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 <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 63 #ifdef USE_PAM 64 #if defined(HAVE_SECURITY_PAM_APPL_H) 65 #include <security/pam_appl.h> 66 #elif defined (HAVE_PAM_PAM_APPL_H) 67 #include <pam/pam_appl.h> 68 #endif 69 70 #if !defined(SSHD_PAM_SERVICE) 71 extern char *__progname; 72 # define SSHD_PAM_SERVICE __progname 73 #endif 74 75 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 76 #ifdef PAM_SUN_CODEBASE 77 # define sshpam_const /* Solaris, HP-UX, SunOS */ 78 #else 79 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */ 80 #endif 81 82 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 83 #ifdef PAM_SUN_CODEBASE 84 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 85 #else 86 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 87 #endif 88 89 #include "xmalloc.h" 90 #include "sshbuf.h" 91 #include "ssherr.h" 92 #include "hostfile.h" 93 #include "auth.h" 94 #include "auth-pam.h" 95 #include "canohost.h" 96 #include "log.h" 97 #include "msg.h" 98 #include "packet.h" 99 #include "misc.h" 100 #include "servconf.h" 101 #include "ssh2.h" 102 #include "auth-options.h" 103 #include "misc.h" 104 #ifdef GSSAPI 105 #include "ssh-gss.h" 106 #endif 107 #include "monitor_wrap.h" 108 #include "blacklist_client.h" 109 110 extern ServerOptions options; 111 extern struct sshbuf *loginmsg; 112 extern u_int utmp_len; 113 114 /* so we don't silently change behaviour */ 115 #ifdef USE_POSIX_THREADS 116 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 117 #endif 118 119 /* 120 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 121 * and generally a bad idea. Use at own risk and do not expect support if 122 * this breaks. 123 */ 124 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 125 #include <pthread.h> 126 /* 127 * Avoid namespace clash when *not* using pthreads for systems *with* 128 * pthreads, which unconditionally define pthread_t via sys/types.h 129 * (e.g. Linux) 130 */ 131 typedef pthread_t sp_pthread_t; 132 #else 133 typedef pid_t sp_pthread_t; 134 #define pthread_exit fake_pthread_exit 135 #define pthread_create fake_pthread_create 136 #define pthread_cancel fake_pthread_cancel 137 #define pthread_join fake_pthread_join 138 #endif 139 140 struct pam_ctxt { 141 sp_pthread_t pam_thread; 142 int pam_psock; 143 int pam_csock; 144 int pam_done; 145 }; 146 147 static void sshpam_free_ctx(void *); 148 static struct pam_ctxt *cleanup_ctxt; 149 150 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 151 /* 152 * Simulate threads with processes. 153 */ 154 155 static int sshpam_thread_status = -1; 156 static sshsig_t sshpam_oldsig; 157 158 static void 159 sshpam_sigchld_handler(int sig) 160 { 161 ssh_signal(SIGCHLD, SIG_DFL); 162 if (cleanup_ctxt == NULL) 163 return; /* handler called after PAM cleanup, shouldn't happen */ 164 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 165 <= 0) { 166 /* PAM thread has not exitted, privsep slave must have */ 167 kill(cleanup_ctxt->pam_thread, SIGTERM); 168 while (waitpid(cleanup_ctxt->pam_thread, 169 &sshpam_thread_status, 0) == -1) { 170 if (errno == EINTR) 171 continue; 172 return; 173 } 174 } 175 if (WIFSIGNALED(sshpam_thread_status) && 176 WTERMSIG(sshpam_thread_status) == SIGTERM) 177 return; /* terminated by pthread_cancel */ 178 if (!WIFEXITED(sshpam_thread_status)) 179 sigdie("PAM: authentication thread exited unexpectedly"); 180 if (WEXITSTATUS(sshpam_thread_status) != 0) 181 sigdie("PAM: authentication thread exited uncleanly"); 182 } 183 184 /* ARGSUSED */ 185 static void 186 pthread_exit(void *value) 187 { 188 _exit(0); 189 } 190 191 /* ARGSUSED */ 192 static int 193 pthread_create(sp_pthread_t *thread, const void *attr, 194 void *(*thread_start)(void *), void *arg) 195 { 196 pid_t pid; 197 struct pam_ctxt *ctx = arg; 198 199 sshpam_thread_status = -1; 200 switch ((pid = fork())) { 201 case -1: 202 error("fork(): %s", strerror(errno)); 203 return errno; 204 case 0: 205 close(ctx->pam_psock); 206 ctx->pam_psock = -1; 207 thread_start(arg); 208 _exit(1); 209 default: 210 *thread = pid; 211 close(ctx->pam_csock); 212 ctx->pam_csock = -1; 213 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler); 214 return (0); 215 } 216 } 217 218 static int 219 pthread_cancel(sp_pthread_t thread) 220 { 221 ssh_signal(SIGCHLD, sshpam_oldsig); 222 return (kill(thread, SIGTERM)); 223 } 224 225 /* ARGSUSED */ 226 static int 227 pthread_join(sp_pthread_t thread, void **value) 228 { 229 int status; 230 231 if (sshpam_thread_status != -1) 232 return (sshpam_thread_status); 233 ssh_signal(SIGCHLD, sshpam_oldsig); 234 while (waitpid(thread, &status, 0) == -1) { 235 if (errno == EINTR) 236 continue; 237 fatal("%s: waitpid: %s", __func__, strerror(errno)); 238 } 239 return (status); 240 } 241 #endif 242 243 244 static pam_handle_t *sshpam_handle = NULL; 245 static int sshpam_err = 0; 246 static int sshpam_authenticated = 0; 247 static int sshpam_session_open = 0; 248 static int sshpam_cred_established = 0; 249 static int sshpam_account_status = -1; 250 static int sshpam_maxtries_reached = 0; 251 static char **sshpam_env = NULL; 252 static Authctxt *sshpam_authctxt = NULL; 253 static const char *sshpam_password = NULL; 254 static char *sshpam_rhost = NULL; 255 static char *sshpam_laddr = NULL; 256 static char *sshpam_conninfo = NULL; 257 258 /* Some PAM implementations don't implement this */ 259 #ifndef HAVE_PAM_GETENVLIST 260 static char ** 261 pam_getenvlist(pam_handle_t *pamh) 262 { 263 /* 264 * XXX - If necessary, we can still support environment passing 265 * for platforms without pam_getenvlist by searching for known 266 * env vars (e.g. KRB5CCNAME) from the PAM environment. 267 */ 268 return NULL; 269 } 270 #endif 271 272 #ifndef HAVE_PAM_PUTENV 273 static int 274 pam_putenv(pam_handle_t *pamh, const char *name_value) 275 { 276 return PAM_SUCCESS; 277 } 278 #endif /* HAVE_PAM_PUTENV */ 279 280 /* 281 * Some platforms, notably Solaris, do not enforce password complexity 282 * rules during pam_chauthtok() if the real uid of the calling process 283 * is 0, on the assumption that it's being called by "passwd" run by root. 284 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 285 * the right thing. 286 */ 287 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 288 static int 289 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 290 { 291 int result; 292 293 if (sshpam_authctxt == NULL) 294 fatal("PAM: sshpam_authctxt not initialized"); 295 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 296 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 297 result = pam_chauthtok(pamh, flags); 298 if (setreuid(0, -1) == -1) 299 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 300 return result; 301 } 302 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 303 #endif 304 305 static void 306 sshpam_password_change_required(int reqd) 307 { 308 extern struct sshauthopt *auth_opts; 309 static int saved_port, saved_agent, saved_x11; 310 311 debug3("%s %d", __func__, reqd); 312 if (sshpam_authctxt == NULL) 313 fatal("%s: PAM authctxt not initialized", __func__); 314 sshpam_authctxt->force_pwchange = reqd; 315 if (reqd) { 316 saved_port = auth_opts->permit_port_forwarding_flag; 317 saved_agent = auth_opts->permit_agent_forwarding_flag; 318 saved_x11 = auth_opts->permit_x11_forwarding_flag; 319 auth_opts->permit_port_forwarding_flag = 0; 320 auth_opts->permit_agent_forwarding_flag = 0; 321 auth_opts->permit_x11_forwarding_flag = 0; 322 } else { 323 if (saved_port) 324 auth_opts->permit_port_forwarding_flag = saved_port; 325 if (saved_agent) 326 auth_opts->permit_agent_forwarding_flag = saved_agent; 327 if (saved_x11) 328 auth_opts->permit_x11_forwarding_flag = saved_x11; 329 } 330 } 331 332 /* Import regular and PAM environment from subprocess */ 333 static void 334 import_environments(struct sshbuf *b) 335 { 336 char *env; 337 u_int n, i, num_env; 338 int r; 339 340 debug3("PAM: %s entering", __func__); 341 342 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 343 /* Import variables set by do_pam_account */ 344 if ((r = sshbuf_get_u32(b, &n)) != 0) 345 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 346 if (n > INT_MAX) 347 fatal("%s: invalid PAM account status %u", __func__, n); 348 sshpam_account_status = (int)n; 349 if ((r = sshbuf_get_u32(b, &n)) != 0) 350 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 351 sshpam_password_change_required(n != 0); 352 353 /* Import environment from subprocess */ 354 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 355 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 356 if (num_env > 1024) 357 fatal("%s: received %u environment variables, expected <= 1024", 358 __func__, num_env); 359 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 360 debug3("PAM: num env strings %d", num_env); 361 for(i = 0; i < num_env; i++) { 362 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0) 363 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 364 } 365 sshpam_env[num_env] = NULL; 366 367 /* Import PAM environment from subprocess */ 368 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 369 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 370 debug("PAM: num PAM env strings %d", num_env); 371 for (i = 0; i < num_env; i++) { 372 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0) 373 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 374 /* Errors are not fatal here */ 375 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 376 error("PAM: pam_putenv: %s", 377 pam_strerror(sshpam_handle, r)); 378 } 379 /* 380 * XXX this possibly leaks env because it is not documented 381 * what pam_putenv() does with it. Does it copy it? Does it 382 * take ownweship? We don't know, so it's safest just to leak. 383 */ 384 } 385 #endif 386 } 387 388 /* 389 * Conversation function for authentication thread. 390 */ 391 static int 392 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 393 struct pam_response **resp, void *data) 394 { 395 struct sshbuf *buffer; 396 struct pam_ctxt *ctxt; 397 struct pam_response *reply; 398 int r, i; 399 u_char status; 400 401 debug3("PAM: %s entering, %d messages", __func__, n); 402 *resp = NULL; 403 404 if (data == NULL) { 405 error("PAM: conversation function passed a null context"); 406 return (PAM_CONV_ERR); 407 } 408 ctxt = data; 409 if (n <= 0 || n > PAM_MAX_NUM_MSG) 410 return (PAM_CONV_ERR); 411 412 if ((reply = calloc(n, sizeof(*reply))) == NULL) 413 return PAM_CONV_ERR; 414 if ((buffer = sshbuf_new()) == NULL) { 415 free(reply); 416 return PAM_CONV_ERR; 417 } 418 419 for (i = 0; i < n; ++i) { 420 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 421 case PAM_PROMPT_ECHO_OFF: 422 case PAM_PROMPT_ECHO_ON: 423 if ((r = sshbuf_put_cstring(buffer, 424 PAM_MSG_MEMBER(msg, i, msg))) != 0) 425 fatal("%s: buffer error: %s", 426 __func__, ssh_err(r)); 427 if (ssh_msg_send(ctxt->pam_csock, 428 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 429 goto fail; 430 431 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 432 goto fail; 433 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 434 fatal("%s: buffer error: %s", 435 __func__, ssh_err(r)); 436 if (status != PAM_AUTHTOK) 437 goto fail; 438 if ((r = sshbuf_get_cstring(buffer, 439 &reply[i].resp, NULL)) != 0) 440 fatal("%s: buffer error: %s", 441 __func__, ssh_err(r)); 442 break; 443 case PAM_ERROR_MSG: 444 case PAM_TEXT_INFO: 445 if ((r = sshbuf_put_cstring(buffer, 446 PAM_MSG_MEMBER(msg, i, msg))) != 0) 447 fatal("%s: buffer error: %s", 448 __func__, ssh_err(r)); 449 if (ssh_msg_send(ctxt->pam_csock, 450 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 451 goto fail; 452 break; 453 default: 454 goto fail; 455 } 456 sshbuf_reset(buffer); 457 } 458 sshbuf_free(buffer); 459 *resp = reply; 460 return (PAM_SUCCESS); 461 462 fail: 463 for(i = 0; i < n; i++) { 464 free(reply[i].resp); 465 } 466 free(reply); 467 sshbuf_free(buffer); 468 return (PAM_CONV_ERR); 469 } 470 471 /* 472 * Authentication thread. 473 */ 474 static void * 475 sshpam_thread(void *ctxtp) 476 { 477 struct pam_ctxt *ctxt = ctxtp; 478 struct sshbuf *buffer = NULL; 479 struct pam_conv sshpam_conv; 480 int r, flags = (options.permit_empty_passwd == 0 ? 481 PAM_DISALLOW_NULL_AUTHTOK : 0); 482 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 483 extern char **environ; 484 char **env_from_pam; 485 u_int i; 486 const char *pam_user; 487 const char **ptr_pam_user = &pam_user; 488 char *tz = getenv("TZ"); 489 490 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 491 (sshpam_const void **)ptr_pam_user); 492 if (sshpam_err != PAM_SUCCESS) 493 goto auth_fail; 494 495 environ[0] = NULL; 496 if (tz != NULL) 497 if (setenv("TZ", tz, 1) == -1) 498 error("PAM: could not set TZ environment: %s", 499 strerror(errno)); 500 501 if (sshpam_authctxt != NULL) { 502 setproctitle("%s [pam]", 503 sshpam_authctxt->valid ? pam_user : "unknown"); 504 } 505 #endif 506 507 sshpam_conv.conv = sshpam_thread_conv; 508 sshpam_conv.appdata_ptr = ctxt; 509 510 if (sshpam_authctxt == NULL) 511 fatal("%s: PAM authctxt not initialized", __func__); 512 513 if ((buffer = sshbuf_new()) == NULL) 514 fatal("%s: sshbuf_new failed", __func__); 515 516 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 517 (const void *)&sshpam_conv); 518 if (sshpam_err != PAM_SUCCESS) 519 goto auth_fail; 520 sshpam_err = pam_authenticate(sshpam_handle, flags); 521 if (sshpam_err == PAM_MAXTRIES) 522 sshpam_set_maxtries_reached(1); 523 if (sshpam_err != PAM_SUCCESS) 524 goto auth_fail; 525 526 if (!do_pam_account()) { 527 sshpam_err = PAM_ACCT_EXPIRED; 528 goto auth_fail; 529 } 530 if (sshpam_authctxt->force_pwchange) { 531 sshpam_err = pam_chauthtok(sshpam_handle, 532 PAM_CHANGE_EXPIRED_AUTHTOK); 533 if (sshpam_err != PAM_SUCCESS) 534 goto auth_fail; 535 sshpam_password_change_required(0); 536 } 537 538 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 539 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 540 541 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 542 /* Export variables set by do_pam_account */ 543 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 544 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 545 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 546 547 /* Export any environment strings set in child */ 548 for (i = 0; environ[i] != NULL; i++) { 549 /* Count */ 550 if (i > INT_MAX) 551 fatal("%s: too many environment strings", __func__); 552 } 553 if ((r = sshbuf_put_u32(buffer, i)) != 0) 554 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 555 for (i = 0; environ[i] != NULL; i++) { 556 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 557 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 558 } 559 /* Export any environment strings set by PAM in child */ 560 env_from_pam = pam_getenvlist(sshpam_handle); 561 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 562 /* Count */ 563 if (i > INT_MAX) 564 fatal("%s: too many PAM environment strings", __func__); 565 } 566 if ((r = sshbuf_put_u32(buffer, i)) != 0) 567 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 568 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 569 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 570 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 571 } 572 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 573 574 /* XXX - can't do much about an error here */ 575 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 576 sshbuf_free(buffer); 577 pthread_exit(NULL); 578 579 auth_fail: 580 if ((r = sshbuf_put_cstring(buffer, 581 pam_strerror(sshpam_handle, sshpam_err))) != 0) 582 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 583 /* XXX - can't do much about an error here */ 584 if (sshpam_err == PAM_ACCT_EXPIRED) 585 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 586 else if (sshpam_maxtries_reached) 587 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 588 else 589 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 590 sshbuf_free(buffer); 591 pthread_exit(NULL); 592 593 return (NULL); /* Avoid warning for non-pthread case */ 594 } 595 596 void 597 sshpam_thread_cleanup(void) 598 { 599 struct pam_ctxt *ctxt = cleanup_ctxt; 600 601 debug3("PAM: %s entering", __func__); 602 if (ctxt != NULL && ctxt->pam_thread != 0) { 603 pthread_cancel(ctxt->pam_thread); 604 pthread_join(ctxt->pam_thread, NULL); 605 close(ctxt->pam_psock); 606 close(ctxt->pam_csock); 607 memset(ctxt, 0, sizeof(*ctxt)); 608 cleanup_ctxt = NULL; 609 } 610 } 611 612 static int 613 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 614 struct pam_response **resp, void *data) 615 { 616 debug3("PAM: %s entering, %d messages", __func__, n); 617 return (PAM_CONV_ERR); 618 } 619 620 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 621 622 static int 623 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 624 struct pam_response **resp, void *data) 625 { 626 struct pam_response *reply; 627 int r, i; 628 629 debug3("PAM: %s called with %d messages", __func__, n); 630 *resp = NULL; 631 632 if (n <= 0 || n > PAM_MAX_NUM_MSG) 633 return (PAM_CONV_ERR); 634 635 if ((reply = calloc(n, sizeof(*reply))) == NULL) 636 return (PAM_CONV_ERR); 637 638 for (i = 0; i < n; ++i) { 639 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 640 case PAM_ERROR_MSG: 641 case PAM_TEXT_INFO: 642 if ((r = sshbuf_putf(loginmsg, "%s\n", 643 PAM_MSG_MEMBER(msg, i, msg))) != 0) 644 fatal("%s: buffer error: %s", 645 __func__, ssh_err(r)); 646 reply[i].resp_retcode = PAM_SUCCESS; 647 break; 648 default: 649 goto fail; 650 } 651 } 652 *resp = reply; 653 return (PAM_SUCCESS); 654 655 fail: 656 for(i = 0; i < n; i++) { 657 free(reply[i].resp); 658 } 659 free(reply); 660 return (PAM_CONV_ERR); 661 } 662 663 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 664 665 void 666 sshpam_cleanup(void) 667 { 668 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 669 return; 670 debug("PAM: cleanup"); 671 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 672 if (sshpam_session_open) { 673 debug("PAM: closing session"); 674 pam_close_session(sshpam_handle, PAM_SILENT); 675 sshpam_session_open = 0; 676 } 677 if (sshpam_cred_established) { 678 debug("PAM: deleting credentials"); 679 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 680 sshpam_cred_established = 0; 681 } 682 sshpam_authenticated = 0; 683 pam_end(sshpam_handle, sshpam_err); 684 sshpam_handle = NULL; 685 } 686 687 static int 688 sshpam_init(struct ssh *ssh, Authctxt *authctxt) 689 { 690 const char *pam_user, *user = authctxt->user; 691 const char **ptr_pam_user = &pam_user; 692 693 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE) 694 /* Protect buggy PAM implementations from excessively long usernames */ 695 if (strlen(user) >= PAM_MAX_RESP_SIZE) 696 fatal("Username too long from %s port %d", 697 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 698 #endif 699 if (sshpam_handle == NULL) { 700 if (ssh == NULL) { 701 fatal("%s: called initially with no " 702 "packet context", __func__); 703 } 704 } if (sshpam_handle != NULL) { 705 /* We already have a PAM context; check if the user matches */ 706 sshpam_err = pam_get_item(sshpam_handle, 707 PAM_USER, (sshpam_const void **)ptr_pam_user); 708 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 709 return (0); 710 pam_end(sshpam_handle, sshpam_err); 711 sshpam_handle = NULL; 712 } 713 debug("PAM: initializing for \"%s\"", user); 714 sshpam_err = 715 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 716 sshpam_authctxt = authctxt; 717 718 if (sshpam_err != PAM_SUCCESS) { 719 pam_end(sshpam_handle, sshpam_err); 720 sshpam_handle = NULL; 721 return (-1); 722 } 723 724 if (ssh != NULL && sshpam_rhost == NULL) { 725 /* 726 * We need to cache these as we don't have packet context 727 * during the kbdint flow. 728 */ 729 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh, 730 options.use_dns)); 731 sshpam_laddr = get_local_ipaddr( 732 ssh_packet_get_connection_in(ssh)); 733 xasprintf(&sshpam_conninfo, "SSH_CONNECTION=%.50s %d %.50s %d", 734 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 735 sshpam_laddr, ssh_local_port(ssh)); 736 } 737 if (sshpam_rhost != NULL) { 738 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); 739 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, 740 sshpam_rhost); 741 if (sshpam_err != PAM_SUCCESS) { 742 pam_end(sshpam_handle, sshpam_err); 743 sshpam_handle = NULL; 744 return (-1); 745 } 746 /* Put SSH_CONNECTION in the PAM environment too */ 747 pam_putenv(sshpam_handle, sshpam_conninfo); 748 } 749 750 #ifdef PAM_TTY_KLUDGE 751 /* 752 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 753 * sshd doesn't set the tty until too late in the auth process and 754 * may not even set one (for tty-less connections) 755 */ 756 debug("PAM: setting PAM_TTY to \"ssh\""); 757 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 758 if (sshpam_err != PAM_SUCCESS) { 759 pam_end(sshpam_handle, sshpam_err); 760 sshpam_handle = NULL; 761 return (-1); 762 } 763 #endif 764 return (0); 765 } 766 767 static void 768 expose_authinfo(const char *caller) 769 { 770 char *auth_info; 771 772 /* 773 * Expose authentication information to PAM. 774 * The environment variable is versioned. Please increment the 775 * version suffix if the format of session_info changes. 776 */ 777 if (sshpam_authctxt->session_info == NULL) 778 auth_info = xstrdup(""); 779 else if ((auth_info = sshbuf_dup_string( 780 sshpam_authctxt->session_info)) == NULL) 781 fatal("%s: sshbuf_dup_string failed", __func__); 782 783 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 784 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 785 free(auth_info); 786 } 787 788 static void * 789 sshpam_init_ctx(Authctxt *authctxt) 790 { 791 struct pam_ctxt *ctxt; 792 int result, socks[2]; 793 794 debug3("PAM: %s entering", __func__); 795 /* 796 * Refuse to start if we don't have PAM enabled or do_pam_account 797 * has previously failed. 798 */ 799 if (!options.use_pam || sshpam_account_status == 0) 800 return NULL; 801 802 /* Initialize PAM */ 803 if (sshpam_init(NULL, authctxt) == -1) { 804 error("PAM: initialization failed"); 805 return (NULL); 806 } 807 808 expose_authinfo(__func__); 809 ctxt = xcalloc(1, sizeof *ctxt); 810 811 /* Start the authentication thread */ 812 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 813 error("PAM: failed create sockets: %s", strerror(errno)); 814 free(ctxt); 815 return (NULL); 816 } 817 ctxt->pam_psock = socks[0]; 818 ctxt->pam_csock = socks[1]; 819 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt); 820 if (result != 0) { 821 error("PAM: failed to start authentication thread: %s", 822 strerror(result)); 823 close(socks[0]); 824 close(socks[1]); 825 free(ctxt); 826 return (NULL); 827 } 828 cleanup_ctxt = ctxt; 829 return (ctxt); 830 } 831 832 static int 833 sshpam_query(void *ctx, char **name, char **info, 834 u_int *num, char ***prompts, u_int **echo_on) 835 { 836 struct sshbuf *buffer; 837 struct pam_ctxt *ctxt = ctx; 838 size_t plen; 839 u_char type; 840 char *msg; 841 size_t len, mlen; 842 int r; 843 844 debug3("PAM: %s entering", __func__); 845 if ((buffer = sshbuf_new()) == NULL) 846 fatal("%s: sshbuf_new failed", __func__); 847 *name = xstrdup(""); 848 *info = xstrdup(""); 849 *prompts = xmalloc(sizeof(char *)); 850 **prompts = NULL; 851 plen = 0; 852 *echo_on = xmalloc(sizeof(u_int)); 853 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 854 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 855 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 856 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 857 switch (type) { 858 case PAM_PROMPT_ECHO_ON: 859 case PAM_PROMPT_ECHO_OFF: 860 *num = 1; 861 len = plen + mlen + 1; 862 **prompts = xreallocarray(**prompts, 1, len); 863 strlcpy(**prompts + plen, msg, len - plen); 864 plen += mlen; 865 **echo_on = (type == PAM_PROMPT_ECHO_ON); 866 free(msg); 867 sshbuf_free(buffer); 868 return (0); 869 case PAM_ERROR_MSG: 870 case PAM_TEXT_INFO: 871 /* accumulate messages */ 872 len = plen + mlen + 2; 873 **prompts = xreallocarray(**prompts, 1, len); 874 strlcpy(**prompts + plen, msg, len - plen); 875 plen += mlen; 876 strlcat(**prompts + plen, "\n", len - plen); 877 plen++; 878 free(msg); 879 break; 880 case PAM_ACCT_EXPIRED: 881 case PAM_MAXTRIES: 882 if (type == PAM_ACCT_EXPIRED) 883 sshpam_account_status = 0; 884 if (type == PAM_MAXTRIES) 885 sshpam_set_maxtries_reached(1); 886 /* FALLTHROUGH */ 887 case PAM_AUTH_ERR: 888 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 889 if (**prompts != NULL && strlen(**prompts) != 0) { 890 *info = **prompts; 891 **prompts = NULL; 892 *num = 0; 893 **echo_on = 0; 894 ctxt->pam_done = -1; 895 free(msg); 896 sshbuf_free(buffer); 897 return 0; 898 } 899 /* FALLTHROUGH */ 900 case PAM_SUCCESS: 901 if (**prompts != NULL) { 902 /* drain any accumulated messages */ 903 debug("PAM: %s", **prompts); 904 if ((r = sshbuf_put(loginmsg, **prompts, 905 strlen(**prompts))) != 0) 906 fatal("%s: buffer error: %s", 907 __func__, ssh_err(r)); 908 free(**prompts); 909 **prompts = NULL; 910 } 911 if (type == PAM_SUCCESS) { 912 if (!sshpam_authctxt->valid || 913 (sshpam_authctxt->pw->pw_uid == 0 && 914 options.permit_root_login != PERMIT_YES)) 915 fatal("Internal error: PAM auth " 916 "succeeded when it should have " 917 "failed"); 918 import_environments(buffer); 919 *num = 0; 920 **echo_on = 0; 921 ctxt->pam_done = 1; 922 free(msg); 923 sshbuf_free(buffer); 924 return (0); 925 } 926 BLACKLIST_NOTIFY(NULL, BLACKLIST_BAD_USER, 927 sshpam_authctxt->user); 928 error("PAM: %s for %s%.100s from %.100s", msg, 929 sshpam_authctxt->valid ? "" : "illegal user ", 930 sshpam_authctxt->user, sshpam_rhost); 931 /* FALLTHROUGH */ 932 default: 933 *num = 0; 934 **echo_on = 0; 935 free(msg); 936 ctxt->pam_done = -1; 937 sshbuf_free(buffer); 938 return (-1); 939 } 940 } 941 sshbuf_free(buffer); 942 return (-1); 943 } 944 945 /* 946 * Returns a junk password of identical length to that the user supplied. 947 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 948 * vary processing time in proportion to password length. 949 */ 950 static char * 951 fake_password(const char *wire_password) 952 { 953 const char junk[] = "\b\n\r\177INCORRECT"; 954 char *ret = NULL; 955 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 956 957 if (l >= INT_MAX) 958 fatal("%s: password length too long: %zu", __func__, l); 959 960 ret = malloc(l + 1); 961 if (ret == NULL) 962 return NULL; 963 for (i = 0; i < l; i++) 964 ret[i] = junk[i % (sizeof(junk) - 1)]; 965 ret[i] = '\0'; 966 return ret; 967 } 968 969 /* XXX - see also comment in auth-chall.c:verify_response */ 970 static int 971 sshpam_respond(void *ctx, u_int num, char **resp) 972 { 973 struct sshbuf *buffer; 974 struct pam_ctxt *ctxt = ctx; 975 char *fake; 976 int r; 977 978 debug2("PAM: %s entering, %u responses", __func__, num); 979 switch (ctxt->pam_done) { 980 case 1: 981 sshpam_authenticated = 1; 982 return (0); 983 case 0: 984 break; 985 default: 986 return (-1); 987 } 988 if (num != 1) { 989 error("PAM: expected one response, got %u", num); 990 return (-1); 991 } 992 if ((buffer = sshbuf_new()) == NULL) 993 fatal("%s: sshbuf_new failed", __func__); 994 if (sshpam_authctxt->valid && 995 (sshpam_authctxt->pw->pw_uid != 0 || 996 options.permit_root_login == PERMIT_YES)) { 997 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 998 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 999 } else { 1000 fake = fake_password(*resp); 1001 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 1002 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1003 free(fake); 1004 } 1005 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 1006 sshbuf_free(buffer); 1007 return (-1); 1008 } 1009 sshbuf_free(buffer); 1010 return (1); 1011 } 1012 1013 static void 1014 sshpam_free_ctx(void *ctxtp) 1015 { 1016 struct pam_ctxt *ctxt = ctxtp; 1017 1018 debug3("PAM: %s entering", __func__); 1019 sshpam_thread_cleanup(); 1020 free(ctxt); 1021 /* 1022 * We don't call sshpam_cleanup() here because we may need the PAM 1023 * handle at a later stage, e.g. when setting up a session. It's 1024 * still on the cleanup list, so pam_end() *will* be called before 1025 * the server process terminates. 1026 */ 1027 } 1028 1029 KbdintDevice sshpam_device = { 1030 "pam", 1031 sshpam_init_ctx, 1032 sshpam_query, 1033 sshpam_respond, 1034 sshpam_free_ctx 1035 }; 1036 1037 KbdintDevice mm_sshpam_device = { 1038 "pam", 1039 mm_sshpam_init_ctx, 1040 mm_sshpam_query, 1041 mm_sshpam_respond, 1042 mm_sshpam_free_ctx 1043 }; 1044 1045 /* 1046 * This replaces auth-pam.c 1047 */ 1048 void 1049 start_pam(struct ssh *ssh) 1050 { 1051 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1052 1053 if (!options.use_pam) 1054 fatal("PAM: initialisation requested when UsePAM=no"); 1055 1056 if (sshpam_init(ssh, authctxt) == -1) 1057 fatal("PAM: initialisation failed"); 1058 } 1059 1060 void 1061 finish_pam(void) 1062 { 1063 sshpam_cleanup(); 1064 } 1065 1066 1067 u_int 1068 do_pam_account(void) 1069 { 1070 debug("%s: called", __func__); 1071 if (sshpam_account_status != -1) 1072 return (sshpam_account_status); 1073 1074 expose_authinfo(__func__); 1075 1076 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1077 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1078 pam_strerror(sshpam_handle, sshpam_err)); 1079 1080 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1081 sshpam_account_status = 0; 1082 return (sshpam_account_status); 1083 } 1084 1085 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1086 sshpam_password_change_required(1); 1087 1088 sshpam_account_status = 1; 1089 return (sshpam_account_status); 1090 } 1091 1092 void 1093 do_pam_setcred(int init) 1094 { 1095 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1096 (const void *)&store_conv); 1097 if (sshpam_err != PAM_SUCCESS) 1098 fatal("PAM: failed to set PAM_CONV: %s", 1099 pam_strerror(sshpam_handle, sshpam_err)); 1100 if (init) { 1101 debug("PAM: establishing credentials"); 1102 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1103 } else { 1104 debug("PAM: reinitializing credentials"); 1105 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1106 } 1107 if (sshpam_err == PAM_SUCCESS) { 1108 sshpam_cred_established = 1; 1109 return; 1110 } 1111 if (sshpam_authenticated) 1112 fatal("PAM: pam_setcred(): %s", 1113 pam_strerror(sshpam_handle, sshpam_err)); 1114 else 1115 debug("PAM: pam_setcred(): %s", 1116 pam_strerror(sshpam_handle, sshpam_err)); 1117 } 1118 1119 static int 1120 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1121 struct pam_response **resp, void *data) 1122 { 1123 char input[PAM_MAX_MSG_SIZE]; 1124 struct pam_response *reply; 1125 int i; 1126 1127 debug3("PAM: %s called with %d messages", __func__, n); 1128 1129 *resp = NULL; 1130 1131 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1132 return (PAM_CONV_ERR); 1133 1134 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1135 return (PAM_CONV_ERR); 1136 1137 for (i = 0; i < n; ++i) { 1138 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1139 case PAM_PROMPT_ECHO_OFF: 1140 reply[i].resp = 1141 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1142 RP_ALLOW_STDIN); 1143 reply[i].resp_retcode = PAM_SUCCESS; 1144 break; 1145 case PAM_PROMPT_ECHO_ON: 1146 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1147 if (fgets(input, sizeof input, stdin) == NULL) 1148 input[0] = '\0'; 1149 if ((reply[i].resp = strdup(input)) == NULL) 1150 goto fail; 1151 reply[i].resp_retcode = PAM_SUCCESS; 1152 break; 1153 case PAM_ERROR_MSG: 1154 case PAM_TEXT_INFO: 1155 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1156 reply[i].resp_retcode = PAM_SUCCESS; 1157 break; 1158 default: 1159 goto fail; 1160 } 1161 } 1162 *resp = reply; 1163 return (PAM_SUCCESS); 1164 1165 fail: 1166 for(i = 0; i < n; i++) { 1167 free(reply[i].resp); 1168 } 1169 free(reply); 1170 return (PAM_CONV_ERR); 1171 } 1172 1173 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1174 1175 /* 1176 * XXX this should be done in the authentication phase, but ssh1 doesn't 1177 * support that 1178 */ 1179 void 1180 do_pam_chauthtok(void) 1181 { 1182 if (use_privsep) 1183 fatal("Password expired (unable to change with privsep)"); 1184 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1185 (const void *)&tty_conv); 1186 if (sshpam_err != PAM_SUCCESS) 1187 fatal("PAM: failed to set PAM_CONV: %s", 1188 pam_strerror(sshpam_handle, sshpam_err)); 1189 debug("PAM: changing password"); 1190 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1191 if (sshpam_err != PAM_SUCCESS) 1192 fatal("PAM: pam_chauthtok(): %s", 1193 pam_strerror(sshpam_handle, sshpam_err)); 1194 } 1195 1196 void 1197 do_pam_session(struct ssh *ssh) 1198 { 1199 debug3("PAM: opening session"); 1200 1201 expose_authinfo(__func__); 1202 1203 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1204 (const void *)&store_conv); 1205 if (sshpam_err != PAM_SUCCESS) 1206 fatal("PAM: failed to set PAM_CONV: %s", 1207 pam_strerror(sshpam_handle, sshpam_err)); 1208 sshpam_err = pam_open_session(sshpam_handle, 0); 1209 if (sshpam_err == PAM_SUCCESS) 1210 sshpam_session_open = 1; 1211 else { 1212 sshpam_session_open = 0; 1213 auth_restrict_session(ssh); 1214 error("PAM: pam_open_session(): %s", 1215 pam_strerror(sshpam_handle, sshpam_err)); 1216 } 1217 1218 } 1219 1220 int 1221 is_pam_session_open(void) 1222 { 1223 return sshpam_session_open; 1224 } 1225 1226 /* 1227 * Set a PAM environment string. We need to do this so that the session 1228 * modules can handle things like Kerberos/GSI credentials that appear 1229 * during the ssh authentication process. 1230 */ 1231 int 1232 do_pam_putenv(char *name, char *value) 1233 { 1234 int ret = 1; 1235 char *compound; 1236 size_t len; 1237 1238 len = strlen(name) + strlen(value) + 2; 1239 compound = xmalloc(len); 1240 1241 snprintf(compound, len, "%s=%s", name, value); 1242 ret = pam_putenv(sshpam_handle, compound); 1243 free(compound); 1244 1245 return (ret); 1246 } 1247 1248 char ** 1249 fetch_pam_child_environment(void) 1250 { 1251 return sshpam_env; 1252 } 1253 1254 char ** 1255 fetch_pam_environment(void) 1256 { 1257 return (pam_getenvlist(sshpam_handle)); 1258 } 1259 1260 void 1261 free_pam_environment(char **env) 1262 { 1263 char **envp; 1264 1265 if (env == NULL) 1266 return; 1267 1268 for (envp = env; *envp; envp++) 1269 free(*envp); 1270 free(env); 1271 } 1272 1273 /* 1274 * "Blind" conversation function for password authentication. Assumes that 1275 * echo-off prompts are for the password and stores messages for later 1276 * display. 1277 */ 1278 static int 1279 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1280 struct pam_response **resp, void *data) 1281 { 1282 struct pam_response *reply; 1283 int r, i; 1284 size_t len; 1285 1286 debug3("PAM: %s called with %d messages", __func__, n); 1287 1288 *resp = NULL; 1289 1290 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1291 return (PAM_CONV_ERR); 1292 1293 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1294 return (PAM_CONV_ERR); 1295 1296 for (i = 0; i < n; ++i) { 1297 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1298 case PAM_PROMPT_ECHO_OFF: 1299 if (sshpam_password == NULL) 1300 goto fail; 1301 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1302 goto fail; 1303 reply[i].resp_retcode = PAM_SUCCESS; 1304 break; 1305 case PAM_ERROR_MSG: 1306 case PAM_TEXT_INFO: 1307 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1308 if (len > 0) { 1309 if ((r = sshbuf_putf(loginmsg, "%s\n", 1310 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1311 fatal("%s: buffer error: %s", 1312 __func__, ssh_err(r)); 1313 } 1314 if ((reply[i].resp = strdup("")) == NULL) 1315 goto fail; 1316 reply[i].resp_retcode = PAM_SUCCESS; 1317 break; 1318 default: 1319 goto fail; 1320 } 1321 } 1322 *resp = reply; 1323 return (PAM_SUCCESS); 1324 1325 fail: 1326 for(i = 0; i < n; i++) { 1327 free(reply[i].resp); 1328 } 1329 free(reply); 1330 return (PAM_CONV_ERR); 1331 } 1332 1333 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1334 1335 /* 1336 * Attempt password authentication via PAM 1337 */ 1338 int 1339 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1340 { 1341 int flags = (options.permit_empty_passwd == 0 ? 1342 PAM_DISALLOW_NULL_AUTHTOK : 0); 1343 char *fake = NULL; 1344 1345 if (!options.use_pam || sshpam_handle == NULL) 1346 fatal("PAM: %s called when PAM disabled or failed to " 1347 "initialise.", __func__); 1348 1349 sshpam_password = password; 1350 sshpam_authctxt = authctxt; 1351 1352 /* 1353 * If the user logging in is invalid, or is root but is not permitted 1354 * by PermitRootLogin, use an invalid password to prevent leaking 1355 * information via timing (eg if the PAM config has a delay on fail). 1356 */ 1357 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1358 options.permit_root_login != PERMIT_YES)) 1359 sshpam_password = fake = fake_password(password); 1360 1361 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1362 (const void *)&passwd_conv); 1363 if (sshpam_err != PAM_SUCCESS) 1364 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1365 pam_strerror(sshpam_handle, sshpam_err)); 1366 1367 sshpam_err = pam_authenticate(sshpam_handle, flags); 1368 sshpam_password = NULL; 1369 free(fake); 1370 if (sshpam_err == PAM_MAXTRIES) 1371 sshpam_set_maxtries_reached(1); 1372 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1373 debug("PAM: password authentication accepted for %.100s", 1374 authctxt->user); 1375 return 1; 1376 } else { 1377 debug("PAM: password authentication failed for %.100s: %s", 1378 authctxt->valid ? authctxt->user : "an illegal user", 1379 pam_strerror(sshpam_handle, sshpam_err)); 1380 return 0; 1381 } 1382 } 1383 1384 int 1385 sshpam_get_maxtries_reached(void) 1386 { 1387 return sshpam_maxtries_reached; 1388 } 1389 1390 void 1391 sshpam_set_maxtries_reached(int reached) 1392 { 1393 if (reached == 0 || sshpam_maxtries_reached) 1394 return; 1395 sshpam_maxtries_reached = 1; 1396 options.password_authentication = 0; 1397 options.kbd_interactive_authentication = 0; 1398 } 1399 #endif /* USE_PAM */ 1400