Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.1
1.1 ! deraadt 1: /*
! 2:
! 3: sshconnect.c
! 4:
! 5: Author: Tatu Ylonen <ylo@cs.hut.fi>
! 6:
! 7: Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
! 8: All rights reserved
! 9:
! 10: Created: Sat Mar 18 22:15:47 1995 ylo
! 11:
! 12: Code to connect to a remote host, and to perform the client side of the
! 13: login (authentication) dialog.
! 14:
! 15: */
! 16:
! 17: #include "includes.h"
! 18: RCSID("$Id: sshconnect.c,v 1.19 1999/06/14 14:41:41 bg Exp $");
! 19:
! 20: #include <gmp.h>
! 21: #include "xmalloc.h"
! 22: #include "randoms.h"
! 23: #include "rsa.h"
! 24: #include "ssh.h"
! 25: #include "packet.h"
! 26: #include "authfd.h"
! 27: #include "cipher.h"
! 28: #include "ssh_md5.h"
! 29: #include "mpaux.h"
! 30: #include "uidswap.h"
! 31:
! 32: #ifdef KRB4
! 33: #include <krb.h>
! 34: #ifdef AFS
! 35: #if defined(HAVE_SYS_IOCTL_H) && SunOS != 4
! 36: #include <sys/ioctl.h>
! 37: #endif
! 38: #ifdef HAVE_SYS_FILIO_H
! 39: #include <sys/filio.h>
! 40: #endif
! 41: #include <kafs.h>
! 42: #endif /* AFS */
! 43: #endif /* KRB4 */
! 44:
! 45: /* Session id for the current session. */
! 46: unsigned char session_id[16];
! 47:
! 48: /* Connect to the given ssh server using a proxy command. */
! 49:
! 50: int ssh_proxy_connect(const char *host, int port, uid_t original_real_uid,
! 51: const char *proxy_command, RandomState *random_state)
! 52: {
! 53: Buffer command;
! 54: const char *cp;
! 55: char *command_string;
! 56: int pin[2], pout[2];
! 57: int pid;
! 58: char portstring[100];
! 59:
! 60: /* Convert the port number into a string. */
! 61: sprintf(portstring, "%d", port);
! 62:
! 63: /* Build the final command string in the buffer by making the appropriate
! 64: substitutions to the given proxy command. */
! 65: buffer_init(&command);
! 66: for (cp = proxy_command; *cp; cp++)
! 67: {
! 68: if (cp[0] == '%' && cp[1] == '%')
! 69: {
! 70: buffer_append(&command, "%", 1);
! 71: cp++;
! 72: continue;
! 73: }
! 74: if (cp[0] == '%' && cp[1] == 'h')
! 75: {
! 76: buffer_append(&command, host, strlen(host));
! 77: cp++;
! 78: continue;
! 79: }
! 80: if (cp[0] == '%' && cp[1] == 'p')
! 81: {
! 82: buffer_append(&command, portstring, strlen(portstring));
! 83: cp++;
! 84: continue;
! 85: }
! 86: buffer_append(&command, cp, 1);
! 87: }
! 88: buffer_append(&command, "\0", 1);
! 89:
! 90: /* Get the final command string. */
! 91: command_string = buffer_ptr(&command);
! 92:
! 93: /* Create pipes for communicating with the proxy. */
! 94: if (pipe(pin) < 0 || pipe(pout) < 0)
! 95: fatal("Could not create pipes to communicate with the proxy: %.100s",
! 96: strerror(errno));
! 97:
! 98: debug("Executing proxy command: %.500s", command_string);
! 99:
! 100: /* Fork and execute the proxy command. */
! 101: if ((pid = fork()) == 0)
! 102: {
! 103: char *argv[10];
! 104:
! 105: /* Child. Permanently give up superuser privileges. */
! 106: permanently_set_uid(original_real_uid);
! 107:
! 108: /* Redirect stdin and stdout. */
! 109: close(pin[1]);
! 110: if (pin[0] != 0)
! 111: {
! 112: if (dup2(pin[0], 0) < 0)
! 113: perror("dup2 stdin");
! 114: close(pin[0]);
! 115: }
! 116: close(pout[0]);
! 117: if (dup2(pout[1], 1) < 0)
! 118: perror("dup2 stdout");
! 119: close(pout[1]); /* Cannot be 1 because pin allocated two descriptors. */
! 120:
! 121: /* Stderr is left as it is so that error messages get printed on
! 122: the user's terminal. */
! 123: argv[0] = "/bin/sh";
! 124: argv[1] = "-c";
! 125: argv[2] = command_string;
! 126: argv[3] = NULL;
! 127:
! 128: /* Execute the proxy command. Note that we gave up any extra
! 129: privileges above. */
! 130: execv("/bin/sh", argv);
! 131: perror("/bin/sh");
! 132: exit(1);
! 133: }
! 134: /* Parent. */
! 135: if (pid < 0)
! 136: fatal("fork failed: %.100s", strerror(errno));
! 137:
! 138: /* Close child side of the descriptors. */
! 139: close(pin[0]);
! 140: close(pout[1]);
! 141:
! 142: /* Free the command name. */
! 143: buffer_free(&command);
! 144:
! 145: /* Set the connection file descriptors. */
! 146: packet_set_connection(pout[0], pin[1], random_state);
! 147:
! 148: return 1;
! 149: }
! 150:
! 151: /* Creates a (possibly privileged) socket for use as the ssh connection. */
! 152:
! 153: int ssh_create_socket(uid_t original_real_uid, int privileged)
! 154: {
! 155: int sock;
! 156:
! 157: /* If we are running as root and want to connect to a privileged port,
! 158: bind our own socket to a privileged port. */
! 159: if (privileged)
! 160: {
! 161: struct sockaddr_in sin;
! 162: int p;
! 163: for (p = 1023; p > 512; p--)
! 164: {
! 165: sock = socket(AF_INET, SOCK_STREAM, 0);
! 166: if (sock < 0)
! 167: fatal("socket: %.100s", strerror(errno));
! 168:
! 169: /* Initialize the desired sockaddr_in structure. */
! 170: memset(&sin, 0, sizeof(sin));
! 171: sin.sin_family = AF_INET;
! 172: sin.sin_addr.s_addr = INADDR_ANY;
! 173: sin.sin_port = htons(p);
! 174:
! 175: /* Try to bind the socket to the privileged port. */
! 176: if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
! 177: break; /* Success. */
! 178: if (errno == EADDRINUSE)
! 179: {
! 180: close(sock);
! 181: continue;
! 182: }
! 183: fatal("bind: %.100s", strerror(errno));
! 184: }
! 185: debug("Allocated local port %d.", p);
! 186: }
! 187: else
! 188: {
! 189: /* Just create an ordinary socket on arbitrary port. We use the
! 190: user's uid to create the socket. */
! 191: temporarily_use_uid(original_real_uid);
! 192: sock = socket(AF_INET, SOCK_STREAM, 0);
! 193: if (sock < 0)
! 194: fatal("socket: %.100s", strerror(errno));
! 195: restore_uid();
! 196: }
! 197: return sock;
! 198: }
! 199:
! 200: /* Opens a TCP/IP connection to the remote server on the given host. If
! 201: port is 0, the default port will be used. If anonymous is zero,
! 202: a privileged port will be allocated to make the connection.
! 203: This requires super-user privileges if anonymous is false.
! 204: Connection_attempts specifies the maximum number of tries (one per
! 205: second). If proxy_command is non-NULL, it specifies the command (with %h
! 206: and %p substituted for host and port, respectively) to use to contact
! 207: the daemon. */
! 208:
! 209: int ssh_connect(const char *host, int port, int connection_attempts,
! 210: int anonymous, uid_t original_real_uid,
! 211: const char *proxy_command, RandomState *random_state)
! 212: {
! 213: int sock = -1, attempt, i;
! 214: int on = 1;
! 215: struct servent *sp;
! 216: struct hostent *hp;
! 217: struct sockaddr_in hostaddr;
! 218: #ifdef SO_LINGER
! 219: struct linger linger;
! 220: #endif /* SO_LINGER */
! 221:
! 222: debug("ssh_connect: getuid %d geteuid %d anon %d",
! 223: (int)getuid(), (int)geteuid(), anonymous);
! 224:
! 225: /* Get default port if port has not been set. */
! 226: if (port == 0)
! 227: {
! 228: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
! 229: if (sp)
! 230: port = ntohs(sp->s_port);
! 231: else
! 232: port = SSH_DEFAULT_PORT;
! 233: }
! 234:
! 235: /* If a proxy command is given, connect using it. */
! 236: if (proxy_command != NULL)
! 237: return ssh_proxy_connect(host, port, original_real_uid, proxy_command,
! 238: random_state);
! 239:
! 240: /* No proxy command. */
! 241:
! 242: /* No host lookup made yet. */
! 243: hp = NULL;
! 244:
! 245: /* Try to connect several times. On some machines, the first time will
! 246: sometimes fail. In general socket code appears to behave quite
! 247: magically on many machines. */
! 248: for (attempt = 0; attempt < connection_attempts; attempt++)
! 249: {
! 250: if (attempt > 0)
! 251: debug("Trying again...");
! 252:
! 253: /* Try to parse the host name as a numeric inet address. */
! 254: memset(&hostaddr, 0, sizeof(hostaddr));
! 255: hostaddr.sin_family = AF_INET;
! 256: hostaddr.sin_port = htons(port);
! 257: #ifdef BROKEN_INET_ADDR
! 258: hostaddr.sin_addr.s_addr = inet_network(host);
! 259: #else /* BROKEN_INET_ADDR */
! 260: hostaddr.sin_addr.s_addr = inet_addr(host);
! 261: #endif /* BROKEN_INET_ADDR */
! 262: if ((hostaddr.sin_addr.s_addr & 0xffffffff) != 0xffffffff)
! 263: {
! 264: /* Valid numeric IP address */
! 265: debug("Connecting to %.100s port %d.",
! 266: inet_ntoa(hostaddr.sin_addr), port);
! 267:
! 268: /* Create a socket. */
! 269: sock = ssh_create_socket(original_real_uid,
! 270: !anonymous && geteuid() == 0 &&
! 271: port < 1024);
! 272:
! 273: /* Connect to the host. We use the user's uid in the hope that
! 274: it will help with the problems of tcp_wrappers showing the
! 275: remote uid as root. */
! 276: temporarily_use_uid(original_real_uid);
! 277: if (connect(sock, (struct sockaddr *)&hostaddr, sizeof(hostaddr))
! 278: >= 0)
! 279: {
! 280: /* Successful connect. */
! 281: restore_uid();
! 282: break;
! 283: }
! 284: debug("connect: %.100s", strerror(errno));
! 285: restore_uid();
! 286:
! 287: /* Destroy the failed socket. */
! 288: shutdown(sock, 2);
! 289: close(sock);
! 290: }
! 291: else
! 292: {
! 293: /* Not a valid numeric inet address. */
! 294: /* Map host name to an address. */
! 295: if (!hp)
! 296: hp = gethostbyname(host);
! 297: if (!hp)
! 298: fatal("Bad host name: %.100s", host);
! 299: if (!hp->h_addr_list[0])
! 300: fatal("Host does not have an IP address: %.100s", host);
! 301:
! 302: /* Loop through addresses for this host, and try each one in
! 303: sequence until the connection succeeds. */
! 304: for (i = 0; hp->h_addr_list[i]; i++)
! 305: {
! 306: /* Set the address to connect to. */
! 307: hostaddr.sin_family = hp->h_addrtype;
! 308: memcpy(&hostaddr.sin_addr, hp->h_addr_list[i],
! 309: sizeof(hostaddr.sin_addr));
! 310:
! 311: debug("Connecting to %.200s [%.100s] port %d.",
! 312: host, inet_ntoa(hostaddr.sin_addr), port);
! 313:
! 314: /* Create a socket for connecting. */
! 315: sock = ssh_create_socket(original_real_uid,
! 316: !anonymous && geteuid() == 0 &&
! 317: port < 1024);
! 318:
! 319: /* Connect to the host. We use the user's uid in the hope that
! 320: it will help with tcp_wrappers showing the remote uid as
! 321: root. */
! 322: temporarily_use_uid(original_real_uid);
! 323: if (connect(sock, (struct sockaddr *)&hostaddr,
! 324: sizeof(hostaddr)) >= 0)
! 325: {
! 326: /* Successful connection. */
! 327: restore_uid();
! 328: break;
! 329: }
! 330: debug("connect: %.100s", strerror(errno));
! 331: restore_uid();
! 332:
! 333: /* Close the failed socket; there appear to be some problems
! 334: when reusing a socket for which connect() has already
! 335: returned an error. */
! 336: shutdown(sock, 2);
! 337: close(sock);
! 338: }
! 339: if (hp->h_addr_list[i])
! 340: break; /* Successful connection. */
! 341: }
! 342:
! 343: /* Sleep a moment before retrying. */
! 344: sleep(1);
! 345: }
! 346: /* Return failure if we didn't get a successful connection. */
! 347: if (attempt >= connection_attempts)
! 348: return 0;
! 349:
! 350: debug("Connection established.");
! 351:
! 352: /* Set socket options. We would like the socket to disappear as soon as
! 353: it has been closed for whatever reason. */
! 354: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
! 355: #ifdef TCP_NODELAY
! 356: setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&on, sizeof(on));
! 357: #endif /* TCP_NODELAY */
! 358: #ifdef SO_LINGER
! 359: linger.l_onoff = 1;
! 360: linger.l_linger = 5;
! 361: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
! 362: #endif /* SO_LINGER */
! 363:
! 364: /* Set the connection. */
! 365: packet_set_connection(sock, sock, random_state);
! 366:
! 367: return 1;
! 368: }
! 369:
! 370: /* Checks if the user has an authentication agent, and if so, tries to
! 371: authenticate using the agent. */
! 372:
! 373: int try_agent_authentication()
! 374: {
! 375: int status, type, bits;
! 376: MP_INT e, n, challenge;
! 377: char *comment;
! 378: AuthenticationConnection *auth;
! 379: unsigned char response[16];
! 380: unsigned int i;
! 381:
! 382: /* Get connection to the agent. */
! 383: auth = ssh_get_authentication_connection();
! 384: if (!auth)
! 385: return 0;
! 386:
! 387: mpz_init(&e);
! 388: mpz_init(&n);
! 389: mpz_init(&challenge);
! 390:
! 391: /* Loop through identities served by the agent. */
! 392: for (status = ssh_get_first_identity(auth, &bits, &e, &n, &comment);
! 393: status;
! 394: status = ssh_get_next_identity(auth, &bits, &e, &n, &comment))
! 395: {
! 396: int plen, clen;
! 397:
! 398: /* Try this identity. */
! 399: debug("Trying RSA authentication via agent with '%.100s'", comment);
! 400: xfree(comment);
! 401:
! 402: /* Tell the server that we are willing to authenticate using this key. */
! 403: packet_start(SSH_CMSG_AUTH_RSA);
! 404: packet_put_mp_int(&n);
! 405: packet_send();
! 406: packet_write_wait();
! 407:
! 408: /* Wait for server's response. */
! 409: type = packet_read(&plen);
! 410:
! 411: /* The server sends failure if it doesn\'t like our key or does not
! 412: support RSA authentication. */
! 413: if (type == SSH_SMSG_FAILURE)
! 414: {
! 415: debug("Server refused our key.");
! 416: continue;
! 417: }
! 418:
! 419: /* Otherwise it should have sent a challenge. */
! 420: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
! 421: packet_disconnect("Protocol error during RSA authentication: %d",
! 422: type);
! 423:
! 424: packet_get_mp_int(&challenge, &clen);
! 425:
! 426: packet_integrity_check(plen, clen, type);
! 427:
! 428: debug("Received RSA challenge from server.");
! 429:
! 430: /* Ask the agent to decrypt the challenge. */
! 431: if (!ssh_decrypt_challenge(auth, bits, &e, &n, &challenge,
! 432: session_id, 1, response))
! 433: {
! 434: /* The agent failed to authenticate this identifier although it
! 435: advertised it supports this. Just return a wrong value. */
! 436: log("Authentication agent failed to decrypt challenge.");
! 437: memset(response, 0, sizeof(response));
! 438: }
! 439:
! 440: debug("Sending response to RSA challenge.");
! 441:
! 442: /* Send the decrypted challenge back to the server. */
! 443: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
! 444: for (i = 0; i < 16; i++)
! 445: packet_put_char(response[i]);
! 446: packet_send();
! 447: packet_write_wait();
! 448:
! 449: /* Wait for response from the server. */
! 450: type = packet_read(&plen);
! 451:
! 452: /* The server returns success if it accepted the authentication. */
! 453: if (type == SSH_SMSG_SUCCESS)
! 454: {
! 455: debug("RSA authentication accepted by server.");
! 456: mpz_clear(&e);
! 457: mpz_clear(&n);
! 458: mpz_clear(&challenge);
! 459: return 1;
! 460: }
! 461:
! 462: /* Otherwise it should return failure. */
! 463: if (type != SSH_SMSG_FAILURE)
! 464: packet_disconnect("Protocol error waiting RSA auth response: %d",
! 465: type);
! 466: }
! 467:
! 468: mpz_clear(&e);
! 469: mpz_clear(&n);
! 470: mpz_clear(&challenge);
! 471:
! 472: debug("RSA authentication using agent refused.");
! 473: return 0;
! 474: }
! 475:
! 476: /* Computes the proper response to a RSA challenge, and sends the response to
! 477: the server. */
! 478:
! 479: void respond_to_rsa_challenge(MP_INT *challenge, RSAPrivateKey *prv)
! 480: {
! 481: unsigned char buf[32], response[16];
! 482: struct MD5Context md;
! 483: int i;
! 484:
! 485: /* Decrypt the challenge using the private key. */
! 486: rsa_private_decrypt(challenge, challenge, prv);
! 487:
! 488: /* Compute the response. */
! 489: /* The response is MD5 of decrypted challenge plus session id. */
! 490: mp_linearize_msb_first(buf, 32, challenge);
! 491: MD5Init(&md);
! 492: MD5Update(&md, buf, 32);
! 493: MD5Update(&md, session_id, 16);
! 494: MD5Final(response, &md);
! 495:
! 496: debug("Sending response to host key RSA challenge.");
! 497:
! 498: /* Send the response back to the server. */
! 499: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
! 500: for (i = 0; i < 16; i++)
! 501: packet_put_char(response[i]);
! 502: packet_send();
! 503: packet_write_wait();
! 504:
! 505: memset(buf, 0, sizeof(buf));
! 506: memset(response, 0, sizeof(response));
! 507: memset(&md, 0, sizeof(md));
! 508: }
! 509:
! 510: /* Checks if the user has authentication file, and if so, tries to authenticate
! 511: the user using it. */
! 512:
! 513: int try_rsa_authentication(struct passwd *pw, const char *authfile,
! 514: int may_ask_passphrase)
! 515: {
! 516: MP_INT challenge;
! 517: RSAPrivateKey private_key;
! 518: RSAPublicKey public_key;
! 519: char *passphrase, *comment;
! 520: int type, i;
! 521: int plen, clen;
! 522:
! 523: /* Try to load identification for the authentication key. */
! 524: if (!load_public_key(authfile, &public_key, &comment))
! 525: return 0; /* Could not load it. Fail. */
! 526:
! 527: debug("Trying RSA authentication with key '%.100s'", comment);
! 528:
! 529: /* Tell the server that we are willing to authenticate using this key. */
! 530: packet_start(SSH_CMSG_AUTH_RSA);
! 531: packet_put_mp_int(&public_key.n);
! 532: packet_send();
! 533: packet_write_wait();
! 534:
! 535: /* We no longer need the public key. */
! 536: rsa_clear_public_key(&public_key);
! 537:
! 538: /* Wait for server's response. */
! 539: type = packet_read(&plen);
! 540:
! 541: /* The server responds with failure if it doesn\'t like our key or doesn\'t
! 542: support RSA authentication. */
! 543: if (type == SSH_SMSG_FAILURE)
! 544: {
! 545: debug("Server refused our key.");
! 546: xfree(comment);
! 547: return 0; /* Server refuses to authenticate with this key. */
! 548: }
! 549:
! 550: /* Otherwise, the server should respond with a challenge. */
! 551: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
! 552: packet_disconnect("Protocol error during RSA authentication: %d", type);
! 553:
! 554: /* Get the challenge from the packet. */
! 555: mpz_init(&challenge);
! 556: packet_get_mp_int(&challenge, &clen);
! 557:
! 558: packet_integrity_check(plen, clen, type);
! 559:
! 560: debug("Received RSA challenge from server.");
! 561:
! 562: /* Load the private key. Try first with empty passphrase; if it fails,
! 563: ask for a passphrase. */
! 564: if (!load_private_key(authfile, "", &private_key, NULL))
! 565: {
! 566: char buf[300];
! 567: /* Request passphrase from the user. We read from /dev/tty to make
! 568: this work even if stdin has been redirected. If running in
! 569: batch mode, we just use the empty passphrase, which will fail and
! 570: return. */
! 571: sprintf(buf, "Enter passphrase for RSA key '%.100s': ", comment);
! 572: if (may_ask_passphrase)
! 573: passphrase = read_passphrase(buf, 0);
! 574: else
! 575: {
! 576: debug("Will not query passphrase for %.100s in batch mode.",
! 577: comment);
! 578: passphrase = xstrdup("");
! 579: }
! 580:
! 581: /* Load the authentication file using the pasphrase. */
! 582: if (!load_private_key(authfile, passphrase, &private_key, NULL))
! 583: {
! 584: memset(passphrase, 0, strlen(passphrase));
! 585: xfree(passphrase);
! 586: error("Bad passphrase.");
! 587:
! 588: /* Send a dummy response packet to avoid protocol error. */
! 589: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
! 590: for (i = 0; i < 16; i++)
! 591: packet_put_char(0);
! 592: packet_send();
! 593: packet_write_wait();
! 594:
! 595: /* Expect the server to reject it... */
! 596: packet_read_expect(&plen, SSH_SMSG_FAILURE);
! 597: xfree(comment);
! 598: return 0;
! 599: }
! 600:
! 601: /* Destroy the passphrase. */
! 602: memset(passphrase, 0, strlen(passphrase));
! 603: xfree(passphrase);
! 604: }
! 605:
! 606: /* We no longer need the comment. */
! 607: xfree(comment);
! 608:
! 609: /* Compute and send a response to the challenge. */
! 610: respond_to_rsa_challenge(&challenge, &private_key);
! 611:
! 612: /* Destroy the private key. */
! 613: rsa_clear_private_key(&private_key);
! 614:
! 615: /* We no longer need the challenge. */
! 616: mpz_clear(&challenge);
! 617:
! 618: /* Wait for response from the server. */
! 619: type = packet_read(&plen);
! 620: if (type == SSH_SMSG_SUCCESS)
! 621: {
! 622: debug("RSA authentication accepted by server.");
! 623: return 1;
! 624: }
! 625: if (type != SSH_SMSG_FAILURE)
! 626: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
! 627: debug("RSA authentication refused.");
! 628: return 0;
! 629: }
! 630:
! 631: /* Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
! 632: authentication and RSA host authentication. */
! 633:
! 634: int try_rhosts_rsa_authentication(const char *local_user,
! 635: RSAPrivateKey *host_key)
! 636: {
! 637: int type;
! 638: MP_INT challenge;
! 639: int plen, clen;
! 640:
! 641: debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
! 642:
! 643: /* Tell the server that we are willing to authenticate using this key. */
! 644: packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
! 645: packet_put_string(local_user, strlen(local_user));
! 646: packet_put_int(host_key->bits);
! 647: packet_put_mp_int(&host_key->e);
! 648: packet_put_mp_int(&host_key->n);
! 649: packet_send();
! 650: packet_write_wait();
! 651:
! 652: /* Wait for server's response. */
! 653: type = packet_read(&plen);
! 654:
! 655: /* The server responds with failure if it doesn't admit our .rhosts
! 656: authentication or doesn't know our host key. */
! 657: if (type == SSH_SMSG_FAILURE)
! 658: {
! 659: debug("Server refused our rhosts authentication or host key.");
! 660: return 0; /* Server refuses to authenticate us with this method. */
! 661: }
! 662:
! 663: /* Otherwise, the server should respond with a challenge. */
! 664: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
! 665: packet_disconnect("Protocol error during RSA authentication: %d", type);
! 666:
! 667: /* Get the challenge from the packet. */
! 668: mpz_init(&challenge);
! 669: packet_get_mp_int(&challenge, &clen);
! 670:
! 671: packet_integrity_check(plen, clen, type);
! 672:
! 673: debug("Received RSA challenge for host key from server.");
! 674:
! 675: /* Compute a response to the challenge. */
! 676: respond_to_rsa_challenge(&challenge, host_key);
! 677:
! 678: /* We no longer need the challenge. */
! 679: mpz_clear(&challenge);
! 680:
! 681: /* Wait for response from the server. */
! 682: type = packet_read(&plen);
! 683: if (type == SSH_SMSG_SUCCESS)
! 684: {
! 685: debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
! 686: return 1;
! 687: }
! 688: if (type != SSH_SMSG_FAILURE)
! 689: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
! 690: debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
! 691: return 0;
! 692: }
! 693:
! 694: #ifdef KRB4
! 695: int try_kerberos_authentication()
! 696: {
! 697: KTEXT_ST auth; /* Kerberos data */
! 698: char *reply;
! 699: char inst[INST_SZ];
! 700: char *realm;
! 701: CREDENTIALS cred;
! 702: int r, type;
! 703: Key_schedule schedule;
! 704: u_long checksum, cksum;
! 705: MSG_DAT msg_data;
! 706: struct sockaddr_in local, foreign;
! 707: struct stat st;
! 708: int plen;
! 709:
! 710: /* Don't do anything if we don't have any tickets. */
! 711: if (stat(tkt_string(), &st) < 0) return 0;
! 712:
! 713: debug("Trying Kerberos authentication.");
! 714: strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
! 715:
! 716: realm = (char *)krb_realmofhost(get_canonical_hostname());
! 717: if (!realm) {
! 718: debug("Kerberos V4: no realm for %.100s", get_canonical_hostname());
! 719: return 0;
! 720: }
! 721: /* This can really be anything. */
! 722: checksum = (u_long) getpid();
! 723:
! 724: r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
! 725: if (r != KSUCCESS) {
! 726: debug("Kerberos V4 krb_mk_req failed: %.100s", krb_err_txt[r]);
! 727: return 0;
! 728: }
! 729: /* Get session key to decrypt the server's reply with. */
! 730: r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
! 731: if (r != KSUCCESS) {
! 732: debug("get_cred failed: %.100s", krb_err_txt[r]);
! 733: return 0;
! 734: }
! 735: des_key_sched((des_cblock *)cred.session, schedule);
! 736:
! 737: /* Send authentication info to server. */
! 738: packet_start(SSH_CMSG_AUTH_KERBEROS);
! 739: packet_put_string((char *)auth.dat, auth.length);
! 740: packet_send();
! 741: packet_write_wait();
! 742:
! 743: /* zero the buffer */
! 744: (void) memset(auth.dat, 0, MAX_KTXT_LEN);
! 745:
! 746: r = sizeof(local);
! 747: memset(&local, 0, sizeof(local));
! 748: if (getsockname(packet_get_connection_in(),
! 749: (struct sockaddr *) &local, &r) < 0)
! 750: debug("getsockname failed: %.100s", strerror(errno));
! 751:
! 752: r = sizeof(foreign);
! 753: memset(&foreign, 0, sizeof(foreign));
! 754: if (getpeername(packet_get_connection_in(),
! 755: (struct sockaddr *)&foreign, &r) < 0)
! 756: debug("getpeername failed: %.100s", strerror(errno));
! 757:
! 758: /* Get server reply. */
! 759: type = packet_read(&plen);
! 760: switch(type) {
! 761:
! 762: case SSH_SMSG_FAILURE: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
! 763: debug("Kerberos V4 authentication failed.");
! 764: return 0;
! 765: break;
! 766:
! 767: case SSH_SMSG_AUTH_KERBEROS_RESPONSE: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
! 768: debug("Kerberos V4 authentication accepted.");
! 769:
! 770: /* Get server's response. */
! 771: reply = packet_get_string((unsigned int *)&auth.length);
! 772: memcpy(auth.dat, reply, auth.length);
! 773: xfree(reply);
! 774:
! 775: packet_integrity_check(plen, 4 + auth.length, type);
! 776:
! 777: /* If his response isn't properly encrypted with the session key,
! 778: and the decrypted checksum fails to match, he's bogus. Bail out. */
! 779: r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
! 780: &foreign, &local, &msg_data);
! 781: if (r != KSUCCESS) {
! 782: debug("Kerberos V4 krb_rd_priv failed: %.100s", krb_err_txt[r]);
! 783: packet_disconnect("Kerberos V4 challenge failed!");
! 784: }
! 785: /* fetch the (incremented) checksum that we supplied in the request */
! 786: (void)memcpy((char *)&cksum, (char *)msg_data.app_data, sizeof(cksum));
! 787: cksum = ntohl(cksum);
! 788:
! 789: /* If it matches, we're golden. */
! 790: if (cksum == checksum + 1) {
! 791: debug("Kerberos V4 challenge successful.");
! 792: return 1;
! 793: }
! 794: else
! 795: packet_disconnect("Kerberos V4 challenge failed!");
! 796: break;
! 797:
! 798: default:
! 799: packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
! 800: }
! 801: return 0;
! 802: }
! 803: #endif /* KRB4 */
! 804:
! 805: #ifdef AFS
! 806:
! 807: #ifdef KERBEROS_TGT_PASSING
! 808: int send_kerberos_tgt()
! 809: {
! 810: CREDENTIALS *creds;
! 811: char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
! 812: int r, plen, type;
! 813: unsigned char buffer[8192];
! 814: struct stat st;
! 815:
! 816: /* Don't do anything if we don't have any tickets. */
! 817: if (stat(tkt_string(), &st) < 0) return 0;
! 818:
! 819: creds = xmalloc(sizeof(CREDENTIALS));
! 820:
! 821: if ((r=krb_get_tf_fullname(TKT_FILE,pname,pinst,prealm)) != KSUCCESS) {
! 822: debug("Kerberos V4 tf_fullname failed: %.100s",krb_err_txt[r]);
! 823: return 0;
! 824: }
! 825: if ((r=krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
! 826: debug("Kerberos V4 get_cred failed: %.100s", krb_err_txt[r]);
! 827: return 0;
! 828: }
! 829: if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
! 830: debug("Kerberos V4 ticket expired: %.100s", TKT_FILE);
! 831: return 0;
! 832: }
! 833:
! 834: creds_to_radix(creds, buffer);
! 835: xfree(creds);
! 836:
! 837: packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
! 838: packet_put_string((char *)buffer, strlen(buffer));
! 839: packet_send();
! 840: packet_write_wait();
! 841:
! 842: type = packet_read(&plen);
! 843:
! 844: if (type == SSH_SMSG_FAILURE)
! 845: debug("Kerberos TGT for realm %.100s rejected.", prealm);
! 846: else if (type != SSH_SMSG_SUCCESS)
! 847: packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
! 848:
! 849: return 1;
! 850: }
! 851: #endif /* KERBEROS_TGT_PASSING */
! 852:
! 853: /* Forwards our AFS tokens to the server. */
! 854: void send_afs_tokens(void)
! 855: {
! 856: CREDENTIALS creds;
! 857: struct ViceIoctl parms;
! 858: struct ClearToken ct;
! 859: int i, type;
! 860: int len, plen;
! 861: char buf[2048], *p, *server_cell;
! 862: unsigned char buffer[8192];
! 863:
! 864: /* Move over ktc_GetToken, here's something leaner. */
! 865: for (i = 0; i < 100; i++) { /* just in case */
! 866: parms.in = (char *)&i;
! 867: parms.in_size = sizeof(i);
! 868: parms.out = buf;
! 869: parms.out_size = sizeof(buf);
! 870: if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) break;
! 871: p = buf;
! 872:
! 873: /* Get secret token. */
! 874: memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
! 875: if (creds.ticket_st.length > MAX_KTXT_LEN) break;
! 876: p += sizeof(unsigned int);
! 877: memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
! 878: p += creds.ticket_st.length;
! 879:
! 880: /* Get clear token. */
! 881: memcpy(&len, p, sizeof(len));
! 882: if (len != sizeof(struct ClearToken)) break;
! 883: p += sizeof(len);
! 884: memcpy(&ct, p, len);
! 885: p += len;
! 886: p += sizeof(len); /* primary flag */
! 887: server_cell = p;
! 888:
! 889: /* Flesh out our credentials. */
! 890: strcpy(creds.service, "afs");
! 891: creds.instance[0] = '\0';
! 892: strncpy(creds.realm, server_cell, REALM_SZ);
! 893: memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
! 894: creds.issue_date = ct.BeginTimestamp;
! 895: creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
! 896: creds.kvno = ct.AuthHandle;
! 897: sprintf(creds.pname, "AFS ID %d", ct.ViceId);
! 898: creds.pinst[0] = '\0';
! 899:
! 900: /* Encode token, ship it off. */
! 901: if (!creds_to_radix(&creds, buffer)) break;
! 902: packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
! 903: packet_put_string((char *)buffer, strlen(buffer));
! 904: packet_send();
! 905: packet_write_wait();
! 906:
! 907: /* Roger, Roger. Clearance, Clarence. What's your vector, Victor? */
! 908: type = packet_read(&plen);
! 909:
! 910: if (type == SSH_SMSG_FAILURE)
! 911: debug("AFS token for cell %.100s rejected.", server_cell);
! 912: else if (type != SSH_SMSG_SUCCESS)
! 913: packet_disconnect("Protocol error on AFS token response: %d", type);
! 914: }
! 915: }
! 916: #endif /* AFS */
! 917:
! 918: /* Waits for the server identification string, and sends our own identification
! 919: string. */
! 920:
! 921: void ssh_exchange_identification()
! 922: {
! 923: char buf[256], remote_version[256]; /* must be same size! */
! 924: int remote_major, remote_minor, i;
! 925: int connection_in = packet_get_connection_in();
! 926: int connection_out = packet_get_connection_out();
! 927:
! 928: /* Read other side\'s version identification. */
! 929: for (i = 0; i < sizeof(buf) - 1; i++)
! 930: {
! 931: if (read(connection_in, &buf[i], 1) != 1)
! 932: fatal("read: %.100s", strerror(errno));
! 933: if (buf[i] == '\r')
! 934: {
! 935: buf[i] = '\n';
! 936: buf[i + 1] = 0;
! 937: break;
! 938: }
! 939: if (buf[i] == '\n')
! 940: {
! 941: buf[i + 1] = 0;
! 942: break;
! 943: }
! 944: }
! 945: buf[sizeof(buf) - 1] = 0;
! 946:
! 947: /* Check that the versions match. In future this might accept several
! 948: versions and set appropriate flags to handle them. */
! 949: if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor,
! 950: remote_version) != 3)
! 951: fatal("Bad remote protocol version identification: '%.100s'", buf);
! 952: debug("Remote protocol version %d.%d, remote software version %.100s",
! 953: remote_major, remote_minor, remote_version);
! 954: #if 0
! 955: /* Removed for now, to permit compatibility with latter versions. The server
! 956: will reject our version and disconnect if it doesn't support it. */
! 957: if (remote_major != PROTOCOL_MAJOR)
! 958: fatal("Protocol major versions differ: %d vs. %d",
! 959: PROTOCOL_MAJOR, remote_major);
! 960: #endif
! 961:
! 962: /* Check if the remote protocol version is too old. */
! 963: if (remote_major == 1 && remote_minor == 0)
! 964: fatal("Remote machine has too old SSH software version.");
! 965:
! 966: /* Send our own protocol version identification. */
! 967: sprintf(buf, "SSH-%d.%d-%.100s\n",
! 968: PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
! 969: if (write(connection_out, buf, strlen(buf)) != strlen(buf))
! 970: fatal("write: %.100s", strerror(errno));
! 971: }
! 972:
! 973: int ssh_cipher_default = SSH_CIPHER_3DES;
! 974:
! 975: int read_yes_or_no(const char *prompt, int defval)
! 976: {
! 977: char buf[1024];
! 978: FILE *f;
! 979: int retval = -1;
! 980:
! 981: if (isatty(0))
! 982: f = stdin;
! 983: else
! 984: f = fopen("/dev/tty", "rw");
! 985:
! 986: if (f == NULL)
! 987: return 0;
! 988:
! 989: fflush(stdout);
! 990:
! 991: while (1)
! 992: {
! 993: fprintf(stderr, "%s", prompt);
! 994: if (fgets(buf, sizeof(buf), f) == NULL)
! 995: {
! 996: /* Print a newline (the prompt probably didn\'t have one). */
! 997: fprintf(stderr, "\n");
! 998: strcpy(buf, "no");
! 999: }
! 1000: /* Remove newline from response. */
! 1001: if (strchr(buf, '\n'))
! 1002: *strchr(buf, '\n') = 0;
! 1003:
! 1004: if (buf[0] == 0)
! 1005: retval = defval;
! 1006: if (strcmp(buf, "yes") == 0)
! 1007: retval = 1;
! 1008: if (strcmp(buf, "no") == 0)
! 1009: retval = 0;
! 1010:
! 1011: if (retval != -1)
! 1012: {
! 1013: if (f != stdin)
! 1014: fclose(f);
! 1015: return retval;
! 1016: }
! 1017: }
! 1018: }
! 1019:
! 1020: /* Starts a dialog with the server, and authenticates the current user on the
! 1021: server. This does not need any extra privileges. The basic connection
! 1022: to the server must already have been established before this is called.
! 1023: User is the remote user; if it is NULL, the current local user name will
! 1024: be used. Anonymous indicates that no rhosts authentication will be used.
! 1025: If login fails, this function prints an error and never returns.
! 1026: This function does not require super-user privileges. */
! 1027:
! 1028: void ssh_login(RandomState *state, int host_key_valid,
! 1029: RSAPrivateKey *own_host_key,
! 1030: const char *orighost,
! 1031: Options *options, uid_t original_real_uid)
! 1032: {
! 1033: int i, type;
! 1034: char buf[1024];
! 1035: char *password;
! 1036: struct passwd *pw;
! 1037: MP_INT key;
! 1038: RSAPublicKey host_key;
! 1039: RSAPublicKey public_key;
! 1040: unsigned char session_key[SSH_SESSION_KEY_LENGTH];
! 1041: const char *server_user, *local_user;
! 1042: char *cp, *host;
! 1043: struct stat st;
! 1044: unsigned char check_bytes[8];
! 1045: unsigned int supported_ciphers, supported_authentications, protocol_flags;
! 1046: HostStatus host_status;
! 1047: int payload_len, clen, sum_len = 0;
! 1048:
! 1049: /* Convert the user-supplied hostname into all lowercase. */
! 1050: host = xstrdup(orighost);
! 1051: for (cp = host; *cp; cp++)
! 1052: if (isupper(*cp))
! 1053: *cp = tolower(*cp);
! 1054:
! 1055: /* Exchange protocol version identification strings with the server. */
! 1056: ssh_exchange_identification();
! 1057:
! 1058: /* Put the connection into non-blocking mode. */
! 1059: packet_set_nonblocking();
! 1060:
! 1061: /* Get local user name. Use it as server user if no user name
! 1062: was given. */
! 1063: pw = getpwuid(original_real_uid);
! 1064: if (!pw)
! 1065: fatal("User id %d not found from user database.", original_real_uid);
! 1066: local_user = xstrdup(pw->pw_name);
! 1067: server_user = options->user ? options->user : local_user;
! 1068:
! 1069: debug("Waiting for server public key.");
! 1070:
! 1071: /* Wait for a public key packet from the server. */
! 1072: packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
! 1073:
! 1074: /* Get check bytes from the packet. */
! 1075: for (i = 0; i < 8; i++)
! 1076: check_bytes[i] = packet_get_char();
! 1077:
! 1078: /* Get the public key. */
! 1079: public_key.bits = packet_get_int();
! 1080: mpz_init(&public_key.e);
! 1081: packet_get_mp_int(&public_key.e, &clen);
! 1082: sum_len += clen;
! 1083: mpz_init(&public_key.n);
! 1084: packet_get_mp_int(&public_key.n, &clen);
! 1085: sum_len += clen;
! 1086:
! 1087: /* Get the host key. */
! 1088: host_key.bits = packet_get_int();
! 1089: mpz_init(&host_key.e);
! 1090: packet_get_mp_int(&host_key.e, &clen);
! 1091: sum_len += clen;
! 1092: mpz_init(&host_key.n);
! 1093: packet_get_mp_int(&host_key.n, &clen);
! 1094: sum_len += clen;
! 1095:
! 1096: /* Get protocol flags. */
! 1097: protocol_flags = packet_get_int();
! 1098: packet_set_protocol_flags(protocol_flags);
! 1099:
! 1100: /* Get supported cipher types. */
! 1101: supported_ciphers = packet_get_int();
! 1102:
! 1103: /* Get supported authentication types. */
! 1104: supported_authentications = packet_get_int();
! 1105:
! 1106: debug("Received server public key (%d bits) and host key (%d bits).",
! 1107: public_key.bits, host_key.bits);
! 1108:
! 1109: packet_integrity_check(payload_len,
! 1110: 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
! 1111: SSH_SMSG_PUBLIC_KEY);
! 1112:
! 1113: /* Compute the session id. */
! 1114: compute_session_id(session_id, check_bytes, host_key.bits, &host_key.n,
! 1115: public_key.bits, &public_key.n);
! 1116:
! 1117: /* Check if the host key is present in the user\'s list of known hosts
! 1118: or in the systemwide list. */
! 1119: host_status = check_host_in_hostfile(options->user_hostfile,
! 1120: host, host_key.bits,
! 1121: &host_key.e, &host_key.n);
! 1122: if (host_status == HOST_NEW)
! 1123: host_status = check_host_in_hostfile(options->system_hostfile, host,
! 1124: host_key.bits, &host_key.e,
! 1125: &host_key.n);
! 1126:
! 1127: /* Force accepting of the host key for localhost and 127.0.0.1.
! 1128: The problem is that if the home directory is NFS-mounted to multiple
! 1129: machines, localhost will refer to a different machine in each of them,
! 1130: and the user will get bogus HOST_CHANGED warnings. This essentially
! 1131: disables host authentication for localhost; however, this is probably
! 1132: not a real problem. */
! 1133: if (strcmp(host, "localhost") == 0 ||
! 1134: strcmp(host, "127.0.0.1") == 0)
! 1135: {
! 1136: debug("Forcing accepting of host key for localhost.");
! 1137: host_status = HOST_OK;
! 1138: }
! 1139:
! 1140: switch (host_status)
! 1141: {
! 1142: case HOST_OK:
! 1143: /* The host is known and the key matches. */
! 1144: debug("Host '%.200s' is known and matches the host key.", host);
! 1145: break;
! 1146: case HOST_NEW:
! 1147: /* The host is new. */
! 1148: if (options->strict_host_key_checking == 1)
! 1149: { /* User has requested strict host key checking. We will not
! 1150: add the host key automatically. The only alternative left
! 1151: is to abort. */
! 1152: fatal("No host key is known for %.200s and you have requested strict checking.", host);
! 1153: }
! 1154: else if (options->strict_host_key_checking == 2) /* The default */
! 1155: {
! 1156: char prompt[1024];
! 1157: sprintf(prompt,
! 1158: "The authenticity of host '%.200s' can't be established.\n"
! 1159: "Are you sure you want to continue connecting (yes/no)? ",
! 1160: host);
! 1161: if (!read_yes_or_no(prompt, -1))
! 1162: fatal("Aborted by user!\n");
! 1163: }
! 1164: /* If not in strict mode, add the key automatically to the local
! 1165: known_hosts file. */
! 1166: if (!add_host_to_hostfile(options->user_hostfile, host, host_key.bits,
! 1167: &host_key.e, &host_key.n))
! 1168: log("Failed to add the host to the list of known hosts (%.500s).",
! 1169: options->user_hostfile);
! 1170: else
! 1171: log("Warning: Permanently added host '%.200s' to the list of known hosts.", host);
! 1172: break;
! 1173: case HOST_CHANGED:
! 1174: /* The host key has changed. */
! 1175: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
! 1176: error("@ WARNING: HOST IDENTIFICATION HAS CHANGED! @");
! 1177: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
! 1178: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
! 1179: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
! 1180: error("It is also possible that the host key has just been changed.");
! 1181: error("Please contact your system administrator.");
! 1182: error("Add correct host key in %.100s to get rid of this message.",
! 1183: options->user_hostfile);
! 1184:
! 1185: /* If strict host key checking is in use, the user will have to edit
! 1186: the key manually and we can only abort. */
! 1187: if (options->strict_host_key_checking)
! 1188: fatal("Host key for %.200s has changed and you have requested strict checking.", host);
! 1189:
! 1190: /* If strict host key checking has not been requested, allow the
! 1191: connection but without password authentication. */
! 1192: error("Password authentication is disabled to avoid trojan horses.");
! 1193: options->password_authentication = 0;
! 1194: /* XXX Should permit the user to change to use the new id. This could
! 1195: be done by converting the host key to an identifying sentence, tell
! 1196: that the host identifies itself by that sentence, and ask the user
! 1197: if he/she whishes to accept the authentication. */
! 1198: break;
! 1199: }
! 1200:
! 1201: /* Generate a session key. */
! 1202:
! 1203: /* Initialize the random number generator. */
! 1204: sprintf(buf, "%.500s/%.200s", pw->pw_dir, SSH_CLIENT_SEEDFILE);
! 1205: if (stat(buf, &st) < 0)
! 1206: log("Creating random seed file ~/%.900s. This may take a while.",
! 1207: SSH_CLIENT_SEEDFILE);
! 1208: else
! 1209: debug("Initializing random; seed file %.900s", buf);
! 1210: random_initialize(state, buf);
! 1211:
! 1212: /* Generate an encryption key for the session. The key is a 256 bit
! 1213: random number, interpreted as a 32-byte key, with the least significant
! 1214: 8 bits being the first byte of the key. */
! 1215: for (i = 0; i < 32; i++)
! 1216: session_key[i] = random_get_byte(state);
! 1217:
! 1218: /* Save the new random state. */
! 1219: random_save(state, buf);
! 1220: random_stir(state); /* This is supposed to be irreversible. */
! 1221:
! 1222: /* According to the protocol spec, the first byte of the session key is
! 1223: the highest byte of the integer. The session key is xored with the
! 1224: first 16 bytes of the session id. */
! 1225: mpz_init_set_ui(&key, 0);
! 1226: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++)
! 1227: {
! 1228: mpz_mul_2exp(&key, &key, 8);
! 1229: if (i < 16)
! 1230: mpz_add_ui(&key, &key, session_key[i] ^ session_id[i]);
! 1231: else
! 1232: mpz_add_ui(&key, &key, session_key[i]);
! 1233: }
! 1234:
! 1235: /* Encrypt the integer using the public key and host key of the server
! 1236: (key with smaller modulus first). */
! 1237: if (mpz_cmp(&public_key.n, &host_key.n) < 0)
! 1238: {
! 1239: /* Public key has smaller modulus. */
! 1240: assert(host_key.bits >= public_key.bits + SSH_KEY_BITS_RESERVED);
! 1241:
! 1242: rsa_public_encrypt(&key, &key, &public_key, state);
! 1243: rsa_public_encrypt(&key, &key, &host_key, state);
! 1244: }
! 1245: else
! 1246: {
! 1247: /* Host key has smaller modulus (or they are equal). */
! 1248: assert(public_key.bits >= host_key.bits + SSH_KEY_BITS_RESERVED);
! 1249:
! 1250: rsa_public_encrypt(&key, &key, &host_key, state);
! 1251: rsa_public_encrypt(&key, &key, &public_key, state);
! 1252: }
! 1253:
! 1254: if (options->cipher == SSH_CIPHER_NOT_SET)
! 1255: if (cipher_mask() & supported_ciphers & (1 << ssh_cipher_default))
! 1256: options->cipher = ssh_cipher_default;
! 1257: else
! 1258: {
! 1259: debug("Cipher %d not supported, using %.100s instead.",
! 1260: cipher_name(ssh_cipher_default),
! 1261: cipher_name(SSH_FALLBACK_CIPHER));
! 1262: options->cipher = SSH_FALLBACK_CIPHER;
! 1263: }
! 1264:
! 1265: /* Check that the selected cipher is supported. */
! 1266: if (!(supported_ciphers & (1 << options->cipher)))
! 1267: fatal("Selected cipher type %.100s not supported by server.",
! 1268: cipher_name(options->cipher));
! 1269:
! 1270: debug("Encryption type: %.100s", cipher_name(options->cipher));
! 1271:
! 1272: /* Send the encrypted session key to the server. */
! 1273: packet_start(SSH_CMSG_SESSION_KEY);
! 1274: packet_put_char(options->cipher);
! 1275:
! 1276: /* Send the check bytes back to the server. */
! 1277: for (i = 0; i < 8; i++)
! 1278: packet_put_char(check_bytes[i]);
! 1279:
! 1280: /* Send the encrypted encryption key. */
! 1281: packet_put_mp_int(&key);
! 1282:
! 1283: /* Send protocol flags. */
! 1284: packet_put_int(SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
! 1285:
! 1286: /* Send the packet now. */
! 1287: packet_send();
! 1288: packet_write_wait();
! 1289:
! 1290: /* Destroy the session key integer and the public keys since we no longer
! 1291: need them. */
! 1292: mpz_clear(&key);
! 1293: rsa_clear_public_key(&public_key);
! 1294: rsa_clear_public_key(&host_key);
! 1295:
! 1296: debug("Sent encrypted session key.");
! 1297:
! 1298: /* Set the encryption key. */
! 1299: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH,
! 1300: options->cipher, 1);
! 1301:
! 1302: /* We will no longer need the session key here. Destroy any extra copies. */
! 1303: memset(session_key, 0, sizeof(session_key));
! 1304:
! 1305: /* Expect a success message from the server. Note that this message will
! 1306: be received in encrypted form. */
! 1307: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
! 1308:
! 1309: debug("Received encrypted confirmation.");
! 1310:
! 1311: /* Send the name of the user to log in as on the server. */
! 1312: packet_start(SSH_CMSG_USER);
! 1313: packet_put_string(server_user, strlen(server_user));
! 1314: packet_send();
! 1315: packet_write_wait();
! 1316:
! 1317: /* The server should respond with success if no authentication is needed
! 1318: (the user has no password). Otherwise the server responds with
! 1319: failure. */
! 1320: type = packet_read(&payload_len);
! 1321: if (type == SSH_SMSG_SUCCESS)
! 1322: return; /* Connection was accepted without authentication. */
! 1323: if (type != SSH_SMSG_FAILURE)
! 1324: packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
! 1325: type);
! 1326:
! 1327: #ifdef KERBEROS_TGT_PASSING
! 1328: /* Try Kerberos tgt passing if the server supports it. */
! 1329: if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
! 1330: options->kerberos_tgt_passing) {
! 1331: if (options->cipher == SSH_CIPHER_NONE)
! 1332: log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
! 1333: (void)send_kerberos_tgt();
! 1334: }
! 1335: #endif /* KERBEROS_TGT_PASSING */
! 1336:
! 1337: #ifdef AFS
! 1338: /* Try AFS token passing if the server supports it. */
! 1339: if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
! 1340: options->afs_token_passing && k_hasafs()) {
! 1341: if (options->cipher == SSH_CIPHER_NONE)
! 1342: log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
! 1343: send_afs_tokens();
! 1344: }
! 1345: #endif /* AFS */
! 1346:
! 1347: #if defined(KRB4)
! 1348: if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
! 1349: options->kerberos_authentication)
! 1350: {
! 1351: if (try_kerberos_authentication()) {
! 1352: /* The server should respond with success or failure. */
! 1353: type = packet_read(&payload_len);
! 1354: if (type == SSH_SMSG_SUCCESS)
! 1355: return; /* Successful connection. */
! 1356: if (type != SSH_SMSG_FAILURE)
! 1357: packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
! 1358: }
! 1359: }
! 1360: #endif /* KRB4 */
! 1361:
! 1362: /* Use rhosts authentication if running in privileged socket and we do not
! 1363: wish to remain anonymous. */
! 1364: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
! 1365: options->rhosts_authentication)
! 1366: {
! 1367: debug("Trying rhosts authentication.");
! 1368: packet_start(SSH_CMSG_AUTH_RHOSTS);
! 1369: packet_put_string(local_user, strlen(local_user));
! 1370: packet_send();
! 1371: packet_write_wait();
! 1372:
! 1373: /* The server should respond with success or failure. */
! 1374: type = packet_read(&payload_len);
! 1375: if (type == SSH_SMSG_SUCCESS)
! 1376: return; /* Successful connection. */
! 1377: if (type != SSH_SMSG_FAILURE)
! 1378: packet_disconnect("Protocol error: got %d in response to rhosts auth",
! 1379: type);
! 1380: }
! 1381:
! 1382: /* Try .rhosts or /etc/hosts.equiv authentication with RSA host
! 1383: authentication. */
! 1384: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
! 1385: options->rhosts_rsa_authentication && host_key_valid)
! 1386: {
! 1387: if (try_rhosts_rsa_authentication(local_user, own_host_key))
! 1388: return; /* Successful authentication. */
! 1389: }
! 1390:
! 1391: /* Try RSA authentication if the server supports it. */
! 1392: if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
! 1393: options->rsa_authentication)
! 1394: {
! 1395: /* Try RSA authentication using the authentication agent. The agent
! 1396: is tried first because no passphrase is needed for it, whereas
! 1397: identity files may require passphrases. */
! 1398: if (try_agent_authentication())
! 1399: return; /* Successful connection. */
! 1400:
! 1401: /* Try RSA authentication for each identity. */
! 1402: for (i = 0; i < options->num_identity_files; i++)
! 1403: if (try_rsa_authentication(pw, options->identity_files[i],
! 1404: !options->batch_mode))
! 1405: return; /* Successful connection. */
! 1406: }
! 1407:
! 1408: /* Try password authentication if the server supports it. */
! 1409: if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
! 1410: options->password_authentication && !options->batch_mode)
! 1411: {
! 1412: debug("Doing password authentication.");
! 1413: if (options->cipher == SSH_CIPHER_NONE)
! 1414: log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
! 1415: password = read_passphrase("Password: ", 0);
! 1416: packet_start(SSH_CMSG_AUTH_PASSWORD);
! 1417: packet_put_string(password, strlen(password));
! 1418: memset(password, 0, strlen(password));
! 1419: xfree(password);
! 1420: packet_send();
! 1421: packet_write_wait();
! 1422:
! 1423: type = packet_read(&payload_len);
! 1424: if (type == SSH_SMSG_SUCCESS)
! 1425: return; /* Successful connection. */
! 1426: if (type != SSH_SMSG_FAILURE)
! 1427: packet_disconnect("Protocol error: got %d in response to passwd auth",
! 1428: type);
! 1429: }
! 1430:
! 1431: /* All authentication methods have failed. Exit with an error message. */
! 1432: fatal("Permission denied.");
! 1433: /*NOTREACHED*/
! 1434: }
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