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; 256 257 /* Some PAM implementations don't implement this */ 258 #ifndef HAVE_PAM_GETENVLIST 259 static char ** 260 pam_getenvlist(pam_handle_t *pamh) 261 { 262 /* 263 * XXX - If necessary, we can still support environment passing 264 * for platforms without pam_getenvlist by searching for known 265 * env vars (e.g. KRB5CCNAME) from the PAM environment. 266 */ 267 return NULL; 268 } 269 #endif 270 271 #ifndef HAVE_PAM_PUTENV 272 static int 273 pam_putenv(pam_handle_t *pamh, const char *name_value) 274 { 275 return PAM_SUCCESS; 276 } 277 #endif /* HAVE_PAM_PUTENV */ 278 279 /* 280 * Some platforms, notably Solaris, do not enforce password complexity 281 * rules during pam_chauthtok() if the real uid of the calling process 282 * is 0, on the assumption that it's being called by "passwd" run by root. 283 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 284 * the right thing. 285 */ 286 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 287 static int 288 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 289 { 290 int result; 291 292 if (sshpam_authctxt == NULL) 293 fatal("PAM: sshpam_authctxt not initialized"); 294 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 295 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 296 result = pam_chauthtok(pamh, flags); 297 if (setreuid(0, -1) == -1) 298 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 299 return result; 300 } 301 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 302 #endif 303 304 static void 305 sshpam_password_change_required(int reqd) 306 { 307 extern struct sshauthopt *auth_opts; 308 static int saved_port, saved_agent, saved_x11; 309 310 debug3("%s %d", __func__, reqd); 311 if (sshpam_authctxt == NULL) 312 fatal("%s: PAM authctxt not initialized", __func__); 313 sshpam_authctxt->force_pwchange = reqd; 314 if (reqd) { 315 saved_port = auth_opts->permit_port_forwarding_flag; 316 saved_agent = auth_opts->permit_agent_forwarding_flag; 317 saved_x11 = auth_opts->permit_x11_forwarding_flag; 318 auth_opts->permit_port_forwarding_flag = 0; 319 auth_opts->permit_agent_forwarding_flag = 0; 320 auth_opts->permit_x11_forwarding_flag = 0; 321 } else { 322 if (saved_port) 323 auth_opts->permit_port_forwarding_flag = saved_port; 324 if (saved_agent) 325 auth_opts->permit_agent_forwarding_flag = saved_agent; 326 if (saved_x11) 327 auth_opts->permit_x11_forwarding_flag = saved_x11; 328 } 329 } 330 331 /* Import regular and PAM environment from subprocess */ 332 static void 333 import_environments(struct sshbuf *b) 334 { 335 char *env; 336 u_int n, i, num_env; 337 int r; 338 339 debug3("PAM: %s entering", __func__); 340 341 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 342 /* Import variables set by do_pam_account */ 343 if ((r = sshbuf_get_u32(b, &n)) != 0) 344 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 345 if (n > INT_MAX) 346 fatal("%s: invalid PAM account status %u", __func__, n); 347 sshpam_account_status = (int)n; 348 if ((r = sshbuf_get_u32(b, &n)) != 0) 349 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 350 sshpam_password_change_required(n != 0); 351 352 /* Import environment from subprocess */ 353 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 354 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 355 if (num_env > 1024) { 356 fatal_f("received %u environment variables, expected <= 1024", 357 num_env); 358 } 359 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 360 debug3("PAM: num env strings %u", 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 if (num_env > 1024) { 371 fatal_f("received %u PAM env variables, expected <= 1024", 372 num_env); 373 } 374 debug("PAM: num PAM env strings %u", num_env); 375 for (i = 0; i < num_env; i++) { 376 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0) 377 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 378 /* Errors are not fatal here */ 379 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 380 error("PAM: pam_putenv: %s", 381 pam_strerror(sshpam_handle, r)); 382 } 383 /* 384 * XXX this possibly leaks env because it is not documented 385 * what pam_putenv() does with it. Does it copy it? Does it 386 * take ownweship? We don't know, so it's safest just to leak. 387 */ 388 } 389 #endif 390 } 391 392 /* 393 * Conversation function for authentication thread. 394 */ 395 static int 396 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 397 struct pam_response **resp, void *data) 398 { 399 struct sshbuf *buffer; 400 struct pam_ctxt *ctxt; 401 struct pam_response *reply; 402 int r, i; 403 u_char status; 404 405 debug3("PAM: %s entering, %d messages", __func__, n); 406 *resp = NULL; 407 408 if (data == NULL) { 409 error("PAM: conversation function passed a null context"); 410 return (PAM_CONV_ERR); 411 } 412 ctxt = data; 413 if (n <= 0 || n > PAM_MAX_NUM_MSG) 414 return (PAM_CONV_ERR); 415 416 if ((reply = calloc(n, sizeof(*reply))) == NULL) 417 return PAM_CONV_ERR; 418 if ((buffer = sshbuf_new()) == NULL) { 419 free(reply); 420 return PAM_CONV_ERR; 421 } 422 423 for (i = 0; i < n; ++i) { 424 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 425 case PAM_PROMPT_ECHO_OFF: 426 case PAM_PROMPT_ECHO_ON: 427 if ((r = sshbuf_put_cstring(buffer, 428 PAM_MSG_MEMBER(msg, i, msg))) != 0) 429 fatal("%s: buffer error: %s", 430 __func__, ssh_err(r)); 431 if (ssh_msg_send(ctxt->pam_csock, 432 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 433 goto fail; 434 435 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 436 goto fail; 437 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 438 fatal("%s: buffer error: %s", 439 __func__, ssh_err(r)); 440 if (status != PAM_AUTHTOK) 441 goto fail; 442 if ((r = sshbuf_get_cstring(buffer, 443 &reply[i].resp, NULL)) != 0) 444 fatal("%s: buffer error: %s", 445 __func__, ssh_err(r)); 446 break; 447 case PAM_ERROR_MSG: 448 case PAM_TEXT_INFO: 449 if ((r = sshbuf_put_cstring(buffer, 450 PAM_MSG_MEMBER(msg, i, msg))) != 0) 451 fatal("%s: buffer error: %s", 452 __func__, ssh_err(r)); 453 if (ssh_msg_send(ctxt->pam_csock, 454 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 455 goto fail; 456 break; 457 default: 458 goto fail; 459 } 460 sshbuf_reset(buffer); 461 } 462 sshbuf_free(buffer); 463 *resp = reply; 464 return (PAM_SUCCESS); 465 466 fail: 467 for(i = 0; i < n; i++) { 468 free(reply[i].resp); 469 } 470 free(reply); 471 sshbuf_free(buffer); 472 return (PAM_CONV_ERR); 473 } 474 475 /* 476 * Authentication thread. 477 */ 478 static void * 479 sshpam_thread(void *ctxtp) 480 { 481 struct pam_ctxt *ctxt = ctxtp; 482 struct sshbuf *buffer = NULL; 483 struct pam_conv sshpam_conv; 484 int r, flags = (options.permit_empty_passwd == 0 ? 485 PAM_DISALLOW_NULL_AUTHTOK : 0); 486 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 487 extern char **environ; 488 char **env_from_pam; 489 u_int i; 490 const char *pam_user; 491 const char **ptr_pam_user = &pam_user; 492 char *tz = getenv("TZ"); 493 494 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 495 (sshpam_const void **)ptr_pam_user); 496 if (sshpam_err != PAM_SUCCESS) 497 goto auth_fail; 498 499 environ[0] = NULL; 500 if (tz != NULL) 501 if (setenv("TZ", tz, 1) == -1) 502 error("PAM: could not set TZ environment: %s", 503 strerror(errno)); 504 505 if (sshpam_authctxt != NULL) { 506 setproctitle("%s [pam]", 507 sshpam_authctxt->valid ? pam_user : "unknown"); 508 } 509 #endif 510 511 sshpam_conv.conv = sshpam_thread_conv; 512 sshpam_conv.appdata_ptr = ctxt; 513 514 if (sshpam_authctxt == NULL) 515 fatal("%s: PAM authctxt not initialized", __func__); 516 517 if ((buffer = sshbuf_new()) == NULL) 518 fatal("%s: sshbuf_new failed", __func__); 519 520 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 521 (const void *)&sshpam_conv); 522 if (sshpam_err != PAM_SUCCESS) 523 goto auth_fail; 524 sshpam_err = pam_authenticate(sshpam_handle, flags); 525 if (sshpam_err == PAM_MAXTRIES) 526 sshpam_set_maxtries_reached(1); 527 if (sshpam_err != PAM_SUCCESS) 528 goto auth_fail; 529 530 if (!do_pam_account()) { 531 sshpam_err = PAM_ACCT_EXPIRED; 532 goto auth_fail; 533 } 534 if (sshpam_authctxt->force_pwchange) { 535 sshpam_err = pam_chauthtok(sshpam_handle, 536 PAM_CHANGE_EXPIRED_AUTHTOK); 537 if (sshpam_err != PAM_SUCCESS) 538 goto auth_fail; 539 sshpam_password_change_required(0); 540 } 541 542 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 543 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 544 545 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 546 /* Export variables set by do_pam_account */ 547 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 548 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 549 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 550 551 /* Export any environment strings set in child */ 552 for (i = 0; environ[i] != NULL; i++) { 553 /* Count */ 554 if (i > INT_MAX) 555 fatal("%s: too many environment strings", __func__); 556 } 557 if ((r = sshbuf_put_u32(buffer, i)) != 0) 558 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 559 for (i = 0; environ[i] != NULL; i++) { 560 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 561 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 562 } 563 /* Export any environment strings set by PAM in child */ 564 env_from_pam = pam_getenvlist(sshpam_handle); 565 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 566 /* Count */ 567 if (i > INT_MAX) 568 fatal("%s: too many PAM environment strings", __func__); 569 } 570 if ((r = sshbuf_put_u32(buffer, i)) != 0) 571 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 572 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 573 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 574 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 575 } 576 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 577 578 /* XXX - can't do much about an error here */ 579 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 580 sshbuf_free(buffer); 581 pthread_exit(NULL); 582 583 auth_fail: 584 if ((r = sshbuf_put_cstring(buffer, 585 pam_strerror(sshpam_handle, sshpam_err))) != 0) 586 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 587 /* XXX - can't do much about an error here */ 588 if (sshpam_err == PAM_ACCT_EXPIRED) 589 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 590 else if (sshpam_maxtries_reached) 591 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 592 else 593 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 594 sshbuf_free(buffer); 595 pthread_exit(NULL); 596 597 return (NULL); /* Avoid warning for non-pthread case */ 598 } 599 600 void 601 sshpam_thread_cleanup(void) 602 { 603 struct pam_ctxt *ctxt = cleanup_ctxt; 604 605 debug3("PAM: %s entering", __func__); 606 if (ctxt != NULL && ctxt->pam_thread != 0) { 607 pthread_cancel(ctxt->pam_thread); 608 pthread_join(ctxt->pam_thread, NULL); 609 close(ctxt->pam_psock); 610 close(ctxt->pam_csock); 611 memset(ctxt, 0, sizeof(*ctxt)); 612 cleanup_ctxt = NULL; 613 } 614 } 615 616 static int 617 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 618 struct pam_response **resp, void *data) 619 { 620 debug3("PAM: %s entering, %d messages", __func__, n); 621 return (PAM_CONV_ERR); 622 } 623 624 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 625 626 static int 627 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 628 struct pam_response **resp, void *data) 629 { 630 struct pam_response *reply; 631 int r, i; 632 633 debug3("PAM: %s called with %d messages", __func__, n); 634 *resp = NULL; 635 636 if (n <= 0 || n > PAM_MAX_NUM_MSG) 637 return (PAM_CONV_ERR); 638 639 if ((reply = calloc(n, sizeof(*reply))) == NULL) 640 return (PAM_CONV_ERR); 641 642 for (i = 0; i < n; ++i) { 643 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 644 case PAM_ERROR_MSG: 645 case PAM_TEXT_INFO: 646 if ((r = sshbuf_putf(loginmsg, "%s\n", 647 PAM_MSG_MEMBER(msg, i, msg))) != 0) 648 fatal("%s: buffer error: %s", 649 __func__, ssh_err(r)); 650 reply[i].resp_retcode = PAM_SUCCESS; 651 break; 652 default: 653 goto fail; 654 } 655 } 656 *resp = reply; 657 return (PAM_SUCCESS); 658 659 fail: 660 for(i = 0; i < n; i++) { 661 free(reply[i].resp); 662 } 663 free(reply); 664 return (PAM_CONV_ERR); 665 } 666 667 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 668 669 void 670 sshpam_cleanup(void) 671 { 672 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 673 return; 674 debug("PAM: cleanup"); 675 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 676 if (sshpam_session_open) { 677 debug("PAM: closing session"); 678 pam_close_session(sshpam_handle, PAM_SILENT); 679 sshpam_session_open = 0; 680 } 681 if (sshpam_cred_established) { 682 debug("PAM: deleting credentials"); 683 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 684 sshpam_cred_established = 0; 685 } 686 sshpam_authenticated = 0; 687 pam_end(sshpam_handle, sshpam_err); 688 sshpam_handle = NULL; 689 } 690 691 static int 692 sshpam_init(struct ssh *ssh, Authctxt *authctxt) 693 { 694 const char *pam_user, *user = authctxt->user; 695 const char **ptr_pam_user = &pam_user; 696 int r; 697 698 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE) 699 /* Protect buggy PAM implementations from excessively long usernames */ 700 if (strlen(user) >= PAM_MAX_RESP_SIZE) 701 fatal("Username too long from %s port %d", 702 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 703 #endif 704 if (sshpam_handle == NULL) { 705 if (ssh == NULL) { 706 fatal("%s: called initially with no " 707 "packet context", __func__); 708 } 709 } if (sshpam_handle != NULL) { 710 /* We already have a PAM context; check if the user matches */ 711 sshpam_err = pam_get_item(sshpam_handle, 712 PAM_USER, (sshpam_const void **)ptr_pam_user); 713 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 714 return (0); 715 pam_end(sshpam_handle, sshpam_err); 716 sshpam_handle = NULL; 717 } 718 debug("PAM: initializing for \"%s\"", user); 719 sshpam_err = 720 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 721 sshpam_authctxt = authctxt; 722 723 if (sshpam_err != PAM_SUCCESS) { 724 pam_end(sshpam_handle, sshpam_err); 725 sshpam_handle = NULL; 726 return (-1); 727 } 728 729 if (ssh != NULL && sshpam_rhost == NULL) { 730 /* 731 * We need to cache these as we don't have packet context 732 * during the kbdint flow. 733 */ 734 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh, 735 options.use_dns)); 736 sshpam_laddr = get_local_ipaddr( 737 ssh_packet_get_connection_in(ssh)); 738 } 739 if (sshpam_rhost != NULL) { 740 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); 741 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, 742 sshpam_rhost); 743 if (sshpam_err != PAM_SUCCESS) { 744 pam_end(sshpam_handle, sshpam_err); 745 sshpam_handle = NULL; 746 return (-1); 747 } 748 } 749 if (ssh != NULL && sshpam_laddr != NULL) { 750 char *conninfo; 751 752 /* Put SSH_CONNECTION in the PAM environment too */ 753 xasprintf(&conninfo, "SSH_CONNECTION=%.50s %d %.50s %d", 754 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 755 sshpam_laddr, ssh_local_port(ssh)); 756 if ((r = pam_putenv(sshpam_handle, conninfo)) != PAM_SUCCESS) 757 logit("pam_putenv: %s", pam_strerror(sshpam_handle, r)); 758 free(conninfo); 759 } 760 761 #ifdef PAM_TTY_KLUDGE 762 /* 763 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 764 * sshd doesn't set the tty until too late in the auth process and 765 * may not even set one (for tty-less connections) 766 */ 767 debug("PAM: setting PAM_TTY to \"ssh\""); 768 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 769 if (sshpam_err != PAM_SUCCESS) { 770 pam_end(sshpam_handle, sshpam_err); 771 sshpam_handle = NULL; 772 return (-1); 773 } 774 #endif 775 return (0); 776 } 777 778 static void 779 expose_authinfo(const char *caller) 780 { 781 char *auth_info; 782 783 /* 784 * Expose authentication information to PAM. 785 * The environment variable is versioned. Please increment the 786 * version suffix if the format of session_info changes. 787 */ 788 if (sshpam_authctxt->session_info == NULL) 789 auth_info = xstrdup(""); 790 else if ((auth_info = sshbuf_dup_string( 791 sshpam_authctxt->session_info)) == NULL) 792 fatal("%s: sshbuf_dup_string failed", __func__); 793 794 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 795 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 796 free(auth_info); 797 } 798 799 static void * 800 sshpam_init_ctx(Authctxt *authctxt) 801 { 802 struct pam_ctxt *ctxt; 803 int result, socks[2]; 804 805 debug3("PAM: %s entering", __func__); 806 /* 807 * Refuse to start if we don't have PAM enabled or do_pam_account 808 * has previously failed. 809 */ 810 if (!options.use_pam || sshpam_account_status == 0) 811 return NULL; 812 813 /* Initialize PAM */ 814 if (sshpam_init(NULL, authctxt) == -1) { 815 error("PAM: initialization failed"); 816 return (NULL); 817 } 818 819 expose_authinfo(__func__); 820 ctxt = xcalloc(1, sizeof *ctxt); 821 822 /* Start the authentication thread */ 823 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 824 error("PAM: failed create sockets: %s", strerror(errno)); 825 free(ctxt); 826 return (NULL); 827 } 828 ctxt->pam_psock = socks[0]; 829 ctxt->pam_csock = socks[1]; 830 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt); 831 if (result != 0) { 832 error("PAM: failed to start authentication thread: %s", 833 strerror(result)); 834 close(socks[0]); 835 close(socks[1]); 836 free(ctxt); 837 return (NULL); 838 } 839 cleanup_ctxt = ctxt; 840 return (ctxt); 841 } 842 843 static int 844 sshpam_query(void *ctx, char **name, char **info, 845 u_int *num, char ***prompts, u_int **echo_on) 846 { 847 struct sshbuf *buffer; 848 struct pam_ctxt *ctxt = ctx; 849 size_t plen; 850 u_char type; 851 char *msg; 852 size_t len, mlen, nmesg = 0; 853 int r; 854 855 debug3("PAM: %s entering", __func__); 856 if ((buffer = sshbuf_new()) == NULL) 857 fatal("%s: sshbuf_new failed", __func__); 858 *name = xstrdup(""); 859 *info = xstrdup(""); 860 *prompts = xmalloc(sizeof(char *)); 861 **prompts = NULL; 862 plen = 0; 863 *echo_on = xmalloc(sizeof(u_int)); 864 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 865 if (++nmesg > PAM_MAX_NUM_MSG) 866 fatal_f("too many query messages"); 867 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 868 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 869 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 870 switch (type) { 871 case PAM_PROMPT_ECHO_ON: 872 case PAM_PROMPT_ECHO_OFF: 873 *num = 1; 874 len = plen + mlen + 1; 875 **prompts = xreallocarray(**prompts, 1, len); 876 strlcpy(**prompts + plen, msg, len - plen); 877 plen += mlen; 878 **echo_on = (type == PAM_PROMPT_ECHO_ON); 879 free(msg); 880 sshbuf_free(buffer); 881 return (0); 882 case PAM_ERROR_MSG: 883 case PAM_TEXT_INFO: 884 /* accumulate messages */ 885 len = plen + mlen + 2; 886 **prompts = xreallocarray(**prompts, 1, len); 887 strlcpy(**prompts + plen, msg, len - plen); 888 plen += mlen; 889 strlcat(**prompts + plen, "\n", len - plen); 890 plen++; 891 free(msg); 892 break; 893 case PAM_ACCT_EXPIRED: 894 case PAM_MAXTRIES: 895 if (type == PAM_ACCT_EXPIRED) 896 sshpam_account_status = 0; 897 if (type == PAM_MAXTRIES) 898 sshpam_set_maxtries_reached(1); 899 /* FALLTHROUGH */ 900 case PAM_AUTH_ERR: 901 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 902 if (**prompts != NULL && strlen(**prompts) != 0) { 903 free(*info); 904 *info = **prompts; 905 **prompts = NULL; 906 *num = 0; 907 **echo_on = 0; 908 ctxt->pam_done = -1; 909 free(msg); 910 sshbuf_free(buffer); 911 return 0; 912 } 913 /* FALLTHROUGH */ 914 case PAM_SUCCESS: 915 if (**prompts != NULL) { 916 /* drain any accumulated messages */ 917 debug("PAM: %s", **prompts); 918 if ((r = sshbuf_put(loginmsg, **prompts, 919 strlen(**prompts))) != 0) 920 fatal("%s: buffer error: %s", 921 __func__, ssh_err(r)); 922 free(**prompts); 923 **prompts = NULL; 924 } 925 if (type == PAM_SUCCESS) { 926 if (!sshpam_authctxt->valid || 927 (sshpam_authctxt->pw->pw_uid == 0 && 928 options.permit_root_login != PERMIT_YES)) 929 fatal("Internal error: PAM auth " 930 "succeeded when it should have " 931 "failed"); 932 import_environments(buffer); 933 *num = 0; 934 **echo_on = 0; 935 ctxt->pam_done = 1; 936 free(msg); 937 sshbuf_free(buffer); 938 return (0); 939 } 940 BLACKLIST_NOTIFY(NULL, BLACKLIST_BAD_USER, 941 sshpam_authctxt->user); 942 error("PAM: %s for %s%.100s from %.100s", msg, 943 sshpam_authctxt->valid ? "" : "illegal user ", 944 sshpam_authctxt->user, sshpam_rhost); 945 /* FALLTHROUGH */ 946 default: 947 *num = 0; 948 **echo_on = 0; 949 free(msg); 950 ctxt->pam_done = -1; 951 sshbuf_free(buffer); 952 return (-1); 953 } 954 } 955 sshbuf_free(buffer); 956 return (-1); 957 } 958 959 /* 960 * Returns a junk password of identical length to that the user supplied. 961 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 962 * vary processing time in proportion to password length. 963 */ 964 static char * 965 fake_password(const char *wire_password) 966 { 967 const char junk[] = "\b\n\r\177INCORRECT"; 968 char *ret = NULL; 969 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 970 971 if (l >= INT_MAX) 972 fatal("%s: password length too long: %zu", __func__, l); 973 974 ret = malloc(l + 1); 975 if (ret == NULL) 976 return NULL; 977 for (i = 0; i < l; i++) 978 ret[i] = junk[i % (sizeof(junk) - 1)]; 979 ret[i] = '\0'; 980 return ret; 981 } 982 983 /* XXX - see also comment in auth-chall.c:verify_response */ 984 static int 985 sshpam_respond(void *ctx, u_int num, char **resp) 986 { 987 struct sshbuf *buffer; 988 struct pam_ctxt *ctxt = ctx; 989 char *fake; 990 int r; 991 992 debug2("PAM: %s entering, %u responses", __func__, num); 993 switch (ctxt->pam_done) { 994 case 1: 995 sshpam_authenticated = 1; 996 return (0); 997 case 0: 998 break; 999 default: 1000 return (-1); 1001 } 1002 if (num != 1) { 1003 error("PAM: expected one response, got %u", num); 1004 return (-1); 1005 } 1006 if ((buffer = sshbuf_new()) == NULL) 1007 fatal("%s: sshbuf_new failed", __func__); 1008 if (sshpam_authctxt->valid && 1009 (sshpam_authctxt->pw->pw_uid != 0 || 1010 options.permit_root_login == PERMIT_YES)) { 1011 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 1012 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1013 } else { 1014 fake = fake_password(*resp); 1015 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 1016 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1017 free(fake); 1018 } 1019 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 1020 sshbuf_free(buffer); 1021 return (-1); 1022 } 1023 sshbuf_free(buffer); 1024 return (1); 1025 } 1026 1027 static void 1028 sshpam_free_ctx(void *ctxtp) 1029 { 1030 struct pam_ctxt *ctxt = ctxtp; 1031 1032 debug3("PAM: %s entering", __func__); 1033 sshpam_thread_cleanup(); 1034 free(ctxt); 1035 /* 1036 * We don't call sshpam_cleanup() here because we may need the PAM 1037 * handle at a later stage, e.g. when setting up a session. It's 1038 * still on the cleanup list, so pam_end() *will* be called before 1039 * the server process terminates. 1040 */ 1041 } 1042 1043 KbdintDevice sshpam_device = { 1044 "pam", 1045 sshpam_init_ctx, 1046 sshpam_query, 1047 sshpam_respond, 1048 sshpam_free_ctx 1049 }; 1050 1051 KbdintDevice mm_sshpam_device = { 1052 "pam", 1053 mm_sshpam_init_ctx, 1054 mm_sshpam_query, 1055 mm_sshpam_respond, 1056 mm_sshpam_free_ctx 1057 }; 1058 1059 /* 1060 * This replaces auth-pam.c 1061 */ 1062 void 1063 start_pam(struct ssh *ssh) 1064 { 1065 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1066 1067 if (!options.use_pam) 1068 fatal("PAM: initialisation requested when UsePAM=no"); 1069 1070 if (sshpam_init(ssh, authctxt) == -1) 1071 fatal("PAM: initialisation failed"); 1072 } 1073 1074 void 1075 finish_pam(void) 1076 { 1077 sshpam_cleanup(); 1078 } 1079 1080 1081 u_int 1082 do_pam_account(void) 1083 { 1084 debug("%s: called", __func__); 1085 if (sshpam_account_status != -1) 1086 return (sshpam_account_status); 1087 1088 expose_authinfo(__func__); 1089 1090 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1091 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1092 pam_strerror(sshpam_handle, sshpam_err)); 1093 1094 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1095 sshpam_account_status = 0; 1096 return (sshpam_account_status); 1097 } 1098 1099 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1100 sshpam_password_change_required(1); 1101 1102 sshpam_account_status = 1; 1103 return (sshpam_account_status); 1104 } 1105 1106 void 1107 do_pam_setcred(int init) 1108 { 1109 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1110 (const void *)&store_conv); 1111 if (sshpam_err != PAM_SUCCESS) 1112 fatal("PAM: failed to set PAM_CONV: %s", 1113 pam_strerror(sshpam_handle, sshpam_err)); 1114 if (init) { 1115 debug("PAM: establishing credentials"); 1116 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1117 } else { 1118 debug("PAM: reinitializing credentials"); 1119 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1120 } 1121 if (sshpam_err == PAM_SUCCESS) { 1122 sshpam_cred_established = 1; 1123 return; 1124 } 1125 if (sshpam_authenticated) 1126 fatal("PAM: pam_setcred(): %s", 1127 pam_strerror(sshpam_handle, sshpam_err)); 1128 else 1129 debug("PAM: pam_setcred(): %s", 1130 pam_strerror(sshpam_handle, sshpam_err)); 1131 } 1132 1133 static int 1134 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1135 struct pam_response **resp, void *data) 1136 { 1137 char input[PAM_MAX_MSG_SIZE]; 1138 struct pam_response *reply; 1139 int i; 1140 1141 debug3("PAM: %s called with %d messages", __func__, n); 1142 1143 *resp = NULL; 1144 1145 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1146 return (PAM_CONV_ERR); 1147 1148 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1149 return (PAM_CONV_ERR); 1150 1151 for (i = 0; i < n; ++i) { 1152 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1153 case PAM_PROMPT_ECHO_OFF: 1154 reply[i].resp = 1155 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1156 RP_ALLOW_STDIN); 1157 reply[i].resp_retcode = PAM_SUCCESS; 1158 break; 1159 case PAM_PROMPT_ECHO_ON: 1160 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1161 if (fgets(input, sizeof input, stdin) == NULL) 1162 input[0] = '\0'; 1163 if ((reply[i].resp = strdup(input)) == NULL) 1164 goto fail; 1165 reply[i].resp_retcode = PAM_SUCCESS; 1166 break; 1167 case PAM_ERROR_MSG: 1168 case PAM_TEXT_INFO: 1169 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1170 reply[i].resp_retcode = PAM_SUCCESS; 1171 break; 1172 default: 1173 goto fail; 1174 } 1175 } 1176 *resp = reply; 1177 return (PAM_SUCCESS); 1178 1179 fail: 1180 for(i = 0; i < n; i++) { 1181 free(reply[i].resp); 1182 } 1183 free(reply); 1184 return (PAM_CONV_ERR); 1185 } 1186 1187 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1188 1189 /* 1190 * XXX this should be done in the authentication phase, but ssh1 doesn't 1191 * support that 1192 */ 1193 void 1194 do_pam_chauthtok(void) 1195 { 1196 if (use_privsep) 1197 fatal("Password expired (unable to change with privsep)"); 1198 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1199 (const void *)&tty_conv); 1200 if (sshpam_err != PAM_SUCCESS) 1201 fatal("PAM: failed to set PAM_CONV: %s", 1202 pam_strerror(sshpam_handle, sshpam_err)); 1203 debug("PAM: changing password"); 1204 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1205 if (sshpam_err != PAM_SUCCESS) 1206 fatal("PAM: pam_chauthtok(): %s", 1207 pam_strerror(sshpam_handle, sshpam_err)); 1208 } 1209 1210 void 1211 do_pam_session(struct ssh *ssh) 1212 { 1213 debug3("PAM: opening session"); 1214 1215 expose_authinfo(__func__); 1216 1217 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1218 (const void *)&store_conv); 1219 if (sshpam_err != PAM_SUCCESS) 1220 fatal("PAM: failed to set PAM_CONV: %s", 1221 pam_strerror(sshpam_handle, sshpam_err)); 1222 sshpam_err = pam_open_session(sshpam_handle, 0); 1223 if (sshpam_err == PAM_SUCCESS) 1224 sshpam_session_open = 1; 1225 else { 1226 sshpam_session_open = 0; 1227 auth_restrict_session(ssh); 1228 error("PAM: pam_open_session(): %s", 1229 pam_strerror(sshpam_handle, sshpam_err)); 1230 } 1231 1232 } 1233 1234 int 1235 is_pam_session_open(void) 1236 { 1237 return sshpam_session_open; 1238 } 1239 1240 /* 1241 * Set a PAM environment string. We need to do this so that the session 1242 * modules can handle things like Kerberos/GSI credentials that appear 1243 * during the ssh authentication process. 1244 */ 1245 int 1246 do_pam_putenv(char *name, char *value) 1247 { 1248 int ret = 1; 1249 char *compound; 1250 size_t len; 1251 1252 len = strlen(name) + strlen(value) + 2; 1253 compound = xmalloc(len); 1254 1255 snprintf(compound, len, "%s=%s", name, value); 1256 ret = pam_putenv(sshpam_handle, compound); 1257 free(compound); 1258 1259 return (ret); 1260 } 1261 1262 char ** 1263 fetch_pam_child_environment(void) 1264 { 1265 return sshpam_env; 1266 } 1267 1268 char ** 1269 fetch_pam_environment(void) 1270 { 1271 return (pam_getenvlist(sshpam_handle)); 1272 } 1273 1274 void 1275 free_pam_environment(char **env) 1276 { 1277 char **envp; 1278 1279 if (env == NULL) 1280 return; 1281 1282 for (envp = env; *envp; envp++) 1283 free(*envp); 1284 free(env); 1285 } 1286 1287 /* 1288 * "Blind" conversation function for password authentication. Assumes that 1289 * echo-off prompts are for the password and stores messages for later 1290 * display. 1291 */ 1292 static int 1293 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1294 struct pam_response **resp, void *data) 1295 { 1296 struct pam_response *reply; 1297 int r, i; 1298 size_t len; 1299 1300 debug3("PAM: %s called with %d messages", __func__, n); 1301 1302 *resp = NULL; 1303 1304 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1305 return (PAM_CONV_ERR); 1306 1307 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1308 return (PAM_CONV_ERR); 1309 1310 for (i = 0; i < n; ++i) { 1311 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1312 case PAM_PROMPT_ECHO_OFF: 1313 if (sshpam_password == NULL) 1314 goto fail; 1315 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1316 goto fail; 1317 reply[i].resp_retcode = PAM_SUCCESS; 1318 break; 1319 case PAM_ERROR_MSG: 1320 case PAM_TEXT_INFO: 1321 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1322 if (len > 0) { 1323 if ((r = sshbuf_putf(loginmsg, "%s\n", 1324 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1325 fatal("%s: buffer error: %s", 1326 __func__, ssh_err(r)); 1327 } 1328 if ((reply[i].resp = strdup("")) == NULL) 1329 goto fail; 1330 reply[i].resp_retcode = PAM_SUCCESS; 1331 break; 1332 default: 1333 goto fail; 1334 } 1335 } 1336 *resp = reply; 1337 return (PAM_SUCCESS); 1338 1339 fail: 1340 for(i = 0; i < n; i++) { 1341 free(reply[i].resp); 1342 } 1343 free(reply); 1344 return (PAM_CONV_ERR); 1345 } 1346 1347 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1348 1349 /* 1350 * Attempt password authentication via PAM 1351 */ 1352 int 1353 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1354 { 1355 int flags = (options.permit_empty_passwd == 0 ? 1356 PAM_DISALLOW_NULL_AUTHTOK : 0); 1357 char *fake = NULL; 1358 1359 if (!options.use_pam || sshpam_handle == NULL) 1360 fatal("PAM: %s called when PAM disabled or failed to " 1361 "initialise.", __func__); 1362 1363 sshpam_password = password; 1364 sshpam_authctxt = authctxt; 1365 1366 /* 1367 * If the user logging in is invalid, or is root but is not permitted 1368 * by PermitRootLogin, use an invalid password to prevent leaking 1369 * information via timing (eg if the PAM config has a delay on fail). 1370 */ 1371 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1372 options.permit_root_login != PERMIT_YES)) 1373 sshpam_password = fake = fake_password(password); 1374 1375 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1376 (const void *)&passwd_conv); 1377 if (sshpam_err != PAM_SUCCESS) 1378 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1379 pam_strerror(sshpam_handle, sshpam_err)); 1380 1381 sshpam_err = pam_authenticate(sshpam_handle, flags); 1382 sshpam_password = NULL; 1383 free(fake); 1384 if (sshpam_err == PAM_MAXTRIES) 1385 sshpam_set_maxtries_reached(1); 1386 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1387 debug("PAM: password authentication accepted for %.100s", 1388 authctxt->user); 1389 return 1; 1390 } else { 1391 debug("PAM: password authentication failed for %.100s: %s", 1392 authctxt->valid ? authctxt->user : "an illegal user", 1393 pam_strerror(sshpam_handle, sshpam_err)); 1394 return 0; 1395 } 1396 } 1397 1398 int 1399 sshpam_get_maxtries_reached(void) 1400 { 1401 return sshpam_maxtries_reached; 1402 } 1403 1404 void 1405 sshpam_set_maxtries_reached(int reached) 1406 { 1407 if (reached == 0 || sshpam_maxtries_reached) 1408 return; 1409 sshpam_maxtries_reached = 1; 1410 options.password_authentication = 0; 1411 options.kbd_interactive_authentication = 0; 1412 } 1413 #endif /* USE_PAM */ 1414