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 "sshbuf.h" 90 #include "ssherr.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 struct sshbuf *loginmsg; 110 extern u_int utmp_len; 111 112 /* so we don't silently change behaviour */ 113 #ifdef USE_POSIX_THREADS 114 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 115 #endif 116 117 /* 118 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 119 * and generally a bad idea. Use at own risk and do not expect support if 120 * this breaks. 121 */ 122 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 123 #include <pthread.h> 124 /* 125 * Avoid namespace clash when *not* using pthreads for systems *with* 126 * pthreads, which unconditionally define pthread_t via sys/types.h 127 * (e.g. Linux) 128 */ 129 typedef pthread_t sp_pthread_t; 130 #else 131 typedef pid_t sp_pthread_t; 132 #endif 133 134 struct pam_ctxt { 135 sp_pthread_t pam_thread; 136 int pam_psock; 137 int pam_csock; 138 int pam_done; 139 }; 140 141 static void sshpam_free_ctx(void *); 142 static struct pam_ctxt *cleanup_ctxt; 143 144 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 145 /* 146 * Simulate threads with processes. 147 */ 148 149 static int sshpam_thread_status = -1; 150 static mysig_t sshpam_oldsig; 151 152 static void 153 sshpam_sigchld_handler(int sig) 154 { 155 signal(SIGCHLD, SIG_DFL); 156 if (cleanup_ctxt == NULL) 157 return; /* handler called after PAM cleanup, shouldn't happen */ 158 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 159 <= 0) { 160 /* PAM thread has not exitted, privsep slave must have */ 161 kill(cleanup_ctxt->pam_thread, SIGTERM); 162 while (waitpid(cleanup_ctxt->pam_thread, 163 &sshpam_thread_status, 0) == -1) { 164 if (errno == EINTR) 165 continue; 166 return; 167 } 168 } 169 if (WIFSIGNALED(sshpam_thread_status) && 170 WTERMSIG(sshpam_thread_status) == SIGTERM) 171 return; /* terminated by pthread_cancel */ 172 if (!WIFEXITED(sshpam_thread_status)) 173 sigdie("PAM: authentication thread exited unexpectedly"); 174 if (WEXITSTATUS(sshpam_thread_status) != 0) 175 sigdie("PAM: authentication thread exited uncleanly"); 176 } 177 178 /* ARGSUSED */ 179 static void 180 pthread_exit(void *value) 181 { 182 _exit(0); 183 } 184 185 /* ARGSUSED */ 186 static int 187 pthread_create(sp_pthread_t *thread, const void *attr, 188 void *(*thread_start)(void *), void *arg) 189 { 190 pid_t pid; 191 struct pam_ctxt *ctx = arg; 192 193 sshpam_thread_status = -1; 194 switch ((pid = fork())) { 195 case -1: 196 error("fork(): %s", strerror(errno)); 197 return (-1); 198 case 0: 199 close(ctx->pam_psock); 200 ctx->pam_psock = -1; 201 thread_start(arg); 202 _exit(1); 203 default: 204 *thread = pid; 205 close(ctx->pam_csock); 206 ctx->pam_csock = -1; 207 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler); 208 return (0); 209 } 210 } 211 212 static int 213 pthread_cancel(sp_pthread_t thread) 214 { 215 signal(SIGCHLD, sshpam_oldsig); 216 return (kill(thread, SIGTERM)); 217 } 218 219 /* ARGSUSED */ 220 static int 221 pthread_join(sp_pthread_t thread, void **value) 222 { 223 int status; 224 225 if (sshpam_thread_status != -1) 226 return (sshpam_thread_status); 227 signal(SIGCHLD, sshpam_oldsig); 228 while (waitpid(thread, &status, 0) == -1) { 229 if (errno == EINTR) 230 continue; 231 fatal("%s: waitpid: %s", __func__, strerror(errno)); 232 } 233 return (status); 234 } 235 #endif 236 237 238 static pam_handle_t *sshpam_handle = NULL; 239 static int sshpam_err = 0; 240 static int sshpam_authenticated = 0; 241 static int sshpam_session_open = 0; 242 static int sshpam_cred_established = 0; 243 static int sshpam_account_status = -1; 244 static int sshpam_maxtries_reached = 0; 245 static char **sshpam_env = NULL; 246 static Authctxt *sshpam_authctxt = NULL; 247 static const char *sshpam_password = NULL; 248 249 /* Some PAM implementations don't implement this */ 250 #ifndef HAVE_PAM_GETENVLIST 251 static char ** 252 pam_getenvlist(pam_handle_t *pamh) 253 { 254 /* 255 * XXX - If necessary, we can still support envrionment passing 256 * for platforms without pam_getenvlist by searching for known 257 * env vars (e.g. KRB5CCNAME) from the PAM environment. 258 */ 259 return NULL; 260 } 261 #endif 262 263 /* 264 * Some platforms, notably Solaris, do not enforce password complexity 265 * rules during pam_chauthtok() if the real uid of the calling process 266 * is 0, on the assumption that it's being called by "passwd" run by root. 267 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 268 * the right thing. 269 */ 270 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 271 static int 272 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 273 { 274 int result; 275 276 if (sshpam_authctxt == NULL) 277 fatal("PAM: sshpam_authctxt not initialized"); 278 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 279 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 280 result = pam_chauthtok(pamh, flags); 281 if (setreuid(0, -1) == -1) 282 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 283 return result; 284 } 285 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 286 #endif 287 288 void 289 sshpam_password_change_required(int reqd) 290 { 291 extern struct sshauthopt *auth_opts; 292 static int saved_port, saved_agent, saved_x11; 293 294 debug3("%s %d", __func__, reqd); 295 if (sshpam_authctxt == NULL) 296 fatal("%s: PAM authctxt not initialized", __func__); 297 sshpam_authctxt->force_pwchange = reqd; 298 if (reqd) { 299 saved_port = auth_opts->permit_port_forwarding_flag; 300 saved_agent = auth_opts->permit_agent_forwarding_flag; 301 saved_x11 = auth_opts->permit_x11_forwarding_flag; 302 auth_opts->permit_port_forwarding_flag = 0; 303 auth_opts->permit_agent_forwarding_flag = 0; 304 auth_opts->permit_x11_forwarding_flag = 0; 305 } else { 306 if (saved_port) 307 auth_opts->permit_port_forwarding_flag = saved_port; 308 if (saved_agent) 309 auth_opts->permit_agent_forwarding_flag = saved_agent; 310 if (saved_x11) 311 auth_opts->permit_x11_forwarding_flag = saved_x11; 312 } 313 } 314 315 /* Import regular and PAM environment from subprocess */ 316 static void 317 import_environments(struct sshbuf *b) 318 { 319 char *env; 320 u_int n, i, num_env; 321 int r; 322 323 debug3("PAM: %s entering", __func__); 324 325 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 326 /* Import variables set by do_pam_account */ 327 if ((r = sshbuf_get_u32(b, &n)) != 0) 328 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 329 if (n > INT_MAX) 330 fatal("%s: invalid PAM account status %u", __func__, n); 331 sshpam_account_status = (int)n; 332 if ((r = sshbuf_get_u32(b, &n)) != 0) 333 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 334 sshpam_password_change_required(n != 0); 335 336 /* Import environment from subprocess */ 337 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 338 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 339 if (num_env > 1024) 340 fatal("%s: received %u environment variables, expected <= 1024", 341 __func__, num_env); 342 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 343 debug3("PAM: num env strings %d", num_env); 344 for(i = 0; i < num_env; i++) { 345 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0) 346 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 347 } 348 sshpam_env[num_env] = NULL; 349 350 /* Import PAM environment from subprocess */ 351 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 352 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 353 debug("PAM: num PAM env strings %d", num_env); 354 for (i = 0; i < num_env; i++) { 355 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0) 356 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 357 #ifdef HAVE_PAM_PUTENV 358 /* Errors are not fatal here */ 359 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 360 error("PAM: pam_putenv: %s", 361 pam_strerror(sshpam_handle, r)); 362 } 363 #endif 364 /* XXX leak env? */ 365 } 366 #endif 367 } 368 369 /* 370 * Conversation function for authentication thread. 371 */ 372 static int 373 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 374 struct pam_response **resp, void *data) 375 { 376 struct sshbuf *buffer; 377 struct pam_ctxt *ctxt; 378 struct pam_response *reply; 379 int r, i; 380 u_char status; 381 382 debug3("PAM: %s entering, %d messages", __func__, n); 383 *resp = NULL; 384 385 if (data == NULL) { 386 error("PAM: conversation function passed a null context"); 387 return (PAM_CONV_ERR); 388 } 389 ctxt = data; 390 if (n <= 0 || n > PAM_MAX_NUM_MSG) 391 return (PAM_CONV_ERR); 392 393 if ((reply = calloc(n, sizeof(*reply))) == NULL) 394 return PAM_CONV_ERR; 395 if ((buffer = sshbuf_new()) == NULL) { 396 free(reply); 397 return PAM_CONV_ERR; 398 } 399 400 for (i = 0; i < n; ++i) { 401 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 402 case PAM_PROMPT_ECHO_OFF: 403 case PAM_PROMPT_ECHO_ON: 404 if ((r = sshbuf_put_cstring(buffer, 405 PAM_MSG_MEMBER(msg, i, msg))) != 0) 406 fatal("%s: buffer error: %s", 407 __func__, ssh_err(r)); 408 if (ssh_msg_send(ctxt->pam_csock, 409 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 410 goto fail; 411 412 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 413 goto fail; 414 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 415 fatal("%s: buffer error: %s", 416 __func__, ssh_err(r)); 417 if (status != PAM_AUTHTOK) 418 goto fail; 419 if ((r = sshbuf_get_cstring(buffer, 420 &reply[i].resp, NULL)) != 0) 421 fatal("%s: buffer error: %s", 422 __func__, ssh_err(r)); 423 break; 424 case PAM_ERROR_MSG: 425 case PAM_TEXT_INFO: 426 if ((r = sshbuf_put_cstring(buffer, 427 PAM_MSG_MEMBER(msg, i, msg))) != 0) 428 fatal("%s: buffer error: %s", 429 __func__, ssh_err(r)); 430 if (ssh_msg_send(ctxt->pam_csock, 431 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 432 goto fail; 433 break; 434 default: 435 goto fail; 436 } 437 sshbuf_reset(buffer); 438 } 439 sshbuf_free(buffer); 440 *resp = reply; 441 return (PAM_SUCCESS); 442 443 fail: 444 for(i = 0; i < n; i++) { 445 free(reply[i].resp); 446 } 447 free(reply); 448 sshbuf_free(buffer); 449 return (PAM_CONV_ERR); 450 } 451 452 /* 453 * Authentication thread. 454 */ 455 static void * 456 sshpam_thread(void *ctxtp) 457 { 458 struct pam_ctxt *ctxt = ctxtp; 459 struct sshbuf *buffer = NULL; 460 struct pam_conv sshpam_conv; 461 int r, flags = (options.permit_empty_passwd == 0 ? 462 PAM_DISALLOW_NULL_AUTHTOK : 0); 463 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 464 extern char **environ; 465 char **env_from_pam; 466 u_int i; 467 const char *pam_user; 468 const char **ptr_pam_user = &pam_user; 469 char *tz = getenv("TZ"); 470 471 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 472 (sshpam_const void **)ptr_pam_user); 473 if (sshpam_err != PAM_SUCCESS) 474 goto auth_fail; 475 476 environ[0] = NULL; 477 if (tz != NULL) 478 if (setenv("TZ", tz, 1) == -1) 479 error("PAM: could not set TZ environment: %s", 480 strerror(errno)); 481 482 if (sshpam_authctxt != NULL) { 483 setproctitle("%s [pam]", 484 sshpam_authctxt->valid ? pam_user : "unknown"); 485 } 486 #endif 487 488 sshpam_conv.conv = sshpam_thread_conv; 489 sshpam_conv.appdata_ptr = ctxt; 490 491 if (sshpam_authctxt == NULL) 492 fatal("%s: PAM authctxt not initialized", __func__); 493 494 if ((buffer = sshbuf_new()) == NULL) 495 fatal("%s: sshbuf_new failed", __func__); 496 497 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 498 (const void *)&sshpam_conv); 499 if (sshpam_err != PAM_SUCCESS) 500 goto auth_fail; 501 sshpam_err = pam_authenticate(sshpam_handle, flags); 502 if (sshpam_err == PAM_MAXTRIES) 503 sshpam_set_maxtries_reached(1); 504 if (sshpam_err != PAM_SUCCESS) 505 goto auth_fail; 506 507 if (!do_pam_account()) { 508 sshpam_err = PAM_ACCT_EXPIRED; 509 goto auth_fail; 510 } 511 if (sshpam_authctxt->force_pwchange) { 512 sshpam_err = pam_chauthtok(sshpam_handle, 513 PAM_CHANGE_EXPIRED_AUTHTOK); 514 if (sshpam_err != PAM_SUCCESS) 515 goto auth_fail; 516 sshpam_password_change_required(0); 517 } 518 519 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 520 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 521 522 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 523 /* Export variables set by do_pam_account */ 524 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 525 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 526 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 527 528 /* Export any environment strings set in child */ 529 for (i = 0; environ[i] != NULL; i++) { 530 /* Count */ 531 if (i > INT_MAX) 532 fatal("%s: too many enviornment strings", __func__); 533 } 534 if ((r = sshbuf_put_u32(buffer, i)) != 0) 535 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 536 for (i = 0; environ[i] != NULL; i++) { 537 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 538 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 539 } 540 /* Export any environment strings set by PAM in child */ 541 env_from_pam = pam_getenvlist(sshpam_handle); 542 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 543 /* Count */ 544 if (i > INT_MAX) 545 fatal("%s: too many PAM enviornment strings", __func__); 546 } 547 if ((r = sshbuf_put_u32(buffer, i)) != 0) 548 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 549 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 550 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 551 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 552 } 553 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 554 555 /* XXX - can't do much about an error here */ 556 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 557 sshbuf_free(buffer); 558 pthread_exit(NULL); 559 560 auth_fail: 561 if ((r = sshbuf_put_cstring(buffer, 562 pam_strerror(sshpam_handle, sshpam_err))) != 0) 563 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 564 /* XXX - can't do much about an error here */ 565 if (sshpam_err == PAM_ACCT_EXPIRED) 566 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 567 else if (sshpam_maxtries_reached) 568 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 569 else 570 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 571 sshbuf_free(buffer); 572 pthread_exit(NULL); 573 574 return (NULL); /* Avoid warning for non-pthread case */ 575 } 576 577 void 578 sshpam_thread_cleanup(void) 579 { 580 struct pam_ctxt *ctxt = cleanup_ctxt; 581 582 debug3("PAM: %s entering", __func__); 583 if (ctxt != NULL && ctxt->pam_thread != 0) { 584 pthread_cancel(ctxt->pam_thread); 585 pthread_join(ctxt->pam_thread, NULL); 586 close(ctxt->pam_psock); 587 close(ctxt->pam_csock); 588 memset(ctxt, 0, sizeof(*ctxt)); 589 cleanup_ctxt = NULL; 590 } 591 } 592 593 static int 594 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 595 struct pam_response **resp, void *data) 596 { 597 debug3("PAM: %s entering, %d messages", __func__, n); 598 return (PAM_CONV_ERR); 599 } 600 601 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 602 603 static int 604 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 605 struct pam_response **resp, void *data) 606 { 607 struct pam_response *reply; 608 int r, i; 609 610 debug3("PAM: %s called with %d messages", __func__, n); 611 *resp = NULL; 612 613 if (n <= 0 || n > PAM_MAX_NUM_MSG) 614 return (PAM_CONV_ERR); 615 616 if ((reply = calloc(n, sizeof(*reply))) == NULL) 617 return (PAM_CONV_ERR); 618 619 for (i = 0; i < n; ++i) { 620 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 621 case PAM_ERROR_MSG: 622 case PAM_TEXT_INFO: 623 if ((r = sshbuf_putf(loginmsg, "%s\n", 624 PAM_MSG_MEMBER(msg, i, msg))) != 0) 625 fatal("%s: buffer error: %s", 626 __func__, ssh_err(r)); 627 reply[i].resp_retcode = PAM_SUCCESS; 628 break; 629 default: 630 goto fail; 631 } 632 } 633 *resp = reply; 634 return (PAM_SUCCESS); 635 636 fail: 637 for(i = 0; i < n; i++) { 638 free(reply[i].resp); 639 } 640 free(reply); 641 return (PAM_CONV_ERR); 642 } 643 644 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 645 646 void 647 sshpam_cleanup(void) 648 { 649 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 650 return; 651 debug("PAM: cleanup"); 652 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 653 if (sshpam_session_open) { 654 debug("PAM: closing session"); 655 pam_close_session(sshpam_handle, PAM_SILENT); 656 sshpam_session_open = 0; 657 } 658 if (sshpam_cred_established) { 659 debug("PAM: deleting credentials"); 660 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 661 sshpam_cred_established = 0; 662 } 663 sshpam_authenticated = 0; 664 pam_end(sshpam_handle, sshpam_err); 665 sshpam_handle = NULL; 666 } 667 668 static int 669 sshpam_init(Authctxt *authctxt) 670 { 671 const char *pam_rhost, *pam_user, *user = authctxt->user; 672 const char **ptr_pam_user = &pam_user; 673 struct ssh *ssh = active_state; /* XXX */ 674 675 if (sshpam_handle != NULL) { 676 /* We already have a PAM context; check if the user matches */ 677 sshpam_err = pam_get_item(sshpam_handle, 678 PAM_USER, (sshpam_const void **)ptr_pam_user); 679 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 680 return (0); 681 pam_end(sshpam_handle, sshpam_err); 682 sshpam_handle = NULL; 683 } 684 debug("PAM: initializing for \"%s\"", user); 685 sshpam_err = 686 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 687 sshpam_authctxt = authctxt; 688 689 if (sshpam_err != PAM_SUCCESS) { 690 pam_end(sshpam_handle, sshpam_err); 691 sshpam_handle = NULL; 692 return (-1); 693 } 694 pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns); 695 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 696 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 697 if (sshpam_err != PAM_SUCCESS) { 698 pam_end(sshpam_handle, sshpam_err); 699 sshpam_handle = NULL; 700 return (-1); 701 } 702 #ifdef PAM_TTY_KLUDGE 703 /* 704 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 705 * sshd doesn't set the tty until too late in the auth process and 706 * may not even set one (for tty-less connections) 707 */ 708 debug("PAM: setting PAM_TTY to \"ssh\""); 709 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 710 if (sshpam_err != PAM_SUCCESS) { 711 pam_end(sshpam_handle, sshpam_err); 712 sshpam_handle = NULL; 713 return (-1); 714 } 715 #endif 716 return (0); 717 } 718 719 static void 720 expose_authinfo(const char *caller) 721 { 722 char *auth_info; 723 724 /* 725 * Expose authentication information to PAM. 726 * The environment variable is versioned. Please increment the 727 * version suffix if the format of session_info changes. 728 */ 729 if (sshpam_authctxt->session_info == NULL) 730 auth_info = xstrdup(""); 731 else if ((auth_info = sshbuf_dup_string( 732 sshpam_authctxt->session_info)) == NULL) 733 fatal("%s: sshbuf_dup_string failed", __func__); 734 735 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 736 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 737 free(auth_info); 738 } 739 740 static void * 741 sshpam_init_ctx(Authctxt *authctxt) 742 { 743 struct pam_ctxt *ctxt; 744 int socks[2]; 745 746 debug3("PAM: %s entering", __func__); 747 /* 748 * Refuse to start if we don't have PAM enabled or do_pam_account 749 * has previously failed. 750 */ 751 if (!options.use_pam || sshpam_account_status == 0) 752 return NULL; 753 754 /* Initialize PAM */ 755 if (sshpam_init(authctxt) == -1) { 756 error("PAM: initialization failed"); 757 return (NULL); 758 } 759 760 expose_authinfo(__func__); 761 ctxt = xcalloc(1, sizeof *ctxt); 762 763 /* Start the authentication thread */ 764 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 765 error("PAM: failed create sockets: %s", strerror(errno)); 766 free(ctxt); 767 return (NULL); 768 } 769 ctxt->pam_psock = socks[0]; 770 ctxt->pam_csock = socks[1]; 771 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 772 error("PAM: failed to start authentication thread: %s", 773 strerror(errno)); 774 close(socks[0]); 775 close(socks[1]); 776 free(ctxt); 777 return (NULL); 778 } 779 cleanup_ctxt = ctxt; 780 return (ctxt); 781 } 782 783 static int 784 sshpam_query(void *ctx, char **name, char **info, 785 u_int *num, char ***prompts, u_int **echo_on) 786 { 787 struct ssh *ssh = active_state; /* XXX */ 788 struct sshbuf *buffer; 789 struct pam_ctxt *ctxt = ctx; 790 size_t plen; 791 u_char type; 792 char *msg; 793 size_t len, mlen; 794 int r; 795 796 debug3("PAM: %s entering", __func__); 797 if ((buffer = sshbuf_new()) == NULL) 798 fatal("%s: sshbuf_new failed", __func__); 799 *name = xstrdup(""); 800 *info = xstrdup(""); 801 *prompts = xmalloc(sizeof(char *)); 802 **prompts = NULL; 803 plen = 0; 804 *echo_on = xmalloc(sizeof(u_int)); 805 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 806 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 807 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 808 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 809 switch (type) { 810 case PAM_PROMPT_ECHO_ON: 811 case PAM_PROMPT_ECHO_OFF: 812 *num = 1; 813 len = plen + mlen + 1; 814 **prompts = xreallocarray(**prompts, 1, len); 815 strlcpy(**prompts + plen, msg, len - plen); 816 plen += mlen; 817 **echo_on = (type == PAM_PROMPT_ECHO_ON); 818 free(msg); 819 return (0); 820 case PAM_ERROR_MSG: 821 case PAM_TEXT_INFO: 822 /* accumulate messages */ 823 len = plen + mlen + 2; 824 **prompts = xreallocarray(**prompts, 1, len); 825 strlcpy(**prompts + plen, msg, len - plen); 826 plen += mlen; 827 strlcat(**prompts + plen, "\n", len - plen); 828 plen++; 829 free(msg); 830 break; 831 case PAM_ACCT_EXPIRED: 832 case PAM_MAXTRIES: 833 if (type == PAM_ACCT_EXPIRED) 834 sshpam_account_status = 0; 835 if (type == PAM_MAXTRIES) 836 sshpam_set_maxtries_reached(1); 837 /* FALLTHROUGH */ 838 case PAM_AUTH_ERR: 839 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 840 if (**prompts != NULL && strlen(**prompts) != 0) { 841 *info = **prompts; 842 **prompts = NULL; 843 *num = 0; 844 **echo_on = 0; 845 ctxt->pam_done = -1; 846 free(msg); 847 return 0; 848 } 849 /* FALLTHROUGH */ 850 case PAM_SUCCESS: 851 if (**prompts != NULL) { 852 /* drain any accumulated messages */ 853 debug("PAM: %s", **prompts); 854 if ((r = sshbuf_put(loginmsg, **prompts, 855 strlen(**prompts))) != 0) 856 fatal("%s: buffer error: %s", 857 __func__, ssh_err(r)); 858 free(**prompts); 859 **prompts = NULL; 860 } 861 if (type == PAM_SUCCESS) { 862 if (!sshpam_authctxt->valid || 863 (sshpam_authctxt->pw->pw_uid == 0 && 864 options.permit_root_login != PERMIT_YES)) 865 fatal("Internal error: PAM auth " 866 "succeeded when it should have " 867 "failed"); 868 import_environments(buffer); 869 *num = 0; 870 **echo_on = 0; 871 ctxt->pam_done = 1; 872 free(msg); 873 return (0); 874 } 875 BLACKLIST_NOTIFY(BLACKLIST_BAD_USER, 876 sshpam_authctxt->user); 877 error("PAM: %s for %s%.100s from %.100s", msg, 878 sshpam_authctxt->valid ? "" : "illegal user ", 879 sshpam_authctxt->user, 880 auth_get_canonical_hostname(ssh, options.use_dns)); 881 /* FALLTHROUGH */ 882 default: 883 *num = 0; 884 **echo_on = 0; 885 free(msg); 886 ctxt->pam_done = -1; 887 return (-1); 888 } 889 } 890 return (-1); 891 } 892 893 /* 894 * Returns a junk password of identical length to that the user supplied. 895 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 896 * vary processing time in proportion to password length. 897 */ 898 static char * 899 fake_password(const char *wire_password) 900 { 901 const char junk[] = "\b\n\r\177INCORRECT"; 902 char *ret = NULL; 903 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 904 905 if (l >= INT_MAX) 906 fatal("%s: password length too long: %zu", __func__, l); 907 908 ret = malloc(l + 1); 909 if (ret == NULL) 910 return NULL; 911 for (i = 0; i < l; i++) 912 ret[i] = junk[i % (sizeof(junk) - 1)]; 913 ret[i] = '\0'; 914 return ret; 915 } 916 917 /* XXX - see also comment in auth-chall.c:verify_response */ 918 static int 919 sshpam_respond(void *ctx, u_int num, char **resp) 920 { 921 struct sshbuf *buffer; 922 struct pam_ctxt *ctxt = ctx; 923 char *fake; 924 int r; 925 926 debug2("PAM: %s entering, %u responses", __func__, num); 927 switch (ctxt->pam_done) { 928 case 1: 929 sshpam_authenticated = 1; 930 return (0); 931 case 0: 932 break; 933 default: 934 return (-1); 935 } 936 if (num != 1) { 937 error("PAM: expected one response, got %u", num); 938 return (-1); 939 } 940 if ((buffer = sshbuf_new()) == NULL) 941 fatal("%s: sshbuf_new failed", __func__); 942 if (sshpam_authctxt->valid && 943 (sshpam_authctxt->pw->pw_uid != 0 || 944 options.permit_root_login == PERMIT_YES)) { 945 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 946 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 947 } else { 948 fake = fake_password(*resp); 949 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 950 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 951 free(fake); 952 } 953 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 954 sshbuf_free(buffer); 955 return (-1); 956 } 957 sshbuf_free(buffer); 958 return (1); 959 } 960 961 static void 962 sshpam_free_ctx(void *ctxtp) 963 { 964 struct pam_ctxt *ctxt = ctxtp; 965 966 debug3("PAM: %s entering", __func__); 967 sshpam_thread_cleanup(); 968 free(ctxt); 969 /* 970 * We don't call sshpam_cleanup() here because we may need the PAM 971 * handle at a later stage, e.g. when setting up a session. It's 972 * still on the cleanup list, so pam_end() *will* be called before 973 * the server process terminates. 974 */ 975 } 976 977 KbdintDevice sshpam_device = { 978 "pam", 979 sshpam_init_ctx, 980 sshpam_query, 981 sshpam_respond, 982 sshpam_free_ctx 983 }; 984 985 KbdintDevice mm_sshpam_device = { 986 "pam", 987 mm_sshpam_init_ctx, 988 mm_sshpam_query, 989 mm_sshpam_respond, 990 mm_sshpam_free_ctx 991 }; 992 993 /* 994 * This replaces auth-pam.c 995 */ 996 void 997 start_pam(Authctxt *authctxt) 998 { 999 if (!options.use_pam) 1000 fatal("PAM: initialisation requested when UsePAM=no"); 1001 1002 if (sshpam_init(authctxt) == -1) 1003 fatal("PAM: initialisation failed"); 1004 } 1005 1006 void 1007 finish_pam(void) 1008 { 1009 sshpam_cleanup(); 1010 } 1011 1012 1013 u_int 1014 do_pam_account(void) 1015 { 1016 debug("%s: called", __func__); 1017 if (sshpam_account_status != -1) 1018 return (sshpam_account_status); 1019 1020 expose_authinfo(__func__); 1021 1022 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1023 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1024 pam_strerror(sshpam_handle, sshpam_err)); 1025 1026 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1027 sshpam_account_status = 0; 1028 return (sshpam_account_status); 1029 } 1030 1031 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1032 sshpam_password_change_required(1); 1033 1034 sshpam_account_status = 1; 1035 return (sshpam_account_status); 1036 } 1037 1038 void 1039 do_pam_setcred(int init) 1040 { 1041 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1042 (const void *)&store_conv); 1043 if (sshpam_err != PAM_SUCCESS) 1044 fatal("PAM: failed to set PAM_CONV: %s", 1045 pam_strerror(sshpam_handle, sshpam_err)); 1046 if (init) { 1047 debug("PAM: establishing credentials"); 1048 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1049 } else { 1050 debug("PAM: reinitializing credentials"); 1051 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1052 } 1053 if (sshpam_err == PAM_SUCCESS) { 1054 sshpam_cred_established = 1; 1055 return; 1056 } 1057 if (sshpam_authenticated) 1058 fatal("PAM: pam_setcred(): %s", 1059 pam_strerror(sshpam_handle, sshpam_err)); 1060 else 1061 debug("PAM: pam_setcred(): %s", 1062 pam_strerror(sshpam_handle, sshpam_err)); 1063 } 1064 1065 static int 1066 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1067 struct pam_response **resp, void *data) 1068 { 1069 char input[PAM_MAX_MSG_SIZE]; 1070 struct pam_response *reply; 1071 int i; 1072 1073 debug3("PAM: %s called with %d messages", __func__, n); 1074 1075 *resp = NULL; 1076 1077 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1078 return (PAM_CONV_ERR); 1079 1080 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1081 return (PAM_CONV_ERR); 1082 1083 for (i = 0; i < n; ++i) { 1084 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1085 case PAM_PROMPT_ECHO_OFF: 1086 reply[i].resp = 1087 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1088 RP_ALLOW_STDIN); 1089 reply[i].resp_retcode = PAM_SUCCESS; 1090 break; 1091 case PAM_PROMPT_ECHO_ON: 1092 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1093 if (fgets(input, sizeof input, stdin) == NULL) 1094 input[0] = '\0'; 1095 if ((reply[i].resp = strdup(input)) == NULL) 1096 goto fail; 1097 reply[i].resp_retcode = PAM_SUCCESS; 1098 break; 1099 case PAM_ERROR_MSG: 1100 case PAM_TEXT_INFO: 1101 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1102 reply[i].resp_retcode = PAM_SUCCESS; 1103 break; 1104 default: 1105 goto fail; 1106 } 1107 } 1108 *resp = reply; 1109 return (PAM_SUCCESS); 1110 1111 fail: 1112 for(i = 0; i < n; i++) { 1113 free(reply[i].resp); 1114 } 1115 free(reply); 1116 return (PAM_CONV_ERR); 1117 } 1118 1119 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1120 1121 /* 1122 * XXX this should be done in the authentication phase, but ssh1 doesn't 1123 * support that 1124 */ 1125 void 1126 do_pam_chauthtok(void) 1127 { 1128 if (use_privsep) 1129 fatal("Password expired (unable to change with privsep)"); 1130 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1131 (const void *)&tty_conv); 1132 if (sshpam_err != PAM_SUCCESS) 1133 fatal("PAM: failed to set PAM_CONV: %s", 1134 pam_strerror(sshpam_handle, sshpam_err)); 1135 debug("PAM: changing password"); 1136 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1137 if (sshpam_err != PAM_SUCCESS) 1138 fatal("PAM: pam_chauthtok(): %s", 1139 pam_strerror(sshpam_handle, sshpam_err)); 1140 } 1141 1142 void 1143 do_pam_session(struct ssh *ssh) 1144 { 1145 debug3("PAM: opening session"); 1146 1147 expose_authinfo(__func__); 1148 1149 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1150 (const void *)&store_conv); 1151 if (sshpam_err != PAM_SUCCESS) 1152 fatal("PAM: failed to set PAM_CONV: %s", 1153 pam_strerror(sshpam_handle, sshpam_err)); 1154 sshpam_err = pam_open_session(sshpam_handle, 0); 1155 if (sshpam_err == PAM_SUCCESS) 1156 sshpam_session_open = 1; 1157 else { 1158 sshpam_session_open = 0; 1159 auth_restrict_session(ssh); 1160 error("PAM: pam_open_session(): %s", 1161 pam_strerror(sshpam_handle, sshpam_err)); 1162 } 1163 1164 } 1165 1166 int 1167 is_pam_session_open(void) 1168 { 1169 return sshpam_session_open; 1170 } 1171 1172 /* 1173 * Set a PAM environment string. We need to do this so that the session 1174 * modules can handle things like Kerberos/GSI credentials that appear 1175 * during the ssh authentication process. 1176 */ 1177 int 1178 do_pam_putenv(char *name, char *value) 1179 { 1180 int ret = 1; 1181 #ifdef HAVE_PAM_PUTENV 1182 char *compound; 1183 size_t len; 1184 1185 len = strlen(name) + strlen(value) + 2; 1186 compound = xmalloc(len); 1187 1188 snprintf(compound, len, "%s=%s", name, value); 1189 ret = pam_putenv(sshpam_handle, compound); 1190 free(compound); 1191 #endif 1192 1193 return (ret); 1194 } 1195 1196 char ** 1197 fetch_pam_child_environment(void) 1198 { 1199 return sshpam_env; 1200 } 1201 1202 char ** 1203 fetch_pam_environment(void) 1204 { 1205 return (pam_getenvlist(sshpam_handle)); 1206 } 1207 1208 void 1209 free_pam_environment(char **env) 1210 { 1211 char **envp; 1212 1213 if (env == NULL) 1214 return; 1215 1216 for (envp = env; *envp; envp++) 1217 free(*envp); 1218 free(env); 1219 } 1220 1221 /* 1222 * "Blind" conversation function for password authentication. Assumes that 1223 * echo-off prompts are for the password and stores messages for later 1224 * display. 1225 */ 1226 static int 1227 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1228 struct pam_response **resp, void *data) 1229 { 1230 struct pam_response *reply; 1231 int r, i; 1232 size_t len; 1233 1234 debug3("PAM: %s called with %d messages", __func__, n); 1235 1236 *resp = NULL; 1237 1238 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1239 return (PAM_CONV_ERR); 1240 1241 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1242 return (PAM_CONV_ERR); 1243 1244 for (i = 0; i < n; ++i) { 1245 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1246 case PAM_PROMPT_ECHO_OFF: 1247 if (sshpam_password == NULL) 1248 goto fail; 1249 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1250 goto fail; 1251 reply[i].resp_retcode = PAM_SUCCESS; 1252 break; 1253 case PAM_ERROR_MSG: 1254 case PAM_TEXT_INFO: 1255 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1256 if (len > 0) { 1257 if ((r = sshbuf_putf(loginmsg, "%s\n", 1258 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1259 fatal("%s: buffer error: %s", 1260 __func__, ssh_err(r)); 1261 } 1262 if ((reply[i].resp = strdup("")) == NULL) 1263 goto fail; 1264 reply[i].resp_retcode = PAM_SUCCESS; 1265 break; 1266 default: 1267 goto fail; 1268 } 1269 } 1270 *resp = reply; 1271 return (PAM_SUCCESS); 1272 1273 fail: 1274 for(i = 0; i < n; i++) { 1275 free(reply[i].resp); 1276 } 1277 free(reply); 1278 return (PAM_CONV_ERR); 1279 } 1280 1281 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1282 1283 /* 1284 * Attempt password authentication via PAM 1285 */ 1286 int 1287 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1288 { 1289 int flags = (options.permit_empty_passwd == 0 ? 1290 PAM_DISALLOW_NULL_AUTHTOK : 0); 1291 char *fake = NULL; 1292 1293 if (!options.use_pam || sshpam_handle == NULL) 1294 fatal("PAM: %s called when PAM disabled or failed to " 1295 "initialise.", __func__); 1296 1297 sshpam_password = password; 1298 sshpam_authctxt = authctxt; 1299 1300 /* 1301 * If the user logging in is invalid, or is root but is not permitted 1302 * by PermitRootLogin, use an invalid password to prevent leaking 1303 * information via timing (eg if the PAM config has a delay on fail). 1304 */ 1305 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1306 options.permit_root_login != PERMIT_YES)) 1307 sshpam_password = fake = fake_password(password); 1308 1309 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1310 (const void *)&passwd_conv); 1311 if (sshpam_err != PAM_SUCCESS) 1312 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1313 pam_strerror(sshpam_handle, sshpam_err)); 1314 1315 sshpam_err = pam_authenticate(sshpam_handle, flags); 1316 sshpam_password = NULL; 1317 free(fake); 1318 if (sshpam_err == PAM_MAXTRIES) 1319 sshpam_set_maxtries_reached(1); 1320 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1321 debug("PAM: password authentication accepted for %.100s", 1322 authctxt->user); 1323 return 1; 1324 } else { 1325 debug("PAM: password authentication failed for %.100s: %s", 1326 authctxt->valid ? authctxt->user : "an illegal user", 1327 pam_strerror(sshpam_handle, sshpam_err)); 1328 return 0; 1329 } 1330 } 1331 1332 int 1333 sshpam_get_maxtries_reached(void) 1334 { 1335 return sshpam_maxtries_reached; 1336 } 1337 1338 void 1339 sshpam_set_maxtries_reached(int reached) 1340 { 1341 if (reached == 0 || sshpam_maxtries_reached) 1342 return; 1343 sshpam_maxtries_reached = 1; 1344 options.password_authentication = 0; 1345 options.kbd_interactive_authentication = 0; 1346 options.challenge_response_authentication = 0; 1347 } 1348 #endif /* USE_PAM */ 1349