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