Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 1 | /* $OpenBSD: sshd.c,v 1.385 2011/06/23 09:34:13 djm Exp $ */ |
| 2 | /* |
| 3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 5 | * All rights reserved |
| 6 | * This program is the ssh daemon. It listens for connections from clients, |
| 7 | * and performs authentication, executes use commands or shell, and forwards |
| 8 | * information to/from the application to the user client over an encrypted |
| 9 | * connection. This can also handle forwarding of X11, TCP/IP, and |
| 10 | * authentication agent connections. |
| 11 | * |
| 12 | * As far as I am concerned, the code I have written for this software |
| 13 | * can be used freely for any purpose. Any derived versions of this |
| 14 | * software must be clearly marked as such, and if the derived work is |
| 15 | * incompatible with the protocol description in the RFC file, it must be |
| 16 | * called by a name other than "ssh" or "Secure Shell". |
| 17 | * |
| 18 | * SSH2 implementation: |
| 19 | * Privilege Separation: |
| 20 | * |
| 21 | * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. |
| 22 | * Copyright (c) 2002 Niels Provos. All rights reserved. |
| 23 | * |
| 24 | * Redistribution and use in source and binary forms, with or without |
| 25 | * modification, are permitted provided that the following conditions |
| 26 | * are met: |
| 27 | * 1. Redistributions of source code must retain the above copyright |
| 28 | * notice, this list of conditions and the following disclaimer. |
| 29 | * 2. Redistributions in binary form must reproduce the above copyright |
| 30 | * notice, this list of conditions and the following disclaimer in the |
| 31 | * documentation and/or other materials provided with the distribution. |
| 32 | * |
| 33 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 34 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 35 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 36 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 37 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 38 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 39 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 40 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 41 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 42 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 43 | */ |
| 44 | |
| 45 | #include "includes.h" |
| 46 | |
| 47 | #include <sys/types.h> |
| 48 | #include <sys/ioctl.h> |
| 49 | #include <sys/socket.h> |
| 50 | #ifdef HAVE_SYS_STAT_H |
| 51 | # include <sys/stat.h> |
| 52 | #endif |
| 53 | #ifdef HAVE_SYS_TIME_H |
| 54 | # include <sys/time.h> |
| 55 | #endif |
| 56 | #include "openbsd-compat/sys-tree.h" |
| 57 | #include "openbsd-compat/sys-queue.h" |
| 58 | #include <sys/wait.h> |
| 59 | |
| 60 | #include <errno.h> |
| 61 | #include <fcntl.h> |
| 62 | #include <netdb.h> |
| 63 | #ifdef HAVE_PATHS_H |
| 64 | #include <paths.h> |
| 65 | #endif |
| 66 | #include <grp.h> |
| 67 | #include <pwd.h> |
| 68 | #include <signal.h> |
| 69 | #include <stdarg.h> |
| 70 | #include <stdio.h> |
| 71 | #include <stdlib.h> |
| 72 | #include <string.h> |
| 73 | #include <unistd.h> |
| 74 | |
| 75 | #include <openssl/dh.h> |
| 76 | #include <openssl/bn.h> |
| 77 | #include <openssl/md5.h> |
| 78 | #include <openssl/rand.h> |
| 79 | #include "openbsd-compat/openssl-compat.h" |
| 80 | |
| 81 | #ifdef HAVE_SECUREWARE |
| 82 | #include <sys/security.h> |
| 83 | #include <prot.h> |
| 84 | #endif |
| 85 | |
| 86 | #include "xmalloc.h" |
| 87 | #include "ssh.h" |
| 88 | #include "ssh1.h" |
| 89 | #include "ssh2.h" |
| 90 | #include "rsa.h" |
| 91 | #include "sshpty.h" |
| 92 | #include "packet.h" |
| 93 | #include "log.h" |
| 94 | #include "buffer.h" |
| 95 | #include "servconf.h" |
| 96 | #include "uidswap.h" |
| 97 | #include "compat.h" |
| 98 | #include "cipher.h" |
| 99 | #include "key.h" |
| 100 | #include "kex.h" |
| 101 | #include "dh.h" |
| 102 | #include "myproposal.h" |
| 103 | #include "authfile.h" |
| 104 | #include "pathnames.h" |
| 105 | #include "atomicio.h" |
| 106 | #include "canohost.h" |
| 107 | #include "hostfile.h" |
| 108 | #include "auth.h" |
| 109 | #include "misc.h" |
| 110 | #include "msg.h" |
| 111 | #include "dispatch.h" |
| 112 | #include "channels.h" |
| 113 | #include "session.h" |
| 114 | #include "monitor_mm.h" |
| 115 | #include "monitor.h" |
| 116 | #ifdef GSSAPI |
| 117 | #include "ssh-gss.h" |
| 118 | #endif |
| 119 | #include "monitor_wrap.h" |
| 120 | #include "roaming.h" |
| 121 | #include "ssh-sandbox.h" |
| 122 | #include "version.h" |
| 123 | |
| 124 | #ifdef LIBWRAP |
| 125 | #include <tcpd.h> |
| 126 | #include <syslog.h> |
| 127 | int allow_severity; |
| 128 | int deny_severity; |
| 129 | #endif /* LIBWRAP */ |
| 130 | |
| 131 | #ifndef O_NOCTTY |
| 132 | #define O_NOCTTY 0 |
| 133 | #endif |
| 134 | |
| 135 | /* Re-exec fds */ |
| 136 | #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) |
| 137 | #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) |
| 138 | #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) |
| 139 | #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) |
| 140 | |
| 141 | extern char *__progname; |
| 142 | |
| 143 | /* Server configuration options. */ |
| 144 | ServerOptions options; |
| 145 | |
| 146 | /* Name of the server configuration file. */ |
| 147 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; |
| 148 | |
| 149 | /* |
| 150 | * Debug mode flag. This can be set on the command line. If debug |
| 151 | * mode is enabled, extra debugging output will be sent to the system |
| 152 | * log, the daemon will not go to background, and will exit after processing |
| 153 | * the first connection. |
| 154 | */ |
| 155 | int debug_flag = 0; |
| 156 | |
| 157 | /* Flag indicating that the daemon should only test the configuration and keys. */ |
| 158 | int test_flag = 0; |
| 159 | |
| 160 | /* Flag indicating that the daemon is being started from inetd. */ |
| 161 | int inetd_flag = 0; |
| 162 | |
| 163 | /* Flag indicating that sshd should not detach and become a daemon. */ |
| 164 | int no_daemon_flag = 0; |
| 165 | |
| 166 | /* debug goes to stderr unless inetd_flag is set */ |
| 167 | int log_stderr = 0; |
| 168 | |
| 169 | /* Saved arguments to main(). */ |
| 170 | char **saved_argv; |
| 171 | int saved_argc; |
| 172 | |
| 173 | /* re-exec */ |
| 174 | int rexeced_flag = 0; |
| 175 | int rexec_flag = 1; |
| 176 | int rexec_argc = 0; |
| 177 | char **rexec_argv; |
| 178 | |
| 179 | /* |
| 180 | * The sockets that the server is listening; this is used in the SIGHUP |
| 181 | * signal handler. |
| 182 | */ |
| 183 | #define MAX_LISTEN_SOCKS 16 |
| 184 | int listen_socks[MAX_LISTEN_SOCKS]; |
| 185 | int num_listen_socks = 0; |
| 186 | |
| 187 | /* |
| 188 | * the client's version string, passed by sshd2 in compat mode. if != NULL, |
| 189 | * sshd will skip the version-number exchange |
| 190 | */ |
| 191 | char *client_version_string = NULL; |
| 192 | char *server_version_string = NULL; |
| 193 | |
| 194 | /* for rekeying XXX fixme */ |
| 195 | Kex *xxx_kex; |
| 196 | |
| 197 | /* |
| 198 | * Any really sensitive data in the application is contained in this |
| 199 | * structure. The idea is that this structure could be locked into memory so |
| 200 | * that the pages do not get written into swap. However, there are some |
| 201 | * problems. The private key contains BIGNUMs, and we do not (in principle) |
| 202 | * have access to the internals of them, and locking just the structure is |
| 203 | * not very useful. Currently, memory locking is not implemented. |
| 204 | */ |
| 205 | struct { |
| 206 | Key *server_key; /* ephemeral server key */ |
| 207 | Key *ssh1_host_key; /* ssh1 host key */ |
| 208 | Key **host_keys; /* all private host keys */ |
| 209 | Key **host_certificates; /* all public host certificates */ |
| 210 | int have_ssh1_key; |
| 211 | int have_ssh2_key; |
| 212 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; |
| 213 | } sensitive_data; |
| 214 | |
| 215 | /* |
| 216 | * Flag indicating whether the RSA server key needs to be regenerated. |
| 217 | * Is set in the SIGALRM handler and cleared when the key is regenerated. |
| 218 | */ |
| 219 | static volatile sig_atomic_t key_do_regen = 0; |
| 220 | |
| 221 | /* This is set to true when a signal is received. */ |
| 222 | static volatile sig_atomic_t received_sighup = 0; |
| 223 | static volatile sig_atomic_t received_sigterm = 0; |
| 224 | |
| 225 | /* session identifier, used by RSA-auth */ |
| 226 | u_char session_id[16]; |
| 227 | |
| 228 | /* same for ssh2 */ |
| 229 | u_char *session_id2 = NULL; |
| 230 | u_int session_id2_len = 0; |
| 231 | |
| 232 | /* record remote hostname or ip */ |
| 233 | u_int utmp_len = MAXHOSTNAMELEN; |
| 234 | |
| 235 | /* options.max_startup sized array of fd ints */ |
| 236 | int *startup_pipes = NULL; |
| 237 | int startup_pipe; /* in child */ |
| 238 | |
| 239 | /* variables used for privilege separation */ |
| 240 | int use_privsep = -1; |
| 241 | struct monitor *pmonitor = NULL; |
| 242 | |
| 243 | /* global authentication context */ |
| 244 | Authctxt *the_authctxt = NULL; |
| 245 | |
| 246 | /* sshd_config buffer */ |
| 247 | Buffer cfg; |
| 248 | |
| 249 | /* message to be displayed after login */ |
| 250 | Buffer loginmsg; |
| 251 | |
| 252 | /* Unprivileged user */ |
| 253 | struct passwd *privsep_pw = NULL; |
| 254 | |
| 255 | /* Prototypes for various functions defined later in this file. */ |
| 256 | void destroy_sensitive_data(void); |
| 257 | void demote_sensitive_data(void); |
| 258 | |
| 259 | static void do_ssh1_kex(void); |
| 260 | static void do_ssh2_kex(void); |
| 261 | |
| 262 | /* |
| 263 | * Close all listening sockets |
| 264 | */ |
| 265 | static void |
| 266 | close_listen_socks(void) |
| 267 | { |
| 268 | int i; |
| 269 | |
| 270 | for (i = 0; i < num_listen_socks; i++) |
| 271 | close(listen_socks[i]); |
| 272 | num_listen_socks = -1; |
| 273 | } |
| 274 | |
| 275 | static void |
| 276 | close_startup_pipes(void) |
| 277 | { |
| 278 | int i; |
| 279 | |
| 280 | if (startup_pipes) |
| 281 | for (i = 0; i < options.max_startups; i++) |
| 282 | if (startup_pipes[i] != -1) |
| 283 | close(startup_pipes[i]); |
| 284 | } |
| 285 | |
| 286 | /* |
| 287 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; |
| 288 | * the effect is to reread the configuration file (and to regenerate |
| 289 | * the server key). |
| 290 | */ |
| 291 | |
| 292 | /*ARGSUSED*/ |
| 293 | static void |
| 294 | sighup_handler(int sig) |
| 295 | { |
| 296 | int save_errno = errno; |
| 297 | |
| 298 | received_sighup = 1; |
| 299 | signal(SIGHUP, sighup_handler); |
| 300 | errno = save_errno; |
| 301 | } |
| 302 | |
| 303 | /* |
| 304 | * Called from the main program after receiving SIGHUP. |
| 305 | * Restarts the server. |
| 306 | */ |
| 307 | static void |
| 308 | sighup_restart(void) |
| 309 | { |
| 310 | logit("Received SIGHUP; restarting."); |
| 311 | close_listen_socks(); |
| 312 | close_startup_pipes(); |
| 313 | alarm(0); /* alarm timer persists across exec */ |
| 314 | signal(SIGHUP, SIG_IGN); /* will be restored after exec */ |
| 315 | execv(saved_argv[0], saved_argv); |
| 316 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
| 317 | strerror(errno)); |
| 318 | exit(1); |
| 319 | } |
| 320 | |
| 321 | /* |
| 322 | * Generic signal handler for terminating signals in the master daemon. |
| 323 | */ |
| 324 | /*ARGSUSED*/ |
| 325 | static void |
| 326 | sigterm_handler(int sig) |
| 327 | { |
| 328 | received_sigterm = sig; |
| 329 | } |
| 330 | |
| 331 | /* |
| 332 | * SIGCHLD handler. This is called whenever a child dies. This will then |
| 333 | * reap any zombies left by exited children. |
| 334 | */ |
| 335 | /*ARGSUSED*/ |
| 336 | static void |
| 337 | main_sigchld_handler(int sig) |
| 338 | { |
| 339 | int save_errno = errno; |
| 340 | pid_t pid; |
| 341 | int status; |
| 342 | |
| 343 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
| 344 | (pid < 0 && errno == EINTR)) |
| 345 | ; |
| 346 | |
| 347 | signal(SIGCHLD, main_sigchld_handler); |
| 348 | errno = save_errno; |
| 349 | } |
| 350 | |
| 351 | /* |
| 352 | * Signal handler for the alarm after the login grace period has expired. |
| 353 | */ |
| 354 | /*ARGSUSED*/ |
| 355 | static void |
| 356 | grace_alarm_handler(int sig) |
| 357 | { |
| 358 | if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) |
| 359 | kill(pmonitor->m_pid, SIGALRM); |
| 360 | |
| 361 | /* Log error and exit. */ |
| 362 | sigdie("Timeout before authentication for %s", get_remote_ipaddr()); |
| 363 | } |
| 364 | |
| 365 | /* |
| 366 | * Signal handler for the key regeneration alarm. Note that this |
| 367 | * alarm only occurs in the daemon waiting for connections, and it does not |
| 368 | * do anything with the private key or random state before forking. |
| 369 | * Thus there should be no concurrency control/asynchronous execution |
| 370 | * problems. |
| 371 | */ |
| 372 | static void |
| 373 | generate_ephemeral_server_key(void) |
| 374 | { |
| 375 | verbose("Generating %s%d bit RSA key.", |
| 376 | sensitive_data.server_key ? "new " : "", options.server_key_bits); |
| 377 | if (sensitive_data.server_key != NULL) |
| 378 | key_free(sensitive_data.server_key); |
| 379 | sensitive_data.server_key = key_generate(KEY_RSA1, |
| 380 | options.server_key_bits); |
| 381 | verbose("RSA key generation complete."); |
| 382 | |
| 383 | arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); |
| 384 | arc4random_stir(); |
| 385 | } |
| 386 | |
| 387 | /*ARGSUSED*/ |
| 388 | static void |
| 389 | key_regeneration_alarm(int sig) |
| 390 | { |
| 391 | int save_errno = errno; |
| 392 | |
| 393 | signal(SIGALRM, SIG_DFL); |
| 394 | errno = save_errno; |
| 395 | key_do_regen = 1; |
| 396 | } |
| 397 | |
| 398 | static void |
| 399 | sshd_exchange_identification(int sock_in, int sock_out) |
| 400 | { |
| 401 | u_int i; |
| 402 | int mismatch; |
| 403 | int remote_major, remote_minor; |
| 404 | int major, minor; |
| 405 | char *s, *newline = "\n"; |
| 406 | char buf[256]; /* Must not be larger than remote_version. */ |
| 407 | char remote_version[256]; /* Must be at least as big as buf. */ |
| 408 | |
| 409 | if ((options.protocol & SSH_PROTO_1) && |
| 410 | (options.protocol & SSH_PROTO_2)) { |
| 411 | major = PROTOCOL_MAJOR_1; |
| 412 | minor = 99; |
| 413 | } else if (options.protocol & SSH_PROTO_2) { |
| 414 | major = PROTOCOL_MAJOR_2; |
| 415 | minor = PROTOCOL_MINOR_2; |
| 416 | newline = "\r\n"; |
| 417 | } else { |
| 418 | major = PROTOCOL_MAJOR_1; |
| 419 | minor = PROTOCOL_MINOR_1; |
| 420 | } |
| 421 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, |
| 422 | SSH_VERSION, newline); |
| 423 | server_version_string = xstrdup(buf); |
| 424 | |
| 425 | /* Send our protocol version identification. */ |
| 426 | if (roaming_atomicio(vwrite, sock_out, server_version_string, |
| 427 | strlen(server_version_string)) |
| 428 | != strlen(server_version_string)) { |
| 429 | logit("Could not write ident string to %s", get_remote_ipaddr()); |
| 430 | cleanup_exit(255); |
| 431 | } |
| 432 | |
| 433 | /* Read other sides version identification. */ |
| 434 | memset(buf, 0, sizeof(buf)); |
| 435 | for (i = 0; i < sizeof(buf) - 1; i++) { |
| 436 | if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { |
| 437 | logit("Did not receive identification string from %s", |
| 438 | get_remote_ipaddr()); |
| 439 | cleanup_exit(255); |
| 440 | } |
| 441 | if (buf[i] == '\r') { |
| 442 | buf[i] = 0; |
| 443 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
| 444 | if (i == 12 && |
| 445 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) |
| 446 | break; |
| 447 | continue; |
| 448 | } |
| 449 | if (buf[i] == '\n') { |
| 450 | buf[i] = 0; |
| 451 | break; |
| 452 | } |
| 453 | } |
| 454 | buf[sizeof(buf) - 1] = 0; |
| 455 | client_version_string = xstrdup(buf); |
| 456 | |
| 457 | /* |
| 458 | * Check that the versions match. In future this might accept |
| 459 | * several versions and set appropriate flags to handle them. |
| 460 | */ |
| 461 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", |
| 462 | &remote_major, &remote_minor, remote_version) != 3) { |
| 463 | s = "Protocol mismatch.\n"; |
| 464 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
| 465 | close(sock_in); |
| 466 | close(sock_out); |
| 467 | logit("Bad protocol version identification '%.100s' from %s", |
| 468 | client_version_string, get_remote_ipaddr()); |
| 469 | cleanup_exit(255); |
| 470 | } |
| 471 | debug("Client protocol version %d.%d; client software version %.100s", |
| 472 | remote_major, remote_minor, remote_version); |
| 473 | |
| 474 | compat_datafellows(remote_version); |
| 475 | |
| 476 | if (datafellows & SSH_BUG_PROBE) { |
| 477 | logit("probed from %s with %s. Don't panic.", |
| 478 | get_remote_ipaddr(), client_version_string); |
| 479 | cleanup_exit(255); |
| 480 | } |
| 481 | |
| 482 | if (datafellows & SSH_BUG_SCANNER) { |
| 483 | logit("scanned from %s with %s. Don't panic.", |
| 484 | get_remote_ipaddr(), client_version_string); |
| 485 | cleanup_exit(255); |
| 486 | } |
| 487 | |
| 488 | mismatch = 0; |
| 489 | switch (remote_major) { |
| 490 | case 1: |
| 491 | if (remote_minor == 99) { |
| 492 | if (options.protocol & SSH_PROTO_2) |
| 493 | enable_compat20(); |
| 494 | else |
| 495 | mismatch = 1; |
| 496 | break; |
| 497 | } |
| 498 | if (!(options.protocol & SSH_PROTO_1)) { |
| 499 | mismatch = 1; |
| 500 | break; |
| 501 | } |
| 502 | if (remote_minor < 3) { |
| 503 | packet_disconnect("Your ssh version is too old and " |
| 504 | "is no longer supported. Please install a newer version."); |
| 505 | } else if (remote_minor == 3) { |
| 506 | /* note that this disables agent-forwarding */ |
| 507 | enable_compat13(); |
| 508 | } |
| 509 | break; |
| 510 | case 2: |
| 511 | if (options.protocol & SSH_PROTO_2) { |
| 512 | enable_compat20(); |
| 513 | break; |
| 514 | } |
| 515 | /* FALLTHROUGH */ |
| 516 | default: |
| 517 | mismatch = 1; |
| 518 | break; |
| 519 | } |
| 520 | chop(server_version_string); |
| 521 | debug("Local version string %.200s", server_version_string); |
| 522 | |
| 523 | if (mismatch) { |
| 524 | s = "Protocol major versions differ.\n"; |
| 525 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
| 526 | close(sock_in); |
| 527 | close(sock_out); |
| 528 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", |
| 529 | get_remote_ipaddr(), |
| 530 | server_version_string, client_version_string); |
| 531 | cleanup_exit(255); |
| 532 | } |
| 533 | } |
| 534 | |
| 535 | /* Destroy the host and server keys. They will no longer be needed. */ |
| 536 | void |
| 537 | destroy_sensitive_data(void) |
| 538 | { |
| 539 | int i; |
| 540 | |
| 541 | if (sensitive_data.server_key) { |
| 542 | key_free(sensitive_data.server_key); |
| 543 | sensitive_data.server_key = NULL; |
| 544 | } |
| 545 | for (i = 0; i < options.num_host_key_files; i++) { |
| 546 | if (sensitive_data.host_keys[i]) { |
| 547 | key_free(sensitive_data.host_keys[i]); |
| 548 | sensitive_data.host_keys[i] = NULL; |
| 549 | } |
| 550 | if (sensitive_data.host_certificates[i]) { |
| 551 | key_free(sensitive_data.host_certificates[i]); |
| 552 | sensitive_data.host_certificates[i] = NULL; |
| 553 | } |
| 554 | } |
| 555 | sensitive_data.ssh1_host_key = NULL; |
| 556 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); |
| 557 | } |
| 558 | |
| 559 | /* Demote private to public keys for network child */ |
| 560 | void |
| 561 | demote_sensitive_data(void) |
| 562 | { |
| 563 | Key *tmp; |
| 564 | int i; |
| 565 | |
| 566 | if (sensitive_data.server_key) { |
| 567 | tmp = key_demote(sensitive_data.server_key); |
| 568 | key_free(sensitive_data.server_key); |
| 569 | sensitive_data.server_key = tmp; |
| 570 | } |
| 571 | |
| 572 | for (i = 0; i < options.num_host_key_files; i++) { |
| 573 | if (sensitive_data.host_keys[i]) { |
| 574 | tmp = key_demote(sensitive_data.host_keys[i]); |
| 575 | key_free(sensitive_data.host_keys[i]); |
| 576 | sensitive_data.host_keys[i] = tmp; |
| 577 | if (tmp->type == KEY_RSA1) |
| 578 | sensitive_data.ssh1_host_key = tmp; |
| 579 | } |
| 580 | /* Certs do not need demotion */ |
| 581 | } |
| 582 | |
| 583 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ |
| 584 | } |
| 585 | |
| 586 | static void |
| 587 | privsep_preauth_child(void) |
| 588 | { |
| 589 | u_int32_t rnd[256]; |
| 590 | gid_t gidset[1]; |
| 591 | |
| 592 | /* Enable challenge-response authentication for privilege separation */ |
| 593 | privsep_challenge_enable(); |
| 594 | |
| 595 | arc4random_stir(); |
| 596 | arc4random_buf(rnd, sizeof(rnd)); |
| 597 | RAND_seed(rnd, sizeof(rnd)); |
| 598 | |
| 599 | /* Demote the private keys to public keys. */ |
| 600 | demote_sensitive_data(); |
| 601 | |
| 602 | /* Change our root directory */ |
| 603 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
| 604 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, |
| 605 | strerror(errno)); |
| 606 | if (chdir("/") == -1) |
| 607 | fatal("chdir(\"/\"): %s", strerror(errno)); |
| 608 | |
| 609 | /* Drop our privileges */ |
| 610 | debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, |
| 611 | (u_int)privsep_pw->pw_gid); |
| 612 | #if 0 |
| 613 | /* XXX not ready, too heavy after chroot */ |
| 614 | do_setusercontext(privsep_pw); |
| 615 | #else |
| 616 | gidset[0] = privsep_pw->pw_gid; |
| 617 | if (setgroups(1, gidset) < 0) |
| 618 | fatal("setgroups: %.100s", strerror(errno)); |
| 619 | permanently_set_uid(privsep_pw); |
| 620 | #endif |
| 621 | } |
| 622 | |
| 623 | static int |
| 624 | privsep_preauth(Authctxt *authctxt) |
| 625 | { |
| 626 | int status; |
| 627 | pid_t pid; |
| 628 | struct ssh_sandbox *box = NULL; |
| 629 | |
| 630 | /* Set up unprivileged child process to deal with network data */ |
| 631 | pmonitor = monitor_init(); |
| 632 | /* Store a pointer to the kex for later rekeying */ |
| 633 | pmonitor->m_pkex = &xxx_kex; |
| 634 | |
| 635 | if (use_privsep == PRIVSEP_SANDBOX) |
| 636 | box = ssh_sandbox_init(); |
| 637 | pid = fork(); |
| 638 | if (pid == -1) { |
| 639 | fatal("fork of unprivileged child failed"); |
| 640 | } else if (pid != 0) { |
| 641 | debug2("Network child is on pid %ld", (long)pid); |
| 642 | |
| 643 | if (box != NULL) |
| 644 | ssh_sandbox_parent_preauth(box, pid); |
| 645 | pmonitor->m_pid = pid; |
| 646 | monitor_child_preauth(authctxt, pmonitor); |
| 647 | |
| 648 | /* Sync memory */ |
| 649 | monitor_sync(pmonitor); |
| 650 | |
| 651 | /* Wait for the child's exit status */ |
| 652 | while (waitpid(pid, &status, 0) < 0) { |
| 653 | if (errno != EINTR) |
| 654 | fatal("%s: waitpid: %s", __func__, |
| 655 | strerror(errno)); |
| 656 | } |
| 657 | if (WIFEXITED(status)) { |
| 658 | if (WEXITSTATUS(status) != 0) |
| 659 | fatal("%s: preauth child exited with status %d", |
| 660 | __func__, WEXITSTATUS(status)); |
| 661 | } else if (WIFSIGNALED(status)) |
| 662 | fatal("%s: preauth child terminated by signal %d", |
| 663 | __func__, WTERMSIG(status)); |
| 664 | if (box != NULL) |
| 665 | ssh_sandbox_parent_finish(box); |
| 666 | return 1; |
| 667 | } else { |
| 668 | /* child */ |
| 669 | close(pmonitor->m_sendfd); |
| 670 | close(pmonitor->m_log_recvfd); |
| 671 | |
| 672 | /* Arrange for logging to be sent to the monitor */ |
| 673 | set_log_handler(mm_log_handler, pmonitor); |
| 674 | |
| 675 | /* Demote the child */ |
| 676 | if (getuid() == 0 || geteuid() == 0) |
| 677 | privsep_preauth_child(); |
| 678 | setproctitle("%s", "[net]"); |
| 679 | if (box != NULL) |
| 680 | ssh_sandbox_child(box); |
| 681 | |
| 682 | return 0; |
| 683 | } |
| 684 | } |
| 685 | |
| 686 | static void |
| 687 | privsep_postauth(Authctxt *authctxt) |
| 688 | { |
| 689 | u_int32_t rnd[256]; |
| 690 | |
| 691 | #ifdef DISABLE_FD_PASSING |
| 692 | if (1) { |
| 693 | #else |
| 694 | if (authctxt->pw->pw_uid == 0 || options.use_login) { |
| 695 | #endif |
| 696 | /* File descriptor passing is broken or root login */ |
| 697 | use_privsep = 0; |
| 698 | goto skip; |
| 699 | } |
| 700 | |
| 701 | /* New socket pair */ |
| 702 | monitor_reinit(pmonitor); |
| 703 | |
| 704 | pmonitor->m_pid = fork(); |
| 705 | if (pmonitor->m_pid == -1) |
| 706 | fatal("fork of unprivileged child failed"); |
| 707 | else if (pmonitor->m_pid != 0) { |
| 708 | verbose("User child is on pid %ld", (long)pmonitor->m_pid); |
| 709 | buffer_clear(&loginmsg); |
| 710 | monitor_child_postauth(pmonitor); |
| 711 | |
| 712 | /* NEVERREACHED */ |
| 713 | exit(0); |
| 714 | } |
| 715 | |
| 716 | /* child */ |
| 717 | |
| 718 | close(pmonitor->m_sendfd); |
| 719 | pmonitor->m_sendfd = -1; |
| 720 | |
| 721 | /* Demote the private keys to public keys. */ |
| 722 | demote_sensitive_data(); |
| 723 | |
| 724 | arc4random_stir(); |
| 725 | arc4random_buf(rnd, sizeof(rnd)); |
| 726 | RAND_seed(rnd, sizeof(rnd)); |
| 727 | |
| 728 | /* Drop privileges */ |
| 729 | do_setusercontext(authctxt->pw); |
| 730 | |
| 731 | skip: |
| 732 | /* It is safe now to apply the key state */ |
| 733 | monitor_apply_keystate(pmonitor); |
| 734 | |
| 735 | /* |
| 736 | * Tell the packet layer that authentication was successful, since |
| 737 | * this information is not part of the key state. |
| 738 | */ |
| 739 | packet_set_authenticated(); |
| 740 | } |
| 741 | |
| 742 | static char * |
| 743 | list_hostkey_types(void) |
| 744 | { |
| 745 | Buffer b; |
| 746 | const char *p; |
| 747 | char *ret; |
| 748 | int i; |
| 749 | Key *key; |
| 750 | |
| 751 | buffer_init(&b); |
| 752 | for (i = 0; i < options.num_host_key_files; i++) { |
| 753 | key = sensitive_data.host_keys[i]; |
| 754 | if (key == NULL) |
| 755 | continue; |
| 756 | switch (key->type) { |
| 757 | case KEY_RSA: |
| 758 | case KEY_DSA: |
| 759 | case KEY_ECDSA: |
| 760 | if (buffer_len(&b) > 0) |
| 761 | buffer_append(&b, ",", 1); |
| 762 | p = key_ssh_name(key); |
| 763 | buffer_append(&b, p, strlen(p)); |
| 764 | break; |
| 765 | } |
| 766 | /* If the private key has a cert peer, then list that too */ |
| 767 | key = sensitive_data.host_certificates[i]; |
| 768 | if (key == NULL) |
| 769 | continue; |
| 770 | switch (key->type) { |
| 771 | case KEY_RSA_CERT_V00: |
| 772 | case KEY_DSA_CERT_V00: |
| 773 | case KEY_RSA_CERT: |
| 774 | case KEY_DSA_CERT: |
| 775 | case KEY_ECDSA_CERT: |
| 776 | if (buffer_len(&b) > 0) |
| 777 | buffer_append(&b, ",", 1); |
| 778 | p = key_ssh_name(key); |
| 779 | buffer_append(&b, p, strlen(p)); |
| 780 | break; |
| 781 | } |
| 782 | } |
| 783 | buffer_append(&b, "\0", 1); |
| 784 | ret = xstrdup(buffer_ptr(&b)); |
| 785 | buffer_free(&b); |
| 786 | debug("list_hostkey_types: %s", ret); |
| 787 | return ret; |
| 788 | } |
| 789 | |
| 790 | static Key * |
| 791 | get_hostkey_by_type(int type, int need_private) |
| 792 | { |
| 793 | int i; |
| 794 | Key *key; |
| 795 | |
| 796 | for (i = 0; i < options.num_host_key_files; i++) { |
| 797 | switch (type) { |
| 798 | case KEY_RSA_CERT_V00: |
| 799 | case KEY_DSA_CERT_V00: |
| 800 | case KEY_RSA_CERT: |
| 801 | case KEY_DSA_CERT: |
| 802 | case KEY_ECDSA_CERT: |
| 803 | key = sensitive_data.host_certificates[i]; |
| 804 | break; |
| 805 | default: |
| 806 | key = sensitive_data.host_keys[i]; |
| 807 | break; |
| 808 | } |
| 809 | if (key != NULL && key->type == type) |
| 810 | return need_private ? |
| 811 | sensitive_data.host_keys[i] : key; |
| 812 | } |
| 813 | return NULL; |
| 814 | } |
| 815 | |
| 816 | Key * |
| 817 | get_hostkey_public_by_type(int type) |
| 818 | { |
| 819 | return get_hostkey_by_type(type, 0); |
| 820 | } |
| 821 | |
| 822 | Key * |
| 823 | get_hostkey_private_by_type(int type) |
| 824 | { |
| 825 | return get_hostkey_by_type(type, 1); |
| 826 | } |
| 827 | |
| 828 | Key * |
| 829 | get_hostkey_by_index(int ind) |
| 830 | { |
| 831 | if (ind < 0 || ind >= options.num_host_key_files) |
| 832 | return (NULL); |
| 833 | return (sensitive_data.host_keys[ind]); |
| 834 | } |
| 835 | |
| 836 | int |
| 837 | get_hostkey_index(Key *key) |
| 838 | { |
| 839 | int i; |
| 840 | |
| 841 | for (i = 0; i < options.num_host_key_files; i++) { |
| 842 | if (key_is_cert(key)) { |
| 843 | if (key == sensitive_data.host_certificates[i]) |
| 844 | return (i); |
| 845 | } else { |
| 846 | if (key == sensitive_data.host_keys[i]) |
| 847 | return (i); |
| 848 | } |
| 849 | } |
| 850 | return (-1); |
| 851 | } |
| 852 | |
| 853 | /* |
| 854 | * returns 1 if connection should be dropped, 0 otherwise. |
| 855 | * dropping starts at connection #max_startups_begin with a probability |
| 856 | * of (max_startups_rate/100). the probability increases linearly until |
| 857 | * all connections are dropped for startups > max_startups |
| 858 | */ |
| 859 | static int |
| 860 | drop_connection(int startups) |
| 861 | { |
| 862 | int p, r; |
| 863 | |
| 864 | if (startups < options.max_startups_begin) |
| 865 | return 0; |
| 866 | if (startups >= options.max_startups) |
| 867 | return 1; |
| 868 | if (options.max_startups_rate == 100) |
| 869 | return 1; |
| 870 | |
| 871 | p = 100 - options.max_startups_rate; |
| 872 | p *= startups - options.max_startups_begin; |
| 873 | p /= options.max_startups - options.max_startups_begin; |
| 874 | p += options.max_startups_rate; |
| 875 | r = arc4random_uniform(100); |
| 876 | |
| 877 | debug("drop_connection: p %d, r %d", p, r); |
| 878 | return (r < p) ? 1 : 0; |
| 879 | } |
| 880 | |
| 881 | static void |
| 882 | usage(void) |
| 883 | { |
| 884 | fprintf(stderr, "%s, %s\n", |
| 885 | SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); |
| 886 | fprintf(stderr, |
| 887 | "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" |
| 888 | " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" |
| 889 | " [-k key_gen_time] [-o option] [-p port] [-u len]\n" |
| 890 | ); |
| 891 | exit(1); |
| 892 | } |
| 893 | |
| 894 | static void |
| 895 | send_rexec_state(int fd, Buffer *conf) |
| 896 | { |
| 897 | Buffer m; |
| 898 | |
| 899 | debug3("%s: entering fd = %d config len %d", __func__, fd, |
| 900 | buffer_len(conf)); |
| 901 | |
| 902 | /* |
| 903 | * Protocol from reexec master to child: |
| 904 | * string configuration |
| 905 | * u_int ephemeral_key_follows |
| 906 | * bignum e (only if ephemeral_key_follows == 1) |
| 907 | * bignum n " |
| 908 | * bignum d " |
| 909 | * bignum iqmp " |
| 910 | * bignum p " |
| 911 | * bignum q " |
| 912 | * string rngseed (only if OpenSSL is not self-seeded) |
| 913 | */ |
| 914 | buffer_init(&m); |
| 915 | buffer_put_cstring(&m, buffer_ptr(conf)); |
| 916 | |
| 917 | if (sensitive_data.server_key != NULL && |
| 918 | sensitive_data.server_key->type == KEY_RSA1) { |
| 919 | buffer_put_int(&m, 1); |
| 920 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); |
| 921 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); |
| 922 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); |
| 923 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); |
| 924 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); |
| 925 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); |
| 926 | } else |
| 927 | buffer_put_int(&m, 0); |
| 928 | |
| 929 | #ifndef OPENSSL_PRNG_ONLY |
| 930 | rexec_send_rng_seed(&m); |
| 931 | #endif |
| 932 | |
| 933 | if (ssh_msg_send(fd, 0, &m) == -1) |
| 934 | fatal("%s: ssh_msg_send failed", __func__); |
| 935 | |
| 936 | buffer_free(&m); |
| 937 | |
| 938 | debug3("%s: done", __func__); |
| 939 | } |
| 940 | |
| 941 | static void |
| 942 | recv_rexec_state(int fd, Buffer *conf) |
| 943 | { |
| 944 | Buffer m; |
| 945 | char *cp; |
| 946 | u_int len; |
| 947 | |
| 948 | debug3("%s: entering fd = %d", __func__, fd); |
| 949 | |
| 950 | buffer_init(&m); |
| 951 | |
| 952 | if (ssh_msg_recv(fd, &m) == -1) |
| 953 | fatal("%s: ssh_msg_recv failed", __func__); |
| 954 | if (buffer_get_char(&m) != 0) |
| 955 | fatal("%s: rexec version mismatch", __func__); |
| 956 | |
| 957 | cp = buffer_get_string(&m, &len); |
| 958 | if (conf != NULL) |
| 959 | buffer_append(conf, cp, len + 1); |
| 960 | xfree(cp); |
| 961 | |
| 962 | if (buffer_get_int(&m)) { |
| 963 | if (sensitive_data.server_key != NULL) |
| 964 | key_free(sensitive_data.server_key); |
| 965 | sensitive_data.server_key = key_new_private(KEY_RSA1); |
| 966 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); |
| 967 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); |
| 968 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); |
| 969 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); |
| 970 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); |
| 971 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); |
| 972 | rsa_generate_additional_parameters( |
| 973 | sensitive_data.server_key->rsa); |
| 974 | } |
| 975 | |
| 976 | #ifndef OPENSSL_PRNG_ONLY |
| 977 | rexec_recv_rng_seed(&m); |
| 978 | #endif |
| 979 | |
| 980 | buffer_free(&m); |
| 981 | |
| 982 | debug3("%s: done", __func__); |
| 983 | } |
| 984 | |
| 985 | /* Accept a connection from inetd */ |
| 986 | static void |
| 987 | server_accept_inetd(int *sock_in, int *sock_out) |
| 988 | { |
| 989 | int fd; |
| 990 | |
| 991 | startup_pipe = -1; |
| 992 | if (rexeced_flag) { |
| 993 | close(REEXEC_CONFIG_PASS_FD); |
| 994 | *sock_in = *sock_out = dup(STDIN_FILENO); |
| 995 | if (!debug_flag) { |
| 996 | startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); |
| 997 | close(REEXEC_STARTUP_PIPE_FD); |
| 998 | } |
| 999 | } else { |
| 1000 | *sock_in = dup(STDIN_FILENO); |
| 1001 | *sock_out = dup(STDOUT_FILENO); |
| 1002 | } |
| 1003 | /* |
| 1004 | * We intentionally do not close the descriptors 0, 1, and 2 |
| 1005 | * as our code for setting the descriptors won't work if |
| 1006 | * ttyfd happens to be one of those. |
| 1007 | */ |
| 1008 | if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { |
| 1009 | dup2(fd, STDIN_FILENO); |
| 1010 | dup2(fd, STDOUT_FILENO); |
| 1011 | if (fd > STDOUT_FILENO) |
| 1012 | close(fd); |
| 1013 | } |
| 1014 | debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); |
| 1015 | } |
| 1016 | |
| 1017 | /* |
| 1018 | * Listen for TCP connections |
| 1019 | */ |
| 1020 | static void |
| 1021 | server_listen(void) |
| 1022 | { |
| 1023 | int ret, listen_sock, on = 1; |
| 1024 | struct addrinfo *ai; |
| 1025 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
| 1026 | |
| 1027 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
| 1028 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) |
| 1029 | continue; |
| 1030 | if (num_listen_socks >= MAX_LISTEN_SOCKS) |
| 1031 | fatal("Too many listen sockets. " |
| 1032 | "Enlarge MAX_LISTEN_SOCKS"); |
| 1033 | if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, |
| 1034 | ntop, sizeof(ntop), strport, sizeof(strport), |
| 1035 | NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { |
| 1036 | error("getnameinfo failed: %.100s", |
| 1037 | ssh_gai_strerror(ret)); |
| 1038 | continue; |
| 1039 | } |
| 1040 | /* Create socket for listening. */ |
| 1041 | listen_sock = socket(ai->ai_family, ai->ai_socktype, |
| 1042 | ai->ai_protocol); |
| 1043 | if (listen_sock < 0) { |
| 1044 | /* kernel may not support ipv6 */ |
| 1045 | verbose("socket: %.100s", strerror(errno)); |
| 1046 | continue; |
| 1047 | } |
| 1048 | if (set_nonblock(listen_sock) == -1) { |
| 1049 | close(listen_sock); |
| 1050 | continue; |
| 1051 | } |
| 1052 | /* |
| 1053 | * Set socket options. |
| 1054 | * Allow local port reuse in TIME_WAIT. |
| 1055 | */ |
| 1056 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, |
| 1057 | &on, sizeof(on)) == -1) |
| 1058 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); |
| 1059 | |
| 1060 | /* Only communicate in IPv6 over AF_INET6 sockets. */ |
| 1061 | if (ai->ai_family == AF_INET6) |
| 1062 | sock_set_v6only(listen_sock); |
| 1063 | |
| 1064 | debug("Bind to port %s on %s.", strport, ntop); |
| 1065 | |
| 1066 | /* Bind the socket to the desired port. */ |
| 1067 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
| 1068 | error("Bind to port %s on %s failed: %.200s.", |
| 1069 | strport, ntop, strerror(errno)); |
| 1070 | close(listen_sock); |
| 1071 | continue; |
| 1072 | } |
| 1073 | listen_socks[num_listen_socks] = listen_sock; |
| 1074 | num_listen_socks++; |
| 1075 | |
| 1076 | /* Start listening on the port. */ |
| 1077 | if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) |
| 1078 | fatal("listen on [%s]:%s: %.100s", |
| 1079 | ntop, strport, strerror(errno)); |
| 1080 | logit("Server listening on %s port %s.", ntop, strport); |
| 1081 | } |
| 1082 | freeaddrinfo(options.listen_addrs); |
| 1083 | |
| 1084 | if (!num_listen_socks) |
| 1085 | fatal("Cannot bind any address."); |
| 1086 | } |
| 1087 | |
| 1088 | /* |
| 1089 | * The main TCP accept loop. Note that, for the non-debug case, returns |
| 1090 | * from this function are in a forked subprocess. |
| 1091 | */ |
| 1092 | static void |
| 1093 | server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) |
| 1094 | { |
| 1095 | fd_set *fdset; |
| 1096 | int i, j, ret, maxfd; |
| 1097 | int key_used = 0, startups = 0; |
| 1098 | int startup_p[2] = { -1 , -1 }; |
| 1099 | struct sockaddr_storage from; |
| 1100 | socklen_t fromlen; |
| 1101 | pid_t pid; |
| 1102 | |
| 1103 | /* setup fd set for accept */ |
| 1104 | fdset = NULL; |
| 1105 | maxfd = 0; |
| 1106 | for (i = 0; i < num_listen_socks; i++) |
| 1107 | if (listen_socks[i] > maxfd) |
| 1108 | maxfd = listen_socks[i]; |
| 1109 | /* pipes connected to unauthenticated childs */ |
| 1110 | startup_pipes = xcalloc(options.max_startups, sizeof(int)); |
| 1111 | for (i = 0; i < options.max_startups; i++) |
| 1112 | startup_pipes[i] = -1; |
| 1113 | |
| 1114 | /* |
| 1115 | * Stay listening for connections until the system crashes or |
| 1116 | * the daemon is killed with a signal. |
| 1117 | */ |
| 1118 | for (;;) { |
| 1119 | if (received_sighup) |
| 1120 | sighup_restart(); |
| 1121 | if (fdset != NULL) |
| 1122 | xfree(fdset); |
| 1123 | fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), |
| 1124 | sizeof(fd_mask)); |
| 1125 | |
| 1126 | for (i = 0; i < num_listen_socks; i++) |
| 1127 | FD_SET(listen_socks[i], fdset); |
| 1128 | for (i = 0; i < options.max_startups; i++) |
| 1129 | if (startup_pipes[i] != -1) |
| 1130 | FD_SET(startup_pipes[i], fdset); |
| 1131 | |
| 1132 | /* Wait in select until there is a connection. */ |
| 1133 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
| 1134 | if (ret < 0 && errno != EINTR) |
| 1135 | error("select: %.100s", strerror(errno)); |
| 1136 | if (received_sigterm) { |
| 1137 | logit("Received signal %d; terminating.", |
| 1138 | (int) received_sigterm); |
| 1139 | close_listen_socks(); |
| 1140 | unlink(options.pid_file); |
| 1141 | exit(received_sigterm == SIGTERM ? 0 : 255); |
| 1142 | } |
| 1143 | if (key_used && key_do_regen) { |
| 1144 | generate_ephemeral_server_key(); |
| 1145 | key_used = 0; |
| 1146 | key_do_regen = 0; |
| 1147 | } |
| 1148 | if (ret < 0) |
| 1149 | continue; |
| 1150 | |
| 1151 | for (i = 0; i < options.max_startups; i++) |
| 1152 | if (startup_pipes[i] != -1 && |
| 1153 | FD_ISSET(startup_pipes[i], fdset)) { |
| 1154 | /* |
| 1155 | * the read end of the pipe is ready |
| 1156 | * if the child has closed the pipe |
| 1157 | * after successful authentication |
| 1158 | * or if the child has died |
| 1159 | */ |
| 1160 | close(startup_pipes[i]); |
| 1161 | startup_pipes[i] = -1; |
| 1162 | startups--; |
| 1163 | } |
| 1164 | for (i = 0; i < num_listen_socks; i++) { |
| 1165 | if (!FD_ISSET(listen_socks[i], fdset)) |
| 1166 | continue; |
| 1167 | fromlen = sizeof(from); |
| 1168 | *newsock = accept(listen_socks[i], |
| 1169 | (struct sockaddr *)&from, &fromlen); |
| 1170 | if (*newsock < 0) { |
| 1171 | if (errno != EINTR && errno != EAGAIN && |
| 1172 | errno != EWOULDBLOCK) |
| 1173 | error("accept: %.100s", strerror(errno)); |
| 1174 | continue; |
| 1175 | } |
| 1176 | if (unset_nonblock(*newsock) == -1) { |
| 1177 | close(*newsock); |
| 1178 | continue; |
| 1179 | } |
| 1180 | if (drop_connection(startups) == 1) { |
| 1181 | debug("drop connection #%d", startups); |
| 1182 | close(*newsock); |
| 1183 | continue; |
| 1184 | } |
| 1185 | if (pipe(startup_p) == -1) { |
| 1186 | close(*newsock); |
| 1187 | continue; |
| 1188 | } |
| 1189 | |
| 1190 | if (rexec_flag && socketpair(AF_UNIX, |
| 1191 | SOCK_STREAM, 0, config_s) == -1) { |
| 1192 | error("reexec socketpair: %s", |
| 1193 | strerror(errno)); |
| 1194 | close(*newsock); |
| 1195 | close(startup_p[0]); |
| 1196 | close(startup_p[1]); |
| 1197 | continue; |
| 1198 | } |
| 1199 | |
| 1200 | for (j = 0; j < options.max_startups; j++) |
| 1201 | if (startup_pipes[j] == -1) { |
| 1202 | startup_pipes[j] = startup_p[0]; |
| 1203 | if (maxfd < startup_p[0]) |
| 1204 | maxfd = startup_p[0]; |
| 1205 | startups++; |
| 1206 | break; |
| 1207 | } |
| 1208 | |
| 1209 | /* |
| 1210 | * Got connection. Fork a child to handle it, unless |
| 1211 | * we are in debugging mode. |
| 1212 | */ |
| 1213 | if (debug_flag) { |
| 1214 | /* |
| 1215 | * In debugging mode. Close the listening |
| 1216 | * socket, and start processing the |
| 1217 | * connection without forking. |
| 1218 | */ |
| 1219 | debug("Server will not fork when running in debugging mode."); |
| 1220 | close_listen_socks(); |
| 1221 | *sock_in = *newsock; |
| 1222 | *sock_out = *newsock; |
| 1223 | close(startup_p[0]); |
| 1224 | close(startup_p[1]); |
| 1225 | startup_pipe = -1; |
| 1226 | pid = getpid(); |
| 1227 | if (rexec_flag) { |
| 1228 | send_rexec_state(config_s[0], |
| 1229 | &cfg); |
| 1230 | close(config_s[0]); |
| 1231 | } |
| 1232 | break; |
| 1233 | } |
| 1234 | |
| 1235 | /* |
| 1236 | * Normal production daemon. Fork, and have |
| 1237 | * the child process the connection. The |
| 1238 | * parent continues listening. |
| 1239 | */ |
| 1240 | platform_pre_fork(); |
| 1241 | if ((pid = fork()) == 0) { |
| 1242 | /* |
| 1243 | * Child. Close the listening and |
| 1244 | * max_startup sockets. Start using |
| 1245 | * the accepted socket. Reinitialize |
| 1246 | * logging (since our pid has changed). |
| 1247 | * We break out of the loop to handle |
| 1248 | * the connection. |
| 1249 | */ |
| 1250 | platform_post_fork_child(); |
| 1251 | startup_pipe = startup_p[1]; |
| 1252 | close_startup_pipes(); |
| 1253 | close_listen_socks(); |
| 1254 | *sock_in = *newsock; |
| 1255 | *sock_out = *newsock; |
| 1256 | log_init(__progname, |
| 1257 | options.log_level, |
| 1258 | options.log_facility, |
| 1259 | log_stderr); |
| 1260 | if (rexec_flag) |
| 1261 | close(config_s[0]); |
| 1262 | break; |
| 1263 | } |
| 1264 | |
| 1265 | /* Parent. Stay in the loop. */ |
| 1266 | platform_post_fork_parent(pid); |
| 1267 | if (pid < 0) |
| 1268 | error("fork: %.100s", strerror(errno)); |
| 1269 | else |
| 1270 | debug("Forked child %ld.", (long)pid); |
| 1271 | |
| 1272 | close(startup_p[1]); |
| 1273 | |
| 1274 | if (rexec_flag) { |
| 1275 | send_rexec_state(config_s[0], &cfg); |
| 1276 | close(config_s[0]); |
| 1277 | close(config_s[1]); |
| 1278 | } |
| 1279 | |
| 1280 | /* |
| 1281 | * Mark that the key has been used (it |
| 1282 | * was "given" to the child). |
| 1283 | */ |
| 1284 | if ((options.protocol & SSH_PROTO_1) && |
| 1285 | key_used == 0) { |
| 1286 | /* Schedule server key regeneration alarm. */ |
| 1287 | signal(SIGALRM, key_regeneration_alarm); |
| 1288 | alarm(options.key_regeneration_time); |
| 1289 | key_used = 1; |
| 1290 | } |
| 1291 | |
| 1292 | close(*newsock); |
| 1293 | |
| 1294 | /* |
| 1295 | * Ensure that our random state differs |
| 1296 | * from that of the child |
| 1297 | */ |
| 1298 | arc4random_stir(); |
| 1299 | } |
| 1300 | |
| 1301 | /* child process check (or debug mode) */ |
| 1302 | if (num_listen_socks < 0) |
| 1303 | break; |
| 1304 | } |
| 1305 | } |
| 1306 | |
| 1307 | |
| 1308 | /* |
| 1309 | * Main program for the daemon. |
| 1310 | */ |
| 1311 | int |
| 1312 | main(int ac, char **av) |
| 1313 | { |
| 1314 | extern char *optarg; |
| 1315 | extern int optind; |
| 1316 | int opt, i, j, on = 1; |
| 1317 | int sock_in = -1, sock_out = -1, newsock = -1; |
| 1318 | const char *remote_ip; |
| 1319 | char *test_user = NULL, *test_host = NULL, *test_addr = NULL; |
| 1320 | int remote_port; |
| 1321 | char *line, *p, *cp; |
| 1322 | int config_s[2] = { -1 , -1 }; |
| 1323 | u_int64_t ibytes, obytes; |
| 1324 | mode_t new_umask; |
| 1325 | Key *key; |
| 1326 | Authctxt *authctxt; |
| 1327 | |
| 1328 | #ifdef HAVE_SECUREWARE |
| 1329 | (void)set_auth_parameters(ac, av); |
| 1330 | #endif |
| 1331 | __progname = ssh_get_progname(av[0]); |
| 1332 | |
| 1333 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ |
| 1334 | saved_argc = ac; |
| 1335 | rexec_argc = ac; |
| 1336 | saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); |
| 1337 | for (i = 0; i < ac; i++) |
| 1338 | saved_argv[i] = xstrdup(av[i]); |
| 1339 | saved_argv[i] = NULL; |
| 1340 | |
| 1341 | #ifndef HAVE_SETPROCTITLE |
| 1342 | /* Prepare for later setproctitle emulation */ |
| 1343 | compat_init_setproctitle(ac, av); |
| 1344 | av = saved_argv; |
| 1345 | #endif |
| 1346 | |
| 1347 | if (geteuid() == 0 && setgroups(0, NULL) == -1) |
| 1348 | debug("setgroups(): %.200s", strerror(errno)); |
| 1349 | |
| 1350 | /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ |
| 1351 | sanitise_stdfd(); |
| 1352 | |
| 1353 | /* Initialize configuration options to their default values. */ |
| 1354 | initialize_server_options(&options); |
| 1355 | |
| 1356 | /* Parse command-line arguments. */ |
| 1357 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { |
| 1358 | switch (opt) { |
| 1359 | case '4': |
| 1360 | options.address_family = AF_INET; |
| 1361 | break; |
| 1362 | case '6': |
| 1363 | options.address_family = AF_INET6; |
| 1364 | break; |
| 1365 | case 'f': |
| 1366 | config_file_name = optarg; |
| 1367 | break; |
| 1368 | case 'c': |
| 1369 | if (options.num_host_cert_files >= MAX_HOSTCERTS) { |
| 1370 | fprintf(stderr, "too many host certificates.\n"); |
| 1371 | exit(1); |
| 1372 | } |
| 1373 | options.host_cert_files[options.num_host_cert_files++] = |
| 1374 | derelativise_path(optarg); |
| 1375 | break; |
| 1376 | case 'd': |
| 1377 | if (debug_flag == 0) { |
| 1378 | debug_flag = 1; |
| 1379 | options.log_level = SYSLOG_LEVEL_DEBUG1; |
| 1380 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) |
| 1381 | options.log_level++; |
| 1382 | break; |
| 1383 | case 'D': |
| 1384 | no_daemon_flag = 1; |
| 1385 | break; |
| 1386 | case 'e': |
| 1387 | log_stderr = 1; |
| 1388 | break; |
| 1389 | case 'i': |
| 1390 | inetd_flag = 1; |
| 1391 | break; |
| 1392 | case 'r': |
| 1393 | rexec_flag = 0; |
| 1394 | break; |
| 1395 | case 'R': |
| 1396 | rexeced_flag = 1; |
| 1397 | inetd_flag = 1; |
| 1398 | break; |
| 1399 | case 'Q': |
| 1400 | /* ignored */ |
| 1401 | break; |
| 1402 | case 'q': |
| 1403 | options.log_level = SYSLOG_LEVEL_QUIET; |
| 1404 | break; |
| 1405 | case 'b': |
| 1406 | options.server_key_bits = (int)strtonum(optarg, 256, |
| 1407 | 32768, NULL); |
| 1408 | break; |
| 1409 | case 'p': |
| 1410 | options.ports_from_cmdline = 1; |
| 1411 | if (options.num_ports >= MAX_PORTS) { |
| 1412 | fprintf(stderr, "too many ports.\n"); |
| 1413 | exit(1); |
| 1414 | } |
| 1415 | options.ports[options.num_ports++] = a2port(optarg); |
| 1416 | if (options.ports[options.num_ports-1] <= 0) { |
| 1417 | fprintf(stderr, "Bad port number.\n"); |
| 1418 | exit(1); |
| 1419 | } |
| 1420 | break; |
| 1421 | case 'g': |
| 1422 | if ((options.login_grace_time = convtime(optarg)) == -1) { |
| 1423 | fprintf(stderr, "Invalid login grace time.\n"); |
| 1424 | exit(1); |
| 1425 | } |
| 1426 | break; |
| 1427 | case 'k': |
| 1428 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { |
| 1429 | fprintf(stderr, "Invalid key regeneration interval.\n"); |
| 1430 | exit(1); |
| 1431 | } |
| 1432 | break; |
| 1433 | case 'h': |
| 1434 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
| 1435 | fprintf(stderr, "too many host keys.\n"); |
| 1436 | exit(1); |
| 1437 | } |
| 1438 | options.host_key_files[options.num_host_key_files++] = |
| 1439 | derelativise_path(optarg); |
| 1440 | break; |
| 1441 | case 't': |
| 1442 | test_flag = 1; |
| 1443 | break; |
| 1444 | case 'T': |
| 1445 | test_flag = 2; |
| 1446 | break; |
| 1447 | case 'C': |
| 1448 | cp = optarg; |
| 1449 | while ((p = strsep(&cp, ",")) && *p != '\0') { |
| 1450 | if (strncmp(p, "addr=", 5) == 0) |
| 1451 | test_addr = xstrdup(p + 5); |
| 1452 | else if (strncmp(p, "host=", 5) == 0) |
| 1453 | test_host = xstrdup(p + 5); |
| 1454 | else if (strncmp(p, "user=", 5) == 0) |
| 1455 | test_user = xstrdup(p + 5); |
| 1456 | else { |
| 1457 | fprintf(stderr, "Invalid test " |
| 1458 | "mode specification %s\n", p); |
| 1459 | exit(1); |
| 1460 | } |
| 1461 | } |
| 1462 | break; |
| 1463 | case 'u': |
| 1464 | utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); |
| 1465 | if (utmp_len > MAXHOSTNAMELEN) { |
| 1466 | fprintf(stderr, "Invalid utmp length.\n"); |
| 1467 | exit(1); |
| 1468 | } |
| 1469 | break; |
| 1470 | case 'o': |
| 1471 | line = xstrdup(optarg); |
| 1472 | if (process_server_config_line(&options, line, |
| 1473 | "command-line", 0, NULL, NULL, NULL, NULL) != 0) |
| 1474 | exit(1); |
| 1475 | xfree(line); |
| 1476 | break; |
| 1477 | case '?': |
| 1478 | default: |
| 1479 | usage(); |
| 1480 | break; |
| 1481 | } |
| 1482 | } |
| 1483 | if (rexeced_flag || inetd_flag) |
| 1484 | rexec_flag = 0; |
| 1485 | if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) |
| 1486 | fatal("sshd re-exec requires execution with an absolute path"); |
| 1487 | if (rexeced_flag) |
| 1488 | closefrom(REEXEC_MIN_FREE_FD); |
| 1489 | else |
| 1490 | closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); |
| 1491 | |
| 1492 | OpenSSL_add_all_algorithms(); |
| 1493 | |
| 1494 | /* |
| 1495 | * Force logging to stderr until we have loaded the private host |
| 1496 | * key (unless started from inetd) |
| 1497 | */ |
| 1498 | log_init(__progname, |
| 1499 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
| 1500 | SYSLOG_LEVEL_INFO : options.log_level, |
| 1501 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? |
| 1502 | SYSLOG_FACILITY_AUTH : options.log_facility, |
| 1503 | log_stderr || !inetd_flag); |
| 1504 | |
| 1505 | /* |
| 1506 | * Unset KRB5CCNAME, otherwise the user's session may inherit it from |
| 1507 | * root's environment |
| 1508 | */ |
| 1509 | if (getenv("KRB5CCNAME") != NULL) |
| 1510 | unsetenv("KRB5CCNAME"); |
| 1511 | |
| 1512 | #ifdef _UNICOS |
| 1513 | /* Cray can define user privs drop all privs now! |
| 1514 | * Not needed on PRIV_SU systems! |
| 1515 | */ |
| 1516 | drop_cray_privs(); |
| 1517 | #endif |
| 1518 | |
| 1519 | sensitive_data.server_key = NULL; |
| 1520 | sensitive_data.ssh1_host_key = NULL; |
| 1521 | sensitive_data.have_ssh1_key = 0; |
| 1522 | sensitive_data.have_ssh2_key = 0; |
| 1523 | |
| 1524 | /* |
| 1525 | * If we're doing an extended config test, make sure we have all of |
| 1526 | * the parameters we need. If we're not doing an extended test, |
| 1527 | * do not silently ignore connection test params. |
| 1528 | */ |
| 1529 | if (test_flag >= 2 && |
| 1530 | (test_user != NULL || test_host != NULL || test_addr != NULL) |
| 1531 | && (test_user == NULL || test_host == NULL || test_addr == NULL)) |
| 1532 | fatal("user, host and addr are all required when testing " |
| 1533 | "Match configs"); |
| 1534 | if (test_flag < 2 && (test_user != NULL || test_host != NULL || |
| 1535 | test_addr != NULL)) |
| 1536 | fatal("Config test connection parameter (-C) provided without " |
| 1537 | "test mode (-T)"); |
| 1538 | |
| 1539 | /* Fetch our configuration */ |
| 1540 | buffer_init(&cfg); |
| 1541 | if (rexeced_flag) |
| 1542 | recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); |
| 1543 | else |
| 1544 | load_server_config(config_file_name, &cfg); |
| 1545 | |
| 1546 | parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, |
| 1547 | &cfg, NULL, NULL, NULL); |
| 1548 | |
| 1549 | seed_rng(); |
| 1550 | |
| 1551 | /* Fill in default values for those options not explicitly set. */ |
| 1552 | fill_default_server_options(&options); |
| 1553 | |
| 1554 | /* challenge-response is implemented via keyboard interactive */ |
| 1555 | if (options.challenge_response_authentication) |
| 1556 | options.kbd_interactive_authentication = 1; |
| 1557 | |
| 1558 | /* set default channel AF */ |
| 1559 | channel_set_af(options.address_family); |
| 1560 | |
| 1561 | /* Check that there are no remaining arguments. */ |
| 1562 | if (optind < ac) { |
| 1563 | fprintf(stderr, "Extra argument %s.\n", av[optind]); |
| 1564 | exit(1); |
| 1565 | } |
| 1566 | |
| 1567 | debug("sshd version %.100s", SSH_RELEASE); |
| 1568 | |
| 1569 | /* Store privilege separation user for later use if required. */ |
| 1570 | if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { |
| 1571 | if (use_privsep || options.kerberos_authentication) |
| 1572 | fatal("Privilege separation user %s does not exist", |
| 1573 | SSH_PRIVSEP_USER); |
| 1574 | } else { |
| 1575 | if (privsep_pw->pw_passwd) |
| 1576 | memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); |
| 1577 | privsep_pw = pwcopy(privsep_pw); |
| 1578 | if (privsep_pw->pw_passwd) |
| 1579 | xfree(privsep_pw->pw_passwd); |
| 1580 | privsep_pw->pw_passwd = xstrdup("*"); |
| 1581 | } |
Greg Hartman | f5c67b4 | 2015-02-27 07:55:00 -0800 | [diff] [blame^] | 1582 | #ifndef ANDROID |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 1583 | endpwent(); |
Greg Hartman | f5c67b4 | 2015-02-27 07:55:00 -0800 | [diff] [blame^] | 1584 | #endif |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 1585 | |
| 1586 | /* load private host keys */ |
| 1587 | sensitive_data.host_keys = xcalloc(options.num_host_key_files, |
| 1588 | sizeof(Key *)); |
| 1589 | for (i = 0; i < options.num_host_key_files; i++) |
| 1590 | sensitive_data.host_keys[i] = NULL; |
| 1591 | |
| 1592 | for (i = 0; i < options.num_host_key_files; i++) { |
| 1593 | key = key_load_private(options.host_key_files[i], "", NULL); |
| 1594 | sensitive_data.host_keys[i] = key; |
| 1595 | if (key == NULL) { |
| 1596 | error("Could not load host key: %s", |
| 1597 | options.host_key_files[i]); |
| 1598 | sensitive_data.host_keys[i] = NULL; |
| 1599 | continue; |
| 1600 | } |
| 1601 | switch (key->type) { |
| 1602 | case KEY_RSA1: |
| 1603 | sensitive_data.ssh1_host_key = key; |
| 1604 | sensitive_data.have_ssh1_key = 1; |
| 1605 | break; |
| 1606 | case KEY_RSA: |
| 1607 | case KEY_DSA: |
| 1608 | case KEY_ECDSA: |
| 1609 | sensitive_data.have_ssh2_key = 1; |
| 1610 | break; |
| 1611 | } |
| 1612 | debug("private host key: #%d type %d %s", i, key->type, |
| 1613 | key_type(key)); |
| 1614 | } |
| 1615 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { |
| 1616 | logit("Disabling protocol version 1. Could not load host key"); |
| 1617 | options.protocol &= ~SSH_PROTO_1; |
| 1618 | } |
| 1619 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { |
| 1620 | logit("Disabling protocol version 2. Could not load host key"); |
| 1621 | options.protocol &= ~SSH_PROTO_2; |
| 1622 | } |
| 1623 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
| 1624 | logit("sshd: no hostkeys available -- exiting."); |
| 1625 | exit(1); |
| 1626 | } |
| 1627 | |
| 1628 | /* |
| 1629 | * Load certificates. They are stored in an array at identical |
| 1630 | * indices to the public keys that they relate to. |
| 1631 | */ |
| 1632 | sensitive_data.host_certificates = xcalloc(options.num_host_key_files, |
| 1633 | sizeof(Key *)); |
| 1634 | for (i = 0; i < options.num_host_key_files; i++) |
| 1635 | sensitive_data.host_certificates[i] = NULL; |
| 1636 | |
| 1637 | for (i = 0; i < options.num_host_cert_files; i++) { |
| 1638 | key = key_load_public(options.host_cert_files[i], NULL); |
| 1639 | if (key == NULL) { |
| 1640 | error("Could not load host certificate: %s", |
| 1641 | options.host_cert_files[i]); |
| 1642 | continue; |
| 1643 | } |
| 1644 | if (!key_is_cert(key)) { |
| 1645 | error("Certificate file is not a certificate: %s", |
| 1646 | options.host_cert_files[i]); |
| 1647 | key_free(key); |
| 1648 | continue; |
| 1649 | } |
| 1650 | /* Find matching private key */ |
| 1651 | for (j = 0; j < options.num_host_key_files; j++) { |
| 1652 | if (key_equal_public(key, |
| 1653 | sensitive_data.host_keys[j])) { |
| 1654 | sensitive_data.host_certificates[j] = key; |
| 1655 | break; |
| 1656 | } |
| 1657 | } |
| 1658 | if (j >= options.num_host_key_files) { |
| 1659 | error("No matching private key for certificate: %s", |
| 1660 | options.host_cert_files[i]); |
| 1661 | key_free(key); |
| 1662 | continue; |
| 1663 | } |
| 1664 | sensitive_data.host_certificates[j] = key; |
| 1665 | debug("host certificate: #%d type %d %s", j, key->type, |
| 1666 | key_type(key)); |
| 1667 | } |
| 1668 | /* Check certain values for sanity. */ |
| 1669 | if (options.protocol & SSH_PROTO_1) { |
| 1670 | if (options.server_key_bits < 512 || |
| 1671 | options.server_key_bits > 32768) { |
| 1672 | fprintf(stderr, "Bad server key size.\n"); |
| 1673 | exit(1); |
| 1674 | } |
| 1675 | /* |
| 1676 | * Check that server and host key lengths differ sufficiently. This |
| 1677 | * is necessary to make double encryption work with rsaref. Oh, I |
| 1678 | * hate software patents. I dont know if this can go? Niels |
| 1679 | */ |
| 1680 | if (options.server_key_bits > |
| 1681 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
| 1682 | SSH_KEY_BITS_RESERVED && options.server_key_bits < |
| 1683 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
| 1684 | SSH_KEY_BITS_RESERVED) { |
| 1685 | options.server_key_bits = |
| 1686 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
| 1687 | SSH_KEY_BITS_RESERVED; |
| 1688 | debug("Forcing server key to %d bits to make it differ from host key.", |
| 1689 | options.server_key_bits); |
| 1690 | } |
| 1691 | } |
| 1692 | |
| 1693 | if (use_privsep) { |
| 1694 | struct stat st; |
| 1695 | |
| 1696 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || |
| 1697 | (S_ISDIR(st.st_mode) == 0)) |
| 1698 | fatal("Missing privilege separation directory: %s", |
| 1699 | _PATH_PRIVSEP_CHROOT_DIR); |
| 1700 | |
| 1701 | #ifdef HAVE_CYGWIN |
| 1702 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && |
| 1703 | (st.st_uid != getuid () || |
| 1704 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) |
| 1705 | #else |
| 1706 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
| 1707 | #endif |
| 1708 | fatal("%s must be owned by root and not group or " |
| 1709 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); |
| 1710 | } |
| 1711 | |
| 1712 | if (test_flag > 1) { |
| 1713 | if (test_user != NULL && test_addr != NULL && test_host != NULL) |
| 1714 | parse_server_match_config(&options, test_user, |
| 1715 | test_host, test_addr); |
| 1716 | dump_config(&options); |
| 1717 | } |
| 1718 | |
| 1719 | /* Configuration looks good, so exit if in test mode. */ |
| 1720 | if (test_flag) |
| 1721 | exit(0); |
| 1722 | |
| 1723 | /* |
| 1724 | * Clear out any supplemental groups we may have inherited. This |
| 1725 | * prevents inadvertent creation of files with bad modes (in the |
| 1726 | * portable version at least, it's certainly possible for PAM |
| 1727 | * to create a file, and we can't control the code in every |
| 1728 | * module which might be used). |
| 1729 | */ |
| 1730 | if (setgroups(0, NULL) < 0) |
| 1731 | debug("setgroups() failed: %.200s", strerror(errno)); |
| 1732 | |
| 1733 | if (rexec_flag) { |
| 1734 | rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); |
| 1735 | for (i = 0; i < rexec_argc; i++) { |
| 1736 | debug("rexec_argv[%d]='%s'", i, saved_argv[i]); |
| 1737 | rexec_argv[i] = saved_argv[i]; |
| 1738 | } |
| 1739 | rexec_argv[rexec_argc] = "-R"; |
| 1740 | rexec_argv[rexec_argc + 1] = NULL; |
| 1741 | } |
| 1742 | |
| 1743 | /* Ensure that umask disallows at least group and world write */ |
| 1744 | new_umask = umask(0077) | 0022; |
| 1745 | (void) umask(new_umask); |
| 1746 | |
| 1747 | /* Initialize the log (it is reinitialized below in case we forked). */ |
| 1748 | if (debug_flag && (!inetd_flag || rexeced_flag)) |
| 1749 | log_stderr = 1; |
| 1750 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
| 1751 | |
| 1752 | /* |
| 1753 | * If not in debugging mode, and not started from inetd, disconnect |
| 1754 | * from the controlling terminal, and fork. The original process |
| 1755 | * exits. |
| 1756 | */ |
| 1757 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
| 1758 | #ifdef TIOCNOTTY |
| 1759 | int fd; |
| 1760 | #endif /* TIOCNOTTY */ |
| 1761 | if (daemon(0, 0) < 0) |
| 1762 | fatal("daemon() failed: %.200s", strerror(errno)); |
| 1763 | |
| 1764 | /* Disconnect from the controlling tty. */ |
| 1765 | #ifdef TIOCNOTTY |
| 1766 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
| 1767 | if (fd >= 0) { |
| 1768 | (void) ioctl(fd, TIOCNOTTY, NULL); |
| 1769 | close(fd); |
| 1770 | } |
| 1771 | #endif /* TIOCNOTTY */ |
| 1772 | } |
| 1773 | /* Reinitialize the log (because of the fork above). */ |
| 1774 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
| 1775 | |
| 1776 | /* Initialize the random number generator. */ |
| 1777 | arc4random_stir(); |
| 1778 | |
| 1779 | /* Chdir to the root directory so that the current disk can be |
| 1780 | unmounted if desired. */ |
| 1781 | chdir("/"); |
| 1782 | |
| 1783 | /* ignore SIGPIPE */ |
| 1784 | signal(SIGPIPE, SIG_IGN); |
| 1785 | |
| 1786 | /* Get a connection, either from inetd or a listening TCP socket */ |
| 1787 | if (inetd_flag) { |
| 1788 | server_accept_inetd(&sock_in, &sock_out); |
| 1789 | } else { |
| 1790 | platform_pre_listen(); |
| 1791 | server_listen(); |
| 1792 | |
| 1793 | if (options.protocol & SSH_PROTO_1) |
| 1794 | generate_ephemeral_server_key(); |
| 1795 | |
| 1796 | signal(SIGHUP, sighup_handler); |
| 1797 | signal(SIGCHLD, main_sigchld_handler); |
| 1798 | signal(SIGTERM, sigterm_handler); |
| 1799 | signal(SIGQUIT, sigterm_handler); |
| 1800 | |
| 1801 | /* |
| 1802 | * Write out the pid file after the sigterm handler |
| 1803 | * is setup and the listen sockets are bound |
| 1804 | */ |
| 1805 | if (!debug_flag) { |
| 1806 | FILE *f = fopen(options.pid_file, "w"); |
| 1807 | |
| 1808 | if (f == NULL) { |
| 1809 | error("Couldn't create pid file \"%s\": %s", |
| 1810 | options.pid_file, strerror(errno)); |
| 1811 | } else { |
| 1812 | fprintf(f, "%ld\n", (long) getpid()); |
| 1813 | fclose(f); |
| 1814 | } |
| 1815 | } |
| 1816 | |
| 1817 | /* Accept a connection and return in a forked child */ |
| 1818 | server_accept_loop(&sock_in, &sock_out, |
| 1819 | &newsock, config_s); |
| 1820 | } |
| 1821 | |
| 1822 | /* This is the child processing a new connection. */ |
| 1823 | setproctitle("%s", "[accepted]"); |
| 1824 | |
| 1825 | /* |
| 1826 | * Create a new session and process group since the 4.4BSD |
| 1827 | * setlogin() affects the entire process group. We don't |
| 1828 | * want the child to be able to affect the parent. |
| 1829 | */ |
| 1830 | #if !defined(SSHD_ACQUIRES_CTTY) |
| 1831 | /* |
| 1832 | * If setsid is called, on some platforms sshd will later acquire a |
| 1833 | * controlling terminal which will result in "could not set |
| 1834 | * controlling tty" errors. |
| 1835 | */ |
| 1836 | if (!debug_flag && !inetd_flag && setsid() < 0) |
| 1837 | error("setsid: %.100s", strerror(errno)); |
| 1838 | #endif |
| 1839 | |
| 1840 | if (rexec_flag) { |
| 1841 | int fd; |
| 1842 | |
| 1843 | debug("rexec start in %d out %d newsock %d pipe %d sock %d", |
| 1844 | sock_in, sock_out, newsock, startup_pipe, config_s[0]); |
| 1845 | dup2(newsock, STDIN_FILENO); |
| 1846 | dup2(STDIN_FILENO, STDOUT_FILENO); |
| 1847 | if (startup_pipe == -1) |
| 1848 | close(REEXEC_STARTUP_PIPE_FD); |
| 1849 | else |
| 1850 | dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); |
| 1851 | |
| 1852 | dup2(config_s[1], REEXEC_CONFIG_PASS_FD); |
| 1853 | close(config_s[1]); |
| 1854 | if (startup_pipe != -1) |
| 1855 | close(startup_pipe); |
| 1856 | |
| 1857 | execv(rexec_argv[0], rexec_argv); |
| 1858 | |
| 1859 | /* Reexec has failed, fall back and continue */ |
| 1860 | error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); |
| 1861 | recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); |
| 1862 | log_init(__progname, options.log_level, |
| 1863 | options.log_facility, log_stderr); |
| 1864 | |
| 1865 | /* Clean up fds */ |
| 1866 | startup_pipe = REEXEC_STARTUP_PIPE_FD; |
| 1867 | close(config_s[1]); |
| 1868 | close(REEXEC_CONFIG_PASS_FD); |
| 1869 | newsock = sock_out = sock_in = dup(STDIN_FILENO); |
| 1870 | if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { |
| 1871 | dup2(fd, STDIN_FILENO); |
| 1872 | dup2(fd, STDOUT_FILENO); |
| 1873 | if (fd > STDERR_FILENO) |
| 1874 | close(fd); |
| 1875 | } |
| 1876 | debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", |
| 1877 | sock_in, sock_out, newsock, startup_pipe, config_s[0]); |
| 1878 | } |
| 1879 | |
| 1880 | /* Executed child processes don't need these. */ |
| 1881 | fcntl(sock_out, F_SETFD, FD_CLOEXEC); |
| 1882 | fcntl(sock_in, F_SETFD, FD_CLOEXEC); |
| 1883 | |
| 1884 | /* |
| 1885 | * Disable the key regeneration alarm. We will not regenerate the |
| 1886 | * key since we are no longer in a position to give it to anyone. We |
| 1887 | * will not restart on SIGHUP since it no longer makes sense. |
| 1888 | */ |
| 1889 | alarm(0); |
| 1890 | signal(SIGALRM, SIG_DFL); |
| 1891 | signal(SIGHUP, SIG_DFL); |
| 1892 | signal(SIGTERM, SIG_DFL); |
| 1893 | signal(SIGQUIT, SIG_DFL); |
| 1894 | signal(SIGCHLD, SIG_DFL); |
| 1895 | signal(SIGINT, SIG_DFL); |
| 1896 | |
| 1897 | /* |
| 1898 | * Register our connection. This turns encryption off because we do |
| 1899 | * not have a key. |
| 1900 | */ |
| 1901 | packet_set_connection(sock_in, sock_out); |
| 1902 | packet_set_server(); |
| 1903 | |
| 1904 | /* Set SO_KEEPALIVE if requested. */ |
| 1905 | if (options.tcp_keep_alive && packet_connection_is_on_socket() && |
| 1906 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) |
| 1907 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); |
| 1908 | |
| 1909 | if ((remote_port = get_remote_port()) < 0) { |
| 1910 | debug("get_remote_port failed"); |
| 1911 | cleanup_exit(255); |
| 1912 | } |
| 1913 | |
| 1914 | /* |
| 1915 | * We use get_canonical_hostname with usedns = 0 instead of |
| 1916 | * get_remote_ipaddr here so IP options will be checked. |
| 1917 | */ |
| 1918 | (void) get_canonical_hostname(0); |
| 1919 | /* |
| 1920 | * The rest of the code depends on the fact that |
| 1921 | * get_remote_ipaddr() caches the remote ip, even if |
| 1922 | * the socket goes away. |
| 1923 | */ |
| 1924 | remote_ip = get_remote_ipaddr(); |
| 1925 | |
| 1926 | #ifdef SSH_AUDIT_EVENTS |
| 1927 | audit_connection_from(remote_ip, remote_port); |
| 1928 | #endif |
| 1929 | #ifdef LIBWRAP |
| 1930 | allow_severity = options.log_facility|LOG_INFO; |
| 1931 | deny_severity = options.log_facility|LOG_WARNING; |
| 1932 | /* Check whether logins are denied from this host. */ |
| 1933 | if (packet_connection_is_on_socket()) { |
| 1934 | struct request_info req; |
| 1935 | |
| 1936 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); |
| 1937 | fromhost(&req); |
| 1938 | |
| 1939 | if (!hosts_access(&req)) { |
| 1940 | debug("Connection refused by tcp wrapper"); |
| 1941 | refuse(&req); |
| 1942 | /* NOTREACHED */ |
| 1943 | fatal("libwrap refuse returns"); |
| 1944 | } |
| 1945 | } |
| 1946 | #endif /* LIBWRAP */ |
| 1947 | |
| 1948 | /* Log the connection. */ |
| 1949 | verbose("Connection from %.500s port %d", remote_ip, remote_port); |
| 1950 | |
| 1951 | /* |
| 1952 | * We don't want to listen forever unless the other side |
| 1953 | * successfully authenticates itself. So we set up an alarm which is |
| 1954 | * cleared after successful authentication. A limit of zero |
| 1955 | * indicates no limit. Note that we don't set the alarm in debugging |
| 1956 | * mode; it is just annoying to have the server exit just when you |
| 1957 | * are about to discover the bug. |
| 1958 | */ |
| 1959 | signal(SIGALRM, grace_alarm_handler); |
| 1960 | if (!debug_flag) |
| 1961 | alarm(options.login_grace_time); |
| 1962 | |
| 1963 | sshd_exchange_identification(sock_in, sock_out); |
| 1964 | |
| 1965 | /* In inetd mode, generate ephemeral key only for proto 1 connections */ |
| 1966 | if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) |
| 1967 | generate_ephemeral_server_key(); |
| 1968 | |
| 1969 | packet_set_nonblocking(); |
| 1970 | |
| 1971 | /* allocate authentication context */ |
| 1972 | authctxt = xcalloc(1, sizeof(*authctxt)); |
| 1973 | |
| 1974 | authctxt->loginmsg = &loginmsg; |
| 1975 | |
| 1976 | /* XXX global for cleanup, access from other modules */ |
| 1977 | the_authctxt = authctxt; |
| 1978 | |
| 1979 | /* prepare buffer to collect messages to display to user after login */ |
| 1980 | buffer_init(&loginmsg); |
| 1981 | auth_debug_reset(); |
| 1982 | |
| 1983 | if (use_privsep) |
| 1984 | if (privsep_preauth(authctxt) == 1) |
| 1985 | goto authenticated; |
| 1986 | |
| 1987 | /* perform the key exchange */ |
| 1988 | /* authenticate user and start session */ |
| 1989 | if (compat20) { |
| 1990 | do_ssh2_kex(); |
| 1991 | do_authentication2(authctxt); |
| 1992 | } else { |
| 1993 | do_ssh1_kex(); |
| 1994 | do_authentication(authctxt); |
| 1995 | } |
| 1996 | /* |
| 1997 | * If we use privilege separation, the unprivileged child transfers |
| 1998 | * the current keystate and exits |
| 1999 | */ |
| 2000 | if (use_privsep) { |
| 2001 | mm_send_keystate(pmonitor); |
| 2002 | exit(0); |
| 2003 | } |
| 2004 | |
| 2005 | authenticated: |
| 2006 | /* |
| 2007 | * Cancel the alarm we set to limit the time taken for |
| 2008 | * authentication. |
| 2009 | */ |
| 2010 | alarm(0); |
| 2011 | signal(SIGALRM, SIG_DFL); |
| 2012 | authctxt->authenticated = 1; |
| 2013 | if (startup_pipe != -1) { |
| 2014 | close(startup_pipe); |
| 2015 | startup_pipe = -1; |
| 2016 | } |
| 2017 | |
| 2018 | #ifdef SSH_AUDIT_EVENTS |
| 2019 | audit_event(SSH_AUTH_SUCCESS); |
| 2020 | #endif |
| 2021 | |
| 2022 | #ifdef GSSAPI |
| 2023 | if (options.gss_authentication) { |
| 2024 | temporarily_use_uid(authctxt->pw); |
| 2025 | ssh_gssapi_storecreds(); |
| 2026 | restore_uid(); |
| 2027 | } |
| 2028 | #endif |
| 2029 | #ifdef USE_PAM |
| 2030 | if (options.use_pam) { |
| 2031 | do_pam_setcred(1); |
| 2032 | do_pam_session(); |
| 2033 | } |
| 2034 | #endif |
| 2035 | |
| 2036 | /* |
| 2037 | * In privilege separation, we fork another child and prepare |
| 2038 | * file descriptor passing. |
| 2039 | */ |
| 2040 | if (use_privsep) { |
| 2041 | privsep_postauth(authctxt); |
| 2042 | /* the monitor process [priv] will not return */ |
| 2043 | if (!compat20) |
| 2044 | destroy_sensitive_data(); |
| 2045 | } |
| 2046 | |
| 2047 | packet_set_timeout(options.client_alive_interval, |
| 2048 | options.client_alive_count_max); |
| 2049 | |
| 2050 | /* Start session. */ |
| 2051 | do_authenticated(authctxt); |
| 2052 | |
| 2053 | /* The connection has been terminated. */ |
| 2054 | packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); |
| 2055 | packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); |
| 2056 | verbose("Transferred: sent %llu, received %llu bytes", |
| 2057 | (unsigned long long)obytes, (unsigned long long)ibytes); |
| 2058 | |
| 2059 | verbose("Closing connection to %.500s port %d", remote_ip, remote_port); |
| 2060 | |
| 2061 | #ifdef USE_PAM |
| 2062 | if (options.use_pam) |
| 2063 | finish_pam(); |
| 2064 | #endif /* USE_PAM */ |
| 2065 | |
| 2066 | #ifdef SSH_AUDIT_EVENTS |
| 2067 | PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); |
| 2068 | #endif |
| 2069 | |
| 2070 | packet_close(); |
| 2071 | |
| 2072 | if (use_privsep) |
| 2073 | mm_terminate(); |
| 2074 | |
| 2075 | exit(0); |
| 2076 | } |
| 2077 | |
| 2078 | /* |
| 2079 | * Decrypt session_key_int using our private server key and private host key |
| 2080 | * (key with larger modulus first). |
| 2081 | */ |
| 2082 | int |
| 2083 | ssh1_session_key(BIGNUM *session_key_int) |
| 2084 | { |
| 2085 | int rsafail = 0; |
| 2086 | |
| 2087 | if (BN_cmp(sensitive_data.server_key->rsa->n, |
| 2088 | sensitive_data.ssh1_host_key->rsa->n) > 0) { |
| 2089 | /* Server key has bigger modulus. */ |
| 2090 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < |
| 2091 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
| 2092 | SSH_KEY_BITS_RESERVED) { |
| 2093 | fatal("do_connection: %s: " |
| 2094 | "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", |
| 2095 | get_remote_ipaddr(), |
| 2096 | BN_num_bits(sensitive_data.server_key->rsa->n), |
| 2097 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), |
| 2098 | SSH_KEY_BITS_RESERVED); |
| 2099 | } |
| 2100 | if (rsa_private_decrypt(session_key_int, session_key_int, |
| 2101 | sensitive_data.server_key->rsa) <= 0) |
| 2102 | rsafail++; |
| 2103 | if (rsa_private_decrypt(session_key_int, session_key_int, |
| 2104 | sensitive_data.ssh1_host_key->rsa) <= 0) |
| 2105 | rsafail++; |
| 2106 | } else { |
| 2107 | /* Host key has bigger modulus (or they are equal). */ |
| 2108 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < |
| 2109 | BN_num_bits(sensitive_data.server_key->rsa->n) + |
| 2110 | SSH_KEY_BITS_RESERVED) { |
| 2111 | fatal("do_connection: %s: " |
| 2112 | "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", |
| 2113 | get_remote_ipaddr(), |
| 2114 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), |
| 2115 | BN_num_bits(sensitive_data.server_key->rsa->n), |
| 2116 | SSH_KEY_BITS_RESERVED); |
| 2117 | } |
| 2118 | if (rsa_private_decrypt(session_key_int, session_key_int, |
| 2119 | sensitive_data.ssh1_host_key->rsa) < 0) |
| 2120 | rsafail++; |
| 2121 | if (rsa_private_decrypt(session_key_int, session_key_int, |
| 2122 | sensitive_data.server_key->rsa) < 0) |
| 2123 | rsafail++; |
| 2124 | } |
| 2125 | return (rsafail); |
| 2126 | } |
| 2127 | /* |
| 2128 | * SSH1 key exchange |
| 2129 | */ |
| 2130 | static void |
| 2131 | do_ssh1_kex(void) |
| 2132 | { |
| 2133 | int i, len; |
| 2134 | int rsafail = 0; |
| 2135 | BIGNUM *session_key_int; |
| 2136 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
| 2137 | u_char cookie[8]; |
| 2138 | u_int cipher_type, auth_mask, protocol_flags; |
| 2139 | |
| 2140 | /* |
| 2141 | * Generate check bytes that the client must send back in the user |
| 2142 | * packet in order for it to be accepted; this is used to defy ip |
| 2143 | * spoofing attacks. Note that this only works against somebody |
| 2144 | * doing IP spoofing from a remote machine; any machine on the local |
| 2145 | * network can still see outgoing packets and catch the random |
| 2146 | * cookie. This only affects rhosts authentication, and this is one |
| 2147 | * of the reasons why it is inherently insecure. |
| 2148 | */ |
| 2149 | arc4random_buf(cookie, sizeof(cookie)); |
| 2150 | |
| 2151 | /* |
| 2152 | * Send our public key. We include in the packet 64 bits of random |
| 2153 | * data that must be matched in the reply in order to prevent IP |
| 2154 | * spoofing. |
| 2155 | */ |
| 2156 | packet_start(SSH_SMSG_PUBLIC_KEY); |
| 2157 | for (i = 0; i < 8; i++) |
| 2158 | packet_put_char(cookie[i]); |
| 2159 | |
| 2160 | /* Store our public server RSA key. */ |
| 2161 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
| 2162 | packet_put_bignum(sensitive_data.server_key->rsa->e); |
| 2163 | packet_put_bignum(sensitive_data.server_key->rsa->n); |
| 2164 | |
| 2165 | /* Store our public host RSA key. */ |
| 2166 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
| 2167 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); |
| 2168 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); |
| 2169 | |
| 2170 | /* Put protocol flags. */ |
| 2171 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); |
| 2172 | |
| 2173 | /* Declare which ciphers we support. */ |
| 2174 | packet_put_int(cipher_mask_ssh1(0)); |
| 2175 | |
| 2176 | /* Declare supported authentication types. */ |
| 2177 | auth_mask = 0; |
| 2178 | if (options.rhosts_rsa_authentication) |
| 2179 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; |
| 2180 | if (options.rsa_authentication) |
| 2181 | auth_mask |= 1 << SSH_AUTH_RSA; |
| 2182 | if (options.challenge_response_authentication == 1) |
| 2183 | auth_mask |= 1 << SSH_AUTH_TIS; |
| 2184 | if (options.password_authentication) |
| 2185 | auth_mask |= 1 << SSH_AUTH_PASSWORD; |
| 2186 | packet_put_int(auth_mask); |
| 2187 | |
| 2188 | /* Send the packet and wait for it to be sent. */ |
| 2189 | packet_send(); |
| 2190 | packet_write_wait(); |
| 2191 | |
| 2192 | debug("Sent %d bit server key and %d bit host key.", |
| 2193 | BN_num_bits(sensitive_data.server_key->rsa->n), |
| 2194 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
| 2195 | |
| 2196 | /* Read clients reply (cipher type and session key). */ |
| 2197 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
| 2198 | |
| 2199 | /* Get cipher type and check whether we accept this. */ |
| 2200 | cipher_type = packet_get_char(); |
| 2201 | |
| 2202 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
| 2203 | packet_disconnect("Warning: client selects unsupported cipher."); |
| 2204 | |
| 2205 | /* Get check bytes from the packet. These must match those we |
| 2206 | sent earlier with the public key packet. */ |
| 2207 | for (i = 0; i < 8; i++) |
| 2208 | if (cookie[i] != packet_get_char()) |
| 2209 | packet_disconnect("IP Spoofing check bytes do not match."); |
| 2210 | |
| 2211 | debug("Encryption type: %.200s", cipher_name(cipher_type)); |
| 2212 | |
| 2213 | /* Get the encrypted integer. */ |
| 2214 | if ((session_key_int = BN_new()) == NULL) |
| 2215 | fatal("do_ssh1_kex: BN_new failed"); |
| 2216 | packet_get_bignum(session_key_int); |
| 2217 | |
| 2218 | protocol_flags = packet_get_int(); |
| 2219 | packet_set_protocol_flags(protocol_flags); |
| 2220 | packet_check_eom(); |
| 2221 | |
| 2222 | /* Decrypt session_key_int using host/server keys */ |
| 2223 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); |
| 2224 | |
| 2225 | /* |
| 2226 | * Extract session key from the decrypted integer. The key is in the |
| 2227 | * least significant 256 bits of the integer; the first byte of the |
| 2228 | * key is in the highest bits. |
| 2229 | */ |
| 2230 | if (!rsafail) { |
| 2231 | (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); |
| 2232 | len = BN_num_bytes(session_key_int); |
| 2233 | if (len < 0 || (u_int)len > sizeof(session_key)) { |
| 2234 | error("do_ssh1_kex: bad session key len from %s: " |
| 2235 | "session_key_int %d > sizeof(session_key) %lu", |
| 2236 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); |
| 2237 | rsafail++; |
| 2238 | } else { |
| 2239 | memset(session_key, 0, sizeof(session_key)); |
| 2240 | BN_bn2bin(session_key_int, |
| 2241 | session_key + sizeof(session_key) - len); |
| 2242 | |
| 2243 | derive_ssh1_session_id( |
| 2244 | sensitive_data.ssh1_host_key->rsa->n, |
| 2245 | sensitive_data.server_key->rsa->n, |
| 2246 | cookie, session_id); |
| 2247 | /* |
| 2248 | * Xor the first 16 bytes of the session key with the |
| 2249 | * session id. |
| 2250 | */ |
| 2251 | for (i = 0; i < 16; i++) |
| 2252 | session_key[i] ^= session_id[i]; |
| 2253 | } |
| 2254 | } |
| 2255 | if (rsafail) { |
| 2256 | int bytes = BN_num_bytes(session_key_int); |
| 2257 | u_char *buf = xmalloc(bytes); |
| 2258 | MD5_CTX md; |
| 2259 | |
| 2260 | logit("do_connection: generating a fake encryption key"); |
| 2261 | BN_bn2bin(session_key_int, buf); |
| 2262 | MD5_Init(&md); |
| 2263 | MD5_Update(&md, buf, bytes); |
| 2264 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); |
| 2265 | MD5_Final(session_key, &md); |
| 2266 | MD5_Init(&md); |
| 2267 | MD5_Update(&md, session_key, 16); |
| 2268 | MD5_Update(&md, buf, bytes); |
| 2269 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); |
| 2270 | MD5_Final(session_key + 16, &md); |
| 2271 | memset(buf, 0, bytes); |
| 2272 | xfree(buf); |
| 2273 | for (i = 0; i < 16; i++) |
| 2274 | session_id[i] = session_key[i] ^ session_key[i + 16]; |
| 2275 | } |
| 2276 | /* Destroy the private and public keys. No longer. */ |
| 2277 | destroy_sensitive_data(); |
| 2278 | |
| 2279 | if (use_privsep) |
| 2280 | mm_ssh1_session_id(session_id); |
| 2281 | |
| 2282 | /* Destroy the decrypted integer. It is no longer needed. */ |
| 2283 | BN_clear_free(session_key_int); |
| 2284 | |
| 2285 | /* Set the session key. From this on all communications will be encrypted. */ |
| 2286 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); |
| 2287 | |
| 2288 | /* Destroy our copy of the session key. It is no longer needed. */ |
| 2289 | memset(session_key, 0, sizeof(session_key)); |
| 2290 | |
| 2291 | debug("Received session key; encryption turned on."); |
| 2292 | |
| 2293 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
| 2294 | packet_start(SSH_SMSG_SUCCESS); |
| 2295 | packet_send(); |
| 2296 | packet_write_wait(); |
| 2297 | } |
| 2298 | |
| 2299 | /* |
| 2300 | * SSH2 key exchange: diffie-hellman-group1-sha1 |
| 2301 | */ |
| 2302 | static void |
| 2303 | do_ssh2_kex(void) |
| 2304 | { |
| 2305 | Kex *kex; |
| 2306 | |
| 2307 | if (options.ciphers != NULL) { |
| 2308 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
| 2309 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
| 2310 | } |
| 2311 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
| 2312 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); |
| 2313 | myproposal[PROPOSAL_ENC_ALGS_STOC] = |
| 2314 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); |
| 2315 | |
| 2316 | if (options.macs != NULL) { |
| 2317 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = |
| 2318 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; |
| 2319 | } |
| 2320 | if (options.compression == COMP_NONE) { |
| 2321 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = |
| 2322 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; |
| 2323 | } else if (options.compression == COMP_DELAYED) { |
| 2324 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = |
| 2325 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; |
| 2326 | } |
| 2327 | if (options.kex_algorithms != NULL) |
| 2328 | myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; |
| 2329 | |
| 2330 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
| 2331 | |
| 2332 | /* start key exchange */ |
| 2333 | kex = kex_setup(myproposal); |
| 2334 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; |
| 2335 | kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; |
| 2336 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; |
| 2337 | kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; |
| 2338 | kex->kex[KEX_ECDH_SHA2] = kexecdh_server; |
| 2339 | kex->server = 1; |
| 2340 | kex->client_version_string=client_version_string; |
| 2341 | kex->server_version_string=server_version_string; |
| 2342 | kex->load_host_public_key=&get_hostkey_public_by_type; |
| 2343 | kex->load_host_private_key=&get_hostkey_private_by_type; |
| 2344 | kex->host_key_index=&get_hostkey_index; |
| 2345 | |
| 2346 | xxx_kex = kex; |
| 2347 | |
| 2348 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); |
| 2349 | |
| 2350 | session_id2 = kex->session_id; |
| 2351 | session_id2_len = kex->session_id_len; |
| 2352 | |
| 2353 | #ifdef DEBUG_KEXDH |
| 2354 | /* send 1st encrypted/maced/compressed message */ |
| 2355 | packet_start(SSH2_MSG_IGNORE); |
| 2356 | packet_put_cstring("markus"); |
| 2357 | packet_send(); |
| 2358 | packet_write_wait(); |
| 2359 | #endif |
| 2360 | debug("KEX done"); |
| 2361 | } |
| 2362 | |
| 2363 | /* server specific fatal cleanup */ |
| 2364 | void |
| 2365 | cleanup_exit(int i) |
| 2366 | { |
| 2367 | if (the_authctxt) |
| 2368 | do_cleanup(the_authctxt); |
| 2369 | #ifdef SSH_AUDIT_EVENTS |
| 2370 | /* done after do_cleanup so it can cancel the PAM auth 'thread' */ |
| 2371 | if (!use_privsep || mm_is_monitor()) |
| 2372 | audit_event(SSH_CONNECTION_ABANDON); |
| 2373 | #endif |
| 2374 | _exit(i); |
| 2375 | } |