struct ead_instance *in; |
| 830 | struct list_head *p, *tmp; |
| 831 | |
| 832 | list_for_each_safe(p, tmp, &instances) { |
| 833 | in = list_entry(p, struct ead_instance, list); |
| 834 | stop_server(in, true); |
| 835 | } |
| 836 | exit(1); |
| 837 | } |
| 838 | |
| 839 | #ifdef linux |
| 840 | static int |
| 841 | check_bridge_port(const char *br, const char *port, void *arg) |
| 842 | { |
| 843 | struct ead_instance *in; |
| 844 | struct list_head *p, *tmp; |
| 845 | |
| 846 | list_for_each(p, &instances) { |
| 847 | in = list_entry(p, struct ead_instance, list); |
| 848 | |
| 849 | if (strcmp(in->ifname, port) != 0) |
| 850 | continue; |
| 851 | |
| 852 | in->br_check = true; |
| 853 | if (strcmp(in->bridge, br) == 0) |
| 854 | break; |
| 855 | |
| 856 | strncpy(in->bridge, br, sizeof(in->bridge)); |
| 857 | DEBUG(2, "assigning port %s to bridge %s\n", in->ifname, in->bridge); |
| 858 | stop_server(in, false); |
| 859 | } |
| 860 | return 0; |
| 861 | } |
| 862 | |
| 863 | static int |
| 864 | check_bridge(const char *name, void *arg) |
| 865 | { |
| 866 | br_foreach_port(name, check_bridge_port, arg); |
| 867 | return 0; |
| 868 | } |
| 869 | #endif |
| 870 | |
| 871 | static void |
| 872 | check_all_interfaces(void) |
| 873 | { |
| 874 | #ifdef linux |
| 875 | struct ead_instance *in; |
| 876 | struct list_head *p, *tmp; |
| 877 | |
| 878 | br_foreach_bridge(check_bridge, NULL); |
| 879 | |
| 880 | /* look for interfaces that are no longer part of a bridge */ |
| 881 | list_for_each(p, &instances) { |
| 882 | in = list_entry(p, struct ead_instance, list); |
| 883 | |
| 884 | if (in->br_check) { |
| 885 | in->br_check = false; |
| 886 | } else if (in->bridge[0]) { |
| 887 | DEBUG(2, "removing port %s from bridge %s\n", in->ifname, in->bridge); |
| 888 | in->bridge[0] = 0; |
| 889 | stop_server(in, false); |
| 890 | } |
| 891 | } |
| 892 | #endif |
| 893 | } |
| 894 | |
| 895 | |
| 896 | int main(int argc, char **argv) |
| 897 | { |
| 898 | struct ead_instance *in; |
| 899 | struct timeval tv; |
| 900 | const char *pidfile = NULL; |
| 901 | bool background = false; |
| 902 | int n_iface = 0; |
| 903 | int fd, ch; |
| 904 | |
| 905 | if (argc == 1) |
| 906 | return usage(argv[0]); |
| 907 | |
| 908 | INIT_LIST_HEAD(&instances); |
| 909 | while ((ch = getopt(argc, argv, "Bd:D:fhp:P:")) != -1) { |
| 910 | switch(ch) { |
| 911 | case 'B': |
| 912 | background = true; |
| 913 | break; |
| 914 | case 'f': |
| 915 | nonfork = true; |
| 916 | break; |
| 917 | case 'h': |
| 918 | return usage(argv[0]); |
| 919 | case 'd': |
| 920 | in = malloc(sizeof(struct ead_instance)); |
| 921 | memset(in, 0, sizeof(struct ead_instance)); |
| 922 | INIT_LIST_HEAD(&in->list); |
| 923 | strncpy(in->ifname, optarg, sizeof(in->ifname) - 1); |
| 924 | list_add(&in->list, &instances); |
| 925 | in->id = n_iface++; |
| 926 | break; |
| 927 | case 'D': |
| 928 | dev_name = optarg; |
| 929 | break; |
| 930 | case 'p': |
| 931 | passwd_file = optarg; |
| 932 | break; |
| 933 | case 'P': |
| 934 | pidfile = optarg; |
| 935 | break; |
| 936 | } |
| 937 | } |
| 938 | signal(SIGCHLD, server_handle_sigchld); |
| 939 | signal(SIGINT, server_handle_sigint); |
| 940 | signal(SIGTERM, server_handle_sigint); |
| 941 | signal(SIGKILL, server_handle_sigint); |
| 942 | |
| 943 | if (!n_iface) { |
| 944 | fprintf(stderr, "Error: ead needs at least one interface\n"); |
| 945 | return -1; |
| 946 | } |
| 947 | |
| 948 | if (background) { |
| 949 | if (fork() > 0) |
| 950 | exit(0); |
| 951 | |
| 952 | fd = open("/dev/null", O_RDWR); |
| 953 | dup2(fd, 0); |
| 954 | dup2(fd, 1); |
| 955 | dup2(fd, 2); |
| 956 | } |
| 957 | |
| 958 | if (pidfile) { |
| 959 | char pid[8]; |
| 960 | int len; |
| 961 | |
| 962 | unlink(pidfile); |
| 963 | fd = open(pidfile, O_CREAT|O_WRONLY|O_EXCL, 0644); |
| 964 | if (fd > 0) { |
| 965 | len = sprintf(pid, "%d\n", getpid()); |
| 966 | write(fd, pid, len); |
| 967 | close(fd); |
| 968 | } |
| 969 | } |
| 970 | |
| 971 | /* randomize the mac address */ |
| 972 | get_random_bytes(ethmac + 3, 3); |
| 973 | nid = *(((u16_t *) ethmac) + 2); |
| 974 | |
| 975 | start_servers(false); |
| 976 | #ifdef linux |
| 977 | br_init(); |
| 978 | #endif |
| 979 | tv.tv_sec = 1; |
| 980 | tv.tv_usec = 0; |
| 981 | while (1) { |
| 982 | check_all_interfaces(); |
| 983 | start_servers(true); |
| 984 | sleep(1); |
| 985 | } |
| 986 | #ifdef linux |
| 987 | br_shutdown(); |
| 988 | #endif |
| 989 | |
| 990 | return 0; |
| 991 | } |
| 992 | |