1 /*- 2 * Copyright (c) 2002 Networks Associates Technology, Inc. 3 * All rights reserved. 4 * 5 * This software was developed for the FreeBSD Project by ThinkSec AS and 6 * NAI Labs, the Security Research Division of Network Associates, Inc. 7 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 8 * DARPA CHATS research program. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 /* 32 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org> 33 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au> 34 * 35 * Permission to use, copy, modify, and distribute this software for any 36 * purpose with or without fee is hereby granted, provided that the above 37 * copyright notice and this permission notice appear in all copies. 38 * 39 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 40 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 41 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 42 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 43 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 44 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 45 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 46 */ 47 48 /* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */ 49 50 #include "includes.h" 51 52 #include <sys/types.h> 53 #include <sys/stat.h> 54 #include <sys/wait.h> 55 56 #include <errno.h> 57 #include <signal.h> 58 #include <stdarg.h> 59 #include <string.h> 60 #include <unistd.h> 61 62 #ifdef USE_PAM 63 #if defined(HAVE_SECURITY_PAM_APPL_H) 64 #include <security/pam_appl.h> 65 #elif defined (HAVE_PAM_PAM_APPL_H) 66 #include <pam/pam_appl.h> 67 #endif 68 69 #if !defined(SSHD_PAM_SERVICE) 70 extern char *__progname; 71 # define SSHD_PAM_SERVICE __progname 72 #endif 73 74 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 75 #ifdef PAM_SUN_CODEBASE 76 # define sshpam_const /* Solaris, HP-UX, SunOS */ 77 #else 78 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */ 79 #endif 80 81 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 82 #ifdef PAM_SUN_CODEBASE 83 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 84 #else 85 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 86 #endif 87 88 #include "xmalloc.h" 89 #include "buffer.h" 90 #include "key.h" 91 #include "hostfile.h" 92 #include "auth.h" 93 #include "auth-pam.h" 94 #include "canohost.h" 95 #include "log.h" 96 #include "msg.h" 97 #include "packet.h" 98 #include "misc.h" 99 #include "servconf.h" 100 #include "ssh2.h" 101 #include "auth-options.h" 102 #ifdef GSSAPI 103 #include "ssh-gss.h" 104 #endif 105 #include "monitor_wrap.h" 106 #include "blacklist_client.h" 107 108 extern ServerOptions options; 109 extern Buffer loginmsg; 110 extern int compat20; 111 extern u_int utmp_len; 112 113 /* so we don't silently change behaviour */ 114 #ifdef USE_POSIX_THREADS 115 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 116 #endif 117 118 /* 119 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 120 * and generally a bad idea. Use at own risk and do not expect support if 121 * this breaks. 122 */ 123 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 124 #include <pthread.h> 125 /* 126 * Avoid namespace clash when *not* using pthreads for systems *with* 127 * pthreads, which unconditionally define pthread_t via sys/types.h 128 * (e.g. Linux) 129 */ 130 typedef pthread_t sp_pthread_t; 131 #else 132 typedef pid_t sp_pthread_t; 133 #endif 134 135 struct pam_ctxt { 136 sp_pthread_t pam_thread; 137 int pam_psock; 138 int pam_csock; 139 int pam_done; 140 }; 141 142 static void sshpam_free_ctx(void *); 143 static struct pam_ctxt *cleanup_ctxt; 144 145 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 146 /* 147 * Simulate threads with processes. 148 */ 149 150 static int sshpam_thread_status = -1; 151 static mysig_t sshpam_oldsig; 152 153 static void 154 sshpam_sigchld_handler(int sig) 155 { 156 signal(SIGCHLD, SIG_DFL); 157 if (cleanup_ctxt == NULL) 158 return; /* handler called after PAM cleanup, shouldn't happen */ 159 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 160 <= 0) { 161 /* PAM thread has not exitted, privsep slave must have */ 162 kill(cleanup_ctxt->pam_thread, SIGTERM); 163 while (waitpid(cleanup_ctxt->pam_thread, 164 &sshpam_thread_status, 0) == -1) { 165 if (errno == EINTR) 166 continue; 167 return; 168 } 169 } 170 if (WIFSIGNALED(sshpam_thread_status) && 171 WTERMSIG(sshpam_thread_status) == SIGTERM) 172 return; /* terminated by pthread_cancel */ 173 if (!WIFEXITED(sshpam_thread_status)) 174 sigdie("PAM: authentication thread exited unexpectedly"); 175 if (WEXITSTATUS(sshpam_thread_status) != 0) 176 sigdie("PAM: authentication thread exited uncleanly"); 177 } 178 179 /* ARGSUSED */ 180 static void 181 pthread_exit(void *value) 182 { 183 _exit(0); 184 } 185 186 /* ARGSUSED */ 187 static int 188 pthread_create(sp_pthread_t *thread, const void *attr, 189 void *(*thread_start)(void *), void *arg) 190 { 191 pid_t pid; 192 struct pam_ctxt *ctx = arg; 193 194 sshpam_thread_status = -1; 195 switch ((pid = fork())) { 196 case -1: 197 error("fork(): %s", strerror(errno)); 198 return (-1); 199 case 0: 200 close(ctx->pam_psock); 201 ctx->pam_psock = -1; 202 thread_start(arg); 203 _exit(1); 204 default: 205 *thread = pid; 206 close(ctx->pam_csock); 207 ctx->pam_csock = -1; 208 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler); 209 return (0); 210 } 211 } 212 213 static int 214 pthread_cancel(sp_pthread_t thread) 215 { 216 signal(SIGCHLD, sshpam_oldsig); 217 return (kill(thread, SIGTERM)); 218 } 219 220 /* ARGSUSED */ 221 static int 222 pthread_join(sp_pthread_t thread, void **value) 223 { 224 int status; 225 226 if (sshpam_thread_status != -1) 227 return (sshpam_thread_status); 228 signal(SIGCHLD, sshpam_oldsig); 229 while (waitpid(thread, &status, 0) == -1) { 230 if (errno == EINTR) 231 continue; 232 fatal("%s: waitpid: %s", __func__, strerror(errno)); 233 } 234 return (status); 235 } 236 #endif 237 238 239 static pam_handle_t *sshpam_handle = NULL; 240 static int sshpam_err = 0; 241 static int sshpam_authenticated = 0; 242 static int sshpam_session_open = 0; 243 static int sshpam_cred_established = 0; 244 static int sshpam_account_status = -1; 245 static int sshpam_maxtries_reached = 0; 246 static char **sshpam_env = NULL; 247 static Authctxt *sshpam_authctxt = NULL; 248 static const char *sshpam_password = NULL; 249 250 /* Some PAM implementations don't implement this */ 251 #ifndef HAVE_PAM_GETENVLIST 252 static char ** 253 pam_getenvlist(pam_handle_t *pamh) 254 { 255 /* 256 * XXX - If necessary, we can still support envrionment passing 257 * for platforms without pam_getenvlist by searching for known 258 * env vars (e.g. KRB5CCNAME) from the PAM environment. 259 */ 260 return NULL; 261 } 262 #endif 263 264 /* 265 * Some platforms, notably Solaris, do not enforce password complexity 266 * rules during pam_chauthtok() if the real uid of the calling process 267 * is 0, on the assumption that it's being called by "passwd" run by root. 268 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 269 * the right thing. 270 */ 271 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 272 static int 273 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 274 { 275 int result; 276 277 if (sshpam_authctxt == NULL) 278 fatal("PAM: sshpam_authctxt not initialized"); 279 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 280 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 281 result = pam_chauthtok(pamh, flags); 282 if (setreuid(0, -1) == -1) 283 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 284 return result; 285 } 286 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 287 #endif 288 289 void 290 sshpam_password_change_required(int reqd) 291 { 292 debug3("%s %d", __func__, reqd); 293 if (sshpam_authctxt == NULL) 294 fatal("%s: PAM authctxt not initialized", __func__); 295 sshpam_authctxt->force_pwchange = reqd; 296 if (reqd) { 297 no_port_forwarding_flag |= 2; 298 no_agent_forwarding_flag |= 2; 299 no_x11_forwarding_flag |= 2; 300 } else { 301 no_port_forwarding_flag &= ~2; 302 no_agent_forwarding_flag &= ~2; 303 no_x11_forwarding_flag &= ~2; 304 } 305 } 306 307 /* Import regular and PAM environment from subprocess */ 308 static void 309 import_environments(Buffer *b) 310 { 311 char *env; 312 u_int i, num_env; 313 int err; 314 315 debug3("PAM: %s entering", __func__); 316 317 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 318 /* Import variables set by do_pam_account */ 319 sshpam_account_status = buffer_get_int(b); 320 sshpam_password_change_required(buffer_get_int(b)); 321 322 /* Import environment from subprocess */ 323 num_env = buffer_get_int(b); 324 if (num_env > 1024) 325 fatal("%s: received %u environment variables, expected <= 1024", 326 __func__, num_env); 327 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 328 debug3("PAM: num env strings %d", num_env); 329 for(i = 0; i < num_env; i++) 330 sshpam_env[i] = buffer_get_string(b, NULL); 331 332 sshpam_env[num_env] = NULL; 333 334 /* Import PAM environment from subprocess */ 335 num_env = buffer_get_int(b); 336 debug("PAM: num PAM env strings %d", num_env); 337 for(i = 0; i < num_env; i++) { 338 env = buffer_get_string(b, NULL); 339 340 #ifdef HAVE_PAM_PUTENV 341 /* Errors are not fatal here */ 342 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 343 error("PAM: pam_putenv: %s", 344 pam_strerror(sshpam_handle, sshpam_err)); 345 } 346 #endif 347 } 348 #endif 349 } 350 351 /* 352 * Conversation function for authentication thread. 353 */ 354 static int 355 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 356 struct pam_response **resp, void *data) 357 { 358 Buffer buffer; 359 struct pam_ctxt *ctxt; 360 struct pam_response *reply; 361 int i; 362 363 debug3("PAM: %s entering, %d messages", __func__, n); 364 *resp = NULL; 365 366 if (data == NULL) { 367 error("PAM: conversation function passed a null context"); 368 return (PAM_CONV_ERR); 369 } 370 ctxt = data; 371 if (n <= 0 || n > PAM_MAX_NUM_MSG) 372 return (PAM_CONV_ERR); 373 374 if ((reply = calloc(n, sizeof(*reply))) == NULL) 375 return (PAM_CONV_ERR); 376 377 buffer_init(&buffer); 378 for (i = 0; i < n; ++i) { 379 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 380 case PAM_PROMPT_ECHO_OFF: 381 case PAM_PROMPT_ECHO_ON: 382 buffer_put_cstring(&buffer, 383 PAM_MSG_MEMBER(msg, i, msg)); 384 if (ssh_msg_send(ctxt->pam_csock, 385 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 386 goto fail; 387 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 388 goto fail; 389 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 390 goto fail; 391 reply[i].resp = buffer_get_string(&buffer, NULL); 392 break; 393 case PAM_ERROR_MSG: 394 case PAM_TEXT_INFO: 395 buffer_put_cstring(&buffer, 396 PAM_MSG_MEMBER(msg, i, msg)); 397 if (ssh_msg_send(ctxt->pam_csock, 398 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 399 goto fail; 400 break; 401 default: 402 goto fail; 403 } 404 buffer_clear(&buffer); 405 } 406 buffer_free(&buffer); 407 *resp = reply; 408 return (PAM_SUCCESS); 409 410 fail: 411 for(i = 0; i < n; i++) { 412 free(reply[i].resp); 413 } 414 free(reply); 415 buffer_free(&buffer); 416 return (PAM_CONV_ERR); 417 } 418 419 /* 420 * Authentication thread. 421 */ 422 static void * 423 sshpam_thread(void *ctxtp) 424 { 425 struct pam_ctxt *ctxt = ctxtp; 426 Buffer buffer; 427 struct pam_conv sshpam_conv; 428 int flags = (options.permit_empty_passwd == 0 ? 429 PAM_DISALLOW_NULL_AUTHTOK : 0); 430 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 431 extern char **environ; 432 char **env_from_pam; 433 u_int i; 434 const char *pam_user; 435 const char **ptr_pam_user = &pam_user; 436 char *tz = getenv("TZ"); 437 438 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 439 (sshpam_const void **)ptr_pam_user); 440 if (sshpam_err != PAM_SUCCESS) 441 goto auth_fail; 442 443 environ[0] = NULL; 444 if (tz != NULL) 445 if (setenv("TZ", tz, 1) == -1) 446 error("PAM: could not set TZ environment: %s", 447 strerror(errno)); 448 449 if (sshpam_authctxt != NULL) { 450 setproctitle("%s [pam]", 451 sshpam_authctxt->valid ? pam_user : "unknown"); 452 } 453 #endif 454 455 sshpam_conv.conv = sshpam_thread_conv; 456 sshpam_conv.appdata_ptr = ctxt; 457 458 if (sshpam_authctxt == NULL) 459 fatal("%s: PAM authctxt not initialized", __func__); 460 461 buffer_init(&buffer); 462 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 463 (const void *)&sshpam_conv); 464 if (sshpam_err != PAM_SUCCESS) 465 goto auth_fail; 466 sshpam_err = pam_authenticate(sshpam_handle, flags); 467 if (sshpam_err == PAM_MAXTRIES) 468 sshpam_set_maxtries_reached(1); 469 if (sshpam_err != PAM_SUCCESS) 470 goto auth_fail; 471 472 if (compat20) { 473 if (!do_pam_account()) { 474 sshpam_err = PAM_ACCT_EXPIRED; 475 goto auth_fail; 476 } 477 if (sshpam_authctxt->force_pwchange) { 478 sshpam_err = pam_chauthtok(sshpam_handle, 479 PAM_CHANGE_EXPIRED_AUTHTOK); 480 if (sshpam_err != PAM_SUCCESS) 481 goto auth_fail; 482 sshpam_password_change_required(0); 483 } 484 } 485 486 buffer_put_cstring(&buffer, "OK"); 487 488 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 489 /* Export variables set by do_pam_account */ 490 buffer_put_int(&buffer, sshpam_account_status); 491 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange); 492 493 /* Export any environment strings set in child */ 494 for(i = 0; environ[i] != NULL; i++) 495 ; /* Count */ 496 buffer_put_int(&buffer, i); 497 for(i = 0; environ[i] != NULL; i++) 498 buffer_put_cstring(&buffer, environ[i]); 499 500 /* Export any environment strings set by PAM in child */ 501 env_from_pam = pam_getenvlist(sshpam_handle); 502 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 503 ; /* Count */ 504 buffer_put_int(&buffer, i); 505 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 506 buffer_put_cstring(&buffer, env_from_pam[i]); 507 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 508 509 /* XXX - can't do much about an error here */ 510 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); 511 buffer_free(&buffer); 512 pthread_exit(NULL); 513 514 auth_fail: 515 buffer_put_cstring(&buffer, 516 pam_strerror(sshpam_handle, sshpam_err)); 517 /* XXX - can't do much about an error here */ 518 if (sshpam_err == PAM_ACCT_EXPIRED) 519 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer); 520 else if (sshpam_maxtries_reached) 521 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, &buffer); 522 else 523 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); 524 buffer_free(&buffer); 525 pthread_exit(NULL); 526 527 return (NULL); /* Avoid warning for non-pthread case */ 528 } 529 530 void 531 sshpam_thread_cleanup(void) 532 { 533 struct pam_ctxt *ctxt = cleanup_ctxt; 534 535 debug3("PAM: %s entering", __func__); 536 if (ctxt != NULL && ctxt->pam_thread != 0) { 537 pthread_cancel(ctxt->pam_thread); 538 pthread_join(ctxt->pam_thread, NULL); 539 close(ctxt->pam_psock); 540 close(ctxt->pam_csock); 541 memset(ctxt, 0, sizeof(*ctxt)); 542 cleanup_ctxt = NULL; 543 } 544 } 545 546 static int 547 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 548 struct pam_response **resp, void *data) 549 { 550 debug3("PAM: %s entering, %d messages", __func__, n); 551 return (PAM_CONV_ERR); 552 } 553 554 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 555 556 static int 557 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 558 struct pam_response **resp, void *data) 559 { 560 struct pam_response *reply; 561 int i; 562 size_t len; 563 564 debug3("PAM: %s called with %d messages", __func__, n); 565 *resp = NULL; 566 567 if (n <= 0 || n > PAM_MAX_NUM_MSG) 568 return (PAM_CONV_ERR); 569 570 if ((reply = calloc(n, sizeof(*reply))) == NULL) 571 return (PAM_CONV_ERR); 572 573 for (i = 0; i < n; ++i) { 574 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 575 case PAM_ERROR_MSG: 576 case PAM_TEXT_INFO: 577 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 578 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len); 579 buffer_append(&loginmsg, "\n", 1 ); 580 reply[i].resp_retcode = PAM_SUCCESS; 581 break; 582 default: 583 goto fail; 584 } 585 } 586 *resp = reply; 587 return (PAM_SUCCESS); 588 589 fail: 590 for(i = 0; i < n; i++) { 591 free(reply[i].resp); 592 } 593 free(reply); 594 return (PAM_CONV_ERR); 595 } 596 597 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 598 599 void 600 sshpam_cleanup(void) 601 { 602 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 603 return; 604 debug("PAM: cleanup"); 605 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 606 if (sshpam_session_open) { 607 debug("PAM: closing session"); 608 pam_close_session(sshpam_handle, PAM_SILENT); 609 sshpam_session_open = 0; 610 } 611 if (sshpam_cred_established) { 612 debug("PAM: deleting credentials"); 613 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 614 sshpam_cred_established = 0; 615 } 616 sshpam_authenticated = 0; 617 pam_end(sshpam_handle, sshpam_err); 618 sshpam_handle = NULL; 619 } 620 621 static int 622 sshpam_init(Authctxt *authctxt) 623 { 624 const char *pam_rhost, *pam_user, *user = authctxt->user; 625 const char **ptr_pam_user = &pam_user; 626 struct ssh *ssh = active_state; /* XXX */ 627 628 if (sshpam_handle != NULL) { 629 /* We already have a PAM context; check if the user matches */ 630 sshpam_err = pam_get_item(sshpam_handle, 631 PAM_USER, (sshpam_const void **)ptr_pam_user); 632 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 633 return (0); 634 pam_end(sshpam_handle, sshpam_err); 635 sshpam_handle = NULL; 636 } 637 debug("PAM: initializing for \"%s\"", user); 638 sshpam_err = 639 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 640 sshpam_authctxt = authctxt; 641 642 if (sshpam_err != PAM_SUCCESS) { 643 pam_end(sshpam_handle, sshpam_err); 644 sshpam_handle = NULL; 645 return (-1); 646 } 647 pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns); 648 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 649 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 650 if (sshpam_err != PAM_SUCCESS) { 651 pam_end(sshpam_handle, sshpam_err); 652 sshpam_handle = NULL; 653 return (-1); 654 } 655 #ifdef PAM_TTY_KLUDGE 656 /* 657 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 658 * sshd doesn't set the tty until too late in the auth process and 659 * may not even set one (for tty-less connections) 660 */ 661 debug("PAM: setting PAM_TTY to \"ssh\""); 662 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 663 if (sshpam_err != PAM_SUCCESS) { 664 pam_end(sshpam_handle, sshpam_err); 665 sshpam_handle = NULL; 666 return (-1); 667 } 668 #endif 669 return (0); 670 } 671 672 static void * 673 sshpam_init_ctx(Authctxt *authctxt) 674 { 675 struct pam_ctxt *ctxt; 676 int socks[2]; 677 678 debug3("PAM: %s entering", __func__); 679 /* 680 * Refuse to start if we don't have PAM enabled or do_pam_account 681 * has previously failed. 682 */ 683 if (!options.use_pam || sshpam_account_status == 0) 684 return NULL; 685 686 /* Initialize PAM */ 687 if (sshpam_init(authctxt) == -1) { 688 error("PAM: initialization failed"); 689 return (NULL); 690 } 691 692 ctxt = xcalloc(1, sizeof *ctxt); 693 694 /* Start the authentication thread */ 695 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 696 error("PAM: failed create sockets: %s", strerror(errno)); 697 free(ctxt); 698 return (NULL); 699 } 700 ctxt->pam_psock = socks[0]; 701 ctxt->pam_csock = socks[1]; 702 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 703 error("PAM: failed to start authentication thread: %s", 704 strerror(errno)); 705 close(socks[0]); 706 close(socks[1]); 707 free(ctxt); 708 return (NULL); 709 } 710 cleanup_ctxt = ctxt; 711 return (ctxt); 712 } 713 714 static int 715 sshpam_query(void *ctx, char **name, char **info, 716 u_int *num, char ***prompts, u_int **echo_on) 717 { 718 struct ssh *ssh = active_state; /* XXX */ 719 Buffer buffer; 720 struct pam_ctxt *ctxt = ctx; 721 size_t plen; 722 u_char type; 723 char *msg; 724 size_t len, mlen; 725 726 debug3("PAM: %s entering", __func__); 727 buffer_init(&buffer); 728 *name = xstrdup(""); 729 *info = xstrdup(""); 730 *prompts = xmalloc(sizeof(char *)); 731 **prompts = NULL; 732 plen = 0; 733 *echo_on = xmalloc(sizeof(u_int)); 734 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { 735 type = buffer_get_char(&buffer); 736 msg = buffer_get_string(&buffer, NULL); 737 mlen = strlen(msg); 738 switch (type) { 739 case PAM_PROMPT_ECHO_ON: 740 case PAM_PROMPT_ECHO_OFF: 741 *num = 1; 742 len = plen + mlen + 1; 743 **prompts = xreallocarray(**prompts, 1, len); 744 strlcpy(**prompts + plen, msg, len - plen); 745 plen += mlen; 746 **echo_on = (type == PAM_PROMPT_ECHO_ON); 747 free(msg); 748 return (0); 749 case PAM_ERROR_MSG: 750 case PAM_TEXT_INFO: 751 /* accumulate messages */ 752 len = plen + mlen + 2; 753 **prompts = xreallocarray(**prompts, 1, len); 754 strlcpy(**prompts + plen, msg, len - plen); 755 plen += mlen; 756 strlcat(**prompts + plen, "\n", len - plen); 757 plen++; 758 free(msg); 759 break; 760 case PAM_ACCT_EXPIRED: 761 case PAM_MAXTRIES: 762 if (type == PAM_ACCT_EXPIRED) 763 sshpam_account_status = 0; 764 if (type == PAM_MAXTRIES) 765 sshpam_set_maxtries_reached(1); 766 /* FALLTHROUGH */ 767 case PAM_AUTH_ERR: 768 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 769 if (**prompts != NULL && strlen(**prompts) != 0) { 770 *info = **prompts; 771 **prompts = NULL; 772 *num = 0; 773 **echo_on = 0; 774 ctxt->pam_done = -1; 775 free(msg); 776 return 0; 777 } 778 /* FALLTHROUGH */ 779 case PAM_SUCCESS: 780 if (**prompts != NULL) { 781 /* drain any accumulated messages */ 782 debug("PAM: %s", **prompts); 783 buffer_append(&loginmsg, **prompts, 784 strlen(**prompts)); 785 free(**prompts); 786 **prompts = NULL; 787 } 788 if (type == PAM_SUCCESS) { 789 if (!sshpam_authctxt->valid || 790 (sshpam_authctxt->pw->pw_uid == 0 && 791 options.permit_root_login != PERMIT_YES)) 792 fatal("Internal error: PAM auth " 793 "succeeded when it should have " 794 "failed"); 795 import_environments(&buffer); 796 *num = 0; 797 **echo_on = 0; 798 ctxt->pam_done = 1; 799 free(msg); 800 return (0); 801 } 802 BLACKLIST_NOTIFY(BLACKLIST_BAD_USER, 803 sshpam_authctxt->user); 804 error("PAM: %s for %s%.100s from %.100s", msg, 805 sshpam_authctxt->valid ? "" : "illegal user ", 806 sshpam_authctxt->user, 807 auth_get_canonical_hostname(ssh, options.use_dns)); 808 /* FALLTHROUGH */ 809 default: 810 *num = 0; 811 **echo_on = 0; 812 free(msg); 813 ctxt->pam_done = -1; 814 return (-1); 815 } 816 } 817 return (-1); 818 } 819 820 /* 821 * Returns a junk password of identical length to that the user supplied. 822 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 823 * vary processing time in proportion to password length. 824 */ 825 static char * 826 fake_password(const char *wire_password) 827 { 828 const char junk[] = "\b\n\r\177INCORRECT"; 829 char *ret = NULL; 830 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 831 832 if (l >= INT_MAX) 833 fatal("%s: password length too long: %zu", __func__, l); 834 835 ret = malloc(l + 1); 836 if (ret == NULL) 837 return NULL; 838 for (i = 0; i < l; i++) 839 ret[i] = junk[i % (sizeof(junk) - 1)]; 840 ret[i] = '\0'; 841 return ret; 842 } 843 844 /* XXX - see also comment in auth-chall.c:verify_response */ 845 static int 846 sshpam_respond(void *ctx, u_int num, char **resp) 847 { 848 Buffer buffer; 849 struct pam_ctxt *ctxt = ctx; 850 char *fake; 851 852 debug2("PAM: %s entering, %u responses", __func__, num); 853 switch (ctxt->pam_done) { 854 case 1: 855 sshpam_authenticated = 1; 856 return (0); 857 case 0: 858 break; 859 default: 860 return (-1); 861 } 862 if (num != 1) { 863 error("PAM: expected one response, got %u", num); 864 return (-1); 865 } 866 buffer_init(&buffer); 867 if (sshpam_authctxt->valid && 868 (sshpam_authctxt->pw->pw_uid != 0 || 869 options.permit_root_login == PERMIT_YES)) 870 buffer_put_cstring(&buffer, *resp); 871 else { 872 fake = fake_password(*resp); 873 buffer_put_cstring(&buffer, fake); 874 free(fake); 875 } 876 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 877 buffer_free(&buffer); 878 return (-1); 879 } 880 buffer_free(&buffer); 881 return (1); 882 } 883 884 static void 885 sshpam_free_ctx(void *ctxtp) 886 { 887 struct pam_ctxt *ctxt = ctxtp; 888 889 debug3("PAM: %s entering", __func__); 890 sshpam_thread_cleanup(); 891 free(ctxt); 892 /* 893 * We don't call sshpam_cleanup() here because we may need the PAM 894 * handle at a later stage, e.g. when setting up a session. It's 895 * still on the cleanup list, so pam_end() *will* be called before 896 * the server process terminates. 897 */ 898 } 899 900 KbdintDevice sshpam_device = { 901 "pam", 902 sshpam_init_ctx, 903 sshpam_query, 904 sshpam_respond, 905 sshpam_free_ctx 906 }; 907 908 KbdintDevice mm_sshpam_device = { 909 "pam", 910 mm_sshpam_init_ctx, 911 mm_sshpam_query, 912 mm_sshpam_respond, 913 mm_sshpam_free_ctx 914 }; 915 916 /* 917 * This replaces auth-pam.c 918 */ 919 void 920 start_pam(Authctxt *authctxt) 921 { 922 if (!options.use_pam) 923 fatal("PAM: initialisation requested when UsePAM=no"); 924 925 if (sshpam_init(authctxt) == -1) 926 fatal("PAM: initialisation failed"); 927 } 928 929 void 930 finish_pam(void) 931 { 932 sshpam_cleanup(); 933 } 934 935 u_int 936 do_pam_account(void) 937 { 938 debug("%s: called", __func__); 939 if (sshpam_account_status != -1) 940 return (sshpam_account_status); 941 942 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 943 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 944 pam_strerror(sshpam_handle, sshpam_err)); 945 946 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 947 sshpam_account_status = 0; 948 return (sshpam_account_status); 949 } 950 951 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 952 sshpam_password_change_required(1); 953 954 sshpam_account_status = 1; 955 return (sshpam_account_status); 956 } 957 958 void 959 do_pam_setcred(int init) 960 { 961 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 962 (const void *)&store_conv); 963 if (sshpam_err != PAM_SUCCESS) 964 fatal("PAM: failed to set PAM_CONV: %s", 965 pam_strerror(sshpam_handle, sshpam_err)); 966 if (init) { 967 debug("PAM: establishing credentials"); 968 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 969 } else { 970 debug("PAM: reinitializing credentials"); 971 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 972 } 973 if (sshpam_err == PAM_SUCCESS) { 974 sshpam_cred_established = 1; 975 return; 976 } 977 if (sshpam_authenticated) 978 fatal("PAM: pam_setcred(): %s", 979 pam_strerror(sshpam_handle, sshpam_err)); 980 else 981 debug("PAM: pam_setcred(): %s", 982 pam_strerror(sshpam_handle, sshpam_err)); 983 } 984 985 static int 986 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 987 struct pam_response **resp, void *data) 988 { 989 char input[PAM_MAX_MSG_SIZE]; 990 struct pam_response *reply; 991 int i; 992 993 debug3("PAM: %s called with %d messages", __func__, n); 994 995 *resp = NULL; 996 997 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 998 return (PAM_CONV_ERR); 999 1000 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1001 return (PAM_CONV_ERR); 1002 1003 for (i = 0; i < n; ++i) { 1004 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1005 case PAM_PROMPT_ECHO_OFF: 1006 reply[i].resp = 1007 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1008 RP_ALLOW_STDIN); 1009 reply[i].resp_retcode = PAM_SUCCESS; 1010 break; 1011 case PAM_PROMPT_ECHO_ON: 1012 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1013 if (fgets(input, sizeof input, stdin) == NULL) 1014 input[0] = '\0'; 1015 if ((reply[i].resp = strdup(input)) == NULL) 1016 goto fail; 1017 reply[i].resp_retcode = PAM_SUCCESS; 1018 break; 1019 case PAM_ERROR_MSG: 1020 case PAM_TEXT_INFO: 1021 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1022 reply[i].resp_retcode = PAM_SUCCESS; 1023 break; 1024 default: 1025 goto fail; 1026 } 1027 } 1028 *resp = reply; 1029 return (PAM_SUCCESS); 1030 1031 fail: 1032 for(i = 0; i < n; i++) { 1033 free(reply[i].resp); 1034 } 1035 free(reply); 1036 return (PAM_CONV_ERR); 1037 } 1038 1039 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1040 1041 /* 1042 * XXX this should be done in the authentication phase, but ssh1 doesn't 1043 * support that 1044 */ 1045 void 1046 do_pam_chauthtok(void) 1047 { 1048 if (use_privsep) 1049 fatal("Password expired (unable to change with privsep)"); 1050 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1051 (const void *)&tty_conv); 1052 if (sshpam_err != PAM_SUCCESS) 1053 fatal("PAM: failed to set PAM_CONV: %s", 1054 pam_strerror(sshpam_handle, sshpam_err)); 1055 debug("PAM: changing password"); 1056 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1057 if (sshpam_err != PAM_SUCCESS) 1058 fatal("PAM: pam_chauthtok(): %s", 1059 pam_strerror(sshpam_handle, sshpam_err)); 1060 } 1061 1062 void 1063 do_pam_session(void) 1064 { 1065 debug3("PAM: opening session"); 1066 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1067 (const void *)&store_conv); 1068 if (sshpam_err != PAM_SUCCESS) 1069 fatal("PAM: failed to set PAM_CONV: %s", 1070 pam_strerror(sshpam_handle, sshpam_err)); 1071 sshpam_err = pam_open_session(sshpam_handle, 0); 1072 if (sshpam_err == PAM_SUCCESS) 1073 sshpam_session_open = 1; 1074 else { 1075 sshpam_session_open = 0; 1076 disable_forwarding(); 1077 error("PAM: pam_open_session(): %s", 1078 pam_strerror(sshpam_handle, sshpam_err)); 1079 } 1080 1081 } 1082 1083 int 1084 is_pam_session_open(void) 1085 { 1086 return sshpam_session_open; 1087 } 1088 1089 /* 1090 * Set a PAM environment string. We need to do this so that the session 1091 * modules can handle things like Kerberos/GSI credentials that appear 1092 * during the ssh authentication process. 1093 */ 1094 int 1095 do_pam_putenv(char *name, char *value) 1096 { 1097 int ret = 1; 1098 #ifdef HAVE_PAM_PUTENV 1099 char *compound; 1100 size_t len; 1101 1102 len = strlen(name) + strlen(value) + 2; 1103 compound = xmalloc(len); 1104 1105 snprintf(compound, len, "%s=%s", name, value); 1106 ret = pam_putenv(sshpam_handle, compound); 1107 free(compound); 1108 #endif 1109 1110 return (ret); 1111 } 1112 1113 char ** 1114 fetch_pam_child_environment(void) 1115 { 1116 return sshpam_env; 1117 } 1118 1119 char ** 1120 fetch_pam_environment(void) 1121 { 1122 return (pam_getenvlist(sshpam_handle)); 1123 } 1124 1125 void 1126 free_pam_environment(char **env) 1127 { 1128 char **envp; 1129 1130 if (env == NULL) 1131 return; 1132 1133 for (envp = env; *envp; envp++) 1134 free(*envp); 1135 free(env); 1136 } 1137 1138 /* 1139 * "Blind" conversation function for password authentication. Assumes that 1140 * echo-off prompts are for the password and stores messages for later 1141 * display. 1142 */ 1143 static int 1144 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1145 struct pam_response **resp, void *data) 1146 { 1147 struct pam_response *reply; 1148 int i; 1149 size_t len; 1150 1151 debug3("PAM: %s called with %d messages", __func__, n); 1152 1153 *resp = NULL; 1154 1155 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1156 return (PAM_CONV_ERR); 1157 1158 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1159 return (PAM_CONV_ERR); 1160 1161 for (i = 0; i < n; ++i) { 1162 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1163 case PAM_PROMPT_ECHO_OFF: 1164 if (sshpam_password == NULL) 1165 goto fail; 1166 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1167 goto fail; 1168 reply[i].resp_retcode = PAM_SUCCESS; 1169 break; 1170 case PAM_ERROR_MSG: 1171 case PAM_TEXT_INFO: 1172 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1173 if (len > 0) { 1174 buffer_append(&loginmsg, 1175 PAM_MSG_MEMBER(msg, i, msg), len); 1176 buffer_append(&loginmsg, "\n", 1); 1177 } 1178 if ((reply[i].resp = strdup("")) == NULL) 1179 goto fail; 1180 reply[i].resp_retcode = PAM_SUCCESS; 1181 break; 1182 default: 1183 goto fail; 1184 } 1185 } 1186 *resp = reply; 1187 return (PAM_SUCCESS); 1188 1189 fail: 1190 for(i = 0; i < n; i++) { 1191 free(reply[i].resp); 1192 } 1193 free(reply); 1194 return (PAM_CONV_ERR); 1195 } 1196 1197 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1198 1199 /* 1200 * Attempt password authentication via PAM 1201 */ 1202 int 1203 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1204 { 1205 int flags = (options.permit_empty_passwd == 0 ? 1206 PAM_DISALLOW_NULL_AUTHTOK : 0); 1207 char *fake = NULL; 1208 1209 if (!options.use_pam || sshpam_handle == NULL) 1210 fatal("PAM: %s called when PAM disabled or failed to " 1211 "initialise.", __func__); 1212 1213 sshpam_password = password; 1214 sshpam_authctxt = authctxt; 1215 1216 /* 1217 * If the user logging in is invalid, or is root but is not permitted 1218 * by PermitRootLogin, use an invalid password to prevent leaking 1219 * information via timing (eg if the PAM config has a delay on fail). 1220 */ 1221 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1222 options.permit_root_login != PERMIT_YES)) 1223 sshpam_password = fake = fake_password(password); 1224 1225 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1226 (const void *)&passwd_conv); 1227 if (sshpam_err != PAM_SUCCESS) 1228 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1229 pam_strerror(sshpam_handle, sshpam_err)); 1230 1231 sshpam_err = pam_authenticate(sshpam_handle, flags); 1232 sshpam_password = NULL; 1233 free(fake); 1234 if (sshpam_err == PAM_MAXTRIES) 1235 sshpam_set_maxtries_reached(1); 1236 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1237 debug("PAM: password authentication accepted for %.100s", 1238 authctxt->user); 1239 return 1; 1240 } else { 1241 debug("PAM: password authentication failed for %.100s: %s", 1242 authctxt->valid ? authctxt->user : "an illegal user", 1243 pam_strerror(sshpam_handle, sshpam_err)); 1244 return 0; 1245 } 1246 } 1247 1248 int 1249 sshpam_get_maxtries_reached(void) 1250 { 1251 return sshpam_maxtries_reached; 1252 } 1253 1254 void 1255 sshpam_set_maxtries_reached(int reached) 1256 { 1257 if (reached == 0 || sshpam_maxtries_reached) 1258 return; 1259 sshpam_maxtries_reached = 1; 1260 options.password_authentication = 0; 1261 options.kbd_interactive_authentication = 0; 1262 options.challenge_response_authentication = 0; 1263 } 1264 #endif /* USE_PAM */ 1265