sshconnect.c revision 69591
1/* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * Code to connect to a remote host, and to perform the client side of the 6 * login (authentication) dialog. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 */ 14 15#include "includes.h" 16RCSID("$OpenBSD: sshconnect.c,v 1.79 2000/09/17 15:52:51 markus Exp $"); 17RCSID("$FreeBSD: head/crypto/openssh/sshconnect.c 69591 2000-12-05 02:55:12Z green $"); 18 19#include <openssl/bn.h> 20#include <openssl/dsa.h> 21#include <openssl/rsa.h> 22 23#include "xmalloc.h" 24#include "rsa.h" 25#include "ssh.h" 26#include "buffer.h" 27#include "packet.h" 28#include "uidswap.h" 29#include "compat.h" 30#include "readconf.h" 31#include "key.h" 32#include "sshconnect.h" 33#include "hostfile.h" 34 35char *client_version_string = NULL; 36char *server_version_string = NULL; 37 38extern Options options; 39extern char *__progname; 40 41/* 42 * Connect to the given ssh server using a proxy command. 43 */ 44int 45ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, 46 const char *proxy_command) 47{ 48 Buffer command; 49 const char *cp; 50 char *command_string; 51 int pin[2], pout[2]; 52 pid_t pid; 53 char strport[NI_MAXSERV]; 54 55 /* Convert the port number into a string. */ 56 snprintf(strport, sizeof strport, "%hu", port); 57 58 /* Build the final command string in the buffer by making the 59 appropriate substitutions to the given proxy command. */ 60 buffer_init(&command); 61 for (cp = proxy_command; *cp; cp++) { 62 if (cp[0] == '%' && cp[1] == '%') { 63 buffer_append(&command, "%", 1); 64 cp++; 65 continue; 66 } 67 if (cp[0] == '%' && cp[1] == 'h') { 68 buffer_append(&command, host, strlen(host)); 69 cp++; 70 continue; 71 } 72 if (cp[0] == '%' && cp[1] == 'p') { 73 buffer_append(&command, strport, strlen(strport)); 74 cp++; 75 continue; 76 } 77 buffer_append(&command, cp, 1); 78 } 79 buffer_append(&command, "\0", 1); 80 81 /* Get the final command string. */ 82 command_string = buffer_ptr(&command); 83 84 /* Create pipes for communicating with the proxy. */ 85 if (pipe(pin) < 0 || pipe(pout) < 0) 86 fatal("Could not create pipes to communicate with the proxy: %.100s", 87 strerror(errno)); 88 89 debug("Executing proxy command: %.500s", command_string); 90 91 /* Fork and execute the proxy command. */ 92 if ((pid = fork()) == 0) { 93 char *argv[10]; 94 95 /* Child. Permanently give up superuser privileges. */ 96 permanently_set_uid(original_real_uid); 97 98 /* Redirect stdin and stdout. */ 99 close(pin[1]); 100 if (pin[0] != 0) { 101 if (dup2(pin[0], 0) < 0) 102 perror("dup2 stdin"); 103 close(pin[0]); 104 } 105 close(pout[0]); 106 if (dup2(pout[1], 1) < 0) 107 perror("dup2 stdout"); 108 /* Cannot be 1 because pin allocated two descriptors. */ 109 close(pout[1]); 110 111 /* Stderr is left as it is so that error messages get 112 printed on the user's terminal. */ 113 argv[0] = "/bin/sh"; 114 argv[1] = "-c"; 115 argv[2] = command_string; 116 argv[3] = NULL; 117 118 /* Execute the proxy command. Note that we gave up any 119 extra privileges above. */ 120 execv("/bin/sh", argv); 121 perror("/bin/sh"); 122 exit(1); 123 } 124 /* Parent. */ 125 if (pid < 0) 126 fatal("fork failed: %.100s", strerror(errno)); 127 128 /* Close child side of the descriptors. */ 129 close(pin[0]); 130 close(pout[1]); 131 132 /* Free the command name. */ 133 buffer_free(&command); 134 135 /* Set the connection file descriptors. */ 136 packet_set_connection(pout[0], pin[1]); 137 138 return 1; 139} 140 141/* 142 * Creates a (possibly privileged) socket for use as the ssh connection. 143 */ 144int 145ssh_create_socket(uid_t original_real_uid, int privileged, int family) 146{ 147 int sock; 148 149 /* 150 * If we are running as root and want to connect to a privileged 151 * port, bind our own socket to a privileged port. 152 */ 153 if (privileged) { 154 int p = IPPORT_RESERVED - 1; 155 sock = rresvport_af(&p, family); 156 if (sock < 0) 157 error("rresvport: af=%d %.100s", family, strerror(errno)); 158 else 159 debug("Allocated local port %d.", p); 160 } else { 161 /* 162 * Just create an ordinary socket on arbitrary port. We use 163 * the user's uid to create the socket. 164 */ 165 temporarily_use_uid(original_real_uid); 166 sock = socket(family, SOCK_STREAM, 0); 167 if (sock < 0) 168 error("socket: %.100s", strerror(errno)); 169 restore_uid(); 170 } 171 return sock; 172} 173 174/* 175 * Opens a TCP/IP connection to the remote server on the given host. 176 * The canonical host name used to connect will be returned in *host. 177 * The address of the remote host will be returned in hostaddr. 178 * If port is 0, the default port will be used. If anonymous is zero, 179 * a privileged port will be allocated to make the connection. 180 * This requires super-user privileges if anonymous is false. 181 * Connection_attempts specifies the maximum number of tries (one per 182 * second). If proxy_command is non-NULL, it specifies the command (with %h 183 * and %p substituted for host and port, respectively) to use to contact 184 * the daemon. 185 */ 186int 187ssh_connect(char **host, struct sockaddr_storage * hostaddr, 188 u_short port, int connection_attempts, 189 int anonymous, uid_t original_real_uid, 190 const char *proxy_command) 191{ 192 int sock = -1, attempt; 193 struct servent *sp; 194 struct addrinfo hints, *ai, *aitop; 195 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 196 int gaierr; 197 struct linger linger; 198 199 debug("ssh_connect: getuid %u geteuid %u anon %d", 200 (u_int) getuid(), (u_int) geteuid(), anonymous); 201 202 /* Get default port if port has not been set. */ 203 if (port == 0) { 204 sp = getservbyname(SSH_SERVICE_NAME, "tcp"); 205 if (sp) 206 port = ntohs(sp->s_port); 207 else 208 port = SSH_DEFAULT_PORT; 209 } 210 /* If a proxy command is given, connect using it. */ 211 if (proxy_command != NULL) 212 return ssh_proxy_connect(*host, port, original_real_uid, proxy_command); 213 214 /* No proxy command. */ 215 216 memset(&hints, 0, sizeof(hints)); 217 hints.ai_family = IPv4or6; 218 hints.ai_socktype = SOCK_STREAM; 219 hints.ai_flags = AI_CANONNAME; 220 snprintf(strport, sizeof strport, "%d", port); 221 if ((gaierr = getaddrinfo(*host, strport, &hints, &aitop)) != 0) 222 fatal("%s: %.100s: %s", __progname, *host, 223 gai_strerror(gaierr)); 224 225 /* 226 * Try to connect several times. On some machines, the first time 227 * will sometimes fail. In general socket code appears to behave 228 * quite magically on many machines. 229 */ 230 for (attempt = 0; attempt < connection_attempts; attempt++) { 231 if (attempt > 0) 232 debug("Trying again..."); 233 234 /* Loop through addresses for this host, and try each one in 235 sequence until the connection succeeds. */ 236 for (ai = aitop; ai; ai = ai->ai_next) { 237 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 238 continue; 239 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 240 ntop, sizeof(ntop), strport, sizeof(strport), 241 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 242 error("ssh_connect: getnameinfo failed"); 243 continue; 244 } 245 debug("Connecting to %.200s [%.100s] port %s.", 246 ai->ai_canonname, ntop, strport); 247 248 /* Create a socket for connecting. */ 249 sock = ssh_create_socket(original_real_uid, 250 !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, 251 ai->ai_family); 252 if (sock < 0) 253 continue; 254 255 /* Connect to the host. We use the user's uid in the 256 * hope that it will help with tcp_wrappers showing 257 * the remote uid as root. 258 */ 259 temporarily_use_uid(original_real_uid); 260 if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { 261 /* Successful connection. */ 262 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 263 restore_uid(); 264 break; 265 } else { 266 debug("connect: %.100s", strerror(errno)); 267 restore_uid(); 268 /* 269 * Close the failed socket; there appear to 270 * be some problems when reusing a socket for 271 * which connect() has already returned an 272 * error. 273 */ 274 shutdown(sock, SHUT_RDWR); 275 close(sock); 276 } 277 } 278 if (ai) { 279 if (ai->ai_canonname != NULL) 280 *host = xstrdup(ai->ai_canonname); 281 break; /* Successful connection. */ 282 } 283 284 /* Sleep a moment before retrying. */ 285 sleep(1); 286 } 287 288 freeaddrinfo(aitop); 289 290 /* Return failure if we didn't get a successful connection. */ 291 if (attempt >= connection_attempts) 292 return 0; 293 294 debug("Connection established."); 295 296 /* 297 * Set socket options. We would like the socket to disappear as soon 298 * as it has been closed for whatever reason. 299 */ 300 /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ 301 linger.l_onoff = 1; 302 linger.l_linger = 5; 303 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); 304 305 /* Set the connection. */ 306 packet_set_connection(sock, sock); 307 308 return 1; 309} 310 311/* 312 * Waits for the server identification string, and sends our own 313 * identification string. 314 */ 315void 316ssh_exchange_identification() 317{ 318 char buf[256], remote_version[256]; /* must be same size! */ 319 int remote_major, remote_minor, i, mismatch; 320 int connection_in = packet_get_connection_in(); 321 int connection_out = packet_get_connection_out(); 322 323 /* Read other side\'s version identification. */ 324 for (;;) { 325 for (i = 0; i < sizeof(buf) - 1; i++) { 326 int len = atomicio(read, connection_in, &buf[i], 1); 327 if (len < 0) 328 fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); 329 if (len != 1) 330 fatal("ssh_exchange_identification: Connection closed by remote host"); 331 if (buf[i] == '\r') { 332 buf[i] = '\n'; 333 buf[i + 1] = 0; 334 continue; /**XXX wait for \n */ 335 } 336 if (buf[i] == '\n') { 337 buf[i + 1] = 0; 338 break; 339 } 340 } 341 buf[sizeof(buf) - 1] = 0; 342 if (strncmp(buf, "SSH-", 4) == 0) 343 break; 344 debug("ssh_exchange_identification: %s", buf); 345 } 346 server_version_string = xstrdup(buf); 347 348 /* 349 * Check that the versions match. In future this might accept 350 * several versions and set appropriate flags to handle them. 351 */ 352 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 353 &remote_major, &remote_minor, remote_version) != 3) 354 fatal("Bad remote protocol version identification: '%.100s'", buf); 355 debug("Remote protocol version %d.%d, remote software version %.100s", 356 remote_major, remote_minor, remote_version); 357 358 compat_datafellows(remote_version); 359 mismatch = 0; 360 361 switch(remote_major) { 362 case 1: 363 if (remote_minor == 99 && 364 (options.protocol & SSH_PROTO_2) && 365 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 366 enable_compat20(); 367 break; 368 } 369 if (!(options.protocol & SSH_PROTO_1)) { 370 mismatch = 1; 371 break; 372 } 373 if (remote_minor < 3) { 374 fatal("Remote machine has too old SSH software version."); 375 } else if (remote_minor == 3) { 376 /* We speak 1.3, too. */ 377 enable_compat13(); 378 if (options.forward_agent) { 379 log("Agent forwarding disabled for protocol 1.3"); 380 options.forward_agent = 0; 381 } 382 } 383 break; 384 case 2: 385 if (options.protocol & SSH_PROTO_2) { 386 enable_compat20(); 387 break; 388 } 389 /* FALLTHROUGH */ 390 default: 391 mismatch = 1; 392 break; 393 } 394 if (mismatch) 395 fatal("Protocol major versions differ: %d vs. %d", 396 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 397 remote_major); 398 if (compat20) 399 packet_set_ssh2_format(); 400 /* Send our own protocol version identification. */ 401 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", 402 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 403 compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1, 404 SSH_VERSION); 405 if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) 406 fatal("write: %.100s", strerror(errno)); 407 client_version_string = xstrdup(buf); 408 chop(client_version_string); 409 chop(server_version_string); 410 debug("Local version string %.100s", client_version_string); 411} 412 413int 414read_yes_or_no(const char *prompt, int defval) 415{ 416 char buf[1024]; 417 FILE *f; 418 int retval = -1; 419 420 if (isatty(0)) 421 f = stdin; 422 else 423 f = fopen("/dev/tty", "rw"); 424 425 if (f == NULL) 426 return 0; 427 428 fflush(stdout); 429 430 while (1) { 431 fprintf(stderr, "%s", prompt); 432 if (fgets(buf, sizeof(buf), f) == NULL) { 433 /* Print a newline (the prompt probably didn\'t have one). */ 434 fprintf(stderr, "\n"); 435 strlcpy(buf, "no", sizeof buf); 436 } 437 /* Remove newline from response. */ 438 if (strchr(buf, '\n')) 439 *strchr(buf, '\n') = 0; 440 441 if (buf[0] == 0) 442 retval = defval; 443 if (strcmp(buf, "yes") == 0) 444 retval = 1; 445 else if (strcmp(buf, "no") == 0) 446 retval = 0; 447 else 448 fprintf(stderr, "Please type 'yes' or 'no'.\n"); 449 450 if (retval != -1) { 451 if (f != stdin) 452 fclose(f); 453 return retval; 454 } 455 } 456} 457 458/* 459 * check whether the supplied host key is valid, return only if ok. 460 */ 461 462void 463check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, 464 const char *user_hostfile, const char *system_hostfile) 465{ 466 Key *file_key; 467 char *type = key_type(host_key); 468 char *ip = NULL; 469 char hostline[1000], *hostp; 470 HostStatus host_status; 471 HostStatus ip_status; 472 int local = 0, host_ip_differ = 0; 473 char ntop[NI_MAXHOST]; 474 475 /* 476 * Force accepting of the host key for loopback/localhost. The 477 * problem is that if the home directory is NFS-mounted to multiple 478 * machines, localhost will refer to a different machine in each of 479 * them, and the user will get bogus HOST_CHANGED warnings. This 480 * essentially disables host authentication for localhost; however, 481 * this is probably not a real problem. 482 */ 483 /** hostaddr == 0! */ 484 switch (hostaddr->sa_family) { 485 case AF_INET: 486 local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 487 break; 488 case AF_INET6: 489 local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 490 break; 491 default: 492 local = 0; 493 break; 494 } 495 if (local) { 496 debug("Forcing accepting of host key for loopback/localhost."); 497 return; 498 } 499 500 /* 501 * Turn off check_host_ip for proxy connects, since 502 * we don't have the remote ip-address 503 */ 504 if (options.proxy_command != NULL && options.check_host_ip) 505 options.check_host_ip = 0; 506 507 if (options.check_host_ip) { 508 if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop), 509 NULL, 0, NI_NUMERICHOST) != 0) 510 fatal("check_host_key: getnameinfo failed"); 511 ip = xstrdup(ntop); 512 } 513 514 /* 515 * Store the host key from the known host file in here so that we can 516 * compare it with the key for the IP address. 517 */ 518 file_key = key_new(host_key->type); 519 520 /* 521 * Check if the host key is present in the user\'s list of known 522 * hosts or in the systemwide list. 523 */ 524 host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key); 525 if (host_status == HOST_NEW) 526 host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key); 527 /* 528 * Also perform check for the ip address, skip the check if we are 529 * localhost or the hostname was an ip address to begin with 530 */ 531 if (options.check_host_ip && !local && strcmp(host, ip)) { 532 Key *ip_key = key_new(host_key->type); 533 ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key); 534 535 if (ip_status == HOST_NEW) 536 ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key); 537 if (host_status == HOST_CHANGED && 538 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) 539 host_ip_differ = 1; 540 541 key_free(ip_key); 542 } else 543 ip_status = host_status; 544 545 key_free(file_key); 546 547 switch (host_status) { 548 case HOST_OK: 549 /* The host is known and the key matches. */ 550 debug("Host '%.200s' is known and matches the %s host key.", 551 host, type); 552 if (options.check_host_ip) { 553 if (ip_status == HOST_NEW) { 554 if (!add_host_to_hostfile(user_hostfile, ip, host_key)) 555 log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).", 556 type, ip, user_hostfile); 557 else 558 log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.", 559 type, ip); 560 } else if (ip_status != HOST_OK) 561 log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'", 562 type, host, ip); 563 } 564 break; 565 case HOST_NEW: 566 /* The host is new. */ 567 if (options.strict_host_key_checking == 1) { 568 /* User has requested strict host key checking. We will not add the host key 569 automatically. The only alternative left is to abort. */ 570 fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host); 571 } else if (options.strict_host_key_checking == 2) { 572 /* The default */ 573 char prompt[1024]; 574 char *fp = key_fingerprint(host_key); 575 snprintf(prompt, sizeof(prompt), 576 "The authenticity of host '%.200s' can't be established.\n" 577 "%s key fingerprint is %s.\n" 578 "Are you sure you want to continue connecting (yes/no)? ", 579 host, type, fp); 580 if (!read_yes_or_no(prompt, -1)) 581 fatal("Aborted by user!\n"); 582 } 583 if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) { 584 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 585 hostp = hostline; 586 } else 587 hostp = host; 588 589 /* If not in strict mode, add the key automatically to the local known_hosts file. */ 590 if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) 591 log("Failed to add the host to the list of known hosts (%.500s).", 592 user_hostfile); 593 else 594 log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.", 595 hostp, type); 596 break; 597 case HOST_CHANGED: 598 if (options.check_host_ip && host_ip_differ) { 599 char *msg; 600 if (ip_status == HOST_NEW) 601 msg = "is unknown"; 602 else if (ip_status == HOST_OK) 603 msg = "is unchanged"; 604 else 605 msg = "has a different value"; 606 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 607 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 608 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 609 error("The %s host key for %s has changed,", type, host); 610 error("and the key for the according IP address %s", ip); 611 error("%s. This could either mean that", msg); 612 error("DNS SPOOFING is happening or the IP address for the host"); 613 error("and its host key have changed at the same time"); 614 } 615 /* The host key has changed. */ 616 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 617 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 618 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 619 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 620 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 621 error("It is also possible that the %s host key has just been changed.", type); 622 error("Please contact your system administrator."); 623 error("Add correct host key in %.100s to get rid of this message.", 624 user_hostfile); 625 626 /* 627 * If strict host key checking is in use, the user will have 628 * to edit the key manually and we can only abort. 629 */ 630 if (options.strict_host_key_checking) 631 fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host); 632 633 /* 634 * If strict host key checking has not been requested, allow 635 * the connection but without password authentication or 636 * agent forwarding. 637 */ 638 if (options.password_authentication) { 639 error("Password authentication is disabled to avoid trojan horses."); 640 options.password_authentication = 0; 641 } 642 if (options.forward_agent) { 643 error("Agent forwarding is disabled to avoid trojan horses."); 644 options.forward_agent = 0; 645 } 646 /* 647 * XXX Should permit the user to change to use the new id. 648 * This could be done by converting the host key to an 649 * identifying sentence, tell that the host identifies itself 650 * by that sentence, and ask the user if he/she whishes to 651 * accept the authentication. 652 */ 653 break; 654 } 655 if (options.check_host_ip) 656 xfree(ip); 657} 658 659#ifdef KRB5 660int 661try_krb5_authentication(krb5_context *context, krb5_auth_context *auth_context) 662{ 663 krb5_error_code problem; 664 const char *tkfile; 665 struct stat buf; 666 krb5_ccache ccache = NULL; 667 krb5_creds req_creds; 668 krb5_creds *new_creds = NULL; 669 const char *remotehost; 670 krb5_data ap; 671 int type, payload_len; 672 krb5_ap_rep_enc_part *reply = NULL; 673 int ret; 674 675 memset(&ap, 0, sizeof(ap)); 676 677 problem = krb5_init_context(context); 678 if (problem) { 679 ret = 0; 680 goto out; 681 } 682 683 tkfile = krb5_cc_default_name(*context); 684 if (strncmp(tkfile, "FILE:", 5) == 0) 685 tkfile += 5; 686 687 if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { 688 debug("Kerberos V5: could not get default ccache (permission denied)."); 689 ret = 0; 690 goto out; 691 } 692 693 problem = krb5_cc_default(*context, &ccache); 694 if (problem) { 695 ret = 0; 696 goto out; 697 } 698 699 memset(&req_creds, 0, sizeof(req_creds)); 700 701 remotehost = get_canonical_hostname(); 702 703 problem = krb5_sname_to_principal(*context, remotehost, 704 "host", KRB5_NT_SRV_HST, 705 &req_creds.server); 706 if (problem) { 707 ret = 0; 708 goto out; 709 710 } 711 712 problem = krb5_cc_get_principal(*context, ccache, &req_creds.client); 713 if (problem) { 714 ret = 0; 715 goto out; 716 } 717 718 /* creds.session.keytype=ETYPE_DES_CBC_CRC; */ 719 720 problem = krb5_get_credentials(*context, 0, ccache, &req_creds, &new_creds); 721 if (problem) { 722 ret = 0; 723 goto out; 724 } 725 726 problem = krb5_auth_con_init(*context, auth_context); 727 if (problem) { 728 ret = 0; 729 goto out; 730 } 731 732 /* krb5_auth_con_setflags(ssh_context, auth_context, 733 KRB5_AUTH_CONTEXT_RET_TIME); 734 */ 735 problem = krb5_mk_req_extended(*context, auth_context, 736 AP_OPTS_MUTUAL_REQUIRED /*| AP_OPTS_USE_SUBKEY*/ , 737 NULL, new_creds, &ap); 738 if (problem) { 739 ret = 0; 740 goto out; 741 } 742 743 packet_start(SSH_CMSG_AUTH_KRB5); 744 packet_put_string((char *) ap.data, ap.length); 745 packet_send(); 746 packet_write_wait(); 747 748 xfree(ap.data); 749 ap.length = 0; 750 751 type = packet_read(&payload_len); 752 switch (type) { 753 case SSH_SMSG_FAILURE: 754 /* Should really be SSH_SMSG_AUTH_KRB5_FAILURE */ 755 debug("Kerberos V5 authentication failed."); 756 ret = 0; 757 break; 758 759 case SSH_SMSG_AUTH_KRB5_RESPONSE: 760 /* SSH_SMSG_AUTH_KRB5_SUCCESS */ 761 debug("Kerberos V5 authentication accepted."); 762 763 /* Get server's response. */ 764 ap.data = packet_get_string((unsigned int *) &ap.length); 765 766 packet_integrity_check(payload_len, 4 + ap.length, type); 767 /* XXX je to dobre? */ 768 769 problem = krb5_rd_rep(*context, *auth_context, &ap, &reply); 770 if (problem) { 771 ret = 0; 772 } 773 ret = 1; 774 break; 775 776 default: 777 packet_disconnect("Protocol error on Kerberos V5 response: %d", type); 778 ret = 0; 779 break; 780 781 } 782 783out: 784 if (req_creds.server != NULL) 785 krb5_free_principal(*context, req_creds.server); 786 if (req_creds.client != NULL) 787 krb5_free_principal(*context, req_creds.client); 788 if (new_creds != NULL) 789 krb5_free_creds(*context, new_creds); 790 if (ccache != NULL) 791 krb5_cc_close(*context, ccache); 792 if (reply != NULL) 793 krb5_free_ap_rep_enc_part(*context, reply); 794 if (ap.length > 0) 795 krb5_data_free(&ap); 796 797 return ret; 798 799} 800 801void 802send_krb5_tgt(krb5_context context, krb5_auth_context auth_context) 803{ 804 int fd; 805 int type, payload_len; 806 krb5_error_code problem; 807 krb5_data outbuf; 808 krb5_ccache ccache = NULL; 809 krb5_creds creds; 810 krb5_kdc_flags flags; 811 const char* remotehost = get_canonical_hostname(); 812 813 memset(&creds, 0, sizeof(creds)); 814 memset(&outbuf, 0, sizeof(outbuf)); 815 816 fd = packet_get_connection_in(); 817 problem = krb5_auth_con_setaddrs_from_fd(context, auth_context, &fd); 818 if (problem) { 819 goto out; 820 } 821 822#if 0 823 tkfile = krb5_cc_default_name(context); 824 if (strncmp(tkfile, "FILE:", 5) == 0) 825 tkfile += 5; 826 827 if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { 828 debug("Kerberos V5: could not get default ccache (permission denied)."); 829 goto out; 830 } 831#endif 832 833 problem = krb5_cc_default(context, &ccache); 834 if (problem) { 835 goto out; 836 } 837 838 problem = krb5_cc_get_principal(context, ccache, &creds.client); 839 if (problem) { 840 goto out; 841 } 842 843 problem = krb5_build_principal(context, &creds.server, 844 strlen(creds.client->realm), 845 creds.client->realm, 846 "krbtgt", 847 creds.client->realm, 848 NULL); 849 if (problem) { 850 goto out; 851 } 852 853 creds.times.endtime = 0; 854 855 flags.i = 0; 856 flags.b.forwarded = 1; 857 flags.b.forwardable = krb5_config_get_bool(context, NULL, 858 "libdefaults", "forwardable", NULL); 859 860 problem = krb5_get_forwarded_creds (context, 861 auth_context, 862 ccache, 863 flags.i, 864 remotehost, 865 &creds, 866 &outbuf); 867 if (problem) { 868 goto out; 869 } 870 871 packet_start(SSH_CMSG_HAVE_KRB5_TGT); 872 packet_put_string((char *)outbuf.data, outbuf.length); 873 packet_send(); 874 packet_write_wait(); 875 876 type = packet_read(&payload_len); 877 switch (type) { 878 case SSH_SMSG_SUCCESS: 879 break; 880 case SSH_SMSG_FAILURE: 881 break; 882 default: 883 break; 884 } 885 886out: 887 if (creds.client) 888 krb5_free_principal(context, creds.client); 889 if (creds.server) 890 krb5_free_principal(context, creds.server); 891 if (ccache) 892 krb5_cc_close(context, ccache); 893 if (outbuf.data) 894 xfree(outbuf.data); 895 896 return; 897} 898#endif /* KRB5 */ 899 900/* 901 * Starts a dialog with the server, and authenticates the current user on the 902 * server. This does not need any extra privileges. The basic connection 903 * to the server must already have been established before this is called. 904 * If login fails, this function prints an error and never returns. 905 * This function does not require super-user privileges. 906 */ 907void 908ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, 909 struct sockaddr *hostaddr, uid_t original_real_uid) 910{ 911 struct passwd *pw; 912 char *host, *cp; 913 char *server_user, *local_user; 914 915 /* Get local user name. Use it as server user if no user name was given. */ 916 pw = getpwuid(original_real_uid); 917 if (!pw) 918 fatal("User id %u not found from user database.", original_real_uid); 919 local_user = xstrdup(pw->pw_name); 920 server_user = options.user ? options.user : local_user; 921 922 /* Convert the user-supplied hostname into all lowercase. */ 923 host = xstrdup(orighost); 924 for (cp = host; *cp; cp++) 925 if (isupper(*cp)) 926 *cp = tolower(*cp); 927 928 /* Exchange protocol version identification strings with the server. */ 929 ssh_exchange_identification(); 930 931 /* Put the connection into non-blocking mode. */ 932 packet_set_nonblocking(); 933 934 /* key exchange */ 935 /* authenticate user */ 936 if (compat20) { 937 ssh_kex2(host, hostaddr); 938 ssh_userauth2(server_user, host); 939 } else { 940 ssh_kex(host, hostaddr); 941 ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); 942 } 943} 944